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Hydrochloric Acid (hydrochloric + acid)
Selected AbstractsChemInform Abstract: Effect of Hydrochloric Acid on the Reductive Amination of 1-(3-Nitropyridin-2-yl)pyridinium Salts.CHEMINFORM, Issue 4 2008R. S. Begunov Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] FS02.8 Patch testing with gold trichloride can give false test resultsCONTACT DERMATITIS, Issue 3 2004Birgitta Gruvberger Background:, Hydrochloric acid is formed in water solutions of gold trichloride. Hydrochloric acid in contact with aluminium generates hydrogen gas which can reduce and transform trivalent gold to elemental gold. Objective:, To investigate whether patch testing with aqueous gold trichloride can cause false positive (irritant) reactions in patients without contact allergy to gold and false negative reactions in patients with gold allergy. Methods:, 13 patients with and 13 patients without positive patch test reactions to gold sodium thiosulfate were tested with gold trichloride in 2 different vehicles, water and alkaline buffer, using 2 different test techniques, the Finn Chamber technique with aluminium chambers and van der Bend technique with polypropene chambers. Results:, Irritant patch test reactions were obtained with aqueous gold trichloride tested in van der Bend chambers in 10 patients without gold allergy. In gold-allergic patients no positive test reactions were obtained from aqueous gold trichloride in Finn chambers while 2 positive test reactions were obtained from gold trichloride in alkaline buffer tested in van der Bend chambers. Conclusion:, If gold trichloride is patch tested in wrong vehicle and with wrong test technique irritant test reactions may occur which can be misinterpreted as positive allergic reactions in patients without gold allergy as well as negative reactions in patients with gold allergy. [source] Reproducible protein analysis by CE using linear polyacrylamide-coated capillaries and hydrochloric acid rinsingELECTROPHORESIS, Issue 13 2007Adhitasari Suratman Abstract Hydrochloric acid was investigated as a rinsing reagent to remove adsorbed proteins from linear polyacrylamide-coated capillaries for electrophoresis. Three model proteins were used, namely cytochrome c as a basic protein, ,-lactoglobulin as an acidic protein, and ,-casein as a more easily denaturing protein. In order to regenerate capillary surfaces, they have been rinsed for 5,min with 2,M hydrochloric acid, 5,min with water, and then 30,min with buffer after every tenth run. It was found important to perform this regeneration procedure on time. The obtained results show good repeatability of the apparent EOF mobility with percentage RSDs below 3% (n,=,60) in various cases. These good results were mainly confirmed in long-term series with more than 200 runs each. Only very high concentrations (175,,M) of ,-lactoglobulin and ,-casein at pH,3.5 gave RSD% values above 5%. For these conditions, the further test of 85% m/m phosphoric acid as rinsing reagent showed a good repeatability of the apparent EOF mobilities as well. [source] Removal of heavy metals from municipal solid waste incineration (MSWI) fly ash by traditional and microwave acid extractionJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 9 2010Jun Xue Abstract BACKGROUND: Municipal solid waste incinerator (MSWI) fly ash is regarded as hazardous waste because it contains various toxic metals. A previous study has shown that fly ash can be detoxified by removal of heavy metals. In this work, the extractability of heavy metals from MSWI fly ash by traditional and microwave acid extraction were compared. RESULTS: A 24 , 1 fractional factorial experimental design was adopted using acid concentration, extraction time, temperature, and liquid/solid (L/S) ratio as the experimental factors for traditional extraction, and acid concentration, extraction time, liquid/solid (L/S) ratio and microwave power as the experimental factors for microwave extraction. The traditional extraction results show that L/S played an important role in Zn, Cd extraction while L/S ratio and extractant concentration were important for Pb extraction. However, no controlling parameter was determined for Cu and Cr extraction. For the microwave extraction, it was shown that L/S was important for Pb and Zn and extractant concentration was important for Pb, Zn and Cd. The time and the power were not significant for the extractability of heavy metals. CONCLUSION: Hydrochloric acid was an effective extractant. Microwave heating promoted extraction and shortened extraction time. Microwave acid extraction treatment is a potentially feasible method for the removal of heavy metals from MSWI fly ash. Copyright © 2010 Society of Chemical Industry [source] Recycling of nickel,metal hydride batteries.JOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 9 2004I: Dissolution, solvent extraction of metals Abstract Nickel,metal hydride batteries contain valuable metallic components and although they are not considered a hazardous waste, recovery of these materials is necessary from an economic point of view. In this work a hydrometallurgical method for the dissolution and separation of the metals from cylindrical nickel,metal hydride rechargeable batteries was investigated. Hydrochloric acid was employed as the leaching agent to dissolve the metals from the batteries. Dissolution of metals was