Roles for root iron plaque in sequestration and uptake of heavy metals and metalloids in aquatic and wetland plants.

Science.gov (United States)

Tripathi, Rudra D; Tripathi, Preeti; Dwivedi, Sanjay; Kumar, Amit; Mishra, Aradhana; Chauhan, Puneet S; Norton, Gareth J; Nautiyal, Chandra S

2014-10-01

Toxic metal(loid) contamination of soil and sediment poses long term risk to soil and human health through plant-human or plant-animal-human food chain pathways. Iron plaque (IP) formation is frequent in aquatic and wetland plant species and is responsible for the sequestration of various metal(loids). The presence of IP may act as a buffer or barrier and may thus enhance or reduce the uptake of potentially phytotoxic metals and metalloids by plants. If IP acts as a barrier, then low IP producing macrophytes/aquatic plants may be better accumulators of toxic metals and may find use in constructed wetlands for remediation of pollutants, while high IP forming edible plant species could be safer for human consumption. Conversely, if IP acts as a buffer for mineral nutrients and toxic elements then those cultivars may be rich in nutrients, but may also cause toxicity. However, an ecotoxicological risk is also inevitable if IP rich macrophyte roots containing heavy metals are consumed by herbivores. In this review, we summarize the current understanding about the role of IP in metal and metalloid sequestration, uptake, and transport. Furthermore, we will address the role of root IP in Oryza sativa for arsenic (As) sequestration leading to lower grain As translocation, reducing the risk of human exposure.

Flavoprotein-mediated tellurite reduction: structural basis and applications to the synthesis of tellurium-containing nanostructures

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Mauricio Arenas-Salinas

2016-07-01

Full Text Available The tellurium oxyanion tellurite (TeO32- is extremely harmful for most organisms. It has been suggested that a potential bacterial tellurite resistance mechanism would consist of an enzymatic, NAD(PH-dependent, reduction to the less toxic form elemental tellurium (Te0. To date, a number of enzymes such as catalase, type II NADH dehydrogenase and terminal oxidases from the electron transport chain, nitrate reductases, and dihydrolipoamide dehydrogenase (E3, among others, have been shown to display tellurite-reducing activity. This activity is generically referred to as tellurite reductase (TR. Bioinformatic data resting on some of the abovementioned enzymes enabled the identification of common structures involved in tellurite reduction including vicinal catalytic cysteine residues and the FAD/NAD(P+-binding domain, which is characteristic of some flavoproteins. Along this line, thioredoxin reductase (TrxB, alkyl hydroperoxide reductase (AhpF, glutathione reductase (GorA, mercuric reductase (MerA, NADH: flavorubredoxin reductase (NorW, dihydrolipoamide dehydrogenase, and the putative oxidoreductase YkgC from Escherichia coli or environmental bacteria were purified and assessed for TR activity. All of them displayed in vitro TR activity at the expense of NADH or NADPH oxidation. In general, optimal reducing conditions occurred around pH 9-10 and 37 °C.Enzymes exhibiting strong TR activity produced Te-containing nanostructures (TeNS. While GorA and AhpF generated TeNS of 75 nm average diameter, E3 and YkgC produced larger structures (> 100 nm. Electron-dense structures were observed in cells over-expressing genes encoding TrxB, GorA and YkgC.

Heavy metals and metalloids as a cause for protein misfolding and aggregation.

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Tamás, Markus J; Sharma, Sandeep K; Ibstedt, Sebastian; Jacobson, Therese; Christen, Philipp

2014-02-25

While the toxicity of metals and metalloids, like arsenic, cadmium, mercury, lead and chromium, is undisputed, the underlying molecular mechanisms are not entirely clear. General consensus holds that proteins are the prime targets; heavy metals interfere with the physiological activity of specific, particularly susceptible proteins, either by forming a complex with functional side chain groups or by displacing essential metal ions in metalloproteins. Recent studies have revealed an additional mode of metal action targeted at proteins in a non-native state; certain heavy metals and metalloids have been found to inhibit the in vitro refolding of chemically denatured proteins, to interfere with protein folding in vivo and to cause aggregation of nascent proteins in living cells. Apparently, unfolded proteins with motile backbone and side chains are considerably more prone to engage in stable, pluridentate metal complexes than native proteins with their well-defined 3D structure. By interfering with the folding process, heavy metal ions and metalloids profoundly affect protein homeostasis and cell viability. This review describes how heavy metals impede protein folding and promote protein aggregation, how cells regulate quality control systems to protect themselves from metal toxicity and how metals might contribute to protein misfolding disorders.

Technological advances in tellurite glasses properties, processing, and applications

CERN Document Server

Manzani, Danilo

2017-01-01

This book is the first to provide a comprehensive introduction to the synthesis, optical properties, and photonics applications of tellurite glasses. The book begins with an overview of tellurite glasses, followed by expert chapters on synthesis, properties, and state-of-the-art applications ranging from laser glass, optical fibers, and optical communications through color tuning, plasmonics, supercontinuum generation, and other photonic devices. The book provides in-depth information on the the structural, linear, and non-linear optical properties of tellurite glasses and their implications for device development. Real-world examples give the reader valuable insight into the applications of tellurite glass. A detailed discussion of glass production methods, including raw materials and melting and refining oxide- and fluoro-tellurite glasses, is also included. The book features an extensive reference list for further reading. This highly readable and didactic text draws on chemical composition, glass science,...

Effect doses for protection of human health predicted from physicochemical properties of metals/metalloids.

Science.gov (United States)

Wang, Ying; Wu, Fengchang; Liu, Yuedan; Mu, Yunsong; Giesy, John P; Meng, Wei; Hu, Qing; Liu, Jing; Dang, Zhi

2018-01-01

Effect doses (EDs) of metals/metalloids, usually obtained from toxicological experiments are required for developing environmental quality criteria/standards for use in assessment of hazard or risks. However, because in vivo tests are time-consuming, costly and sometimes impossible to conduct, among more than 60 metals/metalloids, there are sufficient data for development of EDs for only approximately 25 metals/metalloids. Hence, it was deemed a challenge to derive EDs for additional metals by use of alternative methods. This study found significant relationships between EDs and physicochemical parameters for twenty-five metals/metalloids. Elements were divided into three classes and then three individual empirical models were developed based on the most relevant parameters for each class. These parameters included log-βn, ΔE 0 and X m 2 r, respectively (R 2  = 0.988, 0.839, 0.871, P metalloids. Here, these alternative models for deriving thresholds of toxicity that could be used to perform preliminarily, screen-level health assessments for metals are presented. Copyright © 2017. Published by Elsevier Ltd.

Immobilization of Technetium Waste from Pyro-processing Using Tellurite Glasses

Energy Technology Data Exchange (ETDEWEB)

Heo, Jong; Pyo, Jae-Young; Lee, Cheong-Won [POSTECH, Pohang (Korea, Republic of); Yang, Jae-Hwan; Park, Hwan-Seo [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2016-10-15

Vitrification of Tc wastes has been challenging because of the low solubility in the silicate glass and high volatility in the melting process. In previous studies, the measured solubility of Tc and Re was ⁓ 3000 ppm at 1000 .deg. C in low activity waste (LAW) glass. And retention of Tc has been reported within 12 - 77% during the borosilicate vitrification process. Tellurite glasses have been studied for halide waste immobilization due to low melting temperatures (Tm= 600-800 .deg. C) and flexibility of network with foreign ions. Tellurite glasses offered higher halide retention than borosilicate glasses. The structure of pure tellurite (TeO{sub 2}) consists of TeO{sub 4} trigonal bipyramids (tbp), but TeO{sub 4} units are converted to TeO{sub 3} trigonal pyramids (tp) having non-bridging oxygen (NBO) as the modifiers added. Objectives of this study are to investigate the tellurite glasses for Tc immobilization using Re as a surrogate. Retention and waste loading of Re were analyzed during the vitrification process of tellurite glass. We investigated local structures of Re ions in glasses by Raman and X-ray absorption spectroscopies. The tellurite glass was investigated to immobilize the Ca(TcO{sub 4}){sub 2}, surrogated by Ca(ReO{sub 4}){sub 2}. The average of Re retention in tellurite glass was 86%. The 7-day PCT results were satisfied with U.S requirement up to 9 mass% of Ca(ReO{sub 4}){sub 2} content. Re in the tellurite glass exists +7 oxidation state and was coordinated with 4 oxygen.

Study of optical properties of Erbium doped Tellurite glass-polymer composite

Science.gov (United States)

Sushama, D.

2014-10-01

Chalcogenide glasses have wide applications in optical device technology. But it has some disadvantages like thermal instability. Among them Tellurite glasses exhibits high thermal Stability. Doping of rare earth elements into the Tellurite glasses improve its optical properties. To improve its mechanical properties composites of this Tellurite glasses with polymer are prepared. Bulk samples of Er2O3 doped TeO2-WO3-La2O3 Tellurite glasses are prepared from high purity oxide mixtures, melting in an alumina crucible in air atmosphere. Composites of this Tellurite glasses with polymer are prepared by powder mixing method and the thin films of these composites are prepared using polymer press. Variations in band gap of these composites are studied from the UV/Vis/NIR absorption.

Study of optical properties of Erbium doped Tellurite glass-polymer composite

Energy Technology Data Exchange (ETDEWEB)

Sushama, D., E-mail: sushasukumar@gmail.com [Research Awardee, LAMP, Dept. of Physics, Nit, Calicut, India and Dept. of Physics, M.S.M. College, Kayamkulam, Kerala (India)

2014-10-15

Chalcogenide glasses have wide applications in optical device technology. But it has some disadvantages like thermal instability. Among them Tellurite glasses exhibits high thermal Stability. Doping of rare earth elements into the Tellurite glasses improve its optical properties. To improve its mechanical properties composites of this Tellurite glasses with polymer are prepared. Bulk samples of Er{sub 2}O{sub 3} doped TeO{sub 2}‐WO{sub 3}‐La{sub 2}O{sub 3} Tellurite glasses are prepared from high purity oxide mixtures, melting in an alumina crucible in air atmosphere. Composites of this Tellurite glasses with polymer are prepared by powder mixing method and the thin films of these composites are prepared using polymer press. Variations in band gap of these composites are studied from the UV/Vis/NIR absorption.

Study of optical properties of Erbium doped Tellurite glass-polymer composite

International Nuclear Information System (INIS)

Sushama, D.

2014-01-01

Chalcogenide glasses have wide applications in optical device technology. But it has some disadvantages like thermal instability. Among them Tellurite glasses exhibits high thermal Stability. Doping of rare earth elements into the Tellurite glasses improve its optical properties. To improve its mechanical properties composites of this Tellurite glasses with polymer are prepared. Bulk samples of Er 2 O 3 doped TeO 2 ‐WO 3 ‐La 2 O 3 Tellurite glasses are prepared from high purity oxide mixtures, melting in an alumina crucible in air atmosphere. Composites of this Tellurite glasses with polymer are prepared by powder mixing method and the thin films of these composites are prepared using polymer press. Variations in band gap of these composites are studied from the UV/Vis/NIR absorption

Tellurite and Tellurate Reduction by the Aerobic Anoxygenic Phototroph Erythromonas ursincola, Strain KR99 Is Carried out by a Novel Membrane Associated Enzyme

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Chris Maltman

2017-04-01

Full Text Available Erythromonas ursincola, strain KR99 isolated from a freshwater thermal spring of Kamchatka Island in Russia, resists and reduces very high levels of toxic tellurite under aerobic conditions. Reduction is carried out by a constitutively expressed membrane associated enzyme, which was purified and characterized. The tellurite reductase has a molecular weight of 117 kDa, and is comprised of two subunits (62 and 55 kDa in a 1:1 ratio. Optimal activity occurs at pH 7.0 and 28 °C. Tellurite reduction has a Vmax of 5.15 µmol/min/mg protein and a Km of 3.36 mM. The enzyme can also reduce tellurate with a Vmax and Km of 1.08 µmol/min/mg protein and 1.44 mM, respectively. This is the first purified membrane associated Te oxyanion reductase.

Tellurite Composite Microstructured Optical Fibers with Tailored Chromatic Dispersion for Nonlinear Applications

Science.gov (United States)

Duan, Zhongchao; Liao, Meisong; Yan, Xin; Kito, Chihiro; Suzuki, Takenobu; Ohishi, Yasutake

2011-07-01

We report the fabrication of tellurite composite microstructured optical fibers (CMOFs) which consist of a TeO2-Li2O-WO3-MoO3-Nb2O5 (TLWMN) tellurite glass core and TeO2-ZnO-Na2O-La2O3 (TZNL) tellurite glass cladding. Flattened chromatic dispersion and tunable zero dispersion wavelength (ZDW) were realized in the small core diameter (˜1.5 µm) fiber with six surrounding air holes. The optical loss was measured to be about 4.0 dB/m in the spectral range of 1510-1640 nm. Supercontinuum (SC) generation was demonstrated by a femtosecond laser pumping at 1.55 µm. The threshold pump power for this novel tellurite CMOF was the lowest among tellurite microstructured optical fibers (MOFs).

Role of Tellurite Resistance Operon in Filamentous Growth of Yersinia pestis in Macrophages.

Science.gov (United States)

Ponnusamy, Duraisamy; Clinkenbeard, Kenneth D

2015-01-01

Yersinia pestis initiates infection by parasitism of host macrophages. In response to macrophage infections, intracellular Y. pestis can assume a filamentous cellular morphology which may mediate resistance to host cell innate immune responses. We previously observed the expression of Y. pestis tellurite resistance proteins TerD and TerE from the terZABCDE operon during macrophage infections. Others have observed a filamentous response associated with expression of tellurite resistance operon in Escherichia coli exposed to tellurite. Therefore, in this study we examine the potential role of Y. pestis tellurite resistance operon in filamentous cellular morphology during macrophage infections. In vitro treatment of Y. pestis culture with sodium tellurite (Na2TeO3) caused the bacterial cells to assume a filamentous phenotype similar to the filamentous phenotype observed during macrophage infections. A deletion mutant for genes terZAB abolished the filamentous morphologic response to tellurite exposure or intracellular parasitism, but without affecting tellurite resistance. However, a terZABCDE deletion mutant abolished both filamentous morphologic response and tellurite resistance. Complementation of the terZABCDE deletion mutant with terCDE, but not terZAB, partially restored tellurite resistance. When the terZABCDE deletion mutant was complemented with terZAB or terCDE, Y. pestis exhibited filamentous morphology during macrophage infections as well as while these complemented genes were being expressed under an in vitro condition. Further in E. coli, expression of Y. pestis terZAB, but not terCDE, conferred a filamentous phenotype. These findings support the role of Y. pestis terZAB mediation of the filamentous response phenotype; whereas, terCDE confers tellurite resistance. Although the beneficial role of filamentous morphological responses by Y. pestis during macrophage infections is yet to be fully defined, it may be a bacterial adaptive strategy to macrophage

Optical, physical and structural studies of boro-zinc tellurite glasses

International Nuclear Information System (INIS)

Gayathri Pavani, P.; Sadhana, K.; Chandra Mouli, V.

2011-01-01

To investigate the modification effect of the modifier ZnO on boro-tellurite glass, a series of glasses with compositions 50B 2 O 3 -(50-x)ZnO-xTeO 2 have been prepared by conventional melt quenching technique. Amorphous nature of the samples was confirmed through X-ray diffraction technique. Optical absorption and IR structural studies are carried out on the glass system. The optical absorption studies revealed that the cutoff wavelength increases while optical band gap (E opt ) and Urbach energy decreases with an increase of ZnO content. Refractive index evaluated from E opt was found to increase with an increase of ZnO content. The compositional dependence of different physical parameters such as density, molar volume, oxygen packing density, optical basicity, have been analyzed and discussed. The IR studies showed that the structure of glass consists of TeO 4 , TeO 3 /TeO 3+1 , BO 3 , BO 4 and ZnO 4 units. -- Research highlights: → Novel boro-zinc tellurite ternary glasses that can compete with boro-tellurite and zinc tellurite glasses are successfully prepared. → Boro-zinc tellurite ternary glasses are of higher refractive index compared with zinc tellurite glasses. → Optical, physical and structural properties of the novel ternary glass system are explained.→ At 30 mol% of ZnO, TeO 4 is replaced by ZnO 4 indicating the presence of ZnO 4 network.

Glucose-6-phosphate dehydrogenase protects Escherichia coli from tellurite-mediated oxidative stress.

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Juan M Sandoval

Full Text Available The tellurium oxyanion tellurite induces oxidative stress in most microorganisms. In Escherichia coli, tellurite exposure results in high levels of oxidized proteins and membrane lipid peroxides, inactivation of oxidation-sensitive enzymes and reduced glutathione content. In this work, we show that tellurite-exposed E. coli exhibits transcriptional activation of the zwf gene, encoding glucose 6-phosphate dehydrogenase (G6PDH, which in turn results in augmented synthesis of reduced nicotinamide adenine dinucleotide phosphate (NADPH. Increased zwf transcription under tellurite stress results mainly from reactive oxygen species (ROS generation and not from a depletion of cellular glutathione. In addition, the observed increase of G6PDH activity was paralleled by accumulation of glucose-6-phosphate (G6P, suggesting a metabolic flux shift toward the pentose phosphate shunt. Upon zwf overexpression, bacterial cells also show increased levels of antioxidant molecules (NADPH, GSH, better-protected oxidation-sensitive enzymes and decreased amounts of oxidized proteins and membrane lipids. These results suggest that by increasing NADPH content, G6PDH plays an important role in E. coli survival under tellurite stress.

Comparison of accumulation of four metalloids in Allium sativum.

Science.gov (United States)

Ogra, Yasumitsu; Awaya, Yumi; Anan, Yasumi

2015-05-01

In this study, we evaluated the accumulation and metabolism of four metalloids: arsenic (As), selenium (Se), antimony (Sb), and tellurium (Te) in garlic to determine whether garlic can be used for the phytoremediation of those metalloids. Garlic was able to efficiently accumulate As and Se, the two-fourth-period metalloids. However, it was not able to accumulate Sb and Te, the two-fifth-period metalloids, because their bioaccumulation factors were below one. Speciation analyses revealed that four metalloids could be metabolized in garlic, although their metabolites could not be identified yet. Results also suggested that garlic was able to distinguish the metalloids in groups 15 and 16 and the fourth and fifth periods, i.e., As, Se, Sb, and Te. Therefore, garlic is one of the potential plants for the phytoremediation of the fourth-period metalloids.

Predicting criteria continuous concentrations of 34 metals or metalloids by use of quantitative ion character-activity relationships–species sensitivity distributions (QICAR–SSD) model

International Nuclear Information System (INIS)

Mu, Yunsong; Wu, Fengchang; Chen, Cheng; Liu, Yuedan; Zhao, Xiaoli; Haiqing Liao; Giesy, John P.

2014-01-01

Criteria continuous concentrations (CCCs) are useful for describing chronic exposure to pollutants and setting water quality standards to protect aquatic life. However, because of financial, practical, or ethical restrictions on toxicity testing, few data are available to derive CCCs. In this study, CCCs for 34 metals or metalloids were derived using quantitative ion character-activity relationships–species sensitivity distributions (QICAR–SSD) and the final acute-chronic ratio (FACR) method. The results showed that chronic toxic potencies were correlated with several physico-chemical properties among eight species chosen, where the softness index was the most predictive characteristic. Predicted CCCs for most of the metals, except for Lead and Iron, were within a range of 10-fold of values recommended by the U.S. EPA. The QICAR–SSD model was superior to the FACR method for prediction of data-poor metals. This would have significance for predicting toxic potencies and criteria thresholds of more metals or metalloids. - Highlights: • We investigate relationships between σp and log-NOEC in eight species. • The QICAR–SSD model, FACR, and CMC/CCC were used to predict CCCs. • They are as a supplement to screening for toxicities, criteria and standards. - CCCs for 34 metals/metalloids were predicted by use of QICAR–SSD model and FACR method

Magnetically sensitive nanodiamond-doped tellurite glass fibers.

Science.gov (United States)

Ruan, Yinlan; Simpson, David A; Jeske, Jan; Ebendorff-Heidepriem, Heike; Lau, Desmond W M; Ji, Hong; Johnson, Brett C; Ohshima, Takeshi; Afshar V, Shahraam; Hollenberg, Lloyd; Greentree, Andrew D; Monro, Tanya M; Gibson, Brant C

2018-01-19

Traditional optical fibers are insensitive to magnetic fields, however many applications would benefit from fiber-based magnetometry devices. In this work, we demonstrate a magnetically sensitive optical fiber by doping nanodiamonds containing nitrogen vacancy centers into tellurite glass fibers. The fabrication process provides a robust and isolated sensing platform as the magnetic sensors are fixed in the tellurite glass matrix. Using optically detected magnetic resonance from the doped nanodiamonds, we demonstrate detection of local magnetic fields via side excitation and longitudinal collection. This is a first step towards intrinsically magneto-sensitive fiber devices with future applications in medical magneto-endoscopy and remote mineral exploration sensing.

Aeration Controls the Reduction and Methylation of Tellurium by the Aerobic, Tellurite-Resistant Marine Yeast Rhodotorula mucilaginosa▿

Science.gov (United States)

Ollivier, Patrick R. L.; Bahrou, Andrew S.; Church, Thomas M.; Hanson, Thomas E.

2011-01-01

We previously described a marine, tellurite-resistant strain of the yeast Rhodotorula mucilaginosa that both precipitates intracellular Te(0) and volatilizes methylated Te compounds when grown in the presence of the oxyanion tellurite. The uses of microbes as a “green” route for the production of Te(0)-containing nanostructures and for the remediation of Te-oxyanion wastes have great potential, and so a more thorough understanding of this process is required. Here, Te precipitation and volatilization catalyzed by R. mucilaginosa were examined in continuously aerated and sealed (low oxygen concentration) batch cultures. Continuous aeration was found to strongly promote Te volatilization while inhibiting Te(0) precipitation. This differs from the results in sealed batch cultures, for which tellurite reduction to Te(0) was found to be very efficient. We show also that volatile Te species may be degraded rapidly in medium and converted to the particulate form by biological activity. Further experiments revealed that Te(0) precipitates produced by R. mucilaginosa can be further transformed to volatile and dissolved Te species. However, it was not clearly determined whether Te(0) is a required intermediate for Te volatilization. Based on these results, we conclude that low oxygen concentrations will be the most efficient for production of Te(0) nanoparticles while limiting the production of toxic volatile Te species, although the production of these compounds may never be completely eliminated. PMID:21602387

Spatial clustering of metal and metalloid mixtures in unregulated water sources on the Navajo Nation - Arizona, New Mexico, and Utah, USA.

Science.gov (United States)

Hoover, Joseph H; Coker, Eric; Barney, Yolanda; Shuey, Chris; Lewis, Johnnye

2018-08-15

Contaminant mixtures are identified regularly in public and private drinking water supplies throughout the United States; however, the complex and often correlated nature of mixtures makes identification of relevant combinations challenging. This study employed a Bayesian clustering method to identify subgroups of water sources with similar metal and metalloid profiles. Additionally, a spatial scan statistic assessed spatial clustering of these subgroups and a human health metric was applied to investigate potential for human toxicity. These methods were applied to a dataset comprised of metal and metalloid measurements from unregulated water sources located on the Navajo Nation, in the southwest United States. Results indicated distinct subgroups of water sources with similar contaminant profiles and that some of these subgroups were spatially clustered. Several profiles had metal and metalloid concentrations that may have potential for human toxicity including arsenic, uranium, lead, manganese, and selenium. This approach may be useful for identifying mixtures in water sources, spatially evaluating the clusters, and help inform toxicological research investigating mixtures. Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.

Influence of tellurite on lifetime for samarium doped lanthanum lead borate glass

Science.gov (United States)

Madhu, A.; Eraiah, B.

2018-04-01

Samarium substituted tellurium lanthanum lead borate glass is prepared using melt quenching technique. Luminescence spectra have been recorded upon excitation with 402 nm various transitions from 4G5/2 level, for samarium doped tellurite glasses are studied and also lifetime for all the samples exhibit single exponential behaviour of decay curve. Luminescence spectra of present glasses show quenching effect due to cross-relation channels of samarium ions. The lifetime of glass samples decrease as the tellurite concentration is decreased. So, it evidences that to attain longer lifetime for lasing material one can tune the host by selecting concentration of tellurite.

Health benefit from decreasing exposure to heavy metals and metalloid after strict pollution control measures near a typical river basin area in China.

Science.gov (United States)

Cao, Suzhen; Duan, Xiaoli; Ma, Yingqun; Zhao, Xiuge; Qin, Yanwen; Liu, Yan; Li, Sai; Zheng, Binghui; Wei, Fusheng

2017-10-01

The metal(loid) pollution still is a great concern due to the effects from urbanization and industrialization. While, the health risks from the toxic metal(loid)s could decrease if strict pollution control measures were adopted. However, few studies to date investigate the health risks of heavy metal(loid)s in a systematic river basin for the dependent residents, after taking pollution control measures. Thus, the contents of metal(loid)s (Cu, Pb, Zn, Cd, Mn, As) in surface water along a typical river basin were investigated in this study, and the potential non-carcinogenic and carcinogenic health risks posed to the residents were assessed. Although the soluble contents of Cu, Pb, Zn and Cd exceeded the respective thresholds in two sites located downstream the mine area, they were greatly decreased in comparison with previous contamination levels, and the soluble concentrations of all the metal(loid)s were within the relevant thresholds in the sites far away from the mining area. Moreover, the closer to the mining area, the higher the pollution levels of metal(loid)s. The total hazard index for non-carcinogenic risks of metal(loid)s were basically lower than the threshold (1) for the local population. Whereas, although the content of metal(loid)s were low (such as As), they could pose relative higher non-carcinogenic health risks. The result illustrated that pollution levels, toxicity of the contaminants and exposure behavior patterns all could contribute to the potential detrimental health risks. Additionally, the non-carcinogenic and carcinogenic risks from ingestion exposure were ∼2-∼4 orders of magnitude higher than those from dermal contact. The total carcinogenic risks were basically lower than the maximum tolerable levels (1.0 × 10 -4 ), indicating carcinogenic risks from most areas of the river could also be accepted. Among different population groups, heavy metal(loid)s posed relative higher non-carcinogenic and carcinogenic risks to the children in

The evolution of December 2004 tsunami deposits: temporal and spatial distribution of potentially toxic metalloids.

Science.gov (United States)

Kozak, Lidia; Niedzielski, Przemysław

2013-11-01

The article presents the results of research into the content of metalloid fractions in the tsunami deposits from southern Thailand. The following fractions, which are potentially most easily released from deposits to the environment, have been distinguished: the water soluble fraction, the exchangeable fraction extracted with the phosphate buffer and the fraction eluted with the solution of hydrochloric acid. The analytical technique atomic absorption spectrometry with hydride generation was applied. Spatial variability of the metalloid fractions in deposits and changes occurring in deposits over a period of several years of observation were determined. Based on the statistical analysis of the results, an attempt was made to determine the post-depositional release of deposits components to the environment. Based on the conducted research, the 4 years forming process of the arsenic, antimony and selenium occurrence after the deposition of sediments on land were described, as well as the balance in the amount of deposit components released to the environment. Copyright © 2013 Elsevier Ltd. All rights reserved.

Comparative studies on antisickling properties of thiocyanate, tellurite and hydroxyurea

International Nuclear Information System (INIS)

Oyewole, O.I.; Maloma, S.O.; Adebayo, J.O.

2008-01-01

Thiocyanate, hydroxyurea and tellurite are among chemical agents being used as antisickling drugs and currently receiving attention for research. The antisickling properties of these drugs was investigated and compared in this study. Human sickle blood was incubated with the drugs in vitro at concentrations related to the dose used by patients in vivo. Haemoglobin function and specific aspects of the sickling process were then measured by employing standard methods used in screening potential antisickling agents. All the drugs significantly inhibited (P<0.05) sickling of deoxygenated sickle blood and formation of irreversibly sickled cell in a dose and time-dependent manner. Thiocyanate, hydroxyurea and tellurite inhibited sickling optimally at 20 mM, 40 mM and 50 microM respectively. Thiocyanate and hydroxyurea prolonged sickle red blood cell life span as indicated in the significant decrease in haemolysis and osmotic fragility while tellurite increased these blood parameters. The three drugs also caused significant prolongation of delay time of haemoglobin S (HbS) polymerization while thiocyanate and hydroxyurea significantly increased (P<0.05) both solubility ratio and oxygen affinity of HbS. Results obtained in this study suggest that the three drugs have remarkable antisickling potential in vitro with thiocyanate being the most efficient followed by tellurite. (author)

Multi-element determination of metals and metalloids in waters and wastewaters, at trace concentration level, using electroanalytical stripping methods with environmentally friendly mercury free-electrodes: A review.

Science.gov (United States)

Alves, Georgina M S; Rocha, Luciana S; Soares, Helena M V M

2017-12-01

Nowadays, water is no longer regarded as an inexhaustible resource and the excessive release and proliferation of toxic metal(loid)s into aquatic environments has become a critical issue. Therefore, fast, accurate, simple, selective, sensitive and portable methodologies to detect multiple elements in natural waters is of paramount importance. Electrochemical stripping analysis is an efficient tool for trace metal(loid)s determinations and bring new prospects for answering the current environmental concerns. This review presents a survey of the advancements made between 2003 and 2016 on the development and application of non-toxic mercury free electrodes on the simultaneous analysis of metals and metalloids in waters and wastewaters by means of electroanalytical stripping techniques. The advantages, limitations, improvements and real applications of these "green" sensors are discussed from a critical point of view. Copyright © 2017 Elsevier B.V. All rights reserved.

Elaboration and optimization of tellurite-based materials for raman gain application

Science.gov (United States)

Guery, Guillaume

Tellurite-based oxide glasses have been investigated as promising materials for Raman gain applications, due to their good linear and nonlinear optical properties and their wide transparency windows in the near- and midwave infrared spectral region. Furthermore, their interesting thermal properties, i.e. low glass transition temperature and ability to be drawn into optical fibers, make tellurite-based glasses excellent candidates for optical fiber amplifiers. The estimation of the strength and spectral distribution of Raman gain in materials is commonly approximated from the spontaneous Raman scattering cross-section measurement. For development of tellurite-based glasses as Raman amplifiers, understanding the relationship between glass structure, vibrational response, and nonlinear optical properties (NLO) represents a key point. This dissertation provides an answer to the fundamental question of the PhD study: "What is the impact of the glass structure on Raman gain properties of tellurite glasses?" This dissertation summarizes findings on different tellurite-based glass families: the TeO2-TaO5/2-ZnO, TeO2-BiO 3/2-ZnO and TeO2-NbO5/2 glass networks. The influence of glass modifiers has been shown on the glass' properties. Introduction of tantalum oxide or zinc oxide has been shown to increase the glass' stability against crystallization, quantified by DeltaT, where DeltaT = Tx -Tg. Added to the variation of the glass viscosity, this attribute is critical in fabricating optical fibers and for the use of these materials in fiber-based Raman gain applications. The role of ZnO in the tellurite network and the mechanism for structural modification has been determined. This addition results in not only the largest DeltaT reported for these highly nonlinear glasses to date, but coincides with a commensurate decrease of the refractive index. A hydroxyl purification has been developed that when employed, resulted in high purity preform materials exhibiting a limited

Effect of ZnO on the Thermal Properties of Tellurite Glass

Directory of Open Access Journals (Sweden)

H. A. A. Sidek

2013-01-01

Full Text Available Systematic series of binary zinc tellurite glasses in the form (ZnOx(TeO2 (where x=0 to 0.4 with an interval of 0.05 mole fraction have been successfully prepared via conventional melt cast-quenching technique. Their density was determined by Archimedes method with acetone as buoyant liquid. The thermal expansion coefficient of each zinc tellurite glasses was measured using L75D1250 dilatometer, while their glass transition temperature (Tg was determined by the SETARAM Labsys DTA/6 differential thermogravimetric analysis at a heating rate of 20 K min−1. The acoustic Debye temperature and the softening temperature (Ts were estimated based on the longitudinal (VL and shear ultrasonic (Vs wave velocities propagated in each glass sample. For ultrasonic velocity measurement of the glass sample, MATEC MBS 8000 Ultrasonic Data Acquisition System was used. All measurements were taken at 10 MHz frequency and at room temperature. All the thermal properties of such binary tellurite glasses were measured as a function of ZnO composition. The composition dependence was discussed in terms of ZnO modifiers that were expected to change the thermal properties of tellurite glasses. Experimental results show their density, and the thermal expansion coefficient increases as more ZnO content is added to the tellurite glass network, while their glass transition, Debye temperature, and the softening temperature decrease due to a change in the coordination number (CN of the network forming atoms and the destruction of the network structure brought about by the formation of some nonbridging oxygen (NBO atoms.

Erbium concentration dependent absorbance in tellurite glass

Energy Technology Data Exchange (ETDEWEB)

Sazali, E. S., E-mail: mdsupar@utm; Rohani, M. S., E-mail: mdsupar@utm; Sahar, M. R., E-mail: mdsupar@utm; Arifin, R., E-mail: mdsupar@utm; Ghoshal, S. K., E-mail: mdsupar@utm; Hamzah, K., E-mail: mdsupar@utm [Advanced Optical Material Research Group, Department of Physics, Faculty of Science, Universiti Teknologi Malaysia, 81310, Skudai, Johor Bahru, Johor (Malaysia)

2014-09-25

Enhancing the optical absorption cross-section in topically important rare earth doped tellurite glasses is challenging for photonic devices. Controlled synthesis and detailed characterizations of the optical properties of these glasses are important for the optimization. The influence of varying concentration of Er{sup 3+} ions on the absorbance characteristics of lead tellurite glasses synthesized via melt-quenching technique are investigated. The UV-Vis absorption spectra exhibits six prominent peaks centered at 490, 526, 652, 800, 982 and 1520 nm ascribed to the transitions in erbium ion from the ground state to the excited states {sup 4}F{sub 7/2}, {sup 2}H{sub 11/2}, {sup 4}F{sub 9/2}, {sup 4}I{sub 9/2}, {sup 2}H{sub 11/2} and {sup 4}I{sub 13/2}, respectively. The results are analyzed by means of optical band gap E{sub g} and Urbach energy E{sub u}. The values of the energy band gap are found decreased from 2.82 to 2.51 eV and the Urbach energy increased from 0.15 to 0.24 eV with the increase of the Er{sub 2}O{sub 3} concentration from 0 to 1.5 mol%. The excellent absorbance of the prepared tellurite glasses makes them suitable for fabricating solid state lasers.

Synthesis and Antibacterial Activity of Metal(loid Nanostructures by Environmental Multi-Metal(loid Resistant Bacteria and Metal(loid-Reducing Flavoproteins

Directory of Open Access Journals (Sweden)

Maximiliano Figueroa

2018-05-01

Full Text Available Microbes are suitable candidates to recover and decontaminate different environments from soluble metal ions, either via reduction or precipitation to generate insoluble, non-toxic derivatives. In general, microorganisms reduce toxic metal ions generating nanostructures (NS, which display great applicability in biotechnological processes. Since the molecular bases of bacterial reduction are still unknown, the search for new -environmentally safe and less expensive- methods to synthesize NS have made biological systems attractive candidates. Here, 47 microorganisms isolated from a number of environmental samples were analyzed for their tolerance or sensitivity to 19 metal(loids. Ten of them were highly tolerant to some of them and were assessed for their ability to reduce these toxicants in vitro. All isolates were analyzed by 16S rRNA gene sequencing, fatty acids composition, biochemical tests and electron microscopy. Results showed that they belong to the Enterobacter, Staphylococcus, Acinetobacter, and Exiguobacterium genera. Most strains displayed metal(loid-reducing activity using either NADH or NADPH as cofactor. While Acinetobacter schindleri showed the highest tellurite (TeO32- and tetrachloro aurate (AuCl4- reducing activity, Staphylococcus sciuri and Exiguobacterium acetylicum exhibited selenite (SeO32- and silver (Ag+ reducing activity, respectively. Based on these results, we used these bacteria to synthetize, in vivo and in vitro Te, Se, Au, and Ag-containing nanostructures. On the other hand, we also used purified E. cloacae glutathione reductase to synthesize in vitro Te-, Ag-, and Se-containing NS, whose morphology, size, composition, and chemical composition were evaluated. Finally, we assessed the putative anti-bacterial activity exhibited by the in vitro synthesized NS: Te-containing NS were more effective than Au-NS in inhibiting Escherichia coli and Listeria monocytogenes growth. Aerobically synthesized TeNS using MF09 crude

Predicting criteria continuous concentrations of 34 metals or metalloids by use of quantitative ion character-activity relationships-species sensitivity distributions (QICAR-SSD) model.

Science.gov (United States)

Mu, Yunsong; Wu, Fengchang; Chen, Cheng; Liu, Yuedan; Zhao, Xiaoli; Haiqing Liao; Giesy, John P

2014-05-01

Criteria continuous concentrations (CCCs) are useful for describing chronic exposure to pollutants and setting water quality standards to protect aquatic life. However, because of financial, practical, or ethical restrictions on toxicity testing, few data are available to derive CCCs. In this study, CCCs for 34 metals or metalloids were derived using quantitative ion character-activity relationships-species sensitivity distributions (QICAR-SSD) and the final acute-chronic ratio (FACR) method. The results showed that chronic toxic potencies were correlated with several physico-chemical properties among eight species chosen, where the softness index was the most predictive characteristic. Predicted CCCs for most of the metals, except for Lead and Iron, were within a range of 10-fold of values recommended by the U.S. EPA. The QICAR-SSD model was superior to the FACR method for prediction of data-poor metals. This would have significance for predicting toxic potencies and criteria thresholds of more metals or metalloids. Copyright © 2014 Elsevier Ltd. All rights reserved.

Improved Density Functional Tight Binding Potentials for Metalloid Aluminum Clusters

Science.gov (United States)

2016-06-01

unlimited IMPROVED DENSITY-FUNCTIONAL TIGHT BINDING POTENTIALS FOR METALLOID ALUMINUM CLUSTERS by Joon H. Kim June 2016 Thesis Advisor...DATES COVERED Master’s thesis 4. TITLE AND SUBTITLE IMPROVED DENSITY-FUNCTIONAL TIGHT BINDING POTENTIALS FOR METALLOID ALUMINUM CLUSTERS 5. FUNDING...repulsive potentials for use in density-functional tight binding (DFTB) simulations of low-valence aluminum metalloid clusters . These systems are under

Immobilization and bonding scheme of radioactive iodine-129 in silver tellurite glass

Science.gov (United States)

Lee, Cheong Won; Pyo, Jae-Young; Park, Hwan-Seo; Yang, Jae Hwan; Heo, Jong

2017-08-01

Silver tellurite glasses with melting temperatures disposal site. Iodine waste loading in glasses was as high as 12.64 wt% of all metallic elements and 11.21 wt% including oxygen. Normalized elemental releases obtained from the product consistency test were well below US regulation of 2 g/m2. Iodines are surrounded by four Ag+ ions forming [Ag4I]3+ units that are further connected to tellurite network through bonds with non-bridging oxygens.

Structural and thermal properties of vanadium tellurite glasses

Science.gov (United States)

Kaur, Rajinder; Kaur, Ramandeep; Khanna, Atul; González, Fernando

2018-04-01

V2O5-TeO2 glasses containing 10 to 50 mol% V2O5 were prepared by melt quenching and characterized by X-ray diffraction (XRD), density, Differential Scanning Calorimetry (DSC) and Raman studies.XRD confirmed the amorphous nature of vanadium tellurite samples. The density of the glasses decreases and the molar volume increases on increasing the concentration of V2O5. The thermal properties, such as glass transition temperature Tg, crystallization temperature Tc, and the melting temperature Tm were measured. Tg decreases from a value of 288°C to 232°C. The changes in Tg were correlated with the number of bonds per unit volume, and the average stretching force constant. Raman spectra were used to elucidate the short-range structure of vanadium tellurite glasses.

Remediation of heavy metal(loid)s contaminated soils--to mobilize or to immobilize?

Science.gov (United States)

Bolan, Nanthi; Kunhikrishnan, Anitha; Thangarajan, Ramya; Kumpiene, Jurate; Park, Jinhee; Makino, Tomoyuki; Kirkham, Mary Beth; Scheckel, Kirk

2014-02-15

Unlike organic contaminants, metal(loid)s do not undergo microbial or chemical degradation and persist for a long time after their introduction. Bioavailability of metal(loid)s plays a vital role in the remediation of contaminated soils. In this review, the remediation of heavy metal(loid) contaminated soils through manipulating their bioavailability using a range of soil amendments will be presented. Mobilizing amendments such as chelating and desorbing agents increase the bioavailability and mobility of metal(loid)s. Immobilizing amendments such of precipitating agents and sorbent materials decrease the bioavailabilty and mobility of metal(loid)s. Mobilizing agents can be used to enhance the removal of heavy metal(loid)s though plant uptake and soil washing. Immobilizing agents can be used to reduce the transfer to metal(loid)s to food chain via plant uptake and leaching to groundwater. One of the major limitations of mobilizing technique is susceptibility to leaching of the mobilized heavy metal(loid)s in the absence of active plant uptake. Similarly, in the case of the immobilization technique the long-term stability of the immobilized heavy metal(loid)s needs to be monitored. Copyright © 2013 Elsevier B.V. All rights reserved.

Optical and spectroscopic properties of Eu-doped tellurite glasses and glass ceramics

International Nuclear Information System (INIS)

Stambouli, W.; Elhouichet, H.; Gelloz, B.; Férid, M.

2013-01-01

Tellurite glasses doped with trivalent europium were prepared by the conventional melt quenching technique, in the chemical composition of (85−x) TeO 2 +5La 2 O 3 +10TiO 2 +xEu 2 O 3 by varying the concentration of the rare-earth ion in the order 0.5, 1 and 1.5 mol%. Using Judd–Ofelt analysis, we calculated intensity parameters (Ω 2 and Ω 4 ), spontaneous emission probabilities, the radiative lifetime, luminescence branching factors, the quantum yield of luminescence, and the stimulated emission cross-sections for 5 D 0 → 7 F 2 transition. The change in optical properties with the variation of Eu 3+ ion concentration have been discussed and compared with other glasses. The luminescence intensity ratio, quantum efficiency and emission cross-section values support that the TeEu1.5 tellurite glass is a suitable candidate for red laser source applications. Optical properties for Eu 3+ doped tellurite glass, heated for different temperature, were investigated. Crystalline phases for α-TeO 2 , γ-TeO 2 and TiTe 3 O 8 system were determined by the XRD method. The effect of heat treatment on luminescence properties in the tellurite glass was discussed. By using Eu 3+ as a probe, the local structure of rare-earth ion in tellurite glass, vitro-ceramic and ceramic glass has been investigated. The evaluated J–O intensity parameters have been used to calculate different radiative and laser characteristic parameters of the 5 D 0 excited level. The large magnitudes of stimulated emission cross-section (σ e ), branching ratio (β) and Gain bandwidth (σ e ×Δλ eff ) obtained for 5 D 0 → 7 F 2 (613 nm) transition for ceramic glass indicate that the present glass ceramic is promising host material for Eu 3+ doped fiber amplifiers. The measured lifetime of 5 D 0 excited state increases with increase of the heat treatment which further indicate that some Eu 3+ ions were successfully embedded in the crystal phase and prove the low phonon energy environment of Eu 3+ ions

Atom-Photon Coupling from Nitrogen-vacancy Centres Embedded in Tellurite Microspheres

Science.gov (United States)

Ruan, Yinlan; Gibson, Brant C.; Lau, Desmond W. M.; Greentree, Andrew D.; Ji, Hong; Ebendorff-Heidepriem, Heike; Johnson, Brett C.; Ohshima, Takeshi; Monro, Tanya M.

2015-06-01

We have developed a technique for creating high quality tellurite microspheres with embedded nanodiamonds (NDs) containing nitrogen-vacancy (NV) centres. This hybrid method allows fluorescence of the NVs in the NDs to be directly, rather than evanescently, coupled to the whispering gallery modes of the tellurite microspheres at room temperature. As a demonstration of its sensing potential, shifting of the resonance peaks is also demonstrated by coating a sphere surface with a liquid layer. This new approach is a robust way of creating cavities for use in quantum and sensing applications.

Nature's refineries — Metals and metalloids in arc volcanoes

Science.gov (United States)

Henley, R.W.; Berger, Byron R.

2013-01-01

Chemical data for fumaroles and for atmospheric gas and ash plumes from active arc volcanoes provide glimpses of the rates of release of metal and metalloids, such as Tl and Cd, from shallow and mid-crust magmas. Data from copper deposits formed in ancient volcanoes at depths of up to about 1500 m in the fractures below paleo-fumaroles, and at around 2000–4000 m in association with sub-volcanic intrusions (porphyry copper deposits) provide evidence of sub-surface deposition of Cu–Au–Ag–Mo and a range of other minor elements including Te, Se, As and Sb. These deposits, or ‘sinks’, of metals consistently record sustained histories of magmatic gas streaming through volcanic systems interspersed by continuing intrusive and eruptive activity. Here we integrate data from ancient and modern volcanic systems and show that the fluxes of metals and metalloids are controlled by a) the maintenance of fracture permeability in the stressed crust below volcanoes and b) the chemical processes that are triggered as magmatic gas, initially undersaturated with metals and metalloids, expands from lithostatic to very low pressure conditions through fracture arrays. The recognition of gas streaming may also account for the phenomenon of ‘excess degassing’, and defines an integral, but generally understated, component of active volcanic systems – a volcanic gas core – that is likely to be integral to the progression of eruptions to Plinean state.Destabilization of solvated molecular metal and metalloid species in magmatic gas mixtures and changes in their redox state are triggered, as it expands to the surface by abrupt pressure drops, or throttles' in the fracture array that guides expansion to the surface. The electronically harder, low electronegativity metals, such as copper and iron, deposit rapidly in response to expansion followed more slowly by arsenic with antimony as sulfosalts. Heavy, large radius, softer elements such as bismuth, lead, and thallium

Evaluation of metals, metalloids, and ash mixture toxicity using sediment toxicity testing.

Science.gov (United States)

Stojak, Amber; Bonnevie, Nancy L; Jones, Daniel S

2015-01-01

In December 2008, a release of 4.1 million m(3) of coal ash from the Tennessee Valley Authority Kingston Fossil Plant occurred. Ash washed into the Emory River and migrated downstream into the Clinch and Tennessee Rivers. A Baseline Ecological Risk Assessment evaluated risks to ecological receptors from ash in the river system post-dredging. This article describes the approach used and results from sediment toxicity tests, discussing any causal relationships between ash, metals, and toxicity. Literature is limited in the realm of aquatic coal combustion residue (CCR) exposures and the potential magnitude of effects on benthic invertebrates. Sediment samples along a spectrum of ash content were used in a tiered toxicity testing approach and included a combination of 10 day sediment toxicity acute tests and longer-term, partial life cycle "definitive" tests with 2 species (Hyalella azteca and Chironomus dilutus). Arsenic, and to a lesser extent Se, in the ash was the most likely toxicant causing observed effects in the laboratory toxicity tests. Sites in the Emory River with the greatest statistical and biologically significant effects had As concentrations in sediments twice the probable effects concentration of 33 mg/kg. These sites contained greater than 50% ash. Sites with less than approximately 50% ash in sediments exhibited fewer significant toxic responses relative to the reference sediment in the laboratory. The results discussed here present useful evidence of only limited effects occurring from a worst-case exposure pathway. These results provided a valuable line of evidence for the overall assessment of risks to benthic invertebrates and to other ecological receptors, and were crucial to risk management and development of project remediation goals. © 2014 SETAC.

40 CFR 721.4668 - Hydrated alkaline earth metal salts of metalloid oxyanions.

Science.gov (United States)

2010-07-01

... metalloid oxyanions. 721.4668 Section 721.4668 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.4668 Hydrated alkaline earth metal salts of metalloid oxyanions. (a... hydrated alkaline earth metal salts of metalloid oxyanions (PMN P-94-1557) is subject to reporting under...

Comparative investigation on the spectroscopic properties of Pr3+-doped boro-phosphate, boro-germo-silicate and tellurite glasses

Science.gov (United States)

Zhang, Liaolin; Dong, Guoping; Peng, Mingying; Qiu, Jianrong

We report on the spectroscopic properties of Pr3+-doped boro-phosphate, boro-germo-silicate and tellurite glasses. The stimulated absorption and emission cross sections were estimated. Only one emission at 596 nm and 605 nm is observed in Pr3+-doped boro-phosphate and boro-germo-silicate glasses, respectively, while three emissions at 605 nm, 612 nm and 645 nm are observed in Pr3+-doped tellurite glass when excited at 467 nm. The fluorescence lifetime at 600 nm in Pr3+-doped boro-phosphate, boro-germo-silicate and tellurite glasses is 137 μs, 73 μs and 51 μs, respectively. The emissions from Pr3+-doped boro-phosphate, boro-germo-silicate and tellurite glasses show different decay behaviors and can be well explained by multiphonon relaxation theory.

Spectroscopic properties and thermal stability of Er3+-doped tungsten-tellurite glass for waveguide amplifier application

International Nuclear Information System (INIS)

Zhao Shilong; Wang Xiuli; Fang Dawei; Xu Shiqing; Hu Lili

2006-01-01

Tungsten-tellurite glass with molar composition of 60TeO 2 -30WO 3 -10Na 2 O has been investigated for developing planar broadband waveguide amplifier application. Spectroscopic properties and thermal stability of Er 3+ -doped tungsten-tellurite glass have been discussed. The results show that the introduction of WO 3 increases significantly the glass transition temperature and the maximum phonon energy. Er 3+ -doped tungsten-tellurite glass exhibits high glass transition temperature (377 deg. C), large emission cross-section (0.91 x 10 -20 cm 2 ) at 1532 nm and broad full width at half maximum (FWHM), which make it preferable for broadband Er 3+ -doped waveguide amplifier application

Linking Arsenic Metabolism and Toxic Effects

Science.gov (United States)

Although arsenic has been long recognized as a toxicant and a carcinogen, the molecular basis for few of its adverse effects are well understood. Like other metalloids, arsenic undergoes extensive metabolism involving oxidation state changes and formation of methyl-arsenic bonds ...

Metals, Metalloids and Radionuclides in the Baltic Sea Ecosystem

International Nuclear Information System (INIS)

Szefer, P.

2002-01-01

The state of knowledge of the distribution, bioavailability, biomagnification, discrimination, fate and sources of chemical pollutants (metals, metalloids, radionuclides and nutrients) in all compartments (atmosphere, water, deposits, biota) of the Baltic environment is presented. Particular components of the Baltic ecosystem are considered as potential monitors of pollutants. Budgets of chemical elements and the ecological status of the Baltic Sea in the past, present and future are presented. Estimates of health risks to man in respect to some toxic metals and radionuclides in fish and seafood are briefly discussed. The content of the book makes possible the identification of gaps in our environmental knowledge of the Baltic Sea, with certain sections establishing possible priorities, key areas or strategies for future research

Potential Biotechnological Strategies for the Cleanup of Heavy Metals and Metalloids

Directory of Open Access Journals (Sweden)

Kareem A. Mosa

2016-03-01

Full Text Available Global mechanization, urbanization and various natural processes have led to the increased release of toxic compounds into the biosphere. These hazardous toxic pollutants include a variety of organic and inorganic compounds, which pose a serious threat to the ecosystem. The contamination of soil and water are the major environmental concerns in the present scenario. This leads to a greater need for remediation of contaminated soils and water with suitable approaches and mechanisms. The conventional remediation of contaminated sites commonly involves the physical removal of contaminants, and their disposition. Physical remediation strategies are expensive, non-specific and often make the soil unsuitable for agriculture and other uses by disturbing the microenvironment. Owing to these concerns, there has been increased interest in eco-friendly and sustainable approaches such as bioremediation, phytoremediation and rhizomediation for the cleanup of contaminated sites. This review lays particular emphasis on biotechnological approaches and strategies for heavy metal and metalloid containment removal from the environment, highlighting the advances and implications of bioremediation and phytoremediation as well as their utilization in cleaning-up toxic pollutants from contaminated environments.

Optical properties of zinc lead tellurite glasses

Directory of Open Access Journals (Sweden)

Salah Hassan Alazoumi

2018-06-01

Full Text Available Tellurite glass systems in the form of [ZnO]x [(TeO20.7-(PbO0.3]1-x with x = 0.15, 0.17, 0.20, 0.22 and 0.25 mol% were prepared using the melt quenching technique. XRD of the prepared samples have been measured for all samples. Both FTIR (280–4000 cm−1 and UV-Vis (200–800 nm spectra have been measured. Optical band gap and refractive index were calculated for every glass sample. Density of glass, molar volume and oxygen packing density (OPD were obtained. Values of the direct, indirect band gap ranged were found in the range 3.41–3.94 eV and 2.40–2.63 eV with increasing of ZnO concentration. Refractive index 2.58 and dielectric constant 6.66 were heigh at 17 ZnO mol% concentration. Molar polarizability, metallization criterion, polaron radius have been calculated for every glass composition. Keywords: Tellurite, Glass, Optical band gap, Refractive index

Setting water quality criteria in China: approaches for developing species sensitivity distributions for metals and metalloids.

Science.gov (United States)

Liu, Yuedan; Wu, Fengchang; Mu, Yunsong; Feng, Chenglian; Fang, Yixiang; Chen, Lulu; Giesy, John P

2014-01-01

Both nonparametric and parametric approaches were used to construct SSDs for use in ecological risk assessments. Based on toxicity to representative aquatic species and typical water contaminants of metals and metalloids in China, nonparametric methods based on the bootstrap were statistically superior to the parametric curve-fitting approaches. Knowing what the SSDs for each targeted species are might help in selecting efficient indicator species to use for water quality monitoring. The species evaluated herein showed sensitivity variations to different chemical treatments that were used in constructing the SSDs. For example, D. magna was more sensitive than most species to most chemical treatments, whereas D. rerio was sensitive to Hg and Pb but was tolerant to Zn. HC5 values, derived for the pollutants in this study for protecting Chinese species, differed from those published by the USEPA. Such differences may result from differences in geographical conditions and biota between China and the United States. Thus, the degree of protection desired for aquatic organisms should be formulated to fit local conditions. For approach selection, we recommend all approaches be considered and the most suitable approaches chosen. The selection should be based on the practical information needs of the researcher (viz., species composition, species sensitivity, and geological characteristics of aquatic habitats), since risk assessments usually are focused on certain substances, species, or monitoring sites. We used Tai Lake as a typical freshwater lake in China to assess the risk of metals and metalloids to the aquatic species. We calculated hazard quotients for the metals and metalloids that were found in the water of this lake. Results indicated the decreasing ecological risk of these contaminants in the following order: Hg metalloids to aquatic species. Based on the MEC and HC5 derived from SSDs by nonparametric and parametric approaches together, the risk levels of metals

Critical V2O5/TeO2 Ratio Inducing Abrupt Property Changes in Vanadium Tellurite Glasses.

Science.gov (United States)

Kjeldsen, Jonas; Rodrigues, Ana C M; Mossin, Susanne; Yue, Yuanzheng

2014-12-26

Transition metal containing glasses have unique electrical properties and are therefore often used for electrochemical applications, such as in batteries. Among oxide glasses, vanadium tellurite glasses exhibit the highest electronic conductivity and thus the high potential for applications. In this work, we investigate how the dynamic and physical properties vary with composition in the vanadium tellurite system. The results show that there exists a critical V(2)O(5) concentration of 45 mol %, above which the local structure is subjected to a drastic change with increasing V(2)O(5), leading to abrupt changes in both hardness and liquid fragility. Electronic conductivity does not follow the expected correlation to the valence state of the vanadium as predicted by the Mott-Austin equation but shows a linear correlation to the mean distance between vanadium ions. These findings could contribute to designing optimum vanadium tellurite compositions for electrochemical devices. The work gives insight into the mechanism of electron conduction in the vanadium tellurite systems.

Role of organic amendments on enhanced bioremediation of heavy metal(loid) contaminated soils.

Science.gov (United States)

Park, Jin Hee; Lamb, Dane; Paneerselvam, Periyasamy; Choppala, Girish; Bolan, Nanthi; Chung, Jae-Woo

2011-01-30

As land application becomes one of the important waste utilization and disposal practices, soil is increasingly being seen as a major source of metal(loid)s reaching food chain, mainly through plant uptake and animal transfer. With greater public awareness of the implications of contaminated soils on human and animal health there has been increasing interest in developing technologies to remediate contaminated sites. Bioremediation is a natural process which relies on soil microorganisms and higher plants to alter metal(loid) bioavailability and can be enhanced by addition of organic amendments to soils. Large quantities of organic amendments, such as manure compost, biosolid and municipal solid wastes are used as a source of nutrients and also as a conditioner to improve the physical properties and fertility of soils. These organic amendments that are low in metal(loid)s can be used as a sink for reducing the bioavailability of metal(loid)s in contaminated soils and sediments through their effect on the adsorption, complexation, reduction and volatilization of metal(loid)s. This review examines the mechanisms for the enhanced bioremediation of metal(loid)s by organic amendments and discusses the practical implications in relation to sequestration and bioavailability of metal(loid)s in soils. Copyright © 2010 Elsevier B.V. All rights reserved.

Spatiotemporal distribution of airborne particulate metals and metalloids in a populated arid region

Science.gov (United States)

Prabhakar, Gouri; Sorooshian, Armin; Toffol, Emily; Arellano, Avelino F.; Betterton, Eric A.

2014-08-01

A statistical analysis of data from the Interagency Monitoring of Protected Visual Environments (IMPROVE) network of aerosol samplers has been used to study the spatial and temporal concentration trends in airborne particulate metals and metalloids for southern Arizona. The study region is a rapidly growing area in southwestern North America characterized by high fine soil concentrations (among the highest in the United States), anthropogenic emissions from an area within the fastest growing region in the United States, and a high density of active and abandoned mining sites. Crustal tracers in the region are most abundant in the summer (April-June) followed by fall (October-November) as a result of dry meteorological conditions which favor dust emissions from natural and anthropogenic activity. A distinct day-of-week cycle is evident for crustal tracer mass concentrations, with the greatest amplitude evident in urban areas. There have been significant reductions since 1988 in the concentrations of toxic species that are typically associated with smelting and mining. Periods with high fine soil concentrations coincide with higher concentrations of metals and metalloids in the atmosphere, with the enhancement being higher at urban sites.

Deriving site-specific soil clean-up values for metals and metalloids: rationale for including protection of soil microbial processes.

Science.gov (United States)

Kuperman, Roman G; Siciliano, Steven D; Römbke, Jörg; Oorts, Koen

2014-07-01

Although it is widely recognized that microorganisms are essential for sustaining soil fertility, structure, nutrient cycling, groundwater purification, and other soil functions, soil microbial toxicity data were excluded from the derivation of Ecological Soil Screening Levels (Eco-SSL) in the United States. Among the reasons for such exclusion were claims that microbial toxicity tests were too difficult to interpret because of the high variability of microbial responses, uncertainty regarding the relevance of the various endpoints, and functional redundancy. Since the release of the first draft of the Eco-SSL Guidance document by the US Environmental Protection Agency in 2003, soil microbial toxicity testing and its use in ecological risk assessments have substantially improved. A wide range of standardized and nonstandardized methods became available for testing chemical toxicity to microbial functions in soil. Regulatory frameworks in the European Union and Australia have successfully incorporated microbial toxicity data into the derivation of soil threshold concentrations for ecological risk assessments. This article provides the 3-part rationale for including soil microbial processes in the development of soil clean-up values (SCVs): 1) presenting a brief overview of relevant test methods for assessing microbial functions in soil, 2) examining data sets for Cu, Ni, Zn, and Mo that incorporated soil microbial toxicity data into regulatory frameworks, and 3) offering recommendations on how to integrate the best available science into the method development for deriving site-specific SCVs that account for bioavailability of metals and metalloids in soil. Although the primary focus of this article is on the development of the approach for deriving SCVs for metals and metalloids in the United States, the recommendations provided in this article may also be applicable in other jurisdictions that aim at developing ecological soil threshold values for protection of

Dietary intake and health effects of selected toxic elements

OpenAIRE

Silva, André Luiz Oliveira da; Barrocas, Paulo R.G.; Jacob, Silvana do Couto; Moreira, Josino Costa

2005-01-01

Anthropogenic activities have being contributing to the spread of toxic chemicals into the environment, including several toxic metals and metalloids, increasing the levels of human exposure to many of them. Contaminated food is an important route of human exposure and may represent a serious threat to human health. This mini review covers the health effects caused by toxic metals, especially Cd, Hg, Pb and As, the most relevant toxic elements from a human health point of view. As atividad...

Eriophorum angustifolium and Lolium perenne metabolic adaptations to metals- and metalloids-induced anomalies in the vicinity of a chemical industrial complex.

Science.gov (United States)

Anjum, Naser A; Ahmad, Iqbal; Rodrigues, Sónia M; Henriques, Bruno; Cruz, Nuno; Coelho, Cláudia; Pacheco, Mário; Duarte, Armando C; Pereira, Eduarda

2013-01-01

As plants constitute the foundation of the food chain, concerns have been raised about the possibility of toxic concentrations of metals and metalloids being transported from plants to the higher food chain strata. In this perspective, the use of important phytotoxicity endpoints may be of utmost significance in assessing the hazardous nature of metals and metalloids and also in developing ecological soil screening levels. The current study aimed to investigate the role of glutathione (GSH) and its associated enzymes in the metabolic adaptation of two grass species namely Eriophorum angustifolium Honck. and Lolium perenne L. to metals and metalloids stress in the vicinity of a chemical industrial complex (Estarreja, Portugal). Soil and plant samples were collected from contaminated (C) and non-contaminated (reference, R) sites, respectively, near and away from the Estarreja Chemical Complex, Portugal. Soils (from 0 to 10 and 10 to 20 cm depths) were analyzed for pH, organic carbon, and metals and metalloids concentrations. Plant samples were processed fresh for physiological and biochemical estimations, while oven-dried plant samples were used for metals and metalloids determinations following standard methodologies. Both soils and plants from the industrial area exhibited differential concentrations of major metals and metalloids including As, Cu, Hg, Pb, and Zn. In particular, L. perenne shoot displayed significantly higher and lower concentrations of Pb and As, respectively at contaminated site (vs. E. angustifolium). Irrespective of sites, L. perenne shoot exhibited significantly higher total GSH pool, oxidized glutathione (GSSG) and oxidized protein (vs. E. angustifolium). Additionally, severe damages to photosynthetic pigments, proteins, cellular membrane integrity (in terms of electrolyte leakage), and lipid peroxidation were also perceptible in L. perenne shoot. Contrarily, irrespective of the sites, activities of catalase and GSH-regenerating enzyme, GSH

Viscosity properties of tellurite-based glasses

International Nuclear Information System (INIS)

Tincher, B.; Massera, J.; Petit, L.; Richardson, K.

2010-01-01

The viscosity behavior of glasses with the composition (90-x)TeO 2 -10Bi 2 O 3 -xZnO with x = 15, 17.5, and 20 (TBZ glasses) and 80TeO 2 -(20-y)Na 2 O-yZnO system with y = 0, 5, and 10 (TNZ glasses) have been measured as a function of temperature using a beam-bending (BBV) and a parallel-plate (PPV) viscometer. The structure of the glass' network has been characterized using Raman spectroscopy and has been related to the viscosity temperature behavior and the fragility parameter (m) of the glasses. As the concentration of ZnO in the TBZ system (x) increases, the fragility parameter of the glass increases, whereas it decreases with an increase of the ZnO concentration (y) in the TNZ system. In both glasses, these variations in m have been related to the partial depolymerization of the tellurite network associated with the level of modifier content. The depolymerization of the tellurite network is believed to be the result of a reduction in the number of [TeO 4 ] units and the formation of [TeO 3 ] and [TeO 3+1 ] units that occurs with a change in TeO 2 content in the TBZ system and modifier content in the TNZ system.

Optical studies on Eu3+ doped boro-tellurite glasses

Science.gov (United States)

Maheshvaran, K.; Marimuthu, K.

2012-06-01

Eu3+ doped boro-tellurite glasses with the chemical composition (39-x)B2O3+30TeO2+15MgO+15K2O +xEu2O3 (where x = 0.01, 0.1, 1, 2 and 3 wt%) have been prepared by following conventional melt quenching technique. Spectroscopic properties of the Eu3+ doped boro-tellurite glasses have been studied by recording the optical absorption and luminescence measurements. Through the optical absorption spectra, bonding parameters (β¯, δ) have been calculated to identify the ionic/covalent nature of the glasses. Judd-Ofelt (JO) analysis have been carried out using the luminescence spectra. The JO parameters (Ωλ = 2, 4 and 6) were used to calculate the radiative properties for the 5D0 → 7FJ (J = 1, 2, 3 and 4) emission transitions of the Eu3+ ions. The change in optical properties with the variation of Eu3+ ion concentration have been studied and discussed with similar studies.

Comparative investigation on the spectroscopic properties of Pr³⁺-doped boro-phosphate, boro-germo-silicate and tellurite glasses.

Science.gov (United States)

Zhang, Liaolin; Dong, Guoping; Peng, Mingying; Qiu, Jianrong

2012-07-01

We report on the spectroscopic properties of Pr(3+)-doped boro-phosphate, boro-germo-silicate and tellurite glasses. The stimulated absorption and emission cross sections were estimated. Only one emission at 596 nm and 605 nm is observed in Pr(3+)-doped boro-phosphate and boro-germo-silicate glasses, respectively, while three emissions at 605 nm, 612 nm and 645 nm are observed in Pr(3+)-doped tellurite glass when excited at 467 nm. The fluorescence lifetime at 600 nm in Pr(3+)-doped boro-phosphate, boro-germo-silicate and tellurite glasses is 137 μs, 73 μs and 51 μs, respectively. The emissions from Pr(3+)-doped boro-phosphate, boro-germo-silicate and tellurite glasses show different decay behaviors and can be well explained by multiphonon relaxation theory. Copyright © 2012 Elsevier B.V. All rights reserved.

Total and cytosolic concentrations of twenty metals/metalloids in the liver of brown trout Salmo trutta (Linnaeus, 1758) from the karstic Croatian river Krka.

Science.gov (United States)

Dragun, Zrinka; Filipović Marijić, Vlatka; Krasnići, Nesrete; Ivanković, Dušica; Valić, Damir; Žunić, Jakov; Kapetanović, Damir; Smrzlić, Irena Vardić; Redžović, Zuzana; Grgić, Ivana; Erk, Marijana

2018-01-01

Total and cytosolic concentrations of twenty metals/metalloids in the liver of brown trout Salmo trutta (Linnaeus, 1758) were studied in the period from April 2015 to May 2016 at two sampling sites on Croatian river Krka, to establish if river water contamination with metals/metalloids downstream of Knin town has influenced metal bioaccumulation in S. trutta liver. Differences were observed between two sites, with higher concentrations of several elements (Ag, As, Ca, Co, Na, Se, Sr, V) found downstream of Knin town, whereas few others (Cd, Cs, Mo, Tl) were, unexpectedly, increased at the Krka River spring. However, total metal/metalloid concentrations in the liver of S. trutta from both sites of the Krka River were still mainly below previously reported levels for pristine freshwaters worldwide. The analysis of seasonal changes of metal/metalloid concentrations in S. trutta liver and their association with fish sex and size mostly indicated their independence of fish physiology, making them good indicators of water contamination and exposure level. Metal/metalloid concentrations in the metabolically available hepatic cytosolic fractions reported in this study are the first data of that kind for S. trutta liver, and the majority of analyzed elements were present in the cytosol in the quantity higher than 50% of their total concentrations, thus indicating their possible availability for toxic effects. However, the special attention should be directed to As, Cd, Cs, and Tl, which under the conditions of increased exposure tended to accumulate more within the cytosol. Although metal/metalloid concentrations in S. trutta liver were still rather low, monitoring of the Krka River water quality and of the health status of its biota is essential due to a trend of higher metal/metalloid bioaccumulation downstream of Knin town, especially taking into consideration the proximity of National Park Krka and the need for its conservation. Copyright © 2017 Elsevier Inc. All

Optical aging observation in suspended core tellurite microstructured fibers under atmospheric conditions

Science.gov (United States)

Strutynski, C.; Mouawad, O.; Picot-Clémente, J.; Froidevaux, P.; Désévédavy, F.; Gadret, G.; Jules, J.-C.; Kibler, B.; Smektala, F.

2017-11-01

Tellurite glasses are good candidates for the development of broadband supercontinuum (SC) laser sources in the 1-5 μm range. At the moment, beside very few exceptions, SC generation in TeO2-based microstructured optical fibers (MOFs) is limited to 3 μm in the mid-infrared (MIR). We present here an observation of an optical aging occurring in six-hole suspended-core tellurite MOFs. When exposed to atmospheric conditions, such fibers show an alteration of their transmission between 3 and 4 μm. This aging phenomenon leads to the growth of strong additional losses in this wavelengths range over time. Impact of the transmission degradation on spectral broadening is studied through numerical simulations of SC generation.

The electronic and optical properties of germanium tellurite glasses containing various transition metal oxides

International Nuclear Information System (INIS)

Khan, M.N.

1988-01-01

Various transition metal oxides, such as TiO 2 , V 2 O 5 , NiO, CuO, and ZnO are added to germanium-tellurite glass and measurements are reported of the electrical conductivity, density, optical absorption, infra-red absorption spectra, and electron spin resonance. It is found that the d.c. conductivity of glasses containing the same amount of V 2 O 5 is higher than that of germanium tellurite glasses containing a similar amount of other transition metal oxides, and is due to hopping between localized states. The optical absorption measurements show that the fundamental absorption edge is a function of glass composition and the optical absorption is due to forbidden indirect transitions. From the infra-red absorption spectra, it is found that the addition of transition metal oxides does not introduce any new absorption band in the infra-red spectrum of germanium tellurite glasses. A small shift of existing absorptions toward higher wave number is observed. The ESR measurements revealed that some transition metal ions are diamagnetic while others are paramagnetic in the glass network. (author)

Glass Transition Temperature- and Specific Volume- Composition Models for Tellurite Glasses

Energy Technology Data Exchange (ETDEWEB)

Riley, Brian J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Vienna, John D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

2017-09-01

This report provides models for predicting composition-properties for tellurite glasses, namely specific gravity and glass transition temperature. Included are the partial specific coefficients for each model, the component validity ranges, and model fit parameters.

The associations between metals/metalloids concentrations in blood plasma of Hong Kong residents and their seafood diet, smoking habit, body mass index and age.

Science.gov (United States)

Qin, Yan Yan; Leung, Clement Kai Man; Lin, Che Kit; Wong, Ming Hung

2015-09-01

The concentrations of metals/metalloids in blood plasma collected from 111 healthy residents (51 female, 60 male) in Hong Kong (obtained from the Hong Kong Red Cross Blood Transfusion Service, from March to April 2008) were quantified by means of a double-focusing sector field inductively coupled plasma optical emission spectrometer (ICP-OES). Results showed that concentrations of these toxic metals such as Hg, Cd, and Pb in Hong Kong residents were not serious when compared with other countries. Males accumulated significantly higher (p diet habit, body mass index (BMI), and age. More intensive studies involving more samples are needed before a more definite conclusion can be drawn, especially on the causal relationships between concentrations of metals/metalloids with dietary preference and lifestyle of the general public.

Optical spectroscopy of rare earth-doped oxyfluoro-tellurite glasses ...

Indian Academy of Sciences (India)

2017-08-16

Aug 16, 2017 ... glass matrix with different RE ions for optical properties is of importance. ... Figure 1. XRD pattern of the tellurite glasses studied. Table 1. Composition and glass transition ... convoluted using Gaussian line shape. Parameters like .... On the other hand, in Er3+ ion, the ground state 4I15/2 itself has manifold.

Faraday rotation influence factors in tellurite-based glass and fibers

Energy Technology Data Exchange (ETDEWEB)

Chen, Qiuling; Wang, Qingwei [Henan University of Technology, School of Materials Science and Engineering, Zhengzhou, Henan (China); Wang, Hui; Chen, Qiuping [Politecnico di Torino, Department of Applied Science and Technology, Turin (Italy)

2015-09-15

The Faraday rotation influence factors in tellurite-based glass and fibers were studied by experiments and simulations. TeO{sub 2}-ZnO-Na{sub 2}O-BaO glass family was fabricated and characterized in terms of the thermal and magneto-optical properties. Two core-cladding pairs for two fibers were selected from fabricated glasses. The Verdet constants of the glasses and fibers were measured at different wavelengths using a homemade optical bench, and the Verdet constant of fiber was close to that of the bulk glass. The influence from external factors (wavelength, laser power and magnetic field) and internal factors (thermal expansion coefficient difference, refractive index and Verdet constant of core and cladding) on Faraday rotation in fibers was investigated and discussed, and the purpose of this study is to improve the Faraday rotation in tellurite fibers for MO device applications both from internal material property match and external parameter configuration in measurement. (orig.)

Faraday rotation influence factors in tellurite-based glass and fibers

International Nuclear Information System (INIS)

Chen, Qiuling; Wang, Qingwei; Wang, Hui; Chen, Qiuping

2015-01-01

The Faraday rotation influence factors in tellurite-based glass and fibers were studied by experiments and simulations. TeO 2 -ZnO-Na 2 O-BaO glass family was fabricated and characterized in terms of the thermal and magneto-optical properties. Two core-cladding pairs for two fibers were selected from fabricated glasses. The Verdet constants of the glasses and fibers were measured at different wavelengths using a homemade optical bench, and the Verdet constant of fiber was close to that of the bulk glass. The influence from external factors (wavelength, laser power and magnetic field) and internal factors (thermal expansion coefficient difference, refractive index and Verdet constant of core and cladding) on Faraday rotation in fibers was investigated and discussed, and the purpose of this study is to improve the Faraday rotation in tellurite fibers for MO device applications both from internal material property match and external parameter configuration in measurement. (orig.)

Structure of zinc and niobium tellurite glasses by neutron and x-ray diffraction

Science.gov (United States)

Hoppe, U.; Yousef, E.; Rüssel, C.; Neuefeind, J.; Hannon, A. C.

2004-03-01

Neutron and x-ray diffraction experiments of high resolving power with neutrons from a spallation source and high-energy photons from a synchrotron have been performed on compositional series of binary Zn, Nb and on mixed Zn/Nb tellurite glasses. The Te-O, Zn-O and Nb-O coordination numbers are determined by Gaussian fitting of the first-neighbour peaks in the neutron and x-ray data simultaneously. The transition of TeO4 to TeO3 units with increasing fraction of a second component is indicated by decreasing total Te-O coordination numbers. This transition appears different for glasses with ZnO or Nb2O5 additions. Details of the Te-O peaks suggest there are two species of Te-O bonds with lengths of {\\sim }0.19 and {\\sim }0.21 nm. The change of their fractions shows excellent agreement with the existence of TeO4 trigonal bipyramids and TeO3 trigonal pyramids. All oxygen atoms from ZnO and Nb2O5 are used for rupture of Te-O-Te bridges, which is accompanied with a change of nearly all participating TeO4 to TeO3 groups. The tendency for a {\\mathrm {TeO}}_{4} \\to {\\mathrm {TeO}}_{3} change decreases for glasses of higher second component content which is accompanied by the occurrence of TeO4 groups with non-bridging oxygens. The Nb tellurite glasses show transition to network-forming behaviour with the formation of Nb-O-Nb bridges. The fractions of TeO3 units of ternary Zn/Nb tellurite glasses agree with an additivity behaviour of the modifying effects of ZnO and Nb2O5 additions. Some of these results have already been presented in thesis work: Yousef E 2003 A study of some physical properties of tellurite glass (Al-Azhar University, Assiut Egypt).

Structural investigation and simulation of acoustic properties of some tellurite glasses using artificial intelligence technique

International Nuclear Information System (INIS)

Gaafar, M.S.; Abdeen, Mostafa A.M.; Marzouk, S.Y.

2011-01-01

Research highlights: → Simulation the acoustic properties of some tellurite glasses using one of the artificial intelligence techniques (artificial neural network). → The glass network is strengthened by enhancing the linkage of Te-O chains. The tellurite network will also come to homogenization, because of uniform distribution of Nb 5+ ions among the Te-O chains, though some of the tellurium-oxide polyhedra still link each other in edge sharing. → Excellent agreements between the measured values and the predicted values were obtained for over 50 different tellurite glass compositions. → The model we designed gives a better agreement as compared with Makishima and Machenzie model. - Abstract: The developments in the field of industry raise the need for simulating the acoustic properties of glass materials before melting raw material oxides. In this paper, we are trying to simulate the acoustic properties of some tellurite glasses using one of the artificial intelligence techniques (artificial neural network). The artificial neural network (ANN) technique is introduced in the current study to simulate and predict important parameters such as density, longitudinal and shear ultrasonic velocities and elastic moduli (longitudinal and shear moduli). The ANN results were found to be in successful good agreement with those experimentally measured parameters. Then the presented ANN model is used to predict the acoustic properties of some new tellurite glasses. For this purpose, four glass systems xNb 2 O 5 -(1 - x)TeO 2 , 0.1PbO-xNb 2 O 5 -(0.9 - x)TeO 2 , 0.2PbO-xNb 2 O 5 -(0.8 - x)TeO 2 and 0.05Bi 2 O 3 -xNb 2 O 5 -(0.95 - x)TeO 2 were prepared using melt quenching technique. The results of ultrasonic velocities and elastic moduli showed that the addition of Nb 2 O 5 as a network modifier provides oxygen ions to change [TeO 4 ] tbps into [TeO 3 ] tps.

Structural investigation and simulation of acoustic properties of some tellurite glasses using artificial intelligence technique

Energy Technology Data Exchange (ETDEWEB)

Gaafar, M.S., E-mail: mohamed_s_gaafar@hotmail.com [Ultrasonic Department, National Institute for Standards, Giza (Egypt); Physics Department, Faculty of Science, Majmaah University, Zulfi (Saudi Arabia); Abdeen, Mostafa A.M., E-mail: mostafa_a_m_abdeen@hotmail.com [Dept. of Eng. Math. and Physics, Faculty of Eng., Cairo University, Giza (Egypt); Marzouk, S.Y., E-mail: samir_marzouk2001@yahoo.com [Arab Academy of Science and Technology, Al-Horria, Heliopolis, Cairo (Egypt)

2011-02-24

Research highlights: > Simulation the acoustic properties of some tellurite glasses using one of the artificial intelligence techniques (artificial neural network). > The glass network is strengthened by enhancing the linkage of Te-O chains. The tellurite network will also come to homogenization, because of uniform distribution of Nb{sup 5+} ions among the Te-O chains, though some of the tellurium-oxide polyhedra still link each other in edge sharing. > Excellent agreements between the measured values and the predicted values were obtained for over 50 different tellurite glass compositions. > The model we designed gives a better agreement as compared with Makishima and Machenzie model. - Abstract: The developments in the field of industry raise the need for simulating the acoustic properties of glass materials before melting raw material oxides. In this paper, we are trying to simulate the acoustic properties of some tellurite glasses using one of the artificial intelligence techniques (artificial neural network). The artificial neural network (ANN) technique is introduced in the current study to simulate and predict important parameters such as density, longitudinal and shear ultrasonic velocities and elastic moduli (longitudinal and shear moduli). The ANN results were found to be in successful good agreement with those experimentally measured parameters. Then the presented ANN model is used to predict the acoustic properties of some new tellurite glasses. For this purpose, four glass systems xNb{sub 2}O{sub 5}-(1 - x)TeO{sub 2}, 0.1PbO-xNb{sub 2}O{sub 5}-(0.9 - x)TeO{sub 2}, 0.2PbO-xNb{sub 2}O{sub 5}-(0.8 - x)TeO{sub 2} and 0.05Bi{sub 2}O{sub 3}-xNb{sub 2}O{sub 5}-(0.95 - x)TeO{sub 2} were prepared using melt quenching technique. The results of ultrasonic velocities and elastic moduli showed that the addition of Nb{sub 2}O{sub 5} as a network modifier provides oxygen ions to change [TeO{sub 4}] tbps into [TeO{sub 3}] tps.

Quantitative analysis of some important metals and metalloids in tobacco products by inductively coupled plasma-mass spectrometry (ICP-MS)

Science.gov (United States)

2012-01-01

Background Large scale usage of tobacco causes a lot of health troubles in human. Various formulations of tobacco are extensively used by the people particularly in developing world. Besides several toxic tobacco constituents some metals and metalloids are also believed to pose health risks. This paper describes inductively coupled plasma-mass spectrometric (ICP-MS) quantification of some important metals and metalloids in various brands of smoked, sniffed, dipped and chewed tobacco products. Results A microwave-assisted digestion method was used for sample preparation. The method was validated by analyzing a certified reference material. Percentage relative standard deviation (% R.S.D.) between recovered and certified values was  r > 0.999. Improved limits of detection (LODs) were in range of ng/L for all elements. Fe, Al and Mn were found to be in the highest concentration in all types of tobacco products, while Zn, Cu, Ni and Cr were below the average concentration of 40 μg/g, and Pb, Co, As, Se and Cd were below 5 μg/g. All elements, apart from Pb, were high in concentration in dipping tobacco in comparison to other tobacco products. Generally, the order of all elemental concentration can be expressed in different tobacco products as chewing metalloids in a wide spectrum of tobacco formulations. The outcome of this study would be beneficial for health authorities and individuals. PMID:22709464

Enhancing the Electronic Conductivity of Vanadium-tellurite Glasses by Tuning the Redox State

DEFF Research Database (Denmark)

Kjeldsen, Jonas; Yue, Yuanzheng

Transition metal oxides are used in a variety of electronic purposes, e.g., vanadium tellurite as cathode material in high-power demanding batteries. By tuning the redox state of vanadium, it is possible to achieve a lower internal resistance within the entire battery unit, thus a higher capacity....... In this work we vary the redox state of a given vanadium tellurite system by performing post heat-treatment in controlled atmosphere. This process is in theory not limited only to varying electronic conductivity, but also varying the glass structure, and hence, changing properties of the glasses, e.g, thermal...... and mechanical properties. Finally we give insight into the relation between the redox state and electronic conductivity....

