Sample records for nanosized hydrous manganese

  1. Nano-sized manganese oxides as biomimetic catalysts for water oxidation in artificial photosynthesis: a review

    PubMed Central

    Najafpour, Mohammad Mahdi; Rahimi, Fahimeh; Aro, Eva-Mari; Lee, Choon-Hwan; Allakhverdiev, Suleyman I.

    2012-01-01

    There has been a tremendous surge in research on the synthesis of various metal compounds aimed at simulating the water-oxidizing complex (WOC) of photosystem II (PSII). This is crucial because the water oxidation half reaction is overwhelmingly rate-limiting and needs high over-voltage (approx. 1 V), which results in low conversion efficiencies when working at current densities required for hydrogen production via water splitting. Particular attention has been given to the manganese compounds not only because manganese has been used by nature to oxidize water but also because manganese is cheap and environmentally friendly. The manganese–calcium cluster in PSII has a dimension of about approximately 0.5 nm. Thus, nano-sized manganese compounds might be good structural and functional models for the cluster. As in the nanometre-size of the synthetic models, most of the active sites are at the surface, these compounds could be more efficient catalysts than micrometre (or bigger) particles. In this paper, we focus on nano-sized manganese oxides as functional and structural models of the WOC of PSII for hydrogen production via water splitting and review nano-sized manganese oxides used in water oxidation by some research groups. PMID:22809849

  2. Novel synergistic hydrous iron-nickel-manganese (HINM) trimetal oxide for hazardous arsenite removal.

    PubMed

    Nasir, A M; Goh, P S; Ismail, A F

    2018-06-01

    A novel hydrous iron-nickel-manganese (HINM) trimetal oxide was successfully fabricated using oxidation and coprecipitation method for metalloid arsenite removal. The atomic ratio of Fe:Ni:Mn for this adsorbent is 3:2:1. HINM adsorbent was identified as an amorphous nanosized adsorbent with particle size ranged from 30 nm to 60 nm meanwhile the total active surface area and pore diameter of HINM area of 195.78 m 2 /g and 2.43 nm, respectively. Experimental data of arsenite adsorption is best fitted into pseudo-second order and Freundlich isotherm model. The maximum adsorption capacity of arsenite onto HINM was 81.9 mg/g. Thermodynamic study showed that the adsorption of arsenite was a spontaneous and endothermic reaction with enthalpy change of 14.04 kJ/mol and Gibbs energy of -12 to -14 kJ/mol. Zeta potential, thermal gravimetric (TGA) and Fourier transform infrared (FTIR) analysis were applied to elucidate the mechanism of arsenite adsorption by HINM. Mechanism of arsenite adsorption by HINM involved both chemisorption and physisorption based on the electrostatic attraction between arsenite ions and surface charge of HINM. It also involved the hydroxyl substitution by arsenite ions through the formation of inner-sphere complex. Reusability of HINM trimetal oxide was up to 89% after three cycles of testing implied that HINM trimetal oxide is a promising and practical adsorbent for arsenite. Copyright © 2018 Elsevier Ltd. All rights reserved.

  3. An engineered polypeptide around nano-sized manganese-calcium oxide: copying plants for water oxidation.

    PubMed

    Najafpour, Mohammad Mahdi; Ghobadi, Mohadeseh Zarei; Sarvi, Bahram; Haghighi, Behzad

    2015-09-14

    Synthesis of new efficient catalysts inspired by Nature is a key goal in the production of clean fuel. Different compounds based on manganese oxide have been investigated in order to find their water-oxidation activity. Herein, we introduce a novel engineered polypeptide containing tyrosine around nano-sized manganese-calcium oxide, which was shown to be a highly active catalyst toward water oxidation at low overpotential (240 mV), with high turnover frequency of 1.5 × 10(-2) s(-1) at pH = 6.3 in the Mn(III)/Mn(IV) oxidation range. The compound is a novel structural and efficient functional model for the water-oxidizing complex in Photosystem II. A new proposed clever strategy used by Nature in water oxidation is also discussed. The new model of the water-oxidizing complex opens a new perspective for synthesis of efficient water-oxidation catalysts.

  4. Proposed mechanisms for water oxidation by Photosystem II and nanosized manganese oxides.

    PubMed

    Najafpour, Mohamad Mahdi; Heidari, Sima; Balaghi, S Esmael; Hołyńska, Małgorzata; Sadr, Moayad Hossaini; Soltani, Behzad; Khatamian, Maasoumeh; Larkum, Anthony W; Allakhverdiev, Suleyman I

    2017-02-01

    Plants, algae and cyanobacteria capture sunlight, extracting electrons from H 2 O to reduce CO 2 into sugars while releasing O 2 in the oxygenic photosynthetic process. Because of the important role of water oxidation in artificial photosynthesis and many solar fuel systems, understanding the structure and function of this unique biological catalyst forms a requisite research field. Herein the structure of the water-oxidizing complex and its ligand environment are described with reference to the 1.9Å resolution X-ray-derived crystallographic model of the water-oxidizing complex from the cyanobacterium Thermosynechococcus vulcanus. Proposed mechanisms for water oxidation by Photosystem II and nanosized manganese oxides are also reviewed and discussed in the paper. Copyright © 2016 Elsevier B.V. All rights reserved.

  5. QSAR analysis for nano-sized layered manganese-calcium oxide in water oxidation: An application of chemometric methods in artificial photosynthesis.

    PubMed

    Shahbazy, Mohammad; Kompany-Zareh, Mohsen; Najafpour, Mohammad Mahdi

    2015-11-01

    Water oxidation is among the most important reactions in artificial photosynthesis, and nano-sized layered manganese-calcium oxides are efficient catalysts toward this reaction. Herein, a quantitative structure-activity relationship (QSAR) model was constructed to predict the catalytic activities of twenty manganese-calcium oxides toward water oxidation using multiple linear regression (MLR) and genetic algorithm (GA) for multivariate calibration and feature selection, respectively. Although there are eight controlled parameters during synthesizing of the desired catalysts including ripening time, temperature, manganese content, calcium content, potassium content, the ratio of calcium:manganese, the average manganese oxidation state and the surface of catalyst, by using GA only three of them (potassium content, the ratio of calcium:manganese and the average manganese oxidation state) were selected as the most effective parameters on catalytic activities of these compounds. The model's accuracy criteria such as R(2)test and Q(2)test in order to predict catalytic rate for external test set experiments; were equal to 0.941 and 0.906, respectively. Therefore, model reveals acceptable capability to anticipate the catalytic activity. Copyright © 2015 Elsevier B.V. All rights reserved.

  6. Development of Surface Complexation Models of Cr(VI) Adsorption on Soils, Sediments and Model Mixtures of Kaolinite, Montmorillonite, γ-Alumina, Hydrous Manganese and Ferric Oxides and Goethite

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Koretsky, Carla

    Hexavalent chromium is a highly toxic contaminant that has been introduced into aquifers and shallow sediments and soils via many anthropogenic activities. Hexavalent chromium contamination is a problem or potential problem in the shallow subsurface at several DOE sites, including Hanford, Idaho National Laboratory, Los Alamos National Laboratory and the Oak Ridge Reservation (DOE, 2008). To accurately quantify the fate and transport of hexavalent chromium at DOE and other contaminated sites, robust geochemical models, capable of correctly predicting changes in chromium chemical form resulting from chemical reactions occurring in subsurface environments are needed. One important chemical reaction that may greatlymore » impact the bioavailability and mobility of hexavalent chromium in the subsurface is chemical binding to the surfaces of particulates, termed adsorption or surface complexation. Quantitative thermodynamic surface complexation models have been derived that can correctly calculate hexavalent chromium adsorption on well-characterized materials over ranges in subsurface conditions, such pH and salinity. However, models have not yet been developed for hexavalent chromium adsorption on many important constituents of natural soils and sediments, such as clay minerals. Furthermore, most of the existing thermodynamic models have been developed for relatively simple, single solid systems and have rarely been tested for the complex mixtures of solids present in real sediments and soils. In this study, the adsorption of hexavalent chromium was measured as a function of pH (3-10), salinity (0.001 to 0.1 M NaNO3), and partial pressure of carbon dioxide(0-5%) on a suite of naturally-occurring solids including goethite (FeOOH), hydrous manganese oxide (MnOOH), hydrous ferric oxide (Fe(OH)3), γ-alumina (Al2O3), kaolinite (Al2Si2O5(OH)4), and montmorillonite (Na3(Al, Mg)2Si4O10(OH)2-nH2O). The results show that all of these materials can bind substantial quantities

  7. Production of Manganese Oxide Nanoparticles by Shewanella Species

    PubMed Central

    Farooqui, Saad M.; White, Alan R.

    2016-01-01

    ABSTRACT Several species of the bacterial genus Shewanella are well-known dissimilatory reducers of manganese under anaerobic conditions. In fact, Shewanella oneidensis is one of the most well studied of all metal-reducing bacteria. In the current study, a number of Shewanella strains were tested for manganese-oxidizing capacity under aerobic conditions. All were able to oxidize Mn(II) and to produce solid dark brown manganese oxides. Shewanella loihica strain PV-4 was the strongest oxidizer, producing oxides at a rate of 20.3 mg/liter/day and oxidizing Mn(II) concentrations of up to 9 mM. In contrast, S. oneidensis MR-1 was the weakest oxidizer tested, producing oxides at 4.4 mg/liter/day and oxidizing up to 4 mM Mn(II). Analysis of products from the strongest oxidizers, i.e., S. loihica PV-4 and Shewanella putrefaciens CN-32, revealed finely grained, nanosize, poorly crystalline oxide particles with identical Mn oxidation states of 3.86. The biogenic manganese oxide products could be subsequently reduced within 2 days by all of the Shewanella strains when culture conditions were made anoxic and an appropriate nutrient (lactate) was added. While Shewanella species were detected previously as part of manganese-oxidizing consortia in natural environments, the current study has clearly shown manganese-reducing Shewanella species bacteria that are able to oxidize manganese in aerobic cultures. IMPORTANCE Members of the genus Shewanella are well known as dissimilatory manganese-reducing bacteria. This study shows that a number of species from Shewanella are also capable of manganese oxidation under aerobic conditions. Characterization of the products of the two most efficient oxidizers, S. loihica and S. putrefaciens, revealed finely grained, nanosize oxide particles. With a change in culture conditions, the manganese oxide products could be subsequently reduced by the same bacteria. The ability of Shewanella species both to oxidize and to reduce manganese indicates

  8. Modeling sorption of divalent metal cations on hydrous manganese oxide using the diffuse double layer model

    USGS Publications Warehouse

    Tonkin, J.W.; Balistrieri, L.S.; Murray, J.W.

    2004-01-01

    Manganese oxides are important scavengers of trace metals and other contaminants in the environment. The inclusion of Mn oxides in predictive models, however, has been difficult due to the lack of a comprehensive set of sorption reactions consistent with a given surface complexation model (SCM), and the discrepancies between published sorption data and predictions using the available models. The authors have compiled a set of surface complexation reactions for synthetic hydrous Mn oxide (HMO) using a two surface site model and the diffuse double layer SCM which complements databases developed for hydrous Fe (III) oxide, goethite and crystalline Al oxide. This compilation encompasses a range of data observed in the literature for the complex HMO surface and provides an error envelope for predictions not well defined by fitting parameters for single or limited data sets. Data describing surface characteristics and cation sorption were compiled from the literature for the synthetic HMO phases birnessite, vernadite and ??-MnO2. A specific surface area of 746 m2g-1 and a surface site density of 2.1 mmol g-1 were determined from crystallographic data and considered fixed parameters in the model. Potentiometric titration data sets were adjusted to a pH1EP value of 2.2. Two site types (???XOH and ???YOH) were used. The fraction of total sites attributed to ???XOH (??) and pKa2 were optimized for each of 7 published potentiometric titration data sets using the computer program FITEQL3.2. pKa2 values of 2.35??0.077 (???XOH) and 6.06??0.040 (???YOH) were determined at the 95% confidence level. The calculated average ?? value was 0.64, with high and low values ranging from 1.0 to 0.24, respectively. pKa2 and ?? values and published cation sorption data were used subsequently to determine equilibrium surface complexation constants for Ba2+, Ca2+, Cd 2+, Co2+, Cu2+, Mg2+, Mn 2+, Ni2+, Pb2+, Sr2+ and Zn 2+. In addition, average model parameters were used to predict additional

  9. Morphology and phase identification of micron to nanosized manganese oxide (MnO) with variations in sintering time

    NASA Astrophysics Data System (ADS)

    Sasongko, Muhammad Ilman Nur; Puspitasari, Poppy; Yazirin, Cepi; Tsamroh, Dewi Izzatus; Risdanareni, Puput

    2017-09-01

    Manganese oxide (MnO) occurs in many rock types and may take the form of minerals. MnO has its drawbacks, namely highly reactive oxidizing species classified as dangerous and explosive at temperatures above 55 °C. Despite this,MnO has excellent magnetic, electrochemical, and conductivity properties, which should be reduced to nano-size to maximize their use and improve the properties of MnO. Phase and morphology characterization of powder this research aims to reduce the grain size of the MnO from micro to nano using the sol-gel method with various sintering times. Sol-gel is a simple synthesis method that has been proven capable of synthesizing a wide variety of micro-sized oxide materials into nano. Sintering time is a technique performed in the synthesis process to dry the material to a temperature above the normal temperature. The temperature used for sintering starting from 600 °C to 1000 °C. Characterizations were done using XRD, SEM, EDX, and FTIR machines. The sintering processes in this study used a temperature of 600 °C with different sintering periods of 30, 60 and 90 minutes. The XRD characterization with a 30-minute sintering time resulted in the smallest MnO in the form crystalline powder of 47.3 nm. The highest intensity (degree of crystallinity) found in MnO sintered for 90 minutes. The results of the morphological characterization of SEM showed a morphological change in MnO from micro-sized triangular to nano-sized spherical shape. The EDX characterization results indicated that the 30-minute sintering caused the lowest change in Mn and the highest change in O. The results of FTIR characterization showed a shift in C-H and Mn-O followed by an increase in the group of N-H, C=O and Mn-O.

  10. Thin film hydrous metal oxide catalysts

    DOEpatents

    Dosch, Robert G.; Stephens, Howard P.

    1995-01-01

    Thin film (<100 nm) hydrous metal oxide catalysts are prepared by 1) synthesis of a hydrous metal oxide, 2) deposition of the hydrous metal oxide upon an inert support surface, 3) ion exchange with catalytically active metals, and 4) activating the hydrous metal oxide catalysts.

  11. Recent advances in nanosized Mn-Zn ferrite magnetic fluid hyperthermia for cancer treatment.

    PubMed

    Lin, Mei; Huang, Junxing; Sha, Min

    2014-01-01

    This paper reviews the recent research and development of nanosized manganese zinc (Mn-Zn) ferrite magnetic fluid hyperthermia (MFH) for cancer treatment. Mn-Zn ferrite MFH, which has a targeted positioning function that only the temperature of tumor tissue with magnetic nanoparticles can rise, while normal tissue without magnetic nanoparticles is not subject to thermal damage, is a promising therapy for cancer. We introduce briefly the composition and properties of magnetic fluid, the concept of MFH, and features of Mn-Zn ferrite magnetic nanoparticles for MFH such as thermal bystander effect, universality, high specific absorption rate, the targeting effect of small size, uniformity of hyperthermia temperature, and automatic temperature control and constant temperature effect. Next, preparation methods of Mn-Zn ferrite magnetic fluid are discussed, and biocompatibility and biosecurity of Mn-Zn ferrite magnetic fluid are analyzed. Then the applications of nanosized Mn-Zn ferrite MFH in cancer are highlighted, including nanosized Mn-Zn ferrite MFH alone, nanosized Mn-Zn ferrite MFH combined with As2O3 chemotherapy, and nanosized Mn-Zn ferrite MFH combined with radiotherapy. Finally, the combination application of nanosized Mn-Zn ferrite MFH and gene-therapy is conceived, and the challenges and perspectives for the future of nanosized Mn-Zn ferrite MFH for oncotherapy are discussed.

  12. Thermodynamics of Manganese Oxides at Bulk and Nanoscale: Phase Formation, Transformation, Oxidation-Reduction, and Hydration

    NASA Astrophysics Data System (ADS)

    Birkner, Nancy R.

    Natural manganese oxides are generally formed in surficial environments that are near ambient temperature and water-rich, and may be exposed to wet-dry cycles and a variety of adsorbate species that influence dramatically their level of hydration. Manganese oxide minerals are often poorly crystalline, nanophase, and hydrous. In the near-surface environment they are involved in processes that are important to life, such as water column oxygen cycling, biomineralization, and transport of minerals/nutrients through soils and water. These processes, often involving transformations among manganese oxide polymorphs, are governed by a complex interplay between thermodynamics and kinetics. Manganese oxides are also used in technology as catalysts, and for other applications. The major goal of this dissertation is to examine the energetics of bulk and nanophase manganese oxide phases as a function of particle size, composition, and surface hydration. Careful synthesis and characterization of manganese oxide phases with different surface areas provided samples for the study of enthalpies of formation by high temperature oxide melt solution calorimetry and of the energetics of water adsorption on their surfaces. These data provide a quantitative picture of phase stability and how it changes at the nanoscale. The surface energy of the hydrous surface of Mn3O4 is 0.96 +/- 0.08 J/m2, of Mn2O3 is 1.29 +/- 0.10 J/m2, and of MnO2 is 1.64 +/- 0.10 J/m2. The surface energy of the anhydrous surface of Mn3O4 is 1.62 +/- 0.08 J/m 2, of Mn2O3 is 1.77 +/- 0.10 J/m 2, and of MnO2 is 2.05 +/- 0.10 J/m2. Supporting preliminary findings (Navrotsky et al., 2010), the spinel phase (Mn3O4) has a lower surface energy (more stabilizing) than bixbyite, while the latter has a smaller surface energy than pyrolusite. These differences significantly change the positions in oxygen fugacity---temperature space of the redox couples Mn3O4-Mn2O 3 and Mn2O3-MnO2 favoring the lower surface enthalpy phase (the

  13. Method for preparing hydrous zirconium oxide gels and spherules

    DOEpatents

    Collins, Jack L.

    2003-08-05

    Methods for preparing hydrous zirconium oxide spherules, hydrous zirconium oxide gels such as gel slabs, films, capillary and electrophoresis gels, zirconium monohydrogen phosphate spherules, hydrous zirconium oxide spherules having suspendable particles homogeneously embedded within to form a composite sorbent, zirconium monohydrogen phosphate spherules having suspendable particles of at least one different sorbent homogeneously embedded within to form a composite sorbent having a desired crystallinity, zirconium oxide spherules having suspendable particles homogeneously embedded within to form a composite, hydrous zirconium oxide fiber materials, zirconium oxide fiber materials, hydrous zirconium oxide fiber materials having suspendable particles homogeneously embedded within to form a composite, zirconium oxide fiber materials having suspendable particles homogeneously embedded within to form a composite and spherules of barium zirconate. The hydrous zirconium oxide spherules and gel forms prepared by the gel-sphere, internal gelation process are useful as inorganic ion exchangers, catalysts, getters and ceramics.

  14. Adsorption of arsenite and selenite using an inorganic ion exchanger based on Fe-Mn hydrous oxide.

    PubMed

    Szlachta, Małgorzata; Gerda, Vasyl; Chubar, Natalia

    2012-01-01

    The adsorption behaviour and mechanism of As(III) and Se(IV) oxyanion uptake using a mixed inorganic adsorbent were studied. The novel adsorbent, based on Fe(III)-Mn(III) hydrous oxides and manganese(II) carbonate, was synthesised using a hydrothermal precipitation approach in the presence of urea. The inorganic ion exchanger exhibited a high selectivity and adsorptive capacity towards As(III) (up to 47.6 mg/g) and Se(IV) (up to 29.0 mg/g), even at low equilibrium concentration. Although pH effects were typical for anionic species (i.e., the adsorption decreased upon pH increase), Se(IV) was more sensitive to pH changes than As(III). The rates of adsorption of both oxyanions were high. Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS) studies showed that the ion exchange adsorption of both anions took place via OH(-) groups, mainly from Fe(III) but also Mn(III) hydrous oxides. MnCO(3) did not contribute directly to As(III) and Se(IV) removal. A higher adsorptive capacity of the developed material towards As(III) was partly due to partial As(III) oxidation during adsorption. Copyright © 2011 Elsevier Inc. All rights reserved.

  15. Method for preparing hydrous iron oxide gels and spherules

    DOEpatents

    Collins, Jack L.; Lauf, Robert J.; Anderson, Kimberly K.

    2003-07-29

    The present invention is directed to methods for preparing hydrous iron oxide spherules, hydrous iron oxide gels such as gel slabs, films, capillary and electrophoresis gels, iron monohydrogen phosphate spherules, hydrous iron oxide spherules having suspendable particles homogeneously embedded within to form composite sorbents and catalysts, iron monohydrogen phosphate spherules having suspendable particles of at least one different sorbent homogeneously embedded within to form a composite sorbent, iron oxide spherules having suspendable particles homogeneously embedded within to form a composite of hydrous iron oxide fiber materials, iron oxide fiber materials, hydrous iron oxide fiber materials having suspendable particles homogeneously embedded within to form a composite, iron oxide fiber materials having suspendable particles homogeneously embedded within to form a composite, dielectric spherules of barium, strontium, and lead ferrites and mixtures thereof, and composite catalytic spherules of barium or strontium ferrite embedded with oxides of Mg, Zn, Pb, Ce and mixtures thereof. These variations of hydrous iron oxide spherules and gel forms prepared by the gel-sphere, internal gelation process offer more useful forms of inorganic ion exchangers, catalysts, getters, dielectrics, and ceramics.

  16. Effective removal of trace thallium from surface water by nanosized manganese dioxide enhanced quartz sand filtration.

    PubMed

    Huangfu, Xiaoliu; Ma, Chengxue; Ma, Jun; He, Qiang; Yang, Chun; Zhou, Jian; Jiang, Jin; Wang, Yaan

    2017-12-01

    Thallium (Tl) has drawn wide concern due to its high toxicity even at extremely low concentrations, as well as its tendency for significant accumulation in the human body and other organisms. The need to develop effective strategies for trace Tl removal from drinking water is urgent. In this study, the removal of trace Tl (0.5 μg L -1 ) by conventional quartz sand filtration enhanced by nanosized manganese dioxide (nMnO 2 ) has been investigated using typical surface water obtained from northeast China. The results indicate that nMnO 2 enhanced quartz sand filtration could remove trace Tl(I) and Tl(III) efficiently through the adsorption of Tl onto nMnO 2 added to a water matrix and onto nMnO 2 attached on quartz sand surfaces. Tl(III)-HA complexes might be responsible for higher residual Tl(III) in the effluent compared to residual Tl(I). Competitive Ca 2+ cations inhibit Tl removal to a certain extent because the Ca 2+ ions will occupy the Tl adsorption site on nMnO 2 . Moreover, high concentrations of HA (10 mgTOC L -1 ), which notably complexes with and dissolves nMnO 2 (more than 78%), resulted in higher residual Tl(I) and Tl(III). Tl(III)-HA complexes might also enhance Tl(III) penetration to a certain extent. Additionally, a higher pH level could enhance the removal of trace Tl from surface water. Finally, a slight increase of residual Tl was observed after backwash, followed by the reduction of the Tl concentration in the effluent to a "steady" state again. The knowledge obtained here may provide a potential strategy for drinking water treatment plants threatened by trace Tl. Copyright © 2017. Published by Elsevier Ltd.

  17. Small-scale hydrous pyrolysis of macromolecular material in meteorites

    NASA Astrophysics Data System (ADS)

    Sephton, M. A.; Pillinger, C. T.; Gilmour, I.

    1998-12-01

    The hydrous pyrolysis method, usually performed on several hundred grams of terrestrial rock sample, has been scaled down to accommodate less than two grams of meteorite sample. This technique makes full use of the high yields associated with hydrous pyrolysis experiments and permits the investigation of the meteorite macromolecular material, the major organic component in carbonaceous meteorites. The hydrous pyrolysis procedure transforms the high molecular weight macromolecular material into low molecular weight fragments. The released entities can then be extracted with supercritical fluid extraction. In contrast to the parent structure, the pyrolysis products are amenable for analysis by gas chromatography-based techniques. When subjected to hydrous pyrolysis, two carbonaceous chondrites (Orgueil and Cold Bokkeveld) released generally similar products, which consisted of abundant volatile aromatic and alkyl-substituted aromatic compounds. These results revealed the ability of small-scale hydrous pyrolysis to dissect extraterrestrial macromolecular material and thereby reveal its organic constitution.

  18. Derivation of hydrous pyrolysis kinetic parameters from open-system pyrolysis

    NASA Astrophysics Data System (ADS)

    Tseng, Yu-Hsin; Huang, Wuu-Liang

    2010-05-01

    Kinetic information is essential to predict the temperature, timing or depth of hydrocarbon generation within a hydrocarbon system. The most common experiments for deriving kinetic parameters are mainly by open-system pyrolysis. However, it has been shown that the conditions of open-system pyrolysis are deviant from nature by its low near-ambient pressure and high temperatures. Also, the extrapolation of heating rates in open-system pyrolysis to geological conditions may be questionable. Recent study of Lewan and Ruble shows hydrous-pyrolysis conditions can simulate the natural conditions better and its applications are supported by two case studies with natural thermal-burial histories. Nevertheless, performing hydrous pyrolysis experiment is really tedious and requires large amount of sample, while open-system pyrolysis is rather convenient and efficient. Therefore, the present study aims at the derivation of convincing distributed hydrous pyrolysis Ea with only routine open-system Rock-Eval data. Our results unveil that there is a good correlation between open-system Rock-Eval parameter Tmax and the activation energy (Ea) derived from hydrous pyrolysis. The hydrous pyrolysis single Ea can be predicted from Tmax based on the correlation, while the frequency factor (A0) is estimated based on the linear relationship between single Ea and log A0. Because the Ea distribution is more rational than single Ea, we modify the predicted single hydrous pyrolysis Ea into distributed Ea by shifting the pattern of Ea distribution from open-system pyrolysis until the weight mean Ea distribution equals to the single hydrous pyrolysis Ea. Moreover, it has been shown that the shape of the Ea distribution is very much alike the shape of Tmax curve. Thus, in case of the absence of open-system Ea distribution, we may use the shape of Tmax curve to get the distributed hydrous pyrolysis Ea. The study offers a new approach as a simple method for obtaining distributed hydrous pyrolysis

  19. Phase transition and equation of state of dense hydrous silica up to 63 GPa: DENSE HYDROUS PURE SILICA

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Nisr, C.; Leinenweber, K.; Prakapenka, V.

    Although it has previously been considered to be essentially anhydrous, Al-free stishovite can contain up to ~1.3 wt % of H2O, perhaps through the direct substitution ( math formula), according to recent studies. Yet the stability of such substitution and its impact on the properties of silica and rutile-structured hydrous phases (such as δ-AlOOH and phase H) are unknown at the conditions of the deeper mantle. We have synthesized hydrous and anhydrous Al-free stishovite samples at 723 K and 9 GPa, and 1473 K and 10 GPa, respectively. Synchrotron X-ray diffraction patterns show that the unit cell volume of hydrousmore » stishovite is 1.3% greater than that of anhydrous stishovite at 1 bar, suggesting significant incorporation of OH in the crystal structure (3.2 ± 0.5 wt % H2O). At 300 K, we found a lower and broader transition pressure from rutile type to CaCl2 type (28–42 GPa) in hydrous dense silica. We also found that hydrous silica polymorphs are more compressible than their anhydrous counterparts. After the phase transition, the unit cell volume of hydrous silica becomes the same as that of anhydrous silica, showing that the proton incorporation through a direct substitution can be further stabilized at high pressure. The lower pressure transition and the pressure stabilization of the proton incorporation in silica would provide ways to transport and store water in the lower mantle in silica-rich heterogeneities, such as subducted oceanic crust.« less

  20. Mineralogy of the Hydrous Lower Mantle

    NASA Astrophysics Data System (ADS)

    Shim, S. H.; Chen, H.; Leinenweber, K. D.; Kunz, M.; Prakapenka, V.; Bechtel, H.; Liu, Z.

    2017-12-01

    The hydrous ringwoodite inclusions found in diamonds suggest water storage in the mantle transition zone. However, water storage in the lower mantle remains unclear. Bridgmanite and magnesiowustite appear to have very little storage capacity for water. Here, we report experimental results indicating significant changes in the lower-mantle mineralogy under the presence of water. We have synthesized Mg2SiO4 ringwoodite with 2 wt% water in multi-anvil press at 20 GPa and 1573 K at ASU. The hydrous ringwoodite sample was then loaded to diamond anvil cells with Ar or Ne as a pressure medium. We heated the pure hydrous ringwoodite samples at lower-mantle pressure using a CO2 laser heating system at ASU. We measured X-ray diffraction patterns at the GSECARS sector of the Advanced Photon Source (APS) and 12.2.2 sector of the Advanced Light Source (ALS). For the separate Pt-mixed samples, we have conducted in situ heating at the beamlines using near IR laser heating systems. We measured the infrared spectra of the heated samples at high pressure and after pressure quench at 1.4.4 sector of ALS. In the in situ experiments with hydrous ringwoodite + Pt mixture as a starting material, we found formation of stishovite together with bridgmanite and periclase during heating with a near IR laser beams at 1300-2500 K and 35-66 GPa. However, some hydrous ringwoodite still remains even after a total of 45 min of heating. In contrast, the hydrous ringwoodite samples heated without Pt by CO2 laser beams are transformed completely to bridgmanite, periclase and stishovite at 31-55 GPa and 1600-1900 K. We have detected IR active OH mode of stishovite from the samples heated at lower-mantle pressures. The unit-cell volume of stishovite measured after pressure quench is greater than that of dry stishovite by 0.3-0.6%, supporting 0.5-1 wt% of H2O in stishovite in these samples. Stishovite is a thermodynamically forbidden phase in the dry lower mantle because of the existence of periclase and

  1. Crystallization of biogenic hydrous amorphous silica

    NASA Astrophysics Data System (ADS)

    Kyono, A.; Yokooji, M.; Chiba, T.; Tamura, T.; Tuji, A.

    2017-12-01

    Diatom, Nitzschia cf. frustulum, collected from Lake Yogo, Siga prefecture, Japan was cultured in laboratory. Organic components of the diatom cell were removed by washing with acetone and sodium hypochlorite. The remaining frustules were studied by SEM-EDX, FTIR spectroscopy, and synchrotron X-ray diffraction. The results showed that the spindle-shaped morphology of diatom frustule was composed of hydrous amorphous silica. Pressure induced phase transformation of the diatom frustule was investigated by in situ Raman spectroscopic analysis. With exposure to 0.3 GPa at 100 oC, Raman band corresponding to quartz occurred at ν = 465 cm-1. In addition, Raman bands known as a characteristic Raman pattern of moganite was also observed at 501 cm-1. From the integral ratio of Raman bands, the moganite content in the probed area was estimated to be approximately 50 wt%. With the pressure and temperature effect, the initial morphology of diatom frustule was completely lost and totally changed to a characteristic spherical particle with a diameter of about 2 mm. With keeping the compression of 5.7 GPa at 100 oC, a Raman band assignable to coesite appeared at 538 cm-1. That is, with the compression and heating, the hydrous amorphous silica can be readily crystallized into quartz, moganite, and coesite. The first-principles calculations revealed that a disiloxane molecule stabilized in a trans configuration is twisted 60o and changed into the cis configuration with a close approach of water molecule. It is therefore a reasonable assumption that during crystallization of hydrous amorphous silica, the Si-O-Si bridging unit with the cis configuration would survive as a structural defect and then crystallized into moganite by keeping the geometry. This hypothesis is adaptable to the phase transformation from hydrous amorphous silica to coesite as well, because coesite has the four-membered rings and easily formed from the hydrous amorphous silica under high pressure and high

  2. Quantification of water in hydrous ringwoodite

    DOE PAGES

    Thomas, Sylvia -Monique; Jacobsen, Steven D.; Bina, Craig R.; ...

    2015-01-28

    Here, ringwoodite, γ-(Mg,Fe) 2SiO 4, in the lower 150 km of Earth’s mantle transition zone (410-660 km depth) can incorporate up to 1.5-2 wt% H 2O as hydroxyl defects. We present a mineral-specific IR calibration for the absolute water content in hydrous ringwoodite by combining results from Raman spectroscopy, secondary ion mass spectrometery (SIMS) and proton-proton (pp)-scattering on a suite of synthetic Mg- and Fe-bearing hydrous ringwoodites. H 2O concentrations in the crystals studied here range from 0.46 to 1.7 wt% H 2O (absolute methods), with the maximum H 2O in the same sample giving 2.5 wt% by SIMS calibration.more » Anchoring our spectroscopic results to absolute H-atom concentrations from pp-scattering measurements, we report frequency-dependent integrated IR-absorption coefficients for water in ringwoodite ranging from 78180 to 158880 L mol -1cm -2, depending upon frequency of the OH absorption. We further report a linear wavenumber IR calibration for H 2O quantification in hydrous ringwoodite across the Mg 2SiO 4-Fe 2SiO 4 solid solution, which will lead to more accurate estimations of the water content in both laboratory-grown and naturally occurring ringwoodites. Re-evaluation of the IR spectrum for a natural hydrous ringwoodite inclusion in diamond from the study of the crystal contains 1.43 ± 0.27 wt% H 2O, thus confirming near-maximum amounts of H 2O for this sample from the transition zone.« less

  3. On the dielectric dispersion and absorption in nanosized manganese zinc mixed ferrites.

    PubMed

    Veena Gopalan, E; Malini, K A; Sakthi Kumar, D; Yoshida, Yasuhiko; Al-Omari, I A; Saravanan, S; Anantharaman, M R

    2009-04-08

    The temperature and frequency dependence of dielectric permittivity and dielectric loss of nanosized Mn(1-x)Zn(x)Fe(2)O(4) (for x = 0, 0.2, 0.4, 0.6, 0.8, 1) were investigated. The impact of zinc substitution on the dielectric properties of the mixed ferrite is elucidated. Strong dielectric dispersion and broad relaxation were exhibited by Mn(1-x)Zn(x)Fe(2)O(4). The variation of dielectric relaxation time with temperature suggests the involvement of multiple relaxation processes. Cole-Cole plots were employed as an effective tool for studying the observed phenomenon. The activation energies were calculated from relaxation peaks and Cole-Cole plots and found to be consistent with each other and indicative of a polaron conduction.

