Patients with clinically isolated syndromes suggestive of multiple sclerosis have evidence for abnormality in normal appearing grey matter detected using the magnetization transfer ratio (MTR), a quantitative MRI meas...Patients with clinically isolated syndromes suggestive of multiple sclerosis have evidence for abnormality in normal appearing grey matter detected using the magnetization transfer ratio (MTR), a quantitative MRI measure. One potential mechanism for the decreased grey matter MTR (GM MTR) observed is trans-synaptic morphological abnormality secondary to demyelinating lesions that are in an anatomically linked pathway but remote location. We investigated this potential association by studying the location of abnormalities using voxel-based analysis of GM MTR maps in a group of 80 patients studied within 6 months of presenting with isolated optic neuritis and compared the findings with those seen in 50 age-and sex-matched healthy controls. Occipital cortex and whole brain analysis comparing all optic neuritis patients and controls revealed a selective decrease of MTR bilaterally in the visual cortex in patients [Brodmann area (BA) 17]. Whole brain analysis of patients fulfilling the McDonald criteria for multiple sclerosis (n=20) showed a lower MTR compared to controls bilaterally in the visual cortex (BA 17/18), left hippocampus, bilateral superior temporal gyrus, bilateral lenticular nuclei and the right cerebellum. There was no significant difference in the percentage of grey matter between patients and controls in the regions of abnormal MTR detected in the visual cortex. The intrinsic MTR decrease seen in patients suggests that there are structural changes in the visual cortex following an attack of optic neuritis. Potential mechanisms for this include trans-synaptic neuronal degeneration and cortical synaptic morphological changes; such abnormalities may also contribute to MTR abnormalities observed in the normal appearing grey matter in multiple sclerosis.展开更多
Patients with clinically isolated syndromes suggestive of multiple sclerosis have evidence for abnormality in normal appearing grey matter detected using the magnetization transfer ratio (MTR), a quantitative MRI meas...Patients with clinically isolated syndromes suggestive of multiple sclerosis have evidence for abnormality in normal appearing grey matter detected using the magnetization transfer ratio (MTR), a quantitative MRI measure. One potential mechanism for the decreased grey matter MTR (GM MTR) observed is trans-synaptic morphological abnormality secondary to demyelinating lesions that are in an anatomically linked pathway but remote location. We investigated this potential association by studying the location of abnormalities using voxel-based analysis of GM MTR maps in a group of 80 patients studied within 6 months of presenting with isolated optic neuritis and compared the findings with those seen in 50 age-and sex-matched healthy controls. Occipital cortex and whole brain analysis comparing all optic neuritis patients and controls revealed a selective decrease of MTR bilaterally in the visual cortex in patients [Brodmann area (BA) 17]. Whole brain analysis of patients fulfilling the McDonald criteria for multiple sclerosis (n = 20) showed a lower MTR compared to controls bilaterally in the visual cortex (BA 17/18), left hippocampus, bilateral superior temporal gyrus, bilateral lenticular nuclei and the right cerebellum. There was no significant difference in the percentage of grey matter between patients and controls in the regions of abnormal MTR detected in the visual cortex. The intrinsic MTR decrease seen in patients suggests that there are structural changes in the visual cortex following an attack of optic neuritis. Potential mechanisms for this include trans-synaptic neuronal degeneration and cortical synaptic morphological changes; such abnormalities may also contribute to MTR abnormalities observed in the normal appearing grey matter in multiple sclerosis.展开更多
