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81.
Polyvinyl alcohol is a multipurpose polymer, and there is abundant hydroxyl group on its surface. In this article, we first time attempted to assay the superficial hydroxyl group content on the solid polyvinyl alcohol (PVA-1799) with a degree of polymerization over 1700 and a degree of alcoholysis over 99.0%. The assay was carried out by two different titration systems. The results show: (1) the order of magnitude of superficial hydroxyl group content on its solid surface was about 3.8E-5 mol/cm2 by acylation system with single functional group reagent (acetic anhydride); while (2) the order of magnitude of superficial hydroxyl group content was about 1.4E-7 mol/cm2 by esterification system with bi-functional group reagent (Toluence 2,4-DiIsocyanate, TDI). The results would be useful to provide a quantitative reference when -OH on the solid PVA surface is intended to be utilized for surface modification for some application. Moreover, the results and their difference also offer us the knowledge of the surface modification efficiency. 相似文献
82.
四丙基氢氧化铵改性纳米HZSM-5分子筛及其在甲醇制汽油中的催化性能 总被引:1,自引:0,他引:1
采用四丙基氢氧化铵(TPAOH)溶液对纳米ZSM-5分子筛进行改性, 运用X射线衍射、扫描电镜、27Al和29Si固体核磁、X射线光电子能谱、N2物理吸附脱附法和NH3程序升温脱附等手段对所制样品进行了表征, 并评价了其催化甲醇制汽油反应性能. 结果表明, 改性后的HZSM-5相对结晶度增加, 晶体形貌更加规整, 表面硅铝比增加, 比表面积和微孔表面积增大, 强酸位酸量增多. 同时, TPAOH改性不仅可以使分子筛脱硅脱铝, 而且伴有二次晶化补硅补铝, 改变了分子筛的硅铝分布. 改性的HZSM-5在甲醇制汽油反应中的稳定性大幅度提高, 其寿命由70h增至170h以上, 随着TPAOH处理时间的增加, 催化剂寿命增加, 氢转移反应加快, 导致油相产品中异构烷烃增多, 烯烃减少. 相似文献
83.
Zhang W Zhao Y Bai X Wang Y Zhao D 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2011,78(3):1105-1109
Raman and surface-enhanced Raman scattering (SERS) technique are reliably used to compare relative intensity shifts and to investigate the adsorption geometry of protoberberine alkaloids on Ag nanoparticles. We report joint application of fluorescence and SERS spectroscopy to study the interaction between protoberberine alkaloids and human serum albumin (HSA). We propose SERS technique to improve the quenching interaction caused by protoberberine alkaloids which are used to be applied in recognition process of fluorescent drugs with large biomolecules. The fluorescence results show that the fluorescence intensity of HSA is significantly decreased in presence of protoberberine alkaloids. The SERS technique demonstrates obvious advantages over direct measurements in discriminating and identifying pharmaceutical molecules. By means of this method, we are able to detect important information concerning the orientation of protoberberine alkaloids when interacting with HSA. We also show that the nitrogen atom is free, but a benzene ring and two adjacent methoxy groups are involved in the spontaneously electrostatic inducement and subsequently binding with HSA. 相似文献
84.
85.
86.
Shunyi Yang Xianyou Wang Xiukang Yang Ziling Liu Yansong Bai Yingping Wang Hongbo Shu 《Journal of Solid State Electrochemistry》2012,16(8):2823-2836
Spherical Li[Ni0.5Mn0.3Co0.2]O2 was prepared by both the continuous hydroxide co-precipitation method and continuous carbonate co-precipitation method under different calcined temperatures. The physical properties and electrochemical behaviors of Li[Ni0.5Mn0.3Co0.2]O2 prepared by two methods were characterized by X-ray diffraction, scanning electron microscope, and electrochemical measurements. It has been found that different preparation methods will result in the differences in the morphology (shape, particle size, and tap density), structure stability, and the electrochemical characteristics (shape of initial charge/discharge curve, cycle stability, and rate capability) of the final product Li[Ni0.5Mn0.3Co0.2]O2. The physical and electrochemical properties of the spherical Li[Ni0.5Mn0.3Co0.2]O2 prepared by continuous hydroxide co-precipitation is apparently superior to the one prepared by continuous carbonate co-precipitation method. The optimal sample prepared by continuous hydroxide co-precipitation at 820 °C exhibits a hexagonally ordered layer structure, high special discharge capacity, good capacity retention, and excellent rate capability. It delivers high initial discharge capacity of 175.2 mAh g?1 at 0.2 C rate between 3.0 and 4.3 V, and the capacity retention of 98.8 % can be maintained after 50 cycles. While the voltage range is broadened up to 2.5 and 4.6 V vs. Li+/Li, the special discharge capacities at 0.2 C, 0.5 C, 1 C, 2 C, 5 C, and 10 C rates are as high as 214.3, 205.0, 198.3, 183.3, 160.1 and 135.2 mAh g?1, respectively. 相似文献
87.