The glass-forming ability of model metal-metalloid alloys

Energy Technology Data Exchange (ETDEWEB)

Zhang, Kai; Liu, Yanhui; Schroers, Jan [Department of Mechanical Engineering and Materials Science, Yale University, New Haven, Connecticut 06520 (United States); Center for Research on Interface Structures and Phenomena, Yale University, New Haven, Connecticut 06520 (United States); Shattuck, Mark D. [Department of Physics and Benjamin Levich Institute, The City College of the City University of New York, New York, New York 10031 (United States); Department of Mechanical Engineering and Materials Science, Yale University, New Haven, Connecticut 06520 (United States); O’Hern, Corey S. [Department of Mechanical Engineering and Materials Science, Yale University, New Haven, Connecticut 06520 (United States); Center for Research on Interface Structures and Phenomena, Yale University, New Haven, Connecticut 06520 (United States); Department of Physics, Yale University, New Haven, Connecticut 06520 (United States); Department of Applied Physics, Yale University, New Haven, Connecticut 06520 (United States)

2015-03-14

Bulk metallic glasses (BMGs) are amorphous alloys with desirable mechanical properties and processing capabilities. To date, the design of new BMGs has largely employed empirical rules and trial-and-error experimental approaches. Ab initio computational methods are currently prohibitively slow to be practically used in searching the vast space of possible atomic combinations for bulk glass formers. Here, we perform molecular dynamics simulations of a coarse-grained, anisotropic potential, which mimics interatomic covalent bonding, to measure the critical cooling rates for metal-metalloid alloys as a function of the atomic size ratio σ{sub S}/σ{sub L} and number fraction x{sub S} of the metalloid species. We show that the regime in the space of σ{sub S}/σ{sub L} and x{sub S} where well-mixed, optimal glass formers occur for patchy and LJ particle mixtures, coincides with that for experimentally observed metal-metalloid glass formers. Thus, our simple computational model provides the capability to perform combinatorial searches to identify novel glass-forming alloys.

Energy transfer induced Eu{sup 3+} photoluminescence enhancement in tellurite glass

Energy Technology Data Exchange (ETDEWEB)

Stambouli, W. [Laboratoire des Materiaux Mineraux et leurs Applications, Centre National de Recherches en Sciences des Materiaux, B.P. 95, Hammam-Lif 2050 (Tunisia); Elhouichet, H., E-mail: habib.elhouichet@fst.rnu.tn [Laboratoire des Materiaux Mineraux et leurs Applications, Centre National de Recherches en Sciences des Materiaux, B.P. 95, Hammam-Lif 2050 (Tunisia); Departement de Physique, Faculte des Sciences de Tunis, Universite de Tunis-ElManar ElManar 2092, Tunis (Tunisia); Gelloz, B. [Graduate School of Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Nakacho, Koganei, 184-8588 Tokyo (Japan); Ferid, M. [Laboratoire des Materiaux Mineraux et leurs Applications, Centre National de Recherches en Sciences des Materiaux, B.P. 95, Hammam-Lif 2050 (Tunisia); Koshida, N. [Graduate School of Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Nakacho, Koganei, 184-8588 Tokyo (Japan)

2012-01-15

In this work, structural, thermal and optical properties of Eu{sup 3+} doped TeO{sub 2}-La{sub 2}O{sub 3}-TiO{sub 2} glass were investigated. The differential scanning calorimetry (DSC) measurements reveal an important stability factor {Delta}T=143.52 K, which indicates the good thermal and mechanical stabilities of tellurite glass. From the absorption spectrum, the optical band gap was found to be direct with E{sub g}=3.23 eV. The temperature dependences of photoluminescence (PL) properties of Eu-doped and Eu-Tb codoped tellurite glass are investigated. As the temperature increases from 7 to 300 K, both the PL intensity and the PL lifetime relative to the {sup 5}D{sub 2}{yields}{sup 7}F{sub 0} are nearly constant below 230 K and then an enhancement takes place. This anomalous feature is attributed to the thermally activated carrier transfer process from charged intrinsic defects states to Eu{sup 3+} energy levels. By co-doping tellurite glasses with Eu and Tb, a strong Eu{sup 3+} PL enhancement is shown due to excitation transfer from Tb{sup 3+} and intrinsic defects to Eu ions. - Highlights: > TeO{sub 2}-La{sub 2}O{sub 3}-TiO{sub 2} glass doped Eu{sup 3+} with good thermal stability elaborated. > PL evolution of Eu{sup 3+} with temperature shows a non-conventional behavior. > Thermally activated carrier transfer from intrinsic defects states to Eu{sup 3+} shown. > Strong Eu{sup 3+} PL enhancement is shown in Eu-Tb codoped glass.

Distribution of metals and metalloids in dried seaweeds and health risk to population in southeastern China.

Science.gov (United States)

Chen, Qing; Pan, Xiao-Dong; Huang, Bai-Fen; Han, Jian-Long

2018-02-23

Concern about metals and metalloids, especially heavy metals in seaweeds has risen due to potential health risk. This study investigated the distribution of 10 metals and metalloids in 295 dried seaweeds (brown and red) and estimated the possible health risk via hazard index (HI). Elements in seaweeds can be sequenced in descending order by mean values: Al > Mn > As > Cu > Cr > Ni > Cd > Se > Pb > Hg. The levels of Cd, Cu, Mn and Ni in red seaweeds were significantly higher than those in brown seaweeds (P < 0.01). Correlation analysis showed contents of Ni-Cr (r = 0.59, P < 0.01) in seaweeds had moderate positive correlations. Seaweeds from different geographical origins had diverse element distribution. Risk assessment showed that HI at mean level was less than the threshold of 1. It indicates that for the general people there is low health risk to these elements by the intake of seaweeds. Furthermore, in terms of the confirmative toxicity of some metals, such as Cd, Pb and Hg, surveillance of metals in seaweeds should be performed continuously.

Polarographic behaviour and determination of selenite and tellurite in simple solutions or in a binary mixture

International Nuclear Information System (INIS)

Hassan, A.

1991-01-01

The polarographic behaviour of simple solutions of selenite and tellurite in 1 M ammonium salts of formate, acetate, tartrate, oxalate, and benzoate solutions in absence and in presence of Triton X-100 as a maximum suppressor and a temperature of 25 O C has been investigated. Schemes for the mechanism of reductions occuring at the DME have been deduced. A method for analytical determination of selenite and tellurite in simple solutions as well as in a binary mixture in the presence of 4-14 . 10 -3 % Triton X-100 is reported. (author)

Effects of different drying processes on the concentrations of metals and metalloids in plant materials

International Nuclear Information System (INIS)

Anawar, H.M.; Canha, N.; Freitas, M.C; Santa Regina, I.; Garcia-Sanchez, A.

2011-01-01

The drying process of fresh plant materials may affect the porous structure, dehydration and a number of quality characteristics of these materials. Therefore, this study has investigated the effect of different drying processes on the variation of metal and metalloid concentrations in the dried plant materials. Seven varieties of native plant species collected from Sao Domingos mine were analyzed by instrumental neutron activation analysis (INAA) to investigate the effects of freeze-drying (FD), ambient air-drying (AAD) and oven-drying (OD) process on the concentrations of metals and metalloids in the plant biomass. Comparison of ambient air-dried, oven-dried and freeze-dried preparations allows a phenomenological description of the dehydration artefacts. In the quantitative analysis of metals and metalloids, FD and OD plant samples show the higher concentrations of metals and metalloids when compared to those in the AAD plant biomass. The freeze-drying process is comparatively reliable for determination of metals and metalloids concentrations in plant materials. (author)

SELENIUM MODIFIES THE METABOLISM AND TOXICITY OF ARSENIC IN PRIMARY RAT HEPATOCYTES

Science.gov (United States)

ABSTRACTSelenium Modifies the Metabolism and Toxicity of Arsenic in Primary Rat Hepatocytes. Miroslav Styblo, David J. Thomas (2000) Toxicol. Appl. Pharmacol. Arsenic and selenium are metalloids with similar chemical properties and metabolic fates. Inorganic arsenic (iAs...

The filter feeder Dreissena polymorpha affects nutrient, silicon, and metal(loid) mobilization from freshwater sediments.

Science.gov (United States)

Schaller, Jörg; Planer-Friedrich, Britta

2017-05-01

Organic sediments in aquatic ecosystems are well known sinks for nutrients, silicon, and metal(loid)s. Organic matter-consuming organisms like invertebrate shredders, grazers, and bioturbators significantly affect element fixation or remobilization by changing redox conditions or binding properties of organic sediments. Little is known about the effect of filter feeders, like the zebra mussel Dreissena polymorpha, an invasive organism in North American and European freshwater ecosystems. A laboratory batch experiment exposing D. polymorpha (∼1200 organisms per m 2 ) to organic sediment from a site contaminated with arsenic, copper, lead, and uranium revealed a significant uptake and accumulation of arsenic, copper, iron, and especially uranium both into the soft body tissues and the seashell. This is in line with previous observations of metal(loid) accumulation from biomonitoring studies. Regarding its environmental impact, D. polymorpha significantly contributed to mobilization of silicon, iron, phosphorus, arsenic, and copper and to immobilization of uranium (p < 0.001), probably driven by redox conditions, microbial activity within the gut system, or active control of element homeostasis. No net mobilization or immobilization was observed for zinc and lead, because of their low mobility at the prevailing pH of 7.5-8.5. The present results suggest that D. polymorpha can both ameliorate (nutrient mobilization, immobilization of toxicants mobile under oxic conditions) or aggravate negative effects (mobilization of toxicants mobile under reducing conditions) in ecosystems. Relating the results of the present study to observed population densities in natural freshwater ecosystems suggests a significant influence of D. polymorpha on element cycling and needs to be considered in future studies. Copyright © 2017 Elsevier Ltd. All rights reserved.

Silver nanoparticles enhanced 1.53 µm band fluorescence of Er{sup 3+}/Yb{sup 3+} codoped tellurite glasses

Energy Technology Data Exchange (ETDEWEB)

Qi, Yawei; Zhou, Yaxun, E-mail: zhouyaxun@nbu.edu.cn; Wu, Libo; Yang, Fengjing; Peng, Shengxi; Zheng, Shichao; Yin, Dandan

2014-09-15

The silver nanoparticles (NPs) was introduced into the Er{sup 3+}/Yb{sup 3+} codoped tellurite glasses with composition of TeO{sub 2}–ZnO to improve the 1.53 µm band fluorescence of Er{sup 3+} and the thermal stability of glass host. The UV–Vis–NIR absorption spectra, 1.53 µm band fluorescence spectra and fluorescence decaying curves, the differential scanning calorimeter (DSC) curves, X-ray diffraction (XRD) patterns and transmission electron microscopy (TEM) images of glass samples were characterized to investigate the effect of silver NPs on the fluorescence properties of Er{sup 3+}, thermal stability and structure behavior of glass host. It is shown that the Er{sup 3+}/Yb{sup 3+} codoped tellurite glass emits intense 1.53 µm band fluorescence with peak wavelength located at about 1532 nm under the 980 nm excitation. The introduction of silver NPs further improves the fluorescence intensity of Er{sup 3+} which is attributed to the enhanced local electric field effect induced by localized surface Plasmon resonance (LSPR) of silver NPs and the possible energy transfer from silver NPs to Er{sup 3+}. An improvement by about 62% of 1.5{sup 3} µm band fluorescence intensity was found in the studied Er{sup 3+}/Yb{sup 3+} codoped tellurite glass containing 0.5 mol% amount of AgNO{sub 3}. In addition, the thermal stability of glass host increases with the introduction of silver NPs while the glass structure maintains the amorphous nature. The present results indicate that the prepared Er{sup 3+}/Yb{sup 3+} codoped tellurite glass with an appropriate amount of silver NPs has good prospect as a gain medium applied for 1.53 µm band broad and high-gain erbium-doped fiber amplifiers (EDFAs). - Highlights: • Tellurite glass with Er{sup 3+}/Yb{sup 3+} and silver NPs was prepared by melt-quenching method. • Silver NPs with average size of 12 nm and Plasmon band at 560 nm was observed. • Addition of silver NPs increased the thermal stability of tellurite glass. �

Optical Properties of Bismuth Tellurite Based Glass

Directory of Open Access Journals (Sweden)

Hooi Ming Oo

2012-04-01

Full Text Available A series of binary tellurite based glasses (Bi2O3x (TeO2100−x was prepared by melt quenching method. The density, molar volume and refractive index increase when bismuth ions Bi3+ increase, this is due to the increased polarization of the ions Bi3+ and the enhanced formation of non-bridging oxygen (NBO. The Fourier transform infrared spectroscopy (FTIR results show the bonding of the glass sample and the optical band gap, Eopt decreases while the refractive index increases when the ion Bi3+ content increases.

Optical Properties of Bismuth Tellurite Based Glass

Science.gov (United States)

Oo, Hooi Ming; Mohamed-Kamari, Halimah; Wan-Yusoff, Wan Mohd Daud

2012-01-01

A series of binary tellurite based glasses (Bi2O3)x (TeO2)100−x was prepared by melt quenching method. The density, molar volume and refractive index increase when bismuth ions Bi3+ increase, this is due to the increased polarization of the ions Bi3+ and the enhanced formation of non-bridging oxygen (NBO). The Fourier transform infrared spectroscopy (FTIR) results show the bonding of the glass sample and the optical band gap, Eopt decreases while the refractive index increases when the ion Bi3+ content increases. PMID:22605999

Metal(loid) allocation and nutrient retranslocation in Pinus halepensis trees growing on semiarid mine tailings

Energy Technology Data Exchange (ETDEWEB)

Parraga-Aguado, Isabel, E-mail: isabel.parraga@upct.es [Universidad Politecnica de Cartagena, Departamento de Ciencia y Tecnología Agraria Paseo Alfonso XIII, Cartagena 48. 30203 (Spain); Querejeta, Jose-Ignacio [Water and Soil Conservation Department, Centro de Edafología y Biología Aplicada del Segura CEBAS-CSIC Campus Universitario de Espinardo, PO Box 164, Espinardo-Murcia ES-30100 (Spain); González-Alcaraz, María Nazaret; Conesa, Hector M. [Universidad Politecnica de Cartagena, Departamento de Ciencia y Tecnología Agraria Paseo Alfonso XIII, Cartagena 48. 30203 (Spain)

2014-07-01

The goal of this study was to evaluate internal metal(loid) cycling and the risk of metal(loid) accumulation in litter from Pinus halepensis trees growing at a mine tailing disposal site in semiarid Southeast Spain. Internal nutrient retranslocation was also evaluated in order to gain insight into the ability of pine trees to cope with the low-fertility soil conditions at the tailings. We measured metal(loid) concentrations in the foliage (young and old needles), woody stems and fresh leaf litter of pine trees growing on tailings. The nutrient status and stable isotope composition of pine foliage (δ{sup 13}C, δ{sup 15}N, δ{sup 18}O as indicators of photosynthesis and water use efficiency) were also analyzed. Tailing soil properties in vegetation patches and in adjacent bare soil patches were characterized as well. Significant amounts of metal(loid)s such us Cd, Cu, Pb and Sb were immobilized in the woody stems of Pinus halepensis trees growing on tailings. Leaf litterfall showed high concentrations of As, Cd, Sb, Pb and Zn, which thereby return to the soil. However, water extractable metal(loid) concentrations in tailing soils were similar between vegetation patches (mineral soil under the litter layer) and bare soil patches. The pines growing on mine tailings showed very low foliar P concentrations in all leaf age classes, which suggests severe P deficiency. Young (current year) needles showed lower accumulation of metal(loid)s, higher nutrient concentrations (P and K), and higher water use efficiency (as indicated by and δ{sup 13}C and δ{sup 18}O data) than older needles. Substantial nutrient resorption occurred before leaf litterfall, with 46% retranslocation efficiency for P and 89% for K. In conclusion, phytostabilization of semiarid mine tailings with Pinus halepensis is feasible but would require careful monitoring of the trace elements released from litterfall, in order to assess the long term risk of metal(loid) transfer to the food chain

Metal(loid) allocation and nutrient retranslocation in Pinus halepensis trees growing on semiarid mine tailings

International Nuclear Information System (INIS)

Parraga-Aguado, Isabel; Querejeta, Jose-Ignacio; González-Alcaraz, María Nazaret; Conesa, Hector M.

2014-01-01

The goal of this study was to evaluate internal metal(loid) cycling and the risk of metal(loid) accumulation in litter from Pinus halepensis trees growing at a mine tailing disposal site in semiarid Southeast Spain. Internal nutrient retranslocation was also evaluated in order to gain insight into the ability of pine trees to cope with the low-fertility soil conditions at the tailings. We measured metal(loid) concentrations in the foliage (young and old needles), woody stems and fresh leaf litter of pine trees growing on tailings. The nutrient status and stable isotope composition of pine foliage (δ 13 C, δ 15 N, δ 18 O as indicators of photosynthesis and water use efficiency) were also analyzed. Tailing soil properties in vegetation patches and in adjacent bare soil patches were characterized as well. Significant amounts of metal(loid)s such us Cd, Cu, Pb and Sb were immobilized in the woody stems of Pinus halepensis trees growing on tailings. Leaf litterfall showed high concentrations of As, Cd, Sb, Pb and Zn, which thereby return to the soil. However, water extractable metal(loid) concentrations in tailing soils were similar between vegetation patches (mineral soil under the litter layer) and bare soil patches. The pines growing on mine tailings showed very low foliar P concentrations in all leaf age classes, which suggests severe P deficiency. Young (current year) needles showed lower accumulation of metal(loid)s, higher nutrient concentrations (P and K), and higher water use efficiency (as indicated by and δ 13 C and δ 18 O data) than older needles. Substantial nutrient resorption occurred before leaf litterfall, with 46% retranslocation efficiency for P and 89% for K. In conclusion, phytostabilization of semiarid mine tailings with Pinus halepensis is feasible but would require careful monitoring of the trace elements released from litterfall, in order to assess the long term risk of metal(loid) transfer to the food chain. - Highlights: • Significant

Solid state field-assisted diffusion of silver in multi-component tellurite glasses

Czech Academy of Sciences Publication Activity Database

Stepanov, B.; Ren, J.; Wágner, T.; Lorinčík, Jan; Frumar, M.; Churbanov, M.; Chigirinsky, Y.

2011-01-01

Roč. 357, č. 15 (2011), 3022-3026 ISSN 0022-3093 Institutional research plan: CEZ:AV0Z20670512 Keywords : Solid state diffusion * Secondary Ion Mass Spectrometry * Tellurite glass Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 1.537, year: 2011

Solid State Field-Assisted Diffusion of Copper in Multi-Component Tellurite Glass

Czech Academy of Sciences Publication Activity Database

Stepanov, B.; Ren, J.; Wágner, T.; Lorinčík, Jan; Frumar, M.; Churbanov, M.; Chigirinsky, Y.

2011-01-01

Roč. 94, č. 7 (2011), 1986-1988 ISSN 0002-7820 Institutional research plan: CEZ:AV0Z20670512 Keywords : Solid state diffusion * Secondary Ion Mass Spectrometry * Tellurite glass Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 2.272, year: 2011

Acute toxicity of metals and reference toxicants to a freshwater ostracod, Cypris subglobosa Sowerby, 1840 and correlation to EC50 values of other test models

International Nuclear Information System (INIS)

Khangarot, B.S.; Das, Sangita

2009-01-01

The ostracod Cypris subglobosa Sowerby, 1840 static bioassay test on the basis of a 48 h of 50% of immobilization (EC 50 ) has been used to measure the toxicity of 36 metals and metalloids and 12 reference toxicants. Among the 36 metals and metalloids, osmium (Os) was found to be the most toxic in the test while boron (B), the least toxic. The EC 50 values of this study revealed positive linear relationship with the established test models of cladoceran (Daphnia magna), sludge worm (Tubifex tubifex), chironomid larvae (Chironomus tentans), protozoan (Tetrahymena pyriformis), fathead minnow (Pimephales promelas), bluegill sunfish (Lepomis macrochirus), and aquatic macrophyte duckweed (Lemna minor). Correlation coefficients (r 2 ) for 17 physicochemical properties of metals or metal ions and EC 50 s (as pM) were examined by linear regression analysis. The electronegativity, ionization potential, melting point, solubility product of metal sulfides (pK sp ), softness parameter and some other physicochemical characteristics were significantly correlated with EC 50 s of metals to C. subglobosa. The reproducibility of toxicity test was determined using 12 reference toxicants. The coefficient of variability of the EC 50 s ranged from 6.95% to 55.37% and variability was comparable to that noticed for D. magna and other aquatic test models. The study demonstrated the need to include crustacean ostracods in a battery of biotests to detect the presence of hazardous chemicals in soils, sewage sludges, sediments and aquatic systems.

Metals and metalloids in PM10 in Nandan County, Guangxi, China, and the health risks posed.

Science.gov (United States)

Guo, Guanghui; Song, Bo; Xia, Deshang; Yang, Zijie; Wang, Fopeng

2018-03-16

Intense mining, smelting, and tailing activities of polymetallic ore deposits have affected the environment in Nandan County, Guangxi, China. Samples of particulates with aerodynamic diameters low or equal 10 μm (PM 10 ) were collected in Nandan County to investigate the concentrations of and health risks posed by 17 metals and metalloids in the PM 10 . The metal and metalloid concentrations were lower than those found in other industrial cities. The mean Cr concentration was 7.48 ng/m 3 . Significant higher metal and metalloid concentrations were found in PM 10 from mining areas (Dachang and Chehe) than from the control area (Liuzhai) (p metalloids in PM 10 at all the sites were low, but the non-carcinogenic risks posed to children by all the metals and metalloids together exceeded the safe level (i.e., risk value > 1). The carcinogenic risks posed by Cd, Ni, and Pb were negligible at all sites, while As, Co, and Cr posed potential carcinogenic risks to the residents.

Remediation of Heavy Metal(loid)s Contaminated Soils – To Mobilize or To Immobilize?

Science.gov (United States)

Unlike organic contaminants, metal(loid)s do not undergo microbial or chemical degradation and persist for a long time after their introduction. Bioavailability of metal(loid)s plays a vital role in the remediation of contaminated soils. In this review, the remediation of heavy ...

Sorption of V and VI group metalloids (As, Sb, Te on modified peat sorbents

Directory of Open Access Journals (Sweden)

Ansone-Bertina Linda

2016-01-01

Full Text Available The present work investigates arsenic, antimony and tellurium sorption using iron modified peat. The results were obtained using batch tests and the sorption was studied as a function of initial metalloid concentration, pH and sorption time, as well as the presence of competing substances. The obtained results indicate that modification of peat with Fe compounds significantly enhances the sorption capacity of the sorbents used for sorption of arsenic, antimony and tellurium. The optimal pH interval for the sorption of Sb(III is 6.5–9 and for As(V and Sb(V – 3–6, while As(III and tellurium sorption using Fe-modified peat is favourable in a wider interval of 3–9. The presence of competing ions as well as HA affect sorption of metalloids on Fe-modified peat. A minor impact on the reduction of metalloid sorption was detected in the presence of nitrate, sulphate, carbonate and tartrate ions, while in the presence of phosphate and HA the sorption ability of metalloids can be considerably reduced. The obtained results of kinetic experiments indicate that sorption of metalloids on Fe-modified peat mainly occurs relying on mechanisms of physical sorption processes.

Acute toxicity of metals and reference toxicants to a freshwater ostracod, Cypris subglobosa Sowerby, 1840 and correlation to EC{sub 50} values of other test models

Energy Technology Data Exchange (ETDEWEB)

Khangarot, B.S., E-mail: bkhangarot@hotmail.com [Ecotoxicology Division, Indian Institute of Toxicology Research (Formerly: Industrial Toxicology Research Centre), Post Box No. 80, Mahatma Gandhi Marg, Lucknow 226001 (India); Das, Sangita [Ecotoxicology Division, Indian Institute of Toxicology Research (Formerly: Industrial Toxicology Research Centre), Post Box No. 80, Mahatma Gandhi Marg, Lucknow 226001 (India)

2009-12-30

The ostracod Cypris subglobosa Sowerby, 1840 static bioassay test on the basis of a 48 h of 50% of immobilization (EC{sub 50}) has been used to measure the toxicity of 36 metals and metalloids and 12 reference toxicants. Among the 36 metals and metalloids, osmium (Os) was found to be the most toxic in the test while boron (B), the least toxic. The EC{sub 50} values of this study revealed positive linear relationship with the established test models of cladoceran (Daphnia magna), sludge worm (Tubifex tubifex), chironomid larvae (Chironomus tentans), protozoan (Tetrahymena pyriformis), fathead minnow (Pimephales promelas), bluegill sunfish (Lepomis macrochirus), and aquatic macrophyte duckweed (Lemna minor). Correlation coefficients (r{sup 2}) for 17 physicochemical properties of metals or metal ions and EC{sub 50}s (as pM) were examined by linear regression analysis. The electronegativity, ionization potential, melting point, solubility product of metal sulfides (pK{sub sp}), softness parameter and some other physicochemical characteristics were significantly correlated with EC{sub 50}s of metals to C. subglobosa. The reproducibility of toxicity test was determined using 12 reference toxicants. The coefficient of variability of the EC{sub 50}s ranged from 6.95% to 55.37% and variability was comparable to that noticed for D. magna and other aquatic test models. The study demonstrated the need to include crustacean ostracods in a battery of biotests to detect the presence of hazardous chemicals in soils, sewage sludges, sediments and aquatic systems.

Tellurite composite microstructured optical fibers with ultra-flattened and zero dispersion

Science.gov (United States)

Duan, Zhongchao; Liao, Meisong; Tomas, Kohoutek; Tong, Hoangtuan; Asano, Koji; Suzuki, Takenobu; Ohishi, Yasutake

2012-04-01

We report the fabrication of tellurite composite microstructured optical fiber (CMOF) with ultra-flattened zero dispersion (+/-3 ps/nm/Km) over 200nm band. To obtain this dispersion profile together with high nonlinearity, one ring of air holes and two layers of glass cladding are employed in the tellurite CMOF. The core of fiber is made of TeO2-Li2O-WO3 -MoO3-Nb2O5 (TLWMN) tellurite glass which possesses high linear and nonlinear refractive indices. The refractive index (n) at 1544nm and nonlinear refractive index (n2) of TLWMN glass is 2.08 and 3.78×10-11 esu, respectively. TeO2-ZnO-Na2O-La2O3 (TZNL) glass with n of 1.96 at 1544 nm and TeO2-ZnO-Li2O-Na2O-P2O5 (TZLNP) glass with low refractive index n of 1.63 at 1544 nm are used as the first cladding and the second cladding, respectively. Six small air holes are located between the core and the first glass cladding. Such kind of fiber with ~1.7 μm core and ~0.6 μm air holes are fabricated by a rod-in-tube method. The chromatic dispersion of the fiber is calculated by the fully vectorial finite difference method (FV-FDM) and becomes (+/-3 ps/nm/Km) in the wide range from 1.53 μm to 1.72 μm. And the nonlinear coefficient of present fiber is about 3.47 m-1W-1 which is much higher than that of silica MOFs. Furthermore, broad and flattened supercontinuum generation is demonstrated in 30-cm-long fiber with femtosecond laser pumping at 1557 nm. This kind of fiber has promising potential in nonlinear applications owing to the high nonlinearity and flattened dispersion profile.

Assessing ecotoxicity and uptake of metals and metalloids in relation to two different earthworm species (Eiseina hortensis and Lumbricus terrestris).

Science.gov (United States)

Leveque, Thibaut; Capowiez, Yvan; Schreck, Eva; Mazzia, Christophe; Auffan, Mélanie; Foucault, Yann; Austruy, Annabelle; Dumat, Camille

2013-08-01

Due to diffuse atmospheric fallouts of process particles enriched by metals and metalloids, polluted soils concern large areas at the global scale. Useful tools to assess ecotoxicity induced by these polluted soils are therefore needed. Earthworms are currently used as biotest, however the influence of specie and earthworm behaviour, soil characteristics are poorly highlighted. Our aim was therefore to assess the toxicity of various polluted soils with process particles enriches by metals and metalloids (Pb, Cd, Cu, Zn, As and Sb) collected from a lead recycling facility on two earthworm species belonging to different ecological types and thus likely to have contrasted behavioural responses (Eiseina hortensis and Lumbricus terrestris). The combination of behavioural factors measurements (cast production and biomass) and physico-chemical parameters such as metal absorption, bioaccumulation by earthworms and their localization in invertebrate tissues provided a valuable indication of pollutant bioavailability and ecotoxicity. Soil characteristics influenced ecotoxicity and metal uptake by earthworms, as well as their soil bioturbation. Copyright © 2013 Elsevier Ltd. All rights reserved.

Luminescence studies on Dy3+ doped calcium boro-tellurite glasses for White light applications

Science.gov (United States)

Karthikeyan, P.; Vijayakumar, R.; Marimuthu, K.

2017-09-01

A new series of Dy3+ doped calcium boro-tellurite glasses have been prepared by melt quenching technique and their spectroscopic properties were studied through FTIR, absorption luminescence and lifetime spectral measurements. FTIR studies have been made to explore the presence of various stretching and bending vibrations of different borate and tellurite groups in the prepared glasses. The bonding parameter values were estimated from the absorption band positions using Nephelauxetic ratios to examine the nature of the metal-ligand bond. The optical band gap and Urbach energy (ΔE) values were obtained from the absorption spectra to explore the electronic band structure of the studied glasses. Judd-Ofelt (JO) theory have been used to determine the JO intensity parameters (Ω2, Ω4, Ω6) following the least square fitting procedure between the experimental and calculated oscillator strength values. The luminescence spectra of the Dy3+ doped calcium boro-tellurite glasses exhibit two intense emission bands corresponding to the 4F9/2→6H15/2 and 4F9/2→6H13/2 transitions. Further, they exhibit less intense emission band due to the 4F9/2→6H11/2 transition. Luminescence spectra were characterized through CIE 1931 chromaticity diagram to obtain the dominant emission color of the prepared glasses. The JO intensity parameters and refractive index values have been used to calculate the radiative parameters such as transition probabilities (AR), branching ratios (βR) and stimulated emission cross-section (σPE) values for the observed transitions in the luminescence spectra. The decay curves of all the studied glasses found to exhibit non-exponential behavior and further to understand the energy transfer process takes place between the Dy3+ ions, the decay curves were fitted to the Inokuti-Hirayama (IH) model. The structural and optical properties of the Dy3+ doped calcium boro-tellurite glasses have been studied as a function of different metal cations (Zn, Cd, Pb and

Influence of Organic Matter - Mineral Interfacial Reactions on Metal(loid) Speciation and Bioaccessibility

Science.gov (United States)

Chorover, J.; Kong, S.; Root, R. A.; Thomas, A.

2015-12-01

Bioaccessibility of contaminant metals in geomedia is often measured on the basis of kinetic release to solution during in vitro reaction with biofluid simulants. We postulate that development of a predictive-mechanistic understanding of bioaccessibility requires knowledge of metal(loid) molecular speciation upon sample introduction, as well as its change over the course of the in vitro reaction. Our results - including data from batch, column, mesocosm and field studies pertaining to arsenic, lead, and zinc contaminated materials - indicate the strong influence of organic matter and associated biological activity on metal(loid) speciation in mine tailings and related model systems. Furthermore, presence/absence of organic matter during bioassays affects the kinetics of metal(loid) release into biofluid simulants through multiple mechanisms.

Soliton self-frequency shift controlled by a weak seed laser in tellurite photonic crystal fibers.

Science.gov (United States)

Liu, Lai; Meng, Xiangwei; Yin, Feixiang; Liao, Meisong; Zhao, Dan; Qin, Guanshi; Ohishi, Yasutake; Qin, Weiping

2013-08-01

We report the first demonstration of soliton self-frequency shift (SSFS) controlled by a weak continuous-wave (CW) laser, from a tellurite photonic crystal fiber pumped by a 1560 nm femtosecond fiber laser. The control of SSFS is performed by the cross-gain modulation of the 1560 nm femtosecond laser. By varying the input power of the weak CW laser (1560 nm) from 0 to 1.17 mW, the soliton generated in the tellurite photonic crystal fiber blue shifts from 1935 to 1591 nm. The dependence of the soliton wavelength on the operation wavelength of the weak CW laser is also measured. The results show the CW laser with a wavelength tunable range of 1530-1592 nm can be used to control the SSFS generation.

Fragility–structure–conductivity relations in vanadium tellurite glass

DEFF Research Database (Denmark)

Kjeldsen, Jonas; Yue, Yuanzheng; Rodrigues, Ana Candida Martins

the ability to intercalate lithium-ions, it is a candidate as cathode material. Here, we investigate the correlation between liquid fragility, structure and electronic conductivity in a series of vanadium-tellurite glasses with varying vanadium concentration. We measure dynamic and thermodynamic fragility...... the number of bonding and non-bonding oxygen atoms per network former, while we use IS and ESR to determine the electronic conductivity and the valence states of the system. We correlate the changes in local atomic structures as determined by NMR to the observed changes in macroscopic properties. Since...

Solitonic supercontinuum of femtosecond mid-IR pulses in W-type index tellurite fibers with two zero dispersion wavelengths

Directory of Open Access Journals (Sweden)

S. Kedenburg

2016-11-01

Full Text Available We present a detailed experimental parameter study on mid-IR supercontinuum generation in W-type index tellurite fibers, which reveals how the core diameter, pump wavelength, fiber length, and pump power dramatically influence the spectral broadening. As pump source, we use femtosecond mid-IR pulses from a post-amplified optical parametric oscillator tunable between 1.7 μm and 4.1 μm at 43 MHz repetition rate. We are able to generate red-shifted dispersive waves up to a wavelength of 5.1 μm by pumping a tellurite fiber in the anomalous dispersion regime between its two zero dispersion wavelengths. Distinctive soliton dynamics can be identified as the main broadening mechanism resulting in a maximum spectral width of over 2000 nm with output powers of up to 160 mW. We experimentally demonstrated that efficient spectral broadening with considerably improved power proportion in the important first atmospheric transmission window between 3 and 5 μm can be achieved in robust W-type tellurite fibers pumped at long wavelengths by ultra-fast lasers.

Bioreduction of selenite and tellurite by Phanerochaete chrysosporium

NARCIS (Netherlands)

Espinosa‐Ortiz, E.J.

2015-01-01

Selenium (Se) and tellurium (Te) are elements, they are part of the chalcogens (VI‐A group of the periodic table) and share common properties. These metalloids are of commercial interest due to their physicochemical properties, and they have been used in a broad range of applications in advanced

Toxicity assessment using Lactuca sativa L. bioassay of the metal(loid)s As, Cu, Mn, Pb and Zn in soluble-in-water saturated soil extracts from an abandoned mining site

Energy Technology Data Exchange (ETDEWEB)

Bagur-Gonzalez, Maria Gracia [Univ. of Granada, Faculty of Sciences, Dept. of Analytical Chemistry, Granada (Spain); Univ. of Granada-CSIC, Inst. Andaluz de Ciencias de la Tierra, Faculty of Sciences, Granada (Spain); Estepa-Molina, Carmen [Univ. of Granada, Faculty of Sciences, Dept. of Mineralogy and Petrology, Granada (Spain); Martin-Peinado, Francisco [Univ. of Granada, Faculty of Sciences, Dept. of Soil Science, Granada (Spain); Morales-Ruano, Salvador [Univ. of Granada-CSIC, Inst. Andaluz de Ciencias de la Tierra, Faculty of Sciences, Granada (Spain); Univ. of Granada, Faculty of Sciences, Dept. of Mineralogy and Petrology, Granada (Spain)

2011-02-15

We used the different soluble-in-water concentrations of As, Cu, Mn, Pb and Zn from contaminated soils in an abandoned mining area (anthropogenic origin) to assess the phytotoxicity of the abandoned site using the results obtained with a Lactuca sativa L. bioassay. Material and methods The study has been carried out on potentially polluted samples from the Rodalquilar mining district (southern Spain). The area was sampled according to the different metallurgical treatments for gold extraction used in each one: dynamic cyanidation and heap leaching. The saturation extracts were obtained by filtering each saturated paste with a vacuum-extraction pump, in which measurements of metal(loid) concentrations, pH and electrical conductivity were made. The variables evaluated in the bioassay, defined as toxicity indices ranging from -1 (maximum phytotoxicity) to >0 (hormesis), were seed germination (SG) and root elongation (RE) of lettuce seeds. Results and discussion In areas with a low degree of contamination, the most sensitive toxicity index is RE, whereas in highly contaminated areas, both RE and SG are good estimators of soil toxicity. According to these results, samples from the western area showed moderate to low toxicity, which was closely related to water-soluble As concentrations. Samples from the eastern area had a high degree of toxicity in 40% of the soils. Conclusions The comparison of the two indices (SG and RE) defined using the L. sativa L. bioassay indicates that, for areas with a low degree of contamination, the most sensitive toxicity index is RE, whereas in highly contaminated areas, both RE and SG are good estimators of soil phytotoxicity. Unsupervised pattern recognition methods such as HCA and PCA enabled us to conclude that the low/moderate phytotoxicity of the soils is related to the extraction process used for the recovery of gold (mainly dynamic cyanidation in tanks located in the eastern area) and to the As and Pb contents. (orig.)

Effect of silver nanoparticles on the 1.53 μm fluorescence in Er3+/Yb3+ codoped tellurite glasses

Science.gov (United States)

Wu, Libo; Zhou, Yaxun; Zhou, Zizhong; Cheng, Pan; Huang, Bo; Yang, Fengjing; Li, Jun

2016-07-01

Improving the spectroscopic properties of rare earth (RE) doped glass materials is a challenging task. In the present work the metallic silver nanoparticles (Ag NPs) were embedded into Er3+/Yb3+ codoped tellurite glasses with composition TeO2-Bi2O3-TiO2, prepared using melt-quenching and subsequent heat-treated techniques, and the improved effect of Ag NPs on the 1.53 μm band fluorescence of Er3+ ions was investigated. About 24 h heat-treatment of Er3+/Yb3+ codoped tellurite glass containing 1 mol % amount of AgNO3 at the temperature 370 °C yielded the well-dispersed and near-spherical Ag NPs with ∼11.4 nm average diameter as evidenced by transmission electron microscopy (TEM) image. The intense 1.53 μm band fluorescence was observed in the prepared Er3+/Yb3+ codoped tellurite glasses under the excitation of 980 nm and was further improved with the presence of Ag NPs in the glass matrix, which is attributed to the enhanced local electric field around doped RE ions induced by Ag NPs and the possible energy transfer from Ag NPs to Er3+ ions. The enhanced local electric field was well demonstrated by comparing the variation of emission spectra of hypersensitive probe Eu3+ ions in tellurite glasses with and without Ag NPs. From the Judd-Ofelt analysis, it was also found that the value of Ω6 intensity parameter increased slightly with the increase of Ag NPs concentration in a certain range, also confirming the possibility of realizing strong fluorescence emission. In addition, the amorphous structural nature was demonstrated by the measured X-ray diffraction (XRD) patterns with no sharp diffraction peak. The enhanced 1.53 μm band fluorescence indicates that the Er3+/Yb3+ codoped tellurite glass with an appropriate amount of Ag NPs is a promising candidate for the development of Er3+-doped fiber amplifiers (EDFAs) applied in the WDM systems.

Bioaccumulation of metals and metalloids in medicinal plant Ipomoea pes-caprae from areas impacted by tsunami.

Science.gov (United States)

Kozak, Lidia; Kokociński, Mikołaj; Niedzielski, Przemysław; Lorenc, Stanisław

2015-02-01

Tsunami events may have an enormous impact on the functioning of aquatic and terrestrial ecosystems by altering various relationships with biotic components. Concentrations of acid-leachable fractions of heavy metals and metalloids in soils and plant samples from areas affected by the December 2004 tsunami in Thailand were determined. Ipomoea pes-caprae, a common plant species growing along the seashore of this region, and frequently used in folk medicine, was selected to assess the presence of selected elements. Elevated amounts of Cd, Pb, Zn, and As in soil samples, and Pb, Zn, As, Se, Cr, and Ni in plant samples were determined from the tsunami-impacted regions for comparison with reference locations. The flowers of Ipomoea pes-caprae contained the highest amounts of these metals, followed by its leaves, and stems. In addition, its bioaccumulation factor (BAF) supports this capability of high metal uptake by Ipomoea pes-caprae from the areas affected by the tsunami in comparison with a reference site. This uptake was followed by the translocation of these elements to the various plant components. The presence of these toxic metals in Ipomoea pes-caprae growing in contaminated soils should be a concern of those who use this plant for medicinal purposes. Further studies on the content of heavy metals and metalloids in this plant in relation to human health concerns are recommended. © 2014 SETAC.

Green manure plants for remediation of soils polluted by metals and metalloids: ecotoxicity and human bioavailability assessment.

Science.gov (United States)

Foucault, Y; Lévêque, T; Xiong, T; Schreck, E; Austruy, A; Shahid, M; Dumat, C

2013-10-01

Borage, white mustard and phacelia, green manure plants currently used in agriculture to improve soil properties were cultivated for 10 wk on various polluted soils with metal(loid) concentrations representative of urban brownfields or polluted kitchen gardens. Metal(loid) bioavailability and ecotoxicity were measured in relation to soil characteristics before and after treatment. All the plants efficiently grow on the various polluted soils. But borage and mustard only are able to modify the soil characteristics and metal(loid) impact: soil respiration increased while ecotoxicity, bioaccessible lead and total metal(loid) quantities in soils can be decreased respectively by phytostabilization and phytoextraction mechanisms. These two plants could therefore be used for urban polluted soil refunctionalization. However, plant efficiency to improve soil quality strongly depends on soil characteristics. Copyright © 2013. Published by Elsevier Ltd.

Evaluation of silkworm excrement and mushroom dreg for the remediation of multiple heavy metal/metalloid contaminated soil using pakchoi.

Science.gov (United States)

Wang, Ruigang; Guo, Junkang; Xu, Yingming; Ding, Yongzhen; Shen, Yue; Zheng, Xiangqun; Feng, Renwei

2016-02-01

The economical, environmental friendly and efficient materials to remediate the pollution with multiple heavy metals and metalloids are scarce. Silkworm excrement (SE) and mushroom dregs (MD) are two types of agricultural wastes, and they are widely used to improve the soil fertility in many regions of China. A pot experiment with sixteen treatments was set up to assess the possibility of using SE and MD to stabilize heavy metals and metalloids and reduce their uptake in pakchoi cultivated in slightly contaminated soils with arsenic (As), cadmium (Cd), lead (Pb) and zinc (Zn). The results showed that the single addition of SE obviously stimulated the growth of pakchoi, reduced the contents of all tested heavy metals and metalloids in the edible part of pakchoi and availability of Zn and Cd in soil. The single MD treatment showed an inferior ability to enhance the growth and reduce the contents of heavy metals and metalloids in the edible part of pakchoi. The combined utilization of SE and MD appeared not to show better effects than their individual treatment when using them to remediate this contaminated soil. Some potential mechanisms on the stimulation on pakchoi growth and decreasing the accumulation of heavy metals and metalloids in pakchoi subjected to SE were suggested, including: (1) enhancing soil pH to impact the availability of heavy metals and metalloids; (2) improve the fertility of soil; (3) sulfhydryl groups of organic materials in SE play a role in conjugating heavy metals and metalloids to affect their availability in soil; and (4) stimulating the growth of pakchoi so as to show a "dilution effect" of heavy metals and metalloids. Copyright © 2015 Elsevier Inc. All rights reserved.

Optical Properties of Erbium Zinc Tellurite Glass System

Directory of Open Access Journals (Sweden)

Sidek Hj. Abdul Aziz

2015-01-01

Full Text Available Er3+-doped tellurite glasses with molar compositions of xEr2O3-20ZnO-(80-xTeO2 (x=0, 1, 2, 3, and 4 mole% (EZT have been successfully synthesized by the melt-quenching method. Density and molar volume have been measured. UV-VIS absorption spectra in the wavelength range of 400–800 nm at room temperature has been measured. The band gap for every composition has been calculated. Photoluminescence spectroscopy in the wavelength range of 400–650 nm and at room temperature has been evaluated.

Structural and spectroscopic studies on Er3+ doped boro-tellurite glasses

Science.gov (United States)

Selvaraju, K.; Marimuthu, K.

2012-04-01

Er3+ doped boro-tellurite glasses with the chemical composition (69-x)B2O3-xTeO2-15MgO-15K2O-1Er2O3 (where x=0, 10, 20, 30 and 40 wt%) have been prepared and their structural and spectroscopic behavior were studied and reported. The varying tellurium dioxide content in the host matrix that results, changes in structural and spectroscopic behavior around Er3+ ions are explored through XRD, FTIR, UV-VIS-NIR and luminescence measurements. The XRD pattern confirms the amorphous nature of the prepared glasses and the FTIR spectra explore the fundamental groups and the local structural units in the prepared boro-tellurite glasses. The bonding parameters (βbar and δ) have been calculated from the observed band positions of the absorption spectra to claim the ionic/covalent nature of the prepared glasses. The Judd-Ofelt (JO) intensity parameters Ωλ (λ=2, 4 and 6) were determined through experimental and calculated oscillator strengths obtained from the absorption spectra and their results are studied and compared with reported literature. The variation in the JO parameters Ωλ (λ=2, 4 and 6) with the change in chemical composition have been discussed in detail. The JO parameters have also been used to derive the important radiative properties like transition probability (A), branching ratio (βR) and peak stimulated emission cross-section (σPE) for the excited state transitions 2H9/2→4I15/2 and 2H11/2 and 4S3/2→4I15/2 of the Er3+ ions and the results were studied and reported. Using Davis and Mott theory, optical band gap energy (Eopt) values for the direct and indirect allowed transitions have been calculated and discussed along with the Urbach energy values for the prepared Er3+ doped boro-tellurite glasses in the present study. The optical properties of the prepared glasses with the change in tellurium dioxide have been studied and compared with similar results.

Plasma-based techniques applied to the determination of metals and metalloids in atmospheric aerosols

International Nuclear Information System (INIS)

Smichowski, Patricia

2011-01-01

Full text: This lecture presents an overview of the research carried out by our group during the last decade on the determination of metals, metalloids, ions and species in atmospheric aerosols and related matrices using plasma-based techniques. In our first studies we explored the application of a size fractionation procedure and the subsequent determination of minor, major and trace elements in samples of deposited particles collected one day after the eruption of the Copahue Volcano, located in the Chile-Argentina border to assess the content of relevant elements with respect of the environment and the local population health. We employed a multi-technique approach (ICP-MS, XRD and NAA) to gain complete information of the characteristics of the sample. In addition to the study of ashes emitted for natural sources we also studied ashes of anthropogenic origin such as those arising from coal combustion in thermal power plants. For estimating the behavior and fate of elements in atmospheric particles and ashes we applied in this case a chemical fractionation procedure in order to establish the distribution of many elements amongst soluble, bound to carbonates, bound to oxides and bound to organic matter and environmental immobile fraction. Studies on the air quality of the mega-city of Buenos Aires were scarce and fragmentary and our objective was, and still is, to contribute to clarify key issues related to levels of crustal, toxic and potentially toxic elements in this air basin. Our findings were compared with average concentrations of metals and metalloids with results reported for other Latin American cities such as Sao Paulo, Mexico and Santiago de Chile. In this context, a series of studies were carried out since 2004 considering different sampling strategies to reflect local aspects of air pollution sources. In the last years, our interest was focused on the levels of traffic-related elements in the urban atmosphere. We have contributed with the first data

Plasma-based techniques applied to the determination of metals and metalloids in atmospheric aerosols

Energy Technology Data Exchange (ETDEWEB)

Smichowski, Patricia, E-mail: smichows@cnea.gov.ar [Comision Nacional de Energia Atomica, Gerencia Quimica, Pcia de Buenos Aires (Argentina)

2011-07-01

Full text: This lecture presents an overview of the research carried out by our group during the last decade on the determination of metals, metalloids, ions and species in atmospheric aerosols and related matrices using plasma-based techniques. In our first studies we explored the application of a size fractionation procedure and the subsequent determination of minor, major and trace elements in samples of deposited particles collected one day after the eruption of the Copahue Volcano, located in the Chile-Argentina border to assess the content of relevant elements with respect of the environment and the local population health. We employed a multi-technique approach (ICP-MS, XRD and NAA) to gain complete information of the characteristics of the sample. In addition to the study of ashes emitted for natural sources we also studied ashes of anthropogenic origin such as those arising from coal combustion in thermal power plants. For estimating the behavior and fate of elements in atmospheric particles and ashes we applied in this case a chemical fractionation procedure in order to establish the distribution of many elements amongst soluble, bound to carbonates, bound to oxides and bound to organic matter and environmental immobile fraction. Studies on the air quality of the mega-city of Buenos Aires were scarce and fragmentary and our objective was, and still is, to contribute to clarify key issues related to levels of crustal, toxic and potentially toxic elements in this air basin. Our findings were compared with average concentrations of metals and metalloids with results reported for other Latin American cities such as Sao Paulo, Mexico and Santiago de Chile. In this context, a series of studies were carried out since 2004 considering different sampling strategies to reflect local aspects of air pollution sources. In the last years, our interest was focused on the levels of traffic-related elements in the urban atmosphere. We have contributed with the first data

Selenite and tellurite form mixed seleno- and tellurotrisulfides with CstR from Staphylococcus aureus.

Science.gov (United States)

Luebke, Justin L; Arnold, Randy J; Giedroc, David P

2013-04-01

Staphylococcus aureus CstR (CsoR-like sulfur transferase repressor) is a member of the CsoR family of transition metal sensing metalloregulatory proteins. Unlike CsoR, CstR does not form a stable complex with transition metals but instead reacts with sulfite to form a mixture of di- and trisulfide species, CstR2(RS-SR') and CstR2(RS-S-SR')n)n=1 or 2, respectively. Here, we investigate if CstR performs similar chemistry with related chalcogen oxyanions selenite and tellurite. In this work we show by high resolution tandem mass spectrometry that CstR is readily modified by selenite (SeO3(2-)) or tellurite (TeO3(2-)) to form a mixture of intersubunit disulfides and selenotrisulfides or tellurotrisulfides, respectively, between Cys31 and Cys60'. Analogous studies with S. aureus CsoR reveals no reaction with selenite and minimal reaction with tellurite. All cross-linked forms of CstR exhibit reduced DNA binding affinity. We show that Cys31 initiates the reaction with sulfite through the formation of S-sulfocysteine (RS-SO3(2-)) and Cys60 is required to fully derivatize CstR to CstR2(RS-SR') and CstR2(RS-S-SR'). The modification of Cys31 also drives an allosteric switch that negatively regulates DNA binding while derivatization of Cys60 alone has no effect on DNA binding. These results highlight the differences between CstRs and CsoRs in chemical reactivity and metal ion selectivity and establish Cys31 as the functionally important cysteine residue in CstRs.

Assessment of lead tellurite glass for immobilizing electrochemical salt wastes from used nuclear fuel reprocessing

Energy Technology Data Exchange (ETDEWEB)

Riley, Brian J.; Kroll, Jared O.; Peterson, Jacob A.; Pierce, David A.; Ebert, William L.; Williams, Benjamin D.; Snyder, Michelle M. V.; Frank, Steven M.; George, Jaime L.; Kruska, Karen

2017-11-01

This paper provides an overview of research evaluating the use of lead tellurite glass as a waste form for salt wastes from electrochemical reprocessing of used nuclear fuel. The efficacy of using lead tellurite glass to immobilize three different salt compositions was evaluated: a LiCl-Li2O oxide reduction salt containing fission products from oxide fuel, a LiCl-KCl eutectic salt containing fission products from metallic fuel, and SrCl2. Physical and chemical properties of glasses made with these salts were characterized with X-ray diffraction, bulk density measurements, differential thermal analysis, chemical durability tests, scanning and transmission electron microscopies, and energy-dispersive X-ray spectroscopy. These glasses were found to accommodate high salt concentrations and have high densities, but further development is needed to improve chemical durability. (C) 2017 Published by Elsevier B.V.

Continuous reduction of tellurite to recoverable tellurium nanoparticles using an upflow anaerobic sludge bed (UASB) reactor.

Science.gov (United States)

Ramos-Ruiz, Adriana; Sesma-Martin, Juan; Sierra-Alvarez, Reyes; Field, Jim A

2017-01-01

According to the U.S. Department of Energy and the European Union, tellurium is a critical element needed for energy and defense technology. Thus methods are needed to recover tellurium from waste streams. The objectives of this study was to determine the feasibility of utilizing upflow anaerobic sludge bed (UASB) reactors to convert toxic tellurite (Te IV ) oxyanions to non-toxic insoluble elemental tellurium (Te 0 ) nanoparticles (NP) that are amendable to separation from aqueous effluents. The reactors were supplied with ethanol as the electron donating substrate to promote the biological reduction of Te IV . One reactor was additionally amended with the redox mediating flavonoid compound, riboflavin (RF), with the goal of enhancing the bioreduction of Te IV . Its performance was compared to a control reactor lacking RF. The continuous formation of Te 0 NPs using the UASB reactors was found to be feasible and remarkably improved by the addition of RF. The presence of this flavonoid was previously shown to enhance the conversion rate of Te IV by approximately 11-fold. In this study, we demonstrated that this was associated with the added benefit of reducing the toxic impact of Te IV towards the methanogenic consortium in the UASB and thus enabled a 4.7-fold higher conversion rate of the chemical oxygen demand. Taken as a whole, this work demonstrates the potential of a methanogenic granular sludge to be applied as a bioreactor technology producing recoverable Te 0 NPs in a continuous fashion. Copyright © 2016 Elsevier Ltd. All rights reserved.

Structure of zinc and niobium tellurite glasses by neutron and x-ray diffraction

International Nuclear Information System (INIS)

Hoppe, U; Yousef, E; Ruessel, C; Neuefeind, J; Hannon, A C

2004-01-01

Neutron and x-ray diffraction experiments of high resolving power with neutrons from a spallation source and high-energy photons from a synchrotron have been performed on compositional series of binary Zn, Nb and on mixed Zn/Nb tellurite glasses. The Te-O, Zn-O and Nb-O coordination numbers are determined by Gaussian fitting of the first-neighbour peaks in the neutron and x-ray data simultaneously. The transition of TeO 4 to TeO 3 units with increasing fraction of a second component is indicated by decreasing total Te-O coordination numbers. This transition appears different for glasses with ZnO or Nb 2 O 5 additions. Details of the Te-O peaks suggest there are two species of Te-O bonds with lengths of ∼ 0.19 and ∼ 0.21 nm. The change of their fractions shows excellent agreement with the existence of TeO 4 trigonal bipyramids and TeO 3 trigonal pyramids. All oxygen atoms from ZnO and Nb 2 O 5 are used for rupture of Te-O-Te bridges, which is accompanied with a change of nearly all participating TeO 4 to TeO 3 groups. The tendency for a TeO 4 → TeO 3 change decreases for glasses of higher second component content which is accompanied by the occurrence of TeO 4 groups with non-bridging oxygens. The Nb tellurite glasses show transition to network-forming behaviour with the formation of Nb-O-Nb bridges. The fractions of TeO 3 units of ternary Zn/Nb tellurite glasses agree with an additivity behaviour of the modifying effects of ZnO and Nb 2 O 5 additions

Spectroscopy of Yb-doped tungsten-tellurite glass and assessment of its lasing properties

Science.gov (United States)

Merzliakov, M. A.; Kouhar, V. V.; Malashkevich, G. E.; Pestryakov, E. V.

2018-01-01

Glasses of the TeO2-WO3-Yb2O3 system are synthesized for wide range of Yb3+ concentrations of up to 6.0 × 1021 ions/cm3. The spectral-luminescent properties of lightly doped samples are investigated at room temperature and at the boiling point of liquid nitrogen. The energies of the Stark levels of the ground and excited states of Yb3+ ions incorporated into tungsten-tellurite glass are determined by analyzing the low-temperature spectra. The absorption, emission, and gain cross section spectra are obtained. The excess of the measured fluorescence decay time over the radiative lifetime ∼0.3 ms derived from the absorption spectra is attributed to the reabsorption effect in bulk samples. Measurements of lightly doped glass powder in the immersion liquid are made to reduce the effect of reabsorption. The fluorescence decay time of the powder is very close to the calculated radiative lifetime. Compared with phosphate, silicate, and other Yb3+-doped glasses, the tungsten-tellurite glass has a promising potential as a gain medium for lasers and amplifiers.

Studies on boro cadmium tellurite glasses

Science.gov (United States)

Gayathri Pavani, P.; Suresh, S.; Chandra Mouli, V.

2011-11-01

To investigate the modification effect of the modifier CdO on boro tellurite glass, a series of glasses with compositions (50 - x) CdO- xTeO 2-50B 2O 3 have been prepared by conventional melt quenching technique. Optical absorption, IR and Raman structural studies are carried out on the glass system. The optical absorption studies revealed that the cutoff wave length and refractive index increase while optical band gap ( Eopt) and Urbach energy decreases with increase of CdO content. The IR and Raman studies revealed that structure of glass network consists of [TeO 3]/[TeO 3+1], [TeO 4], [BO 3], [BO 4] and [Cd-Te] linkages .The compositional dependence of different physical parameters such as density, molar volume, oxygen packing density, optical basicity, have been analyzed and discussed.

Metals and metalloids treatment in contaminated neutral effluents using modified materials.

Science.gov (United States)

Calugaru, Iuliana Laura; Neculita, Carmen Mihaela; Genty, Thomas; Zagury, Gérald J

2018-04-15

Circumneutral surface water and groundwater can contain hazardous concentrations of metals and metalloids that can threaten organisms in surrounding ecosystems. Extensive research has been conducted over the past two decades to prevent, limit, and treat water pollution. Among the currently available treatment options is the use of natural and residual materials, which is generally regarded as effective and inexpensive. The modification of such materials enhances the removal capacity of metals and metalloids, as well as the physical and chemical stability of the materials and resulting sludge (after treatment). This paper reviews several modified materials that have produced and evaluated in the past twenty years to treat various contaminants in water under specific conditions. Important factors on performance improvement following the modifications are emphasized. Sorption capacity and kinetics, and element removal mechanisms are also discussed. Element recovery, material regeneration, water reuse, evaluation of treatment efficiency for real effluents are also considered, as well as the applicability of these materials in both active and passive treatment systems. Modified natural and residual materials are a promising option for the treatment of metals and metalloids in circumneutral contaminated waters. However, further research is necessary to evaluate their field-scale performance and to properly assess treatment costs. Copyright © 2018 Elsevier Ltd. All rights reserved.

Jacks of metal(loid chelation trade in plants – an overview

Directory of Open Access Journals (Sweden)

Naser A. Anjum

2015-04-01

Full Text Available Varied environmental compartments including soils are being contaminated by a myriad toxic metal(loids (hereafter termed as ‘metal/s’ mainly through anthropogenic activities. These metals may contaminate food chain and bring irreparable consequences in human. Plant-based approach (phytoremediation stands second to none among bioremediation technologies meant for sustainable cleanup of soils/sites with metal-contamination. In turn, the capacity of plants to tolerate potential consequences caused by the extracted/accumulated metals decides the effectiveness and success of phytoremediation system. Chelation is among the potential mechanisms that largely govern metal-tolerance in plant cells by maintaining low concentrations of free metals in cytoplasm. Metal-chelation can be performed by compounds of glutathione (GSH (reduced GSH; phytochelatins, PCs; metallothioneins, MTs and non-GSH (histidine, nicotianamine, organic acids origin. This paper presents an appraisal of recent reports on both GSH and non-GSH associated compounds in an effort to shed light on the significance of these compounds in metal-plant tolerance, as well as to provide scientific clues for the development of phytoextraction strategies.

Absorption and emission analysis of RE3+(Sm3+ and Dy3+): lithium boro tellurite glasses.

Science.gov (United States)

Sooraj Hussain, N; Hungerford, G; El-Mallawany, R; Gomes, M J M; Lopes, M A; Ali, Nasar; Santos, J D; Buddhudu, S

2009-06-01

This paper reports on the development and spectral analysis of Sm3+ (1.0%) and Dy3+ (1.0%) doped lithium-boro-tellurite glasses. A bright orange (4G5/2-->6H7/2) along with a red (4G5/2-->6H9/2) and a yellow (4G5/2-->6H5/2) emission transition have been measured from Sm3+ doped lithium-boro-tellurite glass. Both blue (4F9/2-->6H15/2) and yellow (4F9/2-->6H13/2) emission bands have been obtained from Dy3+ glass. From the measured decay profiles, the lifetimes of the emissions of the Sm3+ glass (4G5/2-->6H5/2, 7/2, 9/2 and 11/2) at an excitation of 401 nm have been found to be in the range 0.47-0.81 ms, and with respect to the Dy3+ emissions (4F9/2-->6H15/2 and 13/2), with excitation at 450 nm, are measured to be in the range of 0.302-0.307 ms. Stimulated emission cross-sections (sigmapE) of the measured emission transitions have also been computed and the values are in the range of (0.38-1.20) x 10(-20) cm2 for Sm3+ and for Dy3+ doped lithium-boro-tellurite glass the values are (0.66-1.39) x 10(-20) cm2.

Evaluation of a new optic-enabled portable X-ray fluorescence spectrometry instrument for measuring toxic metals/metalloids in consumer goods and cultural products

Science.gov (United States)

Guimarães, Diana; Praamsma, Meredith L.; Parsons, Patrick J.

2016-08-01

X-ray fluorescence spectrometry (XRF) is a rapid, non-destructive multi-elemental analytical technique used for determining elemental contents ranging from percent down to the μg/g level. Although detection limits are much higher for XRF compared to other laboratory-based methods, such as inductively coupled plasma mass spectrometry (ICP-MS), ICP-optical emission spectrometry (OES) and atomic absorption spectrometry (AAS), its portability and ease of use make it a valuable tool, especially for field-based studies. A growing necessity to monitor human exposure to toxic metals and metalloids in consumer goods, cultural products, foods and other sample types while performing the analysis in situ has led to several important developments in portable XRF technology. In this study, a new portable XRF analyzer based on the use of doubly curved crystal optics (HD Mobile®) was evaluated for detecting toxic elements in foods, medicines, cosmetics and spices used in many Asian communities. Two models of the HD Mobile® (a pre-production and a final production unit) were investigated. Performance parameters including accuracy, precision and detection limits were characterized in a laboratory setting using certified reference materials (CRMs) and standard solutions. Bias estimates for key elements of public health significance such as As, Cd, Hg and Pb ranged from - 10% to 11% for the pre-production, and - 14% to 16% for the final production model. Five archived public health samples including herbal medicine products, ethnic spices and cosmetic products were analyzed using both XRF instruments. There was good agreement between the pre-production and final production models for the four key elements, such that the data were judged to be fit-for-purpose for the majority of samples analyzed. Detection of the four key elements of interest using the HD Mobile® was confirmed using archived samples for which ICP-OES data were available based on digested sample materials. The HD

Informal E-waste recycling in developing countries: review of metal(loid)s pollution, environmental impacts and transport pathways.

Science.gov (United States)

Ackah, Michael

2017-11-01

Crude or primitive recycling practices are often adopted in material resource recovery from E-waste in developing nations. Significant human health and environmental impacts may occur because of such practices. Literature on metal(loid)s pollution during E-waste processing is fragmented. Here, I review the health and environmental impacts of E-waste recycling operations and transport pathways of metal(loid)s, dispersed during operations. This paper is organised into five sections. Section 1 relates to the background of global E-waste generation and legal/illegal trade, citing specific cases from Ghana and other developing nations. Section 2 provides a brief information on sources of metal(loid)s in E-waste. Section 3 describes characteristics of informal E-waste recycling operations in developing nations. Section 4 examines the health and environmental impacts in E-waste recycling while section 5 evaluates major transport pathways of metal(loid)s contaminants.

Hyperaccumulators of metal and metalloid trace elements: facts and fiction.

NARCIS (Netherlands)

van der Ent, A.; Baker, A.J.M.; Reeves, R.D.; Pollard, A.J.; Schat, H.

2012-01-01

Background: Plants that accumulate metal and metalloid trace elements to extraordinarily high concentrations in their living biomass have inspired much research worldwide during the last decades. Hyperaccumulators have been recorded and experimentally confirmed for elements such as nickel, zinc,

The effect of La2O3 in Tm3+-doped germanate-tellurite glasses for ~2 μm emission

OpenAIRE

Peng, Ya-Pei; Yuan, Xinqiang; Zhang, Junjie; Zhang, Long

2014-01-01

A germanate-tellurite glass (GeO2-TeO2-K2O-Nb2O5-La2O3) with thulium doping has been investigated for application as a laser material around 2.0 μm regions. Under the 808 nm laser diode pumped, intense 1.8 μm emission is obtained. Based on the absorption spectra, radiative properties are predicted using Judd-Ofelt theory. The maximum value of emission cross-section of Tm3+ around 1.8 μm can reach 1.46 × 10−20 cm2, which indicated that the germanate-tellurite glass may provide high gain as a g...

Natural Fe3O4 nanoparticles embedded zinc–tellurite glasses: Polarizability and optical properties

International Nuclear Information System (INIS)

Widanarto, W.; Sahar, M.R.; Ghoshal, S.K.; Arifin, R.; Rohani, M.S.; Hamzah, K.; Jandra, M.

2013-01-01

Modifying the optical behavior of zinc–tellurite glass by embedding magnetic nanoparticles has implication in nanophotonics. A series of zinc–tellurite glasses containing natural Fe 3 O 4 nanoparticles with composition (80 − x)TeO 2 ·xFe 3 O 4 ·20ZnO (0 ≤ x ≤ 2) in mol% are synthesized by melt quenching method and their optical properties are investigated using FTIR and UV–vis–NIR spectroscopies. Lorentz–Lorenz relations are exploited to determine the refractive index, molar refraction and electronic polarizability. The sharp absorption peaks of FTIR spectra show a shift from 667 cm −1 to 671 cm −1 in the presence of nanoparticles that increase the non-bridging oxygen, confirmed by the intensity change of the TeO 3 peak at 752 cm −1 . A new peak around 461 cm −1 is also observed which is attributed to the band characteristic of covalent Fe–O linkages. A decrease in the Urbach energy as much as 0.122 eV and the optical energy band gap with the increase of Fe 3 O 4 concentration (0.5–1.0 mol%) is evidenced. Electronic polarizability of the glasses increases with increasing Fe 3 O 4 nanoparticles concentration up to 1 mol%. Interestingly, the polarizability tends to decrease with the further increase of Fe 3 O 4 concentration at 2 mol%. The role of magnetic nanoparticles in influencing the structural and optical behavior are examined and understood. - Highlights: ► Incorporation of natural Fe 3 O 4 nanoparticles into the zinc–tellurite glass. ► Influence of magnetic nanoparticles in modifying structure and optical properties. ► Enhancement of refraction index and change in electronic polarizability

Comparative Spectroscopic Investigation of Tm3+:Tellurite Glasses for 2-μm Lasing Applications

Directory of Open Access Journals (Sweden)

Huseyin Cankaya

2018-02-01

Full Text Available We performed a comparative spectroscopic analysis on three novel Tm3+:tellurite-based glasses with the following compositions Tm2O3:TeO2-ZnO (TeZnTm, Tm2O3:TeO2-Nb2O5 (TeNbTm, and Tm3+:TeO2-K2O-Nb2O5 (TeNbKTm, primarily for 2-μm laser applications. Tellurite glasses were prepared at different doping concentrations in order to investigate the effect of Tm3+ ion concentration as well as host composition on the stimulated emission cross sections and the luminescence quantum efficiencies. By performing Judd–Ofelt analysis, we determined the average radiative lifetimes of the 3H4 level to be 2.55 ± 0.07 ms, 2.76 ± 0.03 ms and 2.57 ± 0.20 ms for the TeZnTm, TeNbTm and TeNbKTm samples, respectively. We clearly observed the effect of the cross-relaxation, which becomes significant at higher Tm2O3 concentrations, leading to the quenching of 1460-nm emission and enhancement of 1860-nm emission. Furthermore, with increasing Tm2O3 concentrations, we observed a decrease in the fluorescence lifetimes as a result of the onset of non-radiative decay. For the 3H4 level, the highest obtained quantum efficiency was 32% for the samples with the lowest Tm2O3 ion concentration. For the 1860-nm emission band, the average emission cross section was determined to measure around 6.33 ± 0.34 × 10−21 cm2, revealing the potential of thulium-doped tellurite gain media for 2-μm laser applications in bulk and fiber configurations.

Structural studies on iron-tellurite glasses prepared by sol-gel method

Energy Technology Data Exchange (ETDEWEB)

Rada, S., E-mail: Simona.Rada@phys.utcluj.r [Department of Physics, Technical University of Cluj-Napoca, Bibliotecii, No. 10, 400020 Cluj-Napoca (Romania); Dehelean, A. [Department of Physics, Technical University of Cluj-Napoca, Bibliotecii, No. 10, 400020 Cluj-Napoca (Romania); Nat. Inst. for R and D of Isotopic and Molec. Technologies, Cluj-Napoca (Romania); Stan, M. [Nat. Inst. for R and D of Isotopic and Molec. Technologies, Cluj-Napoca (Romania); Chelcea, R. [Department of Physics, Technical University of Cluj-Napoca, Bibliotecii, No. 10, 400020 Cluj-Napoca (Romania); Nat. Inst. for R and D of Isotopic and Molec. Technologies, Cluj-Napoca (Romania); Culea, E. [Department of Physics, Technical University of Cluj-Napoca, Bibliotecii, No. 10, 400020 Cluj-Napoca (Romania)

2011-01-05

Research highlights: {yields} Iron-tellurite glasses obtained using the sol-gel synthesis. - Abstract: In this study, we report structural properties of the iron-tellurite glasses obtained using the sol-gel synthesis. The samples were characterized by X-ray diffraction, FTIR, UV-vis and EPR spectroscopy. Our results indicate dominant presence of iron ions in the trivalent state and the existence some Fe{sup 2+} ions. The analysis of the IR spectra indicates a gradual transformation of iron ions from tetrahedral into octahedral sites when the concentration of Fe(NO{sub 3}){sub 3} is increased beyond 0.64 mol%. EPR studies show that the increase of Fe(NO{sub 3}){sub 3} content in the host matrix induces the growth of the number of effective g values. This can be explained considering that the orbitals of O{sup 2-} ion with a large spin-orbit interaction constant will interact with the 3d orbital of Fe{sup 3+} ion bonded to this O{sup 2-} ion, thus leading to appearance of an orbital angular momentum which contributes to the magnetic moment of Fe{sup 3+} ion. A strong dipolar interaction, which is more predominant in a glass with higher content of Fe(NO{sub 3}){sub 3}, causing a localized magnetic field along the site of the Fe{sup 3+} ions and the increase the effective g values.

Particle-size dependence on metal(loid) distributions in mine wastes: Implications for water contamination and human exposure

Science.gov (United States)

Kim, C.S.; Wilson, K.M.; Rytuba, J.J.

2011-01-01

The mining and processing of metal-bearing ores has resulted in contamination issues where waste materials from abandoned mines remain in piles of untreated and unconsolidated material, posing the potential for waterborne and airborne transport of toxic elements. This study presents a systematic method of particle size separation, mass distribution, and bulk chemical analysis for mine tailings and adjacent background soil samples from the Rand historic mining district, California, in order to assess particle size distribution and related trends in metal(loid) concentration as a function of particle size. Mine tailings produced through stamp milling and leaching processes were found to have both a narrower and finer particle size distribution than background samples, with significant fractions of particles available in a size range (???250 ??m) that could be incidentally ingested. In both tailings and background samples, the majority of trace metal(loid)s display an inverse relationship between concentration and particle size, resulting in higher proportions of As, Cr, Cu, Pb and Zn in finer-sized fractions which are more susceptible to both water- and wind-borne transport as well as ingestion and/or inhalation. Established regulatory screening levels for such elements may, therefore, significantly underestimate potential exposure risk if relying solely on bulk sample concentrations to guide remediation decisions. Correlations in elemental concentration trends (such as between As and Fe) indicate relationships between elements that may be relevant to their chemical speciation. ?? 2011 Elsevier Ltd.

Effect of B2O3 on luminescence of erbium doped tellurite glasses.

Science.gov (United States)

Shen, Xiang; Nie, Qiuhua; Xu, Tiefeng; Dai, Shixun; Wang, Xunsi

2007-02-01

The B2O3 was introduced into the Er3+ doped TeO2-ZnO-Na2O glass to increase the phonon energy of the host. The effect of B2O3 on the non-radiative rate of the 4I11/2-->4I13/2 transition of Er3+, the lifetime of the 4I11/2 and 4I13/2 levels, the green and red upconversion emissions intensity, and the 4I13/2-->4I15/2 emission intensity was discussed. The results show that the phonon energy of boro-tellurite glass is close to that of germanate glass and is quite smaller than that of borate glass. The lifetime of 4I11/2 level and the upconversion emissions decrease with increasing B2O3 concentration. The higher OH group concentration presented in the boro-tellurite glass may shorten the lifetime of 4I13/2 level and also reduce the quantum efficiency of 4I13/2-->4I15/2 emission. The future dehydrating procedures are suggested to enhance the efficiency of amplification at 1.5 microm band.

Relationships between seminal plasma metals/metalloids and semen quality, sperm apoptosis and DNA integrity.

Science.gov (United States)

Wang, Yi-Xin; Wang, Peng; Feng, Wei; Liu, Chong; Yang, Pan; Chen, Ying-Jun; Sun, Li; Sun, Yang; Yue, Jing; Gu, Long-Jie; Zeng, Qiang; Lu, Wen-Qing

2017-05-01

This study aimed to investigate the relationships between environmental exposure to metals/metalloids and semen quality, sperm apoptosis and DNA integrity using the metal/metalloids levels in seminal plasma as biomarkers. We determined 18 metals/metalloids in seminal plasma using an inductively coupled plasma-mass spectrometry among 746 men recruited from a reproductive medicine center. Associations of these metals/metalloids with semen quality (n = 746), sperm apoptosis (n = 331) and DNA integrity (n = 404) were evaluated using multivariate linear and logistic regression models. After accounting for multiple comparisons and confounders, seminal plasma arsenic (As) quartiles were negatively associated with progressive and total sperm motility using multivariable linear regression analysis, which were in accordance with the trends for increased odds ratios (ORs) for below-reference semen quality parameters in the logistic models. We also found inverse correlations between cadmium (Cd) quartiles and progressive and total sperm motility, whereas positive correlations between zinc (Zn) quartiles and sperm concentration, between copper (Cu) and As quartiles and the percentage of tail DNA, between As and selenium (Se) quartiles and tail extent and tail distributed moment, and between tin (Sn) categories and the percentage of necrotic spermatozoa (all P trend <0.05). These relationships remained after the simultaneous consideration of various elements. Our results indicate that environmental exposure to As, Cd, Cu, Se and Sn may impair male reproductive health, whereas Zn may be beneficial to sperm concentration. Copyright © 2017 Elsevier Ltd. All rights reserved.

Energy transfer and infrared-to-visible upconversion luminescence of Er3+/Yb3+-codoped halide modified tellurite glasses

International Nuclear Information System (INIS)

Zhang, Q.Y.; Feng, Z.M.; Yang, Z.M.; Jiang, Z.H.

2006-01-01

We report on the energy transfer and frequency upconversion spectroscopic properties of Er 3+ -doped and Er 3+ /Yb 3+ -codoped TeO 2 -ZnO-Na 2 O-PbCl 2 halide modified tellurite glasses upon excitation with 808 and 978 nm laser diode. Three intense emissions centered at around 529, 546 and 657 nm, alongwith a very weak blue emission at 410 nm have clearly been observed for the Er 3+ /Yb 3+ -codoped halide modified tellurite glasses upon excitation at 978 nm and the involved mechanisms are explained. The quadratic dependence of fluorescence on excitation laser power confirms the fact that the two-photon contribute to the infrared to green-red upconversion emissions. And the blue upconversion at 410 nm involved a sequential three-photon absorption process

Determination of the long-term release of metal(loid)s from construction materials using DGTs.

Science.gov (United States)

Schmukat, A; Duester, L; Ecker, D; Heininger, P; Ternes, T A

2013-09-15

Long-term leaching experiments are crucial to estimate the potential release of dangerous substances from construction materials. The application of Diffuse Gradients in Thin film (DGT) in static-batch experiments was tested to study the long-term release of metal(loid)s from construction materials for hydraulic engineering, for half a year. Long-term release experiments are essential to improve calculations of the life-time release for this materials. DGTs in batch experiments were found to be a space and labour efficient application, which enabled (i) to study, in a non-invasive manner, the total release of nine metal(loid)s for half a year, (ii) to differentiate between release mechanisms and (iii) to study mechanisms which were contrary to the release or caused experimental artefacts in the batch experiments. For copper slag (test material) it was found that eight metal(loid)s were released over the whole time period of 184 d. Cu, Ni and Pb were found to be released, predominantly caused by (the) weathering of sulphide minerals. Only for Zn a surface depletion mechanism was identified. The results from the long-term batch experiments deliver new information on the release of metal(loid)s during the life cycle of construction materials with regard to river basin management objectives. Copyright © 2013 Elsevier B.V. All rights reserved.

Monitoring of heavy/toxic metals and halides in surface/ground water (abstract)

International Nuclear Information System (INIS)

Viqar-un-Nisa; Ahmed, R.; Husain, M.

1999-01-01

Water is essential for maintaining physical and social life. Human and animal consumption is perhaps the most evident essential use of water. Water quality and quantity have become critical issues, affecting all life. The importance of water in our lives, combined with the threats, make water resources use a global problem. Among the different pollutants toxic metals, metalloids and halides have special significance. Industrial effluents and municipal wastewater are normally drained into water streams, rivers and other reservoirs thus polluting these significantly. Quality of our water resources especially is an issue, which continues to arouse the attention of concerned scientists, legislators and the general public. Among various pollutant chemicals, the heavy metals and metalloids are present at trace levels in various compartments of the environment. Some metals become toxic even at trace levels because of the important features that distinguishes metals from other pollutants is that they are not biodegradable. The halides like Cl, Br, and I from different sources can enter easily into water systems and then they make their way directly into the human body. The intake of toxic as wells as essential elements through water and other food items like vegetables, milk wheat flour etc. is significant. The abundance or deficiency of these meals as well as halides results in abnormal metabolic functions. Due to excessive demand for trace analysis in water and other materials a variety of techniques and instrumentation has been developed. Determination of heavy metals ions is of the highest interest in environmental analysis. Among the food materials water is most important because of their large consumption by man. Also toxic metals in water may be in dissolved ionic form, which directly go into human metabolism and start their toxic action. Presence of even small amounts of toxic metals in drinking water can produce serious health hazards. (author)

The effect of La2O3 in Tm3+-doped germanate-tellurite glasses for ~2 μm emission

Science.gov (United States)

Peng, Ya-Pei; Yuan, Xinqiang; Zhang, Junjie; Zhang, Long

2014-06-01

A germanate-tellurite glass (GeO2-TeO2-K2O-Nb2O5-La2O3) with thulium doping has been investigated for application as a laser material around 2.0 μm regions. Under the 808 nm laser diode pumped, intense 1.8 μm emission is obtained. Based on the absorption spectra, radiative properties are predicted using Judd-Ofelt theory. The maximum value of emission cross-section of Tm3+ around 1.8 μm can reach 1.46 × 10-20 cm2, which indicated that the germanate-tellurite glass may provide high gain as a good medium for efficient 1.8 μm laser system.

Spin-exchange interaction between transition metals and metalloids in soft-ferromagnetic metallic glasses

Science.gov (United States)

Das, Santanu; Choudhary, Kamal; Chernatynskiy, Aleksandr; Choi Yim, Haein; Bandyopadhyay, Asis K.; Mukherjee, Sundeep

2016-06-01

High-performance magnetic materials have immense industrial and scientific importance in wide-ranging electronic, electromechanical, and medical device technologies. Metallic glasses with a fully amorphous structure are particularly suited for advanced soft-magnetic applications. However, fundamental scientific understanding is lacking for the spin-exchange interaction between metal and metalloid atoms, which typically constitute a metallic glass. Using an integrated experimental and molecular dynamics approach, we demonstrate the mechanism of electron interaction between transition metals and metalloids. Spin-exchange interactions were investigated for a Fe-Co metallic glass system of composition [(Co1-x Fe x )0.75B0.2Si0.05]96Cr4. The saturation magnetization increased with higher Fe concentration, but the trend significantly deviated from simple rule of mixtures. Ab initio molecular dynamics simulation was used to identify the ferromagnetic/anti-ferromagnetic interaction between the transition metals and metalloids. The overlapping band-structure and density of states represent ‘Stoner type’ magnetization for the amorphous alloys in contrast to ‘Heisenberg type’ in crystalline iron. The enhancement of magnetization by increasing iron was attributed to the interaction between Fe 3d and B 2p bands, which was further validated by valence-band study.

Structural, Chemical and Biological Aspects of Antioxidants for Strategies Against Metal and Metalloid Exposure

Directory of Open Access Journals (Sweden)

Swaran J. S. Flora

2009-01-01

Full Text Available Oxidative stress contributes to the pathophysiology of exposure to heavy metals/metalloid. Beneficial renal effects of some medications, such as chelation therapy depend at least partially on the ability to alleviate oxidative stress. The administration of various natural or synthetic antioxidants has been shown to be of benefit in the prevention and attenuation of metal induced biochemical alterations. These include vitamins, N-acetylcysteine, α-lipoic acid, melatonin, dietary flavonoids and many others. Human studies are limited in this regard. Under certain conditions, surprisingly, the antioxidant supplements may exhibit pro-oxidant properties and even worsen metal induced toxic damage. To date, the evidence is insufficient to recommend antioxidant supplements in subject with exposure to metals. Prospective, controlled clinical trials on safety and effectiveness of different therapeutic antioxidant strategies either individually or in combination with chelating agent are indispensable. The present review focuses on structural, chemical and biological aspects of antioxidants particularly related to their chelating properties.

