Modeling and Transport Analysis of Silver Extraction in Porous Membrane Extractors by Computational Methods

A comprehensive two-dimensional mathematical model was developed for the transport of $ {\text{Ag(CN)}}_{ 2}^{ - } $ ions through porous membrane extractors. Extraction of $ {\text{Ag(CN)}}_{ 2}^{ - } $ with n-heptane solution of N,N-bis(2-ethyl hexyl) guanidine as extractant (LIX79) was investigated theoretically. Simulations were done using computational fluid dynamics of momentum and mass transfer in all subdomains of a hollow-fiber membrane extractor by COMSOL Multiphysics software. The latter uses finite element method for numerical simulations. Parabolic velocity profile was used for the aqueous feed in the tube side and the solvent flow in the shell side that was characterized by Happel’s equation. The distribution of concentration was obtained for the solute in the membrane module. Simulation results indicated that increasing feed flow rate reduces the extraction efficiency of silver from aqueous phase to organic phase. Dimensionless concentration distribution (C/C₀) of silver ions in the tube side of membrane extractor in axial and radial direction shows that it moves to the membrane due to the concentration difference, and then it is swept by the moving extractants in the shell.     

Synthesis, Structure and Bonding Feature of New Metallic Zintl Phases RE 3Cu 3Sb 4(RE=Nd, Sm, Tb, Dy, Ho)

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Demonstration of efficient trichloroethylene biodegradation in a hollow-fiber membrane bioreactor

Rapid cometabolism of trichloroethylene (TCE) by pure cultures of Methylosinus trichosporium OB3b PP358 was demonstrated in a two-stage hollow-fiber membrane bioreactor over the course of 3 weeks. PP358 was grown in a continuous-flow chemostat and circulated through the shell of a hollow-fiber membrane module (HFMM), while TCE contaminated water (160 to 1450 micrograms/L) was pumped through the fiber lumen (fiber interior). In parallel-flow HFMM biological experiments, 82% to 89% of the influent TCE was removed from the lumen (5.1-min residence time) with 99% of the transferred TCE undergoing biodegradation. Biological experiments in a larger capacity baffled radial-flow HFMM resulted in 66% to 99% TCE transferred and 93% to 96% TCE biodegradation at lumen residence times of between 1.5 and 3.7 min. Biodegradation was maintained throughout the experiments at pseudo-first-order biodegradation rate constants of 0.41 to 2.8 L/mg TSS/day. Best-fit computer modeling of the baffled radial-flow biological process estimated mass transfer coefficients as large as 2.7 x 10(-2) cm/min. The computer model was also shown to simulate the experimental results quite well.     

Morphological stability of γ/α interface formed by carburization in Fe-C-X alloys

Effect of alloying elements on the morphological stability of austenite/ferrite interface formed by carburization of Fe-X alloys at 850 °C and 800 °C was investigated. Planar interfaces were found when the alloying elements added were from among the following: Ti, V, Nb, Ta, Cr, Mo, W, Co, and Cu. Nonplanar interfaces with Widmanstätten-like structures and/or an isolated phase were observed when the alloying elements were from the following group: P, Al, Sb, Ni, Mn, Si, and Ge. The degree of supersaturation of C in the α phase adjacent to the γ phase front was analyzed using the concept of local equilibrium. It was confirmed that there was indeed a close correlation between the morphological stability and the degree of C supersaturation, which in itself depended on whether the alloying element added was an α or γ stabilizer and how strongly it bonded with C in the ferrite phase.     

Effects of MO_x(M=Mn,Cu,Sb,La)on V-Mo-Ce/Ti selective catalytic reduction catalysts

A series of MO_x-V_2O_5-MoO_3-CeO_2/TiO_2(M=Mn,Cu,Sb,and La) catalysts were prepared via an impregnation method.The physico-chemical properties of the catalysts were characterized and their NH_3-SCR of NO performance was compared.The Mn-loaded catalyst(Mn5V1Mo3Ce7/Ti) exhibits a large number of acid sites of varying strength,and together with good reducibility of the catalyst,contributes to the optimal SCR performance.The sulphate species formed in the presence of SO_2 significantly enhance the H_2O and SO_2 tolerance of Mn5V1Mo3Ce7/Ti.The Cu-loaded catalyst(Cu5V1Mo3Ce7/Ti)demonstrates potential in flue gas applications in the absence of SO_2 at low temperatures because of the excellent redox ability observed and the high degree of weak acid sites.The Sb and La loaded catalysts(Sb5V1Mo3Ce7/Ti and La5V1Mo3Ce7/Ti),especially La5V1Mo3 Ce7/Ti,exhibit the largest number of acid sites and the lowest reducibility,and therefore,may be suitable for use in high temperature denitrification applications.     