  4. Method for preparing hydrous titanium oxide spherules and other gel forms thereof

    DOEpatents

    Collins, J.L.

    1998-10-13

    The present invention are methods for preparing hydrous titanium oxide spherules, hydrous titanium oxide gels such as gel slabs, films, capillary and electrophoresis gels, titanium monohydrogen phosphate spherules, hydrous titanium oxide spherules having suspendible particles homogeneously embedded within to form a composite sorbent, titanium monohydrogen phosphate spherules having suspendible particles of at least one different sorbent homogeneously embedded within to form a composite sorbent having a desired crystallinity, titanium oxide spherules in the form of anatase, brookite or rutile, titanium oxide spherules having suspendible particles homogeneously embedded within to form a composite, hydrous titanium oxide fiber materials, titanium oxide fiber materials, hydrous titanium oxide fiber materials having suspendible particles homogeneously embedded within to form a composite, titanium oxide fiber materials having suspendible particles homogeneously embedded within to form a composite and spherules of barium titanate. These variations of hydrous titanium oxide spherules and gel forms prepared by the gel-sphere, internal gelation process offer more useful forms of inorganic ion exchangers, catalysts, getters and ceramics. 6 figs.

  5. Method for preparing hydrous titanium oxide spherules and other gel forms thereof

    DOEpatents

    Collins, Jack L.

    1998-01-01

    The present invention are methods for preparing hydrous titanium oxide spherules, hydrous titanium oxide gels such as gel slabs, films, capillary and electrophoresis gels, titanium monohydrogen phosphate spherules, hydrous titanium oxide spherules having suspendible particles homogeneously embedded within to form a composite sorbent, titanium monohydrogen phosphate spherules having suspendible particles of at least one different sorbent homogeneously embedded within to form a composite sorbent having a desired crystallinity, titanium oxide spherules in the form of anatase, brookite or rutile, titanium oxide spherules having suspendible particles homogeneously embedded within to form a composite, hydrous titanium oxide fiber materials, titanium oxide fiber materials, hydrous titanium oxide fiber materials having suspendible particles homogeneously embedded within to form a composite, titanium oxide fiber materials having suspendible particles homogeneously embedded within to form a composite and spherules of barium titanate. These variations of hydrous titanium oxide spherules and gel forms prepared by the gel-sphere, internal gelation process offer more useful forms of inorganic ion exchangers, catalysts, getters and ceramics.

  6. Manganese

    MedlinePlus

    ... de Manganèse, Dioxyde de Manganèse, Gluconate de Manganèse, Glycérophosphate de Manganèse, Manganèse, Manganese Amino Acid Chelate, Manganese ... Chloridetetrahydrate, Manganese Citrate, Manganese Dioxide, Manganese ... Sulfate, Manganese Sulfate Monohydrate, Manganese Sulfate Tetrahydrate, ...

  7. The heat capacity of hydrous cordierite above 295 K

    NASA Astrophysics Data System (ADS)

    Carey, J. William

    1993-04-01

    The heat capacity of synthetic hydrous cordierite (Mg2Al4Si5O18·nH2O) has been determined by differential scanning calorimetry (DSC) from 295 to 425 K as a function of H2O content. Six samples with H2O contents ranging from 0 to 0.82 per formula unit were examined. The partial molar heat capacity of H2O in cordierite over the measured temperature interval is independent of composition and temperature within experimental uncertainty and is equal to 43.3 ±0.8 J/mol/ K. This value exceeds the molar heat capacity of gaseous H2O by 9.7 J/mol/K, but is significantly smaller than the heat capacity of H2O in several zeolites and liquid H2O. A statistical-mechanical model of the heat capacity of adsorbed gas species (Barrer 1978) is used to extrapolate the heat capacity of hydrous cordierite to temperatures greater than 425 K. In this model, the heat capacity of hydrous cordierite (Crd·nH2O) is represented as follows: Cp(Crd · nH2O) = Cp(Crd)+ n{Cp(H2O, gas)+ R(gas constant)} (1) An examination of calorimetric data for hydrous beryl, analcime, mordenite, and clinoptilolite (Hemingway et al. 1986; Johnson et al. 1982, 1991, 1992) demonstrates the general applicability of the statistical-mechanical model for the extrapolation of heat capacity data of zeolitic minerals. The heat capacity data for cordierite are combined with the data of Carey and Navrotsky (1992) to obtain the molar enthalpy of formation and enthalpy of hydration of hydrous cordierite as a function of temperature.

  8. Formulation and method for preparing gels comprising hydrous aluminum oxide

    DOEpatents

    Collins, Jack L.

    2014-06-17

    Formulations useful for preparing hydrous aluminum oxide gels contain a metal salt including aluminum, an organic base, and a complexing agent. Methods for preparing gels containing hydrous aluminum oxide include heating a formulation to a temperature sufficient to induce gel formation, where the formulation contains a metal salt including aluminum, an organic base, and a complexing agent.

  9. Formulation and method for preparing gels comprising hydrous cerium oxide

    DOEpatents

    Collins, Jack L; Chi, Anthony

    2013-05-07

    Formulations useful for preparing hydrous cerium oxide gels contain a metal salt including cerium, an organic base, and a complexing agent. Methods for preparing gels containing hydrous cerium oxide include heating a formulation to a temperature sufficient to induce gel formation, where the formulation contains a metal salt including cerium, an organic base, and a complexing agent.

  10. Heat Capacity of Hydrous Silicate Melts

    NASA Astrophysics Data System (ADS)

    Robert, G.; Whittington, A. G.; Stechern, A.; Behrens, H.

    2015-12-01

    We determined the heat capacities of four series of glasses and liquids of basaltic and basaltic andesite compositions including two natural remelts from Fuego volcano, Guatemala, and two Fe-free analogs. The samples are low-alkali, Ca- and Mg-rich aluminosilicates with non-bridging oxygen to tetrahedrally-coordinated cation ratios (NBO/T) ranging between 0.33 and 0.67. Differential scanning calorimetry measurements were performed at atmospheric pressure between room temperature and ≈100 K above the glass transition for hydrous samples and up to ≈1800 K for dry samples. The water contents investigated range up to 5.34 wt.% (16.4 mol%). Water does not measurably affect the heat capacity of glasses (T hydrous samples also occurs below the Dulong-Petit limit of 3R/g atom. We see little change in liquid heat capacity with increasing water content; hydrous liquid heat capacities are within 3-6% of the dry liquid, at low temperatures just above the glass transition. However, dry liquids show a decrease in heat capacity with increasing temperature above the glass transition, from supercooled to superliquidus temperatures. Liquid heat capacity values just above the glass transition range between 95-100 J/mol K, whereas liquid heat capacity values at superliquidus temperatures are between 85-91 J/mol K. Comparison with other studies of the heat capacity of hydrous glasses and liquids shows that the liquid heat capacity of strongly depolymerized samples (NBO/T ≥ 0.8) increases with increasing water content, whereas depolymerized samples (0.4 ≤ NBO/T ≤ 0.8) or polymerized samples (NBO/T ≤ 0.4) generally show little change or a moderate decrease in liquid heat capacity with increasing water content.

  11. Water exchange in manganese-based water-oxidizing catalysts in photosynthetic systems: from the water-oxidizing complex in photosystem II to nano-sized manganese oxides.

    PubMed

    Najafpour, Mohammad Mahdi; Isaloo, Mohsen Abbasi; Eaton-Rye, Julian J; Tomo, Tatsuya; Nishihara, Hiroshi; Satoh, Kimiyuki; Carpentier, Robert; Shen, Jian-Ren; Allakhverdiev, Suleyman I

    2014-09-01

    The water-oxidizing complex (WOC), also known as the oxygen-evolving complex (OEC), of photosystem II in oxygenic photosynthetic organisms efficiently catalyzes water oxidation. It is, therefore, responsible for the presence of oxygen in the Earth's atmosphere. The WOC is a manganese-calcium (Mn₄CaO₅(H₂O)₄) cluster housed in a protein complex. In this review, we focus on water exchange chemistry of metal hydrates and discuss the mechanisms and factors affecting this chemical process. Further, water exchange rates for both the biological cofactor and synthetic manganese water splitting are discussed. The importance of fully unveiling the water exchange mechanism to understand the chemistry of water oxidation is also emphasized here. This article is part of a special issue entitled: photosynthesis research for sustainability: keys to produce clean energy. Copyright © 2014 Elsevier B.V. All rights reserved.

  12. Comparison of artificial maturation of lignite in hydrous and nonhydrous conditions

    USGS Publications Warehouse

    Behar, F.; Lewan, M.D.; Lorant, F.; Vandenbroucke, M.

    2003-01-01

    The objectives of the study are to compare product compositions and yields generated from lignite artificially matured by open nonhydrous pyrolysis, closed nonhydrous pyrolysis, and hydrous pyrolysis. The pyrolysis products were fractionated into CO2, H2O, CH4, C2-C5, C8-C14, C14+ saturates, C14+ aromatics and NSOs (resins+asphaltenes). All three methods generated high and similar quantities of water during pyrolysis that ranged between 14.6 and 15.2 wt.% of the original lignite. As a result of this high water content generated by the lignite, the experiments with no added water are referred to as nonhydrous rather than anhydrous. Rock-Eval pyrolysis and elemental analyses were conducted on the recovered lignite after solvent extraction to determine their residual hydrocarbon generation potential and to plot their position in a van Krevelen diagram, respectively. Residual lignite from the closed nonhydrous and hydrous experiments showed relationships between vitrinite reflectance (%Ro) values and atomic H/C ratios that occurred within the fields observed for natural maturation of coal. Although no significant differences in the atomic H/C ratios were observed between closed nonhydrous and hydrous pyrolysis, the vitrinite reflectance values were on the average 0.2% Ro lower in the residual lignite from the nonhydrous experiments. The remaining hydrocarbon generation potential as determined by Rock-Eval pyrolysis of the residual lignite showed that the nonhydrous residuals had on the average 16 mg more hydrocarbon potential per gram of original lignite than the hydrous residuals. This suggests there is a better release of the pyrolysis products from the lignite network in the hydrous experiments once generation occurs. For gas generation, at maximum yields, open nonhydrous pyrolysis generates the most hydrocarbon gas (21.0 mg/g original lignite), which is 20% more than closed nonhydrous pyrolysis and 29% more than hydrous pyrolysis. Closed nonhydrous pyrolysis

  13. Formulation and method for preparing gels comprising hydrous hafnium oxide

    DOEpatents

    Collins, Jack L; Hunt, Rodney D; Montgomery, Frederick C

    2013-08-06

    Formulations useful for preparing hydrous hafnium oxide gels contain a metal salt including hafnium, an acid, an organic base, and a complexing agent. Methods for preparing gels containing hydrous hafnium oxide include heating a formulation to a temperature sufficient to induce gel formation, where the formulation contains a metal salt including hafnium, an acid, an organic base, and a complexing agent.

  14. Understanding the Underground Hydrous Minerals on Mars: Stability Field, Phase Transitions, and Environmental Implications

    NASA Astrophysics Data System (ADS)

    Wang, A.; Chou, I. M.; Ling, Z.; Sobron, P.

    2017-12-01

    Three types of studies form the bases of our understandings: (1) systematic laboratory experiments on the thermodynamics and kinetic properties of hydrous (Mg, Fe2+, Fe3+, Ca, Al, Na) -sulfates, -chlorides, and -perchlorates, made by this and many other teams. (2) the thermal modeling of two-layer regolith with very different thermal inertia (TI) and its validating observation on Mars [Mellon et al., 2004, 2009]. (3) the mission observations on Mars and the field investigations at analog sites. Following are some examples of these understandings, with more to be presented at AGU. Hydrous salts (sulfates, chlorides, perchlorates) in an enclosure could keep a relatively stable RH%, i.e., they are environmental RH buffers. Underground layers of hydrous salty soils (high TI) on Mars could be considered as a quasi-closed system, equilibrated within their environments. The RH% range kept by them would help to stabilize many hydrous salts. For example, Mg- & Fe3+-sulfates with high hydration degrees (6-20 H2O) were observed in the subsurface layers in a terrestrial hyperarid region and at Gusev on Mars. A general trend was found that the RH% levels kept by hydrous sulfates in an enclosure are much higher than those by hydrous perchlorates and by hydrous chlorides. This implies that in an underground layer of mixed hydrous salts, one type of salts (e.g. sulfates) can provide the necessary RH-buffering for the phase transition of other types,, e.g., the deliquescence of perchlorates or chlorides, to trigger RSL or to provide liquid H2O at relatively warm T. The dehydration rates of hydrous sulfates have a high dependence on cation types. Among them, Mg and Fe2+-sulfate have higher dehydration rates, and ferric sulfates dehydrate much slow. This lab-observation was validated by MER mission observation, i.e., the finding of highly hydrated ferric sulfates, i.e. Fe4.67(SO4)6(OH)2.20H2O, in subsurface at Gusev crater. However, the dehydration rate of hydrous sulfates can also

  15. Mineralogical, Spectral, and Compositional Changes During Heating of Hydrous Carbonaceous Chondrites

    NASA Technical Reports Server (NTRS)

    Nakamura, T.; Matsuoka, M.; Yamashita, S.; Sato, Y.; Mogi, K.; Enokido, Y.; Nakata, A.; Okumura, S.; Furukawa, Y.; Zolensky, M.

    2017-01-01

    Hydrous carbonaceous chondrites experienced hydration and subsequent dehydration by heating, which resulted in a variety of mineralogical and spectral features [e. g., 1-6]. The degree of heating is classified according to heating stage (HS) II to IV based on mineralogy of phyllosilicates [2], because they change, with elevating temperature, to poorly crystal-line phases and subsequently to aggregates of small secondary anhydrous silicates of mainly olivine. Heating of hydrous carbonaceous chondrites also causes spectral changes and volatile loss [3-6]. Experimental heating of Murchison CM chondrite showed flattening of whole visible-near infrared spectra, especially weakening of the 3µm band strength [1, 4, 7]. In order to understand mineralogical, spectral, and compositional changes during heating of hydrous carbonaceous chondrites, we have carried out systematic investigation of mineralogy, reflectance spectra, and volatile composition of hydrated and dehydrated carbonaceous chondrites as well as experimentally-heated hydrous carbonaceous chondrites. In addition, we investigated reflectance spectra of tochilinite that is a major phase of CM chondrites and has a low dehydration temperature (250degC).

  16. Intermediate-depth earthquake generation: what hydrous minerals can tell us

    NASA Astrophysics Data System (ADS)

    Deseta, N.; Ashwal, L.; Andersen, T. B.

    2012-04-01

    Subduction zone seismicity has commonly been causally related to the dehydration of minerals within the subducting slab(Hacker et al. 2004, Jung et al. (2004), Dobson et al. 2002, Rondenay et al. 2008). Other models for release of intermediate- and deep earthquakes include spontaneous reaction(s) affecting large rock-bodies along overstepped phase boundaries ( e.g. Green and Houston, 1995) and various shear heating-localization models (e.g. Kelemen and Hirth 2007, John et al. 2009). These concepts are principally reliant on seismic and thermo-petrological modeling; both of which are indirect methods of analysis. Recent discoveries of pseudotachylytes (PST) formed under high pressure conditions (Ivrea-Verbano Zone, Italy, Western Gneiss Region, Norway and Corsica) provide the first tangible opportunity to evaluate these models (Austrheim and Andersen, 2004, Lund and Austrheim, 2003, Obata and Karato, 1995, Jin et al., 1998). This case study focuses on observations based on ultramafic and mafic PST within the Ligurian Ophiolite of the high pressure-low temperature metamorphic (HP-LT) 'Shistes Lustres' complex in Cima di Gratera, Corsica (Andersen et al. 2008). These PST have been preserved in pristine lenses of peridotite and gabbro surrounded by schistose serpentinites. The PST range in thickness from 1mm to 25 cm (Andersen and Austrheim, 2006). Petrography and geochemistry on PST from the peridotite and gabbro samples indicates that total/near-total fusion of the local host rock mineral assemblage occurred; bringing up the temperature of shear zone from 350° C to 1400 - 1700° C; depending on the host rock (Andersen and Austrheim, 2006). The composition of the PST is highly variable, even at the thin section scale and this has been attributed to the coarse-grained nature of the host rock, its small scale inhomogeneity and poor mixing of the fusion melt. Almost all the bulk analyses of the PST are hydrous; the peridotitic PST is always hydrous (H2O content from 3

  17. Failure warning of hydrous sandstone based on electroencephalogram technique

    NASA Astrophysics Data System (ADS)

    Tao, Kai; Zheng, Wei

    2018-06-01

    Sandstone is a type of rock mass that widely exists in nature. Moisture is an important factor that leads to sandstone structural failure. The major failure assessment methods of hydrous sandstone at present cannot satisfy real-time and portability requirements, especially lacks of warning function. In this study, acoustic emission (AE) and computed tomography (CT) techniques are combined for real-time failure assessment of hydrous sandstone. Eight visual colors for warning are screened according to different failure states, and an electroencephalogram (EEG) experiment is conducted to demonstrate their diverse excitations of the human brain's concentration.

  18. Synthesis of nanosized sodium titanates

    DOEpatents

    Hobbs, David T.; Taylor-Pashow, Kathryn M. L.; Elvington, Mark C.

    2015-09-29

    Methods directed to the synthesis and peroxide-modification of nanosized monosodium titanate are described. Methods include combination of reactants at a low concentration to a solution including a nonionic surfactant. The nanosized monosodium titanate can exhibit high selectivity for sorbing various metallic ions.

  19. Biological water-oxidizing complex: a nano-sized manganese-calcium oxide in a protein environment.

    PubMed

    Najafpour, Mohammad Mahdi; Moghaddam, Atefeh Nemati; Yang, Young Nam; Aro, Eva-Mari; Carpentier, Robert; Eaton-Rye, Julian J; Lee, Choon-Hwan; Allakhverdiev, Suleyman I

    2012-10-01

    The resolution of Photosystem II (PS II) crystals has been improved using isolated PS II from the thermophilic cyanobacterium Thermosynechococcus vulcanus. The new 1.9 Å resolution data have provided detailed information on the structure of the water-oxidizing complex (Umena et al. Nature 473: 55-61, 2011). The atomic level structure of the manganese-calcium cluster is important for understanding the mechanism of water oxidation and to design an efficient catalyst for water oxidation in artificial photosynthetic systems. Here, we have briefly reviewed our knowledge of the structure and function of the cluster.

  20. Manganese

    USGS Publications Warehouse

    Cannon, William F.; Kimball, Bryn E.; Corathers, Lisa A.; Schulz, Klaus J.; DeYoung,, John H.; Seal, Robert R.; Bradley, Dwight C.

    2017-12-19

    Manganese is an essential element for modern industrial societies. Its principal use is in steelmaking, where it serves as a purifying agent in iron-ore refining and as an alloy that converts iron into steel. Although the amount of manganese consumed to make a ton of steel is small, ranging from 6 to 9 kilograms, it is an irreplaceable component in the production of this fundamental material. The United States has been totally reliant on imports of manganese for many decades and will continue to be so for at least the near future. There are no domestic reserves, and although some large low-grade resources are known, they are far inferior to manganese ores readily available on the international market. World reserves of manganese are about 630 million metric tons, and annual global consumption is about 16 million metric tons. Current reserves are adequate to meet global demand for several decades. Global resources in traditional land-based deposits, including both reserves and rocks sufficiently enriched in manganese to be ores in the future, are much larger, at about 17 billion metric tons. Manganese resources in seabed deposits of ferromanganese nodules and crusts are larger than those on land and have not been fully quantified. No production from seabed deposits has yet been done, but current research and development activities are substantial and may bring parts of these seabed resources into production in the future. The advent of economically successful seabed mining could substantially alter the current scenario of manganese supply by providing a large new source of manganese in addition to traditional land-based deposits.From a purely geologic perspective, there is no global shortage of proven ores and potential new ores that could be developed from the vast tonnage of identified resources. Reserves and resources are very unevenly distributed, however. The Kalahari manganese district in South Africa contains 70 percent of the world’s identified resources

  1. Hydrous oxide ion-exchange compound catalysts

    DOEpatents

    Dosch, Robert G.; Stephens, Howard P.

    1990-01-01

    A catalytic material of improved activity which comprises a hydrous, alkali metal or alkaline earth metal or quaternary ammonium titanate, zirconate, niobate, or tantalate, in which the metal or ammonium cations have been exchange with a catalytically effective quantity of a catalyst metal, and which has been subsequently treated with a solution of a Bronsted acid.

  2. The density, compressibility and seismic velocity of hydrous melts at crustal and upper mantle conditions

    NASA Astrophysics Data System (ADS)

    Ueki, K.; Iwamori, H.

    2015-12-01

    Various processes of subduction zone magmatism, such as upward migration of partial melts and fractional crystallization depend on the density of the hydrous silicate melt. The density and the compressibility of the hydrous melt are key factors for the thermodynamic calculation of phase relation of the hydrous melt, and the geophysical inversion to predict physicochemical conditions of the melting region based on the seismic velocity. This study presents a new model for the calculations of the density of the hydrous silicate melts as a function of T, P, H2O content and melt composition. The Birch-Murnaghan equation is used for the equation of state. We compile the experimentally determined densities of various hydrous melts, and optimize the partial molar volume, compressibility, thermal expansibility and its pressure derivative, and K' of the H2O component in the silicate melt. P-T ranges of the calibration database are 0.48-4.29 GPa and 1033-2073 K. As such, this model covers the P-T ranges of the entire melting region of the subduction zone. Parameter set provided by Lange and Carmichael [1990] is used for the partial molar volume and KT value of the anhydrous silicate melt. K' of anhydrous melt is newly parameterized as a function of SiO2 content. The new model accurately reproduces the experimentally determined density variations of various hydrous melts from basalt to rhyolite. Our result shows that the hydrous melt is more compressive and less dense than the anhydrous melt; with the 5 wt% of H2O in melt, density and KT decrease by ~10% and ~30% from those of the anhydrous melt, respectively. For the application of the model, we calculated the P-wave velocity of the hydrous melt. With the 5 wt% of H2O, P-wave velocity of the silicate melt decreases by >10%. Based on the melt P-wave velocity, we demonstrate the effect of the melt H2O content on the seismic velocity of the partially molten zone of the subduction zone.

  3. The Role of Hydrogen Bonds Of The Azeotropic Hydrous Ethanol Fuel Composition To The Exhaust Emissions

    NASA Astrophysics Data System (ADS)

    Made Suarta, I.; Nyoman Gede Baliarta, I.; Sopan Rahtika, I. P. G.; Wijaya Sunu, Putu

    2018-01-01

    In this study observed the role of hydrogen bonding to the composition of exhaust emissions which is produced hydrous ethanol fuel (95.5% v). Testing is done by using single cylinder four stroke motor engine. The composition of exhaust gas emissions is tested using exhaust gas analyzer on lean and stoichiometry mixer. The exhaust emissions produced by anhydrous ethanol were also tested. The composition of emissions produced by that two fuels is compared. The results showed CO emissions levels produced by hydrous ethanol are slightly higher than anhydrous ethanol in stoichiometric mixtures. But the composition of CO hydrous ethanol emissions is lower in the lean mix. If lean the mixer the different in the composition of emissions is increasing. On hydrous ethanol emission CO2 content little bit lower on the stoichiometric mixer and higher on the lean mixture. Exhaust emissions of ethanol fuel also produce O2. O2 hydrous ethanol emissions is higher than anhydrous ethanol fuel.

  4. Structure and stability of hydrous minerals at high pressure

    NASA Technical Reports Server (NTRS)

    Duffy, T. S.; Fei, Y.; Meade, C.; Hemley, R. J.; Mao, H. K.

    1994-01-01

    The presence of even small amounts of hydrogen in the Earth's deep interior may have profound effects on mantle melting, rheology, and electrical conductivity. The recent discovery of a large class of high-pressure H-bearing silicates further underscores the potentially important role for hydrous minerals in the Earth's mantle. Hydrogen may also be a significant component of the Earth's core, as has been recently documented by studies of iron hydride at high pressure. In this study, we explore the role of H in crystal structures at high pressure through detailed Raman spectroscopic and x ray diffraction studies of hydrous minerals compressed in diamond anvil cells. Brucite, Mg(OH)2, has a simple structure and serves as an analogue for the more complex hydrous silicates. Over the past five years, this material has been studied at high pressure using shock-compression, powder x ray diffraction, infrared spectroscopy, Raman spectroscopy, and neutron diffraction. In addition, we have recently carried out single-crystal synchrotron x-ray diffraction on Mg(OH)2 and Raman spectroscopy on Mg(OD)2 at elevated pressure. From all these studies, an interesting picture of the crystal chemical behavior of this material at high pressure is beginning to emerge. Some of the primary conclusions are as follows: First, hydrogen bonding is enhanced by the application of pressure. Second, layered minerals which are elastically anisotropic at low pressure may not be so at high pressure. Furthermore, the brucite data place constraints on the effect of hydrogen on seismic velocities and density at very high pressure. Third, the stability of hydrous minerals may be enhanced at high P by subtle structural rearrangements that are difficult to detect using traditional probes and require detailed spectroscopic analyses. Finally, brucite appears to be unique in that it undergoes pressure-induced disordering that is confined solely to the H-containing layers of the structure.

  5. Comparison of petroleum generation kinetics by isothermal hydrous and nonisothermal open-system pyrolysis

    USGS Publications Warehouse

    Lewan, M.D.; Ruble, T.E.

    2002-01-01

    This study compares kinetic parameters determined by open-system pyrolysis and hydrous pyrolysis using aliquots of source rocks containing different kerogen types. Kinetic parameters derived from these two pyrolysis methods not only differ in the conditions employed and products generated, but also in the derivation of the kinetic parameters (i.e., isothermal linear regression and non-isothermal nonlinear regression). Results of this comparative study show that there is no correlation between kinetic parameters derived from hydrous pyrolysis and open-system pyrolysis. Hydrous-pyrolysis kinetic parameters determine narrow oil windows that occur over a wide range of temperatures and depths depending in part on the organic-sulfur content of the original kerogen. Conversely, open-system kinetic parameters determine broad oil windows that show no significant differences with kerogen types or their organic-sulfur contents. Comparisons of the kinetic parameters in a hypothetical thermal-burial history (2.5 ??C/my) show open-system kinetic parameters significantly underestimate the extent and timing of oil generation for Type-US kerogen and significantly overestimate the extent and timing of petroleum formation for Type-I kerogen compared to hydrous pyrolysis kinetic parameters. These hypothetical differences determined by the kinetic parameters are supported by natural thermal-burial histories for the Naokelekan source rock (Type-IIS kerogen) in the Zagros basin of Iraq and for the Green River Formation (Type-I kerogen) in the Uinta basin of Utah. Differences in extent and timing of oil generation determined by open-system pyrolysis and hydrous pyrolysis can be attributed to the former not adequately simulating natural oil generation conditions, products, and mechanisms.

  6. Vibrational Sum Frequency Generation Spectroscopy Study of Hydrous Species in Soda Lime Silica Float Glass.

    PubMed

    Luo, Jiawei; Banerjee, Joy; Pantano, Carlo G; Kim, Seong H

    2016-06-21

    It is generally accepted that the mechanical properties of soda lime silica (SLS) glass can be affected by the interaction between sodium ions and hydrous species (silanol groups and water molecules) in its surface region. While the amount of these hydrous species can be estimated from hydrogen profiles and infrared spectroscopy, their chemical environment in the glass network is still not well understood. This work employed vibrational sum frequency generation (SFG) spectroscopy to investigate the chemical environment of hydrous species in the surface region of SLS float glass. SLS float glass shows sharp peaks in the OH stretching vibration region in SFG spectra, while the OH stretch peaks of glasses that do not have leachable sodium ions and the OH peaks of water molecules in condensed phases are normally broad due to fast hydrogen bonding dynamics. The hydrous species responsible for the sharp SFG peaks for the SLS float glass were found to be thermodynamically more stable than physisorbed water molecules, did not exchange with D2O, and were associated with the sodium concentration gradient in the dealkalized subsurface region. These results suggested that the hydrous species reside in static solvation shells defined by the silicate network with relatively slow hydrogen bonding dynamics, compared to physisorbed water layers on top of the glass surface. A putative radial distribution of the hydrous species within the SLS glass network was estimated based on the OH SFG spectral features, which could be compared with theoretical distributions calculated from computational simulations.

  7. Discovery of a hexagonal ultradense hydrous phase in (Fe,Al)OOH

    NASA Astrophysics Data System (ADS)

    Zhang, Li; Yuan, Hongsheng; Meng, Yue; Mao, Ho-kwang

    2018-03-01

    A deep lower-mantle (DLM) water reservoir depends on availability of hydrous minerals which can store and transport water into the DLM without dehydration. Recent discoveries found hydrous phases AlOOH (Z = 2) with a CaCl2-type structure and FeOOH (Z = 4) with a cubic pyrite-type structure stable under the high-pressure–temperature (P-T) conditions of the DLM. Our experiments at 107–136 GPa and 2,400 K have further demonstrated that (Fe,Al)OOH is stabilized in a hexagonal lattice. By combining powder X-ray-diffraction techniques with multigrain indexation, we are able to determine this hexagonal hydrous phase with a = 10.5803(6) Å and c = 2.5897(3) Å at 110 GPa. Hexagonal (Fe,Al)OOH can transform to the cubic pyrite structure at low T with the same density. The hexagonal phase can be formed when δ-AlOOH incorporates FeOOH produced by reaction between water and Fe, which may store a substantial quantity of water in the DLM.

  8. Improved hydrous oxide ion-exchange compound catalysts

    DOEpatents

    Dosch, R.G.; Stephens, H.P.

    1986-04-09

    Disclosed is a catalytic material of improved activity which comprises a hydrous, alkali metal or alkaline earth metal or quaternary ammonium titanate, zirconate, niobate, or tantalate, in which the metal or ammonium cations have been exchanged with a catalytically effective quantity of a catalyst metal, and which has been subsequently treated with a solution of a Bronsted acid.

  9. Retrieving the hydrous minerals on Mars by sparse unmixing and the Hapke model using MRO/CRISM data

    NASA Astrophysics Data System (ADS)

    Lin, Honglei; Zhang, Xia

    2017-05-01

    The hydrous minerals on Mars preserve records of potential past aqueous activity. Quantitative information regarding mineralogical composition would enable a better understanding of the formation processes of these hydrous minerals, and provide unique insights into ancient habitable environments and the geological evolution of Mars. The Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) has the advantage of both a high spatial and spectral resolution, which makes it suitable for the quantitative analysis of minerals on Mars. However, few studies have attempted to quantitatively retrieve the mineralogical composition of hydrous minerals on Mars using visible-infrared (VISIR) hyperspectral data due to their distribution characteristics (relatively low concentrations, located primarily in Noachian terrain, and unclear or unknown background minerals) and limitations of the spectral unmixing algorithms. In this study, we developed a modified sparse unmixing (MSU) method, combining the Hapke model with sparse unmixing. The MSU method considers the nonlinear mixed effects of minerals and avoids the difficulty of determining the spectra and number of endmembers from the image. The proposed method was tested successfully using laboratory mixture spectra and an Airborne Visible Infrared Imaging Spectrometer (AVIRIS) image of the Cuprite site (Nevada, USA). Then it was applied to CRISM hyperspectral images over Gale crater. Areas of hydrous mineral distribution were first identified by spectral features of water and hydroxyl absorption. The MSU method was performed on these areas, and the abundances were retrieved. The results indicated that the hydrous minerals consisted mostly of hydrous silicates, with abundances of up to 35%, as well as hydrous sulfates, with abundances ≤10%. Several main subclasses of hydrous minerals (e.g., Fe/Mg phyllosilicate, prehnite, and kieserite) were retrieved. Among these, Fe/Mg- phyllosilicate was the most abundant, with abundances

  10. Catalysis using hydrous metal oxide ion exchanges

    DOEpatents

    Dosch, Robert G.; Stephens, Howard P.; Stohl, Frances V.

    1985-01-01

    In a process which is catalyzed by a catalyst comprising an active metal on a carrier, said metal being active as a catalyst for the process, an improvement is provided wherein the catalyst is a hydrous, alkali metal or alkaline earth metal titanate, zirconate, niobate or tantalate wherein alkali or alkaline earth metal cations have been exchanged with a catalytically effective amount of cations of said metal.

  11. Catalysis using hydrous metal oxide ion exchangers

    DOEpatents

    Dosch, R.G.; Stephens, H.P.; Stohl, F.V.