Structural and spectroscopic studies on Er{sup 3+} doped boro-tellurite glasses

Energy Technology Data Exchange (ETDEWEB)

Selvaraju, K. [Department of Physics, Gandhigram Rural University, Gandhigram - 624 302 (India); Marimuthu, K., E-mail: mari_ram2000@yahoo.com [Department of Physics, Gandhigram Rural University, Gandhigram - 624 302 (India)

2012-04-01

Er{sup 3+} doped boro-tellurite glasses with the chemical composition (69-x)B{sub 2}O{sub 3}-xTeO{sub 2}-15MgO-15K{sub 2}O-1Er{sub 2}O{sub 3} (where x=0, 10, 20, 30 and 40 wt%) have been prepared and their structural and spectroscopic behavior were studied and reported. The varying tellurium dioxide content in the host matrix that results, changes in structural and spectroscopic behavior around Er{sup 3+} ions are explored through XRD, FTIR, UV-VIS-NIR and luminescence measurements. The XRD pattern confirms the amorphous nature of the prepared glasses and the FTIR spectra explore the fundamental groups and the local structural units in the prepared boro-tellurite glasses. The bonding parameters ({beta}{sup Macron} and {delta}) have been calculated from the observed band positions of the absorption spectra to claim the ionic/covalent nature of the prepared glasses. The Judd-Ofelt (JO) intensity parameters {Omega}{sub {lambda}} ({lambda}=2, 4 and 6) were determined through experimental and calculated oscillator strengths obtained from the absorption spectra and their results are studied and compared with reported literature. The variation in the JO parameters {Omega}{sub {lambda}} ({lambda}=2, 4 and 6) with the change in chemical composition have been discussed in detail. The JO parameters have also been used to derive the important radiative properties like transition probability (A), branching ratio ({beta}{sub R}) and peak stimulated emission cross-section ({sigma}{sub P}{sup E}) for the excited state transitions {sup 2}H{sub 9/2}{yields}{sup 4}I{sub 15/2} and {sup 2}H{sub 11/2} and {sup 4}S3{sub /2}{yields}{sup 4}I{sub 15/2} of the Er{sup 3+} ions and the results were studied and reported. Using Davis and Mott theory, optical band gap energy (E{sub opt}) values for the direct and indirect allowed transitions have been calculated and discussed along with the Urbach energy values for the prepared Er{sup 3+} doped boro-tellurite glasses in the present study. The

Up-conversion luminescence and local heating in Er{sup 3+} doped tellurite glass

Energy Technology Data Exchange (ETDEWEB)

Dwivedi, Y.; Rai, S.B. [Banaras Hindu University, Laser and Spectroscopy Laboratory, Physics Department, Varanasi, UP (India)

2012-10-15

The present article discusses the up-conversion and thermometric properties of Er doped tellurite glass on excitation with 976 nm laser radiation. Temperature has been measured using fluorescence intensity ratio variation, in 528/548 and 801/828 nm, with temperature. Temperature at laser focus spot has been estimated by comparing the intensity ratios at different laser powers with the intensity ratio at different temperatures when sample was heated externally. (orig.)

Assessing ecotoxicity and uptake of metals and metalloids in relation to two different earthworm species (Eiseina hortensis and Lumbricus terrestris)

International Nuclear Information System (INIS)

Leveque, Thibaut; Capowiez, Yvan; Schreck, Eva; Mazzia, Christophe; Auffan, Mélanie; Foucault, Yann; Austruy, Annabelle; Dumat, Camille

2013-01-01

Due to diffuse atmospheric fallouts of process particles enriched by metals and metalloids, polluted soils concern large areas at the global scale. Useful tools to assess ecotoxicity induced by these polluted soils are therefore needed. Earthworms are currently used as biotest, however the influence of specie and earthworm behaviour, soil characteristics are poorly highlighted. Our aim was therefore to assess the toxicity of various polluted soils with process particles enriches by metals and metalloids (Pb, Cd, Cu, Zn, As and Sb) collected from a lead recycling facility on two earthworm species belonging to different ecological types and thus likely to have contrasted behavioural responses (Eiseina hortensis and Lumbricus terrestris). The combination of behavioural factors measurements (cast production and biomass) and physico-chemical parameters such as metal absorption, bioaccumulation by earthworms and their localization in invertebrate tissues provided a valuable indication of pollutant bioavailability and ecotoxicity. Soil characteristics influenced ecotoxicity and metal uptake by earthworms, as well as their soil bioturbation. -- Highlights: •Historically polluted soils collected from a lead recycling facility were studied. •Cast production is a sensitive parameter to assess ecotoxicity on earthworms. •Both soil parameters, like organic matter content and pH and earthworm specie influence metal uptake and ecotoxicity. -- Behavioural factors and inorganic pollutant uptake by earthworms provide a valuable indication of bioavailability and ecotoxicity

On observation of the downconversion mechanism in Er{sup 3+}/Yb{sup 3+} co-doped tellurite glass using thermal and optical parameters

Energy Technology Data Exchange (ETDEWEB)

Figueiredo, M.S.; Santos, F.A. [Universidade Federal da Grande Dourados, Faculdade de Ciências Exatas e Tecnologias, Dourados, MS (Brazil); Yukimitu, K.; Moraes, J.C.S. [Universidade Estadual Paulista, UNESP, Departamento de Física e Química, Av. Brasil, 56, 15385-000 Ilha Solteira, SP (Brazil); Nunes, L.A.O. [Instituto de Física de São Carlos, Universidade de São Paulo, CP 369, 13560-970 São Carlos, SP (Brazil); Andrade, L.H.C. [Grupo de Espectroscopia Óptica e Fototérmica, Universidade Estadual de Mato Grosso do Sul, Cidade Universitária de Dourados, CP 351, Dourados, MS (Brazil); Lima, S.M., E-mail: smlima@uems.br [Grupo de Espectroscopia Óptica e Fototérmica, Universidade Estadual de Mato Grosso do Sul, Cidade Universitária de Dourados, CP 351, Dourados, MS (Brazil)

2015-01-15

In this work we report the observed downconversion (DC) mechanism in Er{sup 3+}/Yb{sup 3+}-codoped tellurite glasses (in mol%, 80TeO{sub 2}–10Li{sub 2}O–10TiO{sub 2}). The samples were synthesized by the conventional melt-quenching method and then studied using optical spectroscopy and thermal lens spectroscopy (TLS). These characterizations enabled investigation of the radiative and nonradiative processes involved in energy transfer from erbium to ytterbium. The visible Er{sup 3+} fluorescence intensities decreased as a function of the Yb{sup 3+} concentration, and there was a corresponding increase in the ytterbium emission at around 980 nm. Simultaneously, there was a reduction in the heat-generated due nonradiative decays (∼21%) when ytterbium was added. This temperature change was measured by TLS measurements and the results corroborate with the indicated by spectroscopic interpretation. - Highlights: • Energy transfer from erbium to ytterbium in tellurite glass. • ∼56% of cross-relaxation efficiency from Er{sup 3+} to Yb{sup 3+}. • Downconversion effect in tellurite glasses. • Downconversion effect observation by thermal lens spectroscopy.

Elemental redistribution behavior in tellurite glass induced by high repetition rate femtosecond laser irradiation

International Nuclear Information System (INIS)

Teng, Yu; Zhou, Jiajia; Khisro, Said Nasir; Zhou, Shifeng; Qiu, Jianrong

2014-01-01

Highlights: • Abnormal elements redistribution behavior was observed in tellurite glass. • The refractive index and Raman intensity distribution changed significantly. • The relative glass composition remained unchanged while the glass density changed. • First time report on the abnormal element redistribution behavior in glass. • The glass network structure determines the elemental redistribution behavior. - Abstract: The success in the fabrication of micro-structures in glassy materials using femtosecond laser irradiation has proved its potential applications in the construction of three-dimensional micro-optical components or devices. In this paper, we report the elemental redistribution behavior in tellurite glass after the irradiation of high repetition rate femtosecond laser pulses. The relative glass composition remained unchanged while the glass density changed significantly, which is quite different from previously reported results about the high repetition rate femtosecond laser induced elemental redistribution in silicate glasses. The involved mechanism is discussed with the conclusion that the glass network structure plays the key role to determine the elemental redistribution. This observation not only helps to understand the interaction process of femtosecond laser with glassy materials, but also has potential applications in the fabrication of micro-optical devices

Fatigue and wear of metalloid-ion-implanted metals

International Nuclear Information System (INIS)

Hohmuth, K.; Richter, E.; Rauschenbach, B.; Blochwitz, C.

1985-01-01

The effect of metalloid ion implantation on the fatigue behaviour and wear of nickel and two steels has been investigated. These metals were implanted with boron, carbon and nitrogen ions at energies from 30 to 60 keV and with doses from 1 X 10 16 to 1 X 10 18 ions cm -2 at room temperature. The mechanical behaviour of fatigued nickel was studied in push-pull tests at room temperature. Wear measurements were made using a pin-and-disc technique. The surface structure, dislocation arrangement and modification of the implantation profile resulting from mechanical tests on metals which had been implanted with metalloid ions were examined using high voltage electron microscopy, transmission high energy electron diffraction, scanning electron microscopy and Auger electron spectroscopy. It is reported that nitrogen and boron ion implantation improves the fatigue lifetime, changes the number and density of the slip bands and modifies the dislocation arrangements in nickel. The cyclic deformation leads to recrystallization of the boron-ion-induced amorphous structure of nickel and to diffusion of the boron and nitrogen in the direction of the surface. The wear behaviour of steels was improved by implantation of mass-separated ions and by implantation of ions without mass separation. (Auth.)

The effect of La2O3 in Tm3+-doped germanate-tellurite glasses for ~2 μm emission

Science.gov (United States)

Peng, Ya-Pei; Yuan, Xinqiang; Zhang, Junjie; Zhang, Long

2014-01-01

A germanate-tellurite glass (GeO2-TeO2-K2O-Nb2O5-La2O3) with thulium doping has been investigated for application as a laser material around 2.0 μm regions. Under the 808 nm laser diode pumped, intense 1.8 μm emission is obtained. Based on the absorption spectra, radiative properties are predicted using Judd-Ofelt theory. The maximum value of emission cross-section of Tm3+ around 1.8 μm can reach 1.46 × 10−20 cm2, which indicated that the germanate-tellurite glass may provide high gain as a good medium for efficient 1.8 μm laser system. PMID:24918516

The heron that laid the golden egg: metals and metalloids in ibis, darter, cormorant, heron, and egret eggs from the Vaal River catchment, South Africa.

Science.gov (United States)

van der Schyff, V; Pieters, R; Bouwman, H

2016-06-01

Metal pollution issues are afforded the highest priority in developing countries. Only one previous study has addressed metals in African bird eggs. We determined the concentration of metals and metalloids in bird eggs from four sites in the Vaal River catchment (VRC) of South Africa to provide data on the current situation. We analysed 16 pools of 77 heron, ibis, darter, egret, and cormorant eggs for 18 metals and metalloids using ICP-MS. We found high concentrations of gold (Au), uranium (U), thallium (Tl), and platinum (Pt) in Grey Heron eggs from Baberspan. Great white egrets from Bloemhof Dam had high concentrations of mercury (Hg). Multivariate analyses revealed strong associations between Au and U, and between palladium (Pd) and Pt. The toxic reference value (TRV) for Hg was exceeded in seven pools. Selenium exceeded its TRV in one pool; in the same pool, copper (Cu) reached its TRV. Compared with other studies, VRC bird eggs had high concentrations of contaminants. Based on these high concentrations, human health might be at risk as Grey Herons and humans share similar food and are therefore exposed to the same contaminants.

Development of an accelerated leaching method for incineration bottom ash correlated to toxicity characteristic leaching protocol.

Science.gov (United States)

Lin, Shengxuan; Zhou, Xuedong; Ge, Liya; Ng, Sum Huan; Zhou, Xiaodong; Chang, Victor Wei-Chung

2016-10-01

Heavy metals and some metalloids are the most significant inorganic contaminants specified in toxicity characteristic leaching procedure (TCLP) in determining the safety of landfills or further utilization. As a consequence, a great deal of efforts had been made on the development of miniaturized analytical devices, such as Microchip Electrophoresis (ME) and μTAS for on-site testing of heavy metals and metalloids to prevent spreading of those pollutants or decrease the reutilization period of waste materials such as incineration bottom ash. However, the bottleneck lied in the long and tedious conventional TCLP that requires 18 h of leaching. Without accelerating the TCLP process, the on-site testing of the waste material leachates was impossible. In this study, therefore, a new accelerated leaching method (ALM) combining ultrasonic assisted leaching with tumbling was developed to reduce the total leaching time from 18 h to 30 min. After leaching, the concentrations of heavy metals and metalloids were determined with ICP-MS or ICP-optical emission spectroscopy. No statistical significance between ALM and TCLP was observed for most heavy metals (i.e., cobalt, manganese, mercury, molybdenum, nickel, silver, strontium, and tin) and metalloids (i.e., arsenic and selenium). For the heavy metals with statistical significance, correlation factors derived between ALM and TCLP were 0.56, 0.20, 0.037, and 0.019 for barium, cadmium, chromium, and lead, respectively. Combined with appropriate analytical techniques (e.g., ME), the ALM can be applied to rapidly prepare the incineration bottom ash samples as well as other environmental samples for on-site determination of heavy metals and metalloids. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Study of absorption and IR-emission of Er3+, Dy3+, Tm3+ doped high-purity tellurite glasses

Science.gov (United States)

Motorin, S. E.; Dorofeev, V. V.; Galagan, B. I.; Sverchkov, S. E.; Koltashev, V. V.; Denker, B. I.

2018-04-01

A study of high-purity TeO2-ZnO based tellurite glasses doped with Er3+, Dy3+ or Tm3+ that could be used as laser media in the 2-3 μm spectral range is presented. The glasses are prepared by melting the oxides mixture inside a silica glass reactor in an atmosphere of purified oxygen. The low level of hydroxyl groups absorption allowed to measure correctly the luminescence decay characteristics of the dopants. The rare-earth ions absorption bands, the luminescence spectra and kinetic characteristics of emission from the levels 4I11/2, 4I13/2 of Er3+, 6H13/2 of Dy3+ and 3H4, 3H5, 3F4 of Tm3+ ions are investigated. The results confirm the high potential of tellurite glasses as an active media for bulk, planar waveguide and fiber lasers.

Advances in Mid-IR Fiber Lasers: Tellurite, Fluoride and Chalcogenide

Directory of Open Access Journals (Sweden)

Mario Christian Falconi

2017-06-01

Full Text Available A review on the recent progress in modeling and fabrication of medium infrared (Mid-IR fiber lasers is reported. The main objective is to illustrate some recent examples of continuous wave optical sources at wavelengths longer than those commonly employed in telecom applications and allowing high beam quality. A small number of Mid-IR lasers, among the large variety of schemes, glasses, dopants and pumping schemes reported in literature, is selected on the basis of their slope efficiency and threshold pump power. In particular, tellurite, fluoride and chalcogenide fiber lasers are considered. More details are given with reference to the novel pumping schemes.

Natural Fe{sub 3}O{sub 4} nanoparticles embedded zinc–tellurite glasses: Polarizability and optical properties

Energy Technology Data Exchange (ETDEWEB)

Widanarto, W. [Physics Study Program, Jenderal Soedirman University, Jl. Dr. Soeparno 61, Purwokerto 53123 (Indonesia); Sahar, M.R., E-mail: rahimsahar@utm.my [Department of Physics, Faculty of Science, Universiti Teknologi Malaysia, Johor Bahru, Skudai 81310 (Malaysia); Ghoshal, S.K.; Arifin, R.; Rohani, M.S.; Hamzah, K. [Department of Physics, Faculty of Science, Universiti Teknologi Malaysia, Johor Bahru, Skudai 81310 (Malaysia); Jandra, M. [FTI, University Teknologi Malaysia, Johor Bahru, Skudai 81310 (Malaysia)

2013-02-15

Modifying the optical behavior of zinc–tellurite glass by embedding magnetic nanoparticles has implication in nanophotonics. A series of zinc–tellurite glasses containing natural Fe{sub 3}O{sub 4} nanoparticles with composition (80 − x)TeO{sub 2}·xFe{sub 3}O{sub 4}·20ZnO (0 ≤ x ≤ 2) in mol% are synthesized by melt quenching method and their optical properties are investigated using FTIR and UV–vis–NIR spectroscopies. Lorentz–Lorenz relations are exploited to determine the refractive index, molar refraction and electronic polarizability. The sharp absorption peaks of FTIR spectra show a shift from 667 cm{sup −1} to 671 cm{sup −1} in the presence of nanoparticles that increase the non-bridging oxygen, confirmed by the intensity change of the TeO{sub 3} peak at 752 cm{sup −1}. A new peak around 461 cm{sup −1} is also observed which is attributed to the band characteristic of covalent Fe–O linkages. A decrease in the Urbach energy as much as 0.122 eV and the optical energy band gap with the increase of Fe{sub 3}O{sub 4} concentration (0.5–1.0 mol%) is evidenced. Electronic polarizability of the glasses increases with increasing Fe{sub 3}O{sub 4} nanoparticles concentration up to 1 mol%. Interestingly, the polarizability tends to decrease with the further increase of Fe{sub 3}O{sub 4} concentration at 2 mol%. The role of magnetic nanoparticles in influencing the structural and optical behavior are examined and understood. - Highlights: ► Incorporation of natural Fe{sub 3}O{sub 4} nanoparticles into the zinc–tellurite glass. ► Influence of magnetic nanoparticles in modifying structure and optical properties. ► Enhancement of refraction index and change in electronic polarizability.

Low-level environmental metals and metalloids and incident pregnancy loss.

Science.gov (United States)

Buck Louis, Germaine M; Smarr, Melissa M; Sundaram, Rajeshwari; Steuerwald, Amy J; Sapra, Katherine J; Lu, Zhaohui; Parsons, Patrick J

2017-04-01

Environmental exposure to metals and metalloids is associated with pregnancy loss in some but not all studies. We assessed arsenic, cadmium, mercury, and lead concentrations in 501 couples upon trying for pregnancy and followed them throughout pregnancy to estimate the risk of incident pregnancy loss. Using Cox proportional hazard models, we estimated hazard ratios (HR) and 95% confidence intervals (CIs) for pregnancy loss after covariate adjustment for each partner modeled individually then we jointly modeled both partners' concentrations. Incidence of pregnancy loss was 28%. In individual partner models, the highest adjusted HRs were observed for female and male blood cadmium (HR=1.08; CI 0.81, 1.44; HR=1.09; 95% CI 0.84, 1.41, respectively). In couple based models, neither partner's blood cadmium concentrations were associated with loss (HR=1.01; 95% CI 0.75, 1.37; HR=0.92; CI 0.68, 1.25, respectively). We observed no evidence of a significant relation between metal(loids) at these environmentally relevant concentrations and pregnancy loss. Published by Elsevier Inc.

Tailored white light emission in Eu3+/Dy3+ doped tellurite glass phosphors containing Al3+ ions

Science.gov (United States)

Walas, Michalina; Piotrowski, Patryk; Lewandowski, Tomasz; Synak, Anna; Łapiński, Marcin; Sadowski, Wojciech; Kościelska, Barbara

2018-05-01

Tellurite glass systems modified by addition of aluminum fluoride AlF3 have been successfully synthesized as host matrices for optically active rare earth ions RE3+ (RE3+ = Eu3+, Dy3+). Samples with different Eu3+ to Dy3+ molar ratio have been studied in order to determine possibility of white light emission via UV excitation. Structural investigations confirmed amorphous character of materials whereas spectroscopic studies brought more insight into glass network's nature. FTIR results shown presence of two features related to tellurite glass matrix (in 490-935 cm-1 spectral region) and another one (940-1250 cm-1) due to aluminum addition. Especially, Al-O and Te-O-Al bonds of AlO4 tetrahedrons have been found. AlO4 units are considered as glass formers that improve network's strength and thermal resistivity against devitrification. Based on XPS studies of Al3+ photoelectron band the existence of Al-O and also Al-F bonds have been examined. Moreover, signals originating from Eu3+ and Dy3+ have been found confirming their valence state. Luminescence results revealed possibility of simultaneous UV excitation of Eu3+ and Dy3+ ions. Excitation with λexc = 390 and 393 nm resulted in white light generation starting from warm white to neutral and cool white depending on Eu3+ concentration and used excitation wavelength. Additionally, increase of decay lifetime of Eu3+ induced by Al3+ presence have been revealed based on luminescence decay analysis. Thus, tellurite glass systems modified by AlF3 and doped with Eu3+/Dy3+ may be considered as promising candidates for white light emitting sources.

Structure and properties of transition metal-metalloid glasses based on refractory metals

International Nuclear Information System (INIS)

Johnson, W.L.; Williams, A.R.

1979-01-01

The structure and properties of several new transition metal-metalloid (TM/sub 1-x/M/sub x/) metallic glasses based on refractory transition metals (e.g. Mo, W, Ru etc.) have been systemically investigated as a function of composition. The structure of the alloys has been investigated by x-ray diffraction methods and measurements of superconducting properties, electrical resistivity, density, hardness, and mechanical behavior were made. These data are used in developing a novel description of the structure of TM/sub 1-x/M/sub x/ glasses. The experimental evidence suggests that an ideal amorphous phase forms at a specific composition x/sub c/ and that this phase has a well defined atomic short range order. For metallic glasses having x x/sub c/. This novel picture can explain the variation of many properties of these glasses with metalloid concentration

Health risk assessment of various metal(loid)s via multiple exposure pathways on children living near a typical lead-acid battery plant, China

International Nuclear Information System (INIS)

Cao, Suzhen; Duan, Xiaoli; Zhao, Xiuge; Wang, Beibei; Ma, Jin; Fan, Delong; Sun, Chengye; He, Bin; Wei, Fusheng; Jiang, Guibin

2015-01-01

Manufacture of lead-acid batteries is of widespread interest because of its emissions of heavy metals and metalloids into environment, harming environmental quality and consequently causing detrimental effects on human health. In this study, exposure pathways and health risks of children to heavy metal(loid)s (Pb, Cd, As, etc) were investigated based on field sampling and questionnaire. Pb was one of the most abundant elements in children's blood, with an elevated blood lead level of 12.45 μg dL −1 . Soil/dust and food were heavily polluted by targeted metal(loid)s. Food ingestion accounted for more than 80% of the total exposure for most metal(loid)s. The non-cancer risks to children were 3–10 times higher than the acceptable level of 1, while the cancer risks were 5–200 times higher than the maximum acceptable level of 1.0 × 10 −4 . The study emphasized the significance of effective environmental management, particularly to ensure food security near battery facilities. - Highlights: • The health risks of children living around a typical lead-acid battery was analyzed. • The exposure pathways of children to 12 heavy metal(loid)s were assessed. • Courtyard soil and indoor dust and duplicate food were contaminated by metal(loid)s. • Food ingestion was the major pathway for children's exposure to most metal(loid)s. • Higher potentially non-cancer and cancer risks happened to the local children. - The children living around a typical lead-acid battery plant suffered from serious health risks, which mainly attributed to food ingestion and air inhalation exposure

The structural studies of vanadium substituted lithium-bismuth-boro-tellurite glass

Science.gov (United States)

Madhu, A.; Eraiah, B.

2018-05-01

The structural studies of vanadium substituted lithium-bismuth-boro-tellurite glass is successfully prepared and certain analysis like XRD,FTIR,DTA/TGA with density, molar volume are done. The amorphous phase has been identified based on X-ray diffraction analysis. The vanadium oxide plays the role as a glass-modifier and influences on BO3 ↔ BO4 conversion. The observed nonlinear variation in Tg with vanadium oxide increase, it reflects structural changes. The nonlinear variation of density and molar volume can be attributed to vanadium oxide incorporation have increased the number of Non-bridging oxygen (NBO'S).

Environmental contextualisation of potential toxic elements and polycyclic aromatic hydrocarbons in biochar

International Nuclear Information System (INIS)

Freddo, Alessia; Cai Chao; Reid, Brian J.

2012-01-01

Nine dissimilar biochars, produced from varying feedstock at different pyrolysis temperatures, are appraised with respect to concentrations of potentially toxic elements, specifically, metals, metalloids and polycyclic aromatic hydrocarbons (PAHs). Concentrations of the metals and metalloids varied with the following ranges (mg kg −1 ): 0.02–0.94, Cd; 0.12–6.48, Cr; 0.04–13.2, Cu; 0.1–1.37, Ni; 0.06–3.87, Pb; 0.94–207, Zn and 0.03–0.27, As. Σ 16 PAH concentrations (16 Environmental Protection Agency (EPA) PAHs) range between 0.08 mg kg −1 to 8.7 mg kg −1 . Subsequent comparison with background soil concentrations, concentration applied to the regulation of composted materials (Publicly Available Specification (PAS 100)) and European Union (EU) regulations relating to the application of sewage sludge to agricultural land suggest low risk associated with the concentrations of PTEs observed in biochar. Collectively, results suggest that environmental impacts attributable to metals, metalloids and PAHs associated with biochar following its application to soil are likely to be minimal. - Highlights: ► Concentrations of PTEs varied with feedstock and temperature of production. ► Of the PTEs Zn (0.94–207 mg kg −1 ) was of most priority. ► PTE levels did not infringe guidance values for compost or sewage sludge. ► Biochar ( −1 ) is unlikely to make any real difference to PTE concentrations in soil. - Environmental impacts attributable to metals, metalloids and PAHs associated with biochar following its application to soil are likely to be minimal.

Optical properties of zinc lead tellurite glasses

Science.gov (United States)

Alazoumi, Salah Hassan; Aziz, Sidek Abdul; El-Mallawany, R.; Aliyu, Umar Sa'ad; Kamari, Halimah Mohamed; Zaid, Mohd Hafiz Mohd Mohd; Matori, Khamirul Amin; Ushah, Abdulbaset

2018-06-01

Tellurite glass systems in the form of [ZnO]x [(TeO2)0.7-(PbO)0.3]1-x with x = 0.15, 0.17, 0.20, 0.22 and 0.25 mol% were prepared using the melt quenching technique. XRD of the prepared samples have been measured for all samples. Both FTIR (280-4000 cm-1) and UV-Vis (200-800 nm) spectra have been measured. Optical band gap and refractive index were calculated for every glass sample. Density of glass, molar volume and oxygen packing density (OPD) were obtained. Values of the direct, indirect band gap ranged were found in the range 3.41-3.94 eV and 2.40-2.63 eV with increasing of ZnO concentration. Refractive index 2.58 and dielectric constant 6.66 were heigh at 17 ZnO mol% concentration. Molar polarizability, metallization criterion, polaron radius have been calculated for every glass composition.

Arsenic: A Review of the Element's Toxicity, Plant Interactions, and Potential Methods of Remediation.

Science.gov (United States)

Hettick, Bryan E; Cañas-Carrell, Jaclyn E; French, Amanda D; Klein, David M

2015-08-19

Arsenic is a naturally occurring element with a long history of toxicity. Sites of contamination are found worldwide as a result of both natural processes and anthropogenic activities. The broad scope of arsenic toxicity to humans and its unique interaction with the environment have led to extensive research into its physicochemical properties and toxic behavior in biological systems. The purpose of this review is to compile the results of recent studies concerning the metalloid and consider the chemical and physical properties of arsenic in the broad context of human toxicity and phytoremediation. Areas of focus include arsenic's mechanisms of human toxicity, interaction with plant systems, potential methods of remediation, and protocols for the determination of metals in experimentation. This assessment of the literature indicates that controlling contamination of water sources and plants through effective remediation and management is essential to successfully addressing the problems of arsenic toxicity and contamination.

Dy{sup 3+} ions as optical probes for studying structure of boro-tellurite glasses

Energy Technology Data Exchange (ETDEWEB)

Tuyen, Vu Phi, E-mail: vptuyen@gust-edu.vast.vn [Duytan University, K7/25 Quang Trung, Da Nang (Viet Nam); Graduate University of Science and Technology – VAST, 18 Hoang Quoc Viet, Hanoi (Viet Nam); Sengthong, Bounyavong; Quang, Vu Xuan [Duytan University, K7/25 Quang Trung, Da Nang (Viet Nam); Van Do, Phan [Thuyloi University, 175 Tay Son, Dong Da, Hanoi (Viet Nam); Van Tuyen, Ho; Xuan Hung, Le [Duytan University, K7/25 Quang Trung, Da Nang (Viet Nam); Thanh, Nguyen Trong [Institute of Materials Science – VAST, 18 Hoang Quoc Viet, Hanoi (Viet Nam); Nogami, Masayuki [Duytan University, K7/25 Quang Trung, Da Nang (Viet Nam); Toyota Physical and Chemical research Institute (Japan); Hayakawa, Tomokatsu [Nagoya Institute of Technology, Gokisocho Showaku, 466-8555 Nagoya, Aichiken (Japan); Huy, Bui The, E-mail: buithehuy.nt@gmail.com [Duytan University, K7/25 Quang Trung, Da Nang (Viet Nam); Department of Chemistry, Changwon National University, Changwon 641-773 (Korea, Republic of)

2016-10-15

Dy{sup 3+}-doped glasses with various compositions (35+x)B{sub 2}O{sub 3}+ (45−x)TeO{sub 2}+9.5ZnO+10Na{sub 2}O+0.5Dy{sub 2}O{sub 3} (x=0; 10 and 20) were prepared by a melt–quenching technique. The Dy{sup 3+} ions are used as an optical probe, of which the Judd–Ofelt parameters, the phonon-side band, and the Raman spectra were quantitatively estimated to search the change of glass structure (the change of the ratio of [BO{sub 4}] to [BO{sub 3}] units, formation of the non-bridging oxygens (NBO{sup −}), the change of [TeO{sub 3}] to [TeO{sub 4}] units) as a function of the B{sub 2}O{sub 3} content. The Ω{sub 2} and Ω{sub 6} values of Dy{sup 3+}-doped boro-tellurite samples are larger than that of Dy{sup 3+}-doped borate or tellurite sample. The CIE chromaticity color coordinates were calculated for the luminescence spectra of Dy{sup 3+} ions of the glasses with the different compositions and they were all located in the vicinity of white light center of the color coordination diagram.

Spectroscopic investigation of zinc tellurite glasses doped with Yb3 + and Er3 + ions

Science.gov (United States)

Bilir, Gökhan; Kaya, Ayfer; Cinkaya, Hatun; Eryürek, Gönül

2016-08-01

This paper presents a detailed spectroscopic investigation of zinc tellurite glasses with the compositions (0.80 - x - y) TeO2 + (0.20) ZnO + xEr2O3 + yYb2O3 (x = 0, y = 0; x = 0.004, y = 0; x = 0, y = 0.05 and x = 0.004, y = 0.05 per moles). The samples were synthesized by the conventional melt quenching method. The optical absorption and emission measurements were conducted at room temperature to determine the spectral properties of lanthanides doped zinc tellurite glasses and, to study the energy transfer processes between dopant lanthanide ions. The band gap energies for both direct and indirect possible transitions and the Urbach energies were measured from the absorption spectra. The absorption spectra of the samples were analyzed by using the Judd-Ofelt approach. The effect of the ytterbium ions on the emission properties of erbium ions was investigated and the energy transfer processes between dopant ions were studied by measuring the up-conversion emission properties of the materials. The color quality parameters of obtained visible up-conversion emission were also determined as well as possibility of using the Er3 + glasses as erbium doped fiber amplifiers at 1.55 μm in infrared emission region.

Stabilization of metal(loid)s in two contaminated agricultural soils: Comparing biochar to its non-pyrolysed source material.

Science.gov (United States)

Trakal, Lukáš; Raya-Moreno, Irene; Mitchell, Kerry; Beesley, Luke

2017-08-01

Two metal(loid) contaminated agricultural soils were amended with grape stalk (wine production by-product)-derived biochar as well as its pre-pyrolysed origin material, to investigate their geochemical impacts on As, Cr, Cu and Zn. Detailed physico-chemical evaluation combined with a column leaching test determined the retention of metal(loid)s from soil solution by each amendments. A pot experiment measured metal(loid)s in soil pore water and their uptake to ryegrass when the amendments were mixed into soils at 1 and 5% (w/w). Total Cr and Zn concentrations were reduced furthest in column leachates by the addition of raw material and biochar respectively, compared to the untreated soil; Cr(III) was the predominant specie initially due to rapid acidification of leachates and organic complexation resulting from raw material addition. Loadings of metal(loid)s to the amendments recovered from the post-leached columns were in the order Cu » Zn > Cr ≈ As. In the pot test ryegrass Cr uptake was initiated by the addition of both amendments, compared to the untreated soil, whereas only biochar addition resulted in significant increases in Zn uptake, explained by its significant enhancement of ryegrass biomass yield, especially at 5% dosage; raw material addition significantly decreased biomass yields. Inconsistent relationships between pore water parameters and ryegrass uptake were common to both soils investigated. Therefore, whilst both amendments modified soil metal(loid) geochemistry, their effects differed fundamentally; in environmental risk management terms these results highlight the need to investigate the detailed geochemical response of contaminated soils to diverse organic amendment additions. Copyright © 2017 Elsevier Ltd. All rights reserved.

VOLATILE ORGANO-METALLOIDS IN BIO-SOLID MATERIALS: ANALYSIS BY VACUUM DISTILLATION-GC/MS

Science.gov (United States)

An analytical method based on vacuum distillation-gas chromatography-mass spectrometry (VD-GC-MS)was developed for determining volatile organo-metalloid contaminants in bio-solid materials. Methodperformance was evaluated for dimethylselenide (DMSe), dimethyldisel...

Metals and metalloids in precipitation collected during CHINARE campaign from Shanghai, China, to Zhongshan Station, Antarctica: Spatial variability and source identification

Science.gov (United States)

Shi, G.; Teng, J.; Ma, H.; Li, Y.; Sun, B.

2015-06-01

Metals and metalloids in continental precipitation have been widely observed, but the data over open oceans are still very limited. Investigation of metals and metalloids in marine precipitation is of great significance to understand global transport of these elements in the atmosphere and their input fluxes to the oceans. So shipboard sampling of precipitation was conducted during a Chinese National Antarctic Research Expedition campaign from Shanghai, China, to Zhongshan Station, East Antarctica, and 22 samples (including 17 rainfall and 5 snowfall events) were collected and analyzed for concentrations of Pb, Ni, Cr, Cu, Co, Hg, As, Cd, Sb, Se, Zn, Mn, and Ti. Results show that concentrations of both metals and metalloids vary considerably along the cruise, with higher concentrations at coastal sites and lower values on the south Indian Ocean. Although only soluble fractions were determined for elements, concentrations in this study are generally comparable to the reported values of marine rain. Enrichment factor analysis shows that most of metals and metalloids are enriched versus crustal sources, even in the samples collected from remote south Indian Ocean. In addition, metals and metalloids in precipitation are also very enriched above sea-salt abundance, indicating that impacts of sea-salt aerosols on their concentrations are negligible. Main sources of metals and metalloids were explored with the aid of multivariate statistical analyses. The results show that human emissions have far-reaching distribution, which may exert an important influence on the solubility of elements in precipitation. This investigation provides valuable information on spatial variation and possible sources of trace elements in precipitation over the open oceans corresponding to understudied region.

A review on the importance of metals and metalloids in atmospheric dust and aerosol from mining operations.

Science.gov (United States)

Csavina, Janae; Field, Jason; Taylor, Mark P; Gao, Song; Landázuri, Andrea; Betterton, Eric A; Sáez, A Eduardo

2012-09-01

Contaminants can be transported rapidly and over relatively long distances by atmospheric dust and aerosol relative to other media such as water, soil and biota; yet few studies have explicitly evaluated the environmental implications of this pathway, making it a fundamental but understudied transport mechanism. Although there are numerous natural and anthropogenic activities that can increase dust and aerosol emissions and contaminant levels in the environment, mining operations are notable with respect to the quantity of particulates generated, the global extent of area impacted, and the toxicity of contaminants associated with the emissions. Here we review (i) the environmental fate and transport of metals and metalloids in dust and aerosol from mining operations, (ii) current methodologies used to assess contaminant concentrations and particulate emissions, and (iii) the potential health and environmental risks associated with airborne contaminants from mining operations. The review evaluates future research priorities based on the available literature and suggest that there is a particular need to measure and understand the generation, fate and transport of airborne particulates from mining operations, specifically the finer particle fraction. More generally, our findings suggest that mining operations play an important but underappreciated role in the generation of contaminated atmospheric dust and aerosol and the transport of metal and metalloid contaminants, and highlight the need for further research in this area. The role of mining activities in the fate and transport of environmental contaminants may become increasingly important in the coming decades, as climate change and land use are projected to intensify, both of which can substantially increase the potential for dust emissions and transport. Copyright © 2012 Elsevier B.V. All rights reserved.

A Review on the Importance of Metals and Metalloids in Atmospheric Dust and Aerosol from Mining Operations

Science.gov (United States)

Csavina, Janae; Field, Jason; Taylor, Mark P.; Gao, Song; Landázuri, Andrea; Betterton, Eric A.; Sáez, A. Eduardo

2012-01-01

Contaminants can be transported rapidly and over relatively long distances by atmospheric dust and aerosol relative to other media such as water, soil and biota; yet few studies have explicitly evaluated the environmental implications of this pathway, making it a fundamental but understudied transport mechanism. Although there are numerous natural and anthropogenic activities that can increase dust and aerosol emissions and contaminant levels in the environment, mining operations are notable with respect to the quantity of particulates generated, the global extent of area impacted, and the toxicity of contaminants associated with the emissions. Here we review (i) the environmental fate and transport of metals and metalloids in dust and aerosol from mining operations, (ii) current methodologies used to assess contaminant concentrations and particulate emissions, and (iii) the potential health and environmental risks associated with airborne contaminants from mining operations. The review evaluates future research priorities based on the available literature and suggest that there is a particular need to measure and understand the generation, fate and transport of airborne particulates from mining operations, specifically the finer particle fraction. More generally, our findings suggest that mining operations play an important but underappreciated role in the generation of contaminated atmospheric dust and aerosol and the transport of metal and metalloid contaminants, and highlight the need for further research in this area. The role of mining activities in the fate and transport of environmental contaminants may become increasingly important in the coming decades, as climate change and land use are projected to intensify, both of which can substantially increase the potential for dust emissions and transport. PMID:22766428

Blood and urinary levels of metals and metalloids in the general adult population of Northern France: The IMEPOGE study, 2008-2010.

Science.gov (United States)

Nisse, Catherine; Tagne-Fotso, Romuald; Howsam, Mike; Richeval, Camille; Labat, Laurence; Leroyer, Ariane

2017-04-01

French national survey for the same period except for urinary V. Mean blood lead level was markedly less than that of the French national population. This first biomonitoring survey of a large number of metal(loid)s in the general population of Northern France provides useful information on exposure levels to toxic elements and highlights the specificity of the regional environment. These data could be used, in complement to the national human biomonitoring reference values, for the interpretation of biomonitoring results. Copyright © 2016 Elsevier GmbH. All rights reserved.

Spectroscopic investigation of zinc tellurite glasses doped with Yb(3+) and Er(3+) ions.

Science.gov (United States)

Bilir, Gökhan; Kaya, Ayfer; Cinkaya, Hatun; Eryürek, Gönül

2016-08-05

This paper presents a detailed spectroscopic investigation of zinc tellurite glasses with the compositions (0.80-x-y) TeO2+(0.20) ZnO+xEr2O3+yYb2O3 (x=0, y=0; x=0.004, y=0; x=0, y=0.05 and x=0.004, y=0.05 per moles). The samples were synthesized by the conventional melt quenching method. The optical absorption and emission measurements were conducted at room temperature to determine the spectral properties of lanthanides doped zinc tellurite glasses and, to study the energy transfer processes between dopant lanthanide ions. The band gap energies for both direct and indirect possible transitions and the Urbach energies were measured from the absorption spectra. The absorption spectra of the samples were analyzed by using the Judd-Ofelt approach. The effect of the ytterbium ions on the emission properties of erbium ions was investigated and the energy transfer processes between dopant ions were studied by measuring the up-conversion emission properties of the materials. The color quality parameters of obtained visible up-conversion emission were also determined as well as possibility of using the Er(3+) glasses as erbium doped fiber amplifiers at 1.55μm in infrared emission region. Copyright © 2016 Elsevier B.V. All rights reserved.

All-optical control of group velocity dispersion in tellurite photonic crystal fibers.

Science.gov (United States)

Liu, Lai; Tian, Qijun; Liao, Meisong; Zhao, Dan; Qin, Guanshi; Ohishi, Yasutake; Qin, Weiping

2012-12-15

We demonstrate all-optical control of group velocity dispersion (GVD) via optical Kerr effect in highly nonlinear tellurite photonic crystal fibers. The redshift of the zero-dispersion wavelength is over 307 nm, measured by soliton self-frequency shift cancellation, when the pump peak power of a 1.56 μm femtosecond fiber laser is increased to 11.6 kW. The all-optical control of GVD not only offers a new platform for constructing all-optical-control photonic devices but also promises a new class of experiments in nonlinear fiber optics and light-matter interactions.

Short-range structure and thermal properties of barium tellurite glasses

Science.gov (United States)

Kaur, Amarjot; Khanna, Atul; Gonzàlez, Fernando

2017-05-01

BaO-TeO2 glasses containing 10 to 20 BaO mol% were prepared and characterized by X-ray diffraction, density measurements, differential scanning calorimetry and Raman spectroscopy. Glass density decreases with increase in BaO concentration from 10 to 20 mol%, due to replacement of heavier TeO2 by lighter BaO, however glass transition temperature (Tg) increases significantly from a value of 318°C to 327°C due to increase in average single bond enthalpy of the tellurite network. Raman studies found that glass short-range structure consists of TeO4 and TeO3 structural units and BaO modifies the network by producing the structural transformation: TeO4→ TeO3.

Structural and optical study of tellurite-barium glasses

Science.gov (United States)

Grelowska, I.; Reben, M.; Burtan, B.; Sitarz, M.; Cisowski, J.; Yousef, El Sayed; Knapik, A.; Dudek, M.

2016-12-01

The goal of this work was to determine the effect of barium oxide on the structural, thermal and optical properties of the TeO2-BaO-Na2O (TBN) and TeO2-BaO-WO3 (TBW) glass systems. Raman spectra allow relating the glass structure and vibration properties (i.e. vibrational frequencies and Raman intensities) with the glass composition. Raman spectra show the presence of TeO4 and TeO3+1/TeO3 units that conform with the glass matrix. Differential thermal analysis DTA, XRD measurements have been considered in term of BaO addition. The spectral dependence of ellipsometric angles of the tellurite-barium glass has been studied. The optical measurements were conducted on Woollam M2000 spectroscopic ellipsometer in spectral range of 190-1700 nm. The reflectance and transmittance measurements have been done on spectrophotometer Perkin Elmer, Lambda 900 in the range of 200-2500 nm (UV-VIS-NIR). From the transmittance spectrum, the energy gap was determined.

Toxicity of a metal(loid)-polluted agricultural soil to Enchytraeus crypticus changes under a global warming perspective: Variations in air temperature and soil moisture content.

Science.gov (United States)

González-Alcaraz, M Nazaret; van Gestel, Cornelis A M

2016-12-15

This study aimed to assess how the current global warming perspective, with increasing air temperature (20°C vs. 25°C) and decreasing soil moisture content (50% vs. 30% of the soil water holding capacity, WHC), affected the toxicity of a metal(loid)-polluted agricultural soil to Enchytraeus crypticus. Enchytraeids were exposed for 21d to a dilution series of the agricultural soil with Lufa 2.2 control soil under four climate situations: 20°C+50% WHC (standard conditions), 20°C+30% WHC, 25°C+50% WHC, and 25°C+30% WHC. Survival, reproduction and bioaccumulation of As, Cd, Co, Cu, Fe, Mn, Ni, Pb and Zn were obtained as endpoints. Reproduction was more sensitive to both climate factors and metal(loid) pollution. High soil salinity (electrical conductivity~3dSm -1 ) and clay texture, even without the presence of high metal(loid) concentrations, affected enchytraeid performance especially at drier conditions (≥80% reduction in reproduction). The toxicity of the agricultural soil increased at drier conditions (10% reduction in EC10 and EC50 values for the effect on enchytraeid reproduction). Changes in enchytraeid performance were accompanied by changes in As, Fe, Mn, Pb and Zn bioaccumulation, with lower body concentrations at drier conditions probably due to greater competition with soluble salts in the case of Fe, Mn, Pb and Zn. This study shows that apart from high metal(loid) concentrations other soil properties (e.g. salinity and texture) may be partially responsible for the toxicity of metal(loid)-polluted soils to soil invertebrates, especially under changing climate conditions. Copyright © 2016 Elsevier B.V. All rights reserved.

Determination of soluble ultra-trace metals and metalloids in rainwater and atmospheric deposition fluxes: a 2-year survey and assessment.

Science.gov (United States)

Montoya-Mayor, R; Fernández-Espinosa, A J; Seijo-Delgado, I; Ternero-Rodríguez, M

2013-08-01

The present work investigates the relationships between composition of rainwater and dry deposition fluxes by trace metals and metalloids. A modification in automatic "wet-only" and "dry-only" samplers was applied, which allowed the collection and conservation of samples separately. ICP-MS technique was used for the determination of analytes in samples. Concentrations of soluble elements in rainwater were measured directly in filtered samples. A sequential acid treatment with nitric, hydrofluoric and finally perchloric acids was used to measure the total contents of metals and metalloids in coarse particles. Variation between periods of heavy and light rains was assessed. Almost all of the metals and metalloids - B, Tl, Th, U, Al, Cs, Be, Ti and others - studied in dry deposition showed important decreases in concentrations (40-92%) during periods of heavy rainfall. Most of these metals and metalloids - As, Cr, Co, Ni - presented their highest levels (53-90%) in heavy rainfall periods in rainwater samples. Sources were identified in both types of samples collected using a new chemometric tool (SPCA). Urban traffic, surrounding contaminated soils and local anthropogenic sources were identified for rainwater samples. Natural and contaminated soils and general anthropogenic emissions were the sources identified for dry deposition fluxes. Copyright © 2013 Elsevier Ltd. All rights reserved.

Photoluminescence study of Sm{sup 3+}–Yb{sup 3+}co-doped tellurite glass embedding silver nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Reza Dousti, M., E-mail: mrdousti@ifsc.usp.br [Laboratório de Espectroscopia de Materiais Funcionais (LEMAF), Instituto de Fisica de São Carlos, Universidade de São Paulo, Av. Trabalhador So-carlense 400, São Carlos, SP 13566-590 (Brazil); Department of Physics, Tehran-North Branch, Islamic Azad University Tehran (Iran, Islamic Republic of); Department of Physics, Faculty of Science, Universiti Teknologi Malaysia, Skudai 81310, Johor (Malaysia); Amjad, R.J. [Department of Physics, Faculty of Science, Universiti Teknologi Malaysia, Skudai 81310, Johor (Malaysia); Department of Physics, COMSATS Institute of Information Technology, Lahore 54000 (Pakistan); Hosseinian S, R.; Salehi, M.; Sahar, M.R. [Department of Physics, Faculty of Science, Universiti Teknologi Malaysia, Skudai 81310, Johor (Malaysia)

2015-03-15

We report on the upconversion emission of Sm{sup 3+} ions doped tellurite glass in the presence of Yb{sup 3+} ions and silver nanoparticles. The enhancement of infrared-to-visible upconversion emissions is achieved under 980 nm excitation wavelength and attributed to the high absorption cross section of Yb{sup 3+} ions and an efficient energy transfer to Sm{sup 3+} ions. Further enhancements are attributed to the plasmonic effect via metallic nanoparticles resulting in the large localized field around rare earth ions. However, under excitation at 406 nm, the addition of Yb{sup 3+} content and heat-treated silver nanoparticles quench the luminescence of Sm{sup 3+} ions likely due to quantum cutting and plasmonic diluent effects, respectively. - Highlights: • Sm{sup 3+} tellurite glasses co-doped with Yb{sup 3+} ions and tri-doped with Yb{sup 3+}:Ag NPs were prepared. • In first step, Yb{sup 3+} ions enhanced the upconversion emissions of Sm{sup 3+} doped samples. • In second step, Ag NPs further enhanced the upconversion emissions in tri-doped glasses. • Finally, the quench in luminescence under 406 nm excitation is observed and discussed.

Structural characterization of tellurite glasses doped with transition metal oxides using Raman spectra and ab initio calculations.

Science.gov (United States)

Mohamed, Tarek A; Shaltout, I; Al Yahyaei, K M

2006-05-01

Systems of iron tellurite glasses were prepared by melt quenching with compositions of [85%TeO2+5%Fe2O3+10%TMO], where transition metal oxides (TMO) are TiO2, V2O5, MnO, CoO, NiO and CuO. Furthermore, the main structural units of these samples have been characterized by means of Raman spectra (150-1200 cm(-1)) as well as wavenumber predictions by means of Gaussian 98 ab initio calculations for the proposed site symmetries of TeO4(4-) triagonal bipyramid (C2v) and Te2O7(6-) bridged tetrahedra (Cs and C1). Aided by normal coordinate analysis, calculated vibrational frequencies, Raman scattering activities, force constants in internal coordinates and potential energy distributions (PEDs), revised vibrational assignments for the fundamental modes have been proposed. The main structural features are correlated to the dominant units of triagonal bipyramid (tbp) or bridged tetrahedral (TeO3+1 binds to TeO3 through TeOTe bridge; corner sharing). Moreover, the Raman spectra of the investigated tellurites reflect a structural change from tbp (coordination number is four) to triagonal pyramidal (coordination number is three).

Continuous leaching modifies the surface properties and metal(loid) sorption of sludge-derived biochar.

Science.gov (United States)

Feng, Mingyu; Zhang, Weihua; Wu, Xueyong; Jia, Yanming; Jiang, Chixiao; Wei, Hang; Qiu, Rongliang; Tsang, Daniel C W

2018-06-01

After the application of sludge derived biochar (SDBC) for soil stabilization, it is subjected to continuous leaching that may change its surface properties and metal(loid) immobilization performance. This study simulated the continuous leaching through the fresh SDBC sample in columns with unsaturated and saturated zones under flushing with 0.01M NaNO 3 solution (pH5.5) and acidic solution (pH adjusted to 3.2 by HNO 3 :H 2 SO 4 =1:2), respectively. The resultant changes were assessed in terms of the SDBC surface characteristics and metal(loid) sorption capacities. Continuous leaching was found to gradually decrease the density of basic functional groups and increase the density of carboxyl groups as well as cation exchange capacity on the SDBC surface. It was attributed to the surface acidification and oxidation process by the leaching process, yet it occurred to a lesser extent than the atmospheric exposure. Continuous leaching increased Pb(II), Cr(VI), and As(III) sorption capacity of the SDBC, probably because the increase in carboxyl groups promoted inner-sphere complexation and Fe oxidation as revealed by spectroscopic analysis. It was noteworthy that the SDBC in the unsaturated and saturated zones under continuous leaching displayed distinctive effects on metal(loid) sorption capacity than the atmospheric exposure. Future investigations are needed for understanding the fate and interactions of the SDBC under varying redox conditions and intermittent leaching process. Copyright © 2017. Published by Elsevier B.V.

Improved ionic conductivity of lithium-zinc-tellurite glass-ceramic electrolytes

Directory of Open Access Journals (Sweden)

W. Widanarto

Full Text Available An enhancement in the secondary battery safety demands the optimum synthesis of glass-ceramics electrolytes with modified ionic conductivity. To achieve improved ionic conductivity and safer operation of the battery, we synthesized Li2O included zinc-tellurite glass-ceramics based electrolytes of chemical composition (85-xTeO2·xLi2O·15ZnO, where x = 0, 5, 10, 15 mol%. Samples were prepared using the melt quenching method at 800 °C followed by thermal annealing at 320 °C for 3 h and characterized. The effects of varying temperature, alternating current (AC frequency and Li2O concentration on the structure and ionic conductivity of such glass-ceramics were determined. The SEM images of the annealed glass-ceramic electrolytes displayed rough surface with a uniform distribution of nucleated crystal flakes with sizes less than 1 μm. X-ray diffraction analysis confirmed the well crystalline nature of achieved electrolytes. Incorporation of Li2O in the electrolytes was found to generate some new crystalline phases including hexagonal Li6(TeO6, monoclinic Zn2Te3O8 and monoclinic Li2Te2O5. The estimated crystallite size of the electrolyte was ranged from ≈40 to 80 nm. AC impedance measurement revealed that the variation in the temperatures, Li2O contents, and high AC frequencies have a significant influence on the ionic conductivity of the electrolytes. Furthermore, electrolyte doped with 15 mol% of Li2O exhibited the optimum performance with an ionic conductivity ≈2.4 × 10−7 S cm−1 at the frequency of 54 Hz and in the temperature range of 323–473 K. This enhancement in the conductivity was attributed to the sizable alteration in the ions vibration and ruptures of covalent bonds in the electrolytes network structures. Keywords: Zinc-tellurite, Glass-ceramics, X-ray diffraction, Ionic conductivity, Lithium oxide

The influence of ytterbium doping on the optical properties of tellurite glasses

Energy Technology Data Exchange (ETDEWEB)

Jaglarz, Janusz; Burtan, Bozena [Institute of Physics, Cracow University of Technology, ul. Podchorazych 1, 30-084 Cracow (Poland); Reben, Manuela; Wasylak, Jan [Faculty of Materials Science and Ceramics, AGH - University of Science and Technology, al. Mickiewicza 30, 30-059 Cracow (Poland); Cisowski, Jan [Institute of Physics, Cracow University of Technology, ul. Podchorazych 1, 30-084 Cracow (Poland); Centre of Polymer and Carbon Materials, Polish Academy of Sciences, ul. M. Curie-Sklodowskiej 34, 41-819 Zabrze (Poland); Jarzabek, Bozena [Centre of Polymer and Carbon Materials, Polish Academy of Sciences, ul. M. Curie-Sklodowskiej 34, 41-819 Zabrze (Poland)

2011-09-15

The goal of this work was to investigate the influence of rare earth ion Yb{sup 3+} doping on the thermal and optical properties of tellurite glass (TG) of the TeO{sub 2}-ZnO-PbO-La{sub 2}O{sub 3} system. The reflectance, transmittance and ellipsometric measurements have been done. Decreasing of the refractive index of TG with the Yb{sup 3+} ion doping has been concluded. For determination of the refractive index variation in the bulk, the small angle light scatter (SALS) measurements have been carried out. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Ecological and human health risks from metal(loid)s in peri-urban soil in Nanjing, China.

Science.gov (United States)

Ding, Zhuhong; Hu, Xin

2014-06-01

In order to investigate the ecological and human health risks of metal(loid)s (Cu, Pb, Zn, Ni, Cd, Mn, Cr, and As) in peri-urban soils, 43 surface soil samples were collected from the peri-urban area around Nanjing, a megacity in China. The average contents were 1.19, 67.8, 37.6, 105, 167, 44.6, 722, and 50.8 mg kg(-1) for Cd, Cr, Ni, Pb, Zn, Cu, Mn, and As, respectively. A significant positive correlation was found between Cu, Pb, Zn, Cd, Mn, and As (p urban soil samples. Potential ecological risk indices show that the metal(loid)s in the soil could result in higher ecological risks. Cd is the main contributor to the risk, followed by As. The levels of Cu, Pb, Zn, Cd, Mn, and As in stomach and intestinal phases show a positive linear correlation with their total contents. Mn, Zn, Ni, Cd, and Pb in stomach phase showed higher bioaccessibility, while in intestinal phase, Cu, Cr, and As had the higher bioaccessibility. The carcinogenic risk in children and adults posed by As, Pb, and Cr via ingestion was deemed acceptable. The non-carcinogenic risks posed by these metal(loid)s via ingestion to children are higher than to adults and mainly result from As.

Decreased vaccine antibody titers following exposure to multiple metals and metalloids in e-waste-exposed preschool children.

Science.gov (United States)

Lin, Xinjiang; Xu, Xijin; Zeng, Xiang; Xu, Long; Zeng, Zhijun; Huo, Xia

2017-01-01

We explored acquired immunity resulting from vaccination in 3 to 7-year-old children, chronically exposed to multiple heavy metals and metalloids, in an e-waste recycling area (Guiyu, China). Child blood levels of ten heavy metals and metalloids, including lead (Pb), arsenic (As), mercury (Hg), chromium (Cr), cadmium (Cd), manganese (Mn), nickel (Ni), copper (Cu), zinc (Zn) and selenium (Se), and seven vaccine antibodies (diphtheria, pertussis, tetanus, hepatitis B, Japanese encephalitis, polio, measles) were measured. The exposed group had higher levels of blood Pb, Mn, Cu, Zn and Cr compared to the reference group (P 10 μg/dL) and high blood Cu and Zn (upper median value of each group) to be inversely associated with seven antibody titers. Antibody titers increased with age, BMI, high blood Mn (>15 μg/L), and high blood Cd and Ni (upper median value of each group). Results suggest multiple heavy metal and metalloid exposure, especially to Pb, Zn and Cu, may be a risk factor inhibiting the development of child immunity, resulting in decreased child antibody levels against vaccines. Copyright © 2016 Elsevier Ltd. All rights reserved.

RETROSPECTIVE STUDY OF METHYLMERCURY AND OTHER METAL(LOID)S IN MADAGASCAR UNPOLISHED RICE (Oryza sativa L.)

Science.gov (United States)

Rothenberg, Sarah E.; Mgutshini, Noma L.; Bizimis, Michael; Johnson-Beebout, Sarah E.; Ramanantsoanirina, Alain

2014-01-01

The rice ingestion rate in Madagascar is among the highest globally; however studies concerning metal(loid) concentrations in Madagascar rice are lacking. For Madagascar unpolished rice (n=51 landraces), levels of toxic elements (e.g., total mercury, methylmercury, arsenic and cadmium) as well as essential micronutrients (e.g., zinc and selenium) were uniformly low, indicating potentially both positive and negative health effects. Aside from manganese (Wilcoxon rank sum, p<0.01), no significant differences in concentrations for all trace elements were observed between rice with red bran (n=20) and brown bran (n=31) (Wilcoxon rank sum, p=0.06–0.91). Compared to all elements in rice, rubidium (i.e., tracer for phloem transport) was most positively correlated with methylmercury (Pearson's r=0.33, p<0.05) and total mercury (r=0.44, p<0.05), while strontium (i.e., tracer for xylem transport) was least correlated with total mercury and methylmercury (r<0.01 for both), suggesting inorganic mercury and methylmercury were possibly more mobile in phloem compared to xylem. PMID:25463705

Concentration dependent luminescence quenching of Er{sup 3+}-doped zinc boro-tellurite glass

Energy Technology Data Exchange (ETDEWEB)

Said Mahraz, Zahra Ashur; Sahar, M.R., E-mail: mrahim057@gmail.com; Ghoshal, S.K.; Reza Dousti, M.

2013-12-15

Understanding the mechanism of luminescence quenching in rare earth doped tellurite glass is an important issue. The Er{sup 3+}-doped boro-tellurite glasses with compositions 30B{sub 2}O{sub 3}+10ZnO+(60−x)TeO{sub 2}+xEr{sub 2}O{sub 3} (where x=0, 0.5, 1, 1.5 and 2 mol%) were prepared by melt quenching method. Structural and optical properties of the proposed glasses were characterized using XRD, FTIR, density, UV–vis-IR absorption and PL spectroscopy. The amorphous nature of these glasses was confirmed by XRD technique. The IR-spectrum reveals five absorption bands assigned to different B–O and Te–O vibrational groups. UV–vis-IR absorption spectrum exhibits seven absorption bands at 6553, 10,244, 12,547, 15,360, 19,230, 20,661 and 22,522 cm{sup −1} corresponding to {sup 4}I{sub 13/2}, {sup 4}I{sub 11/2}, {sup 4}I{sub 9/2}, {sup 4}F{sub 9/2}, {sup 2}H{sub 11/2}, {sup 4}F{sub 7/2} and {sup 4}F{sub 3/2} excited states of Er{sup 3+} ion respectively. The optical band gap energy (E{sub opt}) corresponding to the direct and indirect allowed transitions decreased, while the Urbach energy and cut-off wavelengths are increased by the introduction of Er{sup 3+} ions. The refractive index, density and phonon cut-off edge of the samples are increased and the molar volume decreased with the further addition of dopants. The Judd–Ofelt parameter (Ω{sub 2}) decreased from 5.73 to 3.13×10{sup −20} cm{sup 2} with the increase of erbium ions concentration from 0.5 to 2 mol%. The PL spectra show green emissions for the transition from {sup 2}H{sub 11/2} and {sup 4}S{sub 3/2} excited states to {sup 4}I{sub 15/2} ground state, which show strong quenching due to the addition of Er{sup 3+} ions. -- Highlights: • Er{sup 3+}-doped zinc boro-tellurite glass has been synthesized by melt quench method. • Spectroscopic properties dependent concentration is analyzed by different techniques. • Judd–Ofelt intensity parameter (Ω{sub 2}) decreased by increase in erbium

Supplementary dataset for child and adult exposure and health risk evaluation following the use of metal- and metalloid-containing costume cosmetics sold in the United States

Directory of Open Access Journals (Sweden)

Angela L. Perez

2017-08-01

Full Text Available The data presented in this article are related to the research article entitled "Child and adult exposure and health risk evaluation following the use of metal- and metalloid-containing costume cosmetics sold in the United States" [1]. This article describes the concentration of metals and metalloids contained in various cosmetic products such as body paint, lipstick and eye shadow, the relative percent deviation of two analyses performed on the products and the physico-chemico properties of the metals and metalloids used in the SkinPerm model presented in the aforementioned article.

Selenite and tellurite form mixed seleno- and tellurotrisulfides with CstR from Staphylococcus aureus

OpenAIRE

Luebke, Justin L.; Arnold, Randy J.; Giedroc, David P.

2013-01-01

Staphylococcus aureus CstR (CsoR-like sulfur transferase repressor) is a member of the CsoR family of transition metal sensing metalloregulatory proteins. Unlike CsoR, CstR does not form a stable complex with transition metals but instead reacts with sulfite to form a mixture of di- and trisulfide species, CstR2(RS-SR′) and CstR2(RS-S-SR′)n, n = 1 or 2, respectively. Here, we investigate if CstR performs similar chemistry with related chalcogen oxyanions selenite and tellurite. In this work w...

Roles of biomarkers in evaluating interactions among mixtures of lead, cadmium and arsenic

International Nuclear Information System (INIS)

Wang Gensheng; Fowler, Bruce A.

2008-01-01

Human exposure to environmental chemicals is most correctly characterized as exposure to mixtures of these agents. The metals/metalloids, lead (Pb), cadmium (Cd), and arsenic (As), are among the leading toxic agents detected in the environment. Exposure to these elements, particularly at chronic low dose levels, is still a major public health concern. Concurrent exposure to Pb, Cd, or As may produce additive or synergistic interactions or even new effects that are not seen in single component exposures. Evaluating these interactions on a mechanistic basis is essential for risk assessment and management of metal/metalloid mixtures. This paper will review a number of individual studies that addressed interactions of these metals/metalloids in both experimental and human exposure studies with particular emphasis on biomarkers. In general, co-exposure to metal/metalloid mixtures produced more severe effects at both relatively high dose and low dose levels in a biomarker-specific manner. These effects were found to be mediated by dose, duration of exposure and genetic factors. While traditional endpoints, such as morphological changes and biochemical parameters for target organ toxicity, were effective measures for evaluating the toxicity of high dose metal/metalloid mixtures, biomarkers for oxidative stress, altered heme biosynthesis parameters, and stress proteins showed clear responses in evaluating toxicity of low dose metal/metalloid mixtures. Metallothionein, heat shock proteins, and glutathione are involved in regulating interactive effects of metal/metalloid mixtures at low dose levels. These findings suggest that further studies on interactions of these metal/metalloid mixtures utilizing biomarker endpoints are highly warranted

In-Situ Analysis Of Metal(loid)s In Plants: State Of The Art And Artefacts

Science.gov (United States)

Metals and metalloids play important roles in plant function and metabolism. Likewise, plants subsequently introduce vital dietary nutrition to people and animals. Understanding the transport, localisation and speciation of these elements is critical for understanding availabil...

Critical V₂O₅/TeO₂ ratio inducing abrupt property changes in vanadium tellurite glasses

DEFF Research Database (Denmark)

Kjeldsen, Jonas; Rodrigues, Ana C. M.; Mossin, Susanne

2014-01-01

Transition metal containing glasses have unique electrical properties and are therefore often used for electrochemical applications, such as in batteries. Among oxide glasses, vanadium tellurite glasses exhibit the highest electronic conductivity and thus the high potential for applications. In t...

Heavy metal(loid)s and organic contaminants in groundwater in the Pearl River Delta that has undergone three decades of urbanization and industrialization: Distributions, sources, and driving forces.

Science.gov (United States)

Huang, Guanxing; Zhang, Ming; Liu, Chunyan; Li, Liangping; Chen, Zongyu

2018-09-01

Urbanization and industrialization have increased groundwater resource demands, and may drive the change of heavy metal(loid)s and organic chemicals in groundwater in the Pearl River Delta (PRD), southern China. Thus, a comprehensive understanding of the distributions, sources, and driving forces of heavy metal(loid)s and organic chemicals in groundwater in the PRD is vital for water resource management in this region. In this study, eight heavy metal(loid)s and fifty-five organic chemicals in groundwater across the PRD were investigated. The results show that undrinkable groundwater related to heavy metal(loid)s was mainly due to high concentrations of Fe (19.3%) and As (6.8%). Eighteen organic contaminants were detected in groundwater in the PRD, where the most frequently detected organic contaminant was naphthalene, and its detection rate was 2.51%. In 5.3% of all groundwater samples, one or more organic contaminants were found. All detected organic contaminants, except ones without allowable limits, in groundwater were at concentrations below allowable limits of China. The mean concentrations of heavy metal(loid)s in granular aquifers were higher than those in fissured and karst aquifers, especially for Fe and As. Except Se, the mean concentrations of other heavy metal(loid)s and the frequency of detection of organic contaminants in groundwater in urbanized and peri-urban areas were higher than those in non-urbanized areas, especially for Hg, Co, and organic contaminants. Fe, As, and Se in groundwater mainly originated from the release of Fe/As/Se rich sediments. The former two were driven by reduction reactions, while the latter was driven by oxidation resulting from the infiltration of NO 3 - . In contrast, other five heavy metal(loid)s and organic contaminants in groundwater mainly originated from the anthropogenic sources, such as the infiltration of industrial sewage. It is evident that urbanization and industrialization are two powerful driving forces for

Laboratory dust generation and size-dependent characterization of metal and metalloid-contaminated mine tailings deposits

Energy Technology Data Exchange (ETDEWEB)

Gonzales, Patricia; Felix, Omar [Department of Chemical and Environmental Engineering, University of Arizona, 1133 E. James E. Rogers Way, Tucson, AZ 85721 (United States); Alexander, Caitlin; Lutz, Eric [Division of Community, Environment, and Policy, Mel and Enid Zuckerman College of Public Health, University of Arizona, 1656 E. Mabel St., Tucson, AZ 85724 (United States); Ela, Wendell [Department of Chemical and Environmental Engineering, University of Arizona, 1133 E. James E. Rogers Way, Tucson, AZ 85721 (United States); Eduardo Sáez, A., E-mail: esaez@arizona.edu [Department of Chemical and Environmental Engineering, University of Arizona, 1133 E. James E. Rogers Way, Tucson, AZ 85721 (United States)

2014-09-15

Highlights: • A laboratory dust fractionator was developed for the production of respirable dust. • The size-dependent distribution of arsenic and lead in mine tailings dust is reported. • Metal and metalloid contaminants are enriched in particles smaller than 10 μm. • Lead isotope signatures show spread of mine tailings particles onto surrounding soils. - Abstract: The particle size distribution of mine tailings material has a major impact on the atmospheric transport of metal and metalloid contaminants by dust. Implications to human health should be assessed through a holistic size-resolved characterization involving multidisciplinary research, which requires large uniform samples of dust that are difficult to collect using conventional atmospheric sampling instruments. To address this limitation, we designed a laboratory dust generation and fractionation system capable of producing several grams of dust from bulk materials. The equipment was utilized in the characterization of tailings deposits from the arsenic and lead-contaminated Iron King Superfund site in Dewey-Humboldt, Arizona. Results show that metal and metalloid contaminants are more concentrated in particles of <10 μm aerodynamic diameter, which are likely to affect surrounding communities and ecosystems. In addition, we traced the transport of contaminated particles from the tailings to surrounding soils by identifying Pb and Sr isotopic signatures in soil samples. The equipment and methods developed for this assessment ensure uniform samples for further multidisciplinary studies, thus providing a tool for comprehensive representation of emission sources and associated risks of exposure.

Laboratory dust generation and size-dependent characterization of metal and metalloid-contaminated mine tailings deposits

International Nuclear Information System (INIS)

Gonzales, Patricia; Felix, Omar; Alexander, Caitlin; Lutz, Eric; Ela, Wendell; Eduardo Sáez, A.

2014-01-01

Highlights: • A laboratory dust fractionator was developed for the production of respirable dust. • The size-dependent distribution of arsenic and lead in mine tailings dust is reported. • Metal and metalloid contaminants are enriched in particles smaller than 10 μm. • Lead isotope signatures show spread of mine tailings particles onto surrounding soils. - Abstract: The particle size distribution of mine tailings material has a major impact on the atmospheric transport of metal and metalloid contaminants by dust. Implications to human health should be assessed through a holistic size-resolved characterization involving multidisciplinary research, which requires large uniform samples of dust that are difficult to collect using conventional atmospheric sampling instruments. To address this limitation, we designed a laboratory dust generation and fractionation system capable of producing several grams of dust from bulk materials. The equipment was utilized in the characterization of tailings deposits from the arsenic and lead-contaminated Iron King Superfund site in Dewey-Humboldt, Arizona. Results show that metal and metalloid contaminants are more concentrated in particles of <10 μm aerodynamic diameter, which are likely to affect surrounding communities and ecosystems. In addition, we traced the transport of contaminated particles from the tailings to surrounding soils by identifying Pb and Sr isotopic signatures in soil samples. The equipment and methods developed for this assessment ensure uniform samples for further multidisciplinary studies, thus providing a tool for comprehensive representation of emission sources and associated risks of exposure

All-solid tellurite optical fiber with transversely disordered refractive index profile and its optical image transport performance

Science.gov (United States)

Tong, Hoang Tuan; Kuroyanagi, Shunei; Suzuki, Takenobu; Ohishi, Yasutake

2018-02-01

All-solid tellurite-glass optical rod and fiber with transversely-disordered refractive index profile were successfully fabricated to study the transport of infrared images by using transverse localization of light. The fabrication was carried out by using stack-and-draw and rod-in-tube techniques. The fabricated tellurite optical rod and fiber were composed of high-index and low-index units which were arranged randomly in the transverse plane but were invariant in the longitudinal direction. The diameter of each unit was approximately 1.0 μm. The high-index and low-index materials were TeO2-Li2O-WO3-MoO3-Nb2O5 (TLWMN) glass and TeO2-ZnO-Na2O-La2O3 (TZNL) glass, respectively. At 1550 nm, their refractive index difference Δn is 0.096. To investigate the optical image transport capability, A CW laser light at 1550 nm was used as an input probe beam and the 1951 U.S. Air Force test target was installed in front of 10-cm-long segments of the fabricated rod and fiber in the experimental setup. The output signal was recorded by a beam profiler. As a result, clear transported images of numbers and lines on the test target were obtained.

Mass spectrometric study of vaporization of cesium tellurate and tellurite

International Nuclear Information System (INIS)

Semenov, G.A.; Fokina, L.A.; Mouldagalieva, R.A.

1994-01-01

The process of vaporization of cesium tellurate and tellurite was studied by the Knudsen effusion method with a mass spectrometric analysis of the vapor composition. The thermal dissociation of Cs 2 TeO 4 to Cs 2 TeO 3 and the congruent vaporization of Cs 2 TeO 3 were established. Thermodynamic functions for gaseous Cs 2 TeO 3 have been calculated. The standard enthalpy of sublimation Δ s H (298.15)=268.1±13.0 kJ mol -1 was determined by the 2nd and 3rd laws of thermodynamics. The enthalpy of formation Δ f H (298.15)=-725.1±13.0 kJ mol -1 for gaseous Cs 2 TeO 3 and the enthalpy of atomization Δ at H (298.15)=1841.3±15.0 kJ mol -1 have been computed. ((orig.))

Enhanced 1.32 μm fluorescence and broadband amplifying for O-band optical amplifier in Nd3+-doped tellurite glass

Science.gov (United States)

Zhou, Zi-zhong; Zhou, Ming-han; Su, Xiu-e.; Cheng, Pan; Zhou, Ya-xun

2017-01-01

WO3 oxides with relatively high phonon energy and different concentrations were introduced into the Nd3+-doped tellurite-based glasses of TeO2-ZnO-Na2O to improve the 1.32 μm band fluorescence emission. The absorption spectra, Raman spectra, 1.32 μm band fluorescence spectra and differential scanning calorimeter (DSC) curves were measured, together with the Judd-Ofelt intensity parameters, stimulated emission and gain parameters were calculated to evaluate the effects of WO3 amount on the glass structure and spectroscopic properties of 1.32 μm band fluorescence. It is shown that the introduction of an appropriate amount of WO3 oxide can effectively improve the 1.32 μm band fluorescence intensity through the enhanced multi-phonon relaxation (MPR) processes between the excited levels of Nd3+. The results indicate that the prepared Nd3+-doped tellurite glass with an appropriate amount of WO3 oxide is a potential gain medium applied for the O-band broad and high-gain fiber amplifier.

Effect of heat treatment on the structural and optical properties of tellurite glasses doped erbium

Energy Technology Data Exchange (ETDEWEB)

Jlassi, I., E-mail: ifa.jlassi@fst.rnu.tn [Laboratoire de Physico-Chimie des Materiaux Mineraux et leurs Applications, Centre National de Recherches en Sciences des Materiaux, B.P. 95 Hammam-Lif 2050 (Tunisia); Elhouichet, H. [Laboratoire de Physico-Chimie des Materiaux Mineraux et leurs Applications, Centre National de Recherches en Sciences des Materiaux, B.P. 95 Hammam-Lif 2050 (Tunisia); Departement de Physique, Faculte des Sciences de Tunis, Campus ElManar 2092 (Tunisia); Hraiech, S.; Ferid, M. [Laboratoire de Physico-Chimie des Materiaux Mineraux et leurs Applications, Centre National de Recherches en Sciences des Materiaux, B.P. 95 Hammam-Lif 2050 (Tunisia)

2012-03-15

The 75TeO{sub 2}-20ZnO-4Na{sub 2}CO{sub 3}-1Er{sub 2}O{sub 3} (in molar ratio) glass system was prepared by the conventional melt-quenching method. As such, the samples prepared were investigated by differential scanning calorimetry (DSC), X-ray diffractrometry (XRD), Raman spectroscopy and infrared luminescence. DSC analyses were carried out on our glass at different heating rates between 5 and 20 Degree-Sign C/min. The result of the annealing temperature on the spectroscopic properties of Er{sup 3+} in tellurite glasses was discussed. The activation energy, for surface crystallization, was determined graphically from a Kissinger-type plot and had a value about 897.2 kJ/mol. Crystalline phases for both {alpha}-TeO{sub 2}, {gamma}-TeO{sub 2} and Zn{sub 2}Te{sub 3}O{sub 8} system were determined by the XRD method and were confirmed by Raman spectroscopy characterizations after heat treatment. The effect of heat treatment on absorption spectra and luminescence properties in the tellurite glass was also investigated. With heat treatment, the ultraviolet absorption edge presented a redshift. As a result, the Judd-Ofelt (J-O) intensity parameters ({Omega}{sub 2}, {Omega}{sub 4}, {Omega}{sub 6}) were determined. The spontaneous emission probabilities of some relevant transitions, the branching ratio and the radiative lifetimes of several excited states of Er{sup 3+} were predicted using intensity J-O parameters. The near infrared emission that corresponds to Er{sup 3+}: {sup 4}I{sub 13/2}{yields}{sup 4}I{sub 15/2} can be significantly enhanced after heat treatment. Notably, it is found that the luminescence lifetime in the present system is much longer than that in most other glasses and glass ceramics. A comparative study on luminescence performance suggests that the obtained glass ceramic is a promising material for Er{sup 3+} doped fiber amplifiers. - Highlights: Black-Right-Pointing-Pointer Tellurite glasses were prepared by conventional melt-quenching method. Black

Global DNA methylation in earthworms: A candidate biomarker of epigenetic risks related to the presence of metals/metalloids in terrestrial environments

Energy Technology Data Exchange (ETDEWEB)

Maldonado Santoyo, Maria; Rodriguez Flores, Crescencio; Lopez Torres, Adolfo; Wrobel, Kazimierz [Department of Chemistry, University of Guanajuato, L de Retana No 5, 36000 Guanajuato (Mexico); Wrobel, Katarzyna, E-mail: katarzyn@quijote.ugto.mx [Department of Chemistry, University of Guanajuato, L de Retana No 5, 36000 Guanajuato (Mexico)

2011-10-15

In this work, possible relationships between global DNA methylation and metal/metalloid concentrations in earthworms have been explored. Direct correlation was observed between soil and tissue As, Se, Sb, Zn, Cu, Mn, Ag, Co, Hg, Pb (p < 0.05). Speciation results obtained for As and Hg hint at the capability of earthworms for conversion of inorganic element forms present in soil to methylated species. Inverse correlation was observed between the percentage of methylated DNA cytosines and total tissue As, As + Hg, As + Hg + Se + Sb ({beta} = -0.8456, p = 0.071; {beta} = -0.9406, p = 0.017; {beta} = -0.9526, p = 0.012 respectively), as well as inorganic As + Hg ({beta} = -0.8807, p = 0.049). It was concluded that earthworms would be particularly helpful as bioindicators of elements undergoing in vivo methylation and might also be used to assess the related risk of epigenetic changes in DNA methylation. - Graphical abstract: Display Omitted Highlights: > Several metals and metalloids contribute to epigenetic gene regulation. > As, Hg, Se, Sb inversely correlated with global DNA methylation in earthworms. > Biomethylation of the above elements in worms suggested. > Elements biomethylation apparently competes with DNA methylation. > DNA methylation a biomarker of epigenetic risks related to soil metals/metalloids. - Biomethylation of As, Hg in earthworms versus DNA methylation - a candidate biomarker of epigenetic risks related to the presence of metals/metalloids in soil.

Comparison of sample preparation procedures on metal(loid) fractionation patterns in lichens.

Science.gov (United States)

Kroukamp, E M; Godeto, T W; Forbes, P B C

2017-08-13

The effects of different sample preparation strategies and storage on metal(loid) fractionation trends in plant material is largely underresearched. In this study, a bulk sample of lichen Parmotrema austrosinense (Zahlbr.) Hale was analysed for its total extractable metal(loid) content by ICP-MS, and was determined to be adequately homogenous (sample were prepared utilising a range of sample preservation techniques and subjected to a modified sequential extraction procedure or to total metal extraction. Both experiments were repeated after 1-month storage at 4 °C. Cryogenic freezing gave the best reproducibility for total extractable elemental concentrations between months, indicating this to be the most suitable method of sample preparation in such studies. The combined extraction efficiencies were >82% for As, Cu, Mn, Pb, Sr and Zn but poor for other elements, where sample preparation strategies 'no sample preparation' and 'dried in a desiccator' had the best extraction recoveries. Cryogenic freezing procedures had a significantly (p sample cleaning and preservation when species fractionation patterns are of interest. This study also shows that the assumption that species stability can be ensured through cryopreservation and freeze drying techniques needs to be revisited.

Raman, photoluminescence and EPR spectroscopic characterization of europium(III) oxide–lead dioxide–tellurite glassy network

Energy Technology Data Exchange (ETDEWEB)

Dehelean, A. [National Research and Development Institute for Isotopic and Molecular Technologies, Cluj-Napoca (Romania); Rada, S. [Technical University of Cluj-Napoca (Romania); Popa, A.; Suciu, R.C. [National Research and Development Institute for Isotopic and Molecular Technologies, Cluj-Napoca (Romania); Culea, E., E-mail: eugen.culea@phys.utcluj.ro [Technical University of Cluj-Napoca (Romania)

2016-09-15

Raman, photoluminescence and EPR spectroscopies were used to characterize some xEu{sub 2}O{sub 3}·(100−x)[4TeO{sub 2}·PbO{sub 2}] glasses with x=0–50 mol% obtained by melt quenching technique. Raman spectra of these glasses were interpreted in terms of vibration modes of deformed Te–O–Te linkages due to the intercalation of [PbO{sub n}] and [EuO{sub n}] entities produced by addition of Eu{sub 2}O{sub 3} to the host lead–tellurite glass. Photoluminescence spectra of xEu{sub 2}O{sub 3}·(100−x)[4TeO{sub 2}·PbO{sub 2}] glasses reveal the presence of Pb{sup 2+}, Eu{sup 2+} and Eu{sup 3+} ions. EPR data confirm the presence of Eu{sup 2+} ions in the europium–lead–tellurite glassy network and offer information about the compositional evolution of the Eu{sup 2+} ions local environment and Eu{sup 3+}↔Eu{sup 2+} redox process. PL and EPR data show that the decrease of the Eu{sup 2+} ions luminescence intensity for the x≥40 mol% Eu{sub 2}O{sub 3} region is not due to the clusterization of europium ions but is due the decrease of the amount of Eu{sup 2+} ions as result of changes in the Eu{sup 3+}→Eu{sup 2+} redox equilibrium.

Protein-protein association and cellular localization of four essential gene products encoded by tellurite resistance-conferring cluster "ter" from pathogenic Escherichia coli.

Science.gov (United States)

Valkovicova, Lenka; Vavrova, Silvia Minarikova; Mravec, Jozef; Grones, Jozef; Turna, Jan

2013-12-01

Gene cluster "ter" conferring high tellurite resistance has been identified in various pathogenic bacteria including Escherichia coli O157:H7. However, the precise mechanism as well as the molecular function of the respective gene products is unclear. Here we describe protein-protein association and localization analyses of four essential Ter proteins encoded by minimal resistance-conferring fragment (terBCDE) by means of recombinant expression. By using a two-plasmid complementation system we show that the overproduced single Ter proteins are not able to mediate tellurite resistance, but all Ter members play an irreplaceable role within the cluster. We identified several types of homotypic and heterotypic protein-protein associations among the Ter proteins by in vitro and in vivo pull-down assays and determined their cellular localization by cytosol/membrane fractionation. Our results strongly suggest that Ter proteins function involves their mutual association, which probably happens at the interface of the inner plasma membrane and the cytosol.

Distribution of metal and metalloid elements in human scalp hair in Taiyuan, China.

Science.gov (United States)

Zhu, Yuen; Wang, Yuzhe; Meng, Fanjian; Li, Lifen; Wu, Shan; Mei, Xiaohui; Li, Hua; Zhang, Guixiang; Wu, Daishe

2018-02-01

This study investigated the levels of metal and metalloid elements (As, Ca, Cd, Cr, Cu, Fe, Hg, Mg, Ni, Pb, and Zn) in scalp hair samples collected from 161 people of different age and gender groups living in the six districts of Taiyuan, an industrial city with rich coal reserve in Shanxi province in China. Levels of most elements in the hair were high in the 26-40 age groups and increased with the length of residence. Calcium, Cr, Mg, Ni and Zn levels in the females' hair were significantly higher than those in the males' (p industrial and non-industrial districts because most of industry factories are in the upper wind position in Taiyuan, and contamination is prone to spread to non-industrial districts. The principal component analysis indicates that the main sources of these elements are mining activities, the neighboring stainless steel industry, and coal combustion. These results indicate that the industrial activities primarily contribute to the metal and metalloid pollution in Taiyuan, whereas numerous factors caused the metals accumulation in hair. Copyright © 2017 Elsevier Inc. All rights reserved.

