Potential release of hydrogen fluoride from domestic coal in endemic fluorosis area in Guizhou,China

Almost half of the total rural area of Guizhou Province and many regions within the 11 adjacent provinces in southwestern China have a long history(at least 70 years) of endemic fluorosis,including dental fluorosis and osteofluorosis along with its associated deformities and disabilities.Over decades of research,this specific type of endemic fluorosis has been defined as coal-burning fluorosis,which is distinct from drinking-water fluorosis.It is generally acknowledged that indoor burning and combustion of high-fluorine coal leads to food contamination,and fluorine then enters the human body.However,the exact chemical form of fluorine during its release and transfer to the body is still unknown.In the present study,21 domestic coal samples from outcrop and semi-outcrop coal collected in five villages with fluorosis were analyzed by time-of-flight secondary ion mass spectrometry(TOF-SIMS).The total mass fraction of sulfur in the samples ranged from 0.24%-5.58% and total fluorine content ranged 90.2-149.2 mg/kg.H3O+,H2SO4+ and HSO4-were detected in the samples by TOF-SIMS,which indicated that sulfuric acid hydrate(H2SO4.H2O) was present in the samples.F-was detected in all of these,which suggested the samples contain ionic fluorine compounds.Under certain circumstances,such as heating or burning,the prevalence and coexistence of the acid(H2SO4.H2O) and base(F-) would lead to a neutralization reaction producing volatile hydrogen fluoride(HF,bp = 19.5℃).This would be the chemical form of fluorine released from the coal.Further studies using HF and SO2 test tubes on headspace gas over coal samples heated to 200℃ in the laboratory and on headspace gas over stoves or chimney tops at rural residences confirmed the release of HF.     

Fatty-acids and their <Emphasis Type="Italic">δ</Emphasis><Superscript>13</Superscript>C characteristics of seep carbonates from the northern continental slope of Gulf of Mexico

Here we reported the fatty-acids and their δ¹³C values in seep carbonates collected from Green Canyon lease block 185 (GC 185; Sample GC-F) at upper continental slope (water depth: ~540 m), and Alaminos Canyon lease block 645 (GC 645; Sample AC-E) at lower continental slope (water depth: ~2200 m) of the Gulf of Mexico. More than thirty kinds of fatty acids were detected in both samples. These fatty acids are maximized at C₁₆. There is a clear even-over-odd carbon number predominance in carbon number range. The fatty acids are mainly composed of n-fatty acids, iso-/anteiso-fatty acids and terminally branched odd-numbered fatty acids (iso/anteiso). The low δ¹³C values (−39.99‰ to −32.36‰) of n-C₁₂:0, n-C₁₃:0, i-C₁₄:0 and n-C₁₄:0 suggest that they may relate to the chemosynthetic communities at seep sites. The unsaturated fatty acids n-C_18:2 and C_18:1△⁹ have the same δ¹³C values, they may originate from the Beggiatoa/Thioploca. Unlike other fatty acids, the terminally branched fatty acids (iso/anteiso) show lower δ¹³C values (as low as −63.95‰) suggesting a possible relationship to sulfate reducing bacteria, which is common during anaerobic oxidation of methane at seep sites.     

UV/visible spectroscopic analysis of CO<Superscript>3+</Superscript> and CO<Superscript>2+</Superscript> during the dissolution of cobalt from mixed Co-Cu oxidized ores

The leaching of cobalt from four-mixed Co-Cu oxidized ores containing cobalt at levels ranging from 0.5wt% to 34wt% was studied and the results has been reported. Conventional dissolution of these oxidized Co-Cu ores with diluted H₂SO₄ and SO₂ as a reducing agent resulted in a substantial improvement in the solution based recovery of cobalt. UV/visible spectroscopic analysis of the leached solutions indicated that the increased cobalt content in the solution was a result of flushing the acidified cobalt leaching solution with SO₂. Furthermore, UV/visible spectroscopy confirmed that as SO₂ was flushed into the acidified leaching solution, Co³⁺ bearing minerals were reduced to the readily soluble Co²⁺ bearing minerals, and this resulted in the increase of total cobalt in the collected solution. The mechanism of the reduction of Co³⁺ to Co²⁺ bearing minerals when SO₂ is flushed during the leaching of mixed Co-Cu oxidized ores, including the stability trends of Co³⁺, Co²⁺, and Cu²⁺ complexes, as shown by their UV/visible spectra, are also discussed.     

