Surgical management of late esophageal perforation

A simple and rapid high-performance capillary electrophoresis (HPCE) method for the determination of 2-mercaptopyridine-1-oxide (pyrithione) was developed. After addition of ethylenediaminetetraacetic acid (EDTA), pyrithione was determined in the form of the free anion using 50 mM borate (pH 9.2) as background electrolyte and was detected at 244 nm with a limit of detection (LOD) of 0.636 ppm (S/N = 3). The method was used to check the purity of pyrithione preparations and for the determination of pyrithione in shampoo.     

EDTA掩蔽-络合物吸附催化波极谱法测定锌电解液中钴

在丁二酮肟(DMG)和亚硝酸钠存在的氨水-氯化铵缓冲介质中,以EDTA作掩蔽剂,建立了测定锌电解液中钴的络合物吸附催化波极谱法。探究了掩蔽剂EDTA用量的选择,结果表明:所需EDTA的量与溶液中锌的含量有关,当EDTA与锌的物质的量比n_EDTA/n_Zn为1.15时为最佳选择,此时可消除锌电解液中高浓度锌及其他共存杂质金属离子对测定痕量钴的干扰。对底液酸度、氨水-氯化铵缓冲液用量、丁二酮肟乙醇溶液用量和亚硝酸钠溶液用量,以及静置时间等进行了优化。结果表明,在优化的实验条件下,钴的浓度分别在5.0×10^-11~5.0×10^-9和5.0×10^-9~3.2×10^-7mol/L范围内时与其对应的二阶导数波峰电流I_p(nA)呈良好的线性关系,相关系数分别为0.9980和为0.9997,方法检出限为2.0×10^-12mol/L。将实验方法应用于中性上清夜、锌电解新液和除钴后液等实际样品分析,测定值与国标方法GB/T 223.22—1994(亚硝基R盐分光光度法,NRS)比较,相对误差(RE)在±4.5%范围内,相对标准偏差(RSD,n=6)不大于2.7%。方法线性范围宽,对锌电解液中钴的测定具有很高选择性,适用于湿法冶金过程控制分析。     

EDTA络合滴定法测定铁矿石中钙和镁

在微氨性溶液中,采用硫化钠及铜试剂使铜、铅、锌、铁、钴、镍、锰、铬、镉、铋等生成硫化物沉淀和铜试剂内络盐沉淀与钙镁分离,然后以盐酸羟胺将微量的锰还原成低价消除其干扰,用三乙醇胺和L-半胱氨酸掩蔽残留的其他金属离子。在pH10氨水-氯化铵缓冲溶液中,以酸性铬蓝K-萘酚绿B为指示剂,用EDTA络合滴定法测定钙、镁合量;另在氢氧化钾溶液中,用钙试剂为指示剂,以EDTA络合滴定法测定钙量,用差减法计算镁的含量。该方法对铁矿石标准样品中的钙和镁进行多次测定,结果与认定值相符,相对标准偏差在0.99%~3.4%(n=6)之间,加标回收率在98%~101%之间。     

Enhanced Electrokinetic Remediation of Heavy Metals in Glacial Till Soils Using Different Electrolyte Solutions

Previous electrokinetic remediation studies involving the geochemical characterization of heavy metals in high acid buffering soils, such as glacial till soil, revealed significant hexavalent chromium migration towards the anode. The migration of cationic contaminants, such as nickel and cadmium, towards the cathode was insignificant due to their precipitation under the high pH conditions that result when the soil has a high acid buffering capacity. Therefore the present laboratory study was undertaken to investigate the performance of different electrolyte (or purging) solutions, which were introduced to either dissolve the metal precipitates and/or form soluble metal complexes. Tests were conducted on a glacial till soil that was spiked with Cr(VI), Ni(II), and Cd(II) in concentrations of 1,000, 500, and 250 mg/kg, respectively, under the application of a 1.0 VDC/cm voltage gradient. The electrolyte solutions tested were 0.1M EDTA (ethylenediaminetetraacetic acid), 1.0M acetic acid, 1.0M citric acid, 0.1M NaCl/0.1M EDTA, and 0.05M sulfuric acid/0.5M sulfuric acid. The results showed that 46–82% of the Cr(VI) was removed from the soil, depending on the purging solution used. The highest removal of Ni(II) and Cd(II) was 48 and 26%, respectively, and this removal was achieved using 1.0M acetic acid. Although cationic contaminant removal was low, the use of 0.1M NaCl as an anode purging solution and 0.1M EDTA as a cathode purging solution resulted in significant contaminant migration towards the soil regions adjacent to the electrodes. Compared to low buffering capacity soils, such as kaolin, the removal of heavy metals from the glacial till soil was low, and this was attributed to the more complex composition of glacial till. Overall, this study showed that the selection of the purging solutions for the enhanced removal of heavy metals from soils should be primarily based upon the contaminant characteristics and the soil composition.     

