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Terms modified by Zn Selected AbstractsUtility of fine-needle aspiration cytology in the classification of leprosyDIAGNOSTIC CYTOPATHOLOGY, Issue 5 2001I. Satish Rao M.D. Abstract The role of fine-needle aspiration cytology (FNAC) in the diagnosis of benign skin lesions has been restricted primarily to the evaluation of bacteriologic and morphologic indices in leprosy. This study was undertaken to evaluate the efficacy of FNAC in the diagnosis and classification of lepromatous lesions. Aspirates of 94 newly diagnosed cases of leprosy were studied, and the bacterial load was determined by modified Ziehl-Neelsen (ZN) stain. A skin biopsy was taken from the same site at the same sitting. Frozen and paraffin sections stained with hematoxylin-eosin (H&E) and ZN stains were examined from the biopsy specimen. In 61 of 94 cases (64.9%), the aspirates were satisfactory. Both diagnosis and classification of leprosy were possible in 40 of these 61 cases; the rest of the aspirates showed nonspecific chronic inflammation. The 39 cases of leprosy where a biopsy was available from the same site were classified on FNAC into tuberculoid (TT and BT), lepromatous (LL and BL), and midborderline (BB) subtypes. Taking the histologic diagnosis and Ridley-Jopling classification to be the gold standard, a strong concordance in tuberculoid leprosy cases (18 of 20 cases, 90%) and in lepromatous cases (15 of 16 cases, 93.7%) was observed. Midborderline cases of leprosy posed a problem, and a correct cytohistological correlation was observed in only one of the three cases. Diagn. Cytopathol. 24:317,321, 2001. © 2001 Wiley-Liss, Inc. [source] Airways infection with virulent Mycobacterium tuberculosis delays the influx of dendritic cells and the expression of costimulatory molecules in mediastinal lymph nodesIMMUNOLOGY, Issue 4 2004Gina S. García-Romo Summary Despite tuberculosis resurgence and extensive dendritic cell (DC) research, there are no in vivo studies evaluating DC within regional lymphoid tissue during airways infection with virulent Mycobacterium tuberculosis (Mtb) H37Rv. Using DC-specific antibodies, immunocytochemistry, flow cytometry and Ziehl,Neelsen (ZN) for bacilli staining, we searched for Mtb and DC changes within mediastinal lymph nodes, after intratracheal (ITT) inoculation of virulent Mtb. ZN and immunocytochemistry in frozen and paraffin sections of mediastinal lymph nodes identified Mtb until day 14 after ITT inoculation, associated with CD11c+ and Dec205+ DC. Analysing CD11c, MHC-CII, and Dec205 combinations by flow cytometry in MLN suspensions revealed that CD11c+/MHC-CII+ and CD11c+/Dec205+ DC did not increase until day 14, peaked on day 21, and sharply declined by day 28. No changes were seen in control, saline-inoculated animals. The costimulatory molecules evaluated in CD11c+ DCs followed a similar trend; the CD80 increase was negligible, slightly surpassed by CD40. CD86 increased earlier and the three markers peaked at day 21, declining by day 28. While antigen-specific proliferation was not evident for MLN CD4+ T cells at 2 weeks postinfection, delayed-type hypersensitivity responses upon ITT inoculation revealed that, as early as day 3 and 7, both the priming and peripheral systemic immune responses were clearly established, persisting until days 14,21. While airways infection with virulent Mtb triggers an early, systemic peripheral response maintained for three weeks, this seems dissociated from regional events within mediastinal lymph nodes, such as antigen-specific T-cell reactivity and a delay in the influx and local activation of DC. [source] Diagnosis of tuberculosis: Available technologies, limitations, and possibilitiesJOURNAL OF CLINICAL LABORATORY ANALYSIS, Issue 5 2003Sanjay K. Garg Abstract Rapid diagnosis and treatment are important for preventing transmission of Mycobacterium tuberculosis. However, the diagnosis of tuberculosis continues to pose serious problems, mainly because of difficulties in differentiating between patients with active tuberculosis and those with healed lesions, normal mycobacterium boris BCG (Bacillus Calmette Guerin) vaccinated individuals, and unvaccinated Manteux positives. Physicians still rely on conventional methods such as Ziehl-Neelsen (ZN) staining, fluorochrome staining, sputum culture, gastric lavage, and other non-traditional methods. Although the tuberculin test has aided in the diagnosis of tuberculosis for more than 85 years, its interpretation is difficult because sensitization with nontuberculous mycobacteria leads to false-positive tests. There have been numerous unsuccessful attempts to develop clinically useful serodiagnostic kits for tuberculosis. A number of proteinaceous and nonprotein antigens (such as acyltrehaloses and phenolglycolipids) have been explored from time to time for the development of such assays but they have not proved to be clinically useful. It has been difficult to develop an ELISA utilizing a suitable antigen because M. tuberculosis shares a large number of antigenic proteins with other microorganisms that may or may