Possibility of reconstructing hydrological variability of shallow sea by measuring frequency shifts of interference structure of sound field

Variations in the vertical space-frequency interference structure of the sound field in the oceanic waveguide are described. Reconstruction algorithms of sound speed field, based on information on frequency shifts of interference maxima of the sound field, are presented.     

Bacteriochlorin <Emphasis Type="Italic">e</Emphasis><Subscript>6</Subscript> as a sensitizer for photodynamic therapy

A simple scheme of modification of the native pigment bacteriochlorophyll a, extracted from the biomass of phototropic bacteria, for the purpose of obtaining a water-soluble derivative — bacteriochlorin e ₆ — which is similar in molecular structure to the effective sensitizer chlorin e ₆ and, in addition, has an intense longwave absorption band in the near-infrared region of the spectrum where biological tissues weakly absorb light — has been developed. The ease of production of bacteriochlorin e ₆ in combination with its physicochemical and spectral properties allow it to be considered as a promising sensitizer for photodynamic therapy.Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 71, No. 6, pp. 745–748, November–December, 2004.This revised version was published online in April 2005 with a corrected cover date.     

New Effects in the Poly-N-Vinylcaprolactam/Titanium(IV) Oxides Nanocomposite System and Their Nature

Nanocomposites based on poly-N-vinylcaprolactam (PVC), characterized by different drying temperatures of aqueous PVC solution at 25°С (PVC25) and 40°С (PVC40), with titanium(IV) oxide nanoparticles (TONs) (η-phase (TP: TiO_{2 – x} · mH₂O) with a superstructure to the anatase structure and ordered solid solution with partial replacement of oxygen atoms in the η-phase with peroxo group O ₂ ^2– (PP: TiO _x (O₂)_{2 – x} · nH₂O)) have been obtained for the first time and characterized by X-ray diffraction and IR spectroscopy. It is found that a common feature of TP/PVC and PP/PVC obtained by dry mixing and grinding is the decrease in the number of water molecules for TP and PP in the interlayer space of the structure and their attachment to the PVC amide groups; the differences are related to the specificity of PVC behavior in these systems: mechanodestruction of PVC in PP/PVC40 and different numbers of water molecules in PVC25 and PVC40.     

Reconstruction of internal waves in oceanic waveguides

Reconstruction of the temporal variability of an intense internal wave field is studied by a numerical experiment. The inverse problem is solved using the data on the frequency shifts of the maxima of the inverted wave field. The influence of the amplitude of the internal wave on the efficiency of reconstruction is analyzed.     

Maleic acid solvation in mixed water-ethanol solvents

Heat effects of maleic acid dissolution in mixed water-ethanol solvents at 298.15 K are determined by means of calorimetry. A rise in exothermicity of maleic acid solvation is observed upon changes in the solvent copmosition in the direction of H₂O → EtOH, the minimum being at ∼0.2 mol fraction of EtOH.     

Synthesis of thiacyanine dyes containing coumarin moieties at benzothiazole rings

New bischromophoric dyes (thiacarbocyanine and thiadicarbocyanine) containing coumarin moieties at each of the two benzothiazole systems, as well as monomethinecyanine containing coumarin moiety at only one heterocyclic system, manifest significant batho-chromic shift compared to relative coumarin-free dyes.     

Triplet states of humic acids studied by laser flash photolysis using different excitation wavelengths

The spectra and kinetics of short-lived intermediates formed from aqueous (0.1 N NaOH) solutions of the natural mixture of humic and fulvic acids (HFA) were studied by laser flash photolysis using excitation wavelengths of 337, 390, 470, and 520 nm. Laser photolysis of HFA with light of 520 and 470 nm results in the formation of triplet excited states (T_HFA) characterized by the broad absorption spectrum with a maximum near 630 nm and lifetimes of 0.15 ms in deoxygenated solutions. The formation of two types of T_HFA with lifetimes of 0.1 and 2 ms and absorption spectra with maxima at 570 nm is observed under photolysis with light of 337 and 390 nm. The estimation of quantum yields of T_HFA gives 1 and 0.3% under photolysis with excitation wavelengths of 337 and 520 nm, respectively. The rate constants of T_HFA quenching by molecular oxygen are equal to (7—8)·10⁸ L mol^–1 s^–1.     

Stereospecific [2+2] autophotocycloaddition in the dimeric complex of 18-crown-6 ether styryl dye bearing N-(3-ammoniopropyl) substituent

New 18-crown-6 ether styryl dye of the 4-pyridine series bearing N-(3-ammoniopropyl) substituent has been synthesized. In MeCN, the dye forms a stable dimeric complex of the syn-head-to-tail type due to the complexation of the ammonium group of one molecule with the crown ether fragment of another. In the dimeric complex, the ethylene bonds of the molecules are close in space and antiparallel, which promotes an efficient stereospecific [2+2] autophotocycloaddition to yield the only rctt-isomer of 1,2,3,4-tetrasubstituted cyclobutane. The cyclobutane derivative structure was confirmed by NMR spectroscopy and X-ray diffraction.     

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.