Title: NiFeGa ferromagnetic shape memory alloys and magnetic properties of phase change thermal effects of Author: Yu Huajun Degree awarded by: University of Electronic Science and Technology Keywords: ferromagnetic shape memory alloy;; Ni-Fe-Ga;; martensite;; magnetic properties;; magnetocaloric effect Abstract:
Ferromagnetic shape memory alloys in recent years, studies have found a set of magnetic shape memory and magnetic field induced strain in one of the new smart materials, sensors and actuators are expected to become key components such as the material of choice. The Ni-Fe-Ga ferromagnetic shape memory alloys have magnetic anisotropy can be large and thermal processing performance, etc., the rich physical contents include: first, the alloy is Magnetic lifter ferromagnetic intermetallic compounds, it's hot parent phase with L2_1/B2 cubic structure, while the martensite phase modulation is usually a complex layer structure. Second, it is the thermoelastic martensitic transformation, the martensitic transformation characteristics and chemical composition of alloys by heat treatment and other effects. Third, the alloy with high saturation magnetization and large magnetic anisotropy constant. Therefore, the project has a very broad application prospects, and research scholars from various countries has gradually become one of the key material.
In this paper, arc melting and suction casting method of preparation of the Ni-Fe-Ga (-X) series alloys, a systematic study of Ni-Fe-Ga (-X) alloy microstructure, microstructure, martensitic change behavior and magnetic properties to study the chemical composition of the fourth alloying elements and heat treatment processes such as on the Ni-Fe-Ga alloy of impact. Improved preparation of Ni-Fe-Ga (-X) alloy method, attempted to improve the thermal effect of the magnetic alloy channels for Ni-Fe-Ga alloy lay the foundation for engineering applications.
The results show that the chemical composition of Ni-Fe-Ga alloy at room temperature and phase structure of very significant. Room temperature when Ni_ (73-x) Fe_xGa_ (27) series of alloys of Fe content from 18at% to 20at%, the alloy from the http://www.999magnet.com/products/131-magnetic-lifter martensitic phase transition into a single body with Austin. X-ray diffraction and TEM selected area electron diffraction revealed, Ni55Fe_ (18) Ga_ (27) alloy at room temperature monoclinic martensite phase modulation of the 14M structure. It also found that Ge, Al, Co and Cu alloying elements such as the Fourth of Ni-Fe-Ga alloy has an important impact on organizational structure. A certain amount of Ge element substitution Ni_ (56.5) Fe_ (17) Ga_ (26.5) in the alloy part of the group element, to make alloy martensitic at room temperature into Austin from the bulk phase; Co Add so Ni_ (56.5) Fe_ (17) Ga_ (26.5-z) Co_z alloy microstructure at room temperature from the martensite phase and γ phase formed, with the Co content increases, γ-phase increase in the number size increases; Ni_ (56.5) Fe_ (17) Ga_ (26.5-x) Al_x and Ni_ (56.5-z) Fe_ (17) Ga_ (26.5) Cu_z not only by the martensitic alloy or austenitic form, and there is a variety of phase structures.
Ni-Fe-Ga martensitic alloy chemical composition and behavior of alloying elements is very sensitive to the fourth. In Ni_ (73-x) Fe_xGa_ (27) series alloys, the martensitic transformation temperature M_s the Ni_ (55) Fe_ (18) Ga_ (27) alloy decreased to 31.7 ℃ Ni_ (52.5) Fe_ (20.5) Ga_ (27) alloy -118.3 ℃; in Ni_ (73.5-y) Fe_yGa_ (26.5) series alloys, M_s the Ni_ (56.5) Fe_ (17) Ga_ (26.5) alloy decreased to 108.9 ℃ Ni_ (54.5) Fe_ (19) Ga_ (26.5) alloy of 28.1 ℃. Fixed Fe / Ga ratio is constant, Ni-Fe-Ga alloys with martensitic transformation temperature increases linearly with Ni content increased, specifically, in Ni_ (56.5 + z) Fe_ (17) Ga_ (26.5) series alloys, M_s 54.5at% from the Ni content increased when the Ni content of 39.6 ℃ to 58.5at% when 139.9 ℃. Ge elements found in both the alternative alloys of Ni or Fe, or Ga, are significantly lower temperature martensitic alloys, Ge substitution Ni martensitic phase transition temperature decreased the fastest, Ge, followed by alternative Fe, Ge Ga substitution slowest: The Co substitution Ni-Fe-Ga alloys Ga atoms significantly improved the alloy's martensitic transformation temperature. Preliminary view should be from the valence electron concentration, the size factor and a combination of factors such as degree of order study the role of martensitic transformation temperature.
Heat treatment process is also affected Ni-Fe-Ga alloy martensitic transformation behavior is one important factor. The results show that the martensitic transformation temperature decreased significantly compared with unannealed, and then rises with increasing annealing temperature; and annealing time, the alloy of the reverse martensitic transformation temperature gradually increased, Ma bulk transition temperature first increases, until the annealing time 5 h, then the extension of the annealing time decreased. The order degree of parent phase alloy, crystal defects and internal stress such as heat treatment process is affecting the temperature of the martensitic alloy may cause.
In the strong magnetic field magnetization, Ni-Fe-Ga (-X) alloy exhibits a common feature, namely the high-temperature austenitic alloy was easily magnetized, easily saturated; low temperature martensite phase shows hard magnetization, saturation Slow features. In Ni_ (56.5-x) Fe_ (17) Ga_ (26.5) Ge_x (x = 0,0.5,1.0,2.0) alloy, alloy and the saturation magnetization of the magnetic crystal anisotropy constant, along with the increase of Ge content decreases; Curie temperature increases with the Ge atom concentration decrease. By isothermal magnetization curves of the Ni-Fe-Ga (-X) alloy magnetocaloric effect. The results showed that, Ni_ (55) Fe_ (18) Ga_ (27) alloy is not very high maximum magnetic entropy change in the 50 kOe magnetic field, the maximum value of only -2.0J/kgK, difficult as magnetic refrigeration technology magnetic refrigerant. Despite the addition of Al and Ge alloy increases the maximum magnetic entropy change, but still can not achieve the requirements of magnetic refrigeration technology. However, through the study found that changing the alloy composition, magnetic atoms alloying is to improve the magnetocaloric effect may be an effective way.
Room temperature compression test results show that, Ge elements added to improve the NiFeGa alloy compressive strength, improve the elongation of the alloy. (Ni_ (56.5) Fe_ (17) Ga_ (26.5)) _ (100-x) Ge_x compressive strength and elongation of alloys with Ge content increases. Degree Year: 2009
2011年9月28日星期三
chemical preparation of diluted magnetic semiconductors and magnetic properties of the structure
Title: chemical preparation of diluted magnetic semiconductors and magnetic properties of the structure Author: Left Aru Degree-granting units: Lanzhou University Keywords: ZnO;; SnO_2;; Room temperature ferromagnetism;; Bound magnetic polaron Abstract:
Since the discovery of spin-related phenomena and many of its great potential usefulness, spintronics research in the world has been widely carried out. Which is considered the next generation of magnetic semiconductors using electron spin degree Magnetic lifter of freedom the main material manufacturing microelectronic components, have a good prospect.
In recent years, many research groups have prepared a room temperature ferromagnetic diluted magnetic semiconductors, dilute magnetic semiconductors, ferromagnetic origin there is considerable controversy. The theory of magnetic sources are mainly divided into two parts: one is induced by the carrier ferromagnetic exchange coupling, such as the RKKY exchange interaction. Another view of the defects in the sample, representative of the bound polaron (BMP) model.
In this article, we systematically studied the Co-SnO_2 film and powder, Tb-In_2O_3 films and Co-ZnO nanorod arrays of micro-structure, optical properties, electrical and magnetic properties of the main results obtained are as follows:
1. Sol - gel preparation of the Co-SnO_2 powder and film samples
(1) Co-SnO_2 powder and film samples were obtained pure rutile ore structure. And as Co doping increased, the sample grain size decreases, http://www.999magnet.com/products/131-magnetic-lifter indicating that Co ~ (2 +) doping inhibited the grain growth.
(2) High-resolution electron microscopy showed: the rules and did not sample the lattice distortion or deformation, the selected area electron diffraction (SAED) show that the samples of rutile phase SnO_2, and no impurity phase. X-ray photoelectron spectroscopy studies have shown that the valence state of elements of Co 2 +. The resulting Co ~ (2 +) into the SnO_2 lattice.
(3) has been at room temperature ferromagnetism of Co-SnO_2 powder and film samples, nuclear magnetic resonance (NMR) studies have shown that the magnetic sample is intrinsic to. In the amount of different Co-doped samples, each Co moment with the doping amount increases. Explanation for this phenomenon: the increase in the amount of doping with Co, Co ions decreases the distance between, Co ions by oxygen ions between the antiferromagnetic super-exchange interaction, resulting in the decrease of magnetic moment per Co .
(4) with Sn_ (1-x) Co_xO_2 sol spin-coating on Si (111) and Si (amorphous) films were prepared on the substrate. Studies have shown that, Si (111) substrate is better than the sample crystal Si (amorphous) substrate, while also significantly stronger than the magnetic Si (amorphous) substrates, indicating that closely related to magnetic and crystalline quality .
(5) The chemical resistance of coated samples large magnetic origin can not be carrier-induced exchange interaction model, and models required to explain the BMP. In order to verify whether the BMP model for Co-SnO_2 system, first samples annealed in oxidizing environments, magnetic disappear. The samples were then annealed in a vacuum environment, magnetic and reproduce. The results demonstrate that oxygen vacancies on the Co_xSn_ (1-x) O_2 ferromagnetic system has an important impact, confirmed the BMP model for Co_xSn_ (1-x) O_2 thin film system.
2 sol - gel preparation diluted magnetic semiconductor (In_ (1-xy) Tb_xSn_y) _2O_3 film
(1) different doping (In_ (0.9-x) Tb_xSn_ (0.1)) _2O_3 and (In_ (0.99-y) Tb_ (0.01) Sn_y) _2O_3 film samples were pure cubic structure.
(2) Magnetic studies show that: For a different amount of Tb-doped samples, with the increase in the amount of Tb-doped, Tb magnetic moment of each sample first increased. When the doping amount of 1%, the moment the largest 8.2μ_B/Tb. After the sample moments with Tb doping increases. Electrical studies have shown that: With the increase in the amount of Tb-doped sample the conductivity first increases and then decreases, the magnetic moment of Tb-doped trends and the relationship between the amount of the same, indicating that the magnetic moment of the sample and its conductivity on.
(3) for different amount of Sn-doped samples increase with Sn doping, the sample magnetic moment per Tb first increases and then decreases. Conductivity of the sample doped with Sn and the relationship between the magnetic moment per Tb doped with Sn relationship trend. As the conductivity is proportional to the carrier concentration, indicating that the sample moments and the carrier concentration. Therefore, the system can be the source of the magnetic carrier induced exchange interaction (RKKY) to explain.
3 Hydrothermal diluted magnetic semiconductors Zn_ (1-x) Co_xO nanorods
(1) on Si substrate prepared by the success of the ZnO and Zn_ (1-x) Co_xO nanowire arrays, all of the nanowires are perpendicular to the substrate. As the reaction time and Zn ~ (2 +) ion concentration in solution increases, the diameter and length of the nanorods increases. Nanorods diameter 50 ~ 250nm, a length of 100nm ~ 3μm.