not be pathogenic. With the advent of molecular biology techniques, there have been significant advances in nucleic acid-based amplification and hybridization, which are helping to rectify existing flaws in the diagnosis of tuberculosis. The detection of mycobacterial DNA in clinical samples by polymerase chain reaction (PCR) is a promising approach for the rapid diagnosis of tuberculous infection. However, the PCR results must be corrected for the presence of inhibitors as well as for DNA contamination. In the modern era of genetics, marked by proteomics and genomics, the day is not far off when DNA chip-based hybridization assays will instantly reveal mycobacterial infections. J. Clin. Lab. Anal. 17: 155,163, 2003. © 2003 Wiley-Liss, Inc. [source] Modified immunohistological staining allows detection of Ziehl,Neelsen-negative Mycobacterium tuberculosis organisms and their precise localization in human tissueTHE JOURNAL OF PATHOLOGY, Issue 5 2005Timo Ulrichs Abstract The diagnosis of mycobacterial infection depends on the Ziehl,Neelsen (ZN) stain, which detects mycobacteria because of their characteristic acid-fast cell wall composition and structure. The histological diagnosis of tuberculosis (TB) comprises various aspects: (1) sensitive detection of mycobacteria; (2) precise localization of mycobacteria in the context of granulomatous lesions; (3) ,staging' of disease according to mycobacterial spread and granulomatous tissue integrity. Thus, detection of minute numbers of acid-fast bacteria in tissue specimens is critical. The conventional ZN stain fails to identify mycobacteria in numbers less than 104 per ml. Hence many infections evade diagnosis. PCR is highly sensitive, but allows neither localization within tissues nor staging of mycobacterial disease, and positive findings frequently do not correlate with disease. In this study, an anti- Mycobacterium bovis bacille Calmette,Guérin polyclonal antiserum (pAbBCG) was used to improve immunostaining, which was compared to the ZN stain in histological samples. Screening of tissue samples including lungs, pleural lesions, lymph nodes, bone marrow, and skin for mycobacterial infection revealed that pAbBCG staining detects infected macrophages harbouring intracellular mycobacteria or mycobacterial material as well as free mycobacteria that are present at low abundance and not detected by the ZN stain. The positive pAbBCG staining results were confirmed either by PCR analysis of microdissected stained tissue or by culture from tissue. This immunostaining approach allows precise localization of the pathogen in infected tissue. Copyright © 2005 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd. [source] Transformation of a zinc inclusion complex to wurtzite ZnS microflowers under solvothermal conditionsCRYSTAL RESEARCH AND TECHNOLOGY, Issue 9 2010Liwei Mi Abstract Wurtzite zinc sulfide (ZnS) microflowers were synthesized successfully by a convenient solvothermal route in ethylene glycol (EG) and ethylenediamine (EN) using thiourea and zinc inclusion complex as starting materials. The inclusion complex {[Zn(bipy)2(H2O)2](4-Cl-3-NH2 -C6H3SO3)2(bipy) (H2O)2}n was achieved by the reaction of zinc oxide (ZnO) and 4-Cl-3-NH2 -C6H3SO3 with the bridging ligand bipy under moderate conditions, in which bipy is 4,4,-bipyridine and 4-Cl-3-NH2C6H3SO3NH is 4-Chloro-3-aminobenzene sulfonic acid. The phase purity of bulk products was confirmed by powder X-ray diffraction and element analysis. The factors that might affect the purity of the ZnS product during the synthesis were discussed in detail. It was found that the products were significantly affected by the mixed solvents and the starting materials. X-ray single crystal diffraction, scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDS), and X-ray diffraction (XRD) were used to characterize the products. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] A theory for elastic properties of single crystals with microstructure and its application to diffusion induced segregationCRYSTAL RESEARCH AND TECHNOLOGY, Issue 9 2008T. Blesgen Abstract In this article a general theory for elastically stressed single crystals in the presence of microstructure is presented and an explicit formula for the resulting non-linear stored mechanical energy is obtained. The optimal microstructure under applied stress is characterised and the optimal laminates are identified in 2D. The analysis is based on a sharp lower estimate of the energy that relies on relaxation. The new theory is then used to extend existing models for diffusion induced segregation (DIS) in the case of (Zn,Fe)S single crystals. Numerical simulations based on finite elements are carried out and the results are compared with former computations of the homogeneous case. