Journal articles on the topic 'LaO(1-x)F(x)FeAs'

Based on electronic structure calculations using WIEN2k code for the iron oxypnictide LaO1-xFxFeAs a multi-band model is proposed. Within the BCS framework a generalized Fermi surface with overlapping bands is introduced. s-wave pairing symmetry and different doping values are considered. This model is used to describe some properties of iron-based oxypnictide superconductors as function of the coupling parameter as well as other relevant parameters of the model. In order to get numerical results the experimental data of LaO1-xFxFeAs with several doping concentrations provide the input of this work.

The occurrence of high-Tc superconductivity in the iron pnictides shares a similar amorphous characteristic with that of high-Tc superconducting cuprates. Here we show that nearly frictionless (electric-field-driven) transport of condensed electrons in amorphous superconductors could happen after using the Eyring's transition-rate approach which has been successfully adopted to study the critical transport of other superconductors as well as supersolid helium in very low temperature environment. The critical temperatures related to the nearly frictionless transport of electrons were found to be directly relevant to the superconducting temperature of high-temperature superconductors (like La [ O 1-x F x] FeAs (x = 0.11-0.12)) after selecting specific activation energies and activation volumes.

The superconducting iron-pnictides SmFeAsO1-xFx (x = 0.15 and x = 0.2) are studied by means of 19F-NMR spectroscopy and SQUID magnetometry. Fluctuating diamagnetism above Tc is briefly examined, stressing the analogy with the phenomenology in underdoped cuprates. The 19F relaxation rate allows us to infer an indirect magnetic coupling between Sm3+ moments, possibly involving conduction electrons in FeAs bands, with no appreciable effects on crossing the superconducting transition temperature. A comparison between the superconducting samples and the insulating SmOF, often present as spurious phase in SmFeAsO1-xFx pnictides, is also carried out. Relevant differences in the spin dynamics features are found.

