The orientation angle is an important parameter that reflects the structure of molecules at interfaces. In order to obtain this parameter, second order nonlinear spectroscopic techniques including second harmonic gene...The orientation angle is an important parameter that reflects the structure of molecules at interfaces. In order to obtain this parameter, second order nonlinear spectroscopic techniques including second harmonic generation (SHG) and sum frequency generation-vibrational spec- troscopy (SFG-VS) have been successfully applied through analysis of the nonlinear signal from various polarizations. In some SHG and SFG-VS experiments, total internal reflection (TIR) configuration has been adopted to get enhanced signals. However, the reports on the detailed procedure of the polarization analysis and the calculation of the orientation angle of interracial molecules under TIR configuration are still very few. In this paper, we mea- sured the orientation angles of two molecules at the hexadecane-water interface under TIR and Non-TIR experimental configurations. The results measured from polarization analysis in TIR configuration consist with those obtained from Non-TIR configuration. This work demonstrates the feasibility and accuracy of polarization analysis in the determination of the orientation angle of molecules at the interfaces under TIR-SHG configuration.展开更多
The constructive or destructive spectral interference between the molecular groups oriented up and down at the interface in the sum-frequency generation (SFG) spectra provides a direct measurement of the absolute or...The constructive or destructive spectral interference between the molecular groups oriented up and down at the interface in the sum-frequency generation (SFG) spectra provides a direct measurement of the absolute orientation of these molecular groups. This simple approach can be employed to interrogate absolute molecular orientations other than using the complex absolute phase measurement in the SFG studies. We used the -CN group in the p-cyanophenol (PCP) molecule as the internal phase standard, and we measured the phases of the SFG fields of the -CN groups in the 3,5-dimethyl-4-hydroxy-benzonitrile (35DMHBN) and 2,6-dimethyl-4-hydroxy-benzonitrile (26DMHBN) at the air/water interface by measuring the SFG spectra of the aqueous surfaces of the mixtures of the PCP, 35DMHBN, and 26DMHBN solutions. The results showed that the 35DMHBN had its -CN group pointing into the aqueous phase; while the 26DMHBN, similar to the PCP, had its -CN group pointing away from the aqueous phase. The tilt angles of the -CN group for both the 35DMHBN and 26DMHBN molecules at the air/water interface were around 25°-45° from the interface normal. These results provided insights on the understanding of the detailed balance of the competing factors, such as solvation of the polar head groups, hydrogen bonding and hydrophobic effects, etc., on influencing the absolute molecular orientation at the air/water interface.展开更多
The watermiscible room temperature ionic liquid 1butyl3methylimidazolium tetrafluorob orate ([bmim] [BF4]) is a model system for studying the interactions between ionic liquid and water molecules. In this work the o...The watermiscible room temperature ionic liquid 1butyl3methylimidazolium tetrafluorob orate ([bmim] [BF4]) is a model system for studying the interactions between ionic liquid and water molecules. In this work the orientational structure of the low concentrated aqueous solution of [bmim] [BF4] at the air/liquid interface was investigated by sum frequency gener ation vibrational spectroscopy. It has been found that at very low concentrations, the butyl chain exhibited a significant gauche defect, indicating a disordered conformation; and the cation ring oriented with a fairly small tilting angle at the surface. When the concentration increased, the cation ring tended to lie flat at the surface, and the gauche defects of the butyl chain decreased due to the intermolecular chainchain interactions and the consequent more ordered interfacial molecular arrangement. Additionally, the antisymmetric stretching mode in the PPP and SPS spectra exhibited a peak shift, showing that there exists more than one kind of orientation or chemical environment for the butyl CH3 group. These results may shed new light on understanding the surface behavior of watermiscible ionic liquids as well as the imidazolium based surfactants.展开更多
The development of the recrystallization texture of the alloy AA3104 was investigated by analysis of orientation distribution functions determined by X-ray diffraction,supported by EBSD local texture analysis.A typic...The development of the recrystallization texture of the alloy AA3104 was investigated by analysis of orientation distribution functions determined by X-ray diffraction,supported by EBSD local texture analysis.A typical β-fiber with nearly 20%Bs orientation {011}211 was detected in the final hot rolled sheet.At the beginning of annealing at 350 ℃,the cube component{001}100 got a sharp increase.TEM results show that the growth of both number and size of precipitation appears to inhibit the advantage of Cube orientation {001}100 notably after annealing at 350 ℃ for 15 min.Finally,it comes out to be a random distributed orientation by full recry stallization.展开更多
