Optical third-harmonic generation in coupled microcavities based on porous silicon

The resonance features of the third-harmonic generation have been observed in 1D coupled microcavities consisting of three Bragg reflectors and two identical half-wave layers of mesoporous silicon. The third-harmonic intensity increases by a factor of about 10³ in the resonance of fundamental radiation with each of the modes of coupled microcavities. It has been shown that the resonance positions in the angular spectra of the third-harmonic intensity depend on the coupling between microcavities that is determined by the transmission of the intermediate Bragg reflector. In the framework of the transfer-matrix method with nonlinear sources, it has been shown that the basic mechanism of the enhancement of the third-harmonic generation in coupled microcavities based on porous silicon is the constructive interference of the partial third-harmonic waves that are generated by near-surface layers.     

The effect of preliminary orientation of polymers via tensile drawing at elevated temperature on solvent crazing

We studied how the preliminary orientation of an amorphous glassy PET via its uniaxial tensile drawing above the glass transition temperature affects the deformation behavior during subsequent tensile drawing in the presence of adsorptionally active environments. The tensile drawing of the preoriented PET samples with a low degree of preliminary orientation (below 100%) in the presence of liquid environments proceeds via the mechanism of solvent crazing; however, when a certain critical tensile strain is achieved (150% for PET), the ability of oriented samples to experience crazing appears to be totally suppressed. When the tensile drawing of preoriented samples is performed at a constant strain rate, the craze density in the sample increases with increasing degree of preliminary orientation; however when the test samples are stretched under creep conditions, the craze density markedly decreases. This behavior can be explained by a partial healing and smoothening of surface defects during preliminary orientation and by the effect of entanglement network. The preliminary orientation of polymers provides an efficient means for control over the craze density and the volume fraction of fibrillar polymer material in crazes.     

Effect of Transition Metal Diketonates on Oxidation of Sunflower-Seed Oil

Effect of transition metal (Mn, Fe, Co, Ni, Cu, Zn) diketonates on oxidation of sunflower-seed oil with atmospheric oxygen was studied.     

Specific properties of hydroxyapatite as a potential transporter of copper ions and its complexes

Russian Chemical Bulletin - Modification of the cocrystallization method for producing hydroxyapatite (HAP) and an HAP-Cu combination to the enzymatic method using alkaline phosphatase leads to a...     

New phosphonium salts based on 3-(diphenylphosphino)propanoic and ω-haloalkanoic acids

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Chiral modification of polyformyl compounds of dendrite type with optically active primary and secondary 1,2-aminoalcohols

Procedures were developed for preparation of optically active dendrones and dendrimers with terminal 1,2-hydroxylimino, 1,2-hydroxylamino and oxazolidinyl groups containing ether bonds in the branches and ester bonds in the backbone of the macromolecule. The compounds described may serve as chiral ligands for asymmetric metallocomplex catclysis.     

Femtosecond relaxation dynamics of surface plasmon-polaritons in the vicinity of fano-type resonance

Temporal modification of femtosecond laser pulses reflected from planar periodic metal nanostructures with resonant excitation of surface plasmon-polaritons is experimentally studied. Spectral time-resolved measurements of the second-order cross-correlation function performed with the pulse duration comparable with the surface plasmon-polariton relaxation time (about 100 fs) show the strong spectral dependence of the envelope of the reflected femtosecond pulse described by Fano-resonance parameters.