Fluorescence resonance energy transfer （FRET） systems have broad applications in visual detection, intelligent materials, and biological imaging, all of which favor the transmission of light through multiple dimensi...Fluorescence resonance energy transfer （FRET） systems have broad applications in visual detection, intelligent materials, and biological imaging, all of which favor the transmission of light through multiple dimensions and in diverse directions. Herein, we have demonstrated multi-dimensional （0D and 2D） FRET within a multi-layer ultrathin film （UTF） by employing a layer-by-layer （LBL） assembly technique. The anionic block copolymer micelle poly（tert-butyl acrylate- co-ethyl acrylate-co-methacrylic acid） （PTBEM） is chosen as a molecular carrier for the incorporation of bis（8-hydroxyquinolate） zinc （Znq2） and open-ring merocyanine （MC） （denoted as （Znq2/MC）@PTBEM）. Alternatively, electrostatic assembly is performed with cationic layered double hydroxide （LDH） nanosheets （denoted as [（Znq2/MC）@PTBEM/LDH]n）. This [（Znq2/MC）@PTBEM/ LDH]n system offers a multi-dimensional propagation medium and ensures that the FRET donor and acceptor are located within their F6rster radii in each direction. The system demonstrates a FRET process that can be switched via alternating ultraviolet/visible （UV/vis） irradiation, with tunable blue-green/red fluorescence, resulting in a FRET efficiency as high as 81.7%. It is expected that this assembly method, which uses 0D micelles on a 2D layered material, can be extended to other systems for further development of multi-dimensional FRET.展开更多
Styrene-isoprene-styrene（SIS） block copolymer was modified into epoxidized styrene-isoprene-styrene（ESIS） block copolymer with performic acid generated in situ from hydrogen peroxide and formic acid.The structure ...Styrene-isoprene-styrene（SIS） block copolymer was modified into epoxidized styrene-isoprene-styrene（ESIS） block copolymer with performic acid generated in situ from hydrogen peroxide and formic acid.The structure and property of ESIS were characterized by Fourier transform infrared（FT-IR） spectroscopy,gel permeation chromatography（GPC）,thermogravimetric/differential thermogravimetric（TG/DTG）,melt flow rate（MFR） and dynamic mechanical analysis（DMA）,and the reaction mechanism in the process of epoxidation was analyzed.The results showed that C=C double bonds of 1,4-structure were more active than that of 3,4-structure in polyisoprene chains.With epoxidation reaction proceeding,the whole tendency of molecular weight increased and molecular weight distribution widened,and MFR firstly increased and latterly decreased.The heat resistance of ESIS was superior to that of SIS.When SIS was changed into ESIS with 15.3% of mass fraction of epoxide groups,Tg of polyisoprene chains increased from-45.3 ℃ to 10.9 ℃.In the earlier period of epoxidation,some molecular chains ruptured and new substances with low molecular weight formed.However,in the latter period,crosslinking reaction between molecular chains which was initiated by epoxide groups or C=C double bonds occurred and crosslinked insoluble substances came into being.展开更多
Tumefactive demyelinating lesions (TDLs) are often misdiagnosed as brain tumors. To identify imaging characteristics of TDLs for their proper diagnosis, their differences from malignant gliomas, etc., were investigate...Tumefactive demyelinating lesions (TDLs) are often misdiagnosed as brain tumors. To identify imaging characteristics of TDLs for their proper diagnosis, their differences from malignant gliomas, etc., were investigated based on 3-Tesla magnetic resonance imaging (MRI) and MR spectroscopy data that was obtained from 5 patients diagnosed with TDLs in our hospital. MfRI displayed a paraventricular lesion with a maximum diameter of ≥2 cm. Diffusion-weighted imaging (DWI) displayed a region of bright signal intensity at the margin of the lesion, and apparent diffusion coefficient (ADC) imaging displayed high signal intensity at the core of the lesion. The mass effect was mild relative to the size of the lesion, and the edema around the lesion was mild to moderate. Gadolinium-enhanced MRI displayed a characteristic open-ring sign, in which the ring of enhancement was incomplete (open towards the cortex), with the medullary vein running through the lesion, resulting in the enhancement of the surrounding area. MR spectroscopy displayed an increase in the choline peak, a decrease in the N-acetyl aspartate (NAA) peak, the presence of lactate/lipid peaks, and the presence of β, γ-glutamate-glutamine (GLX) peaks that are slightly shifted to a higher resonance frequency (2.1 - 2.4 ppm) from the NAA peak. Taken together, the following main characteristics were identified as imaging features of TDLs: bright rim on DWI, a high signal core on ADC imaging, an open-ring sign, and β, γ-GLX peaks on proton MR spectroscopy. We concluded that the key to the improvement of neurological symptoms of patients is the prompt initiation of steroid treatment following the accurate diagnosis of TDLs.展开更多
Functional groups on the rim of open-cage fullerenes usually exhibit different reactivity from those in classical organic molecules due to the unique spherical structure of fullerenes.The present work shows a sequence...Functional groups on the rim of open-cage fullerenes usually exhibit different reactivity from those in classical organic molecules due to the unique spherical structure of fullerenes.The present work shows a sequence of lactone opening,imino hydrolysis,aminal formation and imine formation processes during the reaction of aniline with the open-cage compound 1 with functional groups including lactone on the rim of the orifice.Single crystal X-ray diffraction analysis confirmed the structure of the product.展开更多
基金This work was supported by the National Basic Research Program of China （No. 2014CB932104）, the National Natural Science Foundation of China （NSFC）, and the Fundamental Research Funds for the Central Universities （No. YS1406）. M. W. appreciates the China National Science Funds for Distinguished Young Scholars of China.
