Using two kinds of molybdenum （Mo） powders with different micro-morphologies as raw materials, the Mo wires with a diameter of 0.18 mm and Mo sheets with thickness of 0.5 and 0.2 mm were prepared at the same process...Using two kinds of molybdenum （Mo） powders with different micro-morphologies as raw materials, the Mo wires with a diameter of 0.18 mm and Mo sheets with thickness of 0.5 and 0.2 mm were prepared at the same process of pressing, sintering, drawing, or rolling, respectively. By comparative analysis on the microstructure and mechanical properties of Mo wires and Mo sheets, the effect of Mo powder micro-morphology on properties and quality of Mo products was studied. The results show that, compared with that prepared by traditional Mo powder with inhomogeneous particle size and aggregation, the Mo wires prepared by specific Mo powder with homogeneous particle sizes, less agglomeration, and better dispersion exhibit higher yield, higher tensile strength, and lower elongation at room temperature, and the Mo sheets also show excellent high-temperature performances and better isotropy. The essential reason for those is the difference of Mo powder micro-morphology. Inhomogeneous particle size and aggregation of Mo powder greatly influence the microstructure of Mo sintered compacts and mechanical properties of Mo products.展开更多
Long-term preservation of human platelets will greatly reduce the risk of their shortage. Lyophilization has been proved feasible for this purpose. For the recovery of lyophilized platelets,rehydration is an important...Long-term preservation of human platelets will greatly reduce the risk of their shortage. Lyophilization has been proved feasible for this purpose. For the recovery of lyophilized platelets,rehydration is an important process. In this paper,the rehydration proc-esses for 1 mL and 2 mL samples were studied. The effects of prehydration duration(15,30,60,90,120 and 150 min) in 37°C water vapor and the concentration of rehydration solution(25%,50%,75%,100% platelet-poor plasma) on the recovery rate,MPV(mean platelet volume) and PDW(platelet distribution width) were investigated. The mass changes during the prehydration process were weighed. The optimized rehydration conditions are as follows:(1) for 1 mL sample,the prehydration duration was 15 min and for 2 mL sample the prehydration duration was 90 min;(2) the rehydration solution was 75% platelet-poor plasma. Under optimized conditions,the morphology of the rehydrated platelets kept normal and their ultrastructures kept intact,their aggregation capacity to thrombin(1 U/mL) was 82.8% of the fresh ones. These results will be helpful for designing the freeze-drying protocols for human platelets.展开更多
Rotaxanes have attracted more and more attentions because of their diverse applications as sensors,catalysts, and functional materials. The construction of highly ordered and discrete multirotaxanes with the well-defi...Rotaxanes have attracted more and more attentions because of their diverse applications as sensors,catalysts, and functional materials. The construction of highly ordered and discrete multirotaxanes with the well-defined structure remains a challenge. Herein, a symmetric [5]rotaxane with zinc porphyrin as core and the neutral platinum-acetylide as the linkage was synthesized with high yield. The [5]rotaxane was well characterized with NMR spectroscopy and MALDI-TOF mass spectrometry. Interestingly, it was found that the [5]rotaxane showed the controllable aggregation behaviours in different solution compositions. For example, in non-polar solution, the [5]rotaxane could self-assemble into the largescaled solid nanospheres while the nanofibers were formed in polar solvent. Further investigation revealed that the [5]rotaxane displayed J-type aggregation in solution driven by p-p interaction. Notably,the similar structure without DPP[5]A formed the irregular morphology at the same condition,suggesting that the existence of rotaxanes endowed the complex with a relative rigid structure to facilitate the formation of the ordered aggregates.展开更多
Humic substances constitute the major organic fractions of soils, sediments and natural waters, and play a dominant role in the binding, mobilization, transport and ultimate fate of organic contaminants in subsurface ...Humic substances constitute the major organic fractions of soils, sediments and natural waters, and play a dominant role in the binding, mobilization, transport and ultimate fate of organic contaminants in subsurface systems. In this paper, two humic acid samples, Guanting and Tianjin, with different origin and chemical compositions have been investigated with AFM imaging for their adsorption and aggregation behaviors on mica. While the Tianjin humic sample is found to form small spheres with 250 to 330 nm in diameter at lower concentrations, irregular loop-chain assemblies of hundreds of nanometer in diameter with the chain width of about 40 nm are dominant for the Guanting humic sample, which may attribute to the more polar aliphatic fractions in the chemical composition in the latter. The heterogeneous and polydisperse nature of humic substances with multiple structural features, such as sponge-like structures, perforated sheets, aggregate of spheres, branches and chain-like assemblies etc., is apparent at higher concentrations for both humic samples, showing morphologically new evidence for the dominant view of the humic dual-mode sorption model. With naphthalene introduced, the assemblies of Guanting humic substances clearly become more compact with significantly narrowed branches and less porous the perforated sheet-like structures. It is indica- tive of that smaller nanometer scale rings present along the perforated assemblies could potentially represent hydrophobic domains, which may facilitate the adsorption and aggregation of naphthalene onto the natural particle surfaces and therefore lead to an important role of dissolved humic sub- stances in the sorption of environmental pollutants.展开更多
基金financially supported by the National Science Technology Supporting Program of China(No.2012BAE06B02)
文摘Using two kinds of molybdenum （Mo） powders with different micro-morphologies as raw materials, the Mo wires with a diameter of 0.18 mm and Mo sheets with thickness of 0.5 and 0.2 mm were prepared at the same process of pressing, sintering, drawing, or rolling, respectively. By comparative analysis on the microstructure and mechanical properties of Mo wires and Mo sheets, the effect of Mo powder micro-morphology on properties and quality of Mo products was studied. The results show that, compared with that prepared by traditional Mo powder with inhomogeneous particle size and aggregation, the Mo wires prepared by specific Mo powder with homogeneous particle sizes, less agglomeration, and better dispersion exhibit higher yield, higher tensile strength, and lower elongation at room temperature, and the Mo sheets also show excellent high-temperature performances and better isotropy. The essential reason for those is the difference of Mo powder micro-morphology. Inhomogeneous particle size and aggregation of Mo powder greatly influence the microstructure of Mo sintered compacts and mechanical properties of Mo products.