(2) ZnO and Zn_ (1-x) Co_xO have wurtzite structure and have a good optimization approach. Zn_ (0.8) Co_ (0.2) O nanorods with room temperature ferromagnetism.
(3) ZnO, ZnO_ (0.9) Co_ (0.1) O and ZnO_ (0.8) Co_ (0.2) O nanorod emission spectrum at the 391nm band gap shows a strong light, and 613nm show a clear and strong at the red emission peak. Doped, Co-ZnO nanorods red luminescence peak intensity decreased, the gap may be reduced by the doping amount of oxygen due. The peaks rarely reported in the literature. Degree Year: 2009
Since the discovery of spin-related phenomena and many of its great potential usefulness, spintronics research in the world has been widely carried out. Which is considered the next generation of magnetic semiconductors using electron spin degree Magnetic lifter of freedom the main material manufacturing microelectronic components, have a good prospect.
In recent years, many research groups have prepared a room temperature ferromagnetic diluted magnetic semiconductors, dilute magnetic semiconductors, ferromagnetic origin there is considerable controversy. The theory of magnetic sources are mainly divided into two parts: one is induced by the carrier ferromagnetic exchange coupling, such as the RKKY exchange interaction. Another view of the defects in the sample, representative of the bound polaron (BMP) model.
In this article, we systematically studied the Co-SnO_2 film and powder, Tb-In_2O_3 films and Co-ZnO nanorod arrays of micro-structure, optical properties, electrical and magnetic properties of the main results obtained are as follows:
1. Sol - gel preparation of the Co-SnO_2 powder and film samples
(1) Co-SnO_2 powder and film samples were obtained pure rutile ore structure. And as Co doping increased, the sample grain size decreases, http://www.999magnet.com/products/131-magnetic-lifter indicating that Co ~ (2 +) doping inhibited the grain growth.
(2) High-resolution electron microscopy showed: the rules and did not sample the lattice distortion or deformation, the selected area electron diffraction (SAED) show that the samples of rutile phase SnO_2, and no impurity phase. X-ray photoelectron spectroscopy studies have shown that the valence state of elements of Co 2 +. The resulting Co ~ (2 +) into the SnO_2 lattice.
(3) has been at room temperature ferromagnetism of Co-SnO_2 powder and film samples, nuclear magnetic resonance (NMR) studies have shown that the magnetic sample is intrinsic to. In the amount of different Co-doped samples, each Co moment with the doping amount increases. Explanation for this phenomenon: the increase in the amount of doping with Co, Co ions decreases the distance between, Co ions by oxygen ions between the antiferromagnetic super-exchange interaction, resulting in the decrease of magnetic moment per Co .
(4) with Sn_ (1-x) Co_xO_2 sol spin-coating on Si (111) and Si (amorphous) films were prepared on the substrate. Studies have shown that, Si (111) substrate is better than the sample crystal Si (amorphous) substrate, while also significantly stronger than the magnetic Si (amorphous) substrates, indicating that closely related to magnetic and crystalline quality .
(5) The chemical resistance of coated samples large magnetic origin can not be carrier-induced exchange interaction model, and models required to explain the BMP. In order to verify whether the BMP model for Co-SnO_2 system, first samples annealed in oxidizing environments, magnetic disappear. The samples were then annealed in a vacuum environment, magnetic and reproduce. The results demonstrate that oxygen vacancies on the Co_xSn_ (1-x) O_2 ferromagnetic system has an important impact, confirmed the BMP model for Co_xSn_ (1-x) O_2 thin film system.
2 sol - gel preparation diluted magnetic semiconductor (In_ (1-xy) Tb_xSn_y) _2O_3 film
(1) different doping (In_ (0.9-x) Tb_xSn_ (0.1)) _2O_3 and (In_ (0.99-y) Tb_ (0.01) Sn_y) _2O_3 film samples were pure cubic structure.
(2) Magnetic studies show that: For a different amount of Tb-doped samples, with the increase in the amount of Tb-doped, Tb magnetic moment of each sample first increased. When the doping amount of 1%, the moment the largest 8.2μ_B/Tb. After the sample moments with Tb doping increases. Electrical studies have shown that: With the increase in the amount of Tb-doped sample the conductivity first increases and then decreases, the magnetic moment of Tb-doped trends and the relationship between the amount of the same, indicating that the magnetic moment of the sample and its conductivity on.
(3) for different amount of Sn-doped samples increase with Sn doping, the sample magnetic moment per Tb first increases and then decreases. Conductivity of the sample doped with Sn and the relationship between the magnetic moment per Tb doped with Sn relationship trend. As the conductivity is proportional to the carrier concentration, indicating that the sample moments and the carrier concentration. Therefore, the system can be the source of the magnetic carrier induced exchange interaction (RKKY) to explain.
3 Hydrothermal diluted magnetic semiconductors Zn_ (1-x) Co_xO nanorods
(1) on Si substrate prepared by the success of the ZnO and Zn_ (1-x) Co_xO nanowire arrays, all of the nanowires are perpendicular to the substrate. As the reaction time and Zn ~ (2 +) ion concentration in solution increases, the diameter and length of the nanorods increases. Nanorods diameter 50 ~ 250nm, a length of 100nm ~ 3μm.
(2) ZnO and Zn_ (1-x) Co_xO have wurtzite structure and have a good optimization approach. Zn_ (0.8) Co_ (0.2) O nanorods with room temperature ferromagnetism.
(3) ZnO, ZnO_ (0.9) Co_ (0.1) O and ZnO_ (0.8) Co_ (0.2) O nanorod emission spectrum at the 391nm band gap shows a strong light, and 613nm show a clear and strong at the red emission peak. Doped, Co-ZnO nanorods red luminescence peak intensity decreased, the gap may be reduced by the doping amount of oxygen due. The peaks rarely reported in the literature. Degree Year: 2009
Magnetic resonance imaging method to eliminate motion artifacts
Title: Magnetic resonance imaging method to eliminate motion artifacts Author: Tan Pei Degree awarded: China University of Science and Technology Keywords: magnetic resonance imaging;; motion artifacts;; motion estimation;; image reconstruction;; PROPELLER;; grid Abstract:
MRI (Magnetic Resonance Imaging, MRI) based on in vivo nuclear magnetic resonance in the static magnetic field within the imaging characteristics of the signal with high image resolution, more imaging parameters, the fault can be in any direction, the human body without ionizing radiation damage, etc. significant advantages, as the most neodymium magnets advanced medical imaging methods in clinical and scientific research has been more widely used.
Magnetic resonance imaging process, the patient's autonomy and physical movement is often difficult to avoid, it will undermine the data collection process and the formation of the image into artifacts, allowing physicians to make the correct diagnosis difficult. Uncertainty due to movement and movement is difficult to obtain a priori knowledge of the motion artifact correction also very difficult to seriously affect and impede the development of magnetic resonance imaging technology and applications. Therefore, to eliminate motion artifacts in magnetic resonance methods of research, attracted wide attention from foreign scholars, is the current medical imaging field of research focus, progress of any research in this area will have magnetic resonance imaging technology and applications from to the active role.
This familiar and master in magnetic resonance imaging based on the principles and techniques of motion artifacts in-depth research, analysis of motion artifacts on magnetic resonance imaging in the process of data collection and final imaging these two important aspects of impact, proposed several artifacts in image reconstruction algorithms and post-processing correction algorithms for magnetic resonance imaging motion artifact can be effectively suppressed. This study from the analysis of a kind to eliminate motion artifacts in functional imaging algorithm PROPELLER data acquisition to start, right in the application on the basis of implementing the algorithm proposed can improve the speed of the circular grid algorithms, and grid algorithm has been improved to further improve the imaging speed and quality of the algorithm, then presents several practical value of the magnetic resonance image post-processing correction algorithm, on which the translational motion and rotational motion http://www.chinamagnets.biz/Neodymium/Ball-Neodymium-Magnets.php artifact correction, to improve the final image quality.
To sum up, this completed the following distinctive research work:
1) PROPELLER imaging algorithm to improve data collection, proposed a new algorithm based on circular grid. PROPELLER magnetic resonance imaging is a new algorithm, it by changing the way data acquisition and imaging reconstruction step in the reconstruction process by adding correction algorithms, which can more effectively eliminate motion artifacts. Based on the analysis of the algorithm to achieve its basic principles and steps, based on the correction algorithm for the rotation which takes many shortcomings, propose a new circular grid algorithm, grid and interpolation operations to reduce the number of times, improved estimation of rotation parameters PROPELLER accuracy and the speed of the algorithm. Improved PROPELLER imaging data acquisition scanning algorithm not only can effectively inhibit the formation process of motion artifacts, and fast, high image quality.
2) proposed two improved sampling-based data grid PROPELLER imaging algorithm. PROPELLER imaging grid is an important step in the algorithm, the imaging results of the final plays a decisive role in improvement of the meshing algorithm, mesh-based imaging can significantly improve the speed and quality. Algorithms for the Voronoi grid mesh size density compensation value as a function of closure and proposed the establishment of the grid method, the grid-based imaging algorithm has been improved. Algorithm II to a large matrix of grid-based algorithm not only improves the quality of the grid, but also the use of matrix operations to speed up the computing process.
3) for two magnetic resonance translational motion artifact correction algorithms. First, a new algorithm based directly on the artifact zone correction algorithm. It is based on artifacts zone data to establish the constraint equations translation exercise, using a differential evolution algorithm for optimization of the value function, shift to get exercise, to achieve translational motion artifact correction. Algorithm based on two non-sports related, respectively, x and y direction translational motion processing. Fourier projection algorithm, to get x-amount of the entire pixel motion pan, quickly correct the x direction of motion artifacts; parameters based on polynomial fitting, correct use of genetic algorithms and x-y direction, the direction of the sub-pixel motion artifacts. Experimental results show that two algorithms of translational motion artifacts can play a better inhibitory effect.
4) rapid scanning sequence for the MRI, we propose a rotational motion artifact correction algorithms. Algorithm includes the following new ideas: the uniformly rectangular K-space data, the idea of a new striping plan; given new similarity measure formula used to estimate the rotation parameters; proposed compensation Hermitian conjugate algorithm, after correction for the position to compensate for uneven data space; design a fast grid-based algorithm, the process of accelerated computing. Experimental results show that the algorithm can effectively correct rotation motion artifacts, and by the signal to noise ratio is small, has a certain robustness. Degree Year: 2009
MRI (Magnetic Resonance Imaging, MRI) based on in vivo nuclear magnetic resonance in the static magnetic field within the imaging characteristics of the signal with high image resolution, more imaging parameters, the fault can be in any direction, the human body without ionizing radiation damage, etc. significant advantages, as the most neodymium magnets advanced medical imaging methods in clinical and scientific research has been more widely used.
Magnetic resonance imaging process, the patient's autonomy and physical movement is often difficult to avoid, it will undermine the data collection process and the formation of the image into artifacts, allowing physicians to make the correct diagnosis difficult. Uncertainty due to movement and movement is difficult to obtain a priori knowledge of the motion artifact correction also very difficult to seriously affect and impede the development of magnetic resonance imaging technology and applications. Therefore, to eliminate motion artifacts in magnetic resonance methods of research, attracted wide attention from foreign scholars, is the current medical imaging field of research focus, progress of any research in this area will have magnetic resonance imaging technology and applications from to the active role.
