Objective： To discuss the feasibility and clinical value of high-resolution magnetic resonance vessel wall imaging （HRMR VWI） for intracranial arterial stenosis. Date Sources： We retrieved information from PubMed ...Objective： To discuss the feasibility and clinical value of high-resolution magnetic resonance vessel wall imaging （HRMR VWI） for intracranial arterial stenosis. Date Sources： We retrieved information from PubMed database up to December 2015, using various search terms including vessel wall imaging （VWI）, high-resolution magnetic resonance imaging, intracranial arterial stenosis, black blood, and intracranial atherosclerosis. Study Selection： We reviewed peer-reviewed articles printed in English on imaging technique of VWI and characteristic findings of various intracranial vasculopathies on VWI. We organized this data to explain the value of VWI in clinical application. Results： VWI with black blood technique could provide high-quality images with submillimeter voxel size, and display both the vessel wall and lumen of intracranial artery simultaneously. Various intracranial vasculopathies （atherosclerotic or nonatherosclerotic） had differentiating features including pattern of wall thickening, enhancement, and vessel remodeling on VWI. This technique could be used for determining causes of stenosis, identification of stroke mechanism, risk-stratifying patients, and directing therapeutic management in clinical practice. In addition, a new morphological classification based on VWI could be established for predicting the efficacy of endovascular therapy. Conclusions： This review highlights the value of HRMR VWI for discrimination of different intracranial vasculopathies and directing therapeutic management.展开更多
Background： There are few studies for evaluating plaque characteristics of nonstenotic basilar arteries （BA）. Our aim was to determine entire BA plaques with a three-dimensional volumetric isotropic turbo spin-echo...Background： There are few studies for evaluating plaque characteristics of nonstenotic basilar arteries （BA）. Our aim was to determine entire BA plaques with a three-dimensional volumetric isotropic turbo spin-echo acquisition （VISTA） and investigate the differences between the patients with and without isolated pontine infarction （IPI）. Methods： Twenty-four consecutive symptomatic patients with nonstenotic BA on time of flight magnetic resonance angiography （TOF MRA） were enrolled from China-Japan Friendship Hospital between January 2014 and December 2014. BA was classified as ＂normal＂ or ＂irregular＂ based on TOF MRA, and ＂normal wall＂, ＂slight wall-thickening＂, and ＂plaque＂ based on three-dimensional VISTA images. Outcomes from MRA and VISTA were compared. Patients were categorized as IPI and non-lPl groups based on the diffusion-weighted imaging. Clinical and plaque characteristics were compared between the two groups. Results： A total of 1024 image slices including 311 （30.37%） plaque slices, 427 （41.70%） slight wall-thickening slices, and 286 （27.93%） normal wall slices for the entire BA from 23 patients were finally included for analysis. VISTA images detected plaques in all the 9 （100%） irregular MRA patients and 7 of 14 （50%） normal MRA patients. IPl was found in 11 （47.83%） patients. Compared to non-IPI group, the IPI group had a higher percentage of plaque slices （P = 0.001 ） and lower percentage of normal wall slices （P = 0.014） than non-IPl group. Conclusions： Three-dimensional V1STA images enable detection of BA plaques not visualized by MRA. BA plaques could be found in both the IPl and non-IPl group. However, IPI group showed plaques more extensively in BA than the non-IPI group.展开更多
In this paper we will summarize the progress in the development of the Chinese Space Solar Telescope (SST) during the past few years. The main scientific objective of SST is to observe the fundamental structure of sol...In this paper we will summarize the progress in the development of the Chinese Space Solar Telescope (SST) during the past few years. The main scientific objective of SST is to observe the fundamental structure of solar magnetic field with its 1-m optical telescope. The success of 1-m Swedish Solar Telescope and Hinode underscores the importance of this 1-m space telescope. In addition, some key technical problems have been solved.展开更多
High-resolution nuclear magnetic resonance （NMR） is one of the most powerful tools for analyzing molecular structures and dynamics. Magnetic field homogeneity is required for conventional high-resolution spectra. Ho...High-resolution nuclear magnetic resonance （NMR） is one of the most powerful tools for analyzing molecular structures and dynamics. Magnetic field homogeneity is required for conventional high-resolution spectra. However, there are many chemical and/or biological circumstances where the spatial homogeneities of the magnetic fields are degraded. Intense solvent signal is another obstacle for obtaining high-resolution spectra, especially in in vivo and in situ NMR spectroscopy. In this paper, a new pulse sequence based on intermolecular multiple quantum coherence （iMQC） was reported. This sequence can effectively remove the effect of magnetic field inhomogeneity and suppress the solvent signal. It can recover the spectral information such as chemical shifts, coupling constants, multiplet patterns, and relative peak areas in inhomogeneous fields. Theoretical analyses and experimental verifications are presented to demonstrate the feasibility of this method.展开更多
