Radiation-Stimulated Formation of Two-Dimensional Structures Based on Calcium Silicide.

The formation of CaSi polycrystalline structures under the postgrowth electron irradiation of epitaxial CaF/Si(111) films with embedded thin Si layers was studied. The dependence on the electron exposure time was investigated for two types of structures with different film thicknesses. The optimal conditions for the formation of two-dimensional CaSi structures were found.

Permeation of Nanoparticles into Pulmonary Surfactant Monolayer: In Situ X-ray Standing Wave Studies.

High-resolution X-ray techniques were applied to examine the effects of gold nanoparticles (size <5 nm) on natural pulmonary surfactant and pure DPPC monolayers preliminarily formed on water subphase in a Langmuir trough. Hydrophobic and hydrophilic nanoparticles were delivered from nanoaerosol using electrodeposition method. Grazing incidence diffraction, X-ray reflectivity, and X-ray standing wave measurements allow to monitor the changes in molecular organization of lipid monolayer and to locate the position of gold nanoparticles.

Tunneling magnetoresistance in ensembles of ferromagnetic granules with exchange interaction and random easy axes of magnetic anisotropy.

We study the tunneling magnetoresistance in the ensembles of ferromagnetic granules with random easy axes of magnetic anisotropy taking into account the exchange interaction between granules. It is shown that due to the exchange interaction magnetoresistance is effectively decoupled from magnetization, i.e.

Factor VIII and IX assays for post-infusion monitoring in hemophilia patients: Guidelines from the French BIMHO group (GFHT).

Replacement therapy with plasma-derived or recombinant FVIII and FIX (pdFVIII/pdFIX or rFVIII/rFIX) concentrates is the standard of treatment in patients with haemophilia A and B, respectively. Measurement of factor VIII (FVIII:C) or factor IX (FIX:C) levels can be done by one-stage clotting assay (OSA) or chromogenic substrate assay (CSA). The French study group on the Biology of Hemorrhagic Diseases (a collaborative group of the GFHT and MHEMO network) presents a literature review and proposals for the monitoring of FVIII:C and FIX:C levels in treated haemophilia A and B patients, respectively.

The Enhancement of Metal-Binding Properties in Hemoglobin: The Role of Mild Damaging Factors.

X-ray studies revealed the considerable enhancement of metal-binding properties in human hemoglobin under exposure to mild damaging factors (in the presence of 0.09 M urea or upon heating for 30 min at 50 °C). Changes in the element composition of the hemoglobin monolayer, formed on the water subphase in the Langmuir trough, have been monitored in real time by the total external reflection X-ray fluorescence measurements.

Distinct effect of xenobiotics on the metal-binding properties of protein molecules.

The X-ray standing-wave method was applied to study the elemental composition and molecular organization of ordered protein films of alkaline phosphatase exposed to different xenobiotics (drug compounds, lead). Binding of metal ions from triply distilled water to protein molecules has been experimentally observed. Definite differences in the arrangement of impurity metal ions in the films have been established.

Universal behavior of magnetoresistance in quantum dot arrays with different degrees of disorder.

The magnetoresistance in a two-dimensional array of Ge/Si quantum dots was studied in a wide range of zero magnetic field conductances, where the transport regime changes from a hopping to a diffusive one. The behavior of the magnetoresistance is found to be similar for all samples--it is negative in weak fields and becomes positive with increasing magnetic field. The result apparently contradicts existing theories.

X-ray fluorescence methods for investigations of lipid/protein membrane models.

The protective effect of the bisphosphonate drug xydiphone (K,Na-ethidronate) on membrane-bound enzyme damaged by lead ions has been studied. A protein/lipid film of Ca-ATPase/phosphatedylethanolamine deposited on a silicon substrate was used as a model system. The position of lead ions within the molecular film before and after the xydiphone treatment was determined using the total-reflection X-ray fluorescence method.

[The mitostatic activity of benzylpenicillin and aspisol in an experiment].

The changes occurring in the proliferation and differentiation of pluripotent hematopoietic stem cells under the action of different doses of benzylpenicillin and aspisole were investigated by using models of sublethally and lethally irradiated mice. The mitogenic and mitostatic dose-dependent effects of the drugs were revealed at the very early stages of immunogenesis and hemopoiesis. These effects show themselves in different ways (depending on the predominance of T- and B-lymphocytic conditions for T-B-cooperation and so on.

[Absence of a correlation between anti-oxidative and anti-ischemic effect of alpha-tocopherol in heat ischemia of the kidney].

Experiments were conducted on 110 inbred albino rats to compare the ability of alpha-tocopherol (alpha-TP), injected in a dose of 200 or 50 mg/kg 3, 6 or 24 hours before the experiment, to inhibit lipid peroxidation (LPO) in the cortex of a kidney after 90-minute ischemia with the influence of the drug on the function of the organ in the early postischemic period. Ischemia and alpha-TP had a mild effect on the basal malonic dialdehyde content in the kidney. Study of ascorbate-induced LPO showed it to be significantly activated in ischemia and after reperfusion, alpha-TP was also found to produce a marked inhibiting effect which grew with the gradual increase of the period between the injection of the agent and the development of ischemia.

[The reasons for the inefficiency of local kidney hypothermia during the temporary discontinuation of their blood supply].

Functional changes in the kidney exposed to 1-hour ischemia with surface cooling to +5+7 degrees C (series I) or +16+18 degrees C (series II) were studied in experiments on 50 rabbits and 20 non-inbred rats. In series II animals significant changes in renal function were not registered. In series I cooling there was a marked decrease of creatinine clearance, clearance of osmotic substances and Na-reabsorption during 1-3 days after ischemia.