Hybrid opto-TV image-processing system

Quantum Radiophysics Division. Translated from preprint No. 23, 1991 of the Lebedev Physics Institute, Russian Academy of Sciences, Moscow, Russia.     

Mercuration of Benzyltriphenylphosphonium Chloride with Mercury(II) Acetate and Trifluoroacetate and Some Transformations of the Products

Russian Journal of Organic Chemistry -     

Stereoselective synthesis of tetrahydropyran new derivatives underlain by α-allyl ketones

Decarboxylation of α-allyl-substituted acetoacetic esters afforded α-allyl ketones that were reduced with L-selectride [LiBH(s-Bu)₃] in alcohols RCH(OH)CH₂CH₂CH=C(Me)CH₂R'. The latter reacted with methyl 4-hydroxy-3-formylbenzoate and methyl orthoformate in the presence of p-toluenesulfonic acid to provide trans-tetrahydropyrano[3,2-с][1]benzopyran. In reaction of the E-isomer of alcohol Me₂CHCH(OH) CH₂CH₂CH=C(Me)CH₂CH₂Ph with CF₃SO₃H a stereoselective cyclization occurred with the formation of 2,6-disubstituted tetrahydropyran; Prins reaction with 4-bromobenzaldehyde and salicylaldehyde in the presence of boron trifluoride etherate also proceeded stereoselectively giving a substituted tetrahydropyrano-[3,2-c][1]-benzopyran.     

Sound propagation in a plane wave guide with an elastic wall section

Problems of acoustic wave propagation in a plane wave guide whose walls are assumed to be undeformed with the exception of a section of finite length whose bending is described by the thin plate theory equations in the framework of the Kirchhoff-Love hypotheses are considered. The sound-proofing characteristics of the wave guide described and the stability of the forced oscillations of the system considered are investigated. Formulations of the problem of active vibroacoustic protection and the problem for the peristaltic pump are given. Soundproofing in wave guides has been considered in a number of papers, a fairly complete review of which is given in [1].Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza., No. 1, pp. 132–139, January–February, 1986.     

Neuroprotective and Antioxidant Enhancing Properties of Selective Equisetum Extracts

The sterile stems belonging to the Equisetum species are often used in traditional medicine of various nations, including Romanians. They are highly efficient in treating urinary tract infections, cardiovascular diseases, respiratory tract infections, and medical skin conditions due to their content of polyphenolic derivatives that have been isolated. In this regard, this study aimed to provide the chemical composition of the extracts obtained from the Equisetum species (E. pratense, E. sylvaticum, E. telmateia) and to investigate the biological action in vitro and in vivo. For the chemical characterization of the analyzed Equisetum species extracts, studies were performed by using ultra-high-performance liquid chromatography (UHPLC-DAD). In vitro evaluation of the antioxidant activity of the plant extracts obtained from these species of Equisetum genus was determined. The neuroprotective activity of these three ethanolic extracts from the Equisetum species using zebrafish tests was determined in vivo. All obtained results were statistically significant. The results indicate that E. sylvaticum extract has a significant antioxidant activity; whereas, E. pratense extract had anxiolytic and antidepressant effects significantly higher than the other two extracts used. All these determinations indicate promising results for the antioxidant in vitro tests and neuroprotective activity of in vivo tests, particularly mediated by their active principles.     

Intramolecular hydroalkoxylation of <Emphasis Type="Italic">syn</Emphasis>- and <Emphasis Type="Italic">anti</Emphasis>-1-R-2-arylhex-4-en-1-ols. Efficient stereoselective synthesis of tri- and tetrasubstituted tetrahydrofurans

Reactions of syn- and anti-4-(4-bromophenyl)-2-methylnon-1-en-5-ols and 3-(4-bromophenyl)-5- methyl-1-phenylhex-5-en-2-ols with trifluoromethanesulfonic acid and salicylaldehyde derivatives in the presence of Et₂O · BF₃ (Prins reaction) or with salicylaldehydes in the presence of trimethyl orthoformate and p-toluenesulfonic acid stereoselectively afforded tri- and tetrasubstituted tetrahydrofurans with one or two fused heterocycles and various functional groups (COOEt, Br, MeC=CH₂). The reactivity of the synthesized compounds toward thiophen-2-ylboronic acid in the Suzuki reaction was studied, and hydrolysis and reduction (LiAlH₄) of the ester group therein gave the corresponding carboxylic acids and alcohols. One of the obtained tetrahydrofuran derivatives was converted into amide, aldehyde, and aldehyde oxime. Stereochemical configuration of substituents was retained in all chemical transformations.     

General procedure for the synthesis of spirocyclic 3-hydroxy- and 3-oxotetrahydrofurans containing carboand heterocyclic fragments

Reactions of cyclopentanone, cyclohexanone, N-substituted pyrrolidin-3-one and piperidin-4-one, and tetrahydropyran-4-one with allyl bromide in the presence of zinc and ammonium chloride gave the corresponding geminal hydroxy allyl derivatives. Treatment of the latter with sodium periodate in the presence of sodium metabisulfite resulted in their oxidative cyclization with formation of oxa spirocyclic alcohols containing carbo- and heterocyclic fragments. Swern oxidation of the spiro alcohols afforded the corresponding ketones which were characterized as 2,4-dinitrophenylhydrazones.     

Reconstruction of a complex-shaped defect from the known arrival time of the reflected ultrasonic wave

The problem of reconstructing the boundary of an arbitrarily shaped defect formed inside an elastic body from the measured time of arrival of the reflected ultrasonic wave in the echo method is considered. The characteristic size of the defect is assumed to be greater than the wavelength, and the defect is irradiated from the far-field zone, which means that the incident wave can be considered as plane. An algorithm is developed for reconstructing the convex envelope of a nonconvex defect from the arrival times of echo signals measured at different angles with the use of circular scanning.