A study of different analytical extraction methods for nondetrital heavy metals in aquatic sediments

4.0 N HNO3-0.7 N HCl, 0.5 N HCl, 1 N hydroxylamine hydrochloride-25% acetic acid and 0.05 N EDTA were investiagted as extractants of nondetrital heavy metals from the sediments of the Rideau River. A comparison of these partial extraction methods with a total extraction method, showed that the 4.0 N HNO3-0.7 N HCl attacks the silicate crystal lattice considerably. 1 N hydroxylamine hydrochloride-25% acetic acid was found to be unsuitable for copper extraction. Both of the other two methods were suitable for the simultaneous extraction of Cd, Cu, Pb, Zn, Ni, Cr, Co, Mn, Fe, and Al from the organic adsorbed and precipitated phases of sediments. They both gave a measure of nondetrital heavy metals in sediments and are thus useful to environmental contamination studies.     

Studies on the leaching of an arsenic–uranium ore

Preliminary leaching studies were carried out to develop a suitable method for the recovery of uranium and the elimination of arsenic from a low grade carbonate/silicate ore containing 64 ppm U and 2446 ppm As, as well as some Cu, Pb, Ni and Zn. An examination of the mineralogy found mostly uranium(VI) minerals, such as uraninite, and various base metal sulfides and arsenates in veins and fissures. Roasting the ore at 500–800 °C to volatilize arsenic proved to be unsuitable. Therefore, the ground ore was subjected to direct leaching with sulfuric acid, sodium sulfide and ferric chloride at 80–90 °C with a liquid to solid ratio of 1:1. With sulfuric acid at a concentration of 180 kg/t ore, complete recovery of both uranium and arsenic was achieved giving undesirable arsenic in the leach liquor. The maximum recovery of uranium and arsenic by leaching with sodium sulfide was only 20% and 18%, respectively. However, 3 M ferric chloride leached approximately 92% U(VI) and precipitated arsenic as ferric arsenate. Therefore, maximum uranium can be extracted and arsenic eliminated as impurity by selective leaching with ferric chloride.     

Electrolytic Treatment of Azo Dye Wastewaters: Impact of Matrix Chloride Content

Direct Red 83 (10?μM) was electrolytically treated with a graphite anode paired with a stainless steel cathode at 0.05?mA/mm2. Electrolyte composition was varied from 0 to 0.05?N sodium chloride in increments of 0.01?N, using sodium sulfate as a makeup salt to keep the total electrolyte strength at 0.05?N. Fraction of dye remaining was plotted versus time, and first order curves were fitted to the data. Apparent first order rate constants ranged from 3.96×10?5 to 1.24×10?3?s?1. Both direct oxidation by applied current and indirect oxidation by electrolytically formed chemical species were responsible for color removal. The rate of indirect oxidation was slower than the rate of chlorinated oxidizing species production above 0.01?N sodium chloride concentration. Decolorization rate increased with increasing chloride concentration to a rate-limited point occurring at 0.04?N sodium chloride in the system studied.     

