Positronium Laser Cooling via the 1

We report on laser cooling of a large fraction of positronium (Ps) in free flight by strongly saturating the 1^{3}S-2^{3}P transition with a broadband, long-pulsed 243 nm alexandrite laser. The ground state Ps cloud is produced in a magnetic and electric field-free environment. We observe two different laser-induced effects. The first effect is an increase in the number of atoms in the ground state after the time Ps has spent in the long-lived 2^{3}P states. The second effect is one-dimensional Doppler cooling of Ps, reducing the cloud's temperature from 380(20) to 170(20) K. We demonstrate a 58(9)% increase in the fraction of Ps atoms with v_{1D}<3.7×10^{4} ms^{-1}.

Lensless optical encryption with speckle-noise suppression and QR codes.

The majority of contemporary optical encryption techniques use coherent illumination and suffer from speckle-noise pollution, which severely limits their applicability even when information encoded into special "containers" such as a QR code. Spatially incoherent encryption does not have this drawback, but it suffers from reduced encryption strength due to formation of an unobscured image right on top of the encrypted one by undiffracted light from the encoding diffraction optical element (DOE) in axial configuration. We present a new lensless encryption scheme, experimentally implemented with two liquid crystal spatial light modulators, that does not have this disadvantage because of a special encoding DOE design, which forms desired light distribution in the photosensor plane under spherically diverging illumination without a converging lens. Results of optical experiments on encryption of QR codes and successful information retrieval from decoded images are presented. Conducted analysis of encryption strength demonstrates sufficiently high key sensitivity and large enough key space to resist any brute force attacks.

Hypothermic Preservation of Red Blood Cells in Different Conditions of Inert Gas Xenon: Hyperbaria and Clathrates.

BACKGROUND: Xenon is an inert gas promising for the preservation of biomaterials, which forms clathrate hydrates above 0°C. OBJECTIVE: This study addresses the effect of hyperbaric xenon (P = 303 kPa) and water-xenon clathrates (P ≥ 608 kPa) on 30 days preservation of red blood cells (RBCs) at +4°C. MATERIALS AND METHODS: RBCs from healthy human donors were preserved under four different conditions: without preservatives (negative control), in CPDA-1, hyperbaric xenon, and xenon clathrate hydrates. RESULTS: The qualitative (mean RBC volume, anisocytosis degree and mean osmotic fragility) and quantitative characteristics (RBC count and hemolysis degree) of preserved RBCs were measured. CONCLUSION: The positive role of hyperbaric xenon in the preservation of erythrocytes is attributed to the equilibrium extraction and displacement of O2 and CO2 by xenon. The effect is presumably due to a lowering of oxygen concentration and a decrease in the production of reactive oxygen species.

[The complications of laser surgery for the treatment of chronic vasomotor rhinitis].

The objective of the present study was to reveal cases of complications developing after laser coagulation of inferior turbinated bones. This treatment was given to 322 patients presenting with vasomotor rhinitis. A surgical ND:YAG laser with a quartz light guide 400 mcm in diameter was used for the purpose. In the majority of the cases, a single irradiation session produced a persistent positive effect, both functional and morphological. At the same time, two patients developed an unusual complication in the form of osteomyelitis of an inferior turbinated bone with its sequestration.

[Corrosive activity of natural microbial associations at various conditions of cultivation].

Influence of microbial associations isolated from different ecological niches on corrosion of mild steel was changed depending on composition of medium and aeration regime. Both decrease and increase in corrosion losses were observed, which indicated that the subdivision of microorganisms into destructors and passivators of corrosion is merely conventional.

[NMR-relaxation in hydrated collagen from the spotted dogfish]].

Collagen samples from dog-fish egg case at different water content were studied by the 1H NMR relaxation method. The dependences of the proton spin-lattice and spin-spin relaxation rates on the concentration of water in hydrated native collagen were measured. The fractions of water protons of different mobility and their corresponding spin-spin and spin-lattice relaxation rates were determined in a multi-phase model of water protons in natural biopolymer-water systems. The correlation times were calculated as the characteristics of molecular motion in hydrated collagens with different content of absorbed water. The results obtained were compared with literature data of pulse NMR studies of molecular mobility in other collagen fibers.

[The properties of natural silk fibers: deformation study and NMR data]. / Svoistva volokon prirodnogo shelka: deformatsionnye issledovaniia i IaMR-dannye.

Natural silk (Bombyx mori) fibers with low humidity (0.07 g H2O/g dried silk) after temperature influence were studied for mechanical longitudinal deformation. On the basis of the stress-strain curves, some estimates of tensile properties for silk fibers were obtained. It was found that the maximal tension (sigma(max) in tensile-linear field of deformation of silk fibers decreases with increasing fiber diameter. The results showed that the heating of fibers (100 degrees C) results in a diminishing of the sigma(max)-value. Scanning electron microscopy pictures for cross section and longitudinal fiber surface were obtained. Natural silk fibers were studied by the NMR relaxation method (free induction decay curves) and the second moments of NMR-line shape in silk samples were calculated. The intra- and intermolecular contributions into the second moment were analyzed. The results showed a strong interaction of water molecules with macromolecules and a low molecular mobility. Some characteristics of interactions between silk macromolecules and water molecules as well as the role of intermolecular links in the change of the structure-function properties of natural silk under the action of external factors are discussed.

