The laws of silicon ingot formation by combustion reaction

The formation of a phase pure silicon ingot from SiO₂+Al+KClO₃ and Na₂SiO₃+Al+KClO₃ systems was investigated thermodynamically and experimentally under combustion mode, known also as self-propagating high-temperature synthesis (SHS). The regularities of combustion and phase formation versus KClO₃ concentration by a thermocouple technique were obtained. The morphology, chemical and phase composition of the silicon ingot were analyzed by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), and ICP-analysis. The method reported here proved effective in producing silicon ingots with a purity of 98%.     

Refractory metal nanopowders: Synthesis and characterization

Refractory nanometals have been the subject of interest for the past two decades in order to manufacture compact materials with dramatically improved mechanical properties for aerospace, military, chemical and metallurgical applications. The interest in nanomaterials has led to the development of many synthetic methods for their fabrication. In this review the challenges, synthesis methods and the characteristics of refractory metal nanopowders of IV–VI sub-group of the periodic table are discussed. Special attention is paid to salt-assisted combustion reaction (SACR) as a promising technique for the large-scale production of refractory metal nanopowders.The current paper will: (1) focus on the synthesis methods, morphology and physical–chemical characteristics of metal nanopowders; (2) present the specific feature of the salt-assisted combustion reaction, combustion parameters and macro-kinetic aspects of chemical reactions in the powder bed; and (3) demonstrate the perceptiveness of the fabrication route for the mass production of nanosized powders.     

Combustion synthesis of porous titanium microspheres

The synthesis of titanium porous microspheres by a combustion technique was studied under an argon atmosphere by using a TiO₂ − 2.5Mg reactive mixture. The precursor, a fine TiO₂ powder, was thermally treated in the range 600–1300 °C prior to the combustion experiments. TiO₂ microspheres whose diameters were between 10 and 50 μm were obtained from precursor particles annealed in the range 900–1100 °C. A biphase product consisting of Ti and MgO phases was obtained when the TiO₂ microspheres were reduced with Mg. The spherical morphology of the final particles was retained despite the relatively high combustion temperatures (1630–1670 °C) used in this study. Moreover, porous titanium microspheres were obtained when the MgO particles were dissolved using acid leaching. Scanning electron microscopy (SEM) images of the microspheres suggested that the spherical structure contained ∼0.5–2.0-μm-diameter porous windows. The Brunauer–Emmett–Teller (BET) surface area of the Ti microspheres was determined to be 2.8 m² g⁻¹.     

Structural change of hydrothermal BaTiO3 powder

Formation rate of tetragonal BaTiO₃ powder by hydrothermal synthesis and its dielectric property were studied. Submicron tetragonal BaTiO₃ powders were prepared hydrothermally, using Ba(OH)₂ · 8H₂O, TiO₂ (anatase) and KOH as starting chemicals. Characterization via X-ray diffractometry, Field Emission Scanning Electron Microscopy confirmed that increasing calcination temperature (from 1100 to 1300°C) promotes the formation of tetragonal BaTiO₃. Tetragonal BaTiO₃ ceramics obtained from optimum condition (Tetragonal BaTiO₃ powders calcined at 1200°C for 3 h after hydrothermal synthesized at 200°C for 168 h) exhibited submicron size of 0.5–0.7 m, monodispersed type and high relative permittivity.     

Densification of porous materials in rigid conical and cylindrical dies

Conclusions A solution obtained by the FEM is proposed to the problem on the nonsteady-state extrusion of a cylindrical porous blank through a conical die and on the extrustion of a porous and a bimetallic blank of varying cross sections through a conical die. Zones of large and small strains are determined from the distribution of porosity. An analysis is made by the FEM of the stressed-strained state in the double-ended densification of porous blanks in rigid cylindrical dies. Cases of the densification of porous bimetallic blanks are also considered.Translated from Poroshkovaya Metallurgiya, No. 5(233), pp. 22–27, May, 1982.     

Synthesis of hollow SiC microglobules by a combustion method

Hollow β-SiC microglobules have been synthesized successfully by a combustion technique by using a Si + C starting mixture. In this process, a controlled amount of KClO₃ + 3Mg is mixed with Si + C to enable a self-sustaining combustion regime and to promote a carburization of the silicon. The structures and morphologies of the products were analyzed by X-ray diffractometry (XRD) and a scanning electron microscopy (SEM). This procedure provides an easy method for the synthesis of hollow microglobular assemblies with SiC composed of submicrometer size particles.     

Thermomechanical effect in a cylindrically-hybrid nematic liquid crystal

Thermomechanical rotation of a cylindrically-hybrid nematic liquid crystal in the presence of a longitudinal temperature gradient is predicted theoretically and detected experimentally. Pis’ma Zh. Tekh. Fiz. 25, 71–73 (March 26, 1999)     

Immunogenicity of MultiTEP-Platform-Based Recombinant Protein Vaccine,PV-1950R,Targeting Three B-Cell Antigenic Determinants of Pathological α-Synuclein

Parkinson’s disease (PD) and dementia with Lewy bodies (DLB) are characterized by the aberrant accumulation of intracytoplasmic misfolded and aggregated α-synuclein (α-Syn), resulting in neurodegeneration associated with inflammation. The propagation of α-Syn aggregates from cell to cell is implicated in the spreading of pathological α-Syn in the brain and disease progression. We and others demonstrated that antibodies generated after active and passive vaccinations could inhibit the propagation of pathological α-Syn in the extracellular space and prevent/inhibit disease/s in the relevant animal models. We recently tested the immunogenicity and efficacy of four DNA vaccines on the basis of the universal MultiTEP platform technology in the DLB/PD mouse model. The antibodies generated by these vaccines efficiently reduced/inhibited the accumulation of pathological α-Syn in the different brain regions and improved the motor deficit of immunized female mice. The most immunogenic and preclinically effective vaccine, PV-1950D, targeting three B-cell epitopes of pathological α-Syn simultaneously, has been selected for future IND-enabling studies. However, to ensure therapeutically potent concentrations of α-Syn antibodies in the periphery of the vaccinated elderly, we developed a recombinant protein-based MultiTEP vaccine, PV-1950R/A, and tested its immunogenicity in young and aged D-line mice. Antibody responses induced by immunizations with the PV-1950R/A vaccine and its homologous DNA counterpart, PV-1950D, in a mouse model of PD/DLB have been compared.