EDTA滴定法测定铝灰中金属铝

铝灰是炼钢重要辅助材料之一,不仅能吸附钢水夹杂物而提高钢水质量,而且其中的金属铝能起到脱氧作用,从而降低钢中气体含量、减少钢中夹杂、提高钢的洁净度及机械性能。因此,将铝灰中金属铝与三氧化二铝物相分离,准确测定金属铝含量具有重要意义。采用三氯化铁溶液在电磁搅拌下溶解试样,将金属铝和三氧化二铝分离,金属铝以离子形式转入溶液中,强碱分离溶液中铁、锰等干扰元素,用过量的EDTA络合Al³⁺,在pH 4.5~5.5以二甲酚橙为指示剂,用锌标准溶液滴定过量的EDTA后,用F^-置换出与Al³⁺络合的EDTA,再用锌标淮溶液滴定释放出的EDTA,从而计算出金属铝含量。实验表明,通过正交试验,确定了三氯化铁溶液的质量浓度(100g/L)、用量(100mL)、样品质量(0.5000g)、搅拌时间(60min)等溶样条件。结果表明,测得结果的相对标准偏差(RSD,n=8)为0.45%~0.78%;回收率为96%~101%。方法满足金属铝质量分数范围在10%~30%之间的铝灰检测要求。     

bagpipe-Dependent expression of vimar, a novel Armadillo-repeats gene, in Drosophila visceral mesoderm

The combined effect of the bacteriocins nisin (1-2100 IU/ml) and leucocin F10 (1-2100 AU/ml), pH (4.7-6.5), NaCl (0.7-4.5% w/l), ethylene diaminetetraacetic acid disodium salt (EDTA, 0.08-4.72 mmol/l) and inoculum level (10(3)-10(8) cfu/ml) on the survival of a pool of three strains of Listeria monocytogenes in broth was evaluated in three factorial experiments. Several factor combinations were found to prevent growth. Logistic regression analysis of the categorical data (survival/no survival) was used to generate predictive models for the probability of survival in 0.01 ml (P0.01) or 1 ml (P1). Predicted and observed probabilities of survival were not significantly different in 72% and 68.9% of treatments for P0.01 and P1, respectively. Unsafe predictions were obtained in 9.4% and 14.8% of treatments for P0.01 and P1, respectively. Nisin had a major effect on the probability of survival but the addition of leucocin F10 was necessary to prevent the survival of L. monocytogenes. Lower pH values significantly decreased the probability of survival, while NaCl and EDTA had only a minor effect. Doses of bacteriocins > 250 AU/ml, pH < 5.6 and EDTA > 0.2 mmol/l (0.074 g/l) were needed to reliably prevent survival of Listeria monocytogenes.     

The behaviour of lix 63 in the extraction of Cu(II) and Fe(III) from chloride media

Investigation of the extraction of copper from chloride solutions using the commercial Lix reagents has shown that Lix 64N extracts small amounts of chloride whereas Lix 65N does not. The extraction of chloride is due to a minor component of the Lix 64N, the aliphatic α-hydroxyoxime Lix 63. This latter reagent extracts copper as a neutral chlorocomplex, probably of the form CuCl₂ · HCl or CuCl₁ · 2HCl₁ at low pH values and extracts the metal ion directly at higher pH. Under similar conditions iron is apparently extracted as the mono-chloro complex, entering the organic phase as FeCl · Lix₂. Following this behaviour, it appears that, in a solvent extraction operation involving chloride leach solutions, Lix 65N, which exhibits no tendency to extract chloride ions, might be a preferable extractant.     

CyDTA滴定法测定精炼调渣剂中金属铝

提出了用三氯化铁溶解试样、强碱分离CyDTA滴定法测定金属铝的分析方法。试样用三氯化铁溶液溶解,在pH 1～2的溶液中,将金属铝和三氧化二铝分离,金属铝以离子的形式转入溶液中,加入氢氧化钠,金属铝溶于氢氧化钠溶液中,而使铁、锰等干扰元素沉淀,在pH 5～6的溶液中,用CyDTA络合铝,在室温条件下,以二甲酚橙作指示剂,用硝酸铅回滴过量的CyDTA。研究了样品粒度、三氯化铁的浓度及用量、搅拌时间、络合剂、指示剂对测定的影响,确定了三氯化铁溶液浓度和用量为80 g/L和50 mL、搅拌时间为60 min的最佳实验条件。将该法用于测定精炼调渣剂中金属铝,相对标准偏差小于3%,测得结果与EDTA滴定法结果基本一致。     

