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101.
102.
以低相对分子质量生物可降解D,L-聚乳酸(D,L-PLA)二醇和六亚甲基二异氰酸酯(HDI)为原料、1,4-丁二醇(BD)为扩链剂及聚乙烯基吡咯烷酮(PVP)为悬浮剂,通过悬浮聚合法初步合成了一种新型聚氨酯微球(PUMS)。用扫描电子显微镜(SEM)考察了BD的含量对微球表面形态的影响,通过激光粒度分析仪讨论了搅拌速率和PVP浓度对微球粒径及其分布的影响,用傅立叶变换红外光谱(FTIR)粒度分析仪对微球的化学结构进行了表征。结果表明,合成的微球的平均粒径随搅拌速率和PVP浓度的增加而减少,粒径分布变宽;当搅拌速率为400r/min,PVP质量分数为1.5%时。微球的平均粒径约47μm,粒径分布最窄。约在10~90μm;微球表面有孔,但随着BD含量的增加,微球表面变得相对粗糙,孔数减少,孔径减小,直至孔消失。 相似文献
103.
Nano SiO2-P(VDF-HFP) composite porous membranes were prepared as the matrix of porous polymer electrolytes through in situ composite method based on hydrolysis of tetraethoxysilane and phase inversion. SEM, TEM, DSC and AC impedance analysis were carried out. It is found that the in situ prepared nano silica was homogeneously dispersed in the polymeric matrix, enhanced conductivity and electrochemical stability of porous polymer electrolytes, and improved the stability of the electrolytes against lithium metal electrodes. The in situ composite method was found to be much better than the direct composite method in lowering the interfacial resistance between electrolyte and lithium metal electrode. Moreover, cycle test of lithium batteries using lithium metal as anode and sulfur composite material as cathode showed that the electrolyte based on in situ composite of silica presented stable charge-discharge behavior and little capacity loss of battery. 相似文献
104.
105.
Lihua Wang Xiaodong Yi Weizheng Weng Chunxi Zhang Xin Xu Huilin Wan 《Catalysis Letters》2007,118(3-4):238-243
By using the in situ IR spectroscopy, the superoxide species (O2−), characterized by the O–O stretching peak at 1130 cm−1, was detected on the SrF2/La2O3 catalyst at temperatures up to 973 K. The introduction of 18O2 isotope caused the 1130 cm−1 peak to shift to lower wavenumbers (1095 and 1064 cm−1), consistent with the assignment of the spectra to the superoxide species. A good correlation between the rate of the disappearance
of the O2− species and that of the formation of C2H4 was observed, suggesting that O2− was the active oxygen species responsible for the oxidative coupling of methane (OCM) on the SrF2/La2O3 catalyst. This conclusion was reinforced by the EPR experiments (gxx = 2.0001, gyy = 2.0045, gzz = 2.0685), showing that O2− was the only paramagnetic oxygen species detectable on the O2-preadsorbed SrF2/La2O3 catalyst. These results suggest that superoxide O2− can be a stable active oxygen species, whose role in the OCM reaction cannot be overlooked. 相似文献
106.
107.
本文首先叙述了智能家居的基本概念以及分析了智能家居中的通信技术,分析了WiFi技术在智能家居中的应用优势。接着讨论了串口WiFi的功能,以WiFi插座为例,描述了串口WiFi在智能家居中的具体应用。最后叙述了基于WiFi技术的智能家居系统。 相似文献
108.
Ethanol extraction of oil,gossypol and aflatoxin from cottonseed 总被引:7,自引:0,他引:7
R. J. Hron Sr. M. S. Kuk G. Abraham P. J. Wan 《Journal of the American Oil Chemists' Society》1994,71(4):417-421
Commercial processing of cottonseed requires hexane to extract and recover edible oil. Gossypol and aflatoxin are not removed
from extracted meals. A bench-top extraction process with 95% (vol/vol) aqueous ethanol (EtOH) solvent has been developed
that extracts all three of the above materials with a much less volatile solvent. In this process, cottonseed is pretreated
and extracted with ambient 95% EtOH to remove gossypol and then extracted with hot 95% EtOH to extract oil and aflatoxin.
Membranes and adsorption columns are used to purify the various extract streams, so that they can be recycled directly. A
representative extracted meal contained a total gossypol content of 0.47% (a 70% reduction) and 3 ppb aflatoxin (a 95% reduction).
Residual oil content was approximately 2%. Although the process is technically feasible, it is presently not economical unless
a mill has a continual, serious aflatoxin contamination problem. However, if a plant cannot meet the hexane emission standards
under the Clean Air Act of 1990, this process could provide a safer solvent that may expand the use and increase the value
of cottonseed meal as a feed for nonruminants.
Presented in part at the AOCS annual meeting, Toronto, Canada, May 1992. 相似文献
109.
Bottomley Stephen P.; Popplewell Andrew G.; Scawen Michael; Wan Tommy; Sutton Brian J.; Gore Michael G. 《Protein engineering, design & selection : PEDS》1994,7(12):1463-1470
The stability and unfolding of an immunoglobulin (Ig) G bindingprotein based upon the B domain of protein A (SpAB) from Staphylococcusaureus were studied by substituting tryptophan residues at strategiclocations within each of the three a-helical regions (al-a3)of the domain. The role of the C-terminal helix, a3, was investigatedby generating two protein constructs, one corresponding to thecomplete SpAB, the other lacking a part of ct3; the Trp substitutionswere made in both one-and two-domain versions of each of theseconstructs. The fluorescence properties of each of the single-tryptophanmutants were studied in the native state and as a function ofguanidine-HCl-mediated unfolding, and their IgG binding activitieswere determined by a competitive enzyme-linked immunosorbentassay. The free energies of folding and of binding to IgG foreach mutant were compared with those for the native domains.The effect of each substitution upon the overall structure andupon the IgG binding interface was modelled by molecular graphicsand energy minimization. These studies indicate that (i) 3 contributesto the overall stability of the domain and to the formationof the IgG binding site in l and 2, and (ii) al unfolds first,followed by 2 and 3 together. 相似文献
110.
A thin circular film clamped at the periphery is adhered to the planar surface of a rigid cylindrical punch. An external tensile load is applied to the punch, causing the film to delaminate from the substrate and the circular contact edge to contract. The film spontaneously separates from the punch, or pulls off, when the contact radius reduces to a range between 0.1758 and 0.3651 of the film radius, depending on the magnitude of the residual membrane stress. The mechanical delamination process is derived by a thermodynamic energy balance based on a coupled interfacial adhesion and residual membrane stress. The theoretical model has significant implications in nanoforce measurement, microelectromechanical systems (MEMS) comprising active moveable films, and biological cell adhesion. 相似文献