基金supported by the National Natural Science Foundation of China (50606032)Specialized Research Fund for the Doctoral Program of Higher Education (20070335145)Scientific Research Foundation for Advanced Talents,Nanjing University of Aeronautics and Astronautics,China (1001-909382)
文摘Long-term preservation of human platelets will greatly reduce the risk of their shortage. Lyophilization has been proved feasible for this purpose. For the recovery of lyophilized platelets,rehydration is an important process. In this paper,the rehydration proc-esses for 1 mL and 2 mL samples were studied. The effects of prehydration duration(15,30,60,90,120 and 150 min) in 37°C water vapor and the concentration of rehydration solution(25%,50%,75%,100% platelet-poor plasma) on the recovery rate,MPV(mean platelet volume) and PDW(platelet distribution width) were investigated. The mass changes during the prehydration process were weighed. The optimized rehydration conditions are as follows:(1) for 1 mL sample,the prehydration duration was 15 min and for 2 mL sample the prehydration duration was 90 min;(2) the rehydration solution was 75% platelet-poor plasma. Under optimized conditions,the morphology of the rehydrated platelets kept normal and their ultrastructures kept intact,their aggregation capacity to thrombin(1 U/mL) was 82.8% of the fresh ones. These results will be helpful for designing the freeze-drying protocols for human platelets.
基金financial support from the National Natural Science Foundation of China (No. 21572066)STCSM (No. 16XD1401000)Program for Changjiang Scholars and Innovative Research Team in University
文摘Rotaxanes have attracted more and more attentions because of their diverse applications as sensors,catalysts, and functional materials. The construction of highly ordered and discrete multirotaxanes with the well-defined structure remains a challenge. Herein, a symmetric [5]rotaxane with zinc porphyrin as core and the neutral platinum-acetylide as the linkage was synthesized with high yield. The [5]rotaxane was well characterized with NMR spectroscopy and MALDI-TOF mass spectrometry. Interestingly, it was found that the [5]rotaxane showed the controllable aggregation behaviours in different solution compositions. For example, in non-polar solution, the [5]rotaxane could self-assemble into the largescaled solid nanospheres while the nanofibers were formed in polar solvent. Further investigation revealed that the [5]rotaxane displayed J-type aggregation in solution driven by p-p interaction. Notably,the similar structure without DPP[5]A formed the irregular morphology at the same condition,suggesting that the existence of rotaxanes endowed the complex with a relative rigid structure to facilitate the formation of the ordered aggregates.
基金This research was supported by the National Natural Science Foundation of China (Grant Nos. 20037010 and 20277042).
文摘Humic substances constitute the major organic fractions of soils, sediments and natural waters, and play a dominant role in the binding, mobilization, transport and ultimate fate of organic contaminants in subsurface systems. In this paper, two humic acid samples, Guanting and Tianjin, with different origin and chemical compositions have been investigated with AFM imaging for their adsorption and aggregation behaviors on mica. While the Tianjin humic sample is found to form small spheres with 250 to 330 nm in diameter at lower concentrations, irregular loop-chain assemblies of hundreds of nanometer in diameter with the chain width of about 40 nm are dominant for the Guanting humic sample, which may attribute to the more polar aliphatic fractions in the chemical composition in the latter. The heterogeneous and polydisperse nature of humic substances with multiple structural features, such as sponge-like structures, perforated sheets, aggregate of spheres, branches and chain-like assemblies etc., is apparent at higher concentrations for both humic samples, showing morphologically new evidence for the dominant view of the humic dual-mode sorption model. With naphthalene introduced, the assemblies of Guanting humic substances clearly become more compact with significantly narrowed branches and less porous the perforated sheet-like structures. It is indica- tive of that smaller nanometer scale rings present along the perforated assemblies could potentially represent hydrophobic domains, which may facilitate the adsorption and aggregation of naphthalene onto the natural particle surfaces and therefore lead to an important role of dissolved humic sub- stances in the sorption of environmental pollutants.