The leaching of nickeliferous laterite with ferric chloride

Several experiments were conducted to investigate the extraction of nickel from nickeliferous laterite by ferric chloride solutions as a function of pulp density, solution composition, and temperature. Solubility relationships for goethite and nickel laterite in aqueous solution were reviewed in terms of leaching rates and reaction mechanisms. Generally, the amount of nickel extracted increased with temperature, the amount of “free acid,” and ferric chloride concentration; however, the amount was inhibited by ferrous chloride. In this investigation, as much as 96 pct of the available nickel was extracted by ferric chloride solution. Nickel extraction was found to be more dependent on ferric chloride concentration than on the concentration of hydrochloric acid. Mechanistically, nickel extraction occurred by the formation of an intermediate ferric chloride complex, which was then hydrolyzed to hematite.     

Gas-liquid chromatographic determination of azinphos ethyl in human plasma and in mouse plasma, tissue, and fat

A new method for the determination of azinphos ethyl (O,O-diethyl-S-(4-oxo-1,2,3-benzotriazin-3(4H)-ylmethyl) phosphorodithioate) in human plasma and in mouse plasma, tissue, and fat has been developed. The method is based on extraction with benzene or hexane and cleanup of fat and tissue samples by a minicolumn containing Florisil and sodium sulfate. Azinphos ethyl is eluted from the column with 10% acetonitrile in benzene and is concentrated to an appropriate volume for gas-liquid chromatographic analysis, using a 63Ni electron capture detector and a glass column containing 3% OV-1 on Gas-Chrom Q. The method is sensitive to 0.005 ppm in human plasma, 0.01 ppm in mouse plasma, 0.08 ppm in mouse liver, 0.05 ppm in mouse brain, and 0.10 ppm in mouse fat. The limit of detection is 2 pg; mean recoveries ranged from 96 to 98%.     

Gastric carcinoma and thrombotic thrombocytopenic purpura: association with plasma immune complex concentrations

A patient with metastatic adenocarcinoma of the stomach developed microangiopathic haemolytic anaemia, thrombocytopenia, renal insufficiency, and fluctuating neurological abnormalities in association with appreciably raised plasma concentrations of immune complexes. This syndrome, similar to thrombotic thrombocytopenic purpura, occurred while the tumour was in sustained objective remission after successful treatment with fluorouracil, doxorubicin, and mitomycin. Reversal of the syndrome was achieved with plasmapheresis, azathioprine, corticosteroids, and antiplatelet treatment; this response was paralleled by a reduction in immune complex concentration, suggesting an immune aetiology for the syndrome. Antibodies eluted from the immune complexes reacted with 50% of cells from the gastric cancer but less than 10% of cells from normal gastric mucosa. There was no reactivity with either carcinoembryonic antigen or mitomycin. A 17S immune complex reacted with a glycoprotein from the patient's autologous platelets and produced platelet aggregation. It is postulated that reducing the tumour and the pre-existing state of antigen excess by chemotherapy allowed soluble antigen-antibody complexes to form and the syndrome to develop.     

固体氯化铅直接电解提取铅工艺研究

对固体氯化铅直接电解过程进行了研究。实验考察了阴极电流密度、电解温度、盐酸浓度、NaCl浓度、PbCl2质量等因素对电流效率、槽压和沉积物质量的影响。结果表明,当阴极电流密度为200 A/m2,温度为65℃,氯化钠浓度为2 mol/L,盐酸浓度为0.1 mol/L,阴极板上固体氯化铅质量为20 g时,阴极电流效率可达98%以上,槽压控制在2 V左右。     

Use of the bromley equation for the analysis of ionic equilibria in mixed ferric and ferrous chloride solutions at 25 °C

The ionic equilibria in the mixed ferric and ferrous chloride solution were analyzed by considering the complex formation reactions as well as the mass and charge balance equations. The activity coefficients of the ions were calculated using the Bromley equation. The equilibrium constants for the formation of ferrous complexes were determined from the reported thermodynamic data. The interaction parameters of the ferric species were estimated from the reported values of FeCl₃ in an HCl solution. By applying the ionic equilibria, the speciation of the ferric and ferrous species with the composition was obtained. The predicted pH values of the FeCl₃-FeCl₂-HCl-H₂O system agreed well with the measured values at 25 °C in the ionic strength range of up to 9.34 m.     