Nanocomposite fibers have attracted intensive attentions owing to their promising applications in various fields. However, the fabrication of nanocomposite fibers with super toughness and strong strength under mild co...Nanocomposite fibers have attracted intensive attentions owing to their promising applications in various fields. However, the fabrication of nanocomposite fibers with super toughness and strong strength under mild conditions remains a great challenge. Here we present a facile flow-induced assembly strategy for the development of super-tough and strong nanocomposite fibers with highly ordered carbon nanotubes (CNTs), which can be induced by directional and fast flow on a grooved hydrogel surface. The prepared nanocomposite fibers show excellent mechanical properties, with a tensile strength up to 643±27 MPa and toughness as high as 77.3±3.4 MJ m^-3 at ultimate strain of 14.8±1.5%. This versatile and efficient flow-induced alignment strategy represents a promising direction for the development of high-performance nanocomposites for practical applications.展开更多
OBJECTIVE:To observe the effect of tetrahydroxy stilbene glucoside(TSG) on the behavior of APP695V717 I transgenic mouse models and the expression of autophagy-associated proteins Beclin-1and LC3-Ⅱ.METHODS:Forty 3-mo...OBJECTIVE:To observe the effect of tetrahydroxy stilbene glucoside(TSG) on the behavior of APP695V717 I transgenic mouse models and the expression of autophagy-associated proteins Beclin-1and LC3-Ⅱ.METHODS:Forty 3-month-old APP695V717 I transgenic mice were randomized equally into either a TSG group(n = 20) or a model group(n = 20).A normal control group consisted of C57BL/6J mice of the same age and background(n = 20).The TSG group received TSG intragastric administration for1 month.Behavior was measured using the Morris water maze and the Y-maze tests.Changes in protein expression and mRNA of autophagy-associated Beclin-1 and LC3-Ⅱ in mice hippocampus were detected by western blot and Reverse Transcription-Polymerase Chain Reaction(RT-PCR) analyses.RESULTS:The number of electric-stimulus escapes significantly increased and the Morris water maze test showed prolonged escape latency,greater swimming distance,less time taken to cross the exact former platform location in the model group,and increased mRNA and protein expressions of Beclin-1 and LC3-Ⅱ compared with the control group(P < 0.05).The TSG group showed a decrease in the number of electric-stimulus escapes,shorter escape latency and swimming distance,greater time taken to cross the exact former platform location,and decreased mRNA and protein expressions of Beclin-1 and LC3-Ⅱ compared with the model group(P< 0.05).CONCLUSION:These results indicate that tetrahydroxy stilbene glucoside can decrease expressions of Beclin-1 and LC3-Ⅱ in the autophagy pathway.It can attenuate injury to endoplasmic reticulum functions caused by Ab neurotoxicity,improving learning,memorizing,and spatial orientation behavior in mice.展开更多
Self-diffusion of water has been investigated by molecular dynamics simulations. It was found that the preference of the direction in self-diffusion of water is orientation dependent in a finite time. For a time of-lO...Self-diffusion of water has been investigated by molecular dynamics simulations. It was found that the preference of the direction in self-diffusion of water is orientation dependent in a finite time. For a time of-lO0 ps, there are more possibilities for water molecules moving along the initial dipole orientation than in the opposite direction. This reveals that self-diffusion of water molecules is asymmetric in a finite time. We tested four water models and found that they all show similar asymmetric diffusion, indicating that asymmetric diffusion of water is intrinsic behavior rather than induced by the water model. These results are important for understanding and application of asymmetric diffusion in research fields such as biological water and confined water in small dimensions.展开更多
文摘The orientation angle is an important parameter that reflects the structure of molecules at interfaces. In order to obtain this parameter, second order nonlinear spectroscopic techniques including second harmonic generation (SHG) and sum frequency generation-vibrational spec- troscopy (SFG-VS) have been successfully applied through analysis of the nonlinear signal from various polarizations. In some SHG and SFG-VS experiments, total internal reflection (TIR) configuration has been adopted to get enhanced signals. However, the reports on the detailed procedure of the polarization analysis and the calculation of the orientation angle of interracial molecules under TIR configuration are still very few. In this paper, we mea- sured the orientation angles of two molecules at the hexadecane-water interface under TIR and Non-TIR experimental configurations. The results measured from polarization analysis in TIR configuration consist with those obtained from Non-TIR configuration. This work demonstrates the feasibility and accuracy of polarization analysis in the determination of the orientation angle of molecules at the interfaces under TIR-SHG configuration.