investigated as a function of acid concentration, leaching time and temperature. Suitable conditions for maximum metal dissolution were 3 h leaching with 4.0 mol dm,3 hydrochloric acid solutions at 95 °C. Extraction of 98% of nickel, 100% of cobalt and 99% of rare earth elements was achieved under these conditions. Separation of the rare earths from nickel and cobalt was preliminarily investigated by single batch solvent extraction with 25% bis(2-ethylhexyl)phosphoric acid. Efficient separation via complete extraction of the rare earths was obtained at a pH of approximately 2.5 while leaving nickel and cobalt in the raffinate. A shrinking particle model which can enable, under certain conditions, evaluation of the extent of metal dissolution present in nickel,metal hydride batteries was developed. A proposed electrochemical recovery of nickel and cobalt is also briefly discussed. Copyright © 2004 Society of Chemical Industry [source] Y2O2S:Eu Red Phosphor Powders Coated with SilicaJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 8 2000Jau-Ho Jean Y2O2S:Eu red phosphor powders were coated with silica (SiO2), using sol,gel and heterocoagulation techniques. Phosphor powders were dispersed in ethanol with tetraethyl orthosilicate and water. Hydrochloric acid was used to catalyze the sol,gel reaction, and an amorphous film 10,20 nm thick was observed via transmission electron microscopy (TEM). Colloidal SiO2 powders 10,70 nm in size were used, and the SiO2 powder coating was made by controlling pH values in the range of 4.5,8, in which a negatively charged surface of SiO2 powder and a positively charged surface of red phosphor powder were formed. Then, SiO2 powders were adsorbed electrically onto the phosphor powder surface, as evidenced by TEM, dissolution, and zeta potential measurements. Chemical bonding in the coating was studied using electron spectroscopy for chemical analysis and Fourier transform infrared spectroscopy. [source] Synthesis and characterization of tetraprolinium silicotungstic acid tetra-hydrate, a new organic-inorganic hybrid based on polyoxometallatesCRYSTAL RESEARCH AND TECHNOLOGY, Issue 2 2008M. H. Alizadeh Abstract A new solvated polyoxometallate bearing an amino acid, (I), has been prepared for the first time by the reaction of 0.16 mmol ,-H4SiW12O40.15H2O with 0.78 mmol of L-proline in hydrochloric acid at pH 3. The structure of (I) was substantially characterized by some physical approaches, such as elemental analysis, infrared spectroscopy, and 1H-NMR. Our findings proved that (I) could be formulated as [L-C5H10NO2]4[SiW12O40].4H2O. It is believed that the electrostatic attractions and hydrogen bonding between tungstosilisic acid and the prolinium cation affected the structure of (I). It is evident that the polyoxometallates moieties were arranged in good order to form large holes in the structural backbone. These cavities were occupied by the prolinium cations and water molecules. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Is esophagoscopy necessary for corrosive ingestion in adults?DISEASES OF THE ESOPHAGUS, Issue 8 2009Burcin Celik SUMMARY The aim of the study was to determine whether early esophagoscopy is really necessary for the patients who have ingested a corrosive agent. Patients who were followed up with the diagnosis of corrosive ingestion in our clinic between the years 1998 and 2008 were studied retrospectively. The data were collected through the medical records of the patients and from interviews with them. The analyzed parameters included age, gender, the nature and the amount of the ingested agent, whether the event was accidental or suicidal, diagnostic tools, treatment and the results of the treatment, and long-term follow up. Over a 10-year period, a total of 124 cases of corrosive ingestion cases were determined. Of these, 64 (51.6%) were male and 60 (48.4%) were female. The mean age was 38 ± 17.5 years. The most commonly ingested corrosive agents were sodium hypochlorite in 50 (40.3%) patients and hydrochloric acid in 33 (26.6%) patients. The mean admission time for the emergency department after ingestion of the corrosive agent was 2.5 ± 3.7 hours. Ingestion was accidental in 82% of the patients and as a result of a suicide attempt in 18%. The amount of ingested corrosive agent in the suicidal group (190 ± 208.3 mL) was higher than that of accidental group (66 ± 58.3 mL) (P= 0.012). Nine patients underwent esophagoscopy, six of which were performed in other clinical centers. Only three (2.4%) patients experienced esophageal stricture, which were treated with repeated dilatations. In the long-term follow up, we could get in touch with only 63 patients and none of them had complications due to corrosive ingestion. The follow-up period ranged from 1 to 120 months (median 45 ± 29.2 months). Based on our study, early esophagoscopy appears to be unnecessary in adult patients who ingested the corrosive agent accidentally. A larger prospective study is needed to answer the question. [source] Determination of ethyl glucuronide in human serum by hyphenation of capillary isotachophoresis and zone electrophoresisELECTROPHORESIS, Issue 8 2008Michaela Nováková Abstract The determination of ethyl glucuronide (EtG), a marker of recent alcohol consumption, in human serum by hyphenation of capillary ITP (CITP) and CZE is reported. For CITP step, 1×10,2,M hydrochloric acid adjusted with ,-aminocaproic