[The molecular mobility of water in natural polymers: silk Bombyx mori with a low water content as studied by 1H DQF NMR]. / Molekuliarnaia podvizhnost' v prirodnykh polimerakh: shelk Bombyx mori s nizkim soderzhanien vody po dannym 1H DQF IAMR.

The molecular mobility of water in fibres of natural silk (Bombyx mori) was studied by the double-quantum-filtered (DQF) and single-pulse 1H NMR techniques. The results obtained showed a slow motion of water molecules and their strong interaction with silk macromolecules. At different model functions for resonance lineshape in 1H NMR spectra, the influence of signal linewidth on the estimation of relaxation times and cross-relaxation parameters was considered. The observed 1H DQF NMR signal in B. mori silk fibres (BC = 0.065) indicated a local order and anisotropic motion of water molecules, which leads to 1H-1H dipolar interactions in natural silk fibers due to the creation of the second-rank tensors (T(2,+1), T(2,-1)). DQF spectra were the difference of two Lorentzians with different linewidths and were analyzed using the theory of 1H DQF NMR and the data on residual dipolar interactions in systems with the anisotropic mobility of water molecules. The residual dipolar interactions was insignificant and, as the humidity increased (0.18), no DQF-signals and residual dipolar interactions were observed.

[Natural polymers according to NMR data: cross-relaxation in hydrated collagen macromolecules from two connective tissues]. / Prirodnye polimery po dannym IaMR: krossrelaksatsiia v makromolekulakh kollagena iz dvukh soedinitel'nykh tkanei.

Spin-lattice relaxation and cross-relaxation in oriented and randomly oriented collagen fibers from two connective tissues (15-month-old calf and 8-year-old steer) at a water content of 0.6 g H2O/g dry matter were studied. Collagens were chosen according to different numbers of covalent nonreducible cross-links, which increase during the life of the animal. The spin-lattice relaxation curves for all the collagens after a 180 degree-tau-90 degree pulse sequence were described by two exponential components. The dependences of two components of spin lattice relaxation time and their populations on the length of the 180 degree-pulse were obtained. On the basis of data of Goldman-Shen sequence and the two-phase model, the populations of proton fractions (p(w) and p(c)) as well as the rates of transfer of magnetization between water protons and collagen protons (k(w) and k(c)) were calculated. No significant difference between k(w) (k(c)) in oriented and randomly oriented fibers as well as in fibers with different cross-linking was found. The estimates of the cross-relaxation times for low cross-link collagen and high cross-link one were done. The correlation times of dipole-dipole interactions for both connective tissues were calculated using the cross-relaxation theory.

[Unit of electrochemical oxidation of hemodialysis products--development and research]. / Blok élektrokhimicheskogo okisleniia produktov gemodializa--razrabotka i issledovanie.

Some aspects related with research and development of a key functional unit of the hemodilysis apparatus with the electrochemical regeneration of dialyzate, i.e. the electrochemical oxidation unit which enables a regulated electrochemical oxidation of the main organic hemodilysis products in the waste dialyzate, are described.

[Self-diffusion of water into silk fibers from magnetic field pulse gradient data]. / Samodiffuziia vody v volokonakh prirodnogo shelka po dannym impul'snogo gradienta magnitnogo polia.

Self-diffusion of water was studied in fibers of natural silk (Bombyx mori) with a water content of 0.18 g H2O/g dried material. Self-diffusion measurements were conducted by pulsed gradient of magnetic field (stimulated echo) at diffusion times from 10 to 200 mc. The dependence of experimental diffusion coefficients Dexp = f(delta) (observed decrease when delta increased) was determined to be responsible for the restricted diffusion. A model of planar and regularly spaced permeable barriers to diffusion of water molecules was applied to estimate the barrier spacing a and the permeability constant p. The maximal value of Dexp (at short diffusion time) in B. mori silk fibres was about 0.06 of the value of Dexp in bulk free water. The results obtained are compared to literature data on self-diffusion of water in hydrated biopolymer fibers and are discussed in connection with molecular mobility in natural macromolecular systems with low water content.

[State of the art and outlook for promoting Russian-made hemodialysis equipment with regeneration of dialyzing solution]. / Sovremennoe sostoianie i perspektivy razvitiia otechestvennoi gemodializnoi apparatury s regeneratsiei dializiruiushchego rastvora.

