Structural and superconducting properties of single-crystal Bi2Sr2Can ? 1CunO2n + 4 + δ (n = 1–3) whiskers grown in gas-filled cavities

Using growth inside gas-filled cavities in KCl-fluxed melts, we have obtained free-standing phasepure Bi₂Sr₂Ca _{n − 1}Cu _n O_{2n + 4 + δ} (n = 1–3) whiskers possessing superconducting properties in the as-grown state. Bi-2212 whiskers have been prepared in a wide range of doping levels, from underdoped (T _c = 76.5 K) to optimally doped (T _c = 84 K). The whiskers possess high structural perfection, as shown by X-ray diffraction. Annealing under optimal conditions raises the superconducting transition temperature of the underdoped Bi-2212 whiskers to T _{c max} = 85.5 K (ΔT _c = 1.8 K), without impairing their structural perfection. Original Russian Text ? M.V. Golubkov, Yu.I. Gorina, G.A. Kalyuzhnaya, V.V. Rodin, N.N. Sentyurina, V.A. Stepanov, S.G. Chernook, 2009, published in Neorganicheskie Materialy, 2009, Vol. 45, No. 6, pp. 731–737.     

Asymmetric Dimethylarginine Is a Marker of Endothelial Dysfunction in Thrombotic Antiphospholipid Syndrome Patients

Objective: The potential contribution of asymmetric dimethylarginine (ADMA) and high-sensitivity C reactive protein (hsCRP) to endothelial dysfunction in APS patients has not been studied in detail, until now. The study involved 105 APS patients (59 diagnosed with primary APS (PAPS) and 46 APS associated with systemic lupus erythematosus (SAPS)) who were compared to 40 controls. Endothelial dysfunction was assessed by measurement of flow-mediated dilatation (FMD) and glyceryl trinitrate dilatation (NMD) of the brachial artery. ADMA (micromol/L) was analyzed by ELISA. Results: FMD in patients with APS was significantly lower than that of the controls (p < 0.001), with no difference between the PAPS and the SAPS groups. ADMA and hsCRP concentrations were significantly higher in the patient cohort than in the control group (p < 0.001, p = 0.006, respectively), as was the case with the SAPS group as compared to the PAPS group (p < 0.001, p = 0.022, respectively). FMD impairment correlated to ADMA (ρ 0.472, p < 0.001) and to hsCRP (ρ 0.181, p = 0.033). In the regression model, the ADMA concentration confirmed the strength of its association (B 0.518, SE 0.183, Wald 8.041, p = 0.005, Exp(B) 1.679, 95% CI 1.174–2.402) to FMD impairment. The synergistic probability model of ADMA and hsCRP caused FMD impairment when the positivity of β2GPIIgG was added. ADMA may be used as a simple and low-cost tool for verifying the presence of endothelial dysfunction in APS patients. According to the results of the study, we could presume that hsCRP, together with aPL, has a preparatory effect on the endothelium in causing endothelial dysfunction.     

Chitosan modified by poly(ethylene oxide): Film and mixture properties

Chitosan + poly(ethylene oxide) mixtures and films prepared from these mixtures were studied by rheological, absorption of solvent vapors, SANS, and mechanical testing methods. At a stoichiometric chitosan:poly(ethylene oxide) monomer:monomer composition, the mechanical properties of chitosan + poly(ethylene oxide) film are the best as compared with those of the initial components or of other compositions. This film composition is shown to be less heterogeneous. Chitosan and poly(ethylene oxide) are proved to be slightly incompatible polymers. This is supposed to induce the two components to align and to order at their stoichiometric composition, leading to the improvement in the mechanical properties. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1114–1122, 2002; DOI 10.1002/app.10319     

Low back pain among mineworkers in relation to driving,cold environment and ergonomics

Objectives: We aimed to study the association between low back pain (LBP) and exposure to low temperature, wet clothes, heavy lifting and jobs that involve whole body vibration (WBV) in a population of miners. Methods: Health and personal data were collected in a population study by a questionnaire. A total of 3530 workers from four mines participated in the study. Results: 51% of the workers reported LBP within the last 12 months. The adjusted odds ratio for LBP was above unity for working with wet clothes (1.82), working in cold conditions (1.52), lifting heavy (1.54), having worked as a driver previously (1.79) and driving Toro400 (2.61) or train (1.69). Conclusion: Wet clothing, cold working conditions, heavy lifting, previous work as a driver and driving certain vehicles were associated with LBP, but vehicles with WBV levels above action value were not. For better prevention of LBP, improved cabin conditions and clothing should be emphasised.     

