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801.
Yue Ming Zhou Jian Hua Ding Xie Zhang Huan Wen Chen 《中国化学快报》2007,18(1):115-117
Extractive electrospray ionization source(EESI)was adapted for ion-ion reaction,which was demonstrated by using a linear quadrupole ion trap mass spectrometer for the first ion-ion reaction of biopolymers in the atmospheric pressure ambient. 相似文献
802.
803.
804.
Nan Zhou 《Mikrochimica acta》1991,105(4-6):159-162
Proposed in this paper is an improved method for removal of tin as the matrix element by volatilization in an anhydrous medium as mixed halides of different composition. Any one of them boils at a lower temperature than SnBr4. This ternary system enhances the eventual recombination of temporarily dissociated species to volatile ones, thus making the process quicker and more efficient. The presence of 2 mg of Pb(II) suffices to prevent Bi(III) from loss due to volatilization. 相似文献
805.
806.
We perform molecular dynamics simulations of the hydrophobic collapse of two paraffin plates to examine how the collapse is mediated by realistic paraffin-water attractive van der Waals forces. We explore several aspects of the drying transition between the plates, including the critical separation for drying and the critical size of the vapor bubble required for the nucleation of the drying event. We also investigate the kinetics of hydrophobic collapse and find that the hydrophobic collapse occurs in about 100 ps. We compare these results with the simulations with the plate-water van der Waals attractions turned off and with recent results on the hydrophobic collapse of multidomain proteins. Last, we discuss the relationship among the dewetting transition critical distance, van der Waals potential well depth, and water contact angle on solute surface using a simple macroscopic theory. 相似文献
807.
A new method of measuring the amount of coalescence that occurs between drops during the emulsification process is proposed. The method uses a hydrophobic fluorescent probe, which is introduced into a fraction of the oil phase that is to be homogenized. The ratio of the intensity of the excimer peak to the intensity of the monomer peak in the fluorescent emission spectrum is sensitive to the concentration of the probe in the oil phase. Random coalescence events between oil drops lead to redistribution of the probe and its effective dilution in the oil phase. Coalescence results in a decrease in the intensity ratio in the fluorescence spectrum obtained from the ensemble of drops. Monte Carlo simulation is used to relate the change in intensity ratio to the coalescence rate. It is experimentally verified that the signal change is only due to coalescence and is not affected by the drop size of the distribution. 相似文献
808.
Zhixian Zhou Yuzhong Wang Jingchao Tao Yaoting Fan Yangjie Wu 《Journal of inclusion phenomena and macrocyclic chemistry》1998,32(1):69-80
A novel anion-selective electrode has been prepared by usingtetraazaporphyrinogen as the electroactive component and o-nitrophenyloctylether as the plasticizer. The electrode exhibits almost Nernstian responsecharacteristics for Pic-, ReO
4
-
,SCN-, ClO
4
-
and TPB-. The linearresponse ranges towards the above-mentioned anions are 10-6 10-2, 10-5 10-2,10-5 10-2, 10-5 10-1, and 10-5 10-2mol/Land the corresponding slopes are -56.8, -57.1, -56.3, -56.1, and -59.9mV/decade with correlation coefficients of -0.99978, -0.99987, -0.99999,-0.99998, and -0.99998, respectively. The electrode shows an anti-Hofmeisterselectivity sequence: Pic- > SCN- >ReO
4
-
> ClO
4
-
> I- >Br- > BF
4
-
> Sal->NO
3
-
> Cl-. The unusual responsemechanism of the novel anion-selective electrode was investigated byexperimental observations and calculation with the MNDO method. Theelectrode was used as a TPB- and a Pic-sensitiveelectrode, respectively, and applied to the assay of levamisolehydrochloride tablets by potentiometric titration and Gran's methods. Theresults obtained are in excellent agreement with that determined by thestandard pharmacopoeia method based on nonaqueous titration. 相似文献
809.
810.
Shenqian Ma Weixin Zhao Jun Zhou Jiaou Wang Shengqi Chu Zigeng Liu Guolei Xiang 《Chemical science》2021,12(12):4411
Noncovalent π stacking of aromatic molecules is a universal form of noncovalent interactions normally occurring on planar structures (such as aromatic molecules and graphene) based on sp2-hybridized atoms. Here we reveal a new type of noncovalent surface–π stacking unusually occurring between aromatic groups and peroxide-modified titania (PMT) nanosheets, which can drive versatile aromatic adsorptions. We experimentally explore the underlying electronic-level origin by probing the perturbed changes of unoccupied Ti 3d states with near-edge X-ray absorption fine structures (NEXAFS), and find that aromatic groups can vertically attract π electrons in the surface peroxo-Ti states and increase their delocalization regions. Our discovery updates the concept of noncovalent π-stacking interactions by extending the substrates from carbon-based structures to a transition metal oxide, and presents an approach to exploit the surface chemistry of nanomaterials based on noncovalent interactions.A new type of noncovalent surface–π stacking interaction occurring on a transition metal oxide, titania, is reported, which is different from the traditional forms on sp2-hybridized planar structures like graphene. 相似文献