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Synthesis and crystal strcucture of two zinc inclusion complexesCRYSTAL RESEARCH AND TECHNOLOGY, Issue 8 2008Min-Le Han Abstract X-ray single crystals of these two inclusion complexes, [Zn(H2O)4L2]·(4-amino-1-naphthalene sulfonate)2 (L = 1,3-bis(4-pyridyl) propane), 1, and [Zn(H2O)(bipy)2]·(4-amino-1-naphthalene sulfonate)(NO3) (bipy = 4,4'-bipyridine), 2 were achieved by the reaction of Zn(NO3)2 and 4-amino-1-naphthalene sulfonate to 1,3-bis(4-pyridyl) propane and 4,4'-bipyridine, respectively. As inclusion complexes, the cationic components of 1 and 2 were formed by two infinite zigzag chains, while, 4-amino-1-naphthalene sulfonate made up the anionic parts of these two complexes. Thus, the whole molecules of these two complexes are neuter. Numous hydrogen bonds could be found in these two inclusion complexes, which help them to form three-dimensional solid-state packing structure architectures. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Growth and properties of an organometallic nonlinear optical crystal: bis(isothiocyanato)-bis(4-methylpyridine)zinc(II) (Zn(SCN)2(C6H7N)2)CRYSTAL RESEARCH AND TECHNOLOGY, Issue 12 2006L. Y. Zhu Abstract Bis(isothiocyanato)-bis(4-methylpyridine)zinc(II)(Zn(SCN)2(C6H7N)2), (abbreviated as ZBNC) single crystals of optical quality have been grown from acetone solution by the slow temperature-lowering method. Its solubilities at different temperatures in acetone were measured. The X-ray powder diffraction (XRPD) spectroscopy of ZBNC crystal was performed at room temperature. The second harmonic generation (SHG) efficiency was determined by powder technique of Kurtz and Perry using Nd:YAG laser, which is equivalent to KDP crystal. The thermal decomposition process was characterized by thermal gravity and differential thermal analysis (TG\DTA). The specific heat of the crystal is 1440.67 J/mol·K at 325 K. The IR spectrum was recorded in the 500,3500 cm,1 region, using KBr pellets on a Nicolet 170sx FT-IR spectrometer. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Growth and characterisation of Zn:LiNbO3/Mg:LiNbO3 multilayer thin films grown by liquid phase epitaxyCRYSTAL RESEARCH AND TECHNOLOGY, Issue 9 2006H. J. Lee Abstract 1, 3 and 5 mol% ZnO doped LiNbO3 film and 2 mol% MgO doped LiNbO3 multilayer films were grown on the LiNbO3 (001) substrate by liquid phase epitaxy (LPE) method with a Li2O-V2O5 system. We examined the optical transmission spectra of the Zn:LiNbO3 by Fourier Transform-Infrared Spectrophotometer (FT-IR). The crystallinity and the lattice mismatch between the Zn:LiNbO3 film and Mg:LiNbO3 film was confirmed by x-ray rocking curve (XRC) and observed the ZnO and MgO distribution in the cross-section of the multilayer thin films by electron probe micro analyzer (EPMA). Furthermore, the surface morphology of the films was observed using atomic force microscopy (AFM). (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Synthesis and X-ray structure of two conformational isomers of [Zn(medpt)(SCN)2], medpt = bis (3 , aminopropyl)methylamineCRYSTAL RESEARCH AND TECHNOLOGY, Issue 2 2006S. Guha Abstract Two conformational isomers of [Zn (medpt)(NCS)2], medpt=bis(3-aminopropyl) methylamine, (1) and (2) have been synthesised and the crystal structures are determined using single crystal X-ray diffraction. The structures of the complexes have been solved by Patterson method and refined by full-matrix least- squares techniques to R1 = 0.0524 for (1) and R1 = 0.0506 for (2), respectively. The geometry around the Zn(II) centre in both isomers is distorted trigonal bipyramidal. The two pendent thiocyanate moieties in (1), with Zn,N,C angles 167.9(4),173.9(4)º, coordinate the mental centre almost linearly while the corresponding coordinations in (2) are significantly bent [Zn,N,C angles 150.8(3),153.1(2)°]. Intermolecular N,H,S hydrogen bonds stabilise the crystal packing in the complexes forming infinite chains parallel to the [100] direction. The combinations of molecular chains generate three/two dimensional supramolecular framework in complexes (1) and (2). (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Investigation of semi-insulating InP co-doped with Ti and various acceptors for use in X-ray detectionCRYSTAL RESEARCH AND TECHNOLOGY, Issue 4-5 2005K. Zdansky Abstract Semi-insulating InP single crystals co-doped with Zn and Ti and co-doped with Ti and Mn were grown by Czochralski technique. Wafers of these crystals were annealed for a long time at a high temperature and cooled slowly. The samples were characterized by temperature dependent resistivity and Hall coefficient measurements. The binding energies of Ti in semi-insulating InP co-doped with Ti and Zn and co-doped with Ti and Mn were found to differ which shows that Ti may occupy different sites in InP. The curves of Hall coefficient vs. reciprocal temperature deviate from straight lines at low temperatures due to electron and hole mixed conductance. The value of resistivity of the annealed semi-insulating InP co-doped with Ti and Mn reaches high resistivity at a reduced temperature easily achievable by thermo-electric devices which could make this material useable in X-ray detection. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Diffusion induced segregation in the case of the ternary system sphalerite, chalcopyrite and cubaniteCRYSTAL RESEARCH AND TECHNOLOGY, Issue 11 2004T. Blesgen Abstract A mathematical model for describing natural and experimental diffusion induced segregation (DIS) in the case of a (Zn,Fe)S single crystal with three coexisting phases is derived. As main result, a new and quite general segregation principle for ternary systems is discovered where one phase has a flat free energy density and serves as catalyst for the segregation of the other two phases. The model includes also a stochastic noise term to represent fluctuations of the copper concentration. Numerical simulations in 2-d underline the physical significance of the model and allow to make quantitative predictions. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Beyond macronutrients: element variability and multielement stoichiometry in freshwater invertebratesECOLOGY LETTERS, Issue 12 2006Roxanne Karimi Abstract We contrasted concentrations of macronutrients (C, N and P), essential (As, Cu, Zn and Se) and non-essential metals (Pb, Hg and Cd) in invertebrates across five lakes and June to October in one lake. We predicted that somatic concentrations of tightly regulated elements would be less variable than weakly and unregulated elements. Within each taxon, variation was lowest in macronutrients, intermediate in essential micronutrients, and highest in non-essential metals, which corresponded in rank to homeostatic regulation strength for the same elements calculated from the literature. Hence, homeostatic regulation may strongly influence variation in element concentrations of biota in situ. Of the individual elements, only taxonomic differences in C and N were consistent across lakes and over a season. Nevertheless, canonical discriminant analyses successfully discriminated among taxa based on taxonomic multielement composition. Thus, relative taxonomic differences in multielement composition appear more informative than absolute stoichiometric formulae when considering the role of inherently variable trace elements in ecological investigations. [source] Simultaneous Determination of Trace Zinc(II) and Cadmium(II) by Differential Pulse Anodic Stripping Voltammetry Using a MWCNTs,NaDBS Modified Stannum Film ElectrodeELECTROANALYSIS, Issue 23 2009Qing Tian Abstract A multiwalled carbon nanotubes,sodium dodecyl benzene sulfonate (MWCNTs,NaDBS) modified stannum film electrode was employed for the determination of cadmium(II) and zinc(II). The Sn/MWCNTs-NaDBS film electrode was prepared by applying MWCNTs,NaDBS suspension to the surface of the GCE, while the Sn film was plated in situ simultaneously with the target metal ions. Under optimal conditions, linear calibration curves were obtained in a range of 5.0 ,100.0,,g L,1 with detection limits of 0.9,,g L,1 for zinc(II) and 0.8,,g L,1 for cadmium(II), respectively. This film electrode was successfully applied to the determination of Zn(II) and Cd(II) in tap water sample. [source] A Study of Nafion-Coated Bismuth-Film Electrode for the Determination of Zinc, Lead, and Cadmium in Blood SamplesELECTROANALYSIS, Issue 21 2008Benzhi Liu Abstract In this article a sensitive differential pulse stripping voltammetry technique on Nafion-coated bismuth-film electrode (NCBFE) was studied for the simultaneous determination of zinc, cadmium, and lead ions in blood samples at ultra trace levels. The measurement results were in excellent agreement with those obtained from atomic absorption spectroscopy. Various operational parameters were investigated and discussed in terms of their effect on the measurement signals. Under optimal conditions, calibration curves for the simultaneous determination of zinc, cadmium, and lead ions were achieved, based on three times the standard deviation of the baseline, the limits of detection were 0.09,,g L,1 for Cd(II), 0.13,,g L,1 for Pb(II), and 0.97,,g L,1 for Zn(II) respectively. [source] Zinc Oxide/Zinc Hexacyanoferrate Hybrid Film-Modified Electrodes for Guanine DetectionELECTROANALYSIS, Issue 18 2007Hung-Wei Chu Abstract An electroactive polynuclear hybrid films of zinc oxide and zinc hexacyanoferrate (ZnO/ZnHCF) have been deposited on electrode surfaces from H2SO4 solution containing Zn(NO3)2 and K3[Fe(CN)6] by repetitive potential cycling method. Simultaneous cyclic voltammetry and electrochemical quartz crystal microbalance (EQCM) measurements demonstrate the steady growth of hybrid film. There are two redox couples present in the voltammograms of hybrid film and it is obvious in the case of pH,2. Surface morphology of hybrid film was investigated using scanning electron microscopy (SEM) and atomic force microscopy (AFM). Energy dispersive spectrometer (EDS) data confirm existence of zinc oxide in the hybrid film. The effect of type of monovalent cations on the redox behavior of resulting film was investigated. In pure supporting electrolyte, electrochemical responses of modified electrode resemble with that of a surface immobilized redox couple. The electrocatalytic activity of ZnO/ZnHCF hybrid film was investigated towards guanine using cyclic voltammetry and rotating disc electrode (RDE) techniques. Finally, feasibility of using ZnO/ZnHCF hybrid film-coated electrodes for guanine estimation in flow injection