Tm3+/Yb3+ co-doped tellurite glass with silver nanoparticles for 1.85 μm band laser material

Science.gov (United States)

Huang, Bo; Zhou, Yaxun; Cheng, Pan; Zhou, Zizhong; Li, Jun; Jin, Wei

2016-10-01

Tm3+/Yb3+ co-doped tellurite glasses with different silver nanoparticles (Ag NPs) concentrations were prepared using the conventional melt-quenching technique and characterized by the UV/Vis/NIR absorption spectra, 1.85 μm band fluorescence emission spectra, transmission electron microscopy (TEM) images, differential scanning calorimeter (DSC) curves and X-ray diffraction (XRD) patterns to investigate the effects of Ag NPs on the 1.85 μm band spectroscopic properties of Tm3+ ions, thermal stability and structural nature of glass hosts. Under the excitation of 980 nm laser diode (LD), the 1.85 μm band fluorescence emission of Tm3+ ions enhances significantly in the presence of Ag NPs with average diameter of ∼8 nm and local surface Plasmon resonance (LSPR) band of ∼590 nm, which is mainly attributed to the increased local electric field induced by Ag NPs at the proximity of doped rare-earth ions on the basis of energy transfer from Yb3+ to Tm3+ ions. An improvement by about 110% of fluorescence intensity is observed in the Tm3+/Yb3+ co-doped tellurite glass containing 0.5 mol% amount of AgNO3 while the prepared glass samples possess good thermal stability and amorphous structural nature. Meanwhile, the Judd-Ofelt intensity parameters Ωt (t = 2,4,6), spontaneous radiative transition probabilities, fluorescence branching ratios and radiative lifetimes of relevant excited levels of Tm3+ ions were determined based on the Judd-Ofelt theory to reveal the enhanced effects of Ag NPs on the 1.85 μm band spectroscopic properties, and the energy transfer micro-parameters and phonon contribution ratios were calculated based on the non-resonant energy transfer theory to elucidate the energy transfer mechanism between Yb3+ and Tm3+ ions. The present results indicate that the prepared Tm3+/Yb3+ co-doped tellurite glass with an appropriate amount of Ag NPs is a promising lasing media applied for 1.85 μm band solid-state lasers and amplifiers.

Ternary alkali-metal and transition metal or metalloid acetylides as alkali-metal intercalation electrodes for batteries

Science.gov (United States)

Nemeth, Karoly; Srajer, George; Harkay, Katherine C; Terdik, Joseph Z

2015-02-10

Novel intercalation electrode materials including ternary acetylides of chemical formula: A.sub.nMC.sub.2 where A is alkali or alkaline-earth element; M is transition metal or metalloid element; C.sub.2 is reference to the acetylide ion; n is an integer that is 0, 1, 2, 3 or 4 when A is alkali element and 0, 1, or 2 when A is alkaline-earth element. The alkali elements are Lithium (Li), Sodium (Na), Potassium (K), Rubidium (Rb), Cesium (Cs) and Francium (Fr). The alkaline-earth elements are Berilium (Be), Magnesium (Mg), Calcium (Ca), Strontium (Sr), Barium (Ba), and Radium (Ra). M is a transition metal that is any element in groups 3 through 12 inclusive on the Periodic Table of Elements (elements 21 (Sc) to element 30 (Zn)). In another exemplary embodiment, M is a metalloid element.

Selenite reduction by the obligate aerobic bacterium Comamonas testosteroni S44 isolated from a metal-contaminated soil

DEFF Research Database (Denmark)

Zheng, Shixue; Su, Jing; Wang, Liang

2014-01-01

impacted cellular growth and subsequent resistance to multiple heavy metal(loid)s. Conclusions: C. testosteroni S44 could be very useful for bioremediation in heavy metal(loid) polluted soils due to the ability to both reduce toxic Se(VI) and Se(IV) to non-toxic Se (0) under aerobic conditions...

Simple one-pot aqueous synthesis of CdHgTe nanocrystals using sodium tellurite as the Te source

International Nuclear Information System (INIS)

Shen, Zhitao; Luo, Chunhua; Huang, Rong; Wang, Yiting; Peng, Hui; Travas-sejdic, Jadranka

2014-01-01

In this work, we systematically investigated the one-pot aqueous synthesis conditions of CdHgTe nanocrystals (NCs) using sodium tellurite (Na 2 TeO 3 ) as the Te source, and found that the added content of Hg 2+ and the initial pH value of reaction solutions significantly affected the photoluminescence quantum yield (PL QY) of alloyed CdHgTe NCs. When the concentration of Cd was 1.0 mmol L −1 , the mole ratio of Cd/Te/Hg/MPA was 1:0.5:0.05:2.4, and the initial pH value of the reaction solution was about 8.78, the PL QY of as-prepared CdHgTe NCs was up to 45%. Characterization by HRTEM and XRD confirmed the crystalline nature of CdHgTe NCs. Compared to other synthetic approaches of CdHgTe NCs, our experimental results indicate that Na 2 TeO 3 could be an attractive alternative Te source to directly synthesize CdHgTe NCs in aqueous media. - Highlights: • A one-pot method was developed for the synthesis of highly luminescent CdHgTe nanocrystals (NCs). • Sodium tellurite was used as the Te source. • The quantum yield reached up to 45%. • The experimental conditions were optimized and the prepared CdHgTe NCs were characterized

Evaluation of shielding parameters for heavy metal fluoride based tellurite-rich glasses for gamma ray shielding applications

International Nuclear Information System (INIS)

Sayyed, M.I.; Lakshminarayana, G.; Kityk, I.V.; Mahdi, M.A.

2017-01-01

In this work, we have evaluated the γ-ray shielding parameters such as mass attenuation coefficient (μ/ρ), effective atomic number (Z eff ), half value layer (HVL), mean free path (MFP) and exposure buildup factors (EBF) for heavy metal fluoride (PbF 2 ) based tellurite-rich glasses. In addition, neutron total macroscopic cross sections (∑ R ) for these glasses were also calculated. The maximum value for µ/ρ, Z eff and ∑ R was found for heavy metal (Bi 2 O 3 ) oxide introduced glass. The results of the selected glasses have been compared, in terms of MFP with different glass systems. The shielding effectiveness of the selected glasses is found comparable or better than of common ones, which indicates that these glasses with suitable oxides could be developed for gamma ray shielding applications. - Highlights: • μ/ρ, Z eff , HVL and MFP for PbF 2 based tellurite-rich glasses have been calculated. • µ/ρ and Z eff depend on the photon energy and chemical composition of the glasses. • EBF values of these glasses have been calculated using G-P fitting method. • The maximum value for µ/ρ and Z eff was found for Bi 2 O 3 oxide introduced glass. • New types of non-traditional radiation shielding glasses are demonstrated.

Trace Metals and Metalloids in Forest Soils and Exotic Earthworms in Northern New England, USA

Science.gov (United States)

Richardson, J.B.; Görres, J.H.; Jackson, B.P.; Friedland, A.J.

2015-01-01

Trace metals and metalloids (TMM) in forest soils and invasive earthworms were studied at 9 uncontaminated sites in northern New England, USA. Essential (Cu, Mo, Ni, Zn, Se) and toxic (As, Cd, Pb, Hg and U) TMM concentrations (mg kg-1) and pools (mg m-2) were quantified for organic horizons (forest floor), mineral soils and earthworm tissues. Essential TMM tissue concentrations were greatest for mineral soil-feeding earthworm Octolasion cyaneum. Toxic TMM tissue concentrations were highest for organic horizon-feeding earthworms Dendobaena octaedra, Aporrectodea rosea and Amynthas agrestis. Most earthworm species had attained tissue concentrations of Pb, Hg and Se potentially hazardous to predators. Bioaccumulation factors were Cd > Se > Hg > Zn > Pb > U > 1.0 > Cu > As > Mo > Ni. Only Cd, Se Hg and Zn were considered strongly bioaccumulated by earthworms because their average bioaccumulation factors were significantly greater than 1.0. Differences in bioaccumulation did not appear to be caused by soil concentrations as earthworm TMM tissue concentrations were poorly correlated with TMM soil concentrations. Instead, TMM bioaccumulation appears to be species and site dependent. The invasive Amynthas agrestis had the greatest tissue TMM pools, due to its large body mass and high abundance at our stands. We observed that TMM tissue pools in earthworms were comparable or exceeded organic horizon TMM pools; earthworm tissue pools of Cd were up 12 times greater than in the organic horizon. Thus, exotic earthworms may represent an unaccounted portion and flux of TMM in forests of the northeastern US. Our results highlight the importance of earthworms in TMM cycling in northern forests and warrant more research into their impact across the region. PMID:25883392

Nanoparticle interactions with co-existing contaminants: joint toxicity, bioaccumulation and risk.

Science.gov (United States)

Deng, Rui; Lin, Daohui; Zhu, Lizhong; Majumdar, Sanghamitra; White, Jason C; Gardea-Torresdey, Jorge L; Xing, Baoshan

2017-06-01

With their growing production and application, engineered nanoparticles (NPs) are increasingly discharged into the environment. The released NPs can potentially interact with pre-existing contaminants, leading to biological effects (bioaccumulation and/or toxicity) that are poorly understood. Most studies on NPs focus on single analyte exposure; the existing literature on joint toxicity of NPs and co-existing contaminants is rather limited but beginning to develop rapidly. This is the first review paper evaluating the current state of knowledge regarding the joint effects of NPs and co-contaminants. Here, we review: (1) methods for investigating and evaluating joint effects of NPs and co-contaminants; (2) simultaneous toxicities from NPs co-exposed with organic contaminants, metal/metalloid ions, dissolved organic matter (DOM), inorganic ligands and additional NPs; and (3) the influence of NPs co-exposure on the bioaccumulation of organic contaminants and heavy metal ions, as well as the influence of contaminants on NPs bioaccumulation. In addition, future research needs are discussed so as to better understand risk associated with NPs-contaminant co-exposure.

Cuz1/Ynl155w, a Zinc-dependent Ubiquitin-binding Protein, Protects Cells from Metalloid-induced Proteotoxicity*

Science.gov (United States)

Hanna, John; Waterman, David; Isasa, Marta; Elsasser, Suzanne; Shi, Yuan; Gygi, Steven; Finley, Daniel

2014-01-01

Protein misfolding is a universal threat to cells. The ubiquitin-proteasome system mediates a cellular stress response capable of eliminating misfolded proteins. Here we identify Cuz1/Ynl155w as a component of the ubiquitin system, capable of interacting with both the proteasome and Cdc48. Cuz1/Ynl155w is regulated by the transcription factor Rpn4, and is required for cells to survive exposure to the trivalent metalloids arsenic and antimony. A related protein, Yor052c, shows similar phenotypes, suggesting a multicomponent stress response pathway. Cuz1/Ynl155w functions as a zinc-dependent ubiquitin-binding protein. Thus, Cuz1/Ynl155w is proposed to protect cells from metalloid-induced proteotoxicity by delivering ubiquitinated substrates to Cdc48 and the proteasome for destruction. PMID:24297164

Comparisons of plutonium, thorium, and cerium tellurite sulfates.

Science.gov (United States)

Lin, Jian; Cross, Justin N; Diwu, Juan; Meredith, Nathan A; Albrecht-Schmitt, Thomas E

2013-04-15

The hydrothermal reaction of PuCl3 or CeCl3 with TeO2 in the presence of sulfuric acid under the comparable conditions results in the crystallization of Pu(TeO3)(SO4) or Ce2(Te2O5)(SO4)2, respectively. Pu(TeO3)(SO4) and its isotypic compound Th(TeO3)(SO4) are characterized by a neutral layer structure with no interlamellar charge-balancing ions. However, Ce2(Te2O5)(SO4)2 possesses a completely different dense three-dimensional framework. Bond valence calculation and UV-vis-NIR spectra indicate that the Ce compound is trivalent whereas the Pu and Th compounds are tetravalent leading to the formation of significantly different compounds. Pu(TeO3)(SO4), Th(TeO3)(SO4), and Ce2(Te2O5)(SO4)2 represent the first plutonium/thorium/cerium tellurite sulfate compounds. Our study strongly suggests that the chemistries of Pu and Ce are not the same, and this is another example of the failure of Ce as a surrogate.

Genomic Variability of O Islands Encoding Tellurite Resistance in Enterohemorrhagic Escherichia coli O157:H7 Isolates

OpenAIRE

Taylor, Diane E.; Rooker, Michelle; Keelan, Monika; Ng, Lai-King; Martin, Irene; Perna, Nicole T.; Burland, N. T. Valerie; Blattner, Fredrick R.

2002-01-01

Strains of Escherichia coli causing enterohemorrhagic colitis belonging to the O157:H7 lineage are reported to be highly related. Fifteen strains of E. coli O157:H7 and 1 strain of E. coli O46:H− (nonflagellated) were examined for the presence of potassium tellurite resistance (Ter). Ter genes comprising terABCDEF were shown previously to be part of a pathogenicity island also containing integrase, phage, and urease genes. PCR analysis, both conventional and light cycler based, demonstrated t...

Resolving colocalization of bacteria and metal(loid)s on plant root surfaces by combining fluorescence in situ hybridization (FISH) with multiple-energy micro-focused X-ray fluorescence (ME μXRF).

Science.gov (United States)

Honeker, Linnea K; Root, Robert A; Chorover, Jon; Maier, Raina M

2016-12-01

Metal(loid)-contamination of the environment due to anthropogenic activities is a global problem. Understanding the fate of contaminants requires elucidation of biotic and abiotic factors that influence metal(loid) speciation from molecular to field scales. Improved methods are needed to assess micro-scale processes, such as those occurring at biogeochemical interfaces between plant tissues, microbial cells, and metal(loid)s. Here we present an advanced method that combines fluorescence in situ hybridization (FISH) with synchrotron-based multiple-energy micro-focused X-ray fluorescence microprobe imaging (ME μXRF) to examine colocalization of bacteria and metal(loid)s on root surfaces of plants used to phytostabilize metalliferous mine tailings. Bacteria were visualized on a small root section using SytoBC nucleic acid stain and FISH probes targeting the domain Bacteria and a specific group (Alphaproteobacteria, Gammaproteobacteria, or Actinobacteria). The same root region was then analyzed for elemental distribution and metal(loid) speciation of As and Fe using ME μXRF. The FISH and ME μXRF images were aligned using ImageJ software to correlate microbiological and geochemical results. Results from quantitative analysis of colocalization show a significantly higher fraction of As colocalized with Fe-oxide plaques on the root surfaces (fraction of overlap 0.49±0.19) than to bacteria (0.072±0.052) (proots, metal(loid)s and microbes, information that should lead to improved mechanistic models of metal(loid) speciation and fate. Copyright © 2016 Elsevier B.V. All rights reserved.

Eigenstates and radiative transition probabilities for Tm3+(4f12) in phosphate and tellurite glasses

International Nuclear Information System (INIS)

Spector, N.; Reisfeld, R.; Boehm, L.

1977-01-01

Electronic wavefunctions of Tm 3+ in intermediate coupling were obtained and used to calculate the Usup((lambda)) matrix elements between all possible states of the 4f 12 configuration. The Judd-Ofelt intensity parameters Ωsub(lambda) obtained for Tm 3+ in phosphate and tellurite glasses were used in conjunction with the Usup((lambda))'s to calculate the forced electric dipole line strengths. The total electric and magnetic radiative transition probabilities are calculated. The entire theoretical spectrum involving the ground and excited levels (from 129 nm to 16447 nm) is given. (Auth.)

A novel approach for rapidly and cost-effectively assessing toxicity of toxic metals in acidic water using an acidophilic iron-oxidizing biosensor.

Science.gov (United States)

Yang, Shih-Hung; Cheng, Kuo-Chih; Liao, Vivian Hsiu-Chuan

2017-11-01

Contamination by heavy metals and metalloids is a serious environmental and health concern. Acidic wastewaters are often associated with toxic metals which may enter and spread into agricultural soils. Several biological assays have been developed to detect toxic metals; however, most of them can only detect toxic metals in a neutral pH, not in an acidic environment. In this study, an acidophilic iron-oxidizing bacterium (IOB) Strain Y10 was isolated, characterized, and used to detect toxic metals toxicity in acidic water at pH 2.5. The colorimetric acidophilic IOB biosensor was based on the inhibition of the iron oxidizing ability of Strain Y10, an acidophilic iron-oxidizing bacterium, by metals toxicity. Our results showed that Strain Y10 is acidophilic iron-oxidizing bacterium. Thiobacillus caldus medium (TCM) (pH 2.5) supplied with both S 4 O 6 2- and glucose was the optimum growth medium for Strain Y10. The optimum temperature and pH for the growth of Strain Y10 was 45 °C and pH 2.5, respectively. Our study demonstrates that the color-based acidophilic IOB biosensor can be semi-quantitatively observed by eye or quantitatively measured by spectrometer to detect toxicity from multiple toxic metals at pH 2.5 within 45 min. Our study shows that monitoring toxic metals in acidic water is possible by using the acidophilic IOB biosensor. Our study thus provides a novel approach for rapid and cost-effective detection of toxic metals in acidic conditions that can otherwise compromise current methods of chemical analysis. This method also allows for increased efficiency when screening large numbers of environmental samples. Copyright © 2017 Elsevier Ltd. All rights reserved.

[Source identification and potential ecological hazards assessment of trace metalloid/heavy metals in the soil of Tianshan Mountains, Xinjiang, China].

Science.gov (United States)

Zhang, Zhao-Yong; Jilili, Abuduwailil; Jiang, Feng-Qing

2014-11-01

In this study, the contents of ten metalloid/heavy metals (As, Pb, Ni, Cd, Co, Hg, Cu, Mn, Zn and Cr) in soil samples collected from three sections including the central Urumqi-Akesu, eastern Blikun-Yiwu and western Zhaosu-Tekesi in Tianshan Mountains were determined, and their sources were identified by using typical statistical and multivariate statistical methods. The potential ecological risks of these heavy metals were assessed by employing pollution index method, potential ecological risk index and the background values of Tianshan Mountains, and Xinjiang, and also the Second National Standard of the Soil Qualities of China. The results showed that the contents of the heavy metals (Pb, Ni, Cd, Co, Hg, Cu, Mn Zn and Cr) and metalloid As were all higher than the soil background values of the Tianshan Mountain or Xinjiang, and their variation co- efficients belonged to the medium variation. In general, the contents of the ten metalloid/heavy metals in the soil of Tianshan Mountains were low. Principal component analysis showed that the ten metalloid/heavy metals could be identified as two principal components, among which PC1 (Cd, Pb, Hg, Mn and Zn) could be seen as 'human influence sources factor', PC2 (Cu, Ni, Cr, Co and As) as 'natural sources factor'. Mn and As had larger loads both in PC1 and PC2, and they could be co-influenced by human and natural sources. The pollution assessment showed that Hg and Cd in central Urumuqi-Akesu section and As in western Zhaosu-Tekesi section were all at alert level, while the other heavy metals in other sections were all at security level. From the comprehensive pollution indices (P(z)) of heavy metals, it was found that the ten metalloid/heavy metals in the soils of central Urumqi-Akesu section were at low pollution level, but those in the other two sections were at clean level. The potential ecological risk assessment showed that the potential ecological risk coefficient (E(i)r) and the ecological damage index (RI) of Hg

Heavy metals and metalloids in the surface sediments of the Xiangjiang River, Hunan, China: distribution, contamination, and ecological risk assessment.

Science.gov (United States)

Chai, Liyuan; Li, Huan; Yang, Zhihui; Min, Xiaobo; Liao, Qi; Liu, Yi; Men, Shuhui; Yan, Yanan; Xu, Jixin

2017-01-01

Here, we aim to determine the distribution, ecological risk and sources of heavy metals and metalloids in the surface sediments of the Xiangjiang River, Hunan Province, China. Sixty-four surface sediment samples were collected in 16 sites of the Xiangjiang River, and the concentrations of ten heavy metals and metalloids (Mn, Zn, Cr, V, Pb, Cu, As, Ni, Co, and Cd) in the sediment samples were investigated using an inductively coupled plasma mass spectrometer (ICP-MS) and an atomic fluorescence spectrophotometer (AFS), respectively. The results showed that the mean concentrations of the ten heavy metals and metalloids in the sediment samples followed the order Mn > Zn > Cr > V > Pb > Cu > As ≈ Ni >Co > Cd. The geoaccumulation index (I geo ), enrichment factor (EF), modified degree of contamination (mC d ), and potential ecological risk index (RI) revealed that Cd, followed by Pb, Zn, and Cu, caused severely contaminated and posed very highly potential ecological risk in the Xiangjiang River, especially in Shuikoushan of Hengyang, Xiawan of Zhuzhou, and Yijiawan of Xiangtan. The Pearson's correlation coefficient (PCC) analysis, principal component analysis (PCA), and hierarchical cluster analysis (HCA) indicated that the ten heavy metals and metalloids in the sampling sediments of the Xiangjiang River were classified into three groups: (1) Cd, Pb, Zn, and Cu which possibly originated from Shuikoushan, Xiawan, and Yijiawan clustering Pb-Zn mining and smelting industries; (2) Co, V, Ni, Cr, and Al from natural resources; and (3) Mn and As. Therefore, our results suggest that anthropogenic activities, especially mining and smelting, have caused severe contamination of Cd, Pb, Zn, and Cu and posed very high potential ecological risk in the Xiangjiang River.

Variation and distribution of metals and metalloids in soil/ash mixtures from Agbogbloshie e-waste recycling site in Accra, Ghana.

Science.gov (United States)

Itai, Takaaki; Otsuka, Masanari; Asante, Kwadwo Ansong; Muto, Mamoru; Opoku-Ankomah, Yaw; Ansa-Asare, Osmund Duodu; Tanabe, Shinsuke

2014-02-01

Illegal import and improper recycling of electronic waste (e-waste) are an environmental issue in developing countries around the world. African countries are no exception to this problem and the Agbogbloshie market in Accra, Ghana is a well-known e-waste recycling site. We have studied the levels of metal(loid)s in the mixtures of residual ash, formed by the burning of e-waste, and the cover soil, obtained using a portable X-ray fluorescence spectrometer (P-XRF) coupled with determination of the 1M HCl-extractable fraction by an inductively coupled plasma mass spectrometer. The accuracy and precision of the P-XRF measurements were evaluated by measuring 18 standard reference materials; this indicated the acceptable but limited quality of this method as a screening tool. The HCl-extractable levels of Al, Co, Cu, Zn, Cd, In, Sb, Ba, and Pb in 10 soil/ash mixtures varied by more than one order of magnitude. The levels of these metal(loid)s were found to be correlated with the color (i.e., soil/ash ratio), suggesting that they are being released from disposed e-waste via open burning. The source of rare elements could be constrained using correlation to the predominant metals. Human hazard quotient values based on ingestion of soil/ash mixtures exceeded unity for Pb, As, Sb, and Cu in a high-exposure scenario. This study showed that along with common metals, rare metal(loid)s are also enriched in the e-waste burning site. We suggest that risk assessment considering exposure to multiple metal(loid)s should be addressed in studies of e-waste recycling sites. © 2013. Published by Elsevier B.V. All rights reserved.

Behaviour of metalloids and metals from highly polluted soil samples when mobilized by water – Evaluation of static versus dynamic leaching

International Nuclear Information System (INIS)

Wennrich, Rainer; Daus, Birgit; Müller, Karsten; Stärk, Hans-Joachim; Brüggemann, Lutz; Morgenstern, Peter

2012-01-01

The mobilization behaviour of metalloids and metals when leached by water from highly polluted soil/sediment samples was studied using static and dynamic approaches employing batch methodology and rotating coiled columns (RCC), respectively. Increasing the solution-to-solid ratios during batch leaching resulted in different enhanced mobilization rates, which are element-specific and matrix-specific. When dynamic leaching is employed with continuous replacement of the eluent, a higher portion is mobilized than when using batch elution with an identical solid-to-water ratio. Using RCC the time-resolved leaching of the elements was monitored to demonstrate the leaching patterns. For the majority of elements a significant decrease could be shown in the mobilized portion of the elements with ongoing leaching process. The data were discussed targeted at solid liquid partitioning coefficients of the metal(loid)s. The capabilities in application of K d values was demonstrated for dynamic leaching which is relevant for environmental processes. - Highlights: ► We examine the mobilization of metal(loid)s by water under simulated conditions. ► Static versus dynamic leaching (RCC) with continuous supply of extractant was compared. ► RCC is favourable for detailed time-resolved investigations of the leaching behaviour. ► The influence of matrices on the leaching behaviour was investigated. ► The capabilities of the K d values in environmentally relevant processes is shown. - Dynamic leaching with continuous supply of water has proved as tool for long-term and time-resolved mobility of metal(loid)s in contaminated soils.

Coping With Metal Toxicity – Cues From Halophytes

Directory of Open Access Journals (Sweden)

Ganesh C. Nikalje

2018-06-01

Full Text Available Being the native flora of saline soil, halophytes are well studied for their salt tolerance and adaptation mechanism at the physiological, biochemical, molecular and metabolomic levels. However, these saline habitats are getting contaminated due to various anthropogenic activities like urban waste, agricultural runoff, mining, industrial waste that are rich in toxic metals and metalloids. These toxic metals impose detrimental effects on growth and development of most plant species. Halophytes by virtue of their tolerance to salinity also show high tolerance to heavy metals which is attributed to the enhanced root to shoot metal translocation and bioavailability. Halophytes rapidly uptake toxic ions from the root and transport them toward aerial parts by using different transporters which are involved in metal tolerance and homeostasis. A number of defense related physiological and biochemical strategies are known to be crucial for metal detoxification in halophytes however; there is paucity of information on the molecular regulators. Understanding of the phenomenon of cross-tolerance of salinity with other abiotic stresses in halophytes could very well boost their potential use in phytoremediation. In this article, we present an overview of heavy metal tolerance in case of halophytes, associated mechanisms and cross-tolerance of salinity with other abiotic stresses.

Annealing time dependent up-conversion luminescence enhancement in magnesium–tellurite glass

Energy Technology Data Exchange (ETDEWEB)

Amjad, Raja J., E-mail: rajajunaid25@gmail.com [Advanced Optical Material Research Group, Faculty of Science, Universiti Teknologi Malaysia, Skudai, Johor bahru 81310 (Malaysia); Centre for Solid State Physics, University of the Punjab, QAC, Lahore 54590 (Pakistan); Sahar, M.R.; Ghoshal, S.K.; Dousti, M.R. [Advanced Optical Material Research Group, Faculty of Science, Universiti Teknologi Malaysia, Skudai, Johor bahru 81310 (Malaysia); Riaz, S. [Centre for Solid State Physics, University of the Punjab, QAC, Lahore 54590 (Pakistan); Samavati, A.R.; Arifin, R. [Advanced Optical Material Research Group, Faculty of Science, Universiti Teknologi Malaysia, Skudai, Johor bahru 81310 (Malaysia); Naseem, S. [Centre for Solid State Physics, University of the Punjab, QAC, Lahore 54590 (Pakistan)

2013-04-15

Silver nanoparticles (NPs) embedded Er{sup 3+} ions doped magnesium–tellurite glasses are prepared using melt quenching technique. Heat treatment with different time intervals above the glass transition temperature is applied in order to reduce the silver ions (Ag{sup +}) to silver NPs (Ag{sup o}). The transmission electron microscopy (TEM), differential thermal analyses (DTA), UV–vis-NIR absorption spectroscopy and photoluminescence (PL) spectroscopy are used to examine annealing time dependent structural and optical properties. The characteristics temperatures such as glass transition temperature (T{sub g}), crystallization temperature (T{sub c}) and melting temperature (T{sub m}) obtained from DTA for an as prepared sample are 322 °C, 450 °C and 580 °C, respectively. TEM image clearly shows the homogeneous distribution of silver NPs with an average diameter ∼12 nm. The observed localized surface plasmon resonance (LSPR) band is evidenced at 534 nm. Furthermore, the infrared to visible frequency up-conversion (UC) emission under 786 nm excitation exhibits three emission bands centered at 532 nm, 554 nm and 634 nm corresponding to {sup 2}H{sub 11/2}→{sup 4}I{sub 15/2}, {sup 4}S{sub 3/2}→{sup 4}I{sub 15/2} and {sup 4}F{sub 9/2}→{sup 4}I{sub 15/2} transitions of Er{sup 3+}, respectively. Intensity of all the bands is found to enhance by increasing the annealing time up to 24 h. However, further increase in the annealing time duration (∼40 h) reduces the intensity. Enhancement in the luminescence intensity is understood in terms of the local field effect of the silver NPs whereas the quenching is attributed to the energy transfer from Er{sup 3+} ions to silver NPs. -- Highlights: ► Er{sup 3+}-doped silver NPs embedded magnesium–tellurite glasses are prepared. ► TEM confirms the successful precipitation of spherical NPs by heat treatment (HT). ► Luminescence is enhanced due to the growth of NPs after HT up to 24 h. ► With HT>24 h (40 h

Ecological Risk of Heavy Metals and a Metalloid in Agricultural Soils in Tarkwa, Ghana

Science.gov (United States)

Bortey-Sam, Nesta; Nakayama, Shouta M. M.; Akoto, Osei; Ikenaka, Yoshinori; Baidoo, Elvis; Mizukawa, Hazuki; Ishizuka, Mayumi

2015-01-01

Heavy metals and a metalloid in agricultural soils in 19 communities in Tarkwa were analyzed to assess the potential ecological risk. A total of 147 soil samples were collected in June, 2012 and analyzed for As, Cd, Co, Cr, Cu, Hg, Ni, Pb and Zn. Mean concentrations (mg/kg dw) of heavy metals in the communities decreased in order of Zn (39) ˃ Cr (21) ˃ Pb (7.2) ˃ Cu (6.2) ˃ As (4.4) ˃ Ni (3.7) ˃ Co (1.8) ˃ Hg (0.32) ˃ Cd (0.050). Correlations among heavy metals and soil properties indicated that soil organic matter could have substantial influence on the total contents of these metals in soil. From the results, integrated pollution (Cdeg) in some communities such as, Wangarakrom (11), Badukrom (13) and T–Tamso (17) indicated high pollution with toxic metals, especially from As and Hg. Potential ecological risk (RI) indices indicated low (Mile 7) to high risks (Wangarakrom; Badukrom) of metals. Based on pollution coefficient (Cif), Cdeg, monomial ecological risk (Eir) and RI, the investigated soils fall within low to high contamination and risk of heavy metals to the ecological system especially plants, soil invertebrates and/or mammalian wildlife. This represented moderate potential ecological risk in the study area, and mining activities have played a significant role. PMID:26378563

Investigations on luminescence behavior of Er3+/Yb3+ co-doped boro-tellurite glasses

Science.gov (United States)

Maheshvaran, K.; Arunkumar, S.; Venkata Krishnaiah, K.; Marimuthu, K.

2015-01-01

Er3+/Yb3+ co-doped boro-tellurite glasses with the chemical composition 30TeO2+(24 - x)B2O3 + 15SrO + 10BaO + 10Li2O + 10LiF + 1Er2O3 + xYb2O3 (where x = 0, 0.1, 0.5, 1 and 2 in wt%) have been prepared and their luminescence behavior were studied and reported. Absorption spectral measurements have been used to derive the Judd-Ofelt (JO) intensity parameters from the experimental and calculated oscillator strength values following the JO theory. The various lasing parameters such as stimulated emission cross-section (σEp), experimental and calculated branching ratios (βR) and radiative lifetime (τcal) for the 2H9/2 → 4I15/2, 4S3/2 → 4I15/2 and 4I13/2 → 4I15/2 emission transitions were determined using the JO intensity parameters. The absorption and emission cross-section values for the 4I13/2 → 4I15/2 emission band have been calculated using McCumbar theory and the Gain cross-section for the 4I13/2 → 4I15/2 emission transition also obtained. The upconversion emission mechanism have been studied through various energy transfer processes and the intensity of the upconversion emission transitions are found to increase with the increase in Yb3+ ion concentration. The luminescence decay curves corresponding to the 4I13/2 → 4I15/2 transition of the Er3+/Yb3+ co-doped boro-tellurite glasses under 980 nm excitation wavelength have also been studied and reported in the present work.

Structural, thermal and optical absorption features of heavy metal oxides doped tellurite rich glasses

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Kawa M. Kaky

Full Text Available In order to improve tellurite glass stability to be applicable for optical fiber amplifier applications, glasses with the composition of (70 − xTeO2. (10ZnO. (10WO3. (5Na2O. (5TiO2. (xBi2O3 (x = 1, 2, 3, 4, and 5 mol% have been produced and characterized using the related methods. Structural properties were investigated using X-ray diffraction (XRD which confirms the non-crystalline structure and scanning electron microscopy (SEM micrographs also confirm the XRD results. The energy dispersive X-ray (EDX analysis profiles show that all the mentioned elements are present in the prepared glasses. Following the IR spectra, all the tellurium bonds such as stretching vibrations of TeO4 tbp and TeO3/TeO3+1 unit are revealed. Raman spectra confirm the presence of different functional groups, actually, it shows bands mainly in four spectral regions: R1 (65–150 cm−1, R2 (280–550 cm−1, R3 (880–950 cm−1 and R4 (916–926 cm−1 and the identified bands are assigned to respective molecular groups. The thermal study was carried out using Differential scanning calorimetry (DSC which indicates good thermal stability of the synthesized glasses with increasing Bi concentration. From the optical absorption spectra, we evaluated cut-off edge wavelengths and found increasing cutoff wavelength with an increase in Bi2O3 concentration. In the UV–Visible region, optical band gap energy and allowed transitions were investigated using three methods; direct, indirect, and absorption spectrum fitting (ASF, and band gaps from indirect and ASF were matched. Keywords: Tellurite glasses, XRD, FT-IR, Raman, TGA/DSC

Effect of AlF3 on the Density and Elastic Properties of Zinc Tellurite Glass Systems

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Sidek, Haji Abdul Aziz; Rosmawati, Shaharuddin; Halimah, Mohamed Kamari; Matori, Khamirul Amin; Talib, Zainal Abidin

2012-01-01

This paper presents the results of the physical and elastic properties of the ternary zinc oxyfluoro tellurite glass system. Systematic series of glasses (AlF3)x(ZnO)y(TeO2)z with x = 0–19, y = 0–20 and z = 80, 85, 90 mol% were synthesized by the conventional rapid melt quenching technique. The composition dependence of the physical, mainly density and molar volume, and elastic properties is discussed in term of the AlF3 modifiers addition that are expected to produce quite substantial changes in their physical properties. The absence of any crystalline peaks in the X-ray diffraction (XRD) patterns of the present glass samples indicates the amorphous nature. The addition of AlF3 lowered the values of the densities in ternary oxyfluorotellurite glass systems. The longitudinal and transverse ultrasonic waves propagated in each glass sample were measured using a MBS8020 ultrasonic data acquisition system. All the velocity data were taken at 5 MHz frequency and room temperature. The longitudinal modulus (L), shear modulus (G), Young’s modulus (E), bulk modulus (K) and Poisson’s ratio (σ) are obtained from both velocities data and their respective density. Experimental data shows the density and elastic moduli of each AlF3-ZnO-TeO2 series are found strongly depend upon the glass composition. The addition of AlF3 modifiers into the zinc tellurite causes substantial changes in their density, molar volume as well as their elastic properties.

Comparison Study on the Estimation of the Spatial Distribution of Regional Soil Metal(loids Pollution Based on Kriging Interpolation and BP Neural Network

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Zhenyi Jia

2017-12-01

Full Text Available Soil pollution by metal(loids resulting from rapid economic development is a major concern. Accurately estimating the spatial distribution of soil metal(loid pollution has great significance in preventing and controlling soil pollution. In this study, 126 topsoil samples were collected in Kunshan City and the geo-accumulation index was selected as a pollution index. We used Kriging interpolation and BP neural network methods to estimate the spatial distribution of arsenic (As and cadmium (Cd pollution in the study area. Additionally, we introduced a cross-validation method to measure the errors of the estimation results by the two interpolation methods and discussed the accuracy of the information contained in the estimation results. The conclusions are as follows: data distribution characteristics, spatial variability, and mean square errors (MSE of the different methods showed large differences. Estimation results from BP neural network models have a higher accuracy, the MSE of As and Cd are 0.0661 and 0.1743, respectively. However, the interpolation results show significant skewed distribution, and spatial autocorrelation is strong. Using Kriging interpolation, the MSE of As and Cd are 0.0804 and 0.2983, respectively. The estimation results have poorer accuracy. Combining the two methods can improve the accuracy of the Kriging interpolation and more comprehensively represent the spatial distribution characteristics of metal(loids in regional soil. The study may provide a scientific basis and technical support for the regulation of soil metal(loid pollution.

Factors of the accumulation of heavy metals and metalloids at geochemical barriers in urban soils

Science.gov (United States)

Kosheleva, N. E.; Kasimov, N. S.; Vlasov, D. V.

2015-05-01

The bulk contents and concentrations of mobile (extracted by an ammonium acetate buffer with EDTA) Cd, Pb, Sb, As, Bi, Zn, and Cu were determined in the surface horizons of urban soils in the Eastern administrative okrug of Moscow. The regression analysis showed that the accumulation of these metals and metalloids in the soils is controlled by the physicochemical soil properties and by number of anthropogenic factors and landscape conditions (geochemical position, type of loose deposits, character of land use, dust load, vehicle emissions, building pattern, percent of green areas, and the extent of sealed soils). The precipitation of studied elements on the geochemical barriers had the following regularities: Cd, Cu, and Zn accumulated on the alkaline barriers; Bi, Sb, As, Cu, Pb, and Zn, on chemisorption barriers; Sb, As, and Pb, on organomineral barriers; and Cd and Cu, on the sorption-sedimentation barriers. Technogenic transformation of the physicochemical properties of urban soils resulted in the increase of the mean bulk contents of heavy metals and metalloids by 33-99%; the portion of elements fixed on the geochemical barriers increased by 26-50%.

Leaching capacity of metals-metalloids and recovery of valuable materials from waste LCDs.

Science.gov (United States)

Savvilotidou, Vasiliki; Hahladakis, John N; Gidarakos, Evangelos

2015-11-01

The purpose of Directive 2012/19/EU which is related to WEEE (Waste Electrical and Electronic Equipment), also known as "e-waste", is to contribute to their sustainable production and consumption that would most possibly be achieved by their recovery, recycling and reuse. Under this perspective, the present study focused on the recovery of valuable materials, metals and metalloids from LCDs (Liquid Crystal Displays). Indium (In), arsenic (As) and stibium (Sb) were selected to be examined for their Leaching Capacity (R) from waste LCDs. Indium was selected mainly due to its rarity and preciousness, As due to its high toxicity and wide use in LCDs and Sb due to its recent application as arsenic's replacement to improve the optimal clarity of a LCD screen. The experimental procedure included disassembly of screens along with removal and recovery of polarizers via thermal shock, cutting, pulverization and digestion of the shredded material and finally leaching evaluation of the aforementioned elements. Leaching tests were conducted under various temperatures, using various solid:liquid (S/L) ratios and solvents (acid mixtures), to determine the optimal conditions for obtaining the maximum leaching capacities. The examined elements exhibited different leaching behaviors, mainly due to the considerable diversity in their inherent characteristic properties. Indium demonstrated the highest recovery percentages (approximately 60%), while the recovery of As and Sb was unsuccessful, obtaining poor leaching percentages (0.16% and 0.5%, respectively). Copyright © 2015 Elsevier Ltd. All rights reserved.

Fabrication and characterization of an all-solid tellurite-phosphate photonic bandgap fiber.

Science.gov (United States)

Cheng, Tonglei; Sakai, Yukiko; Suzuki, Takenobu; Ohishi, Yasutake

2015-05-01

We present an all-solid tellurite-phosphate photonic bandgap fiber (PBGF) with two layers of high-index rods (TeO2-Li2O-WO3-MoO3-Nb2O5, TLWMN) in the cladding (TeO2-ZnO-Li2O-K2O-Al2O3-P2O5, TZLKAP). TLWMN and TZLKAP glasses have good compatibility for fabricating the all-solid PBGF. Photonic bandgap (PBG) properties are calculated by the plane wave expansion method (PWM), and the results agree well with the measured transmission spectrum. Furthermore, the modal field patterns are measured at ∼1300 and 1520 nm, respectively. The light is confined to the core at ∼1300  nm and lost in the cladding at ∼1520  nm, which match well with the calculated modal field intensities.

Luminescent properties of Ln3+ doped tellurite glasses containing AlF3

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Walas, Michalina; Pastwa, Agata; Lewandowski, Tomasz; Synak, Anna; Gryczyński, Ignacy; Sadowski, Wojciech; Kościelska, Barbara

2016-09-01

The low-phonon energy tellurite glasses TeO2-BaO-Bi2O3 and TeO2-BaO-Bi2O3-AlF3 triply doped with Eu3+, Tb3+, Tm3+ ions in two different molar ratios were synthesized using melt-quenching technique. Their structure and luminescence properties were widely investigated by X-ray Diffraction (XRD), Differential Scanning Calorimetry (DSC), Fourier Transform Infrared Spectroscopy (FTIR) and Photoluminescence Spectroscopy (PL). The luminescence spectra of Eu3+, Tb3+, Tm3+ co-doped glasses show apart of the bands corresponding to the 4f-4f transitions of lanthanide ions also band corresponding to glass matrix. AlF3 doping increases emission intensity, although to improve overall emission color further studies on molar composition of samples and the molar ratio of the components should be carried out.

A comparison of technologies for remediation of heavy metal contaminated soils

OpenAIRE

Khalid , Sana; Shahid , Muhammad; Niazi , Nabeel Khan; Murtaza , Behzad; Bibi , Irshad; Dumat , Camille

2016-01-01

International audience; Soil contamination with persistent and potentially (eco)toxic heavy metal(loid)s is ubiquitous around the globe. Concentration of these heavy metal(loid)s in soil has increased drastically over the last three decades, thus posing risk to the environment and human health. Some technologies have long been in use to remediate the hazardous heavy metal(loid)s. Conventional remediation methods for heavy metal(loid)s are generally based on physical, chemical and biological a...

Toxic metal(loid)-based pollutants and their possible role in autism spectrum disorder.

Science.gov (United States)

Bjørklund, Geir; Skalny, Anatoly V; Rahman, Md Mostafizur; Dadar, Maryam; Yassa, Heba A; Aaseth, Jan; Chirumbolo, Salvatore; Skalnaya, Margarita G; Tinkov, Alexey A

2018-06-11

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by deficits in social interaction, verbal and non-verbal communication, and stereotypic behaviors. Many studies support a significant relationship between many different environmental factors in ASD etiology. These factors include increased daily exposure to various toxic metal-based environmental pollutants, which represent a cause for concern in public health. This article reviews the most relevant toxic metals, commonly found, environmental pollutants, i.e., lead (Pb), mercury (Hg), aluminum (Al), and the metalloid arsenic (As). Additionally, it discusses how pollutants can be a possible pathogenetic cause of ASD through various mechanisms including neuroinflammation in different regions of the brain, fundamentally occurring through elevation of the proinflammatory profile of cytokines and aberrant expression of nuclear factor kappa B (NF-κB). Due to the worldwide increase in toxic environmental pollution, studies on the role of pollutants in neurodevelopmental disorders, including direct effects on the developing brain and the subjects' genetic susceptibility and polymorphism, are of utmost importance to achieve the best therapeutic approach and preventive strategies. Copyright © 2018 Elsevier Inc. All rights reserved.

Health risk assessment of heavy metals and metalloid in drinking water from communities near gold mines in Tarkwa, Ghana.

Science.gov (United States)

Bortey-Sam, Nesta; Nakayama, Shouta M M; Ikenaka, Yoshinori; Akoto, Osei; Baidoo, Elvis; Mizukawa, Hazuki; Ishizuka, Mayumi

2015-07-01

Concentrations of heavy metals and metalloid in borehole drinking water from 18 communities in Tarkwa, Ghana, were measured to assess the health risk associated with its consumption. Mean concentrations of heavy metals (μg/L) exceeded recommended values in some communities. If we take into consideration the additive effect of heavy metals and metalloid, then oral hazard index (HI) results raise concerns about the noncarcinogenic adverse health effects of drinking groundwater in Huniso. According to the US Environmental Protection Agency's (USEPA) guidelines, HI values indicating noncarcinogenic health risk for adults and children in Huniso were 0.781 (low risk) and 1.08 (medium risk), respectively. The cancer risk due to cadmium (Cd) exposure in adults and children in the sampled communities was very low. However, the average risk values of arsenic (As) for adults and children through drinking borehole water in the communities indicated medium cancer risk, but high cancer risk in some communities such as Samahu and Mile 7. Based on the USEPA assessment, the average cancer risk values of As for adults (3.65E-05) and children (5.08E-05) indicated three (adults) and five (children) cases of neoplasm in a hundred thousand inhabitants. The results of this study showed that residents in Tarkwa who use and drink water from boreholes could be at serious risk from exposure to these heavy metals and metalloid.

Comparative analyses reveal different consequences of two oxidative stress inducers, gamma irradiation and potassium tellurite, in the extremophile Deinococcus radiodurans

International Nuclear Information System (INIS)

Narasimha, Anaganti; Basu, Bhakti; Apte, Shree Kumar

2014-01-01

Proteomic and mass spectrometric analyses revealed differential responses of D. radiodurans to two oxidative stressors. While both elicited oxidative stress alleviation response, major divergence was observed at the level of DNA repair, metabolic pathways and protein homeostasis. Response to gamma irradiation was focused on DNA repair and ROS scavenging but supported metabolism as well as protein homeostasis. Tellurite, induced oxidative stress alleviation but decreased reducing affected and adversely affected metabolism and protein homeostasis

Risk Assessment and Source Identification of 17 Metals and Metalloids on Soils from the Half-Century Old Tungsten Mining Areas in Lianhuashan, Southern China

OpenAIRE

Guo, Li; Zhao, Weituo; Gu, Xiaowen; Zhao, Xinyun; Chen, Juan; Cheng, Shenggao

2017-01-01

Background: Mining activities always emit metal(loid)s into the surrounding environment, where their accumulation in the soil may pose risks and hazards to humans and ecosystems. Objective: This paper aims to determine of the type, source, chemical form, fate and transport, and accurate risk assessment of 17 metal(loid) contaminants including As, Cd, Cu, Ni, Pb, Zn, Cr, Ag, B, Bi, Co, Mo, Sb, Ti, V, W and Sn in the soils collected from an abandoned tungsten mining area, and to guide the imple...

Radiative transition, local field enhancement and energy transfer microcosmic mechanism of tellurite glasses containing Er3+, Yb3+ ions and Ag nanoparticles

International Nuclear Information System (INIS)

Zhang, Wenjun; Lin, Jian; Cheng, Mingzhao; Zhang, Shuo; Jia, Yujie; Zhao, Junhong

2015-01-01

Er 3+ -doped, Er 3+ /Yb 3+ co-doped tellurite glass with and without Ag NPs were synthesized by melt-quenching method. The high resolution transmission electron microscopy (HR-TEM) and selected area electron diffractions (SAED) manifest growth of Ag NPs. The UV–vis–NIR absorption spectroscopy and fluorescence spectroscopy were measured. The optical band gap and multiphonon relaxation rate constants were calculated. The electronic band structure and local density of state (DOS) of Ag NPs are calculated. The fluorescence emission and enhancement mechanism including localized surface plasmon resonance (LSPR) and energy transfer (ET) microcosmic mechanism were discussed. The electric field distributions of Ag NPs are emulated by FDTD solutions software. Local field enhancement (LFE) induced by LSPR and lightning rod effect was found to be responsible for the fluorescence enhancement while energy transfer from Ag NPs to rare-earth was considered ignorable in the samples without photoluminescent emission. - Highlights: • Tellurite glasses containing Er 3+ , Yb 3+ and Ag NPs are prepared. • Judd–Ofelt and multiphonon relaxation are calculated. • The electronic band structures of Ag NPs are calculated. • The energy transfer mechanism is discussed. • The plasmon resonance effect of Ag NPs is discussed

Spectral properties of Er3+/Yb3+ codoped tungsten-tellurite glasses.

Science.gov (United States)

Shen, Xiang; Nie, QiuHua; Xu, TieFeng; Gao, Yuan

2005-07-01

The spectral properties of Er3+/Yb3+ codoped tungsten-tellurite (WT) glasses have been investigated. The measured absorption spectra are analyzed by Judd-Ofelt theory. The compositional change of intensity parameter omega2 is attributed to the change in the covalency between the Er3+ and oxygen ions, the asymmetry in the local structures around the Er3+ ions can be neglected. The lifetimes of 4I(13/2) level of Er3+ in WT glasses are measured and comparable with other TeO2-based glasses. The stimulated emission cross-section is calculated based on McCumber theory. The fluorescence full width at half maximum (FWHM) and the emission cross-section (sigma(peak)) of the 4I(13/2) --> 4I(15/2) transition of Er3+ in different glass hosts have been compared. The suitability of such WT glasses as host materials for 1.5 microm broadband amplification is discussed.

Self-Q-switching behavior of erbium-doped tellurite microstructured fiber lasers

International Nuclear Information System (INIS)

Jia, Zhi-Xu; Yao, Chuan-Fei; Kang, Zhe; Qin, Guan-Shi; Qin, Wei-Ping; Ohishi, Yasutake

2014-01-01

We reported self-Q-switching behavior of erbium-doped tellurite microstructured fiber (EDTMF) lasers and further demonstrated a self-Q-switched EDTMF laser with a high repetition rate of more than 1 MHz. A 14 cm EDTMF was used as the gain medium. Upon a pump power of ∼705 mW at 1480 nm, output pulses with a lasing wavelength of ∼1558 nm, a repetition rate of ∼1.14 MHz, and a pulse width of ∼282 ns were generated from the fiber by employing a linear cavity. The maximum output power was ∼316 mW and the slope efficiency was about 72.6% before the saturation of the laser power. Moreover, the influence of the fiber length on laser performances was investigated. The results showed that self-Q-switching behavior in our experiments was caused by the re-absorption originated from the ineffectively pumped part of the active fiber.

Variation of energy absorption and exposure buildup factors with incident photon energy and penetration depth for boro-tellurite (B2O3-TeO2) glasses

Science.gov (United States)

Sayyed, M. I.; Elhouichet, H.

2017-01-01

The gamma ray energy absorption (EABF) and exposure buildup factors (EBF) of (100-x)TeO2-xB2O3 glass systems (where x=5, 10, 15, 20, 22.5 and 25 mol%) have been calculated in the energy region 0.015-15 MeV up to a penetration depth of 40 mfp (mean free path). The five parameters (G-P) fitting method has been used to estimate both EABF and EBF values. Variations of EABF and EBF with incident photon energy and penetration depth have been studied. It was found that EABF and EBF values were higher in the intermediate energy region, for all the glass systems. Furthermore, boro-tellurite glass with 5 mol% B2O3, was found to present the lowest EABF and EBF values, hence it is superior gamma-ray shielding material. The results indicate that the boro-tellurite glasses can be used as radiation shielding materials.

Reaction of 11 C-benzoyl chlorides with metalloid reagents: 11 C-labeling of benzyl alcohols, benzaldehydes, and phenyl ketones from [11 C]CO.

Science.gov (United States)

Roslin, Sara; Dahl, Kenneth; Nordeman, Patrik

2018-01-26

In this article, we describe the carbon-11 ( 11 C, t 1/2  = 20.4 minutes) labeling of benzyl alcohols, benzaldehydes, and ketones using an efficient 2-step synthesis in which 11 C-carbon monoxide is used in an initial palladium-mediated reaction to produce 11 C-benzoyl chloride as a key intermediate. In the second step, the obtained 11 C-benzoyl chloride is further treated with a metalloid reagent to furnish the final 11 C-labeled product. Benzyl alcohols were obtained in moderated to high non-isolated radiochemical yields (RCY, 35%-90%) with lithium aluminum hydride or lithium aluminum deuteride as metalloid reagent. Changing the metalloid reagent to either tributyltin hydride or sodium borohydride, allowed for the reliable syntheses of 11 C-benzaldehydes in RCYs ranging from 58% to 95%. Finally, sodium tetraphenylborate were utilized to obtain 11 C-phenyl ketones in high RCYs (77%-95%). The developed method provides a new and efficient route to 3 different classes of compounds starting from aryl iodides or aryl bromides. Copyright © 2018 John Wiley & Sons, Ltd.

Comparison Study on the Estimation of the Spatial Distribution of Regional Soil Metal(loid)s Pollution Based on Kriging Interpolation and BP Neural Network.

Science.gov (United States)

Jia, Zhenyi; Zhou, Shenglu; Su, Quanlong; Yi, Haomin; Wang, Junxiao

2017-12-26

Soil pollution by metal(loid)s resulting from rapid economic development is a major concern. Accurately estimating the spatial distribution of soil metal(loid) pollution has great significance in preventing and controlling soil pollution. In this study, 126 topsoil samples were collected in Kunshan City and the geo-accumulation index was selected as a pollution index. We used Kriging interpolation and BP neural network methods to estimate the spatial distribution of arsenic (As) and cadmium (Cd) pollution in the study area. Additionally, we introduced a cross-validation method to measure the errors of the estimation results by the two interpolation methods and discussed the accuracy of the information contained in the estimation results. The conclusions are as follows: data distribution characteristics, spatial variability, and mean square errors (MSE) of the different methods showed large differences. Estimation results from BP neural network models have a higher accuracy, the MSE of As and Cd are 0.0661 and 0.1743, respectively. However, the interpolation results show significant skewed distribution, and spatial autocorrelation is strong. Using Kriging interpolation, the MSE of As and Cd are 0.0804 and 0.2983, respectively. The estimation results have poorer accuracy. Combining the two methods can improve the accuracy of the Kriging interpolation and more comprehensively represent the spatial distribution characteristics of metal(loid)s in regional soil. The study may provide a scientific basis and technical support for the regulation of soil metal(loid) pollution.

"Incorporating epigenetic data into the risk assessment process for the toxic metals arsenic, cadmium, chromium, lead, and mercury: strategies and challenges."

Directory of Open Access Journals (Sweden)

Paul eRay

2014-07-01

Full Text Available Exposure to toxic metals poses a serious human health hazard based on ubiquitous environmental presence, the extent of exposure, and the toxicity and disease states associated with exposure. This global health issue warrants accurate and reliable models derived from the risk assessment process to predict disease risk in populations. There has been considerable interest recently in the impact of environmental toxicants such as toxic metals on the epigenome. Epigenetic modifications are somatically inherited alterations to an individual’s genome without a change in the DNA sequence, and include, but are not limited to, three commonly studied alterations: DNA methylation, histone modification, and non-coding RNA expression. Given the role of epigenetic alterations in regulating gene and thus protein expression, there is the potential for the integration of toxic metal-induced epigenetic alterations as informative factors in the risk assessment process. In the present review, epigenetic alterations induced by five high priority toxic metals/metalloids are prioritized for analysis and their possible inclusion into the risk assessment process is discussed.

Data on metals (Zn, Al, Sr, and Co and metalloid (As concentration levels of ballast water in commercial ships entering Bushehr port, along the Persian Gulf

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Farshid Soleimani

2016-12-01

Full Text Available In this article, we determined the concentration levels of metals including Zn, Al, Sr, and Co and metalloid of As of ballast water in commercial ships entering Bushehr port, along the Persian Gulf. Ballast water samples were taken from commercial ships entering Bushehr port from 34 ports around the world during 15 February and 25 August 2016. The concentration levels of metals and metalloid were determined by using a graphite furnace absorption spectrometer (AAS.

Immunological alterations in individuals exposed to metal(loid)s in the Panasqueira mining area, Central Portugal.

Science.gov (United States)

Coelho, Patrícia; García-Lestón, Julia; Costa, Solange; Costa, Carla; Silva, Susana; Fuchs, Dietmar; Geisler, Simon; Dall'Armi, Valentina; Zoffoli, Roberto; Bonassi, Stefano; Pásaro, Eduardo; Laffon, Blanca; Teixeira, João Paulo

2014-03-15

Environmental studies performed in Panasqueira mine area (central Portugal) identified high concentrations of several metal(loid)s in environmental media, and individuals environmentally and occupationally exposed showed higher levels of As, Cr, Mg, Mn, Mo, Pb and Zn in blood, urine, hair and nails when compared to unexposed controls. To evaluate the presence of immunological alterations attributable to environmental contamination, we quantified neopterin, kynurenine, tryptophan, and nitrite concentrations in plasma, and analysed the percentage of several lymphocytes subsets, namely CD3(+), CD4(+) and CD8(+) T-cells, CD19(+) B-cells, and CD16(+)56(+) natural killer (NK) cells in a group of individuals previously tested for metal(loid) levels in different biological matrices. The environmentally exposed group had significantly lower levels of %CD8(+) and higher CD4(+)/CD8(+) ratios, whereas the occupationally exposed individuals showed significant decreases in %CD3(+) and %CD4(+), and significant increases in %CD16(+)56(+), when compared to controls. Analysed biomarkers were found to be influenced by age, particularly neopterin, kynurenine and kynurenine to tryptophan ratio (Kyn/Trp) with significantly higher levels in older individuals, and %CD3(+), %CD8(+) and %CD19(+) with significantly lower values in older individuals. Males environmentally exposed showed significantly lower values of %CD19(+) when compared to control females. The concentration of Pb in toenails was associated to the level of neopterin, kynurenine and Kyn/Trp ratio (all direct), and the concentration of Mn in blood to the level of %CD8(+), %CD19(+) (both inverse) and CD4(+)/CD8(+) ratio (direct). Overall our results show that the metal(loid) contamination in Panasqueira mine area induced immunotoxic effects in exposed populations, possibly increasing susceptibility to diseases. Copyright © 2013 Elsevier B.V. All rights reserved.

Assessment of lead tellurite glass for immobilizing electrochemical salt wastes from used nuclear fuel reprocessing

Energy Technology Data Exchange (ETDEWEB)

Riley, Brian J.; Kroll, Jared O.; Peterson, Jacob A.; Pierce, David A.; Ebert, William L.; Williams, Benjamin D.; Snyder, Michelle M. V.; Frank, Steven M.; George, Jaime L.; Kruska, Karen

2017-11-01

This paper provides an overview of research evaluating the use of tellurite glass as a waste form for salt wastes from electrochemical processing. The capacities to immobilize different salts were evaluated including: a LiCl-Li2O oxide reduction salt (for oxide fuel) containing fission products, a LiCl-KCl eutectic salt (for metallic fuel) containing fission products, and SrCl2. Physical and chemical properties of the glasses were characterized by using X-ray diffraction, bulk density measurements, chemical durability tests, scanning electron microscopy, and energy dispersive X-ray emission spectroscopy. These glasses were found to accommodate high concentrations of halide salts and have high densities. However, improvements are needed to meet chemical durability requirements.

Watt-level ~2 μm laser output in Tm3+-doped tungsten tellurite glass double-cladding fiber.

Science.gov (United States)

Li, Kefeng; Zhang, Guang; Hu, Lili

2010-12-15

We report, for the first time to the best of our knowledge, a watt level cw fiber laser at ~2 μm from a piece of 40-cm-long newly developed highly thulium-doped (3.76 × 10(20) ions/cm(3)) tungsten tellurite glass double cladding fiber pumped by a commercial 800 nm laser diode. The maximum output power of the fiber laser reaches 1.12 W. The slope efficiency and the optical-optical efficiency with respect to the absorbed pump are 20% and 16%, respectively. The lasing threshold is 1.46 W, and the lasing wavelength is centered at 1937 nm.

Vermiremediation of metal(loid)s via Eichornia crassipes phytomass extraction: A sustainable technique for plant amelioration.

Science.gov (United States)

Majumdar, Arnab; Barla, Anil; Upadhyay, Munish Kumar; Ghosh, Dibyarpita; Chaudhuri, Punarbasu; Srivastava, Sudhakar; Bose, Sutapa

2018-08-15

Eichhornia crassipes (water hyacinth), imparts deficiency of soluble arsenic and other toxic metal (loid)s through rhizofiltration and phytoaccumulation. Without proper management strategy, this phytoremediation of metal (loid)s might fail and get reverted back to the environment, contaminating the nearby water bodies. This study, focused on bio-conversion of phytoremediating hyacinths, spiked with 100 times and greater arsenic, lead and cadmium concentrations than the average water contamination, ranging in 58.81 ± 0.394, 16.74 ± 0.367, 12.18 ± 0.153 mg Kg -1 arsenic, 18.95 ± 0.212, 9.53 ± 0.054, 6.83 ± 0.306 mg kg -1 lead and 2.79 ± 0.033, 1.39 ± 0.025, 0.92 ± 0.045 mg kg -1 cadmium, respectively in root, shoot and leaves, proving it's phytoaccumulation capacity. Next, these hyacinths has been used as a source of organic supplement for preparing vermicompost using Eisenia fetida following analysis of total metal content and sequential extraction. Control soil was having 134.69 ± 2.47 mg kg -1 arsenic in compare to 44.6 ± 0.91 mg kg -1 at premature stage of compost to 23.9 ± 1.55 mg kg -1 at mature compost indicating sustainable fate of phytoremediated vermicompost. This vermiremediation of arsenic and other toxic elements, restricted the bioavailability of soil pollutants. Furthermore, processed compost amended as organic fertilizer, growing chickpea, coriander, tomato and chilli plant, resulted in negligible metal(loid)s in treated samples, enhancing also plant's growth and production. Copyright © 2018 Elsevier Ltd. All rights reserved.

An experimental study on the geochemical behavior of highly siderophile elements (HSE) and metalloids (As, Se, Sb, Te, Bi) in a mss-iss-pyrite system at 650 °C: A possible magmatic origin for Co-HSE-bearing pyrite and the role of metalloid-rich phases in the fractionation of HSE

Science.gov (United States)

Cafagna, Fabio; Jugo, Pedro J.

2016-04-01

Pyrite, the most abundant sulfide in the Earth's crust, is an accessory mineral in several magmatic sulfide deposits. Although most pyrite is hydrothermal, previous experimental studies have shown that pyrite can also have a primary magmatic origin, by exsolving from monosulfide solid solution (mss) during cooling of a sulfide melt, if sulfur fugacity is sufficiently high. Pyrite from some localities has significant amounts of Co, and complex zonation in some low-melting-point chalcophile elements (LMCE), such as As, Se, Sb, Te, Bi (henceforth referred to as metalloids) and some platinum-group elements (PGE: Ru, Rh, Pd, Os, Ir, Pt). However, the origin of such pyrite and the causes of zonation are not clear. Because the distribution of some of these elements is heterogeneous and seems to be developed in concentric zones, the zonation has been interpreted to represent growth stages, some of them secondary and caused partly by hydrothermal fluids. Better constraints on the origin of Co-PGE-bearing pyrite could help unravel the geochemical processes affecting the sulfide assemblages in which it is found; thus, an experimental study was undertaken to characterize pyrite formation in magmatic sulfide environments and its relationship with metalloids and highly siderophile elements (HSE: PGE, Re, Au). Natural pyrrhotite, chalcopyrite, pentlandite and elemental S were mixed and doped with approximately 50 ppm of each HSE. A mixture of metalloids was added at 0.2 wt.% or 3 wt.% to aliquots of sulfide mixtures. Starting materials were sealed in evacuated silica tubes and fused at 1200 °C. The temperature was subsequently reduced to 750 °C (at 60 °C/h), then to 650 °C (at 0.5 °C/h) to produce relatively large euhedral pyrite crystals, then quenched. The experiments were analyzed using reflected light, SEM, EPMA and LA-ICP-MS. Experimental products contained euhedral pyrite, mss, intermediate solid solution (iss) and metalloid-rich phases, interpreted as quench product

Occurrence and risk assessment of trace metals and metalloids in sediments and benthic invertebrates from Dianshan Lake, China.

Science.gov (United States)

Wu, Yan; Zhou, Yihui; Qiu, Yanling; Chen, Da; Zhu, Zhiliang; Zhao, Jianfu; Bergman, Ǻke

2017-06-01

The present study measured concentrations of Cr, Ni, Cu, Zn, As, Cd, Sb, and Pb in surface sediments and two benthic invertebrate species (Anodonta woodiana and Bellamya aeruginosa) collected from Dianshan Lake, located in the Yangtze River Delta. The Dianshan Lake acts as one of the most important drinking water sources to Shanghai, the biggest city in China. Concentrations of trace metals and metalloids ranged from 0.04 mg/kg for Cd to 288.0 mg/kg for Zn. Substantial bioaccumulation in invertebrates was observed for Zn and Cu based on the biota-sediment accumulation factor (BSAF) measurements. The results revealed that concentrations of metals and metalloids in sediments from Dianshan Lake were at the lower end of the range of levels found in other regions of China. The assessment of three significantly inter-related evaluation indices, including the geo-accumulation Index (I geo ), potential ecological risk factor (Er i ), and mean probable effect concentration quotients (Q m-PEC ), suggested that sediment-associated trace elements exhibited no considerable ecological risks in the studied watershed. However, the target hazard quotient and hazard index analysis suggested that selected elements (particularly As) accumulation in edible tissues of benthic invertebrates could pose potential health risks to local populations, especially fishermen. Given that wild aquatic organisms (e.g., fish and bivalves) constitute the diet of local populations as popular food/protein choices, further investigations are needed to better elucidate human health risks from metal and metalloid exposure via edible freshwater organisms.

Preparation and optical properties of TeO2-BaO-ZnO-ZnF2 fluoro-tellurite glass for mid-infrared fiber Raman laser applications

Science.gov (United States)

Li, Jie; Xiao, Xusheng; Gu, Shaoxuan; Xu, Yantao; Zhou, Zhiguang; Guo, Haitao

2017-04-01

A serial of novel fluoro-tellurite glasses with compositions of 60TeO2-20BaO-(20-x)ZnO-xZnF2 (x = 0, 2, 4, 5 and 6 mol%) were prepared. The compositional dependences of glass structural evaluation, Raman gain coefficient, UV-Vis transmission spectrum, IR transmission spectrum, linear refractive index and third-order nonlinearity were analyzed. The results showed that the addition of 6 mol% ZnF2 can further improve the Raman gain coefficient to as well as 52 × 10-11 cm/W and effectively decrease around 73% and 57% absorption coefficients respectively caused by free Osbnd H groups (@3.3 μm) and hydrogen-bonded Osbnd H groups (@4.5 μm) in glass. Addition of ZnF2 does not change the UV-Vis absorption edge, optical band gap energy and infrared region cut-off edge almost, while the linear refraction index and ultrafast third-nonlinearity show unmonotonic changes. These novel fluoro-tellurite glasses may be suitable candidates for using in mid-infrared Raman fiber laser and/or amplifier.

Variation and distribution of metals and metalloids in soil/ash mixtures from Agbogbloshie e-waste recycling site in Accra, Ghana

Energy Technology Data Exchange (ETDEWEB)

Itai, Takaaki, E-mail: itai@sci.ehime-u.ac.jp [Center for Marine Environmental Studies, Ehime University, Bunkyo-cho 2-5, Matsuyama, Ehime 790-8577 (Japan); Otsuka, Masanari [Center for Marine Environmental Studies, Ehime University, Bunkyo-cho 2-5, Matsuyama, Ehime 790-8577 (Japan); Asante, Kwadwo Ansong [Center for Marine Environmental Studies, Ehime University, Bunkyo-cho 2-5, Matsuyama, Ehime 790-8577 (Japan); CSIR Water Research Institute, P. O. Box AH 38, Achimota, Accra (Ghana); Muto, Mamoru [Center for Marine Environmental Studies, Ehime University, Bunkyo-cho 2-5, Matsuyama, Ehime 790-8577 (Japan); Opoku-Ankomah, Yaw; Ansa-Asare, Osmund Duodu [CSIR Water Research Institute, P. O. Box AH 38, Achimota, Accra (Ghana); Tanabe, Shinsuke [Center for Marine Environmental Studies, Ehime University, Bunkyo-cho 2-5, Matsuyama, Ehime 790-8577 (Japan)

2014-02-01

Illegal import and improper recycling of electronic waste (e-waste) are an environmental issue in developing countries around the world. African countries are no exception to this problem and the Agbogbloshie market in Accra, Ghana is a well-known e-waste recycling site. We have studied the levels of metal(loid)s in the mixtures of residual ash, formed by the burning of e-waste, and the cover soil, obtained using a portable X-ray fluorescence spectrometer (P-XRF) coupled with determination of the 1 M HCl-extractable fraction by an inductively coupled plasma mass spectrometer. The accuracy and precision of the P-XRF measurements were evaluated by measuring 18 standard reference materials; this indicated the acceptable but limited quality of this method as a screening tool. The HCl-extractable levels of Al, Co, Cu, Zn, Cd, In, Sb, Ba, and Pb in 10 soil/ash mixtures varied by more than one order of magnitude. The levels of these metal(loid)s were found to be correlated with the color (i.e., soil/ash ratio), suggesting that they are being released from disposed e-waste via open burning. The source of rare elements could be constrained using correlation to the predominant metals. Human hazard quotient values based on ingestion of soil/ash mixtures exceeded unity for Pb, As, Sb, and Cu in a high-exposure scenario. This study showed that along with common metals, rare metal(loid)s are also enriched in the e-waste burning site. We suggest that risk assessment considering exposure to multiple metal(loid)s should be addressed in studies of e-waste recycling sites. - Highlights: • Contamination on the largest e-waste recycling site in Africa was investigated. • Portable X-ray Fluorescence analyzer useful for first screening • High levels of Cu, Zn, Pb, and Al in soil/ash mixtures • Hazards for workers are significant.

Variation and distribution of metals and metalloids in soil/ash mixtures from Agbogbloshie e-waste recycling site in Accra, Ghana

International Nuclear Information System (INIS)

Itai, Takaaki; Otsuka, Masanari; Asante, Kwadwo Ansong; Muto, Mamoru; Opoku-Ankomah, Yaw; Ansa-Asare, Osmund Duodu; Tanabe, Shinsuke

2014-01-01

Illegal import and improper recycling of electronic waste (e-waste) are an environmental issue in developing countries around the world. African countries are no exception to this problem and the Agbogbloshie market in Accra, Ghana is a well-known e-waste recycling site. We have studied the levels of metal(loid)s in the mixtures of residual ash, formed by the burning of e-waste, and the cover soil, obtained using a portable X-ray fluorescence spectrometer (P-XRF) coupled with determination of the 1 M HCl-extractable fraction by an inductively coupled plasma mass spectrometer. The accuracy and precision of the P-XRF measurements were evaluated by measuring 18 standard reference materials; this indicated the acceptable but limited quality of this method as a screening tool. The HCl-extractable levels of Al, Co, Cu, Zn, Cd, In, Sb, Ba, and Pb in 10 soil/ash mixtures varied by more than one order of magnitude. The levels of these metal(loid)s were found to be correlated with the color (i.e., soil/ash ratio), suggesting that they are being released from disposed e-waste via open burning. The source of rare elements could be constrained using correlation to the predominant metals. Human hazard quotient values based on ingestion of soil/ash mixtures exceeded unity for Pb, As, Sb, and Cu in a high-exposure scenario. This study showed that along with common metals, rare metal(loid)s are also enriched in the e-waste burning site. We suggest that risk assessment considering exposure to multiple metal(loid)s should be addressed in studies of e-waste recycling sites. - Highlights: • Contamination on the largest e-waste recycling site in Africa was investigated. • Portable X-ray Fluorescence analyzer useful for first screening • High levels of Cu, Zn, Pb, and Al in soil/ash mixtures • Hazards for workers are significant

Supercritical water treatment of heavy metal and arsenic metalloid-bioaccumulating-biomass.

Science.gov (United States)

Li, Jianxin; Chen, Jinbo; Chen, Shan

2018-08-15

Hyperaccumulator biomass, as a promising resource for renewable energy that can be converted into valuable fuel productions with high conversion efficiency, must be considered as hazardous materials and be carefully treated before further reuse due to the high contents of heavy metals. In this study, Pteris vittata L., an As-hyperaccumulator biomass was treated by an effective and environmental friendly method-supercritical water gasification (SCWG) using a bench-scale batch reactor. The contents of heavy metals (Cd, Pb and Zn) and arsenic metalloid in solid, liquid and gaseous products during SCWG process were thoroughly investigated. The speciation fractions including exchangeable, reducible, oxidizable and residual fractions of each heavy metal as the proportion of the total contents in solid residue were presented and the transformations trend of these heavy metals during the SCWG process was especially demonstrated. The significant operating parameters, including reaction temperature (395-445 °C), pressure (21-27 MPa) and residence time (0-40 min) were varied to explore their effects on the contents and forms. Moreover, the environmental risks of heavy metals in solid residues were evaluated based on risk assessment code, taking into consideration the speciation fractions and bioavailability. It was highlighted that although heavy metals particularly Pb and Zn tended to accumulate in solid residues with a maximum increment of about 50% in the total content, they were mostly converted to more stable oxidizable and residual fractions, and thus the ecotoxicity and bioavailability were greatly mitigated with no obvious increase in direct toxicity fractions. Each tested heavy metal presented no or low risk to the environments after SCWG treatments, meaning that the environmental pollution levels were markedly reduced with no or low risk to the environment. This study highlights the remarkable ability of SCWG for the heavy metal stabilization. Copyright �

Biosorbents for Removing Hazardous Metals and Metalloids

Directory of Open Access Journals (Sweden)

Katsutoshi Inoue

2017-07-01

Full Text Available Biosorbents for remediating aquatic environmental media polluted with hazardous heavy metals and metalloids such as Pb(II, Cr(VI, Sb(III and V, and As(III and V were prepared from lignin waste, orange and apple juice residues, seaweed and persimmon and grape wastes using simple and cheap methods. A lignophenol gel such as lignocatechol gel was prepared by immobilizing the catechol functional groups onto lignin from sawdust, while lignosulfonate gel was prepared directly from waste liquor generated during pulp production. These gels effectively removed Pb(II. Orange and apple juice residues, which are rich in pectic acid, were easily converted using alkali (e.g., calcium hydroxide into biosorbents that effectively removed Pb(II. These materials also effectively removed Sb(III and V and As(III and V when these were preloaded with multi-valent metal ions such as Zr(IV and Fe(III. Similar biosorbents were prepared from seaweed waste, which is rich in alginic acid. Other biosorbents, which effectively removed Cr(VI, were prepared by simply treating persimmon and grape wastes with concentrated sulfuric acid.

Influence of fine process particles enriched with metals and metalloids on Lactuca sativa L. leaf fatty acid composition following air and/or soil-plant field exposure.

Science.gov (United States)

Schreck, Eva; Laplanche, Christophe; Le Guédard, Marina; Bessoule, Jean-Jacques; Austruy, Annabelle; Xiong, Tiantian; Foucault, Yann; Dumat, Camille

2013-08-01

We investigate the effect of both foliar and root uptake of a mixture of metal(loid)s on the fatty acid composition of plant leaves. Our objectives are to determine whether both contamination pathways have a similar effect and whether they interact. Lactuca sativa L. were exposed to fine process particles enriched with metal(loid)s in an industrial area. Data from a first experiment were used to conduct an exploratory statistical analysis which findings were successfully cross-validated by using the data from a second one. Both foliar and root pathways impact plant leaf fatty acid composition and do not interact. Z index (dimensionless quantity), weighted product of fatty acid concentration ratios was built up from the statistical analyses. It provides new insights on the mechanisms involved in metal uptake and phytotoxicity. Plant leaf fatty acid composition is a robust and fruitful approach to detect and understand the effects of metal(loid) contamination on plants. Copyright © 2013 Elsevier Ltd. All rights reserved.

Influence of fine process particles enriched with metals and metalloids on Lactuca sativa L. leaf fatty acid composition following air and/or soil-plant field exposure

International Nuclear Information System (INIS)

Schreck, Eva; Laplanche, Christophe; Le Guédard, Marina; Bessoule, Jean-Jacques; Austruy, Annabelle; Xiong, Tiantian; Foucault, Yann; Dumat, Camille

2013-01-01

We investigate the effect of both foliar and root uptake of a mixture of metal(loid)s on the fatty acid composition of plant leaves. Our objectives are to determine whether both contamination pathways have a similar effect and whether they interact. Lactuca sativa L. were exposed to fine process particles enriched with metal(loid)s in an industrial area. Data from a first experiment were used to conduct an exploratory statistical analysis which findings were successfully cross-validated by using the data from a second one. Both foliar and root pathways impact plant leaf fatty acid composition and do not interact. Z index (dimensionless quantity), weighted product of fatty acid concentration ratios was built up from the statistical analyses. It provides new insights on the mechanisms involved in metal uptake and phytotoxicity. Plant leaf fatty acid composition is a robust and fruitful approach to detect and understand the effects of metal(loid) contamination on plants. -- Highlights: •The study compares foliar and root transfers of metal(loid)s and their effects on plants. •Field experiments are performed combining ecotoxicological and statistical analyses. •The use of leaf fatty acid composition is a relevant indicator of exposure pathway. •The uptake pathways are independent, with an additive effect in terms of phytotoxicity. -- Metal uptake via both foliar and root pathways alters in a distinctive manner the fatty acid composition of lettuce leaves

Toxicology of metals and metalloids: Promising issues for future studies in environmental health and toxicology.

Science.gov (United States)

Barbosa, Fernando

2017-01-01

The function and behavior of chemical elements in ecosystems and in human health probably comprise one of the most studied issues and a theme of great interest and fascination in science. Hot topics are emerging on an annual basis in this field. Bearing this in mind, some promising themes to explore in the field of metals and metalloids in the environment and in toxicology are highlighted and briefly discussed herein.

Thermal, structural and spectroscopic investigations on Eu{sup 3+} doped boro-tellurite glasses

Energy Technology Data Exchange (ETDEWEB)

Selvaraju, K. [Department of Physics, Gandhigram Rural University, Gandhigram 624 302 (India); Marimuthu, K., E-mail: mari_ram2000@yahoo.com [Department of Physics, Gandhigram Rural University, Gandhigram 624 302 (India); Seshagiri, T.K.; Godbole, S.V. [Radiochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085 (India)

2011-12-15

Highlights: Black-Right-Pointing-Pointer Fundamental O-H, (BO{sub 3}){sup -} vibrations and B-O-B linkages in borate network explored. Black-Right-Pointing-Pointer The covalent nature of the Eu{sup 3+} ions with surrounding ligands have been confirmed. Black-Right-Pointing-Pointer B3TMK glass is found to be the best optical candidate for laser working at 612 nm. - Abstract: Eu{sup 3+} doped boro-tellurite glasses with the chemical composition (69 - x)B{sub 2}O{sub 3}-xTeO{sub 2}-15Mg{sub 2}O-15K{sub 2}O-1Eu{sub 2}O{sub 3} (where x = 0, 10, 20, 30 and 40 wt%) have been synthesized and its thermal, structural and spectroscopic behavior were studied and reported. The thermal behavior of the Eu{sup 3+} doped boro-tellurite glasses were explored through DTA thermograms. The presence of varying tellurium dioxide results in structural and spectroscopic changes around Eu{sup 3+} ions and are explored through XRD, FTIR, UV-vis, Luminescence and lifetime measurements. The XRD pattern confirms the amorphous nature and the FTIR spectra reveal the formation of the local structural units BO{sub 3} and BO{sub 4} in the prepared glasses. The bonding parameters (-bar {beta} and {delta}) have been calculated based on the observed band positions of the absorption spectra. The Judd-Ofelt (JO) parameters were determined from the absorption and luminescence spectra and the results are presented. The variation in the JO intensity parameters {Omega}{sub {lambda}} ({lambda} = 2, 4 and 6) and the hypersensitive band positions with the change in chemical composition have been discussed in detail. The JO parameters have been used to derive important radiative properties like transition probabilities (A), branching ratios ({beta}{sub R}) and peak stimulated emission cross section ({sigma}E/P) for the {sup 5}D{sub 0} {yields} {sup 7}F{sub J} (J = 1, 2, 3 and 4) transitions of the Eu{sup 3+} ions. The varying optical properties of the prepared glasses with the change in tellurium dioxide have

[Detection of metals and metalloids in the lavage fluid of whole-lung lavage of the cases of pneumoconiosis].

Science.gov (United States)

Wen, K; Ding, C G; Chen, G; Ma, G X; Wang, H Q

2017-11-20

Objective: To detect of the components and concentration of the metals and metalloids in the lavage fluid of whole-lung lavage (WLL) of the cases of pneumoconiosis, and analyze the characteristics, and explore the method to sample and process the samples of bronchoalveolar lavage fluid (BAL) . Methods: The samples of urine and serum of three cases of pneumoconiosis were collected before WLL, and the samples of BAL were collected during the WLL from the left and right lungs according to the sequence of four pressured gas flow and five negative pressure drainage. Each of 10ml original samples of WLL was collected firstly, and the left was centrifuged to acquire all the sediment samples and each of 10 ml samples from the centrifuge clear liquids, The components and concentration of the metals and metalloids in the samples were measured by Inductively Coupled Plasma mass spectrometer (ICP-MS) . Results: The average volume of BAL from unilat-eral lung for 3 patients was 10 758.3±1518 ml, and the average recovery rate was 89.7%. The average dry weight of sediment samples of BAL of three cases of pneumoconiosis was 0.292 gram with the right lung sam-ples slightly higher than the left lung samples. The detectable elements from the samples included Barium (Ba) , Strontium (Sr) , Calcium (Ca) , Magnesium (Mg) , Manganum (Mn) , Ferrum (Fe) , Cuprum (Cu) , Zinc (Zn) , Kalium (K) , Natrium (Na) , Selenium (Se) , Silicon (Si) and Uranium (U) . Each of concentration dis-tributions of these elements were not normal. Except for Cuprum, Selenium and Uranium, the concentrations of the other ten elements in the supernatant samples, mixture samples and sediments samples were statistical-ly different with the nonparametric test of Kruskal-Wallis. The concentrations of Natrium, Kalium and Barium in supernatant samples were higher, while the others in precipitation samples were higher. The concentration of elements in the sample from the right lung was slightly higher than that from the

Tailoring Nd3+ emission spectrum by a neodymium-doped tellurite all-solid photonic bandgap fiber

Science.gov (United States)

Tong, Hoang Tuan; Demichi, Daisuke; Suzuki, Takenobu; Ohishi, Yasutake

2018-02-01

A tellurite all-solid photonic bandgap fiber (ASPBF) whose cladding consists of 60 high-index rods arranged periodically around a central core was successfully fabricated. The diameter of high-index rod was about 5.0 μm and the distance between the center of two adjacent high-index rods was approximately 8.0 μm. The high-index rod was made of the TeO2-Li2O-WO3-MoO3-Nb2O5 (TLWMN) glass, the cladding was made of the TeO2-ZnO-Na2O-La2O3 (TZNL) glass as the background glass material and the central core was made of TZNL glass doped with 0.5 wt% of Nd2O3. A supercontinuum light from 0.6 to 2.4 μm was coupled into the core of fiber which is 2.2 cm long to measure its transmission spectrum. High transmission bands were obtained in the vicinity of 0.75 and 1.3 μm but the transmission was suppressed in the wavelength range from 1.0 to 1.06 μm. When a titanium∶Sapphire laser source at 0.75 μm was used, the emission spectrum was obtained with two peaks at 1.06 and 1.33 μm which are attributed to the 4F3/2->4I11/2 and 4F3/2->4I13/2 transitions of Nd3+ ion, respectively. The intensities of those emission peaks were compared with those obtained from a bulk glass having the same doping concentration of Nd3+. The results showed that by using tellurite ASPBF, the intensity of the 1.06-μm emission was suppressed by one-twelfth but the intensity of the 1.33-μm emission was maintained. This feature is very advantageous to filter out the 1.06-μm emission of Nd3+ ion in order to realize practical amplifier devices at 1.3 μm.