Over the past few decades,various types of metal-sandwich structures have been synthesized and reported,which significantly advanced organometallic chemistry and contributed to numerous applications.However,charge-neu...Over the past few decades,various types of metal-sandwich structures have been synthesized and reported,which significantly advanced organometallic chemistry and contributed to numerous applications.However,charge-neutral rare-earth(Ⅲ)sandwich structure s based on compact aromatic ligands still remained unexplored due to the challenges in their synthesis.Nevertheless,the immense potential of this type of structure in building high-performance single-molecule magnets(SMMs)has compelled us to overcome these synthetic obstacles.Herein,we aimed to isolate such complexes in a general formula of[(Ring1)RE^(Ⅲ)(Ring2)].[(C_(4)B)^(Et4Me2NR)E^(Ⅲ)(Cp^(iPr5))](3-RE,RE=Y,Dy;(C_(4)B)^(Et4Me2N)=1-(N,N-dimethylamino)-2,3,4,5-tetraethylborolyl;CpiPr5=pentaisopropylcyclopentadienyl)were successfully obtained via the salt-metathesis reaction of the precursor[RE^(Ⅲ)(Cp^(iPr5))(BH4)2-(THF)](1-RE,RE=Y,Dy;THF=tetrahydrofuran)and the new aminoborolide ligand[Na_(2)(C_(4)B)^(Ef4Me2N)(THF)_(2)]_(2)(2),which represent the first neutral rare-earth(Ⅲ)-sandwich complexes ligated by compact aromatic ligands.Both complexes 3-RE were characterized by single-crystal X-ray diffraction,elemental analysis,UV-Vis-NIR and FTIR.Diamagnetic 3-Y was studied by NMR spectroscopy.Static and dynamic magnetic properties of 3-Dy were investigated by SQUID magnetometry,showing a high anisotropy barrier of 785(12)cm-1and open hysteresis loops up to 12 K.The bonding of nitrogen to dysprosium(Ⅲ)near the equatorial plane lowers the anisotropy,and a bulkier ligand in the future should be able to avoid this.This work not only demonstrate s that such type of neutral rare-earth(Ⅲ)-sandwich complexe s is totally synthetically feasible,but also paves the way for the development of high-performance SMMs.展开更多
Magnetoelectric(ME)multiferroic materials have unique advantages in low-power and high-density information storage,because they can simultaneously display ferroelectricity and ferromagnetism.However,research on how to...Magnetoelectric(ME)multiferroic materials have unique advantages in low-power and high-density information storage,because they can simultaneously display ferroelectricity and ferromagnetism.However,research on how to construct air-stable highperformance ME single-molecule magnets(SMMs)is nonexistent.Herein,by introducing homochirality while reducing molecular symmetry,two doubledecker Dy(III)enantiomers adopting the polar space group P2_(1) and exhibiting excellent thermal stability were obtained.They displayed zero field SMM behavior with an anisotropy barrier(Ueff)of ca.100 cm^(−1).This work establishes a rational chemical design strategy for crystallizing SMMs in polar space groups and elucidates the direction for future research,that is,engineering small-size high-performance SMMs.展开更多
文摘Patients with clinically isolated syndromes suggestive of multiple sclerosis have evidence for abnormality in normal appearing grey matter detected using the magnetization transfer ratio (MTR), a quantitative MRI measure. One potential mechanism for the decreased grey matter MTR (GM MTR) observed is trans-synaptic morphological abnormality secondary to demyelinating lesions that are in an anatomically linked pathway but remote location. We investigated this potential association by studying the location of abnormalities using voxel-based analysis of GM MTR maps in a group of 80 patients studied within 6 months of presenting with isolated optic neuritis and compared the findings with those seen in 50 age-and sex-matched healthy controls. Occipital cortex and whole brain analysis comparing all optic neuritis patients and controls revealed a selective decrease of MTR bilaterally in the visual cortex in patients [Brodmann area (BA) 17]. Whole brain analysis of patients fulfilling the McDonald criteria for multiple sclerosis (n=20) showed a lower MTR compared to controls bilaterally in the visual cortex (BA 17/18), left hippocampus, bilateral superior temporal gyrus, bilateral lenticular nuclei and the right cerebellum. There was no significant difference in the percentage of grey matter between patients and controls in the regions of abnormal MTR detected in the visual cortex. The intrinsic MTR decrease seen in patients suggests that there are structural changes in the visual cortex following an attack of optic neuritis. Potential mechanisms for this include trans-synaptic neuronal degeneration and cortical synaptic morphological changes; such abnormalities may also contribute to MTR abnormalities observed in the normal appearing grey matter in multiple sclerosis.