Processing the wastes from the production of methyl chloride in the synthesis of olefins from natural gas

The gas phase (200–400°C) catalytic hydrodechlorination (HDC) of the main waste components (CH₂Cl₂, CH₃Cl, CCl₄) obtained in the production of methyl chloride from methane was studied with the aim of utilizing them in the development of promising technology for the synthesis of light olefins from methane via the pyrolysis of methyl chloride. Laboratory investigations were conducted on industrial hydrogenation and hydrotreating catalysts. Three catalytic systems and the conditions ensuring the stable operational characteristics of the HDC process were chosen. Methane, methyl chloride, light olefins, and HCl are the main products of this process. The use of Ni-Mo/Al₂O₃ catalyst leads to an increase in the CH₃Cl and olefin concentrations in the products. All the products of the HDC process can be used in the production of olefins to create a wasteless and chlorine-balanced technology for the synthesis of olefins from natural gas (methane). Owing to their considerable waste volumes, the technology for the synthesis of olefins cannot be realized without the HDC stage.     

Intercalation Method for the Synthesis of Fine Aluminium Hydroxide

A new method to synthesize fine low-alkaline aluminium hydroxide from technical-grade gibbsite has been proposed. This method is based on carrying out the cycle of intercalation–deintercalation of lithium salts within gibbsite. In order to improve the intercalation process, which requires substantial consumption of water, the electrodialysis method is proposed.     

The photolysis of metal carbonyl polymers in solutions and polymer films

The photochemical behaviour of VIB group metal carbonyl complexes of polyacrylonitrile (PAN) and iron tricarbonyl complexes of poly(styrene-butadiene) (SBS) block-copolymer have been investigated in this study in dimethylsulphoxide (DMSO) and/or in N,N-dimethylformamide (DMFA) solutions as well as in polymer films. In the case of metal carbonyl complexes with polyacrylonitrile the primary photochemical reactions have been shown to be the dissociation of pentaand tetracarbonyl complexes which result in the removal of one nitrile ligand followed by an exchange between the nitrile groups and the solvent molecules. The removal of CO has been shown to be the most probable photochemical reaction in films of these polymers. In the case of the iron tricarbonyl complex of SBS, laser photolysis leads to the fast isomerization of the complex followed by the replacement of the olefin groups of the polymer by CO.     

1-Isobutanoil-2-isopropylisothiourea Phosphate,T1082: A Safe and Effective Prevention of Radiotherapy Complications in Oncology

The radioprotective effects of a new 1-isobutanoil-2-isopropylisothiourea derivative named T1082 are presented. Research methods included toxic characteristics, radioprotective activity (Till–McCulloch’s test and 30-day survival test) in γ-ray total-body-irradiated mice, and a clinical and histological study of the effect of T1082 on acute radiation skin reactions (RSR) in rats after a single or fractionated β-ray local irradiation. T1082 is more effective than its analogue, the NOS inhibitor T1023, at low concentrations and doses (1/12–1/8 LD₁₀), both parenterally and intragastrically. In this case, its therapeutic index (LD₅₀/ED₅₀) reaches 30, and the optimal radioprotective doses (ED_84–98—141–224 mg/kg) are an order less than the maximum tolerated doses—1/16–1/10 LD₁₀. These properties allowed T1082, at a low intragastrical dose (160 mg/kg; 1/14 LD10), to significantly limit the severity of acute RSR after single (40 Gy) and fractionated (78 Gy) β-ray irradiation. The results confirm T1082 as one of the safest emergency radioprotectors and indicate the prospects for its further development as a pharmacological agent for the prevention of RT complications.     

Determination of 210Pb and 210Po in Sediments, Water, and Plants in an Area Contaminated with Mine Waste

We compared the activities of ²¹⁰Pb and ²¹⁰Po in samples of reeds with the concentrations in sediment and water, and estimated the capability of bioaccumulation of these radionuclides in the reeds. The results showed that there are very high levels of ²¹⁰Pb and ²¹⁰Po in sediment from the Boršt stream, where mill tailings were transported. The reeds accumulate ²¹⁰Pb to a slightly higher extent than ²¹⁰Po and in this way help to decontaminate the water, which then flows via a channel into the Todraščica stream. We also observed that the stream possessed a good self-cleaning capability. The Jazbec waste pile, where spoils and lower grade ores were disposed of, is not badly contaminated with ²¹⁰Pb and ²¹⁰Po, and has little influence on the environment.     

DnaK from Vibrio proteolyticus: complementation of a dnaK-null mutant of Escherichia coli and the role of its ATPase domain

We cloned the 4.8-kbp DNA fragment containing the dnaK gene from the chromosomal DNA of Vibrio proteolyticus. It contained four genes arranged unidirectionally in the order of grpE, gltP, dnaK and dnaJ. The DnaK gene of V. proteolyticus (VprDnaK) allowed a dnaK-null mutant of Escherichia coli (DeltadnaK52) to propagate lambda phages but not to grow at 43 degrees C. However, a chimeric DnaK gene comprising the regions corresponding to the N-terminal ATPase domain of E. coli DnaK (EcoDnaK) and the C-terminal region of VprDnaK including the substrate-binding domain, enabled the mutant to grow at 43 degrees C. The temperature dependence for the ATPase activity of the chimeric DnaK was similar to that of EcoDnaK. Fluorometric analyses showed that the chimeric DnaK is much more thermostable than EcoDnaK and VprDnaK. These findings indicate that the thermal stability of the ATPase domain of DnaK is responsible for its chaperone action at high temperatures such as 43 degrees C.