analysis (FIA) was also investigated. [source] Electrocatalysis and Amperometric Detection of the Reduced Form of Nicotinamide Adenine Dinucleotide at Toluidine Blue/Zinc Oxide Coated ElectrodesELECTROANALYSIS, Issue 18 2007Ashok Kumar Abstract Thin toluidine blue (TBO) and zinc oxide (ZnO) hybrid films have been grown on glassy carbon electrode (GCE) and indium tin oxide coated (SnO2) glass electrodes by using cyclic voltammetry (CV). Scanning electron microscopy (SEM) images revealed spherical and beads-like shape of highly oriented TBO/ZnO hybrid films. Energy dispersive spectrometry (EDS) results declared that the films composed mainly of Zn and O. Moreover, TBO/ZnO hybrid films modified electrode is electrochemically active, dye molecules were not easily leached out from the ZnO matrix and the hybrid films can be considered for potential applications as sensor for amperometric determination of reduced nicotinamide adenine dinucleotide (NADH) at 0.0,V. A linear correlation between electrocatalytic current and NADH concentration was found to be in the range between 25,,M and 100,,M in phosphate buffer. In addition, we observed that dopamine, ascorbic acid and uric acid are not interference in amperometric detection of NADH in this proposed method. In addition, TBO/ZnO hybrid film modified electrode was highly stable and its response to the NADH also remained relentless. [source] Electrochemical Investigation of Heavy Metal Ion Transfer Across the Water/1,2-Dichloroethane Interface Assisted by 9-Ethyl-3-Carbazolecarboxaldehyde-ThiosemicarbazoneELECTROANALYSIS, Issue 12 2007Haluk Bingol Abstract The transfer of heavy metal ions across the polarized water/1,2-dichloroethane (1,2-DCE) interface assisted by 9-ethyl-3-carbazolecarboxaldehyde-thiosemicarbazone (ECCAT) in the 1,2-DCE phase has been studied by cyclic voltammetry. Voltammetric waves of Pb(II) and Cd(II) ions were reversible and quasi-reversible, respectively, whereas that of Hg(II) and Zn(II) ion were irreversible. The voltammogram of Cu(II) ion showed a two-step wave, however the nature of the transfer could not be satisfactorily evaluated by analyzing the cyclic voltammetric data. When Ni(II) and Co(II) was used no peak was visible under the experimental conditions used in this study. The dependence of the half-wave potentials of Pb(II) and Cd(II) ions on the ligand concentration reveals that their ion-transfer is assisted by the formation of 1:3 metal-ECCAT complex in 1,2-DCE. The over-all association constants of [Pb(ECCAT)3]2+ and [Cd(ECCAT)3]2+ complexes in DCE-phase have been determined to be log ,=14.03 and log ,=15.44, respectively. [source] Complex Formation in the Region of Metal Hydrolysis and M(OH)2 Precipitation.ELECTROANALYSIS, Issue 7 2006(AMPSO)x, (OH)y, (OH)y Systems, A Glass Electrode Potentiometric, Polarographic Study of Cd Abstract The interaction between cadmium or zinc and AMPSO was investigated by DCP and GEP, at fixed total ligand to total metal concentration ratios and various pH values, at 25.0,°C and 0.1,M KNO3 ionic strength. For Cd,(AMPSO)x,(OH)y system, CdL and CdL(OH) species, were identified, with stability constants values set to (as log,,): 2.1±0.1 and 6.2±0.2, respectively. For Zn,(AMPSO)x,(OH)y system, the proposed final model with stability constants set to (as log,,) is: ZnL=2.5±0.1 and ZnL(OH)2=12.9±0.2. For both systems, the fact that AMPSO deprotonation occurs in the metal hydrolysis and M(OH)2 precipitation and the complexes formed are not too strong added a real challenge to data interpretation. [source] A Study of Heavy Metal Complexation in Grape JuiceELECTROANALYSIS, Issue 5-6 2005Íñigo Salinas Abstract Differential pulse anodic stripping voltammetry, DPASV, has been used to monitor the initial stages of grape juice fermentation, focusing on Zn interactions with natural occurring ligands. Langmuir and Scatchard linearization methods have been employed. A 1,:,1 ratio has been found by either method; from Langmuir data analysis only one ligand population was found, while Scatchard approach gave rise to the detection of two ligand types. Both data analysis procedures led to the same total ligand concentration. When catechin was used as model ligand, a 1,:,1 ratio was found for Zn and also for Cu. [source] Heavy Metals in Matrices of Food Interest: Sequential Voltammetric Determination at Trace and Ultratrace Level of Copper, Lead, Cadmium, Zinc, Arsenic, Selenium, Manganese and Iron in MealsELECTROANALYSIS, Issue 18 2004Clinio Locatelli Abstract The voltammetric methods are very suitable and versatile techniques for the simultaneous metal determination in complex matrices. The present work, regarding the sequential determination of Cu(II), Pb(II), Cd(II), Zn(II) by square-wave anodic stripping voltammetry (SWASV), As(III), Se(IV) by square-wave cathodic stripping voltammetry (SWCSV) and Mn(II), Fe(III) by square-wave voltammetry (SWV) in matrices involved in foods and food chain as wholemeal, wheat and maize meal, are an interesting example of the possibility to sequentially determine each single element in real samples. Besides the set up of the