The Application of SF6 in the Geochemical Research

For mass spectrometric measurements of δ³¹S, pure sulphur hexafluoride was prepared quantitatively from different mineral sulphides by the reaction with elemental fluorine under pressure. The results of δ³¹S measurements on SF₆ samples were confirmed by comparison of δ³¹S values with the classical method leading to SO₂. Numerous mass spectrometric measurements of SF₆ and SO₂ with regard to the experimental conditions of the synthesis, the influence of background, memory effect, and adsorption were made. The measurements of small isotopic variations of sulphur with SF₆ has advantages in comparison to the SO₂ technique. The method described can be successfully used for routine work.     

Sulphur transformation during pyrolysis of an Australian lignite

Transformation of various sulphur forms, including inherent and added pyrite, sulphates (CaSO₄ and FeSO₄) and organic sulphur, during pyrolysis of an Australian lignite was studied using TGA, TGA-MS and a fixed bed reactor, supplemented by sulphur form analysis. It was shown that hydrogen sulphide (H₂S) and a small quantity of sulphur dioxide (SO₂) were released during the pyrolysis of the pyrite-lignite blend. However, only SO₂ was detected during the pyrolysis of the lignite with high pyrite content. Inorganic matter was found to help retaining some of the inorganic sulphur, including pyrite, in the char. Inherent sulphates decomposed at much lower temperatures than the added sulphates, releasing SO₂ rather than H₂S. The inherent sulphates in the lignite were dominated by iron sulphates which started to decompose and release SO₂ at around 500 K and all sulphate had been decomposed at 1073 K. The retention of organic sulphur in the high organic sulphur lignite was higher than in its acid washed lignite sample, due to the interaction between inherent inorganic matter with the organic sulphur retaining the organic sulphur in the solid phase. SO₂ was the only sulphur gas produced during pyrolysis of acid washed lignite. A comprehensive mechanism of sulphur transformation during pyrolysis of lignite was proposed.     

含硫添加剂润滑下CrMoCu合金铸铁渗硫层的摩擦磨损性能研究

采用低温离子渗硫技术在CrMoCu合金铸铁表面形成厚度约5μm渗硫层,渗硫层表面分布均匀,其相组成主要为FeS．在液体石蜡及含硫添加剂液体石蜡润滑下,对未渗硫及渗硫表面进行摩擦磨损性能对比试验,并对其磨损表面形貌和成分进行分析．结果表明,在高速重载条件下,CrMoCu合金铸铁经表面渗硫后其摩擦系数明显降低,同时降低了材料的粘着倾向,提高了材料的抗擦伤性能,在渗硫层与含硫添加剂协同作用下生成钼的化合物、磷酸盐及硫化物等化学反应膜,使CrMoCu合金铸铁表面具有更加优良的减摩耐磨性能．     

SO2 binding into the solid phase during thermooxidation of blendsestonian oil shale semicoke

Approximately one million tons of semicoke (SC) is formed and stored in open air dumps every year in the production of shale oil by processing Estonian oil shale (OS). The content of different harmful compounds as sulphides, PAH, phenols, etc. in SC make these dumps one of the most serious sources of environmental contamination. The aim of this work was to study the behaviour of sulphur compounds in OS and its SC, formation of SO₂ and possibilities of binding it into the solid phase during thermooxidation of fuel blends based on SC. Blends modified with SC ash addition were studied as well. It was determined that SO₂ emission in thermooxidation of SC samples started at 280-300°C and proceeded with a steady speed up to 580-600°C and the amount of sulphur evolved was 5-10% from the total content of sulphur in the sample. The amount of SO₂ emitted decreased depending on the mass ratio of the composite fuels from 49-56 to 15-35% during thermooxidation of OS samples studied or their blends with SC, respectively, from 43-80% for coal samples to 13-60% for their blends with SC and to 2-13% during thermooxidation of these blends modified with SC ash addition. In the products of thermooxidation formed at 800-900°C the only sulphur containing phase was CaSO₄, at 650°C also traces of CaS and CaMg3(SO₄)₄ were fixed. This revised version was published online in July 2006 with corrections to the Cover Date.     