This familiar and master in magnetic resonance imaging based on the principles and techniques of motion artifacts in-depth research, analysis of motion artifacts on magnetic resonance imaging in the process of data collection and final imaging these two important aspects of impact, proposed several artifacts in image reconstruction algorithms and post-processing correction algorithms for magnetic resonance imaging motion artifact can be effectively suppressed. This study from the analysis of a kind to eliminate motion artifacts in functional imaging algorithm PROPELLER data acquisition to start, right in the application on the basis of implementing the algorithm proposed can improve the speed of the circular grid algorithms, and grid algorithm has been improved to further improve the imaging speed and quality of the algorithm, then presents several practical value of the magnetic resonance image post-processing correction algorithm, on which the translational motion and rotational motion http://www.chinamagnets.biz/Neodymium/Ball-Neodymium-Magnets.php artifact correction, to improve the final image quality.
To sum up, this completed the following distinctive research work:
1) PROPELLER imaging algorithm to improve data collection, proposed a new algorithm based on circular grid. PROPELLER magnetic resonance imaging is a new algorithm, it by changing the way data acquisition and imaging reconstruction step in the reconstruction process by adding correction algorithms, which can more effectively eliminate motion artifacts. Based on the analysis of the algorithm to achieve its basic principles and steps, based on the correction algorithm for the rotation which takes many shortcomings, propose a new circular grid algorithm, grid and interpolation operations to reduce the number of times, improved estimation of rotation parameters PROPELLER accuracy and the speed of the algorithm. Improved PROPELLER imaging data acquisition scanning algorithm not only can effectively inhibit the formation process of motion artifacts, and fast, high image quality.
2) proposed two improved sampling-based data grid PROPELLER imaging algorithm. PROPELLER imaging grid is an important step in the algorithm, the imaging results of the final plays a decisive role in improvement of the meshing algorithm, mesh-based imaging can significantly improve the speed and quality. Algorithms for the Voronoi grid mesh size density compensation value as a function of closure and proposed the establishment of the grid method, the grid-based imaging algorithm has been improved. Algorithm II to a large matrix of grid-based algorithm not only improves the quality of the grid, but also the use of matrix operations to speed up the computing process.
3) for two magnetic resonance translational motion artifact correction algorithms. First, a new algorithm based directly on the artifact zone correction algorithm. It is based on artifacts zone data to establish the constraint equations translation exercise, using a differential evolution algorithm for optimization of the value function, shift to get exercise, to achieve translational motion artifact correction. Algorithm based on two non-sports related, respectively, x and y direction translational motion processing. Fourier projection algorithm, to get x-amount of the entire pixel motion pan, quickly correct the x direction of motion artifacts; parameters based on polynomial fitting, correct use of genetic algorithms and x-y direction, the direction of the sub-pixel motion artifacts. Experimental results show that two algorithms of translational motion artifacts can play a better inhibitory effect.
4) rapid scanning sequence for the MRI, we propose a rotational motion artifact correction algorithms. Algorithm includes the following new ideas: the uniformly rectangular K-space data, the idea of a new striping plan; given new similarity measure formula used to estimate the rotation parameters; proposed compensation Hermitian conjugate algorithm, after correction for the position to compensate for uneven data space; design a fast grid-based algorithm, the process of accelerated computing. Experimental results show that the algorithm can effectively correct rotation motion artifacts, and by the signal to noise ratio is small, has a certain robustness. Degree Year: 2009
Acupuncture for mild cognitive impairment leukoaraiosis impact of functional magnetic resonance
Title: Acupuncture for mild cognitive impairment leukoaraiosis impact of functional magnetic resonance Author: Hou Xiaobing Degree-granting units: Beijing University of Chinese Medicine Keywords: Acupuncture;; leukoaraiosis;; mild cognitive impairment;; functional magnetic resonance imaging;; magnetic resonance spectroscopy Abstract:
Vascular cognitive impairment refers to vascular risk factors lead to a variety of levels and types of cognitive impairment, covering vascular mild cognitive impairment, vascular dementia and mixed dementia. Early detection, early diagnosis, early intervention vascular Neodymium Magnets mild cognitive impairment can prevent or delay the occurrence and progress of dementia, dementia This lack of effective and economical treatment today, has an extremely important social, economic and medical value.
Mild cognitive impairment leading to vascular heterogeneity factors, including leukoaraiosis, cerebral arteriosclerosis, stenosis, cerebral infarction, cerebral hemorrhage, hypertension, diabetes and so on. Magnetic resonance technology, leukoaraiosis found in the general prevalence of older people, which amounts to 49.7%, its prevalence increased with increasing age, more than 80 years of age is almost 100%. Leukoaraiosis more than just a pathological image changes, it is important that the clinical manifestations were cognitive impairment, cognitive impairment so both imaging and pathological changes of leukoaraiosis on a mild vascular cognitive barriers to a good starting point.
Acupuncture is the treatment of dementia, a more effective method, clinical focusing mostly in a variety of neuropsychological scale evaluation of the efficacy of acupuncture, not from the cognitive point of view of neuroimaging to explore the mechanism of acupuncture and efficacy of objective criteria. Functional magnetic resonance technology is an important class of medical data visualization technology, which can function in the human brain and objective information visualization display. Thus, functional magnetic resonance technology to study acupuncture intervention mechanism of action of mild cognitive impairment and efficacy of objective criteria providing advanced methods and means.
In this experiment, mild cognitive impairment as leukoaraiosis study, functional magnetic resonance imaging as a research tool, refer to the actual clinical situation, long-range acupuncture intervention, through neuropsychological evaluation of leukoaraiosis scale mild cognitive impairment The clinical changes observed on this basis before and after acupuncture leukoaraiosis mild cognitive impairment of brain function and brain MRI changes in neurotransmitters, acupuncture http://www.everbeenmagnet.com/en/products/110-sintered-neodymium-magnets
intervention to explore the mechanism of mild cognitive impairment and efficacy of the objective of standards.
Papers, including literature review and clinical studies two parts.
Literature Review section
Summarizes the acupuncture treatment of vascular cognitive impairment ancient literature on the clinical and basic research in relevant content, reviewed brain magnetic resonance imaging in mild cognitive impairment and application of acupuncture research, analysis of domestic and foreign Research and problems, proposed future development.
Part of clinical trials
Acupuncture for mild cognitive impairment leukoaraiosis functional magnetic resonance effects. Mild cognitive impairment observed leukoaraiosis acupuncture intervention before and after the fMRI brain neurotransmitter changes and the situation.
Into LAMCI subjects in 23 cases, normal subjects (control group) in 13 cases. LAMCI were tested further for the acupuncture group of 10 patients stratified with the natural process of group 13 cases, the acupuncture group treatment for 3 months, the natural process of group dynamics for 3 months, into the group that day, three months after treatment, neuropsychological evaluation , functional magnetic resonance imaging and spectroscopy MRI; the control group into the group the same day as neuropsychological assessment, functional magnetic resonance imaging and spectroscopy MRI. MMSE and neuropsychological evaluation for the MoCA evaluation, MRI spectroscopy NAA / Cr, Cho / Cr, MI / Cr.
Results:
1. Cingulate gyrus in the back, LAMCI subjects and normal subjects of NAA / Cr, Cho / Cr, MI / Cr was no significant difference;
(2) to match the age correction factors, the selected eight cases LAMCI were tested with normal subjects comparison of neurotransmitter re-found two groups of NAA / Cr, Cho / Cr was no significant difference, LAMCI subjects group MI / Cr increased significantly, the two groups were significantly different;
3 of 5 patients LAMCI were tested acupuncture intervention for three months, before acupuncture abnormal neuropsychological score, neuropsychological score after acupuncture normal. Acupuncture intervention group and the natural process of group LAMCI were tested between NAA / Cr, Cho / Cr, MI / Cr was no significant difference;
4 hearing before acupuncture music tasks activated brain areas including the temporal lobe of the superior temporal gyrus (BA22), temporal gyrus (BA21), temporal poles (BA38); frontal somatosensory cortex (BA1) and premotor cortex (BA6), acupuncture activates the brain's temporal lobe, including superior temporal gyrus (BA22); the amount of orbital frontal lobe (BA11), frontal pole region (BA10), frontal lobe was covered. Activated brain areas are activated before acupuncture was significantly less than the area.
Conclusion:
1. Leukoaraiosis mild cognitive impairment damaged brain functional areas involved in frontal temporal lobe, the performance of tasks for the implementation of the temporal lobe auditory cortex activation increased, the prefrontal cortex is not activated. Functional magnetic resonance imaging diagnosis for mild cognitive impairment, to determine efficacy and the mechanism of acupuncture provides a visual basis.
2. Leukoaraiosis cingulate mild cognitive impairment occurred at neurotransmitter changes, the performance of MI / Cr ratio increased, the disease may be one of objective diagnostic criteria.
3. Acupuncture can be used as leukoaraiosis mild cognitive impairment is one of effective interventions to reduce the activation of brain areas, to improve the task stimulus processing efficiency, but in order to affect the brain neurotransmitter changes take longer to intervention. Degree Year: 2009
Vascular cognitive impairment refers to vascular risk factors lead to a variety of levels and types of cognitive impairment, covering vascular mild cognitive impairment, vascular dementia and mixed dementia. Early detection, early diagnosis, early intervention vascular Neodymium Magnets mild cognitive impairment can prevent or delay the occurrence and progress of dementia, dementia This lack of effective and economical treatment today, has an extremely important social, economic and medical value.
Mild cognitive impairment leading to vascular heterogeneity factors, including leukoaraiosis, cerebral arteriosclerosis, stenosis, cerebral infarction, cerebral hemorrhage, hypertension, diabetes and so on. Magnetic resonance technology, leukoaraiosis found in the general prevalence of older people, which amounts to 49.7%, its prevalence increased with increasing age, more than 80 years of age is almost 100%. Leukoaraiosis more than just a pathological image changes, it is important that the clinical manifestations were cognitive impairment, cognitive impairment so both imaging and pathological changes of leukoaraiosis on a mild vascular cognitive barriers to a good starting point.
Acupuncture is the treatment of dementia, a more effective method, clinical focusing mostly in a variety of neuropsychological scale evaluation of the efficacy of acupuncture, not from the cognitive point of view of neuroimaging to explore the mechanism of acupuncture and efficacy of objective criteria. Functional magnetic resonance technology is an important class of medical data visualization technology, which can function in the human brain and objective information visualization display. Thus, functional magnetic resonance technology to study acupuncture intervention mechanism of action of mild cognitive impairment and efficacy of objective criteria providing advanced methods and means.
In this experiment, mild cognitive impairment as leukoaraiosis study, functional magnetic resonance imaging as a research tool, refer to the actual clinical situation, long-range acupuncture intervention, through neuropsychological evaluation of leukoaraiosis scale mild cognitive impairment The clinical changes observed on this basis before and after acupuncture leukoaraiosis mild cognitive impairment of brain function and brain MRI changes in neurotransmitters, acupuncture http://www.everbeenmagnet.com/en/products/110-sintered-neodymium-magnets
intervention to explore the mechanism of mild cognitive impairment and efficacy of the objective of standards.
Papers, including literature review and clinical studies two parts.