analytical method, particular attention is aimed either at the problem of possible signal interference or to show that, using the peak area Ap as instrumental datum, it is possible to achieve lower limits of detection. The analytical procedure was verified by the analysis of the standard reference materials: Wholemeal BCR-CRM 189, Wheat Flour NIST-SRM 1567a and Rice Flour NIST-SRM 1568a. Precision, as repeatability, and accuracy, expressed as relative standard deviation and relative error, respectively, were lower than 6% in all cases. In the presence of reciprocal interference, the standard addition method considerably improved the resolution of the voltammetric technique. Once set up on the standard reference materials, the analytical procedure was transferred and applied to commercial meals sampled on market for sale. A critical comparison with spectroscopic measurements is also discussed. [source] Selective Electrochemical Analysis of Various Metal Ions at an EDTA Bonded Conducting Polymer Modified ElectrodeELECTROANALYSIS, Issue 16 2004Aminur Rahman Abstract An EDTA-bonded conducting polymer modified electrode was prepared and characterized by FT-IR. The modified electrode was used for the selective electrochemical analysis of various trace metal ions such as, Cu(II), Hg(II), Pb(II), Co(II), Ni(II), Fe(II), Cd(II), and Zn(II) at the different pHs by linear sweep and square wave voltammetry. Dynamic ranges were obtained using square wave voltammetry from 0.1,,M to 10.0,,M for Co(II), Ni(II), Cd(II), Fe(II), and Zn(II) and 0.5,nM to 20,nM for Cu(II), Hg(II), and Pb(II) after 10,min of preconcentration. The detection limits were determined to be 0.1,nM, 0.3,nM, 0.4,nM, 50.0,nM, 60.0,nM, 65.0,nM, 80.0,nM, and 90.0,nM for Cu(II), Hg(II), Pb(II), Co(II), Ni(II), Cd(II), Fe(II), and Zn(II), respectively. The technique offers an excellent way for the selective trace determination of various heavy metal ions in a solution. [source] The resistance of metallothionein to proteolytic digestion: An LC-MS/MS analysisELECTROPHORESIS, Issue 16 2007Rongying Wang Abstract Metallothioneins (MTs) are a family of cysteine-rich metalloproteins which strongly bind to heavy metals, such as Cd(II), Zn(II), and Cu(I). Previous works by other group using gel electrophoresis and fluorescence showed MTs were resistant to proteolytic digestion by a variety of enzymes, raising the difficulties in proteomic identification of MTs. The present work was attempted to analyze the resistance of MTs to trypsin using LC with MS/MS (LC-MS/MS), which was able to determine the sequences of the produced peptides and thus precisely characterize the cleavages. The results showed that metal-saturated MTs were completely resistant to trypsin. This resistance problem could be overcome by the addition of EDTA to MT samples, which rendered MTs readily digested into peptides and identified by MS/MS. Interestingly, the partially metal binding MTs were digested into peptides predominantly with miss cleavages which were well dependent on the amount of heavy metals bound to MTs. An explanation for these observations was proposed. The potential applications of the MT's resistance to trypsin in isolation and identification of MTs in complex mixtures such as cultured cells was demonstrated. The preliminary data also showed the same proteomic approach of proteolytic digestion followed by MS/MS analysis may provide information on metal binding status of MTs, along with the identification of MTs in a mixture. [source] Treatment of Process Water Containing Heavy Metals with a Two-Stage Electrolysis Procedure in a Membrane Electrolysis CellENGINEERING IN LIFE SCIENCES (ELECTRONIC), Issue 2 2005R. Fischer Abstract The capability of a two-stage electrochemical treatment for the regeneration of acidic heavy-metal containing process water was examined. The process water came from sediment bioleaching and was characterized by a wide spectrum of dissolved metals, a high sulfate content, and a pH of about 3. In the modular laboratory model cell used, the anode chamber and the cathode chamber were separated by a central chamber fitted with an ion exchanger membrane on either side. The experiments were carried out applying a platinum anode and a graphite cathode at a current density of 0.1,A/cm2. The circulation flow of the process water in the batch process amounted to 35,L/h, the electrolysis duration was 5.5,h at maximum and the total electrolysis current was about 1,A. In the first stage, the acidic process water containing metals passed through the cathode chamber. In the second stage, the cathodically pretreated process water was electrolyzed anodically. In the cathode chamber the main load of dissolved Cu, Zn, Cr and Pb was eliminated. The sulfuric acid surplus of 3,4,g/L decreased to about 1,g/L, the pH rose from initially 3.0 to 4,5, but the desired pH of 9,10 was not achieved. Precipitation in the proximity to the cathode evidently takes place at a higher pH than farther away. The dominant process in the anode chamber was the precipitation of amorphous MnO2 owing to the oxidation of dissolved Mn(II). The further