Diazene--a not so innocent ligand for the binuclear center of cytochrome c oxidase

Diazene reacts rapidly with cytochrome c oxidase to reduce cytochrome a and CuA and to form a charge-transfer complex with ferric cytochrome a3; the diazene may serve to bridge the heme iron of this cytochrome and CuB. The complex is characterized by an intense, optically active absorbance located at 847 nm. A similar band had been observed previously upon reduction of cytochrome oxidase with hydrazine [Markossian, K. A., Paitian, N. A., and Nalbandyan, R. M. (1983) FEBS Lett. 156, 235-238], but it appears that this band is actually due to the diazene produced as a result of the oxidation of the hydrazine that occurs in this process. A similar diazene to iron charge-transfer band is found following the reaction of diazene with ferric horseradish peroxidase and with hemin chloride but not with met-myoglobin.     

N1923-异戊醇对不同浓度盐酸介质中钛的萃取性能研究

研究了N1923-异戊醇对不同浓度盐酸介质中钛的萃取性能,考察了盐酸浓度、预酸化、异戊醇的加入量以及萃取温度、时间、相比和稀释剂对萃钛性能的影响。结果表明:N1923对钛的萃取率随盐酸浓度的增加而提高,当CHCl>8 mol/L时,N1923对钛的萃取率显著提高。N1923-异戊醇对浓盐酸中钛存在协同萃取效应,一次萃取率可达90%以上,但对钛、铁的分离性能较差。     

MgOHCl thermal decomposition kinetics

Experiments to determine the kinetics of the thermal decomposition of MgOHCl were performed. It was found that the decomposition of MgOHCl commenced at 649 K, and it directly converted into MgO and HCl without undergoing any intermediate step. Decomposition vs time data showed that the thermal decomposition of MgOHCl was a first-order process with respect to the amount of MgOHCl remaining, and the mass transfer of the product HCl gas away from the interface was likely the rate-limiting step. It was also found that the time required to completely decompose MgOHCl into MgO, more than 20 minutes, at the operating temperatures of electrolytic magnesium production processes, 600 °C±50 °C, was significantly longer than the time required, less than 1 minute, to digest the solid magnesium chloride containing feed material into the molten salt electrolyte in these processes. Such delay in the decomposition would mean that any MgOHCl produced during heating and digestion of the feed would not be decomposed by the heat of the electrolyte and thus the persistent MgOHCl would dissolve into the molten salt electrolyte with potentially severe negative consequences on electrolysis cell operation.     

Polarographic determination of robenidine residues in chicken tissues, eggs, litter, soil, and plant tissue

Polarographic residue methods have been developed for determining robenidine (Robenz), 1,3-bis[p-chlorobenzylidene)amino]-guanidine monohydrochloride, in chicken tissues, eggs, litter, soil, and plants. The compound is extracted from chicken fat, skin, muscle, liver, and eggs with ethyl acetate; from blood with acetone; from plant tissue, litter, and kidney with acidic acetone; and from soil with basic methanol. After extraction by high-speed blending or overnight shaking, the extract is cleaned up by evaporation, solvent partition and/or elution from CG-50 ion exchange resin. Robenidine is quantitated by differential cathode ray polarography, using acidic aqueous methanol or acetic acid (1+1) supporting electrolyte. Recoveries ranged from 64 to 125% with an average overall recovery of 90%. The validated sensitivity is 0.1 ppm for chicken tissues, soil, and plants, 0.01 ppm for eggs, and 1 ppm for litter.