Literature Review section
Summarizes the acupuncture treatment of vascular cognitive impairment ancient literature on the clinical and basic research in relevant content, reviewed brain magnetic resonance imaging in mild cognitive impairment and application of acupuncture research, analysis of domestic and foreign Research and problems, proposed future development.
Part of clinical trials
Acupuncture for mild cognitive impairment leukoaraiosis functional magnetic resonance effects. Mild cognitive impairment observed leukoaraiosis acupuncture intervention before and after the fMRI brain neurotransmitter changes and the situation.
Into LAMCI subjects in 23 cases, normal subjects (control group) in 13 cases. LAMCI were tested further for the acupuncture group of 10 patients stratified with the natural process of group 13 cases, the acupuncture group treatment for 3 months, the natural process of group dynamics for 3 months, into the group that day, three months after treatment, neuropsychological evaluation , functional magnetic resonance imaging and spectroscopy MRI; the control group into the group the same day as neuropsychological assessment, functional magnetic resonance imaging and spectroscopy MRI. MMSE and neuropsychological evaluation for the MoCA evaluation, MRI spectroscopy NAA / Cr, Cho / Cr, MI / Cr.
Results:
1. Cingulate gyrus in the back, LAMCI subjects and normal subjects of NAA / Cr, Cho / Cr, MI / Cr was no significant difference;
(2) to match the age correction factors, the selected eight cases LAMCI were tested with normal subjects comparison of neurotransmitter re-found two groups of NAA / Cr, Cho / Cr was no significant difference, LAMCI subjects group MI / Cr increased significantly, the two groups were significantly different;
3 of 5 patients LAMCI were tested acupuncture intervention for three months, before acupuncture abnormal neuropsychological score, neuropsychological score after acupuncture normal. Acupuncture intervention group and the natural process of group LAMCI were tested between NAA / Cr, Cho / Cr, MI / Cr was no significant difference;
4 hearing before acupuncture music tasks activated brain areas including the temporal lobe of the superior temporal gyrus (BA22), temporal gyrus (BA21), temporal poles (BA38); frontal somatosensory cortex (BA1) and premotor cortex (BA6), acupuncture activates the brain's temporal lobe, including superior temporal gyrus (BA22); the amount of orbital frontal lobe (BA11), frontal pole region (BA10), frontal lobe was covered. Activated brain areas are activated before acupuncture was significantly less than the area.
Conclusion:
1. Leukoaraiosis mild cognitive impairment damaged brain functional areas involved in frontal temporal lobe, the performance of tasks for the implementation of the temporal lobe auditory cortex activation increased, the prefrontal cortex is not activated. Functional magnetic resonance imaging diagnosis for mild cognitive impairment, to determine efficacy and the mechanism of acupuncture provides a visual basis.
2. Leukoaraiosis cingulate mild cognitive impairment occurred at neurotransmitter changes, the performance of MI / Cr ratio increased, the disease may be one of objective diagnostic criteria.
3. Acupuncture can be used as leukoaraiosis mild cognitive impairment is one of effective interventions to reduce the activation of brain areas, to improve the task stimulus processing efficiency, but in order to affect the brain neurotransmitter changes take longer to intervention. Degree Year: 2009
126kV high-voltage vacuum circuit breaker synchronous permanent magnetic actuator and control
Title: 126kV high-voltage vacuum circuit breaker synchronous permanent magnetic actuator and control technology research Author: Ma Shaohua Degree-granting units: Shenyang University Keywords: vacuum circuit breaker;; pressure;; magnetic actuator;; synchronization Abstract:
Permanent magnet actuator structure is simple, spare parts, high reliability, operating life long, action dispersion is small, very suitable equipped with vacuum circuit breakers, is the only technology able to synchronize the control actuator, has been widely used in medium voltage vacuum circuit breaker. Although the market for high-voltage level of permanent magnetic actuator has been very concerned about, but have not yet seen the product at home and Neodymium Magnets abroad reported. To meet the development of high-voltage vacuum circuit breakers need to fill the high-voltage magnetic actuator of the international space, this study used simultaneously with making and breaking capabilities of 126kV high-voltage vacuum circuit breaker magnetic actuator.
In this paper, virtual prototyping technology, the use of Ansoft Maxwell 3D/2D simulation software for magnetic actuator electromagnetic system of static and dynamic properties were calculated. Through theoretical analysis and comparison, about the use of primary and secondary coils in series excitation field winding ways to improve the effect, so that the movement of moving core in the long journey to get enough of the next operation is always successful. Excitation method proposed in this paper significantly improves the characteristics of permanent magnet actuator, so that sub-gate and the closing time, energy storage capacitors to reduce energy consumption, reduce peak current excitation coil, sub-gate and the closing velocity increases, moving core impact collisions slow down when closed, not only to meet the 126kV high voltage vacuum interrupter-off requirements, but also to improve the medium-voltage performance of permanent magnetic actuator provides a good solution.
To meet the synchronization accuracy and reduce the dispersion of the action, the need for permanent magnetic actuator of the operating time to compensate. In this paper, statistical learning theory, a least squares support vector machines based on permanent magnet actuator movement time prediction model. Using cross validation and grid search method to determine the core functions and support vector, then get a vector with only minority support for the prediction function expression. The simulation results show that the validation data, least squares support vector machine model has a strong generalization (forecasting) ability to obtain a smaller fitting error in the forecast http://www.everbeenmagnet.com/en/products/110-sintered-neodymium-magnets on the basis of minimum error, maximum error is less than ± 0.2ms , computational complexity is small, easy-to-line programming.
Electrical circuit breaker synchronous control is the development of intelligent direction and cutting-edge issues. At present, the synchronization technology has turned into the practical stage, but not easy to precisely synchronized with the signal breaking, breaking synchronization technology is still in the theoretical preparation. In this paper, the general expression of short-circuit current starting, parameter identification and adaptive arithmetic recursive method with the DC component of the transient short-circuit current decay for analysis, a mathematical model for forecasting short-circuit current zero. Analyzed using Matlab software, sampling rate, A / D converter quantization precision and signal to noise ratio of short-circuit current measurement circuit waveform analysis accuracy. After comprehensive comparison, made with 7 / 8 wave arithmetic recursive formula predict changes in properties of short-circuit current, with an estimated zero-crossing. The projections presented in this paper short-circuit current of 7 / 8 wave count recursive formula, the only 12bit A / D converter, each fundamental cycle, the sampling rate and 32 times more than 60dB signal to noise ratio of the circuit, easy hardware implementation and software programming.
Field programmable gate array developed in recent years as a general-purpose user-programmable devices, it has both the gate array of high integration and versatility, there are user-programmable flexibility, high speed, low power consumption, general strong, especially for complex systems design. This design uses a microcontroller and FPGA combination of parallel processing, design of permanent magnet synchronous actuator intelligent control system. The use of SCM measurement and control functions, the FPGA as an embedded microcontroller chip, designed to analyze the changes in short-circuit current characteristics, improve the synchronization of real-time and reliability. Degree Year: 2009
Permanent magnet actuator structure is simple, spare parts, high reliability, operating life long, action dispersion is small, very suitable equipped with vacuum circuit breakers, is the only technology able to synchronize the control actuator, has been widely used in medium voltage vacuum circuit breaker. Although the market for high-voltage level of permanent magnetic actuator has been very concerned about, but have not yet seen the product at home and Neodymium Magnets abroad reported. To meet the development of high-voltage vacuum circuit breakers need to fill the high-voltage magnetic actuator of the international space, this study used simultaneously with making and breaking capabilities of 126kV high-voltage vacuum circuit breaker magnetic actuator.
In this paper, virtual prototyping technology, the use of Ansoft Maxwell 3D/2D simulation software for magnetic actuator electromagnetic system of static and dynamic properties were calculated. Through theoretical analysis and comparison, about the use of primary and secondary coils in series excitation field winding ways to improve the effect, so that the movement of moving core in the long journey to get enough of the next operation is always successful. Excitation method proposed in this paper significantly improves the characteristics of permanent magnet actuator, so that sub-gate and the closing time, energy storage capacitors to reduce energy consumption, reduce peak current excitation coil, sub-gate and the closing velocity increases, moving core impact collisions slow down when closed, not only to meet the 126kV high voltage vacuum interrupter-off requirements, but also to improve the medium-voltage performance of permanent magnetic actuator provides a good solution.
To meet the synchronization accuracy and reduce the dispersion of the action, the need for permanent magnetic actuator of the operating time to compensate. In this paper, statistical learning theory, a least squares support vector machines based on permanent magnet actuator movement time prediction model. Using cross validation and grid search method to determine the core functions and support vector, then get a vector with only minority support for the prediction function expression. The simulation results show that the validation data, least squares support vector machine model has a strong generalization (forecasting) ability to obtain a smaller fitting error in the forecast http://www.everbeenmagnet.com/en/products/110-sintered-neodymium-magnets on the basis of minimum error, maximum error is less than ± 0.2ms , computational complexity is small, easy-to-line programming.
Electrical circuit breaker synchronous control is the development of intelligent direction and cutting-edge issues. At present, the synchronization technology has turned into the practical stage, but not easy to precisely synchronized with the signal breaking, breaking synchronization technology is still in the theoretical preparation. In this paper, the general expression of short-circuit current starting, parameter identification and adaptive arithmetic recursive method with the DC component of the transient short-circuit current decay for analysis, a mathematical model for forecasting short-circuit current zero. Analyzed using Matlab software, sampling rate, A / D converter quantization precision and signal to noise ratio of short-circuit current measurement circuit waveform analysis accuracy. After comprehensive comparison, made with 7 / 8 wave arithmetic recursive formula predict changes in properties of short-circuit current, with an estimated zero-crossing. The projections presented in this paper short-circuit current of 7 / 8 wave count recursive formula, the only 12bit A / D converter, each fundamental cycle, the sampling rate and 32 times more than 60dB signal to noise ratio of the circuit, easy hardware implementation and software programming.
Field programmable gate array developed in recent years as a general-purpose user-programmable devices, it has both the gate array of high integration and versatility, there are user-programmable flexibility, high speed, low power consumption, general strong, especially for complex systems design. This design uses a microcontroller and FPGA combination of parallel processing, design of permanent magnet synchronous actuator intelligent control system. The use of SCM measurement and control functions, the FPGA as an embedded microcontroller chip, designed to analyze the changes in short-circuit current characteristics, improve the synchronization of real-time and reliability. Degree Year: 2009
magneto-rheological fluid device and its aspheric polishing application
Title: magneto-rheological fluid device and its aspheric polishing application
Author: Cui governance
Degree-granting units: Jilin University
Keywords: magneto-rheological fluid;; yield stress;; finite element analysis;; non-spherical;; compliance control;; force-bit separation;; torque servo
Abstract:
In this paper, the National Natural Science Neodymium Magnets Foundation (50705044) 'NC polishing of the mold surface compliance control research "and
Ningbo Key Laboratory Fund (2007A22005) "based on magneto-rheological fluid (MRF) compliant device and its new research in the mold surface
Throw in the application of "soft polishing non-spherical target specific, in-depth study of magneto-rheological fluid device characteristics and in the process of polishing to do
For the moment the application server components.
In this paper, different work MRF model is proposed to control the maximum transmission ratio and
Output (torque) as the evaluation of the magneto-rheological fluid device mode options, and through experimental verification of this criterion is reasonable.
