Ru-Containing Polymeric Catalysts for Cellulose Conversion to Polyols

In this paper Ru-containing catalysts based on hypercrosslinked polystyrene (MN-270) and its functional analogues (MN-100 and MN-500) were studied for the first time in cellulose hydrolytic hydrogenation. The catalysts were characterized using transmission electron microscopy (TEM), high resolution TEM, and porosity measurements. Catalytic studies demonstrated that the catalyst containing 1.0 % Ru and based on MN-270 is the most active. The total yield of sorbitol and mannitol was 50 % on the average at 85 % cellulose conversion.     

Defects in heteroepitaxial CdHgTe/Si layers and their behavior under conditions of implanted p +-n photodiode structure formation

The impurity-defect structure of heteroepitaxial Cd _x Hg_{1 ? x} Te/Si (0.35 < x < 0.39) layers grown by molecular beam epitaxy for the creation of arsenic-ion-implanted p ⁺-n junctions has been studied by the photoluminescence method. It is established that full realization of the possibilities of p ⁺-on-n photodiode structures based on the CdHgTe/Si system is hindered by uncontrolled doping of the material that leads to the formation of both shallow (impurity level energy ～10 meV) and deep (～50 meV) acceptor levels.     

Microstructure and Young’s modulus of high-pressure LixNa1 ? xTayNb1 ? yO3 ceramics

The microstructure and elastic properties of ceramic samples of high-pressure Li _x Na_{1 − x} Ta _y Nb_{1 − y} O₃ perovskite solid solutions have been studied for the first time in relation to their composition and the synthesis temperature. The results demonstrate that, with increasing sintering temperature, the Young’s modulus of the Li_0.17Na_0.83Ta _y Nb_{1 − y} O₃ solid solutions decreases, which can be understood in terms of the recrystallization behavior of the disordered solid solutions under high-pressure synthesis conditions.     

Monitoring system for lateral strains and seismic processes in bore-holes and underground mine workings

The article describes a seismic deformation monitoring system composed of the seismic station “Baykal-7HR” and a strain gauge station with optico-polarization sensors for lateral strains in relief bore-holes. The presented monitoring system is equipped with a GPS-receiver and a self-contained data pickup device for real-time measurement and data coordination, which is very important in controlling stress conditions of rocks in underground rooms and pillars.     

Distortion of the spatial distribution of a laser beam reflected by a VO2 mirror

The switching of controllable VO₂ mirrors with dR/dT>0 or dR/dT<0 under the action of a Gaussian-profile laser beam is modeled. It is shown that when a high-intensity laser beam is reflected by a VO₂ mirror, it undergoes appreciable spatial distortion during switching. Pis’ma Zh. Tekh. Fiz. 24, 17–22 (March 12, 1998)     

Reconstructive operations on the head and neck using a microsurgical technic

Eighty-one patients with defects and deformations of the head and neck of various origin were examined and treated. Microsurgical autotransplantation of vascularized tissue complexes was carried out in all the cases. Profound preliminary examinations of patients helped objectively define the indications for the use of this method. Special attention was paid to the choice of donor zone. Due to correct selection of a complex graft, good functional and cosmetic results were attained. Despite repeated corrective operations in 16 patients, virtually complete social and communal rehabilitation was attained in 74 (91.4%) patients by using a limited number of donor areas. The authors persuasively demonstrate the advantages of microsurgery in repair of complex and extensive defects on the head and neck.     

A small triggered high-current vacuum switch

The results of studies of the switching characteristics of small triggered PBY-27C and PBY-27Π vacuum switches with systems of rod and disk electrodes, respectively, are presented. The studies were performed during switching of pulse currents with amplitudes of up to 200 kA at a current-rise rate no higher than 2 × 10¹¹ A/s.     

Mechanism of the influence of microadditions on the oxidation resistance of high-temperature nickel alloys

The effect of rare earth metals (yttrium, cerium, praseodymium) on the oxidation resistance in cast high-temperature nickel alloys ZhS6K-V1 and ZhS6U-VI is considered from the standpoint of reducing defect concentrations in the oxides and changing the parameters of their crystal lattice.     

The antiviral action of recombinant receptorotoxins based on the diphtheria toxin and the human T-lymphocyte CD4-receptor

Lack of uniformity in the classification of oral diseases, and variability of study designs, measurements, methods, and statistical formats, hamper the interpretation, comparison and review of the evidence linking smoking and oral diseases. However, there have been a significant number of controlled studies, allowing definitive conclusions to be drawn. This review of 22 controlled scientific studies from 1983-1992, considers the role of smoking as an aetiological agent in: gingival problems (impaired gingival bleeding, ANUG), periodontal problems (periodontitis, bone loss, tooth loss), and caries.