acid (EACA) to pH,4.4 was used as the leading electrolyte, and 1×10,2,M nicotinic acid with EACA, pH,4.4, was used as the terminating electrolyte (TE). All electrolytes contained 0.2% hydroxypropylcellulose to suppress electroosmosis. In CITP, EtG was separated from fast serum macrocomponents chloride, phosphate, lactate, and acetate. Zones of microcomponents including EtG that migrated between acetate and nicotinate were forwarded to the second capillary filled with a BGE identical with the TE. Conductivity detection was used in the CITP step. Sensitive detection in the CZE step was performed using indirect spectrophotometric detection at 254,nm. The assay is based on a 1:5 dilution of serum with deionized water and has a concentration LOD for EtG in diluted sample of 9.8×10,9,M. The method was used for the determination of EtG in sera of volunteers consuming alcohol. [source] Reproducible protein analysis by CE using linear polyacrylamide-coated capillaries and hydrochloric acid rinsingELECTROPHORESIS, Issue 13 2007Adhitasari Suratman Abstract Hydrochloric acid was investigated as a rinsing reagent to remove adsorbed proteins from linear polyacrylamide-coated capillaries for electrophoresis. Three model proteins were used, namely cytochrome c as a basic protein, ,-lactoglobulin as an acidic protein, and ,-casein as a more easily denaturing protein. In order to regenerate capillary surfaces, they have been rinsed for 5,min with 2,M hydrochloric acid, 5,min with water, and then 30,min with buffer after every tenth run. It was found important to perform this regeneration procedure on time. The obtained results show good repeatability of the apparent EOF mobility with percentage RSDs below 3% (n,=,60) in various cases. These good results were mainly confirmed in long-term series with more than 200 runs each. Only very high concentrations (175,,M) of ,-lactoglobulin and ,-casein at pH,3.5 gave RSD% values above 5%. For these conditions, the further test of 85% m/m phosphoric acid as rinsing reagent showed a good repeatability of the apparent EOF mobilities as well. [source] Poly(methacrylic acid-ethylene glycol dimethacrylate) monolith in-tube solid-phase microextraction applied to simultaneous analysis of some amphetamine derivatives in urine by capillary zone electrophoresisELECTROPHORESIS, Issue 16 2005Fang Wei Abstract A method based on in-tube solid-phase microextraction and capillary zone electrophoresis (CZE) was proposed for simultaneously determining four amphetamines (amphetamine, methamphetamine, 3,4-methylenedioxyamphetamine, and 3,4-methylenedioxymethamphetamine) in urine. A poly(methacrylic acid-ethylene glycol dimethacrylate) monolithic capillary column, which can provide sufficient extraction efficiency, was introduced for the extraction of amphetamines from urine samples. The hydrophobic main chains and acidic pendant groups of the monolithic column make it a superior material for extraction of basic analytes from aqueous matrix. After extraction, the samples were analyzed by CZE. The best separation was achieved using a buffer composed of 0.1,M disodium hydrogen phosphate (adjusted to pH,4.5 with 1,M hydrochloric acid) and 20% methanol v/v, with a temperature and voltage of 25°C and 20,kV, respectively. By applying electrokinetic injection with field-amplified sample stacking, detection limits of 25,34,µg/L were achieved. Excellent method of reproducibility was found over a linear range of 0.1,5,mg/L. Determination of these analytes from abusers' urine sample was also demonstrated. [source] Electrophoretically mediated microanalysis with partial filling technique and indirect or direct detection as a tool for inhibition studies of enzymatic reactionELECTROPHORESIS, Issue 7-8 2004Magdaléna Telnarová Abstract The inhibition of the model enzyme, haloalkane dehalogenase from Sphingomonas paucimobilis, was investigated by a combination of electrophoretically mediated microanalysis with a partial filling technique, followed by indirect or direct detection. In this setup, part of the capillary is filled with a buffer suitable for the enzymatic reaction (20 mM glycine buffer, pH 8.6) whereas the rest of the capillary is filled with the background electrolyte optimal for separation of substrates and products. Two different background electrolytes and corresponding detection approaches were used to show the versatility of the developed method. The inhibition effect of 1,2-dichloroethane on the dehalogenation of brominated substrate 1-bromobutane was studied by means of 10 mM chromate , 0.1 mM cetyltrimethylammonium bromide (pH 9.2) in combination with indirect detection or 20 mM ,-alanine , hydrochloric acid (pH 3.5) in combination with direct detection. The method was used to estimate the inhibition constant KI (0.44 mM by indirect detection and 0.63 mM by of direct detection) and to determine the inhibition type. Compared to spectrophotometric and other discontinuous assays, the method is rapid, can be automated, and requires only small amount of reagents that is especially important in the case of enzymes and inhibitors. [source] Slow desorption behavior of one highly resistant aromatic amine in Lake Macatawa, Michigan, USA, sedimentENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 12 2005Shihua Chen Abstract The desorption behavior of benzidine from Lake Macatawa (Holland, MI, USA) sediment was investigated in this study using