Damping plate for the magnetic field in http://www.everbeenmagnet.com/en/products/110-sintered-neodymium-magnets the non-uniform distribution due to different changes in the output torque, this same control current, the total flux constant and
The average gap for the same constraints and structural parameters to produce the maximum damping torque as an indicator of the shape of the damping of three different gap
To optimize the design. Improved magneto-rheological fluid device output performance.
This paper studies the characteristics of non-spherical rotating body, and magnetic flow
Fluid processing device applications for polishing the torque servo, machining polishing proposed force control room and digital control space accordingly
Share decoupling theory, will work with prototype and CNC machine tools, to achieve a force / position control of the separation of synchronization, an effective solution to the compliance control over
The impact of process variables are many and affect each other hard-line control problems.
This variable will be used in magneto-rheological fluid damping force
Torque servo tool, take advantage of this unique smart materials controllable reversible viscosity, vary widely and fast response characteristics, will be open
Provision of magneto-rheological fluid components for smart new areas of implementation;
Degree Year: 2009
Author: Cui governance
Degree-granting units: Jilin University
Keywords: magneto-rheological fluid;; yield stress;; finite element analysis;; non-spherical;; compliance control;; force-bit separation;; torque servo
Abstract:
In this paper, the National Natural Science Neodymium Magnets Foundation (50705044) 'NC polishing of the mold surface compliance control research "and
Ningbo Key Laboratory Fund (2007A22005) "based on magneto-rheological fluid (MRF) compliant device and its new research in the mold surface
Throw in the application of "soft polishing non-spherical target specific, in-depth study of magneto-rheological fluid device characteristics and in the process of polishing to do
For the moment the application server components.
In this paper, different work MRF model is proposed to control the maximum transmission ratio and
Output (torque) as the evaluation of the magneto-rheological fluid device mode options, and through experimental verification of this criterion is reasonable.
Damping plate for the magnetic field in http://www.everbeenmagnet.com/en/products/110-sintered-neodymium-magnets the non-uniform distribution due to different changes in the output torque, this same control current, the total flux constant and
The average gap for the same constraints and structural parameters to produce the maximum damping torque as an indicator of the shape of the damping of three different gap
To optimize the design. Improved magneto-rheological fluid device output performance.
This paper studies the characteristics of non-spherical rotating body, and magnetic flow
Fluid processing device applications for polishing the torque servo, machining polishing proposed force control room and digital control space accordingly
Share decoupling theory, will work with prototype and CNC machine tools, to achieve a force / position control of the separation of synchronization, an effective solution to the compliance control over
The impact of process variables are many and affect each other hard-line control problems.
This variable will be used in magneto-rheological fluid damping force
Torque servo tool, take advantage of this unique smart materials controllable reversible viscosity, vary widely and fast response characteristics, will be open
Provision of magneto-rheological fluid components for smart new areas of implementation;
Degree Year: 2009
2011年9月25日星期日
Ge-based and ZnO-based magnetic semiconductors, magnetic and transport studies
Title: Ge-based and ZnO-based magnetic semiconductors, magnetic and transport studies Author: Jiang Xia Tang Degree-granting units: Shandong University Keywords: Spintronics;; magnetic semiconductor;; Ge_ (1-x) Mn_x;; Zn_ (1-x) Co_xO;; Zn_ (1-x) Fe_xO Abstract: Spintronics is today's condensed matter physics, information science and new materials and many other areas of research focus of common concern, which the main
To study with the electron charge Neodymium Magnets and spin closely related processes, including the generation of the source spin, spin injection, spin transport, spin detection
And spin control, with the ultimate goal is to achieve a new type of spin electronic devices. Because of its guidance of a new mode of information processing and storage, large
Great ability to enhance information processing has a very broad application prospects. For the realization of spin electronic devices, you first need to generate in the material
Spin-polarized current. Generate spin-polarized current program there are many, the use of magnetic semiconductor spin-polarized current is injected into one of the main
To one of the options, so much attention magnetic semiconductors, as the field of spintronics research focus. Magnetic semiconductor is usually
Is through the of Ⅲ - Ⅴ, Ⅱ - Ⅵ family and Ⅳ compounds or elemental semiconductors doped with transition metal elements to get. Mn-doped
GaAs is the most studied and most detailed study of the system, the Curie temperature is currently up to 185K. Their magnetic properties from the carrier (hole)-induced
Ferromagnetic exchange interaction between the doped Mn ions mediated by holes generated macro-ferromagnetic exchange interaction resulting in spontaneous
Polarization. However, due to its Curie temperature is still too low at room temperature application. Therefore, the search for Curie temperature at room temperature or above room temperature magnetic
Applied research of semiconductor materials to become a hot issue. Theory predicts, Ge-based magnetic semiconductors above the Curie temperature up to 400K, ZnO
Based magnetic semiconductors above the Curie temperature up to 300K. In addition, as the semiconductor itself, Ge with the current mature phase of Si-based semiconductor technology
Compatible, ZnO semiconductor light-emitting materials, piezoelectric materials, transparent conductive film has a broad research and application, so, Ge-based and ZnO-based
Magnetic semiconductors has been of great concern! At present, research work from the point of view, Ge-based and ZnO-based magnetic semiconductors are
Needed to overcome a series of common problems, such as: the nature of the sample preparation method and often depends on the growth process, each sample of magnetic
Sexual expression is not consistent with the origin of ferromagnetism is no uniform interpretation and so on. To solve these problems, we will use the low-temperature molecular beam epitaxy and
The sample was prepared by amorphous phase two experimental preparation methods, to study the Ge-based and ZnO-based http://www.everbeenmagnet.com/en/products/110-sintered-neodymium-magnets magnetic semiconductors. Which the low-temperature molecular beam epitaxy
Single-crystal samples prepared in the structure of its unity and purity of the composition can effectively prevent precipitation of the ferromagnetic impurity phase or
Ferromagnetic material of the sample sources of interference, more conducive to analysis of its magnetic origin and so on; and amorphous phase approach is from the application point of view
, By increasing the solubility of ferromagnetic metals to increase the Curie temperature and magnetization. This thesis work includes preparation of single crystal, amorphous
Ge-based and ZnO-based magnetic semiconductor thin films, to study its magnetic and transport properties, and its corresponding magnetic transport mechanism of the origin and
. Paper's results are as follows: ● We use ultra-high vacuum molecular beam epitaxy at low temperature the Ge_ (1-x) Mn_x
(X = 0.019,0.041,0.051,0.072,0.105) diluted magnetic semiconductor thin films, and studied its magnetic and transport properties. Real-time reflection
High-energy electron diffraction image (RHEED) and XRD measurements show that when the Mn content x less than 0.105, Ge_ (1-x) Mn_x film to maintain crystal structure.
5K hysteresis whirl under the line that all samples are ferromagnetic, in addition to single crystal film in the presence of strong magnetic anisotropy, that is, magnetization in the
Film plane and perpendicular to the membrane surface is very different, indicating that there is a strong film spin-orbit coupling. R-T curve shows that the film
Conductive properties are semiconducting properties, and low-temperature region in line with Efros variable range transport transition. Ge_ (0.949) Mn_ (0.051) film
The Hall effect measurements showed that the Hall effect and anomalous Hall effect from the normal Hall effect composition. Anomalous Hall effect shows that the sample
Ferromagnetism by the carrier to pass. As the temperature decreases, the coefficient of the normal Hall effect changes sign occurs. According to Emin's theory, the jump
Hall moved to have conductive areas of the Aharonov-Bohm effect ring contains an odd number of bits will be sign anomaly, given the low sample
Conductive zone of transition, we believe that the distribution of low temperature in any of the three local Mn acceptor transition between the centers of the anomalous Hall effect
Sources, but also the normal Hall effect changes sign from. ● We have three different conductivity types (n-type, intrinsic, p-type) Ge single
Crystal substrate, molecular beam epitaxy epitaxy of Ge_ (1-x) Mn_x single crystal film, to form Ge_ (1-x) Mn_x / Ge heterojunction, and research
The heterojunction rectification characteristics and magnetic field characteristics of its rectification. Research shows that all samples have the rectification effect results, which
the best characteristics of pn junction rectifier, pp knot by the maximum current density and magnetic field of the pi junction control the most obvious. In addition, in view of p-i junction
To the positive magnetoresistance observed, its value as the temperature rises in the 225K A great value, combined with the band filling effect and the magnetic field resulting wave function
Contraction effect on the experimental results to make a more reasonable explanation. ● We use molecular beam epitaxy of ultra-high vacuum and low sample stage
Temperature growth conditions in liquid nitrogen cooled glass substrates were prepared by high Mn concentrations Ge_ (1-x) Mn_x (x = 0.39,0.52,0.66,0.79) non-
Crystal magnetic semiconductor thin films, and studied its magnetic and transport aspects of nature. All samples under 5K whirl lines indicate magnetic hysteresis and
Coexist in the sample being paramagnetic. Ge_ (0.48) Mn_ (0.52) film, the Curie temperature up to 220K. X = 0.66 and 0.79 in the sample
Are observed in exchange bias phenomenon, combined with the corresponding structural properties of thin films, this phenomenon may come from poor areas of the ferromagnetic phase-Mn and Mn-rich
Area and Mn_ (11) Ge_8 antiferromagnetic phase-antiferromagnetic exchange coupling between the role. Conductive properties of the sample electrical properties of semiconductors, in temperature
Degrees below the Curie temperature of the sample to the anomalous Hall effect observed, indicating that the ferromagnetism is caused by carrier. ● We
Using oxygen plasma assisted molecular beam epitaxy source was prepared at room temperature ferromagnetism with the Co doped ZnO diluted magnetic semiconductor single crystal film. Real
Observed when the scan shows RHEED and XRD 2θ Zn_ (1-x) Co_xO film is single crystal. Transmission spectrum and XPS measurements indicate that Co in Co ~
(2 +) chemical state. SQUID measurements show Zn_ (1-x) Co_xO thin films with room temperature ferromagnetism, the Curie temperature above room
Temperature, the saturation magnetization increases with Co doping increases. Combining these results can determine the sample at room temperature ferromagnetism is the
Sign of. The magnetic origin can be used to describe the bound magnetic polaron model, the doping of Co ~ (2 +) to produce light as a medium of exchange donor defects
Role in forming a magnetic polaron, as a result of these magnetic polaron coupling between the interaction of a long-range ferromagnetic order to form a macro
View of ferromagnetism. In addition, the conductive properties of the sample electrical properties of semiconductors. ● We have studied the sputtering device obtained by the non-uniform
High quality Fe concentration Zn_ (1-x) Fe_xO magnetic semiconductor thin films annealed state and the magnetic and transport aspects of nature. Study Table
Ming, their magnetic properties by controlling the composition of the heterogeneity and to be modulated by rapid annealing. Ferromagnetic and paramagnetic elements coexist in
Preparation of state Zn_ (1-x) Fe_xO film samples, and in the preparation of state Zr_ (0.23) Fe_ (0.77) O thin films observed positive reversal
Field, indicating that local neighbor ferromagnetic films with antiferromagnetic coupling region, this role is to stimulate the transition from the hot-carrier passed by, the
Reverse field size 110K to 300K temperature range increases with increasing temperature. Degree Year: 2009
To study with the electron charge Neodymium Magnets and spin closely related processes, including the generation of the source spin, spin injection, spin transport, spin detection
And spin control, with the ultimate goal is to achieve a new type of spin electronic devices. Because of its guidance of a new mode of information processing and storage, large
Great ability to enhance information processing has a very broad application prospects. For the realization of spin electronic devices, you first need to generate in the material
Spin-polarized current. Generate spin-polarized current program there are many, the use of magnetic semiconductor spin-polarized current is injected into one of the main
To one of the options, so much attention magnetic semiconductors, as the field of spintronics research focus. Magnetic semiconductor is usually
Is through the of Ⅲ - Ⅴ, Ⅱ - Ⅵ family and Ⅳ compounds or elemental semiconductors doped with transition metal elements to get. Mn-doped
GaAs is the most studied and most detailed study of the system, the Curie temperature is currently up to 185K. Their magnetic properties from the carrier (hole)-induced
Ferromagnetic exchange interaction between the doped Mn ions mediated by holes generated macro-ferromagnetic exchange interaction resulting in spontaneous
Polarization. However, due to its Curie temperature is still too low at room temperature application. Therefore, the search for Curie temperature at room temperature or above room temperature magnetic
Applied research of semiconductor materials to become a hot issue. Theory predicts, Ge-based magnetic semiconductors above the Curie temperature up to 400K, ZnO
Based magnetic semiconductors above the Curie temperature up to 300K. In addition, as the semiconductor itself, Ge with the current mature phase of Si-based semiconductor technology
Compatible, ZnO semiconductor light-emitting materials, piezoelectric materials, transparent conductive film has a broad research and application, so, Ge-based and ZnO-based
Magnetic semiconductors has been of great concern! At present, research work from the point of view, Ge-based and ZnO-based magnetic semiconductors are
Needed to overcome a series of common problems, such as: the nature of the sample preparation method and often depends on the growth process, each sample of magnetic
Sexual expression is not consistent with the origin of ferromagnetism is no uniform interpretation and so on. To solve these problems, we will use the low-temperature molecular beam epitaxy and
The sample was prepared by amorphous phase two experimental preparation methods, to study the Ge-based and ZnO-based http://www.everbeenmagnet.com/en/products/110-sintered-neodymium-magnets magnetic semiconductors. Which the low-temperature molecular beam epitaxy
Single-crystal samples prepared in the structure of its unity and purity of the composition can effectively prevent precipitation of the ferromagnetic impurity phase or
Ferromagnetic material of the sample sources of interference, more conducive to analysis of its magnetic origin and so on; and amorphous phase approach is from the application point of view
, By increasing the solubility of ferromagnetic metals to increase the Curie temperature and magnetization. This thesis work includes preparation of single crystal, amorphous
Ge-based and ZnO-based magnetic semiconductor thin films, to study its magnetic and transport properties, and its corresponding magnetic transport mechanism of the origin and
. Paper's results are as follows: ● We use ultra-high vacuum molecular beam epitaxy at low temperature the Ge_ (1-x) Mn_x
(X = 0.019,0.041,0.051,0.072,0.105) diluted magnetic semiconductor thin films, and studied its magnetic and transport properties. Real-time reflection
High-energy electron diffraction image (RHEED) and XRD measurements show that when the Mn content x less than 0.105, Ge_ (1-x) Mn_x film to maintain crystal structure.
