Search

In the process of performing the work, an extruder was designed for the manufacture of metal-polymer filament for additive technologies, of sufficient power, characterized in that it has a cooled screw, which allows to reduce the forces for mixing the mass, as well as a tungsten carbide coating, which has high wear resistance. The extruder will be loaded with a pre-prepared mixture consisting of polymer and metal powder.

The effective input noise temperature Te of a bridge made from a highly oriented YBaCuO film is measured at a frequency of 4.6 GHz. The bridge is brought to a weakly resistive state by a dc current, by microwave radiation at a frequency of 9.4 GHz, or by a combination of the two. Along with the noise temperature, the current-voltage characteristics and impedance of the bridge are also measured at a frequency of 4.6 GHz. At T=78 K the value of Te does not exceed 120 K. Analysis of the results allows one to compare the experimental values of Te with the values determined by the equilibrium Nyquist noise of overheated normal domains and indicates the presence of excess noise at a level comparable to the Nyquist noise.

The microwave engineering is on the threshold of the design and manufacture of Cryogenic Microwave Integrated Circuits (CMIC) based on high-T c superconductors (HTSC), operating at the liquid nitrogen temperature. Along wihh HTSC delay lines, filters, and resonators, active components (modulators, switches, phase shifters) and nonlinear components (signal limiters and mixers) are considered as important constituents of CMIC's. The problem of noise is in urgent need of being investigated. The development of computer aided design (CAD) of the microwave components mentioned above is reported. The advancement of CMIC's is anticipated for opening up a new possibility of signal processing at microwaves

Software for optimization of instrumental neutron activation analysis of geological samples, preferentially silicate rocks, and a technique for evaluation and minimization of interference of gamma-ray lines are given. The maximum relevant signal-to-noise ratio was taken as a criterion for optimization by taking into account information available from a large number of lines in the gamma spectra studied.

Studies of peripheral limb nerves through stimulation electroneuromyography, evaluation of hormonal levels via radioimmune assay were performed in 59 patients having vibration disease caused by local vibration. Findings are obligatory signs of peripheral neuropathy and hypothyroid state without thyroid disease manifestations. Statistic analysis revealed reliable dependence between degree of motor axons functional deficit and level of serum triiodothyronine and thyroxin decrease--that could point to participation of thyroid hormones in peripheral neuropathy progression in vibration disease.

Analyzing values of transitory disablement morbidity for workers engaged into mining enterprises of East Siberia and Asiatic Far North, the authors revealed high prevalence of locomotory disorders among inside workers. The authors specified diagnostic criteria for occupational etiology of those disorders, presented arguments against considering cervical and lumbar pains as occupational diseases.

The authors analyzed possible causes of encephalopathy progression in late occupational intoxication among firemen. Those causes are disordered autoregulation of cerebral vessels, oxidant and psychoemotional stress, autoimmune disorders.

The article covers a specified concept model of vibration disease pathogenesis. The leading mechanisms underlying the disease are nervous and hormonal dysfunction presenting hypercortisolemia and low serum levels of thyroid hormones, associated tunnel compression of upper limb nerves and immune disorders resulting in autoimmune aggression. Informative diagnostic methods are suggested and diagnostic values are justified. The authors proved efficiency of therapeutic measures aimed to relieve compression and ischemic changes in peripheral nerves, to correct immune disorders.

Calorimetry proved disorders of peripheral thermoregulation in vibration disease patients. The authors suggested formulae to calculate specific rate of heat flow from hand surface. Calorimetry was proved appropriate for early diagnosis of vibration disease associated with acroangiospasm fits.

The genome of the model plant Arabidopsis thaliana has been sequenced by an international collaboration, The Arabidopsis Genome Initiative. Here we report the complete sequence of chromosome 5. This chromosome is 26 megabases long; it is the second largest Arabidopsis chromosome and represents 21% of the sequenced regions of the genome. The sequence of chromosomes 2 and 4 have been reported previously and that of chromosomes 1 and 3, together with an analysis of the complete genome sequence, are reported in this issue. Analysis of the sequence of chromosome 5 yields further insights into centromere structure and the sequence determinants of heterochromatin condensation. The 5,874 genes encoded on chromosome 5 reveal several new functions in plants, and the patterns of gene organization provide insights into the mechanisms and extent of genome evolution in plants.

