On some second-order rigidity conditions for analytic surfaces

It is proved that an analytic surface does not admit a nontrivial analytic infinitesimal deformation of the second order satisfying one of the following conditions: a) preservation of the normal curvature of a planar closed convex curve belonging to the surface; b) each point of a closed curve belonging to the surface slides in a rectifiable curve.Translated from Matematicheskie Zametki, Vol. 14, No. 2, pp. 233–242, August, 1973.     

Einfluß der Zusammensetzungsheterogenität der Vinylalkohol/Vinylacetat-Copolymerisate auf die Geschwindigkeit der Emulsionspolymerisation des Vinylaeetats und die Eigenschaften der Polyvinylacetatdispersion

Ohne Zusammenfassung     

Synthesis and biological activity of permethrin analogs containing various substituents in position <Emphasis Type="Italic">2</Emphasis> of the cyclopropane ring

A number of permethrin derivatives having various substituents (Me, Et, Pr, Ph, PhCH₂, PhCH₂CH₂) in position 2 of the cyclopropane ring were synthesized and assayed for insecticidal activity against typhoid flies, rice weevils, and black bean aphid and juvenile hormone activity against flour beetle chrysalises. The examined compounds showed a weak insecticidal activity. Some derivatives were found to exert knockdown effect analogous to that of commercial pyrethroid tetramethrin; however, unlike permethrin, they exhibited pronounced juvenile hormone activity.     

Metabolic engineering of Pseudomonas putida for methylmalonyl-CoA biosynthesis to enable complex heterologous secondary metabolite formation

An operon consisting of three open reading frames, annotated in silico as methylmalonyl-CoA (mm-CoA) epimerase, mm-CoA mutase (MCM), and meaB, was identified in the sequencing project of the myxobacterium Sorangium cellulosum So ce56. This putative MCM pathway operon was subcloned from a bacterial artificial chromosome by Red/ET recombineering onto a minimal replicon derived from p15A. This plasmid was modified for integration and heterologous expression in Pseudomonas putida to enable the production of complex secondary metabolites requiring mm-CoA as precursor. Methylmalonate was identified in the recombinant P. putida strain by an analysis method based on gas chromatography/mass spectrometry. The engineered strain is able to synthesize polyketides requiring mm-CoA as an extender unit, which was demonstrated by the production of myxothiazol after integration of the biosynthetic gene cluster into the chromosome, followed by induction of expression.     

Detection of Refractive Index Change of Liquids by Diffractive Element talrd Sensor

Refractive index change of liquids was detected using a temperature compensated prism cavity together with a diffractive optical element fabricated by electron beam lithography. Small changes of refractive index could be detected from image data of the sensor.     

The relation betweenk-th order rigidity and analytic nondeformability of surfaces

It is proved that a surface of class C ³ admitting only one linearly independent, infinitely small, first order bending and having rigidity of order k (k2) is analytically nondeformable. This result can also be obtained from Sabitov's more general result [Theses and Reports of the All-Union Conference on Geometry in the Large, Novosibirsk (1987)] the proof of which, still unpublished, is based on another idea. Translated from Ukrainskii Geometricheskii Sbornik, No. 34, pp. 98–104, 1991.     

Kinetics of sorption of uranium(VI) compounds with zirconium-silica nanosorbents

The kinetics of sorption of uranium(VI) compounds from sulfate and carbonate solutions using four samples of mesoporous zirconium-silica nanosorbents obtained by bitemplate (solubilization) synthesis was studied. The sorption equilibrium set-in time and the kinetic characteristics of sorption were shown to depend on the sorbent (its composition, specific surface area, dispersity, and pore size), the temperature, and the composition and pH of the solution from which uranium compounds are sorbed. The sorption kinetics was described by a first-order equation. The limiting stage of the process was found to be the external diffusion of uranium-containing particles to the sorbent surface.     

Sorption of uranium(VI) compounds on fibrous anion exchanger surface from aqueous solutions

The effect of sorbent consumption and the kinetics and mechanism of sorption of uranium(VI) compounds on the surface of FIBAN A-6 fibrous anion exchanger from aqueous uranyl acetate solutions have been studied in the presence of sulfuric acid or sodium hydrocarbonate. The degree of sorption of uranium(VI) compounds by FIBAN A-6 anion exchanger has been found to be as high 97.0–99.5% at an interfacial contact time of 3–7 min and a sorbent consumption of 2–5 g/dm³. Diffusion and chemical kinetics models have been employed to show that the sorption kinetics of uranyl sulfate and carbonate complexes corresponds to the mixed diffusion mechanism and is described by a pseudo-second-order equation. The sorption isotherms of uranium(VI) compounds have the pattern of L-type isotherms according to the Giles classification and are satisfactorily described by the Langmuir, Freundlich, and Dubinin–Radushkevich equations. It has been found that, within 40 min, the sorbent may be regenerated by 65–82% with a 1 M NaHCO₃ solution.