文摘Fluorescence resonance energy transfer （FRET） systems have broad applications in visual detection, intelligent materials, and biological imaging, all of which favor the transmission of light through multiple dimensions and in diverse directions. Herein, we have demonstrated multi-dimensional （0D and 2D） FRET within a multi-layer ultrathin film （UTF） by employing a layer-by-layer （LBL） assembly technique. The anionic block copolymer micelle poly（tert-butyl acrylate- co-ethyl acrylate-co-methacrylic acid） （PTBEM） is chosen as a molecular carrier for the incorporation of bis（8-hydroxyquinolate） zinc （Znq2） and open-ring merocyanine （MC） （denoted as （Znq2/MC）@PTBEM）. Alternatively, electrostatic assembly is performed with cationic layered double hydroxide （LDH） nanosheets （denoted as [（Znq2/MC）@PTBEM/LDH]n）. This [（Znq2/MC）@PTBEM/ LDH]n system offers a multi-dimensional propagation medium and ensures that the FRET donor and acceptor are located within their F6rster radii in each direction. The system demonstrates a FRET process that can be switched via alternating ultraviolet/visible （UV/vis） irradiation, with tunable blue-green/red fluorescence, resulting in a FRET efficiency as high as 81.7%. It is expected that this assembly method, which uses 0D micelles on a 2D layered material, can be extended to other systems for further development of multi-dimensional FRET.
文摘Styrene-isoprene-styrene（SIS） block copolymer was modified into epoxidized styrene-isoprene-styrene（ESIS） block copolymer with performic acid generated in situ from hydrogen peroxide and formic acid.The structure and property of ESIS were characterized by Fourier transform infrared（FT-IR） spectroscopy,gel permeation chromatography（GPC）,thermogravimetric/differential thermogravimetric（TG/DTG）,melt flow rate（MFR） and dynamic mechanical analysis（DMA）,and the reaction mechanism in the process of epoxidation was analyzed.The results showed that C=C double bonds of 1,4-structure were more active than that of 3,4-structure in polyisoprene chains.With epoxidation reaction proceeding,the whole tendency of molecular weight increased and molecular weight distribution widened,and MFR firstly increased and latterly decreased.The heat resistance of ESIS was superior to that of SIS.When SIS was changed into ESIS with 15.3% of mass fraction of epoxide groups,Tg of polyisoprene chains increased from-45.3 ℃ to 10.9 ℃.In the earlier period of epoxidation,some molecular chains ruptured and new substances with low molecular weight formed.However,in the latter period,crosslinking reaction between molecular chains which was initiated by epoxide groups or C=C double bonds occurred and crosslinked insoluble substances came into being.
文摘Tumefactive demyelinating lesions (TDLs) are often misdiagnosed as brain tumors. To identify imaging characteristics of TDLs for their proper diagnosis, their differences from malignant gliomas, etc., were investigated based on 3-Tesla magnetic resonance imaging (MRI) and MR spectroscopy data that was obtained from 5 patients diagnosed with TDLs in our hospital. MfRI displayed a paraventricular lesion with a maximum diameter of ≥2 cm. Diffusion-weighted imaging (DWI) displayed a region of bright signal intensity at the margin of the lesion, and apparent diffusion coefficient (ADC) imaging displayed high signal intensity at the core of the lesion. The mass effect was mild relative to the size of the lesion, and the edema around the lesion was mild to moderate. Gadolinium-enhanced MRI displayed a characteristic open-ring sign, in which the ring of enhancement was incomplete (open towards the cortex), with the medullary vein running through the lesion, resulting in the enhancement of the surrounding area. MR spectroscopy displayed an increase in the choline peak, a decrease in the N-acetyl aspartate (NAA) peak, the presence of lactate/lipid peaks, and the presence of β, γ-glutamate-glutamine (GLX) peaks that are slightly shifted to a higher resonance frequency (2.1 - 2.4 ppm) from the NAA peak. Taken together, the following main characteristics were identified as imaging features of TDLs: bright rim on DWI, a high signal core on ADC imaging, an open-ring sign, and β, γ-GLX peaks on proton MR spectroscopy. We concluded that the key to the improvement of neurological symptoms of patients is the prompt initiation of steroid treatment following the accurate diagnosis of TDLs.
基金the National Natural Science Foundation of China(Nos.21272013 and 21132007)the Major State Basic Research Development Program(No.2011CB808401).
文摘Functional groups on the rim of open-cage fullerenes usually exhibit different reactivity from those in classical organic molecules due to the unique spherical structure of fullerenes.The present work shows a sequence of lactone opening,imino hydrolysis,aminal formation and imine formation processes during the reaction of aniline with the open-cage compound 1 with functional groups including lactone on the rim of the orifice.Single crystal X-ray diffraction analysis confirmed the structure of the product.