Identification of arsenato antimonates in copper anode slimes

It was found that, in copper electrolyte, the combination of As(V) and Sb(V) can form arsenato antimonic acid (AAAc) and, the reactions of AAAc with As(III), Sb(III), and Bi(III) can produce the precipitates of arsenato antimonates. During copper electrorefining, the As, Sb, and Bi deposited into the anode slime from the electrolyte are dominant in the forms of arsenato antimonates. It is extremely difficult to separate pure arsenato antimonates from copper anode slimes, while it is easy to synthesize arsenato antimonates using H₂O₂ to oxidize As(III) and Sb(III) in copper refining electrolyte. The composition and structure of the arsenato antimonates were determined with chemical analysis, IR and XRD techniques. The characteristic bands in the IR spectra of arsenato antimonates are δ of As–OH and Sb–OH at 1126.8 cm^− 1, ν_as of As–OH at 1029.7 cm^− 1, ν_as of As–OX(X = As, Sb) at 819.5 cm^− 1, ν_as of Sb–OH at 618.4 cm^− 1, ν_as of Sb–OY(Y = As, Sb) at 507.2 cm^− 1, and ν_as of Sb–OBi at 470 cm^− 1.The arsenato antimonates form irregular masses of amorphous structure because there are many OH groups in AAAc, the OH groups bond with As(III), Sb(III), and Bi(III) at random, which makes the arsenato antimonates formed in copper refining electrolyte have no fixed ratios for As/Sb/Bi. The formation of the arsenato antimonates can be expressed as follows:aH₃AsO₄ + bH[Sb(OH)₆] + cMeO ⁺ →Me_cAs_aSb_bO_{(3a+5b+c/2+1)}H_{(a+5b−2c+2)}·xH₂O + cH⁺ + (a + b + c / 2 − 1 − x)H₂O, where Me = As(III), Sb(III) and Bi(III); a ≥ 1, b ≥ 1, c ≤ (3a + b)     

调整价态萃取-陶瓷膜过滤联合除锑制取超高纯氧化铌

萃取分离是制取高纯氧化铌主要方法, 在一定条件下, 可以达到制取高纯氧化铌目的, 但随着原料杂质复杂化, 尤其是难分离杂质Sb的超标, 单纯依靠萃取制取高纯氧化铌变得尤其困难, 需要运用新的方法加以解决Sb超标问题。为此联合运用调整价态萃取与陶瓷膜过滤法, 通过调整价态萃取最大限度降低Sb含量, 再利用Nb与Sb在一定条件下溶解度各不相同原理, 通过特种溶解试剂溶解、陶瓷膜过滤除Sb, 可以最大限度地过滤分离Nb与Sb, 达到制取超高纯氧化铌（ω（Sb）＜5×10-6。即5ppm）的目的。      

Oncogenic mutations in thyroid adenoma: methodological criteria

Pentavalent antimony-mannan (Sb[V]-mannan) was 10-fold more potent than sodium stibogluconate in a murine model of visceral leishmaniasis. Liver antimony concentrations were six-fold higher after Sb[V]-mannan therapy compared with a dose of sodium stibogluconate that was equipotent in reducing liver parasite burdens. Murine toxicity of Sb[V]-mannan was variable, with a 50% lethal dose (LD50) for one preparation that was well above the concentration that killed 90% of the parasites, and for another preparation was only modestly higher than the concentration that killed 90% of the parasites.     