基金Ⅵ. ACKNOWLEDGMENTS Hong-fei Wang thanks the support by the National Natural Science Foundation of China (No.20373076, No.20425309, and No.20533070) and the Ministry of Science and Technology of China (No.2007CB815205). Zhi-feng Cui thanks the support by the Natural Science Foundation of China (No.10674002) and the Natural Science Foundation of Anhui Province (No.ZD2007001-1).
文摘The constructive or destructive spectral interference between the molecular groups oriented up and down at the interface in the sum-frequency generation (SFG) spectra provides a direct measurement of the absolute orientation of these molecular groups. This simple approach can be employed to interrogate absolute molecular orientations other than using the complex absolute phase measurement in the SFG studies. We used the -CN group in the p-cyanophenol (PCP) molecule as the internal phase standard, and we measured the phases of the SFG fields of the -CN groups in the 3,5-dimethyl-4-hydroxy-benzonitrile (35DMHBN) and 2,6-dimethyl-4-hydroxy-benzonitrile (26DMHBN) at the air/water interface by measuring the SFG spectra of the aqueous surfaces of the mixtures of the PCP, 35DMHBN, and 26DMHBN solutions. The results showed that the 35DMHBN had its -CN group pointing into the aqueous phase; while the 26DMHBN, similar to the PCP, had its -CN group pointing away from the aqueous phase. The tilt angles of the -CN group for both the 35DMHBN and 26DMHBN molecules at the air/water interface were around 25°-45° from the interface normal. These results provided insights on the understanding of the detailed balance of the competing factors, such as solvation of the polar head groups, hydrogen bonding and hydrophobic effects, etc., on influencing the absolute molecular orientation at the air/water interface.
文摘The watermiscible room temperature ionic liquid 1butyl3methylimidazolium tetrafluorob orate ([bmim] [BF4]) is a model system for studying the interactions between ionic liquid and water molecules. In this work the orientational structure of the low concentrated aqueous solution of [bmim] [BF4] at the air/liquid interface was investigated by sum frequency gener ation vibrational spectroscopy. It has been found that at very low concentrations, the butyl chain exhibited a significant gauche defect, indicating a disordered conformation; and the cation ring oriented with a fairly small tilting angle at the surface. When the concentration increased, the cation ring tended to lie flat at the surface, and the gauche defects of the butyl chain decreased due to the intermolecular chainchain interactions and the consequent more ordered interfacial molecular arrangement. Additionally, the antisymmetric stretching mode in the PPP and SPS spectra exhibited a peak shift, showing that there exists more than one kind of orientation or chemical environment for the butyl CH3 group. These results may shed new light on understanding the surface behavior of watermiscible ionic liquids as well as the imidazolium based surfactants.
文摘The development of the recrystallization texture of the alloy AA3104 was investigated by analysis of orientation distribution functions determined by X-ray diffraction,supported by EBSD local texture analysis.A typical β-fiber with nearly 20%Bs orientation {011}211 was detected in the final hot rolled sheet.At the beginning of annealing at 350 ℃,the cube component{001}100 got a sharp increase.TEM results show that the growth of both number and size of precipitation appears to inhibit the advantage of Cube orientation {001}100 notably after annealing at 350 ℃ for 15 min.Finally,it comes out to be a random distributed orientation by full recry stallization.
