冷冻面制品在食品行业发展迅速,但在冻藏过程中对面制品品质影响的关键性问题仍未明朗。本研究采用小角X射线散射仪(SAXS)探讨了恒温冻藏(-18℃)对小麦面筋蛋白分子链构形、均方根旋转半径(Rg)及分子量的影响。实验发现,冻藏前,面筋蛋...冷冻面制品在食品行业发展迅速,但在冻藏过程中对面制品品质影响的关键性问题仍未明朗。本研究采用小角X射线散射仪(SAXS)探讨了恒温冻藏(-18℃)对小麦面筋蛋白分子链构形、均方根旋转半径(Rg)及分子量的影响。实验发现,冻藏前,面筋蛋白分子在500 m M乙酸溶液中链结构较疏松,属于质量分形(分形维数Dm:2.05),呈现网络状的结构。随着冻藏时间的延长,Dm值呈现下降的趋势,表明面筋蛋白高聚物的链结构逐渐疏松,同时发现在冻藏过程中面筋蛋白平均分子量和Rg都随着冻藏时间的增加也呈现下降趋势,并且Rg与Dm的变化正相关,说明在冻藏过程中由于冰晶的重结晶等作用使得高聚物发生了解聚现象,造成了面筋蛋白分子链的断裂,从而使得其网络结构的疏松。展开更多
Beamline BL16B1 at Shanghai Synchrotron Radiation Facility(SSRF) is dedicated to studying the microstructure and dynamic processes of polymers, nanomaterials, mesoporous materials, colloids, liquid crystals,metal mate...Beamline BL16B1 at Shanghai Synchrotron Radiation Facility(SSRF) is dedicated to studying the microstructure and dynamic processes of polymers, nanomaterials, mesoporous materials, colloids, liquid crystals,metal materials, etc. At present, SAXS, wide angle X-ray scattering(WAXS), simultaneous SAXS/WAXS,grazing incident SAXS, and anomalous SAXS techniques are available for end user to conduct diverse experiments at this beamline. The sample-to-detector distance is adjustable from 0.2 m to 5 m. The practicable q-range is 0.03–3.6 nm-1at incident X-ray of 10 ke V for conventional SAXS whilst a continuous q-region of0.06–33 nm-1can be achieved in simultaneous SAXS/WAXS mode. Time-resolved SAXS measurements in sub-second level was achieved by the beamline upgrating in 2013. This paper gives detailed descriptions about the status, performance and applications of the SAXS beamline.展开更多
The evolution of microstructure parameters （precipitate size and volume fraction） for two types of Al-Zn-Mg-Cu alloys （7075 and 7055） during aging has been studied by synchrotron-radiation small angle X-ray scatte...The evolution of microstructure parameters （precipitate size and volume fraction） for two types of Al-Zn-Mg-Cu alloys （7075 and 7055） during aging has been studied by synchrotron-radiation small angle X-ray scattering （SAXS）.The results show that the precipitates are only a few nanorneters for both alloys ageing even at higher temperature of 160℃ for 72 h （4.44 and 5.82 nm, respectively）. The maximum of the precipitate volume fraction increases with in creasing Zn content and is about 0.023-0.028 and 0.052-0.054, respectively. The coarsening of precipitate is consistent with LSW （Lifshitz-Slyozov-Wagner） model even at the initial stage where volume fraction is still varying.The activation energy of coarsening regime has been determined to be about 1.22±0.02 eV and 1.25±0.02 eV for alloys 7075 and 7055, respectively.展开更多
Small Angle X-ray Scattering (SAXS) experiment using Synchrotron Radiation as X-ray source was used to determine the average wall thickness of mesoporous silica prepared by condensation of tetraethylorthosilicate (TEO...Small Angle X-ray Scattering (SAXS) experiment using Synchrotron Radiation as X-ray source was used to determine the average wall thickness of mesoporous silica prepared by condensation of tetraethylorthosilicate (TEOS) using non-ionic alkylpolyethyleneoxide (AEO(9)) surfactant as templates. The results agreed with that of high-resolution TEM (HRTEM) measurement.展开更多
The mechanical properties of fibers were notably improved by incorporating 2,2＇-bis（trifluoromethyl）benzidine（TFMB） into 3,3＇,4,4＇-biphenyltetracarboxylic dianhydride（s-BPDA） and p-phenylenediamine（PPD） bac...The mechanical properties of fibers were notably improved by incorporating 2,2＇-bis（trifluoromethyl）benzidine（TFMB） into 3,3＇,4,4＇-biphenyltetracarboxylic dianhydride（s-BPDA） and p-phenylenediamine（PPD） backbone.The best strength and modulus of BPDA/PPD/TFMB polyimide（PI） fiber（diamine molar ratio of PPD/TFMB= 90/10） were 1.60 and 90 GPa,respectively,which was over two times that of BPDA/PPD PI fiber.SEM image showed that the cross-section of fibers at each stage was round and voids free.Besides,the ＂skin-core＂ and microfibrillar structure were not observed.The thermal properties of PI fibers were also investigated.The results showed that the fibers owned excellent thermal stability,moreover,the structural homogeneity of fibers were significantly improved by heat-drawn stage.The T g values were found to be around 300 °C by dynamic mechanical analysis（DMA）.Wide angle X-ray diffraction（WAXD） and small angle X-ray scattering（SAXS） experiments indicated that the order degree of longitudinal and lateral stacks,the molecular orientation and the structural homogeneity of fibers were improved in the preparation process of fibers.展开更多