Analysis of active sites for N2 and H^＋ reduction on FeMo-cofactor of nitrogenase

Dinitrogen (N2) and proton (H ),which act as physiological substrates of nitrogenase,are reduced on FeMo-co of the MoFe protein. However,researchers have different opinions about their exact reduction sites. Nitrogenases were purified from the wild type (WT) and five mutants of Azotobacter vinelandii (Av),including Qα191K,Hα195Q,nifV-,Qα191K/nifV- and Hα195Q/nifV-; and the activities of these en-zymes for N2 and H reduction were analyzed. Our results suggest that the Fe2 and Fe6,atoms closed to the central sulfur atom (S2B) within FeMo-co,are sites for N2 binding and reduction and the Mo atom of FeMo-co is the site for H reduction. Combining these data with further bioinformatical analysis,we propose that two parallel electron channels may exist between the 8Fe7S cluster and FeMo-co.     

Reaction condition optimization and kinetic investigation of roasting zinc oxide ore using (NH<Subscript>4</Subscript>)<Subscript>2</Subscript>SO<Subscript>4</Subscript>

An orthogonal test was used to optimize the reaction conditions of roasting zinc oxide ore using (NH₄)₂SO₄. The optimized reaction conditions are defined as an (NH₄)₂SO₄/zinc molar ratio of 1.4:1, a roasting temperature of 440°C, and a thermostatic time of 60 min. The molar ratio of (NH₄)₂SO₄/zinc is the most predominant factor and the roasting temperature is the second significant factor that governs the zinc extraction. Thermogravimetric–differential thermal analysis was used for (NH₄)₂SO₄ and zinc mixed in a molar ratio of 1.4:1 at the heating rates of 5, 10, 15, and 20 K·min-1. Two strong endothermic peaks indicate that the complex chemical reactions occur at approximately 290°C and 400°C. XRD analysis was employed to examine the transformations of mineral phases during roasting process. Kinetic parameters, including reaction apparent activation energy, reaction order, and frequency factor, were calculated by the Doyle–Ozawa and Kissinger methods. Corresponding to the two endothermic peaks, the kinetic equations were obtained.     

The synthesis and characterization of a Co-N/C composite catalyst for the oxygen reduction reaction in acidic solution

A non-precious metal Co-N/C catalyst for the oxygen reduction reaction (ORR) was synthesized by heating a mechanical mixture of cobalt chloride, urea and acetylene black under a nitrogen atmosphere. The catalyst was characterized by XRD and XPS. The electrocatalytic activity in the ORR was evaluated by linear sweep voltammetry in 0.5 mol L⁻¹ H₂SO₄ solution. The results show that the Co-N/C catalyst aids the reduction of oxygen. The presence of elemental cobalt in the precursor allows nitrogen atoms to embed themselves in the graphite matrix to form pyridinic and graphitic type C-N structures as the ORR active sites. The effect of heat-treating temperature on the catalytic activity was also investigated. The results also show that the Co-N/C catalyst is most active when pyrolyzed at 600°C. The obtained Co-N/C catalyst loses some activity after initial exposure to the H₂SO₄ solution because of leaching, but is then stable for up to 20 h immersion. The catalyst is also stable when charged, which is supported by the cyclic voltammetry results.     

硫酸铵和硫酸钠溶液侵蚀下水泥土力学性质试验研究

为研究硫酸铵和硫酸钠溶液侵蚀下水泥土的力学性质,将制备的水泥土试块置于不同浓度的硫酸铵和硫酸钠溶液中进行长期(150 d)浸泡,通过无侧限抗压强度试验,得到无侧限抗压强度随侵蚀溶液浓度和侵蚀时间的变化规律,分析硫酸铵和硫酸钠溶液侵蚀对水泥土力学性质的影响。研究结果表明:硫酸铵和硫酸钠溶液对水泥土均具有侵蚀作用,浓度越大,侵蚀越显著;浸泡时间越久,侵蚀越明显;在侵蚀早期,硫酸钠浓度在一定范围内对水泥土的抗压强度增长有利,在短期内硫酸钠溶液可以提高水泥土试块无侧限抗压强度;在相同SO_4~(2-)浓度下,硫酸铵溶液侵蚀下的水泥土抗压强度要低于硫酸钠溶液侵蚀下的抗压强度,铵盐会对水泥土的力学性质产生影响;硫酸盐对水泥土的侵蚀作用要远大于铵盐对水泥土侵蚀作用。     

