Materials for Protection of the Respiratory Organs Fabricated from Polymer Melts by Blowing

Filter materials fabricated by spraying a polymer melt are comparable to the Petryanov filters widely used in systems for protecting the respiratory organs with respect to the passage coefficient and air resistance and they can be successfully used in respirators. The electret charge significantly increases the capacity of the filter material to trap submicron particles of a pollutant at the low filtration rates characteristic of individual devices for protection of the respiratory organs. The results of the study will be useful to developers of filters and other specialists involved with problems of removing different kinds of suspended matter, including toxic aerosols, from air. Institute of Mechanics of Metal-Containing Polymer Systems, National Academy of Sciences of Belarus', Gomel'. Translated fromKhimicheskie Volokna, No. 6, pp. 42–45, November–December, 2000.     

A methodology for tribological correction of osteoarthritic joints

The paper discusses a methodology for correcting the tribological state of synovial osteoarthritic joints by means of blood dialysis. The concept of medicinal and immunological modification of lubricating fluids based on blood serum is substantiated. The concept is based on the fundamental capacity of living tissues, as frictional materials, to regenerate defects on the friction surfaces of cartilage during metabolism.     

Quality of ferroelectric capacitors used in tunable microwave filters

The problem of determining the quality of ferroelectric capacitors from measured characteristics of tunable microwave bandpass filters has been solved. The quality of ferroelectric capacitors based on barium-strontium-titanate (BST) thin films, used in four filters tunable over a frequency range of 1.8 to 4.3 GHz, have been determined.     

Effect of the plasticizer on structure formation in porified polydispersed glass ceramic composites

A composite material based on synthetic phosphates strengthened with 50 wt.% glass phase has been obtained. The porosity of the material is 48–61%, depending on the plasticizer agent and sintering regime. The experimental samples showed adequate mechanical strength and biochemical solubility, which commends this material for use as a biomaterial. __________ Translated from Steklo i Keramika, No. 4, pp. 27–30, April, 2007.     

The ribology of joints and problems of modern orthopedics

The paper presents a review of current trends in biotribiology. The authors discuss the extent of the achievements in this field at the turn of the 21st century. This period is distinguished by the discovery of liquid-crystalline and quasi-electret states revealed by AFM in the articular lubricating fluid; new boundary lubrication mechanisms, which are realized by organic super-lubricants at the nanolevel; and methods for in vitro study of friction in joints using electromagnetic fields able to simulate the natural articular biofield. A relationship is traced between biotribology and the chief directions in contemporary orthopedics, namely: 1) articular chondroprotection exercised via local therapeutic methods based on tribomonitoring of pharmaceutic substances; 2) injection of drugs based on blood serum; 3) development of a new generation of articular endoprostheses able to simulate the biophysical properties of synovial joints. It is shown that progress in modern biotribology has provided scientific substantiatiation of orthopedic treatment procedures. The ideas advanced by I.V. Kragelskii in resolving various engineering problems have proven fruitful in biotribology, which deals with living tissues and biological fluids.     

Sampling phased array technology for the detection of voids in carbon fiber-reinforced plastics

In the lightweight material industries, the current focus is on fiber-reinforced plastics, in particular on carbon fiber-reinforced plastics (CFRPs), since they offer higher relative specific tensile strength and stiffness as well as reduced weight compared to conventional metallic materials. Currently, the quality assurance of manufactured CFRP components represents a major challenge for CFRP manufacturers. Voids are generated during the infusion process of CFRPs, which in turn reduce the mechanical performance of CFRPs. This article presents the possibility to detect the distribution of voids across the surface of CFRPs by using a non-destructive testing method, the so-called sampling phased array ultrasound technology. Two types of CFRPs with six carbon layers in the same direction are fabricated by means of a vacuum-assisted resin infusion process. Voids in CFRPs are generated using a foaming agent during the impregnation process. The C-scan images produced through the sampling phased array technology are subsequently analyzed by the optical image analysis software in order to determine the amount of voids for each type of manufactured CFRP.     

Dynamics of the Disturbances of a Weakly Ionized Plasma under Conditions of the Chambers of Thermal Energy Converters

Relations between the characteristics of disturbing acoustic effects and the parameters of state of a medium which correspond to the conditions of the development of charge instabilities in the low-temperature plasma of combustion products in chambers of thermal energy converters are determined in dimensionless form. These relations are confirmed by the results of a numerical experiment.     

Quasi-TEM modes in parallel-line transmission structures withconductors embedded in dielectrics

A transmission structure of many parallel conductors is capable of propagating many distinct quasi-TEM modes. A field theory of such modes was developed for a theoretically infinite number of very thin conductors placed on a dielectric substrate. The current paper extends this work to include a large number of thin parallel conductors embedded within finite dielectric slabs. The theory is illustrated by the following three structures: a large number of parallel wires embedded in dielectric slabs with substrates of infinite width, both with and without a ground plane; and a large number of thin wires embedded in a finite dielectric slab without a ground plane. This extension to a finite dielectric structure is obtained using a superposition method where both vertical and horizontal surfaces are considered infinite in turn. A major application of the derived formulation is the investigation of velocity distributions and crosstalk within these structures. Comparison of these structures with ones where the conductors are on the substrate (as opposed to embedded) indicates how the placement and structure of the conducting channel affects the modal velocities and crosstalk