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The effects of positive and negative temperature and static load on the main informative parameters (structure coefficient, partial energy, location) of acoustic emission (AE) signals, which determined the mechanism for changing the structure of carbon fiber and the beginning of its destruction, are investigated. Tests of specimens of carbon fiber T800, made of nine monolayers with laying [±45/90/О3/90/±45], size 600x100x0.9 mm. Each sample was subjected to static loading and the effects of positive (+20, +40, +60, +80, +100 °С) or negative (–20, –40, –60, –80 °C) temperatures in the area of the concentrator in the form of a 12 mm diameter hole. Using fractography, changes in the structure of carbon plastic from the applied static load and temperature and changes informative parameters were analyzed. It was shown that the lamination of the material with simultaneous exposure to static load and temperatures from –80 to –20 °C and from +60 to +100 °C corresponded to an increase in the structural coefficient and partial energy, which caused an energy shift in the frequency range 125…250 kHz. Under the same static loads, but temperatures of +20 and +40 °C, informative parameters took on minimal values, that meant the energy was shifted to the frequency range 250…500 kHz, characterized the crumbling of the matrix and breaking of the fibers without lamination of the CFRP. Under all temperature conditions, the location of the signals began in the hole area and spread in the direction of the static load. The detection the disturbance of the CFRP structure by the informative parameters of AE signals makes it possible to reduce the risk of emergency situations during working of the composite construction.

Relationship between the main informative parameters of acoustic-emission (AE) signals recorded during static loading of a CFRP sample and the process of material fracture has been investigated. Clusterization of AE signals by digitized shape has made it possible to locate a zone they originate from. Material was then cut out from this zone to prepare thin sections that were subjected to fractography. Fractography revealed fiber fracture, brittle cracking of the matrix, its exfoliation from the carbon fibers, etc.

In this work the study of the friction stir welding process of 2 mm thick aluminum alloy AA2024 sheets cut along and across the rolling direction was carried out. The obtained results show that the rolling direction of AA2024 sheet workpieces has a significant effect on the selection of optimal welding modes. It is revealed that at welding across the rolling direction it is possible to achieve the highest values of the ultimate tensile strength in a rather wide range of modes.

The work compares the strength characteristics and microstructure of 2-mm-thick welded joints from Al-Mg alloy AA5056, produced by friction stir welding along and across the workpiece rolling direction. The tests show that the variation of parameters results in the formation of a complex structure, which is determined by the contribution of both mechanical and thermal components. Depending on the rolling direction, the welded joint has different mechanical properties under identical conditions. In the case of the rolling direction coinciding with the friction stir welding direction, the strongest welded joint has the ultimate tensile strength of 328 MPa, which is equal to 98% of the base metal strength. In case of welding in the transverse direction, the ultimate tensile strength of the joint exceeds those of the base metal by 8 MPa and is equal to 333 MPa. According to the conducted experiments it was proved that the structure and strength of friction stir welded joints depends on the workpiece rolling direction, which implies different welding parameters for these cases.

Residual stresses in rolled tungsten after pulsed irradiation with a plasma and an electron beam at the GOL-3 facility were measured. The mechanical stresses were derived from the strain, which was measured by the change in the interplanar distance in different directions. The interplanar distance was gaged from the shift of the peak of diffraction scattering of X-rays. The measured tension turned out to be a tensile stress along the surface. The tension along the direction of rolling and grinding was approximately three times larger than that in the perpendicular direction. The work was carried out at the VEPP-3/VEPP-4 complex.

In this paper, we investigate the microstructure and microhardness of high-nitrogen austenitic steel after high-pressure upset and high-pressure torsion (6 GPa) at room temperature. As the result of deformation, steel microhardness increases by 1.5 times after high-pressure torsion per one revolution while the distribution of microhardness is quasi-homogeneous across the disks. The level of solid solution hardening of steel remains high after deformation processing, and the main mechanisms determining fragmentation of the steel structure are slip, twinning, formation of localized deformation microbands, and precipitation hardening.

In most cases, medical implants are made from titanium alloys or stainless steel with good mechanical properties. However, these materials contain toxic ele� ments such as nickel, aluminum, and vanadium. For medical applications, it would be preferable to use titanium (1, 2), zirconium, niobium and their alloys, with distinctive physicomechanical and biological properties. The widespread use of titanium in implants is mainly hindered by its poor mechanical properties, including its durability under periodic and cyclic loads. This problem may be resolved by using nano� structural (ultrafinegrain) titanium. At present, we are able to produce large blanks of nanostructural tita� nium with good mechanical properties (3). The meth� ods employed are based on intense plastic deformation (3-7): equalchannel angular pressing (3, 4), abc pressing (5-7), and so on. By intense plastic deforma� tion, a nanostructural state may be established over the whole volume of the blank. That ensures mechanical properties matching those of moderately complex tita� nium alloys such as VT6 alloy. The creation of nanostructure permits fundamen� tal change in the mechanical properties of metals: the yield point and strength, the fatigue life, the wear resis� tance, the cyclic durability, etc. Note that at least two successive methods of intense plastic deformation must be used to obtain a nanostructural state of tita� nium (6, 7). Those methods may be combined in a sin� gle cycle (3). Twostage intense plastic deformation was pro� posed in (6, 7): abc pressing in a mold; and multipass rolling. In that approach, the initial upsetting in the mold involves successively changing the compression axis three or four times (analogously to multistage abc pressing (5)). In the first stage, the blank is deformed in a hydraulic press at 10 -3 -10 -1 s -1 . At specified tem� perature, each cycle includes onetime 40-50% upsetting, with subsequent change of the deformation axis by 90° rotation of the blank around the longitudi� nal axis. The temperature of the blank is reduced in stages in the range 700-400°C on passing to the next cycle. In the second stage, the blank is deformed by rolling at room temperature; the rollers may be grooved or smooth. The accumulated strain in rolling is 90%. Rolling produces blanks in the form of rods or plates. The final blanks are annealed in argon at 250 or 300 °C to remove the internal stress and increase the plasticity. As a result of twostage treatment and lowtemper� ature annealing, uniform grain-subgrain nanostruc� ture is formed in the blank (Fig. 1). The mean size of the elements (grains, subgrains, fragments) is less than 100 nm. This nanostructural state ensures plasticity of 6-10%, yield point of 1100 MPa, and strength of 1160 MPa.