Core-shell structured magnetic wrinkled organosilica-based metal-enzyme integrated catalysts were synthesized,and their catalytic performances were studied in the chemoenzymatic dynamic kinetic resolution of chiral am...Core-shell structured magnetic wrinkled organosilica-based metal-enzyme integrated catalysts were synthesized,and their catalytic performances were studied in the chemoenzymatic dynamic kinetic resolution of chiral amines in an organic solvent,as well as in the chemoenzymatic synthesis of chiral alcohols in water.Structureperformance studies revealed the important influence of their tunable structure and composition on the optimization of activity,stability,and recyclability in chemoenzymatic catalysis.展开更多
在当今信息社会时代,需要存储的信息总量正在急剧增加。与光存储技术和半导体存储技术相比而言,磁记录技术占领着几乎90%的存储市场。磁力显微镜（magnetic force microscope,MFM）的发展与磁记录工业密切相关。然而,从1987年至今,MFM...在当今信息社会时代,需要存储的信息总量正在急剧增加。与光存储技术和半导体存储技术相比而言,磁记录技术占领着几乎90%的存储市场。磁力显微镜（magnetic force microscope,MFM）的发展与磁记录工业密切相关。然而,从1987年至今,MFM的分辨率仍然停留在50～10 nm的水平,传统思路已经很难再实现突破。本论文基于MFM探针的窄带-频率调制机理,发展接近表面磁力显微镜方法,实现对纳米结构中磁畴状态的超高分辨率成像。该工作的关键在于合理利用MFM探针的窄带-频率调制机理,优化设计动态信号处理模块,精确控制探针-样品间距（5 nm以下）,独立分离磁力像和表面像（磁力像为交流信号,原子力像为直流信号）,由此测量和解释纳米尺度磁畴结构。该方面的工作对于纳米磁畴结构的设计、核心磁性器件的研究起到非常关键的作用,为下一代磁记录技术的发展提供了新型的有力工具。展开更多
Solid state 13C nuclear magnetic resonance （NMR） spectroscopy is a common tool to study the structure of soil humic fractions; however, knowledge regarding carbon structural relationships in humic fractions is limit...Solid state 13C nuclear magnetic resonance （NMR） spectroscopy is a common tool to study the structure of soil humic fractions; however, knowledge regarding carbon structural relationships in humic fractions is limited. In this study, mobile humic acid （MHA） and recalcitrant calcium humate （CallA） fractions were extracted from eight soils collected from six US states and representing a variety of soils and ecoregions, characterized by this spectroscopic technique and analyzed for statistical significance at P 〈 0.05. We found that the abundances of COO and N-C=O functional groups in the MHA fractions were negatively correlated to soil sand content, but were positively correlated to silt, total N and soil organic carbon contents. In contrast, the abundances of the COO and N-C=O functional groups were only positively correlated to the content of clay in the CallA fractions, indicating that the two humic fractions were associated with different soil components. The two 13C NMR peaks representing alkyls and OCH3/NCH were negatively correlated to the peaks representing aromatics, aromatic C-O and N-C=O/COO. Comparison of the sets of data from 13C NMR spectroscopy and ultrahigh resolution mass spectrometry revealed that the aromatic components identified by the two methods were highly consistent. The comparison further revealed that protein in MHA was associated with, or bound to, the nonpolar alkyl groups, but a component competitively against （or complementary to） aromatic groups in the MHA composition. These observations provided insight on the internal correlations of the functional groups of soil humic fractions.展开更多
Modern computer techniques have been in use for several years to generate three-dimensional visualizations of human anatomy. Very good 3-D computer models of the human body are now available and used routinely in anat...Modern computer techniques have been in use for several years to generate three-dimensional visualizations of human anatomy. Very good 3-D computer models of the human body are now available and used routinely in anatomy instruction. These techniques are subsumed under the heading “virtual anatomy” to distinguish them from the conventional study of anatomy entailing cadavers and anatomy textbooks. Moreover, other imaging procedures (X-ray, angiography, CT and MR) are also used in virtual anatomy instruction. A recently introduced three-dimensional post-processing technique named Cinematic Rendering now makes it possible to use the output of routine CT and MR examinations as the basis for highly photo-realistic 3-D depictions of human anatomy. We have installed Cinematic Rendering (enabled for stereoscopy) in a high-definition 8K 3-D projection space that accommodates an audience of 150. The space’s projection surface measures 16 × 9 meters;images can be projected on both the front wall and the floor. A game controller can be used to operate Cinematic Rendering software so that it can generate interactive real-time depictions of human anatomy on the basis of CT and MR data sets. This prototype installation was implemented without technical problems;in day-to-day, real-world use over a period of 22 months, there were no impairments of service due to software crashes or other technical problems. We are already employing this installation routinely for educational offerings open to the public, courses for students in the health professions, and (continuing) professional education units for medical interns, residents and specialists—in, so to speak, the dissecting theater of the future.展开更多
