Free SHS-Compression Method for Producing Large-Sized Plates from Ceramic Materials

Refractories and Industrial Ceramics - A free SHS-compression method was used to produce large-sized plates measuring 120 × 80 × 8 and 80 × 40 × 8 mm from a titanium...     

Scaling of general quadratic matrix equations

A scaling framework for general quadratic algebraic matrix equations is presented. All algebraic quadratic equations can be considered as special cases of a single generalized algebraic quadratic matrix equation (GQME). Hence, the paper is focused on the analysis and solution of the scaling problem of that GQME. The presented scaling method is based on the assignment of predetermined values of the coefficients and the unknown matrices of the GQME. The proposed framework is independent of any numerical method and therefore its use is general. Implementations are presented for the special case of matrix algebraic Riccati equations (AREs). Some new results of matrix algebraic identities considering Kronecker and Hadamard products are also reported.     

Thermoelectric Properties of nGeTe · mSb2Te3Layered Compounds

The Hall coefficient, electrical conductivity, and thermoelectric power of Ge₃Sb₂Te₆, Ge₂Sb₂Te₅, GeSb₂Te₄, and GeSb₄Te₇were measured over a wide temperature range (R _Hand from 77 to 800 K and Sfrom 90 to 450 K). The carrier concentration was varied via compositional changes within the homogeneity regions of the compounds. All of the materials studied were found to be p-type. Some of the alloys have a low lattice thermal conductivity and are, therefore, candidate p-type thermoelectric materials. The temperature-dependent hole mobility data suggest that both acoustic phonons and point defects contribute to the scattering of charge carriers at low temperatures.     

Structure and Superconducting Properties of Cd0.8Ba2(Y0.7Ca0.4)Cu3.5Oy

A new Cd-containing superconductor with nominal composition ofCd_0.8Ba₂(Y_0.7Ca_0.4)Cu_3.5O _y was synthesized and investigated. The obtained Cd and Ca-doped 123 phase exhibits an orthorhombic (T _c=80 K) or tetragonal (T _c=65 K) modification depending on the reaction atmosphere. It was shown that the combined Cd and Ca substitution facilitates the 123 phase formation. The results of the EDX analysis, as well as the comparison of the obtained lattice parameters with those of undoped, Cd-doped, and Ca-doped 123 have shown that both Cd and Ca enter the 123 phase and form a new Cd–Ba–Y–Ca–Cu–O superconducting compound.     

Certification of Class I standard spectrometric gamma sources

Conclusions High accuracy can be obtained with the relative method of determining-radiation activity on a scintillation counter only when the samples are precisely positioned, especially for small distances between the source and the radiation detector. Because of the low levels of activity of the standards (approximately 0.5 Ci) SSGS must be calibrated for small distances between the source and the detector. Additional measurements taken with the source rotated through 180 greatly reduce the systematic error caused by inaccurate positioning. A large scintillation crystal of NaI(T1) used as a detector reduces systematic error in relative measurements owing to the sources shifting from the detector axis and to variations in the dimensions of the radioactive spots of different sources.Translated from Izmeritel'naya Tekhnika, No. 2, pp. 77–80, February, 1971.     

Analysis of Electromagnetic Waves Scattering by a Finite Size Dielectric and Metal Cylinder in a Rectangular Waveguide

The paper presents a rigorous solution of the scattering problem by a circular dielectric and perfectly conducting cylinders of any radius and any height in the rectangular waveguide oriented perpendicularly to a wall. The method is based on the representation of fields in waveguide and dielectric medium by cylindrical eigenfunctions and application of boundary conditions on surfaces of the cylinder to evaluate the fields inside and outside the cylinder. The reflection and transmission coefficients are expressed through the fields. As an example the reflection and transmission coefficients versus frequency for various dielectric and metallic cylinders are computed. The comparison of numerical with experimental data is presented.     

Vibration spectroscopy study of hydrolyzed precursors for sintering calcium phosphate bio-ceramics

Diffuse reflectance infrared Fourier transform and Raman spectroscopy is applied to investigate the structure of hydrolyzed CaHPO₄ · 2H₂O (DCPD) processed to non-stoichiometric apatite to be used as starting material for preparing sintered calcium phosphate materials. The spectra of hydrolyzed DCPD samples, obtained under differing experimental conditions, are analyzed to check how the sintered phase composition correlates with the structure of the hydrolyzed precursor. It is shown that the addition of extra Ca²⁺ ions in the alkaline solution during the process of hydrolyzing affects strongly the degree of disorder in the structure of the hydrolyzed materials, thus increasing the relative amount of hydroxyapatite in the final sintered product. The addition of F^– ions to the synthesis mixture strengthens slightly the P-O bonds in the precursors and increases the content of hydroxyapatite phase in the sintered material. As a result bi-phase ceramics of highest content of hydroxyapatite can be produced using both fluorine additives and calcium compensators in the synthesis suspension.     

ATP-dependent proteolysis in mitochondria. m-AAA protease and PIM1 protease exert overlapping substrate specificities and cooperate with the mtHsp70 system

To analyze protein degradation in mitochondria and the role of molecular chaperone proteins in this process, bovine apocytochrome P450scc was employed as a model protein. When imported into isolated yeast mitochondria, P450scc was mislocalized to the matrix and rapidly degraded. This proteolytic breakdown was mediated by the ATP-dependent PIM1 protease, a Lon-like protease in the mitochondrial matrix, in cooperation with the mtHsp70 system. In addition, a derivative of P450scc was studied to which a heterologous transmembrane region was fused at the amino terminus. This protein became anchored to the inner membrane upon import and was degraded by the membrane-embedded, ATP-dependent m-AAA protease. Again, degradation depended on the mtHsp70 system; it was inhibited at non-permissive temperature in mitochondria carrying temperature-sensitive mutant forms of Ssc1p, Mdj1p, or Mge1p. These results demonstrate overlapping substrate specificities of PIM1 and the m-AAA protease, and they assign a central role to the mtHsp70 system during the degradation of misfolded polypeptides by both proteases.