Hardening of Additive Manufactured 316L Stainless Steel by Using Bimodal Powder Containing Nanoscale Fraction

The particle size distribution significantly affects the material properties of the additively manufactured parts. In this work, the influence of bimodal powder containing nano- and micro-scale particles on microstructure and materials properties is studied. Moreover, to study the effect of the protective atmosphere, the test samples were additively manufactured from 316L stainless steel powder in argon and nitrogen. The samples fabricated from the bimodal powder demonstrate a finer subgrain structure, regardless of protective atmospheres and an increase in the Vickers microhardness, which is in accordance with the Hall-Petch relation. The porosity analysis revealed the deterioration in the quality of as-built parts due to the poor powder flowability. The surface roughness of fabricated samples was the same regardless of the powder feedstock materials used and protective atmospheres. The results suggest that the improvement of mechanical properties is achieved by adding a nano-dispersed fraction, which dramatically increases the total surface area, thereby contributing to the nitrogen absorption by the material.     

Reversal of granulocyte adherence to nylon fibers using local anesthetic agents: possible application to filtration leukapheresis

The effects of the cationic anesthetic agents tetracaine and lidocaine on granulocyte function, morphology, and adherence to nylon fibers were studied in an attempt to improve current methods of granulocyte collection by filtration leukapheresis (FL). When dissolved in acid- citrate-dextrose (ACD) plasma, these drugs significantly increased granulocyte elution from the fibers in a dose-related fashion. Granulocytes exposed to tetracaine and lidocaine remained more than 95% viable, retained normal bactericidal capacity after the drugs were washed from the cells, and had preserved membrane integrity, as evidenced by the normal ultrastructural appearance of tetracaine- exposed cells and an absence of leakage of lysozyme or lactic dehydrogenase. Granulocytes eluted with the anesthetic agents were rounded in shape with a reduction in the number of filopodial cytoplasmic projections and a relative absence of cytoplasmic vacuolization when compared to granulocytes eluted with ACD plasma alone. Dose-related inhibition of phagocytosis and adherence, which was largely reversible after washing the granulocytes, was noted. Greater than 95% of the lidocaine could be removed from the eluate with a single centrifugation and resuspension, indicating that granulocytes prepared by FL with anesthetic-enhanced elution could be potentially transfusable.     

Platelets inhibit the induction of nitric oxide synthesis by interleukin-1 beta in vascular smooth muscle cells

We have investigated the role of platelets in regulating the hemostatic and vasomotor properties of vascular smooth muscle. Experiments were performed to examine the effect of the releasate from activated platelets on the production of nitric oxide from interleukin-1 beta (IL- 1 beta)-treated cultured rat aortic smooth muscle cells. Treatment of vascular smooth muscle cells with IL-1 beta resulted in significant accumulation of nitrite in the culture media and in marked elevation of intracellular cyclic guanosine monophosphate (GMP) levels. The releasate from collagen-aggregated platelets blocked the IL-1 beta- mediated production of nitrite and the accumulation of cyclic GMP in smooth muscle cells in a platelet number-dependent manner. In functional assays, the perfusates from columns containing IL-1 beta- treated smooth muscle cells relaxed detector blood vessels without endothelium and the addition of IL-1 beta-treated smooth muscle cells to suspensions of platelets inhibited their thrombin-induced aggregation. The simultaneous treatment of smooth muscle cells with IL- 1 beta and the platelet releasate abolished both the vasorelaxing activities of the perfusates and the inhibition of platelet aggregation. Platelet releasates treated with a neutralizing antibody to platelet-derived growth factor (PDGF) failed to block IL-1 beta- induced nitric oxide production by the smooth muscle cells, as measured by both biochemical and functional assays. The platelet releasate from a patient with gray platelet syndrome likewise failed to block IL-1 beta-induced nitrite release by smooth muscle cells. These results demonstrate that platelets downregulate the production of nitric oxide by IL-1 beta-treated vascular smooth muscle cells through the release of PDGF. This effect may represent a novel mechanism by which platelets regulate vasomotor tone and thrombus formation at sites of vascular injury.     

Possibilities of surgical treatment of lesions of the organs of the reproductive system and disorders of sexual development

The authors describe the data on clinico-laboratory and instrumental examinations and surgical treatment of about 5,000 children with different reproductive organ injuries including complex patterns of abnormal sexual differentiation. The designed diagnostic programs made it possible to distribute patients into groups and according to the disease entities in conformity with the classification suggested. It is emphasized that in the developing science concerned with sex, it is necessary to distinguish an area pertaining to childhood, namely pediatric andrology, and to delineate its subject matter and tasks. Skilled assistance can be rendered by a specialized center. A broad spectrum of improved masculinizing (including the design of an artificial phallus) and feminizing (including the design of an artificial vagina from the rectosigmoid segment of the colon) is provided. The catamnestic data are evaluated.     

Modified technique of the Ivanissevich operation for varicocele in children]

On the basis of the results of rheotesticulographic studies in 38 children with left-sided II-III degree varicocele, the impairment in hemodynamics in the testicle at the involved side was established. No suppression of androgen function of the organ was revealed. The expediency to perform in patients of pediatric and young age the Ivanissevich operation, the effectiveness of which is increased in use of intraoperative phlebotesticulography was noted. The effective method for varicocele treatment in children has been suggested. The testicular vein is ligated near the deep inguinal ring as well as at the level of the upper third, then it is excised between the ligatures together with the deviating branches. The method was used in treatment of 120 patients with II-III degree varicocele. No disease recurrence is noted during 1.5 years.     

Detection of squamous cell differentiation in experimental tumors of urothelium by using epidermal G2 chalone

The presence of epidermal G2 chalone was investigated by different immunochemical methods in normal urothelium and in tumors of the urinary bladder induced in rats with N-butyl-N-butanol-(4)-nitrosamine. This chalone was not revealed in normal urothelium but found in 37 out of 56 tumors examined. In all these 37 tumors, squamous urothelial metaplasia was detected by electron or even light microscopy. The extent of morphological manifestations of squamous metaplasia showed a definite correlation with the concentration of chalone in tissue extracts. The method used may be applied as a subsidiary test for the determination of focal squamous metaplasia in biopsy material of human urothelial tumors which is of importance for prognosis of the disease.