文摘Patients with clinically isolated syndromes suggestive of multiple sclerosis have evidence for abnormality in normal appearing grey matter detected using the magnetization transfer ratio (MTR), a quantitative MRI measure. One potential mechanism for the decreased grey matter MTR (GM MTR) observed is trans-synaptic morphological abnormality secondary to demyelinating lesions that are in an anatomically linked pathway but remote location. We investigated this potential association by studying the location of abnormalities using voxel-based analysis of GM MTR maps in a group of 80 patients studied within 6 months of presenting with isolated optic neuritis and compared the findings with those seen in 50 age-and sex-matched healthy controls. Occipital cortex and whole brain analysis comparing all optic neuritis patients and controls revealed a selective decrease of MTR bilaterally in the visual cortex in patients [Brodmann area (BA) 17]. Whole brain analysis of patients fulfilling the McDonald criteria for multiple sclerosis (n = 20) showed a lower MTR compared to controls bilaterally in the visual cortex (BA 17/18), left hippocampus, bilateral superior temporal gyrus, bilateral lenticular nuclei and the right cerebellum. There was no significant difference in the percentage of grey matter between patients and controls in the regions of abnormal MTR detected in the visual cortex. The intrinsic MTR decrease seen in patients suggests that there are structural changes in the visual cortex following an attack of optic neuritis. Potential mechanisms for this include trans-synaptic neuronal degeneration and cortical synaptic morphological changes; such abnormalities may also contribute to MTR abnormalities observed in the normal appearing grey matter in multiple sclerosis.
基金supported by the National High-Level Young Talents Programthe National Natural Science Foundation of China(22371031,22131011,21821003)the funding provided by the University of Oulu(Kvantum Institute)。
文摘Over the past few decades,various types of metal-sandwich structures have been synthesized and reported,which significantly advanced organometallic chemistry and contributed to numerous applications.However,charge-neutral rare-earth(Ⅲ)sandwich structure s based on compact aromatic ligands still remained unexplored due to the challenges in their synthesis.Nevertheless,the immense potential of this type of structure in building high-performance single-molecule magnets(SMMs)has compelled us to overcome these synthetic obstacles.Herein,we aimed to isolate such complexes in a general formula of[(Ring1)RE^(Ⅲ)(Ring2)].[(C_(4)B)^(Et4Me2NR)E^(Ⅲ)(Cp^(iPr5))](3-RE,RE=Y,Dy;(C_(4)B)^(Et4Me2N)=1-(N,N-dimethylamino)-2,3,4,5-tetraethylborolyl;CpiPr5=pentaisopropylcyclopentadienyl)were successfully obtained via the salt-metathesis reaction of the precursor[RE^(Ⅲ)(Cp^(iPr5))(BH4)2-(THF)](1-RE,RE=Y,Dy;THF=tetrahydrofuran)and the new aminoborolide ligand[Na_(2)(C_(4)B)^(Ef4Me2N)(THF)_(2)]_(2)(2),which represent the first neutral rare-earth(Ⅲ)-sandwich complexes ligated by compact aromatic ligands.Both complexes 3-RE were characterized by single-crystal X-ray diffraction,elemental analysis,UV-Vis-NIR and FTIR.Diamagnetic 3-Y was studied by NMR spectroscopy.Static and dynamic magnetic properties of 3-Dy were investigated by SQUID magnetometry,showing a high anisotropy barrier of 785(12)cm-1and open hysteresis loops up to 12 K.The bonding of nitrogen to dysprosium(Ⅲ)near the equatorial plane lowers the anisotropy,and a bulkier ligand in the future should be able to avoid this.This work not only demonstrate s that such type of neutral rare-earth(Ⅲ)-sandwich complexe s is totally synthetically feasible,but also paves the way for the development of high-performance SMMs.
基金This work was supported by the National Natural Science Foundation of China(no.21871247)the Key Research Program of Frontier Sciences,CAS(no.ZDBSLY-SLH023)+2 种基金the Key Research Program of the Chinese Academy of Sciences(no.ZDRW-CN-2021-3-3)the Academy of Finland(grant no.332294)Computational resources were provided by CSC-IT Center for Science in Finland and the Finnish Grid and Cloud Infrastructure(persistent identifier urn:nbn:fi:research-infras-2016072533).
文摘Magnetoelectric(ME)multiferroic materials have unique advantages in low-power and high-density information storage,because they can simultaneously display ferroelectricity and ferromagnetism.However,research on how to construct air-stable highperformance ME single-molecule magnets(SMMs)is nonexistent.Herein,by introducing homochirality while reducing molecular symmetry,two doubledecker Dy(III)enantiomers adopting the polar space group P2_(1) and exhibiting excellent thermal stability were obtained.They displayed zero field SMM behavior with an anisotropy barrier(Ueff)of ca.100 cm^(−1).This work establishes a rational chemical design strategy for crystallizing SMMs in polar space groups and elucidates the direction for future research,that is,engineering small-size high-performance SMMs.