batch solvent extraction method. Seven solvents were tested as the extracting reagents: Deionized water (DI), calcium chloride in DI (CaCl2), sodium hydroxide in DI (NaOH), acetonitrile (ACN), a mixture of acetonitrile and ammonium acetate in DI (ACNNH4OAc), methanol (MeOH), and hydrochloric acid in DI (HCl). These solvents are proposed to react with sediment-associated benzidine by different mechanisms (e.g., cation exchange, hydrophobic partitioning, and covalent binding). Three sets of sorption isotherm experiments were conducted separately in these seven solvents with a 7-d, three-week, and two-month contact time. The results demonstrated nonlinear isotherms with Freundlich 1/n values varying from 0.25 to 0.52. The desorption behavior of benzidine in the solvents was evaluated after the sorption of benzidine onto the sediment with same contact times of 7 d, three weeks, and two months. A two-stage model subsequently was applied to simulate the experimental data. The rapidly desorbing rate constants were on the order of one to two per day for ACN, ACN-NH4OAc, and NaOH solvents, and the slowly desorbing rate constants were on the order of 10,5 to 10,4/d. Sequential desorption experiment demonstrated low total extraction efficiency of less than 40%. Both the observed sorption and desorption phenomena suggested that hysteresis and/or mass-transfer limited diffusion may result in the slow desorption behavior observed in this study. [source] Novel Enantioselective Synthesis of Functionalized Pyridylarsanes by a Chiral Palladium Template Promoted Asymmetric Hydroarsanation ReactionEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 27 2009Fengli Liu Abstract The asymmetric hydroarsanation reactions between diphenylarsane and (E)-1-phenyl-3-(pyridin-2-yl)-2-propenone and (E)-1-methyl-3-(pyridin-2-yl)-2-propenoate have been achieved by use of the organopalladium complex containing ortho -metalated (R)-[1-(dimethylamino)ethyl]naphthalene as the chiral reaction template in high regio- and stereoselectivities under mild conditions. Hydroarsanation of (E)-1-phenyl-3-(pyridin-2-yl)-2-propenone with diphenylarsane generated two stereoisomeric products in the ratio of 3:1 as five-membered As,N bidentate chelates on the chiral naphthylamine palladium template. Using the same chiral metal template, the corresponding hydroarsanation reaction with (E)-1-methyl-3-(pyridin-2-yl)-2-propenoate gave only one product as a six-membered As,N bidentate chelate. The naphthylamine auxiliary could be removed chemoselectively by treatment with concentrated hydrochloric acid to form the corresponding optically pure neutral complexes. Subsequent ligands displacement from the palladium using aqueous potassium cyanide generated the optically pure keto- and ester-functionalized chiral pyridylarsane ligands. The absolute configuration and the coordination properties of the pyridylarsanes have been established by single-crystal X-ray analysis.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Comparative Sol,Hydro(Solvo)thermal Synthesis of TiO2 NanocrystalsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 11 2006Xianfeng Yang Abstract Three small inorganic compounds [acetic acid (CH3COOH), nitric acid (HNO3), and hydrochloric acid (HCl)] andfive small organic compounds [n -butyl alcohol (CH3CH2CH2CH2OH), 1,2-propanediol (CH2OHCHOHCH3), propane-1,3-dicarboxylic acid (HOOCCH2COOH), butane-1,4-dicarboxylic acid (HOOCCH2CH2COOH), and ethylenediamine (H2NCH2CH2NH2)] with different donors (Cl,, NO3,, OH, COO,, and NH2) are used respectively and comparatively in different reaction media for tailoring the sol,hydrothermal synthesis of TiO2 nanocrystals at a specific reaction temperature and/or for different reaction times. Both anatase and rutile with a variety of nanostructures such as nanocubes, nanorods, nanoneedles, and their self-assembled nanospheres are selectively grown. Well-defined and crystalline anatase nanocrystals with a narrow size distribution are prepared in the presence of n -butyl alcohol. With the use of HCl, nanoneedles and their assembled nanospheres of phase-pure rutile are obtained under much less drastic conditions, even at 100 °C and for only two hours. The effects of the reaction media, synthesis temperatures, and aging times on the structures and shapes of the products are investigated in detail by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Attack and defence in the gastric epithelium , a delicate balanceEXPERIMENTAL PHYSIOLOGY, Issue 4 2007Rod Dimaline The gastric epithelium is a complex structure formed into tubular branched gastric glands. The glands contain a wide variety of cell types concerned with the secretion of hydrochloric acid, proteases, mucus and a range of signalling molecules. All cell types originate from stem cells in the neck region of the gland, before migrating and differentiating to assume their characteristic positions and functions. Endocrine and local paracrine mediators are of crucial importance for maintaining structural and functional integrity of the epithelium, in the face of a hostile luminal environment. The first such mediator to be recognized, the hormone gastrin, was identified over a century ago and is now established as the major physiological stimulant of gastric acid secretion. Recent studies, including those using mice that overexpress or lack the gastrin gene, suggest a number of previously unrecognized