Nuclear hyperfine interactions in W^(182), W^(183), and Pt^(195) as studies by the Mossbauer effect

The Mössbauer technique has been used to study the nuclear hyperfine interactions and lifetimes in W¹⁸² (2⁺ state) and W¹⁸³ (3/2^- and 5/2^- states) with the following results: g(5/2^-)/g(2⁺) = 1.40 ± 0.04; g(3/2^- = -0.07 ± 0.07; Q(5/2^-)/Q(2⁺) = 0.94 ± 0.04; T_1/2(3/2^-) = 0.184 ± 0.005 nsec; T_1/2(5/2^-) >̰ 0.7 nsec. These quantities are discussed in terms of a rotation-particle interaction in W¹⁸³ due to Coriolis coupling. From the measured quantities and additional information on γ-ray transition intensities magnetic single-particle matrix elements are derived. It is inferred from these that the two effective g-factors, resulting from the Nilsson-model calculation of the single-particle matrix elements for the spin operators ŝ_z and ŝ₊, are not equal, consistent with a proposal of Bochnacki and Ogaza.

The internal magnetic fields at the tungsten nucleus were determined for substitutional solid solutions of tungsten in iron, cobalt, and nickel. With g(2⁺) = 0.24 the results are: |H_eff(W-Fe)| = 715 ± 10 kG; |H_eff(W-Co)| = 360 ± 10 kG; |H_eff(W-Ni)| = 90 ± 25 kG. The electric field gradients at the tungsten nucleus were determined for WS₂ and WO₃. With Q(2⁺) = -1.81b the results are: for WS₂, eq = -(1.86 ± 0.05) 10¹⁸ V/cm²; for WO₃, eq = (1.54 ± 0.04) 10¹⁸ V/cm² and ƞ = 0.63 ± 0.02.

The 5/2^- state of Pt¹⁹⁵ has also been studied with the Mössbauer technique, and the g-factor of this state has been determined to be -0.41 ± 0.03. The following magnetic fields at the Pt nucleus were found: in an Fe lattice, 1.19 ± 0.04 MG; in a Co lattice, 0.86 ± 0.03 MG; and in a Ni lattice, 0.36 ± 0.04 MG. Isomeric shifts have been detected in a number of compounds and alloys and have been interpreted to imply that the mean square radius of the Pt¹⁹⁵ nucleus in the first-excited state is smaller than in the ground state.

Accumulation of Heavy Metals in Franciscanas from Buenos Aires Province, Argentina

Marine mammals accumulate heavy metals in their tissues at different concentrations according to trophic levels and environmental conditions. The franciscana (Pontoporia blainvillei) is a small coastal species inhabiting the marine and estuarine areas of the Southwestern Atlantic Ocean. Its diet includes numerous species of small fish, squid and crustaceans. The aims of this study were to (i) assess the heavy metal concentration and burden distribution in different franciscana age classes and sex, and to (ii) evaluate both the accumulation processes and the transplacental transference of zinc, cadmium, copper and total mercury. Heavy metal concentrations (wet weight) were determined in eighteen dolphins by Atomic Absorption Spectrophotometry (AAS), by the cold vapour technique (mercury) or with air/acetylene flame (cadmium, zinc and copper). Liver showed the highest concentrations of mercury (max. 8.8 mg/g), zinc (max. 29.7 mg/g) and copper (max. 19.0 mg/g), whereas the highest cadmium concentrations (max. 6.7 mg/g) were found in kidney. Adults contained the highest concentrations for all heavy metals, followed by juveniles and calves in decreasing order, suggesting an age-related accumulation. No differences (p<0.05) were found between sexes within each age class. Organ burden distribution followed the same pattern for all metals and age classes: liver tissues contained maximum burdens. Mercury concentrations were higher than those of cadmium in both foetuses and newborns; and neither metal could be detected in the foetus. The analysed data suggested differences in the placental transference between metals, being significant for mercury and almost null in the case of cadmium. We can conclude that franciscana accumulates heavy metals and, due to its coastal distribution, it may be considered as a biomonitor of its environment. SPANISH: Los mamíferos marinos acumulan metales pesados en sus tejidos cuyas concentraciones están en relación con su nivel trófico y las condiciones ambientales. La franciscana (Pontoporia blainvillei) es una especie costera que habita áreas marinas y estuariales en el Atlántico Sudoccidental. Su dieta está constituída por peces, como item alimentario principal, calamares y crustáceos. El objetivo del presente trabajo es estudiar la distribución de metales pesados en diferentes clases de edad y en ambos sexos, evaluando procesos de acumulación y cargas de cadmio, mercurio total, cinc y cobre. Las concentraciones de metales pesados (en peso húmedo) fueron determinadas en dieciocho delfines por Espectrofotometría de Absorción Atómica (EAA), usando la técnica de vapor frío (mercurio) o llama de aire/acetileno (cadmio, cinc y cobre). El hígado presentó las concentraciones más altas de mercurio (máx. 8,8 mg/g), cinc (máx. 29,7 mg/g) y cobre (máx. 19,0 mg/g), mientras que las más altas de cadmio (máx. 6,7 mg/g) fueron encontradas en el riñón. Los adultos presentaron los niveles más altos, presentando los juveniles y cachorros concentraciones menores, lo cual sugirió una acumulación con la edad. No se encontraron diferencias significativas (p < 0,05) entre sexos dentro de cada clase de edad. Las cargas de metales pesados en los órganos presentaron la misma disribución para todos los metales y clases de edad. Los valores más altos fueron encontrados en el hígado, incluyendo los correspondientes a cadmio. Las concentraciones de mercurio y cadmio fueron no detectables en el feto, mientras que las de mercurio fueron superiores a las de cadmio en los cachorros. Los datos encontrados en el feto sugieren una transferencia nula a través de la placenta. Podemos concluir que P.blainvillei acumula metales pesados en sus tejidos y debido a su distribución costera, esta especie puede ser considerada como un biomonitor de su ambiente.

