Biomedical subjects

S A Vasiliev

Publications and source records attributed to S A Vasiliev.

5 recordsLinked to original sources

PubMed2006

Increased solubility of molecular hydrogen in UV-exposed germanosilicate fibers.

Spectral properties of photoinduced fiber Bragg gratings written in germanosilicate fibers and subjected to hydrogen loading at a pressure of 150-170 MPa have been studied. It was observed, for the first time to our knowledge, that hydrogen dissolution in the glass network at such high pressures leads not only to a Bragg wavelength shift but also to a considerable alteration of the grating reflectivity. The relative magnitude of the latter effect is independent of the dissolved hydrogen concentration and is defined mainly by the core glass properties and the UV-irradiation conditions. The alteration of the grating reflectivity observed experimentally is explained by increased solubility of molecular hydrogen in UV-exposed germanosilicate glass.

Journal Article↗

PubMed2004

Germania-glass-core silica-glass-cladding modified chemical-vapor deposition optical fibers: optical losses, photorefractivity, and Raman amplification.

Germania-glass-core silica-glass-cladding single-mode fibers (deltan as great as 0.143) with a minimum loss of 20 dB/km at 1.85 microm were fabricated by modified chemical-vapor deposition. The fibers exhibit strong photorefractivity, with type IIa index modulation of 2 x 10(-3). A Raman gain of 300 dB/(kmW) was determined at 1.12 microm. Only 3 m of such fibers is sufficient for constructing the 10-W Raman laser at 1.12 microm with a 13-W pump at 1.07 microm.

Journal Article↗

PubMed2004

Tunable single-frequency diode laser at wavelength lambda = 1.645 microm for methane concentration measurements.

This paper deals with the development of a novel single-frequency tunable diode laser with fiber-optic output for gas-analysis applications. The approach we propose is a convenient, simple and cheap solution for spectroscopy of single absorption lines of any gases having absorption bands in the optical fiber transparency window (0.7 microm/1.7 microm). The presence of fiber-optic output is an additional advantage for remote sensing applications. The laser operation is demonstrated as applied to R7 line of 2 nu(3) methane absorption band at lambda = 1.645 microm. The mode-hop-free tuning range of 35 GHz (1.2 cm(-1)) has been achieved.

Lasers↗

PubMed1996

Deficiency of P-selectin in a patient with grey platelet syndrome.

Patient B.G. is a 29-yr-old female with a lifelong bleeding disorder characterized clinically by a highly increased bleeding time, menorrhagias, long-lasting bleeding after cuts and tooth extractions and large post-traumatic haematomas. Her coagulation tests were within normal range, platelet count was 140,000-160,000 per microliters, but platelet function was impaired as demonstrated by the absence of collagen-induced aggregation, although no abnormalities were detected in aggregation response to ADP and ristocetin. Morphologically her platelets were characterized by gigantic size-average profile area was about 2.5 times higher than that of control donors, and severe deficiency of alpha-granules-only 16% of their number in control donors. These features taken together indicated the diagnosis of grey platelet syndrome. As has been shown by quantitative immunoblotting, patient's platelets contained small amounts of alpha-granule membrane protein P-selectin-about 15% of that in control donors. The content of plasma membrane glycoproteins IIb-IIIa and Ib was not reduced, suggesting the specific deficiency of alpha-granule membrane protein. Thus, B.G. is the second patient described in the literature (see also Lages et al, J Clin Invest 1991: 87: 919-929) with combined deficiency of alpha-granules and P-selectin.

Adenosine Diphosphate↗

PubMed1985

[Effect of the method of extracorporeal heparin precipitation of plasma proteins (selective plasmapheresis) on the level of immune complexes in the blood].

A study was made of the effect of selective plasmapheresis (SPP) on the concentration of circulating immune complexes (CIC). The method is based on precipitation at 4 degrees C of plasma fibronectin and associated macromolecular complexes by means of heparin. Sterile plasma of the patient is separated from the precipitate, frozen and kept at -20 degrees C till the next plasmapheresis during which it is returned to the patient instead of the donor's one. All 15 patients examined were exposed to 6 SPP with an interval made every 2 to 5 days. Six patients were diagnosed to have rheumatoid arthritis, 2 systemic lupus erythematosus, 3 hemorrhagic microthrombovasculitis, and 4 multiple sclerosis. The concentration of CIC was measured by precipitation with 3.5% polyethylene glycol before and after SPP, in some cases between sessions. All the patients with rheumatoid arthritis and systemic lupus erythematosus and 2 out of the 3 patients with hemorrhagic vasculitis showed an elevated content of CIC (greater than 0.150 Units OD). The CIC content appeared normal in all the patients with multiple sclerosis. After SPP 4 patients manifested a reduction in the CIC concentration, whereas in 6 it returned to normal. Such a time course correlated with the improvement of other clinical and laboratory findings. It was established that after the first session of SPP the CIC content sharply declined followed by a gradual increment and exceeded the initial values toward the beginning of the second session. After the second SPP the patients manifested the same tendencies. The CIC content reached a maximum by the third SPP and then fell from session to session.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