roles for this hormone in the regulation of cellular proliferation, migration and differentiation. This review focuses on the identification of hitherto unsuspected gastrin-regulated genes and discusses the paracrine cascades that contribute to the maintenance of gastric epithelial architecture and secretory function. Helicobacter infection is also considered in cases where it shares targets and signalling mechanisms with gastrin. [source] Determination of Selenium Concentration in Sixty Five Reference Materials for Geochemical Analysis by GFAAS after Separation with Thiol CottonGEOSTANDARDS & GEOANALYTICAL RESEARCH, Issue 2-3 2001Luc Marin sélénium; SAA four graphite; séparation; matériaux géologiques de référence; coton thiol Selenium has been determined in sixty five geological reference materials of different origins by graphite furnace atomic absorption spectrometry. Samples were decomposed with a mixture of nitric and hydrofluoric acids. Selenium was reduced to SeIV with hydrochloric acid, and then fixed and separated from the matrix on thiol cotton. After digestion of the thiol cotton in hot nitric acid, the Se concentration was measured using palladium and magnesium nitrates as a matrix modifier. The limit of determination was 0.02 ,g g,1, the precision of the results (relative standard deviation of 3 to 8 replicates) varied from 2.6 to 17.7% with an average of 7.9% in the range 0.02-42.7 ,g g,1 and was similar to the value obtained for synthetic samples. Our results are in good agreement with available literature values. Le sélénium a été dosé sur 65 standards géochimiques de référence de différentes provenances par spectrométrie d'absorption atomique avec four graphite. Les échantillons ont été mis en solution par une attaque acide HNO3 -HF. Le sélénium a été réduit en SeIV avec de l'acide chlorhydrique, fixé et séparé de la matrice sur du coton thiol. Après décomposition du coton thiol par chauffage avec de l'acide nitrique, les concentrations en sélénium ont été mesurées en utilisant du nitrate de palladium et de magnésium comme modificateur de matrice. La limite de détermination est de 0.02 ,g g,1, la précision des résultats (écart type relatif sur 3 à 8 mesures) pour les standards géochimiques varie de 2.6 à 17.7% avec une moyenne de 7.9% dans la game 0.02-42.7 ,g g,1et est comparable à celle obtenue pour des échantillons synthétiques. Nos résultats sont en bonne concordance avec les résultats déjà publiés dans la littérature. [source] A comparison between clearing and radiographic techniques in the study of the root-canal anatomy of maxillary first and second molarsINTERNATIONAL ENDODONTIC JOURNAL, Issue 5 2004O. E. Omer Abstract Aim, To compare a clearing technique with conventional radiography in studying certain features of the root-canal system of maxillary right first and second molars. A secondary aim was to assess interexaminer agreement for these features using radiographs. Methodology, Eighty-three recently extracted permanent maxillary right first molars and 40 recently extracted maxillary right second molars from an Irish population were included. Standard periapical radiographs were taken from a buccolingual and mesiodistal direction. The specimens were then decoronated, demineralized in 10% hydrochloric acid for 8 days and then cleared using methyl salicylate. The cleared teeth were examined using a dissecting microscope (×20), and data relating to number of roots, canal type following Vertucci's classification, presence of lateral canals, presence of transverse anastomoses and position/number of apical foramina were collected. The radiographs were examined by two independent trained endodontists using an X-ray viewer and a magnifying lens (×2) in a dark room for the same features studied using the clearing technique. Results, The Kappa values for the agreement between the radiographic examiners A and B and the clearing technique and between the two examiners for the number of roots were 0.60, 0.64 and 0.53; for the root-canal type, 0.37, 0.41 and 0.42; for the number of roots with lateral canals, 0.21, 0.18 and 0.14; and for the transverse anastomoses, 0.29 for radiographic Examiner A. Radiographic Examiner B did not feel capable of accurately recognizing transverse anastomoses from the radiographs. For the position/number of apical foramina, the Kappa values were 0.33 and 0.24, respectively. In general, the Kappa values were low to modest for all comparisons. Conclusions, It is concluded that the agreement between the two radiographic examiners and the agreement between either radiographic examiner and the clearing technique were poor to moderate, indicating the limited value of radiographs alone when studying certain aspects of the root-canal system. [source] Kinetics and mechanism of oxidation of aurate(I) by peroxydisulphate in aqueous hydrochloric acidINTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 10 2002R. M. Babshet The reaction between Au(I), generated by reaction of thallium(I) with Au(III), and peroxydisulphate was studied in 5 mol dm,3 hydrochloric acid. The reaction proceeds with the formation of an ion-pair between peroxydisulphate and chloride ion as the Michealis,Menten plot was linear with intercept. The ion-pair thus formed oxidizes AuCl2, in a slow two-electron transfer step without any formation of free radicals. The ion-pair formation constant and the rate constant for the slow