depletion of the remaining heavy metals in the cathodically pretreated process water by subsequent anodic treatment was nearly exhaustive, more than 99,% of Cd, Cr, Cu, Mn, Ni, Pb, and Zn were removed from the leachate. The high depletion of heavy metals might be due to both the sorption on MnO2 precipitates and/or basic ferrous sulfate formed anodically, and the migration of metal ions through the cation exchanger membrane via the middle chamber into the cathode chamber. In the anode chamber, the sulfuric acid content increased to 6,7,g/L and the pH sank to 1.7. All heavy metals contained, with the exception of Zn, were removed to levels below the German limits for discharging industrial wastewaters into the receiving water. Moreover, the metal-depleted and acid-enriched process waters could be returned to the leaching process, hence reducing the output of wastewater. The results indicated that heavy metals could be removed from acidic process waters by two-stage electrochemical treatment to a large extent. However, to improve the efficiency of metal removal and to establish the electrochemical treatment in practice, further work is necessary to optimize the operation of the process with respect to current density, energy consumption, discharging of metal precipitates deposited in the electrode chambers and preventing membrane clogging. [source] Diversity of the cadmium-containing carbonic anhydrase in marine diatoms and natural watersENVIRONMENTAL MICROBIOLOGY, Issue 2 2007Haewon Park Summary A recent report of a novel carbonic anhydrase (CDCA1) with Cd as its metal centre in the coastal diatom Thalassiosira weissflogii has led us to search for the occurrence of this Cd enzyme (CDCA) in other marine phytoplankton and in the environment. Using degenerate primers designed from the published sequences from T. weissflogii and a putative sequence in the genome of Thalassiosira pseudonana, we show that CDCA is widespread in diatom species and ubiquitous in the environment. All detected genes share more than 64% amino acid identity with the CDCA of T. pseudonana. Analysis of the amino acid sequence of CDCA shows that the putative Cd binding site resembles that of beta-class carbonic anhydrases (CAs). The prevalence of CAs in diatoms that presumably contain Cd at their active site probably reflects the very low concentration of Zn in the marine environment and the difficulty in acquiring inorganic carbon for photosynthesis. The cdca primers developed in this study should be useful for detecting cdca genes in the field, and studying the conditions under which they are expressed. [source] Zeolite synthesis employing alkaline waste effluents from the aluminum industryENVIRONMENTAL PROGRESS & SUSTAINABLE ENERGY, Issue 2 2002A. La Iglesia Zeolites 4A, 13X, Y, and HZSM5 have been synthesized from alkaline residues from aluminum finishing plants. These residues could contain concentrations of sodium aluminate and sodium hydroxide between 200 and 300 Kg/m3, and small concentrations of heavy metal cations (Cd, Co, Cr, Cu, Mn, and Zn). These contaminants make handling and disposal of these residues difficult. However, the physicochemical properties of the synthesized zeolites (cation exchange capacity of 3 mmol g,1, specific surface area between 600,900 m2g,1, particle size distribution between 0.5,2 ,m and whiteness of 97%) make them useful as detergents and catalysts. Analysis of the chemical composition of the raw materials and the reaction products demonstrates that the heavy metal cation content in the synthesized zeolites is low enough to allow their industrial use (lower than that of the original residues). Therefore, the production of various types of zeolites for industrial use could be used for the elimination of these residues from the aluminum industry. [source] Adsorbing colloid flotation for removal of metal ions in waters from base metal minesENVIRONMENTAL PROGRESS & SUSTAINABLE ENERGY, Issue 1 2002H. Sabti Adsorbing Colloid Flotation (ACF) has been shown in laboratory experiments to be effective for the removal of heavy metals (Zn, Cu, Cd and Pb) from dilute solutions. Sodium dodecyl sulphate (SDS) and sodium oleate (NaOl) were used as surfactants in single or mixed form, with Fe(OH)3 as a flocculant for colloid formation. These reagents worked best for zinc and copper ions for a feed concentration of 50 parts per million (ppm). The removal of lead improved significantly by the use of Fe(OH)3 and NaLS (Sodium lauryl sulphate), while the best removal of cadmium was achieved by the use of Al(OH)3 and HTMABr (hexadecyltrimethylammonium bromide). Flotation experiments were conducted with feed concentrations of 50 and 500 parts per billion (ppb) and 50 ppm (parts per million). The experimental results showed that the residual concentration of metal ions decreased significantly with the decrease in the feed concentration. This could be the effect of excessive (much more than stoichiometric ratio) amounts of surfactant and flocculant, compared to the feed concentrations, required in the effective flotation of dilute feed solutions. The surfactant concentration and