Fine Ti Powders Through Metallothermic Reduction in TiO<Subscript>2</Subscript>–Mg–Ca Mixtures

Fine Ti powders were prepared through magnesiothermic reduction in TiO₂–Mg–Ca mixtures under 4 MPa of Ar followed by acid leaching (with HCl or HNO₃) and characterized by XRD, SEM/EDS, and chemical analysis. Thus prepared Ti powders exhibited the specific surface ranging between 7.0 and 30.0 m²/g. The produced Ti powders can find their application in pyrotechnics, powder metallurgy, and as raw material for SHS of inorganic compounds.     

Development of technology and equipment for ultrasonic shock treatment of welded joints

New equipment and technology for ultrasonic shock treatment (UST) of components in engineering are described. The design of new equipment and its technical characteristics are outlined. Technology and the results of stress relief after welding, surfacing, pressure working and other operations are presented.     

Formation of regular structures on the surface of metals under the effect of a high-power ion beam of nanosecond duration

The formation of regular structures, microparticles on the surface of polycrystalline metals (magnesium, zinc, and aluminum) under the multiple effect of a nanosecond high-power ion beam with a current density from 50 to 150 A/cm², is investigated. The spatial parameters of the relief, which are in the limits of 8–40 μm for studied metals, are investigated. The size of particles appearing during the formation of this relief is from 0.1 to 1.5 μm. The appearance of regular structures is attributed to the excitation of capillary waves on the melt surface.     

Two-dimensional semimetal in wide HgTe quantum wells: Charge-carrier energy spectrum and magnetotransport

The magnetoresistivity and the Hall and Shubnikov-de Haas effects in heterostructures with a single 20.2-nm-wide quantum well made from the gapless semiconductor HgTe are studied experimentally. The measurements are performed on gated samples over a wide range of electron and hole densities. The data obtained are used to reconstruct the energy spectrum of electrons and holes in the vicinity of the extrema of the quantum-confinement subbands. It is shown that the charge-carrier dispersion relation in the investigated systems differs from that calculated within the framework of the conventional kp model.     

Application of shock waves for the improvement of current-carrying properties of YBCO(123) and Bi(2223) HTSC tapes in magnetic fields

Shock waves with a leading-edge pressure of ～10¹¹ Pa, which were produced in a plasma focus setup, were used to increase the critical current density in YBCO(123) and Bi(2223) HTSC tapes. It was shown that the effect of chemically inactive high-temperature high-density plasma on the HTSC tapes leads to an irreversible increase in the critical current in high magnetic fields. The improvement of the current-carrying properties of the YBCO(123) HTSC tape is confirmed also by the results of scanning Hall magnetometry at 77 K. In particular, in a field of 8 T applied perpendicular to the c axis (H ⊥ c), the increase in the critical current after shock-wave treatment is ～60%. In the case of the Bi(2223) tape, the critical current in a zero field in the sample portion subjected to shock-wave action was found to be twice as high as that in the untreated portion (100 and 50 A, respectively). The increase in the critical current can be related to a number of possible structural transformations of the superconducting core. First of all, an increase in the density of current-carrying core, which leads to an increase in weak bonds at grain boundaries, is possible. In this case, the formation of nanosized defects, which are responsible for an increase in the force of pinning of Abrikosov vortices, is also possible.     

Importance of pre-treatment radiation absorbed dose estimation for radioimmunotherapy of non-Hodgkin''s lymphoma

We have been developing a new type of centrifugal pump for long-term use. The magnetically suspended centrifugal pump (MSCP) contains no shaft and seal so that long life expectancy is predicted. Paracorporeal left ventricular (LV) assist circulation between the left atrium and the descending aorta was instituted using sheep. The flow rates ranged from 2.5-5.5 L/min. The sheep that lived the longest (46 days) died of an embolism as a result of the thrombus in the pump. No thrombus formation was observed in other pumps. Plasma free hemoglobin levels ranged from 9 to 18 mg/dl, which led to the conclusion that the hemolysis level remained within an acceptable range. Two driving modes were compared. The slope of the pressure-flow relationship plot under a constant motor current mode was steeper than that under a constant rotational speed mode, and thus, the flow fluctuation decreased. In conclusion, the MSCP is durable for more than a month at the current stage of development and is a promising device for long-term ventricular assist.     

水幕投影

水幕显示为公共庆典提供了一种令人兴奋的显示媒体，但技术本身比其外观微妙得多。     

The biologic effects of growth factor-toxin conjugates in models of vascular injury depend on dose, mode of delivery, and animal species

Toxin-conjugates, complexes designed from the fusion of tissue toxins and pathology-specific ligands, offer the potential for targeted cytotoxic therapy. Some have postulated that the recurrent failure of these conjugates to exhibit benefit in animal models of vascular injury arose because the timing and frequency of conjugate delivery were insufficient to meet the demands of the arterial wall. Previous data suggest that increasingly frequent dosing would lead to superior inhibition of intimal hyperplasia. We now report on the biological effects of the controlled release of a recombinant conjugate of basic fibroblast growth factor (bFGF) and the plant toxin saporin (SAP), bFGF-SAP. Alginate/heparin-Sepharose microspheres and films were designed as drug carriers to control release the bFGF-SAP conjugate or bFGF alone in small doses. When bFGF-SAP-incorporated microspheres or films were implanted adjacent to balloon angioplastied porcine carotid arteries, the controlled release of bFGF-SAP over the four-week study stimulated rather than inhibited hyperplasia. When these same devices were used in cell culture, unexpected findings were produced. bFGF-SAP reduced in vitro bovine vascular smooth muscle cell growth at high concentrations (1-10 microgram/mL) but increased smooth muscle cell growth at lower concentrations (up to 1 microgram/mL). Microsphere controlled-released bFGF-SAP ( approximately 60 ng/mL over 4 days) stimulated the growth of smooth muscle cells more than any of the tested bolus applications of the conjugate. These data provide cause to reconsider our acceptance of controlled release technology as the answer to all forms of drug delivery problems, and to apply more rigorous means of matching the kinetics of drug delivery to the kinetics of the vascular response to injury.