Distributions, sources and pollution status of 17 trace metal/metalloids in the street dust of a heavily industrialized city of central China

International Nuclear Information System (INIS)

Li, Zhonggen; Feng, Xinbin; Li, Guanghui; Bi, Xiangyang; Zhu, Jianming; Qin, Haibo; Dai, Zhihui; Liu, Jinling; Li, Qiuhua; Sun, Guangyi

2013-01-01

A series of representative street dust samples were collected from a heavily industrialized city, Zhuzhou, in central China, with the aim to investigate the spatial distribution and pollution status of 17 trace metal/metalloid elements. Concentrations of twelve elements (Pb, Zn, Cu, Cd, Hg, As, Sb, In, Bi, Tl, Ag and Ga) were distinctly amplified by atmospheric deposition resulting from a large scale Pb/Zn smelter located in the northwest fringe of the city, and followed a declining trend towards the city center. Three metals (W, Mo and Co) were enriched in samples very close to a hard alloy manufacturing plant, while Ni and Cr appeared to derive predominantly from natural sources. Other industries and traffic had neglectable effects on the accumulation of observed elements. Cd, In, Zn, Ag and Pb were the five metal/metalloids with highest pollution levels and the northwestern part of city is especially affected by heavy metal pollution. -- Highlights: •Large-scale Pb/Zn smelters contributed to elevated trace elements in the street dust. •The hard alloy processing caused the enrichment of a few elements. •Cd, In, Zn, Ag and Pb were the most polluted elements. •Northwestern Zhuzhou suffered severe contamination for a range of trace elements. -- Pb/Zn smelting and hard alloy processing operations have caused seriously contamination of trace metal/metalloids in the street dust

Optical properties of Dy3+ doped bismuth boro-tellurite glasses for WLED applications

Science.gov (United States)

Karthikeyan, P.; Marimuthu, K.

2016-05-01

The Dy3+ doped bismuth boro-tellurite glasses with the chemical composition (79.5-x) B2O3+xTeO2+10Bi2O3+10PbF2+0.5Dy2O3 (where x = 10, 20, 30 and 40 in wt%) have been prepared by melt quenching technique. The optical properties of the prepared glasses have been studied through absorption and emission spectral measurements. The bonding parameters, optical band gap energy, Urbach's energy and Judd-Ofelt (JO) intensity parameters (Ωλ, λ = 2, 4 and 6) were calculated from the absorption spectra. The radiative properties like transition probability (A), stimulated emission cross-section (σPE) and branching ratios (βR) were calculated from the emission spectra using JO theory. The strong emissions in the visible region, large stimulated emission cross-section and higher branching ratio values observed for the title glasses are found to be suitable for lasers and WLED applications.

Plasmon-Assisted Efficiency Enhancement of Eu3+-Doped Tellurite Glass-Covered Solar Cells

Science.gov (United States)

Lima, Bismarck C.; Gómez-Malagón, L. A.; Gomes, A. S. L.; Garcia, J. A. M.; Kassab, L. R. P.

2017-12-01

Rare-earth-doped tellurite glass containing metallic nanoparticles can be exploited to manage the solar spectrum in order to increase solar cell efficiency. It is therefore possible to modify the incident solar spectrum profile to the spectrum that optimizes the solar cell recombination process by covering the solar cell with plasmonic luminescent downshifting layers. With this approach, the losses due to thermalization are minimized and the efficiency is increased. Due to the down-conversion process that couples the plasmon resonance of the metallic nanoparticles and the rare-earth electronic energy levels, it is possible to convert photons from the ultraviolet region to the visible and near-band-gap region of the semiconductor. It is demonstrated here that plasmon-assisted efficiency enhancements of 14.0% and 34.5% can be obtained for commercial Si and GaP solar cells, respectively, covered with Eu3+-doped TeO2-ZnO glass containing silver nanoparticles.

Biosorbents for Removing Hazardous Metals and Metalloids †

Science.gov (United States)

Inoue, Katsutoshi; Parajuli, Durga; Ghimire, Kedar Nath; Biswas, Biplob Kumar; Kawakita, Hidetaka; Oshima, Tatsuya; Ohto, Keisuke

2017-01-01

Biosorbents for remediating aquatic environmental media polluted with hazardous heavy metals and metalloids such as Pb(II), Cr(VI), Sb(III and V), and As(III and V) were prepared from lignin waste, orange and apple juice residues, seaweed and persimmon and grape wastes using simple and cheap methods. A lignophenol gel such as lignocatechol gel was prepared by immobilizing the catechol functional groups onto lignin from sawdust, while lignosulfonate gel was prepared directly from waste liquor generated during pulp production. These gels effectively removed Pb(II). Orange and apple juice residues, which are rich in pectic acid, were easily converted using alkali (e.g., calcium hydroxide) into biosorbents that effectively removed Pb(II). These materials also effectively removed Sb(III and V) and As(III and V) when these were preloaded with multi-valent metal ions such as Zr(IV) and Fe(III). Similar biosorbents were prepared from seaweed waste, which is rich in alginic acid. Other biosorbents, which effectively removed Cr(VI), were prepared by simply treating persimmon and grape wastes with concentrated sulfuric acid. PMID:28773217

New vanadium tellurites: Syntheses, structures, optical properties of noncentrosymmetric VTeO{sub 4}(OH), centrosymmetric Ba{sub 2}V{sub 4}O{sub 8}(Te{sub 3}O{sub 10})

Energy Technology Data Exchange (ETDEWEB)

Liang, Ming-Li [College of Chemistry, Fuzhou University, Fuzhou, Fujian 350108 (China); State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002 (China); Marsh, Matthew [Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL 32306 (United States); Shang, Xian-Xing [College of Chemistry, Fuzhou University, Fuzhou, Fujian 350108 (China); State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002 (China); Mao, Jiang-Gao [State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002 (China); Albrecht-Schmitt, Thomas E. [Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL 32306 (United States); Kong, Fang, E-mail: kongfang@fjirsm.ac.cn [State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002 (China); Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL 32306 (United States)

2017-05-15

Two new vanadium tellurites, VTeO{sub 4}(OH) (1) and Ba{sub 2}V{sub 4}O{sub 8}(Te{sub 3}O{sub 10}) (2), have been synthesized successfully with the use of hydrothermal reactions. The crystal structures of the two compounds were determined by single-crystal X-ray diffraction. Compound 1 crystallizes in the polar space group Pca2{sub 1} (No. 29) while compound 2 crystallizes in the centrosymmetric space group C2/c (No. 15). The topography of compound 1 reveals a two-dimensional, layered structure comprised of VO{sub 6} octahedral chains and TeO{sub 3}(OH) zig-zag chains. Compound 2, on the contrary, features a three-dimensional [V{sub 4}O{sub 8}(Te{sub 3}O{sub 10})]{sup 4-} anionic framework with Ba{sup 2+} ions filled into the 10-member ring helical tunnels. The [V{sub 4}O{sub 8}(Te{sub 3}O{sub 10})]{sup 4-} anionic network is the first 3D vanadium tellurite framework to be discovered in the alkaline-earth vanadium tellurite system. Powder second harmonic generation (SHG) measurements indicate that compound 1 shows a weak SHG response of about 0.3×KDP (KH{sub 2}PO{sub 4}) under 1064 nm laser radiation. Infrared spectroscopy, elemental analysis, thermal analysis, and dipole moment calculations have also been carried out. - Graphical abstract: VTeO{sub 4}(OH) (1) crystallizes in the noncentrosymmetric space group Pca2{sub 1} (No. 29) while Ba{sub 2}V{sub 4}O{sub 8}(Te{sub 3}O{sub 10}) (2) crystallizes in the centrosymmetric space group C2/c (No. 15). - Highlights: • VTeO{sub 4}(OH) (1) and Ba{sub 2}V{sub 4}O{sub 8}(Te{sub 3}O{sub 10}) (2) have been synthesized successfully with the use of hydrothermal reactions. • VTeO{sub 4}(OH) (1) crystallizes in the noncentrosymmetric space group Pca2{sub 1} and displays a weak SHG response. • VTeO{sub 4}(OH) (1) represents only the fourth SHG-active material found in vanadium tellurite systems. • Ba{sub 2}V{sub 4}O{sub 8}(Te{sub 3}O{sub 10}) (2) exhibits a novel three-dimensional [V{sub 4}O{sub 8}(Te{sub 3}O{sub 10

Carbon dioxide triggered metal(loid) mobilisation in a mofette

DEFF Research Database (Denmark)

Beulig, Felix

2014-01-01

Carbon capture and geologic storage is a frequently discussed option to reduce atmospheric CO2 concentrations with the long-term risk of leakage from storage sites to overlying aquifers and soils. We chose natural CO2 exhalations, so-called mofettes, in a wetland area in the Czech Republic...... as analogues to follow the fate of metal(loid)s under CO2-saturated conditions. Compared to the reference fluvisol at the study site, mofette soils exhibited lower pH (4.9 ± 0.05) and redox potential (300 ± 40 mV), as well as higher organic carbon contents. Poorly crystalline and crystalline Fe (hydr...... to complexation and/or adsorption to organic carbon and the small amount of Fe (hydr)oxides. A one-month-in-situ mobilisation experiment showed mobilisation of all investigated elements to the aqueous phase suggesting that desorption is the faster and initially dominating process while resorption is a secondary...

Behaviour of metalloids and metals from highly polluted soil samples when mobilized by water--evaluation of static versus dynamic leaching.

Science.gov (United States)

Wennrich, Rainer; Daus, Birgit; Müller, Karsten; Stärk, Hans-Joachim; Brüggemann, Lutz; Morgenstern, Peter

2012-06-01

The mobilization behaviour of metalloids and metals when leached by water from highly polluted soil/sediment samples was studied using static and dynamic approaches employing batch methodology and rotating coiled columns (RCC), respectively. Increasing the solution-to-solid ratios during batch leaching resulted in different enhanced mobilization rates, which are element-specific and matrix-specific. When dynamic leaching is employed with continuous replacement of the eluent, a higher portion is mobilized than when using batch elution with an identical solid-to-water ratio. Using RCC the time-resolved leaching of the elements was monitored to demonstrate the leaching patterns. For the majority of elements a significant decrease could be shown in the mobilized portion of the elements with ongoing leaching process. The data were discussed targeted at solid liquid partitioning coefficients of the metal(loid)s. The capabilities in application of K(d) values was demonstrated for dynamic leaching which is relevant for environmental processes. Copyright © 2012 Elsevier Ltd. All rights reserved.

Investigations on structural and optical behavior of Er3+ doped lead boro-tellurite glasses

Science.gov (United States)

Karthikeyan, P.; Suthanthirakumar, P.; Vijayakumar, R.; Marimuthu, K.

2015-06-01

Er3+ doped lead boro-tellurite glasses with the chemical composition (30-x)B2O3+30TeO2+23MgO+17PbF2+xEr2O3 (where x=0.05, 0.25, 0.5, and 1 in wt%) were synthesized by melt quenching technique. The structural and optical behaviors have been investigated through FTIR, absorption and emission spectral analysis. The UV-vis- NIR absorption spectra were used to calculate the bonding parameters (β ¯, δ), Judd-Ofelt intensity parameters (Ωλ, λ = 2, 4 and 6), Optical band gap and Urbach's energy of the prepared glasses. The radiative properties such as transition probability (AR), stimulated emission cross-section (σPE ), branching ratios (βR) were calculated from the luminescence spectra. The optical properties of the prepared glasses with varying Er3+ ion concentration have been studied and reported in the present work.

Metal and metalloid removal in constructed wetlands, with emphasis on the importance of plants and standardized measurements: A review

International Nuclear Information System (INIS)

Marchand, L.; Mench, M.; Jacob, D.L.; Otte, M.L.

2010-01-01

This review integrates knowledge on the removal of metals and metalloids from contaminated waters in constructed wetlands and offers insight into future R and D priorities. Metal removal processes in wetlands are described. Based on 21 papers, the roles and impacts on efficiency of plants in constructed wetlands are discussed. The effects of plant ecotypes and class (monocots, dicots) and of system size on metal removal are addressed. Metal removal rates in wetlands depend on the type of element (Hg > Mn > Fe = Cd > Pb = Cr > Zn = Cu > Al > Ni > As), their ionic forms, substrate conditions, season, and plant species. Standardized procedures and data are lacking for efficiently comparing properties of plants and substrates. We propose a new index, the relative treatment efficiency index (RTEI), to quantify treatment impacts on metal removal in constructed wetlands. Further research is needed on key components, such as effects of differences in plant ecotypes and microbial communities, in order to enhance metal removal efficiency. - A new index, the relative treatment efficiency index (RTEI), to quantify treatment impacts on metal and metalloid removal in constructed wetlands.

Prominent spectral features of Sm3+ ion in disordered zinc tellurite glass

Directory of Open Access Journals (Sweden)

Y.A. Tanko

Full Text Available Trivalent rare earth doped glasses with modified spectroscopic features are essential for solid state lasers and diverse photonic applications. Glass composition optimisation may fulfil such demand. Stimulating the spectral properties of samarium (Sm3+ ions in tellurite glass host with desired enhancement is the key issue. Glasses with composition (80 − xTeO2–20ZnO–(xSm2O3, where 0 ⩽ x ⩽ 1.5 mol% are prepared using melt quenching method. The role of varying Sm3+ contents to improving the absorption and emission properties of the prepared glasses are determined. XRD pattern verifies amorphous nature of synthesised glasses. FTIR spectroscopy has been used to observe the structural modification of (TeO4 trigonal bipyramid structural units. DTA traces display prominent transition peaks for glass transition, crystallisation and melting temperature. Samples are discerned to be stable with desired Hruby parameter and superior glass forming ability. The UV–Vis–NIR absorption spectra reveals nine peaks centred at 470, 548, 947, 1085, 1238, 1385, 1492, 1550 and 1589 nm. These bands arise due to 6H5/2 → 4I11/2, 4G5/2, 6F11/2, 6F9/2, 6F7/2, 6F5/2, 6F3/2, 6H15/2 and 6F1/2 transitions, respectively. The direct, indirect band gap and Urbach energy calculated from the absorption edge of UV–Vis–NIR spectra are found to appear within (2.75–3.18 eV, (3.22–3.40 eV, and (0.20–0.31 eV, respectively. The observed increase in refractive index from 2.45 to 2.47 is ascribed to the generation of non-bridging oxygen atoms via the conversion of TeO4 into TeO3 units. Conversely the decrease in refractive index to 2.39 is attributed to the lower ionic radii (1.079 Å of Sm3+. PL spectra under the excitation of 452 nm display four emission bands centred at 563, 600, 644 and 705 nm corresponding to 4G5/2 → 6H5/2, 6H7/2, 6H9/2 and 6H11/2 transitions of samarium ions. Excellent features of the results nominate these compositions

Infrequent blue and green emission transitions from Eu3+ in heavy metal tellurite glasses with low phonon energy

International Nuclear Information System (INIS)

Lin, H.; Tanabe, S.; Lin, L.; Yang, D.L.; Liu, K.; Wong, W.H.; Yu, J.Y.; Pun, E.Y.B.

2006-01-01

Eu 3+ doped alkali-barium-bismuth-tellurite (Eu 3+ :LKBBT) glasses were prepared by conventional melt quenching. Twelve emission bands including infrequent blue and green bands are observed and they almost cover whole visible spectral region under violet light radiation. The blue and green emissions of Eu 3+ rarely appeared in oxide glasses before, but they have been clearly recorded in Eu 3+ :LKBBT glasses even in the case of high concentration doping of Eu 3+ . The analysis based on spontaneous-radiative rate, energy gap and Raman scattering reveals that the obtaining of the abundant multichannel emissions of Eu 3+ is due to the higher refractive index and the lower phonon energy in LKBBT glass system

Effect of concentration on the photoluminescence properties of Sm3+ and Dy3+: cadmium lithium boro tellurite glasses.

Science.gov (United States)

Raju, K Vemasevana; Sailaja, S; Reddy, M Bhushana; Giridhar, P; Raju, C Nageswara; Reddy, B Sudhakar

2012-02-01

Rare-earth (Sm3+ or Dy3+) ions doped cadmium lithium boro tellurite glasses have been prepared by melt quenching method for their spectral studies. From X-ray diffraction (XRD) patterns the glass amorphous nature has been confirmed. Vis-NIR absorption, excitation and emission spectra of these glasses have been analyzed systematically and also rare earth ion concentration is optimised Sm3+: CLiBT glasses have shown strong orange-reddish emission at 598 nm (4G5/2-->6H7/2) with an excitation wavelength lambda(exci) = 401 nm and Dy3+: CLiBT glasses have shown strong yellow emission at 574 nm (6F9/2-->6H13/2) with lambda(exci) = 451 nm.

Monitoring and assessment of heavy metal/metalloid concentration by inductively coupled plasma mass spectroscopy (ICP-MS) method in Gonyeli Lake, Cyprus.

Science.gov (United States)

Alkas, Fehmi Burak; Shaban, Jehad Abdullah; Sukuroglu, Ayca Aktas; Kurt, Mehmet Ali; Battal, Dilek; Saygi, Sahan

2017-09-22

The presence of heavy metals/metalloids in the ecosystem has been an increasing ecological and global public health concern due to their potential to cause adverse health effects. For this reason, the accumulation of some heavy metals such as Cr, Mn, Ni, Cu, As, Cd, Pb was assessed by way of ICP-MS in water, sediment and fish (Cyprinus carpio) sampled from Gonyeli Lake, North Cyprus. The results showed that these metals/metalloids are found widespread throughout the study area. In water, most concentrated element was manganese with 92.1 ppb and least concentrated was lead with 0.914 ppb. In sediment, copper had the highest concentration with 613 ppm, and cadmium the lowest with 1.57 ppm. In fish tissues (muscle and gills), the most concentrated element was manganese with 12.5 ppm and the least concentrated cadmium with 0.017 ppm. These results indicate that future remediation efforts are indispensable for the rehabilitation of the lake.

YCu(TeO32(NO3(H2O3: a novel layered tellurite

Directory of Open Access Journals (Sweden)

Stuart J. Mills

2016-08-01

Full Text Available A new hydrated yttrium copper tellurite nitrate, yttrium(III copper(II bis[trioxidotellurate(IV] nitrate trihydrate, has been synthesized hydrothermally in a Teflon-lined autoclave and structurally determined using synchrotron radiation. The new phase is the first example containing yttrium, copper and tellurium in one structure. Its crystal structure is unique, with relatively strongly bound layers extending parallel to (020, defined by YO8, CuO4 and TeO3 polyhedra, while the NO3− anions and one third of the water molecules lie between those layers. The structural unit consists of [Cu2(TeO34]4− loop-branched chains of {Cu...Te...Cu...Te} squares running parallel to [001], which are linked further into layers only through Y(O,H2O8 polyhedra. Weak `secondary' Te bonds and O—H...O hydrogen-bonding interactions, involving water molecules and layer O atoms, link the layers and interlayer species. IR spectroscopic data are also presented.

Determination and evaluation of the metals and metalloids in the Chapeu-de-couro (Echinodorus macrophyllus (Kunth) Micheli).

Science.gov (United States)

Barbosa, Uenderson Araujo; dos Santos, Ivanice Ferreira; dos Santos, Ana Maria Pinto; dos Santos, Debora Correia; da Costa, Grenivel Mota

2013-09-01

The Chapeu-de-couro (Echinodorus macrophyllus (Kunth) Micheli) is a native plant from Brazil, which has been mainly used in medicinal application being a potent antirheumatic and diuretic, in the production of soft drinks, and also in the ornamentation of aquariums. In this paper, the metals and metalloids for the leaves of chapeu-de-couro collected in the Paraguacu River from the city Cachoeira, Bahia State, Brazil, was determined and evaluated using multivariate analysis. The samples were digested using nitric acid and hydrogen peroxide and were analyzed using inductively coupled plasma mass spectrometry. The accuracy of the method was confirmed by analysis of a certified reference material of apple leaves, furnished by National Institute of Standard and Technology. The study involved 15 samples of the Paraguacu River. The results expressed as milligrams of element per kilogram of sample demonstrated that the concentration ranges varied: 1.39-5.27 for chromium, 44.85-165.39 for manganese, 0.55-0.84 for arsenic, 0.01-3.94 for antimony, and 0.18-0.31 for lead. The principal component analysis and hierarchical cluster analysis evidenced that the concentrations of the metals and metalloids varied according with the variations in the water of the Paraguacu.

EFFECTS OF SILICON ON ALLEVIATING ARSENIC TOXICITY IN MAIZE PLANTS

Directory of Open Access Journals (Sweden)

Airon José da Silva

2015-02-01

Full Text Available Arsenic is a metalloid highly toxic to plants and animals, causing reduced plant growth and various health problems for humans and animals. Silicon, however, has excelled in alleviating stress caused by toxic elements in plants. The aim of this study was to investigate the effects of Si in alleviating As stress in maize plants grown in a nutrient solution and evaluate the potential of the spectral emission parameters and the red fluorescence (Fr and far-red fluorescence (FFr ratio obtained in analysis of chlorophyll fluorescence in determination of this interaction. An experiment was carried out in a nutrient solution containing a toxic rate of As (68 μmol L-1 and six increasing rates of Si (0, 0.25, 0.5, 1.0, 1.5, and 2.0 mmol L-1. Dry matter production and concentrations of As, Si, and photosynthetic pigments were then evaluated. Chlorophyll fluorescence was also measured throughout plant growth. Si has positive effects in alleviating As stress in maize plants, evidenced by the increase in photosynthetic pigments. Silicon application resulted in higher As levels in plant tissue; therefore, using Si for soil phytoremediation may be a promising choice. Chlorophyll fluorescence analysis proved to be a sensitive tool, and it can be successfully used in the study of the ameliorating effects of Si in plant protection, with the Fr/FFr ratio as the variable recommended for identification of temporal changes in plants.

Comparative proteomic analysis reveals heart toxicity induced by chronic arsenic exposure in rats

DEFF Research Database (Denmark)

Huang, Qingyu; Xi, Guochen; Alamdar, Ambreen

2017-01-01

Arsenic is a widespread metalloid in the environment, which poses a broad spectrum of adverse effects on human health. However, a global view of arsenic-induced heart toxicity is still lacking, and the underlying molecular mechanisms remain unclear. By performing a comparative quantitative...... proteomic analysis, the present study aims to investigate the alterations of proteome profile in rat heart after long-term exposure to arsenic. As a result, we found that the abundance of 81 proteins were significantly altered by arsenic treatment (35 up-regulated and 46 down-regulated). Among these, 33...... proteins were specifically associated with cardiovascular system development and function, including heart development, heart morphology, cardiac contraction and dilation, and other cardiovascular functions. It is further proposed that the aberrant regulation of 14 proteins induced by arsenic would disturb...

Single- and double energy N{sup +} ion irradiated planar optical waveguides in Er: Tungsten–tellurite oxide glass and sillenite type Bismuth Germanate crystals working up to telecommunications wavelengths

Energy Technology Data Exchange (ETDEWEB)

Bányász, I., E-mail: banyasz@sunserv.kfki.hu [Department of Crystal Physics, Wigner Research Centre for Physics, Hungarian Academy of Sciences, P.O. Box 49, H-1525 Budapest (Hungary); Zolnai, Z.; Fried, M.; Lohner, T. [Research Institute for Technical Physics and Materials Science, Research Centre for Natural Sciences, Hungarian Academy of Sciences, P.O. Box 49, H-1525 Budapest (Hungary); Berneschi, S.; Righini, G.C. [MDF-Lab, “Nello Carrara” Institute of Applied Physics, IFAC-CNR, Via Madonna del Piano 10, 50019 Sesto Fiorentino (Italy); “Enrico Fermi” Center for Study and Research, Piazza del Viminale 2, 00184 Roma (Italy); Pelli, S.; Nunzi-Conti, G. [MDF-Lab, “Nello Carrara” Institute of Applied Physics, IFAC-CNR, Via Madonna del Piano 10, 50019 Sesto Fiorentino (Italy)

2013-07-15

Ion implantation proved to be a universal technique for producing waveguides in most optical materials. Tellurite glasses are good hosts of rare-earth elements for the development of fibre and integrated optical amplifiers and lasers covering all the main telecommunication bands. Er{sup 3+}-doped tellurite glasses are good candidates for the fabrication of broadband amplifiers in wavelength division multiplexing around 1.55 μm, as they exhibit large stimulated cross sections and broad emission bandwidth. Fabrication of channel waveguides in such a material via N{sup +} ion implantation was reported recently. Sillenite type Bismuth Germanate (BGO) crystals are good nonlinear optical materials. Parameters of waveguide fabrication in both materials via implantation of MeV-energy N{sup +} ions were optimized. First single-energy implantations at 3.5 MeV at various fluences were applied. Waveguide operation up to 1.5 μm was observed in both materials. Then double-energy implantations at a fixed upper energy of 3.5 MeV and lower energies between 2.5 and 3.1 MeV were performed to suppress leaky modes by increasing barrier width. Improvement of waveguide characteristics was found by m-line spectroscopy and spectroscopic ellipsometry.

Tellurites of hexavalent uranium: first observation of polymerized (UO{sub 4}){sup 2-} tetraoxido cores

Energy Technology Data Exchange (ETDEWEB)

Zadoya, Anastasiya I.; Siidra, Oleg I.; Nazarchuk, Evgeny V.; Bocharov, Sergey N. [Department of Crystallography, St. Petersburg State University (Russian Federation); Bubnova, Rimma S. [Department of Crystallography, St. Petersburg State University (Russian Federation); Institute of Silicate Chemistry, Russian Academy of Sciences, St. Petersburg (Russian Federation)

2016-09-15

Two novel Ca{sub 2}(UO{sub 3})(TeO{sub 3}){sub 2} (1) and K{sub 2}(UO{sub 2}){sub 2}O{sub 2}(TeO{sub 3}) (2) uranyl tellurites were obtained from telluric acid, used as a starting reagent for both compounds. In 1, the tetraoxido core is coordinated by TeO{sub 3} groups and UO{sub 4} squares polymerize into [UO{sub 3}] chains. The tetraoxido core coordination modes in compound 1 are unique. New layered {sub ∞}{sup 2}[(UO{sub 2}){sub 2}(TeO{sub 3})O{sub 2}]{sup 2-} topology is observed for 2. Both of the compounds were studied by the means of high-temperature X-ray diffraction. The thermal decomposition of 1 and 2 is different and leads to formation of uranate compounds. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Facultative hyperaccumulation of heavy metals and metalloids.

Science.gov (United States)

Pollard, A Joseph; Reeves, Roger D; Baker, Alan J M

2014-03-01

Approximately 500 species of plants are known to hyperaccumulate heavy metals and metalloids. The majority are obligate metallophytes, species that are restricted to metalliferous soils. However, a smaller but increasing list of plants are "facultative hyperaccumulators" that hyperaccumulate heavy metals when occurring on metalliferous soils, yet also occur commonly on normal, non-metalliferous soils. This paper reviews the biology of facultative hyperaccumulators and the opportunities they provide for ecological and evolutionary research. The existence of facultative hyperaccumulator populations across a wide edaphic range allows intraspecific comparisons of tolerance and uptake physiology. This approach has been used to study zinc and cadmium hyperaccumulation by Noccaea (Thlaspi) caerulescens and Arabidopsis halleri, and it will be instructive to make similar comparisons on species that are distributed even more abundantly on normal soil. Over 90% of known hyperaccumulators occur on serpentine (ultramafic) soil and accumulate nickel, yet there have paradoxically been few experimental studies of facultative nickel hyperaccumulation. Several hypotheses suggested to explain the evolution of hyperaccumulation seem unlikely when most populations of a species occur on normal soil, where plants cannot hyperaccumulate due to low metal availability. In such species, it may be that hyperaccumulation is an ancestral phylogenetic trait or an anomalous manifestation of physiological mechanisms evolved on normal soils, and may or may not have direct adaptive benefits. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Evaluation of shielding parameters for heavy metal fluoride based tellurite-rich glasses for gamma ray shielding applications

Science.gov (United States)

Sayyed, M. I.; Lakshminarayana, G.; Kityk, I. V.; Mahdi, M. A.

2017-10-01

In this work, we have evaluated the γ-ray shielding parameters such as mass attenuation coefficient (μ/ρ), effective atomic number (Zeff), half value layer (HVL), mean free path (MFP) and exposure buildup factors (EBF) for heavy metal fluoride (PbF2) based tellurite-rich glasses. In addition, neutron total macroscopic cross sections (∑R) for these glasses were also calculated. The maximum value for μ/ρ, Zeff and ∑R was found for heavy metal (Bi2O3) oxide introduced glass. The results of the selected glasses have been compared, in terms of MFP with different glass systems. The shielding effectiveness of the selected glasses is found comparable or better than of common ones, which indicates that these glasses with suitable oxides could be developed for gamma ray shielding applications.

Health concerns of heavy metals and metalloids.

Science.gov (United States)

Cooksey, Chris

2012-01-01

There is a long history and an overwhelming amount of data on the toxicity of heavy metal compounds. Here a brief look is taken of some aspects of the toxicity of lead, cadmium, mercury and arsenic, chosen for their historical importance and environmental significance, highlighting especially the contrast between the acute and chronic toxicity of purely inorganic species and their organic derivatives. For further details of other toxic metal compounds, the reader might like to consult "Elements of murder: a history of poison" by John Emsley (2005, Oxford University Press).

Distributions, sources and pollution status of 17 trace metal/metalloids in the street dust of a heavily industrialized city of central China.

Science.gov (United States)

Li, Zhonggen; Feng, Xinbin; Li, Guanghui; Bi, Xiangyang; Zhu, Jianming; Qin, Haibo; Dai, Zhihui; Liu, Jinling; Li, Qiuhua; Sun, Guangyi

2013-11-01

A series of representative street dust samples were collected from a heavily industrialized city, Zhuzhou, in central China, with the aim to investigate the spatial distribution and pollution status of 17 trace metal/metalloid elements. Concentrations of twelve elements (Pb, Zn, Cu, Cd, Hg, As, Sb, In, Bi, Tl, Ag and Ga) were distinctly amplified by atmospheric deposition resulting from a large scale Pb/Zn smelter located in the northwest fringe of the city, and followed a declining trend towards the city center. Three metals (W, Mo and Co) were enriched in samples very close to a hard alloy manufacturing plant, while Ni and Cr appeared to derive predominantly from natural sources. Other industries and traffic had neglectable effects on the accumulation of observed elements. Cd, In, Zn, Ag and Pb were the five metal/metalloids with highest pollution levels and the northwestern part of city is especially affected by heavy metal pollution. Copyright © 2013 Elsevier Ltd. All rights reserved.

Imprinted Genes and the Environment: Links to the Toxic Metals Arsenic, Cadmium and Lead

Science.gov (United States)

Smeester, Lisa; Yosim, Andrew E.; Nye, Monica D.; Hoyo, Cathrine; Murphy, Susan K.; Fry, Rebecca C.

2014-01-01

Imprinted genes defy rules of Mendelian genetics with their expression tied to the parent from whom each allele was inherited. They are known to play a role in various diseases/disorders including fetal growth disruption, lower birth weight, obesity, and cancer. There is increasing interest in understanding their influence on environmentally-induced disease. The environment can be thought of broadly as including chemicals present in air, water and soil, as well as food. According to the Agency for Toxic Substances and Disease Registry (ATSDR), some of the highest ranking environmental chemicals of concern include metals/metalloids such as arsenic, cadmium, and lead. The complex relationships between toxic metal exposure, imprinted gene regulation/expression and health outcomes are understudied. Herein we examine trends in imprinted gene biology, including an assessment of the imprinted genes and their known functional roles in the cell, particularly as they relate to toxic metals exposure and disease. The data highlight that many of the imprinted genes have known associations to developmental diseases and are enriched for their role in the TP53 and AhR pathways. Assessment of the promoter regions of the imprinted genes resulted in the identification of an enrichment of binding sites for two transcription factor families, namely the zinc finger family II and PLAG transcription factors. Taken together these data contribute insight into the complex relationships between toxic metals in the environment and imprinted gene biology. PMID:24921406

Imprinted Genes and the Environment: Links to the Toxic Metals Arsenic, Cadmium and Lead

Directory of Open Access Journals (Sweden)

Lisa Smeester

2014-06-01

Full Text Available Imprinted genes defy rules of Mendelian genetics with their expression tied to the parent from whom each allele was inherited. They are known to play a role in various diseases/disorders including fetal growth disruption, lower birth weight, obesity, and cancer. There is increasing interest in understanding their influence on environmentally-induced disease. The environment can be thought of broadly as including chemicals present in air, water and soil, as well as food. According to the Agency for Toxic Substances and Disease Registry (ATSDR, some of the highest ranking environmental chemicals of concern include metals/metalloids such as arsenic, cadmium, lead and mercury. The complex relationships between toxic metal exposure, imprinted gene regulation/expression and health outcomes are understudied. Herein we examine trends in imprinted gene biology, including an assessment of the imprinted genes and their known functional roles in the cell, particularly as they relate to toxic metals exposure and disease. The data highlight that many of the imprinted genes have known associations to developmental diseases and are enriched for their role in the TP53 and AhR pathways. Assessment of the promoter regions of the imprinted genes resulted in the identification of an enrichment of binding sites for two transcription factor families, namely the zinc finger family II and PLAG transcription factors. Taken together these data contribute insight into the complex relationships between toxic metals in the environment and imprinted gene biology.

Uptake of metals and metalloids by Conyza canadensis L. from a thermoelectric power plant landfill

Directory of Open Access Journals (Sweden)

Vukojević Vesna

2016-01-01

Full Text Available Fourteen metals and metalloids were determined in Conyza canadensis L. harvested from the fly ash landfill of the thermoelectric power plant “Kolubara” (Serbia. Fly ash samples were collected together with the plant samples and subjected to sequential extraction according to the three-step sequential extraction scheme proposed by the Community Bureau of Reference (BCR; now the Standards, Measurements and Testing Program. The contents of metals and metalloids were determined by inductively coupled plasma optical emission spectrometry (ICP-OES in plant root and the aboveground part and correlated with their contents in the fly ash samples. The bioconcentration factor (BCF and translocation factors (TF were calculated to access uptake of metals from fly ash and their translocation to the aboveground part. Results regarding As revealed that fly ash samples in the proximity of the active cassette had higher amounts of the element. Principal component analysis (PCA showed that As had no impact on the classification of plant parts. BCF for As ranged from 1.44 to 23.8 and varied, depending on the investigated area; TF for As ranged from 0.43 to 2.61, indicating that the plant translocated As from root to shoot. In addition to As, Conyza canadensis L. exhibited efficient uptake of other metals from fly ash. According to the calculated BCF and TF, the plant retained Al, Fe and Cr in the root and translocated Zn, Cd, Cu and As from root to shoot in the course of the detoxifying process. [Projekat Ministarstva nauke Republike Srbije, br. 172030 i br. 172017

Influence of environmental parameters and of their interactions on the release of metal(loid)s from a construction material in hydraulic engineering

International Nuclear Information System (INIS)

Schmukat, A.; Duester, L.; Goryunova, E.; Ecker, D.; Heininger, P.; Ternes, T.A.

2016-01-01

Highlights: • DoE supported multi-factorial study on the metal(loid) release from copper slag. • Interactions of four parameters were studied and weighted. • An effective separation method between slag and sediment was established. • The metal(loid) partitioning between sediment, slag and eluent is described. • The knowledge on the potential environmental impact of copper slag is increased. - Abstract: Besides the leaching behaviour of a construction material under standardised test-specific conditions with laboratory water, for some construction materials it is advisable to test their environmental behaviour also under close to end use conditions. The envisaged end use combined with the product characteristics (e.g. mineral phases) is decisive for the choice of environmental factors that may change the release of substance that potentially cause adverse environmental effects (e.g. fertilisation or ecotoxicity). At the moment an experimental link is missing between mono-factorial standardised test systems and non standardised complex incubation experiments such as mesocosms which are closer to environmental conditions. Multi-factorial batch experiments may have the potential to close the gap. To verify this, batch experiments with copper slag were performed which is used as armour stones in hydraulic engineering. Design of experiments (DoE) was applied to evaluate the impact of pH, ionic strength, temperature and sediment content on the release of As, Cu, Mo, Ni, Pb, Sb and Zn. The study shows that release and sediment-eluent partitioning of metal(loid)s are impacted by interactions between the studied factors. Under the prevalent test conditions sediment acts as a sink enhancing most strongly the release of elements from the material.

Influence of environmental parameters and of their interactions on the release of metal(loid)s from a construction material in hydraulic engineering

Energy Technology Data Exchange (ETDEWEB)

Schmukat, A., E-mail: schmukat@harzwasserwerke.de [Harzwasserwerke GmbH, Zur Granetalsperre 8, 38685 Langelsheim (Germany); Federal Institute of Hydrology, Department of Aquatic Chemistry, Am Mainzer Tor 1, 56068 Koblenz (Germany); Duester, L. [Federal Institute of Hydrology, Department of Aquatic Chemistry, Am Mainzer Tor 1, 56068 Koblenz (Germany); Goryunova, E. [Federal Institute of Hydrology, Department of Aquatic Chemistry, Am Mainzer Tor 1, 56068 Koblenz (Germany); KAPP-Chemie GmbH & Co. KG, Industriestr. 2-4, 56357 Miehlen (Germany); Ecker, D.; Heininger, P.; Ternes, T.A. [Federal Institute of Hydrology, Department of Aquatic Chemistry, Am Mainzer Tor 1, 56068 Koblenz (Germany)

2016-03-05

Highlights: • DoE supported multi-factorial study on the metal(loid) release from copper slag. • Interactions of four parameters were studied and weighted. • An effective separation method between slag and sediment was established. • The metal(loid) partitioning between sediment, slag and eluent is described. • The knowledge on the potential environmental impact of copper slag is increased. - Abstract: Besides the leaching behaviour of a construction material under standardised test-specific conditions with laboratory water, for some construction materials it is advisable to test their environmental behaviour also under close to end use conditions. The envisaged end use combined with the product characteristics (e.g. mineral phases) is decisive for the choice of environmental factors that may change the release of substance that potentially cause adverse environmental effects (e.g. fertilisation or ecotoxicity). At the moment an experimental link is missing between mono-factorial standardised test systems and non standardised complex incubation experiments such as mesocosms which are closer to environmental conditions. Multi-factorial batch experiments may have the potential to close the gap. To verify this, batch experiments with copper slag were performed which is used as armour stones in hydraulic engineering. Design of experiments (DoE) was applied to evaluate the impact of pH, ionic strength, temperature and sediment content on the release of As, Cu, Mo, Ni, Pb, Sb and Zn. The study shows that release and sediment-eluent partitioning of metal(loid)s are impacted by interactions between the studied factors. Under the prevalent test conditions sediment acts as a sink enhancing most strongly the release of elements from the material.

Judd-Ofelt analysis and improvement of thermal and optical properties of tellurite glasses by adding P{sub 2}O{sub 5}

Energy Technology Data Exchange (ETDEWEB)

Jlassi, I. [Laboratoire de Physico-Chimie des Materiaux Mineraux et leurs Applications, Centre National de Recherches en Sciences des Materiaux, B.P. 95, Hammam-Lif 2050 (Tunisia); Elhouichet, H., E-mail: habib.elhouichet@fst.rnu.t [Laboratoire de Physico-Chimie des Materiaux Mineraux et leurs Applications, Centre National de Recherches en Sciences des Materiaux, B.P. 95, Hammam-Lif 2050 (Tunisia); Departement de Physique, Faculte des Sciences de Tunis, Campus ElManar 2092 (Tunisia); Ferid, M. [Laboratoire de Physico-Chimie des Materiaux Mineraux et leurs Applications, Centre National de Recherches en Sciences des Materiaux, B.P. 95, Hammam-Lif 2050 (Tunisia); Barthou, C. [Institut des Nanosciences de Paris, Universite P. et M. Curie, Centre Nationale de la Recherche Scientifique, UMR-7588, Campus Boucicaut, 140 rue de Lourmel, 75015 Paris (France)

2010-12-15

Er{sup 3+} and Er{sup 3+}/Yb{sup 3+} co-doped tellurite glasses, suitable for developing optical fiber laser and amplifier, have been elaborated from the conventional melt-quenching method. Results of differential scanning calorimetry (DSC) measurements indicate a good thermal stability of tellurite glasses. The DSC measurements show an improvement of thermal stability of glass hosts after adding P{sub 2}O{sub 5}. Absorption spectrum from near infrared to visible was obtained and the Judd-Ofelt (J-O) intensity parameters ({Omega}{sub 2}, {Omega}{sub 4}, and {Omega}{sub 6}) were determined. Spontaneous emission probabilities of some relevant transitions, branching ratio, and radiative lifetimes of several excited states of Er{sup 3+} have been predicted using intensity J-O parameters. Absorption cross-section and calculated emission cross-section, using the McCumber method, for the {sup 4}I{sub 13/2{yields}}{sup 4}I{sub 15/2} transition, were determined and compared for the doped and co-doped glasses. Energy transfer (ET) and effect of changing concentration of P{sub 2}O{sub 5} and Yb{sup 3+} ions on spectroscopic properties were investigated. It was found that the addition of P{sub 2}O{sub 5} can increase the symmetry of the Er{sup 3+} ion. As a consequence, PL lifetime becomes more longer. The spectroscopic properties and the efficient infrared luminescence indicate that Er{sup 3+} doped TeO{sub 2}-ZnO-Na{sub 2}O-Er{sub 2}O{sub 3}(TZNE) is a promising laser and amplifier materials and may be a potentially useful material for developing upconversion fiber optical devices.

Imprinted genes and the environment: links to the toxic metals arsenic, cadmium, lead and mercury.

Science.gov (United States)

Smeester, Lisa; Yosim, Andrew E; Nye, Monica D; Hoyo, Cathrine; Murphy, Susan K; Fry, Rebecca C

2014-06-11

Imprinted genes defy rules of Mendelian genetics with their expression tied to the parent from whom each allele was inherited. They are known to play a role in various diseases/disorders including fetal growth disruption, lower birth weight, obesity, and cancer. There is increasing interest in understanding their influence on environmentally-induced disease. The environment can be thought of broadly as including chemicals present in air, water and soil, as well as food. According to the Agency for Toxic Substances and Disease Registry (ATSDR), some of the highest ranking environmental chemicals of concern include metals/metalloids such as arsenic, cadmium, lead and mercury. The complex relationships between toxic metal exposure, imprinted gene regulation/expression and health outcomes are understudied. Herein we examine trends in imprinted gene biology, including an assessment of the imprinted genes and their known functional roles in the cell, particularly as they relate to toxic metals exposure and disease. The data highlight that many of the imprinted genes have known associations to developmental diseases and are enriched for their role in the TP53 and AhR pathways. Assessment of the promoter regions of the imprinted genes resulted in the identification of an enrichment of binding sites for two transcription factor families, namely the zinc finger family II and PLAG transcription factors. Taken together these data contribute insight into the complex relationships between toxic metals in the environment and imprinted gene biology.

Metal and metalloid foliar uptake by various plant species exposed to atmospheric industrial fallout: Mechanisms involved for lead

Energy Technology Data Exchange (ETDEWEB)

Schreck, E., E-mail: eva.schreck@ensat.fr [Universite de Toulouse (France); INP, UPS (France); EcoLab (Laboratoire Ecologie Fonctionnelle et Environnement) (France); ENSAT, Avenue de l' Agrobiopole, 31326 Castanet Tolosan (France); CNRS (France); EcoLab, 31326 Castanet Tolosan (France); Foucault, Y. [Universite de Toulouse (France); INP, UPS (France); EcoLab (Laboratoire Ecologie Fonctionnelle et Environnement) (France); ENSAT, Avenue de l' Agrobiopole, 31326 Castanet Tolosan (France); CNRS (France); EcoLab, 31326 Castanet Tolosan (France); STCM, Societe de Traitements Chimiques des Metaux, 30 Avenue de Fondeyre 31200 Toulouse (France); Sarret, G. [ISTerre (UMR 5275), Universite J. Fourier and CNRS, BP 53, 38041 Grenoble cedex 9 (France); Sobanska, S. [LASIR (UMR CNRS 8516), Universite de Lille 1, Bat. C5, 59655 Villeneuve d' Ascq cedex (France); Cecillon, L. [ISTerre (UMR 5275), Universite J. Fourier and CNRS, BP 53, 38041 Grenoble cedex 9 (France); Castrec-Rouelle, M. [Universite Pierre and Marie Curie (UPMC-Paris 6), Bioemco (Biogeochimie et Ecologie des Milieux Continentaux), Site Jussieu, Tour 56, 4 Place Jussieu, 75252 Paris cedex 05 (France); Uzu, G. [Laboratoire d' Aerologie (UMR 5560), OMP, UPS 14, Avenue Edouard Belin, 31400 Toulouse (France); GET (UMR 5563), IRD, 14, Avenue Edouard Belin, 31400 Toulouse (France); Dumat, C. [Universite de Toulouse (France); INP, UPS (France); EcoLab (Laboratoire Ecologie Fonctionnelle et Environnement) (France); ENSAT, Avenue de l' Agrobiopole, 31326 Castanet Tolosan (France); CNRS (France); EcoLab, 31326 Castanet Tolosan (France)

2012-06-15

Fine and ultrafine metallic particulate matters (PMs) are emitted from metallurgic activities in peri-urban zones into the atmosphere and can be deposited in terrestrial ecosystems. The foliar transfer of metals and metalloids and their fate in plant leaves remain unclear, although this way of penetration may be a major contributor to the transfer of metals into plants. This study focused on the foliar uptake of various metals and metalloids from enriched PM (Cu, Zn, Cd, Sn, Sb, As, and especially lead (Pb)) resulting from the emissions of a battery-recycling factory. Metal and metalloid foliar uptake by various vegetable species, exhibiting different morphologies, use (food or fodder) and life-cycle (lettuce, parsley and rye-grass) were studied. The mechanisms involved in foliar metal transfer from atmospheric particulate matter fallout, using lead (Pb) as a model element was also investigated. Several complementary techniques (micro-X-ray fluorescence, scanning electron microscopy coupled with energy dispersive X-ray microanalysis and time-of-flight secondary ion mass spectrometry) were used to investigate the localization and the speciation of lead in their edible parts, i.e. leaves. The results showed lead-enriched PM on the surface of plant leaves. Biogeochemical transformations occurred on the leaf surfaces with the formation of lead secondary species (PbCO{sub 3} and organic Pb). Some compounds were internalized in their primary form (PbSO{sub 4}) underneath an organic layer. Internalization through the cuticle or penetration through stomata openings are proposed as two major mechanisms involved in foliar uptake of particulate matter. - Graphical abstract: Overall picture of performed observations and mechanisms potentially involved in lead foliar uptake. Highlights: Black-Right-Pointing-Pointer Foliar uptake of metallic particulate matter (PM) is of environmental and health concerns. Black-Right-Pointing-Pointer The leaf morphology influences the adsorption

Enhanced green upconversion by controlled ceramization of Er3+–Yb3+ co-doped sodium niobium tellurite glass–ceramics for low temperature sensors

International Nuclear Information System (INIS)

Suresh Kumar, J.; Pavani, K.; Graça, M.P.F.; Soares, M.J.

2014-01-01

Highlights: • Upconversion luminescence improved in glass–ceramics compared to host glass. • Judd–Ofelt and radiative parameters calculated. • NIR decay curve results concur the results of improved luminescence. • Temperature dependent upconversion support the use of materials for sensors. - Abstract: Tellurite based glasses are well-known for their upconversion properties besides having a disadvantage of low mechanical strength dragging them away from practical applications. The present work deals with preparation of sodium niobium tellurite (SNT) glasses using melt quenching method, in which small quantities of boron and silicon in the form of oxides are added to improve their mechanical properties. Controlled heat treatment is performed to ceramize the prepared glasses based on the thermal data given by DTA. XRD and SEM profiles of the glass–ceramics which confirmed the formation of crystalline monoclinic Sodium Tellurium Niobium Oxide (Na 1.4 Nb 3 Te 4.9 O 18 ) phase (JCPDS card No. 04–011-7556). Upconversion measurements in the visible region were made for the prepared Er 3+ –Yb 3+ co-doped glasses and glass–ceramics with 980 nm laser excitation varying the laser power and concentration of Er 3+ ions. Results showed that the upconversion luminescence intensity was enhanced by ten times in SNT glass–ceramics compared to that in the SNT glasses. Decay curves give evidence of high performance of glass–ceramics compared to glasses due to ceramization and structural changes. Temperature dependent visible upconversion was performed to test the ability of efficient SNT glass–ceramic at low temperatures and variation of upconversion intensities was studied

Investigation, Pollution Mapping and Simulative Leakage Health Risk Assessment for Heavy Metals and Metalloids in Groundwater from a Typical Brownfield, Middle China.

Science.gov (United States)

Li, Fei; Qiu, Zhenzhen; Zhang, Jingdong; Liu, Wenchu; Liu, Chaoyang; Zeng, Guangming

2017-07-13

Heavy metal and metalloid (Cr, Pb, Cd, Zn, Cu, Ni, As and Hg) concentrations in groundwater from 19 typical sites throughout a typical brownfield were detected. Mean concentrations of toxic metals in groundwater decreased in the order of Cr > Zn > Cu > Cd > Ni > Pb > Hg > As. Concentration of Cr 6+ in groundwater was detected to further study chromium contamination. Cr 6+ and Cd in groundwater were recommended as the priority pollutants because they were generally 1399-fold and 12-foldgreater than permissible limits, respectively. Owing to the fact that a waterproof curtain (WPC) in the brownfield is about to pass the warranty period, a steady two-dimensional water quality model and health risk assessment were applied to simulate and evaluate adverse effects of Cr 6 + and Cd on the water quality of Xiangjiang River and the drinking-water intake of Wangcheng Waterworks. The results indicated that when groundwater in the brownfield leaked with valid curtain prevention, the water quality in Xiangjiang River and drinking-water intake downstream were temporarily unaffected. However, if there was no curtain prevention, groundwater leakage would have adverse impact on water quality of Xiangjiang River. Under the requirements of Class III surface water quality, the pollution belt for Cr 6+ was 7500 m and 200 m for Cd. The non-carcinogenic risk of toxic metals in Xiangjiang River exceeded the threshold in a limited area, but did not threaten Wangcheng Waterworks. By contrast, the carcinogenic risk area for adults was at a transverse distance of 200 m and a longitudinal distance of 18,000 m, which was close to the Wangcheng Waterworks (23,000 m). Therefore, it was essential to reconstruct the WPC in the brownfield for preventing pollution diffusion.

Investigation, Pollution Mapping and Simulative Leakage Health Risk Assessment for Heavy Metals and Metalloids in Groundwater from a Typical Brownfield, Middle China

Science.gov (United States)

Qiu, Zhenzhen; Zhang, Jingdong; Liu, Wenchu; Liu, Chaoyang; Zeng, Guangming

2017-01-01

Heavy metal and metalloid (Cr, Pb, Cd, Zn, Cu, Ni, As and Hg) concentrations in groundwater from 19 typical sites throughout a typical brownfield were detected. Mean concentrations of toxic metals in groundwater decreased in the order of Cr > Zn > Cu > Cd > Ni > Pb > Hg > As. Concentration of Cr6+ in groundwater was detected to further study chromium contamination. Cr6+ and Cd in groundwater were recommended as the priority pollutants because they were generally 1399-fold and 12-foldgreater than permissible limits, respectively. Owing to the fact that a waterproof curtain (WPC) in the brownfield is about to pass the warranty period, a steady two-dimensional water quality model and health risk assessment were applied to simulate and evaluate adverse effects of Cr6 + and Cd on the water quality of Xiangjiang River and the drinking-water intake of Wangcheng Waterworks. The results indicated that when groundwater in the brownfield leaked with valid curtain prevention, the water quality in Xiangjiang River and drinking-water intake downstream were temporarily unaffected. However, if there was no curtain prevention, groundwater leakage would have adverse impact on water quality of Xiangjiang River. Under the requirements of Class III surface water quality, the pollution belt for Cr6+ was 7500 m and 200 m for Cd. The non-carcinogenic risk of toxic metals in Xiangjiang River exceeded the threshold in a limited area, but did not threaten Wangcheng Waterworks. By contrast, the carcinogenic risk area for adults was at a transverse distance of 200 m and a longitudinal distance of 18,000 m, which was close to the Wangcheng Waterworks (23,000 m). Therefore, it was essential to reconstruct the WPC in the brownfield for preventing pollution diffusion. PMID:28703781

Heavy metals, metalloids and other hazardous elements in marine plastic litter.

Science.gov (United States)

Turner, Andrew

2016-10-15

Plastics, foams and ropes collected from beaches in SW England have been analysed for As, Ba, Br, Cd, Cl, Cr, Cu, Hg, Ni, Pb, Sb, Se, Sn and Zn by field-portable-x-ray fluorescence spectrometry. High concentrations of Cl in foams that were not PVC-based were attributed to the presence of chlorinated flame retardants. Likewise, high concentrations of Br among both foams and plastics were attributed to the presence of brominated flame retardants. Regarding heavy metals and metalloids, Cd and Pb were of greatest concern from an environmental perspective. Lead was encountered in plastics, foams and ropes and up to concentrations of 17,500μgg(-1) due to its historical use in stabilisers, colourants and catalysts in the plastics industry. Detectable Cd was restricted to plastics, where its concentration often exceeded 1000μgg(-1); its occurrence is attributed to the use of both Cd-based stabilisers and colourants in a variety of products. Copyright © 2016 Elsevier Ltd. All rights reserved.

Enhanced green and red upconversion emissions in Er3+-doped boro-tellurite glass containing gold nanoparticles

Science.gov (United States)

Dousti, M. Reza; Amjad, Raja J.; Mahraz, Zahra Ashur S.

2015-01-01

Increasing the cross-section of upconversion emissions from the rare earth ions doped materials is a challenging issue. In this work, we report on the enhancement of the up-converted emissions of Er3+-doped boro-tellurite glasses containing gold nanoparticles which have been prepared by a conventional melt-quench technique. Seven absorption bands and three emission lines are observed using the UV-Vis-IR and photoluminescence spectroscopic techniques, respectively. Red emission is enhanced up to 30 times in a sample having 1 wt% of Au nanoparticles. The presence of the gold nanoparticles with average size of ∼5.74 nm is confirmed by transmission electron microscopy and corresponding surface plasmon band is observed at 630 nm in a singly-doped Au-nanoparticles embedded glass sample. A model to determine the enhancement factor of the emissions is suggested which could not describe the phenomenon for high concentrations of nanoparticles. Enhancement is attributed to the increased local field around the metal, and the results are discussed in details.

Nanoscale zero-valent iron for metal/metalloid removal from model hydraulic fracturing wastewater.

Science.gov (United States)

Sun, Yuqing; Lei, Cheng; Khan, Eakalak; Chen, Season S; Tsang, Daniel C W; Ok, Yong Sik; Lin, Daohui; Feng, Yujie; Li, Xiang-Dong

2017-06-01

Nanoscale zero-valent iron (nZVI) was tested for the removal of Cu(II), Zn(II), Cr(VI), and As(V) in model saline wastewaters from hydraulic fracturing. Increasing ionic strength (I) from 0.35 to 4.10 M (Day-1 to Day-90 wastewaters) increased Cu(II) removal (25.4-80.0%), inhibited Zn(II) removal (58.7-42.9%), slightly increased and then reduced Cr(VI) removal (65.7-44.1%), and almost unaffected As(V) removal (66.7-75.1%) by 8-h reaction with nZVI at 1-2 g L -1 . The removal kinetics conformed to pseudo-second-order model, and increasing I decreased the surface area-normalized rate coefficient (k sa ) of Cu(II) and Cr(VI), probably because agglomeration of nZVI in saline wastewaters restricted diffusion of metal(loid)s to active surface sites. Increasing I induced severe Fe dissolution from 0.37 to 0.77% in DIW to 4.87-13.0% in Day-90 wastewater; and Fe dissolution showed a significant positive correlation with Cu(II) removal. With surface stabilization by alginate and polyvinyl alcohol, the performance of entrapped nZVI in Day-90 wastewater was improved for Zn(II) and Cr(VI), and Fe dissolution was restrained (3.20-7.36%). The X-ray spectroscopic analysis and chemical speciation modelling demonstrated that the difference in removal trends from Day-1 to Day-90 wastewaters was attributed to: (i) distinctive removal mechanisms of Cu(II) and Cr(VI) (adsorption, (co-)precipitation, and reduction), compared to Zn(II) (adsorption) and As(V) (bidentate inner-sphere complexation); and (ii) changes in solution speciation (e.g., from Zn 2+ to ZnCl 3 - and ZnCl 4 2- ; from CrO 4 2- to CaCrO 4 complex). Bare nZVI was susceptible to variations in wastewater chemistry while entrapped nZVI was more stable and environmentally benign, which could be used to remove metals/metalloids before subsequent treatment for reuse/disposal. Copyright © 2017 Elsevier Ltd. All rights reserved.

A 125Te and 23Na NMR investigation of the structure and crystallisation of sodium tellurite glasses.

Science.gov (United States)

Holland, D; Bailey, J; Ward, G; Turner, B; Tierney, P; Dupree, R

2005-01-01

125Te static nuclear magnetic resonance (NMR) and 23Na and 125Te magic angle spinning (MAS) NMR have been used, in conjunction with X-ray diffraction, to examine the structure and crystallisation behaviour of glasses of composition xNa2O.(1-x)TeO2 (0.075 x 0.4). The MAS NMR 23Na spectra from the glasses are broad and featureless but shift by approximately +5 ppm with increased x, i.e. as the system becomes more ionic. The static 125Te NMR spectra show an increase in axial symmetry with increasing x, indicating a shift from predominantly [TeO4] to [TeO3] structural units. The 23Na and 125Te spectra from the crystallised samples have been fitted to obtain information on the sites in the metastable crystal phases, which are the first to form on heating and which are therefore more closely related to the glass structure than thermodynamically stable crystal phases. New sodium tellurite phases are reported, including a sodium stabilised, face centred cubic phase related to delta-TeO2; a metastable form of Na2Te4O9 containing 3 sodium and 4 tellurium sites; and a metastable form of Na2Te2O5 containing 2 sodium sites. There is evidence of oxidation of TeIV to TeVI occurring in glasses with high values of x and, at x=0.40 and 0.50 (outside the glass forming range), some sodium metatellurate (Na2TeO4) is formed at the same time as sodium metatellurite (Na2TeO3). The 125Te shift is very sensitive to environment within the sodium tellurite system, covering more than 320 ppm, with anisotropies varying from 640 to 1540 ppm. The lack of features in the 125Te spectra of the glass phases, combined with the large shift range and high but variable anisotropy, means than it is not possible to obtain a unique fit to any presumed species present. Furthermore, the chemical shift anisotropy parameters for three of the four Te sites in the Na2Te4O9 phase are found to lie outside the range used for previous simulations of glass spectra.

Enhanced Toxic Metal Accumulation in Engineered Bacterial Cells Expressing Arabidopsis thaliana Phytochelatin Synthase

Science.gov (United States)

Sauge-Merle, Sandrine; Cuiné, Stéphan; Carrier, Patrick; Lecomte-Pradines, Catherine; Luu, Doan-Trung; Peltier, Gilles

2003-01-01

Phytochelatins (PCs) are metal-binding cysteine-rich peptides, enzymatically synthesized in plants and yeasts from glutathione in response to heavy metal stress by PC synthase (EC 2.3.2.15). In an attempt to increase the ability of bacterial cells to accumulate heavy metals, the Arabidopsis thaliana gene encoding PC synthase (AtPCS) was expressed in Escherichia coli. A marked accumulation of PCs was observed in vivo together with a decrease in the glutathione cellular content. When bacterial cells expressing AtPCS were placed in the presence of heavy metals such as cadmium or the metalloid arsenic, cellular metal contents were increased 20- and 50-fold, respectively. We discuss the possibility of using genes of the PC biosynthetic pathway to design bacterial strains or higher plants with increased abilities to accumulate toxic metals, and also arsenic, for use in bioremediation and/or phytoremediation processes. PMID:12514032

Baseline heavy metals and metalloid values in blood of loggerhead turtles (Caretta caretta) from Baja California Sur, Mexico

International Nuclear Information System (INIS)

Ley-Quinonez, C.; Zavala-Norzagaray, A.A.; Espinosa-Carreon, T.L.; Peckham, H.; Marquez-Herrera, C.; Campos-Villegas, L.; Aguirre, A.A.

2011-01-01

Highlights: → We report baseline levels of selected heavy metals in blood of Pacific loggerhead turtles. → Blood was used to measure in a relatively non-invasive way baseline values of heavy metals. → Zn and Cd were found in high concentrations compared to levels reported in other parts of the world. → Cu concentrations in blood are high as they relate to concentrations in muscle. → No correlations were found between of heavy metals and metalloids analyzed and the size of the turtles. - Abstract: Environmental pollution due to heavy metals is having an increased impact on marine wildlife accentuated by anthropogenic changes in the planet including overfishing, agricultural runoff and marine emerging infectious diseases. Sea turtles are considered sentinels of ecological health in marine ecosystems. The objective of this study was to determine baseline concentrations of zinc, cadmium, copper, nickel, selenium, manganese, mercury and lead in blood of 22 clinically healthy, loggerhead turtles (Caretta caretta), captured for several reasons in Puerto Lopez Mateos, Baja California Sur, Mexico. Zinc was the most prevalent metal in blood (41.89 μg g -1 ), followed by Selenium (10.92 μg g -1 ). The mean concentration of toxic metal Cadmium was 6.12 μg g -1 and 1.01 μg g -1 respectively. Mean concentrations of metals followed this pattern: Zn > Se > Ni > Cu > Mn > Cd > Pb and Hg. We can conclude that blood is an excellent tissue to measure in relatively non-invasive way baseline values of heavy metals in Caretta caretta.

Oxygen vacancy induces self-doping effect and metalloid LSPR in non-stoichiometric tungsten suboxide synergistically contributing to the enhanced photoelectrocatalytic performance of WO3-x/TiO2-x heterojunction.

Science.gov (United States)

Huang, Weicheng; Wang, Jinxin; Bian, Lang; Zhao, Chaoyue; Liu, Danqing; Guo, Chongshen; Yang, Bin; Cao, Wenwu

2018-06-27

A WO3-x/TiO2-x nanotube array (NTA) heterojunction photoanode was strategically designed to improve photoelectrocatalytic (PEC) performance by establishing a synergistic vacancy-induced self-doping effect and localized surface plasmon resonance (LSPR) effect of metalloid non-stoichiometric tungsten suboxide. The WO3-x/TiO2-x NTA heterojunction photoanode was synthesized through a successive process of anodic oxidation to form TiO2 nanotube arrays, magnetron sputtering to deposit metalloid WO3-x, and post-hydrogen reduction to engender oxygen vacancy in TiO2-x as well as crystallization. On the merits of such a synergistic effect, WO3-x/TiO2-x shows higher light-harvesting ability, stronger photocurrent response, and resultant improved photoelectrocatalytic performance than the contrast of WO3-x/TiO2, WO3/TiO2 and TiO2, confirming the importance of oxygen vacancies in improving PEC performance. Theoretical calculation based on density functional theory was applied to investigate the electronic structural features of samples and reveal how the oxygen vacancy determines the optical property. The carrier density tuning mechanism and charge transfer model were considered to be associated with the synergistic effect of self-doping and metalloid LSPR effect in the WO3-x/TiO2-x NTA.

A Market Basket Survey of Horticultural Fruits for Arsenic and Trace Metal Contamination in Southeast Nigeria and Potential Health Risk Implications

OpenAIRE

Chigozie Damian Ezeonyejiaku; Maximilian Obinna Obiakor

2017-01-01

Background. Elevated arsenic and trace metal contamination of the terrestrial food chain represents one of the most significant environmental risk exposures for human populations in developing countries. Metalloid and metal contamination in horticultural crop produce such as fruit is a public health concern in Nigeria. Local fruits are cheap sources of vitamins and minerals for the resident population and pose an important dietary threat of metal(loid) toxicity through consumption. Objecti...

Evolution of ferroelectric SrBi2Nb2O9 phase embedded in tellurite glass

Science.gov (United States)

Mohamed, E. A.

2017-12-01

Glasses with the composition, [(100-x)TeO2- x(SrO-Bi2O3-Nb2O5)] with x = 20, 30 and 40 (in mol %) were prepared. The X-ray diffraction (XRD) pattern and differential thermal analysis (DTA) for the as-prepared samples confirmed the amorphous and glassy characteristics, respectively. The SrBi2Nb2O9 phase in tellurite glass for HT773 sample at x = 40 mol % is formed and confirmed by the Rietveld refinement. DTA curves for all glass samples exhibit two endothermic dips while the two broad exothermic peaks at lower x reduced to one at higher x. Infrared (IR) results revealed that the glassy matrix are composed of TeO3, TeO3+1, TeO4, BiO6 and NbO6 structural units. The changes in the density (ρ), molar volume (Vm), oxygen molar volume (V0) and oxygen packing fraction (OPD) have correlated with structural changes in the glass network. The optical studies show an absorption bands below the absorption edge in the glass samples.

Synthesis and different optical properties of Gd2O3 doped sodium zinc tellurite glasses

Science.gov (United States)

Samanta, Buddhadev; Dutta, Dibakar; Ghosh, Subhankar

2017-06-01

A series of Gd2O3 doped sodium zinc tellurite [xGd2O3-(0.8-x) TeO2-0.1Na2O-0.1ZnO] glasses are prepared by the conventional melt quenching method and their optical properties have been studied. UV-vis spectrophotometric studies within the wavelength range from 230 nm-800 nm are carried out in the integrating sphere mode to study the effect of Gd2O3 doping on the optical band gap (Eg), refractive index (n), dielectric constant (εr) and susceptibility (χ). Other physical properties like molar volume, molar refraction, polarizability, metallization criterion, number density of rare-earth ions (N), polaron radius (rp), inter ionic distance (ri), molar cation polarizability (∑αi), number of oxide ions in chemical composition (NO2-), optical band gap based electronic oxide ion polarizability (αO2-) and optical basicity (Λ) of glass samples have been studied on the basis of UV-vis spectra and density profile of the different glasses.

Syntheses and structural characterization of vanado-tellurites and vanadyl-selenites: SrVTeO{sub 5}(OH), Cd{sub 2}V{sub 2}Te{sub 2}O{sub 11}, Ca{sub 3}VSe{sub 4}O{sub 13}·H{sub 2}O and Ba{sub 2}VSe{sub 3}O{sub 10}

Energy Technology Data Exchange (ETDEWEB)

Konatham, Satish; Vidyasagar, Kanamaluru, E-mail: kvsagar@iitm.ac.in

2017-05-15

Four new quaternary vanado-tellurites and vanadyl-selenites, namely, SrVTeO{sub 5}(OH)(1), Cd{sub 2}V{sub 2}Te{sub 2}O{sub 11}(2), Ca{sub 3}VSe{sub 4}O{sub 13}·H{sub 2}O(3) and Ba{sub 2}VSe{sub 3}O{sub 10}(4) have been synthesized and structurally characterized by single crystal X-ray diffraction. The oxidation state of vanadium is +5 in tellurites 1 and 2 and +4 in selenites 3 and 4. The structures of SrVTeO{sub 5}(OH)(1) and Cd{sub 2}V{sub 2}Te{sub 2}O{sub 11}(2) compounds consist of (VTeO{sub 5}(OH)){sup 2-} and (V{sub 2}Te{sub 2}O{sub 11}){sup 4-}anionic chains respectively, which are built from tetrahedral VO{sub 4} and disphenoidal TeO{sub 4} moieties. Similarly the structures of Ca{sub 3}VSe{sub 4}O{sub 13}·H{sub 2}O(3) and Ba{sub 2}VSe{sub 3}O{sub 10}(4) respectively contain (VSe{sub 2}O{sub 7}){sup 2-} and (VSe{sub 3}O{sub 10}){sup 4-} anionic chains, which are made up of octahedral VO{sub 6} and pyramidal SeO{sub 3} units. Compounds 1 and 3 have been characterized by thermogravimetric and infrared spectroscopic methods. Compounds 1 and 2 are wide band gap semiconductors. - Graphical abstract: Ca{sub 3}VSe{sub 4}O{sub 13}·H{sub 2}O and Ba{sub 2}VSe{sub 3}O{sub 10} compounds contain (VSe{sub 2}O{sub 7}){sup 2-} and (VSe{sub 3}O{sub 10}){sup 4-} chains. - Highlights: • Four new vanado-tellurites and vanadyl-selenites are synthesized. • Their structural features are different. • The vanado-tellurites are wide band gap semiconductors.

Theoretical studies on metal thioarsenites and thioantimonides: synergistic interactions between transition metals and heavy metalloids

Directory of Open Access Journals (Sweden)

Tossell JA

2000-05-01

Full Text Available Recently we established that the ternary complex, CuAsS(SH(OH has an unusually high stability and makes a large contribution to the total concentrations of both Cu and As in sulfidic solutions equilibrated with Cu and As sulfide minerals. This ternary complex has an unusual structure, containing a bond which is formally Cu(I–As(III, along with a broken As–S bond. We have now found that complexes with similar structures exist for Au+ and Tl+ coordinated to AsS(SH(OH-. However, such a direct metal–metalloid bond is not a requirement for stability. In fact, TlAsS(SH(OH is unstable while AuAsS(SH(OH is highly stable (compared to the aquo ion. Zn2+, Cd2+, Hg2+ and Pb2+ also form bonds to the As of AsS(SH(OH, but without breaking any As–S bonds, and HgAsS(SH(OH+ and PbAsS(SH(OH+ are particularly stable complexes. Calculated structures are shown for these complexes, gas-phase energies are calculated, and formation constants in aqueous solution are estimated. The SbS(SH(OH- ion forms analogous complexes, with similar stabilities. However, the Au+ complex of SbS(SH(OH- is slightly less stable than the Cu+ complex, opposite to the order found for the AsS(SH(OH- ligand. The Au+ and AuSH complexes of AsSSHOH- or AsS(SH2- may be implicated in "invisible gold" in arsenian pyrites. Vibrational frequencies are given for the AuAsS(SH3- complex and the XANES energies of this complex and Au(SH2- are compared. The existence of such strong complexes may explain the many correlations observed between the concentrations of coinage metals and metalloids.

Band gap and polarizability of boro-tellurite glass: Influence of erbium ions

Science.gov (United States)

Said Mahraz, Zahra Ashur; Sahar, M. R.; Ghoshal, S. K.

2014-08-01

Understanding the influence of rare earth ions in improving the structural and optical properties of inorganic glasses are the key issues. Er3+-doped zinc boro-tellurite glasses with composition 30B2O3-10ZnO-(60-x) TeO2-xEr2O3 are prepared (x = 0, 0.5, 1, 1.5 and 2 mol%) using melt quenching technique. The physical and optical characterizations are measured by density and UV-Vis-IR absorption spectroscopy. The color of the glass changed from light yellow to deep pink due to the introduction of Er3+ ions. The maximum density is found to be ∼4.73 g cm-3 for 1 mol% of Er3+ doping. The variations in the polarizability (6.7-6.8 cm3) and the molar volume (27.987-28.827 cm3 mol-1) with dopant concentration are ascribed to the formation of non-bridging oxygen. This observation is consistent with the alteration of number of bonds per unit volume. The direct and indirect optical band gaps are increased while the phonon cut-off wavelength and Urbach energy decreased with the increase of erbium content. A high density and wide transparency range in VIS-IR area are achieved. Our results on high refractive index (∼2.416) and polarizability suggest that these glasses are potential for photonics, solid state lasers and communications devices.

Lanthanum lead boro-tellurite glasses doped with samarium trioxide for luminescent devices application

Science.gov (United States)

Madhu, A.; Eraiah, B.

2018-04-01

Boro-tellurite based glasses (10La2O3-(20-x) TeO2-30PbO-40B2O3-xSm2O3) (x = 0, 0.5, 1.0 and 2.0 mol %) doped with different concentrations of Sm3+ ions has been investigated. The optical properties have been studied through spectroscopic measurements such as absorption and luminescence. Absorption spectra reveals nine peaks due to 6H5/2→6P3/2, 4I3/2+4F5/2+4I11/2, 6F11/2, 6F9/2, 6F7/2, 6F5/2, 6F3/2, 6H15/2, and 6H13/2 transitions. Luminescence spectra under the excitation of 403 nm display four emission bands due to 4G5/2→6H5/2, 6H7/2, 6H9/2 and 6H11/2 transitions of Sm3+ ions. Among them 6H7/2 bright orange -red is more intense which proves that the present glasses are potential candidates for luminescent device applications in visible range as well as optical fibre communication since its refractive index is 1.65 high compared to other glasses.

Arsenic and Antimony Transporters in Eukaryotes

Directory of Open Access Journals (Sweden)

Ewa Maciaszczyk-Dziubinska

2012-03-01

Full Text Available Arsenic and antimony are toxic metalloids, naturally present in the environment and all organisms have developed pathways for their detoxification. The most effective metalloid tolerance systems in eukaryotes include downregulation of metalloid uptake, efflux out of the cell, and complexation with phytochelatin or glutathione followed by sequestration into the vacuole. Understanding of arsenic and antimony transport system is of high importance due to the increasing usage of arsenic-based drugs in the treatment of certain types of cancer and diseases caused by protozoan parasites as well as for the development of bio- and phytoremediation strategies for metalloid polluted areas. However, in contrast to prokaryotes, the knowledge about specific transporters of arsenic and antimony and the mechanisms of metalloid transport in eukaryotes has been very limited for a long time. Here, we review the recent advances in understanding of arsenic and antimony transport pathways in eukaryotes, including a dual role of aquaglyceroporins in uptake and efflux of metalloids, elucidation of arsenic transport mechanism by the yeast Acr3 transporter and its role in arsenic hyperaccumulation in ferns, identification of vacuolar transporters of arsenic-phytochelatin complexes in plants and forms of arsenic substrates recognized by mammalian ABC transporters.

Arsenic and Antimony Transporters in Eukaryotes

Science.gov (United States)

Maciaszczyk-Dziubinska, Ewa; Wawrzycka, Donata; Wysocki, Robert

2012-01-01

Arsenic and antimony are toxic metalloids, naturally present in the environment and all organisms have developed pathways for their detoxification. The most effective metalloid tolerance systems in eukaryotes include downregulation of metalloid uptake, efflux out of the cell, and complexation with phytochelatin or glutathione followed by sequestration into the vacuole. Understanding of arsenic and antimony transport system is of high importance due to the increasing usage of arsenic-based drugs in the treatment of certain types of cancer and diseases caused by protozoan parasites as well as for the development of bio- and phytoremediation strategies for metalloid polluted areas. However, in contrast to prokaryotes, the knowledge about specific transporters of arsenic and antimony and the mechanisms of metalloid transport in eukaryotes has been very limited for a long time. Here, we review the recent advances in understanding of arsenic and antimony transport pathways in eukaryotes, including a dual role of aquaglyceroporins in uptake and efflux of metalloids, elucidation of arsenic transport mechanism by the yeast Acr3 transporter and its role in arsenic hyperaccumulation in ferns, identification of vacuolar transporters of arsenic-phytochelatin complexes in plants and forms of arsenic substrates recognized by mammalian ABC transporters. PMID:22489166

Aquaglyceroporins: ancient channels for metalloids

Science.gov (United States)

Bhattacharjee, Hiranmoy; Mukhopadhyay, Rita; Thiyagarajan, Saravanamuthu; Rosen, Barry P

2008-01-01

The identification of aquaglyceroporins as uptake channels for arsenic and antimony shows how these toxic elements can enter the food chain, and suggests that food plants could be genetically modified to exclude arsenic while still accumulating boron and silicon. PMID:19014407

C-di-GMP regulates Pseudomonas aeruginosa stress response to tellurite during both planktonic and biofilm modes of growth

DEFF Research Database (Denmark)

Chua, Song Lin; Sivakumar, Krishnakumar; Rybtke, Morten Levin

2015-01-01

tellurite (TeO3(2-)) exposure induced the intracellular content of the secondary messenger cyclic di-GMP (c-di-GMP) of Pseudomonas aeruginosa. Two diguanylate cyclases (DGCs), SadC and SiaD, were responsible for the increased intracellular content of c-di-GMP. Enhanced c-di-GMP levels by TeO3(2-) further...... increased P. aeruginosa biofilm formation and resistance to TeO3(2-). P. aeruginosa ΔsadCΔsiaD and PAO1/p(lac)-yhjH mutants with low intracellular c-di-GMP content were more sensitive to TeO3(2-) exposure and had low relative fitness compared to the wild-type PAO1 planktonic and biofilm cultures exposed...... to TeO3(2-). Our study provided evidence that c-di-GMP level can play an important role in mediating stress response in microbial communities during both planktonic and biofilm modes of growth....

Spectroscopic studies of Dy3 + ion doped tellurite glasses for solid state lasers and white LEDs

Science.gov (United States)

Himamaheswara Rao, V.; Syam Prasad, P.; Mohan Babu, M.; Venkateswara Rao, P.; Satyanarayana, T.; Luís F., Santos; Veeraiah, N.

2018-01-01

Rare earth ion Dy3 +-doped tellurite glasses were synthesised in the system of (75-x)TeO2-15Sb2O3-10WO3-xDy2O3 (TSWD glasses). XRD and FTIR characterizations were used to find the crystalline and structural properties. The intensities of the electronic transitions and the ligand environment around the Dy3 + ion were determined using the Judd-Ofelt (J-O) theory on the absorption spectra of the glasses. The measured luminescence spectra exhibit intense emissions at 574 and 484 nm along with less intense emissions around 662 and 751 nm. Various radiative properties of the 4F9/2 excited level of Dy3 + ion were calculated for the glasses. Decay profiles were measured to find the life times and quantum efficiencies. Yellow to blue intensity ratio (Y/B), CIE chromaticity coordinates and correlated color temperature (CCT) values are calculated using the emission spectra to evaluate the emitted light. The obtained results suggest the utility of the glasses for potential yellow laser and white LED's applications.

Genomic Variability of O Islands Encoding Tellurite Resistance in Enterohemorrhagic Escherichia coli O157:H7 Isolates

Science.gov (United States)

Taylor, Diane E.; Rooker, Michelle; Keelan, Monika; Ng, Lai-King; Martin, Irene; Perna, Nicole T.; Burland, N. T. Valerie; Blattner, Fredrick R.

2002-01-01

Strains of Escherichia coli causing enterohemorrhagic colitis belonging to the O157:H7 lineage are reported to be highly related. Fifteen strains of E. coli O157:H7 and 1 strain of E. coli O46:H− (nonflagellated) were examined for the presence of potassium tellurite resistance (Ter). Ter genes comprising terABCDEF were shown previously to be part of a pathogenicity island also containing integrase, phage, and urease genes. PCR analysis, both conventional and light cycler based, demonstrated that about one-half of the Ter E. coli O157:H7 strains (6 of 15), including the Sakai strain, which has been sequenced, carried a single copy of the Ter genes. Five of the strains, including EDL933, which has also been sequenced, contained two copies. Three other O157:H7 strains and the O46:H− strain did not contain the Ter genes. In strains containing two copies, the Ter genes were associated with the serW and serX tRNA genes. Five O157:H7 strains resembled the O157 Sakai strain whose sequence contained one copy, close to serX, whereas in one isolate the single copy was associated with serW. There was no correlation between Ter and the ability to produce Shiga toxin ST1 or ST2. The Ter MIC for most strains, containing either one or two copies, was 1,024 μg/ml, although for a few the MIC was intermediate, 64 to 128 μg/ml, which could be increased to 512 μg/ml by pregrowth of strains in subinhibitory concentrations of potassium tellurite. Reverse transcriptase PCR analysis confirmed that in most strains Ter was constitutive but that in the rest it was inducible and involved induction of terB and terC genes. Only the terB, -C, -D, and -E genes are required for Ter. The considerable degree of homology between the ter genes on IncH12 plasmid R478, which originated in Serratia marcescens, and pTE53, from an E. coli clinical isolate, suggests that the pathogenicity island was acquired from a plasmid. This work demonstrates diversity among E. coli O157:H7 isolates, at least as

Transfer of metals and metalloids from soil to shoots in wild rosemary (Rosmarinus officinalis L.) growing on a former lead smelter site: human exposure risk.

Science.gov (United States)

Affholder, Marie-Cécile; Prudent, Pascale; Masotti, Véronique; Coulomb, Bruno; Rabier, Jacques; Nguyen-The, Bénédicte; Laffont-Schwob, Isabelle

2013-06-01

This study aimed at estimating exposition risks to wild rosemary used as herbs in the contaminated area of the former smelting factory of L'Escalette (South of Marseille, France). Metals and metalloids i.e. Pb, As, Sb, Zn, and Cu concentrations were analyzed in soils and in rosemary aerial parts (stems and leaves) on two sites: one heavily contaminated and the other far away from the pollution source, considered as reference. The metal and metalloid transfer into water during the brewing process of herbal tea was also determined. A mixed contamination by the above-cited contaminants was demonstrated in soils of the factory site, with average concentrations of 9253, 1127, 309, 2698 and 32 mg/kg for Pb, As, Sb, Zn and Cu, respectively. However, metals and metalloids' transfer in rosemary aerial parts was limited, as bioaccumulation factors were under 1. Thus, Pb, As and Cu concentrations in leaves were below international regulation limits concerning ingestion of medicinal herbs (no regulation values available for Sb and Zn). This study highlighted that, if contaminated rosemary leaves were ingested, health risks may be limited since acceptable daily intake (ADI) for Pb, As, Sb and Cu (no ADI value available for Zn) will only be reached if very high quantities are consumed. Furthermore, we aimed to establish if this mixed contamination could alter rosemary's essential oil quality, and thereby the compositions of essential oils obtained from individuals on the heavily contaminated soil were compared to those obtained from the reference population. An increased biosynthesis of antioxidant compounds was favored in essential oils from rosemary individuals growing in contaminated site. Although the health risk of a long-term exposition of low level of the mixed contamination by rosemary ingestion is not easy to elucidate, the use of rosemary essential oils from contaminated site appears as safe. Copyright © 2013 Elsevier B.V. All rights reserved.

