Thermal stresses in WC-Co hard alloy after sintering

The stressed-strained state of individual elements of th emicrostructure of tungsten hard alloys as a result cooling the material to room temperature after sintering has been estimated by the method of numerical modelling. It is shown that both tensile and compressive stresses may form in individual tungsten carbide grains and certain interlayers of the cobalt phase. The stressed state of the carbide phase is analyzed which makes it possible to predict the possibility of failure for individual grains and also sliding along intergranular boundaries during alloy cooling after sintering. It has been established that the binder phase deforms plastically during the whole cooling process thus creating at room temperature a very inhomogeneous distribution for the intensity of plastic deformation through interlayers.Translated from Problemy Prochnosti, No. 12, pp. 87–93, December, 1990.     

Complete clinical remission and subsequent relapse of bronchiectasis-related (AA) amyloid induced nephrotic syndrome

Systemic amyloidosis normally has a dismal prognosis. However, there are several case reports of protracted survival, usually as a response to measures designed to retard the further deposition of amyloid fibrils. In AA amyloid, most commonly associated with inflammatory rheumatological, bowel, and chest diseases, such interventions have had some success, but the dramatic response of complete resolution of nephrotic syndrome as a result of the regular institution of postural chest drainage and antibiotic therapy, in the clinical context of bronchiectasis, has been previously reported only once. In both of our cases, after protracted remission, such therapy was abandoned by the patients, leading both to recurrence of nephrotic syndrome and also eventually to end-stage renal failure requiring dialysis.     

(Pheo)melanin photosensitizes UVA-induced DNA damage in cultured human melanocytes

The question of whether melanins are photoprotecting and/or photosensitizing in human skin cells continues to be debated. To evaluate the role of melanin upon UVA irradiation, DNA single-strand breaks (ssb) were measured in human melanocytes differing only in the amount of pigment produced by culturing at two different concentrations, basic (0.01 mM) or high (0.2 mM), of L-tyrosine, the main precursor of melanin. In parallel, pheo- and total melanin contents of the cells were determined. Identical experiments were performed with two melanocyte cultures derived from a skin type I and a skin type VI individual. For the first time the correlation between UVA-induced genotoxicity and pheo-/total melanin content has been investigated. We observed that cultured in basic medium, the skin type VI melanocytes contained 10 times more total melanin and about seven times more pheomelanin than the skin type I melanocytes. Elevation of tyrosine level in the culture medium resulted in an increase of both pheo- and total melanin levels in both melanocyte cultures; however, the melanin composition of skin type I melanocytes became more pheomelanogenic, whereas that of skin type VI melanocytes remained the same. The skin type VI melanocytes cultured in basic medium demonstrated a very high sensitivity (1.18 ssb per 10(10) Da per kJ per m2) toward UVA that is probably related to their high pheo- and total melanin content. Their UVA sensitivity, however, did not change after increasing their melanin content by culturing at high tyrosine concentration. In contrast, the skin type I melanocytes demonstrated a low sensitivity (0.04 ssb per 10(10) Da per kJ per m2) toward UVA when cultured in basic medium, but increasing their melanin content resulted in a 3-fold increase in their UVA sensitivity (0.13 ssb per 10(10) Da per kJ per m2). These results demonstrate that UVA-irradiated cultured human melanocytes are photosensitized by their own synthesized chromophores, most likely pheomelanin and/or melanin intermediates.     

A mechanism of charge-carrier photogeneration in polyamidine supramolecular structures

The photophysical properties and mechanism of charge-carrier photogeneration in supramolecular polyamidine structures (which form, as was shown previously, a promising class of materials for photosensitive and electroluminescent devices) are studied. Based on the analysis of the spectral, field, temperature, and concentration behavior of changes in the photosensitive and luminescence properties, it is shown that the carrier photogeneration in the systems under investigation is described by the Pool-Frenkel model, which takes into account strong interactions and collective effects in the supramolecular system arising due to the formation of a regular network of hydrogen bonds between functional groups of a polymer.     

Structure and functional properties of thermally and thermomechanically treated Ti-Ni-Nb based alloys with a wide martensitic hysteresis: II. Ti-Ni-Nb alloys with zirconium

The effect of zirconium on the structure, characteristics of thermoelastic martensitic transformation, and functional properties of Ti-Ni-Nb shape-memory alloys has been studied. The possibility of using this material for the manufacture of thermomechanical couplings intended for the design of extra reliable thermomechanical joints operating under extreme temperature conditions is considered.     

Should the presence of coiled blood flow in the left heart ventricle and aorta be taken into consideration when constructing artificial heart valves?]

This study presented the outcome of 92 EOC patients treated by platinum or platinum analogue with cyclophosphamide from January 1, 1993 to December 31, 1995. There were 77 evaluable patients. The follow-up ranged from 4-42 months (median 14 months). The over all 3-year survival was 64 per cent and the median progression-free interval was 16 months for the whole group. There was no significant difference in survival between patients who received cisplatin and those who received carboplatin (P = 0.093). Patients who underwent optimal debulking surgery had significantly longer progression-free interval (P = 0.001) than those who had sub-optimal surgery. Fifty four per cent of patients with clear cell carcinoma died of the disease. Patients who received cisplatin had a drop out rate while on therapy more often (24% vs 5.3%) than that of carboplatin. Toxicities from chemotherapy were moderate but manageable.     

Autonomic assessment of cardiovascular disease

Port wine stains (PWS) can lead to considerable emotional distress. The present study evaluated a) the coping with illness, the quality of life and the body image of patients with PWS and b) the effects of dye laser treatment on psychosocial parameters. Seventy PWS patients undergoing treatment with the flashlamp-pumped pulsed dye laser (FPDL) were assessed with questionnaires regarding coping with skin disease, quality of life and body image. Major clinical criterium was the lightening of PWS under treatment. PWS patients showed significant social phobia and avoidance similar to patient suffering from chronic skin diseases. The anxiety correlated with size and darkness of the PWS. In terms of helplessness and depressive mood, PWS patients were less affected than the comparison group. Also, PWS patients had reductions in quality of life and in body image. The coping strategies had a differential effect on the body image. Since there is a correlation between lightening of the PWS and reduction of emotional distress, FDPL therapy can be considered an effective treatment of PWS also in psychosocial terms.     

The ultrastructural organization of the epitheliocytes in the rat small intestine with the long-term use of the artificial carbon-mineral sorbent SUMS-1

Long-term oral treatment with antisorbent SUMS-1 promoted the increase of absorptive surface of intestinal villi due to growth in number and height of epitheliocyte microvilli. Mitochondrial volume density, superficial density of external mitochondrial membrane and epithelial basement membrane volume density tended to grow, while volume density of interdigitations of outer membrane lateral portions and enterocyte intercellular spaces tended to reduce. These changes probably indicate the increase of cell adaptive potential.