Electrospray Generated from the Tip-Sealed Fine Glass Capillary Inserted with an Acupuncture Needle Electrode

In electrospray, excess charges are supplied to a sample solution by the occurrence of electrochemical reactions. Recently, different versions of electrospray, e.g., dielectric barrier electrospray ionization, inductive desorption electrospray ionization, and electrostatic-ionization driven by dielectric polarization, have been reported in which the sample solution was not in direct contact with the metal electrode but separated by dielectric materials. The objective of the current work is to elucidate the mechanism of dielectric barrier electrospray. A sealed borosilicate glass capillary inserted with a fine acupuncture needle was used as a probe. A sample solution (~ 400 nL) was captured on the glass capillary tip and a positive high voltage (HV) pulse (+?4.5 kV) was applied to the internal metal electrode. Mass spectra were measured as a function of the HV pulse width from μs to 10 s. Ions started to be detected with the pulse width of ~ 5 ms. The ion intensities increased slowly with time and reached a plateau in a few seconds. The charge distribution of cytochrome c [M?+?nH]ⁿ⁺ shifted to higher n values from a few ms to seconds. In addition to cone-jet mode normal electrospray that lasted until all the liquid sample was depleted from the glass tip, the polarization-induced electrospray ionization was observed at the early stage of the HV application.

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Influence of infection by Verticillium dahliae on the cuticular lipids of the leaves of cotton plants of variety 175

The composition of the cuticular lipids of young leaves of cotton plants of the wilt-resistant variety 175-F has been determined and it has been established that on artificial infection of the plant with cotton wilt(Verticilliuim dahliae) the component composition of these lipids did not change but the level of the 18:0, 18:1, and 18:2 acids in esters of fatty acids with alkanol, sterols, and triterpenols fell.     

Phytoecdysteroids of plants of the genusSilene. VIII. 2-Deoxyecdysterone 3-acetate fromSilene praemixta

A phytoecdysteroid, 2-deoxyecdysterone 3-acetate, has been isolated from the epigeal organs ofSilene praemixta M. pop.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 60–62, January–February, 1985.     

Isolation of a ca-channel blocker from the venom of the spiderAgelena labirintica

From the venom of the spider Ageiena labirintica we have isolated the neurotoxin Agll (IV-6-1) with a molecular mass of 1000 Da, which effectively blocks the Ca channels of presynaptic membranes of frog nerve-muscle synapses.Institute of Physiology and Biophysics, Academy of Sciences of the Republic of Uzbekistan, 700095, Tashkent, ul. Niyazova, 1. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 467–470, May–June, 1995. Original article submitted October 24, 1994.     

Phospholipase A2 from the venom of the spider Eresus niger

A phospholipase A₂ with a molecular mass of 12–14 kDa has been isolated from the venom of the spiderEresus niger by three-stage column chromatography. Asparagine has been identified as the N-terminal amino acid.Institute of Physiology, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 557–560, July–August, 1991.     

Microwave synthesis of barium titanate,strontium zirconate,and sodium indium tungstate

The results of microwave (at a frequency of 2.45 GHz) synthesis of BaTiO₃, SrZrO₃, and NaIn(WO₄)₂ are compared with those of the common solid-phase synthesis.     

Peculiarities of self-action in second harmonic generation of laser radiation in nonlinear crystals

By using the generalized method of strong interaction of nonlinear waves and computer simulation, an analysis of the influence of self-action effects on second harmonic generation of an intense diverging picosecond pulse is performed. Using the approximation of strong wave interaction, an analytic solution is obtained for frequency conversion of the laser radiation taking into account the pump intensity depletion, the influence of the angular dispersion effect (ADE), and the higher nonlinearities. It is shown that the self-action effects, the ADE, and the linear phase mismatch can compensate for each other, increasing the efficiency of second harmonic generation. Optimum conditions for second harmonic generation in converging and diverging laser beams were found. An asymmetry of the angular dependence of the second harmonic intensity was experimentally observed and theoretically explained. The asymmetry is caused by the reverse energy conversion of the second harmonic into the pump by the influence of the ADE and Kerr nonlinearities.     

Nonlinear susceptibilities of vapors and solutions of organic dyes

Results of theoretical studies of laser and Kerr nonlinear susceptibilities of vapors and solutions of organic dyes using a series of polycyclic arenes as an example are presented. Nonlinear susceptibilities of the third χ⁽³⁾ (?3ω; ω, ω, ω) and the fifth χ⁽⁵⁾ (?3ω; ω, ω, ω, ω, ?ω) orders of a series of organic dyes responsible for third harmonic generation of Nd:YAG laser radiation are calculated within the context of the free electron model. Results of calculations of their Kerr third-order nonlinear susceptibilities χ⁽³⁾ (?ω; ω, ?ω, ω) and non-linear refractive indices n ₂ are presented. The calculation results are compared with experimental data on third harmonic generation in naphthalene vapors and with χ⁽³⁾ (?ω; ω, ?ω, ω) as well as n ₂ of paraterphenyl and naphthalene solutions.     

Transformations of Ethanol Supercritical Fluid

Russian Journal of Organic Chemistry - Nowadays, a new approach to the synthesis of glycerol-free biodiesel is being developed in the framework of sub- and supercritical fluid (SCF) technologies,...