Different patterns of agonist-induced modulation of α1B-adrenoceptor density at different initial expression levels

We compared the norepinephrine (NE) induced α_1B-adrenoceptor (α_1B-AR) expression modulation between two transfected human embryonic kidney (MEK) 293 cell lines in which α_1B-AR densities were (6 336 ± 913) and (773 ± 164) fmol ▪ mg¹, respectively. Treatment of cells with NE (10 μmol ▪ L₁) for 48 h decreased high-level expressed α_1B-AR density, but increased low-level expressed α_1B-AR density. The protein kinase C inhibitor Calphostin C or Ro-31-8220 reversed, and its activator PMA mimicked the NE-induced down-regulation of high-level expressed α_1B-AR. Moreover, PMA induced a down-regulation of low-level expressed α_1B-AR. The endoplasmic reticulum Ca²⁺-ATPase inhibitor cyclopiazonic acid (CPA) and the calcium chelator BAPTA/AM did not affect the down-regulation of high-level expressed α_1B-AR, but inhibited the up-regulation of low-level expression α_1B-AR induced by NE. These results suggest that α_1B-adrenoceptor densities at different initial expression levels are differentially regulated by NE and their signal transduction pathways are different.     

An acidic polysaccharide with xylose branches fromPorphyra yezoensis

An acidic polysaccharide (PY3) was isolated from the hot water extract of the red algae Porphyra yezoensis by successive column chromatographies over DEAE-cellulose and Sephadex G-200. PY3 with an average molecular weight of 1.8×10⁵ was demonstrated to be composed of galactose (Gal), 3,6-anhydrogalactose (3,6-AnGal), 6-OSO₃-galactose (6-OSO₃-Gal) and xylose (Xyl) in an approximate molar ratio of 25︰15︰10︰1. In view of Smith degradation and methylation and on the basis of spectral evidence including those of IR, GC, GC-MS, and ¹H and ¹³C NMR, the most probable repeating unit of PY3 could be proposed as [(1→3)β-D-Gal(1→4)α-L-3,6-AnGal]₃-[(1→3)β-D-Gal(1→4)α-L- 6-OSO₃-Gal]₂ with a xylose moiety at the C₆ of one of every twenty-five β-D-Gal residues. To our knowledge, PY3 was shown to be the first porphyran possessing occasional xylose branches.     

Near-infrared to visible up-conversion emissions of Er^3＋ doped Al2O3 powders derived from the sol-gel method

The Er3 doped Al2O3 powders were prepared by the sol-gel method using the aluminium isopropoxide [Al(OC3H7)3]-derived Al2O3 sols with addition of the erbium nitrate [Er(NO3)3.5H2O]. The different phase structure, including three crystalline types of (Al,Er)2O3 phases, γ, θ, α, and two Er-Al-O phases, ErAlO3 and Al10Er6O24, was obtained with the 1 mol% Er3 doped Al2O3 powders at the different sintering temperatures of 600―1200℃. The green and red up-conversion emissions centered at about 523, 545 and 660 nm, corresponding respectively to the 2H11/2, 4S3/2→4I15/2 and 4F9/2→4I15/2 transitions of Er3 , were detected by a 978 nm semiconductor laser diodes excitation. The phase structure and OH content had evident influence on the up-conversion emissions intensity. The maximum intensities of both the green and red emissions were obtained respectively for the Er3 doped Al2O3 powders sintered at 1200 ℃, which was composed mainly of α-(Al,Er)2O3, less of ErAlO3 and Al10Er6O24 phases, and with the least OH content. The two-photon absorption up-conversion process was involved in the green and red up-conversion emissions of the Er3 doped Al2O3 powders.     

金属离子对钢在没食子酸/硫酸介质中的腐蚀行为研究

 用失重法研究了4种金属离子(Na⁺,Zn²⁺,Cu²⁺,Fe³⁺)在0.5 mol/L H₂SO₄以及500 mg/L没食子酸+0.5 mol/L H₂SO₄介质中在20℃对冷轧钢腐蚀行为的影响.结果表明:Cu²⁺对钢的腐蚀起抑制作用;而其余3种金属离子(Na⁺,Zn²⁺,Fe³⁺)对钢的腐蚀起加速作用.在相同条件下,冷轧钢在0.5 mol/L H₂SO₄溶液中的腐蚀速率顺序为:Cu²⁺2++3+;而在500 mg/L没食子酸+0.5 mol/L H₂SO₄介质中,腐蚀速率顺序为:Cu²⁺2+3++.     