The investigation of the microwave surface resistance of high-Tc single and polycrystalline samples having similar parameters in the presence of trapped flux has been performed. It is shown that the main part of the microwave losses in high-Tc ceramics is determined by flux trapped in the grain clusters.

Evaluation of miners in Northern and East Siberian regions revealed disorders of humoral immunity: increased B-lymphocytes count, higher production of autologic antibodies to peripheral nerves, greater serum concentration of circulating immune complexes and cryoglobulins. Cytostatic medications suppressed antibodies production and considerably increased efficiency of complex therapy of severe vibration disease.

The follow-up studies of patients with vibration disease caused by local vibration proved diagnostic value of minor skin response of dorsal hand surface and anterior surface of arm or forearm, if subjected to irritation with mixture of chloroform and ethanol. Depressed skin receptors during the disease are diagnosed through longer latent period of burning sensation in two of three points irritated on skin of the upper limb. The diagnostic method based on chemical stimulation of skin receptors is highly sensitive (86.9%) and specific (94.4%), especially for early stages of the disease, promoting detection of subclinical peripheral neuropathy caused by vibration. Due to its simplicity and availability the method could replace algesimetry in mass screening among workers exposed to vibration.

The goal of this paper is to develop the model notions which could be used as a basis for carrying out a CAD system for the MICs on HTSC films. The calculations is based on the numerical data describing the surface resistance of the film at the given frequency and temperature and the current distribution across the conductors of the transmission line. A phenomenological model of the HTSC is used. The current distributions are obtained from magnetostatic approximation which is suitable for the HTSC films up to the frequency about 300GHz. A minimum of the numerical parameters is necessary to describe the properties of the HTSC material. A software which makes it possible to calculate the parameters of transmission lines based on the HTSC films as a function of frequency and temperature is developed. The simulation can be carried out for microstrip or for coplanar lines.

A total of 276 Russian deep mine workers engaged into perforant boring were examined. HLA phenotype was determined according to the antigens of class 1 and 2. The antigen HLA-DR 5 turned out to associate with the high risk of severe vibration disease development complicated by degeneration and dystrophy of locomotor apparatus of hands. The antigens HLA-B 35, B 40, DR 2 were proved to have protective function and to be markers of higher resistance to the industrial vibration.

Premorbid condition represented by slightly expressed signs caused by vibration was studied in miners of northern mines and showed the absence of clear clinical manifestations in comparison with the vibration disease. Functional studies showed the disordered skin sensors, peripheral hemodynamics and muscles of the disordered skin sensors, peripheral hemodynamics and muscles of the upper limb: decreased distal blood flow rate in the upper limbs, lowered static endurance of the forearm muscles. Statistic and discriminative analysis helped to differ the groups of miners with preclinical and clinical manifestations of vibration disease by means of using the functional parameters.

The microwave technique needs the development of CAD for the microwave integrated circuits based on high-temperature superconducting films and intended to operate at the liquid nitrogen temperature. The model of bipolaron charge carrier transport was used to obtained the surface resistance as a function of temperature and frequency. The current distribution across the transmission line in quasi-static approximation has been used to calculate the resistance per unit length of the line. The set of model fitting parame ters provides a good agreement between calculation and experimental data.

Characteristics, frequency and distribution of vertebrogenic diseases involving cervico-brachial region were studied in more than 1,000 miners from asian North and East exposed to vibration. The data were compared with the results of examination of drivers. The investigation revealed a high level of vertebrogenic cervical pain and cervico-brachial pain in miners with a long length of service, especially in those suffering from vibration disease and frequent osteochondrosis manifestation in younger age, especially in subjects working beyond the Polar Circle. Occupational hazards are proved to play a leading role in the early development of vertebrogenic diseases, and vibration disease predisposes to such pathology. The results make possible to consider the vertebrogenic cervical pain and cervico-brachial pain as occupational diseases in young-aged workers with long length of service or evaluate such diseases as complications of vibration disease in individuals facing this occupational pathology.