    1983-07-21

    In a process which is catalyzed by a catalyst comprising an active metal on a carrier, said metal being active as a catalyst for the process, an improvement is provided wherein the catalyst is a hydrous, alkali metal or alkaline earth metal titanate, zirconate, niobate or tantalate wherein alkali or alkaline earth metal cations have been exchanged with a catalytically effective amount of cations of said metal.

  12. Recovery of manganese from manganese oxide ores in the EDTA solution

    NASA Astrophysics Data System (ADS)

    Zhang, Chao; Wang, Shuai; Cao, Zhan-fang; Zhong, Hong

    2018-04-01

    A new process has been experimentally and theoretically established for the recovery of manganese from manganese oxide ores, mainly including the reductive leaching of manganese by ethylenediaminetetraacetic acid (EDTA), EDTA recovery, and manganese electrolysis. The experimental conditions for this process were investigated. Moderate leaching environment by EDTA with the pH in the range of 5-6 is of benefit to leach manganese from some manganese oxide ores with high-content impurities, such as iron and aluminum. Most of EDTA can be recovered by acidification. A small amount of the residual EDTA in the electrolyte can prevent the generation of anode mud. In addition, trimanganese tetroxide (Mn3O4) can be obtained by the roasting of the EDTA-Mn crystallized product.

  13. Electrokinetic remediation of manganese and ammonia nitrogen from electrolytic manganese residue.

    PubMed

    Shu, Jiancheng; Liu, Renlong; Liu, Zuohua; Du, Jun; Tao, Changyuan

    2015-10-01

    Electrolytic manganese residue (EMR) is a solid waste found in filters after sulphuric acid leaching of manganese carbonate ore, which mainly contains manganese and ammonia nitrogen and seriously damages the ecological environment. This work demonstrated the use of electrokinetic (EK) remediation to remove ammonia nitrogen and manganese from EMR. The transport behavior of manganese and ammonia nitrogen from EMR during electrokinetics, Mn fractionation before and after EK treatment, the relationship between Mn fractionation and transport behavior, as well as the effects of electrolyte and pretreatment solutions on removal efficiency and energy consumption were investigated. The results indicated that the use of H2SO4 and Na2SO4 as electrolytes and pretreatment of EMR with citric acid and KCl can reduce energy consumption, and the removal efficiencies of manganese and ammonia nitrogen were 27.5 and 94.1 %, respectively. In these systems, electromigration and electroosmosis were the main mechanisms of manganese and ammonia nitrogen transport. Moreover, ammonia nitrogen in EMR reached the regulated level, and the concentration of manganese in EMR could be reduced from 455 to 37 mg/L. In general, the electrokinetic remediation of EMR is a promising technology in the future.

  14. Visible-near infrared spectra of hydrous carbonates, with implications for the detection of carbonates in hyperspectral data of Mars

    NASA Astrophysics Data System (ADS)

    Harner, Patrick L.; Gilmore, Martha S.

    2015-04-01

    We present visible-near infrared (VNIR, 0.35-5 μm) spectra for a suite of hydrous carbonates that may be relevant to the surface of Mars. This includes VNIR spectra for ikaite, nesquehonite, synthetic monohydrocalcite and lansfordite over the 0.35-2.5 μm range that are new to the literature. The spectral features of the hydrous carbonates are dominated by absorptions at ∼1.0, 1.2, 1.4-1.5, 1.9 and 2.8 μm that are due to overtones and combinations of fundamental water and hydroxyl vibrations. Absorptions due to (CO3)2-, Mg-OH, Fe-OH, and/or water are seen at ∼2.3-2.5, 3.4, and 3.9 μm in hydrous Mg and Mg-Fe3+ carbonates containing hydroxyl groups, but are weaker than in the common anhydrous carbonates. When present in the hydrous carbonates, the positions of the centers of the 2.3 μm and/or 2.5 μm absorptions are often shifted relative to the anhydrous carbonates, which may be diagnostic. Some or all of the (CO3)2- absorptions typical of anhydrous carbonates are weak to absent in the hydrous carbonates, and thus this group may be difficult to distinguish from other hydrous minerals like sulfates, phyllosilicates or chlorides in Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) data using standard spectral search parameters for anhydrous carbonates. We present strategies for recognizing hydrous carbonates in CRISM data using combinations of spectral parameters that measure the intensity and shape of the water-related absorptions in these minerals.

  15. Influence of dissolved organic matter and manganese oxides on metal speciation in soil solution: A modelling approach.

    PubMed

    Schneider, Arnaud R; Ponthieu, Marie; Cancès, Benjamin; Conreux, Alexandra; Morvan, Xavier; Gommeaux, Maxime; Marin, Béatrice; Benedetti, Marc F

    2016-06-01

    Trace element (TE) speciation modelling in soil solution is controlled by the assumptions made about the soil solution composition. To evaluate this influence, different assumptions using Visual MINTEQ were tested and compared to measurements of free TE concentrations. The soil column Donnan membrane technique (SC-DMT) was used to estimate the free TE (Cd, Cu, Ni, Pb and Zn) concentrations in six acidic soil solutions. A batch technique using DAX-8 resin was used to fractionate the dissolved organic matter (DOM) into four fractions: humic acids (HA), fulvic acids (FA), hydrophilic acids (Hy) and hydrophobic neutral organic matter (HON). To model TE speciation, particular attention was focused on the hydrous manganese oxides (HMO) and the Hy fraction, ligands not considered in most of the TE speciation modelling studies in soil solution. In this work, the model predictions of free ion activities agree with the experimental results. The knowledge of the FA fraction seems to be very useful, especially in the case of high DOM content, for more accurately representing experimental data. Finally, the role of the manganese oxides and of the Hy fraction on TE speciation was identified and, depending on the physicochemical conditions of the soil solution, should be considered in future studies. Copyright © 2016 Elsevier Ltd. All rights reserved.

  16. Manganese Health Research Program (MHRP)

    DTIC Science & Technology

    2008-01-01

    NO3)2 Manganese sulphate or Manganese (II) sulphate – MnSO4 Manganese sulphide or Manganese (II) sulphide – MnS Manganese oxide – MnO Barium... sulphide or Manganese (II) sulphide – MnS 1344-43-0 Manganese oxide – MnO 7787-35-1 Barium manganate - BaMnO4 10294-64-1 Potassium manganate – K2MnO4...Characterization of welding fumes and their potential neurotoxic effects. International Workshop: Neurotoxic Metals- Lead, Mercury , and Manganese

  17. Elemental selenium particles at nano-size (Nano-Se) are more toxic to Medaka (Oryzias latipes) as a consequence of hyper-accumulation of selenium: a comparison with sodium selenite.

    PubMed

    Li, Hongcheng; Zhang, Jinsong; Wang, Thanh; Luo, Wenru; Zhou, Qunfang; Jiang, Guibin

    2008-09-29

    Recent studies have shown that elemental selenium particles at nano-size (Nano-Se) exhibited comparable bioavailability and less toxicity in mice and rats when compared to sodium selenite, selenomethinine and methylselenocysteine. However, little is known about the toxicity profile of Nano-Se in aquatic animals. In the present study, toxicities of Nano-Se and selenite in selenium-sufficient Medaka fish were compared. Selenium bioaccumulation and subsequent clearance in fish livers, gills, muscles and whole bodies were examined after 10 days of exposure to Nano-Se and selenite (100 microg Se/L) and again after 7 days of depuration. Both forms of selenium exposure effectively increased selenium concentrations in the investigated tissues. Surprisingly, Nano-Se was found to be more hyper-accumulated in the liver compared to selenite with differences as high as sixfold. Selenium clearance of both Nano-Se and selenite occurred at similar ratios in whole bodies and muscles but was not rapidly cleared from livers and gills. Nano-Se exhibited strong toxicity for Medaka with an approximately fivefold difference in terms of LC(50) compared to selenite. Nano-Se also caused larger effects on oxidative stress, most likely due to more hyper-accumulation of selenium in liver. The present study suggests that toxicity of nanoparticles can largely vary between different species and concludes that the evaluation of nanotoxicology should be carried out on a case-by-case basis.

  18. Thermochemistry of dense hydrous magnesium silicates

    NASA Technical Reports Server (NTRS)

    Bose, Kunal; Burnley, Pamela; Navrotsky, Alexandra

    1994-01-01

    Recent experimental investigations under mantle conditions have identified a suite of dense hydrous magnesium silicate (DHMS) phases that could be conduits to transport water to at least the 660 km discontinuity via mature, relatively cold, subducting slabs. Water released from successive dehydration of these phases during subduction could be responsible for deep focus earthquakes, mantle metasomatism and a host of other physico-chemical processes central to our understanding of the earth's deep interior. In order to construct a thermodynamic data base that can delineate and predict the stability ranges for DHMS phases, reliable thermochemical and thermophysical data are required. One of the major obstacles in calorimetric studies of phases synthesized under high pressure conditions has been limitation due to the small (less than 5 mg) sample mass. Our refinement of calorimeter techniques now allow precise determination of enthalpies of solution of less than 5 mg samples of hydrous magnesium silicates. For example, high temperature solution calorimetry of natural talc (Mg(0.99) Fe(0.01)Si4O10(OH)2), periclase (MgO) and quartz (SiO2) yield enthalpies of drop solution at 1044 K to be 592.2 (2.2), 52.01 (0.12) and 45.76 (0.4) kJ/mol respectively. The corresponding enthalpy of formation from oxides at 298 K for talc is minus 5908.2 kJ/mol agreeing within 0.1 percent to literature values.

  19. Fundamental Mvssbauer Parameters of Hydrous Iron Sulfates

    NASA Technical Reports Server (NTRS)

    Rothstein, Y.; Dyar, M. D.; Schaefer, M. W.; Lane, M. D.; Bishop, J. L.

    2005-01-01

    Hydrous iron sulfates, which form as alteration products of sulfides, are rare on Earth. On Mars, the low temperature and pH found in the martian permafrost create ideal conditions for the formation of this group of minerals [1], which includes such phases as coquimbite (Fe2(SO4) 9H2O) and amarantite (FeSO4(OH) 3H2O). Viking, Mars Pathfinder, MER and OMEGA data [e.g., [2

  20. Magneto-structural studies of sol-gel synthesized nanocrystalline manganese substituted nickel ferrites

    NASA Astrophysics Data System (ADS)

    Pandav, R. S.; Patil, R. P.; Chavan, S. S.; Mulla, I. S.; Hankare, P. P.

    2016-11-01

    Nanocrystalline NiFe2-xMnxO4 (2≥x≥0) ferrites were prepared by sol-gel method. X-ray diffraction patterns reveal that synthesized compounds are in single phase cubic spinel lattice for all the composition. The surface morphology of all the samples were studied by scanning electron microscopy. The particle size measured from transmission electron microscopy and X-ray diffraction patterns confirms the nanosized dimension of the as-prepared powder. The elemental analysis was carried out by energy dispersive X-ray analysis technique. Magnetic properties such as saturation magnetization, coercivity and remanence are studied as a function of increasing Mn concentration at room temperature. The saturation magnetization shows a decreasing trend with increase in Mn content. The substitution of manganese in the nickel ferrite affects the structural and magnetic properties of cubic spinels.

  1. Leaching of manganese from electrolytic manganese residue by electro-reduction.

    PubMed

    Shu, Jiancheng; Liu, Renlong; Liu, Zuohua; Chen, Hongliang; Tao, Changyuan

    2017-08-01

    In this study, an improved process for leaching manganese from electrolytic manganese residue (EMR) by electro-reduction was developed. The mechanisms of the electro-reduction leaching were investigated through X-ray diffraction, scanning electron microscopy, X-ray fluorescence, and Brunauer Emmett Teller. The results show that the electric field could change the surface charge distribution of EMR particles, and the high-valent manganese can be reduced by electric field. The leaching efficient of manganese reached 84.1% under the optimal leaching condition: 9.2 wt% H 2 SO 4 , current density of 25 mA/cm 2 , solid-to-liquid ratio of 1:5, and leaching time for 1 h. It is 37.9% higher than that attained without an electric field. Meanwhile, the manganese content in EMR decreased from 2.57% to 0.48%.

  2. Extraction of manganese from electrolytic manganese residue by bioleaching.

    PubMed

    Xin, Baoping; Chen, Bing; Duan, Ning; Zhou, Changbo

    2011-01-01

    Extraction of manganese from electrolytic manganese residues using bioleaching was investigated in this paper. The maximum extraction efficiency of Mn was 93% by sulfur-oxidizing bacteria at 4.0 g/l sulfur after bioleaching of 9days, while the maximum extraction efficiency of Mn was 81% by pyrite-leaching bacteria at 4.0 g/l pyrite. The series bioleaching first by sulfur-oxidizing bacteria and followed by pyrite-leaching bacteria evidently promoted the extraction of manganese, witnessing the maximum extraction efficiency of 98.1%. In the case of sulfur-oxidizing bacteria, the strong dissolution of bio-generated sulfuric acid resulted in extraction of soluble Mn2+, while both the Fe2+ catalyzed reduction of Mn4+ and weak acidic dissolution of Mn2+ accounted for the extraction of manganese with pyrite-leaching bacteria. The chemical simulation of bioleaching process further confirmed that the acid dissolution of Mn2+ and Fe2+ catalyzed reduction of Mn4+ were the bioleaching mechanisms involved for Mn extraction from electrolytic manganese residues. Copyright © 2010 Elsevier Ltd. All rights reserved.

  3. Effects of nanosized constriction on thermal transport properties of graphene

    PubMed Central

    2014-01-01

    Thermal transport properties of graphene with nanosized constrictions are investigated using nonequilibrium molecular dynamics simulations. The results show that the nanosized constrictions have a significant influence on the thermal transport properties of graphene. The thermal resistance of the nanosized constrictions is on the order of 107 to 109 K/W at 150 K, which reduces the thermal conductivity by 7.7% to 90.4%. It is also found that the constriction resistance is inversely proportional to the width of the constriction and independent of the heat current. Moreover, we developed an analytical model for the ballistic thermal resistance of the nanosized constrictions in two-dimensional nanosystems. The theoretical prediction agrees well with the simulation results in this paper, which suggests that the thermal transport across the nanosized constrictions in two-dimensional nanosystems is ballistic in nature. PACS 65.80.CK; 61.48.Gh; 63.20.kp; 31.15.xv PMID:25232292

  4. The impact of dissolved fluorine on bubble nucleation in hydrous rhyolite melts

    NASA Astrophysics Data System (ADS)

    Gardner, James E.; Hajimirza, Sahand; Webster, James D.; Gonnermann, Helge M.

    2018-04-01

    Surface tension of hydrous rhyolitic melt is high enough that large degrees of supersaturation are needed to homogeneously nucleate H2O bubbles during eruptive magma ascent. This study examines whether dissolved fluorine lowers surface tension of hydrous rhyolite, and thus lowers the supersaturation required for bubble nucleation. Fluorine was targeted because it, like H2O, changes melt properties and is highly soluble, unlike all other common magmatic volatiles. Rhyolite melts were saturated at Ps = 245 MPa with H2O fluid that contained F, generating rhyolite with 6.7 ± 0.4 wt.% H2O and 1.1-1.3 wt.% F. When these melts were decompressed rapidly to Pf = 149-202 MPa and quenched after 60 s, bubbles nucleated at supersaturations of ΔP = Ps - Pf ≥52 MPa, and reached bubble number densities of NB = 1012-13 m-3 at ΔP = 78-101 MPa. In comparison, rhyolite saturated with 6.34 ± 0.09 wt.% H2O, but only 0.25 wt.% F, did not nucleate bubbles until ΔP ≥ 100-116 MPa, and even then, at significantly lower NB (<1010 m-3). Numerical modeling of bubble nucleation and growth was used to estimate the values of surface tension required to generate the observed values of NB. Slight differences in melt compositions (i.e., alkalinity and H2O content), H2O diffusivity, or melt viscosity cannot explain the observed differences in NB. Instead, surface tension of F-rich rhyolite must be lower by approximately 4% than that of F-poor rhyolite. This difference in surface tension is significant and, for example, exceeds that found between hydrous basaltic andesite and hydrous rhyolite. These results suggest that is likely that surface tension for F-rich magmas, such as topaz rhyolite, is significantly lower than for F-poor magmas.

  5. Integrated Spectroscopic Studies of Hydrous Sulfate Minerals

    NASA Technical Reports Server (NTRS)

    Dyar, M. D.; Lane, M. D.; Bishop, J. L.; OConnor, V.; Cloutis, E.; Hiroi, T.

    2005-01-01

    Sulfate minerals have been identified in Martian meteorites and on Mars using a suite of instruments aboard the MER rovers. These results have confirmed previous groundbased observations and orbital measurements that suggested their presence. The orbiting OMEGA instrument on Mars Express is also finding evidence for sulfate. In order to better interpret remote-sensing data, we present here the results of a coordinated visible/near infrared (VNIR) reflectance, Moussbauer (MB), and thermal emittance study of wellcharacterized hydrous sulfate minerals.

  6. Manganese, Metallogenium, and Martian Microfossils

    NASA Technical Reports Server (NTRS)

    Stein, L. Y.; Nealson, K. H.

    1999-01-01

    Manganese could easily be considered an abundant element in the Martian regolith, assuming that the composition of martian meteorites reflects the composition of the planet. Mineralogical analyses of 5 SNC meteorites have revealed an average manganese oxide concentration of 0.48%, relative to the 0.1% concentration of manganese found in the Earth's crust. On the Earth, the accumulation of manganese oxides in oceans, soils, rocks, sedimentary ores, fresh water systems, and hydrothermal vents can be largely attributed to microbial activity. Manganese is also a required trace nutrient for most life forms and participates in many critical enzymatic reactions such as photosynthesis. The wide-spread process of bacterial manganese cycling on Earth suggests that manganese is an important element to both geology and biology. Furthermore, there is evidence that bacteria can be fossilized within manganese ores, implying that manganese beds may be good repositories for preserved biomarkers. A particular genus of bacteria, known historically as Metallogenium, can form star-shaped manganese oxide minerals (called metallogenium) through the action of manganese oxide precipitation along its surface. Fossilized structures that resemble metallogenium have been found in Precambrian sedimentary formations and in Cretaceous-Paleogene cherts. The Cretaceous-Paleogene formations are highly enriched in manganese and have concentrations of trace elements (Fe, Zn, Cu, and Co) similar to modern-day manganese oxide deposits in marine environments. The appearance of metallogenium-like fossils associated with manganese deposits suggests that bacteria may be preserved within the minerals that they form. Additional information is contained in the original extended abstract.

  7. Sorption of Eu(III) on humic acid or fulvic acid bound to hydrous alumina studied by SEM-EDS, XPS, TRLFS, and batch techniques.

    PubMed

    Tan, X L; Wang, X K; Geckeis, H; Rabung, Th

    2008-09-01

    To identify the effect of humic acid (HA) and fulvic acid (FA) on the sorption mechanism of Eu(III) on organic--inorganic colloids in the environment at a molecular level, surface adsorbed/ complexed Eu(III) on hydrous alumina, HA-, and FA-hydrous alumina hybrids were characterized by using X-ray photoelectron spectroscopy (XPS) and time-resolved laser fluorescence spectroscopy (TRLFS). The experiments were performed in 0.1 mol/L KNO3 or 0.1 mol/L NaClO4 under ambient conditions. The pH values were varied between 2 and 11 at a fixed Eu(III) concentration of 6.0 x 10(-7) mol/L and 4.3 x 10(-5) mol/L. The different Eu(III)/FA(HA)/hydrous alumina complexes were characterized by their fluorescence emission spectra ((5D0-F1)/ (5D0 --> 7F2)) and binding energy of Eu(III). Inner-sphere surface complexation may contribute mainly to Eu(III) sorption on hydrous alumina, and a ternary surface complex is formed at the HA/ FA-hydrous alumina hybrid surfaces. The sorption and species of Eu(III) in ternary Eu-HA/FA-hydrous alumina systems are not dominated by either HA/FA or hydrous alumina, but are dominated by both HA/FA and hydrous alumina. The results are important for understanding the sorption mechanisms and the nature of surface adsorbed Eu(III) species and trivalent chemical homologues of Eu(III) in the natural environment.

  8. Synthesis and LPG sensing properties of nano-sized cadmium oxide.

    PubMed

    Waghulade, R B; Patil, P P; Pasricha, Renu

    2007-04-30

    This paper reports the synthesis and liquid petroleum gas (LPG) sensing properties of nano-sized cadmium oxide (CdO). The nano-sized CdO powder was successfully synthesized by using a chemical co-precipitation method using cadmium acetate and the ammonium hydroxide, as starting materials and water as a carrier. The resulting nano-sized powder was characterized by X-ray diffraction (XRD) measurements and the transmission electron microscopy (TEM). The LPG sensing properties of the synthesized nano-sized CdO were investigated at different operating temperatures and LPG concentrations. It was found that the calcination temperature and the operating temperature significantly affect the sensitivity of the nano-sized CdO powder to the LPG. The sensitivity is found to be maximum when the calcination temperature was 400 degrees C. The sensitivity to 75ppm of LPG is maximum at an operating temperature 450 degrees C and it was found to be approximately 341%. The response and recovery times were found to be nearly 3-5s and 8-10s, respectively. The synthesized nano-sized CdO powder is able to detect up to 25ppm for LPG with reasonable sensitivity at an operating temperature 450 degrees C and it can be reliably used to monitor the concentration of LPG over the range (25-75ppm). The experimental results of the LPG sensing studies reveal that the nano-sized CdO powder synthesized by a simple co-precipitation method is a suitable material for the fabrication of the LPG sensor.

  9. Reaction between hydrous wadsleyite and iron: Implication for water distribution in Earth's transition zone

    NASA Astrophysics Data System (ADS)

    Zhu, F.; Li, J.; Liu, J.; Dong, J.

    2017-12-01

    The mantle transition zone (TZ) is considered as a potential water reservoir due to large capacities of wadsleyite and ringwoodite to store water in the structures. Whether it is a hydrous layer or an empty reservoir, however, is still under debate. Because the TZ may contain metallic iron1, 2 and water is an oxidizing agent at > 5 GPa, the stability of coexisting iron and TZ hydrous phases needs to be examined. In this study, we conducted multi-anvil experiments on iron with synthetic hydrous wadsleyite or forsterite and water under TZ pressure-temperature conditions. Similar rapid reactions were observed for both types of starting materials, producing ferropericlase, iron-bearing wadsleyite or ringwoodite, and iron hydride. The results imply that a hydrous TZ is incompatible with a reduced state, and that water distribution of TZ is confined to subducting slabs and slab-mantle boundaries, where water or hydrous phases in slab must oxidize the adjacent mantle before they can hydrate the silicates. In contrast, the bulk transition zone may be mostly dry. The iron hydride produced from this slab-mantle interaction may sink to greater depths due to their low melting temperature3, thus providing a pathway for hydrogen to enter the lower mantle and core. References 1. O'Neill HSC, McCammon C, Canil D, Rubie D, Ross C, Seifert F. Mossbauer spectroscopy of mantle transition zone phases and determination of minimum Fe3+ content. American Mineralogist 1993, 78(3-4): 456-460. 2. Rohrbach A, Ballhaus C, Golla-Schindler U, Ulmer P, Kamenetsky VS, Kuzmin DV. Metal saturation in the upper mantle. Nature 2007, 449(7161): 456-458. 3. Sakamaki K, Takahashi E, Nakajima Y, Nishihara Y, Funakoshi K, Suzuki T, et al. Melting phase relation of FeH x up to 20GPa: Implication for the temperature of the Earth's core. Physics of the Earth and Planetary Interiors 2009, 174(1): 192-201.

  10. Preparation of a nanosized as(2)o(3)/mn(0.5)zn(0.5)fe(2)o(4) complex and its anti-tumor effect on hepatocellular carcinoma cells.

    PubMed

    Zhang, Jia; Zhang, Dongsheng

    2009-01-01

    Manganese-zinc-ferrite nanoparticles (Mn(0.5)Zn(0.5)Fe(2)O(4), MZF-NPs) prepared by an improved co-precipitation method and were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD) and energy dispersive spectrometry (EDS). Then thermodynamic testing of various doses of MZF-NPs was performed in vitro. The cytotoxicity of the Mn(0.5)Zn(0.5)Fe(2)O(4) nanoparticles in vitro was tested by the MTT assay. A nanosized As(2)O(3)/Mn(0.5)Zn(0.5)Fe(2)O(4) complex was made by an impregnation process. The complex's shape, component, envelop rate and release rate of As(2)O(3) were measured by SEM, EDS and atom fluorescence spectrometry, respectively. The therapeutic effect of nanosized As(2)O(3)/Mn(0.5)Zn(0.5)Fe(2)O(4) complex combined with magnetic fluid hyperthermia (MFH) on human hepatocelluar cells were evaluated in vitro by an MTT assay and flow cytometry. The results indicated that Mn(0.5)Zn(0.5)Fe(2)O(4) and nanosized As(2)O(3)/Mn(0.5)Zn(0.5)Fe(2)O(4) complex were both prepared successfully. The Mn(0.5)Zn(0.5)Fe(2)O(4) nanoparticles had powerful absorption capabilities in a high-frequency alternating electromagnetic field, and had strong magnetic responsiveness. Moreover, Mn(0.5)Zn(0.5)Fe(2)O(4) didn't show cytotoxicity in vitro. The therapeutic result reveals that the nanosized As(2)O(3)/Mn(0.5)Zn(0.5)Fe(2)O(4) complex can significantly inhibit the growth of hepatoma carcinoma cells.

  11. Megafans as Hydrous Environments

    NASA Technical Reports Server (NTRS)

    Wilkinson, M. Justin; Miller, R. McG.; Allen, C. C.; Kreslavsky, M. H.; Eckardt, F.

    2009-01-01

    The mesoscale sedimentary environment known as the megafan, is a low-angle, partial cone of fluvial sediment generated where a river enters an unconfined basin where it begins the process of avulsing over wide areas. In shifting to different positions, the river lays down a partial cone of sediment and establishes a characteristic radial pattern of paleo courses. The apparent paucity of sedimentary bodies obviously tied to martian outflow channels may also relate to the difficulty of recognition due to their sheer size and featurelessness. However, the existence of megafans on Mars is being examined now that their ubiquity and characteristics on Earth are better understood. Accordingly we suggest two likely candidates on Mars: Maja Valles fluvial cone and Amazonis Planitia fluvial sedimentary bodies. Two cryptic examples from Amazonis Planitia may be important for understanding subsurface hydrous accumulation. For at least some of its history, discharges from Mangala Valles likely resulted in megafans. Distances from the end of Mangala Valles to the northern (low) margin of the planitia are very large, a fact that has suggested that fluvial emplacement was unlikely. However, the megafan model shows that long megafan radii are indeed feasible. It has been suggested further that discharge from Labou Vallis (8.5S 154.5W) must have led to fluvial sedimentation in the planitia. We suggest that during locally non-lacustrine/ocean phases, this sedimentation would have occurred in the form of megafans. However, the megafan model shows that long megafan radii are indeed feasible. It has been suggested further that discharge from Labou Vallis (8.5S 154.5W) must have led to fluvial sedimentation in the planitia. We suggest that during locally non-lacustrine/ocean phases, this sedimentation would have occurred in the form of megafans. Megafans emanating from Marte, Mangala and Labou valles have probably contributed to hydrous near-subsurface environments--in their distal

  12. Advances in nanosized zeolites

    NASA Astrophysics Data System (ADS)

    Mintova, Svetlana; Gilson, Jean-Pierre; Valtchev, Valentin

    2013-07-01

    This review highlights recent developments in the synthesis of nanosized zeolites. The strategies available for their preparation (organic-template assisted, organic-template free, and alternative procedures) are discussed. Major breakthroughs achieved by the so-called zeolite crystal engineering and encompass items such as mastering and using the physicochemical properties of the precursor synthesis gel/suspension, optimizing the use of silicon and aluminium precursor sources, the rational use of organic templates and structure-directing inorganic cations, and careful adjustment of synthesis conditions (temperature, pressure, time, heating processes from conventional to microwave and sonication) are addressed. An on-going broad and deep fundamental understanding of the crystallization process, explaining the influence of all variables of this complex set of reactions, underpins an even more rational design of nanosized zeolites with exceptional properties. Finally, the advantages and limitations of these methods are addressed with particular attention to their industrial prospects and utilization in existing and advanced applications.

  13. Water and Slabs in the Transition Zone - Hydrous Ringwoodite in Diamond

    NASA Astrophysics Data System (ADS)

    Pearson, D. G.; Brenker, F. E.; Nestola, F.; McNeill, J.; Nasdala, L.; Hutchison, M.; Matveev, S.; Mather, K.; Vincze, L.; Schmitz, S.; Vekemens, B.

    2014-12-01

    Theory and experiments have shown that the Earth's Transition Zone (TZ) could be a major repository for water, due to the ability of the higher-pressure polymorphs of olivine - wadsleyite and ringwoodite - to host up to ~2.5wt. % H2O. Despite experimental demonstration of the water-bearing capacity of these phases, geophysical probes such as electrical conductivity have provided conflicting results, and the issue of whether the TZ contains abundant water remains highly controversial. We report X-ray diffraction, Raman and infra-red spectroscopic evidence for the first terrestrial occurrence of any higher pressure polymorph of olivine: ringwoodite, included in a diamond from Juína, Brazil. The ringwoodite occurs with a Ca-walstromite phase that we interpret to be retrogressed Ca-silicate perovskite. The most likely interpretation of this two-phase assemblage is that it represents a partially retrogressed portion of a somewhat Fe-rich peridotitic mantle, in which hydrous ringwoodite, and former CaSiO3- perovskite co-existed above 15GPa. The ringwoodite has a Mg# of ~ 75, suggesting that it may be mantle hybrised with a more fertile component such as subducted oceanic crust. The water-rich nature of this inclusion (~1.5 wt%), along with the preservation of ringwoodite, is the first direct evidence that, at least locally, the TZ is hydrous, to about 1 wt%. As well as being in agreement with recent magnetotelluric estimates of the TZ water content, this amount of water helps to reconcile measured TZ seismic velocities with those predicted from lab experiments. The finding also indicates that some kimberlites must have their primary sources in this deep mantle region. The high water content of the ringwoodite suggests that it was not close to the mantle geotherm when trapped in the diamond. This may be an indication that the the assemblage was part of a water-rich subducted slab out of thermal equilibrium, within the transition zone. The water-rich nature of the

  14. Single-crystal structure determination of hydrous minerals and insights into a wet deep lower mantle

    NASA Astrophysics Data System (ADS)

    Zhang, L.; Yuan, H.; Meng, Y.; Popov, D.

    2017-12-01

    Water enters the Earth's interior through hydrated subducting slabs. How deep within the lower mantle (670-2900 km depth) can water be transported down and stored depends upon the availability of hydrous phases that is thermodynamically stable under the high P-T conditions and have a sufficiently high density to sink through the lower mantle. Phase H [MgSiH2O4] (1) and the δ-AlOOH (2) form solid solutions that are stable in the deep lower mantle (3), but the solid solution phase is 10% lighter than the corresponding lower mantle. Recent experimental discoveries of the pyrite (Py) structured FeO2 and FeOOH (4-6) suggest that these Fe-enriched phases can be transported to the deepest lower mantle owing to their high density. We have further discovered a very dense hydrous phase in (Fe,Al)OOH with a previously unknown hexagonal symmetry and this phase is stable relative to the Py-phase under extreme high P-T conditions in the deep lower mantle. Through in situ multigrain analysis (7) and single-crystal structure determination of the hydrous minerals at P-Tconditions of the deep lower mantle, we can obtain detailed structure information of the hydrous phases and therefore provide insights into the hydration mechanism in the deep lower mantle. These highly stable hydrous minerals extend the water cycle at least to the depth of 2900 km. 1. M. Nishi et al., Nature Geoscience 7, 224-227 (2014). 2. E. Ohtani, K. Litasov, A. Suzuki, T. Kondo, Geophysical Research Letters 28, 3991-3993 (2001). 3. I. Ohira et al., Earth and Planetary Science Letters 401, 12-17 (2014). 4. Q. Hu et al., Proceedings of the National Academy of Sciences of the United States of America 114, 1498-1501 (2017). 5. M. Nishi, Y. Kuwayama, J. Tsuchiya, T. Tsuchiya, Nature 547, 205-208 (2017). 6. Q. Hu et al., Nature 534, 241-244 (2016). 7. L. Zhang et al., American Mineralogist 101, 231-234 (2016).