5K hysteresis whirl under the line that all samples are ferromagnetic, in addition to single crystal film in the presence of strong magnetic anisotropy, that is, magnetization in the
Film plane and perpendicular to the membrane surface is very different, indicating that there is a strong film spin-orbit coupling. R-T curve shows that the film
Conductive properties are semiconducting properties, and low-temperature region in line with Efros variable range transport transition. Ge_ (0.949) Mn_ (0.051) film
The Hall effect measurements showed that the Hall effect and anomalous Hall effect from the normal Hall effect composition. Anomalous Hall effect shows that the sample
Ferromagnetism by the carrier to pass. As the temperature decreases, the coefficient of the normal Hall effect changes sign occurs. According to Emin's theory, the jump
Hall moved to have conductive areas of the Aharonov-Bohm effect ring contains an odd number of bits will be sign anomaly, given the low sample
Conductive zone of transition, we believe that the distribution of low temperature in any of the three local Mn acceptor transition between the centers of the anomalous Hall effect
Sources, but also the normal Hall effect changes sign from. ● We have three different conductivity types (n-type, intrinsic, p-type) Ge single
Crystal substrate, molecular beam epitaxy epitaxy of Ge_ (1-x) Mn_x single crystal film, to form Ge_ (1-x) Mn_x / Ge heterojunction, and research
The heterojunction rectification characteristics and magnetic field characteristics of its rectification. Research shows that all samples have the rectification effect results, which
the best characteristics of pn junction rectifier, pp knot by the maximum current density and magnetic field of the pi junction control the most obvious. In addition, in view of p-i junction
To the positive magnetoresistance observed, its value as the temperature rises in the 225K A great value, combined with the band filling effect and the magnetic field resulting wave function
Contraction effect on the experimental results to make a more reasonable explanation. ● We use molecular beam epitaxy of ultra-high vacuum and low sample stage
Temperature growth conditions in liquid nitrogen cooled glass substrates were prepared by high Mn concentrations Ge_ (1-x) Mn_x (x = 0.39,0.52,0.66,0.79) non-
Crystal magnetic semiconductor thin films, and studied its magnetic and transport aspects of nature. All samples under 5K whirl lines indicate magnetic hysteresis and
Coexist in the sample being paramagnetic. Ge_ (0.48) Mn_ (0.52) film, the Curie temperature up to 220K. X = 0.66 and 0.79 in the sample
Are observed in exchange bias phenomenon, combined with the corresponding structural properties of thin films, this phenomenon may come from poor areas of the ferromagnetic phase-Mn and Mn-rich
Area and Mn_ (11) Ge_8 antiferromagnetic phase-antiferromagnetic exchange coupling between the role. Conductive properties of the sample electrical properties of semiconductors, in temperature
Degrees below the Curie temperature of the sample to the anomalous Hall effect observed, indicating that the ferromagnetism is caused by carrier. ● We
Using oxygen plasma assisted molecular beam epitaxy source was prepared at room temperature ferromagnetism with the Co doped ZnO diluted magnetic semiconductor single crystal film. Real
Observed when the scan shows RHEED and XRD 2θ Zn_ (1-x) Co_xO film is single crystal. Transmission spectrum and XPS measurements indicate that Co in Co ~
(2 +) chemical state. SQUID measurements show Zn_ (1-x) Co_xO thin films with room temperature ferromagnetism, the Curie temperature above room
Temperature, the saturation magnetization increases with Co doping increases. Combining these results can determine the sample at room temperature ferromagnetism is the
Sign of. The magnetic origin can be used to describe the bound magnetic polaron model, the doping of Co ~ (2 +) to produce light as a medium of exchange donor defects
Role in forming a magnetic polaron, as a result of these magnetic polaron coupling between the interaction of a long-range ferromagnetic order to form a macro
View of ferromagnetism. In addition, the conductive properties of the sample electrical properties of semiconductors. ● We have studied the sputtering device obtained by the non-uniform
High quality Fe concentration Zn_ (1-x) Fe_xO magnetic semiconductor thin films annealed state and the magnetic and transport aspects of nature. Study Table
Ming, their magnetic properties by controlling the composition of the heterogeneity and to be modulated by rapid annealing. Ferromagnetic and paramagnetic elements coexist in
Preparation of state Zn_ (1-x) Fe_xO film samples, and in the preparation of state Zr_ (0.23) Fe_ (0.77) O thin films observed positive reversal
Field, indicating that local neighbor ferromagnetic films with antiferromagnetic coupling region, this role is to stimulate the transition from the hot-carrier passed by, the
Reverse field size 110K to 300K temperature range increases with increasing temperature. Degree Year: 2009
Magnetic resonance imaging in chronic kidney disease in the clinical application
Title: Magnetic resonance imaging in chronic kidney disease in the clinical application of Authors: Qing-Hai Li Degree-granting units: Fudan University Keywords: magnetic resonance imaging;; diffusion-weighted imaging;; prospective acquisition correction technique;; kidney; chronic kidney disease;; magnetic resonance imaging;; dispersion plus
The right image;; glomerular filtration rate; Neodymium Magnets chronic kidney disease;; magnetic resonance imaging;; diffusion-weighted imaging;; pathology; chronic kidney disease;; magnetic resonance imaging;;
Blood oxygen level-dependent magnetic resonance imaging;; pathology Abstract: The first part Prospective acquisition correction in diffusion-weighted imaging of the kidney clinical studies Purpose:
Explore the use of navigation technology triggered prospective acquisition correction diffusion-weighted imaging (PACE-DWI) in the kidney ADC value measurement repeatability,
And the image signal to noise ratio (SNR) and contrast to noise ratio (CNR) and routine exclusion of air compared to DWI. Methods: 15 healthy volunteers
Conducted a repeat DWI examination (two inspections for the 5-42 day interval), DWI scans are used for each exclusion gas single-shot spin-echo level
Surface echo (SS-SE-EPI) sequence and the use of PACE technology SE-EPI sequence, the choice of five different diffusion gradient factor (b value) of 100,
300,500,800 and 1000 s / mm ~ 2. PACE-DWI ADC value measured in the renal parenchyma of the reproducibility study, using paired t test,
Bland-Altman plot and coherence of analysis; two imaging sequences between the SNR and CNR were compared using Mann-Whitney U test;
Different b values group asked the SNR and CNR were compared using Kruskal-Wallis H test; air exclusion PACE-DWI DWI and ADC values measured by comparison
Using the Wilcoxon paired signed rank test; http://www.everbeenmagnet.com/en/products/110-sintered-neodymium-magnets different b values between the two groups was used to compare ADC values of the Friedman test. Results: The b-value conditions
, The use of PACE-DWI repeat the measured ADC values of kidneys showed no real significant difference (P> 0.05). And in addition to b = 100 s / mm ~ 2 conditions
Addition, PACE-DWI repeat the measured ADC values of renal mean difference of -4.4 × 10 ~ (-5) mm ~ 2 / s ~ 6.3 × 10 ~ (-5) mm ~ 2 / s, a
To limit (mean difference ± 1.96 SD) of ± 28.1 × 10 ~ (-5) mm ~ 2 / s ~ ± 36.4 × 10 ~ (-5) mm ~ 2 / s, repeated measured renal
ADC values between the high consistency (ρ_c = 0.892, P = 0.000). B-value under the same conditions, PACE-DWI images of the SNR and CNR significantly
Exclusion of air above the sequence, there were significant differences (P <0.05); but the exclusion of air, whether DWI or PACE-DWI, with the b value increased, DWI image
The SNR and CNR were decreased, and in the b-value between groups statistically significant difference (P <0.01). In addition, the same b-value conditions
Under, PACE-DWI ADC values measured are higher than the exclusion of air sequence, and in addition to b = 100 s / mm ~ 2 substance under the conditions of the right kidney ADC values, between
There were significant differences (P <0.05); but the exclusion of air, whether DWI or PACE-DWI, ADC values of renal b value increases with a declining trend
And the b-value ADC values between groups were statistically significant differences (P <0.01). Conclusion: PACE-DWI ADC values measured in the kidney
Has good repeatability, and the SNR and CNR were significantly higher than the conventional exclusion of air DWI, suitable for clinical research. However, PACE-DWI and the exclusion of
Gas DWI measured differences between the ADC value. The second part Diffusion-weighted imaging in patients with chronic renal function assessment in clinical
Applied Research Objective: To evaluate diffusion-weighted imaging (DWI) in patients with chronic kidney disease (CKD) stage and sub-clinical assessment of renal function in the price
Value on renal function and renal effects of volume, compared with the prospective acquisition correction triggered navigation technology diffusion-weighted imaging (PACE-DWI) in
Points in the presence of renal function assessment advantage. Methods: 83 cases of CKD patients and 12 healthy volunteers conducted a DWI examination, were collected
With the exclusion of air SS-SE-EPI sequence and the use of PACE technology, SE-EPI sequence, diffusion gradient factor (b value) were 300 s / mm ~ 2 and 800
s / mm ~ 2. Of which 54 cases were also checked isotope renogram, with Gates method of glomerular filtration rate (GFR). Single factor
Analysis of variance to compare the mean ADC renal function in different clinical kidney during renal ADC values and sub-, sub-sub-renal volume and renal volume by the ADC value
Renal function in a different plot points if there are differences between the groups; factors using partial correlation controlling for age analysis and receiver operating curve (ROC) to sub-
Analysis of ADC values of sub-renal, renal volume and renal ADC values of sub-sub-volume product in the value assessment of renal function, and decreased kidney function in the prediction and sub-
Mild decrease in the diagnosis. Results: The mean ADC measured in the kidneys between the groups in all clinical stages were statistically significant differences exist
(P <0.01), with the clinical stage of CKD increased renal function decline, and in the b = 800 s / mm ~ 2, the first and second period and both during the first 3-5
Statistical difference (P <0.05). ADC value and sub-sub-renal kidney GFR positive correlation between the presence of mild to PACE-DWI at b = 800 s / mm ~ 2
, The positive correlation between the two highest (r = 0.471, P = 0.000). PACE-DWI measured with sub-sub-renal ADC values were reduced renal function decline
Trend in the three groups there were significant statistical difference (P <0.01), and to b = 800 s / mm ~ 2 conditions, mild renal function in predicting sub-