step were determined as 113 ± 20 dm,3 mol,1 and 5.0 ± 1.0 × 10,2 dm3 mol,1 s,1, respectively. The reaction was retarded by hydrogen ion, and formation of unreactive protonated form of the reductant, HAuCl2, causes the rate inhibition. From the hydrogen ion dependence of the reaction rate, the protonation constant was calculated to be as 0.6 ± 0.1 dm3 mol,1. The activation parameters were determined and the values support the proposed mechanism. © 2002 Wiley Periodicals, Inc. Int J Chem Kinet 34: 589,594, 2002 [source] Microstructural studies of PMMA impregnated mortarsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2010Priya Nair Abstract Studies on cement concrete microstructures are carried out to explain experimentally observed phenomenon and for modeling of concrete at the macroscopic level. In this article, the preparation of polymer impregnated mortar (PIC) is carried out by partially or fully replacing the pores in the cement mortars (OPC) by PMMA. The effect of this polymer impregnation on density and morphology of the cement matrix is studied. The microstructural changes in the mortar, on exposure of these specimens to hydrochloric acid and sea water for 7 and 28 days, are also investigated in this article. The above studies indicated that the polymer addition decreased the voids in the mortar thereby preventing leaching of water soluble salts present in the OPC. It was observed that the polymer also prevented the external chemical media from permeating into the cement matrix and undergoing interactions with it. It is concluded that the durability and chemical resistance properties of the PIC are better compared with OPC. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Cobalt removal from waste-water by means of supported liquid membranesJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 5 2009Kim Verbeken Abstract BACKGROUND: Supported liquid membranes (SLM) are an alternative technique to remove and recover metals from diluted process solutions and waste-water. In the present work, the removal of Co(II) from a synthetic CoSO4 solution containing initial amounts of cobalt(II) in the range 100,200 ppm (0.1,0.2 g dm,3) has been studied on a pilot scale. By performing batch equilibrium experiments, the optimal settings, i.e. the composition of the organic phase, the pH of the feed, the type and concentration of the stripping agent were determined. RESULTS: It is shown that the equilibrium characteristics of a synergistic extractant mixture containing di-2-ethyl-hexylphosphoric acid (D2EHPA) and 5-dodecylsalicylaldoxime (LIX 860-I) are superior to D2EHPA. Both hydrochloric acid and sulfuric acid have been evaluated as stripping solutions in liquid,liquid extraction tests and as the receiving phase in a SLM configuration. Although equilibrium tests showed no difference in stripping characteristics between both chemicals, it was observed that in a SLM configuration the stability of the system when hydrochloric acid is used is poor. With a commercially available SLM module (Liqui-Cel Extra-Flow 4 × 28) having a surface area of 19 m2, a steady Co(II) flux of 0.140 gm,2h,1 has been obtained at influent concentrations of cobalt between 100 and 200 ppm with 3 mol dm,3 sulfuric acid as stripping phase. CONCLUSIONS: The results obtained show that a supported liquid membrane containing a synergistic mixture of LIX 860-I and D2EHPA gives the possibility of recovering cobalt from dilute solutions. Copyright © 2008 Society of Chemical Industry [source] The use of sodium formate for the recovery of precious metals from acidic base metal effluentsJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 4 2001Herman G Julsing Abstract Zinc was used for the reduction of the platinum group metals (PGMs) in acidic effluents. Due to the increasing cost of zinc, sodium formate was investigated as an alternative reductant. In a base metal-containing acidic effluent, called diethylenetriamine barren, sodium formate was used to precipitate the PGMs. This effluent was the filtrate obtained after a precipitation procedure had been used to remove rhodium and iridium. It was found that pH 1.5 was the optimum starting pH for sodium formate reduction. The pH increased to approximately 4.5 after the addition of sodium formate. The optimum concentration of sodium formate was found to be 30,g,dm,3 at a temperature of 100,°C where the process time was 6,h. Platinum and palladium were the most effectively reduced PGMs, both exhibiting an average precipitation efficiency of greater than 99%. Difficulty was experienced with the precipitation of iridium (average precipitation efficiency of 76%). The precipitated PGMs readily dissolved in hydrochloric acid (6,M) and sodium chlorate (2%). A reduction in costs resulted from the discontinuation of the use of zinc for reduction purposes. An additional advantage was that zinc was no longer introduced into the PGM refinery circuits. © 2001 Society of Chemical Industry [source] Role of Reduced Ionic Strength and Low pH in Gelation of Chicken Breast Muscle ProteinJOURNAL OF FOOD SCIENCE, Issue 1 2005S. Ke And ABSTRACT: Elastic gels with a high moisture content of 88% were prepared at an acidic pH and low ionic strength. The relationship among pH, ionic strength, water-holding capacity, and fold score of gels was investigated. A decrease of pH from 4.1 to 3.7 or below increased gel elasticity and significantly decreased water