Berberis alkaloids

This review systematizes literature information on alkaloids of plants of the genusBerberis. The main chemical and spectral methods of establishing their structures, and also their pharmacological properties, are considered. The review includes literature sources up to 1992.Andizhan State Medical Institute. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 481–506, July–August, 1993.     

Spatial structure of dimeric guanolides. Crystal and molecular structure of the diguanolide handelin

The structure of the disesquiterpene lactone handelin, in the form of the solvate with dimethyl sulfoxide C₃₂H₄₀O₈·C₂H₆OS has been established by the x-ray structural method (diffractometer, CuK radiation, 1976 reflections, direct method, R=0.102). The results of the investigation confirm the structure of handelin proposed previously on the basis of spectral studies. A comparative analysis has been made of the conformations of the rings of handelin, chrysanthelide, absinthin, anabsin, and artelein with those observed in A/B-cis,B/C-trans-linked monoguaianolides.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Republic of Uzbekistan, Tashkent, Fax (3712) 62 73 48; and Tashkent Institute of Irrigation and the Mechanization of Agriculture. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 204–212, March–April, 1994.     

Obliquely deposited CdTe:In films with anomalous photovoltaic properties

A technology of doping of photovoltaically anomalous polycrystalline CdTe films with indium is developed, which makes it possible to increase the photovoltage by an order of magnitude and the short-circuit current by more than two orders of magnitude. This effect, which was observed for the first time in CdTe:In films, is explained by the asymmetric thermofield migration of In⁺ⁱ ions and cadmium vacancies V _Cd ^?j in the crystal field of grain boundaries during the heat treatment     

Chemical Composition and Antimicrobial Activity of Essential Oil from the Aerial Part of Haplophyllum latifolium

Chemistry of Natural Compounds -     

Solvability of the boundary-value problem for a mixed equation involving hyper-Bessel fractional differential operator and bi-ordinal Hilfer fractional derivative

In a rectangular domain, a boundary-value problem is considered for a mixed equation with a regularized Caputo-like counterpart of hyper-Bessel differential operator and the bi-ordinal Hilfer's fractional derivative. By using the method of separation of variables a unique solvability of the considered problem has been established. Moreover, we have found the explicit solution of initial-boundary problems for the heat equation with the regularized Caputo-like counterpart of the hyper-Bessel differential operator with the non-zero starting point.     

Polyfunctional nitriles in the synthesis of derivatives of 1,3,4-thiadiazolo-[3,2-<Emphasis Type="Italic">a</Emphasis>]pyrimidines

A one-pot method has been developed for the synthesis of 2-R-7-methyl-5-oxo-5H-1,3,4-thia-diazolo[3,2-a]pyrimidine by condensation of β-alkylthio(alkoxy)propionitrile, thiosemicarbazide, and ethyl acetoacetate in PPA, and also (7-methyl-5-oxo-5H-1,3,4-thidiazolo[3,2-a]pyrimidin-2-yl)-acetamide from cyanoacetamide, thiosemicarbazide, and ethyl acetoacetate. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, 1096–1100, July, 2008.     

Impedimetric sensing of humidity and temperature using CeO2–Co3O4 nanoparticles in polymer hosts

Humidity and temperature sensors were fabricated from a nanocomposite consisting of CeO₂-Co₃O₄ hybrid nanoparticle-silicone adhesive and CeO₂-Co₃O₄ hybrid nanoparticle-polymer adhesive, respectively, to fix the material on a glass supported copper electrode. The impedance of the sensor decreases by a factor of 960 at a working frequency of 100 Hz, and by a factor of 800 at 1 kHz, on increasing relative humidity (RH) from 30 to 90 %. In parallel, the capacitances increase by factors of 567 and 355, respectively, under the same experimental conditions. The effect of temperature in the range from 25 to 70 °C on impedance (again at 100 Hz and 1 kHz) was also studied and found to decrease with increasing temperature. On going from 25 to 70 °C, the impedance measured at 100 Hz and 1 kHz decreases 2.22 and 1.58 times, respectively, in surface type sensors, while in sandwich type sensors this decrease is 3.0 and 2.08 times. The calculated average sensitivity to temperature is −1.02 and −0.8 % °C⁻¹ for the surface type and −1.5 and −1.2 % °C⁻¹ for the sandwich type sensors at frequencies of 100 Hz and 1 kHz, respectively.

A highly sensitive sensor with dual functionality for humidity and temperature has been fabricated by using CeO₂-codoped Co₃O₄ nanoparticles with silicone and polymer adhesive.

     

Carbon nanotubeben cuprous oxide composite based pressure sensors

In this paper, we present the design, the fabrication, and the experimental results of carbon nanotube (CNT) and Cu₂O composite based pressure sensors. The pressed tablets of the CNT-Cu₂O composite are fabricated at a pressure of 353 MPa. The diameters of the multiwalled nanotubes (MWNTs) are between 10 nm and 30 nm. The sizes of the Cu₂O micro particles are in the range of 3-4 μm. The average diameter and the average thickness of the pressed tablets are 10 mm and 4.0 mm, respectively. In order to make low resistance electric contacts, the two sides of the pressed tablet are covered by silver pastes. The direct current resistance of the pressure sensor decreases by 3.3 ×as the pressure increases up to 37 kN/m². The simulation result of the resistance-pressure relationship is in good agreement with the experimental result within a variation of ± 2%.     

Preparation and physicochemical properties of polymeric complexes of methyl benzimidazol-2-ylcarbamate with apple pectin

Polymeric complexes have been obtained by the combined mechanical treatment of enzyme-treated apple pectin and methyl benzimidazol-2 -ylcarbamate, and their physicochemical properties have been studied.Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 896–900, November-December, 1995. Original article submitted May 11, 1995.     

Electrochemical and electrocatalytic properties of meso-triphenylcorrole and its complexes with Mn(III), Co(III), Cu(III), and Zn(II)

The method of cyclic voltammetry (CV) was used to compare electrochemical and electrocatalytic properties of meso-triphenylcorrole [H₃(ms-Ph)₃Cor] and also its complexes with Mn(III), Co(III), Cu(III), and Zn(II) in 0.1M KOH. Metal-localized redox transitions are detected in the complexes of Mn (III ?? IV) and (III ?? II), Co (III ?? II), Cu (III ?? II). It is shown that the manganese complex features most effective catalytic properties in the reaction of molecular oxygen electroreduction.