Laser Technology of Directional Microstructuring of Biodegradable Nonwovens

High Energy Chemistry - The influence of mid-IR (1.94 μm) laser radiation on the morphology of polylactide and polycaprolactone nonwoven materials obtained by electrospinning has been...     

Structure and intramolecular stabilization of geometric isomers of Bi- and trithiazolidine-4-ones and their methyl derivatives: A DFT and QTAIM study

At the DFT level with the B3LYP hybride functional the structure and relative stability of geometric isomers of bi- and trithiazolidine-4-ones are calculated. Based on Bader’s analysis of the electron density distribution the presence of intramolecular hydrogen bonds and van der Waals interactions is found in the studied isomers. Energies of these interactions are calculated. It is shown that the presence of a substituent in the thiazolidine ring affects the stabiliyty of the studied geometric isomers.     

Synthesis and biological evaluation of novel cyanuric acid-tethered tris-pyridinium derivatives

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Effect of type of dislocation structure and grain size on the applicability of the Cottrell-Stokes law in alloys

A study is made of the applicability of the Cottrell-Stokes law in the solid solutions Cu-Al, Cu-Ga, and Cu-Ge, in the ordered alloys Ni₃Mn, Ni₃(MnCo), and Ni-Mn-Fe, and also in an aging alloy on an iron-nickel-chromium base. It is shown that the applicability of the Cottrell-Stokes law is greatly affected by the nature of the dislocation structure formed during stressing and also by the grain size.     

The effect of adsorbed impurities on the surface properties of GaAs and the characteristics of electroluminescent p-n junctions

The effect of adsorbed copper and gold on the band bending, the steady-state photoconductivity, and the field-effect mobility in n-type GaA s has been studied. The light and electrical characteristics of electroluminescent p-n junctions have also been studied. It is shown that doping the GaA s surface with Cu and Au leads to an increase of the depleting band bending and to a decrease in the field-effect mobility. Copper, adsorbed at the surface of slices before diffusion, leads to a reduction of the radiative intensity of the p-junctions prepared on GaA s with an electron concentration of 1–6·10¹⁷ cm^–3, to a decrease in the cutoff voltage, and to an increase in the differential resistance of the forward branch of the volt-ampere characteristics. It is proposed that in the region of the experimental current (5·10^–2-10^–2) mA the presence of Cu in the electroluminescent p-n junctions leads not to a change in the injection mechanism but to an increase in the series resistance of the p-n junction.Translated from Izvestiya VUZ. Fizika, No. 12, pp. 72–77, December, 1973.     

Arylation of nitromethane with sterically hindered aryl halides

Efficient conditions for Pd-catalyzed cross-coupling of sterically hindered aryl halides with nitromethane were developed to give corresponding aryl nitromethanes. The opportunity to carry out the reaction of polynitromethylation under these conditions was demonstrated, as well as to use the obtained products in the synthesis of bisnitrile oxides.

     

Structure and spectral properties of truxene dye <Emphasis Type="Italic">S</Emphasis>5

On the ground of functional theory with the B3LYP and BMK functionals, we have studied the structure and optical properties of a truxene dye sensitizer S5 for photoelectric transducers. Based on the calculations of the vertical excitations energy of the dye molecule and accounting the influence of the solvent, we have revealed a positive solvatochromic effect that is weak compared to results obtained in the vacuum approximation. We have studied new features describing stabilization of the planar structure of the cyanothiophene-acrylic fragment of the S5 dye.     

Quantum-chemical investigation of the structure and electronic absorption spectra of electroluminescent zinc complexes

Using the quantum chemical methods of the density functional theory and of the electron density topological analysis, we have studied the structure of two recently synthesized electroluminescent zinc complexes, one with aminoquinoline ligands and the other with a Schiff base (N,O-donor). The energies and intensities of vertical excitations for the molecules under study have been calculated in terms of the PM3 semiempirical approximation taking into account the configurational interaction between singly excited singlet excited states. Good agreement between calculation results and experimental data on the electron density topological characteristics and on the visible and UV absorption spectra has been obtained.     

Theoretical study of the dimerization of rhodanine in various tautomeric forms

The density functional theory (DFT) was used to calculate the relative stability of rhodanine dimers and the energy of intermolecular interaction in them. Analysis of the electron density showed hydrogen bonding in the dimers. The energies of individual hydrogen bonds were determined for the symmetrical dimers. The polarizable continuum model was used to calculate the solvation (hydration) energies of the structures studied. The effect of dimerization on the position of infrared absorption bands was demonstrated.     

The Electronic Structure and Spectra of Triphenylamines Functionalized by Phenylethynyl Groups

We study the features of the electronic structure and the IR, UV, and visible spectra of a series of triphenylamines substituted with phenylethynyl groups. The analysis is performed at the level of the density functional theory (DFT) and its nonstationary version in comparison with the experimental data of IR and electron spectroscopy. It is shown that, in the excited state, there is a change in the alternation of single, double, and triple bonds in accordance with the character of bonding and antibonding in the lowest vacant molecular orbital. The gradual introduction of additional phenylethynyl groups does not cause frequency shifts in the IR spectra of the molecules under study, but significantly affects the intensity of the corresponding IR bands. A similar effect is also observed in the electronic-absorption spectra of these compounds. This can be used for optical tuning of triphenylamines as promising materials for organic light-emitting diodes and solar cells.