The spherical-model limit in a random field

The spherical-model limitn of then-vector model in a random field, with either a statistically independent distribution or with long-range correlated random fields, is studied to demonstrate the correctness of the replica method in which then and replica limits limits are interchanged, provided the replica and thermodynamic limits are taken in the right order, in the case of long-range correlated random fields. A scaling form for the two-point correlation function relevant to the first-order phase transition below the lower critical dimensionality of the random system is also obtained.     

Physico-Chemistry of the Limestone Sulphation Process

Aspects of the mechanism of the overall reaction between CaCO₃/CaO and SO₂/SO₃ under oxidizing conditions are discussed. The limestone and lime sulphation processes were carried out in a thermobalance under conditions relevant to atmospheric fluidized bed combustion. Sulphated samples, prepared in the form of cross-section particles, were examined in a scanning electron microscope by energy-dispersive X-ray and back-scattered electron imaging. Photomicrographs are presented. The reaction proceeded from the outer surface of the particles and along the pores. Surface textural changes during the reaction were considered. The layer of products was identified as controlling both the rate and extent of limestone/lime sulphation. In the products, two sulphur-bearing solids (CaSO₄ and CaS) were identified. The presence of CaS, which may cause difficulties in practice, is attributed to CaSO₃ disproportionation. This revised version was published online in August 2006 with corrections to the Cover Date.     

Mechanosynthesis of zinc ferrite in hardened steel vials: Influence of ZnO on the appearance of Fe(II)

Nanocrystalline ZnFe₂O₄ spinel powders are synthesized by high-energy ball milling, starting from a powder mixture of hematite (α-Fe₂O₃) and zincite (ZnO). The millings are performed under air using hardened steel vials and balls. X-ray diffraction and Mössbauer spectrometry are used to characterize the powders. A spinel phase begins to appear after 3 h of milling and the synthesis is achieved after 9 h. Phase transformation is accompanied by a contamination due to iron coming from the milling tools. A redox reaction is also observed between Fe(III) and metallic iron during milling, leading to a spinel phase containing some Fe(II). The mechanism for the appearance of this phase is studied: ZnO seems to have a non-negligeable influence on the synthesis, by creating an intermediate wüstite-type phase solid solution with FeO.     

Amorphous phase evolution during crystallization of poly(ethylene-terephthalate)

Crystallization of poly(ethylene terephthalate) from the amorphous state has been studied in the temperature range 90°–120°C to characterize the amorphous phase when crystalline microstructure is developing. Small-angle x-ray scattering, scanning electron microscopy, and density measurements were used to investigate the morphology of semi-crystalline materials. Differential scanning calorimetry and dynamical mechanical spectroscopy experiments were carried out on amorphous, partially crystallized and crystallized specimens and, when structural relaxation is allowed (thermal treatments close to but below glass transition temperature), strong evidence is obtained for the existence of two different amorphous phases with different mobilities.     

Synthesis and structure of complex compound Rh(III) of (NH4)2[Rh(NO2)3(NH3)(µ-OH)]2 composition

The crystalline structure of a new compound Rh(III) of (NH₄)₂[Rh(NO₂)₃(NH₃)(μ-OH)]₂ composition has been determined. The crystallographic characteristics are H₁₆N₁₀O₁₄Rh₂: a = 6.3963(2) Å, b = 9.3701(4) Å, c = 13.6646(5) Å, β = 102.266(1)°, V = 800.28(5) ų, Z = 2, d _calc = 2.432 g/cm³. The distance Rh...Rh in the dimer is 3.200 Å. Original Russian Text Copyright ? 2006 by S. P. Khranenko, I. A. Baidina, and S. A. Gromilov __________ Translated from Zhurnal Strukturnoi Khimii, Vol. 47, No. 2, pp. 380–384, March–April, 2006.     

Koexistenzbeziehungen,Darstellung und Eigenschaften ternärer Phasen im System Cu/Mo/O

Coexistence Relations, Preparation and Properties of Ternary Compounds in the System Cu/Mo/O The phase diagram of the ternary system Cu/Mo/O is presented at 773 K. The compounds CuMoO₄, Cu₃Mo₂O₉, Cu₄Mo₅O₁₇, Cu₆Mo₅O₁₈, Cu_4–xMo₃O₁₂, and Cu_xMoO₃ are found to be thermodynamical stable. The homogeneity range of Cu_4–xMo₃O₁₂ runs to x = 0.1–0.2. Single crystals of CuMoO₄ and Cu₃Mo₂O₉ were grown by chemical transport reactions with TeCl₄, Cl₂, HCl, and Br₂ as transport agent. The results were compared with thermochemical calculations. The decomposition of CuMoO₄ and Cu₃Mo₂O₉ was investigated with thermal analysis and decompositon pressure measurements.     

Synthesis of protected peptides from the human IgG1 hinge region on PEG support using disulfide bond synthons and alkaline or enzymatic detachment

Peptides from the hinge region of human IgG1 are potential defined carriers of synthetic immunogens. Their synthesis was carried out on the soluble support—PEG-OMe 2000 using disulfide bond synthons. The loading capacity of the polymer was increased twofold by anchoring the lysine as a simple branching unit. The amino acid leucine was used as an enzymatically cleavable linker. Peptide detachment from the polymer was performed either by classical ester bond saponification or newly by peptide bond cleavage catalyzed by thermolysin in water.     

Pure Organic Phase Phenol Biosensor Based on Tyrosinase Entrapped in a Vapor Deposited Titania Sol‐Gel Membrane

A novel amperometric biosensor was constructed for the determination of phenols in pure organic phase. This biosensor was fabricated by immobilizing tyrosinase in a titania sol‐gel membrane which was obtained with a vapor deposition method. This method was facile and avoided the calcination step needed in conventional titania sol‐gel process. The titania sol‐gel membrane could effectively retain the essential water layer around the enzyme molecule needed for maintaining its activity in organic phase. The experimental parameters such as solvent and operating potential were optimized. At ?100 mV this biosensor showed a good amperometric response to phenols in pure chloroform without any mediator and rehydration of the enzyme. For catechol determination the sensor exhibited a fast response of less than 5 seconds. The sensitivity of different phenols was as follows: catechol > phenol > p‐cresol. Additionally, the apparent Michaelis‐Menten constants of the encapsulated tyrosinase to catechol, phenol and p‐cresol were found to be 0.15±0.003, 0.17±0.008 and 0.21±0.004 mM, respectively. The biosensor had also good reproducibility and stability. This work provided a promising platform for the construction of pure organic phase biosensors and the determination of substrates with poor water solubility.     

140 GHz回旋管高转换效率准光模式变换器设计研究（英文）

成功实现高转换效率的140 GHz TE22,6准光模式变换器原型设计。基于周期微扰原理设计Denisov辐射器,实现低边缘绕射的初级出射波束。针对三镜面光路系统,采用全矢物理光学积分作为主要计算手段,围绕主极化场分量进行三级相位修正面迭代优化,实现高出射高斯纯度的模式场转换,其中一级镜的修正有效改善了辐射器出射的不理想性。基于全矢数值仿真确认,相比原二次曲面原型设计,相位修正后的变换器系统的出射高斯纯度从92.7%提高到99.6%,结合98.8%以上的功率传递效率,实现了性能优越的高阶回旋管准光模式变换器原型设计。