石墨烯/纳米氧化铝修饰电极方波阳极溶出伏安法测定土壤中锑

锑是一种有毒且应用广泛的工业添加剂,但锑是可疑致癌物,对人体及环境生物具有毒性作用,因此锑含量的测定是环境评价的必然要求。实验制备了一种石墨烯/纳米氧化铝复合膜修饰电极,探讨了Sb(III)在该修饰电极上的伏安溶出特性,建立了方波溶出伏安法测定Sb(III)的方法。该复合膜呈疏松多孔结构,具有较大的比表面积和良好的导电性,对Sb(III)具有灵敏的电化学响应。在优化的实验条件下,溶出峰电流与Sb(III)浓度在1.0×10^-7~1.0×10^-5 mol/L范围内呈良好的线性关系,检出限为1×10^-7 mol/L。对某工厂周边土壤样品微波消解处理后,采用方波阳极溶出伏安法测定了锑含量,结果的相对标准偏差(RSD,n=6)为3.1%~3.9%;土壤样品中锑的含量在0.901~1.290mg/kg;与原子吸收光谱法的测量结果进行对比,一致性较好。     

Thermodynamic Simulation of the A<Superscript>III</Superscript>–B<Superscript>V</Superscript> Semiconductor Melts

The equilibrium compositions and the thermodynamic characteristics of binary Ga–Sb, Al–Sb, and In–Sb melts are studied by a thermodynamic simulation using the TERRA software package over wide temperature and composition ranges. The temperature dependences of the partial pressures of the components of the gas phase forming above the III–V (III = Ga, In; V = Sb) semiconductor melts are investigated. The concentration dependences of the component activities and the partial and integral characteristics of melt mixing are obtained. All melts under study are shown to exhibit large negative deviations from Raoult’s law, which is caused by the presence of associates and indicates a strong interaction between the melt components. The temperature dependences of the logarithms and the partial pressures of the gas phase components are obtained. These dependences are shown to be linear for the components of the gas phase forming over the Ga–Sb, Al–Sb, and In–Sb melts.     

Antioxidant status and alpha1-antiproteinase activity in subarachnoid hemorrhage patients

Grafting of polyethylene glycol chains onto cellulosic membrane can be expected to reduce the interaction between blood (plasma protein and cells) and the membrane surface. Alkylether carboxylic acid (PEG acid) grafted high flux cellulosic membranes for hemodialysis, in which the polyethylene glycol chain bears an alkyl group at one side and a carboxyl group at the other side, have been developed and evaluated. PEG acid-grafted high flux cellulosic membranes with various grafting amounts have been compared with respect to platelet adhesion, the contact phase of blood coagulation, and complement activation in vitro. A new method of quantitating platelet adhesion on hollow-fiber membrane surfaces has been developed, which is based on the determination of lactate dehydrogenase (LDH) activity after lysis of the adhered platelets. PEG acid-grafted high flux cellulosic membranes showed reduced platelet adhesion and complement activation effects in grafting amounts of 200 ppm or higher without detecting adverse effects up to grafting amounts of 850 ppm. The platelet adhesion of a PEG acid-grafted cellulosic membrane depends on both the flux and grafting amounts of the membrane. It is concluded that the grafting of PEG acid onto a cellulosic membrane improves its biocompatibility as evaluated in terms of platelet adhesion, complement activation, and thrombogenicity.     

在抗坏血酸存在下正丙醇-碘化钾-硫酸铵体系萃取分离锑（Ⅲ）的研究

研究了在抗坏血酸存在下正丙醇-碘化钾-硫酸铵体系萃取分离和富集Sb（Ⅲ）的行为及与一些金属离子分离的条件。结果表明,硫酸铵能使正丙醇的水溶液分成两相,在分相过程中,Sb（Ⅲ）与碘化钾生成的(SbI4-)与质子化正丙醇(C3H7OH2+)形成的缔合物［SbI4-］［C3H7OH2+］能被正丙醇相完全萃取。当正丙醇、碘化钾和硫酸铵的浓度分别为30%(V/V)、0.40 mol/L、0.20 g/mL时,Sb（Ⅲ）的萃取率达到96.9%以上,Pb（Ⅱ）,Mn（Ⅱ）,Fe （Ⅲ）,Zn（Ⅱ）,Al（Ⅲ）,Cr（Ⅲ）,Ni（Ⅱ）,Cu（Ⅱ）和Mg（Ⅱ）基本不被萃取,实现了Sb（Ⅲ）与上述金属离子的分离。     

