Hexasupersilyloctaindane (tBu3Si)6In8— A Compound with a Novel In8 Cluster Framework

A doubly capped In ₆ octahedron characterizes the structure of the dark green octaindane (tBu₃Si)₆In₈ (see picture), which is obtained from (C₅Me₅)In and tBu₃SiNa in pentane at −78°C. In1/In1′ are the capping atoms, and In2/In2′ form the apexes of the stretched In₆ octahedron. Thus, in agreement with the results of ab initio calculations, the compound can be classified as a hypoprecloso-indane.     

Structure of Germanium Treated in a Planetary Mill

Physics of the Solid State - The structure of a powder germanium treated in a planetary mill in the presence of small (5–25%) additions of diamond powder has been studied by high-resolution...     

Thermodynamic properties of some polymeric forms of fullerite C<Subscript>60</Subscript> at temperatures ranging from 0 to 320 K

The temperature dependences of the heat capacityC ⁰ _p of fullerites C₆₀ were studied at temperatures ranging from 5 to 320 K in an adiabatic vacuum calorimeter with an accuracy of 0.4–0.2%. The fullerite C₆₀ samples were prepared by treating the starting fullerite C₆₀ under 8 GPa at 920 and 1270 K and “quenched” by a sharp decrease in pressure to −10⁵ Pa and in temperature to ∼300 K. Fullerite C₆₀(8 GPa, 920 K), a crystalline polymer with layered structure formed by polymerized fullerene C₆₀ molecules, was obtained at 920 K and 8 GPa. Fullerite C₆₀(8 GPa, 1270 K), a three-dimensional polymer with a graphite-like structure formed by fragments of decomposed C₆₀ molecules and containing many C(sp³)−C(sp³) bonds, was obtained at 1270 K and 8 GPa. Both polymers are metastable polymeric phases. The anomalous character of the temperature dependence of the heat capacity was revealed in the 49–66 K range for the polymer formed at 1270 K. The thermodynamic functions of the substances under study were calculated for the 0–320 K region along with entropies of their formation from graphite. The entropies of transformation of the starting fullerite C₆₀ into metastable phases and that of intertransformation of phases were estimated. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 277–281, February, 2000.     

Real-time control of antibody loading during protein A affinity chromatography using an on-line assay.

We show that an on-line chromatographic assay can reliably control antibody loading in real-time during protein A affinity chromatography purification of a recombinant antibody from clarified Chinese hamster ovary cell culture fluid. The on-line assay directly sampled preparative column effluent and provided real-time measurement of antibody breakthrough during loading. The on-line assay used protein A immobilized on perfusion chromatography media, equilibrated with phosphate-buffered saline at pH 7.2 and eluted with phosphate-buffered saline at pH 2.2. The assay reliably ended loading at 1% breakthrough with minimal yield loss. Reproducible yield and purity were obtained over 23 consecutive cycles. Yield remained constant while breakthrough capacity and the antibody concentration in the load changed.     

Structural and electrical properties of La0.5Sr0.5CoO3 films on SrTiO3 and porous a-Al2O3 substrates

Films of La_0.5Sr_0.5CoO₃ (LSCO) have been deposited on specially treated TiO₂-terminated (001) SrTiO₃ substrate surfaces and on macroporous polycrystalline !-Al₂O₃ substrates, having a mean pore diameter of 80 nm, by pulsed laser deposition. The films deposited on SrTiO₃ are good conducting, (001) textured, and exceptionally smooth (1-2 Å for 100 nm thick films). LSCO films deposited on porous !-Al₂O₃ are polycrystalline and exhibit good crystallographic and electrical properties despite the large substrate roughness and the differences in lattice parameters and crystal structure between the film and the substrate. Different growth modes have been observed on the porous !-Al₂O₃ substrates depending on the oxygen pressure during film deposition. Films grown at an oxygen pressure of 10^-1 mbar are macroporous, whereas films grown at 10^-2 mbar completely cover the substrate pores. In the latter case, strain effects lead to film cracking.     

Experimental demonstration of a W-band (94 GHz) gyrotwystronamplifier

A four section, TE₀₁ mode W-band gyrotwystron amplifier has been designed, built, and tested. The circuit consists of three cavities followed by a traveling wave output section, each operating near the fundamental cyclotron frequency. The gyrotwystron has produced 50 kW peak output power, corresponding to 17.5% efficiency for a 57 kV, 5 A electron beam; the amplifier is zero drive stable at the operating point. The measured center frequency is 93.9 GHz with a full width half maximum instantaneous bandwidth of 925 MHz. These results represent a substantial improvement in the power-bandwidth product over previously demonstrated gyro amplifiers in this band. The small signal and saturated gains were 39 and 30 dB, respectively. The measured results are in good agreement with theoretical predictions