Reduce the diagnostic performance of the largest (AUC = 0.780, P = 0.000). In addition, sub-sub-kidney GFR and renal volume low positive correlation between the presence of
(R = 0.470, P = 0.000). ADC values of sub-renal kidney GFR and its sub-volume product of moderate positive correlation between (r = 0.521-
0.550, P = 0.000), and renal function at different points between the two groups were statistically significant differences (P <0.01), mild renal function in predicting sub-
Reduction to further improve the diagnostic performance (AUC = 0.824-0.841, P = 0.000). Conclusion: DWI in CKD stages and sub-clinical renal
To assess the value of certain, especially the use of PACE technology and high b value DWI in the assessment of renal function points, has an advantage, and in the clinic
Renal function decreased slightly off the point there is a certain value. In addition, the volume as factors affecting renal function can not be ignored, combined with ADC
Value and volume measurement of renal kidney function can increase the accuracy of assessment points. The third part Diffusion-weighted imaging evaluation of chronic kidney
Disease clinical pathological damage - Pathology Objective: To evaluate diffusion-weighted imaging (DWI) in patients with chronic kidney disease (CKD) pathological damage assessment
The clinical value, and the use of navigation technology triggered prospective acquisition correction diffusion-weighted imaging (PACE-DWI) whether there are advantages
. Methods: 83 cases of CKD who underwent kidney biopsy cases and 12 healthy volunteers were DWI examination, exclusion of air were used SS-SE
PACE-EPI sequence and the use of technology, SE-EPI sequence, select the b value 300s/mm ~ 2 and 800 s / mm ~ 2. Pathology by two doctors
Health and renal biopsy specimens of the common pathological damage score, as the evaluation criteria for chronic renal pathological damage. Finally, a total of 71 cases of CKD patients and
12 healthy volunteers included in the analysis. Using Pearson correlation analysis, ANOVA and ROC curve analysis of the ADC value in assessing CKD
Pathological damage and moderate to severe pathology in predicting the value of the extent of damage, and to explore whether there are advantages of PACE-DWI; using two independent
Samples t test and ANOVA to compare the different pathological types of CKD and different levels of IgA nephropathy among Lee's ADC value is stored
The difference; using multiple linear regression model affect the ADC value of the preliminary analysis of independent factors. Results: Pathological damage with CKD
The increase, right kidney ADC values showed a downward trend, and pathology of points there were significant negative correlation to PACE-DWI at b = 800 s / mm ~ 2
, The negative correlation between the maximum (r =- 0.632, P = 0.000), and in the prediction of moderate to severe pathological damage in the performance of the largest diagnostic
(AUC = 0.806, P = 0.000). PACE-DWI at b = 800 s / mm ~ 2, the four kinds of pathological types of primary glomerulonephritis ADC values between the stored
Significant difference in the (F = 4.164, P = 0.016), LSD twenty-two analysis showed that glomerulosclerosis was significantly lower than the ADC values of membrane
Nephropathy and focal segmental glomerulonephritis (P <0.05). Lee's grading of IgA nephropathy different ADC values between the groups there is also a significant statistical difference
(P <0.01), LSD pairwise comparison of the results showed that four cases of ADC values were significantly lower than 2 and 3 patients groups (P <0.01). Multi-line
Regression analysis showed that only pathological damage points and ADC values there were significant linear regression relationship (P <0.05), while the right kidney
GFR and between age and ADC values do not exist in linear regression. Conclusion: DWI to a certain extent, reflect the pathological CKD
The extent of damage, and the use of PACE technology and high b value DWI in pathological damage assessment has an advantage, is expected to become a non-invasive evaluation of CKD
Pathological damage, the means of guiding treatment and follow-up. However, the type of DWI in the pathological diagnosis of CKD is limited value, to be further
Research. Part IV 3.OT blood oxygen level-dependent magnetic resonance imaging in chronic kidney disease in a preliminary clinical study
Objective: To investigate 3.0T magnetic resonance imaging blood oxygen level dependent (BOLD-MRI) is the largest TE timing of kidney R_2 ~ * values are measured
There is influence, and a preliminary study of renal oxygenation in CKD condition assessment of the value. Methods: Magnetic resonance in GE 3.0T Signa HDx
Scanner, in 13 healthy volunteers and 61 cases who underwent renal biopsy in patients with CKD had BOLD-MRI, multi-gradient reunion back
Wave sequence, respectively 6 and 12 echo echo chain chain, TE time was 2.8-22.4 ms and 2.8-45.9 ms. Finally, 13 cases of health
Health volunteers and 44 cases of CKD patients included in the analysis, in which a total of 39 cases of CKD patients had renal pathological damage score, 20 patients were simultaneously
Check the isotope GFR. Jointly by two radiologists for image analysis, histogram analysis method, the image points R_2 ~ *
Do not measured in different conditions, the maximum time TE renal cortex and medulla of R_2 ~ * values, and using using the Wilcoxon signed rank test to compare paired
Whether there are differences between the two. For patients with CKD, only measuring 6 echo chain under the conditions of renal cortex and medulla of R_2 ~ * values. Paper pulp normal kidney
Quality R_2 ~ * values compared using the Wilcoxon paired signed rank test; using 6-echo echo-chain and 12 chain 3.0T BOLD-MRI in
Measuring renal cortex and medulla R_2 ~ * whether there are differences between the comparison, using paired t test, Bland-Altman plot and consistency of the relevant sub-
Analysis; normal control group between the two groups with CKD renal cortex and medulla R_2 ~ * mean comparisons, using Mann-Whitney U test; different renal
Able during clinical renal cortex and medulla R_2 ~ * mean comparison, using single-factor analysis of variance; points kidney R_2 ~ * kidney GFR and its sub-phase
Correlation with pathological damage analysis and correlation analysis points to ask, using spearman correlation analysis. Results: R_2 ~ * Color
Map, normal kidney cortex and medulla is relatively clear boundaries, showing the color gradually from the cortex to the medulla from blue to green, yellow, red over
Crossing changes. Kidney medulla R_2 ~ * significantly higher than the cortex, there were significant between the two statistical difference (P <0.01). 6 echo chain (
Maximum TE: 22.4 msec) and 12 echo chain (maximum TE: 45.9 msec) conditions, measured around the renal cortex and medulla R_2 ~ * values between
Do not exist significant differences (P> 0.05). Also, different echo chain conditions, repeated measured renal cortex and medulla R_2 ~ * average
Difference of -0.3 sec ~ (-1), consistency limits (mean difference ± 1.96 SD) of -1.9 ~ 1.4 sec ~ (-1), repeated measured renal cortical and medullary
Quality R_2 ~ * values with high consistency (pc = 0.983, P = 0.000). CKD group, renal cortex and medulla R_2 ~ * is significantly higher than average
Normal control group, there were significant between the two statistical difference (P <0.01). With increasing clinical stage of renal function, renal medulla R_2 ~ * mean
Was gradually increasing trend, and there are significant differences between the groups (P <0.05). LSD pairwise comparison of the results showed that the normal control group and 2
-4 Significant differences exist in the period (P <0.05). In addition, the sub-renal medullary R_2 ~ * kidney GFR values and points are significantly negative correlation
(R =- 0.415, P = 0.008), and pathological damage points there were significant positive correlation (r = 0.450, P =- 0.004). Conclusion:
In the 3.0T BOLD-MRI examination, using six echo chain (the largest TE 22.4 msec) will be able to meet the kidneys R_2 ~ * value measurements, and can
Enough to reflect the presence of hypoxia in CKD, the kidney is expected to provide an assessment of oxygenation status of non-invasive means. Degree Year: 2009
The right image;; glomerular filtration rate; Neodymium Magnets chronic kidney disease;; magnetic resonance imaging;; diffusion-weighted imaging;; pathology; chronic kidney disease;; magnetic resonance imaging;;
Blood oxygen level-dependent magnetic resonance imaging;; pathology Abstract: The first part Prospective acquisition correction in diffusion-weighted imaging of the kidney clinical studies Purpose:
Explore the use of navigation technology triggered prospective acquisition correction diffusion-weighted imaging (PACE-DWI) in the kidney ADC value measurement repeatability,
And the image signal to noise ratio (SNR) and contrast to noise ratio (CNR) and routine exclusion of air compared to DWI. Methods: 15 healthy volunteers
Conducted a repeat DWI examination (two inspections for the 5-42 day interval), DWI scans are used for each exclusion gas single-shot spin-echo level
Surface echo (SS-SE-EPI) sequence and the use of PACE technology SE-EPI sequence, the choice of five different diffusion gradient factor (b value) of 100,
300,500,800 and 1000 s / mm ~ 2. PACE-DWI ADC value measured in the renal parenchyma of the reproducibility study, using paired t test,
Bland-Altman plot and coherence of analysis; two imaging sequences between the SNR and CNR were compared using Mann-Whitney U test;
Different b values group asked the SNR and CNR were compared using Kruskal-Wallis H test; air exclusion PACE-DWI DWI and ADC values measured by comparison
Using the Wilcoxon paired signed rank test; http://www.everbeenmagnet.com/en/products/110-sintered-neodymium-magnets different b values between the two groups was used to compare ADC values of the Friedman test. Results: The b-value conditions
, The use of PACE-DWI repeat the measured ADC values of kidneys showed no real significant difference (P> 0.05). And in addition to b = 100 s / mm ~ 2 conditions
Addition, PACE-DWI repeat the measured ADC values of renal mean difference of -4.4 × 10 ~ (-5) mm ~ 2 / s ~ 6.3 × 10 ~ (-5) mm ~ 2 / s, a
To limit (mean difference ± 1.96 SD) of ± 28.1 × 10 ~ (-5) mm ~ 2 / s ~ ± 36.4 × 10 ~ (-5) mm ~ 2 / s, repeated measured renal
ADC values between the high consistency (ρ_c = 0.892, P = 0.000). B-value under the same conditions, PACE-DWI images of the SNR and CNR significantly
Exclusion of air above the sequence, there were significant differences (P <0.05); but the exclusion of air, whether DWI or PACE-DWI, with the b value increased, DWI image
The SNR and CNR were decreased, and in the b-value between groups statistically significant difference (P <0.01). In addition, the same b-value conditions
Under, PACE-DWI ADC values measured are higher than the exclusion of air sequence, and in addition to b = 100 s / mm ~ 2 substance under the conditions of the right kidney ADC values, between