文摘Objective： To discuss the feasibility and clinical value of high-resolution magnetic resonance vessel wall imaging （HRMR VWI） for intracranial arterial stenosis. Date Sources： We retrieved information from PubMed database up to December 2015, using various search terms including vessel wall imaging （VWI）, high-resolution magnetic resonance imaging, intracranial arterial stenosis, black blood, and intracranial atherosclerosis. Study Selection： We reviewed peer-reviewed articles printed in English on imaging technique of VWI and characteristic findings of various intracranial vasculopathies on VWI. We organized this data to explain the value of VWI in clinical application. Results： VWI with black blood technique could provide high-quality images with submillimeter voxel size, and display both the vessel wall and lumen of intracranial artery simultaneously. Various intracranial vasculopathies （atherosclerotic or nonatherosclerotic） had differentiating features including pattern of wall thickening, enhancement, and vessel remodeling on VWI. This technique could be used for determining causes of stenosis, identification of stroke mechanism, risk-stratifying patients, and directing therapeutic management in clinical practice. In addition, a new morphological classification based on VWI could be established for predicting the efficacy of endovascular therapy. Conclusions： This review highlights the value of HRMR VWI for discrimination of different intracranial vasculopathies and directing therapeutic management.
基金This study was supported by grants from China- Japan Friendship Hospital Youth Science and Technology Excellence Project （No. 2014-QNYC-A-04）, National Natural Science Foundation of China （No. 81173595, No. 30670731, No. 81070925 and No. 81471767）, and National Basic Research Program （973 Program） of China （No. 2013CB733805）.
文摘Background： There are few studies for evaluating plaque characteristics of nonstenotic basilar arteries （BA）. Our aim was to determine entire BA plaques with a three-dimensional volumetric isotropic turbo spin-echo acquisition （VISTA） and investigate the differences between the patients with and without isolated pontine infarction （IPI）. Methods： Twenty-four consecutive symptomatic patients with nonstenotic BA on time of flight magnetic resonance angiography （TOF MRA） were enrolled from China-Japan Friendship Hospital between January 2014 and December 2014. BA was classified as ＂normal＂ or ＂irregular＂ based on TOF MRA, and ＂normal wall＂, ＂slight wall-thickening＂, and ＂plaque＂ based on three-dimensional VISTA images. Outcomes from MRA and VISTA were compared. Patients were categorized as IPI and non-lPl groups based on the diffusion-weighted imaging. Clinical and plaque characteristics were compared between the two groups. Results： A total of 1024 image slices including 311 （30.37%） plaque slices, 427 （41.70%） slight wall-thickening slices, and 286 （27.93%） normal wall slices for the entire BA from 23 patients were finally included for analysis. VISTA images detected plaques in all the 9 （100%） irregular MRA patients and 7 of 14 （50%） normal MRA patients. IPl was found in 11 （47.83%） patients. Compared to non-IPI group, the IPI group had a higher percentage of plaque slices （P = 0.001 ） and lower percentage of normal wall slices （P = 0.014） than non-IPl group. Conclusions： Three-dimensional V1STA images enable detection of BA plaques not visualized by MRA. BA plaques could be found in both the IPl and non-IPl group. However, IPI group showed plaques more extensively in BA than the non-IPI group.
基金Supported by the Important Directional Project of Chinese Academy of Sciences (Grant No. KJCX2-YW-T04)the National Basic Research Program of China (Grant No. 2006CB806301)the National Natural Science Foundation of China (Grant Nos. 10878004, 10733020, and10673016)
文摘In this paper we will summarize the progress in the development of the Chinese Space Solar Telescope (SST) during the past few years. The main scientific objective of SST is to observe the fundamental structure of solar magnetic field with its 1-m optical telescope. The success of 1-m Swedish Solar Telescope and Hinode underscores the importance of this 1-m space telescope. In addition, some key technical problems have been solved.
基金Project supported by the National Natural Science Foundation of China （Nos. 10375049, 10575085） and China Postdoctoral Science Foundation.
文摘High-resolution nuclear magnetic resonance （NMR） is one of the most powerful tools for analyzing molecular structures and dynamics. Magnetic field homogeneity is required for conventional high-resolution spectra. However, there are many chemical and/or biological circumstances where the spatial homogeneities of the magnetic fields are degraded. Intense solvent signal is another obstacle for obtaining high-resolution spectra, especially in in vivo and in situ NMR spectroscopy. In this paper, a new pulse sequence based on intermolecular multiple quantum coherence （iMQC） was reported. This sequence can effectively remove the effect of magnetic field inhomogeneity and suppress the solvent signal. It can recover the spectral information such as chemical shifts, coupling constants, multiplet patterns, and relative peak areas in inhomogeneous fields. Theoretical analyses and experimental verifications are presented to demonstrate the feasibility of this method.