Enhanced green upconversion by controlled ceramization of Er{sup 3+}–Yb{sup 3+} co-doped sodium niobium tellurite glass–ceramics for low temperature sensors

Energy Technology Data Exchange (ETDEWEB)

Suresh Kumar, J., E-mail: suresh@ua.pt; Pavani, K.; Graça, M.P.F.; Soares, M.J.

2014-12-25

Highlights: • Upconversion luminescence improved in glass–ceramics compared to host glass. • Judd–Ofelt and radiative parameters calculated. • NIR decay curve results concur the results of improved luminescence. • Temperature dependent upconversion support the use of materials for sensors. - Abstract: Tellurite based glasses are well-known for their upconversion properties besides having a disadvantage of low mechanical strength dragging them away from practical applications. The present work deals with preparation of sodium niobium tellurite (SNT) glasses using melt quenching method, in which small quantities of boron and silicon in the form of oxides are added to improve their mechanical properties. Controlled heat treatment is performed to ceramize the prepared glasses based on the thermal data given by DTA. XRD and SEM profiles of the glass–ceramics which confirmed the formation of crystalline monoclinic Sodium Tellurium Niobium Oxide (Na{sub 1.4}Nb{sub 3}Te{sub 4.9}O{sub 18}) phase (JCPDS card No. 04–011-7556). Upconversion measurements in the visible region were made for the prepared Er{sup 3+}–Yb{sup 3+} co-doped glasses and glass–ceramics with 980 nm laser excitation varying the laser power and concentration of Er{sup 3+} ions. Results showed that the upconversion luminescence intensity was enhanced by ten times in SNT glass–ceramics compared to that in the SNT glasses. Decay curves give evidence of high performance of glass–ceramics compared to glasses due to ceramization and structural changes. Temperature dependent visible upconversion was performed to test the ability of efficient SNT glass–ceramic at low temperatures and variation of upconversion intensities was studied.

Fate of nine recycled water trace organic contaminants and metal(loid)s during managed aquifer recharge into a anaerobic aquifer: Column studies.

Science.gov (United States)

Patterson, B M; Shackleton, M; Furness, A J; Pearce, J; Descourvieres, C; Linge, K L; Busetti, F; Spadek, T

2010-03-01

Water quality changes associated with the passage of aerobic reverse osmosis (RO) treated recycled water through a deep anaerobic pyritic aquifer system was evaluated in sediment-filled laboratory columns as part of a managed aquifer recharge (MAR) strategy. The fate of nine recycled water trace organic compounds along with potential negative water quality changes such as the release of metal(loid)s were investigated in large-scale columns over a period of 12 months. The anaerobic geochemical conditions provided a suitable environment for denitrification, and rapid (half-life 100 days). High retardation coefficients (R) determined for many of the trace organics (R 13 to 67) would increase aquifer residence time and be beneficial for many of the slow degrading compounds. However, for the trace organics with low R values (1.1-2.6) and slow degradation rates (half-life > 100 days), such as N-nitrosodimethylamine, N-nitrosomorpholine and iohexol, substantial biodegradation during aquifer passage may not occur and additional investigations are required. Only minor transient increases in some metal(loid) concentrations were observed, as a result of either pyrite oxidation, mineral dissolution or pH induced metal desorption, followed by metal re-sorption downgradient in the oxygen depleted zone. Crown Copyright 2009. Published by Elsevier Ltd. All rights reserved.

Extraction of metals and/or metalloids from acidic media using supercritical fluids and salts

International Nuclear Information System (INIS)

Wai, C.M.; Smart, N.G.; Lin, Y.

1998-01-01

A method is described for extracting metalloid and metal species from a solid or liquid material by exposing the material to a fluid solvent, particularly supercritical carbon dioxide, containing a chelating agent. The chelating agent forms chelates that are soluble in the fluid to allow removal of the species from the material. In preferred embodiments, the extraction solvent is supercritical carbon dioxide and the chelating agent comprises a trialkyl phosphate, a triaryl phosphate, a trialkylphosphine oxide, a triarylphosphine oxide, or mixtures thereof. The method provides an environmentally benign process for removing contaminants from industrial waste. The method is particularly useful for extracting actinides from acidic solutions, and the process can be aided by the addition of nitrate salts. The chelate and supercritical fluid can be regenerated, and the contaminant species recovered, to provide an economic, efficient process. 7 figs

Extraction of metals and/or metalloids from acidic media using supercritical fluids and salts

Science.gov (United States)

Wai, Chien M.; Smart, Neil G.; Lin, Yuehe

1998-01-01

A method of extracting metalloid and metal species from a solid or liquid material by exposing the material to a fluid solvent, particularly supercritical carbon dioxide, containing a chelating agent is described. The chelating agent forms chelates that are soluble in the fluid to allow removal of the species from the material. In preferred embodiments, the extraction solvent is supercritical carbon dioxide and the chelating agent comprises a trialkyl phosphate, a triaryl phosphate, a trialkylphosphine oxide, a triarylphosphine oxide, or mixtures thereof. The method provides an environmentally benign process for removing contaminants from industrial waste. The method is particularly useful for extracting actinides from acidic solutions, and the process can be aided by the addition of nitrate salts. The chelate and supercritical fluid can be regenerated, and the contaminant species recovered, to provide an economic, efficient process.

Improved ionic conductivity of lithium-zinc-tellurite glass-ceramic electrolytes

Science.gov (United States)

Widanarto, W.; Ramdhan, A. M.; Ghoshal, S. K.; Effendi, M.; Cahyanto, W. T.; Warsito

An enhancement in the secondary battery safety demands the optimum synthesis of glass-ceramics electrolytes with modified ionic conductivity. To achieve improved ionic conductivity and safer operation of the battery, we synthesized Li2O included zinc-tellurite glass-ceramics based electrolytes of chemical composition (85-x)TeO2·xLi2O·15ZnO, where x = 0, 5, 10, 15 mol%. Samples were prepared using the melt quenching method at 800 °C followed by thermal annealing at 320 °C for 3 h and characterized. The effects of varying temperature, alternating current (AC) frequency and Li2O concentration on the structure and ionic conductivity of such glass-ceramics were determined. The SEM images of the annealed glass-ceramic electrolytes displayed rough surface with a uniform distribution of nucleated crystal flakes with sizes less than 1 μm. X-ray diffraction analysis confirmed the well crystalline nature of achieved electrolytes. Incorporation of Li2O in the electrolytes was found to generate some new crystalline phases including hexagonal Li6(TeO6), monoclinic Zn2Te3O8 and monoclinic Li2Te2O5. The estimated crystallite size of the electrolyte was ranged from ≈40 to 80 nm. AC impedance measurement revealed that the variation in the temperatures, Li2O contents, and high AC frequencies have a significant influence on the ionic conductivity of the electrolytes. Furthermore, electrolyte doped with 15 mol% of Li2O exhibited the optimum performance with an ionic conductivity ≈2.4 × 10-7 S cm-1 at the frequency of 54 Hz and in the temperature range of 323-473 K. This enhancement in the conductivity was attributed to the sizable alteration in the ions vibration and ruptures of covalent bonds in the electrolytes network structures.

Arabidopsis and the Genetic Potential for the Phytoremediation of Toxic Elemental and Organic Pollutants

Science.gov (United States)

Cobbett, Christopher S.; Meagher, Richard B.

2002-01-01

In a process called phytoremediation, plants can be used to extract, detoxify, and/or sequester toxic pollutants from soil, water, and air. Phytoremediation may become an essential tool in cleaning the environment and reducing human and animal exposure to potential carcinogens and other toxins. Arabidopsis has provided useful information about the genetic, physiological, and biochemical mechanisms behind phytoremediation, and it is an excellent model genetic organism to test foreign gene expression. This review focuses on Arabidopsis studies concerning: 1) the remediation of elemental pollutants; 2) the remediation of organic pollutants; and 3) the phytoremediation genome. Elemental pollutants include heavy metals and metalloids (e.g., mercury, lead, cadmium, arsenic) that are immutable. The general goal of phytoremediation is to extract, detoxify, and hyperaccumulate elemental pollutants in above-ground plant tissues for later harvest. A few dozen Arabidopsis genes and proteins that play direct roles in the remediation of elemental pollutants are discussed. Organic pollutants include toxic chemicals such as benzene, benzo(a)pyrene, polychlorinated biphenyls, trichloroethylene, trinitrotoluene, and dichlorodiphenyltrichloroethane. Phytoremediation of organic pollutants is focused on their complete mineralization to harmless products, however, less is known about the potential of plants to act on complex organic chemicals. A preliminary survey of the Arabidopsis genome suggests that as many as 700 genes encode proteins that have the capacity to act directly on environmental pollutants or could be modified to do so. The potential of the phytoremediation proteome to be used to reduce human exposure to toxic pollutants appears to be enormous and untapped. PMID:22303204

Probing the distribution and contamination levels of 10 trace metal/metalloids in soils near a Pb/Zn smelter in Middle China.

Science.gov (United States)

Li, Zhonggen; Feng, Xinbin; Bi, Xiangyang; Li, Guanghui; Lin, Yan; Sun, Guangyi

2014-03-01

The horizontal and vertical distribution patterns and contamination status of ten trace metal/metalloids (Ag, Bi, Co, Cr, Ge, In, Ni, Sb, Sn, Tl) in soils around one of the largest Chinese Pb-Zn smelter in Zhuzhou City, Central China, were revealed. Different soil samples were collected from 11 areas, including ten agricultural areas and one city park area, with a total of 83 surface soil samples and six soil cores obtained. Trace metal/metalloids were determined by inductively coupled plasma-mass spectrometry after digestion by an acid mixture of HF and HNO3. The results showed that Ag, Bi, In, Sb, Sn, and Tl contents decreased both with the distance to the Pb-Zn smelter as well as the soil depth, hinting that these elements were mainly originated from the Pb-Zn smelting operations and were introduced into soils through atmospheric deposition. Soil Ge was influenced by the smelter at a less extent, while the distributions of Co, Cr, and Ni were roughly even among most sampling sites and soil depths, suggesting that they were primarily derived from natural sources. The contamination status, as revealed by the geo-accumulation index (I geo), indicated that In and Ag were the most enriched elements, followed by Sb, Bi, and Sn. In general, Cr, Tl, Co, Ni, and Ge were of an uncontaminated status.

An improved route to 19-substituted geldanamycins as novel Hsp90 inhibitors ? potential therapeutics in cancer and neurodegeneration? ?Electronic supplementary information (ESI) available. See DOI: 10.1039/c3cc43457e Click here for additional data file. Click here for additional data file.

OpenAIRE

Kitson, Russell R. A.; Moody, Christopher J.

2013-01-01

19-Substituted geldanamycin derivatives are efficient Hsp90 inhibitors, without the toxicity associated with the other benzoquinone ansamycins, thus giving them potential for use as molecular therapeutics in cancer and neurodegeneration. Here a new method of synthesising these important compounds is reported, eliminating the need for toxic metals and metalloids.

Effects of sex on the levels of metals and metalloids in the hair of a group of healthy Spanish adolescents (13 to 16 years old).

Science.gov (United States)

Peña-Fernández, Antonio; Del Carmen Lobo-Bedmar, Maria; González-Muñoz, Maria José

2017-10-01

Human biomonitoring can be a reliable tool to protect the health of the citizens of major urban environments. Human hair may be an invaluable specimen to determine chronic exposure to any environmental contaminant in an individual, especially in the young population. However, different factors including a lack of studies that have established reference values for metals and metalloids (trace elements) in human scalp hair make the use of this matrix controversial. A monitoring study was performed to establish possible normal or tentative reference values of Al, As, Be, Cd, Cr, Cu, Hg, Mn, Pb, Sn, Ti, Tl and Zn in adolescents' (aged 13-16) hair who have lived since birth in Alcalá de Henares, Madrid region (Spain). Strict inclusion criteria were followed to study the effect of sex on the hair metal content, and the levels of the above contaminants were also studied in park topsoils from Alcalá de Henares. Scalp hair samples were collected from 96 healthy adolescents (28 boys and 68 girls), and reference values were calculated following the recommendations of the International Union of Pure and Applied Chemistry. The levels of Cd, Cu, Pb, Sn and Zn in hair of adolescents from Alcalá de Henares show a sex dependency, being significantly higher in female participants. Sex should be a factor taken into account when developing future reference values and hair metal content. Soil metal contamination was not correlated with the levels found in hair. To conclude, the values of metals and metalloids here analysed and discussed could be considered as tentative reference values for Spanish adolescents aged 13-16 years living in the Madrid region, and may be used to identify the level of exposure of adolescents in this Spanish region to the various metals and metalloids.

Polymorphic crystallization of metal-metalloid-glasses above the glass transition temperature

International Nuclear Information System (INIS)

Koster, U.; Schunemann, U.; Stephenson, G.B.; Brauer, S.; Sutton, M.

1992-01-01

Crystallization of metal-metalloid glasses is known to proceed by nucleation and growth processes. Using crystallization statistics in partially crystallized glasses, at temperatures below the glass transition temperature, time-dependent heterogeneous nucleation has been found to occur at a number of quenched-in nucleation sites. Close to the glass transition temperature crystallization proceeds so rapidly that partially crystallized microstructures could not be obtained. Initial results form fully crystallized glasses exhibit evidence for a transient homogeneous nucleation process at higher temperatures. These conclusions are derived post mortem. At there may be some change of the microstructure after crystallization is finished or during he subsequent quenching, it is desirable to directly obtain information during the early stages of crystallization. Recently reported work by Sutton et al. showed that structural changes can be observed in situ during crystallization by time-resolved x-ray diffraction on time scales as short as milliseconds. The aim o the paper is to present the authors study of the crystallization behavior at temperatures near the glass transition by in-situ x-ray diffraction studies and by microstructural analysis after rapid heating experiments. The results are compared to those derived from a computer model of the crystallization process

Determination of the oxidation states of metals and metalloids: An analytical review

Science.gov (United States)

Vodyanitskii, Yu. N.

2013-12-01

The hazard of many heavy metals/metalloids in the soil depends on their oxidation state. The problem of determining the oxidation state has been solved due to the use of synchrotron radiation methods with the analysis of the X-ray absorption near-edge structure (XANES). The determination of the oxidation state is of special importance for some hazardous heavy elements (arsenic, antimony, selenium, chromium, uranium, and vanadium). The mobility and hazard of each of these elements depend on its oxidation state. The mobilities are higher at lower oxidation states of As, Cr, V, and Se and at higher oxidation states of Sb and U. The determination of the oxidation state of arsenic has allowed revealing its fixation features in the rhizosphere of hydrophytes. The known oxidation states of chromium and uranium are used for the retention of these elements on geochemical barriers. Different oxidation states have been established for vanadium displacing iron in goethite. The determination of the oxidation state of manganese in the rhizosphere and the photosynthetic apparatus of plants is of special importance for agricultural chemists.

Effect of natural Fe{sub 3}O{sub 4} nanoparticles on structural and optical properties of Er{sup 3+} doped tellurite glass

Energy Technology Data Exchange (ETDEWEB)

Widanarto, W. [Physics Study Program, Jenderal Soedirman University, Jl. dr. Soeparno 61 Purwokerto 53123 (Indonesia); Sahar, M.R., E-mail: m-rahim@dfiz2.fs.utm.my [Department of Physics, Faculty of Science, Universiti Teknologi Malaysia, Johor Bahru, Skudai 81310 (Malaysia); Ghoshal, S.K.; Arifin, R.; Rohani, M.S.; Hamzah, K. [Department of Physics, Faculty of Science, Universiti Teknologi Malaysia, Johor Bahru, Skudai 81310 (Malaysia)

2013-01-15

Control doping of magnetic nanoparticles and its influence on optical and structural properties of tellurite glass is important from device perspectives. Natural Fe{sub 3}O{sub 4} nanoparticles obtained by extracting and ball milling iron sand, are incorporated in the Er{sup 3+} doped tellurite glasses having composition (80-x)TeO{sub 2}{center_dot}xFe{sub 3}O{sub 4}{center_dot}18ZnO{center_dot}1Li{sub 2}O{center_dot}1Er{sub 2}O{sub 3} (0{<=}x{<=}1.5) in mol% by melt quenching method at 850 Degree-Sign C. X-Ray diffraction spectra confirms the presence of iron nanoparticles with estimated sizes 18-70 nm and an amorphous structure of the samples. Thermal and optical characterizations are made using diffential thermal analysis, ultraviolet-visible and photoluminescence spectrocopies. It is found that the presence of nanoparticles changes color and thermal stability of the glasses, which is proved by increasing thermal stability factor from 118 to 132 Degree-Sign C. Absorption spectra consist of six peaks corresponding to different transition from ground state to the excited states in which the quench of the peak associated with {sup 4}F{sub 1/2} is attributed to the effect nanoparticles. Moreover, the shift in the absorption edge from {approx}400 to {approx}500 nm indicates a significant decrease of the optical energy band gap for both direct and indirect allowed transitions and a decrease in the Urbach energy as much as 0.116 eV is observed. The room temperature down-conversion luminescence spectra obtained under 500 nm excitation exhibit two strong peaks related to excited states {sup 4}S{sub 3/2} and {sup 4}F{sub 9/2} of Er{sup 3+} ions in the absence of nanoparticles. Furthermore, embedding nanoparticles into the glass not only make the peaks weaker but the second peak completely disappears. Interestingly, the emission bands of the Er{sup 3+} ion are quenched as concentration of the magnetic nanoparticles is increased.

Risk Assessment and Source Identification of 17 Metals and Metalloids on Soils from the Half-Century Old Tungsten Mining Areas in Lianhuashan, Southern China

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Li Guo

2017-11-01

Full Text Available Background: Mining activities always emit metal(loids into the surrounding environment, where their accumulation in the soil may pose risks and hazards to humans and ecosystems. Objective: This paper aims to determine of the type, source, chemical form, fate and transport, and accurate risk assessment of 17 metal(loid contaminants including As, Cd, Cu, Ni, Pb, Zn, Cr, Ag, B, Bi, Co, Mo, Sb, Ti, V, W and Sn in the soils collected from an abandoned tungsten mining area, and to guide the implementing of appropriate remediation strategies. Methods: Contamination factors (CFs and integrated pollution indexes (IPIs and enrichment factors (EFs were used to assess their ecological risk and the sources were identified by using multivariate statistics analysis, spatial distribution investigation and correlation matrix. Results: The IPI and EF values indicated the soils in the mine site and the closest downstream one were extremely disturbed by metal(loids such as As, Bi, W, B, Cu, Pb and Sn, which were emitted from the mining wastes and acid drainages and delivered by the runoff and human activities. Arsenic contamination was detected in nine sites with the highest CF values at 24.70 next to the mining site. The Cd contamination scattered in the paddy soils around the resident areas with higher fraction of bioavailable forms, primarily associated with intense application of phosphorus fertilizer. The lithogenic elements V, Ti, Ag, Ni, Sb, Mo exhibit low contamination in all sampling points and their distribution were depended on the soil texture and pedogenesis process. Conclusions: The long term historical mining activities have caused severe As contamination and higher enrichment of the other elements of orebody in the local soils. The appropriate remediation treatment approach should be proposed to reduce the bioavailability of Cd in the paddy soils and to immobilize As to reclaim the soils around the mining site. Furthermore, alternative fertilizing

Risk Assessment and Source Identification of 17 Metals and Metalloids on Soils from the Half-Century Old Tungsten Mining Areas in Lianhuashan, Southern China.

Science.gov (United States)

Guo, Li; Zhao, Weituo; Gu, Xiaowen; Zhao, Xinyun; Chen, Juan; Cheng, Shenggao

2017-11-29

Background: Mining activities always emit metal(loid)s into the surrounding environment, where their accumulation in the soil may pose risks and hazards to humans and ecosystems. Objective : This paper aims to determine of the type, source, chemical form, fate and transport, and accurate risk assessment of 17 metal(loid) contaminants including As, Cd, Cu, Ni, Pb, Zn, Cr, Ag, B, Bi, Co, Mo, Sb, Ti, V, W and Sn in the soils collected from an abandoned tungsten mining area, and to guide the implementing of appropriate remediation strategies. Methods : Contamination factors ( CFs ) and integrated pollution indexes ( IPIs ) and enrichment factors ( EFs ) were used to assess their ecological risk and the sources were identified by using multivariate statistics analysis, spatial distribution investigation and correlation matrix. Results : The IPI and EF values indicated the soils in the mine site and the closest downstream one were extremely disturbed by metal(loid)s such as As, Bi, W, B, Cu, Pb and Sn, which were emitted from the mining wastes and acid drainages and delivered by the runoff and human activities. Arsenic contamination was detected in nine sites with the highest CF values at 24.70 next to the mining site. The Cd contamination scattered in the paddy soils around the resident areas with higher fraction of bioavailable forms, primarily associated with intense application of phosphorus fertilizer. The lithogenic elements V, Ti, Ag, Ni, Sb, Mo exhibit low contamination in all sampling points and their distribution were depended on the soil texture and pedogenesis process. Conclusions : The long term historical mining activities have caused severe As contamination and higher enrichment of the other elements of orebody in the local soils. The appropriate remediation treatment approach should be proposed to reduce the bioavailability of Cd in the paddy soils and to immobilize As to reclaim the soils around the mining site. Furthermore, alternative fertilizing way

Sulphur self as a bioindicator of air pollution

International Nuclear Information System (INIS)

Sihelska, N.; Semerad, M.; Cernansky, S.; Ruzickova, J.; Takacova, A.

2015-01-01

Road transport is one of the major sources of air polluting emissions. An average passenger car produces emissions of 228 g/km, trucks produce emissions of around 317 g/km. Emissions from combustion engines contain carbon dioxide, water vapour, nitrogen oxides, ammonia, carbon monoxide, unburned hydrocarbons, sulphur dioxide and various solids. Emissions also contain compounds of toxic metals/metalloids - arsenic, cadmium, chrome, nickel and lead. To detect metal/metalloid contamination from vehicle emissions, samples were collected and analyzed from biomass and soil near Bratislava's busiest road. We focused our attention on concentration of metals/metalloids in Laetiporus sulphureus because it's a very popular edible mushroom. Mushrooms are very good proxies for the state of nearby environment because of their excellent accumulation ability. (authors)

Investigation of biomethylation of arsenic and tellurium during composting

International Nuclear Information System (INIS)

Diaz-Bone, Roland A.; Raabe, Maren; Awissus, Simone; Keuter, Bianca; Menzel, Bernd; Kueppers, Klaus; Widmann, Renatus; Hirner, Alfred V.

2011-01-01

Though the process of composting features a high microbiological activity, its potential to methylate metals and metalloids has been little investigated so far in spite of the high impact of this process on metal(loid) toxicity and mobility. Here, we studied the biotransformation of arsenic, tellurium, antimony, tin and germanium during composting. Time resolved investigation revealed a highly dynamic process during self-heated composting with markedly differing time patterns for arsenic and tellurium species. Extraordinary high concentrations of up to 150 mg kg -1 methylated arsenic species as well as conversion rates up to 50% for arsenic and 5% for tellurium were observed. In contrast, little to no conversion was observed for antimony, tin and germanium. In addition to experiments with metal(loid) salts, composting of arsenic hyperaccumulating ferns Pteris vittata and P. cretica grown on As-amended soils was studied. Arsenic accumulated in the fronds was efficiently methylated resulting in up to 8 mg kg -1 methylated arsenic species. Overall, these studies indicate that metal(loid)s can undergo intensive biomethylation during composting. Due to the high mobility of methylated species this process needs to be considered in organic waste treatment of metal(loid) contaminated waste materials.

Spatial Characteristics, Health Risk Assessment and Sustainable Management of Heavy Metals and Metalloids in Soils from Central China

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Fei Li

2018-01-01

Full Text Available The contents of seven toxic metals (Cu, Cr, Cd, Zn, Pb, Hg and As in soils from Central China, including Henan Province, Hubei Province and Hunan Province, were collected from published papers from 2007 to 2017. The geoaccumulation index, health risk assessment model and statistics were adopted to study the spatial contamination pattern, to assess the human health risks and to identify the priority control pollutants. The concentrations of soil metals in Central China, especially Cd (1.31 mg/kg, Pb (44.43 mg/kg and Hg (0.19 mg/kg, surpassed their corresponding background values, and the Igeo values of Cd and Hg varied the most, ranging from the unpolluted level to the extremely polluted level. The concentrations of toxic metals were higher in the southern and northern parts of Central China, contrasting to the lowest contents in the middle parts. For non-carcinogenic risk, the hazard index (HI values for the children in Hubei Province (1.10 and Hunan Province (1.41 exceeded the safe level of one, with higher health risks to children than adults, and the hazard quotient (HQ values of the three exposure pathways for both children and adults in Central China decreased in the following order: ingestion > dermal contact > inhalation. For carcinogenic risk (CR, the CR values for children in Hubei Province (2.55 × 10−4, Hunan Province (3.44 × 10−4 and Henan Province (1.69 × 10−4, and the CR for adults in Hubei Province (3.67 × 10−5, Hunan Province (4.92 × 10−5 and Henan Province (2.45 × 10−5 exceeded the unacceptable level (10−4 and acceptable level (10−6, respectively. Arsenic (As appeared to be the main metalloid for both children and adults causing the high carcinogenic risk. For sustainable development in Central China, special attention should be paid to Cd, Hg, Cr, Pb and As, identified as the priority control soil metals. Importance should also be attached to public education, source control, and the remediation of the

Nd3+-doped lanthanum lead boro-tellurite glass for lasing and amplification applications

Science.gov (United States)

Madhu, A.; Eraiah, B.; Manasa, P.; Srinatha, N.

2018-01-01

Nd3+-doped lanthanum lead boro-tellurite glass samples were prepared by conventional melt quenching method and their structural, thermal, fluorescence, and decay times of the glasses were investigated. Prepared glass samples exhibits amorphous nature and shows good thermal stability in the temperature range of 100-800 °C. Judd-Ofelt (JO) analysis was carried out and the intensity parameters (Ωλ = 2, 4, 6) also spontaneous radiative probability and stimulated-.emission cross-sections were estimated. The magnitude of Ωλ confirms the covalency nature. The near infrared emission spectra were measured by 808 nm excitation in which the emission intensity is found to be high at 1060 nm for the 4F3/2 → 4F11/2 transition. The stimulated cross section, effective band width and branching ratios are found to be 8.910 × 10-20 cm2, 21.57 nm and 53.72 % respectively, for 4F3/2 → 4F11/2 transition. The derived gain bandwidth, figure of merit, threshold and saturation intensity found to be comparable to some of the glass systems. Furthermore, the time decay rate found to decrease from 100 μs to 27 μs when the concentration increased from 0.1 to 3.0 mol% of Nd3+ ions and also all follow the single exponential behaviour which is attributed to the self quenching effect due to the cross-relaxation channels.

Lake sediment cores as indicators of historical metal(loid) accumulation – A case study in Mexico

International Nuclear Information System (INIS)

Hansen, Anne M.

2012-01-01

To examine and compare historical accumulation of metal(loid)s in Mexican lakes and reservoirs, 210 Pb and 137 Cs dated sediment cores were evaluated: two from the remote Zempoala and Miramar Lagoons and three from Lake Pátzcuaro, and the Intermedia and Silva dams that are affected by human activities. Sediment ecotoxicology was assessed using consensus-based sediment quality guidelines for freshwater ecosystems. The +100 a sediment core from the remote Miramar Lagoon had the highest concentrations of Cr and Ni these being higher than the Probable Effect Levels (PELs). Zinc concentrations were also higher in the Miramar Lagoon compared to the other lakes and reservoirs, with concentrations higher than the Threshold Effect Level (TEL). Mercury concentrations from this lagoon were comparable to those for the Intermedia dam that receives water from urban, industrial and agricultural areas. The higher metal concentrations in the core from the Miramar Lagoon suggest that metal concentrations in the rocks of the watershed are high. Another explanation for the higher metal concentrations is the slow sediment accumulation that causes metals to be accumulated over longer time-periods at the sediment–water interface. A decrease in the concentration of As in the Intermedia dam was observed in sediments corresponding to the last decades. This may be due to an increase in sediment accumulation rate or to the reduction in sources of this metalloid in the watershed. In the Miramar Lagoon, an increase was observed in concentrations of As and Cr in more recent sediments, probably related to increased deforestation in the area or the eruption of El Chichonal volcano in 1982. Concentrations of Pb showed a decreasing tendency over the past decades in the Lake Pátzcuaro, Miramar and Zempoala Lagoons sediment cores while such behavior was not be observed for the Intermedia dam. This reduction in concentrations of Pb was attributed to the decrease in use of leaded gasoline.

Optical properties of single doped Cr3+ and co-doped Cr3+-Nd3+ aluminum tantalum tellurite glasses

International Nuclear Information System (INIS)

Rodriguez-Mendoza, U.R.; Speghini, A.; Jaque, D.; Zambelli, M.; Bettinelli, M.

2004-01-01

The optical properties for single doped Cr 3+ and co-doped Cr 3+ -Nd 3+ aluminum tantalum tellurite glasses have been studied as a function of temperature. For the single doped glass, the existence of two bands in the emission spectra at low temperature indicates the presence of two different sites for the Cr 3+ ions, labelled as usual as low- and high-field sites. The broad band centred in the Near Infrared region, corresponds to low-field sites transition 4 T 2 → 4 A 2 , and the narrow band centred at approximately 715 nm to the high-field sites transition 2 E→ 4 A 2 . The emission intensity for both high- and low-field sites shows a strong decrease with increasing temperature, with the emission for the former sites vanishing at RT. In both cases the quenching observed with the increase of temperature can be ascribed to the presence of non-radiative relaxation mechanisms. Experimental observations for the co-doped glass show that both radiative and non-radiative energy transfer processes from Cr 3+ to Nd 3+ are present

Enhancement of 800 nm upconversion emission in a thulium doped tellurite microstructured fiber pumped by a 1560 nm femtosecond fiber laser

Energy Technology Data Exchange (ETDEWEB)

Jia, Zhixu; Zheng, Kezhi [State Key Laboratory of Optical Fiber and Cable Manufacture Technology, Yangtze Optical Fiber and Cable Joint Stock Limited Company, Wuhan 430073 (China); State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012 (China); Yao, Chuanfei; Wang, Shunbin; Qin, Guanshi, E-mail: qings@jlu.edu.cn; Qin, Weiping, E-mail: wpqin@jlu.edu.cn [State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012 (China); Xiong, Liangming; Luo, Jie; Lv, Dajuan [State Key Laboratory of Optical Fiber and Cable Manufacture Technology, Yangtze Optical Fiber and Cable Joint Stock Limited Company, Wuhan 430073 (China); Ohishi, Yasutake [Research Center for Advanced Photon Technology, Toyota Technological Institute, 2-12-1 Hisakata, Tempaku, Nagoya 468–8511 (Japan)

2016-04-28

We report enhanced upconversion (UC) fluorescence in Tm{sup 3+} doped tellurite microstructured fibers (TDTMFs) fabricated by using a rod-in-tube method. Under the pumping of a 1560 nm femtosecond fiber laser, ultrabroadband supercontinuum light expanding from ∼1050 to ∼2700 nm was generated in a 4 cm long TDTMF. Simultaneously, intense 800 nm UC emission from the {sup 3}H{sub 4} → {sup 3}H{sub 6} transition of Tm{sup 3+} was observed in the same TDTMF. Compared to that pumped by a 1560 nm continuous wave fiber laser, the UC emission intensity was enhanced by ∼4.1 times. The enhancement was due to the spectral broadening in the TDTMF under the pumping of the 1560 nm femtosecond fiber laser.

Assessment of Metalloid and Metal Contamination in Soils from Hainan, China

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Xiangjun Liao

2018-03-01

Full Text Available The characterization of the concentrations and sources of metals and metalloids in soils is necessary to establish quality standards on a regional level and to assess the potential threat of metals to food safety and human health. A total of 8713 soil samples throughout Hainan Island, China were collected at a density of one sample per 4 km2, and concentrations of As, Cd, Cr, Cu, Hg, Ni, Pb, Se, and Zn were analyzed. The geometric mean values of the elements were 2.17, 0.60, 26.5, 9.43, 0.033, 8.74, 22.2, 0.26, and 39.6 mg·· kg−1 for As, Cd, Cr, Cu, Hg, Ni, Pb, Se, and Zn, respectively, significantly lower than the background values of Chinese soils with the exception of Se. Principal component analysis (PCA suggested that multiple anthropogenic sources regulated the elemental compositions of the Hainan environment. Coal combustion and mining are important anthropogenic sources of metals for Hainan. The geochemical maps of elements in Hainan soils were produced using the Geographic Information System (GIS method, and several hot-spot areas were identified. The ecological impact of As, Cd, Cu, Cr, Hg, Pb, Ni, and Zn pollution to the soils was extremely “low”.

Structural and optical studies on Eu3+ doped boro-tellurite glasses

Science.gov (United States)

Maheshvaran, K.; Veeran, P. K.; Marimuthu, K.

2013-03-01

Eu3+ doped boro-tellurite glasses (69 - x)B2O3 + xTeO2 + 15Na2CO3 + 15NaF + 1Eu2O3 (where x = 0, 10, 20, 30 and 40 wt%) have been prepared and their structural and optical properties were studied through XRD, FTIR, absorption, luminescence and decay time measurements. The FTIR spectra reveal the presence of B-O-B bond bending vibrations and Te-O-Te or O-Te-O linkage bending vibrations in the prepared glasses. The absorption spectral measurements were used to calculate the bonding parameters (β¯, δ). The direct, indirect allowed band gap (Eopt), band tail parameter (B) and Urbach energy (ΔE) values of the prepared glasses have also been determined from the absorption spectral measurements. The phonon sideband is observed from the excitation spectra on the higher energy side of the 7F0 → 5D2 transition. The phonon energy (hω) and the electron-phonon coupling constant (g) were also derived from the phonon sideband spectra. Through the luminescence spectra, Judd-Ofelt (JO) intensity parameters (Ωλ, λ = 2, 4 and 6) and the luminescence intensity ratio (R) have been determined. The JO parameters have also been used to calculate the radiative properties like transition probability (A), stimulated emission cross-section (σPE), radiative lifetime (τrad), and branching ratios (βR) for the 5D0 → 7FJ (J = 0, 1, 2, 3 and 4) emission transitions of the Eu3+ ions. The experimental lifetime of the 5D0 level is found to be single exponential for all the prepared glasses. The obtained results were discussed and reported in the present work.

Comparative proteomic analysis reveals heart toxicity induced by chronic arsenic exposure in rats

International Nuclear Information System (INIS)

Huang, Qingyu; Xi, Guochen; Alamdar, Ambreen; Zhang, Jie; Shen, Heqing

2017-01-01

Arsenic is a widespread metalloid in the environment, which poses a broad spectrum of adverse effects on human health. However, a global view of arsenic-induced heart toxicity is still lacking, and the underlying molecular mechanisms remain unclear. By performing a comparative quantitative proteomic analysis, the present study aims to investigate the alterations of proteome profile in rat heart after long-term exposure to arsenic. As a result, we found that the abundance of 81 proteins were significantly altered by arsenic treatment (35 up-regulated and 46 down-regulated). Among these, 33 proteins were specifically associated with cardiovascular system development and function, including heart development, heart morphology, cardiac contraction and dilation, and other cardiovascular functions. It is further proposed that the aberrant regulation of 14 proteins induced by arsenic would disturb cardiac contraction and relaxation, impair heart morphogenesis and development, and induce thrombosis in rats, which is mediated by the Akt/p38 MAPK signaling pathway. Overall, these findings will augment our knowledge of the involved mechanisms and develop useful biomarkers for cardiotoxicity induced by environmental arsenic exposure. - Highlights: • Arsenic exposure has been associated with a number of adverse health effects. • The molecular mechanisms involved in arsenic-induced cardiotoxicity remain unclear. • Differential proteins were identified in arsenic-exposed rat heart by proteomics. • Arsenic induces heart toxicity through the Akt/p38 MAPK signaling pathway. - Label-free quantitative proteomic analysis of rat heart reveals putative mechanisms and biomarkers for arsenic-induced cardiotoxicity.

Judd-Ofelt analysis and photoluminescence properties of RE3+ (RE = Er & Nd): Cadmium lithium boro tellurite glasses

Science.gov (United States)

Raju, K. Vemasevana; Raju, C. Nageswara; Sailaja, S.; Reddy, B. Sudhakar

2013-01-01

Rare earth (Er3+ and Nd3+) ions doped cadmium lithium boro tellurite (CLiBT) glasses were prepared by melt quenching method. The vis-NIR absorption spectra of these glasses have been analyzed systematically. Judd-Ofelt intensity parameters Ωλ (λ = 2, 4, 6) have been evaluated and used to compute the radiative properties of emission transitions of Er3+ and Nd3+: CLiBT glasses. From the NIR emission spectra of Er3+: CLiBT glasses a broad emission band centered at 1538 nm (4I13/2 → 4I15/2) is observed and from Nd3+: CLiBT glasses, three NIR emission bands at 898 nm (4F3/2 → 4I9/2), 1070 nm (4F3/2 → 4I11/2) and 1338 nm (4F3/2 → 4I13/2) are observed with an excitation wavelength λexci = 514.5 nm (Ar+ Laser). The FWHM and stimulated emission cross-section values are calculated for Er3+ and Nd3+: CLiBT glasses. FWHM × σeP values are also calculated for Er3+: CLiBT glasses.

Arsenite tolerance and biotransformation potential in estuarine bacteria

Digital Repository Service at National Institute of Oceanography (India)

Nagvenkar, G.S.; Ramaiah, N.

and Acinetobacter strains. From these observations it is clear that many environmental strains are capable of quite rapid biotransformation of As. Contamination of drinking water by toxic metalloid arsenic affects thousands of people worldwide. Many environmental...

Gold nanoparticles assisted surface enhanced Raman scattering and luminescence of Er{sup 3+} doped zinc–sodium tellurite glass

Energy Technology Data Exchange (ETDEWEB)

Ghoshal, S.K.; Awang, Asmahani, E-mail: asmahani_awang@yahoo.com; Sahar, M.R.; Arifin, R.

2015-03-15

Significant enhancements in Er{sup 3+} luminescence and Raman intensity mediated via surface plasmon resonance (SPR) of gold (Au) nanoparticles (NPs) embedded zinc–sodium tellurite glass are reported. The observed modifications in the physical and spectroscopic properties are ascribed to the alterations in the glass network. XRD pattern confirms the amorphous nature of prepared glass sample. UV–vis-NIR spectra reveal seven absorption bands. Surface plasmon band is evidenced around 626–630 nm. TEM images manifest the growth of non-spherical Au NPs with average diameter between ∼7.2 nm and 8.6 nm. The visible up-conversion (UC) emission for all samples under 779 nm excitation exhibits three bands centered at 503 nm (green), 546 (green) and 637 nm (red) ascribed to {sup 2}H{sub 11/2}→{sup 4}I{sub 15/2}, {sup 4}S{sub 3/2}→{sup 4}I{sub 15/2} and {sup 4}F{sub 9/2}→{sup 4}I{sub 15/2} transitions. Glass sample with 0.4 mol% Au displaying the highest luminescence intensity with enhancement factor of 3.85 and 3.56 for green bands, and 7.61 for the red band is ascribed to the NPs local field enhancement and energy transfer between rare earth (RE) ions and NPs. FTIR spectra show the vibration of ZnO{sub 4} bonds, Te-O bond in TeO{sub 3} (tp) and TeO{sub 4} (tbp) units and the hydroxyl groups. Raman spectra demonstrate the presence of Er-O and Zn-O bond, anti-symmetric vibrations of Te-O-Te bonds and stretching modes of non-bonded oxygen exists in TeO{sub 3} and TeO{sub 3+1} unit. The amplifications in Raman signals by a factor of 1.62, 1.58, 1.64, 1.68 and 1.69 corresponding to the peak centered at 262 cm{sup −1}, 382 cm{sup −1}, 521 cm{sup −1}, 670 cm{sup −1} and 725 cm{sup −1} are attributed to the contribution of a surface plasmon generating a strong, localized and secondary field. We assert that our glass compositions offer favorable potential to develop solid state lasers and other versatile nanophotonic devices. - Highlights: • Gold

Geochemical and mineralogical characterization of a neutral, low-sulfide/high-carbonate tailings impoundment, Markušovce, eastern Slovakia.

Science.gov (United States)

Hiller, Edgar; Petrák, Marián; Tóth, Roman; Lalinská-Voleková, Bronislava; Jurkovič, L'ubomír; Kučerová, Gabriela; Radková, Anežka; Sottník, Peter; Vozár, Jaroslav

2013-11-01

Tailings deposits generated from mining activities represent a potential risk for the aquatic environment through the release of potentially toxic metals and metalloids occurring in a variety of minerals present in the tailings. Physicochemical and mineralogical characteristics of tailings such as total concentrations of chemical elements, pH, ratio of acid-producing to acid-neutralizing minerals, and primary and secondary mineral phases are very important factors that control the actual release of potentially toxic metals and metalloids from the tailings to the environment. The aims of this study are the determination of geochemical and mineralogical characteristics of tailings deposited in voluminous impoundment situated near the village of Markušovce (eastern Slovakia) and identification of the processes controlling the mobility of selected toxic metals (Cu, Hg) and metalloids (As, Sb). The studied tailings have unique features in comparison with the other tailings investigated previously because of the specific mineral assemblage primarily consisting of barite, siderite, quartz, and minor sulfides. To meet the aims, samples of the tailings were collected from 3 boreholes and 15 excavated pits and subjected to bulk geochemical analyses (i.e., determination of chemical composition, pH, Eh, acid generation, and neutralization potentials) combined with detailed mineralogical characterization using optical microscopy, X-ray diffraction (XRD), electron microprobe analysis (EMPA), and micro-X-ray diffraction (μ-XRD). Additionally, the geochemical and mineralogical factors controlling the transfer of potentially toxic elements from tailings to waters were also determined using short-term batch test (European norm EN 12457), sampling of drainage waters and speciation-equilibrium calculations performed with PHREEQC. The tailings mineral assemblage consists of siderite, barite, quartz, and dolomite. Sulfide minerals constitute only a minor proportion of the tailings

Single and combined metal contamination in coastal environments in China: current status and potential ecological risk evaluation.

Science.gov (United States)

Manzoor, Romana; Zhang, Tingwan; Zhang, Xuejiao; Wang, Min; Pan, Jin-Fen; Wang, Zhumei; Zhang, Bo

2018-01-01

With the development of industrialization and urbanization, metal and metalloid pollution is one of the most serious environmental problems in China. Current contamination status of metals and metalloid and their potential ecological risks along China's coasts were reviewed in the present paper by a comprehensive study on metal contents in marine waters and sediments in the past few decades. The priority metals/metalloid cadmium (Cd), mercury (Hg), chromium (Cr), lead (Pb), and arsenic (As), which were the target elements of the designated project "Comprehensive Prevention and Control of Heavy Metal Pollution" issued by the Chinese government in 2011, were selected considering their high toxicity, persistence, and prevalent existence in coastal environment. Commonly used environmental quality evaluation methods for single and combined metals were compared, and we accordingly suggest the comprehensive approach of joint utilization of the Enrichment Factor and Effect Range Median combined with Pollution Load Index and Mean Effect Range Median Quotient (EEPME); this battery of guidelines may provide consistent, internationally comparable, and accurate understanding of the environment pollution status of combined metals/metalloid and their potential ecological risk.

Synthesis, structure, and characterization of two new bismuth(III) selenite/tellurite nitrates: [(Bi3O2)(SeO3)2](NO3) and [Bi(TeO3)](NO3)

Science.gov (United States)

Meng, Chang-Yu; Wei, Ming-Fang; Geng, Lei; Hu, Pei-Qing; Yu, Meng-Xia; Cheng, Wen-Dan

2016-07-01

Two new bismuth(III) selenite/tellurite nitrates, [(Bi3O2)(SeO3)2](NO3) and [Bi(TeO3)](NO3), have been synthesized by conventional facile hydrothermal method at middle temperature 200 °C and characterized by single-crystal X-ray diffraction, powder diffraction, UV-vis-NIR optical absorption spectrum, infrared spectrum and thermal analylsis. Both [(Bi3O2)(SeO3)2](NO3) and [Bi(TeO3)](NO3) crystallize in the monoclinic centronsymmetric space group P21/c with a=9.9403(4) Å, b=9.6857(4) Å, c=10.6864(5) Å, β=93.1150(10)° for [(Bi3O2)(SeO3)2](NO3) and a=8.1489(3) Å, b=9.0663(4) Å, c=7.4729(3) Å, β=114.899(2)° for Bi(TeO3)(NO3), respectively. The two compounds, whose structures are composed of three different asymmetric building units, exhibit two different types of structures. The structure of [(Bi3O2)(SeO3)2](NO3) features a three-dimensional (3D) bismuth(III) selenite cationic tunnel structure [(Bi3O2)(SeO3)2] 3∞ with NO3- anion group filling in the 1D tunnel along b axis. The structure of [Bi(TeO3)](NO3) features 2D bismuth(III) tellurite [Bi(TeO3)2]2∞ layers separated by NO3- anion groups. The results of optical diffuse-reflectance spectrum measurements and electronic structure calculations based on density functional theory methods show that the two compounds are wide band-gap semiconductors.

Optical analysis of RE(3+) (RE = Pr(3) (+) , Er(3) (+) and Nd(3) (+) ):cadmium lead boro tellurite glasses.

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Giridhar, P; Bhushana Reddy, M; Neelima, G; Ramanaiah, R; Nagamuni Reddy, K; Sahadeva Reddy, V; Sudhakar Reddy, B

2016-09-01

This article reports on the optical characterization of Pr(3) (+) -, Er(3) (+) - and Nd(3) (+) -doped cadmium lead boro tellurite (CLBT) glasses prepared using the melt quenching method. The visible-near infrared (Vis-NIR) absorption spectra of these glasses were analyzed systematically. On measuring the NIR emission spectra of Er(3) (+) :CLBT glasses, a broad emission band centered at 1536 nm ((4) I13 /2  → (4) I15 /2 ) was observed, as were three NIR emission bands at 900 nm ((4) F3 /2  → (4) I9 /2 ), 1069 nm ((4) F3 /2  → (4) I11 /2 ) and 1338 nm ((4) F3 /2  → (4) I13 /2 ) from Nd(3) (+) :CLBT glasses and an NIR emission band at 1334 nm ((1) G4  → (3) H5 ) from Pr(3) (+) :CLBT glasses at an excitation wavelength (λex ) of 514.5 nm (Ar(+) laser). Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Au70S20(PPh3)12: an intermediate sized metalloid gold cluster stabilized by the Au4S4 ring motif and Au-PPh3 groups.

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Kenzler, Sebastian; Schrenk, Claudio; Frojd, Andrew R; Häkkinen, Hannu; Clayborne, Andre Z; Schnepf, Andreas

2018-01-02

Reducing (Ph 3 P)AuSC(SiMe 3 ) 3 with l-Selectride® gives the medium-sized metalloid gold cluster Au 70 S 20 (PPh 3 ) 12 . Computational studies show that the phosphine bound Au-atoms not only stabilize the electronic structure of Au 70 S 20 (PPh 3 ) 12 , but also behave as electron acceptors leading to auride-like gold atoms on the exterior.

Characterization of iron and manganese minerals and their associated microbiota in different mine sites to reveal the potential interactions of microbiota with mineral formation.

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Park, Jin Hee; Kim, Bong-Soo; Chon, Chul-Min

2018-01-01

Different environmental conditions such as pH and dissolved elements of mine stream induce precipitation of different minerals and their associated microbial community may vary. Therefore, mine precipitates from various environmental conditions were collected and their associated microbiota were analyzed through metagenomic DNA sequencing. Various Fe and Mn minerals including ferrihydrite, schwertmannite, goethite, birnessite, and Mn-substituted δ-FeOOH (δ-(Fe 1-x , Mn x )OOH) were found in the different environmental conditions. The Fe and Mn minerals were enriched with toxic metal(loid)s including As, Cd, Ni and Zn, indicating they can act as scavengers of toxic metal(loid)s in mine streams. Under acidic conditions, Acidobacteria was dominant phylum and Gallionella (Fe oxidizing bacteria) was the predominant genus in these Fe rich environments. Manganese oxidizing bacteria, Hyphomicrobium, was found in birnessite forming environments. Leptolyngbya within Cyanobacteria was found in Fe and Mn oxidizing environments, and might contribute to Fe and Mn oxidation through the production of molecular oxygen. The potential interaction of microbial community with minerals in mine sites can be traced by analysis of microbial community in different Fe and Mn mineral forming environments. Iron and Mn minerals contribute to the removal of toxic metal(loid)s from mine water. Therefore, the understanding characteristics of mine precipitates and their associated microbes helps to develop strategies for the management of contaminated mine water. Copyright © 2017 Elsevier Ltd. All rights reserved.

Cerium(IV) Tellurite Halides [Ce ₂ Te ₇ O ₁₇ ]X ₂ (X = Cl ^– or Br ^– ): The First Cerium-Containing Cationic Frameworks

Energy Technology Data Exchange (ETDEWEB)

Lin, Jian [Department of Civil; amp, Environmental Engineering & amp, Earth Sciences and Department of Chemistry and Biochemistry, University of Notre Dame, 156 Fitzpatrick Hall, Notre; Diwu, Juan [Department of Civil; amp, Environmental Engineering & amp, Earth Sciences and Department of Chemistry and Biochemistry, University of Notre Dame, 156 Fitzpatrick Hall, Notre; Cross, Justin N. [Department of Civil; amp, Environmental Engineering & amp, Earth Sciences and Department of Chemistry and Biochemistry, University of Notre Dame, 156 Fitzpatrick Hall, Notre; Villa, Eric M. [Department of Civil; amp, Environmental Engineering & amp, Earth Sciences and Department of Chemistry and Biochemistry, University of Notre Dame, 156 Fitzpatrick Hall, Notre; Albrecht-Schmitt, Thomas E. [Department of Chemistry

2012-09-13

Two isotypic cerium tellurite halides with the formulas [Ce2Te7O17]Cl2 and [Ce2Te7O17]Br2 have been synthesized hydrothermally via the reactions of CeCl3 and CeBr3 with TeO2. The structures of these compounds feature a cationic inorganic framework. The CeIV dimers are bound by a novel 3D Te7O176– building unit, forming an unusual hexagonal-bipyramidal environment around CeIV.

The formal combination of three singlet biradicaloid entities to a singlet hexaradicaloid metalloid Ge14[Si(SiMe3)3]5[Li(THF)2]3 cluster.

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Schenk, Christian; Kracke, Andreas; Fink, Karin; Kubas, Adam; Klopper, Wim; Neumaier, Marco; Schnöckel, Hansgeorg; Schnepf, Andreas

2011-03-02

The reaction of GeBr with LiSi(SiMe(3))(3) leads to the metalloid cluster compound [(THF)(2)Li](3)Ge(14)[Si(SiMe(3))(3)](5) (1). After the introduction of a first cluster of this type, in which 14 germanium atoms form an empty polyhedron, [(THF)(2)Li](3)Ge(14)[Ge(SiMe(3))(3)](5) (2), we present here further investigations on 1 to obtain preliminary insight into its chemical and bonding properties. The molecular structure of 1 is determined via X-ray crystal structure solution using synchrotron radiation. The electronic structure of the Ge(14) polyhedron is further examined by quantum chemical calculations, which indicate that three singlet biradicaloid entities formally combine to yield the singlet hexaradicaloid character of 1. Moreover, the initial reactions of 1 after elimination of the [Li(THF)(2)](+) groups by chelating ligands (e.g., TMEDA or 12-crown-4) are presented. Collision induced dissociation experiments in the gas phase, employing FT-ICR mass spectrometry, lead to the elimination of the singlet biradicaloid Ge(5)H(2)[Si(SiMe(3))(3)](2) cluster. The unique multiradicaloid bonding character of the metalloid cluster 1 might be used as a model for reactions and properties in the field of surface science and nanotechnology.

Effects of heavy metals/metalloids contamination of soils on micronucleus induction in Tradescantia pallida

Directory of Open Access Journals (Sweden)

Neelima Meravi

2013-06-01

Full Text Available The present study was conducted in GGV campus, Bilaspur in which heavy metals/metalloids speciation of soil (for Cr, Fe, Ni, Cd and Pb was performed for assessing the genotoxicity of these metals. The metals concentrations were measured with the help of AAS 7000 (Shimadzu and the standard solution was prepared using standard metal solution of Inorganic Ventures. The concentrations of Cr, Fe, Ni, Cd and Pb (in ug/100 g soil were 12.4, 33.9, 3.1, 0.07 and 2.4 respectively. The flowers of Tradescantia pallida plants growing in this soil were taken and their micronucleus (Trad-MCN bioassay was performed. Trad-MCN bioassay was performed using the protocols established by Ma (1981. The study revealed that at these concentrations of metals micronuclei (stained objects that were smaller than the nuclei and not connected to the nuclei are classified as MCN were formed. Therefore it can be inferred from the present study that soil of GGV campus is genotoxic for the Tradescantia pallida.

Comparative proteomic analysis reveals heart toxicity induced by chronic arsenic exposure in rats.

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Huang, Qingyu; Xi, Guochen; Alamdar, Ambreen; Zhang, Jie; Shen, Heqing

2017-10-01

Arsenic is a widespread metalloid in the environment, which poses a broad spectrum of adverse effects on human health. However, a global view of arsenic-induced heart toxicity is still lacking, and the underlying molecular mechanisms remain unclear. By performing a comparative quantitative proteomic analysis, the present study aims to investigate the alterations of proteome profile in rat heart after long-term exposure to arsenic. As a result, we found that the abundance of 81 proteins were significantly altered by arsenic treatment (35 up-regulated and 46 down-regulated). Among these, 33 proteins were specifically associated with cardiovascular system development and function, including heart development, heart morphology, cardiac contraction and dilation, and other cardiovascular functions. It is further proposed that the aberrant regulation of 14 proteins induced by arsenic would disturb cardiac contraction and relaxation, impair heart morphogenesis and development, and induce thrombosis in rats, which is mediated by the Akt/p38 MAPK signaling pathway. Overall, these findings will augment our knowledge of the involved mechanisms and develop useful biomarkers for cardiotoxicity induced by environmental arsenic exposure. Copyright © 2017 Elsevier Ltd. All rights reserved.

Widely tunable dispersive wave generation and soliton self-frequency shift in a tellurite microstructured optical fiber pumped near the zero dispersion wavelength

International Nuclear Information System (INIS)

Zhang, Lei; Tuan, Tong-Hoang; Liu, Lai; Gao, Wei-Qing; Kawamura, Harutaka; Suzuki, Takenobu; Ohishi, Yasutake

2015-01-01

Widely tunable dispersive waves (DW) and Raman solitons are generated in a tellurite microstructured optical fiber (TMOF) by pumping in the anomalous dispersion regime, close to the zero dispersion wavelength (ZDW). The DW can be generated from 1518.3 nm to 1315.5 nm, and the soliton can be shifted from the pump wavelength of 1570 nm to 1828.7 nm, by tuning the average pump power from 3 dBm to 17.5 dBm. After the average pump power is increased to 18.8 dBm, two DW peaks (centered at 1323 nm and 1260 nm) and three soliton peaks (centered at 1762 nm, 1825 nm, and 1896 nm) can be observed simultaneously. When the average pump power is greater than 23.4 dBm, a flat and broadband supercontinuum (SC) can be formed by the combined nonlinear effects of soliton self-frequency shift (SSFS), DW generation, and cross phase modulation (XPM). (paper)

Role of lithium ions on the physical, structural and optical properties of zinc boro tellurite glasses

Science.gov (United States)

Rani, S.; Ahlawat, N.; Parmar, R.; Dhankhar, S.; Kundu, R. S.

2018-01-01

Lithium zinc boro tellurite glasses with compositions xLi2O-(100-x) [0.25ZnO-0.15B2O3-0.60TeO2] [where x = 0, 5, 10, 15 and 20 mol%] have been prepared by melt-quench technique. The amorphous nature of the prepared system is ascertained by X-ray diffraction. The density and molar volume are found to decrease with the increase in concentration of Li2O. The differential scanning calorimetry is used to calculate the glass transition temperature (Tg) and the observed values are found to be decreased. The IR and Raman spectra indicate that Li2O acts as a network modifier in the glass matrix. In the present system, tellurium exists as TeO4 and TeO3, B2O3 in the form of BO4 and BO3 and zinc oxide exists as ZnO4 structural units. The values of the optical band gap are estimated from the fitting of Mott and Davis's and model. A better convergence is achieved between experimental observed spectra of absorption coefficient and hydrogenic excitonic model. The optical band gap energy increases, whereas refractive index and molar refractivity follow the reverse trend with Li2O. The range of metallization criterion suggests that these glasses may be a potential candidate for nonlinear optical materials.

Correlations in metal release profiles following sorption by Lemna minor.

Science.gov (United States)

Üçüncü Tunca, Esra; Ölmez, Tolga T; Özkan, Alper D; Altındağ, Ahmet; Tunca, Evren; Tekinay, Turgay

2016-08-02

Following the rapid uptake of contaminants in the first few hours of exposure, plants typically attempt to cope with the toxic burden by releasing part of the sorbed material back into the environment. The present study investigates the general trends in the release profiles of different metal(loid)s in the aquatic macrophyte Lemna minor and details the correlations that exist between the release of metal(loid) species. Water samples with distinct contamination profiles were taken from Nilüfer River (Bursa, Turkey), Yeniçağa Lake (Bolu, Turkey), and Beyşehir Lake (Konya, Turkey) and used for release studies; 36 samples were tested in total. Accumulation and release profiles were monitored over five days for 11 metals and a metalloid ((208)Pb, (111)Cd, (52)Cr,(53)Cr,(60)Ni,(63)Cu,(65)Cu,(75)As,(55)Mn, (137)Ba, (27)Al, (57)Fe, (66)Zn,(68)Zn) and correlation, cluster and principal component analyses were employed to determine the factors that affect the release of these elements. Release profiles of the tested metal(loid)s were largely observed to be distinct; however, strong correlations have been observed between certain metal pairs (Cr/Ni, Cr/Cu, Zn/Ni) and principal component analysis was able to separate the metal(loid)s into three well-resolved groups based on their release.

The Escherichia coli BtuE protein functions as a resistance determinant against reactive oxygen species.

Directory of Open Access Journals (Sweden)

Felipe A Arenas

2011-01-01

Full Text Available This work shows that the recently described Escherichia coli BtuE peroxidase protects the bacterium against oxidative stress that is generated by tellurite and by other reactive oxygen species elicitors (ROS. Cells lacking btuE (ΔbtuE displayed higher sensitivity to K(2TeO(3 and other oxidative stress-generating agents than did the isogenic, parental, wild-type strain. They also exhibited increased levels of cytoplasmic reactive oxygen species, oxidized proteins, thiobarbituric acid reactive substances, and lipoperoxides. E. coli ΔbtuE that was exposed to tellurite or H(2O(2 did not show growth changes relative to wild type cells either in aerobic or anaerobic conditions. Nevertheless, the elimination of btuE from cells deficient in catalases/peroxidases (Hpx(- resulted in impaired growth and resistance to these toxicants only in aerobic conditions, suggesting that BtuE is involved in the defense against oxidative damage. Genetic complementation of E. coli ΔbtuE restored toxicant resistance to levels exhibited by the wild type strain. As expected, btuE overexpression resulted in decreased amounts of oxidative damage products as well as in lower transcriptional levels of the oxidative stress-induced genes ibpA, soxS and katG.

Transcriptome profiling of genes and pathways associated with arsenic toxicity and tolerance in Arabidopsis

Science.gov (United States)

2014-01-01

Background Arsenic (As) is a toxic metalloid found ubiquitously in the environment and widely considered an acute poison and carcinogen. However, the molecular mechanisms of the plant response to As and ensuing tolerance have not been extensively characterized. Here, we report on transcriptional changes with As treatment in two Arabidopsis accessions, Col-0 and Ws-2. Results The root elongation rate was greater for Col-0 than Ws-2 with As exposure. Accumulation of As was lower in the more tolerant accession Col-0 than in Ws-2. We compared the effect of As exposure on genome-wide gene expression in the two accessions by comparative microarray assay. The genes related to heat response and oxidative stresses were common to both accessions, which indicates conserved As stress-associated responses for the two accessions. Most of the specific response genes encoded heat shock proteins, heat shock factors, ubiquitin and aquaporin transporters. Genes coding for ethylene-signalling components were enriched in As-tolerant Col-0 with As exposure. A tolerance-associated gene candidate encoding Leucine-Rich Repeat receptor-like kinase VIII (LRR-RLK VIII) was selected for functional characterization. Genetic loss-of-function analysis of the LRR-RLK VIII gene revealed altered As sensitivity and the metal accumulation in roots. Conclusions Thus, ethylene-related pathways, maintenance of protein structure and LRR-RLK VIII-mediated signalling may be important mechanisms for toxicity and tolerance to As in the species. Here, we provide a comprehensive survey of global transcriptional regulation for As and identify stress- and tolerance-associated genes responding to As. PMID:24734953

Characterization of the cytosolic distribution of priority pollutant metals and metalloids in the digestive gland cytosol of marine mussels: seasonal and spatial variability.

Science.gov (United States)

Strižak, Zeljka; Ivanković, Dušica; Pröfrock, Daniel; Helmholz, Heike; Cindrić, Ana-Marija; Erk, Marijana; Prange, Andreas

2014-02-01

Cytosolic profiles of several priority pollutant metals (Cu, Cd, Zn, Pb) and metalloid As were analyzed in the digestive gland of the mussel (Mytilus galloprovincialis) sampled at locations with different environmental pollution levels along the Croatian coast in the spring and summer season. Size-exclusion chromatography (SEC) connected to inductively coupled plasma mass spectrometry (ICP-MS) was used to determine selected elements bound to cytosolic biomolecules separated based on their molecular size. Copper, cadmium and zinc eluted mostly associated with high molecular weight (HMW) and medium molecular weight (MMW) biomolecules, but with a more prominent elution in the MMW peak at polluted locations which were probably associated with the 20 kDa metallothionein (MT). Elution of all three metals within this peak was also strongly correlated with cytosolic Cd as strong inducer of MT. Lead mostly eluted in HMW biomolecule range, but in elevated cytosolic Pb concentrations, significant amount eluted in low molecular weight (LMW) biomolecules. Arsenic, on the other hand eluted almost completely in LMW range, but we could not distinguish specific molecular weight biomolecules which would be predominant in detoxification mechanism. Seasonal variability in element abundance within specific peaks was present, although not in the same extent, for all elements and locations, especially for As. The results confirm the suitability of the distribution of selected metals/metalloids among different cytosolic ligands as potential indicator for metal exposure. Obtained findings can also serve as guidelines for further separation and characterization of specific cytosolic metal-binding biomolecules. © 2013.

Toxicity assessment of boron (B) by Lemna minor L. and Lemna gibba L. and their possible use as model plants for ecological risk assessment of aquatic ecosystems with boron pollution.

Science.gov (United States)

Gür, Nurcan; Türker, Onur Can; Böcük, Harun

2016-08-01

As many of the metalloid-based pollutants, the boron (B) toxicity issues have aroused more and more global attentions, especially concerning drinking water sources which flow through boron-rich areas. Therefore, feasible and innovative approaches are required in order to assess B toxicity in aquatic ecosystems. In this study, the toxic effects of B on Lemna minor L. and Lemna gibba L. were investigated using various endpoints including number of fronds, growth rates, dry biomass and antioxidants enzymatic activities. Lemna species were exposed to B concentrations of 2 (control), 4, 8, 16, 32, 64 and 128 mg L(-1) for a test period of 7 days. The results demonstrated that plant growth was significantly reduced when the B concentration reached 16 mg L(-1). Furthermore, our results also concluded that among the antioxidative enzymes, SOD, APX and GPX can serve as important biomarkers for B-rich environment. The present results suggested that L. minor and L. gibba are very useful model plants for phytoremediation of low-B contaminated wastewater and they are also suitable options for B biomonitoring due to high phototoxic sensitivity against B. In this respect, the scientific insight of the present study is to fill the gaps in the research about the use of L. minor and L. gibba in ecotoxicological research associated with B toxicity. Copyright © 2016 Elsevier Ltd. All rights reserved.

Levels of PM2.5/PM10 and associated metal(loid)s in rural households of Henan Province, China.

Science.gov (United States)

Wu, Fuyong; Wang, Wei; Man, Yu Bon; Chan, Chuen Yu; Liu, Wenxin; Tao, Shu; Wong, Ming Hung

2015-04-15

Although a majority of China's rural residents use solid fuels (biomass and coal) for household cooking and heating, clean energy such as electricity and liquid petroleum gas is becoming more popular in the rural area. Unfortunately, both solid fuels and clean energy could result in indoor air pollution. Daily respirable particulate matter (PM≤10 μm) and inhalable particulate matter (PM≤2.5 μm) were investigated in kitchens, sitting rooms and outdoor area in rural Henan during autumn (Sep to Oct 2012) and winter (Jan 2013). The results showed that PM (PM2.5 and PM10) and associated metal(loid)s varied among the two seasons and the four types of domestic energy used. Mean concentrations of PM2.5 and PM10 in kitchens during winter were 59.2-140.4% and 30.5-145.1% higher than those during autumn, respectively. Similar with the trends of PM2.5 and PM10, concentrations of As, Pb, Zn, Cd, Cu, Ni and Mn in household PM2.5 and PM10 were apparently higher in winter than those in autumn. The highest mean concentrations of PM2.5 and PM10 (368.5 and 588.7 μg m(-3)) were recorded in sitting rooms in Baofeng during winter, which were 5.7 and 3.9 times of corresponding health based guidelines for PM2.5 and PM10, respectively. Using coal can result in severe indoor air pollutants including PM and associated metal(loid)s compared with using crop residues, electricity and gas in rural Henan Province. Rural residents' exposure to PM2.5 and PM10 would be roughly reduced by 13.5-22.2% and 8.9-37.7% via replacing coal or crop residues with electricity. The present study suggested that increased use of electricity as domestic energy would effectively improve indoor air quality in rural China. Copyright © 2015 Elsevier B.V. All rights reserved.

[Raman spectroscopic study of binary PbO-TeO2 glasses].

Science.gov (United States)

Huang, Li; You, Jing-Lin; Chen, Hui; Jiang, Guo-Chang

2008-07-01

Raman spectra of lead tellurite glasses and their melts were measured. Results show that four coordinate tellurite units convert into three coordinate units with increasing the concentration of PbO, and the number of non-bridging oxygen bonds (NBO) increases accordingly in this system. Three spectral peaks in the high frequency range were assigned to stretching vibration of bridging oxygen in four coordinate tellurite units (Q(b)), stretching vibration of non-bridging oxygen in four coordinate tellurite units (Q(nb)) and in three coordinate tellurite units (T(nb)). The relative density of four coordinate structure units decreases and the three coordinate tellurite units considerably exist in tellurite glasses when the concentration of PbO > 50%. Besides, the Raman frequencies of the three species' peaks become blue-shifted because of the temperature induced crystallization at high temperature, and the peak intensities increase and the peaks sharpen. The peaks merge together and become much broader while the glass is heated above the melting point because of multiple microstructure units coexisting.

Selenium Treatment Technologies

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Selenium (Se) is a metalloid that is a dietary requirement in small quantities, but toxic at higher quantities. It also is known to bioaccumulate. In oxic environments, it exists as selenate (+6) and selenite (+4), both of which are soluble. Selenite will sorb more strongly to...

Structural, thermal and optical absorption features of heavy metal oxides doped tellurite rich glasses

Science.gov (United States)

Kaky, Kawa M.; Lakshminarayana, G.; Baki, S. O.; Kityk, I. V.; Taufiq-Yap, Y. H.; Mahdi, M. A.

In order to improve tellurite glass stability to be applicable for optical fiber amplifier applications, glasses with the composition of (70 - x)TeO2. (10)ZnO. (10)WO3. (5)Na2O. (5)TiO2. (x)Bi2O3 (x = 1, 2, 3, 4, and 5 mol%) have been produced and characterized using the related methods. Structural properties were investigated using X-ray diffraction (XRD) which confirms the non-crystalline structure and scanning electron microscopy (SEM) micrographs also confirm the XRD results. The energy dispersive X-ray (EDX) analysis profiles show that all the mentioned elements are present in the prepared glasses. Following the IR spectra, all the tellurium bonds such as stretching vibrations of TeO4 tbp and TeO3/TeO3+1 unit are revealed. Raman spectra confirm the presence of different functional groups, actually, it shows bands mainly in four spectral regions: R1 (65-150) cm-1, R2 (280-550) cm-1, R3 (880-950) cm-1 and R4 (916-926) cm-1 and the identified bands are assigned to respective molecular groups. The thermal study was carried out using Differential scanning calorimetry (DSC) which indicates good thermal stability of the synthesized glasses with increasing Bi concentration. From the optical absorption spectra, we evaluated cut-off edge wavelengths and found increasing cutoff wavelength with an increase in Bi2O3 concentration. In the UV-Visible region, optical band gap energy and allowed transitions were investigated using three methods; direct, indirect, and absorption spectrum fitting (ASF), and band gaps from indirect and ASF were matched.

Metal(loid)s behaviour in soils amended with nano zero-valent iron as a function of pH and time.

Science.gov (United States)

Vítková, Martina; Rákosová, Simona; Michálková, Zuzana; Komárek, Michael

2017-01-15

Nano zero-valent iron (nZVI) is currently investigated as a stabilising amendment for contaminated soils. The effect of pH (4-8) and time (48 and 192 h) on the behaviour of nZVI-treated Pb-Zn and As-contaminated soil samples was assessed. Additionally, soil leachates were subsequently used to study the direct interaction between soil solution components and nZVI particles in terms of mineralogical changes and contaminant retention. A typical U-shaped leaching trend as a function of pH was observed for Cd, Pb and Zn, while As was released predominantly under alkaline conditions. Oxidising conditions prevailed, so pH was the key controlling parameter rather than redox conditions. Generally, longer contact time resulted in increased soluble concentrations of metal(loid)s. However, the stabilisation effect of nZVI was only observed after the direct soil leachate-nZVI interactions, showing enhanced redox and sorption processes for the studied metals. A significant decrease of dissolved As concentrations was observed for both experimental soils, but with different efficiencies depending on neutralisation capacity, organic matter content or solid fractionation of As related to the origin of the soils. Scorodite (FeAsO 4 ·2H 2 O) was predicted as a potential solubility-controlling mineral phase for As. Sorption of metal(loid)s onto secondary Fe- and Al-(oxyhydr)oxides (predicted to precipitate at pH > 5) represents an important scavenger mechanism. Moreover, transmission electron microscopy confirmed the retention of Zn and Pb under near-neutral and alkaline conditions by newly formed Fe oxides or aluminosilicates. This study shows that the efficiency of nZVI application strongly depends not only on soil pH-Eh conditions and contaminant type, but also on the presence of organic matter and other compounds such as Al/Fe/Mn oxyhydroxides and clay minerals. Copyright © 2016 Elsevier Ltd. All rights reserved.

Synthesis, structure, and characterization of two new bismuth(III) selenite/tellurite nitrates: [(Bi{sub 3}O{sub 2})(SeO{sub 3}){sub 2}](NO{sub 3}) and [Bi(TeO{sub 3})](NO{sub 3})

Energy Technology Data Exchange (ETDEWEB)

Meng, Chang-Yu; Wei, Ming-Fang [Department of Chemistry and Materials, Yulin Normal University,Yulin, Guangxi 537000 (China); Geng, Lei, E-mail: lgeng.cn@gmail.com [Department of Materials Science and Engineering, Huaibei Normal University, Huaibei, Anhui 235000 (China); Hu, Pei-Qing; Yu, Meng-Xia [Department of Chemistry and Materials, Yulin Normal University,Yulin, Guangxi 537000 (China); Cheng, Wen-Dan [State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China)

2016-07-15

Two new bismuth(III) selenite/tellurite nitrates, [(Bi{sub 3}O{sub 2})(SeO{sub 3}){sub 2}](NO{sub 3}) and [Bi(TeO{sub 3})](NO{sub 3}), have been synthesized by conventional facile hydrothermal method at middle temperature 200 °C and characterized by single-crystal X-ray diffraction, powder diffraction, UV–vis–NIR optical absorption spectrum, infrared spectrum and thermal analylsis. Both [(Bi{sub 3}O{sub 2})(SeO{sub 3}){sub 2}](NO{sub 3}) and [Bi(TeO3)](NO3) crystallize in the monoclinic centronsymmetric space group P2{sub 1}/c with a=9.9403(4) Å, b=9.6857(4) Å, c=10.6864(5) Å, β=93.1150(10)° for [(Bi{sub 3}O{sub 2})(SeO{sub 3}){sub 2}](NO{sub 3}) and a=8.1489(3) Å, b=9.0663(4) Å, c=7.4729(3) Å, β=114.899(2)° for Bi(TeO3)(NO3), respectively. The two compounds, whose structures are composed of three different asymmetric building units, exhibit two different types of structures. The structure of [(Bi{sub 3}O{sub 2})(SeO{sub 3}){sub 2}](NO{sub 3}) features a three-dimensional (3D) bismuth(III) selenite cationic tunnel structure [(Bi{sub 3}O{sub 2})(SeO{sub 3}){sub 2}] {sup 3}{sub ∞} with NO{sub 3}{sup −} anion group filling in the 1D tunnel along b axis. The structure of [Bi(TeO{sub 3})](NO{sub 3}) features 2D bismuth(III) tellurite [Bi(TeO{sub 3}){sub 2}]{sup 2}{sub ∞} layers separated by NO{sub 3}{sup −} anion groups. The results of optical diffuse-reflectance spectrum measurements and electronic structure calculations based on density functional theory methods show that the two compounds are wide band-gap semiconductors. - Graphical abstract: Two novel bismuth{sup III} selenite/tellurite nitrates [(Bi{sub 3}O{sub 2})(SeO{sub 3}){sub 2}](NO{sub 3}) with 3D tunnel structure and [Bi(TeO{sub 3})](NO{sub 3}) with 2D layer structure have been firstly synthesized and characterized. Display Omitted - Highlights: • Two novel bismuth{sup III} nitrates [(Bi{sub 3}O{sub 2})(SeO{sub 3}){sub 2}](NO{sub 3}) and [Bi(TeO{sub 3})](NO{sub 3}) were firstly

Heavy metals and metalloid content in vegetables and soil collected from the gardens of Zagreb, Croatia.

Science.gov (United States)

Puntarić, Dinko; Vidosavljević, Domagoj; Gvozdić, Vlatka; Puntarić, Eda; Puntarić, Ida; Mayer, Dijana; Bosnir, Jasna; Lasić, Dario; Jergović, Matijana; Klarić, Ivana; Vidosavljević, Marina; Krivdić, Ivancica

2013-09-01

Aim of this study was to determine concentration of Pb, Cd, As and Hg in green leafy vegetables and soil in the urban area of Zagreb, Croatia and to determine if there is a connection between the contamination of soil and vegetables. Green leafy vegetables and soil samples were taken from the gardens located in the outskirts of the city. Concentrations of Pb, Cd, As and Hg were determined by atomic absorption spectrometry; showing that average concentrations of metals and metalloids in vegetables and in soil, regardless of the location of sampling were below the maximum allowed concentration (MAC). The analysis determined that metal concentrations in only nine vegetable samples (9%) were above maximum allowed values prescribed by national and European legislation (three with higher concentrations of Pb, one with a higher concentration of Cd and five with higher concentrations of Hg). Concentrations of contaminants present in the analysed samples, in general, are lower than the ones published in similar studies. The final distribution and concentration of contaminants in vegetables of Zagreb, besides industry and traffic, is affected by the dominant wind direction.

Metals and metalloids in the water-bloom-forming cyanobacteria and ambient water from Nanquan coast of Taihu Lake, China.

Science.gov (United States)

Su, Yanping; Liu, Hongbo; Yang, Jian

2012-08-01

Concentrations of 12 metal(oid)s were investigated in the bloom-forming cyanobacteria and ambient water samples collected monthly between March 2009 and February 2010 at the Nanquan coast of Taihu Lake, China. The metal(oid) concentrations in ambient water decreased in the order Fe > Zn > Ni ≈ As ≈ Cu > Mn > Ag > Cr > Se > Cd > Co > Tl, while those in cyanobacteria followed a sequence Fe > Mn > Zn > Cu ≈ Ni > Co > Ag > Cr ≈ As > Cd > Tl > Se. The metal(loid) burdens removed by cyanobacteria were estimated as 164 t Fe, 12.4 t Mn, 3.6 t Zn, 2.0 t Ni, 2.0 t Cu, 0.5 t As, 0.5 t Cr, 0.4 t Cd, 0.9 t Ag, 1.1 t Co, 0.2 t Tl, and 0.09 t Se during the 2008-2010 bloom seasons.

Current role of ICP-MS in clinical toxicology and forensic toxicology: a metallic profile.

Science.gov (United States)

Goullé, Jean-Pierre; Saussereau, Elodie; Mahieu, Loïc; Guerbet, Michel

2014-08-01

As metal/metalloid exposure is inevitable owing to its omnipresence, it may exert toxicity in humans. Recent advances in metal/metalloid analysis have been made moving from flame atomic absorption spectrometry and electrothermal atomic absorption spectrometry to the multi-elemental inductively coupled plasma (ICP) techniques as ICP atomic emission spectrometry and ICP-MS. ICP-MS has now emerged as a major technique in inorganic analytical chemistry owing to its flexibility, high sensitivity and good reproducibility. This in depth review explores the ICP-MS metallic profile in human toxicology. It is now routinely used and of great importance, in clinical toxicology and forensic toxicology to explore biological matrices, specifically whole blood, plasma, urine, hair, nail, biopsy samples and tissues.

Spectroscopic properties of Er3+/Yb3+ Co-doped zinc boro-tellurite glasses for 1.5 xB5m broadband optical amplifiers

Science.gov (United States)

Suthanthirakumar, P.; Karthikeyan, P.; Vijayakumar, R.; Marimuthu, K.

2015-06-01

A new series of Er3+/Yb3+ co-doped Zinc boro-tellurite glasses with the chemical composition (40-x-y)B2O3+ 25TeO2+20ZnO+15BaO+xYb2O3+yEr2O3 (where x = 0.1, 0.5, 1 and 3; y =1 in wt %) were prepared by melt quenching technique and their spectroscopic behavior were studied through UV-Vis-NIR absorption and NIR luminescence measurements. The bonding parameters (β ¯ and δ) and Judd-Ofelt (JO) intensity parameters Ωλ (λ=2, 4 and 6) have been calculated from the band positions of the absorption spectra. A broad near-infrared emission band at 1540 nm with a full width at half maximum around 80 nm was observed from the NIR luminescence spectra by monitoring an excitation at 980 nm. The absorption cross-section and emission cross-section for the4I13/2→4I15/2 transition of the Er3+ ions were also determined using McCumber theory and the results were discussed and reported.

Seasonal variation and annual trends of metals and metalloids in the blood of the Little Penguin (Eudyptula minor).

Science.gov (United States)

Finger, Annett; Lavers, Jennifer L; Orbell, John D; Dann, Peter; Nugegoda, Dayanthi; Scarpaci, Carol

2016-09-15

Little Penguins (Eudyptula minor) are high-trophic coastal feeders and are effective indicators of bioavailable pollutants in their foraging zones. Here, we present concentrations of metals and metalloids in blood of 157 Little Penguins, collected over three years and during three distinct seasons (breeding, moulting and non-breeding) at two locations: the urban St Kilda colony and the semi-rural colony at Phillip Island, Victoria, Australia. Penguin metal concentrations were foremostly influenced by location (St Kilda>Phillip Island for non-essential elements) and differed among years and seasons at both locations, reflecting differences in seasonal metal bioaccumulation or seasonal exposure through prey. Mean blood mercury concentrations showed an increasing annual trend and a negative correlation with flipper length at St Kilda. Notably, this study is the first to report on blood metal concentrations during the different stages of moult, showing the mechanism of non-essential metal mobilisation and detoxification. Copyright © 2016 Elsevier Ltd. All rights reserved.

Exiguobacterium mediated arsenic removal and its protective effect against arsenic induced toxicity and oxidative damage in freshwater fish, Channa striata

Directory of Open Access Journals (Sweden)

Neha Pandey

2015-01-01

Full Text Available Arsenic is a toxic metalloid existing widely in the environment, and its removal from contaminated water has become a global challenge. The use of bacteria in this regard finds a promising solution. In the present study, Exiguobacterium sp. As-9, which is an arsenic resistant bacterium, was selected with respect to its arsenic removal efficiency. Quantification of arsenic in the water treated with bacterium showed that Exiguobacterium efficiently removed up to 99% of arsenic in less than 20 h. In order to reveal the possible effect of this bacterium in removal of arsenic from water and protecting fishes from the detrimental effects of arsenic, we initiated a range of studies on fresh water fish, Channa striata. It was observed that the fishes introduced into bacteria treated water displayed no symptoms of arsenic toxicity which was marked by a decreased oxidative damage, whereas the fishes exposed to arsenic revealed a significant (p < 0.05 increase in the oxidative stress together with the elevated levels of malondialdehyde. Determination of the bioaccumulation of arsenic in the liver tissues of C. striata using hydride generation atomic absorption spectrophotometry (HG-AAS revealed an increased As(III accumulation in the fishes exposed to arsenic whereas the arsenic level in the control and bacteria treated fishes were found below the detectable limit. In conclusion, this study presents the strategies of bacterial arsenic removal with possible directions for future research.

Speciation and bioavailability of lead in complementary medicines

International Nuclear Information System (INIS)

Bolan, S.; Naidu, R.; Kunhikrishnan, A.; Seshadri, B.; Ok, Y.S.; Palanisami, T.; Dong, M.; Clark, I.