Assessment of contaminant body burdens and histopathology of fish and shellfish species frequently used for subsistence food by Alaskan Native communities

Subsistence food items can be a health concern in rural Alaska because community members often rely on fish and wildlife resources not routinely monitored for persistent bioaccumulative contaminants and pathogens. Subsistence activities are a large part of the traditional culture, as well as a means of providing protein in the diets for Tribal members. In response to the growing concerns among Native communities, contaminant body burden and histopathological condition of chum and sockeye salmon (Oncorhynchus keta and Oncorhynchus nerka) and the shellfish cockles and softshell clams (Clinocardium nuttallii and Mya arenaria) were assessed. In the Spring of 2010, the fish and shellfish were collected from traditional subsistence harvest areas in the vicinity of Nanwalek, Port Graham, and Seldovia, AK, and were analyzed for trace metals and residues of organic contaminants routinely monitored by the NOAA National Status & Trends Program (NS&T). Additionally, the fish and shellfish were histologically characterized for the presence, prevalence and severity of tissue pathology, disease, and parasite infection. The fish and shellfish sampled showed low tissue contamination, and pathologic effects of the parasites and diseases were absent or minimal. Taken together, the results showed that the fish and shellfish were healthy and pose no safety concern for consumption. This study provides reliable chemistry and histopathology information for local resource managers and Alaska Native people regarding subsistence fish and shellfish use and management needs.

Distribution of Cu, Zn, Pb and Cd in some recent molluscan shells from Lake Mariut sediment

Shells and shell fragments were the principal constituents of the core sediment taken from LakeMariut. Their trace metals were studied to assess their contribution to environmental adjustment. The results indicated that the shells of Biomphalaria alexandrina, Mercierella enigmatica and Melanoida tuberculate contain higher amounts of Cu and Zn than the widely distributed shells of Lucina sp. and Cerastoderma edule. The Pb contents found in different types of shells were higher than the other metals. The Cd contents found in different shell types were the most important fraction in comparison to the total Cd in the sediments of the lake. The relationship between the concentrations of trace metals and mineralogical analysis revealed that lead tended to be more concentrated in aragonite than in calcite.

A review on oil sardine 3. Oil and meal industry

The author reviews the advances in the oil and meal industries related to the oil sardine fishery (Sardinella longiceps) since the 1920s. Data on the production of by-produced produced in Kerala over the period 1964- 69 are tabulated. Details of the properties of the commercial oil are given, and the values compared to those for other similar oils. The use of oil sardine for industrial purposes - the oil has been used to cure leather, temper metals and as fungicides or insecticides - and the production of fish meal and fish protein concentrate is considered.

Problems associated with the over protection of fishing trawlers against sea water corrosion and fouling

Some presently used anti-fouling materials contain metals and other compounds, which are toxic in the environment. Coating products are not always stable, and there is a resulting pollution hazard. In particular if surfaces are poorly prepared and manufactures' instructions are not closely followed the application of anti-fouling substances becomes pointless and dangerous. In addition the salinity, constant biological activity and suspended particles make seawater a highly corrosive material in its own right.