There were significant differences (P <0.05); but the exclusion of air, whether DWI or PACE-DWI, ADC values of renal b value increases with a declining trend
And the b-value ADC values between groups were statistically significant differences (P <0.01). Conclusion: PACE-DWI ADC values measured in the kidney
Has good repeatability, and the SNR and CNR were significantly higher than the conventional exclusion of air DWI, suitable for clinical research. However, PACE-DWI and the exclusion of
Gas DWI measured differences between the ADC value. The second part Diffusion-weighted imaging in patients with chronic renal function assessment in clinical
Applied Research Objective: To evaluate diffusion-weighted imaging (DWI) in patients with chronic kidney disease (CKD) stage and sub-clinical assessment of renal function in the price
Value on renal function and renal effects of volume, compared with the prospective acquisition correction triggered navigation technology diffusion-weighted imaging (PACE-DWI) in
Points in the presence of renal function assessment advantage. Methods: 83 cases of CKD patients and 12 healthy volunteers conducted a DWI examination, were collected
With the exclusion of air SS-SE-EPI sequence and the use of PACE technology, SE-EPI sequence, diffusion gradient factor (b value) were 300 s / mm ~ 2 and 800
s / mm ~ 2. Of which 54 cases were also checked isotope renogram, with Gates method of glomerular filtration rate (GFR). Single factor
Analysis of variance to compare the mean ADC renal function in different clinical kidney during renal ADC values and sub-, sub-sub-renal volume and renal volume by the ADC value
Renal function in a different plot points if there are differences between the groups; factors using partial correlation controlling for age analysis and receiver operating curve (ROC) to sub-
Analysis of ADC values of sub-renal, renal volume and renal ADC values of sub-sub-volume product in the value assessment of renal function, and decreased kidney function in the prediction and sub-
Mild decrease in the diagnosis. Results: The mean ADC measured in the kidneys between the groups in all clinical stages were statistically significant differences exist
(P <0.01), with the clinical stage of CKD increased renal function decline, and in the b = 800 s / mm ~ 2, the first and second period and both during the first 3-5
Statistical difference (P <0.05). ADC value and sub-sub-renal kidney GFR positive correlation between the presence of mild to PACE-DWI at b = 800 s / mm ~ 2
, The positive correlation between the two highest (r = 0.471, P = 0.000). PACE-DWI measured with sub-sub-renal ADC values were reduced renal function decline
Trend in the three groups there were significant statistical difference (P <0.01), and to b = 800 s / mm ~ 2 conditions, mild renal function in predicting sub-
Reduce the diagnostic performance of the largest (AUC = 0.780, P = 0.000). In addition, sub-sub-kidney GFR and renal volume low positive correlation between the presence of
(R = 0.470, P = 0.000). ADC values of sub-renal kidney GFR and its sub-volume product of moderate positive correlation between (r = 0.521-
0.550, P = 0.000), and renal function at different points between the two groups were statistically significant differences (P <0.01), mild renal function in predicting sub-
Reduction to further improve the diagnostic performance (AUC = 0.824-0.841, P = 0.000). Conclusion: DWI in CKD stages and sub-clinical renal
To assess the value of certain, especially the use of PACE technology and high b value DWI in the assessment of renal function points, has an advantage, and in the clinic
Renal function decreased slightly off the point there is a certain value. In addition, the volume as factors affecting renal function can not be ignored, combined with ADC
Value and volume measurement of renal kidney function can increase the accuracy of assessment points. The third part Diffusion-weighted imaging evaluation of chronic kidney
Disease clinical pathological damage - Pathology Objective: To evaluate diffusion-weighted imaging (DWI) in patients with chronic kidney disease (CKD) pathological damage assessment
The clinical value, and the use of navigation technology triggered prospective acquisition correction diffusion-weighted imaging (PACE-DWI) whether there are advantages
. Methods: 83 cases of CKD who underwent kidney biopsy cases and 12 healthy volunteers were DWI examination, exclusion of air were used SS-SE
PACE-EPI sequence and the use of technology, SE-EPI sequence, select the b value 300s/mm ~ 2 and 800 s / mm ~ 2. Pathology by two doctors
Health and renal biopsy specimens of the common pathological damage score, as the evaluation criteria for chronic renal pathological damage. Finally, a total of 71 cases of CKD patients and
12 healthy volunteers included in the analysis. Using Pearson correlation analysis, ANOVA and ROC curve analysis of the ADC value in assessing CKD
Pathological damage and moderate to severe pathology in predicting the value of the extent of damage, and to explore whether there are advantages of PACE-DWI; using two independent
Samples t test and ANOVA to compare the different pathological types of CKD and different levels of IgA nephropathy among Lee's ADC value is stored
The difference; using multiple linear regression model affect the ADC value of the preliminary analysis of independent factors. Results: Pathological damage with CKD
The increase, right kidney ADC values showed a downward trend, and pathology of points there were significant negative correlation to PACE-DWI at b = 800 s / mm ~ 2
, The negative correlation between the maximum (r =- 0.632, P = 0.000), and in the prediction of moderate to severe pathological damage in the performance of the largest diagnostic
(AUC = 0.806, P = 0.000). PACE-DWI at b = 800 s / mm ~ 2, the four kinds of pathological types of primary glomerulonephritis ADC values between the stored
Significant difference in the (F = 4.164, P = 0.016), LSD twenty-two analysis showed that glomerulosclerosis was significantly lower than the ADC values of membrane
Nephropathy and focal segmental glomerulonephritis (P <0.05). Lee's grading of IgA nephropathy different ADC values between the groups there is also a significant statistical difference
(P <0.01), LSD pairwise comparison of the results showed that four cases of ADC values were significantly lower than 2 and 3 patients groups (P <0.01). Multi-line
Regression analysis showed that only pathological damage points and ADC values there were significant linear regression relationship (P <0.05), while the right kidney
GFR and between age and ADC values do not exist in linear regression. Conclusion: DWI to a certain extent, reflect the pathological CKD
The extent of damage, and the use of PACE technology and high b value DWI in pathological damage assessment has an advantage, is expected to become a non-invasive evaluation of CKD
Pathological damage, the means of guiding treatment and follow-up. However, the type of DWI in the pathological diagnosis of CKD is limited value, to be further
Research. Part IV 3.OT blood oxygen level-dependent magnetic resonance imaging in chronic kidney disease in a preliminary clinical study
Objective: To investigate 3.0T magnetic resonance imaging blood oxygen level dependent (BOLD-MRI) is the largest TE timing of kidney R_2 ~ * values are measured
There is influence, and a preliminary study of renal oxygenation in CKD condition assessment of the value. Methods: Magnetic resonance in GE 3.0T Signa HDx
Scanner, in 13 healthy volunteers and 61 cases who underwent renal biopsy in patients with CKD had BOLD-MRI, multi-gradient reunion back
Wave sequence, respectively 6 and 12 echo echo chain chain, TE time was 2.8-22.4 ms and 2.8-45.9 ms. Finally, 13 cases of health
Health volunteers and 44 cases of CKD patients included in the analysis, in which a total of 39 cases of CKD patients had renal pathological damage score, 20 patients were simultaneously
Check the isotope GFR. Jointly by two radiologists for image analysis, histogram analysis method, the image points R_2 ~ *
Do not measured in different conditions, the maximum time TE renal cortex and medulla of R_2 ~ * values, and using using the Wilcoxon signed rank test to compare paired
Whether there are differences between the two. For patients with CKD, only measuring 6 echo chain under the conditions of renal cortex and medulla of R_2 ~ * values. Paper pulp normal kidney
Quality R_2 ~ * values compared using the Wilcoxon paired signed rank test; using 6-echo echo-chain and 12 chain 3.0T BOLD-MRI in
Measuring renal cortex and medulla R_2 ~ * whether there are differences between the comparison, using paired t test, Bland-Altman plot and consistency of the relevant sub-
Analysis; normal control group between the two groups with CKD renal cortex and medulla R_2 ~ * mean comparisons, using Mann-Whitney U test; different renal
Able during clinical renal cortex and medulla R_2 ~ * mean comparison, using single-factor analysis of variance; points kidney R_2 ~ * kidney GFR and its sub-phase
Correlation with pathological damage analysis and correlation analysis points to ask, using spearman correlation analysis. Results: R_2 ~ * Color
Map, normal kidney cortex and medulla is relatively clear boundaries, showing the color gradually from the cortex to the medulla from blue to green, yellow, red over
Crossing changes. Kidney medulla R_2 ~ * significantly higher than the cortex, there were significant between the two statistical difference (P <0.01). 6 echo chain (
Maximum TE: 22.4 msec) and 12 echo chain (maximum TE: 45.9 msec) conditions, measured around the renal cortex and medulla R_2 ~ * values between
Do not exist significant differences (P> 0.05). Also, different echo chain conditions, repeated measured renal cortex and medulla R_2 ~ * average
Difference of -0.3 sec ~ (-1), consistency limits (mean difference ± 1.96 SD) of -1.9 ~ 1.4 sec ~ (-1), repeated measured renal cortical and medullary
Quality R_2 ~ * values with high consistency (pc = 0.983, P = 0.000). CKD group, renal cortex and medulla R_2 ~ * is significantly higher than average
Normal control group, there were significant between the two statistical difference (P <0.01). With increasing clinical stage of renal function, renal medulla R_2 ~ * mean
Was gradually increasing trend, and there are significant differences between the groups (P <0.05). LSD pairwise comparison of the results showed that the normal control group and 2
-4 Significant differences exist in the period (P <0.05). In addition, the sub-renal medullary R_2 ~ * kidney GFR values and points are significantly negative correlation
(R =- 0.415, P = 0.008), and pathological damage points there were significant positive correlation (r = 0.450, P =- 0.004). Conclusion:
In the 3.0T BOLD-MRI examination, using six echo chain (the largest TE 22.4 msec) will be able to meet the kidneys R_2 ~ * value measurements, and can
Enough to reflect the presence of hypoxia in CKD, the kidney is expected to provide an assessment of oxygenation status of non-invasive means. Degree Year: 2009
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