Investigation on microwave heating for direct leaching of chalcopyrite ores and concentrates

The use of microwave energy in materials processing is a relatively new development presenting numerous advantages because of the rapid heating feature. Microwave technology has great potential to improve the extraction efficiency of metals in terms of both a reduction in required leaching time and an increase in the recovery of valuable metals. This method is especially pertinent in view of the increased demand for environment-friendly processes. In the present study, the influence of microwave heating on the direct leaching of chalcopyrite ores and concentrates were investigated. The results of microwave leaching experiments were compared with those obtained under conventional conditions. During these processes, parameters such as leaching media, temperature, and time have been worked to determine the optimum conditions for proper copper dissolution. Experimental results show that microwave leaching is more efficient than conventional leaching. The optimum leaching conditions for microwave leaching are the solid-to-liquid ratio of 1:100 g/mL, the temperature of 140℃, the solution of 0.5 M H₂SO₄ + 0.05 M Fe₂(SO₄)₃, and the time of 1 h.     

Preparation of metal oxide doped ACNFs and their adsorption performance for low concentration SO2

Metal oxide （TiO2 or Co304） doped activated carbon nanofibers （ACNFs） were prepared by electrospinning. These nanofibers were characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, and Brunner- Emmett-Teller method （BET）. The results show that the average diameters of ACNFs were within the range of 200-500 nm, and the lengths were several tens of micrometers. The specific surface areas were 1146.7 m2/g for TiO2-doped ACNFs and 1238.5 m2/g for Co304-doped ACNFs, respectively. The electrospun nanofibers were used for adsorption of low concentration sulfur dioxide （SO2）. The results showed that the adsorption rates of these ACNFs increased with an increase in SO2concentration. When the SO2 concentration was 1.0 μg/mL, the adsorption rates of TiO2-doped ACNFs and Co3Oa-doped ACNFs were 66.2% and 67.1%, respectively. The adsorption rate also increased as the adsorption time increased. When the adsorption time was 40 min, the adsorption rates were 67.6% and 69.0% for TiO2-doped ACNFs and Co304-doped ACNFs, respectively. The adsorption rate decreased as the adsorption temperature increased below 60℃, while it increased as the adsorption temperature increased to more than 60℃.     

Dual regulatory effects of resveratrol on activation of NF-κB and cell proliferation in human embryonal kidney 293 cells

Resveratrol (3,4‘,5-trihydroxystilbene, Res), a naturally occurring polyphenol, exhibits antioxidant, antiinflammatory, potential chemopreventive and chemotherapeutic properties in preclinical studies. To further understand its potential clinical efficacy and safety, effect of Res at 10^-9-10^-4 mol/L on human embryonal kidney (HEK293) cell proliferation and its potential mechanism were investigated in present study. Cell viability was detected by using trypan blue dye exclusion method. Cell cycle and apoptosis were analyzed by flow cytometry with propidium iodide stain.Activation of nuclear factor-κB (NF-κB) was determined by luciferase reporter gene assay using stably transfected HEK293/κB-luc cells. Secretion of human interleukin-8(hlL-8) was measured by ELISA. Our results show that HEK293 cell proliferation was significantly stimulated by 10^-7 mol/L Res after treatment for 48 hours, or by 10^-8-10^-7mol/L Res combinated with 10 ng/mL TNFα for 24 h, but was suppressed by 10^-4 mol/L Res with or without TNFα. Both endogenous and TNFα-induced NF-κB activation were downregulated by Res at 10^-7 mol/L, but were upregulated at 10^-4 mol/L. With 10^-4 mol/L Res, the content of secreted IL-8 was increased, and apoptosis rate was increased from lessthan 5 % to 10%, together with significant cell-cycle arrest in S phase. TNFα has coordinative effects with Res on HEK293 cell apoptosis, cell-cycle arrest and IL-8 secretion. These results indicate that Res promotes cell proliferation at low concentration through down-regulation of NF-κB activation in HEK293, but suppresses its growth at high concentration through up-regulation of NF-κB activation, increasing IL-8 and cell-cycle arrest. As resveratrol has dual regulatory effect on cell proliferation in vitro, comprehensive evaluation of its potential clinical utility is needed.     