  15. Three manganese oxide-rich marine sediments harbor similar communities of acetate-oxidizing manganese-reducing bacteria

    PubMed Central

    Vandieken, Verona; Pester, Michael; Finke, Niko; Hyun, Jung-Ho; Friedrich, Michael W; Loy, Alexander; Thamdrup, Bo

    2012-01-01

    Dissimilatory manganese reduction dominates anaerobic carbon oxidation in marine sediments with high manganese oxide concentrations, but the microorganisms responsible for this process are largely unknown. In this study, the acetate-utilizing manganese-reducing microbiota in geographically well-separated, manganese oxide-rich sediments from Gullmar Fjord (Sweden), Skagerrak (Norway) and Ulleung Basin (Korea) were analyzed by 16S rRNA-stable isotope probing (SIP). Manganese reduction was the prevailing terminal electron-accepting process in anoxic incubations of surface sediments, and even the addition of acetate stimulated neither iron nor sulfate reduction. The three geographically distinct sediments harbored surprisingly similar communities of acetate-utilizing manganese-reducing bacteria: 16S rRNA of members of the genera Colwellia and Arcobacter and of novel genera within the Oceanospirillaceae and Alteromonadales were detected in heavy RNA-SIP fractions from these three sediments. Most probable number (MPN) analysis yielded up to 106 acetate-utilizing manganese-reducing cells cm−3 in Gullmar Fjord sediment. A 16S rRNA gene clone library that was established from the highest MPN dilutions was dominated by sequences of Colwellia and Arcobacter species and members of the Oceanospirillaceae, supporting the obtained RNA-SIP results. In conclusion, these findings strongly suggest that (i) acetate-dependent manganese reduction in manganese oxide-rich sediments is catalyzed by members of taxa (Arcobacter, Colwellia and Oceanospirillaceae) previously not known to possess this physiological function, (ii) similar acetate-utilizing manganese reducers thrive in geographically distinct regions and (iii) the identified manganese reducers differ greatly from the extensively explored iron reducers in marine sediments. PMID:22572639

  16. Three manganese oxide-rich marine sediments harbor similar communities of acetate-oxidizing manganese-reducing bacteria.

    PubMed

    Vandieken, Verona; Pester, Michael; Finke, Niko; Hyun, Jung-Ho; Friedrich, Michael W; Loy, Alexander; Thamdrup, Bo

    2012-11-01

    Dissimilatory manganese reduction dominates anaerobic carbon oxidation in marine sediments with high manganese oxide concentrations, but the microorganisms responsible for this process are largely unknown. In this study, the acetate-utilizing manganese-reducing microbiota in geographically well-separated, manganese oxide-rich sediments from Gullmar Fjord (Sweden), Skagerrak (Norway) and Ulleung Basin (Korea) were analyzed by 16S rRNA-stable isotope probing (SIP). Manganese reduction was the prevailing terminal electron-accepting process in anoxic incubations of surface sediments, and even the addition of acetate stimulated neither iron nor sulfate reduction. The three geographically distinct sediments harbored surprisingly similar communities of acetate-utilizing manganese-reducing bacteria: 16S rRNA of members of the genera Colwellia and Arcobacter and of novel genera within the Oceanospirillaceae and Alteromonadales were detected in heavy RNA-SIP fractions from these three sediments. Most probable number (MPN) analysis yielded up to 10(6) acetate-utilizing manganese-reducing cells cm(-3) in Gullmar Fjord sediment. A 16S rRNA gene clone library that was established from the highest MPN dilutions was dominated by sequences of Colwellia and Arcobacter species and members of the Oceanospirillaceae, supporting the obtained RNA-SIP results. In conclusion, these findings strongly suggest that (i) acetate-dependent manganese reduction in manganese oxide-rich sediments is catalyzed by members of taxa (Arcobacter, Colwellia and Oceanospirillaceae) previously not known to possess this physiological function, (ii) similar acetate-utilizing manganese reducers thrive in geographically distinct regions and (iii) the identified manganese reducers differ greatly from the extensively explored iron reducers in marine sediments.

  17. Shock effects on hydrous minerals and implications for carbonaceous meteorites

    NASA Technical Reports Server (NTRS)

    Lange, M. A.; Ahrens, T. J.; Lambert, P.

    1985-01-01

    The effect of shock loading over the pressure range of 29-59 GPa on the shock-recovered specimens of antigorite serpentine, Mg3Si2O5(OH)4, were investigated employing infrared (IR) spectroscopy, thermogravimetric analysis, and optical and scanning electron microscopy. With increasing shock pressure, there was an increase in H2O IR absorption peaks at the expense of OH peaks, while the changes in SiO bond vibration modes were identical to those seen for other, nonhydrous minerals. Thermogravimetric results on vented assembly samples showed linear relationships between the shock pressure and both the length of dehydration interval and the effective activation energy for releasing post-shock structural water. Optical and scanning electron microscopy revealed gas bubbles, which appeared to be injected into zones of partial melting, and vesicular dark veins distributed throughout the shocked samples. It is suggested that shock loading of hydrous minerals would release and redistribute free water in the regoliths of carbonaceous chondrite parent bodies, giving rise to observed hydrous alterations.

  18. Development of Sediment Quality Values for Puget Sound. Volume 1.

    DTIC Science & Technology

    1986-09-01

    62 cadmium CHROMIUM,63 chromium COPPER ,64 copper IRON ,65 iron LEAD ,66 lead MANGANES ,67 manganese NICKEL ,68 nickel SELENIUM,69 selenium SILVER ,70...BERYLLIU beryllium 67. CADMIUM cadmium 68. CHROMIUM chromium 69. COPPER copper 70. IRON iron 71. LEAD lead 72. MANGANES manganese 73. NICKEL nickel 74...they can also be strongly influenced by iron and manganese oxide and hydrous oxide surfaces (these phases can scavenge metals under oxidizing

  19. Discovery of composite diopside-magnetite lamellae in discrete olivine crytals from Colorado Plateau diatremes: indication of former hydrous ringwoodite

    NASA Astrophysics Data System (ADS)

    Sakamaki, K.; Sato, Y.; Marshall, E. W., IV; Ogasawara, Y.

    2016-12-01

    We investigate composite diopside (Di) + magnetite (Mt) lamellae in olivine crystals from Oligocene diatremes of serpentinized ultramafic microbreccia located at Buell Park (AZ) and Green Knobs (NM) in the Colorado Plateau, and propose their genesis as breakdown products of precursor hydrous ringwoodite (γ-olivine) lamellae coexisting with α-olivine host. Among a hundred olivines (2-5 mm across, Fo89-93 in mol%) from both localities, the Di + Mt composite lamellae are recognized in only 15 of relatively Fe-rich grains (Fo89-91.5). The olivine host contains minor amounts of Ca (< 0.01 wt% CaO), Mn, Ni, and Co. Lamellar Di (Di95) contains minor amounts of Al, Na, Cr, Mn, and Ni. Lamellar Mt contains Cr (5.0-43.0 wt% Cr2O3) with minor amounts of Si, Ti, Al, Mn, Ni, and Co. The area fractions of olivine host and the lamellae in a typical grain (sample no. BP02-3) were measured at 98.8 % of the host and 1.2 % of the lamellae that are composed of Di:Mt = 85:15 to 53:47, average 66:34. The estimated average CaO content in a lamella reaches 17 wt% and the reintegrated CaO in the host and the lamellae is 0.22 wt%.We propose that Fe3+ in lamellar Mt was produced by dehydration of hydrous precursor phase via the reaction, Fe2+ + OH- = Fe3+ + O2- + 1/2H2. Converting Fe3+ into Fe2+ in the precursor phase based on this reaction, the composition satisfies the stoichiometry of olivine (X2TO4). Thus, the pre-existing phase certainly is of hydrous and contains Ca and other components with olivine stoichiometry. The most likely phase is lamellar hydrous ringwoodite. The precursor phase, hydrous ringwoodite, might have occurred as lamellae with α-olivine host and have probably decomposed by the following reaction, (1+X+Y+Z) hydrous ringwoodite → α-olivine + X Di + Y Mt + Z H2 (where X:Y:Z=2:1:1). The composite Di-Mt lamellae after hydrous ringwoodite lamellae in α-olivine host certainly suggest the materials originated from a deep mantle setting at least 300 km.

  20. A crystallographic model for hydrous wadsleyite (Beta-Mg2SiO4)

    NASA Technical Reports Server (NTRS)

    Smyth, J. R.

    1994-01-01

    Wadsleyite (beta-Mg2SiO4) is believed to be the most abundant phase in the Earth between depths of 400 and about 525km. Because of the unusual crystal chemistry, Smyth suggested that this phase might be a significant host for hydrogen in the transition zone. Indeed, of the nominally anhydrous phases believed to make up the upper mantle and transition zone none has been reported with a greater H content than wadsleyite. Young et al, report the synthesis of hydrous, Fe-bearing wadsleyite with up to 60,000 H per 10(exp 6) Si. Using ionic constraints and maximal subgroup symmetry, a hypothetical, ordered model for hydrous wadsleyite has been created and examined. The model has formula Mg7Si4O14(OH)2, has space group Pmmb, has an ordered vacancy into one of two non-equivalent M2 sites, and contains two different H positions, one on each of the non-equivalent O1 sites. Electrostatic calculations indicate that hydration would relieve the underbonding of O1 as well as the overbonding of the bridging oxygen, O2, so that the hydrous phase may be more stable than the anhydrous phase. This model makes several predictions that may be of significance for the mechanisms and amounts of H that may be stored in the transition zone of the Earth, and by which the model may be tested experimentally.

  1. Stability and Solid Solutions of Hydrous Alumino-Silicates in the Earth's Mantle

    NASA Astrophysics Data System (ADS)

    Panero, W. R.; Caracas, R.

    2017-12-01

    The degree to which the Earth's mantle stores and cycles water in excess of the storage capacity of nominally anhydrous minerals is dependent upon the stability of hydrous phases under mantle-relevant pressures, temperatures, and compositions. Two hydrous phases, phase D and phase H are stable to the pressures and temperatures of the Earth's lower mantle, suggesting that the Earth's lower mantle may participate in the cycling of water. Each phase has a wide solid solution series between MgSi2O6H2-Al2SiO6H2 and MgSiO4H2-2δAlOOH-SiO2, respectively, yet most work addresses end-member compositions for analysis of stability and elastic properties. We present the results of density functional theory calculations on the stability, structure, bonding, partitioning, and elasticity of hydrous phases D and H in the Al2O3-SiO2-MgO-H2O system, addressing the solid solution series through a statistical sampling of site occupancy and calculation of the partition function from the grand canonical ensemble. We find that the addition of Al to the endmember compositions stabilizes each phase to higher temperatures through additional configurational entropy. We further find that solid solutions tend not to undergo hydrogen-bond symmetrization as is found in the end member compositions as a result of non-symmetric bonding environments.

  2. Significance of hydrous silicate lamellae in pyrope-rich garnets from the Garnet Ridge in the Colorado Plateau

    NASA Astrophysics Data System (ADS)

    Ogasawara, Y.; Sakamaki, K.; Sato, Y.

    2014-12-01

    Pyrope-rich garnets originated from the upper mantle underneath the Colorado Plateau occur at the Garnet Ridge. These garnets contain the following lamellae of hydrous and anhydrous minerals; Rt, Ilm, crichtonites, Cr-Spl, Amp, Cpx, Chl, rarely Apt, srilankite and carmichealite. The origin of these lamellae in the garnets is controversial; exsolved origin or epitaxial growth. We emphasize here the close relations between the presence of hydrous lamellae and the OH concentrations in the host garnets. Lamella phases were identified with a standard-less quantitative EDS system and a laser Raman spectrometer with Ar+ laser (514.5 nm). OH concentrations in garnets were quantitated on the basis of IR absorption spectra of garnet by micro FT-IR method using IR absorption coefficient (8770 L/mol/cm2, Katayama et al., 2006). Pyrope-rich reddish brown garnet (group B by Sato et al., AGU2014F) has large variations of major chemical compositions (Prp: 49-76, Alm: 6-43, Grs: 6-26 mol%), and OH contents (2-177 ppm wt. H2O). Among this group garnets, Ca-rich ones (Prp: 49-66; Alm: 18-28; Grs: 16-26 mol%) have lamellae of both hydrous (Amp and Chl) and anhydrous (Rt, Ilm, and Cpx) minerals. Amp and Chl lamellae are pargasitic amphibole and clinochlore, respectively, and their host garnets contain significantly low amounts of OH (2-42 ppm). Cr and pyrope-rich garnet (group A by Sato et al., AGU2014F) has chemical compositions of Prp: 67-74, Alm: 13-18, Grs: 7-11 mol% with Cr2O3 up to 5.9 wt.%, and contains lamellae of anhydrous minerals (Rt, Ilm, crichtonites, and Cr-Spl). The host garnet with these anhydrous lamellae contains a little higher OH ranging 24 to 115 ppm. Summarizing the present results, the OH contents of the host garnets depend on the presence of hydrous silicate lamella phase; OH in the garnet with hydrous silicate lamellae is lower than that in the garnet with anhydrous lamellae. The precursor OH incorporated in the host garnet structure was exsolved as hydrous

  3. Manganese uptake of imprinted polymers

    DOE Data Explorer

    Susanna Ventura

    2015-09-30

    Batch tests of manganese imprinted polymers of variable composition to assess their ability to extract lithium and manganese from synthetic brines at T=45C . Data on manganese uptake for two consecutive cycles are included.

  4. Manganese in Madison's drinking water.

    PubMed

    Schlenker, Thomas; Hausbeck, John; Sorsa, Kirsti

    2008-12-01

    Public concern over events of manganese-discolored drinking water and the potential for adverse health effects from exposure to excess manganese reached a high level in 2005. In response, Public Health Madison Dane County, together with the Madison Water Utility, conceived and implemented a public health/water utility strategy to quantify the extent of the manganese problem, determine the potential for adverse human health effects, and communicate these findings to the community. This strategy included five basic parts: taking an inventory of wells and their manganese levels, correlating manganese concentration with turbidity, determining the prevalence and distribution of excess manganese in Madison households, reviewing the available scientific literature, and effectively communicating our findings to the community. The year-long public health/water utility strategy successfully resolved the crisis of confidence in the safety of Madison's drinking water.

  5. Manganese ore tailing: optimization of acid leaching conditions and recovery of soluble manganese.

    PubMed

    Santos, Olívia de Souza Heleno; Carvalho, Cornélio de Freitas; Silva, Gilmare Antônia da; Santos, Cláudio Gouvêa Dos

    2015-01-01

    Manganese recovery from industrial ore processing waste by means of leaching with sulfuric acid was the objective of this study. Experimental conditions were optimized by multivariate experimental design approaches. In order to study the factors affecting leaching, a screening step was used involving a full factorial design with central point for three variables in two levels (2(3)). The three variables studied were leaching time, concentration of sulfuric acid and sample amount. The three factors screened were shown to be relevant and therefore a Doehlert design was applied to determine the best working conditions for leaching and to build the response surface. By applying the best leaching conditions, the concentrations of 12.80 and 13.64 %w/w of manganese for the global sample and for the fraction -44 + 37 μm, respectively, were found. Microbeads of chitosan were tested for removal of leachate acidity and recovering of soluble manganese. Manganese recovery from the leachate was 95.4%. Upon drying the leachate, a solid containing mostly manganese sulfate was obtained, showing that the proposed optimized method is efficient for manganese recovery from ore tailings. Copyright © 2014 Elsevier Ltd. All rights reserved.

  6. Biogeochemical cycling of manganese in Oneida Lake, New York: whole lake studies of manganese

    NASA Technical Reports Server (NTRS)

    Aguilar, C.; Nealson, K. H.

    1998-01-01

    Oneida Lake, New York is a eutrophic freshwater lake known for its abundant manganese nodules and a dynamic manganese cycle. Temporal and spatial distribution of soluble and particulate manganese in the water column of the lake were analyzed over a 3-year period and correlated with other variables such as oxygen, pH, and temperature. Only data from 1988 are shown. Manganese is removed from the water column in the spring via conversion to particulate form and deposited in the bottom sediments. This removal is due to biological factors, as the lake Eh/pH conditions alone can not account for the oxidation of the soluble manganese Mn(II). During the summer months the manganese from microbial reduction moves from the sediments to the water column. In periods of stratification the soluble Mn(II) builds up to concentrations of 20 micromoles or more in the bottom waters. When mixing occurs, the soluble Mn(II) is rapidly removed via oxidation. This cycle occurs more than once during the summer, with each manganese atom probably being used several times for the oxidation of organic carbon. At the end of the fall, whole lake concentrations of manganese stabilize, and remain at about 1 micromole until the following summer, when the cycle begins again. Inputs and outflows from the lake indicate that the active Mn cycle is primarily internal, with a small accumulation each year into ferromanganese nodules located in the oxic zones of the lake.

  7. Heavy Metal Soil Contamination at U.S. Army Installations: Proposed Research and Strategy for Technology Development

    DTIC Science & Technology

    1994-03-01

    substrates that form the basis of the soil, such as carbonates, clay minerals, organic matter, iron and manganese oxides and hydroxides, sulfides, or...32 10 25 2.5 32 to 64 7 20 1.4 Total 100 200.7 interstitial water, clay minerals, sulfides, carbonates, organic matter, hydrous iron and manganese ...condensation reaction with OH- groups on the surface of (silicon, iron, manganese , and aluminum) com- pounds (Calmano and Forsmer 1983). Sorption-based

  8. RATES OF HYDROUS FERRIC OXIDE CRYSTALLIZATION AND THE INFLUENCE ON COPRECIPITATED ARSENATE

    EPA Science Inventory

    Arsenate coprecipitated with hydrous ferric oxide (HFO) was stabilized against dissolution during transformation of HFO to more crystalline iron (hydr)oxides. The rate of arsenate stabilization approximately coincided with the rate of HFO transformation at pH 6 and 40 ?C. Compa...

  9. Natural rubber, a potential alternative source for the synthesis of renewable fuels via Hydrous Pyrolysis

    NASA Astrophysics Data System (ADS)

    Ahmad, N.; Dayana, S. A. S.; Abnisa, F.; Mohd, W. A. W. D.

    2018-03-01

    Natural rubber is a humid agricultural harvest, which mostly contains hydrocarbon cis-1, 4-Poly isoprene. Through depolymerisation technology, the natural rubber can be changed into liquid product, and then it can be subsequently utilized as a fuel or chemical feedstock. This article aims to provide an outlook on the natural rubber and its sources, which are available globally. Numerous depolymerisation processes, which include pyrolysis, gasification, chemical degradation, catalytic cracking and hydrogenation, were introduced in this paper, while the focus of discussion was emphasized on the hydrous pyrolysis process. Many studies have shown that the use of hydrous pyrolysis able to improve the depolymerisation process, e.g. the raw material can be feed without drying, the process can be carried out at lower temperature, only the water is used as the reaction medium, and it is easy to separate the water from oil product. The effect of operating parameters such as temperature, water to rubber mass ratio, reaction time and type of gases on the product yield and composition were reviewed in this paper. In addition, this paper also highlighted the eco-friendly and economic viability of the hydrous pyrolysis process.

  10. Thermal Stress Behavior of Micro- and Nano-Size Aluminum Films

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hanabusa, T.; Kusaka, K.; Nishida, M.

    2008-03-17

    In-situ observation of thermal stresses in thin films deposited on silicon substrate was made by X-ray and synchrotron radiation. Specimens prepared in this experiment were micro- and nano-size thin aluminum films with and without passivation film. The thickness of the film was 1 micrometer for micro-size films and 10, 20 and 50 nanometer for nano-size films. The stress measurement in micro-size films was made by X-ray radiation whereas the measurement of nano-size films was made by synchrotron radiation. Residual stress measurement revealed tensile stresses in all as-deposited films. Thermal stresses were measured in a series of heating- and cooling-stage. Thermalmore » stress behavior of micro-size films revealed hysteresis loop during a heating and cooling process. The width of a hysteresis loop was larger in passivated film that unpassivated film. No hysteresis loops were observed in nano-size films with SiO{sub 2} passivation. Strengthning mechanism in thin films was discussed on a passivation film and a film thickness.« less

  11. Aromatic moieties in meteoritic macromolecular materials: analyses by hydrous pyrolysis and δ 13C of individual compounds

    NASA Astrophysics Data System (ADS)

    Sephton, M. A.; Pillinger, C. T.; Gilmour, I.

    2000-01-01

    Hydrous pyrolysis, supercritical fluid extraction (SFE), gas chromatography-mass-spectrometry (GC-MS) and isotope ratio monitoring-gas chromatography-mass spectrometry (irm-GC-MS) were used to investigate the constitution of macromolecular materials in meteorites. Results from the carbonaceous chondrites Orgueil (CI1) and Cold Bokkeveld (CM2) were compared with those obtained previously from Murchison (CM2). Fragments of meteoritic macromolecular materials were produced by hydrous pyrolysis, extracted by SFE, and identified by GC-MS. The CI1 and CM2 hydrous pyrolysates all contain volatile aromatic compounds, some of which have aliphatic side chains, hydroxyl groups, and thiophene rings attached. The results indicate that the macromolecular materials in these meteorites are qualitatively similar. However, the pyrolysates show significant quantitative differences, with the products of ether linkages and condensed aromatic networks being less abundant in the more aqueously altered meteorites. In addition, the methylnaphthalene maturity parameter negatively correlates with aqueous alteration. These features are interpreted as the result of chemical reactions favored under hydrous conditions. Hence, the extent of aqueous alteration on the meteorite parent body appears to be the most important evolutionary stage in determining the final structure of macromolecular materials in the CI1 and CM2 meteorites. The carbon isotopic compositions of the fragments of macromolecular materials were determined by irm-GC-MS. δ 13C values for the hydrous pyrolysis products range from -25.5 to -10.2‰ for Orgueil and -22.9 to +4.0‰ for Cold Bokkeveld. These values can be compared to the -24.6 to -5.6‰ range obtained previously for Murchison. The low molecular weight components in each hydrous pyrolysate display shifts to increased 13C contents with carbon number. This indicates the production of simple organic entities by the preferential cracking of 12C- 12C bonds in more complex

  12. 21 CFR 73.2775 - Manganese violet.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... manganese violet is a violet pigment obtained by reacting phosphoric acid, ammonium dihydrogen orthophosphate, and manganese dioxide at temperatures above 450 °F. The pigment is a manganese ammonium...

  13. Evidence for the late formation of hydrous asteroids from young meteoritic carbonates.

    PubMed

    Fujiya, Wataru; Sugiura, Naoji; Hotta, Hideyuki; Ichimura, Koji; Sano, Yuji

    2012-01-17

    The accretion of small bodies in the Solar System is a fundamental process that was followed by planet formation. Chronological information of meteorites can constrain when asteroids formed. Secondary carbonates show extremely old (53)Mn-(53)Cr radiometric ages, indicating that some hydrous asteroids accreted rapidly. However, previous studies have failed to define accurate Mn/Cr ratios; hence, these old ages could be artefacts. Here we develop a new method for accurate Mn/Cr determination, and report a reliable age of 4,563.4+0.4/-0.5 million years ago for carbonates in carbonaceous chondrites. We find that these carbonates have identical ages, which are younger than those previously estimated. This result suggests the late onset of aqueous activities in the Solar System. The young carbonate age cannot be explained if the parent asteroid accreted within 3 million years after the birth of the Solar System. Thus, we conclude that hydrous asteroids accreted later than differentiated and metamorphosed asteroids.

  14. Characterization of Sumbawa manganese ore and recovery of manganese sulfate as leaching products

    NASA Astrophysics Data System (ADS)

    Kusumaningrum, Retno; Rahmani, Siti Astari; Widayatno, Wahyu Bambang; Wismogroho, Agus Sukarto; Nugroho, Dwi Wahyu; Maulana, Syahrizal; Rochman, Nurul Taufiqu; Amal, M. Ikhlasul

    2018-05-01

    The aims of this research were to study the leaching process of manganese ore which originated from Sumbawa, Indonesia and its characterization. A high grade Indonesian manganese ore from Sumbawa, West of Nusa Tenggara was characterized by X-Ray Fluorescence (XRF). The result showed composition of 78.8 % Mn, 17.77% Fe and the rest were trace elements such as Si, Co, Ti, Zn, V and Zr contents. X-Ray Diffraction analysis showed that the manganese ore was consisted of pyrolusite (MnO2), rhodonite (MnSiO3), rhodochrosite (MnCO3) and hematite (Fe2O3). Manganese ore was also analyzed by thermal analysis to observe their thermal decomposition character. In this study, sulphuric acid (H2SO4, 6 M) was deployed as leaching agent. The leaching process was performed at 90 °C for two hours with the addition of NH4OH to control pH. Recovery percentage of leaching process yielded of 87 % Mn extracted. The crystallization process result at heating temperature of 200 °C was confirmed by XRD as manganese sulfate.

  15. Nano-Se Assimilation and Action in Poultry and Other Monogastric Animals: Is Gut Microbiota an Answer?

    NASA Astrophysics Data System (ADS)

    Surai, Peter F.; Kochish, Ivan I.; Velichko, Oksana A.

    2017-12-01

    Recently, a comprehensive review paper devoted to roles of nano-Se in livestock and fish nutrition has been published in the Nanoscale Research Letters. The authors described in great details an issue related to nano-Se production and its possible applications in animal industry and medicine. However, molecular mechanisms of nano-Se action were not described and the question of how nano-Se is converted into active selenoproteins is not resolved. It seems likely that the gut microbiota can convert nano-Se into selenite, H2Se or Se-phosphate with the following synthesis of selenoproteins. This possibility needs to be further studied in detail, and advantages and disadvantages of nano-Se as a source of Se in animal/poultry/fish nutrition await critical evaluations.

  16. Mineral resource of the month: manganese

    USGS Publications Warehouse

    Corathers, Lisa A.

    2012-01-01

    Manganese is a silver-colored metal resembling iron and often found in conjunction with iron. The earliest-known human use of manganese compounds was in the Stone Age, when early humans used manganese dioxide as pigments in cave paintings. In ancient Rome and Egypt, people started using it to color or remove the color from glass - a practice that continued to modern times. Today, manganese is predominantly used in metallurgical applications as an alloying addition, particularly in steel and cast iron production. Steel and cast iron together provide the largest market for manganese (historically 85 to 90 percent), but it is also alloyed with nonferrous metals such as aluminum and copper. Its importance to steel cannot be overstated, as almost all types of steel contain manganese and could not exist without it.

  17. Structure, thermodynamics, and properties of hydrous aluminosilicate melt in the deep Earth

    NASA Astrophysics Data System (ADS)

    Bajgain, S. K.; Mookherjee, M.

    2017-12-01

    In this study, we use first-principles molecular dynamics (FPMD) simulations to explore the structure, thermodynamics, and transport properties of alkali bearing aluminosliciate melt (NaAlSi2O6) with 4 wt.% H2O. We explored physical properties of the hydrous jadeite melt at temperatures and pressures relevant for the Earth's mantle, i.e., 2500- 4000 K and up to 50 GPa. Our results indicate that the fundamental structural units of jadeite, i.e., one dimensional (1-D) chain with a repeat of [Si2O6]4- is well preserved in anhydrous jadeite melt at low pressures. However, the 1-D chains are nonlinear and the silicate tetrahedral units are very distorted. We also note that in the hydrous jadeite melt, the dominant hydrogen bearing species are hydroxyl (OH) and water molecules (H2O). We do not find any evidence of OH attached to the bridging oxygen atoms. However, we do find OH groups attached to the non-bridging oxygen atoms at the terminal sites of the tetrahedral units associated with the distorted 1-D chains. It is possible that these terminal OH groups were former bridging oxygen atoms. Pressure-volume-temperature results of hydrous jadeite melt could be adequately described with a finite-strain equation of state with ρ0, K0, and K'0 being 2.0 g/cm3, 13.0 GPa, and 4.0, respectively. Our FPMD results also indicate that the diffusivity of alkali (Na) ions is comparable to the hydrogen atoms at lower pressures ( 90 ×10-10 m2/s at 6 GPa and 2500 K). The self diffusion of aluminum (6.5 ×10-10 m2/s) and silicon (4.5 ×10-10 m2/s) ions are significantly lower compared to the alkali ions and proton at the similar P-T condition. At higher pressures i.e., P> 20 GPa, the diffusivity of Na reduces significantly. At P> 20 GPa, the proton diffusivity remains higher than the other cation species. Therefore, a small fraction of hydrous melt at mantle transition zone conditions may explain the observed elevated electrical conductivity in specific regions such as in Japan and in

  18. Tellurium content of marine manganese oxides and other manganese oxides

    USGS Publications Warehouse

    Lakin, H.W.; Thompson, C.E.; Davidson, D.F.

    1963-01-01

    Tellurium in amounts ranging from 5 to 125 parts per million was present in all of 12 samples of manganese oxide nodules from the floor of the Pacific and Indian oceans. These samples represent the first recognized points of high tellurium concentration in a sedimentary cycle. The analyses may lend support to the theory that the minor-element content of seafloor manganese nodules is derived from volcanic emanations.

  19. Effect of quantity and route of administration of manganese monoxide on feed intake and serum manganese in ruminants

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Black, J.R.; Ammerman, C.B.; Henry, P.R.

    1985-02-01

    The experiment investigated effects of high quantities of manganese and route of administration (diet versus capsule-dosed) on feed intake and blood characteristics in sheep. Twenty-four Florida native or Florida native by St. Croix crossbred wethers, 47 kg initially, were assigned randomly to eight treatments including basal diet supplemented with 0, 3000, 6000, or 9000 ppm manganese as a reagent grade manganese monoxide or basal diet plus gelatin capsules containing the equivalent of 0, 3000, 6000, or 9000 ppm manganese based on intake of the previous day. Three sheep per treatment were provided feed and tap water for ad libitum intake.more » Sheep were fed basal diet for 7 days followed by a 21-day experimental period, then placed back on the basal diet for 7 days. Average daily feed intake was reduced by increasing supplemental manganese, regardless of route. Animals dosed by capsule consumed less feed than those administered manganese in the diet. Serum manganese increased as manganese supplementation increased, but route of administration had no effect.« less

  20. Nanosized solvent superstructures in ultramolecular aqueous dilutions: twenty years' research using water proton NMR relaxation.

    PubMed

    Demangeat, Jean-Louis

    2013-04-01

    proton nuclear magnetic resonance (NMR) relaxation times T1, T2, T1/T2 are sensitive to motion and organization of water molecules. Especially, increase in T1/T2 reflects a higher degree of structuring. My purpose was to look at physical changes in water in ultrahigh aqueous dilutions. Samples were prepared by iterative centesimal (c) dilution with vigorous agitation, ranging between 3c and 24c (Avogadro limit 12c). Solutes were silica-lactose, histamine, manganese-lactose. Solvents were water, NaCl 0.15 M or LiCl 0.15 M. Solvents underwent strictly similar, simultaneous dilution/agitation, for each level of dilution, as controls. NMR relaxation was studied within 0.02-20 MHz. No changes were observed in controls. Increasing T1 and T1/T2 were found in dilutions, which persisted beyond 9c (manganese-lactose), 10c (histamine) and 12c (silica-lactose). For silica-lactose in LiCl, continuous decrease in T2 with increase in T1/T2 within the 12c-24c range indicated growing structuring of water despite absence of the initial solute. All changes vanished after heating/cooling. These findings were interpreted in terms of nanosized (>4-nm) supramolecular structures involving water, nanobubbles and ions, if any. Additional study of low dilutions of silica-lactose revealed increased T2 and decreased T1/T2 compared to solvent, within the 10(-3)-10(-6) range, reflecting transient solvent destructuring. This could explain findings at high dilution. Proton NMR relaxation demonstrated modifications of the solvent throughout the low to ultramolecular range of dilution. The findings suggested the existence of superstructures that originate stereospecifically around the solute after an initial destructuring of the solvent, developing more upon dilution and persisting beyond 12c. Copyright © 2013 The Faculty of Homeopathy. Published by Elsevier Ltd. All rights reserved.

  1. Formation of metallic and metal hydrous oxide dispersions

    NASA Technical Reports Server (NTRS)

    Matijevic, E.; Sapieszko, R. S.

    1979-01-01

    The formation, via hydrothermally induced precipitation from homogeneous solution, of a variety of well-defined dispersions of metallic and hydrous metal in the conditions under which the particles are produced (e.g., pH and composition of the growth medium, aging temperature, rate of heating, or degree of agitation) can be readily discerned by following changes in the mass, composition, and morphology of the final solid phase. The generation of colloidal dispersions in the absence of gravity convection or sedimentation effects may result in the appearance of morphological modifications not previously observed in terrestrially formed hydrosols.

  2. Hydrous iron oxide modified diatomite as an active filtration medium for phosphate capture.

    PubMed

    Wang, Zhe; Lin, Yan; Wu, Deyi; Kong, Hainan

    2016-02-01

    A simple method to functionalize diatomite with hydrous iron oxide was attempted and its performance as a new active filtration material to remove and recover phosphate from water was investigated under varying solution conditions. The Langmuir phosphate adsorption capacity increased from 0.6 mgP/g for raw diatomite to 4.89, 14.71, 25.02 mgP/g for hydrous iron oxide modified diatomite (HIOMD), depending on the amount of iron loaded. Loading of hydrous iron oxide caused the increase in true and bulk density and a decline in filtration rate, but to a lesser extent. It was shown that the HIOMD product with suitable iron content could retain a good filtration performance with a greatly increased adsorption capacity for phosphate. The phosphate adsorption increased by decreasing pH and by increasing ionic strength at high pH levels. The adsorption process was interpreted by ligand exchange. Coexisting oxyanions of sulfate, nitrate, citrate, carbonate, silicate and humic acid showed different effects on phosphate fixation but it was presumed that their influence at their concentrations and pH levels commonly encountered in effluent or natural waters was limited, i.e., HIOMD had a reasonably good selectivity. Results in repeated adsorption, desorption and regeneration experiment showed that the adsorbed phosphate could be recovered and the material could be reused after regeneration. The column test showed that HIOMD could be potentially utilized as an adsorption filtration medium for phosphate removal and recovery from water. Copyright © 2015 Elsevier Ltd. All rights reserved.