loss under pressure (P < 0.05). In the presence of sodium chloride, gels made at pH 3.5 to 3.7 had decreased elasticity and increased water loss under pressure. Prior freezing increased the water loss of gels under pressure. Gels made with phosphoric acid and hydrochloric acid lost less water under pressure than those made with citric acid. The percentage loss of water from cylindrical gels was inversely related to the height of the cylinders, suggesting that surface effects were involved. These results suggest that net positive charges on the protein molecules at low pH produced electrostatic repulsion, which was a major driving force for water uptake in the low-salt gels. [source] Characterization of the Products Formed by the Reaction of Trichlorocyanuric Acid with 2-PropanolJOURNAL OF FORENSIC SCIENCES, Issue 6 2009P. Mark L. Sandercock Ph.D. Abstract:, We report a recent investigation into the death of a cat that was initially thought to involve intentionally burning the animal via the use of an ignitable liquid. The exposure of the animal to flame was ruled out. Instead, forensic investigation revealed the intentional mixing together of a common outdoor swimming pool chlorinator, trichlorocyanuric acid (TCCA), and 2-propanol (aka, isopropyl alcohol or rubbing alcohol). The reaction of these two chemicals resulted in the formation of cyanuric acid residue, hydrochloric acid, and the evolution of a significant volume of chlorine gas. Further ,-chlorination side reactions also occurred between 2-propanol and TCCA to produce a variety of chlorinated 2-propanone species that were detected on the submitted evidence. The identification of the products of both the main reaction and the side reactions allowed the authors to determine what chemicals were originally mixed together by the culprit. [source] Protective effect of glucosamine against ibuprofen-induced peptic ulcer in ratsJOURNAL OF GASTROENTEROLOGY AND HEPATOLOGY, Issue 6 2007Sethumadhavan Santhosh Abstract Background:,Helicobacter pylori is the major causative factor of ulcer but the use of ibuprofen and other non-steroidal anti-inflammatory drugs have also been implicated in development of ulcer. The purpose of the present study was to determine the anti-ulcer effect of glucosamine. Methods:, The protective effect of glucosamine on ibuprofen-induced peptic ulcer in male albino rats was studied with respect to changes in the volume of gastric juice, acid output, pepsin activity, activities of membrane bound ATPases, protein content, glycoprotein components and histopathology. Results:, Oral administration of ibuprofen caused significant increase in the number of lesions in the gastric mucosa, increases in the volume of gastric juice and acidity, and decreased activity of pepsin. The levels of protein content and glycoprotein components (hexose, hexosamine and sialic acid) and ATPase activities were also observed. Oral pretreatment with glucosamine resulted in significant reduction in the number of lesions in the gastric mucosa and decreases in the volume of gastric juice and acidity. The pepsin activity was also maintained at near normalcy. Prior oral administration of glucosamine significantly prevented the ibuprofen-induced depletion of protein and glycoprotein components and maintained the activities of membrane bound ATPases as compared to untreated ulcer induced group of rats. Conclusion:, The anti-ulcerogenic activity of glucosamine might be ascribable to its ability to neutralize the hydrochloric acid secreted into the stomach and to its capability to strengthen the mucosal barrier by increasing mucosal glycoprotein synthesis and to its free radical scavenging property. Histopathological investigations of the mucosal tissue also support the anti-ulcerogenic effect of glucosamine. [source] Cyclo-oxygenase-2 inhibitors suppress epithelial cell kinetics and delay gastric wound healing in ratsJOURNAL OF GASTROENTEROLOGY AND HEPATOLOGY, Issue 7 2000Wei-Hao Sun Abstract Background and Aims: The present study examined the effects of NS-398, a specific cyclo-oxygenase-2 inhibitor, on gastric mucosal cell kinetics and gastric wound healing following acid-induced injury. Methods: Male Sprague-Dawley rats were fasted for 24 h and then 0.6 mol/L hydrochloric acid (HCl; 1 mL) was administered into the stomach; NS-398 or indomethacin was administered to the animals 10 min after the acid. Levels of constitutive cyclo-oxygenase (COX-1) and mitogen-inducible cyclo-oxygenase (COX-2) in the gastric mucosa were analysed using western blotting and immunohistochemical staining. The grade of the lesion was assessed using planimetry and histological examination, including immunohistochemistry for proliferating cell nuclear antigen (PCNA). Results: Although there was strong expression of COX-1, there was minimal expression of COX-2 in the gastric mucosa. Expression of COX-2 was enhanced mainly in surface epithelial cells and neck cells following HCl administration. Gastric mucosal ulcers and erosions healed within 48 h, during which time the proliferative zone expanded in the control animals. Indomethacin and NS-398 suppressed the expansion of the proliferative zone and delayed the healing of the gastric injury. Conclusion: The present study demonstrated that cyclo-oxygenase-2 inhibitors delay gastric wound healing by suppressing expansion of the mucosal proliferative zone. These results provide