文摘冷冻面制品在食品行业发展迅速,但在冻藏过程中对面制品品质影响的关键性问题仍未明朗。本研究采用小角X射线散射仪(SAXS)探讨了恒温冻藏(-18℃)对小麦面筋蛋白分子链构形、均方根旋转半径(Rg)及分子量的影响。实验发现,冻藏前,面筋蛋白分子在500 m M乙酸溶液中链结构较疏松,属于质量分形(分形维数Dm:2.05),呈现网络状的结构。随着冻藏时间的延长,Dm值呈现下降的趋势,表明面筋蛋白高聚物的链结构逐渐疏松,同时发现在冻藏过程中面筋蛋白平均分子量和Rg都随着冻藏时间的增加也呈现下降趋势,并且Rg与Dm的变化正相关,说明在冻藏过程中由于冰晶的重结晶等作用使得高聚物发生了解聚现象,造成了面筋蛋白分子链的断裂,从而使得其网络结构的疏松。
基金Supported by the National Basic Research Program of China(Nos.2011CB911104,2011CB606104,and 2011CB605604)National Natural Science Foundation of China(Nos.11305249,11005143,50903089,51273210,11405259,51303200,and 11305242)Knowledge Innovation Program of Chinese Academy of Sciences
文摘Beamline BL16B1 at Shanghai Synchrotron Radiation Facility(SSRF) is dedicated to studying the microstructure and dynamic processes of polymers, nanomaterials, mesoporous materials, colloids, liquid crystals,metal materials, etc. At present, SAXS, wide angle X-ray scattering(WAXS), simultaneous SAXS/WAXS,grazing incident SAXS, and anomalous SAXS techniques are available for end user to conduct diverse experiments at this beamline. The sample-to-detector distance is adjustable from 0.2 m to 5 m. The practicable q-range is 0.03–3.6 nm-1at incident X-ray of 10 ke V for conventional SAXS whilst a continuous q-region of0.06–33 nm-1can be achieved in simultaneous SAXS/WAXS mode. Time-resolved SAXS measurements in sub-second level was achieved by the beamline upgrating in 2013. This paper gives detailed descriptions about the status, performance and applications of the SAXS beamline.
基金This research was supported by the National Key Fun-damental Research Project of China(No.G19990649)National“863”High Technology Program of China(No.2001 A A332030).
文摘The evolution of microstructure parameters （precipitate size and volume fraction） for two types of Al-Zn-Mg-Cu alloys （7075 and 7055） during aging has been studied by synchrotron-radiation small angle X-ray scattering （SAXS）.The results show that the precipitates are only a few nanorneters for both alloys ageing even at higher temperature of 160℃ for 72 h （4.44 and 5.82 nm, respectively）. The maximum of the precipitate volume fraction increases with in creasing Zn content and is about 0.023-0.028 and 0.052-0.054, respectively. The coarsening of precipitate is consistent with LSW （Lifshitz-Slyozov-Wagner） model even at the initial stage where volume fraction is still varying.The activation energy of coarsening regime has been determined to be about 1.22±0.02 eV and 1.25±0.02 eV for alloys 7075 and 7055, respectively.
文摘Small Angle X-ray Scattering (SAXS) experiment using Synchrotron Radiation as X-ray source was used to determine the average wall thickness of mesoporous silica prepared by condensation of tetraethylorthosilicate (TEOS) using non-ionic alkylpolyethyleneoxide (AEO(9)) surfactant as templates. The results agreed with that of high-resolution TEM (HRTEM) measurement.
基金Supported by the Science & Technology Development Program of Jilin Province,China(No.20100537)
文摘The mechanical properties of fibers were notably improved by incorporating 2,2＇-bis（trifluoromethyl）benzidine（TFMB） into 3,3＇,4,4＇-biphenyltetracarboxylic dianhydride（s-BPDA） and p-phenylenediamine（PPD） backbone.The best strength and modulus of BPDA/PPD/TFMB polyimide（PI） fiber（diamine molar ratio of PPD/TFMB= 90/10） were 1.60 and 90 GPa,respectively,which was over two times that of BPDA/PPD PI fiber.SEM image showed that the cross-section of fibers at each stage was round and voids free.Besides,the ＂skin-core＂ and microfibrillar structure were not observed.The thermal properties of PI fibers were also investigated.The results showed that the fibers owned excellent thermal stability,moreover,the structural homogeneity of fibers were significantly improved by heat-drawn stage.The T g values were found to be around 300 °C by dynamic mechanical analysis（DMA）.Wide angle X-ray diffraction（WAXD） and small angle X-ray scattering（SAXS） experiments indicated that the order degree of longitudinal and lateral stacks,the molecular orientation and the structural homogeneity of fibers were improved in the preparation process of fibers.