feed pH had the largest effects on the process, as observed in the case of cadmium removal. This can be attributed to the flocformation and flotation tendencies of the colloid-metal complexes at various solution pH and surfactant concentrations. The ACF method was applied to a number of natural drainage solutions from the metal mines at Te Aroha, New Zealand, and the experimental results demonstrate that significant removal is achieved for most of the heavy metals. [source] Assessment of sediment quality of Yangtze River estuary using zebrafish (Danio rerio) embryosENVIRONMENTAL TOXICOLOGY, Issue 3 2010Lingling Wu Abstract Yangtze River estuary is one of the largest estuaries worldwide. In this study, the sediment quality of Yangtze River estuary was evaluated using zebrafish (Danio rerio) embryos. Freshly fertilized zebrafish eggs (2 h after fertilization) were exposed to the whole sediment and its organic phase of extract, respectively. The parameters, including survival rate, abnormality, hatching rate, and heart rate of the zebrafish embryos, were recorded during the 96-h exposure. The results demonstrated that the concentrations of heavy metals (Zn, Cu, Cd, Ni, Cr, and As) and low-molecular weight PAHs (Fluorene) in the sediment of Yangtze River estuary exceeded their corresponding effects range low values. The maximum concentrations of Zn and Fluorene in the sediment samples were 239.6 ,g/g and 45.9 ng/g, respectively. In both whole sediment test and organic extract test, the survival rate and heart rate of zebrafish embryos were reduced, as well as abnormalities and delayed hatching were induced. For example, the highest mortality of the embryos was 39% in the whole sediment exposure. Overall, the occurrence of toxic compounds in the sediment of Yangtze River estuary may have potentially teratogenic effect on biota. The sediment from the upstream of Yangtze River estuary have more observed toxic effects on zebrafish embryos than that form the downstream. Therefore, more attention should be paid to control these pollutants, especially heavy metals in the Yangtze River estuary. © 2009 Wiley Periodicals, Inc. Environ Toxicol, 2010. [source] Bioconcentrations of metals (Fe, Cu, Zn, Pb) in earthworms (Eisenia fetida), inoculated in municipal sewage sludge: Do earthworms pose a possible risk of terrestrial food chain contamination?ENVIRONMENTAL TOXICOLOGY, Issue 1 2009Surindra Suthar Abstract Efforts have been made to evaluate the possible risks of metal bioaccumulation in composting earthworms during vermicomposting of hazardous wastes, e.g., sewage sludge. The sewage sludge was diluted by mixing cow dung in different proportions, and vermicomposted sludge as well as inoculated earthworms were analyzed for metal (Fe, Cu, Zn, Pb) contents. The sludge processed by worms showed a significant reduction in concentration of metals, Cu (29.4,51.6%), Fe (13.1,19.9%), Zn (15.2,25.8%), and Pb (4.6,46.9%), at the end. A considerable concentration of metals, total Cu (16.7,27.6 mg kg,1), total Fe (42.9,89.8 mg kg,1), total Zn (5.85,75.0 mg kg,1), and total Pb (1.79,12.4 mg kg,1), in composting earthworms was also recorded. The greater values of bioconcentration factors for metals suggested the possible risk of entering contaminants in higher food chains; since, earthworms are near to the terrestrial food chain, they can potentially mediate metal transfer from soil to a range of predators, including birds. Therefore, feasibility of vermitechnology in hazardous waste recycling needs close attention in respect to possible risk of environmental contamination. © 2008 Wiley Periodicals, Inc. Environ Toxicol, 2009. [source] Effects of amendments of N, P, Fe on phytoextraction of Cd, Pb, Cu, and Zn in soil of Zhangshi by mustard, cabbage, and sugar beetENVIRONMENTAL TOXICOLOGY, Issue 6 2007Lina Sun Abstract Soil contaminated with Cd, Pb, Cu, and Zn in the Zhangshi irrigation area is very hard to be remediated. Phytoextraction is considered as an efficient method to remove these toxic metals from soil. In the present study, three vegetables including sugar beet (Beta vulgaris), mustard (Brassica juncea L.), and cabbage (Brassica oleracea L. var. capitata Linn.) were used to bioaccumulate heavy metals in soil through pots experiment for 90 days; and nutrient elements were applied to stimulate the phytoextraction of metals. Results of bioconcentration factors (BCF) and translocation factors (TF) from this study showed that these plants could phytoextract heavy metals, but the accumulation and translocation of metals differed with species of plants, categories of heavy metals, and some environmental conditions (e.g. nutrients). Meanwhile, the addition of nutrient elements, such as N, P, and Fe, could affect the phytoremediation of heavy metals via promoting the normal metabolism of vegetables or changing forms of metals. Results of this study could provide some available information for in-site bioremediation of soil from Zhangshi irrigation area. © 2007 Wiley Periodicals, Inc. Environ Toxicol 22: 565,571, 2007. [source] | |||||||||||||||||||||||||||||||||||||||||||||||||||||||