The research is involved in producing a Ti-Nb alloy surface layer on titanium substrate by high energy beam method, as well as in examining their structures and mechanical properties. Applying electron-beam cladding it was possible to produce a Ti-Nb alloy surface layer of several millimeters, where the niobium concentration was up to 40% at. and the structure itself could be related to martensite quenching structure. At the same time, a significant microhardness increase of 3200-3400 MPa was observed, which, in its turn, is connected with the formation of martensite structure. Cladding material of Ti-Nb composition could be the source in producing alloys of homogeneous microhardness and desired concentration of alloying niobium element.

The paper describes the basic methods for the diagnosis and treatment of ocular tuberculosis, which are based on the studied mechanisms of its pathogenesis. It updates the pathomorphism of the disease, the results of experimental studies dealing with new diagnostic techniques, including an objective estimation of a focal response to tuberculin. The results of studies of ocular tuberculosis in children, as well as the efficacy of the new Russian immunotropic drugs glutoxim and betaleukin are outlined.

There have been great changes in the clinical picture and course of ocular tuberculosis in the 90s versus the 70-80s. There has been a upward trend in the incidence of ocular tuberculosis in the population, in children and teenagers in particular. Patients with tuberculous uveitis involving the posterior eye makes up over 70%. A specific eye tissue inflammatory process is mainly exudative and infiltrative with rapid development of the complications masking a tuberculous focus, which hampers treatment and causes a significant decrease in visual functions.

The study has indicated that in the 1990th, there has been considerable changes in the clinical picture and course of ocular tuberculous lesions. Their morbidity has tended to increase in children, adolescents, and young individuals. Patients with tuberculous uveitis with posterior eyeball lesions are more than 70%. The specific inflammatory process is primarily exudative and infiltrative, followed by rapid development of complications that prevail over the major focus, prevent treatment and substantially deteriorate visual functions. The findings are important not only for understanding the pathogenetic development of an ocular tuberculous process and they provide evidence for the approach to be used in the treatment of various manifestations of ocular tuberculosis.

Pilot experience in the examination and treatment of children with tuberculosis admitted to OT department at St. Petersburg Research Institute of Phthisiopulmonology is evaluated and current features of tuberculous uveitis are characterized. The authors provide recommendations on the research in OT field and check-up of OT patients, on design of new schemes of treatment adjusted for the disease activity, stage and severity.

The etiology of peripapillary choriopathy (so-called geographic serpiginous choroiditis) is still unknown. This condition should be differentiated from tuberculous chorioretinitis because both abnormalities are characterized by a prolonged chronic course with involvement of the choroid and retina in young and middle-aged patients. The present study analyzes the results of a follow-up of 32 patients with peripapillary choriopathy; before these patients were admitted to hospital, ocular tuberculosis was diagnosed in 19 and suspected in 13 of them by local specialists. The authors came to a conclusion that the major differential diagnostic criteria here should be specific features of the ophthalmoscopic picture and of fluorescent angiograms of the fundus oculi, as well as the results of tuberculin diagnosis and tentative therapy.

The author sets forth equations for the hydraulic resistance of adsorbers with annular and plane layers of active carbon, with spherical layer arrangement, and with annular and hemispherical layers. Diagrams illustrate the construction of the adsorbers, and a chart represents the resistance as calculated for each of the three types of geometric shapes. The author concludes that calculated results are in satisfactory agreement with experimental values.

The evolution of the perlite structure in the course of plastic deformation of U8 and St70 steels has been studied. With increasing degree of cold working, the dislocation density increases near the interphase boundary in the ferrite interstices of perlite, which forms a dislocational “fringe”, which in turn forms a pseudocellular structure. Under thermal deformation conditions, a subgrain structure arises in the ferrite interstices of lamellar perlite. The most dangerous localized flow channels in which plasticity is exhausted for the first time and cracks appear, are the deformation bands. The narrower the deformation bands and the larger the value of the relative displacement of the subcolumn blocks adjacent to them, the more dangerous they are with regard to failure. The features revealed in the development of deformation and failure provides a basis for controlling steel treatment regimes in order to produce perlite with the optimum structural parameters.