Radical improvements in the physiological features and self-sufficiency of hemodialysis equipment, an essential reduction of the volume of dialyzate contacting with patient's body and elimination of dependence of the equipment operation on the availability of a water-supply network can be ensured by applying a regime of circulation of a relatively small volume (3-5 l) of dialyzate through the regenerating device. The regeneration unit must eliminate the organic products of dialysis from the dialyzate and stabilize the ionic composition of the purified dialyzate according to the preset parameters. Modern methods and technical means for regenerating the used dialyzate are discussed; a regeneration unit, which ensures an electrochemical oxidation (in the used dialyzate) of nitrogen-containing organic metabolites with a subsequent sorption-type additional purification of electrochemically-processed dialyzate, is offered. The regeneration unit is made up of an electrolyser, a sorption-type additional-purification device and a gas utilizer; it eliminates organic metabolites, phosphorus, calcium and potassium from the used dialyzate and stabilizes the pH solution.

[Optimization of dynamic fuzziness and enhancement of image quality of an URI/230-Amethyst digital image intensifier]. / Optimizatsiia dinamicheskoi nerezkosti i povyshenie kachestva izobrazheniia tsifrovogo usilitelia rentgenovskogo izobrazheniia URI/230-"Ametist."

In X-ray diagnostic units, digital image intensifiers with a SSD matrix have recently been used instead of vacuum vidicons. Along with the well-known advantage of SSD matrixes, they fail to reach the capacities of vidicons in transmitting movable images. The authors consider that the way out of this situation is to use recursive filters and arithmetic logic devices. The automatically used filters are particularly original.

[Initial stages of steel biocorrosion]. / Issledovanie nachal'nykh étapov biokorrozii stali.

Initial stages of corrosion of mild steel induced by Klebsiela rhinoscleromatis BO2 were studied in various media. The effect of the microorganism was detected 8-10 h after inoculation. The number of viable cells were virtually unchanged within one month in all media, but the corrosive activity of the strain decreased. The corrosive activity of microorganisms can be determined by spectrophotometry even only after incubation for 24 h. At a low level of organic substrate, even strong colonization with microorganisms does not inevitably result in a significant damage to metals.

[Chemical-microbiological diagnosis of stress-corrosive damage to pipelines]]. / Khimiko-mikrobiologicheskaia diagnostika stress-korrozionnykh povrezhdenii magistral'nykh truboprovodov.

Samples of soil, ground, electrolyte, corrosion products, and protective coating were taken after excavating pipelines. The depth of stress corrosion cracks of the pipe steel was mostly related to the numbers of sulfate-reducing and denitrifying bacteria. In certain types of soil, damage correlated with the number of acid-producing microorganisms and aerobic chemoorganotrophs (saprophytes). A correlation was found between the extent of stress-corrosion damage to pipelines and the contents of reduced iron, sulfides, and organic carbon in surrounding ground.

[Direct quantitative method for evaluating the effect of biocides on Pseudomonas fluorescens in different culture media]. / Priamoi kolichestvennyi metod otsenki deistviia biotsidov na Pseudomonas fluorescens na raznykh pitatel'nykh sredakh.

A method for quantitative evaluation of the effects of biocides is presented. The method was tested in experiments with Pseudomonas fluorescens grown on various agar nutrient media. The effective concentrations of biocides that decreased the maximum specific rate of the colony biomass growth (mu'm) were called S (suppressing) concentrations, and concentrations that decreased the number of colony-forming units (CFU) were taken as L (sublethal) concentrations. The efficiency of the reported approach was demonstrated in experiments with three biocides tested in four nutrient media. It was found that the biocide sensitivity of Pseudomonas fluorescens varied by a factor of 30, depending on the amount and the type of the nutrient substrate.

[Increase in the ecological danger upon the use of biocides for fighting corrosion induced by microorganisms]. / Povyshenie ékologicheskoi bezopastnosti pri ispol'zovanii biotsidov dlia bor'by s korroziei, indutsiruemoi mikroorganizmami.

Five synergistic combinations of biocides were found, among which the combination of kathon + copper sulfate was the most efficient against Serratia marcescens. Depending on the ratio of these biocides, the synergistic effect of this pair allowed 4-20-fold decreases in the effective concentrations. Combinations of biocides with salts (carbonates and phosphates) that facilitate passivation of steel were found, which considerably decreased the corrosion losses of mild steel in comparison to isolated treatment with biocides or salts. The data showed that biocides must be added to corrosion-prone systems simultaneously with the beginning of their exploitation. Otherwise, considerably excessive amounts of biocides or their synergistic compositions are needed.

[Development of biological methods of combating steel corrosion, induced by aerobic microorganisms]. / Razrabotka biologicheskikh metov bor'by s korroziei uglerodistoi stali, indutsirovannoi aérobnymi mikroorganizmami.

Cocultivation of degrading microorganisms and their antagonists decreases the corrosion loss of carbon steel by 20 to 80%. It was found that a microorganism can either accelerate or inhibit corrosion, depending on the nutrient. The magnitude of the effect on corrosion depends on the ability of the microorganism to respond to changes in the nutrient-medium composition by releasing acidic or alkaline metabolites.

[The characteristics of digital electron optical systems for x-ray diagnosis]. / Osobennosti tsifrovykh élektronno-opticheskikh sistem dlia rentgenodiagnostiki.

The paper deals with the specific features of X-ray diagnostic units that have no screen-filming device for film X-ray study, with the requirements for hardware and software of these units. It gives data on specific systems for digital X-ray study.