Study of chromium ion sorption on modified silica ordered materials

The sensitivity of chemical sensors depends on the number of receptors on the surface; hence, an important role is played by the accessible support surface. Films based on silica mesoporous mesophase materials feature the highest specific surface area for silica materials, and their walls can be modified by various functional groups. In this paper, we propose to use mesoporous mesophase films as supports of sensitive elements for Cr³⁺ ions.     

Nanosecond electrical discharges between semiconducting sulfide mineral particles in water

A model for developing electric discharges between sulfide mineral (pyrite) particles under high-voltage nanosecond pulses in a liquid medium (water) is considered. A possibility of electrical breakdowns of liquid gaps between particles under nanosecond pulses is shown. This probability and the energy released in discharge channels depend strongly on the sulfide conductivity.     

Novel ligands based on bromosubstituted hydroxycarbonyl [2.2]paracyclophane derivatives: synthesis and application in asymmetric catalysis

New planar-chiral hydroxycarbonyl [2.2]paracyclophane derivatives, 4-acetyl-13-bromo-5-hydroxy[2.2]paracyclophane (Br-АНРС, 63%) and 4-benzoyl-13-bromo-5-hydroxy[2.2]paracyclophane (Br-BHPC, 53%), were synthesized and reacted with the enantiomers of α-phenylethylamine to form corresponding Schiff bases, 12-bromo-4-hydroxy-5[1-(1-phenyl-ethylimino)-ethyl]-[2.2]paracyclophane and 12-bromo-4-hydroxy-5[1-(1-phenyl-ethylimino)-(phenyl)methylen-[2.2]paracyclophane. The diastereomers of the imines were resolved and their absolute configurations and consequently the corresponding configurations of the enantiomers of Br-АНРС were determined by X-ray diffraction. Enantiomerically pure Schiff bases were applied as ligands to form catalysts for the enantioselective addition reaction of diethylzinc with benzaldehyde where 1-phenylpropanol was obtained with 77–91% ee.     

A new nonlinear-wave-equation formalism for stimulated Brillioun scattering

A revised formalism of SBS is given based on a new optical nonlinear wave equation which explicitly accounts for the macroscopic spatial inhomogeneity resulting from the induced acoustic wave in the medium. The new equation applies to other scattering phenomena, and more generally to optical wave propagation and interaction in nanostructured media for which characteristic spatial scale lengths of material structures (existing or optically induced) are smaller than the optical wavelength.     

Secondary Ion Mass Spectroscopy of Zinc Selenide Crystals with Photoconductivity Spectral Memory

Russian Physics Journal -     

Estimates of Conformal Radius and Distortion Theorems for Univalent Functions

A simple proof of the recent result by E. G. Emel'yanov concerning the maximum of the conformal radius r(D,1) for a family of simply connected domains with a fixed value r(D,0) is given. A similar problem is solved for a family of convex domains. Exact estimates for functionals of the form are obtained for families of functions inverse to elements of the classes S and S_m, where S={f:f is regular and univalent in the disk {z:|z| < 1} and f(0)=f'(0)-1=0} and S_M= for . Bibliography: 7 titles.     

Analysis of Bulk and Powdered Samples Using a LAMAS-10M Laser Ionization Time-of-Flight Mass Spectrometer

The problem of the modernization of a LAMAS-10M laser desorption/ionization time-of-flight mass spectrometer was considered, and the methodological fundamentals of the quantitative analysis of bulk and powdered samples by laser desorption/ionization time-of-flight mass spectrometry were discussed. Basic modifications of certain spectrometer units were described, and the reproducibility and accuracy that can be attained using these modifications were estimated. The possibility of the quantitative analysis of bulk samples was demonstrated. These studies were performed using bulk and powdered standard reference materials. In determining precious metals in geological samples, the detection limit for powdered samples was (20–50) × 10^–9. The relative standard deviation for the repeatability of the results (RSD) of the bronze standard reference sample bronza 663 was in the limits RSD = 0.06–0.4% for the major component and 0.5–4.5% for the elements present in percent concentrations. It was shown that the majority of analytes can be determined at a semiquantitative level without using standard reference materials. The key problems of laser desorption/ionization time-of-flight mass spectrometry were considered and methods were proposed to solve these problems. Ways to further improvement of the characteristics of the mass spectrometer were demonstrated.     

Evonogenin

Conclusions The structure of a new cardiac aglycone, evonogenin, isolated from the seeds ofEvonymus europaea auct. has been established. Evonogenin is 1, 3, 5, 14-tetrahydroxycard-20(22)-enolide.Khimiya Prirodnykh Soedinenii, Vol. 5, No. 5, pp. 386–389, 1969