Crystallization Rate Behaviour under Change of Czochralski Growth System Parameters

A comparative analysis of growth system parameters' (pulling rate, melt temperature and crucible position or melt level) change influence on crystallization rate in Czochralski growth system is represented.     

Differential inhibition of postnatal brain,spinal cord and body growth by a growth hormone antagonist

Background  

Growth hormone (GH) plays an incompletely understood role in the development of the central nervous system (CNS). In this study, we use transgenic mice expressing a growth hormone antagonist (GHA) to explore the role of GH in regulating postnatal brain, spinal cord and body growth into adulthood. The GHA transgene encodes a protein that inhibits the binding of GH to its receptor, specifically antagonizing the trophic effects of endogenous GH.     

Crystal structure and properties of a new mixed-valence compound LiMn2TeO6 and the survey of the LiMM′XO6 family (X = Sb or Te)

A new compound, LiMn²⁺Mn³⁺TeO₆, was prepared by solid-state reactions and characterized by powder X-ray diffraction, redox titration, conductivity, magnetic measurements and cycling behaviour in an electrochemical cell with Li counter electrode. It is triclinic, P1, a = 5.1077(1), b = 8.5707(1), c = 5.0589(1), α = 92.515(1)°, β = 92.092(2)°, γ = 89.818(2)°, Z = 2. The structure is based on strongly distorted hexagonal close packing of oxygen anions with cations occupying octahedral voids and represents the ordered variant of orthorhombic Li₂TiTeO₆ structure, derived from LiSbO₃. TeO₆ octahedra are almost regular but all four independent MnO₆ octahedra display severe distortions. Room-temperature conductivity is unexpectedly low for a mixed-valence compound, 2 × 10⁻⁷ S/cm. Together with the observed antiferromagnetic exchange interaction, this is a prerequisite for the colossal magnetoresistance effect. The unit cell volumes of LiMn₂TeO₆, LiSbO₃, Li₂M⁴⁺TeO₆ and LiMM′XO₆ series (a total of 21 compounds) correlate well with average cationic radii, but LiMn₂SbO₆ deviates considerably, and its preparation could not be reproduced.     

Study of the ethane oxidation reaction by the kinetic tracer method

The kinetics of ethane oxidation was studied at 320, 340, 353 and 380°C, mixture composition 2 C₂H₆ + 1 O₂, and total pressure 609 torr. It was found that at 320°C CH₂O and CH₃CHO were branching agents. A series of experiments was conducted on 2C₂H₆ + O₂ oxidation in the presence of 0.7% ¹⁴C-labeled ethylene. The ethylene oxide was found to form only from C₂H₄, formaldehyde formed from C₂H₄ and C₂H₆; and CH₃CHO, C₂H₅OH, and CH₃OH formed only from ethane. The formation rates of C₂H₄, C₂H₄O, and CH₂O were calculated by the kinetic tracer method. At 320°C the fraction of oxygen-containing products formed from C₂H₄ was 16–18%, and at 353 and 380°C it was 30–40%.     

Synthesis and structure of polycrystalline adducts of Co(II) azomethine complexes with redox-active 2,4,6,8-tetrakis-(<Emphasis Type="Italic">tert</Emphasis>-butyl)phenoxazin-1-one

The six-coordinate cobalt complexes, C₅₇H_63.50N_4.50O₄Co (IIa), C₆₀H₆₉N₅O₄Co (IIb), C5₈H₆₇N₃O₈Co (IIc), C₅₆H₆₁N₅O₁₀Co (IId), C₅₆H₆₃N₃O₆Co (IIe), C₅₈H₆₆N₄O₆Co (IIf), and C₅₈H₆₃N₇O₈Co (IIg), adducts of high-spin tetrahedral Co(II) bis(salicylaldiminates) (C₂₉H_24.50N_3.50O₂Co (Ia), C₃₂H₃₀N₄O₂Co (Ib), C₃₀H₂₈N₂O₆Co (Ic), C₂₈H₂₂N₄O₈Co (Id), C₂₈H₂₄N₂O₄Co (Ie), C₃₀H₂₇N₃O₄Co (If), and C₃₀H₂₄N₆O₆Co (Ig)) and redox-active 2,4,6,8-tetrakis(tert-butyl)phenoxazin-1-one (L), were synthesized and studied for structure and magnetic properties. Complexes IIa–IIg have octahedral structure (CIF files CCDC nos. 1403920 (IIf), 1403922 (IIg)) and exist in the ground low-spin state (ls-Co^III-SQ), which arises upon intramolecular single-electron redox process in the ligand–metal system. The presence of substituents of different nature in the azomethine ligands of IIa–IIg does not induce any significant changes in their magnetic properties.     

Effect of a structural disorder on the magnetic properties of the sodium–cobalt tellurate Na<Subscript>3.70</Subscript>Co<Subscript>1.15</Subscript>TeO<Subscript>6</Subscript>

A new layered oxide, sodium–cobalt tellurate Na_3.70Co_1.15TeO₆, is synthesized and structurally characterized, and its static and dynamic magnetic properties are studied. This compound has a new monoclinic structure type with quasi-one-dimensional cation ordering in magnetically active layers. This compound is antiferromagnetically ordered at a Néel temperature T _N ~ 3.3 K, and the temperature and field dependences of magnetization suggest competing antiferromagnetic and ferromagnetic interactions. EPR spectroscopy reveals complex spin dynamics when temperature changes and the presence of two different paramagnetic centers, which is attributed to the existence of two structurally nonequivalent (regular and antisite) positions for magnetic Co²⁺ ions.     

Modification of Mössbauer reflection spectra of group AIIBVI single crystals with Fe<Superscript>57</Superscript> nuclei under influence of infrared radiation

Interaction of Mössbauer gamma radiation with ultrasound vibrations in group AIIBVI single crystals of CdS and CdSe with Fe⁵⁷ impurity nuclei under action of infrared radiation is investigated. It is shown that the infrared irradiation excites a phonon field in single crystals. Similar to the case of optical irradiation of single crystals the shape of their Mössbauer spectrum is modified. The effect of double modulation of resonant gamma radiation by infrared radiation has been observed.