Biodiversity and production of bioactive material from cyanobacteria in Persian Gulf

In this project sampling was done from 9 stations in 3 depths during 5 seasons to separate, identify and examine the biodiversity of cyanobacteria. Another sampling also has been done to analyse all physical and physicochemical parameters, primary production and polluting agents such as heavy metals and oil hydrocarbons in water and sediments. Along with optimization of Oscillatoria to study the ability of producing natural substances, these cyanobacteria were analysed from the point of antimicrobial and mutagenic effects. To examine the relationships among analysed parameters, the regression test, analysis of varian and Post Hoc were used. As the result of this study 48 genus of cyanobacteria were pecognised among which 35.5% were croco ccales and 64.4% were Hermogonals. Oscillatoria was one of the Filamentous cyanobacteria which had antibacterial and mutagenic effects. The results of multicommunity consistency varians test, post Hoc and homogenous subsets show significant difference between biodiversity of cyanotbacteria in coral ecosystem, Mangrove and transite. The linear correlation coefficient between biodiversity of cyanobacteria and bioenvironmental agents were examined, but there was no continuous relation between these factors and biological biodiversity. In Surface layer there was a significant correlation coefficent at 0.048 and probability at 95% confidence interval. Also, the biodiversity is depended on oil pollution and heavy metals such as copper (Cu) and chromium (Cr).

Engineering of micro- and nanostructured surfaces with anisotropic geometries and properties

Widespread approaches to fabricate surfaces with robust micro- and nanostructured topographies have been stimulated by opportunities to enhance interface performance by combining physical and chemical effects. In particular, arrays of asymmetric surface features, such as arrays of grooves, inclined pillars, and helical protrusions, have been shown to impart unique anisotropy in properties including wetting, adhesion, thermal and/or electrical conductivity, optical activity, and capability to direct cell growth. These properties are of wide interest for applications including energy conversion, microelectronics, chemical and biological sensing, and bioengineering. However, fabrication of asymmetric surface features often pushes the limits of traditional etching and deposition techniques, making it challenging to produce the desired surfaces in a scalable and cost-effective manner. We review and classify approaches to fabricate arrays of asymmetric 2D and 3D surface features, in polymers, metals, and ceramics. Analytical and empirical relationships among geometries, materials, and surface properties are discussed, especially in the context of the applications mentioned above. Further, opportunities for new fabrication methods that combine lithography with principles of self-assembly are identified, aiming to establish design principles for fabrication of arbitrary 3D surface textures over large areas. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Cloning, characterization, and gene expression analysis of a novel cadmium metallothionein gene in Tetrahymena pigmentosa

A novel cadmium-inducible metallothionein (MT) gene (Tpig-MT1) was cloned and sequenced from the ciliate Tetrahymena pigmentosa. The number of deduced amino acids is 118. The polypeptide possesses CCC and CC clusters characteristic of typical Tetrahymena Cd-inducible MTs. The structure of Tpig-MT1 is different from the reported Cd-MT in T. pyriformis, T. thermophila and T. pigmentosa. Tpig-MT1 contains two intragenic tandem repeats with 72.9% identity described as Tpig-MT1 (repeat A1) and Tpig-MT1 (repeat A2). The transcriptional response of Tpig-MT1 gene to different heavy metals (Cd, Cu, Zn, Hg, Pb) and oxidative stress (H2O2) was measured using real-time quantitative PCR. The results showed that the gene was quickly induced (1 h) by the five heavy metals and the order of expression level was Hg>Pb>Cd>Cu>Zn. The induction effect of H2O2 was 5-fold after about 15 min, but soon decreased to a non-significant level (30 min). The genetic diversity of Tetrahymena MT genes is discussed in relation to the unique structure of the Tpig-MT1 gene and other reported Cd-MT isoforms. (C) 2008 Elsevier B.V. All rights reserved.

Species transformation of trace elements and their distribution prediction in dyestuff residue incineration

The release of heavy metals from the combustion of hazardous wastes is an environmental issue of increasing concern. The species transformation characteristics of toxic heavy metals and their distribution are considered to be a complex problem of mechanism. The behavior of hazardous dyestuff residue is investigated in a tubular furnace under the general condition of hazardous waste pyrolysis and gasfication. Data interpretation has been aided by parallel theoretical study based on a thermodynamic equilibrium model based on the principle of Gibbs free energy minimization. The results show that Ni, Zn, Mn, and Cr are more enriched in dyestuff residue incineration than other heavy metals (Hg, As, and Se) subjected to volatilization. The thermodynamic model calculation is used for explaining the experiment data at 800 degrees C and analyzing species transformation of heavy metals. These results of species transformation are used to predict the distribution and emission characteristics of trace elements. Although most trace element predictions are validated by the measurements, cautions are in order due to the complexity of incineration systems.

