Pulsed THz radiation under ultrafast optical discharge of vacuum photodiode.

In this paper, we first present an experimental demonstration of terahertz radiation pulse generation with energy up to 5 pJ under the electron emission during ultrafast optical discharge of a vacuum photodiode. We use a femtosecond optical excitation of metallic copper photocathode for the generation of ultrashort electron bunch and up to 45 kV/cm external electric field for the photo-emitted electron acceleration. Measurements of terahertz pulses energy as a function of emitted charge density, incidence angle of optical radiation and applied electric field have been provided.

Narrow intensity range optical anisotropy in air induced by a femtosecond laser breakdown.

In this paper, we study the optical anisotropy induced by femtosecond laser radiation in air during an optical breakdown. Using a transverse pump-probe technique, we demonstrate that this anisotropy appears in a narrow range of pump intensities, which are close to the optical breakdown threshold in air and lead to a phase shift of probe radiation, polarized collinear to the pump. The intensity range where an induced intense anisotropy occurs makes it possible to estimate the magnitude of the 5th-order Kerr nonlinear refractive index component in air.

Super-resolution THz endoscope based on a hollow-core sapphire waveguide and a solid immersion lens.

To address a challenging problem of super-resolution terahertz (THz) endoscopy, in this paper, an antiresonant hollow-core waveguide was coupled with a sapphire solid immersion lens (SIL), aimed at subwavelength confinement of guided mode. The waveguide is formed by a polytetrafluoroethylene (PTFE)-coated sapphire tube, the geometry of which was optimized to ensure high optical performance. SIL was judiciously designed, fabricated of bulk sapphire crystal, and then mounted at the output waveguide end.

THz generation by two-color laser air plasma coupled to antiresonance hollow-core sapphire waveguides: THz-wave delivery and angular distribution management.

In this paper, hollow-core antiresonance sapphire waveguides were applied to guide the THz radiation emitted by the two-color laser air plasma, as well as to manage the THz source angular distribution. For this aim, three distinct waveguides were developed. Each of them is based on a cylindrical sapphire tube, either suspended in free space or coated by a polymer.

Photoconductive terahertz generation in nitrogen-doped single-crystal diamond.

The generation of terahertz radiation in a photoconductive emitter based on nitrogen-doped single-crystal diamond was realized for the first time. Under 400 nm femtosecond laser pumping, the performance of diamond antennas with different dopant levels was investigated and compared with a reference ZnSe antenna. Terahertz waveforms and corresponding spectra were measured.

Tunable-shift stimulated Raman scattering in water by chirped 50 fs to 4.5 ps UV-pulses.

Forward stimulated Raman scattering (SRS) induced by focused 400 nm pulses chirped to different pulse durations is observed in water and heavy water. The first Stokes Raman peak shift is shown to be tunable in the range of ${{3500 {-} 4200}}\;{{\rm{cm}}^{- 1}}$ in water and ${{2450 {-} 3250}}\;{{\rm{cm}}^{- 1}}$ in heavy water. It is demonstrated that the Stokes peak shift increases for shorter pulse durations and higher intensities.

Hybrid Perovskite Terahertz Photoconductive Antenna.

Hybrid organic-inorganic perovskites, while well examined for photovoltaic applications, remain almost completely unexplored in the terahertz (THz) range. These low-cost hybrid materials are extremely attractive for THz applications because their optoelectronic properties can be chemically engineered with relative ease. Here, we experimentally demonstrate the first attempt to apply solution-processed polycrystalline films of hybrid perovskites for the development of photoconductive terahertz emitters.

Ring and unimodal angular-frequency distribution of THz emission from two-color femtosecond plasma spark.

We study angular and frequency-angular distributions of the terahertz (THz) emission of the low-frequency region (0.3-3 THz) from a two-color femtosecond plasma spark experimentally and in three-dimensional numerical simulations. We investigate the dependence of the angular shapes of the THz radiation on focusing conditions and pulse durations by using two laser facilities (pulse durations 35 and 150 fs) for different focusing geometries.

Combining Raman and laser induced breakdown spectroscopy by double pulse lasing.

A new approach combining Raman spectrometry and laser induced breakdown spectrometry (LIBS) within a single laser event was suggested. A pulsed solid state Nd:YAG laser running in double pulse mode (two frequency-doubled sequential nanosecond laser pulses with dozens microseconds delay) was used to combine two spectrometry methods within a single instrument (Raman/LIBS spectrometer). First, a low-energy laser pulse (power density far below ablation threshold) was used for Raman measurements while a second powerful laser pulse created the plasma suitable for LIBS analysis.

