Mechanical milling assisted by electrical discharge.

Mechanical milling is an effective technique for the preparation of fine metallic and ceramic powders and can also be used to drive a wide range of chemical reactions. Milling devices include planetary machines, attritors and vibrational mills; products include amorphous, nanocrystalline and quasicrystalline materials, supersaturated solid solutions, reduced minerals, high-surface-area catalysts and reactive chemicals. During milling, solid-solid, solid-liquid and solid-gas reactions are initiated through repeated deformation and fracture of powder particles. A separate materials synthesis and processing technique involves reacting a material in a gas atmosphere under an electrical discharge. Here we show that the application of low-current, high-voltage electrical impulses during milling can result in both faster reactions and new synthesis and processing routes. We demonstrate the effects of glow (cold) and spark (hot) discharge milling on particle fracture for brittle, low-conductivity materials and ductile metals. Glow discharge milling was found to promote solid-gas reactions whereas spark discharge milling promotes fast fracturing, recrystallization, mineral reduction and solid-solid reactions.

[Evaluation of prophylaxis and actual prevalence of HBV infection in twelve hemodialysis centers of Northern Poland]. / Ocena profilaktyki i aktualnej sytuacji epidemiologicznej zakazenia HBV w dwunastu osrodkach hemodializy Polski pólnocnej.

The aim of the study was to estimate the HBV infection preventive measures used in the twelve dialysis centres in north Poland. In all of the centres hepatitis B vaccination and segregation of HBV infected patients (dedicated machines or separate rooms), which are the two basic HBV infection control methods, were introduced. Our results point out that in some of the centres certain modification of these methods would be possible, including universal predialysis vaccination programme, changes in hepatitis B vaccination schedules with most effective routes of vaccination only and dedication for HBV infected patients not only separate rooms but separate dialysis staff as well.

[Microcomputer information systems designed to provide documentation about patients treated with dialysis]. / Mikrokomputerowy system informatyczny przeznaczony do prowadzenia dokumentacji chorych leczonych dializami.

A program specifically designed for PC/XT/AT compatible with IBM was written. This program is intended for collecting data on the patients treated with repeated dialyses. The system collects, edits, and surveys data according certain rules. It may print required data. It may also be extended by inclusion of the additional modules and adopted to other centres of dialysis. It is used for 2 years already and proved quite useful in the center of dialysis.

[Effect of hemodialysis on left-ventricular contractility]. / Wplyw hemodializy na czynnosc skurczowa lewej komory.

43 patients with end-stage renal failure maintained on hemodialysis were studied by echocardiography before and after hemodialysis. Considering possibility, that left ventricule can be enlarged due to intrinsic factors impairing their performance, like myocardial fibres damage in coronary disease or inflammation and extrinsic factors like hypertension, overhydration, anemia, arteriovenous shunt and humoral changes (electrolyte imbalance, uremic toxins, acidosis) three groups of patients were chosen: A--with normal left ventricular diameter, B--with enlarged left ventricule before and after dialysis, C--with enlarged left ventricule only before dialysis. Mean velocity of circumferential fibre shortening (mVcf) and ejection fraction (EF) as left ventricular contractility indexes and end-systolic meridional wall stress as afterload index were determined. Stress-shortening relations before and after hemodialysis were compared in groups, to determine possible intrinsic contractility impairment of the left ventricule. No differences in groups were found in preload reduction (weight loss) and humoral changes (BUN, creatinine, pH, potassium, calcium, hematocrit), also blood pressure was not significantly different in all groups. Hemodialysis improved contractility only in patients with normal left ventricular diameter and significant reduction of afterload. In group A and C stress-shortening relation increased after dialysis. In group B decreased probably because of the lack of mVcf improvement despite reduction of stress in two patients. It is possible that these two patients had impaired contractility and enlarged left ventricle due to intrinsic factors.