荧光光度法测定大气中痕量二氧化硫

在弱酸性介质中,碘与荧光素反应导致荧光素荧光强烈猝灭,而ＳＯ＾２－３的存在可以有效地抑制这猝灭作用,使得体繁荣为光强度增强,籍此可测定痕量ＳＯ＾２－３,在线性范围为２５－１５０μｇ／Ｌ,检出限为８．７μｇ／Ｌ。该法快速,灵敏,选择性好,操作简便,用于大气中二氧化硫实际样品分析,结果令人满意。     

London penetration depth and thermal fluctuations in the sulphur hydride 203 K superconductor

Recently, compressed H₂S has been shown to become superconducting at 203 K under a pressure of 155 GPa. One might expect fluctuations to dominate at such temperatures. Using the magnetisation critical current, we determine the ground‐state London penetration depth, λ₀=189 nm, and the superconducting energy gap, Δ₀=27.8 meV, and find these parameters are similar to those of cuprate superconductors. We also determine the fluctuation temperature scale, K, which shows that, unlike the cuprates, of the hydride is not limited by fluctuations. This is due to its three dimensionality and suggests the search for better superconductors should refocus on three‐dimensional systems where the inevitable thermal fluctuations are less likely to reduce the observed .

     

Part 1: An Appraisal of New Radioisotope Techniques in the Study of Iodine Metabolism

The use of different radioiodines and technetium for the evaluation of the thyroid functions has been discussed. Preparation oe labelled iodotyrosines and labelled throxine is mentioned for the convey of different radiochemical tests and for the use of reference standards, necessary for the identification of separated amino acids. Paper chromatography and paper electrophoresis techniques are used for the identification and determination of iodinated amino acids or homones, either in the free state or bound to the proteins. Tc^99m is employed to substitute radioiodine in the study of uptake measurements of the thyroid gland and to evaluate the excretion of the isotope in urine. Thiourea-S³⁵ is employed, for the first time to human, to study the metabolism of the substance in different thyroid disorders.     

Electron scattering studies of DMS,DMDS and DMSO homologous series

The present paper reports ionisation, elastic and total cross section for the first three members of dimethyl sulphide, dimethyl disulphide and dimethyl sulphoxide family of molecules. The multi-scattering centre spherical complex optical potential formalism is applied for integral elastic and inelastic cross section calculations. From the inelastic part, ionisation cross section is derived using complex scattering potential-ionisation contribution method. The total cross section is then obtained from the sum of elastic and inelastic contributions. A reasonably good agreement is obtained for elastic cross section, wherever comparison is available. The ionisation and total cross section calculation for the complete set of molecules has been performed for the first time.     

Phasing of lysozyme using one－wavelength anomalous scattering of sulphur atoms through the combination of direct methods and density modification

A new method of combining one-wavelength anomalous scattering (OAS) phasing and density modification has been described, in which the improved phases from density modification axe re-introduced into OAS phasing. In this way, the phases could be improved iteratively until convergence. The OAS phasing method is based on the previously established sign-probability formula, which breaks the phase ambiguity in the OAS phasing. The implementation of this method has been available in CCP4 as OASIS. This method, although based on direct-methods, could also incorporate known phases and figures of merit into its sign-probability formula. In the implementation of OASIS, the known phases axe from the positions of the anomalous scatters. In the current method, the known phases are from the density modification. The current method was tested on phasing a lysozyme crystal using anomalous scattering of sulphur atoms with diffraction data collected on an in-house x-ray source. The resulting map was well connected for the backbone atoms and clearly traceable, with an average map correlation coefficient of 0.6622 for the backbone atoms.     

HV-21型碳硫自动分析仪测定碳、硫常见问题及解决办法

采用HV－21型碳硫自动分析仪测定碳、硫时，经常出现空白值偏高，碳含量突然偏低或无检测信号等现象，对这些现象进行了分析并提出了解决办法。