evidence that cyclo-oxygenase-2 has an important role in gastric mucosal regeneration. [source] Preparation of new N6, 9-disubstituted 2-phenyl-adenines and corresponding 8-azaadenines.: A feasibility study for application to solid-phase Synthesis.JOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 4 2004A suitably substituted pyrimidine 1 was converted to a number of title compounds. Nucleophilic substitu tion involving the chlorine atoms in 1 by treatment with phenylmethanethiol yielded 2 or 3, depending on the reaction temperature. Treatment of 3 with an amine afforded 6-phenylmethanesulfanyl-N4 -substituted-2-phenyl-pyrimidine-4,5-diamines 4,7. These pyrimidines were converted into 2-phenylpurines 8,11 and 2-phenyl-8-azapurines 12,14, by treatment with triethyl orthoformate in the presence of hydrochloric acid (or acetic anhydride), or with potassium nitrite and acetic acid respectively. The thioether function on C(6) was then converted into a sulfonyl group by oxidation with m -chloroperoxybenzoic acid affording purines 15,18 and their 8-azaanalogs 19,21; these compounds, as crude products, were treated with an amine to yield the corresponding adenines 22,25 or 8-azaadenines 26,31. All reactions were performed under conditions com patible with the possible use of a thiomethyl resin in place of phenylmethanethiol to bind the pyrimidine ring of 1 to a solid phase. [source] Preparation and structure elucidation of 1,6,9,13-tetraoxadispiro(4.2.4.2)tetradecaneJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 5 2000Bruce Gaede The tricyclic title compound, a symmetrical dispiro oxygen heterocycle, was isolated as a byproduct in the hydrogenation of furfuryl alcohol in the presence of hydrochloric acid. NMR studies and single crystal X-ray analysis have established the relative stereochemistry of the two ketal carbons. Formation of the observed trans stereoisomer under equilibrating conditions is attributed to the anomeric effect. [source] Carbon-14 radiosynthesis of combretastatin A-1 (CA1) and its corresponding phosphate prodrug (CA1P)JOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 14 2009Rodney T. Brown Abstract The natural product combretastatin A-1 (CA1) is isolated from the African bush willow tree, a member of the Combretaceae family. CA1 has important medicinal value, due in part to its ability to inhibit tubulin assembly. The prodrug combretastatin A-1 diphosphate (CA1P; OXi4503) is currently in human Phase I clinical trials as a vascular disrupting agent. This paper describes the carbon-14 radiosynthesis of [4,- 14C]CA1 and the corresponding phosphate prodrug salt [4,- 14C]CA1P in high specific activity (55,mCi/mmol). The carbon-14 label was introduced by methylation of the C-4, protected phenolic moiety of the CA1 precursor following removal of the tert -butyldimethylsilyl protecting group in the presence of [14C]methyl iodide. This was accomplished in excellent yield without significant Z to E isomerization. The [14C]-precursor ((Z)-1-[3,,[4,- 14C],5,-trimethoxyphenyl]-2-[2,,3,-di-[(isopropyl)oxy]-4,-methoxyphenyl] ethene) was subjected to a de- isopropylation reaction with TiCl4. The tetrabenzyl phosphate derivative of the resulting diol was prepared using fresh dibenzyl phosphite. Debenzylation with trimethylsilylbromide, followed by hydrolysis of the trimethylsilyl ester and adjustment of the pH with dilute aqueous hydrochloric acid yielded [4,- 14C]CA1P with an overall radiochemical yield of 8.4%. Copyright © 2009 John Wiley & Sons, Ltd. [source] Determination of BAPTA-AM, the acetoxymethyl tetraester of BAPTA, in rat plasma by liquid chromatography tandem mass spectrometryJOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 12 2006Feng Zheng Abstract BAPTA-AM is the acetoxymethylester of the calcium chelator BAPTA and has demonstrated efficacy in several animal models of cerebral ischemia. This paper describes the development of a method for the determination of BAPTA-AM in rat plasma by liquid chromatography/tandem mass spectrometry. Owing to multiple ester groups in the structure of BAPTA-AM, [M + Na]+ was chosen as the analytical ion for quantification of BAPTA-AM. During the analytical method development, a high percentage of organic solvent and the addition of an amount of sodium acetate and formic acid in the mobile phase were found to favor the sensitivity and reproducibility of [M + Na]+. Poor fragmentation was usually observed in the MS/MS spectra of sodium adduct ions. However, abundant and reproducible fragment ions were observed for the BAPTA-AM sodium adduct ion, and therefore the traditional selective reaction-monitoring mode was used to further improve the sensitivity of MS detection. Because of the lability of the ester bond, a combination of fluoride and hydrochloric acid was applied to minimize the enzymatic hydrolysis, and acetonitrile was chosen to avoid the chemical hydrolysis or solvolysis during the sample collection and preparation procedure. On the basis of these studies, a rapid, sensitive and reproducible method for the determination of BAPTA-AM in rat plasma, using LC/ESI-MS/MS and a simple protein precipitation procedure, was developed and validated. Also, the present method was successfully applied to the determination of BAPTA-AM plasma concentrations for pharmacokinetic studies in rats. Copyright © 2006 John Wiley & Sons, Ltd. [source] | |||||||||||||||||||||||||||||||||||||||||||