Fiber Raman laser at 1450 nm for medical applications

Raman-fiber source emitting 1450 nm with a power of 1 W was realized. The application of the commercially available pump source with an output power of 35 W allows one to increase the output power up to 5 W. The emission wavelength corresponds to the water absorption band therefore it is promising laser for the surgery and other medical applications.     

Isothiocyanates as derivatization reagents in the determination of 1, 1-dimethylhydrazine by gas chromatography coupled with mass spectrometry

Alkyl isothiocyanates were proposed for the determination of 1, 1-dimethylhydrazine (DMH) in the form of 4-alkyl-l, l-dimethylthiosemicarbazides by gas chromatography coupled with mass spectrometry (GC-MS). 4-Alkyl-l, l-dimethylthiosemicarbazides are selectively formed under mild conditions in the absence of catalysts. During the chromatography, these thiosemicarbazides are efficiently resolved from excess of alkyl isothiocyanates. A possibility of identification of DMH derivatives on the basis of the chromatographic retention parameters and fragmentation data under electron ionization conditions was demonstrated.     

Potential barriers of internal rotation in halogen-substituted ethanes

A simple model is proposed for calculating torsional vibrational frequencies and torsion potentials in ethane-type molecules. The model is based on internuclear coulomb electrostatic interactions of the end atoms in molecular groups undergoing rotations. The effective charges on the nuclei are considered to be the model parameters. The results of calculations show that the model can reliably reproduce the frequencies of torsional vibrations for rotational conformers and that the effective charges are transferable among halogen-substituted ethanes, both symmetrical and asymmetrical.Orenburg Pedagogical Institute. Translated from Zhurnal Strukturnoi Khimii, Vol. 34, No. 1, pp. 39–43, January–February, 1993.     

Shallow acceptors in Ge/GeSi strained multilayer heterostructures with quantum wells

The impurity photoconductivity spectra of Ge/Ge_1−x Si_x strained heterostructures with quantum wells are investigated. It is established that the built-in deformation in quantum-size Ge layers substantially changes the spectrum of shallow acceptors, shifting it into the long-wavelength region of the far-IR range. In strong magnetic fields the photoconductivity lines are observed to split and shift as a function of the field. This makes it possible to carry out a classification of the transitions. Pis’ma Zh. éksp. Teor. Fiz. 65, No. 2, 194–198 (25 January 1997)     

Radical Processes in the Low-Temperature Radiolysis of Liposome Dispersions

Processes occurring with the participation of radiolytic radicals in the low-temperature radiolysis of aqueous liposome dispersions were studied. The initial radiation-chemical yields of the resulting radicals were determined, and the transformations of these radicals upon freezing-out the systems were examined. It was found that ionol (2,6-di-tert-butyl-4-methylphenol) introduced into the lipid bilayer of liposomes is an effective scavenger of radiolytic species formed in a frozen (77 K) dispersion upon irradiation.