Active site structure of NO decomposition on perovskite(-like) oxides: An investigation from experiment and density functional theory

Active site structure for NO decomposition carried out on perovskite-like oxides were discussed based on the N-2 yield measured from LaSrNi1-x,AlxO4 with different B-site cations and from La2-ySryCuO4 with different crystal phases. Results show that the active site contains two oxygen vacancies, two transition metals, and one lattice-oxygen, with the oxygen vacancy locating on the apex of MO6 octahedron, and the lattice oxygen locating between the two transition metals (i.e., M-O-M plane). Density functional theory (DFT) analysis to the structure shows that this new active site is the most active structure for NO adsorbing, and hence, for NO decomposition. The similar trend of the relative energies that are required for the formation of oxygen vacancies with f form (calculated from DFT), the amount of oxygen vacancies, and the activities (N-2 yield) certifies this result further.

Phenomenon of micro-droplets formation on metals during the deliquescence of salt particles in atmosphere

CORROSION; MECHANISM; WATER; ZINC

Alteration of metallothionein mRNA in bay scallop Argopecten irradians under cadmium exposure and bacteria challenge

Metallothionein (MT) is a superfamily of cysteine-rich proteins contributing to metal metabolism, detoxification of heavy metals, and immune response such as protecting against ionizing radiation and antioxidant defense. A metallothionein (designated AiMT2) gene was identified and cloned from bay scallop, Argopecten irradians. The full length cDNA of AiMT2 consisted of an open reading frame (ORF) of 333 bp encoding a protein of 110 amino acids. with nine characteristic Cys-X-Cys, five Cys-X-X-Cys, five Cys-X-X-X-Cys and two Cys-Cys motif arrangements and a conserved structural pattern Cys-x-Cys-x(3)-Cys-Tyr-x(3)Cys-x-Cys-x(3)-Cys-x-Cys-Arg at the C-terminus. The cloned ANT showed about 50% identity in the deduced amino acid sequence with previously published MT sequences of mussels and oysters. The conserved structural pattern and the close phylogenetic relationship of AiMT2 shared with MTs from other mollusc especially bivalves indicated that AiMT2 was a new member of molluscan MT family. The mRNA transcripts in hemolymph of AiMT2 under cadmium (Cd) exposure and bacteria challenge were examined by real-time RT-PCR. The mRNA expression of AiMT2 was up-regulated to 3.99-fold at 2 h after Listonella anguillarum challenge, and increased drastically to 66.12-fold and 126.96-fold at 16 and 32 h post-challenge respectively. Cadmium ion exposure could induce the expression of AiMT2, and the expression level increased 2.56-fold and 6.91-fold in hemolymph respectively after a 10-day exposure of 100 mu g L-1 and 200 mu g L-1 CdCl2. The sensitivity of AiMT2 to bacteria challenge and cadmium stress indicated it was a new Cd-dependent MT in bay scallop and also regulated by an immune challenge. The changes in the expression of AiMT2 could be used as an indicator of exposure to metals in pollution monitoring programs and oxidative stress, and bay scallop as a potential sentinel organism for the cadmium contamination in aquatic environment. (C) 2008 Elsevier Inc. All rights reserved.

Toxicity of lead, cadmium and mercury on embryogenesis, survival, growth and metamorphosis of Meretrix meretrix larvae

In order to assess the toxicity of heavy metals on the early development of Meretrix meretrix, the effects of mercury (Hg), cadmium (Cd) and lead (Pb) on embryogenesis, survival, growth and metamorphosis of larvae were investigated. The EC50 for embryogenesis was 5.4 mu g l(-1) for Hg, 1014 mu g l(-1) for Cd and 297 mu g l(-1) for Pb, respectively. The 96 h LC50 for D-shaped larvae was 14.0 mu g l(-1) for Hg, 68 mu g l(-1) for Cd and 353 mu g l(-1) for Pb, respectively. Growth was significantly retarded at 18.5 mu g l(-1) (0.1 mu M) for Hg, 104 mu g l(-1) (1 mu M) for Cd and 197 mu g l(-1) (1 mu M) for Pb, respectively. The EC50 for metamorphosis, similar to 48 h LC50, was higher than 96 h LC50. Our results indicate that the early development of M. meretrix is highly sensitive to heavy metals and can be used as a test organism for ecotoxicology bioassays in temperate and subtropical regions.