  3. Suppressing Manganese Dissolution from Lithium Manganese Oxide Spinel Cathodes with Single-Layer Graphene

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Jaber-Ansari, Laila; Puntambekar, Kanan P.; Kim, Soo

    2015-06-24

    Spinel-structured LiMn 2 O 4 (LMO) is a desirable cathode material for Li-ion batteries due to its low cost, abundance, and high power capability. However, LMO suffers from limited cycle life that is triggered by manganese dissolution into the electrolyte during electrochemical cycling. Here, it is shown that single-layer graphene coatings suppress manganese dissolution, thus enhancing the performance and lifetime of LMO cathodes. Relative to lithium cells with uncoated LMO cathodes, cells with graphene-coated LMO cathodes provide improved capacity retention with enhanced cycling stability. X-ray photoelectron spectroscopy reveals that graphene coatings inhibit manganese depletion from the LMO surface. Additionally, transmissionmore » electron microscopy demonstrates that a stable solid electrolyte interphase is formed on graphene, which screens the LMO from direct contact with the electrolyte. Density functional theory calculations provide two mechanisms for the role of graphene in the suppression of manganese dissolution. First, common defects in single-layer graphene are found to allow the transport of lithium while concurrently acting as barriers for manganese diffusion. Second, graphene can chemically interact with Mn 3+ at the LMO electrode surface, promoting an oxidation state change to Mn 4+ , which suppresses dissolution.« less

  4. Mechanism of selenite removal by a mixed adsorbent based on Fe-Mn hydrous oxides studied using X-ray absorption spectroscopy.

    PubMed

    Chubar, Natalia; Gerda, Vasyl; Szlachta, Małgorzata

    2014-11-18

    Selenium cycling in the environment is greatly controlled by various minerals, including Mn and Fe hydrous oxides. At the same time, such hydrous oxides are the main inorganic ion exchangers suitable (on the basis of their chemical nature) to sorb (toxic) anions, separating them from water solutions. The mechanism of selenite adsorption by the new mixed adsorbent composed of a few (amorphous and crystalline) phases [maghemite, MnCO3, and X-ray amorphous Fe(III) and Mn(III) hydrous oxides] was studied by extended X-ray absorption fine structure (EXAFS) spectroscopy [supported by Fourier transform infrared (FTIR) and X-ray diffraction (XRD) data]. The complexity of the porous adsorbent, especially the presence of the amorphous phases of Fe(III) and Mn(III) hydrous oxides, is the main reason for its high selenite removal performance demonstrated by batch and column adsorption studies shown in the previous work. Selenite was bound to the material via inner-sphere complexation (via oxygen) to the adsorption sites of the amorphous Fe(III) and Mn(III) oxides. This anion was attracted via bidentate binuclear corner-sharing coordination between SeO3(2-) trigonal pyramids and both FeO6 and MnO6 octahedra; however, the adsorption sites of Fe(III) hydrous oxides played a leading role in selenite removal. The contribution of the adsorption sites of Mn(III) oxide increased as the pH decreased from 8 to 6. Because most minerals have a complex structure (they are seldom based on individual substances) of various crystallinity, this work is equally relevant to environmental science and environmental technology because it shows how various solid phases control cycling of chemical elements in the environment.

  5. 21 CFR 582.5455 - Manganese glycerophosphate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Manganese glycerophosphate. 582.5455 Section 582.5455 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED... Dietary Supplements 1 § 582.5455 Manganese glycerophosphate. (a) Product. Manganese glycerophosphate. (b...

  6. 21 CFR 582.5455 - Manganese glycerophosphate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Manganese glycerophosphate. 582.5455 Section 582.5455 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED... Dietary Supplements 1 § 582.5455 Manganese glycerophosphate. (a) Product. Manganese glycerophosphate. (b...

  7. 21 CFR 582.5455 - Manganese glycerophosphate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Manganese glycerophosphate. 582.5455 Section 582.5455 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED... Dietary Supplements 1 § 582.5455 Manganese glycerophosphate. (a) Product. Manganese glycerophosphate. (b...

  8. 21 CFR 582.5455 - Manganese glycerophosphate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Manganese glycerophosphate. 582.5455 Section 582.5455 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED... Dietary Supplements 1 § 582.5455 Manganese glycerophosphate. (a) Product. Manganese glycerophosphate. (b...

  9. 21 CFR 582.5455 - Manganese glycerophosphate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Manganese glycerophosphate. 582.5455 Section 582.5455 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED... Dietary Supplements 1 § 582.5455 Manganese glycerophosphate. (a) Product. Manganese glycerophosphate. (b...

  10. Thermal-maturity limit for primary thermogenic-gas generation from humic coals as determined by hydrous pyrolysis

    USGS Publications Warehouse

    Lewan, Michael; Kotarba, M.J.

    2014-01-01

    Hydrous-pyrolysis experiments at 360°C (680°F) for 72 h were conducted on 53 humic coals representing ranks from lignite through anthracite to determine the upper maturity limit for hydrocarbon-gas generation from their kerogen and associated bitumen (i.e., primary gas generation). These experimental conditions are below those needed for oil cracking to ensure that generated gas was not derived from the decomposition of expelled oil generated from some of the coals (i.e., secondary gas generation). Experimental results showed that generation of hydrocarbon gas ends before a vitrinite reflectance of 2.0%. This reflectance is equivalent to Rock-Eval maximum-yield temperature and hydrogen indices (HIs) of 555°C (1031°F) and 35 mg/g total organic carbon (TOC), respectively. At these maturity levels, essentially no soluble bitumen is present in the coals before or after hydrous pyrolysis. The equivalent kerogen atomic H/C ratio is 0.50 at the primary gas-generation limit and indicates that no alkyl moieties are remaining to source hydrocarbon gases. The convergence of atomic H/C ratios of type-II and -I kerogen to this same value at a reflectance of indicates that the primary gas-generation limits for humic coal and type-III kerogen also apply to oil-prone kerogen. Although gas generation from source rocks does not exceed vitrinite reflectance values greater than , trapped hydrocarbon gases can remain stable at higher reflectance values. Distinguishing trapped gas from generated gas in hydrous-pyrolysis experiments is readily determined by of the hydrocarbon gases when a -depleted water is used in the experiments. Water serves as a source of hydrogen in hydrous pyrolysis and, as a result, the use of -depleted water is reflected in the generated gases but not pre-existing trapped gases.

  11. Efficient determination of average valence of manganese in manganese oxides by reaction headspace gas chromatography.

    PubMed

    Xie, Wei-Qi; Gong, Yi-Xian; Yu, Kong-Xian

    2017-08-18

    This work investigates a new reaction headspace gas chromatographic (HS-GC) technique for efficient quantifying average valence of manganese (Mn) in manganese oxides. This method is on the basis of the oxidation reaction between manganese oxides and sodium oxalate under the acidic condition. The carbon dioxide (CO 2 ) formed from the oxidation reaction can be quantitatively analyzed by headspace gas chromatography. The data showed that the reaction in the closed headspace vial can be completed in 20min at 80°C. The relative standard deviation of this reaction HS-GC method in the precision testing was within 1.08%, the relative differences between the new method and the reference method (titration method) were no more than 5.71%. The new HS-GC method is automated, efficient, and can be a reliable tool for the quantitative analysis of average valence of manganese in the manganese oxide related research and applications. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Bioturbation and Manganese Cycling in Hemipelagic Sediments

    NASA Astrophysics Data System (ADS)

    Aller, R. C.

    1990-06-01

    The activities of infaunal macrobenthos have major influences on the types, rates and distributions of diagenetic reactions involving manganese in relatively carbon-rich deep-sea and nearshore sediments. In some non-sulphidic hemipelagic deposits of the eastern equatorial Pacific (Panama Basin) biogenic reworking drives internal cycles of manganese, which can apparently account for up to ca. 100% of organic carbon oxidation and reduction of O2 supplied (diffusively) to the sea floor. Heterotrophic (carbon-based) manganese reduction is stimulated by simultaneous mixing of reactive organic matter and manganese oxide into suboxic-anoxic deposits. In sulphidic sediments, biogenic reworking must also enhance a lithotrophic pathway (sulphur-based) pathway of manganese reduction by promoting contact of manganese oxides and iron sulphides. Particle reworking dramatically alters the balance between aerobic and anaerobic decomposition pathways, promoting the utilization of O2 in the reoxidaton of reduced metabolites rather than direct oxidation of carbon. Irrigated burrows create microenvironments, which increase manganese reduction-oxidation and deplete Mn2+ from deeper pore waters. This may increase net Mn2+ production rates by removal of metabolites and potential co-precipitants with Mn2+. The occurrence and geometry of manganese oxide encrusted biogenic structures imply specific adaptations of infauna to manganese based microbial activity in hemipelagic sediments like the Panama Basin.

  13. A subchronic toxicity study of elemental Nano-Se in Sprague-Dawley rats.

    PubMed

    Jia, X; Li, N; Chen, J

    2005-03-11

    The subchronic toxicity of Nano-Se was compared with selenite and high-selenium protein in rats. Groups of Sprague-Dawley rats (12 males and 12 females per group) were fed diets containing Nano-Se, selenite and high-selenium protein at concentrations of 0, 2, 3, 4 and 5 ppm Se, respectively, for 13 weeks. Clinical observations were made and body weight and food consumption were recorded weekly. At the end of the study, the rats were subjected to a full necropsy, blood samples were collected for hematology and clinical chemistry determination. Histopathological examination was performed on selected tissues. At the two higher doses (4 and 5 ppm Se), significant abnormal changes were found in body weight, hematology, clinical chemistry, relative organ weights and histopathology parameters. However, the toxicity was more pronounced in the selenite and high-selenium protein groups than the Nano-Se group. At the dose of 3 ppm Se, significant growth inhibition and degeneration of liver cells were found in the selenite and high-selenium protein groups. No changes attributable to administration of Nano-Se at the dose of 3 ppm Se were found. Taken together, the no-observed-adverse-effect level (NOAEL) of Nano-Se in male and female rats was considered to be 3 ppm Se, equivalent to 0.22 mg/kg bw/day for males and 0.33 mg/kg bw/day for females. On the other hand, the NOAELs of selenite and high-selenium protein in males and females were considered to be 2 ppm Se, equivalent to 0.14 mg/kg bw/day for males and 0.20 mg/kg bw/day for females. In addition, studies have shown that Nano-Se has a similar bioavailability in rat, and much less acute toxicity in mice compared with selenite. In conclusion, Nano-Se is less toxic than selenite and high-selenium protein in the 13-week rat study.

  14. Grain Refinement and Mechanical Properties of Cu–Cr–Zr Alloys with Different Nano-Sized TiCp Addition

    PubMed Central

    Zhang, Dongdong; Bai, Fang; Wang, Yong; Wang, Jinguo; Wang, Wenquan

    2017-01-01

    The TiCp/Cu master alloy was prepared via thermal explosion reaction. Afterwards, the nano-sized TiCp/Cu master alloy was dispersed by electromagnetic stirring casting into the melting Cu–Cr–Zr alloys to fabricate the nano-sized TiCp-reinforced Cu–Cr–Zr composites. Results show that nano-sized TiCp can effectively refine the grain size of Cu–Cr–Zr alloys. The morphologies of grain in Cu–Cr–Zr composites changed from dendritic grain to equiaxed crystal because of the addition and dispersion of nano-sized TiCp. The grain size decreased from 82 to 28 μm with the nano-sized TiCp content. Compared with Cu–Cr–Zr alloys, the ultimate compressive strength (σUCS) and yield strength (σ0.2) of 4 wt% TiCp-reinforced Cu–Cr–Zr composites increased by 6.7% and 9.4%, respectively. The wear resistance of the nano-sized TiCp-reinforced Cu–Cr–Zr composites increased with the increasing nano-sized TiCp content. The wear loss of the nano-sized TiCp-reinforced Cu–Cr–Zr composites decreased with the increasing TiCp content under abrasive particles. The eletrical conductivity of Cu–Cr–Zr alloys, 2% and 4% nano-sized TiCp-reinforced Cu–Cr–Zr composites are 64.71% IACS, 56.77% IACS and 52.93% IACS, respectively. PMID:28786937

  15. Bacterial manganese reduction and growth with manganese oxide as the sole electron acceptor

    NASA Technical Reports Server (NTRS)

    Myers, Charles R.; Nealson, Kenneth H.

    1988-01-01

    Microbes that couple growth to the reduction of manganese could play an important role in the biogeochemistry of certain anaerobic environments. Such a bacterium, Alteromonas putrefaciens MR-1, couples its growth to the reduction of manganese oxides only under anaerobic conditions. The characteristics of this reduction are consistent with a biological, and not an indirect chemical, reduction of manganese, which suggest that this bacterium uses manganic oxide as a terminal electron acceptor. It can also utilize a large number of other compounds as terminal electron acceptors; this versatility could provide a distinct advantage in environments where electron-acceptor concentrations may vary.

  16. Manganese recycling in the United States in 1998

    USGS Publications Warehouse

    Jones, Thomas S.

    2001-01-01

    This report describes the flow and processing of manganese within the U.S. economy in 1998 with emphasis on the extent to which manganese is recycled. Manganese was used mostly as an alloying agent in alloys in which it was a minor component. Manganese was recycled mostly within scrap of iron and steel. A small amount was recycled within aluminum used beverage cans. Very little manganese was recycled from materials being recovered specifically for their manganese content. For the United States in 1998, 218,000 metric tons of manganese was estimated to have been recycled from old scrap, of which 96% was from iron and steel scrap. Efficiency of recycling was estimated as 53% and recycling rate as 37%. Metallurgical loss of manganese was estimated to be about 1.7 times that recycled. This loss was mostly into slags from iron and steel production, from which recovery of manganese has yet to be shown economically feasible.

  17. [Comparative study of nanosized and microsized silicon dioxide on spermatogenesis function of male rats].

    PubMed

    Fan, Yi-Ou; Zhang, Ying-Hua; Zhang, Xiao-Peng; Liu, Bing; Ma, Yi-xin; Jin, Yi-he

    2006-09-01

    To compare the effects of nanosized and microsized silicon dioxide on spermatogenesis function of male rats exposed by inhalation. 45 male rats were randomly divided into control group and four experimental groups which were exposed by 100 mg/m3 or 300 mg/m3 nanosized and microsized silicon dioxide in inhalation chambers 2 hours every other day. Age-matched rats were exposed to room air with the same condition and served as controls. 65 days later, the testicular and epididymal viscera coefficients, the quantity and quality of sperm were examined and the histopathological assessment was done. The changes in biochemical parameters in serum and testes were also measured. Nanosized silicon dioxide could induce histopathological changes of testes in rats, and the effect was higher than that of microsized particles at the same concentration. Nanosized silicon dioxide could reduce the sperm counts of rats and the testicular LDH-C4 activities, increase MDA levels in the testes and the effect was higher than that of microsized particles at the same concentration. Nanosized silicon dioxide could lead to the reduction of sperm motility, testicular LDH-C4 activities and 8-hydroxydeoxyguanosine (8-OHdG) concentration in serum elevation in particles-exposed rats compared with the control animals, but there are no significant difference compared with that of microsized particles at the same concentration. The present findings suggest a different effect of impairment of sperm production and maturation induced by inhalation of nanosized and microsized silicon dioxide, and nanosized silicon dioxide exerted more severe reaction.

  18. Hydrous pyrolysis/oxidation process for in situ destruction of chlorinated hydrocarbon and fuel hydrocarbon contaminants in water and soil

    DOEpatents

    Knauss, Kevin G.; Copenhaver, Sally C.; Aines, Roger D.

    2000-01-01

    In situ hydrous pyrolysis/oxidation process is useful for in situ degradation of hydrocarbon water and soil contaminants. Fuel hydrocarbons, chlorinated hydrocarbons, polycyclic aromatic hydrocarbons, petroleum distillates and other organic contaminants present in the soil and water are degraded by the process involving hydrous pyrolysis/oxidation into non-toxic products of the degradation. The process uses heat which is distributed through soils and water, optionally combined with oxygen and/or hydrocarbon degradation catalysts, and is particularly useful for remediation of solvent, fuel or other industrially contaminated sites.

  19. Sound velocity of 23 Å phase (a new Al-bearing hydrous Mg-silicate) to 14 GPa

    NASA Astrophysics Data System (ADS)

    Cai, N.; Chen, T.; Qi, X.; Inoue, T.; Li, B.

    2016-12-01

    Dense hydrous phases are believed to play an important role in transporting water back into the deep interior of the Earth. Recently, a new Al-bearing hydrous Mg-silicate named 23 Å phase (ideal composition Mg11Al2Si4O16(OH)12) was reported (Cai et al., 2015), which could be a very important hydrous phase in subducting slab. Here for the first time we measured the compressional and shear wave velocities of this new hydrous phase under mantle pressures. The sample was synthesized at 10 GPa and 1000 ºC using the chemical mixture of stoichiometric as starting materials. The recovered sample was then crushed into fine powder and hot pressed at 10 GPa and 900 ºC for 3 hours. X-ray diffraction, density measurement, and SEM characterization indicated that the specimen is nearly a pure phase, 20 µm in grain size, with a bulk density of 3.004 g/cm3. The acoustic measurements were conducted in a 1000-ton uniaxial split-cylinder multi-anvil apparatus using ultrasonic interferometry techniques (Li et al., 1996) up to 14 GPa at room temperature. The pressures were determined in situ by using alumina buffer rod as a pressure marker (Wang et al., 2015). A dual-mode piezoelectric transducer enables us to measure P and S wave travel times simultaneously, which in turn allows for a precise determination of the sound velocities and elastic bulk and shear moduli at high pressures. Preliminary results suggest that the velocities, (especially for S wave) of this 23 Å phase are slower than that of phase A and most of the mantle minerals. These results may have important implications for understanding some localized low velocity zones in subduction zones. Cai, N., T. Inoue, K. Fujino, H. Ohfuji and H. Yurimoto (2015) A Possible New Al-bearing Hydrous Mg-silicate (23 Å phase) in the Deep Upper Mantle. Am Mineral. 100: 2330-2335. Li, B., I. Jackson, T. Gasparik, and R. C. Liebermann (1996), Elastic wave velocity measurement in multianvil apparatus to 10 GPa using ultrasonic

  20. XANES study on Fe, U and Th in hydrous melts at high temperature and pressure

    NASA Astrophysics Data System (ADS)

    Wilke, M.; Schmidt, C.; Farges, F.; Borchert, M.; Simionovici, A.; Hahn, M.

    2005-12-01

    Insight to the structural units of melts is an important key to model properties of magmas. The effect of water and pressure on the local structure around minor to trace elements in silicate melts was investigated at in-situ conditions. The study was performed using XANES spectroscopy and a diamond anvil-cell. This was done to characterize spurious effects observed on glasses that are potentially invoked by quenching [1] and to understand better the processes occurring during the quench. We present results of in-situ XANES measurements on iron, uranium and thorium in hydrous silicate melt up to 1 GPa and 700° C. In-situ XANES spectra were recorded at the ESRF (Grenoble, France), beamline ID 22, using a hydrothermal diamond anvil cell with a design optimized for such measurements [2], i.e. recesses on the front and the back-side of one of the diamond anvils that provide the possibility to collect spectra at relatively low energies (down to 7 keV) and relatively low concentrations (0.1-1 wt%). In-situ Fe K-edge XANES spectra of Fe(II) in hydrous haplogranitic melt at 700° C and 500 MPa suggests that the local structure around Fe in hydrous glass observed previously is probably due to ordering during the quench. Additionally, the XANES is very similar to in-situ spectra taken on Fe(II) in anhydrous haplogranitic melt at 1150° C and ambient pressure. This indicates that the combined effect of water and pressure (0-500 MPa range) does not influence drastically the local structure of Fe in this type of melt composition. In-situ LIII-edge XANES of U in hydrous haplogranitic melt (1 wt% U) at 700° C and 620 MPa show that, upon reduction, U precipitated as uraninite. This suggests a low amount of NBO's (to which tetravalent actinides preferentially bond [3]) in this water-saturated melt. In contrast, U-bearing (1000 ppm) hydrous sodium-tri-silicate melt shows the presence of U(IV) dissolved in the melt as 6-7 coordinated species, as in dry glasses [3]. Similar

  1. Manganese-enhanced magnetic resonance microscopy of mineralization

    USGS Publications Warehouse

    Chesnick, I.E.; Todorov, T.I.; Centeno, J.A.; Newbury, D.E.; Small, J.A.; Potter, K.

    2007-01-01

    Paramagnetic manganese (II) can be employed as a calcium surrogate to sensitize magnetic resonance microscopy (MRM) to the processing of calcium during bone formation. At high doses, osteoblasts can take up sufficient quantities of manganese, resulting in marked changes in water proton T1, T2 and magnetization transfer ratio values compared to those for untreated cells. Accordingly, inductively coupled plasma mass spectrometry (ICP-MS) results confirm that the manganese content of treated cell pellets was 10-fold higher than that for untreated cell pellets. To establish that manganese is processed like calcium and deposited as bone, calvaria from the skull of embryonic chicks were grown in culture medium supplemented with 1 mM MnCl2 and 3 mM CaCl2. A banding pattern of high and low T2 values, consistent with mineral deposits with high and low levels of manganese, was observed radiating from the calvarial ridge. The results of ICP-MS studies confirm that manganese-treated calvaria take up increasing amounts of manganese with time in culture. Finally, elemental mapping studies with electron probe microanalysis confirmed local variations in the manganese content of bone newly deposited on the calvarial surface. This is the first reported use of manganese-enhanced MRM to study the process whereby calcium is taken up by osteoblasts cells and deposited as bone. ?? 2007 Elsevier Inc. All rights reserved.

  2. Grain Refinement and Mechanical Properties of Cu-Cr-Zr Alloys with Different Nano-Sized TiCp Addition.

    PubMed

    Zhang, Dongdong; Bai, Fang; Wang, Yong; Wang, Jinguo; Wang, Wenquan

    2017-08-08

    The TiC p /Cu master alloy was prepared via thermal explosion reaction. Afterwards, the nano-sized TiC p /Cu master alloy was dispersed by electromagnetic stirring casting into the melting Cu-Cr-Zr alloys to fabricate the nano-sized TiC p -reinforced Cu-Cr-Zr composites. Results show that nano-sized TiC p can effectively refine the grain size of Cu-Cr-Zr alloys. The morphologies of grain in Cu-Cr-Zr composites changed from dendritic grain to equiaxed crystal because of the addition and dispersion of nano-sized TiC p . The grain size decreased from 82 to 28 μm with the nano-sized TiC p content. Compared with Cu-Cr-Zr alloys, the ultimate compressive strength (σ UCS ) and yield strength (σ 0.2 ) of 4 wt% TiC p -reinforced Cu-Cr-Zr composites increased by 6.7% and 9.4%, respectively. The wear resistance of the nano-sized TiCp-reinforced Cu-Cr-Zr composites increased with the increasing nano-sized TiCp content. The wear loss of the nano-sized TiC p -reinforced Cu-Cr-Zr composites decreased with the increasing TiC p content under abrasive particles. The eletrical conductivity of Cu-Cr-Zr alloys, 2% and 4% nano-sized TiCp-reinforced Cu-Cr-Zr composites are 64.71% IACS, 56.77% IACS and 52.93% IACS, respectively.

  3. 21 CFR 184.1446 - Manganese chloride.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Manganese chloride. 184.1446 Section 184.1446 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR... Specific Substances Affirmed as GRAS § 184.1446 Manganese chloride. (a) Manganese chloride (MnCl2·4H2O, CAS...

  4. Isotopic evidence for organic matter oxidation by manganese reduction in the formation of stratiform manganese carbonate ore

    USGS Publications Warehouse

    Okita, P.M.; Maynard, J.B.; Spiker, E. C.; Force, E.R.

    1988-01-01

    Unlike other marine-sedimentary manganese ore deposits, which are largely composed of manganese oxides, the primary ore at Molango (Hidalgo State, Mexico) is exclusively manganese carbonate (rhodochrosite, Mn-calcite, kutnahorite). Stable isotope studies of the carbonates from Molango provide critical new information relevant to the controversy over syngenetic and diagenetic models of stratiform manganese deposit formation. Negative ??13C values for carbonates from mineralized zones at Molango are strongly correlated with manganese content both on a whole rock scale and by mineral species. Whole rock ??13C data fall into three groups: high-grade ore = -16.4 to -11.5%.; manganese-rich, sub-ore-grade = -5.2 to 0%.; and unmineralized carbonates = 0 to +2.5%. (PDB). ??18O data show considerable overlap in values among the three groups: +4.8 to -2.8, -5.4 to -0.3%., and -7.4 to +6.2 (PDB), respectively. Isotopic data for individual co-existing minerals suggest a similar separation of ??13C values: ??13C values from calcite range from -1.1 to +0.7%. (PDB), whereas values from rhodochrosite are very negative, -12.9 to -5.5%., and values from kutnahorite or Mn-calcite are intermediate between calcite and rhodochrosite. 13C data are interpreted to indicate that calcite (i.e. unmineralized carbonate) formed from a normal marine carbon reservoir. However, 13C data for the manganese-bearing carbonates suggest a mixed seawater and organic source of carbon. The presence of only trace amounts of pyrite suggests sulfate reduction may have played a minor part in oxidizing organic matter. It is possible that manganese reduction was the predominant reaction that oxidized organic matter and that it released organic-derived CO2 to produce negative ??13C values and manganese carbonate mineralization. ?? 1988.

  5. Analysis of Mineral Assemblages Containing Unstable Hydrous Phases

    NASA Astrophysics Data System (ADS)

    Vaniman, D. T.; Wilson, S. A.; Bish, D. L.; Chipera, S.

    2011-12-01

    Minerals in many environments can be treated as durable phases that preserve a record of their formation. However many minerals, especially those with hydrogen-bonded H2O molecules as part of their structure, are ephemeral and are unlikely to survive disturbance let alone removal from their environment of formation. Minerals with exceptionally limited stability such as meridianiite (Mg-sulfate 11 hydrate), ikaite (Ca-carbonate 6 hydrate), and mirabilite (Na-sulfate 10 hydrate) are very susceptible to destabilization during analysis, and even modest changes in temperature or relative humidity can lead to change in hydration state or deliquescence. The result may be not only loss of the salt hydrate but dissolution of other salts present, precipitation of new phases, and ion exchange between the concentrated solution and otherwise unaffected phases. Exchange of H2O molecules can also occur in solid-vapor systems without any liquid involvement; moreover, recent work has shown that cation exchange between smectite and sulfate hydrates can occur without any liquid phase present other than a presumed thin film at the salt-silicate interface. Among hydrous silicates, clay minerals are susceptible to cation exchange and similar alteration can be expected for zeolites, palagonite, and possibly other hydrous silicate alteration products. Environmentally sensitive phases on Mars, such as meridianiite, may occur at higher latitudes or in the subsurface where permafrost may be present. Accurate determination of the presence and paragenesis of such minerals will be important for understanding the near-surface hydrogeology of Mars, and in situ analysis may be the only way to obtain this information. Access to the subsurface may be required, yet the act of exposure by excavation or drilling can itself lead to rapid degradation as the sample is exposed or brought to the surface for analysis. Mars is not the only body with which to be concerned, for similar concerns can be raised

  6. Creation of deep blue light emitting nitrogen-vacancy center in nanosized diamond

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Himics, L., E-mail: himics.laszlo@wigner.mta.hu; Tóth, S.; Veres, M.

    2014-03-03

    This paper reports on the formation of complex defect centers related to the N3 center in nanosized diamond by employing plasma immersion and focused ion beam implantation methods. He{sup +} ion implantation into nanosized diamond “layer” was performed with the aim of creating carbon atom vacancies in the diamond structure, followed by the introduction of molecular N{sub 2}{sup +} ion and heat treatment in vacuum at 750 °C to initiate vacancy diffusion. To decrease the sp{sup 2} carbon content of nanosized diamond formed during the implantation processes, a further heat treatment at 450 °C in flowing air atmosphere was used. The modificationmore » of the bonding properties after each step of defect creation was monitored by Raman scattering measurements. The fluorescence measurements of implanted and annealed nanosized diamond showed the appearance of an intensive and narrow emission band with fine structures at 2.98 eV, 2.83 eV, and 2.71 eV photon energies.« less

  7. Prolactin levels in manganese-exposed male welders.

    PubMed

    Tutkun, Engin; Abuşoğlu, Sedat; Yılmaz, Hinç; Gündüzöz, Meşide; Gıynas, Nilgün; Bal, Ceylan Demir; Ünlü, Ali

    2014-12-01

    Early studies on manganese (Mn) exposure have demonstrated that this transition metal affects dopamine neurotransmission. Dopamine serves as a tonic inhibitor of prolactin release in the anterior hypophysis. Our aim was to determine the relation between serum prolactin levels and manganese-exposure. Whole blood was collected from 95 non-exposed control subjects and 179 manganese-exposed male welders. Whole blood manganese was analyzed by Inductively Coupled Plasma--Mass Spectrometer on Agilent 7700 (Agilent Technologies, USA). Serum prolactin levels (PRL), aspartate transaminase (AST), alanine transaminase (ALT), urea, creatinine, soduim (Na), potassium (K) were analyzed by immunological and spectrophotometric methods on Roche E170 Modular System (Roche Diagnostics, Mannheim, Germany). The mean ages for control and manganese-exposed group were 40.5 ± 7.8 and 39.5 ± 8.7, respectively (p = 0.258). The mean working period (years) for control and manganese-exposed group were 17.4 ± 9.8 and 18.2 ± 7.7 years, respectively (p = 0.581). Serum AST and potassium levels were significantly higher in control group than manganese-exposed group (p = 0.002 and p = 0.048, respectively) and body-mass index (BMI) was significantly lower in control group than manganese-exposed group (p = 0.033). There was a significantly positive correlation between whole blood manganese levels and serum prolactin (r = 0.860, p < 0.001). Serum ALT levels were positively correlated with serum AST, urea and sodium (r = 0.315, p < 0.001; r = 0.121, p = 0.046; r = 0.130, p = 0.031). Serum prolactin level is a diagnostic marker for determining the effect of manganese-exposure.

  8. 21 CFR 184.1461 - Manganese sulfate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Manganese sulfate. 184.1461 Section 184.1461 Food... GRAS § 184.1461 Manganese sulfate. (a) Manganese sulfate (MnSO4·H2O, CAS Reg. No. 7785-0987-097) is a... of pyrolusite (MnO2) ore with solid ferrous sulfate and coal, followed by leaching and...

  9. 21 CFR 184.1461 - Manganese sulfate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Manganese sulfate. 184.1461 Section 184.1461 Food... Specific Substances Affirmed as GRAS § 184.1461 Manganese sulfate. (a) Manganese sulfate (MnSO4·H2O, CAS... dioxide in sulfuric acid, and the roasting of pyrolusite (MnO2) ore with solid ferrous sulfate and coal...

  10. 21 CFR 184.1461 - Manganese sulfate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Manganese sulfate. 184.1461 Section 184.1461 Food... Specific Substances Affirmed as GRAS § 184.1461 Manganese sulfate. (a) Manganese sulfate (MnSO4·H2O, CAS... dioxide in sulfuric acid, and the roasting of pyrolusite (MnO2) ore with solid ferrous sulfate and coal...

  11. Manganese As a Metal Accumulator

    EPA Science Inventory

    Manganese deposits in water distribution systems accumulate metals, radionuclides and oxyanions by a combination of surface complexation, adsorption and solid substitution, as well as a combination of oxidation followed by manganese reduction and sorption of the oxidized constitu...

  12. Autonomic function in manganese alloy workers

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Barrington, W.W.; Angle, C.R.; Willcockson, N.K.

    1998-07-01

    The observation of orthostatic hypotension in an index case of manganese toxicity lead to this prospective attempt to evaluate cardiovascular autonomic function and cognitive and emotional neurotoxicity in eight manganese alloy welders and machinists. The subjects consisted of a convenience sample consisting of an index case of manganese dementia, his four co-workers in a frog shop for gouging, welding, and grinding repair of high manganese railway track and a convenience sample of three mild steel welders with lesser manganese exposure also referred because of cognitive or autonomic symptoms. Frog shop air manganese samples 9.6--10 years before and 1.2--3.4 years aftermore » the diagnosis of the index case exceeded 1.0 mg/m{sup 3} in 29% and 0.2 mg/m{sup 3} in 62%. Twenty-four-hour electrocardiographic (Holter) monitoring was used to determine the temporal variability of the heartrate (RR{prime} interval) and the rates of change at low frequency and high frequency. MMPI and MCMI personality assessment and short-term memory, figure copy, controlled oral word association, and symbol digit tests were used.« less

  13. Raman and IR Spectroscopic Study of Hydrous Pyroxenes

    NASA Astrophysics Data System (ADS)

    Kung, J.; Li, C.; Stalder, R.; Inoue, T.; Chuang, S.; Balfan-Casanova, N.; Skogby, H.

    2017-12-01

    Pyroxene group is one of major composed minerals at upper mantle and is nominally anhydrous mineral (NAM), in terms of its crystal chemistry. The analysis of field specimens showed the mantle-derived pyroxene phase containing some amount of hydrogen within crystal structure, the major incorporation mechanism to be as hydroxyl, OH¯, which chemical component treats as `water', H2O. Compared with the other mantle-derived olivine and garnet, the crystal chemistry of pyroxene phases (opx and cpx) is more complex that can result in different OH¯ bonding environments that would greatly affect the geophysics-interested physical properties, for example, elasticity and transport properties. In order to understand how the hydroxyl bonding condition with different composition of opx and cpx in this study, IR and Raman spectroscopies were employed to investigate the lattice modes and hydroxyl-bonding environments with different composition and crystal structures. The studied pyroxene specimens included natural hydrous pyroxenes and synthesized hydrous orthoenstatite (OEN) at high pressure and temperature (4-7 GPa, 1300-1400°C). The measured IR band range was carried out from 2800 to 3600 cm-1 and the Raman range from 50 to 3600 cm-1. The analysis showed that the band of 3600 cm-1 is the major feature in natural opx specimens but its intensity would be varied in different crystal orientation. For synthesized OEN, the number of observed IR band is higher than that reported in previous studies. The common major bands observed in natural cpx are around 3500 cm-1. The Raman measurement of studied specimen is to characterize the variation of Raman mode as function of composition and possible Raman active hydroxyl-related modes. In this meeting the results will be presented and discussed.