An ATP-dependent As(III)-glutathione transport system in membrane vesicles of Leishmania tarentolae

Membrane preparations enriched in plasma membrane vesicles prepared from promastigotes of Leishmania tarentolae were shown to accumulate thiolate derivatives of 73As(III). Free arsenite was transported at a low rate, but rapid accumulation was observed after reaction with reduced glutathione (GSH) conditions that favor the formation of As(GS)3. Accumulation required ATP but not electrochemical energy, indicating that As(GS)3 is transported by an ATP-coupled pump. Pentostam, a Sb(V)-containing drug that is one of the first-line therapeutic agents for treatment of leishmaniasis, inhibited uptake after reaction with GSH. Vesicles prepared from a strain in which both copies of the pgpA genes were disrupted accumulated As(GS)3 at wild-type levels, demonstrating that the PgpA protein is not the As(GS)3 pump. These results have important implications for the mechanism of drug resistance in the trypanosomatidae, suggesting that a plasma membrane As(GS)3 pump catalyzes active extrusion of metal thiolates, including the Pentostam-glutathione conjugate.     

火花放电原子发射光谱法测定轴承钢中残余元素

残余元素含量已成为衡量轴承钢质量的重要指标,因此有必要对轴承钢中残余元素进行监测和控制。通过对试样制备的条件进行优化,建立了用火花放电原子发射光谱法(Spark-AES)对轴承钢中Ca、Ni、Mo、Cu、Nb、V、Ti、As、Sn、Pb、Sb这11种残余元素含量进行测定的方法。结果表明,采用铣样机对试样进行制备,控制铣样总深度为1.0 mm,刀头平移速度为150 mm/min时,测定结果的相对标准偏差相对最小。采用钢光谱标样对设备的准确性进行验证,并通过调整响应曲线修正系统偏差。平行取6块GCr15轴承钢样品,按照实验方法进行制备和分析,各元素测定结果的相对标准偏差(RSD,n=6)均小于5%。采用实验方法分别对6个轴承钢标准物质中Ca、Ni、Mo、Cu、Nb、V、Ti、As、Sn、Pb、Sb进行测定,测定结果与认定值相符。     

铜电解液中锑氧化还原规律及其价态转化途径

以含H2SO4、As、Sb、Bi的酸性溶液为研究体系,采用化学分析及电化学测试,研究了电解液中锑的氧化还原规律及价态转化途径。实验表明,在铜电解液中,溶解的氧气在一定温度下将Sb(III)氧化,其中砷可显著促进Sb(III)的氧化。通过向电解液中加入适量双氧水可实现电解液中锑的氧化,促进砷锑铋的共沉淀反应。电化学测试表明,加入Sb(III)后,阴极过程在-0.13 V出现还原峰,阳极过程在0.03 V出现氧化峰,随着三价锑浓度增加,阳极过程氧化峰电流先增大再减小。加入Sb(V)后,阴极过程在-0.1 V出现还原峰,阳极过程在0.05 V出现氧化峰,随着五价锑浓度的增加,阳极过程峰电流逐渐增大。采用H2O2氧化方法调节电解液中nSb(III)/nSb(V)至1∶4附近,Sb、Bi在一定条件下脱除率分别达到68.2%和83.7%。     

Trypanothione overproduction and resistance to antimonials and arsenicals in Leishmania

Leishmania resistant to arsenicals and antimonials extrude arsenite. Previous results of arsenite uptake into plasma membrane-enriched vesicles suggested that the transported species is a thiol adduct of arsenite. In this paper, we demonstrate that promastigotes of arsenite-resistant Leishmania tarentolae have increased levels of intracellular thiols. High-pressure liquid chromatography of the total thiols showed that a single peak of material was elevated almost 40-fold. The major species in this peak was identified by matrix-assisted laser desorption/ionization mass spectrometry as N1,N8-bis-(glutathionyl)spermidine (trypanothione). The trypanothione adduct of arsenite was effectively transported by the As-thiol pump. No difference in pump activity was observed in wild type and mutants. A model for drug resistance is proposed in which Sb(V)/As(V)-containing compounds, including the antileishmanial drug Pentostam, are reduced intracellularly to Sb(III)/As(III), conjugated to trypanothione, and extruded by the As-thiol pump. The rate-limiting step in resistance is proposed to be formation of the metalloid-thiol pump substrates, so that increased synthesis of trypanothione produces resistance. Increased synthesis of the substrate rather than an increase in the number of pump molecules is a novel mechanism for drug resistance.     

