Influence of the Degree of Crystallinity on the Dispersion of the Optical Parameters of Ge2Sb2Te5 Phase-Change Memory Thin Films

Semiconductors - Abstract—Extensive studies of Ge2Sb2Te5 material are associated with the possibility of producing multilevel nonvolatile elements for high-speed integrated optical functional...     

Effect of structural analogs of platelet activating factor on the intracellular signal transduction in murine peritoneal neutrophils and macrophages of P388D1 line

Direct and modulate effects of platelet activating factor (PAF), its structural analogues and ATP on primary and second processes at peritoneal neutrophils and P388D1 cells activation has been studied. The effect of compounds was evaluated on changes in Ca2+ transport and generation of reactive oxygen species. It was shown, that the synthetic analogues of MS series interact with PAF receptor, mobilize Ca2+ from thapsigargin-dependent intracellular stores and inhibit Ca2+ response on PAF in both types of cells. Unlike PAF the analogues do not induce the formations of reactive oxygen species in neutrophils and inhibit the PMA-induced respiratory burst. The activation of pyrinoreceptor of P388D1 cells by exogenous ATP does not inhibit PAF induced Ca2+ rise in cytoplasm, though partly releases Ca2+ from the same store.     

An immunochemical study of the antigens from Toxoplasma gondii tachyzoites obtained in different cultivation systems

Ureteral obstruction in a renal allograft, due to a variety of etiologies, is both a challenging diagnostic and therapeutic disorder. Since ureteral obstruction in a renal transplant recipient usually presents as azotemia, it must also be distinguished from acute rejection. Although ultrasound is non-invasive and readily available, the most definitive diagnostic tool is percutaneous nephrostomy tube placement with antegrade nephrostogram. A variety of therapeutic approaches are available to treat ureteral obstruction in a renal allograft. These procedures can be open (e.g., repeat ureteroneocystotomy) or utilize an endourological approach (e.g., transluminal ureteral dilatation). From an experimental standpoint, recent data in rodent models of experimental hydronephrosis demonstrate similar pathobiologic events in both the obstructed kidney and an allograft undergoing the chronic rejection process. To this end, investigation needs to be conducted to assess whether partial, unrecognized ureteral obstruction in an allograft hastens the development of chronic rejection. This would further underscore the importance of ureteral obstruction as a cause for not only acute azotemia in an allograft, but also chronic deterioration in renal transplant function.     

Technique for Analyzing Volumetric Defects Using Digital Elevation Model of a Surface

Russian Journal of Nondestructive Testing - A technique for detecting and analyzing volumetric surface defects has been developed. The technique is based on geomorphometric modeling, in particular,...     

Formation of a submicron GaAs MESFET gate using a four-layer dielectric dummy gate

In the present study, a technology for the formation of a submicron GaAs MESFET gate of 0.5–0.1 μm in length and above 0.5 μm in height using a four-layer dielectric dummy gate was developed. Techniques of chemical and plasma-chemical deposition from a gaseous phase, differing in etch rates in a buffer solution of hydrofluoric acid, were used to prepare silicon oxide films. Different constructions of a multilayer structure with varying sequences of layers and thicknesses were studied. The conditions of chemical and plasma-chemical etching of dielectrics allowing a dummy double-T-gate to be formed were determined. The employment of a sophisticatedly shaped dummy gate made it possible to obtain a gate electrode of a large cross section with a low length. The possibility in principle to fabricate a MESFET gate with a length of up to Lg = 0.1 μm using lithographic procedures with a minimal resolution of 1.0 μm was demonstrated.     

Dissipative losses of mechanical energy and heating of the probe in dynamic contact with the sample surface in a scanning microscope

Dissipative losses of mechanical energy and the rate of heating of the scanning microscope probe in dynamic contact with the sample surface have been theoretically estimated for a small temperature difference between the probe and the sample. Time variation of the temperature and the power of nanoprobe heating (cooling) caused by the near-zone fluctuational electromagnetic field have been calculated. Averaged over the period of nanoprobe oscillations, this thermal power significantly exceeds the power of mechanical losses even for small local variations of the sample surface temperature. For this reason, heating of the probe can stimulate its additional damping. This may account for the discrepancy between theoretical and experimental values of dissipative forces.     

Measuring van der Waals and electrostatic forces for an atomic force microscope probe contacting with metal surfaces

A contact force spectrometry technique was used to measure the van der Waals and electrostatic forces acting on platinum-coated silicon probes contacting with metal films on silicon substrates. It is shown that the results of such measurements can be used for determining the geometric characteristics of probes and the Hamaker constant of contacting materials. The experimental data well agree with the theoretical values.     

Contact atomic force microscopy of biological tissues

The forces of adhesion of the normal and tumor cells of the human stomach epithelium to the probe of an atomic force microscope have been measured for the first time. It is established that the adhesion and contact stiffness of malignant cells are significantly lower than those of the normal cells.