Plasma filament investigation by transverse optical interferometry and terahertz scattering.

Transverse plasma distribution with 10(17) cm(-3) maximum electron density and 150 μm transverse size in a plasma filament formed in air by an intense femtosecond laser pulse was measured by means of optical interferometry. Two orders of magnitude decay of the electron density within 2 ns was obtained by combined use of the interferometry and newly proposed terahertz scattering techniques. Excellent agreement was obtained between the measured plasma density evolution and theoretical calculation.

Molecular epidemiology of the hepatitis C virus in Western Siberia.

Western Siberia is the region with little information on the prevalence of hepatitis C virus (HCV) infection, genotypic diversity of HCV isolates and risk factors. A molecular epidemiological survey was conducted to clarify these issues. Four groups of volunteers were included in a cross-sectional study (n = 500 in each group): health care workers; daycare patients from a hospital for drug users, daycare patients from an AIDS prevention and control center; and persons admitted to a local general practice clinic for any reason (outpatients).

[The occurrence rate of HGV/GBV-C RNA and risk factors in patients of narcological dispensary in Novosibirsk].

The occurrence rate of HGV/GBV-C RNA, genotypic variety of isolates and various risk factors of infection with HGV/GBV-C were evaluated in 500 patients of the narcological dispensary of Novosibirsk. The occurrence rate of HGV/GBV-C RNA among all examined blood sera was 33.6%.

[Volume effect and change in compressibility in intercalation of ethidium bromide and daunomycin in DNA].

A combination of high-precision and density techniques was used to investigate the binding of ethidium bromide and daunomycin to DNA. It was shown that intercalation is accompanied by a decrease in apparent volume and adiabatic compressibility of DNA, which were -28 cm3mol-1 and -20.10(-4) cm3mol-1bar-1 for binding of ethidium to DNA, and -28 cm3mol-1 and -18.

[Experimental study of DNA hydratation].

The present article as a review of experimental investigations of water-DNA interaction in solutions, films, fibres, and crystals. The discussion of the experimental data is directed to the analysis of the sizes of the hydration shells of the DNA atomic groups, the distances at which atomic groups of DNA affect the hydration of each other; the structural, thermodynamic and kinetic characteristics of the water in the DNA hydration shell and their relations with DNA structure. The modern views on the mechanisms by means of which the water affects the physico-chemical properties of DNA are discussed.

[Indices of phagocytosis of S and R forms of Brucella in patients with acute and chronic brucellosis caused by Brucella abortus].

The characteristics of phagocytosis (phagocytic activity and phagocytic index) in patients with acute and chronic brucellosis have been studied with B. abortus S- and R-forms used as its objects. The study has revealed that higher characteristics of phagocytosis with respect to B.

[Binding of bis-(2-guanidoethyl)disulfide with DNA and polyriboadenylic acid in an aqueous solution. Study by ultrasonic velocimetry].

The interaction of DNA and poly(A) with bis-(2-guanidoethyl)disulfide (GED) which is the most simple model of arginine containing proteins has been investigated by means of ultrasonic velocimetry. It has been shown that the association of GED with nucleic acids proceeds by two stages. The stoichiometric relationships and association constants for each of these stages are estimated.

[Spectral changes in the liver microsomal cytochrome P-450 of rats during interaction with phenazepam and its 3-hydroxy metabolite].

Phenazepam (I) and 3-hydroxymetabolite (II) interacting with cytochrome P-450 of the liver of rats administered phenobarbital and 3-methylcholantrene demonstrated the 2nd type of spectral changes in hemoprotein. The binding constants of I and II considerably differ, which points to the possibility of interaction of substrates with different areas of hemoproteins. The characteristic points (maximum, minimum, isobestic) of the cytochrome P-450 spectrum were displaced during II titration to the longwave region as compared with I.

[Anesthesia and intensive therapy in acute suppurative peritonitis].

The investigation of indices of hemodynamics and oxygen regimen in 58 patients with acute purulent peritonitis has shown the programmed intravenous narcosis in combination with Darenthin to promote increasing the cardiac and stroke index. Darenthin included in the complex intensive therapy of peritonitis was found to increase the portal blood flow and to cause early reestablishment of the intestine peristalsis.

[Study of vesicular lipid membranes by the ultrasound method].

The elastic properties of vesicular lipid membranes using high precision ultrasound velocity measurements in egg lecithin bilayer liposomes suspensions were studied. The temperature and K2SO4 concentration dependence of the hydrophobic part of the membrane elastic properties were obtained. The ionic strength dependence is shown to be linear and to change its sign at 27.