In this paper, three ceramic compositions 50SiO2-50CaO (A), 45SiO2-45CaO-10P2O5 (B) and 40SiO2-40CaO-20P2O5 (C) (wt %) were synthesized by using the sol-gel technique. XRD analysis demonstrates that only sample C can form the glass material. Treated temperatures and heated times were also evaluated. Analysis data showed that the bioglass 40SiO2-40CaO-20P2O5 (wt %) can successfully elaborate when the ceramic powder heated at 750 oC for 3 hours. ‘‘In vitro’’ experiment was effectuated to investigate the bioactivity of bioglass 40SiO2-40CaO-20P2O5 by soaking powder samples in SBF solution. Obtained result confirmed the formation of hydroxyapatite (HA) phase on glass’s surface after 15 days of immersion, in which HA formation orients following (211) and (222) miller planes in crystalline structure of HA phase. Keywords Sol-gel; bioglass; hydroxyapatite; SBF; bioactivity References [1] D.F. 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Benzene (B), toluene (T), ethylbenzene (E) and xylene (X) are used commonly in paint industry, so workers who are a high risk of exposure to organic solvent (VOCs). CYP2E1 gene encodes CYP2E1 which plays an important role in the metabolism and bio-activation of volatile organic compounds. When workers expose to VOCs, their body will have a mechanism to metabolize the toxic. The enhancement of mRNA expression of CYP2E1 is a very sensitive and accurate biological marker, which is the basis for the next study to propose the level of mRNA expression of CYP2E1 gene as a human biological indicator to monitor to workers occupationally exposed to VOCs. In this study, we studied the level of mRNA expression of CYP2E1 gene from 118 participants that including 73 workers of exposed group from the paint factories and 45 workers of non-exposed group from garment factories by using Realtime-PCR with SYBR Green – an asymmetrical cyanine dye used as a nucleic acid stain in molecular biology. The initial results, showed that the exposed group had a higher mRNA expression level of CYP2E1 than the non-exposed group approximately 10.47 times, and this difference was statistically significant (P value < 0.05). And the age and the duration of exposure to organic solvents do not affect the expression level of CYP2E1. Keywords CYP2E1, the metabolisms of volatile organic compounds, mRNA expression of CYP2E1. References [1] A. Mendoza-Cantu, F. Castorena-Torres, M. Bermudez De Leon et al., Occupational toluene exposure induces cytochrome P450 2E1 mRNA expression in peripheral lymphocytes, Environmental Health Perspectives, 114 (2006) 494 - 499. https://doi.org/10.1289/ehp.8192.[2] J.H. Hartman, G. Boysen and G.P. Miller, CYP2E1 metabolism of styrene involves allostery, Drug Metabolism and Disposition, 40 (2012) 1976-1983. https://doi.org/10.1124/dmd. 112.046698. [3] S.M. Zhu, X.F. Ren, J.X. Wan et al., Evaluation in vinyl chloride monomer (VCM) - exposed workers and the relationship between liver lesions and gene polymorphisms of metabolic enzymes, World Journal of Gastroenterology,11 (2005) 5821 -5827. 10.3748/wjg.v11.i37.5821.[4] J. Wan, J. Shi, L. Hui et al., Association of genetic polymorphisms in CYP2E1, MPO, NQO1, GSTM1, and GSTT1 genes with benzene poisoning, Environmental Health Perspectives, 110 (2002), 1213-1218. https://doi.org/10.1289/ ehp.021101213.[5] U. Bernauer, B. Vieth, R. Ellrich et al., CYP2E1 - dependent benzene toxicity: the role of extrahepatic benzene metabolism, Archives of Toxicology, 73 (1999) 189 -196. https://doi.org/ 10.1007/s002040050605. [6] P.L. Sheets, G.S. Yost and G.P. Carlson. Benzene metabolism in human lung cell lines BEAS‐2B and A549 and cells overexpressing CYP2F1, Journal of Biochemical and Molecular Toxicology, 18 (2004) 92-99. https://doi.org/10. 1002/jbt.20010.[7] V. Nedelcheva, I. Gut, P. Souček et al., Metabolism of benzene in human liver microsomes: individual variations in relation to CYP2E1 expression, Archives of Toxicology, 73 (1999) 33-40. https://doi.org/10.1007/s0020400 50583.[8] W. Tassaneeyakul, D.J. Birkett, J.W. Edwards et al., Human cytochrome P450 isoform specificity in the regioselective metabolism of toluene and o-, m-and p-xylene, Journal of Pharmacology and Experimental Therapeutics, 276 (1996) 101 - 108. 10.1163/2211730x96x00063[9] A.-H. Wang, S.-M. Zhu, Y.-L. Qiu et al., CYP2E1 mRNA expression, genetic polymorphisms in peripheral blood lymphocytes and liver abnormalities in Chinese VCM-exposed workers, International Journal of Occupational Medicine and Environmental Health, 21 (2008), 141 - 146. 10.2478/v10001-008-0016-x.[10] J. Zhang, Y. Lihong, G. Liang et al., Detection of CYP2E1, a genetic biomarker of susceptibility to benzene metabolism toxicity in immortal human lymphocytes derived from the Han Chinese population, Biomedical and Environmental Sciences, 24 (2011) 300-309. https://doi.org/10. 3967/0895-3988.2011.03.014[11] American Conference of Industrial Hygienists, Guide to Occupational Exposeure Values, ACGIH, Cincinnati, 2018.[12] Bộ Y Tế, Quyết định của Bộ trưởng Bộ Y tế về việc ban hành 21 tiêu chuẩn vệ sinh lao động, 05 nguyên tắc và 07 thông số vệ sinh lao động, 2002.[13] American Conference of Industrial Hygienists, Threshold Limit Value for Chemical Substances and Physical Agents and Biological Exposure Indices, ACGIH, Cincinnati, 2018.[14] Bộ Y Tế, Thông tư 28/2006/TT- BYT hướng dẫn quản lý bệnh bệnh nghề nghiệp, 2016.[15] M. Al Zallouha, Y. Landkocz, J. Brunet et al., Usefulness of toxicological validation of VOCs catalytic degradation by air-liquid interface exposure system", Environmental Research, 152 (2017) 328-335. https://doi.org/10.1016/j.envres. 2016.10.027