2016-01-01

Complementary medicines have associated risks which include toxic heavy metal(loid) and pesticide contamination. The objective of this study was to examine the speciation and bioavailability of lead (Pb) in selected complementary medicines. Six herbal and six ayurvedic medicines were analysed for: (i) total heavy metal(loid) contents including arsenic (As), cadmium (Cd), Pb and mercury (Hg); (ii) speciation of Pb using sequential fractionation and extended x-ray absorption fine structure (EXAFS) techniques; and (iii) bioavailability of Pb using a physiologically-based in vitro extraction test (PBET). The daily intake of Pb through the uptake of these medicines was compared with the safety guidelines for Pb. The results indicated that generally ayurvedic medicines contained higher levels of heavy metal(loid)s than herbal medicines with the amount of Pb much higher than the other metal(loid)s. Sequential fractionation indicated that while organic-bound Pb species dominated the herbal medicines, inorganic-bound Pb species dominated the ayurvedic medicines. EXAFS data indicated the presence of various Pb species in ayurvedic medicines. This implies that Pb is derived from plant uptake and inorganic mineral input in herbal and ayurvedic medicines, respectively. Bioavailability of Pb was higher in ayurvedic than herbal medicines, indicating that Pb added as a mineral therapeutic input is more bioavailable than that derived from plant uptake. There was a positive relationship between soluble Pb fraction and bioavailability indicating that solubility is an important factor controlling bioavailability. The daily intake values for Pb as estimated by total and bioavailable metal(loid) contents are likely to exceed the safe threshold level in certain ayurvedic medicines. This research demonstrated that Pb toxicity is likely to result from the regular intake of these medicines which requires further investigation. - Highlights: • Pb species in complementary medicines was

Arsenic-transforming microbes and their role in biomining processes

OpenAIRE

Drewniak, L.; Sklodowska, A.

2013-01-01

It is well known that microorganisms can dissolve different minerals and use them as sources of nutrients and energy. The majority of rock minerals are rich in vital elements (e.g., P, Fe, S, Mg and Mo), but some may also contain toxic metals or metalloids, like arsenic. The toxicity of arsenic is disclosed after the dissolution of the mineral, which raises two important questions: (1) why do microorganisms dissolve arsenic-bearing minerals and release this metal into the environment in a tox...

Integrated phytobial remediation for sustainable management of arsenic in soil and water.

Science.gov (United States)

Roy, Madhumita; Giri, Ashok K; Dutta, Sourav; Mukherjee, Pritam

2015-02-01

Arsenic (As), cited as the most hazardous substance by the U.S. Agency for Toxic Substance and Disease Registry (ATSDR, 2005), is an ubiquitous metalloid which when ingested for prolonged periods cause extensive health effects leading to ultimate untimely death. Plants and microbes can help mitigate soil and groundwater As problem since they have evolved elaborate detoxification machineries against this toxic metalloid as a result of their coexistence with this since the origin of life on earth. Utilization of the phytoremediation and bioremediation potential of the plants and microbes, respectively, is now regarded as two innovative tools that encompass biology, geology, biotechnology and allied sciences with cutting edge applications for sustainable mitigation of As epidemic. Discovery of As hyperaccumulating plants that uptake and concentrate large amounts of this toxic metalloid in their shoots or roots offered new hope to As phytoremediation, solar power based nature's own green remediation. This review focuses on how phytoremediation and bioremediation can be merged together to form an integrated phytobial remediation which could synergistically achieve the goal of large scale removal of As from soil, sediment and groundwater and overcome the drawbacks of the either processes alone. The review also points to the feasibility of the introduction of transgenic plants and microbes that bring new hope for more efficient treatment of As. The review identifies one critical research gap on the importance of remediation of As contaminated groundwater not only for drinking purpose but also for irrigation purpose and stresses that more research should be conducted on the use of constructed wetland, one of the most suitable areas of application of phytobial remediation. Finally the review has narrowed down on different phytoinvestigation and phytodisposal methods, which constitute the most essential and the most difficult part of pilot scale and field scale applications

Accumulation patterns and risk assessment of metals and metalloid in muscle and offal of free-range chickens, cattle and goat in Benin City, Nigeria.

Science.gov (United States)

Ogbomida, Emmanuel Temiotan; Nakayama, Shouta M M; Bortey-Sam, Nesta; Oroszlany, Balazs; Tongo, Isioma; Enuneku, Alex Ajeh; Ozekeke, Ogbeide; Ainerua, Martins Oshioriamhe; Fasipe, Iriagbonse Priscillia; Ezemonye, Lawrence Ikechukwu; Mizukawa, Hazuki; Ikenaka, Yoshinori; Ishizuka, Mayumi

2018-04-30

The use of free range animals for monitoring environmental health offers opportunities to detect exposure and assess the toxicological effects of pollutants in terrestrial ecosystems. Potential human health risk of dietary intake of metals and metalloid via consumption of offal and muscle of free range chicken, cattle and goats by the urban population in Benin City was evaluated. Muscle, gizzard, liver and kidney samples were analyzed for Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Cd, and Pb concentrations using inductively coupled plasma mass spectrometer (ICP-MS) while Hg was determined using Hg analyzer. Mean concentrations of metals (mg/kg ww) varied significantly depending upon the tissues and animal species. Human health risk estimations for children and adults showed estimated daily intake (EDI) values of tissues below oral reference dose (RfD) threshold for non essential metals Cd, As, Pb and Hg thus strongly indicating no possible health risk via consumption of animal based food. Calculated Hazard quotient (THQ) was less than 1 (< 1) for all the metals analyzed for both adult and children. However, Cd and As had the highest value of THQ suggestive of possible health risk associated with continuous consumption of Cd and As contaminated animal based foods. Hazard Index (HI) for additive effect of metals was higher in chicken liver and gizzard for children and chicken liver for adults. Thus, HI indicated that chicken liver and gizzard may contribute significantly to adult and children dietary exposure to heavy metals. Principal component analysis (PCA) showed a clear species difference in metal accumulation between chickens and the ruminants. This study provides baseline data for future studies and also valuable evidence of anthropogenic impacts necessary to initiate national and international policies for control of heavy metal and metalloid content in food items. Copyright © 2017. Published by Elsevier Inc.

The study of the mechanism of arsenite toxicity in respiration-deficient cells reveals that NADPH oxidase-derived superoxide promotes the same downstream events mediated by mitochondrial superoxide in respiration-proficient cells

Energy Technology Data Exchange (ETDEWEB)

Guidarelli, Andrea; Fiorani, Mara; Carloni, Silvia; Cerioni, Liana; Balduini, Walter; Cantoni, Orazio, E-mail: orazio.cantoni@uniurb.it

2016-09-15

We herein report the results from a comparative study of arsenite toxicity in respiration-proficient (RP) and -deficient (RD) U937 cells. An initial characterization of these cells led to the demonstration that the respiration-deficient phenotype is not associated with apparent changes in mitochondrial mass and membrane potential. In addition, similar levels of superoxide (O{sub 2}{sup .-}) were generated by RP and RD cells in response to stimuli specifically triggering respiratory chain-independent mitochondrial mechanisms or extramitochondrial, NADPH-oxidase dependent, mechanisms. At the concentration of 2.5 μM, arsenite elicited selective formation of O{sub 2}{sup .-} in the respiratory chain of RP cells, with hardly any contribution of the above mechanisms. Under these conditions, O{sub 2}{sup .-} triggered downstream events leading to endoplasmic reticulum (ER) stress, autophagy and apoptosis. RD cells challenged with similar levels of arsenite failed to generate O{sub 2}{sup .-} because of the lack of a functional respiratory chain and were therefore resistant to the toxic effects mediated by the metalloid. Their resistance, however, was lost after exposure to four fold greater concentrations of arsenite, coincidentally with the release of O{sub 2}{sup .-} mediated by NADPH oxidase. Interestingly, extramitochondrial O{sub 2}{sup .-} triggered the same downstream events and an identical mode of death previously observed in RP cells. Taken together, the results obtained in this study indicate that arsenite toxicity is strictly dependent on O{sub 2}{sup .-} availability that, regardless of whether generated in the mitochondrial or extramitochondrial compartments, triggers similar downstream events leading to ER stress, autophagy and apoptosis. - Highlights: • Mitochondrial superoxide mediates arsenite toxicity in respiration-proficient cells. • NADPH-derived superoxide mediates arsenite toxicity in respiration-deficient cells. • Arsenite causes apoptosis

Continuous removal and recovery of tellurium in an upflow anaerobic granular sludge bed reactor

International Nuclear Information System (INIS)

Mal, Joyabrata; Nancharaiah, Yarlagadda V.; Maheshwari, Neeraj; Hullebusch, Eric D. van; Lens, Piet N.L.

2017-01-01

Highlights: • Tellurite bioreduction coupled to recovery of biogenic Te(0) nanocrystals. • First report on continuous tellurite removal in a UASB reactor. • Biogenic Te(0) was mainly associated with loosely-bound EPS of granular sludge. • Repeated exposure to tellurite caused compositional changes in the EPS matrix. - Abstract: Continuous removal of tellurite (TeO 3 2− ) from synthetic wastewater and subsequent recovery in the form of elemental tellurium was studied in an upflow anaerobic granular sludge bed (UASB) reactor operated at 30 °C. The UASB reactor was inoculated with anaerobic granular sludge and fed with lactate as carbon source and electron donor at an organic loading rate of 0.6 g COD L −1 d −1 . After establishing efficient and stable COD removal, the reactor was fed with 10 mg TeO 3 2− L −1 for 42 d before increasing the influent concentration to 20 mg TeO 3 2− L −1 . Tellurite removal (98 and 92%, respectively, from 10 and 20 mg Te L −1 ) was primarily mediated through bioreduction and most of the removed Te was retained in the bioreactor. Characterization using XRD, Raman spectroscopy, SEM-EDX and TEM confirmed association of tellurium with the granular sludge, typically in the form of elemental Te(0) deposits. Furthermore, application of an extracellular polymeric substances (EPS) extraction method to the tellurite reducing sludge recovered up to 78% of the tellurium retained in the granular sludge. This study demonstrates for the first time the application of a UASB reactor for continuous tellurite removal from tellurite-containing wastewater coupled to elemental Te(0) recovery.

Metal and metalloid contamination in roadside soil and wild rats around a Pb-Zn mine in Kabwe, Zambia

Energy Technology Data Exchange (ETDEWEB)

Nakayama, Shouta M.M.; Ikenaka, Yoshinori; Hamada, Kyohei [Laboratory of Toxicology, Department of Environmental Veterinary Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Kita 18, Nishi 9, Kita-ku, Sapporo 060-0818 (Japan); Muzandu, Kaampwe; Choongo, Kennedy [Department of Biomedical Studies, School of Veterinary Medicine, University of Zambia, P.O. Box 32379, Lusaka (Zambia); Teraoka, Hiroki; Mizuno, Naoharu [Department of Toxicology, School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu 069-8501 (Japan); Ishizuka, Mayumi, E-mail: ishizum@vetmed.hokudai.ac.j [Laboratory of Toxicology, Department of Environmental Veterinary Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Kita 18, Nishi 9, Kita-ku, Sapporo 060-0818 (Japan)

2011-01-15

Metal (Cr, Co, Cu, Zn, Cd, Pb, Ni) and metalloid (As) accumulation was studied in roadside soil and wild rat (Rattus sp.) samples from near a Pb-Zn mine (Kabwe, Zambia) and the capital city of Zambia (Lusaka). The concentrations of the seven metals and As in the soil samples and Pb in the rat tissue samples were quantified using atomic absorption spectroscopy. The concentrations of Pb, Zn, Cu, Cd, and As in Kabwe soil were much higher than benchmark values. Geographic Information System analysis indicated the source of metal pollution was mining and smelting activity. Interestingly, the area south of the mine was more highly contaminated even though the prevailing wind flow was westward. Wild rats from Kabwe had much higher tissue concentrations of Pb than those from Lusaka. Their body weight and renal Pb levels were negatively correlated, which suggests that mining activity might affect terrestrial animals in Kabwe. - The area around Kabwe, Zambia is highly polluted with metals and As. Wild rats from this area had high tissue concentrations of Pb and decreased body weight.

Pollution and health risk assessment of industrial and residential area based on metal and metalloids contents in soil and sediment samples from and around the petrochemical industry, Serbia

Science.gov (United States)

Relic, Dubravka; Sakan, Sanja; Andjelkovic, Ivan; Djordjevic, Dragana

2017-04-01

Within this study the investigation of pollution state of metal and metalloids contamination in soils and sediments samples of the petrochemical and nearby residential area is present. The pseudo-total concentrations of Ba, Cd, Co, Cu, Cr, Mn, Ni, Pb, V, Zn, As, Hg, and Se were monitored with ICP/OES. The pollution indices applied in this work, such as the enrichment factor, the pollution load index, the total enrichment factor, and the ecological risk index showed that some of the soil and sediment samples were highly polluted by Hg, Ba, Pb, Cd, Cr Cu and Zn. The highest pollution indices were calculated for Hg in samples from the petrochemical area: chloralkali plant, electrolysis factory, mercury disposal area, and in samples from the waste channel. The pollution indices of the samples from the residential area indicated that this area is not polluted by investigated elements. Besides the pollution indices, the metal and metalloids concentrations were used in the equations for calculating the health risk criteria. We calculate no carcinogenic and carcinogenic risks for the composite worker and residential people by usage adequate equations. In analyzed samples, the no carcinogenic risks were lower than 1. The highest values of carcinogenic risk were obtained in sediment samples from the waste channel within the petrochemical industry and the metal that mostly contributes to the highest carcinogenic risk is Cr. Correlation analysis of pollution indices and carcinogenic risks calculated from the residential area samples showed good correlations while this is not the case for an industrial area.

Enhanced 2.7 μm emission from Er3+ doped oxyfluoride tellurite glasses for a diode-pump mid-infrared laser

Directory of Open Access Journals (Sweden)

F. F. Zhang

2014-04-01

Full Text Available The influence of fluoride and shielding gas (O2 or Ar on the physical and spectroscopic properties of Er3+ doped TeO2-ZnO-ZnF2 glass system is investigated. The larger electronegativity of F than O accounts for the gradual decrease of refractive index, density, and J-O parameters with increasing ZnF2. An analysis on Fourier transform infrared transmission spectra reveals that the absorption coefficient of OH− around 3 μm as low as 0.247 cm−1 can be achieved when 30 mol% ZnF2 containing sample is treated with Ar gas during glass melting process. The reduction of OH− groups combined with the low multiphonon relaxation rate (207 s−1 contributes to the enhanced emissions at 1.5 and 2.7 μm, along with prolonged lifetimes of 4I11/2 and 4I13/2 levels. A high branching ratio (17.95% corresponding to the Er3+: 4I11/2 → 4I13/2 transition, the large absorption and emission cross section (0.44 × 10−20 cm2 and 0.45 × 10−20 cm2, and good gain cross section demonstrate that oxyfluoride tellurite glass could be a promising material for a diode-pump 2.7 μm fiber laser.

Continuous removal and recovery of tellurium in an upflow anaerobic granular sludge bed reactor

Energy Technology Data Exchange (ETDEWEB)

Mal, Joyabrata, E-mail: joyabrata2006@gmail.com [UNESCO-IHE, Westvest 7, 2611 AX Delft (Netherlands); Nancharaiah, Yarlagadda V. [Biofouling and Biofilm Processes Section, Water and Steam Chemistry Division, Bhabha Atomic Research Centre, Kalpakkam, 603102, Tamil Nadu (India); Homi Bhabha National Institute, Anushakti Nagar Complex, Mumbai 400094 (India); Maheshwari, Neeraj [CNRS UMR 7338, BMBI University de Technologie Compiegne, 60200 Compiegne (France); Hullebusch, Eric D. van [UNESCO-IHE, Westvest 7, 2611 AX Delft (Netherlands); Université Paris-Est, Laboratoire Géomatériaux et Environnement (LGE), EA 4508, UPEM, 77454, Marne-la-Vallée (France); Lens, Piet N.L. [UNESCO-IHE, Westvest 7, 2611 AX Delft (Netherlands); Department of Chemistry and Bioengineering, Tampere University of Technology, P.O-Box 541, Tampere (Finland)

2017-04-05

Highlights: • Tellurite bioreduction coupled to recovery of biogenic Te(0) nanocrystals. • First report on continuous tellurite removal in a UASB reactor. • Biogenic Te(0) was mainly associated with loosely-bound EPS of granular sludge. • Repeated exposure to tellurite caused compositional changes in the EPS matrix. - Abstract: Continuous removal of tellurite (TeO{sub 3}{sup 2−}) from synthetic wastewater and subsequent recovery in the form of elemental tellurium was studied in an upflow anaerobic granular sludge bed (UASB) reactor operated at 30 °C. The UASB reactor was inoculated with anaerobic granular sludge and fed with lactate as carbon source and electron donor at an organic loading rate of 0.6 g COD L{sup −1} d{sup −1}. After establishing efficient and stable COD removal, the reactor was fed with 10 mg TeO{sub 3}{sup 2−} L{sup −1} for 42 d before increasing the influent concentration to 20 mg TeO{sub 3}{sup 2−} L{sup −1}. Tellurite removal (98 and 92%, respectively, from 10 and 20 mg Te L{sup −1}) was primarily mediated through bioreduction and most of the removed Te was retained in the bioreactor. Characterization using XRD, Raman spectroscopy, SEM-EDX and TEM confirmed association of tellurium with the granular sludge, typically in the form of elemental Te(0) deposits. Furthermore, application of an extracellular polymeric substances (EPS) extraction method to the tellurite reducing sludge recovered up to 78% of the tellurium retained in the granular sludge. This study demonstrates for the first time the application of a UASB reactor for continuous tellurite removal from tellurite-containing wastewater coupled to elemental Te(0) recovery.

Mobility of engineered inorganic nanoparticles in porous media

Science.gov (United States)

Metreveli, George; Heidmann, Ilona; Schaumann, Gabriele Ellen

2013-04-01

Besides the excellent properties and great potential for various industrial, medical, pharmaceutical, cosmetic, and life science applications, engineered inorganic nanoparticles (EINP) can show also disadvantages concerning increasing risk potential with increasing application, if they are released in the environmental systems. EINP can influence microbial activity and can show toxic effects (Fabrega et al., 2009). Similar to the inorganic natural colloids, EINP can be transported in soil and groundwater systems (Metreveli et al., 2005). Furthermore, due to the large surface area and high sorption and complex formation capacity, EINP can facilitate transport of different contaminants. In this study the mobility behaviour of EINP and their effect on the transport of different metal(loid) species in water saturated porous media was investigated. For these experiments laboratory column system was used. The column was filled with quartz sand. The interactions between EINP and metal(loid)s were characterised by coupling of asymmetrical flow field flow fractionation (AF4) with inductively coupled plasma mass spectrometer (ICP-MS). As EINP laponite (synthetic three layer clay mineral), and as metal(loid)s Cu, Pb, Zn, Pt and As were used. In AF4 experiments sorption of metal(loid)s on the surface of EINP could be observed. The extent of interactions was influenced by pH value and was different for different metal(loid)s. Laboratory column experiments showed high mobility of EINP, which facilitated transport of most of metal(loid)s in water saturated porous media. Furthermore the migration of synthetic silver nanoparticles in natural soil columns was determined in leaching experiments. Acknowledgement Financial support by German Research Council (DFG) and Max-Buchner-Research Foundation (MBFSt) is gratefully acknowledged. We thank Karlsruhe Institute of Technology (KIT) for the opportunity to perform the column and AF4 experiments. References: Fabrega, J., Fawcett, S. R

Mechanism(s of Toxic Action of Zn2+ and Selenite: A Study on AS-30D Hepatoma Cells and Isolated Mitochondria

Directory of Open Access Journals (Sweden)

Elena A. Belyaeva

2011-01-01

Full Text Available Mitochondria of AS-30D rat ascites hepatoma cells are found to be the main target for Zn2+ and sodium selenite (Na2SeO3. High [mu]M concentrations of Zn2+ or selenite were strongly cytotoxic, killing the AS-30D cells by both apoptotic and necrotic ways. Both Zn2+ and selenite produced strong changes in intracellular generation of reactive oxygen species (ROS and the mitochondrial dysfunction via the mitochondrial electron transport chain (mtETC disturbance, the membrane potential dissipation, and the mitochondrial permeability transition pore opening. The significant distinctions in toxic action of Zn2+ and selenite on AS-30D cells were found. Selenite induced a much higher intracellular ROS level (the early event compared to Zn2+ but a lower membrane potential loss and a lower decrease of the uncoupled respiration rate of the cells, whereas the mtETC disturbance was the early and critical event in the mechanism of Zn2+ cytotoxicity. Sequences of events manifested in the mitochondrial dysfunction produced by the metal/metalloid under test are compared with those obtained earlier for Cd2+, Hg2+, and Cu2+ on the same model system.

Novel Arsenic Nanoparticles Are More Effective and Less Toxic than As (III) to Inhibit Extracellular and Intracellular Proliferation of Leishmania donovani

Science.gov (United States)

Chakraborty, Sudipta; Bhar, Kaushik; Saha, Sandip; Chakrabarti, Rajarshi; Pal, Anjali

2014-01-01

Visceral leishmaniasis, a vector-borne tropical disease that is threatening about 350 million people worldwide, is caused by the protozoan parasite Leishmania donovani. Metalloids like arsenic and antimony have been used to treat diseases like leishmaniasis caused by the kinetoplastid parasites. Arsenic (III) at a relatively higher concentration (30 μg/mL) has been shown to have antileishmanial activity, but this concentration is reported to be toxic in several experimental mammalian systems. Nanosized metal (0) particles have been shown to be more effective than their higher oxidation state forms. There is no information so far regarding arsenic nanoparticles (As-NPs) as an antileishmanial agent. We have tested the antileishmanial properties of the As-NPs, developed for the first time in our laboratory. As-NPs inhibited the in vitro growth, oxygen consumption, infectivity, and intramacrophage proliferation of L. donovani parasites at a concentration which is about several fold lower than that of As (III). Moreover, this antileishmanial activity has comparatively less cytotoxic effect on the mouse macrophage cell line. It is evident from our findings that As-NPs have more potential than As (III) to be used as an antileishmanial agent. PMID:25614827

Structural and optical investigations on Dy{sup 3+} doped boro-tellurite glasses

Energy Technology Data Exchange (ETDEWEB)

Maheshvaran, K. [Department of Physics, Gandhigram Rural University, Gandhigram 624 302 (India); Marimuthu, K., E-mail: mari_ram2000@yahoo.com [Department of Physics, Gandhigram Rural University, Gandhigram 624 302 (India)

2011-07-07

Highlights: > The structural and optical properties have been studied through XRD, FTIR, absorption, luminescence and decay time measurements. > The prepared glasses posses ionic nature and the ionic nature gradually increases when the tellurium di-oxide content increases in the host matrix. > The radiative properties such as radiative transition probability (A), radiative lifetime ({tau}{sub rad}), stimulated emission cross section ({sigma}{sub P}{sup E}) and branching ratios ({beta}{sub R}) are calculated for the {sup 4}F{sub 9/2} {yields} {sup 6}H{sub 15/2}, {sup 6}H{sub 13/2} and {sup 6}H{sub 11/2} transitions. > The decay curve of the {sup 4}F{sub 9/2} level of Dy{sup 3+}:BXTD glasses is well fitted for single exponential. > The stimulated emission cross section for the Dy{sup 3+}:B3TD glass possess higher value and therefore it is suggested for suitable laser applications. - Abstract: Dy{sup 3+} doped boro-tellurite glasses were prepared by following melt quenching technique with the chemical composition (69 - x)H{sub 3}BO{sub 3} + xTeO{sub 2} + 15Mg{sub 2}CO{sub 3} + 15K{sub 2}CO{sub 3} + 1Dy{sub 2}O{sub 3} (where x = 0, 10, 20, 30 and 40 wt%) by varying the tellurium dioxide content. The structural and optical properties have been studied through XRD, FTIR, absorption, luminescence and decay time measurements. The XRD pattern has been used to confirm the amorphous nature of the prepared glasses. The FTIR spectra reveals the presence of B-O vibrations and Te-O stretching modes of TeO{sub 3} and TeO{sub 6} units in the prepared glasses. The UV-vis-NIR absorption spectra were used to calculate the oscillator strength, bonding parameters ({beta}-bar and {delta}) and Judd-Ofelt intensity parameters ({Omega}{sub {lambda},} {lambda} = 2, 4 and 6). The radiative transition probability (A), stimulated emission cross section ({sigma}{sub P}{sup E}) and the experimental, calculated branching ratios ({beta}{sub R}) have been calculated from the luminescence spectra

Optical characterization of Eu3+ and Tb3+ ions doped cadmium lithium alumino fluoro boro tellurite glasses.

Science.gov (United States)

Raju, K Vemasevana; Sailaja, S; Raju, C Nageswara; Reddy, B Sudhakar

2011-06-01

This article reports on the development and spectral results of Eu(3+) and Tb(3+) ions doped cadmium lithium alumino fluoro boro tellurite (CLiAFBT) glasses in the following composition. 40TeO2-30B2O3-10CdO-10Li2O-10AlF3 (Hostglass) (40-x)TeO2-30B2O3-10CdO-10Li2O-10AlF3-xEu2O3 (40-x)TeO2-30B2O3-10CdO-10Li2O-10AlF3-xTb4O7 where x=0.25, 0.50, 0.75, 1.0, 1.25 mol%. Glass amorphous nature and thermal properties have been studied using the XRD and DSC profiles. From the emission spectra of Eu(3+):glasses, five emission transitions have been observed at 578 nm, 592 nm, 612 nm, 653 nm, 701 nm and are assigned to the transitions (5)D(0)→(7)F(0), (7)F(1,)(7)F(2), (7)F(3) and (7)F(4), respectively, with λ(exci)=392 nm ((7)F(0)→(5)L(6)). In case of Tb(3+):glasses, four emission transitions ((5)D(4)→(7)F(6,)(7)F(5), (7)F(4) and (7)F(3)) are observed at 488 nm, 543 nm, 584 nm and 614 nm, respectively, with λ(exci)=376 nm. Decay curves and energy level diagrams have been plotted to evaluate the life times and to analyze the emission mechanism. Copyright © 2011 Elsevier B.V. All rights reserved.

Structural, optical absorption and photoluminescence spectral studies of Sm3+ ions in Alkaline-Earth Boro Tellurite glasses

Science.gov (United States)

Siva Rama Krishna Reddy, K.; Swapna, K.; Mahamuda, Sk.; Venkateswarlu, M.; Srinivas Prasad, M. V. V. K.; Rao, A. S.; Prakash, G. Vijaya

2018-05-01

Sm3+ ions doped Alkaline-Earth Boro Tellurite (AEBT) glasses were prepared by using conventional melt quenching technique and characterized using the spectroscopic techniques such as FT-IR, optical absorption, emission and decay spectral measurements to understand their utility in optoelectronic devices. From absorption spectra, the bonding parameters, nephelauxetic ratios were determined to know the nature of bonding between Sm3+ ions and its surrounding ligands. From the measured oscillator strengths, the Judd-Ofelt (J-O) intensity parameters were evaluated and in turn used to estimate various radiative parameters for the fluorescent levels of Sm3+ ions in AEBT glasses. The PL spectra of Sm3+ ions exhibit three emission bands corresponding to the transitions 4G5/2 → 6H5/2, 6H7/2 and 6H9/2 in the visible region for which the emission cross-sections and branching ratios were evaluated. The decay spectral profiles measured for 4G5/2 → 6H7/2 transition showed single exponential for lower concentration and non-exponential for higher concentration of doped rare earth ion in the as prepared glasses. Conversion of decay spectral profiles from single to non-exponential have been analyzed using Inokuti-Hirayama (I-H) model to understand the energy transfer mechanism involved in the decay process. CIE Chromaticity coordinates were measured using emission spectral data to identify the exact region of emission from the as-prepared glasses. From the evaluated radiative parameters, emission cross-sections and quantum efficiencies, it was observed that AEBT glass with 1 mol% of Sm3+ ions is more suitable for designing optoelectronic devices.

Implementation of ferric hydroxide-based media for removal of toxic metalloids

Science.gov (United States)

Szlachta, Małgorzata; Wójtowicz, Patryk

2017-11-01

Effective removal of inorganic arsenic species is possible by application of the sorption technique with the use of iron-based sorbents. This study investigates the removal of arsenic(III) and arsenic(V) from an aqueous solution by application of a granular ferric hydroxide-based sorbent. The performance of tested media was evaluated based on the batch and fixed-bed adsorption studies. The efficiency of the process was determined with various treatment times, adsorbent doses, initial concentrations of arsenic and various solution temperatures. The obtained adsorption data were fitted with pseudo-first and second-order kinetic models and Langmuir and Freundlich isotherm equations. It was observed that the overall arsenite removal was lower when compared to the arsenate, and all tested operating parameters influenced the process efficiency. The experiments under dynamic conditions showed high treatment capacity and stability of tested adsorbent over a long period of time.

Solid–gaseous phase transformation of elemental contaminants during the gasification of biomass

Energy Technology Data Exchange (ETDEWEB)

Jiang, Ying; Ameh, Abiba [Centre for Bioenergy & Resource Management, School of Energy, Environment & Agrifood, Cranfield University, Cranfield MK43 0AL (United Kingdom); Lei, Mei [Centre for Environmental Remediation, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101 (China); Duan, Lunbo [Key Laboratory of Energy Thermal Conversion and Control, Ministry of Education, School of Energy and Environment, Southeast University, Nanjing 210096 (China); Longhurst, Philip, E-mail: P.J.Longhurst@cranfield.ac.uk [Centre for Bioenergy & Resource Management, School of Energy, Environment & Agrifood, Cranfield University, Cranfield MK43 0AL (United Kingdom)

2016-09-01

Disposal of plant biomass removed from heavy metal contaminated land via gasification achieves significant volume reduction and can recover energy. However, these biomass often contain high concentrations of heavy metals leading to hot-corrosion of gasification facilities and toxic gaseous emissions. Therefore, it is of significant interest to gain a further understanding of the solid–gas phase transition of metal(loid)s during gasification. Detailed elemental analyses (C, H, O, N and key metal/metalloid elements) were performed on five plant species collected from a contaminated site. Using multi-phase equilibria modelling software (MTDATA), the analytical data allows modelling of the solid/gas transformation of metal(loid)s during gasification. Thermodynamic modelling based on chemical equilibrium calculations was carried out in this study to predict the fate of metal(loid) elements during typical gasification conditions and to show how these are influenced by metal(loid) composition in the biomass and operational conditions. As, Cd, Zn and Pb tend to transform to their gaseous forms at relatively low temperatures (< 1000 °C). Ni, Cu, Mn and Co converts to gaseous forms within the typical gasification temperature range of 1000–1200 °C. Whereas Cr, Al, Fe and Mg remain in solid phase at higher temperatures (> 1200 °C). Simulation of pressurised gasification conditions shows that higher pressures increase the temperature at which solid-to-gaseous phase transformations takes place. - Highlights: • Disposal of plants removed from metal contaminated land raises environmental concerns • Plant samples collected from a contaminated site are shown to contain heavy metals. • Gasification is suitable for plant disposal and its emission is modelled by MTDATA. • As, Cd, Zn and Pb are found in gaseous emissions at a low process temperature. • High pressure gasification can reduce heavy metal elements in process emission.

Thyroid cancer in toxic and non-toxic multinodular goiter

Directory of Open Access Journals (Sweden)

Cerci C

2007-01-01

Full Text Available Background : Many authors have claimed that hyperthyroidism protects against thyroid cancer and believed that the incidence of malignancy is lower in patients with toxic multinodular goiter (TMG than in those with non-toxic multinodular goiter. But in recent studies, it was reported that the incidence of malignancy with TMG is not as low as previously thought. Aim : To compare the thyroid cancer incidence in patients with toxic and non-toxic multinodular goiter. Settings and Design : Histology reports of patients treated surgically with a preoperative diagnosis of toxic and non-toxic multinodular goiter were reviewed to identify the thyroid cancer incidence. Patients having a history of neck irradiation or radioactive iodine therapy were excluded from the study. Materials and Methods : We reviewed 294 patients operated between 2001-2005 from toxic and non-toxic multinodular goiter. One hundred and twenty-four of them were toxic and 170 were non-toxic. Hyperthyroidism was diagnosed by elevated tri-iodothyroinine / thyroxine ratios and low thyroid-stimulating hormone with clinical signs and symptoms. All patients were evaluated with ultrasonography and scintigraphy and fine needle aspiration biopsy. Statistical Analysis Used : Significance of the various parameters was calculated by using ANOVA test. Results : The incidence of malignancy was 9% in the toxic and 10.58% in the non-toxic multinodular goiter group. Any significant difference in the incidence of cancer and tumor size between the two groups could not be detected. Conclusions : The incidence of malignancy in toxic multinodular goiter is not very low as thought earlier and is nearly the same in non-toxic multinodular goiter.

Global DNA methylation in earthworms: a candidate biomarker of epigenetic risks related to the presence of metals/metalloids in terrestrial environments.

Science.gov (United States)

Santoyo, María Maldonado; Flores, Crescencio Rodríguez; Torres, Adolfo Lopez; Wrobel, Kazimierz; Wrobel, Katarzyna

2011-10-01

In this work, possible relationships between global DNA methylation and metal/metalloid concentrations in earthworms have been explored. Direct correlation was observed between soil and tissue As, Se, Sb, Zn, Cu, Mn, Ag, Co, Hg, Pb (p< 0.05). Speciation results obtained for As and Hg hint at the capability of earthworms for conversion of inorganic element forms present in soil to methylated species. Inverse correlation was observed between the percentage of methylated DNA cytosines and total tissue As, As + Hg, As + Hg + Se + Sb (β = -0.8456, p = 0.071; β = -0.9406, p = 0.017; β = -0.9526, p = 0.012 respectively), as well as inorganic As + Hg (β = -0.8807, p = 0.049). It was concluded that earthworms would be particularly helpful as bioindicators of elements undergoing in vivo methylation and might also be used to assess the related risk of epigenetic changes in DNA methylation. Copyright © 2011 Elsevier Ltd. All rights reserved.

Multi-analytical assessment of iron and steel slag characteristics to estimate the removal of metalloids from contaminated water.

Science.gov (United States)

Mercado-Borrayo, B M; Schouwenaars, R; González-Chávez, J L; Ramírez-Zamora, R M

2013-01-01

A multi-analytical approach was used to develop a mathematical regression model to calculate the residual concentration of borate ions in water present at high initial content, as a function of the main physicochemical, mineralogical and electrokinetic characteristics after adsorption on five different types of iron and steel slag. The analytical techniques applied and slag properties obtained in this work were: X-ray Fluorescence for the identification of the main chemical compounds, X-ray Diffraction to determine crystalline phases, physical adsorption of nitrogen for the quantification of textural properties and zeta-potential for electrokinetic measurements of slag particles. Adsorption tests were carried out using the bottle-point technique and a highly concentrated borate solution (700 mg B/L) at pH 10, with a slag dose of 10 g/L. An excellent correlation between the residual concentration of boron and three independent variables (content of magnesium oxide, zeta potential and specific surface area) was established for the five types of slag tested in this work. This shows that the methodology based on a multi-analytical approach is a very strong and useful tool to estimate the performance of iron and steel slag as adsorbent of metalloids.

Reduction of chalcogen oxyanions and generation of nanoprecipitates by the photosynthetic bacterium Rhodobacter capsulatus

Energy Technology Data Exchange (ETDEWEB)

Borghese, Roberto, E-mail: roberto.borghese@unibo.it [Department of Pharmacy and Biotechnology, University of Bologna (Italy); Baccolini, Chiara; Francia, Francesco [Department of Pharmacy and Biotechnology, University of Bologna (Italy); Sabatino, Piera [Department of Chemistry G. Ciamician, University of Bologna (Italy); Turner, Raymond J. [Department of Biological Sciences, University of Calgary, Calgary, Alberta (Canada); Zannoni, Davide, E-mail: davide.zannoni@unibo.it [Department of Pharmacy and Biotechnology, University of Bologna (Italy)

2014-03-01

Graphical abstract: - Highlights: • R. capsulatus cells produce extracellular chalcogens nanoprecipitates when lawsone is present. • Lawsone acts as a redox mediator from reducing equivalents to tellurite and selenite. • Nanoprecipitates production depends on carbon source and requires metabolically active cells. • Te{sup 0} and Se{sup 0} nanoprecipitates are identified by X-ray diffraction (XRD) spectroscopy. - Abstract: The facultative photosynthetic bacterium Rhodobacter capsulatus is characterized in its interaction with the toxic oxyanions tellurite (Te{sup IV}) and selenite (Se{sup IV}) by a highly variable level of resistance that is dependent on the growth mode making this bacterium an ideal organism for the study of the microbial interaction with chalcogens. As we have reported in the past, while the oxyanion tellurite is taken up by R. capsulatus cells via acetate permease and it is reduced to Te{sup 0} in the cytoplasm in the form of splinter-like black intracellular deposits no clear mechanism was described for Se{sup 0} precipitation. Here, we present the first report on the biotransformation of tellurium and selenium oxyanions into extracellular Te{sup 0} and Se{sup 0}nanoprecipitates (NPs) by anaerobic photosynthetically growing cultures of R. capsulatus as a function of exogenously added redox-mediator lawsone, i.e. 2-hydroxy-1,4-naphthoquinone. The NPs formation was dependent on the carbon source used for the bacterial growth and the rate of chalcogen reduction was constant at different lawsone concentrations, in line with a catalytic role for the redox mediator. X-ray diffraction (XRD) analysis demonstrated the Te{sup 0} and Se{sup 0} nature of the nanoparticles.

Al2O3 influence on structural, elastic, thermal properties of Yb(3+) doped Ba-La-tellurite glass: evidence of reduction in self-radiation trapping at 1μm emission.

Science.gov (United States)

Balaji, S; Biswas, K; Sontakke, A D; Gupta, G; Ghosh, D; Annapurna, K

2014-12-10

Ba-La-tellurite glasses doped with Yb(3+) ions have been prepared through melt quenching technique by modifying their composition with the inclusion of varied concentration of Al2O3 to elucidate its effects on glass structural, elastic, thermal properties and Yb(3+) ion NIR luminescence performance. The FTIR spectral analysis indicates Al2O3 addition is promoting the conversion of BOs from NBOs which have been generated during the process of depolymerisation of main glass forming TeO4 units. The elastic properties of the glass revealed an improved rigidity of the glass network on addition of Al2O3. In concurrence to this, differential thermal analysis showed an increase in glass transition temperature with improved thermal stability factor. Also, Yb(3+) fluorescence dynamics demonstrated that, Al2O3 inclusion helps in restraining the detrimental radiation trapping of ∼1μm emission. Copyright © 2014 Elsevier B.V. All rights reserved.

Response of Key Soil Parameters During Compost-Assisted Phytostabilization in Extremely Acidic Tailings: Effect of Plant Species

Science.gov (United States)

Solís-Dominguez, Fernando A.; White, Scott A.; Hutter, Travis Borrillo; Amistadi, Mary Kay; Root, Robert A.; Chorover, Jon; Maier, Raina M.

2012-01-01

Phytostabilization of mine tailings acts to mitigate both eolian dispersion and water erosion events which can disseminate barren tailings over large distances. This technology uses plants to establish a vegetative cover to permanently immobilize contaminants in the rooting zone, often requiring addition of an amendment to assist plant growth. Here we report the results of a greenhouse study that evaluated the ability of six native plant species to grow in extremely acidic (pH ~ 2.5) metalliferous (As, Pb, Zn: 2000–3000 mg kg−1) mine tailings from Iron King Mine Humboldt Smelter Superfund site when amended with a range of compost concentrations. Results revealed that three of the six plant species tested (buffalo grass, mesquite, and catclaw acacia) are good candidates for phytostabilization at an optimum level of 15% compost (w/w) amendment showing good growth and minimal shoot accumulation of metal(loid)s. A fourth candidate, quailbush, also met all criteria except for exceeding the domestic animal toxicity limit for shoot accumulation of zinc. A key finding of this study was that the plant species that grew most successfully on these tailings significantly influenced key tailings parameters; direct correlations between plant biomass and both increased tailings pH and neutrophilic heterotrophic bacterial counts were observed. We also observed decreased iron oxidizer counts and decreased bioavailability of metal(loid)s mainly as a result of compost amendment. Taken together, these results suggest that the phytostabilization process reduced tailings toxicity as well as the potential for metal(loid) mobilization. This study provides practical information on plant and tailings characteristics that is critically needed for successful implementation of assisted phytostabilization on acidic, metalliferous mine tailings sites. PMID:22191663

Arsenic tolerance in Arabidopsis is mediated by two ABCC-type phytochelatin transporters

Science.gov (United States)

Song, Won-Yong; Park, Jiyoung; Mendoza-Cózatl, David G.; Suter-Grotemeyer, Marianne; Shim, Donghwan; Hörtensteiner, Stefan; Geisler, Markus; Weder, Barbara; Rea, Philip A.; Rentsch, Doris; Schroeder, Julian I.; Lee, Youngsook; Martinoia, Enrico

2010-01-01

Arsenic is an extremely toxic metalloid causing serious health problems. In Southeast Asia, aquifers providing drinking and agricultural water for tens of millions of people are contaminated with arsenic. To reduce nutritional arsenic intake through the consumption of contaminated plants, identification of the mechanisms for arsenic accumulation and detoxification in plants is a prerequisite. Phytochelatins (PCs) are glutathione-derived peptides that chelate heavy metals and metalloids such as arsenic, thereby functioning as the first step in their detoxification. Plant vacuoles act as final detoxification stores for heavy metals and arsenic. The essential PC–metal(loid) transporters that sequester toxic metal(loid)s in plant vacuoles have long been sought but remain unidentified in plants. Here we show that in the absence of two ABCC-type transporters, AtABCC1 and AtABCC2, Arabidopsis thaliana is extremely sensitive to arsenic and arsenic-based herbicides. Heterologous expression of these ABCC transporters in phytochelatin-producing Saccharomyces cerevisiae enhanced arsenic tolerance and accumulation. Furthermore, membrane vesicles isolated from these yeasts exhibited a pronounced arsenite [As(III)]–PC2 transport activity. Vacuoles isolated from atabcc1 atabcc2 double knockout plants exhibited a very low residual As(III)–PC2 transport activity, and interestingly, less PC was produced in mutant plants when exposed to arsenic. Overexpression of AtPCS1 and AtABCC1 resulted in plants exhibiting increased arsenic tolerance. Our findings demonstrate that AtABCC1 and AtABCC2 are the long-sought and major vacuolar PC transporters. Modulation of vacuolar PC transporters in other plants may allow engineering of plants suited either for phytoremediation or reduced accumulation of arsenic in edible organs. PMID:21078981

Response of key soil parameters during compost-assisted phytostabilization in extremely acidic tailings: effect of plant species.

Science.gov (United States)

Solís-Dominguez, Fernando A; White, Scott A; Hutter, Travis Borrillo; Amistadi, Mary Kay; Root, Robert A; Chorover, Jon; Maier, Raina M

2012-01-17

Phytostabilization of mine tailings acts to mitigate both eolian dispersion and water erosion events which can disseminate barren tailings over large distances. This technology uses plants to establish a vegetative cover to permanently immobilize contaminants in the rooting zone, often requiring addition of an amendment to assist plant growth. Here we report the results of a greenhouse study that evaluated the ability of six native plant species to grow in extremely acidic (pH ∼ 2.5) metalliferous (As, Pb, Zn: 2000-3000 mg kg(-1)) mine tailings from Iron King Mine Humboldt Smelter Superfund site when amended with a range of compost concentrations. Results revealed that three of the six plant species tested (buffalo grass, mesquite, and catclaw acacia) are good candidates for phytostabilization at an optimum level of 15% compost (w/w) amendment showing good growth and minimal shoot accumulation of metal(loid)s. A fourth candidate, quailbush, also met all criteria except for exceeding the domestic animal toxicity limit for shoot accumulation of zinc. A key finding of this study was that the plant species that grew most successfully on these tailings significantly influenced key tailings parameters; direct correlations between plant biomass and both increased tailings pH and neutrophilic heterotrophic bacterial counts were observed. We also observed decreased iron oxidizer counts and decreased bioavailability of metal(loid)s mainly as a result of compost amendment. Taken together, these results suggest that the phytostabilization process reduced tailings toxicity as well as the potential for metal(loid) mobilization. This study provides practical information on plant and tailings characteristics that is critically needed for successful implementation of assisted phytostabilization on acidic, metalliferous mine tailings sites.

Spectroscopic study of Pr3+ ions doped Zinc Lead Tungsten Tellurite glasses for visible photonic device applications

Science.gov (United States)

Sharma, Ritu; Rao, A. S.; Deopa, Nisha; Venkateswarlu, M.; Jayasimhadri, M.; Haranath, D.; Prakash, G. Vijaya

2018-04-01

Zinc Lead Tungsten Tellurite (ZnPbWTe) glasses doped with different Pr3+ ion concentrations having the composition 5ZnO + 15PbO + 20WO3 + (60-x)TeO2 + xPr6O11 (where x = 0.5, 1, 1.5, 2.0 and 2.5 mol%) were prepared by using sudden quenching technique and characterized to understand their visible emission characteristic features using spectroscopic techniques such as absorption, excitation and emission. The Judd-Ofelt (J-O) theory has been applied to the absorption spectral features with an aim to evaluate various radiative properties for the prominent fluorescent levels of Pr3+ions in the as-prepared glasses. The emission spectra recorded for the as-prepared glasses under 468 nm excitation show three prominent emission transitions 3P0→3H6, 3P0→3F2 and 3P1→3F4, of which 3P0→3F2 observed in visible red region (648 nm), is relatively more intense. The intensity of 3P0→3F2 emission transition in the titled glasses increases up to 1mol% of Pr3+ ions and beyond concentration quenching is observed. Branching ratios (βR) and emission cross-sections (σse) were estimated for 3P0→3F2 transition to understand the luminescence efficiency in visible red region (648 nm). The CIE chromaticity coordinates were also evaluated in order to understand the suitability of these glasses for visible red luminescence devices. From the emission cross-sections, quantum efficiency and CIE coordinates, it was concluded that 1mol% of Pr3+ ions in ZnPbWTe glasses are quite suitable for preparing visible reddish orange luminescent devices.

Silver nanoparticles enhanced luminescence properties of Er³⁺ doped tellurite glasses: Effect of heat treatment

Energy Technology Data Exchange (ETDEWEB)

Fares, Hssen; Férid, Mokhtar [Laboratoire de Physico-Chimie des Matériaux Minéraux et leurs Applications, Centre National de Recherches en Sciences des Matériaux, B.P. 95 Hammam-Lif, 2050 (Tunisia); Elhouichet, Habib, E-mail: habib.elhouichet@fst.rnu.tn [Laboratoire de Physico-Chimie des Matériaux Minéraux et leurs Applications, Centre National de Recherches en Sciences des Matériaux, B.P. 95 Hammam-Lif, 2050 (Tunisia); Department of Physics, Sciences Faculty of Tunis, University Tunis ElManar 2092 (Tunisia); Gelloz, Bernard [Graduate School of Engineering, Nagoya University, 2-24-16 Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8603 (Japan)

2014-09-28

Tellurite glasses doped Er³⁺ ions and containing Silver nanoparticles (Ag NPs) are prepared using melt quenching technique. The nucleation and growth of Ag NPs were controlled by a thermal annealing process. The X-ray diffraction pattern shows no sharp peak indicating an amorphous nature of the glasses. The presence of Ag NPs is confirmed from transmission electron microscopy micrograph. Absorption spectra show typical surface plasmon resonance (SPR) band of Ag NPs within the 510–550 nm range in addition to the distinctive absorption peaks of Er³⁺ ions. The Judd-Ofelt (J-O) intensity parameters, oscillator strengths, spontaneous transition probabilities, branching ratios, and radiative lifetimes were successfully calculated based on the experimental absorption spectrum and the J-O theory. It was found that the presence of silver NPs nucleated and grown during the heat annealing process improves both of the photoluminescence (PL) intensity and the PL lifetime relative to the ⁴I_13/2 → ⁴I_15/2 transition. Optimum PL enhancement was obtained after 10 h of heat-treatment. Such enhancements are mainly attributed to the strong local electric field induced by SPR of silver NPs and also to energy transfer from the surface of silver NPs to Er³⁺ ions, whereas the quenching is ascribed to the energy transfer from Er³⁺ ions to silver NPs. Using the Mc Cumber method, absorption cross-section, calculated emission cross-section, and gain cross-section for the ⁴I_13/2 → ⁴I_15/2 transition were determined and compared for the doped and co-doped glasses. The present results indicate that the glass heat-treated for 10 h has good prospect as a gain medium applied for 1.53 μm band broad and high-gain erbium-doped fiber amplifiers.

Effect of co-doping Tm3+ ions on the emission properties of Dy3+ ions in tellurite glasses

International Nuclear Information System (INIS)

Sasikala, T.; Rama Moorthy, L.; Mohan Babu, A.; Srinivasa Rao, T.

2013-01-01

The present work reports the absorption, photoluminescence and decay properties of singly doped Dy 3+ and co-doped Dy 3+ /Tm 3+ ions in TeO 2 +ZnO+K 2 O+CaO (TZKC) glasses prepared by the melt quenching technique. The glassy nature of the host glass has been confirmed by X-ray diffraction analysis and the primary vibrational modes were determined from the Raman spectrum. Judd–Ofelt (JO) analysis has been used to calculate the radiative transition rates, branching ratios and radiative lifetime of the emitting 4 F 9/2 state. The effect of co-doping of different concentrations of Tm 3+ ions on the emission properties of Dy 3+ ions has been investigated. The decay profiles of the 4 F 9/2 level were fitted to double exponential as well as Inokuti–Hirayama (IH) model to determine the energy transfer rates between Dy 3+ and Tm 3+ ions. The energy transfer rates found to increase with the increase of Tm 3+ ions concentration. The chromaticity coordinates and color purity of the emitted light for all glasses were determined. - Graphical abstract: The graphical abstract shows the emission spectra of Dy 3+ , Tm 3+ and Dy 3+ /Tm 3+ co-doped TZKC glasses recorded by exciting at 355 nm wavelength. - Highlights: • Zinc tellurite glasses doped with Dy 3+ , Tm 3+ and Dy 3+ /Tm 3+ ions were prepared. • XRD, DTA and Raman spectral measurements were recorded to know the nature of host. • Energy transfer occurs from Dy 3+ ions to Tm 3+ ions. • The color purity of the emitted light was determined

Metals and metalloids in whole blood and tissues of Olive Ridley turtles (Lepidochelys olivacea) from La Escobilla Beach (Oaxaca, Mexico).

Science.gov (United States)

Cortés-Gómez, Adriana A; Fuentes-Mascorro, Gisela; Romero, Diego

2014-12-15

Concentrations of eight metals and metalloids (Pb, Cd, Cu, Zn, Mn, Se, Ni and As) were evaluated from 41 nesting females (blood) and 13 dead (tissues) Olive Ridley turtles (Lepidochelys olivacea), a species classified as vulnerable and also listed in Appendix I of the Convention of International Trade in Endangered Species (CITES). The mean blood, liver and kidney lead concentration were 0.02 ± 0.01, 0.11 ± 0.08 and 0.06 ± 0.03 μ gg(-1) ww respectively, values lower than other turtle species and locations, which it could be due to the gradual disuse of leaded gasoline in Mexico and Central America since the 1990s. Mean concentration of cadmium was 0.17 ± 0.08 (blood), 82.88 ± 36.65 (liver) and 150.88 ± 110.9 9μg g(-1) (kidney). To our knowledge, the mean renal cadmium levels found is the highest ever reported worldwide for any sea turtle species, while other six elements showed a concentration similar to other studies in sea turtles. Copyright © 2014 Elsevier Ltd. All rights reserved.

Potential human health risk by metal(loid)s, 234,238U and 210Po due to consumption of fish from the "Luis L. Leon" Reservoir (Northern México).

Science.gov (United States)

Luna-Porres, Mayra Y; Rodríguez-Villa, Marco A; Herrera-Peraza, Eduardo F; Renteria-Villalobos, Marusia; Montero-Cabrera, María E

2014-06-25

Concentrations of As, Cu, Fe, Hg, Pb and Zn and activity concentrations from 234,238U and 210Po in water, fillet, liver and gills were determined in three stocked fish species from the Luis L. Leon reservoir, located in Northern Mexico. The considered species were Lepomis cyanellus, Cyprinus carpio and Ictalurus furcatus. 238U and 234U activity concentration (AC) in fillet samples showed values of 0.007-0.014 and 0.01-0.02 Bq∙kg-1 wet weight (ww), respectively. Liver samples for L. cyanellus, C. carpio and I. furcatus present 210Po AC of 1.16-3.26, 0.70-1.13 and 0.93-1.37 Bq∙kg-1 ww. Arsenic, mercury and lead concentration intervals in fillet samples were 0.13-0.39, 0.005-0.126 and 0.009-0.08 mg∙kg-1 ww, respectively, while in gill samples they were 0.11-0.43, 0.002-0.039 and 0.02-0.26 mg∙kg-1 ww. The elemental Bioaccumulation Factor (BAF) for fish tissues with respect to their concentrations in water was determined. L. cyanellus showed the highest BAF values for As and total U, being BAFAs = 37 and 40 L∙kg-1 in fillet and gills, respectively, and BAFU total = 1.5 L∙kg-1 in fillet. I. furcatus showed the highest BAF values for Hg and Pb, being BAFHg = 40 and 13 L∙kg-1 in fillet and gills, and BAFPb = 6.5 and 22 L∙kg-1 in fillet and gills, respectively. Some metal(loid) concentrations are slightly higher than European regulations for fish fillets. The difference in concentrations of metal(loid)s in fillet among the studied species is probably due to their differences in diet and habitat.

Potential Human Health Risk by Metal(loids, 234,238U and 210Po due to Consumption of Fish from the “Luis L. Leon” Reservoir (Northern México

Directory of Open Access Journals (Sweden)

Mayra Y. Luna-Porres

2014-06-01

Full Text Available Concentrations of As, Cu, Fe, Hg, Pb and Zn and activity concentrations from 234,238U and 210Po in water, fillet, liver and gills were determined in three stocked fish species from the Luis L. Leon reservoir, located in Northern Mexico. The considered species were Lepomis cyanellus, Cyprinus carpio and Ictalurus furcatus. 238U and 234U activity concentration (AC in fillet samples showed values of 0.007–0.014 and 0.01–0.02 Bq∙kg−1 wet weight (ww, respectively. Liver samples for L. cyanellus, C. carpio and I. furcatus present 210Po AC of 1.16–3.26, 0.70–1.13 and 0.93–1.37 Bq∙kg−1 ww. Arsenic, mercury and lead concentration intervals in fillet samples were 0.13–0.39, 0.005–0.126 and 0.009–0.08 mg∙kg−1 ww, respectively, while in gill samples they were 0.11–0.43, 0.002–0.039 and 0.02–0.26 mg∙kg−1 ww. The elemental Bioaccumulation Factor (BAF for fish tissues with respect to their concentrations in water was determined. L. cyanellus showed the highest BAF values for As and total U, being BAFAs = 37 and 40 L∙kg−1 in fillet and gills, respectively, and BAFU total = 1.5 L∙kg−1 in fillet. I. furcatus showed the highest BAF values for Hg and Pb, being BAFHg = 40 and 13 L∙kg−1 in fillet and gills, and BAFPb = 6.5 and 22 L∙kg−1 in fillet and gills, respectively. Some metal(loid concentrations are slightly higher than European regulations for fish fillets. The difference in concentrations of metal(loids in fillet among the studied species is probably due to their differences in diet and habitat.

Use of low cost dead biomasses in the removal of heavy metal toxic/radiotoxic ions from aqueous wastes- a radiotracer study

International Nuclear Information System (INIS)

Mishra, Shuddhodan P.

2005-01-01

In an environmental context, accelerating pollution by toxic metal ions, metalloids, radionuclides and organometal (loid)s has provided the impetus for the research to look into the biotechnological potential of utilizing several low cost dead biomasses/agricultural byproducts to replace existing expensive technologies. Unlike organic pollutants which are biodegradable, these metallic contaminants tend to persist rather indefinitely in the environment, and are eventually accumulated through the food chain thus posing a serious threat to plants, animal and man. The use of radiotracer technique by several workers and ourselves in the study of adsorption uptake or ions (cations and anions) from aqueous solutions by metals/metals oxide surfaces at micro down to tracer level concentrations had been quite rewarding. In continuation of this work the present studies were directed to assess the uptake behaviour of abundantly available low cost dead biomasses [e.g. Rice hulls (oryza sativa L),] Mango (mangifera indica) and Neem (azadirachta indica)barks] towards some heavy metal (Hg 2+ , Cd 2+ , Cr 2+ , Zn 2+ and Ce 3+ ) toxic and radiotoxic (Sr 2+ and Cs l+ )ions from aqueous solutions at low ionic concentrations (10 -2 -10 -8 mol dm -3 ). In all these studies the adsorptive solution was labeled by a suitable radiotracer of the metal ion and the uptake of ions by the three biosorbents was assessed through monitoring of the decrease in radioactivity of the bulk. A parametric study through change of temperature, pH and addition of other co-ions/complexing agents has helped in deducing the thermodynamic parameters and mechanism of the uptake of the ions. The extent of removal of metal ions by these dead biomasses is quite high in most cases and the nature of the uptake appears to be exchange type. These findings show that the agricultural byproducts (dead biomasses) can be utilized in the development of waste water treatment technology for removal of heavy metal toxic and

Biosynthesis of nanoparticles of metals and metalloids by basidiomycetes. Preparation of gold nanoparticles by using purified fungal phenol oxidases.

Science.gov (United States)

Vetchinkina, Elena P; Loshchinina, Ekaterina A; Vodolazov, Ilya R; Kursky, Viktor F; Dykman, Lev A; Nikitina, Valentina E

2017-02-01

The work shows the ability of cultured Basidiomycetes of different taxonomic groups-Lentinus edodes, Pleurotus ostreatus, Ganoderma lucidum, and Grifola frondosa-to recover gold, silver, selenium, and silicon, to elemental state with nanoparticles formation. It examines the effect of these metal and metalloid compounds on the parameters of growth and accumulation of biomass; the optimal cultivation conditions and concentrations of the studied ion-containing compounds for recovery of nanoparticles have been identified. Using the techniques of transmission electron microscopy, dynamic light scattering, X-ray fluorescence and X-ray phase analysis, the degrees of oxidation of the bioreduced elements, the ζ-potential of colloidal solutions uniformity, size, shape, and location of the nanoparticles in the culture fluid, as well as on the surface and the inside of filamentous hyphae have been determined. The study has found the part played by homogeneous chromatographically pure fungal phenol-oxidizing enzymes (laccases, tyrosinases, and Mn-peroxidases) in the recovery mechanism with formation of electrostatically stabilized colloidal solutions. A hypothetical mechanism of gold(III) reduction from HAuCl 4 to gold(0) by phenol oxidases with gold nanoparticles formation of different shapes and sizes has been introduced.

Effect of F- ions on physical and spectroscopic properties of Yb3+-doped TeO2-based glasses

International Nuclear Information System (INIS)

Wang Guonian; Dai Shixun; Zhang Junjie; Xu Shiqing; Hu Lili; Jiang Zhonghong

2005-01-01

The effects of F - ions on physical and spectroscopic properties of the Yb 3+ in tellurite glass system are investigated. The results show that the glass system takes on good thermal stability with the content of ZnF 2 lower than 15 mol%, both the emission cross-section and the fluorescence lifetime of Yb 3+ ions increase evidently which indicate that such oxyfluoride tellurite glass system is a promising laser host matrix for high power generation. FT-IR spectra were used to analyze the effect of F- ions on the structure of tellurite glasses and OH - groups in this glass system. Analysis demonstrates that addition of fluoride decreases the symmetry of the structure of tellurite glasses which increases the emission cross-section and removes the OH - groups, and which improves the measured fluorescence lifetime of Yb 3+ ions

Toxicity identification evaluation methods for identification of toxicants in refinery effluents

International Nuclear Information System (INIS)

Barten, K.A.; Mount, D.R.; Hackett, J.R.

1993-01-01

During the last five years, the authors have used Toxicity Identification Evaluation (TIE) methods to characterize and identify the source(s) of toxicity in effluents from dozens of municipal and industrial facilities. In most cases, specific chemicals responsible for toxicity have been identified. Although generally successful, the initial experience was that for several refinery effluents, they were able only to qualitatively characterize the presence of organic toxicants; standard toxicant identification procedures were not able to isolate specific organic chemicals. They believe that organic toxicity in these refinery effluents is caused by multiple organic compounds rather than by just a few; evidence for this includes an inability to isolate toxicity in a small number of fractions using liquid chromatography and the presence of very large numbers of compounds in isolated fractions. There is also evidence that the toxicant(s) may be ionic, in that the toxicity of whole effluent and isolated fractions often show increasing toxicity with decreasing pH. Finally, positive-pressure filtration has also reduced toxicity in some samples. In this presentation the authors summarize their experiences with refinery effluents, focusing on typical patterns they have observed and alternative procedures they have used to better understand the nature of these toxicants

Bulletin of Materials Science | Indian Academy of Sciences

Indian Academy of Sciences (India)

Home; Journals; Bulletin of Materials Science; Volume 40; Issue 5. Optical spectroscopy of rare earth-doped oxyfluoro-tellurite glasses to probe local environment. GAJANAN V HONNAVAR K P RAMESH ... Keywords. Tellurite glasses; Raman spectroscopy; photoluminscence; Stark level splitting; UV visible spectroscopy.

Potential Human Health Risk by Metal(loid)s, 234,238U and 210Po due to Consumption of Fish from the “Luis L. Leon” Reservoir (Northern México)

Science.gov (United States)

Luna-Porres, Mayra Y.; Rodríguez-Villa, Marco A.; Herrera-Peraza, Eduardo F.; Renteria-Villalobos, Marusia; Montero-Cabrera, María E.

2014-01-01

Concentrations of As, Cu, Fe, Hg, Pb and Zn and activity concentrations from 234,238U and 210Po in water, fillet, liver and gills were determined in three stocked fish species from the Luis L. Leon reservoir, located in Northern Mexico. The considered species were Lepomis cyanellus, Cyprinus carpio and Ictalurus furcatus. 238U and 234U activity concentration (AC) in fillet samples showed values of 0.007–0.014 and 0.01–0.02 Bq∙kg−1 wet weight (ww), respectively. Liver samples for L. cyanellus, C. carpio and I. furcatus present 210Po AC of 1.16–3.26, 0.70–1.13 and 0.93–1.37 Bq∙kg−1 ww. Arsenic, mercury and lead concentration intervals in fillet samples were 0.13–0.39, 0.005–0.126 and 0.009–0.08 mg∙kg−1 ww, respectively, while in gill samples they were 0.11–0.43, 0.002–0.039 and 0.02–0.26 mg∙kg−1 ww. The elemental Bioaccumulation Factor (BAF) for fish tissues with respect to their concentrations in water was determined. L. cyanellus showed the highest BAF values for As and total U, being BAFAs = 37 and 40 L∙kg−1 in fillet and gills, respectively, and BAFU total = 1.5 L∙kg−1 in fillet. I. furcatus showed the highest BAF values for Hg and Pb, being BAFHg = 40 and 13 L∙kg−1 in fillet and gills, and BAFPb = 6.5 and 22 L∙kg−1 in fillet and gills, respectively. Some metal(loid) concentrations are slightly higher than European regulations for fish fillets. The difference in concentrations of metal(loid)s in fillet among the studied species is probably due to their differences in diet and habitat. PMID:24968208

Introducing Toxics

OpenAIRE

David C. Bellinger

2013-01-01

With this inaugural issue, Toxics begins its life as a peer-reviewed, open access journal focusing on all aspects of toxic chemicals. We are interested in publishing papers that present a wide range of perspectives on toxicants and naturally occurring toxins, including exposure, biomarkers, kinetics, biological effects, fate and transport, treatment, and remediation. Toxics differs from many other journals in the absence of a page or word limit on contributions, permitting authors to present ...

Toxic shock syndrome

Science.gov (United States)

Staphylococcal toxic shock syndrome; Toxic shock-like syndrome; TSLS ... Toxic shock syndrome is caused by a toxin produced by some types of staphylococcus bacteria. A similar problem, called toxic shock- ...

Accumulation of Heavy Metals and Metalloid in Foodstuffs from Agricultural Soils around Tarkwa Area in Ghana, and Associated Human Health Risks

Directory of Open Access Journals (Sweden)

Nesta Bortey-Sam

2015-07-01

Full Text Available This study was carried out to assess the extent of heavy metals and metalloid accumulation from agricultural soils to foodstuffs (viz, M. esculenta (cassava and Musa paradisiaca (plantain around thirteen neighboring communities within Tarkwa, Ghana; and to estimate the human health risk associated with consumption of these foodstuffs. Concentrations of As, Cd, Co, Cr, Cu, Ni, Pb, and Zn were measured with an inductively coupled plasma–mass spectrometer and mercury analysis was done using a mercury analyzer. From the results, 30% of cassava samples collected, contained higher concentrations of Pb when compared to Codex Alimentarius Commission standard values. Bioconcentration factor indicated that Ni had higher capacity of absorption into food crops from soil than the other heavy metals. For both children and adults, the target hazard quotient (THQ of Pb in cassava in communities such as Techiman, Wangarakrom, Samahu, and Tebe (only children were greater than 1, which is defined as an acceptable risk value. This indicated that residents could be exposed to significant health risks associated with cassava consumption.

Accumulation of Heavy Metals and Metalloid in Foodstuffs from Agricultural Soils around Tarkwa Area in Ghana, and Associated Human Health Risks

Science.gov (United States)

Bortey-Sam, Nesta; Nakayama, Shouta M. M.; Akoto, Osei; Ikenaka, Yoshinori; Fobil, Julius N.; Baidoo, Elvis; Mizukawa, Hazuki; Ishizuka, Mayumi

2015-01-01

This study was carried out to assess the extent of heavy metals and metalloid accumulation from agricultural soils to foodstuffs (viz, M. esculenta (cassava) and Musa paradisiaca (plantain)) around thirteen neighboring communities within Tarkwa, Ghana; and to estimate the human health risk associated with consumption of these foodstuffs. Concentrations of As, Cd, Co, Cr, Cu, Ni, Pb, and Zn were measured with an inductively coupled plasma–mass spectrometer and mercury analysis was done using a mercury analyzer. From the results, 30% of cassava samples collected, contained higher concentrations of Pb when compared to Codex Alimentarius Commission standard values. Bioconcentration factor indicated that Ni had higher capacity of absorption into food crops from soil than the other heavy metals. For both children and adults, the target hazard quotient (THQ) of Pb in cassava in communities such as Techiman, Wangarakrom, Samahu, and Tebe (only children) were greater than 1, which is defined as an acceptable risk value. This indicated that residents could be exposed to significant health risks associated with cassava consumption. PMID:26225988

Anaerobic biodegradability and toxicity of complex or toxicant wastewater

International Nuclear Information System (INIS)

Wills Betancur, B.A.

1995-01-01

As a first approximation to wastewater classification in susceptibility terms to treatment by anaerobic biological system, anaerobic biodegradability trials are accomplished to leached of sanitary landfill, to wastewater of coffee grain wet treatment plant and to wastewater of fumaric acid recuperation plant. In the last Plant, anaerobic toxicity trials and lethal toxicity on the Daphnia pulex micro-crustacean are made too. Anaerobic biological trials are made continuing the Wageningen University (Holland) Methodology (1.987). Lethal toxicity biological trials are made following the Standard Methods for the Examination of Water and Wastewater(18th edition, 1992). In development of this investigation project is found that fumaric acid recuperation plant leached it has a low anaerobic biodegradability, a high anaerobic toxicity and a high lethal toxicity over Daphnia pulex, for such reasons this leached is cataloged as complex and toxic wastewater. The other hand, wastewater of coffee grain wet treatment plant and wastewater of sanitary landfill they are both highly biodegradability and not-toxic, for such reasons these wastewaters are cataloged as susceptible to treatment by anaerobic biological system

Reprint of “Extracellular production of tellurium nanoparticles by the photosynthetic bacterium Rhodobacter capsulatus”

Energy Technology Data Exchange (ETDEWEB)

Borghese, Roberto, E-mail: roberto.borghese@unibo.it [Dept. of Pharmacy and Biotechnology, University of Bologna (Italy); Brucale, Marco [Institute for the Study of Nanostructured Materials (CNR-ISMN), Rome (Italy); Fortunato, Gianuario [Dept. of Pharmacy and Biotechnology, University of Bologna (Italy); Lanzi, Massimiliano [Dept. of Industrial Chemistry “Toso Montanari”, University of Bologna (Italy); Mezzi, Alessio [Institute for the Study of Nanostructured Materials (CNR-ISMN), Rome (Italy); Valle, Francesco; Cavallini, Massimiliano [Institute for the Study of Nanostructured Materials (CNR-ISMN), Bologna (Italy); Zannoni, Davide [Dept. of Pharmacy and Biotechnology, University of Bologna (Italy)

2017-02-15

Highlights: • Tellurite is reduced by R. capsulatus as cytosolic tellurium nanoprecipitates TeNPs. • Lawsone allows R. capsulatus to produce extracellular TeNPs. • Extracellular TeNPs production depends on the carbon source used for cells growth. • Both lawsone concentration and the incubation time determine the TeNPs size. • Extracellular TeNPs are coated with extracellular polymeric substances (EPS). - Abstract: The toxic oxyanion tellurite (TeO{sub 3}{sup 2−}) is acquired by cells of Rhodobacter capsulatus grown anaerobically in the light, via acetate permease ActP2 and then reduced to Te{sup 0} in the cytoplasm as needle-like black precipitates. Interestingly, photosynthetic cultures of R. capsulatus can also generate Te{sup 0} nanoprecipitates (TeNPs) outside the cells upon addition of the redox mediator lawsone (2-hydroxy-1,4-naphtoquinone). TeNPs generation kinetics were monitored to define the optimal conditions to produce TeNPs as a function of various carbon sources and lawsone concentration. We report that growing cultures over a 10 days period with daily additions of 1 mM tellurite led to the accumulation in the growth medium of TeNPs with dimensions from 200 up to 600–700 nm in length as determined by atomic force microscopy (AFM). This result suggests that nucleation of TeNPs takes place over the entire cell growth period although the addition of new tellurium Te{sup 0} to pre-formed TeNPs is the main strategy used by R. capsulatus to generate TeNPs outside the cells. Finally, X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FT-IR) analysis of TeNPs indicate they are coated with an organic material which keeps the particles in solution in aqueous solvents.

High-resolution reconstruction of atmospheric deposition of trace metals and metalloids since AD 1400 recorded by ombrotrophic peat cores in Hautes-Fagnes, Belgium.

Science.gov (United States)

Allan, Mohammed; Le Roux, Gaël; De Vleeschouwer, François; Bindler, Richard; Blaauw, Maarten; Piotrowska, Natalia; Sikorski, Jaroslaw; Fagel, Nathalie

2013-07-01

The objective of our study was to determine the trace metal accumulation rates in the Misten bog, Hautes-Fagnes, Belgium, and assess these in relation to established histories of atmospheric emissions from anthropogenic sources. To address these aims we analyzed trace metals and metalloids (Pb, Cu, Ni, As, Sb, Cr, Co, V, Cd and Zn), as well as Pb isotopes, using XRF, Q-ICP-MS and MC-ICP-MS, respectively in two 40-cm peat sections, spanning the last 600 yr. The temporal increase of metal fluxes from the inception of the Industrial Revolution to the present varies by a factor of 5-50, with peak values found between AD 1930 and 1990. A cluster analysis combined with Pb isotopic composition allows the identification of the main sources of Pb and by inference of the other metals, which indicates that coal consumption and metallurgical activities were the predominant sources of pollution during the last 600 years. Copyright © 2013 Elsevier Ltd. All rights reserved.

A study of the uptake and toxicity of some stable and radioactive pollutants in marine organisms: antimony, silver, cobalt and strontium in mollusks, crustaceans and teleosts

International Nuclear Information System (INIS)

Amiard, J.-C.

1978-10-01

Qualitative and quantitative results following direct aquatic contamination of mollusks, crustaceans and teleosts by 125 Sb, 110 Ag, 60 Co, 85 Sr are reported. The effects of a number of biotic and abiotic parameters on the contamination of the various organisms and the distribution and elimination of the radionuclides in the tissues were investigated. The transfer of sup(110m)Ag, 60 Co and 125 Sb was studied in several benthic food chains. The transfer factor (F.T.) between a given trophic level and the initial environment (seawater) was determined as well as various physiological parameters (percentages ingested, assimilated, eliminated via the feces or urine and/or the gills. Elimination and tissue uptake were followed in mollusks and crustaceans. The consequences of contamination by stable and radioactive pollutants on plants and animals were considered. Acute (lethal) toxicity of various metals or metalloids on marine organisms were quantified. More sensitive sublethal tests considering physiological functions or behaviour were used. Irradiation doses to experiment animals were calculated, showing the importance of the (internal or external distribution of radionuclides and individual geometries on the total exposure dose [fr

Heavy metals in marine fish meat and consumer health: a review.

Science.gov (United States)

Bosch, Adina C; O'Neill, Bernadette; Sigge, Gunnar O; Kerwath, Sven E; Hoffman, Louwrens C

2016-01-15

The numerous health benefits provided by fish consumption may be compromised by the presence of toxic metals and metalloids such as lead, cadmium, arsenic and mercury, which can have harmful effects on the human body if consumed in toxic quantities. The monitoring of metal concentrations in fish meat is therefore important to ensure compliance with food safety regulations and consequent consumer protection. The toxicity of these metals may be dependent on their chemical forms, which requires metal speciation processes for direct measurement of toxic metal species or the identification of prediction models in order to determine toxic metal forms from measured total metal concentrations. This review addresses various shortcomings in current knowledge and research on the accumulation of metal contaminants in commercially consumed marine fish globally and particularly in South Africa, affecting both the fishing industry as well as fish consumers. © 2015 Society of Chemical Industry.

Agroecological Responses of Heavy Metal Pollution with Special Emphasis on Soil Health and Plant Performances

Directory of Open Access Journals (Sweden)

Vaibhav Srivastava

2017-10-01

Full Text Available With modern day urbanization and industrialization, heavy metal (HM contamination has become a prime concern for today's society. The impacts of metal contamination on agriculture range from the agricultural soil to the produce in our food basket. The heavy metals (HMs and metalloids, including Cr, Mn, Co, Ni, Cu, Zn, Cd, Sn, Hg, Pb, among others, can result in significant toxic impacts. The intensification of agricultural land use and changes in farming practices along with technological advancement have led to heavy metal pollution in soil. Metals/metalloids concentrations in the soil are increasing at alarming rate and affect plant growth, food safety, and soil microflora. The biological and geological reorganization of heavy metal depends chiefly on green plants and their metabolism. Metal toxicity has direct effects to flora that forms an integral component of ecosystems. Altered biochemical, physiological, and metabolic processes are found in plants growing in regions of high metal pollution. However, metals like Cu, Mn, Co, Zn, and Cr are required in trace amounts by plants for their metabolic activities. The present review aims to catalog major published works related to heavy metal contamination in modern day agriculture, and draw a possible road map toward future research in this domain.

Impact of the Pb and Zn ore mining industry on the pollution of the Biała Przemsza River, Poland.

Science.gov (United States)

Jabłońska-Czapla, Magdalena; Nocoń, Katarzyna; Szopa, Sebastian; Łyko, Aleksandra

2016-05-01

The development of mining and metallurgic industries of Pb and Zn ores in the Biała Przemsza catchment area has had a strong influence on the condition of the surface water and bottom sediments. In the following study, total contents of metals and metalloids were researched in the water and bottom sediment samples from the Biała Przemsza River. The samples were collected monthly in 2014 at five sampling points along the river. The research helped to determine correlations between the parameters and components of the water environment (metals/metalloids, cations/anions, pH, Eh, conductivity, carbon (TOC, IC, TC), and suspension). The contents of metals and metalloids were determined with inductively coupled plasma-mass spectrometry (ICP-MS), whereas anions and cations were investigated with ion chromatography (IC). The simplified Community Bureau of Reference (BCR) three-step sequential chemical extraction was performed on Biała Przemsza River bottom sediments collected in April, July, and October. At its lower course, the Biała Przemsza River water did not meet the Polish surface water quality standards. The Biała Przemsza River water is mainly loaded with metals. Toxic concentrations of Cd, Pb, and Zn were observed at sampling points in Okradzionów and Sławków. The toxic Tl concentration was exceeded (2-6 μg/L) at three sampling points. The Biała Przemsza River bottom sediments were composed mostly of medium and fine sand. The BCR extraction of the bottom sediments demonstrated that Cd and Zn were bound to cations/anions and carbonates loosely adsorbed on the bottom sediments in spring and summer. Such a situation was observed at all the sampling points, except for BP3 in Okradzionów. The organic carbon concentration increased along the river course.

Introducing Toxics

Directory of Open Access Journals (Sweden)

David C. Bellinger

2013-04-01

Full Text Available With this inaugural issue, Toxics begins its life as a peer-reviewed, open access journal focusing on all aspects of toxic chemicals. We are interested in publishing papers that present a wide range of perspectives on toxicants and naturally occurring toxins, including exposure, biomarkers, kinetics, biological effects, fate and transport, treatment, and remediation. Toxics differs from many other journals in the absence of a page or word limit on contributions, permitting authors to present their work in as much detail as they wish. Toxics will publish original research papers, conventional reviews, meta-analyses, short communications, theoretical papers, case reports, commentaries and policy perspectives, and book reviews (Book reviews will be solicited and should not be submitted without invitation. Toxins and toxicants concern individuals from a wide range of disciplines, and Toxics is interested in receiving papers that represent the full range of approaches applied to their study, including in vitro studies, studies that use experimental animal or non-animal models, studies of humans or other biological populations, and mathematical modeling. We are excited to get underway and look forward to working with authors in the scientific and medical communities and providing them with a novel venue for sharing their work. [...

Heavy metals and metalloids in egg contents and eggshells of passerine birds from Arizona

Science.gov (United States)

Mora, Miguel A.

2003-01-01

Concentrations of inorganic elements were determined in eggs of passerine birds including the endangered southwestern willow flycatcher (Empidonax traillii extimus) from four regions in Arizona. The main aim of the study was to determine the distribution of metals in egg contents and eggshells, with emphasis on the deposition of Sr in eggshells. Seventy eggs of 11 passerine species were collected at four nesting locations during 2000. Aluminum, Ba, Cr, Cu, Mn, Se, Sr, and Zn, were detected primarily in egg contents of all bird species. Arsenic, Ni, Pb, and V were detected primarily in eggshells. A proportion of most inorganic elements accumulated in the eggshell. Concentrations of Ba, Cu, Mn, Se, Sr, and Zn in egg contents and As, Ba, Cu, and V in eggshells of yellow-breasted chats (Icteria virens) were similar among locations. However, concentrations of Mn, Ni, Sr, and Zn in eggshells were significant different among locations. Except for Cu, Mn, Se, and Zn, concentrations of inorganic elements were 2–35 times greater in eggshells than in eggs. Most concentrations of metals and metalloids in eggs and eggshells of all the bird species were below levels known to affect reproduction or that have other deleterious effects. However, I found somewhat elevated concentrations of Sr in eggshells (highest mean=1505 μg/g dw, n=3) of yellow-breasted chats and willow flycatchers, and in egg contents of yellow warblers (Dendroica petechia) and song sparrows (Melospiza melodia). Whether current observed concentrations of Sr in eggshells are affecting nesting birds in Arizona remains to be determined. Strontium and other metals could be associated with lower hatching success in some areas. This study shows that a proportion of many inorganic elements accumulates in the eggshell and that the potential effects on the proper structure and functioning of the eggshell should not be ignored.

New studies on mustard gold from the Dongping Mines, Hebei Province, China: The tellurian, plumbian, manganoan and mixed varieties

DEFF Research Database (Denmark)

Li, Jiuling; Makovicky, Emil

2001-01-01

geologi, Dongping gold tellurite deposit, mustard gold, calaverite, Fe-Pb-Te minerals, alteration, tellurium, filling in micro-porous, composite varieties, particles of gold......geologi, Dongping gold tellurite deposit, mustard gold, calaverite, Fe-Pb-Te minerals, alteration, tellurium, filling in micro-porous, composite varieties, particles of gold...

Discovering less toxic ionic liquids by using the Microtox® toxicity test.

Science.gov (United States)

Hernández-Fernández, F J; Bayo, J; Pérez de los Ríos, A; Vicente, M A; Bernal, F J; Quesada-Medina, J

2015-06-01

New Microtox® toxicity data of 16 ionic liquids of different cationic and anionic composition were determined. The ionic liquids 1-butyl-1-methylpyrrolidinium trifluoromethanesulfonate, [BMPyr(+)][TFO(-)], 1-butyl-1-methylpyrrolidinium chloride, [BMPyr(+)][Cl(-)], hydroxypropylmethylimidazolium fluoroacetate, [HOPMIM(+)][FCH2COO(-)], and hydroxypropylmethylimidazolium glycolate [HOPMIM(+)][glycolate(-)] were found to be less toxic than conventional organic solvent such as chloroform or toluene, accoding the Microtox® toxicity assays. The toxicity of pyrrolidinium cation was lower than the imidazolium and pyridinium ones. It was found that the inclusion of an hydroxyl group in the alkyl chain length of the cation also reduce the toxicity of the ionic liquid. To sum up, the Microtox® toxicity assays can be used as screening tool to easily determined the toxicity of a wide range of ionic liquids and the toxicity data obtained could allow the obtention of structure-toxicity relationships to design less toxic ionic liquids. Copyright © 2015 Elsevier Inc. All rights reserved.

Optical properties of gold nanoparticle embedded Er{sup 3+} doped lead–tellurite glasses

Energy Technology Data Exchange (ETDEWEB)

Sazali, E.S.; Sahar, M.R., E-mail: mrahim057@gmail.com; Ghoshal, S.K.; Arifin, R.; Rohani, M.S.; Awang, A.

2014-09-01

Highlights: • Er{sup 3+} doped lead–tellurite glass with and without GNPs has been synthesized. • The existence of Au NPs with average diameter of 6.09 nm dispersed in glass matrix. • Plasmonic effect from Au NPs exert prominent enhancement in UC. - Abstract: Enhanced optical properties of rare earth doped glasses for sundry applications are current challenges in materials science and technology. Series of gold nanoparticles (GNPs) embedded Er{sup 3+} doped TeO{sub 2}–PbO–PbO{sub 2} glasses are synthesized and the influences of GNPs on the optical behaviors are examined. XRD spectra confirm the amorphous nature of all the glass samples. TEM images display the existence of a broad distribution of spherical crystalline GNPs with average diameter ∼6.09 nm. UV–Vis–NIR spectra reveal seven absorption bands centered at 490, 526, 551, 652, 800, 982 and 1520 nm due to the absorptions from the ground state to different excited states. Two surface plasmon resonance bands of gold (Au{sup 0}) are evidenced at 556 and 585 nm. The sizable decrease in the optical band gap (2.82–1.09 eV) with the increase of GNPs concentration from 0.025 to 0.1 mol% is attributed to the generation of higher NPs nucleation sites. The intensity parameters related to the radiative transitions within 4f{sup n} configuration of Er{sup 3+} ion are determined and analyzed using Judd–Ofelt (J–O) theory. The room temperature up-conversion emission spectra under 779 nm excitations shows three peaks centered at 520, 550 and 660 nm corresponding to the transitions from {sup 2}H{sub 11/2}, {sup 4}S{sub 3/2} and {sup 4}F{sub 9/2} excited states to {sup 4}I{sub 15/2} ground state. Significant enhancement in the luminescence intensity is primarily ascribed to surface plasmon resonance mediated strong local field effect of GNPs in the proximity Er{sup 3+} ion and radiative energy transfer. The maximum enhancement are evident for green and red bands at 0.05 mol% of Au. The stimulated

Toxicity of fluoride to aquatic species and evaluation of toxicity modifying factors.