稀土氨基酸混配型配合物的合成与表征 总被引:9,自引:0,他引:9
合成了14种稀土元素与甘氨酸(Gly)、L-丙氨酸(Ala)的混配型三元固态配合物RE(Gly)_(2.5)(Ala)_(1.5)(ClO_4)_3·H_2O(RE=La~Lu,Pm除外)。并对配合物进行了红外、核磁、荧光、X射线粉末衍射和热分析。铕(Ⅲ)、铽(Ⅲ)三元配合物的荧光强度(Eu:~5D_0→~7F_2;Tb:~5D_4→~7F_5,~7F_6)比相应铕(Ⅲ)或铽(Ⅲ)水合高氯酸盐增大10倍。 相似文献
88.
常温常压下光促进烯烃与一氧化碳的羰基化反应 总被引:1,自引:0,他引:1
报道了烯烃(环己烯和1-辛烯)与一氧化碳通过光促进实现常温常压非贵金属(钴配合物)催化的羰基化反应.研究发现,以Co(OAc)2为催化剂时,不需要加入光敏剂丙酮就能发生反应;CoSalen,吡啶-2-羧酸钴和大环配合物[Co(14)4,11-diene-N4]I2是较好的催化剂,其催化活性比Co(OAc)2高.其中,吡啶-2-羧酸钴与Co(OAc)2相同,反应中不需要光敏剂存在,其选择性很高.通过氘代丙酮和氘代甲醇同位素实验,进一步证实了反应中双键异构的存在和副产物的分析结果. 相似文献
89.
Li J Ma W Huang Y Cheng M Zhao J Yu JC 《Chemical communications (Cambridge, England)》2003,(17):2214-2215
A new photocatalytic system involving iron(II) bipyridine supported on NaY zeolite (FeBY) shows excellent reactivity and selectivity in the oxidation of organic compounds. This approach allows highly controlled oxidation reaction to occur but avoids undesirable mineralization into CO2 and H2O. 相似文献
90.
Yu Chen Honggang Chen Huilan Guan Wei Liu Zhe Li Hui Liu Yongfang Li Yingping Zou 《中国化学快报》2021,32(1):229-233
Recent advances in non-fullerene acceptors(NFAs),typically Y6,have driven power conversion efficiency(PCE) of single-junction orga nic solar cells(OSCs) over 16%.Mea nwhile,it becomes essential to know how to adopt simple strategies to further improve device performance.In this work,a new A-DA'D-A acceptor derivative,Y19-N3 employing 3-ethylheptyl branched at the 3rd-position instead of 2-ethylhexyl on the pyrroles of Y19 is reported.The selection of an appropriate solvent in casting device is implemented to maximize the photovoltaic performance.PBDB-T:Y19-N3-based OSCs treated with a ternary solvent of CF/CB(1:3,v/v) and 0.8% DIO exhibit the optimal PCE of 13.77% here,with the significantly improved Voc(0.78 V) and FF(0.72) as well as the high Jsc(24.46 mA/cm2).Further characterizations indicate that this ternary solvent-treated PBDB-T/Y19-N3 film exhibits the more appropriate morphological features with the highly efficient charge generation and collection as well as the more balanced electron and hole mobilities.This work combines molecular design and device engineering to improve the photovoltaic properties,which is important to the development of OSCs. 相似文献