基金financially supported by the National Key Research and Development Program of China(No.2021YFC2104100)the National Natural Science Foundation of China(Nos.21901058,22178083 and 22078081)+2 种基金the S&T program of Hebei(Nos.21372805D,21372804D and 20372802D)the Natural Science Foundation of Tianjin City(No.20JCYBJC00530)the Natural Science Foundation of Hebei Province(No.B2022202014).
文摘Core-shell structured magnetic wrinkled organosilica-based metal-enzyme integrated catalysts were synthesized,and their catalytic performances were studied in the chemoenzymatic dynamic kinetic resolution of chiral amines in an organic solvent,as well as in the chemoenzymatic synthesis of chiral alcohols in water.Structureperformance studies revealed the important influence of their tunable structure and composition on the optimization of activity,stability,and recyclability in chemoenzymatic catalysis.
文摘在当今信息社会时代,需要存储的信息总量正在急剧增加。与光存储技术和半导体存储技术相比而言,磁记录技术占领着几乎90%的存储市场。磁力显微镜（magnetic force microscope,MFM）的发展与磁记录工业密切相关。然而,从1987年至今,MFM的分辨率仍然停留在50～10 nm的水平,传统思路已经很难再实现突破。本论文基于MFM探针的窄带-频率调制机理,发展接近表面磁力显微镜方法,实现对纳米结构中磁畴状态的超高分辨率成像。该工作的关键在于合理利用MFM探针的窄带-频率调制机理,优化设计动态信号处理模块,精确控制探针-样品间距（5 nm以下）,独立分离磁力像和表面像（磁力像为交流信号,原子力像为直流信号）,由此测量和解释纳米尺度磁畴结构。该方面的工作对于纳米磁畴结构的设计、核心磁性器件的研究起到非常关键的作用,为下一代磁记录技术的发展提供了新型的有力工具。
文摘Solid state 13C nuclear magnetic resonance （NMR） spectroscopy is a common tool to study the structure of soil humic fractions; however, knowledge regarding carbon structural relationships in humic fractions is limited. In this study, mobile humic acid （MHA） and recalcitrant calcium humate （CallA） fractions were extracted from eight soils collected from six US states and representing a variety of soils and ecoregions, characterized by this spectroscopic technique and analyzed for statistical significance at P 〈 0.05. We found that the abundances of COO and N-C=O functional groups in the MHA fractions were negatively correlated to soil sand content, but were positively correlated to silt, total N and soil organic carbon contents. In contrast, the abundances of the COO and N-C=O functional groups were only positively correlated to the content of clay in the CallA fractions, indicating that the two humic fractions were associated with different soil components. The two 13C NMR peaks representing alkyls and OCH3/NCH were negatively correlated to the peaks representing aromatics, aromatic C-O and N-C=O/COO. Comparison of the sets of data from 13C NMR spectroscopy and ultrahigh resolution mass spectrometry revealed that the aromatic components identified by the two methods were highly consistent. The comparison further revealed that protein in MHA was associated with, or bound to, the nonpolar alkyl groups, but a component competitively against （or complementary to） aromatic groups in the MHA composition. These observations provided insight on the internal correlations of the functional groups of soil humic fractions.
文摘Modern computer techniques have been in use for several years to generate three-dimensional visualizations of human anatomy. Very good 3-D computer models of the human body are now available and used routinely in anatomy instruction. These techniques are subsumed under the heading “virtual anatomy” to distinguish them from the conventional study of anatomy entailing cadavers and anatomy textbooks. Moreover, other imaging procedures (X-ray, angiography, CT and MR) are also used in virtual anatomy instruction. A recently introduced three-dimensional post-processing technique named Cinematic Rendering now makes it possible to use the output of routine CT and MR examinations as the basis for highly photo-realistic 3-D depictions of human anatomy. We have installed Cinematic Rendering (enabled for stereoscopy) in a high-definition 8K 3-D projection space that accommodates an audience of 150. The space’s projection surface measures 16 × 9 meters;images can be projected on both the front wall and the floor. A game controller can be used to operate Cinematic Rendering software so that it can generate interactive real-time depictions of human anatomy on the basis of CT and MR data sets. This prototype installation was implemented without technical problems;in day-to-day, real-world use over a period of 22 months, there were no impairments of service due to software crashes or other technical problems. We are already employing this installation routinely for educational offerings open to the public, courses for students in the health professions, and (continuing) professional education units for medical interns, residents and specialists—in, so to speak, the dissecting theater of the future.