  14. Facile N...N coupling of manganese(V) imido species.

    PubMed

    Yiu, Shek-Man; Lam, William W Y; Ho, Chi-Ming; Lau, Tai-Chu

    2007-01-31

    (Salen)manganese(V) nitrido species are activated by electrophiles such as trifluoroacetic anhydride (TFAA) or trifluoroacetic acid (TFA) to produce N2. Mechanistic studies suggest that the manganese(V) nitrido species first react with TFAA or TFA to produce an imido species, which then undergoes N...N coupling. It is proposed that the resulting manganese(III) mu-diazene species decomposes via internal redox to give N2 and manganese(II). The manganese(II) species is then rapidly oxidized by manganese(V) imide to give manganese(III) and CF3CONH2 (for TFAA) or NH3 (for TFA).

  15. Plasticity of the dense hydrous magnesium silicate phase A at subduction zones conditions

    DOE PAGES

    Gouriet, K.; Hilairet, N.; Amiguet, E.; ...

    2015-09-12

    The plasticity of the dense hydrous magnesium silicate (DHMS) phase A, a key hydrous mineral within cold subduction zones, was investigated by two complementary approaches: high-pressure deformation experiments and computational methods. The deformation experiments were carried out at 11 GPa, 400 and 580 °C, with in situ measurements of stress, strain and lattice preferred orientations (LPO). Based on viscoplastic self-consistent modeling (VPSC) of the observed LPO, the deformation mechanisms at 580 °C are consistent with glide on the (0 0 0 1) basal and prismatic planes. At 400 °C the deformation mechanisms involve glide on prismatic, (0 0 0 1)more » basal and pyramidal planes. Both give flow stresses of 2.5–3 GPa at strain rates of 2–4 × 10-5 s-1. We use the Peierls–Nabarro–Galerkin (PNG) approach, relying on first-principles calculations of generalized stacking fault (γ-surface), and model the core structure of potential dislocations in basal and prismatic planes. The computations show multiple dissociations of the and dislocations (⟨a⟩ and ⟨b⟩ dislocations) in the basal plane, which is compatible with the ubiquity of basal slip in the experiments. The γ-surface calculations also suggest and dislocations (⟨a+c⟩ or ⟨c-b⟩ directions) in prismatic and pyramidal planes, which is also consistent with the experimental data. Phase A has a higher flow strength than olivine. When forming at depths from the dehydration of weak and highly anisotropic hydrated ultramafic rocks, phase A may not maintain the mechanical softening antigorite can provide. The seismic properties calculated for moderately deformed aggregates suggest that S-wave seismic anisotropy of phase A-bearing rocks is lower than hydrous subduction zone lithologies such as serpentinites and blueschists.« less

  16. Methane production by treating vinasses from hydrous ethanol using a modified UASB reactor

    PubMed Central

    2012-01-01

    Background A modified laboratory-scale upflow anaerobic sludge blanket (UASB) reactor was used to obtain methane by treating hydrous ethanol vinasse. Vinasses or stillage are waste materials with high organic loads, and a complex composition resulting from the process of alcohol distillation. They must initially be treated with anaerobic processes due to their high organic loads. Vinasses can be considered multipurpose waste for energy recovery and once treated they can be used in agriculture without the risk of polluting soil, underground water or crops. In this sense, treatment of vinasse combines the elimination of organic waste with the formation of methane. Biogas is considered as a promising renewable energy source. The aim of this study was to determine the optimum organic loading rate for operating a modified UASB reactor to treat vinasse generated in the production of hydrous ethanol from sugar cane molasses. Results The study showed that chemical oxygen demand (COD) removal efficiency was 69% at an optimum organic loading rate (OLR) of 17.05 kg COD/m3-day, achieving a methane yield of 0.263 m3/kg CODadded and a biogas methane content of 84%. During this stage, effluent characterization presented lower values than the vinasse, except for potassium, sulfide and ammonia nitrogen. On the other hand, primers used to amplify the 16S-rDNA genes for the domains Archaea and Bacteria showed the presence of microorganisms which favor methane production at the optimum organic loading rate. Conclusions The modified UASB reactor proposed in this study provided a successful treatment of the vinasse obtained from hydrous ethanol production. Methanogen groups (Methanobacteriales and Methanosarcinales) detected by PCR during operational optimum OLR of the modified UASB reactor, favored methane production. PMID:23167984

  17. Methane production by treating vinasses from hydrous ethanol using a modified UASB reactor.

    PubMed

    España-Gamboa, Elda I; Mijangos-Cortés, Javier O; Hernández-Zárate, Galdy; Maldonado, Jorge A Domínguez; Alzate-Gaviria, Liliana M

    2012-11-21

    A modified laboratory-scale upflow anaerobic sludge blanket (UASB) reactor was used to obtain methane by treating hydrous ethanol vinasse. Vinasses or stillage are waste materials with high organic loads, and a complex composition resulting from the process of alcohol distillation. They must initially be treated with anaerobic processes due to their high organic loads. Vinasses can be considered multipurpose waste for energy recovery and once treated they can be used in agriculture without the risk of polluting soil, underground water or crops. In this sense, treatment of vinasse combines the elimination of organic waste with the formation of methane. Biogas is considered as a promising renewable energy source. The aim of this study was to determine the optimum organic loading rate for operating a modified UASB reactor to treat vinasse generated in the production of hydrous ethanol from sugar cane molasses. The study showed that chemical oxygen demand (COD) removal efficiency was 69% at an optimum organic loading rate (OLR) of 17.05 kg COD/m3-day, achieving a methane yield of 0.263 m3/kg CODadded and a biogas methane content of 84%. During this stage, effluent characterization presented lower values than the vinasse, except for potassium, sulfide and ammonia nitrogen. On the other hand, primers used to amplify the 16S-rDNA genes for the domains Archaea and Bacteria showed the presence of microorganisms which favor methane production at the optimum organic loading rate. The modified UASB reactor proposed in this study provided a successful treatment of the vinasse obtained from hydrous ethanol production.Methanogen groups (Methanobacteriales and Methanosarcinales) detected by PCR during operational optimum OLR of the modified UASB reactor, favored methane production.

  18. Influence of acetazolamide loading on the (in vitro) performances of non-phospholipid-based cationic nanosized emulsion in comparison with phospholipid-based anionic and neutral-charged nanosized emulsions.

    PubMed

    Tamilvanan, Shunmugaperumal; Kumar, Balakrishnan Ajith

    2011-09-01

    Acetazolamide (ACZM)-loaded anionic, cationic, and neutral-charged oil-in-water nanosized emulsions were prepared and compared with their mean droplet diameter, surface charge, entrapment efficiency, freeze-thaw cycling stability, in vitro drug release, and transcorneal permeation. The present study aims to determine the influence of ACZM loading on the performances of non-phospholipid-based cationic nanosized emulsion in comparison with phospholipid-based anionic and neutral-charged nanosized emulsions. Regardless of charges, all of these emulsions exhibited a nanometer range mean particle diameter (240-443 nm) following autoclave sterilization. While the anionic and cationic emulsions did show high negative (-36.9 mV) and positive zeta potential (+41.4 mV) values, the neutral-charged emulsion did not. Presence of cryoprotectants (5% w/w sucrose + 5% w/w sorbitol) improved the stability of cationic emulsion to droplet aggregation during freeze-thaw cycling. The in vitro release kinetic behavior of drug exchange with physiological anions present in the simulated tear solution appears to be complex and difficult to characterize using mathematical fitting model equations. Augmentation in drug permeation through goat cornea, in vitro, was noticed for cationic emulsion. ACZM-loaded cationic nanosized emulsion could be suitable for topical application into eye to elicit better therapeutic effect in comparison with its anionic and neutral-charged emulsions.

  19. Manganese

    Integrated Risk Information System (IRIS)

    Manganese ; CASRN 7439 - 96 - 5 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Effect

  20. Direct Comparison of Manganese Detoxification/Efflux Proteins and Molecular Characterization of ZnT10 Protein as a Manganese Transporter*

    PubMed Central

    Nishito, Yukina; Tsuji, Natsuko; Fujishiro, Hitomi; Takeda, Taka-aki; Yamazaki, Tomohiro; Teranishi, Fumie; Okazaki, Fumiko; Matsunaga, Ayu; Tuschl, Karin; Rao, Rajini; Kono, Satoshi; Miyajima, Hiroaki; Narita, Hiroshi; Himeno, Seiichiro; Kambe, Taiho

    2016-01-01

    Manganese homeostasis involves coordinated regulation of specific proteins involved in manganese influx and efflux. However, the proteins that are involved in detoxification/efflux have not been completely resolved nor has the basis by which they select their metal substrate. Here, we compared six proteins, which were reported to be involved in manganese detoxification/efflux, by evaluating their ability to reduce manganese toxicity in chicken DT40 cells, finding that human ZnT10 (hZnT10) was the most significant contributor. A domain swapping and substitution analysis between hZnT10 and the zinc-specific transporter hZnT1 showed that residue Asn43, which corresponds to the His residue constituting the potential intramembranous zinc coordination site in other ZnT transporters, is necessary to impart hZnT10's unique manganese mobilization activity; residues Cys52 and Leu242 in transmembrane domains II and V play a subtler role in controlling the metal specificity of hZnT10. Interestingly, the His → Asn reversion mutant in hZnT1 conferred manganese transport activity and loss of zinc transport activity. These results provide important information about manganese detoxification/efflux mechanisms in vertebrate cells as well as the molecular characterization of hZnT10 as a manganese transporter. PMID:27226609

  1. Electrical conductivity of hydrous andesitic melts pertinent to subduction zones

    NASA Astrophysics Data System (ADS)

    Guo, Xuan; Li, Bin; Ni, Huaiwei; Mao, Zhu

    2017-03-01

    Andesitic magmatism and rocks are widespread at convergent plate boundaries. Electrically conductive bodies beneath subduction zone arc volcanoes, such as the Uturuncu Volcano, Bolivia, may correspond to active reservoirs of H2O-bearing andesitic magma. Laboratory measurements of electrical conductivity of hydrous andesitic melts are required to constrain the physicochemical conditions of these magma reservoirs in combination with magnetotelluric data. This experimental study investigates electrical conductivity of andesitic melts with 0.01-5.9 wt % of H2O at 1164-1573 K and 0.5-1.0 GPa in a piston cylinder apparatus using sweeping-frequency impedance spectroscopy. Electrical conductivity of andesitic melt increases with increasing temperature and H2O concentration but decreases with pressure. Across the investigated range of H2O concentration, electrical conductivity varies by 1.2-2.4 log units, indicating stronger influence of H2O for andesitic melt than for rhyolitic and dacitic melts. Using the Nernst-Einstein equation, the principal charge carrier is inferred to be Na in anhydrous melt but divalent cations in hydrous andesitic melts. The experimental data are regressed into a general electrical conductivity model for andesitic melt accounting for the pressure-temperature-H2O dependences altogether. Modeling results show that the conductive layer at >20 km depths beneath the surface of the Uturuncu Volcano could be interpreted by the presence of less than 20 vol % of H2O-rich andesitic melt (with 6-9 wt % H2O).

  2. Mineral of the month: manganese

    USGS Publications Warehouse

    Corathers, Lisa A.

    2005-01-01

    Manganese is one of the most important ferrous metals and one of the few for which the United States is totally dependent on imports. It is a black, brittle element predominantly used in metallurgical applications as an alloying addition, particularly in steel and cast iron production, which together provide the largest market for manganese (about 83 percent). It is also used as an alloy with nonferrous metals such as aluminum and copper. Nonmetallurgical applications of manganese include battery cathodes, soft ferrite magnets used in electronics, micronutrients found in fertilizers and animal feed, water treatment chemicals, and a colorant for bricks and ceramics.

  3. Soil manganese enrichment from industrial inputs: a gastropod perspective.

    PubMed

    Bordean, Despina-Maria; Nica, Dragos V; Harmanescu, Monica; Banatean-Dunea, Ionut; Gergen, Iosif I

    2014-01-01

    Manganese is one of the most abundant metal in natural environments and serves as an essential microelement for all living systems. However, the enrichment of soil with manganese resulting from industrial inputs may threaten terrestrial ecosystems. Several studies have demonstrated harmful effects of manganese exposure by cutaneous contact and/or by soil ingestion to a wide range of soil invertebrates. The link between soil manganese and land snails has never been made although these invertebrates routinely come in contact with the upper soil horizons through cutaneous contact, egg-laying, and feeding activities in soil. Therefore, we have investigated the direct transfer of manganese from soils to snails and assessed its toxicity at background concentrations in the soil. Juvenile Cantareus aspersus snails were caged under semi-field conditions and exposed first, for a period of 30 days, to a series of soil manganese concentrations, and then, for a second period of 30 days, to soils with higher manganese concentrations. Manganese levels were measured in the snail hepatopancreas, foot, and shell. The snail survival and shell growth were used to assess the lethal and sublethal effects of manganese exposure. The transfer of manganese from soil to snails occurred independently of food ingestion, but had no consistent effect on either the snail survival or shell growth. The hepatopancreas was the best biomarker of manganese exposure, whereas the shell did not serve as a long-term sink for this metal. The kinetics of manganese retention in the hepatopancreas of snails previously exposed to manganese-spiked soils was significantly influenced by a new exposure event. The results of this study reveal the importance of land snails for manganese cycling in terrestrial biotopes and suggest that the direct transfer from soils to snails should be considered when precisely assessing the impact of anthropogenic Mn releases on soil ecosystems.

  4. Soil Manganese Enrichment from Industrial Inputs: A Gastropod Perspective

    PubMed Central

    Bordean, Despina-Maria; Nica, Dragos V.; Harmanescu, Monica; Banatean-Dunea, Ionut; Gergen, Iosif I.

    2014-01-01

    Manganese is one of the most abundant metal in natural environments and serves as an essential microelement for all living systems. However, the enrichment of soil with manganese resulting from industrial inputs may threaten terrestrial ecosystems. Several studies have demonstrated harmful effects of manganese exposure by cutaneous contact and/or by soil ingestion to a wide range of soil invertebrates. The link between soil manganese and land snails has never been made although these invertebrates routinely come in contact with the upper soil horizons through cutaneous contact, egg-laying, and feeding activities in soil. Therefore, we have investigated the direct transfer of manganese from soils to snails and assessed its toxicity at background concentrations in the soil. Juvenile Cantareus aspersus snails were caged under semi-field conditions and exposed first, for a period of 30 days, to a series of soil manganese concentrations, and then, for a second period of 30 days, to soils with higher manganese concentrations. Manganese levels were measured in the snail hepatopancreas, foot, and shell. The snail survival and shell growth were used to assess the lethal and sublethal effects of manganese exposure. The transfer of manganese from soil to snails occurred independently of food ingestion, but had no consistent effect on either the snail survival or shell growth. The hepatopancreas was the best biomarker of manganese exposure, whereas the shell did not serve as a long-term sink for this metal. The kinetics of manganese retention in the hepatopancreas of snails previously exposed to manganese-spiked soils was significantly influenced by a new exposure event. The results of this study reveal the importance of land snails for manganese cycling in terrestrial biotopes and suggest that the direct transfer from soils to snails should be considered when precisely assessing the impact of anthropogenic Mn releases on soil ecosystems. PMID:24454856

  5. Selection and Use of Manganese Dioxide by Neanderthals

    PubMed Central

    Heyes, Peter J.; Anastasakis, Konstantinos; de Jong, Wiebren; van Hoesel, Annelies; Roebroeks, Wil; Soressi, Marie

    2016-01-01

    Several Mousterian sites in France have yielded large numbers of small black blocs. The usual interpretation is that these ‘manganese oxides’ were collected for their colouring properties and used in body decoration, potentially for symbolic expression. Neanderthals habitually used fire and if they needed black material for decoration, soot and charcoal were readily available, whereas obtaining manganese oxides would have incurred considerably higher costs. Compositional analyses lead us to infer that late Neanderthals at Pech-de-l’Azé I were deliberately selecting manganese dioxide. Combustion experiments and thermo-gravimetric measurements demonstrate that manganese dioxide reduces wood’s auto-ignition temperature and substantially increases the rate of char combustion, leading us to conclude that the most beneficial use for manganese dioxide was in fire-making. With archaeological evidence for fire places and the conversion of the manganese dioxide to powder, we argue that Neanderthals at Pech-de-l’Azé I used manganese dioxide in fire-making and produced fire on demand. PMID:26922901

  6. 21 CFR 582.5458 - Manganese hypophosphite.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5458 Manganese hypophosphite. (a) Product. Manganese hypophosphite. (b) Conditions of use...

  7. 21 CFR 582.5458 - Manganese hypophosphite.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5458 Manganese hypophosphite. (a) Product. Manganese hypophosphite. (b) Conditions of use...

  8. 21 CFR 582.5458 - Manganese hypophosphite.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5458 Manganese hypophosphite. (a) Product. Manganese hypophosphite. (b) Conditions of use...

  9. 21 CFR 582.5458 - Manganese hypophosphite.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5458 Manganese hypophosphite. (a) Product. Manganese hypophosphite. (b) Conditions of use...

  10. 21 CFR 582.5458 - Manganese hypophosphite.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5458 Manganese hypophosphite. (a) Product. Manganese hypophosphite. (b) Conditions of use...

  11. 21 CFR 582.5461 - Manganese sulfate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5461 Manganese sulfate. (a) Product. Manganese sulfate. (b) Conditions of use. This...

  12. 21 CFR 582.5449 - Manganese citrate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5449 Manganese citrate. (a) Product. Manganese citrate. (b) Conditions of use. This...

  13. 21 CFR 582.5449 - Manganese citrate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5449 Manganese citrate. (a) Product. Manganese citrate. (b) Conditions of use. This...

  14. 21 CFR 582.5461 - Manganese sulfate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5461 Manganese sulfate. (a) Product. Manganese sulfate. (b) Conditions of use. This...

  15. 21 CFR 582.5446 - Manganese chloride.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5446 Manganese chloride. (a) Product. Manganese chloride. (b) Conditions of use. This...

  16. 21 CFR 582.5452 - Manganese gluconate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5452 Manganese gluconate. (a) Product. Manganese gluconate. (b) Conditions of use. This...

  17. 21 CFR 582.5449 - Manganese citrate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5449 Manganese citrate. (a) Product. Manganese citrate. (b) Conditions of use. This...

  18. 21 CFR 582.5446 - Manganese chloride.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5446 Manganese chloride. (a) Product. Manganese chloride. (b) Conditions of use. This...

  19. 21 CFR 582.5461 - Manganese sulfate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5461 Manganese sulfate. (a) Product. Manganese sulfate. (b) Conditions of use. This...

  20. 21 CFR 582.5452 - Manganese gluconate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5452 Manganese gluconate. (a) Product. Manganese gluconate. (b) Conditions of use. This...

  1. 21 CFR 582.5461 - Manganese sulfate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5461 Manganese sulfate. (a) Product. Manganese sulfate. (b) Conditions of use. This...

  2. 21 CFR 582.5446 - Manganese chloride.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5446 Manganese chloride. (a) Product. Manganese chloride. (b) Conditions of use. This...

  3. 21 CFR 582.5452 - Manganese gluconate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5452 Manganese gluconate. (a) Product. Manganese gluconate. (b) Conditions of use. This...

  4. 21 CFR 582.5446 - Manganese chloride.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5446 Manganese chloride. (a) Product. Manganese chloride. (b) Conditions of use. This...

  5. 21 CFR 582.5449 - Manganese citrate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5449 Manganese citrate. (a) Product. Manganese citrate. (b) Conditions of use. This...

  6. 21 CFR 582.5452 - Manganese gluconate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5452 Manganese gluconate. (a) Product. Manganese gluconate. (b) Conditions of use. This...

  7. 21 CFR 582.5461 - Manganese sulfate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5461 Manganese sulfate. (a) Product. Manganese sulfate. (b) Conditions of use. This...

  8. 21 CFR 582.5452 - Manganese gluconate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5452 Manganese gluconate. (a) Product. Manganese gluconate. (b) Conditions of use. This...

  9. 21 CFR 582.5446 - Manganese chloride.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5446 Manganese chloride. (a) Product. Manganese chloride. (b) Conditions of use. This...

  10. 21 CFR 582.5449 - Manganese citrate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5449 Manganese citrate. (a) Product. Manganese citrate. (b) Conditions of use. This...

  11. Hydrous melt-rock reaction in the shallow mantle wedge

    NASA Astrophysics Data System (ADS)

    Mitchell, A.; Grove, T. L.

    2017-12-01

    In subduction zone magmatism, hotter, deeper hydrous mantle melts rise and interact with the shallower, cooler depleted mantle in the uppermost part of the mantle wedge. Here, we experimentally investigate these hydrous reactions using three different ratios of a 1.6 GPa mantle melt and an overlying 1.2 GPa harzburgite from 1060 to 1260 °C. At low ratios of melt/mantle (20:80 and 5:95), the crystallizing assemblages are dunites, harzburgites, and lherzolites (as a function of temperature). When the ratio of deeper melt to overlying mantle is 70:30, the crystallizing assemblage is a wehrlite. This shows that wehrlites, which are observed in ophiolites and mantle xenoliths, can be formed by large amounts of deeper melt fluxing though the mantle wedge during ascent. In all cases, orthopyroxene dissolves in the melt, and olivine crystallizes along with pyroxenes and spinel. The amount of reaction between deeper melts and overlying mantle, simulated here by the three starting compositions, imposes a strong influence on final melt compositions, particularly in terms of depletion. At the lowest melt/mantle ratios, the resulting melt is an extremely depleted Al-poor, high-Si andesite. As the fraction of melt to mantle increases, final melts resemble primitive basaltic andesites found in arcs globally. Wall rock temperature is a key variable; over a span of <80 °C, reaction with deeper melt creates the entire range of mantle lithologies from a depleted dunite to a harzburgite to a refertilized lherzolite. Together, the experimental phase equilibria, melt compositions, and calculated reaction coefficients provide a framework for understanding how melt-wall rock reaction occurs in the natural system during melt ascent in the mantle wedge.

  12. Electrical Conductivity Measurements on Hydrous Carbonate Melts at Mantle Pressure

    NASA Astrophysics Data System (ADS)

    Sifre, D.; Gaillard, F.

    2012-04-01

    Electromagnetic methods image mantle regions in the asthenosphere with elevated conductivity (0.1 to 1 S.m-1), which constrasts with the conductivity of dry olivine (10-2 to 10-3 S.m-1). A correct interpretation of the petrological nature of the conductive mantle is critical for our understanding of mantle geodynamics because such conductive regions indicate mantle rocks with physical and chemical properties that importantly deviates from the canonical peridotites. For decades, such anomalously high mantle conductivities have been attributed to mineralogical defects associated to few tens of ppm water incorporated in olivine. Most recent experimental surveys, however, refute this hydrous olivine model. Conductive mantle regions could then reflect partial melting. The presence of melts in the Earth's mantle has long been proved by geochemical observations and experimental petrology on peridotite rocks. The requirement for melting in the asthenospheric mantle is the presence of volatile species (water, carbon dioxide, halogens). Small melt fractions are then produced by small volatile contents and they are the first liquids produced by melting magma. This study reports electrical conductivity measurements on such melts at mantle pressure and temperature. We investigated on melt chemical compositions produced by melting of peridotite that would interact with CO2-H2O and Cl. Such melts are carbonatite melts, carbonated silicate melts, hydrous carbonate melts, hydrous basalts. A new system allowing in situ electrical conductivity measurements in piston cylinder has been deployed. This design has been specifically adapted to perfom measurements on liquid samples with elevated electrical conductivities. The chemical compositions investigated are pure liquid CaCO3 and CaMg(CO3)2, to which, cloride (as salts), silicate (as basalts) and water (as brucite) have been added. Experiments have been realized at 1.5 and 2.7 GPa pressure and temperature of 1000-1700° C. Impedance

  13. Methods for producing monodispersed particles of barium titanate

    DOEpatents

    Hu, Zhong-Cheng

    2001-01-01

    The present invention is a low-temperature controlled method for producing high-quality, ultrafine monodispersed nanocrystalline microsphere powders of barium titanate and other pure or composite oxide materials having particles ranging from nanosized to micronsized particles. The method of the subject invention comprises a two-stage process. The first stage produces high quality monodispersed hydrous titania microsphere particles prepared by homogeneous precipitation via dielectric tuning in alcohol-water mixed solutions of inorganic salts. Titanium tetrachloride is used as an inorganic salt precursor material. The second stage converts the pure hydrous titania microsphere particles into crystalline barium titanate microsphere powders via low-temperature, hydrothermal reactions.

  14. Nano-sized Adsorbate Structure Formation in Anisotropic Multilayer System

    NASA Astrophysics Data System (ADS)

    Kharchenko, Vasyl O.; Kharchenko, Dmitrii O.; Yanovsky, Vladimir V.

    2017-05-01

    In this article, we study dynamics of adsorbate island formation in a model plasma-condensate system numerically. We derive the generalized reaction-diffusion model for adsorptive multilayer system by taking into account anisotropy in transfer of adatoms between neighbor layers induced by electric field. It will be found that with an increase in the electric field strength, a structural transformation from nano-holes inside adsorbate matrix toward separated nano-sized adsorbate islands on a substrate is realized. Dynamics of adsorbate island sizes and corresponding distributions are analyzed in detail. This study provides an insight into details of self-organization of adatoms into nano-sized adsorbate islands in anisotropic multilayer plasma-condensate systems.

  15. Evaluation of PAN-based manganese dioxide composite for the sorptive removal of cesium-137 from aqueous solutions.

    PubMed

    Nilchi, A; Saberi, R; Garmarodi, S Rasouli; Bagheri, A

    2012-02-01

    Hydrous manganese dioxide-polyacrylonitrile (MnO(2)-PAN) was chemically synthesized and evaluated, as an organic-inorganic composite material, for the removal of radio-contaminant cesium-137 from aqueous solutions. The physico-chemical characterization was carried out by Fourier transform infrared spectroscopy (FT-IR), X-ray powder diffraction (XRD), CHN elemental analysis, scanning electron microscopy (SEM), nitrogen adsorption-desorption studies and thermogravimetry-differential scanning calorimetry (TGA-DSC). Batch experiments were carried out as a function of contact time, interference of the coexisting ions and initial pH of adsorptive solution applying a radiotracer technique. The effect of temperature on the distribution coefficient of cesium has been utilized in order to evaluate the changes in the standard thermodynamic parameters. The results indicated that Cs(+) ions could be efficiently removed using MnO(2)-PAN composite in the pH range of 4-9 from aqueous solutions and the uptake of cesium is affected to varying degrees by the presence of some diverse co-ions. The equilibrium isotherms have been determined and the sorption data were successfully modeled using Freundlich model. Copyright © 2011 Elsevier Ltd. All rights reserved.

  16. Globally sustainable manganese metal production and use.

    PubMed

    Hagelstein, Karen

    2009-09-01

    The "cradle to grave" concept of managing chemicals and wastes has been a descriptive analogy of proper environmental stewardship since the 1970s. The concept incorporates environmentally sustainable product choices-such as metal alloys utilized steel products which civilization is dependent upon. Manganese consumption is related to the increasing production of raw steel and upgrading ferroalloys. Nonferrous applications of manganese include production of dry-cell batteries, plant fertilizer components, animal feed and colorant for bricks. The manganese ore (high grade 35% manganese) production world wide is about 6 million ton/year and electrolytic manganese metal demand is about 0.7 million ton/year. The total manganese demand is consumed globally by industries including construction (23%), machinery (14%), and transportation (11%). Manganese is recycled within scrap of iron and steel, a small amount is recycled within aluminum used beverage cans. Recycling rate is 37% and efficiency is estimated as 53% [Roskill Metals and Minerals Reports, January 13, 2005. Manganese Report: rapid rise in output caused by Chinese crude steel production. Available from: http://www.roskill.com/reports/manganese.]. Environmentally sustainable management choices include identifying raw material chemistry, utilizing clean production processes, minimizing waste generation, recycling materials, controlling occupational exposures, and collecting representative environmental data. This paper will discuss two electrolytically produced manganese metals, the metal production differences, and environmental impacts cited to date. The two electrolytic manganese processes differ due to the addition of sulfur dioxide or selenium dioxide. Adverse environmental impacts due to use of selenium dioxide methodology include increased water consumption and order of magnitude greater solid waste generation per ton of metal processed. The use of high grade manganese ores in the electrolytic process also

  17. Role of bulk and Nanosized SiO2 to overcome salt stress during Fenugreek germination (Trigonella foenum- graceum L.).

    PubMed

    Ivani, Reihane; Sanaei Nejad, Seyed Hossein; Ghahraman, Bijan; Astaraei, Ali Reza; Feizi, Hassan

    2018-04-05

    The effects of bulk and Nanosized SiO 2 on seed germination and seedling growth indices of fenugreek under salinity stress were studied in the College of Agriculture, Ferdowsi University of Mashhad, Iran, in 2013. The experimental treatments included 4 levels of salinity stress (0, 50, 100 and 150 mM), 2 concentrations of bulk (50 and 100 ppm), 2 concentrations of nanosized SiO 2 (50 and 100 ppm), and control (without any SiO 2 types). Seedling growth attributes significantly improved when bulk and nanosized SiO 2 concentrations applied singly or with different levels of salt stress. However, they significantly declined with salt application. The adverse effects of salt on shoot, root and seedling lengths were alleviated by application of 50 ppm nanosized SiO 2 treatment. Under salt stress condition, addition of 50 and 100 ppm nanosized SiO 2 to fenugreek seeds increased shoot, root and seedling dry weights as compared to bulk SiO 2 concentrations and control treatments, though 50 ppm nanosized SiO 2 was more effective than 100 ppm nanosized SiO 2 application. It was concluded that nanosized SiO 2 improves growth attributes of fenugreek and mitigate adverse effects of salt stress.

  18. Nanostructured manganese oxides as highly active water oxidation catalysts: a boost from manganese precursor chemistry.

    PubMed

    Menezes, Prashanth W; Indra, Arindam; Littlewood, Patrick; Schwarze, Michael; Göbel, Caren; Schomäcker, Reinhard; Driess, Matthias

    2014-08-01

    We present a facile synthesis of bioinspired manganese oxides for chemical and photocatalytic water oxidation, starting from a reliable and versatile manganese(II) oxalate single-source precursor (SSP) accessible through an inverse micellar molecular approach. Strikingly, thermal decomposition of the latter precursor in various environments (air, nitrogen, and vacuum) led to the three different mineral phases of bixbyite (Mn2 O3 ), hausmannite (Mn3 O4 ), and manganosite (MnO). Initial chemical water oxidation experiments using ceric ammonium nitrate (CAN) gave the maximum catalytic activity for Mn2 O3 and MnO whereas Mn3 O4 had a limited activity. The substantial increase in the catalytic activity of MnO in chemical water oxidation was demonstrated by the fact that a phase transformation occurs at the surface from nanocrystalline MnO into an amorphous MnOx (1manganese oxides including the newly formed amorphous MnOx . Both Mn2 O3 and the amorphous MnOx exhibit tremendous enhancement in oxygen evolution during photocatalysis and are much higher in comparison to so far known bioinspired manganese oxides and calcium-manganese oxides. Also, for the first time, a new approach for the representation of activities of water oxidation catalysts has been proposed by determining the amount of accessible manganese centers. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Invasion of Hydrous Fluids Predates Kimberlite Formation

    NASA Astrophysics Data System (ADS)

    Kopylova, M. G.; Wang, Q.; Smith, E. M.