An essential property of the superconducting film is S-N transition which can be induced by ac or dc current and exhibits in the large change of the film surface resistance. The S-N transition is used for performing microwave signal limiters or commutators with a high operational speed. The theory and practical realization of such devices have been developed. Some elements of CAD for HTSC microstrip lines has been elaborated on the base of the phenomenological model of the HTSC microwave surface resistance. The signal limiter and commutator are contributions to the HTSC microwave technique along with such elements as stripline, resonator, filter, patch antenna. The possibility of combining all these elements into cryogenic microwave integrated circuits is discussed.

We analyze microstrip line filters-switches CFS) and filters-limiters (FL) on the base of superconducting films. Serviceability of the devices is determined by the ratio of microwave surface resistances of the film being in normal N and superconducting S states. Experimental investigations confirm the possibility of realization of the devices under consideration based on both low- and high-Tc superconductors: NbN, YBaCuO.

A power limiter is designed with two resonant diaphragms included in an X-range rectangular waveguide. The cross strips made of high-Tc superconductive films placed in the centre of diaphragms can be in superconducting or normal states. The film state is controlled by the microwave power. The S-N transition in the strips causes a change of the transmitted wave attenuation from 0.5 to 25 dB.

Calibration procedure of aluminum wedge by optical density gradient of its X-ray image compared to density of standard bone wedge was described for X-ray photometric studies. Calibration of standard aluminum provided the opportunity to determine skeleton mineralization not only by wedge depth but also by units of mineral salt concentrations.

The authors have developed an acupuncture technique which ensures a good effect in moderate forms of vibration disease associated with muscular dystrophy and involvement of the structures of the bone and muscle apparatus. The technique is based on a combined impact on auricular acupuncture points (with needles and microneedles) and on the corporeal points (with needles, drug injections, and irritation of the underlying periosteal acupuncture point). The efficacy of the proposed method in patients with vibration disease is 1.8 times higher as against the conventional combined therapy.

Applications of superconductivity in microwave technique make possible to develop a) high quality resonators, filters delay lines with small losses and controlled dispersion, b) modulators, switches on the basis of S-N transition (the transition from superconducting to normal state of material under the influence of transport current, laser light etc., c) nonlinear elements (detectors, frequency convertors) on the basis of Josephson or S-I-S junctions. The paragraphs a) and b) will be discussed in this paper. The electric current in superconductor is formed by electrons being in two quantum states: superconducting and normal. As dc-current is connected with the movement only the superconducting electrons, the ac-current is a result of travelling of electrons in both quantum states. Therefore some dissipation of microwave electromagnetic field energy takes place in superconductors allways. The rate of this dissipation is strictly connected with the purity, structure and surface quality of the superconducting samples. The requirement on quality of superconducting materials is sufficiently strong espessialy in the case of microwave applications. This problem turns to be of crucial importance with respect to the new high-Tc superconductors.

The article contains results of clinical studies of dimethylsulfoxide (DMSO) therapeutic application at vibration disease (VD) cases caused by local vibration and in comparison with the generally accepted complex therapy. 30% DMSO water solution skin compresses were used applied to the affected zones of the upper extremities for 1-1.5 hours daily with 12-15 procedures in the whole course. It was established that DMSO effects are positive in most VB manifestations: regional angiodystonia, sensor and vegetative--sensor polyneuropathy, arthroses, and particularly in cases of muscle dystonia and myodistrophy, humeroscapular periarthrosis. This kind of technique simplifies VD therapy as it excludes physiotherapy procedures and limits medication to a great extent, doing with no drugs at all in some cases. Treatment costs and clinical course duration are also lowered.