Membrane Bioreactor for Cometabolism of Trichloroethene Air Emissions

Biofilters have been of limited use for cometabolism of chlorinated organic compounds, such as trichloroethene (TCE), due to enzyme inhibition or toxicity effects. A hollow fiber membrane bioreactor was investigated that involves a bundle of polypropylene fibers through which volatile organic compound contaminated air passes. The fibers are immersed in a recirculating nutrient/cosubstrate solution. Batch culture experiments were performed with a mixed culture that could cometabolize TCE with toluene as a primary substrate. No inhibition or inquiry to the toluene degrading ability was observed at up to 15 mg L?1 toluene or up to 1.5 mg L?1 TCE. The culture was inoculated into the hollow-fiber membrane bioreactor. Initially toluene was supplied to the reactor to build a sufficient biomass density on the fibers. After steady-state toluene removal was achieved, TCE was added to the gas phase of the reactor. Toluene was added in three different configurations: (1) As a mixture with TCE in the gas phase; (2) by pulsing into the gas phase; or (3) to the liquid phase. This paper investigates which reactor configuration is most favorable for cometabolism of toluene and TCE.     

火花放电原子发射光谱法测定轴承钢中残余元素

残余元素含量已成为衡量轴承钢质量的重要指标,因此有必要对轴承钢中残余元素进行监测和控制。通过对试样制备的条件进行优化,建立了用火花放电原子发射光谱法(Spark-AES)对轴承钢中Ca、Ni、Mo、Cu、Nb、V、Ti、As、Sn、Pb、Sb这11种残余元素含量进行测定的方法。结果表明,采用铣样机对试样进行制备,控制铣样总深度为1.0 mm,刀头平移速度为150 mm/min时,测定结果的相对标准偏差相对最小。采用钢光谱标样对设备的准确性进行验证,并通过调整响应曲线修正系统偏差。平行取6块GCr15轴承钢样品,按照实验方法进行制备和分析,各元素测定结果的相对标准偏差(RSD,n=6)均小于5%。采用实验方法分别对6个轴承钢标准物质中Ca、Ni、Mo、Cu、Nb、V、Ti、As、Sn、Pb、Sb进行测定,测定结果与认定值相符。     

Neutrophil adhesion molecule expression during cardiopulmonary bypass with bubble and membrane oxygenators

The neutrophil-mediated tissue injury associated with cardiopulmonary bypass (CPB) is thought to require the interaction of specific neutrophil and endothelial adhesion molecules. In this study, the effects of CPB on the expression of neutrophil CD11b and CD18 (the components of the Mac-1 adhesion molecule) were examined; the effects of membrane versus bubble oxygenators on the expression of neutrophil CD11b and CD18 were compared; and the plasma levels of the intercellular adhesion molecule-1 (cICAM-1), an inducible endothelial adhesion molecule, were measured. In addition, the time courses of complement activation and neutrophil granule release were measured to determine their temporal relationship to the expression of the neutrophil adhesion molecule. Fifteen adult patients underwent procedures requiring cardiopulmonary bypass; hollow-fiber membrane oxygenators were used in 8 (group M) and bubble oxygenators were used in 7 (group B). Blood samples were drawn before, during, and after CPB for determination of the expression of neutrophil CD11b and CD18 (immunofluorescent flow cytometry), and the plasma cICAM-1, elastase, lactoferrin (enzyme-linked immunoabsorbent assay), and plasma C3a (radioimmunoassay) levels. CPB caused an immediate and sustained increase in the neutrophil CD11b and CD18 expression in both groups; after 60 minutes of CPB, CD11b expression had increased by 116.9% +/- 19.1% in group B and by 79.3% +/- 8.5% in group M (p = 0.78). Over the same period, CD18 expression increased by 97.2% +/- 17.9% in group B and by 72.4% +/- 16.8% in group M (p = 0.67).(ABSTRACT TRUNCATED AT 250 WORDS)