    2017-12-01

    Petrological observations on diamonds and peridotite xenoliths in kimberlites point towards an influx of hydrous metasomatic fluids shortly predating kimberlite formation. Diamonds may grow at different times within the same segment of the cratonic mantle, and diamonds that form shortly before (<5-7 My) the kimberlite entrainment host the more hydrous fluid inclusions. Younger fibrous diamonds typically contain 10-25 wt.% water in fluid inclusions, while older octahedrally-grown diamonds host "dry" N2-CO2 fluids. Our recent studies of fluids in diamond now show that many different kinds of diamonds can contain fluid inclusions. Specifically, we found a new way to observe and analyze fluids in octahedrally-grown, non-fibrous diamonds by examining healed fractures. This is a new textural context for fluid inclusions that reveals a valuable physical record of infiltrating mantle fluids, that postdate diamond growth, but equilibrate within the diamond stability field at depths beyond 150 km. Another sign of the aqueous fluids influx is the formation of distinct peridotite textures shortly predating the kimberlite. Kimberlites entrain peridotite xenoliths with several types of textures: older coarse metamorphic textures and younger, sheared textures. The preserved contrast in grain sizes between porphyroclasts and neoblasts in sheared peridotites constrain the maximum duration of annealing. Experimental estimates of the annealing time vary from 7x107 sec (2 years) to 106 years (1 My) depending on olivine hydration, strain rate, pressure, temperature and, ultimately, the annealing mechanism. Kimberlite sampling of sheared peridotites from the lithosphere- asthenosphere boundary (LAB) implies their formation no earlier than 1 My prior to the kimberlite ascent. Water contents of olivine measured by FTIR spectrometry using polarized light demonstrated contrasting hydration of coarse and sheared samples. Olivine from sheared peridotite samples has the average water content

  20. Development of nanosized silver-substituted apatite for biomedical applications: A review.

    PubMed

    Lim, Poon Nian; Chang, Lei; Thian, Eng San

    2015-08-01

    The favorable biocompatibility of hydroxyapatite (HA) makes it a popular bone graft material as well as a coating layer on metallic implant. To reduce implant-related infections, silver ions were either incorporated into the apatite during co-precipitation process (AgHA-CP) or underwent ion-exchange with the calcium ions in the apatite (AgHA-IE). However, the distribution of silver ions in AgHA-CP and AgHA-IE was different, thus affecting the antibacterial action. Several studies reported that nanosized AgHA-CP containing 0.5 wt.% of silver provided an optimal trade-off between antibacterial properties and cytotoxicity. Nevertheless, nanosized AgHA and AgHA nanocoatings could not function ideally due to the compromise in the bone differentiation of mesenchymal stem cells, as evidenced in the reduced alkaline phosphatase, type I collagen and osteocalcin. Preliminary studies showed that biological responses of nanosized AgHA and AgHA nanocoatings could be improved with the addition of silicon. This review will discuss on nanosized AgHA and AgHA nanocoatings. In many patients needing bone graft material, hydroxyapatite (HA) has proven to be a popular choice. Nonetheless, implant-related infections remain a major concern. Hence, effective preventive measures are needed. In this review article, the authors discussed the application of incorporating silver nanoparticles in HA and its use as bone graft biomaterials together with the addition of silica. Copyright © 2015 Elsevier Inc. All rights reserved.

  1. Evaluation of nanoselenium (Nano-Se) effect on hematological and serum biochemical parameters of rat in experimentally lead poisoning.

    PubMed

    Dehkordi, A Jafari; Mohebbi, A N; Aslani, M R; Ghoreyshi, S M

    2017-04-01

    The present study was designed to evaluate the effect of nanoselenium (Nano-Se) on hematological and biochemical parameters of rats experimentally intoxicated with lead (Pb). Thirty male rats were randomly divided into six groups as follows: the control, selenite, Nano-Se, Pb group, Pb + selenite, and Pb + Nano-Se groups. After 35 days, blood was collected from rats and hematology and serum biochemical parameters of oxidative stress were measured. The thiobarbituric acid reactive substances (TBARS) level of Pb group was significantly higher than other groups. Also, TBARS level was significantly lower in the Pb + Nano-Se group than Pb + selenite group. The serum superoxide dismutase activities were significantly lower in Pb group than the control, Pb + selenite, and Pb + Nano-Se groups. The catalase activities in the Pb group showed no significant change when compared to other groups. In the Pb group, packed cell volume was lower than the control group. A significant difference was observed between the control group and the Pb, Pb + selenite, and Pb + Nano-Se groups. In the Pb group, the numbers of white blood cell (WBC) decreased in comparison with the control group. Also, there was significant increase in WBC counts in the Pb + Nano-Se and Pb + selenite groups in comparison with Pb group. The number of lymphocytes in the Pb group decreased in comparison with the control group. By comparing the means of the Pb + Nano-Se and Pb + selenite groups together, it was determined that there were significant differences in the lymphocytes and neutrophil counts. In conclusion, usage of selenium compounds particularly Nano-Se particles inhibits the adverse effects of Pb on antioxidant activity and immune system function in the Pb poisoning.

  2. Ion-Selective Deposition of Manganese Sulphate Solution from Trenggalek Manganese Ore by Active Carbon and Sodium Hydroxide

    NASA Astrophysics Data System (ADS)

    Andriyah, L.; Sulistiyono, E.

    2017-02-01

    One of the step in manganese dioxide manufacturing process for battery industry is a purification process of lithium manganese sulphate solution. The elimination of impurities such as iron removal is important in hydrometallurgical processes. Therefore, this paper present the purification results of manganese sulphate solution by removing impurities using a selective deposition method, namely activated carbon adsorption and NaOH. The experimental results showed that the optimum condition of adsorption process occurs on the addition of 5 g adsorbent and the addition of 10 ml NaOH 1 N, processing time of 30 minutes and the best is the activated carbon adsorption of Japan. Because the absolute requirement of the cathode material of lithium ion manganese are free of titanium then of local wood charcoal is good enough in terms of eliminating ions Ti is equal to 70.88%.

  3. Reagent removal of manganese from ground water

    NASA Astrophysics Data System (ADS)

    Brayalovsky, G.; Migalaty, E.; Naschetnikova, O.

    2017-06-01

    The study is aimed at the technology development of treating drinking water from ground waters with high manganese content and oxidizability. Current technologies, physical/chemical mechanisms and factors affecting in ground treatment efficiency are reviewed. Research has been conducted on manganese compound removal from ground waters with high manganese content (5 ppm) and oxidizability. The studies were carried out on granular sorbent industrial ODM-2F filters (0.7-1.5 mm fraction). It was determined that conventional reagent oxidization technologies followed by filtration do not allow us to obtain the manganese content below 0.1 ppm when treating ground waters with high oxidizability. The innovative oxidation-based manganese removal technology with continuous introduction of reaction catalytic agent is suggested. This technology is effective in alkalization up to pH 8.8-9. Potassium permanganate was used as a catalytic agent, sodium hypochlorite was an oxidizer and cauistic soda served an alkalifying agent.

  4. Formation of hydrous Mg-silicates at low temperatures: New insights from sepiolite precipitation experiments

    NASA Astrophysics Data System (ADS)

    Baldermann, Andre; Mavromatis, Vasileios; Dietzel, Martin

    2017-04-01

    The spatiotemporal changes in the distribution and abundance of hydrous Mg-silicates have been frequently used to reconstruct sedimentary facies in modern and past epicontinental seas and lakes, lacustrine settings and in marine environments; albeit the physicochemical conditions and the mineral-forming processes of hydrous Mg-silicates remain questionable. In this experimental study, sepiolite [Mg4Si6O15(OH)2ṡ6H2O] was precipitated from silica-doped seawater and silica-doped synthetic MgCl2-brines over a three months period at aqueous Si/Mg molar ratios ranging from 1:27.5 to 1:110, initial pH of 8.3 ± 0.03 at 25 ± 1°C. The evolution of the solution chemistry and solid-phase composition was monitored using UV-vis spectroscopy, ICP-OES, XRD, ATR-FTIR and TEM analysis. The reactive fluids were, at any time, undersaturated in respect to amorphous silica [SiO2ṡnH2O] and brucite [Mg(OH)2]; thus, a Mg-rich phyllosilicate with a modulated, sepiolite-like structure was the only precipitates in our experiments. The crystallites were poorly crystalline, fibrous (20 to 100 nm in length) and had a (MgO+Al2O3)/SiO2 ratio of 0.44 ± 0.02, which is almost equal to that of ideal and naturally-grown sepiolite. An increase in the intensity of the striking infrared lattice vibration at ˜1205 cm-1 is in accord with an elevated Si/Mg molar ratio of the reactive solutions. This feature results from the periodic inversion of the Si tetrahedra in the evolving 2:1 layer and subsequently denotes the formation of "polysome units" in sepiolite-palygorskite group minerals. For the first time, we determined the apparent growth rate of sepiolite to be 172 ± 16 × 10-6 up to 279 ± 29 × 10-6 mole L-1ṡday-1, which mainly depended on the evolution of pH of the reactive fluids. The presence of MgSO40 aquo-complexes seems to have insignificant influence on the precipitation rate of sepiolite. Our results demonstrate that hydrous Mg-silicates can form in most (peri)marine and diagenetic

  5. A submerged ceramic membrane reactor for the p-nitrophenol hydrogenation over nano-sized nickel catalysts.

    PubMed

    Chen, R Z; Sun, H L; Xing, W H; Jin, W Q; Xu, N P

    2009-02-01

    The catalytic hydrogenation of p-nitrophenol to p-aminophenol over nano-sized nickel catalysts was carried out in a submerged ceramic membrane reactor. It has been demonstrated that the submerged ceramic membrane reactor is more suitable for the p-nitrophenol hydrogenation over nano-sized nickel catalysts compared with the side-stream ceramic membrane reactor, and the membrane module configuration has a great influence on the reaction rate of p-nitrophenol hydrogenation and the membrane treating capacity. The deactivation of nano-sized nickel is mainly caused by the adsorption of impurity on the surface of nickel and the increase of oxidation degree of nickel.

  6. Synthesis and characterization of nano-sized CaCO3 in purified diet

    NASA Astrophysics Data System (ADS)

    Mulyaningsih, N. N.; Tresnasari, D. R.; Ramahwati, M. R.; Juwono, A. L.; Soejoko, D. S.; Astuti, D. A.

    2017-07-01

    The growth and development of animals depend strongly on the balanced nutrition in the diet. This research aims is to characterize the weight variations of nano-sized calcium carbonate (CaCO3) in purified diet that to be fed to animal model of rat. The nano-sized CaCO3 was prepared by milling the calcium carbonate particles for 20 hours at a rotation speed of 1000 rpm and resulting particle size in a range of 2-50 nm. Nano-sized CaCO3 added to purified diet to the four formulas that were identified as normal diet (N), deficiency calcium (DC), rich in calcium (RC), and poor calcium (PC) with containing in nano-sized CaCO3 much as 0.50 %, 0.00 %, 0.75 % and 0.25 % respectively. The nutritional content of the purified diet was proximate analyzed, it resulted as followed moisture, ash, fat, protein, crude fiber. The quantities of chemical element were analyzed by atomic absorption spectrometry (AAS), it resulted iron, magnesium, potassium and calcium. The results showed that N diet (Ca: 16,914.29 ppm) were suggested for healthy rats and RC diet (Ca: 33,696.13 ppm) for conditioned osteoporosis rats. The crystalline phases of the samples that were examined by X-ray diffraction showed that crystalline phase increased with the increasing concentration of CaCO3.

  7. Manganese biomining: A review.

    PubMed

    Das, A P; Sukla, L B; Pradhan, N; Nayak, S

    2011-08-01

    Biomining comprises of processing and extraction of metal from their ores and concentrates using microbial techniques. Currently this is used by the mining industry to extract copper, uranium and gold from low grade ores but not for low grade manganese ore in industrial scale. The study of microbial genomes, metabolites and regulatory pathways provide novel insights to the metabolism of bioleaching microorganisms and their synergistic action during bioleaching operations. This will promote understanding of the universal regulatory responses that the biomining microbial community uses to adapt to their changing environment leading to high metal recovery. Possibility exists of findings ways to imitate the entire process during industrial manganese biomining endeavor. This paper reviews the current status of manganese biomining research operations around the world, identifies factors that drive the selection of biomining as a processing technology, describes challenges in exploiting these innovations, and concludes with a discussion of Mn biomining's future. Copyright © 2011 Elsevier Ltd. All rights reserved.

  8. Sulfur species in source rock bitumen before and after hydrous pyrolysis determined by X-ray absorption near-edge structure

    USGS Publications Warehouse

    Bolin, Trudy B.; Birdwell, Justin E.; Lewan, Michael; Hill, Ronald J.; Grayson, Michael B.; Mitra-Kirtley, Sudipa; Bake, Kyle D.; Craddock, Paul R.; Abdallah, Wael; Pomerantz, Andrew E.

    2016-01-01

    The sulfur speciation of source rock bitumen (chloroform-extractable organic matter in sedimentary rocks) was examined using sulfur K-edge X-ray absorption near-edge structure (XANES) spectroscopy for a suite of 11 source rocks from around the world. Sulfur speciation was determined for both the native bitumen in thermally immature rocks and the bitumen produced by thermal maturation of kerogen via hydrous pyrolysis (360 °C for 72 h) and retained within the rock matrix. In this study, the immature bitumens had higher sulfur concentrations than those extracted from samples after hydrous pyrolysis. In addition, dramatic and systematic evolution of the bitumen sulfur moiety distributions following artificial thermal maturation was observed consistently for all samples. Specifically, sulfoxide sulfur (sulfur double bonded to oxygen) is abundant in all immature bitumen samples but decreases substantially following hydrous pyrolysis. The loss in sulfoxide sulfur is associated with a relative increase in the fraction of thiophene sulfur (sulfur bonded to aromatic carbon) to the extent that thiophene is the dominant sulfur form in all post-pyrolysis bitumen samples. This suggests that sulfur moiety distributions might be used for estimating thermal maturity in source rocks based on the character of the extractable organic matter.

  9. Applications of x ray absorption fine structure to the in situ study of the effect of cobalt in nickel hydrous oxide electrodes for fuel cells and rechargeable batteries

    NASA Technical Reports Server (NTRS)

    Kim, Sunghyun; Tryk, Donald A.; Scherson, Daniel A.; Antonio, Mark R.

    1993-01-01

    Electronic and structural aspects of composite nickel-cobalt hydrous oxides have been examined in alkaline solutions using in situ X-ray absorption fine structure (XAFS). The results obtained have indicated that cobalt in this material is present as cobaltic ions regardless of the oxidation state of nickel in the lattice. Furthermore, careful analysis of the Co K-edge Extended X-ray absorption fine structure data reveals that the co-electrodeposition procedure generates a single phase, mixed metal hydrous oxide, in which cobaltic ions occupy nickel sites in the NiO2 sheet-like layers and not two intermixed phases each consisting of a single metal hydrous oxide.

  10. Manganese oxide nanoparticles, methods and applications

    DOEpatents

    Abruna, Hector D.; Gao, Jie; Lowe, Michael A.

    2017-08-29

    Manganese oxide nanoparticles having a chemical composition that includes Mn.sub.3O.sub.4, a sponge like morphology and a particle size from about 65 to about 95 nanometers may be formed by calcining a manganese hydroxide material at a temperature from about 200 to about 400 degrees centigrade for a time period from about 1 to about 20 hours in an oxygen containing environment. The particular manganese oxide nanoparticles with the foregoing physical features may be used within a battery component, and in particular an anode within a lithium battery to provide enhanced performance.

  11. Microcapsules ejecting nanosized species into the environment.

    PubMed

    De Geest, Bruno G; McShane, Michael J; Demeester, Jo; De Smedt, Stefaan C; Hennink, Wim E

    2008-11-05

    In this communication we report on microcapsules which eject nanoparticles into the environment. The speed of the nanoparticles ejected in water is approximately 800-fold faster than their Brownian diffusion. Such microcarriers may allow nanosized species to travel long distances, in short times, through highly viscous environments and may find applications in e.g. drug delivery and tissue engineering.

  12. Chemoprotective and chemosensitizing properties of selenium nanoparticle (Nano-Se) during adjuvant therapy with cyclophosphamide in tumor-bearing mice.

    PubMed

    Bhattacharjee, Arin; Basu, Abhishek; Biswas, Jaydip; Sen, Tuhinadri; Bhattacharya, Sudin

    2017-01-01

    Cyclophosphamide (CP) is one of the widely used anticancer agents; however, it has serious deleterious effects on normal host cells due to its nonspecific action. The essential trace element Selenium (Se) is suggested to have chemopreventive and chemotherapeutic efficacy and currently used in pharmaceutical formulations. Previous report had shown Nano-Se could protect CP-induced hepatotoxicity and genotoxicity in normal Swiss albino mice; however, its role in cancer management is still not clear. The aim of present study is to investigate the chemoprotective efficacy of Nano-Se against CP-induced toxicity as well as its chemoenhancing capability when used along with CP in Swiss albino mice against Ehrlich's ascites carcinoma (EAC) cells. CP was administered (25 mg/kg b.w., i.p.) and Nano-Se was given (2 mg Se/kg b.w., p.o.) in concomitant and pretreatment schedule. Increase levels of serum hepatic marker, hepatic lipid peroxidation, DNA damage, and chromosomal aberration in CP-treated mice were significantly (P < 0.05) reversed by Nano-Se. The lowered status of various antioxidant enzymes in tumor-bearing mice after CP treatment was also effectively increased by Nano-Se. Administration of Nano-Se along with CP caused a significant reduction in tumor volume, packed cell volume, viable tumor cell count, and increased the survivability of the tumor-bearing hosts. The results suggest that Nano-Se exhibits significant antitumor and antioxidant effects in EAC-bearing mice. The potential for Nano-Se to ameliorate the CP-evoked toxicity as well as to improve the chemotherapeutic effect could have beneficial implications for patients undergoing chemotherapy with CP.

  13. Chronic manganese poisoning in the dry battery industry

    PubMed Central

    Emara, A. M.; El-Ghawabi, S. H.; Madkour, O. I.; El-Samra, G. H.

    1971-01-01

    Emara, A. M., El-Ghawabi, S. H., Madkour, O. I., and El-Samra, G. H. (1971). Brit. J. industr. Med., 28, 78-82. Chronic manganese poisoning in the dry battery industry. A survey was carried out on 36 workers in the dry battery industry exposed to dust containing 65 to 70% manganese oxide. Eight (22·2%) were found to have neuropsychiatric manifestations, six (16·6%) had chronic manganese psychosis, one had left hemi-parkinsonism, and one had left choreoathetosis. An environmental study revealed a high concentration of manganese dust at the main working areas, far exceeding the accepted MAC. The manganese level in blood was almost within the normal range. Coproporphyrin in urine was normal. The electroencephalogram was abnormal in only two of the affected workers (25%) but there was no association between this and the clinical manifestations or duration of exposure. The concentration of manganese dust in air showed some association with the prevalence and rapidity of effect on workers according to their occupation. However, individual susceptibility was apparent. The shortest latent period was one year. PMID:5101169

  14. A Novel Approach of Using Ground CNTs as the Carbon Source to Fabricate Uniformly Distributed Nano-Sized TiCx/2009Al Composites

    PubMed Central

    Wang, Lei; Qiu, Feng; Ouyang, Licheng; Wang, Huiyuan; Zha, Min; Shu, Shili; Zhao, Qinglong; Jiang, Qichuan

    2015-01-01

    Nano-sized TiCx/2009Al composites (with 5, 7, and 9 vol% TiCx) were fabricated via the combustion synthesis of the 2009Al-Ti-CNTs system combined with vacuum hot pressing followed by hot extrusion. In the present study, CNTs were used as the carbon source to synthesize nano-sized TiCx particles. An attempt was made to correlate the effect of ground CNTs by milling and the distribution of synthesized nano-sized TiCx particles in 2009Al as well as the tensile properties of nano-sized TiCx/2009Al composites. Microstructure analysis showed that when ground CNTs were used, the synthesized nano-sized TiCx particles dispersed more uniformly in the 2009Al matrix. Moreover, when 2 h-milled CNTs were used, the 5, 7, and 9 vol% nano-sized TiCx/2009Al composites had the highest tensile properties, especially, the 9 vol% nano-sized TiCx/2009Al composites. The results offered a new approach to improve the distribution of in situ nano-sized TiCx particles and tensile properties of composites. PMID:28793749

  15. Methanogenesis from wastewater stimulated by addition of elemental manganese

    PubMed Central

    Qiao, Sen; Tian, Tian; Qi, Benyu; Zhou, Jiti

    2015-01-01

    This study presents a novel procedure for accelerating methanogenesis from wastewater by adding elemental manganese into the anaerobic digestion system. The results indicated that elemental manganese effectively enhanced both the methane yield and the production rate. Compared to the control test without elemental manganese, the total methane yield and production rate with 4 g/L manganese addition increased 3.4-fold (from 0.89 ± 0.03 to 2.99 ± 0.37 M/gVSS within 120 h) and 4.4-fold (from 6.2 ± 0.1 to 27.2 ± 2.2 mM/gVSS/h), respectively. Besides, more acetate consumption and less propionate generation were observed during the methanogenesis with manganese. Further studies demonstrated that the elemental manganese served as electron donors for the methanogenesis from carbon dioxide, and the final proportion of methane in the total generated gas with 4 g/L manganese addition reached 96.9%, which was 2.1-fold than that of the control (46.6%). PMID:26244609

  16. Evaluating Re-Os systematics in organic-rich sedimentary rocks in response to petroleum generation using hydrous pyrolysis experiments

    USGS Publications Warehouse

    Rooney, A.D.; Selby, D.; Lewan, M.D.; Lillis, P.G.; Houzay, J.-P.

    2012-01-01

    Successful application of the 187Re–187Os geochronometer has enabled the determination of accurate and precise depositional ages for organic-rich sedimentary rocks (ORS) as well as establishing timing constraints of petroleum generation. However, we do not fully understand the systematics and transfer behaviour of Re and Os between ORS and petroleum products (e.g., bitumen and oil). To more fully understand the behaviour of Re–Os systematics in both source rocks and petroleum products we apply hydrous pyrolysis to two immature hydrocarbon source rocks: the Permian Phosphoria Formation (TOC = 17.4%; Type II-S kerogen) and the Jurassic Staffin Formation (TOC = 2.5%; Type III kerogen). The laboratory-based hydrous pyrolysis experiments were carried out for 72 h at 250, 300, 325 and 350 °C. These experiments provided us with whole rock, extracted rock and bitumen and in some cases expelled oil and asphaltene for evaluation of Re–Os isotopic and elemental abundance. The data from these experiments demonstrate that the majority (>95%) of Re and Os are housed within extracted rock and that thermal maturation does not result in significant transfer of Re or Os from the extracted rock into organic phases. Based on existing thermodynamic data our findings suggest that organic chelating sites have a greater affinity for the quadravalent states of Re and Os than sulphides. Across the temperature range of the hydrous pyrolysis experiments both whole rock and extracted rock 187Re/188Os ratios show small variations (3.3% and 4.7%, for Staffin, respectively and 6.3% and 4.9% for Phosphoria, respectively). Similarly, the 187Os/188Os ratios show only minor variations for the Staffin and Phosphoria whole rock and extracted rock samples (0.6% and 1.4% and 1.3% and 2.2%). These isotopic data strongly suggest that crude oil generation through hydrous pyrolysis experiments does not disturb the Re–Os systematics in ORS as supported by various studies on natural systems. The

  17. Evaluating Re-Os systematics in organic-rich sedimentary rocks in response to petroleum generation using hydrous pyrolysis experiments

    NASA Astrophysics Data System (ADS)

    Rooney, Alan D.; Selby, David; Lewan, Michael D.; Lillis, Paul G.; Houzay, Jean-Pierre

    2012-01-01

    Successful application of the 187Re-187Os geochronometer has enabled the determination of accurate and precise depositional ages for organic-rich sedimentary rocks (ORS) as well as establishing timing constraints of petroleum generation. However, we do not fully understand the systematics and transfer behaviour of Re and Os between ORS and petroleum products (e.g., bitumen and oil). To more fully understand the behaviour of Re-Os systematics in both source rocks and petroleum products we apply hydrous pyrolysis to two immature hydrocarbon source rocks: the Permian Phosphoria Formation (TOC = 17.4%; Type II-S kerogen) and the Jurassic Staffin Formation (TOC = 2.5%; Type III kerogen). The laboratory-based hydrous pyrolysis experiments were carried out for 72 h at 250, 300, 325 and 350 °C. These experiments provided us with whole rock, extracted rock and bitumen and in some cases expelled oil and asphaltene for evaluation of Re-Os isotopic and elemental abundance. The data from these experiments demonstrate that the majority (>95%) of Re and Os are housed within extracted rock and that thermal maturation does not result in significant transfer of Re or Os from the extracted rock into organic phases. Based on existing thermodynamic data our findings suggest that organic chelating sites have a greater affinity for the quadravalent states of Re and Os than sulphides. Across the temperature range of the hydrous pyrolysis experiments both whole rock and extracted rock 187Re/188Os ratios show small variations (3.3% and 4.7%, for Staffin, respectively and 6.3% and 4.9% for Phosphoria, respectively). Similarly, the 187Os/188Os ratios show only minor variations for the Staffin and Phosphoria whole rock and extracted rock samples (0.6% and 1.4% and 1.3% and 2.2%). These isotopic data strongly suggest that crude oil generation through hydrous pyrolysis experiments does not disturb the Re-Os systematics in ORS as supported by various studies on natural systems. The elemental

  18. Nano-sized Ni-doped carbon aerogel for supercapacitor.

    PubMed

    Lee, Yoon Jae; Jung, Ji Chul; Park, Sunyoung; Seo, Jeong Gil; Baeck, Sung-Hyeon; Yoon, Jung Rag; Yi, Jongheop; Song, In Kyu

    2011-07-01

    Carbon aerogel was prepared by polycondensation of resorcinol with formaldehyde using sodium carbonate as a catalyst in ambient conditions. Nano-sized Ni-doped carbon aerogel was then prepared by a precipitation method in an ethanol solvent. In order to elucidate the effect of nickel content on electrochemical properties, Ni-doped carbon aerogels (21, 35, 60, and 82 wt%) were prepared and their performance for supercapacitor electrode was investigated. Electrochemical properties of Ni-doped carbon aerogel electrodes were measured by cyclic voltammetry at a scan rate of 10 mV/sec and charge/discharge test at constant current of 1 A/g in 6 M KOH electrolyte. Among the samples prepared, 35 wt% Ni-doped carbon aerogel (Ni/CA-35) showed the highest capacitance (110 F/g) and excellent charge/discharge behavior. The enhanced capacitance of Ni-doped carbon aerogel was attributed to the faradaic redox reactions of nano-sized nickel oxide. Moreover, Ni-doped carbon aerogel exhibited quite stable cyclability, indicating long-term electrochemical stability.

  19. 21 CFR 73.2775 - Manganese violet.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2775 Manganese violet. (a) Identity. The color additive... less than 93 percent. (c) Uses and restrictions. Manganese violet is safe for use in coloring cosmetics generally, including cosmetics applied to the area of the eye, in amounts consistent with good manufacturing...

  20. 21 CFR 73.2775 - Manganese violet.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2775 Manganese violet. (a) Identity. The color additive... less than 93 percent. (c) Uses and restrictions. Manganese violet is safe for use in coloring cosmetics generally, including cosmetics applied to the area of the eye, in amounts consistent with good manufacturing...

  1. 21 CFR 73.2775 - Manganese violet.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2775 Manganese violet. (a) Identity. The color additive... less than 93 percent. (c) Uses and restrictions. Manganese violet is safe for use in coloring cosmetics generally, including cosmetics applied to the area of the eye, in amounts consistent with good manufacturing...

  2. Manganese micro-nodules on ancient brick walls.

    PubMed

    López-Arce, P; García-Guinea, J; Fierro, J L G

    2003-01-20

    Romans, Jews, Arabs and Christians built the ancient city of Toledo (Spain) with bricks as the main construction material. Manganese micro-nodules (circa 2 microm in diameter) have grown under the external bio-film surface of the bricks. Recent anthropogenic activities such as industrial emissions, foundries, or traffic and housing pollution have further altered these old bricks. The energy-dispersive X-ray microanalyses (XPS) of micro-nodules show Al, Si, Ca, K, Fe and Mn, with some carbon species. Manganese atoms are present only as Mn(4+) and iron as Fe(3+) (FeOOH-Fe(2)O(3) mixtures). The large concentration of alga biomass of the River Tagus and the Torcón and Guajaraz reservoirs suggest manganese micro-nodules are formed either from water solutions rich in anthropogenic MnO(4)K in a reduction environment (from Mn(7+) to Mn(4+)) or by oxidation mechanisms from dissolved Mn(2+) (from Mn(2+) to Mn(4+)) linked to algae biofilm onto the ancient brick surfaces. Ancient wall surfaces were also studied by scanning electron microscopy (SEM-EDS) and X-ray diffraction (XRD). Chemical and biological analyses of the waters around Toledo are also analysed for possible sources of manganese. Manganese micro-nodules on ancient brick walls are good indicators of manganese pollution. Copyright 2002 Elsevier Science B.V.

  3. 21 CFR 73.2775 - Manganese violet.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 1 2011-04-01 2011-04-01 false Manganese violet. 73.2775 Section 73.2775 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2775 Manganese violet. (a) Identity. The color additive...

  4. Quantifying manganese and nitrogen cycle coupling in manganese-rich, organic carbon-starved marine sediments: Examples from the Clarion-Clipperton fracture zone

    NASA Astrophysics Data System (ADS)

    Mogollón, José M.; Mewes, Konstantin; Kasten, Sabine

    2016-07-01

    Extensive deep-sea sedimentary areas are characterized by low organic carbon contents and thus harbor suboxic sedimentary environments where secondary (autotrophic) redox cycling becomes important for microbial metabolic processes. Simulation results for three stations in the Eastern Equatorial Pacific with low organic carbon content (<0.5 dry wt %) and low sedimentation rates (10-1-100 mm ky-1) show that ammonium generated during organic matter degradation may act as a reducing agent for manganese oxides below the oxic zone. Likewise, at these sedimentary depths, dissolved reduced manganese may act as a reducing agent for oxidized nitrogen species. These manganese-coupled transformations provide a suboxic conversion pathway of ammonium and nitrate to dinitrogen. These manganese-nitrogen interactions further explain the presence and production of dissolved reduced manganese (up to tens of μM concentration) in sediments with high nitrate (>20 μM) concentrations.

  5. Nitrogen Isotopic Anomalies in a Hydrous Interplanetary Dust Particle

    NASA Technical Reports Server (NTRS)

    Smith, J. B.; Dai, Z. R.; Weber, P. K.; Graham, G. A.; Hutcheon, I. D.; Bajt, S.; Ishii, H.; Bradley, J. P.

    2005-01-01

    Interplanetary dust particles (IDPs) collected in the stratosphere are the fine-grained end member (5 - 50 microns in size) of the meteoritic material available for investigation in the laboratory. IDPs are derived from either cometary or asteroidal sources. Some IDPs contain cosmically primitive materials with isotopic signatures reflecting presolar origins. Recent detailed studies using the NanoSIMS have shown there is a wide variation of isotopic signatures within individual IDPs; grains with a presolar signature have been observed surrounded by material with a solar isotopic composition. The majority of IDPs studied have been anhydrous. We report here results from integrated NanoSIMS/FIB/TEM/Synchrotron IR studies of a hydrous IDP, focused on understanding the correlations between the isotopic, mineralogical and chemical compositions of IDPs.

  6. Effect of nano-sized, elemental selenium supplement on the proteome of chicken liver.

    PubMed

    Gulyas, G; Csosz, E; Prokisch, J; Javor, A; Mezes, M; Erdelyi, M; Balogh, K; Janaky, T; Szabo, Z; Simon, A; Czegledi, L

    2017-06-01

    The nano-sized (100-500 nm) selenium has higher bioavailability and relatively lower toxicity compared to other selenium forms. The objective of the present study was to compare liver proteome profiles of broiler chicken fed with control diet without Se supplementation and diet supplemented with nano-Se with 4.25 mg/kg DM. Differential proteome analyses were performed by two-dimensional gel electrophoresis (2D-PAGE) followed by tryptic digestion and protein identification by liquid chromatography-mass spectrometry (LC-MS). Seven hundred and eight spots were detected, and 18 protein spots showed significant difference in their intensity (p < 0.05) between the two groups. In response to nano-Se supplementation, the expression of 8 proteins was higher, and 5 proteins were lower in nano-Se supplemented group compared to control group. The functions of the differentially expressed proteins indicate that the high dose of selenium supplementation induced a dietary stress. Selenium supplementation may influence the metabolism of fatty acids and carbohydrates and antioxidant system, and increase the quantity of cytoskeletal actin and the expression of actin regulatory protein as well. Journal of Animal Physiology and Animal Nutrition © 2016 Blackwell Verlag GmbH.

  7. A Novel Approach of Using Ground CNTs as the Carbon Source to Fabricate Uniformly Distributed Nano-Sized TiCx/2009Al Composites.

    PubMed

    Wang, Lei; Qiu, Feng; Ouyang, Licheng; Wang, Huiyuan; Zha, Min; Shu, Shili; Zhao, Qinglong; Jiang, Qichuan

    2015-12-17

    Nano-sized TiC x /2009Al composites (with 5, 7, and 9 vol% TiC x ) were fabricated via the combustion synthesis of the 2009Al-Ti-CNTs system combined with vacuum hot pressing followed by hot extrusion. In the present study, CNTs were used as the carbon source to synthesize nano-sized TiC x particles. An attempt was made to correlate the effect of ground CNTs by milling and the distribution of synthesized nano-sized TiC x particles in 2009Al as well as the tensile properties of nano-sized TiC x /2009Al composites. Microstructure analysis showed that when ground CNTs were used, the synthesized nano-sized TiC x particles dispersed more uniformly in the 2009Al matrix. Moreover, when 2 h-milled CNTs were used, the 5, 7, and 9 vol% nano-sized TiC x /2009Al composites had the highest tensile properties, especially, the 9 vol% nano-sized TiC x /2009Al composites. The results offered a new approach to improve the distribution of in situ nano-sized TiC x particles and tensile properties of composites.