Science.gov (United States)

Pearcy, Krysta; Elphick, James; Burnett-Seidel, Charlene

2015-07-01

The present study was performed to investigate the toxicity of fluoride to a variety of freshwater aquatic organisms and to establish whether water quality variables contribute substantively to modifying its toxicity. Water hardness, chloride, and alkalinity were tested as possible toxicity modifying factors for fluoride using acute toxicity tests with Hyalella azteca and Oncorhynchus mykiss. Chloride appeared to be the major toxicity modifying factor for fluoride in these acute toxicity tests. The chronic toxicity of fluoride was evaluated with a variety of species, including 3 fish (Pimephales promelas, O. mykiss, and Salvelinus namaycush), 3 invertebrates (Ceriodaphnia dubia, H. azteca, and Chironomus dilutus), 1 plant (Lemna minor), and 1 alga (Pseudokirchneriella subcapitata). Hyalella azteca was the most sensitive species overall, and O. mykiss was the most sensitive species of fish. The role of chloride as a toxicity modifying factor was inconsistent between species in the chronic toxicity tests. © 2015 SETAC.

Measurements of defect structures by positron annihilation lifetime spectroscopy of the tellurite glass TeO2-P2O5-ZnO-LiNbO3 doped with ions of rare earth elements: Er3+, Nd3+ and Gd3+

Science.gov (United States)

Golis, E.; Yousef, El. S.; Reben, M.; Kotynia, K.; Filipecki, J.

2015-12-01

The objective of the study was the structural analysis of the TeO2-P2O5-ZnO-LiNbO3 tellurite glasses doped with ions of the rare-earth elements: Er3+, Nd3+ and Gd3+ based on the PALS (Positron Annihilation Lifetime Spectroscopy) method of measuring positron lifetimes. Values of positron lifetimes and the corresponding intensities may be connected with the sizes and number of structural defects, such as vacancies, mono-vacancies, dislocations or pores, the sizes of which range from a few angstroms to a few dozen nanometres. Experimental positron lifetime spectrum revealed existence of two positron lifetime components τ1 and τ2. Their interpretation was based on two-state positron trapping model where the physical parameters are the annihilation velocity and positron trapping rate.

Speciation and ecological risk of heavy metals and metalloid in the sediments of Zhalong Wetland in China

International Nuclear Information System (INIS)

Ye, H.; Zang, S.; Xiao, H.; Zhang, L.

2015-01-01

A total of 271 sediments samples from the Zhalong Wetland were analyzed for concentration and distribution of Hg, Cd, As, Cu, Pb, Zn, Cr, and Zn; their speciation according to the modified European Community Bureau of Reference sequential extraction procedures and their ecological risk based on Lars Hakanson’s potential ecological risk assessment and risk assessment code were made. The results can be summarized as the followings: (1) Concentrations of all metals measured were above soil background values of Songnen Plain, and their spatial distributions were distinctly different. The concentrations of metals (except Pb) were high in the east, followed by the north, and were relatively low in the core zone and south. The concentration of Pb was high in the north, south, and west, compared with low concentration in the core zone and east. (2) The dominant proportion of Pb, Zn, and Cr was in the residual fraction, suggesting that they were environmental stable. The concentrations of Cu and As in the reducible fraction, the concentration of Cd in the acid soluble fraction, and the concentration of Hg in the oxidizable fraction were relatively high, indicating they had greater environmental effects. (3) The evaluation of the ecological risk showed that Cd, Hg, and As had relatively high ecological risk index, especially the ecological risk of Cd should be paid attention to. In general, the ecological risk of the heavy metals and metalloid by zone was experimental zone >buffering zone>ecological tourism zone>core zone.

Toxicity alarm: Case history

International Nuclear Information System (INIS)

Hogan, D.; Retallack, J.

1993-01-01

In late fall 1991, the Novacor petrochemical plant near Joffre, Alberta experienced a toxicity alarm, the first since its startup 14 years ago. Fish exposed to a normal toxicity test were stressed within 2 h and showed 100% mortality after 24 h. A history of the events leading up to, during, and after the toxicity alarm is presented. The major effluent sources were three cooling water systems. Although these sources are well characterized, the event causes were not immediately clear. Initial toxic screening indicated that one was very toxic, another moderately toxic, and the third not toxic at all. All three systems utilized the same chemical treatment program to avoid fouling: stabilized phosphates with minor variants. The most toxic of the cooling systems operated at 10-12 cycles, had three chemicals for biocide control, and had three makeup streams. Toxic and nontoxic system characteristics were compared. An in-depth modified toxicity identification and evaluation program was then performed to identify and evaluate the cause of the toxicity alarm for future prevention. The most probable causes of toxicity were identified by elimination. The combination of high numbers of cycles, hydrocarbons in the makeup water, and bromine added as an antifoulant resulted in formation of aromatic bromamines which are capable of causing the toxic condition experienced. 2 tabs

Antimony Toxicity

Directory of Open Access Journals (Sweden)

Shyam Sundar

2010-12-01

Full Text Available Antimony toxicity occurs either due to occupational exposure or during therapy. Occupational exposure may cause respiratory irritation, pneumoconiosis, antimony spots on the skin and gastrointestinal symptoms. In addition antimony trioxide is possibly carcinogenic to humans. Improvements in working conditions have remarkably decreased the incidence of antimony toxicity in the workplace. As a therapeutic, antimony has been mostly used for the treatment of leishmaniasis and schistosomiasis. The major toxic side-effects of antimonials as a result of therapy are cardiotoxicity (~9% of patients and pancreatitis, which is seen commonly in HIV and visceral leishmaniasis co-infections. Quality control of each batch of drugs produced and regular monitoring for toxicity is required when antimonials are used therapeutically.

Differential toxicity and influence of salinity on acute toxicity of ...

African Journals Online (AJOL)

Differential toxicity and influence of salinity on acute toxicity of copper sulphate and lead nitrate against Oreochromis niloticus. KA Bawa-Allah, F Osuala, J Effiong. Abstract. This study investigated the salinity-tolerance of Oreochromis niloticus and the influence of salinity changes on the acute toxicities of copper sulphate ...

Classification of baseline toxicants for QSAR predictions to replace fish acute toxicity studies.

Science.gov (United States)

Nendza, Monika; Müller, Martin; Wenzel, Andrea

2017-03-22

Fish acute toxicity studies are required for environmental hazard and risk assessment of chemicals by national and international legislations such as REACH, the regulations of plant protection products and biocidal products, or the GHS (globally harmonised system) for classification and labelling of chemicals. Alternative methods like QSARs (quantitative structure-activity relationships) can replace many ecotoxicity tests. However, complete substitution of in vivo animal tests by in silico methods may not be realistic. For the so-called baseline toxicants, it is possible to predict the fish acute toxicity with sufficient accuracy from log K ow and, hence, valid QSARs can replace in vivo testing. In contrast, excess toxicants and chemicals not reliably classified as baseline toxicants require further in silico, in vitro or in vivo assessments. Thus, the critical task is to discriminate between baseline and excess toxicants. For fish acute toxicity, we derived a scheme based on structural alerts and physicochemical property thresholds to classify chemicals as either baseline toxicants (=predictable by QSARs) or as potential excess toxicants (=not predictable by baseline QSARs). The step-wise approach identifies baseline toxicants (true negatives) in a precautionary way to avoid false negative predictions. Therefore, a certain fraction of false positives can be tolerated, i.e. baseline toxicants without specific effects that may be tested instead of predicted. Application of the classification scheme to a new heterogeneous dataset for diverse fish species results in 40% baseline toxicants, 24% excess toxicants and 36% compounds not classified. Thus, we can conclude that replacing about half of the fish acute toxicity tests by QSAR predictions is realistic to be achieved in the short-term. The long-term goals are classification criteria also for further groups of toxicants and to replace as many in vivo fish acute toxicity tests as possible with valid QSAR

Potential Influence of Selenium, Copper, Zinc and Cadmium on L-Thyroxine Substitution in Patients with Hashimoto Thyroiditis and Hypothyroidism.

Science.gov (United States)

Rasic-Milutinovic, Z; Jovanovic, D; Bogdanovic, G; Trifunovic, J; Mutic, J

2017-02-01

Background: Besides genetic factors, it is known that some trace elements, as Selenium, Copper, and Zinc are essential for thyroid gland fuction and thyroid hormone metabolism. Moreover, there were some metals effect that suggested patterns associated with overt thyroid disease. Aim of study: Hashimoto thyroiditis (HT), chronic autoimune inflamation of thyroid gland with cosequtive hipothyroidism, is common disease in Serbia, and we thought it is worthwile to explore potential effects of essential and toxic metals and metalloides on thyroid function and ability to restore euthyroid status of them. Results: This cross-sectional, case-control, study investigated the status of essential elements (Selenium,Copper,and Zinc) and toxic metals and metalloides (Al, Cr, Mn, Co, As, Cd, Sb, Ba, Be, Pb and Ni) from the blood of 22 female, patients with Hashimoto thyroiditis and overt hypothyroidism, and compared it with those of 55 female healthy persons. We tried to establish the presence of any correlation between previous mentioned elements and thyroid function in hypothyroid patients and healthy participants. Conclusions: The results of our study suggested that the blood concentration of essential trace elements, especially the ratio of Copper, and Selenium may influence directly thyroid function in patients with HT and overt hypothyroidism.Thus, our findings may have implication to life-long substitution therapy in terms of l-thyroxine dose reduction. Furthermore, for the first time, our study shown potential toxic effect of Cadmium on thyroid function in HT patients, which may implicate the dose of l-thyroxine substitution. © Georg Thieme Verlag KG Stuttgart · New York.

Recent Advances in the Measurement of Arsenic, Cadmium, and Mercury in Rice and Other Foods

OpenAIRE

Jackson, Brian; Punshon, Tracy

2015-01-01

Trace element analysis of foods is of increasing importance because of raised consumer awareness and the need to evaluate and establish regulatory guidelines for toxic trace metals and metalloids. This paper reviews recent advances in the analysis of trace elements in food, including challenges, state-of-the art methods, and use of spatially resolved techniques for localizing the distribution of As and Hg within rice grains. Total elemental analysis of foods is relatively well-established but...

Considerations on aims and approaches of the study on the transport of trace elements in a river watershed

International Nuclear Information System (INIS)

Matsunaga, Takeshi

2002-10-01

Concerning the study subject on the transport of trace, toxic chemicals and radioactive elements in a river watershed, that has been developed in the Research Group for Terrestrial Environment, its aims and methodological approaches have been discussed in the light of related social and technological aspects of today. It is stressed that a study of the transport of radionuclides originated from a nuclear installation is needed to assess the physiological impact and to provide appropriate countermeasures in case of an accident. A numerical model is prerequisite for these objectives and to be keenly developed. The outcome of the modeling will be also important for a quantitative analysis of cycling of trace toxic elements in the atmosphere- lithosphere-hydrosphere, and also of the mechanisms of contamination of the surface aquatic environment. Accordingly, the study will contribute to the key issues stated in the national programs of science and technologies such as conservation of the natural and living environment. The present large consumption of metals and metalloids may cause an extensive contamination in the future. The study can provide solutions to the problems associated with metals and metalloids, because their environmental behavior resembles to that of radionuclides. From a methodological aspect, an importance of a direct investigation of physicochemical forms of trace, toxic elements must be stressed. A simultaneous use of experimental methods and chemical modeling to study the physico-chemical forms will be a good exemption to be realized hereafter. Experimentally, partitioning between solid and liquid phases using radioisotopes, and identification of solid species using various X-ray spectrometric techniques, for example, have been recognized very promising to investigate physico-chemical form of trace elements. These techniques are much ought to the nuclear sciences, suggesting further possible contribution of the nuclear sciences to the questions of

The effect of excitation intensity variation and silver nanoparticle codoping on nonlinear optical properties of mixed tellurite and zinc oxide glass doped with Nd2O3 studied through ultrafast z-scan spectroscopy

Science.gov (United States)

Moreira, L.; Falci, R. F.; Darabian, H.; Anjos, V.; Bell, M. J. V.; Kassab, L. R. P.; Bordon, C. D. S.; Doualan, J. L.; Camy, P.; Moncorgé, R.

2018-05-01

The research on Nd3+ doped new solid-state laser hosts with specific thermo-mechanical and optical properties is very active. Nd3+ doped tellurite glasses are suitable for these applications. They have high linear and nonlinear refraction index, wide transmittance range. The TeO2-ZnO (TZO) glass considered in the present work combines all those features and the nonlinear optical properties can be used for the development of Kerr-lens mode-locked sub picosecond lasers. Recently the laser performance of Nd3+ doped TZO glass and was reported and laser slope efficiency of 21% was observed. We investigate how the intensity variation and the silver nanoparticles codoping affects the nonlinear optical properties of Nd3+ doped TZO glasses. Intensity dependent nonlinear refraction indices coefficients at 750, 800 and 850 nm were observed. The nonlinear optical features were obtained through ultrafast single beam z-scan technique with excitations at 750, 800 and 850 nm and are up to two orders of magnitude higher than those reported in the literature.

Heavy metals and metalloids in egg contents and eggshells of passerine birds from Arizona

International Nuclear Information System (INIS)

Mora, Miguel A.

2003-01-01

High concentrations of Sr in eggshells may be associated with lower hatching success of some passerine birds. - Concentrations of inorganic elements were determined in eggs of passerine birds including the endangered southwestern willow flycatcher (Empidonax traillii extimus) from four regions in Arizona. The main aim of the study was to determine the distribution of metals in egg contents and eggshells, with emphasis on the deposition of Sr in eggshells. Seventy eggs of 11 passerine species were collected at four nesting locations during 2000. Aluminum, Ba, Cr, Cu, Mn, Se, Sr, and Zn, were detected primarily in egg contents of all bird species. Arsenic, Ni, Pb, and V were detected primarily in eggshells. A proportion of most inorganic elements accumulated in the eggshell. Concentrations of Ba, Cu, Mn, Se, Sr, and Zn in egg contents and As, Ba, Cu, and V in eggshells of yellow-breasted chats (Icteria virens) were similar among locations. However, concentrations of Mn, Ni, Sr, and Zn in eggshells were significant different among locations. Except for Cu, Mn, Se, and Zn, concentrations of inorganic elements were 2-35 times greater in eggshells than in eggs. Most concentrations of metals and metalloids in eggs and eggshells of all the bird species were below levels known to affect reproduction or that have other deleterious effects. However, I found somewhat elevated concentrations of Sr in eggshells (highest mean=1505 μg/g dw, n=3) of yellow-breasted chats and willow flycatchers, and in egg contents of yellow warblers (Dendroica petechia) and song sparrows (Melospiza melodia). Whether current observed concentrations of Sr in eggshells are affecting nesting birds in Arizona remains to be determined. Strontium and other metals could be associated with lower hatching success in some areas. This study shows that a proportion of many inorganic elements accumulates in the eggshell and that the potential effects on the proper structure and functioning of the eggshell

Cryptic Role of Zero-Valent Sulfur in Metal and Metalloid Geochemistry in Euxinic Waters

Science.gov (United States)

Helz, G. R.

2014-12-01

Natural waters that are isolated from the atmosphere in confined aquifers, euxinic basins and sediment pore waters often become sulfidic. These waters are conventionally described simply as reducing environments. But because nature does not constrain their exposure to reducing equivalents (e.g. from organic matter) and oxidizing equivalents (e.g. from Fe,Mn oxides), these reducing environments in fact vary cryptically in their redox characteristics. The implications for trace metal and metalloid cycles are only beginning to be explored. The activity of zero-valent sulfur (aS0), a virtual thermodynamic property, is a potentially useful index for describing this variation. At a particular temperature and ionic strength, aS0 can be quantified from knowledge of pH and the total S(0) to total S(-II) ratio. Although data are incomplete, the deep waters of the Black Sea (aS0 ca. 0.3) appear to be more reducing than the deep waters of the Cariaco Basin (aS0 ca. 0.5) even though both are perennially sulfidic. An apparent manifestation is a greater preponderance of greigite relative to mackinawite in the Cariaco Basin. Interestingly, greigite is stable relative to mackinawite in both basins but predominates only at the higher aS0. Values of aS0 in sulfidic natural waters span the range over which Hg-polysulfide complexes gain predominance over Hg sulfide complexes. Competition between these ligands is thought to influence biological methylation, mercury's route into aquatic and human food chains. In sulfidic deep ground waters, the redox state and consequent mobility of As, a global human hazard, will depend on aS0. At intermediate sulfide concentrations, higher aS0 favors more highly charged and thus less mobile As(V) species relative to As(III) species despite the overall reducing characteristics of such waters. Helz, G.R. (2014) Activity of zero-valent sulfur in sulfidic natural waters. Geochem. Trans. In press.

Biogenic selenium and tellurium nanoparticles synthesized by environmental microbial isolates efficaciously inhibit bacterial planktonic cultures and biofilms

Directory of Open Access Journals (Sweden)

Emanuele eZonaro

2015-06-01

Full Text Available The present study deals with Se0- and Te0-based nanoparticles bio-synthesized by two selenite- and tellurite-reducing bacterial strains, namely Stenotrophomonas maltophilia SeITE02 and Ochrobactrum sp. MPV1, isolated from polluted sites. We discovered that, by regulating culture conditions and exposure time to the selenite and tellurite oxyanions, differently sized zero-valent Se and Te nanoparticles were produced. The results revealed that these Se0 and Te0 nanoparticles possess antimicrobial and biofilm eradication activity against E. coli JM109, P. aeruginosa PAO1, and S. aureus ATCC 25923. In particular, Se0 nanoparticles exhibited antimicrobial activity at quite low concentrations, below that of selenite. Toxic effects of both Se0 and Te0 nanoparticles can be related to the production of reactive oxygen species upon exposure of the bacterial cultures. Evidence so far achieved suggests that the antimicrobial activity seems to be strictly linked to the dimensions of the nanoparticles: indeed, the highest activity was shown by nanoparticles of smaller sizes. In particular, it is worth noting how the bacteria tested in biofilm mode responded to the treatment by Se0 and Te0 nanoparticles with a susceptibility similar to that observed in planktonic cultures. This suggests a possible exploitation of both Se0 and Te0 nanoparticles as efficacious antimicrobial agents with a remarkable biofilm eradication capacity.

Toxic substances alert program

Science.gov (United States)

Junod, T. L.

1978-01-01

A toxicity profile is provided, of 187 toxic substances procured by NASA Lewis Research Center during a 3 1/2 year period, including 27 known or suspected carcinogens. The goal of the program is to assure that the center's health and safety personnel are aware of the procurement and use of toxic substances and to alert and inform the users of these materials as to the toxic characteristics and the control measures needed to ensure their safe use. The program also provides a continuing record of the toxic substances procured, who procured them, what other toxic substances the user has obtained in the past, and where similar materials have been used elsewhere at the center.

Mixture toxicity of wood preservative products in the fish embryo toxicity test.

Science.gov (United States)

Coors, Anja; Dobrick, Jan; Möder, Monika; Kehrer, Anja

2012-06-01

Wood preservative products are used globally to protect wood from fungal decay and insects. We investigated the aquatic toxicity of five commercial wood preservative products, the biocidal active substances and some formulation additives contained therein, as well as six generic binary mixtures of the active substances in the fish embryo toxicity test (FET). Median lethal concentrations (LC50) of the single substances, the mixtures, and the products were estimated from concentration-response curves and corrected for concentrations measured in the test medium. The comparison of the experimentally observed mixture toxicity with the toxicity predicted by the concept of concentration addition (CA) showed less than twofold deviation for all binary mixtures of the active substances and for three of the biocidal products. A more than 60-fold underestimation of the toxicity of the fourth product by the CA prediction was detected and could be explained fully by the toxicity of one formulation additive, which had been labeled as a hazardous substance. The reason for the 4.6-fold underestimation of toxicity of the fifth product could not be explained unambiguously. Overall, the FET was found to be a suitable screening tool to verify whether the toxicity of formulated wood preservatives can reliably be predicted by CA. Applied as a quick and simple nonanimal screening test, the FET may support approaches of applying component-based mixture toxicity predictions within the environmental risk assessment of biocidal products, which is required according to European regulations. Copyright © 2012 SETAC.

Predicting molybdenum toxicity to higher plants: Estimation of toxicity threshold values

Energy Technology Data Exchange (ETDEWEB)

McGrath, S.P., E-mail: steve.mcgrath@bbsrc.ac.u [Soil Science Department, Centre for Soils and Ecosystems Function, Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ (United Kingdom); Mico, C.; Zhao, F.J.; Stroud, J.L. [Soil Science Department, Centre for Soils and Ecosystems Function, Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ (United Kingdom); Zhang, H.; Fozard, S. [Division of Environmental Science, Lancaster University, Lancaster LA1 4YQ (United Kingdom)

2010-10-15

Four plant species (oilseed rape, Brassica napus L.; red clover, Trifolium pratense L.; ryegrass, Lolium perenne L.; and tomato, Lycopersicon esculentum L.) were tested on ten soils varying widely in soil properties to assess molybdenum (Mo) toxicity. A larger range (66-fold-609-fold) of added Mo concentrations resulting in 50% inhibition of yield (ED{sub 50}) was found among soils than among plant species (2-fold-38-fold), which illustrated that the soils differed widely in the expression of Mo toxicity. Toxicity thresholds based on soil solution Mo narrowed the variation among soils compared to thresholds based on added Mo concentrations. We conclude that plant bioavailability of Mo in soil depends on Mo solubility, but this alone did not decrease the variability in observed toxicity enough to be used in risk assessment and that other soil properties influencing Mo toxicity to plants need to be considered. - Mo toxicity thresholds varied widely in different soils and therefore soil properties need to be taken into account in order to assess the risk of Mo exposure.

Enhanced luminescence from silver nanoparticles integrated Er{sup 3+}-doped boro-tellurite glasses: Impact of annealing temperature

Energy Technology Data Exchange (ETDEWEB)

Said Mahraz, Zahra Ashur; Sahar, M.R., E-mail: mrahim057@gmail.com; Ghoshal, S.K.

2015-11-15

Considerable enhancement of rare earth ions luminescence intensity stimulated via metal nanoparticles (NPs) inclusion inside inorganic glass matrix opened a new avenue to achieving efficient lasing glass media. Tuning the localised surface plasmon resonance (LSPR) band of noble metal NPs through their precise size manipulation is demonstrated to be the key for such accomplishment. We report the influences of annealing (heat treatment) temperature (AT) on the down-conversion luminescence features of erbium (Er{sup 3+}) doped zinc-boro-tellurite (ZBT) glasses containing silver NPs. The AT dependent (between 390 and 450 °C) variations in refractive index and density are ascribed to the generation of non-bridging oxygen (NBO) ions. X-ray diffraction pattern confirmed the amorphous nature of the melt-quenched synthesized glass samples. TEM micrograph revealed the nucleation of Ag NPs inside the glass matrix having average diameter between 8.4 (un-annealed sample) to 11.8 nm (annealed). The UV–Vis spectra exhibited seven absorption bands corresponding to {sup 4}f–{sup 4}f transitions of Er{sup 3+} ions. Annealed samples displayed a red shift of SPR bands positioned at 550 and 580 nm. Judd–Ofelt theory is used to evaluate the intensity parameters for radiative transitions within 4f{sup n} configuration of Er{sup 3+} ion. Annealing up to 410 °C is found to stimulate the plasmonic effect through the enlargement of NPs. Consequently, the PL intensity is enhanced by a factor of 3.23 ({sup 2}H{sub 11/2} → {sup 4}I{sub 15/2}), 4.10 ({sup 4}S{sub 3/2} → {sup 4}I{sub 15/2}), and 3.79 ({sup 4}F{sub 9/2} → {sup 4}I{sub 15/2}). This achieved excellent down-conversion luminescence efficiency of proposed glasses shows their potential implementation in photonic devices and solid state lasers. - Highlights: • The changes in the physical properties are ascribed to the generation of NBO. • TEM images confirmed the presence of Ag NPs in the glass matrix. • The achieved

Toxic Elements

DEFF Research Database (Denmark)

Hajeb, Parvaneh; Shakibazadeh, Shahram; Sloth, Jens Jørgen

2016-01-01

Food is considered the main source of toxic element (arsenic, cadmium, lead, and mercury) exposure to humans, and they can cause major public health effects. In this chapter, we discuss the most important sources for toxic element in food and the foodstuffs which are significant contributors to h...

Metals and metalloids in whole blood and tissues of Olive Ridley turtles (Lepidochelys olivacea) from La Escobilla Beach (Oaxaca, Mexico)

International Nuclear Information System (INIS)

Cortés-Gómez, Adriana A.; Fuentes-Mascorro, Gisela; Romero, Diego

2014-01-01

Highlights: • We evaluate the concentrations of inorganic pollutants in Olive Ridley turtles. • Information can be used to monitoring the pollutants in habitats of sea turtles. • The renal cadmium levels is the highest ever reported worldwide for any sea turtle species. • Pb levels have declined in recent years in this population. - Abstract: Concentrations of eight metals and metalloids (Pb, Cd, Cu, Zn, Mn, Se, Ni and As) were evaluated from 41 nesting females (blood) and 13 dead (tissues) Olive Ridley turtles (Lepidochelys olivacea), a species classified as vulnerable and also listed in Appendix I of the Convention of International Trade in Endangered Species (CITES). The mean blood, liver and kidney lead concentration were 0.02 ± 0.01, 0.11 ± 0.08 and 0.06 ± 0.03 μg g −1 ww respectively, values lower than other turtle species and locations, which it could be due to the gradual disuse of leaded gasoline in Mexico and Central America since the 1990s. Mean concentration of cadmium was 0.17 ± 0.08 (blood), 82.88 ± 36.65 (liver) and 150.88 ± 110.99 μg g −1 (kidney). To our knowledge, the mean renal cadmium levels found is the highest ever reported worldwide for any sea turtle species, while other six elements showed a concentration similar to other studies in sea turtles

A toxicity reduction evaluation for an oily waste treatment plant exhibiting episodic effluent toxicity.

Science.gov (United States)

Erten-Unal, M; Gelderloos, A B; Hughes, J S

1998-07-30

A Toxicity Reduction Evaluation (TRE) was conducted on the oily wastewater treatment plant (Plant) at a Naval Fuel Depot. The Plant treats ship and ballast wastes, berm water from fuel storage areas and wastes generated in the fuel reclamation plant utilizing physical/chemical treatment processes. In the first period of the project (Period I), the TRE included chemical characterization of the plant wastewaters, monitoring the final effluent for acute toxicity and a thorough evaluation of each treatment process and Plant operating procedures. Toxicity Identification Evaluation (TIE) procedures were performed as part of the overall TRE to characterize and identify possible sources of toxicity. Several difficulties were encountered because the effluent was saline, test organisms were marine species and toxicity was sporadic and unpredictable. The treatability approach utilizing enhancements, improved housekeeping, and operational changes produced substantial reductions in the acute toxicity of the final effluent. In the second period (Period II), additional acute toxicity testing and chemical characterization were performed through the Plant to assess the long-term effects of major unit process improvements for the removal of toxicity. The TIE procedures were also modified for saline wastewaters to focus on suspected class of toxicants such as surfactants. The TRE was successful in reducing acute toxicity of the final effluent through process improvements and operational modifications. The results indicated that the cause of toxicity was most likely due to combination of pollutants (matrix effect) rather than a single pollutant.

Annual and seasonal variability of metals and metalloids in urban and industrial soils in Alcalá de Henares (Spain).

Science.gov (United States)

Peña-Fernández, A; Lobo-Bedmar, M C; González-Muñoz, M J

2015-01-01

Contamination of urban and industrial soils with trace metals has been recognized as a major concern at local, regional and global levels due to their implication on human health. In this study, concentrations of aluminum (Al), arsenic (As), beryllium (Be), cadmium (Cd), chromium (Cr), manganese (Mn), nickel (Ni), lead (Pb), tin (Sn), thallium (Tl), vanadium (V) and zinc (Zn) were determined in soil samples collected in Alcalá de Henares (Madrid, Spain) in order to evaluate the annual and seasonal variation in their levels. The results show that the soils of the industrial area have higher metals concentrations than the urban area. Principal component analysis (PCA) revealed that the two principal sources of trace metal contamination, especially Cd, Cu, Pb, and Zn in the urban soils of Alcalá can be attributed to traffic emissions, while As, Ni and Be primarily originated from industrial discharges. The seasonal variation analysis has revealed that the emission sources in the industrial area remain constant with time. However, in urban areas, both emissions and emission pathways significantly increase over time due to ongoing development. Currently, there is no hypothesis that explains the small seasonal fluctuations of trace metals in soils, since there are many factors affecting this. Owing to the fact that urban environments are becoming the human habitat, it would therefore be advisable to monitor metals and metalloids in urban soils because of the potential risks to human health. Copyright © 2014 Elsevier Inc. All rights reserved.

Metal and metalloid bioaccumulation in the Pacific blue shrimp Litopenaeus stylirostris (Stimpson) from New Caledonia: Laboratory and field studies

International Nuclear Information System (INIS)

Metian, Marc; Hedouin, Laetitia; Eltayeb, Mohamed M.; Lacoue-Labarthe, Thomas; Teyssie, Jean-Louis; Mugnier, Chantal; Bustamante, Paco; Warnau, Michel

2010-01-01

The present work aimed at better understanding metal and metalloid bioaccumulation in the edible Pacific blue shrimp Litopenaeus stylirostris, using both laboratory and field approaches. In the laboratory, the bioaccumulation kinetics of Ag, Cd, Co, Cr, and Zn have been investigated in shrimp exposed via seawater and food, using the corresponding γ-emitting radiotracers ( 110m Ag, 109 Cd, 57 Co, 51 Cr, and 65 Zn) and highly sensitive nuclear detection techniques. Results showed that hepatopancreas and intestine concentrated the metals to the highest extent among the blue shrimp organs and tissues. Moulting was found to play a non negligible detoxification role for Co, Cr and, to a lesser extent, Zn. Metal retention by L. stylirostris widely varied (from a few days to several months), according to the element and exposure pathway considered (a given metal was usually less strongly retained when ingested with food than when it was taken up from the dissolved phase). In the field study, Ag, As, Cd, Co, Cr, Cu, Mn, Ni, and Zn were analysed in shrimp collected from a New Caledonian aquaculture pond. Metal concentrations in the shrimp muscles were generally relatively low and results confirmed the role played by the digestive organs and tissues in the bioaccumulation/storage/detoxification of metals in the Pacific blue shrimp. Preliminary risk considerations indicate that consumption of the shrimp farmed in New Caledonia is not of particular concern for human health.

Improved detection of coastal acid sulfate soil hotspots through biomonitoring of metal(loid) accumulation in water lilies (Nymphaea capensis).

Science.gov (United States)

Stroud, Jacqueline L; Collins, Richard N

2014-07-15

Anthropogenically disturbed coastal acid sulfate soils along the east coast of Australia, and worldwide, periodically result in the discharge of acid waters containing high concentrations of metals. Identifying priority sites (hotspots) within a catchment for acid sulfate soil remediation activities typically involves long-term monitoring of drainwater chemistry, including the capture of data on unpredictable rain-induced groundwater discharge events. To improve upon this monitoring approach, this study investigated using the water lily (Nymphaea capensis) as a biomonitor of drainage waters to identify hotspots in three acid sulfate soil impacted catchments (83 km(2)) in north-eastern New South Wales, Australia. In one catchment where the location of hotspots was known, water lily lamina concentrations of a suite of metal(loid)s were significantly (photspots revealed within catchment variation of plant metal concentrations up to 70-fold. High resolution maps produced from these results, therefore, provided strong evidence for the location of potential hotspots which were confirmed with measurements of drainwater chemistry during rain-induced groundwater discharge events. Median catchment lily accumulation was ca. 160 mg Al kg(-1) and 1,300 mg Fe kg(-1), with hotspots containing up to 6- and 10-fold higher Al and Fe concentrations. These findings suggest that biomonitoring with N. capensis can be an important tool to rapidly identify priority sites for remediation in acid sulfate soil impacted landscapes. Copyright © 2014 Elsevier B.V. All rights reserved.

Metal/metalloid content in plant parts and soils of Corylus spp. influenced by mining-metallurgical production of copper.

Science.gov (United States)

Radojevic, Ana A; Serbula, Snezana M; Kalinovic, Tanja S; Kalinovic, Jelena V; Steharnik, Mirjana M; Petrovic, Jelena V; Milosavljevic, Jelena S

2017-04-01

The town of Bor and its surroundings (Serbia) have been under environmental pollution for more than a century, due to exploitation of large copper deposits. Naturally present Corylus spp. were sampled in the surroundings of the mine and flotation tailings at 12 sites distributed in six zones with different pollution loads, under the assumption that all the zones were endangered except for the background. As, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb and Zn inputs from soil and the air were evaluated in plant parts, in terms of absorption, accumulation and indication abilities of Corylus spp. The obtained results showed that As and Cu were the most enriched elements in soil, and their concentration exceeded the limit and remediation values proposed by the regulation. Plant parts (root, branch, leaf and catkin) also showed enrichment of most studied elements in wide ranges. According to the enrichment factor for plant, metal/metalloid inputs, particularly in leaves, were from anthropogenic origin. Plant absorption which occurred at the soil-root interface was low, based on the bioaccumulation factor, which could be indicative of resistance mechanisms of root to abiotic stress induced by a high content of elements in soil substrate. The values of bioaccumulation coefficient suggested weak and intermediate absorption and exclusion abilities of Corylus spp. to the studied elements. Element concentrations differ in unwashed and washed leaves, as well as pollution loads in plant and soil samples from the background, traffic and the sites with clear mining-metallurgical influence. Therefore, Corylus spp. could be promising in biomonitoring studies.

Estimation of toxicity using the Toxicity Estimation Software Tool (TEST)

Science.gov (United States)

Tens of thousands of chemicals are currently in commerce, and hundreds more are introduced every year. Since experimental measurements of toxicity are extremely time consuming and expensive, it is imperative that alternative methods to estimate toxicity are developed.

Children's Ability to Recognise Toxic and Non-Toxic Fruits

Science.gov (United States)

Fancovicova, Jana; Prokop, Pavol

2011-01-01

Children's ability to identify common plants is a necessary prerequisite for learning botany. However, recent work has shown that children lack positive attitudes toward plants and are unable to identify them. We examined children's (aged 10-17) ability to discriminate between common toxic and non-toxic plants and their mature fruits presented in…

Toxic substances handbook

Science.gov (United States)

Junod, T. L.

1979-01-01

Handbook, published in conjunction with Toxic Substances Alert Program at NASA Lewis Research Center, profiles 187 toxic chemicals in their relatively pure states and include 27 known or suspected carcinogens.

Toxicity evaluation and prediction of toxic chemicals on activated sludge system.

Science.gov (United States)

Cai, Bijing; Xie, Li; Yang, Dianhai; Arcangeli, Jean-Pierre

2010-05-15

The gaps of data for evaluating toxicity of new or overloaded organic chemicals on activated sludge system resulted in the requirements for methodology of toxicity estimation. In this study, 24 aromatic chemicals typically existed in the industrial wastewater were selected and classified into three groups of benzenes, phenols and anilines. Their toxicity on activated sludge was then investigated. Two indexes of IC(50-M) and IC(50-S) were determined respectively from the respiration rates of activated sludge with different toxicant concentration at mid-term (24h) and short-term (30min) time intervals. Experimental results showed that the group of benzenes was the most toxic, followed by the groups of phenols and anilines. The values of IC(50-M) of the tested chemicals were higher than those of IC(50-S). In addition, quantitative structure-activity relationships (QSARs) models developed from IC(50-M) were more stable and accurate than those of IC(50-S). The multiple linear models based on molecular descriptors and K(ow) presented better reliability than single linear models based on K(ow). Among these molecular descriptors, E(lumo) was the most important impact factor for evaluation of mid-term toxicity. Copyright (c) 2009 Elsevier B.V. All rights reserved.

Determination of leachate toxicity through acute toxicity using Daphnia pulex and anaerobic toxicity assays

OpenAIRE

Carabalí-Rivera, Y. S; Barba-Ho, L. E; Torres-Lozada, P

2017-01-01

ABSTRACT The municipal solid waste (MSW) of large cities, in particular the ones of developing countries, is mainly disposed in landfills (LFs), whose inadequate management generates the emission of greenhouse gases and the production of leachates with high concentrations of organic and inorganic matter and, occasionally heavy metals. In this study, the toxicity of the leachates from an intermediate-age municipal landfill was evaluated by ecotoxicity and anaerobic toxicity tests. The acute to...

Toxic clinical hypoxic radiation sensitizers plus radiation-induced toxicity

International Nuclear Information System (INIS)

Richmond, R.C.

1984-01-01

The operational definition espoused twelve years ago that clinical hypoxic radiation sensitizers should be nontoxic interferes with the recognition and research of useful radiation sensitizers. Eight years ago the toxic antitumor drug cis-dichlorodiammineplatinum(II) was reported to be a hypoxic radiation sensitizer and the selective antitumor action of this drug was stressed as potentially creating tumor-targeted radiation sensitization. This rationale of oxidative antitumor drugs as toxic and targeted clinical sensitizers is useful, and has led to the study reported here. The antitumor drug cis-(1,1-cyclobutane-dicarboxylato)diammineplatinum(II), or JM-8, is being tested in clinical trials. Cells of S. typhimurium in PBS in the presence of 0.2mM JM-8 are found to be sensitized to irradiation under hypoxic, but not oxic, conditions. JM-8 is nontoxic to bacteria at this concentration, but upon irradiation the JM-8 solution becomes highly toxic. This radiation induced toxicity of JM-8 preferentially develops from hypoxic solution, and thus contributes to the rationale of hypoxic tumor cell destruction

Separations chemistry of toxic metals

International Nuclear Information System (INIS)

Smith, P.; Barr, M.; Barrans, R.

1996-01-01

Sequestering and removing toxic metal ions from their surroundings is an increasingly active area of research and is gaining importance in light of current environmental contamination problems both within the DOE complex and externally. One method of separating metal ions is to complex them to a molecule (a ligand or chelator) which exhibits specific binding affinity for a toxic metal, even in the presence of other more benign metals. This approach makes use of the sometimes subtle differences between toxic and non-toxic metals resulting from variations in size, charge and shape. For example, toxic metals such as chromium, arsenic, and technetium exist in the environment as oxyanions, negatively charged species with a characteristic tetrahedral shape. Other toxic metals such as actinides and heavy metals are positively charged spheres with specific affinities for particular donor atoms such as oxygen (for actinides) and nitrogen (for heavy metals). In most cases the toxic metals are found in the presence of much larger quantities of less toxic metals such as sodium, calcium and iron. The selectivity of the chelators is critical to the goal of removing the toxic metals from their less toxic counterparts. The approach was to build a ligand framework that complements the unique characteristics of the toxic metal (size, charge and shape) while minimizing interactions with non-toxic metals. The authors have designed ligands exhibiting specificity for the target metals; they have synthesized, characterized and tested these ligands; and they have shown that they exhibit the proposed selectivity and cooperative binding effects

Review of arsenic contamination, exposure through water and food and low cost mitigation options for rural areas

DEFF Research Database (Denmark)

Sharma, Anitha Kumari; Tjell, Jens Christian; Sloth, Jens Jørgen

2014-01-01

Arsenic (As) is a toxic metalloid found to be an important groundwater contaminant of mainly natural geogenic origin worldwide particularly in large deltas and along major rivers in poor regions of South- and East-Asia. Excessive and long-term human intake of toxic inorganic As with food and wate...... for lowering the human intake of As in rural areas are critically evaluated in terms of public acceptance, sustainability and impact on arsenicosis. © 2013 Elsevier Ltd....... is causing arsenicosis, which is disfiguring, disabling, and leading to potentially fatal diseases like skin- and internal cancers. It is estimated that more than 100. million people mainly in developing countries are at risk. The arsenicosis situation in affected countries has been named the largest...

Immunotoxicity, genotoxicity and epigenetic toxicity of nanomaterials: New strategies for toxicity testing?

Science.gov (United States)

Dusinska, Maria; Tulinska, Jana; El Yamani, Naouale; Kuricova, Miroslava; Liskova, Aurelia; Rollerova, Eva; Rundén-Pran, Elise; Smolkova, Bozena

2017-11-01

The unique properties of nanomaterials (NMs) are beneficial in numerous industrial and medical applications. However, they could also induce unintended effects. Thus, a proper strategy for toxicity testing is essential in human hazard and risk assessment. Toxicity can be tested in vivo and in vitro; in compliance with the 3Rs, alternative strategies for in vitro testing should be further developed for NMs. Robust, standardized methods are of great importance in nanotoxicology, with comprehensive material characterization and uptake as an integral part of the testing strategy. Oxidative stress has been shown to be an underlying mechanism of possible toxicity of NMs, causing both immunotoxicity and genotoxicity. For testing NMs in vitro, a battery of tests should be performed on cells of human origin, either cell lines or primary cells, in conditions as close as possible to an in vivo situation. Novel toxicity pathways, particularly epigenetic modification, should be assessed along with conventional toxicity testing methods. However, to initiate epigenetic toxicity screens for NM exposure, there is a need to better understand their adverse effects on the epigenome, to identify robust and reproducible causal links between exposure, epigenetic changes and adverse phenotypic endpoints, and to develop improved assays to monitor epigenetic toxicity. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Radionuclide toxicity

International Nuclear Information System (INIS)

Galle, P.

1982-01-01

The aim of this symposium was to review the radionuclide toxicity problems. Five topics were discussed: (1) natural and artificial radionuclides (origin, presence or emission in the environment, human irradiation); (2) environmental behaviour of radionuclides and transfer to man; (3) metabolism and toxicity of radionuclides (radioiodine, strontium, rare gas released from nuclear power plants, ruthenium-activation metals, rare earths, tritium, carbon 14, plutonium, americium, curium and einsteinium, neptunium, californium, uranium) cancerogenous effects of radon 222 and of its danghter products; (4) comparison of the hazards of various types of energy; (5) human epidemiology of radionuclide toxicity (bone cancer induction by radium, lung cancer induction by radon daughter products, liver cancer and leukaemia following the use of Thorotrast, thyroid cancer; other site of cancer induction by radionuclides) [fr

Pediatric Toxic Shock Syndrome

Directory of Open Access Journals (Sweden)

Jennifer Yee

2017-09-01

Full Text Available Audience: This scenario was developed to educate emergency medicine residents on the diagnosis and management of a pediatric patient with toxic shock syndrome. The case is also appropriate for teaching of medical students and advanced practice providers, as well as a review of the principles of crisis resource management, teamwork, and communication. Introduction: Toxic shock syndrome is a low-frequency, high-acuity scenario requiring timely identification and aggressive management. If patients suffering from this condition are managed incorrectly, they may progress into multi-organ dysfunction and potentially death. Toxic shock syndrome has been associated with Streptococcus and Staphylococcus aureus (Staph. Approximately half of Staph cases are associated with menstruation, which was first described in the 1970s-1980s and was associated with the use of absorbent tampons.1 Group A Streptococcus may cause complications such as necrotizing fasciitis and gangrenous myositis.2 Pediatric patients may present critically ill from toxic shock syndrome. Providers need to perform a thorough history and physical exam to discern the source of infection. Management requires aggressive care with antibiotics and IV fluids. Objectives: By the end of this simulation session, the learner will be able to: 1 Recognize toxic shock syndrome. 2 Review the importance of a thorough physical exam. 3 Discuss management of toxic shock syndrome, including supportive care and the difference in antibiotic choices for streptococcal and staphylococcal toxic shock syndrome. 4 Appropriately disposition a patient suffering from toxic shock syndrome. 5 Communicate effectively with team members and nursing staff during a resuscitation of a critically ill patient. Method: This session was conducted using high-fidelity simulation, followed by a debriefing session and lecture on toxic shock syndrome.

Electronic Cigarette Toxicity.

Science.gov (United States)

Payne, J Drew; Michaels, David; Orellana-Barrios, Menfil; Nugent, Kenneth

2017-04-01

Electronic cigarettes (e-cigarettes) are often advertised as a healthier product when compared with traditional cigarettes. Currently, there are limited data to support this and only a threat of federal regulation from the US Food and Drug Administration. Calls to poison control centers about e-cigarette toxicity, especially in children, and case reports of toxic exposures have increased over the past 3 years. This research letter reports the frequency of hazardous exposures to e-cigarettes and characterizes the reported adverse health effects associated with e-cigarette toxicity.

Evaluation of nano-specific toxicity of zinc oxide, copper oxide, and silver nanoparticles through toxic ratio

Energy Technology Data Exchange (ETDEWEB)

Zhang, Weicheng; Liu, Xiawei; Bao, Shaopan; Xiao, Bangding; Fang, Tao, E-mail: fangt@ihb.ac.cn [Chinese Academy of Sciences, Institute of Hydrobiology (China)

2016-12-15

For safety and environmental risk assessments of nanomaterials (NMs) and to provide essential toxicity data, nano-specific toxicities, or excess toxicities, of ZnO, CuO, and Ag nanoparticles (NPs) (20, 20, and 30 nm, respectively) to Escherichia coli and Saccharomyces cerevisiae in short-term (6 h) and long-term (48 h) bioassays were quantified based on a toxic ratio. ZnO NPs exhibited no nano-specific toxicities, reflecting similar toxicities as ZnO bulk particles (BPs) (as well as zinc salt). However, CuO and Ag NPs yielded distinctly nano-specific toxicities when compared with their BPs. According to their nano-specific toxicities, the capability of these NPs in eliciting hazardous effects on humans and the environment was as follows: CuO > Ag > ZnO NPs. Moreover, long-term bioassays were more sensitive to nano-specific toxicity than short-term bioassays. Overall, nano-specific toxicity is a meaningful measurement to evaluate the environmental risk of NPs. The log T{sub e}{sup particle} value is a useful parameter for quantifying NP nano-specific toxicity and enabling comparisons of international toxicological data. Furthermore, this value could be used to determine the environmental risk of NPs.

Cyclophosphamide-induced pulmonary toxicity

International Nuclear Information System (INIS)

Siemann, D.W.; Macler, L.; Penney, D.P.

1986-01-01

Unlike radiation effects, pulmonary toxicity following drug treatments may develop soon after exposure. The dose-response relationship between Cyclophosphamide and lung toxicity was investigated using increased breathing frequency assays used successfully for radiation induced injury. The data indicate that release of protein into the alveolus may play a significant role in Cy induced pulmonary toxicity. Although the mechanism responsible for the increased alveolar protein is as yet not identified, the present findings suggest that therapeutic intervention to inhibit protein release may be an approach to protect the lungs from toxic effects. (UK)

Chelation in Metal Intoxication

Directory of Open Access Journals (Sweden)

Swaran J.S. Flora

2010-06-01

Full Text Available Chelation therapy is the preferred medical treatment for reducing the toxic effects of metals. Chelating agents are capable of binding to toxic metal ions to form complex structures which are easily excreted from the body removing them from intracellular or extracellular spaces. 2,3-Dimercaprol has long been the mainstay of chelation therapy for lead or arsenic poisoning, however its serious side effects have led researchers to develop less toxic analogues. Hydrophilic chelators like meso-2,3-dimercaptosuccinic acid effectively promote renal metal excretion, but their ability to access intracellular metals is weak. Newer strategies to address these drawbacks like combination therapy (use of structurally different chelating agents or co-administration of antioxidants have been reported recently. In this review we provide an update of the existing chelating agents and the various strategies available for the treatment of heavy metals and metalloid intoxications.

TOXICITY BEHAVIORS IN ORGANIZATIONS: STUDY OF RELIABILITY AND VALIDITY OF TOXIC EMOTIONAL EXPERIENCES SCALE

OpenAIRE

Bektas, Meral; Erkal, Pinar

2016-01-01

In toxic organizations which are mostly destructive instead of being constrictive towards its employees, toxicity behaviors emerge as a result of the formal and informal relationships. Toxicity behaviors are often negatively affect motivation, job satisfaction or performance of the employees in workplace. Basic toxicity behaviors in organizations are: extreme jealousy, biting words, emphasis  superiority emphasis, getting angry, offending employees, strict control, heavy job workload, limited...

Antimony Toxicity

OpenAIRE

Sundar, Shyam; Chakravarty, Jaya

2010-01-01

Antimony toxicity occurs either due to occupational exposure or during therapy. Occupational exposure may cause respiratory irritation, pneumoconiosis, antimony spots on the skin and gastrointestinal symptoms. In addition antimony trioxide is possibly carcinogenic to humans. Improvements in working conditions have remarkably decreased the incidence of antimony toxicity in the workplace. As a therapeutic, antimony has been mostly used for the treatment of leishmaniasis and schistosomiasis. The...

Rectal toxicity profile after transperineal interstitial permanent prostate brachytherapy: Use of a comprehensive toxicity scoring system and identification of rectal dosimetric toxicity predictors

International Nuclear Information System (INIS)

Shah, Jinesh N.; Ennis, Ronald D.

2006-01-01

Purpose: To better understand rectal toxicity after prostate brachytherapy, we employed the National Cancer Institute Common Terminology Criteria for Adverse Events (CTCAE version 3.0), a comprehensive system with distinct and separately reported gastrointestinal adverse event items (unlike Radiation Therapy Oncology Group morbidity scoring), to evaluate item-specific postimplant rectal toxicities. Methods and Materials: We analyzed 135 patients treated with brachytherapy ± hormonal therapy, using CTCAE v3.0 to score acute/late rectal toxicities (median follow-up, 41 months). Dosimetric parameters were evaluated for ability to predict toxicities. Results: Use of CTCAE yielded a novel rectal toxicity profile consisting of diarrhea, incontinence, urgency, proctitis, pain, spasms, and hemorrhage event rates. No item had a 25 (percent of rectal volume receiving 25% of prescribed prostate dose) ≤ 25% vs. 60% for %V 25 > 25% (p 1 ≤ 40% vs. 44% for %V 1 > 40% (p = 0.007). Conclusions: A comprehensive understanding of item-specific postimplant rectal toxicities was obtained using CTCAE. Rectal %V 25 > 25% and %V 1 > 40% predicted worse late diarrhea and maximum toxicity, respectively

Arbuscular Mycorrhizal Fungi Community Structure, Abundance and Species Richness Changes in Soil by Different Levels of Heavy Metal and Metalloid Concentration

Science.gov (United States)

Krishnamoorthy, Ramasamy; Kim, Chang-Gi; Subramanian, Parthiban; Kim, Ki-Yoon; Selvakumar, Gopal; Sa, Tong-Min

2015-01-01

Arbuscular Mycorrhizal Fungi (AMF) play major roles in ecosystem functioning such as carbon sequestration, nutrient cycling, and plant growth promotion. It is important to know how this ecologically important soil microbial player is affected by soil abiotic factors particularly heavy metal and metalloid (HMM). The objective of this study was to understand the impact of soil HMM concentration on AMF abundance and community structure in the contaminated sites of South Korea. Soil samples were collected from the vicinity of an abandoned smelter and the samples were subjected to three complementary methods such as spore morphology, terminal restriction fragment length polymorphism (T-RFLP) and denaturing gradient gel electrophoresis (DGGE) for diversity analysis. Spore density was found to be significantly higher in highly contaminated soil compared to less contaminated soil. Spore morphological study revealed that Glomeraceae family was more abundant followed by Acaulosporaceae and Gigasporaceae in the vicinity of the smelter. T-RFLP and DGGE analysis confirmed the dominance of Funneliformis mosseae and Rhizophagus intraradices in all the study sites. Claroideoglomus claroideum, Funneliformis caledonium, Rhizophagus clarus and Funneliformis constrictum were found to be sensitive to high concentration of soil HMM. Richness and diversity of Glomeraceae family increased with significant increase in soil arsenic, cadmium and zinc concentrations. Our results revealed that the soil HMM has a vital impact on AMF community structure, especially with Glomeraceae family abundance, richness and diversity. PMID:26035444

Trichothecenes: structure-toxic activity relationships.

Science.gov (United States)

Wu, Qinghua; Dohnal, Vlastimil; Kuca, Kamil; Yuan, Zonghui

2013-07-01

Trichothecenes comprise a large family of structurally related toxins mainly produced by fungi belonging to the genus Fusarium. Among trichothecenes, type A and type B are of the most concern due to their broad and highly toxic nature. In order to address structure-activity relationships (SAR) of trichothecenes, relationships between structural features and biological effects of trichothecene mycotoxins in mammalian systems are summarized in this paper. The double bond between C-9-C-10 and the 12,13-epoxide ring are essential structural features for trichothecene toxicity. Removal of these groups results in a complete loss of toxicity. A hydroxyl group at C-3 enhances trichothecene toxicity, while this activity decreases gradually when C-3 is substituted with either hydrogen or an acetoxy group. The presence of a hydroxyl group at C-4 promotes slightly lower toxicity than an acetoxy group at the same position. The toxicity for type B trichothecenes decreases if the substituent at C-4 is changed from acetoxy to hydroxyl or hydrogen at C-4 position. The presence of hydroxyl and hydrogen groups on C-15 decreases the trichothecene toxicity in comparison with an acetoxy group attached to this carbon. Trichothecenes toxicity increases when a macrocyclic ring exists between the C-4 and C-15. At C-8 position, an oxygenated substitution at C-8 is essential for trichothecene toxicity, indicating a decrease in the toxicity if substituent change from isovaleryloxy through hydrogen to the hydroxyl group. The presence of a second epoxy ring at C-7-C-8 reduces the toxicity, whereas epoxidation at C-9-C-10 of some macrocyclic trichothecenes increases the activity. Conjugated trichothecenes could release their toxic precursors after hydrolysis in animals, and present an additional potential risk. The SAR study of trichothecenes should provide some crucial information for a better understanding of trichothecene chemical and biological properties in food contamination.

Arsenic in groundwater: a summary of sources and the biogeochemical and hydrogeologic factors affecting arsenic occurrence and mobility

Science.gov (United States)

Barringer, Julia L.; Reilly, Pamela A.; Bradley, Paul M.

2013-01-01

Arsenic (As) is a metalloid element (atomic number 33) with one naturally occurring isotope of atomic mass 75, and four oxidation states (-3, 0, +3, and +5) (Smedley and Kinniburgh, 2002). In the aqueous environment, the +3 and +5 oxidation states are most prevalent, as the oxyanions arsenite (H3AsO3 or H2AsO3- at pH ~9-11) and arsenate (H2AsO4- and HAsO42- at pH ~4-10) (Smedley and Kinniburgh, 2002). In soils, arsine gases (containing As3-) may be generated by fungi and other organisms (Woolson, 1977). The different forms of As have different toxicities, with arsine gas being the most toxic form. Of the inorganic oxyanions, arsenite is considered more toxic than arsenate, and the organic (methylated) arsenic forms are considered least toxic (for a detailed discussion of toxicity issues, the reader is referred to Mandal and Suzuki (2002)). Arsenic is a global health concern due to its toxicity and the fact that it occurs at unhealthful levels in water supplies, particularly groundwater, in more than 70 countries (Ravenscroft et al., 2009) on six continents.

Is it possible to avert arsenic effects on cells and tissues bypassing its toxicity and suppressive consequences of energy production? A hypothesis

Directory of Open Access Journals (Sweden)

Biplab Giri

2017-01-01

Full Text Available Arsenic, a sulfhydryl reactive metalloid, found primarily in two forms: arsenite and arsenate, causing several human health problems, is considered as a dreaded agent against public health. It mainly spreads through groundwater contamination and affects human mainly through drinking water. Arsenic contaminated groundwater is now a major threat in some parts of India (the river basin of Ganga and Brahmaputra and Bangladesh. The current authors belong to the region where arsenic poisoning and its consequences are spreading in an uncontrolled way. We are helpless to stop the spreading of geogenic groundwater arsenic contamination at present. Although most of the research on arsenic removal from drinking water and on toxicity profile has been carried out, very few preventive measures have been reported till date to balance the arsenic-induced cellular energy deficiency and oxidative stress-mediated cell death and cellular senescence. And, therefore, we need to think about alternative remedial to address such problems, which propel us to propose the current hypothesis that the adverse effects of energy imbalance due to arsenic toxicity in cells could be dodged by intake of moderate amount of alcohol. While pyruvate dehydrogenase complex is blocked by arsenic, glucose cannot be utilized through Kreb's cycle. However, alcohol can produce energy by bypassing the aerobic adenosine triphosphate (ATP production machinery. In addition, arsenic poisoning incurs cellular oxidative stress which needs to be scavenged further. So to meet this secondary problem, we also suggest consuming red grape juice (a potent antioxidant and cytoprotective agent in addition to alcohol (as per International Center for Alcohol Policies (ICAP Drinking Guidelines in our second part of the hypothesis. In conclusion, it can be suggested that the red wine which contains moderate amount of alcohol and high levels of red grape polyphenols, galic acid, resveratrol, and other

Assessing the toxic effects of ethylene glycol ethers using Quantitative Structure Toxicity Relationship models

International Nuclear Information System (INIS)

Ruiz, Patricia; Mumtaz, Moiz; Gombar, Vijay

2011-01-01

Experimental determination of toxicity profiles consumes a great deal of time, money, and other resources. Consequently, businesses, societies, and regulators strive for reliable alternatives such as Quantitative Structure Toxicity Relationship (QSTR) models to fill gaps in toxicity profiles of compounds of concern to human health. The use of glycol ethers and their health effects have recently attracted the attention of international organizations such as the World Health Organization (WHO). The board members of Concise International Chemical Assessment Documents (CICAD) recently identified inadequate testing as well as gaps in toxicity profiles of ethylene glycol mono-n-alkyl ethers (EGEs). The CICAD board requested the ATSDR Computational Toxicology and Methods Development Laboratory to conduct QSTR assessments of certain specific toxicity endpoints for these chemicals. In order to evaluate the potential health effects of EGEs, CICAD proposed a critical QSTR analysis of the mutagenicity, carcinogenicity, and developmental effects of EGEs and other selected chemicals. We report here results of the application of QSTRs to assess rodent carcinogenicity, mutagenicity, and developmental toxicity of four EGEs: 2-methoxyethanol, 2-ethoxyethanol, 2-propoxyethanol, and 2-butoxyethanol and their metabolites. Neither mutagenicity nor carcinogenicity is indicated for the parent compounds, but these compounds are predicted to be developmental toxicants. The predicted toxicity effects were subjected to reverse QSTR (rQSTR) analysis to identify structural attributes that may be the main drivers of the developmental toxicity potential of these compounds.

Oxygen toxicity

Directory of Open Access Journals (Sweden)

C. A. van der Westhuizen

1990-07-01

Full Text Available Oxygen has been discovered about 200 years ago. Since then the vital physiological involvement of oxygen in various biologi­cal processes, mainly energy production, has been established. However, in the body molecular oxygen can be converted to toxic oxygen metabolites such as superoxide anion, hydrogen peroxide, the hydroxyl radical and singlet oxygen. These toxic metabolites are produced mainly in the mitochondria, plasma membranes and endoplasmic reticulum.

Yellow phosphorus process to convert toxic chemicals to non-toxic products

Science.gov (United States)

Chang, S.G.

1994-07-26

The present invention relates to a process for generating reactive species for destroying toxic chemicals. This process first contacts air or oxygen with aqueous emulsions of molten yellow phosphorus. This contact results in rapid production of abundant reactive species such as O, O[sub 3], PO, PO[sub 2], etc. A gaseous or liquid aqueous solution organic or inorganic chemicals is next contacted by these reactive species to reduce the concentration of toxic chemical and result in a non-toxic product. The final oxidation product of yellow phosphorus is phosphoric acid of a quality which can be recovered for commercial use. A process is developed such that the byproduct, phosphoric acid, is obtained without contamination of toxic species in liquids treated. A gas stream containing ozone without contamination of phosphorus containing species is also obtained in a simple and cost-effective manner. This process is demonstrated to be effective for destroying many types of toxic organic, or inorganic, compounds, including polychlorinated biphenyls (PCB), aromatic chlorides, amines, alcohols, acids, nitro aromatics, aliphatic chlorides, polynuclear aromatic compounds (PAH), dyes, pesticides, sulfides, hydroxyamines, ureas, dithionates and the like. 20 figs.

Phylogenetic diversity of bacteria associated with toxic and non-toxic ...

African Journals Online (AJOL)

Phylogenetic diversity of bacteria associated with toxic and non-toxic strains of Alexandrium minutum. L Palacios, B Reguera, J Franco, I Marín. Abstract. Marine planktonic dinoflagellates are usually associated with bacteria, some of which seem to have a symbiotic relation with the dinoflagellate cells. The role of bacteria in ...

Quantifying heavy metals sequestration by sulfate-reducing bacteria in an acid mine drainage-contaminated wetland

Directory of Open Access Journals (Sweden)

John W Moreau

2013-03-01

Full Text Available Bioremediation strategies that depend on bacterial sulfate reduction for heavy metals remediation harness the reactivity of these metals with biogenic aqueous sulfide. Quantitative knowledge of the degree to which specific toxic metals are partitioned into various sulfide, oxide, or other phases is important for predicting the long-term mobility of these metals under environmental conditions. Here we report the quantitative partitioning into sedimentary biogenic sulfides of a suite of metals and metalloids associated with acid mine drainage contamination of a natural estuarine wetland for over a century.

Effects of manganese oxide on arsenic reduction and leaching from contaminated floodplain soil

DEFF Research Database (Denmark)

Ehlert, Katrin; Mikutta, Christian; Kretzschmar, Ruben

2016-01-01

Reductive release of the potentially toxic metalloid As from Fe(III) (oxyhydr)oxides has been identified as an important process leading to elevated As porewater concentrations in soils and sediments. Despite the ubiquitous presence of Mn oxides in soils and their oxidizing power toward As.......7) on As speciation and release from an As-contaminated floodplain soil (214 mg As/kg) under anoxic conditions. Our results show that birnessite additions significantly decreased As leaching. The reduction of both As and Fe was delayed, and As(III) accumulated in birnessite-rich column parts, indicating...

Usefulness of pioneer vegetation for the phytomanagement of metal(loid)s enriched tailings: grasses vs. shrubs vs. trees.

Science.gov (United States)

Parraga-Aguado, Isabel; Querejeta, Jose-Ignacio; González-Alcaraz, María-Nazaret; Jiménez-Cárceles, Francisco J; Conesa, Héctor M

2014-01-15

The goal of this work was to assess the selection of the most suitable combination of plant species for the phytomanagement of mine tailings, by comparing among different plant life-forms (grasses, shrubs and trees). A comparison on induced rhizosphere changes generated by four plant species (the grass Piptatherum miliaceum, the shrub Helichrysum decumbens, and the trees, Pinus halepensis and Tetraclinis articulata) and high density vegetation patches (fertility islands) at a mine tailing located at Southeast Spain and the description of their physiological status employing stable isotopes analyses were carried out. The edaphic niches for plant growth were determined by salinity, organic matter and total soil nitrogen while metal(loid)s concentrations played a minor role. Induced changes in plant rhizospheres had a significant impact in soil microbiology. While grasses and shrubs may play an important role in primary ecological succession, trees seem to be the key to the development of fertility islands. The low δ(15)N values (-8.00‰) in P. halepensis needles may reflect higher ectomycorrhizal dependence. Large differences in leaf δ(18)O among the plant species indicated contrasting and complementary water acquisition strategies. Leaf δ(13)C values (-27.6‰) suggested that T. articulata had higher water use efficiency than the rest of species (-29.9‰). The implement of a diverse set of plant species with contrasting life forms for revegetating tailings may result in a more efficient employment of water resources and a higher biodiversity not only in relation to flora but soil microbiology too. Copyright © 2013 Elsevier Ltd. All rights reserved.

The metalloid arsenite induces nuclear export of Id3 possibly via binding to the N-terminal cysteine residues

International Nuclear Information System (INIS)

Kurooka, Hisanori; Sugai, Manabu; Mori, Kentaro; Yokota, Yoshifumi

2013-01-01

Highlights: •Sodium arsenite induces cytoplasmic accumulation of Id3. •Arsenite binds to closely spaced N-terminal cysteine residues of Id3. •N-terminal cysteines are essential for arsenite-induced nuclear export of Id3. •Nuclear export of Id3 counteracts its transcriptional repression activity. -- Abstract: Ids are versatile transcriptional repressors that regulate cell proliferation and differentiation, and appropriate subcellular localization of the Id proteins is important for their functions. We previously identified distinct functional nuclear export signals (NESs) in Id1 and Id2, but no active NES has been reported in Id3. In this study, we found that treatment with the stress-inducing metalloid arsenite led to the accumulation of GFP-tagged Id3 in the cytoplasm. Cytoplasmic accumulation was impaired by a mutation in the Id3 NES-like sequence resembling the Id1 NES, located at the end of the HLH domain. It was also blocked by co-treatment with the CRM1-specific nuclear export inhibitor leptomycin B (LMB), but not with the inhibitors for mitogen-activated protein kinases (MAPKs). Importantly, we showed that the closely spaced N-terminal cysteine residues of Id3 interacted with the arsenic derivative phenylarsine oxide (PAO) and were essential for the arsenite-induced cytoplasmic accumulation, suggesting that arsenite induces the CRM1-dependent nuclear export of Id3 via binding to the N-terminal cysteines. Finally, we demonstrated that Id3 significantly repressed arsenite-stimulated transcription of the immediate-early gene Egr-1 and that this repression activity was inversely correlated with the arsenite-induced nuclear export. Our results imply that Id3 may be involved in the biological action of arsenite

Validating potential toxicity assays to assess petroleum hydrocarbon toxicity in polar soil.

Science.gov (United States)

Harvey, Alexis Nadine; Snape, Ian; Siciliano, Steven Douglas

2012-02-01

Potential microbial activities are commonly used to assess soil toxicity of petroleum hydrocarbons (PHC) and are assumed to be a surrogate for microbial activity within the soil ecosystem. However, this assumption needs to be evaluated for frozen soil, in which microbial activity is limited by liquid water (θ(liquid)). Influence of θ(liquid) on in situ toxicity was evaluated and compared to the toxicity endpoints of potential microbial activities using soil from an aged diesel fuel spill at Casey Station, East Antarctica. To determine in situ toxicity, gross mineralization and nitrification rates were determined by the stable isotope dilution technique. Petroleum hydrocarbon-contaminated soil (0-8,000 mg kg(-1)), packed at bulk densities of 1.4, 1.7, and 2.0 g cm(-3) to manipulate liquid water content, was incubated at -5°C for one, two, and three months. Although θ(liquid) did not have a significant effect on gross mineralization or nitrification, gross nitrification was sensitive to PHC contamination, with toxicity decreasing over time. In contrast, gross mineralization was not sensitive to PHC contamination. Toxic response of gross nitrification was comparable to potential nitrification activity (PNA) with similar EC25 (effective concentration causing a 25% effect in the test population) values determined by both measurement endpoints (400 mg kg(-1) for gross nitrification compared to 200 mg kg(-1) for PNA), indicating that potential microbial activity assays are good surrogates for in situ toxicity of PHC contamination in polar regions. Copyright © 2011 SETAC.

Pesticide Toxicity Index: a tool for assessing potential toxicity of pesticide mixtures to freshwater aquatic organisms

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Nowell, Lisa H.; Norman, Julia E.; Moran, Patrick W.; Martin, Jeffrey D.; Stone, Wesley W.

2014-01-01

Pesticide mixtures are common in streams with agricultural or urban influence in the watershed. The Pesticide Toxicity Index (PTI) is a screening tool to assess potential aquatic toxicity of complex pesticide mixtures by combining measures of pesticide exposure and acute toxicity in an additive toxic-unit model. The PTI is determined separately for fish, cladocerans, and benthic invertebrates. This study expands the number of pesticides and degradates included in previous editions of the PTI from 124 to 492 pesticides and degradates, and includes two types of PTI for use in different applications, depending on study objectives. The Median-PTI was calculated from median toxicity values for individual pesticides, so is robust to outliers and is appropriate for comparing relative potential toxicity among samples, sites, or pesticides. The Sensitive-PTI uses the 5th percentile of available toxicity values, so is a more sensitive screening-level indicator of potential toxicity. PTI predictions of toxicity in environmental samples were tested using data aggregated from published field studies that measured pesticide concentrations and toxicity to Ceriodaphnia dubia in ambient stream water. C. dubia survival was reduced to ≤ 50% of controls in 44% of samples with Median-PTI values of 0.1–1, and to 0% in 96% of samples with Median-PTI values > 1. The PTI is a relative, but quantitative, indicator of potential toxicity that can be used to evaluate relationships between pesticide exposure and biological condition.

Toxicity of Single and Mixed Contaminants in Seawater Measured with Acute Toxicity Bioassays

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A.R. Fernandez-Alba

2002-01-01

Full Text Available Different types of organic pollutants commonly detected in seawater have been evaluated by acute toxicity bioassays. Vibrio fischeri, Daphnia magna, and Selenastrum capricornotum were selected to test toxic effects of individual compounds and mixtures of these compounds, obtaining EC50 values in the range of 0.001 to 28.9 mg/l. In the case of mixtures, synergistic toxic responses were seen for a clear majority of the cases (>60%. Mixtures containing methyl-tertiary-butyl ether (MTBE exhibit accelerated processes that result in a change in concentration required to produce a toxic effect; for example, in the case of mixtures containing MTBE and Diuron and Dichlofluanid.

Building a developmental toxicity ontology.

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Baker, Nancy; Boobis, Alan; Burgoon, Lyle; Carney, Edward; Currie, Richard; Fritsche, Ellen; Knudsen, Thomas; Laffont, Madeleine; Piersma, Aldert H; Poole, Alan; Schneider, Steffen; Daston, George

2018-04-03

As more information is generated about modes of action for developmental toxicity and more data are generated using high-throughput and high-content technologies, it is becoming necessary to organize that information. This report discussed the need for a systematic representation of knowledge about developmental toxicity (i.e., an ontology) and proposes a method to build one based on knowledge of developmental biology and mode of action/ adverse outcome pathways in developmental toxicity. This report is the result of a consensus working group developing a plan to create an ontology for developmental toxicity that spans multiple levels of biological organization. This report provide a description of some of the challenges in building a developmental toxicity ontology and outlines a proposed methodology to meet those challenges. As the ontology is built on currently available web-based resources, a review of these resources is provided. Case studies on one of the most well-understood morphogens and developmental toxicants, retinoic acid, are presented as examples of how such an ontology might be developed. This report outlines an approach to construct a developmental toxicity ontology. Such an ontology will facilitate computer-based prediction of substances likely to induce human developmental toxicity. © 2018 Wiley Periodicals, Inc.

Mechanisms of Phosphine Toxicity

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Nisa S. Nath

2011-01-01

Full Text Available Fumigation with phosphine gas is by far the most widely used treatment for the protection of stored grain against insect pests. The development of high-level resistance in insects now threatens its continued use. As there is no suitable chemical to replace phosphine, it is essential to understand the mechanisms of phosphine toxicity to increase the effectiveness of resistance management. Because phosphine is such a simple molecule (PH3, the chemistry of phosphorus is central to its toxicity. The elements above and below phosphorus in the periodic table are nitrogen (N and arsenic (As, which also produce toxic hydrides, namely, NH3 and AsH3. The three hydrides cause related symptoms and similar changes to cellular and organismal physiology, including disruption of the sympathetic nervous system, suppressed energy metabolism and toxic changes to the redox state of the cell. We propose that these three effects are interdependent contributors to phosphine toxicity.

Toxicity Estimation Software Tool (TEST)

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The Toxicity Estimation Software Tool (TEST) was developed to allow users to easily estimate the toxicity of chemicals using Quantitative Structure Activity Relationships (QSARs) methodologies. QSARs are mathematical models used to predict measures of toxicity from the physical c...

Distributed Structure Searchable Toxicity

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U.S. Environmental Protection Agency — The Distributed Structure Searchable Toxicity (DSSTox) online resource provides high quality chemical structures and annotations in association with toxicity data....

Modeling Aquatic Toxicity through Chromatographic Systems.

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Fernández-Pumarega, Alejandro; Amézqueta, Susana; Farré, Sandra; Muñoz-Pascual, Laura; Abraham, Michael H; Fuguet, Elisabet; Rosés, Martí

2017-08-01

Environmental risk assessment requires information about the toxicity of the growing number of chemical products coming from different origins that can contaminate water and become toxicants to aquatic species or other living beings via the trophic chain. Direct toxicity measurements using sensitive aquatic species can be carried out but they may become expensive and ethically questionable. Literature refers to the use of chromatographic measurements that correlate to the toxic effect of a compound over a specific aquatic species as an alternative to get toxicity information. In this work, we have studied the similarity in the response of the toxicity to different species and we have selected eight representative aquatic species (including tadpoles, fish, water fleas, protozoan, and bacteria) with known nonspecific toxicity to chemical substances. Next, we have selected four chromatographic systems offering good perspectives for surrogation of the eight selected aquatic systems, and thus prediction of toxicity from the chromatographic measurement. Then toxicity has been correlated to the chromatographic retention factor. Satisfactory correlation results have been obtained to emulate toxicity in five of the selected aquatic species through some of the chromatographic systems. Other aquatic species with similar characteristics to these five representative ones could also be emulated by using the same chromatographic systems. The final aim of this study is to model chemical products toxicity to aquatic species by means of chromatographic systems to reduce in vivo testing.

Exploring the Impact of Toxic Attitudes and a Toxic Environment on the Veterinary Healthcare Team.

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Moore, Irene C; Coe, Jason B; Adams, Cindy L; Conlon, Peter D; Sargeant, Jan M

2015-01-01

The objective of this qualitative study was to compare veterinarians' and Registered Veterinary Technicians' (RVT's) perceptions of the veterinary healthcare team with respect to the impact of toxic attitudes and a toxic environment. Focus group interviews using a semi-structured interview guide and follow up probes were held with four veterinarian groups (23 companion animal veterinarians) and four Registered Veterinary Technician groups (26 RVTs). Thematic analysis of the discussions indicated both veterinarian and RVT participants felt team members with manifestations of toxic attitudes negatively impacted veterinary team function. These manifestations included people being disrespectful, being resistant to change, always wanting to be the "go to person," avoiding conflict, and lacking motivation. When conflict was ignored, or when people with toxic attitudes were not addressed, a toxic environment often resulted. A toxic environment sometimes manifested when "broken communication and tension between staff members" occurred as a result of employees lacking confidence, skills, or knowledge not being managed properly. It also occurred when employees did not feel appreciated, when there was difficulty coping with turnover, and when there were conflicting demands. The presence of people manifesting a toxic attitude was a source of frustration for both veterinarian and RVT participants. Prompt and consistent attention to negative behaviors is recommended to reduce the development of a toxic environment.

Influence of environmental parameters and of their interactions on the release of metal(loid)s from a construction material in hydraulic engineering.

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Schmukat, A; Duester, L; Goryunova, E; Ecker, D; Heininger, P; Ternes, T A

2016-03-05

Besides the leaching behaviour of a construction material under standardised test-specific conditions with laboratory water, for some construction materials it is advisable to test their environmental behaviour also under close to end use conditions. The envisaged end use combined with the product characteristics (e.g. mineral phases) is decisive for the choice of environmental factors that may change the release of substance that potentially cause adverse environmental effects (e.g. fertilisation or ecotoxicity). At the moment an experimental link is missing between mono-factorial standardised test systems and non standardised complex incubation experiments such as mesocosms which are closer to environmental conditions. Multi-factorial batch experiments may have the potential to close the gap. To verify this, batch experiments with copper slag were performed which is used as armour stones in hydraulic engineering. Design of experiments (DoE) was applied to evaluate the impact of pH, ionic strength, temperature and sediment content on the release of As, Cu, Mo, Ni, Pb, Sb and Zn. The study shows that release and sediment-eluent partitioning of metal(loid)s are impacted by interactions between the studied factors. Under the prevalent test conditions sediment acts as a sink enhancing most strongly the release of elements from the material. Copyright © 2015 Elsevier B.V. All rights reserved.

Performance of a pilot-scale constructed wetland system for treating simulated ash basin water.

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Dorman, Lane; Castle, James W; Rodgers, John H

2009-05-01

A pilot-scale constructed wetland treatment system (CWTS) was designed and built to decrease the concentration and toxicity of constituents of concern in ash basin water from coal-burning power plants. The CWTS was designed to promote the following treatment processes for metals and metalloids: precipitation as non-bioavailable sulfides, co-precipitation with iron oxyhydroxides, and adsorption onto iron oxides. Concentrations of Zn, Cr, Hg, As, and Se in simulated ash basin water were reduced by the CWTS to less than USEPA-recommended water quality criteria. The removal efficiency (defined as the percent concentration decrease from influent to effluent) was dependent on the influent concentration of the constituent, while the extent of removal (defined as the concentration of a constituent of concern in the CWTS effluent) was independent of the influent concentration. Results from toxicity experiments illustrated that the CWTS eliminated influent toxicity with regard to survival and reduced influent toxicity with regard to reproduction. Reduction in potential for scale formation and biofouling was achieved through treatment of the simulated ash basin water by the pilot-scale CWTS.

Organophosphorus insecticides: Toxic effects and bioanalytical tests for evaluating toxicity during degradation processes

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Čolović Mirjana B.

2013-01-01

Full Text Available Organophosphorus insecticides have been the most applied group of insecticides for the last two decades. Their main toxic effects are related to irreversible inactivation of acetylcholinesterase (AChE. Actually, they covalently bind to serine OH group in the enzyme active site forming phosphorylated enzyme that cannot hydrolyze acetylcholine. Organophosphorus insecticides in the environment undergo the natural degradation pathway including mainly homogeneous and heterogeneous hydrolysis (especially at high pH generating non-inhibiting products. Additionally, thio organophosphates are easily oxidized by naturally present oxidants and UV light, forming more toxic and stable oxons. Thus, oxidative degradation procedures, generally referred as advanced oxidation processes (AOP, have been applied for their efficient removal from contaminated waters. The most applied bioassays to monitor the organophosphate toxicity i.e. the detoxification degree during AOP are Vibrio fischeri and AChE bioassays. Vibrio fischeri toxicity test exploits bioluminescence as the measure of luciferase activity of this marine bacterium, whereas AChE bioassay is based on AChE activity inhibition. Both bioanalytical techniques are rapid (several minutes, simple, sensitive and reproducible. Vibrio fischeri test seems to be a versatile indicator of toxic compounds generated in AOP for organophosphorus insecticides degradation. However, detection of neurotoxic AChE inhibitors, which can be formed in AOP of some organophosphates, requires AChE bioassays. Therefore, AChE toxicity test is more appropriate for monitoring the degradation processes of thio organophosphates, because more toxic oxo organophosphates might be formed and overlooked by Vibrio fischeri bioluminescence inhibition. In addition, during organophosphates removal by AOP, compounds with strong genotoxic potential may be formed, which cannot be detected by standard toxicity tests. For this reason, determination of

Sensitivity of ecological soil-screening levels for metals to exposure model parameterization and toxicity reference values.

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Sample, Bradley E; Fairbrother, Anne; Kaiser, Ashley; Law, Sheryl; Adams, Bill

2014-10-01

Ecological soil-screening levels (Eco-SSLs) were developed by the United States Environmental Protection Agency (USEPA) for the purposes of setting conservative soil screening values that can be used to eliminate the need for further ecological assessment for specific analytes at a given site. Ecological soil-screening levels for wildlife represent a simplified dietary exposure model solved in terms of soil concentrations to produce exposure equal to a no-observed-adverse-effect toxicity reference value (TRV). Sensitivity analyses were performed for 6 avian and mammalian model species, and 16 metals/metalloids for which Eco-SSLs have been developed. The relative influence of model parameters was expressed as the absolute value of the range of variation observed in the resulting soil concentration when exposure is equal to the TRV. Rank analysis of variance was used to identify parameters with greatest influence on model output. For both birds and mammals, soil ingestion displayed the broadest overall range (variability), although TRVs consistently had the greatest influence on calculated soil concentrations; bioavailability in food was consistently the least influential parameter, although an important site-specific variable. Relative importance of parameters differed by trophic group. Soil ingestion ranked 2nd for carnivores and herbivores, but was 4th for invertivores. Different patterns were exhibited, depending on which parameter, trophic group, and analyte combination was considered. The approach for TRV selection was also examined in detail, with Cu as the representative analyte. The underlying assumption that generic body-weight-normalized TRVs can be used to derive protective levels for any species is not supported by the data. Whereas the use of site-, species-, and analyte-specific exposure parameters is recommended to reduce variation in exposure estimates (soil protection level), improvement of TRVs is more problematic. © 2014 The Authors

The Effects of Temperature and Hydrostatic Pressure on Metal Toxicity: Insights into Toxicity in the Deep Sea.

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Brown, Alastair; Thatje, Sven; Hauton, Chris

2017-09-05

Mineral prospecting in the deep sea is increasing, promoting concern regarding potential ecotoxicological impacts on deep-sea fauna. Technological difficulties in assessing toxicity in deep-sea species has promoted interest in developing shallow-water ecotoxicological proxy species. However, it is unclear how the low temperature and high hydrostatic pressure prevalent in the deep sea affect toxicity, and whether adaptation to deep-sea environmental conditions moderates any effects of these factors. To address these uncertainties we assessed the effects of temperature and hydrostatic pressure on lethal and sublethal (respiration rate, antioxidant enzyme activity) toxicity in acute (96 h) copper and cadmium exposures, using the shallow-water ecophysiological model organism Palaemon varians. Low temperature reduced toxicity in both metals, but reduced cadmium toxicity significantly more. In contrast, elevated hydrostatic pressure increased copper toxicity, but did not affect cadmium toxicity. The synergistic interaction between copper and cadmium was not affected by low temperature, but high hydrostatic pressure significantly enhanced the synergism. Differential environmental effects on toxicity suggest different mechanisms of action for copper and cadmium, and highlight that mechanistic understanding of toxicity is fundamental to predicting environmental effects on toxicity. Although results infer that sensitivity to toxicants differs across biogeographic ranges, shallow-water species may be suitable ecotoxicological proxies for deep-sea species, dependent on adaptation to habitats with similar environmental variability.