高灵敏度的硫酸根离子选择性电极

以2-氨基口白啶与SO₂^-4缔合物为电活性物质，以邻苯二甲酸二丁酯(DBP)为增塑剂，制作PVC膜硫酸根离子选择性电极.实验结果表明，电极对硫酸根离子具有良好的选择性和较高的灵敏度，其线性响应范围为5.0×10^-7～1.0×10^-1mol·L^-1.用该电极测定水中的硫酸根离子含量，结果令人满意.     

Spectrofluorimetric method for the determination of triamcinolone acetonide

0　IntroductionTriamcinoloneAcetonide,9 fluoro 11β,2 1 dihydroxy 16α,17[(1 methylethylidene)bis (oxy) ] pregn 1,4 diene 3,2 0 dione,Mris 4 34.4 8(abr.TA ) .Itbelongstoaclassofadrenalcortexhormonedrug ,whosefunctionsareaffectionofsugarmetabolism ,anti inflammationandresistancehypersusceptibilityetc.TAcanbesuitabletorheumatoidarthritisanddermatosissuchashypersusceptibilityandneuropathicdermatitis .ThefunctionsofTAisstrongerandlongerthantriamcinolone[1 ,2 ] .ThecommonmethodsofdetectingTAm…     

Doping effect on thermoelectric properties of nonstoichiometric AgSbTe<Subscript>2</Subscript> compounds

Nonstoichiometric ternary thermoelectric materials Ag_0.84Sb_1.15M_0.01Te_2.16 (M=Ce, Yb, Cu) were prepared by a direct melt-quench and hot press process. The carrier concentration of all the samples increased after doping. Thermoelectric properties, namely electrical conductivity, Seebeck coefficient, and thermal conductivity, were measured from 300 to 673 K. The phase transition occurring at about 418 K representing the phase transition from β-Ag₂Te to α-Ag₂Te influenced the electrical transport properties. The electrical conductivities of Ce and Yb doped samples increased after doping from 1.9×10⁴ to 2.5×10⁴ and 2.3×10⁴ S·m⁻¹, respectively, at 673 K. Also, at room temperature, the Seebeck coefficient of the Ce doped sample relatively increased corresponding to the high carrier concentration due to the changes in the band structure. However, all the thermal conductivities increased after doping at low temperature. Because of the higher thermal conductivity, the dimensionless figure of merit ZT of these doped samples has not been improved.     

Effect of substrate miscut on the electron mobility in InSb（001） structures on Ge and Ge-on-insulator substrates

InSb epilayers and InSb/Al0.20In0.80Sb quantum wells were grown on Ge(001)substrates and Ge-on-insulator(GeOI)-on-Si(001)substrates by molecular beam epitaxy.Growth on both on-axis and 4°-off-axis substrate orientations was studied.Anti-phase domains were formed when InSb films were grown on on-axis substrates,but suppressed significantly by the use of 4°-off-axis substrates.Such off-axis substrates also reduced the densities of micro-twin defects and threading dislocations.The defect reduction resulted in an increase in the room-temperature electron mobility from 37,000 to 59,000 cm2/Vs in 4.0-lm-thick InSb epilayers and from 10,000 to20,000 cm2/Vs in 25-nm-thick InSb quantum wells on Ge(001)and GeOI-on-Si(001)substrates.     

Simulation experiments on the reaction system of CH4-MgSO4-H2O

H2S-rich gas in carbonate reservoirs is usually attributed to thermochemical sulfate reduction （TSR）. In this paper, thermal simulation experiments on the reaction system of CH4-MgSO4-H2O were carried out using autoclave at 425℃--525℃. The threshold temperature for initiating TSR is much lower than our previous studies （550℃）. Properties of the reaction products were analyzed by microcoulometry, gas-chromatography （GC）, Fourier transform-infrared spectrometry （FT-IR） and X-ray diffraction （XRD） methods. Thermodynamics and reaction kinetics of TSR processes were investigated on the basis of the experimental data. The results show that thermochemical reduction of magnesium sulfate with methane can proceed spontaneously to produce magnesium oxide, hydrogen sulfur, and carbon dioxide as the main products, and high temperature is thermodynamically favorable to the reaction. Ac- cording to the reaction model, the calculated activation energy of TSR is 101.894 kJ/mol, which is lower than that by most previous studies. Mg^2＋ may have played a role of catalytic action in the process of TSR. The elementary steps of TSR and reaction mechanism were discussed tentatively. The study can provide important information on the explanation of geochemical depth limit for natural gas and on the generation of high H2S gas in deep carbonates reservoirs.