基金supported by the National Key R&D Program of China(2017YFA0207800)the National Natural Science Foundation of China(21574004)+4 种基金the National Natural Science Funds for Distinguished Young Scholar(21725401)the 111 project(B14009)the Fundamental Research Funds for the Central Universitiesthe National “Young Thousand Talents Program”the China Postdoctoral Science Foundation(2017M620012)
文摘Nanocomposite fibers have attracted intensive attentions owing to their promising applications in various fields. However, the fabrication of nanocomposite fibers with super toughness and strong strength under mild conditions remains a great challenge. Here we present a facile flow-induced assembly strategy for the development of super-tough and strong nanocomposite fibers with highly ordered carbon nanotubes (CNTs), which can be induced by directional and fast flow on a grooved hydrogel surface. The prepared nanocomposite fibers show excellent mechanical properties, with a tensile strength up to 643±27 MPa and toughness as high as 77.3±3.4 MJ m^-3 at ultimate strain of 14.8±1.5%. This versatile and efficient flow-induced alignment strategy represents a promising direction for the development of high-performance nanocomposites for practical applications.
基金the National Natural Science Foundation of China(Effect of Tetrahydroxy Stilbene Glycoside on Endoplasmic Reticulum Stress Induced byβ-amyloid in Alzheimer's Disease,No.81303097 and the effect of Curcumin on Alzheimer's Disease based on PPARγ-HSP70 Pathway,No.81373794)
文摘OBJECTIVE:To observe the effect of tetrahydroxy stilbene glucoside(TSG) on the behavior of APP695V717 I transgenic mouse models and the expression of autophagy-associated proteins Beclin-1and LC3-Ⅱ.METHODS:Forty 3-month-old APP695V717 I transgenic mice were randomized equally into either a TSG group(n = 20) or a model group(n = 20).A normal control group consisted of C57BL/6J mice of the same age and background(n = 20).The TSG group received TSG intragastric administration for1 month.Behavior was measured using the Morris water maze and the Y-maze tests.Changes in protein expression and mRNA of autophagy-associated Beclin-1 and LC3-Ⅱ in mice hippocampus were detected by western blot and Reverse Transcription-Polymerase Chain Reaction(RT-PCR) analyses.RESULTS:The number of electric-stimulus escapes significantly increased and the Morris water maze test showed prolonged escape latency,greater swimming distance,less time taken to cross the exact former platform location in the model group,and increased mRNA and protein expressions of Beclin-1 and LC3-Ⅱ compared with the control group(P < 0.05).The TSG group showed a decrease in the number of electric-stimulus escapes,shorter escape latency and swimming distance,greater time taken to cross the exact former platform location,and decreased mRNA and protein expressions of Beclin-1 and LC3-Ⅱ compared with the model group(P< 0.05).CONCLUSION:These results indicate that tetrahydroxy stilbene glucoside can decrease expressions of Beclin-1 and LC3-Ⅱ in the autophagy pathway.It can attenuate injury to endoplasmic reticulum functions caused by Ab neurotoxicity,improving learning,memorizing,and spatial orientation behavior in mice.
基金supported by the National Natural Science Foundation of China(Grant Nos.11175230 and 11474299)the Innovation Program of Shanghai Municipality Education Commission,China(Grant No.14ZZ095)
文摘Self-diffusion of water has been investigated by molecular dynamics simulations. It was found that the preference of the direction in self-diffusion of water is orientation dependent in a finite time. For a time of-lO0 ps, there are more possibilities for water molecules moving along the initial dipole orientation than in the opposite direction. This reveals that self-diffusion of water molecules is asymmetric in a finite time. We tested four water models and found that they all show similar asymmetric diffusion, indicating that asymmetric diffusion of water is intrinsic behavior rather than induced by the water model. These results are important for understanding and application of asymmetric diffusion in research fields such as biological water and confined water in small dimensions.