  8. Potential Role of Epigenetic Mechanism in Manganese Induced Neurotoxicity

    PubMed Central

    Tarale, Prashant; Chakrabarti, Tapan; Sivanesan, Saravanadevi; Naoghare, Pravin; Bafana, Amit; Krishnamurthi, Kannan

    2016-01-01

    Manganese is a vital nutrient and is maintained at an optimal level (2.5–5 mg/day) in human body. Chronic exposure to manganese is associated with neurotoxicity and correlated with the development of various neurological disorders such as Parkinson's disease. Oxidative stress mediated apoptotic cell death has been well established mechanism in manganese induced toxicity. Oxidative stress has a potential to alter the epigenetic mechanism of gene regulation. Epigenetic insight of manganese neurotoxicity in context of its correlation with the development of parkinsonism is poorly understood. Parkinson's disease is characterized by the α-synuclein aggregation in the form of Lewy bodies in neuronal cells. Recent findings illustrate that manganese can cause overexpression of α-synuclein. α-Synuclein acts epigenetically via interaction with histone proteins in regulating apoptosis. α-Synuclein also causes global DNA hypomethylation through sequestration of DNA methyltransferase in cytoplasm. An individual genetic difference may also have an influence on epigenetic susceptibility to manganese neurotoxicity and the development of Parkinson's disease. This review presents the current state of findings in relation to role of epigenetic mechanism in manganese induced neurotoxicity, with a special emphasis on the development of Parkinson's disease. PMID:27314012

  9. High-pressure behaviour of serpentine and elasticity systematics of hydrous and nominally anhydrous phases

    NASA Astrophysics Data System (ADS)

    Fumagalli, P.; Mookherjee, M.; Stixrude, L. P.

    2006-12-01

    Serpentine, talc and brucite occur in oceanic crust as alteration products of ultramafic rocks. As mineral phases occurring in the subduction zone setting, both along the slab and within the mantle wedge, they are possible candidates for carrying and tranfer of water to the deep earth. This is manifested by serpentine mud volcanoes, high electrical conductivities, magnetic and seismic anomalies. At high pressure talc transforms to the 10 Å phase. Both the 10 Å phase and serpentine eventually transfer their water content to other dense hydrous magnesium silicates stable at depth greater than 200 km. Most of the mantle's water budget may be contained in nominally anhydrous phases in which hydrogen occurs as non-stoichiometric defects. In order to evaluate the potential for remote detection of mantle water via seismology, we have investigated the elasticity systematics of hydrous phases, supplementing literature data with a new ab initio theoretical study of serpentine. Serpentine shows unusual high-pressure behavior. We predict a symmetry preserving phase transformation involving a proton flip near 25 GPa, and elastic instability at somewhat higher pressures that may be related with experimentally observed amorphization. Results of compression for the low-pressure phase is well represented by a fourth order Birch-Murnaghan finite strain expression with Ko= 81 GPa, Ko'= 9.12 and KoKo"= -142, where K is the bulk modulus, prime indicates pressure derivatives, and O refers to zero pressure. The elastic constant tensor reveals large acoustic anisotropy (41 % in VP) and seismic wave velocities that are significantly higher than those inferred from experiments on serpentinites. We find that serpentine and many other hydrous and nominally anhydrous phases conform closely to generalized Birch's laws in VP, VS, and VB versus density space. Coherent patterns emerge only if hydroxyls are treated as single "atomic" units in the computation of mean atomic weight, suggesting

  10. Magnetic glass-film based on single-nanosize 𝜺 -Fe2O3 nanoparticles

    NASA Astrophysics Data System (ADS)

    Yoshikiyo, Marie; Namai, Asuka; Nakagawa, Kosuke; Ohkoshi, Shin-ichi

    2017-05-01

    We report a magnetic thin film of single-nanosize ɛ-Fe2O3 in SiO2 matrix. The glass-film was prepared by sintering a silica coated iron oxide hydroxide on a quartz substrate in air. The glass-film consists of ɛ-Fe2O3 of 8.8 nm size, and its thickness was 570 nm (0.57 μm) with a roughness of 10 nm (0.01 μm). UV-vis spectrum showed that the glass-film has small absorbance of 0.043 at 500 nm. The magneto-optical effect was investigated, and Faraday ellipticity showed a magnetic hysteresis loop with a coercive field of 3.0 ± 0.2 kOe. Furthermore, single-nanosize ɛ-Fe2O3 without silica was prepared as a reference sample, and ferroelectricity was observed. Therefore, the present thin glass-film consists of single-nanosize ferroelectric-ferromagnetic nanoparticles.

  11. 40 CFR 721.10201 - Cobalt lithium manganese nickel oxide.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Cobalt lithium manganese nickel oxide... Specific Chemical Substances § 721.10201 Cobalt lithium manganese nickel oxide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as cobalt lithium manganese...

  12. 40 CFR 721.10201 - Cobalt lithium manganese nickel oxide.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Cobalt lithium manganese nickel oxide... Specific Chemical Substances § 721.10201 Cobalt lithium manganese nickel oxide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as cobalt lithium manganese...

  13. 40 CFR 721.10201 - Cobalt lithium manganese nickel oxide.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Cobalt lithium manganese nickel oxide... Specific Chemical Substances § 721.10201 Cobalt lithium manganese nickel oxide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as cobalt lithium manganese...

  14. Influence of nanosize clay platelets on the mechanical properties of glass fiber reinforced polyester composites.

    PubMed

    Jawahar, P; Balasubramanian, M

    2006-12-01

    Glass fiber reinforced polyester composite and hybrid nanoclay-fiber reinforced composites were prepared by hand lay-up process. The mechanical behavior of these materials and the changes as a result of the incorporation of both nanosize clay and glass fibers were investigated. Composites were prepared with a glass fibre content of 25 vol%. The proportion of the nanosize clay platelets was varied from 0.5 to 2.5 vol%. Hybrid clay-fiber reinforced polyester composite posses better tensile, flexural, impact, and barrier properties. Hybrid clay-fiber reinforced polyester composites also posses better shear strength, storage modulus, and glass transition temperature. The optimum properties were found to be with the hybrid laminates containing 1.5 vol% nanosize clay.

  15. Size effect of elemental selenium nanoparticles (Nano-Se) at supranutritional levels on selenium accumulation and glutathione S-transferase activity.

    PubMed

    Peng, Dungeng; Zhang, Jinsong; Liu, Qingliang; Taylor, Ethan Will

    2007-10-01

    It has been shown that 36 nm Nano-Se has lower toxicity than selenite or selenomethionine, but these forms of selenium (Se) all possess similar ability to increase selenoenzyme levels. The size of nanoparticles plays an important role in their biological activity: as expected, 5-200 nm Nano-Se can directly scavenge free radicals in vitro in a size-dependent fashion. However, in Se-deficient cells and Se-deficient mice, the size effect of Nano-Se on increasing selenoenzymes and liver Se disappears unexpectedly. We hypothesize that under conditions of Se deficiency, the avidity of Se uptake mechanisms may be increased to maintain the biosynthesis of selenoenzymes, which are fundamental for redox homeostasis. This increased avidity may override the potential advantage of small size Nano-Se seen under Se-replete conditions, thereby eliminating the size effect. Once selenoenzymes have been saturated, Se uptake mechanisms may downregulate; accordingly, the size effect of Nano-Se can then reappear. To test this hypothesis, Se-deficient mice were administered either 36 or 90 nm Nano-Se at supranutritional doses, in both a short-term model and a single-dose model. Under these conditions, Nano-Se showed a size effect on Se accumulation and glutathione S-transferase (GST) activity. A size effect of Nano-Se was found in 15 out of 18 total comparisons between sizes at the same dose and time in the two models. Furthermore, the magnitude of the size effect was more prominent on Se accumulation than on GST activity. GST is strictly regulated by transcriptional and translational mechanisms, so its increase in activity normally does not exceed 3-fold. In contrast, the homeostasis of Se accumulation is not as tightly controlled. In the present experiments, GST activity had reached or was approaching saturation, but liver Se was far below saturation. Therefore, our results strongly suggest that the saturation profile of the tested biomarker has an impact on the size effect of Nano-Se

  16. Formation of Green Rust and Immobilization of Nickel in Response to Bacterial Reduction of Hydrous Ferric Oxide

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Parmar, N.; Gorby, Yuri A.; Beveridge, Terrance J.

    This investigation documents the formation of Green Rust (GR) and immobilization of Ni2+ in response to bacterial reduction of hydrous ferric oxide (HFO) reduction experiments provided evidence that the solid-phase partitioning of Ni2+ in GR extended from equilibrium solid-solution behavior.

  17. 40 CFR 721.10011 - Barium calcium manganese strontium oxide.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... manganese strontium oxide (PMN P-00-1124; CAS No. 359427-90-0) is subject to reporting under this section... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Barium calcium manganese strontium... Specific Chemical Substances § 721.10011 Barium calcium manganese strontium oxide. (a) Chemical substance...

  18. 40 CFR 721.10011 - Barium calcium manganese strontium oxide.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... manganese strontium oxide (PMN P-00-1124; CAS No. 359427-90-0) is subject to reporting under this section... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Barium calcium manganese strontium... Specific Chemical Substances § 721.10011 Barium calcium manganese strontium oxide. (a) Chemical substance...

  19. 40 CFR 721.10011 - Barium calcium manganese strontium oxide.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... manganese strontium oxide (PMN P-00-1124; CAS No. 359427-90-0) is subject to reporting under this section... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Barium calcium manganese strontium... Specific Chemical Substances § 721.10011 Barium calcium manganese strontium oxide. (a) Chemical substance...

  20. Photoinduced oxidation of a water-soluble manganese(III) porphyrin

    PubMed Central

    Maliyackel, Anthony C.; Otvos, John W.; Spreer, Larry O.; Calvin, Melvin

    1986-01-01

    The photoinduced oxidation of tetra(N-methyl-4-pyridyl)porphyrinmanganese(III) has been achieved in homogeneous solution. The manganese porphyrin was used as an electron donor in a three-component system with tris-(2,2′-bipyridine)ruthenium(II) as the photosensitizer and chloropentaamminecobalt(III) as the electron acceptor. The photooxidized manganese porphyrin is unstable in aqueous solution, reverting to the starting manganese(III) porphyrin. The oxidation of manganese(III) porphyrin and the subsequent reduction of the oxidized porphyrin can be cycled repeatedly. PMID:16593699

  1. Manganese Catalyzed C–H Halogenation

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Liu, Wei; Groves, John T.

    2015-06-16

    The remarkable aliphatic C–H hydroxylations catalyzed by the heme-containing enzyme, cytochrome P450, have attracted sustained attention for more than four decades. The effectiveness of P450 enzymes as highly selective biocatalysts for a wide range of oxygenation reactions of complex substrates has driven chemists to develop synthetic metalloporphyrin model compounds that mimic P450 reactivity. Among various known metalloporphyrins, manganese derivatives have received considerable attention since they have been shown to be versatile and powerful mediators for alkane hydroxylation and olefin epoxidation. Mechanistic studies have shown that the key intermediates of the manganese porphyrin-catalyzed oxygenation reactions include oxo- and dioxomanganese(V) species thatmore » transfer an oxygen atom to the substrate through a hydrogen abstraction/oxygen recombination pathway known as the oxygen rebound mechanism. Application of manganese porphyrins has been largely restricted to catalysis of oxygenation reactions until recently, however, due to ultrafast oxygen transfer rates. In this Account, we discuss recently developed carbon–halogen bond formation, including fluorination reactions catalyzed by manganese porphyrins and related salen species. We found that biphasic sodium hypochlorite/manganese porphyrin systems can efficiently and selectively convert even unactivated aliphatic C–H bonds to C–Cl bonds. An understanding of this novel reactivity derived from results obtained for the oxidation of the mechanistically diagnostic substrate and radical clock, norcarane. Significantly, the oxygen rebound rate in Mn-mediated hydroxylation is highly correlated with the nature of the trans-axial ligands bound to the manganese center (L–Mn V$=$O). Based on the ability of fluoride ion to decelerate the oxygen rebound step, we envisaged that a relatively long-lived substrate radical could be trapped by a Mn–F fluorine source, effecting carbon–fluorine bond

  2. Manganese oxide-based materials as electrochemical supercapacitor electrodes.

    PubMed

    Wei, Weifeng; Cui, Xinwei; Chen, Weixing; Ivey, Douglas G

    2011-03-01

    Electrochemical supercapacitors (ECs), characteristic of high power and reasonably high energy densities, have become a versatile solution to various emerging energy applications. This critical review describes some materials science aspects on manganese oxide-based materials for these applications, primarily including the strategic design and fabrication of these electrode materials. Nanostructurization, chemical modification and incorporation with high surface area, conductive nanoarchitectures are the three major strategies in the development of high-performance manganese oxide-based electrodes for EC applications. Numerous works reviewed herein have shown enhanced electrochemical performance in the manganese oxide-based electrode materials. However, many fundamental questions remain unanswered, particularly with respect to characterization and understanding of electron transfer and atomic transport of the electrochemical interface processes within the manganese oxide-based electrodes. In order to fully exploit the potential of manganese oxide-based electrode materials, an unambiguous appreciation of these basic questions and optimization of synthesis parameters and material properties are critical for the further development of EC devices (233 references).

  3. Essentiality, toxicity, and uncertainty in the risk assessment of manganese.

    PubMed

    Boyes, William K

    2010-01-01

    Risk assessments of manganese by inhalation or oral routes of exposure typically acknowledge the duality of manganese as an essential element at low doses and a toxic metal at high doses. Previously, however, risk assessors were unable to describe manganese pharmacokinetics quantitatively across dose levels and routes of exposure, to account for mass balance, and to incorporate this information into a quantitative risk assessment. In addition, the prior risk assessment of inhaled manganese conducted by the U.S. Environmental Protection Agency (EPA) identified a number of specific factors that contributed to uncertainty in the risk assessment. In response to a petition regarding the use of a fuel additive containing manganese, methylcyclopentadienyl manganese tricarbonyl (MMT), the U.S. EPA developed a test rule under the U.S. Clean Air Act that required, among other things, the generation of pharmacokinetic information. This information was intended not only to aid in the design of health outcome studies, but also to help address uncertainties in the risk assessment of manganese. To date, the work conducted in response to the test rule has yielded substantial pharmacokinetic data. This information will enable the generation of physiologically based pharmacokinetic (PBPK) models capable of making quantitative predictions of tissue manganese concentrations following inhalation and oral exposure, across dose levels, and accounting for factors such as duration of exposure, different species of manganese, and changes of age, gender, and reproductive status. The work accomplished in response to the test rule, in combination with other scientific evidence, will enable future manganese risk assessments to consider tissue dosimetry more comprehensively than was previously possible.

  4. Wear Resistance of Austempered Ductile Iron with Nanosized Additives

    NASA Astrophysics Data System (ADS)

    Kaleicheva, J. K.; Mishev, V.

    2018-01-01

    The wear resistance, microstructure and mechanical properties of austempered ductile iron (ADI) with nanosized additives of cubic boron nitride cBN are investigated. Samples of ductile iron are put under austhempering at the following conditions: heating at 900°С, 1 h and isothermal retention at 280оС, 2 h and 380°С, 2 h with the aim to achieve a lower bainitic structure and an upper bainitic structure. The experimental wear testing of austempered ductile irons is performed in friction conditions of a fixed abrasive by a cinematic scheme „pin - disc” using an accelerated testing method and device. The microstructure of the ADI is investigated by metallographic and X-Ray analyses. The Vickers hardness testing and impact strength examination are carried out. The influence of the nanosized additives of cBN on the wear resistance, microstructure, impact strength and hardness of the ADI is investigated.

  5. Air Manganese Study

    EPA Pesticide Factsheets

    In November 2011 US EPA researchers conducted a health study of airborne manganese exposure in East Liverpool, Ohio. This Web site discusses preliminary results of the study and provides background and other related information.

  6. Permanganate-based synthesis of manganese oxide nanoparticles in ferritin

    NASA Astrophysics Data System (ADS)

    Olsen, Cameron R.; Smith, Trevor J.; Embley, Jacob S.; Maxfield, Jake H.; Hansen, Kameron R.; Peterson, J. Ryan; Henrichsen, Andrew M.; Erickson, Stephen D.; Buck, David C.; Colton, John S.; Watt, Richard K.

    2017-05-01

    This paper investigates the comproportionation reaction of MnII with {{{{MnO}}}4}- as a route for manganese oxide nanoparticle synthesis in the protein ferritin. We report that {{{{MnO}}}4}- serves as the electron acceptor and reacts with MnII in the presence of apoferritin to form manganese oxide cores inside the protein shell. Manganese loading into ferritin was studied under acidic, neutral, and basic conditions and the ratios of MnII and permanganate were varied at each pH. The manganese-containing ferritin samples were characterized by transmission electron microscopy, UV/Vis absorption, and by measuring the band gap energies for each sample. Manganese cores were deposited inside ferritin under both the acidic and basic conditions. All resulting manganese ferritin samples were found to be indirect band gap materials with band gap energies ranging from 1.01 to 1.34 eV. An increased UV/Vis absorption around 370 nm was observed for samples formed under acidic conditions, suggestive of MnO2 formation inside ferritin.

  7. Hydrous partial melting in the sheeted dike complex at fast spreading ridges: experimental and natural observations

    NASA Astrophysics Data System (ADS)

    France, Lydéric; Koepke, Juergen; Ildefonse, Benoit; Cichy, Sarah B.; Deschamps, Fabien

    2010-11-01

    In ophiolites and in present-day oceanic crust formed at fast spreading ridges, oceanic plagiogranites are commonly observed at, or close to the base of the sheeted dike complex. They can be produced either by differentiation of mafic melts, or by hydrous partial melting of the hydrothermally altered sheeted dikes. In addition, the hydrothermally altered base of the sheeted dike complex, which is often infiltrated by plagiogranitic veins, is usually recrystallized into granoblastic dikes that are commonly interpreted as a result of prograde granulitic metamorphism. To test the anatectic origin of oceanic plagiogranites, we performed melting experiments on a natural hydrothermally altered dike, under conditions that match those prevailing at the base of the sheeted dike complex. All generated melts are water saturated, transitional between tholeiitic and calc-alkaline, and match the compositions of oceanic plagiogranites observed close to the base of the sheeted dike complex. Newly crystallized clinopyroxene and plagioclase have compositions that are characteristic of the same minerals in granoblastic dikes. Published silicic melt compositions obtained in classical MORB fractionation experiments also broadly match the compositions of oceanic plagiogranites; however, the compositions of the coexisting experimental minerals significantly deviate from those of the granoblastic dikes. Our results demonstrate that hydrous partial melting is a likely common process in the root zone of the sheeted dike complex, starting at temperatures exceeding 850°C. The newly formed melt can either crystallize to form oceanic plagiogranites or may be recycled within the melt lens resulting in hybridized and contaminated MORB melts. It represents the main MORB crustal contamination process. The residue after the partial melting event is represented by the granoblastic dikes. Our results support a model with a dynamic melt lens that has the potential to trigger hydrous partial melting

  8. Nanosized Selenium: A Novel Platform Technology to Prevent Bacterial Infections

    NASA Astrophysics Data System (ADS)

    Wang, Qi

    As an important category of bacterial infections, healthcare-associated infections (HAIs) are considered an increasing threat to the safety and health of patients worldwide. HAIs lead to extended hospital stays, contribute to increased medical costs, and are a significant cause of morbidity and mortality. In the United States, infections encountered in the hospital or a health care facility affect more than 1.7 million patients, cost 35.7 billion to 45 billion, and contribute to 88,000 deaths in hospitals annually. The most conventional and widely accepted method to fight against bacterial infections is using antibiotics. However, because of the widespread and sometimes inappropriate use of antibiotics, many strains of bacteria have rapidly developed antibiotic resistance. Those new, stronger bacteria pose serious, worldwide threats to public health and welfare. In 2014, the World Health Organization (WHO) reported antibiotic resistance as a global serious threat that is no longer a prediction for the future but is now reality. It has the potential to affect anyone, of any age, in any country. The most effective strategy to prevent antibiotic resistance is minimizing the use of antibiotics. In recent years, nanomaterials have been investigated as one of the potential substitutes of antibiotics. As a result of their vastly increased ratio of surface area to volume, nanomaterials will likely exert a stronger interaction with bacteria which may affect bacterial growth and propagation. A major concern of most existing antibacterial nanomaterials, like silver nanoparticles, is their potential toxicity. But selenium is a non-metallic material and a required nutrition for the human body, which is recommended by the FDA at a 53 to 60 μg daily intake. Nanosized selenium is considered to be healthier and less toxic compared with many metal-based nanomaterials due to the generation of reactive oxygen species from metals, especially heavy metals. Therefore, the objectives of

  9. Bioaccumulation of manganese and its toxicity in feral pigeons (Columba livia) exposed to manganese oxide dust (Mn{sub 3}O{sub 4})

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sierra, P.; Chakrabarti, S.; Tounkara, R.

    1998-11-01

    Manganese tetroxide (Mn{sub 3}O{sub 4}) is a product from the combustion of methylcyclopentadienyl manganese tricarbonyl. Exposure to high levels of manganese can lead to serious health effects especially to the central nervous and respiratory systems. Very few studies on the effects of long-term low level exposure to Mn{sub 3}O{sub 4} have been reported. The present study was therefore conducted to examine the bioaccumulation and toxicity of manganese in various organs of feral pigeons (Columba kivia) when exposed to low levels of Mn{sub 3}O{sub 4} via inhalation and hence to find any possible relationship between these two parameters. A total ofmore » 22 pigeons was exposed to 239 {micro}g/m{sup 3} of manganese for 7 h/day, 5 days/week for 5, 9, and 13 consecutive weeks. Manganese concentrations in various tissues, e.g., brain (mesencephalon), lung, liver, intestine, pancreas, kidney, muscle, bone, and whole blood, were measured by neutron activation analysis. Various biochemical parameters in blood, e.g., hematocrit, total proteins, glucose, uric acid, alinine aminotransferase, total iron, blood urea nitrogen and triglycerides, were also measured.« less

  10. Manganese Uptake and Streptococcal Virulence

    PubMed Central

    Eijkelkamp, Bart A.; McDevitt, Christopher A.; Kitten, Todd

    2018-01-01

    Streptococcal solute-binding proteins (SBPs) associated with ATP-binding cassette transporters gained widespread attention first as ostensible adhesins, next as virulence determinants, and finally as metal ion transporters. In this mini-review, we will examine our current understanding of the cellular roles of these proteins, their contribution to metal ion homeostasis, and their crucial involvement in mediating streptococcal virulence. There are now more than 35 studies that have collected structural, biochemical and/or physiological data on the functions of SBPs across a broad range of bacteria. This offers a wealth of data to clarify the formerly puzzling and contentious findings regarding the metal specificity amongst this group of essential bacterial transporters. In particular we will focus on recent findings related to biological roles for manganese in streptococci. These advances will inform efforts aimed at exploiting the importance of manganese and manganese acquisition for the design of new approaches to combat serious streptococcal diseases. PMID:25652937

  11. Differentiation of pre-existing trapped methane from thermogenic methane in an igneous-intruded coal by hydrous pyrolysis

    USGS Publications Warehouse

    Dias, Robert F.; Lewan, Michael D.; Birdwell, Justin E.; Kotarba, Maciej J.

    2014-01-01

    So as to better understand how the gas generation potential of coal changes with increasing rank, same-seam samples of bituminous coal from the Illinois Basin that were naturally matured to varying degrees by the intrusion of an igneous dike were subjected to hydrous pyrolysis (HP) conditions of 360 °C for 72 h. The accumulated methane in the reactor headspace was analyzed for δ13C and δ2H, and mol percent composition. Maximum methane production (9.7 mg/g TOC) occurred in the most immature samples (0.5 %Ro), waning to minimal methane values at 2.44 %Ro (0.67 mg/g TOC), and rebounding to 3.6 mg/g TOC methane in the most mature sample (6.76 %Ro). Methane from coal with the highest initial thermal maturity (6.76 %Ro) shows no isotopic dependence on the reactor water and has a microbial δ13C value of −61‰. However, methane from coal of minimal initial thermal maturity (0.5 %Ro) shows hydrogen isotopic dependence on the reaction water and has a δ13C value of −37‰. The gas released from coals under hydrous pyrolysis conditions represents a quantifiable mixture of ancient (270 Ma) methane (likely microbial) that was generated in situ and trapped within the rock during the rapid heating by the dike, and modern (laboratory) thermogenic methane that was generated from the indigenous organic matter due to thermal maturation induced by hydrous pyrolysis conditions. These findings provide an analytical framework for better assessment of natural gas sources and for differentiating generated gas from pre-existing trapped gas in coals of various ranks.

  12. Late Holocene hydrous mafic magmatism at the Paint Pot Crater and Callahan flows, Medicine Lake Volcano, N. California and the influence of H2O in the generation of silicic magmas

    USGS Publications Warehouse

    Kinzler, R.J.; Donnelly-Nolan, J. M.; Grove, T.L.

    2000-01-01

    This paper characterizes late Holocene basalts and basaltic andesites at Medicine Lake volcano that contain high pre-eruptive H2O contents inherited from a subduction related hydrous component in the mantle. The basaltic andesite of Paint Pot Crater and the compositionally zoned basaltic to andesitic lavas of the Callahan flow erupted approximately 1000 14C years Before Present (14C years B.P.). Petrologic, geochemical and isotopic evidence indicates that this late Holocene mafic magmatism was characterized by H2O contents of 3 to 6 wt% H2O and elevated abundances of large ion lithophile elements (LILE). These hydrous mafic inputs contrast with the preceding episodes of mafic magmatism (from 10,600 to ~3000 14C years B.P.) that was characterized by the eruption of primitive high alumina olivine tholeiite (HAOT) with low H2O (< 0.2 wt%), lower LILE abundance and different isotopic characteristics. Thus, the mantle-derived inputs into the Medicine Lake system have not always been low H2O, primitive HAOT, but have alternated between HAOT and hydrous subduction related, calc-alkaline basalt. This influx of hydrous mafic magma coincides temporally and spatially with rhyolite eruption at Glass Mountain and Little Glass Mountain. The rhyolites contain quenched magmatic inclusions similar in character to the mafic lavas at Callahan and Paint Pot Crater. The influence of H2O on fractional crystallization of hydrous mafic magma and melting of pre-existing granite crust beneath the volcano combined to produce the rhyolite. Fractionation under hydrous conditions at upper crustal pressures leads to the early crystallization of Fe-Mg silicates and the suppression of plagioclase as an early crystallizing phase. In addition, H2O lowers the saturation temperature of Fe and Mg silicates, and brings the temperature of oxide crystallization closer to the liquidus. These combined effects generate SiO2-enrichment that leads to rhyodacitic differentiated lavas. In contrast, low H2O HAOT

  13. MANGANESE DIOXIDE METHOD FOR PREPARATION OF PROTACTINIUM

    DOEpatents

    Katzin, L.I.

    1958-08-12

    A method of obtaining U/sup 233/ is described. An aqueous solution of neutriln irradiated thoriunn is treated by forming tberein a precipitate of manganese dioxide which carries and thus separates the Pa/sup 233/ from the solution. The carrier precipitate so formed is then dissolved in an acidic solution containing a reducing agent sufficiently electronegative to reduce the tetravalent manganese to the divalent state. Further purification of the Pa/sup 233/ may be obtained by forming another manganese dioxide carrier precipitate and subsequently dissolving it. Ater a sufficient number of such cycles have brought the Pa/sup 233/ to the desired purity, the solution is aged, allowing the formation ot U/sup 233/ by radioaetive decay. A manganese dioxide precipitate is then formed in the U/sup 233/ containing solution. This precipitate carries down any remaining Pa/sup 233/ thus leaving the separated U/sup 233/solution, from whieh it may be easily recovered.

  14. Chemically activated manganese dioxide for dry batteries

    NASA Astrophysics Data System (ADS)

    Askar, M.; Abbas, H.

    1994-10-01

    The present investigation has enabled us to convert inactive beta-manganese dioxide to high electrochemically active types by chemical processes. Natural and chemically prepared beta-manganese dioxides were roasted at 1050 C to form Mn3O4. This compound was subjected to activation treatment using hydrochloric and sulfuric acid under various reaction conditions. The manganese dioxide so obtained was examined by x-ray diffraction, thermogravimetric, differential thermal, and chemical analyses. The structure of the dioxide obtained was found to be greatly dependent on the origin of MnO2 and type of acid used. Treatment with hydrochloric acid yielded the so-called gamma-variety while sulfuric acid tended to produce gamma- or alpha-MnO2. In addition, waste manganese sulfate obtained as by-product from sulfuric acid digestion treatment was recycled and electrolytically oxidized to gamma-MnO2. The discharge performance of the above-mentioned MnO2 samples as battery cathodic active material was evaluated and compared with the ordinary battery grade.

  15. Biodistribution and PET Imaging of pharmacokinetics of manganese in mice using Manganese-52

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wooten, A. Lake; Aweda, Tolulope A.; Lewis, Benjamin C.

    Manganese is essential to life, and humans typically absorb sufficient quantities of this element from a normal healthy diet; however, chronic, elevated ingestion or inhalation of manganese can be neurotoxic, potentially leading to manganism. Although imaging of large amounts of accumulated Mn(II) is possible by MRI, quantitative measurement of the biodistribution of manganese, particularly at the trace level, can be challenging. In this study, we produced the positron-emitting radionuclide 52Mn (t 1/2 = 5.6 d) by proton bombardment (E p<15 MeV) of chromium metal, followed by solid-phase isolation by cation-exchange chromatography. An aqueous solution of [ 52Mn]MnCl 2 was nebulizedmore » into a closed chamber with openings through which mice inhaled the aerosol, and a separate cohort of mice received intravenous (IV) injections of [ 52Mn]MnCl 2. Ex vivo biodistribution was performed at 1 h and 1 d post-injection/inhalation (p.i.). In both trials, we observed uptake in lungs and thyroid at 1 d p.i. Manganese is known to cross the blood-brain barrier, as confirmed in our studies following IV injection (0.86%ID/g, 1 d p.i.) and following inhalation of aerosol, (0.31%ID/g, 1 d p.i.). Uptake in salivary gland and pancreas were observed at 1 d p.i. (0.5 and 0.8%ID/g), but to a much greater degree from IV injection (6.8 and 10%ID/g). In a separate study, mice received IV injection of an imaging dose of [ 52Mn]MnCl 2, followed by in vivo imaging by positron emission tomography (PET) and ex vivo biodistribution. The results from this study supported many of the results from the biodistribution-only studies. In this work, we have confirmed results in the literature and contributed new results for the biodistribution of inhaled radiomanganese for several organs. In conclusion, our results could serve as supporting information for environmental and occupational regulations, for designing PET studies utilizing 52Mn, and/or for predicting the biodistribution of manganese

  16. Biodistribution and PET Imaging of pharmacokinetics of manganese in mice using Manganese-52

    DOE PAGES

    Wooten, A. Lake; Aweda, Tolulope A.; Lewis, Benjamin C.; ...

    2017-03-17

    Manganese is essential to life, and humans typically absorb sufficient quantities of this element from a normal healthy diet; however, chronic, elevated ingestion or inhalation of manganese can be neurotoxic, potentially leading to manganism. Although imaging of large amounts of accumulated Mn(II) is possible by MRI, quantitative measurement of the biodistribution of manganese, particularly at the trace level, can be challenging. In this study, we produced the positron-emitting radionuclide 52Mn (t 1/2 = 5.6 d) by proton bombardment (E p<15 MeV) of chromium metal, followed by solid-phase isolation by cation-exchange chromatography. An aqueous solution of [ 52Mn]MnCl 2 was nebulizedmore » into a closed chamber with openings through which mice inhaled the aerosol, and a separate cohort of mice received intravenous (IV) injections of [ 52Mn]MnCl 2. Ex vivo biodistribution was performed at 1 h and 1 d post-injection/inhalation (p.i.). In both trials, we observed uptake in lungs and thyroid at 1 d p.i. Manganese is known to cross the blood-brain barrier, as confirmed in our studies following IV injection (0.86%ID/g, 1 d p.i.) and following inhalation of aerosol, (0.31%ID/g, 1 d p.i.). Uptake in salivary gland and pancreas were observed at 1 d p.i. (0.5 and 0.8%ID/g), but to a much greater degree from IV injection (6.8 and 10%ID/g). In a separate study, mice received IV injection of an imaging dose of [ 52Mn]MnCl 2, followed by in vivo imaging by positron emission tomography (PET) and ex vivo biodistribution. The results from this study supported many of the results from the biodistribution-only studies. In this work, we have confirmed results in the literature and contributed new results for the biodistribution of inhaled radiomanganese for several organs. In conclusion, our results could serve as supporting information for environmental and occupational regulations, for designing PET studies utilizing 52Mn, and/or for predicting the biodistribution of manganese

  17. Essentiality, Toxicity and Uncertainty in the Risk Assessment of Manganese

    EPA Science Inventory

    Risk assessments of manganese by inhalation or oral routes of exposure typically acknowledge the duality of manganese as an essential element at low doses and a toxic metal at high doses. Previously, however, risk assessors were unable to describe manganese pharmacokinetics quant...

  18. Functionally charged nanosize particles differentially activate BV2 microglia.

    EPA Science Inventory

    The effect of particle surface charge on the biological activation of immortalized mouse microglia (BV2) was examined. Nanosize (860-950 nm) spherical polystyrene microparticles (SPM) were coated with carboxyl (COOH-) or dimethyl amino (CH3)2-N- groups to give a net negative or p...

  19. A Brillouin scattering study of hydrous basaltic glasses: the effect of H2O on their elastic behavior and implications for the densities of basaltic melts

    NASA Astrophysics Data System (ADS)

    Wu, Lei; Yang, De-Bin; Liu, Jun-Xiu; Hu, Bo; Xie, Hong-Sen; Li, Fang-Fei; Yu, Yang; Xu, Wen-Liang; Gao, Chun-Xiao

    2017-06-01

    Hydrous basalt glasses with water contents of 0-6.82% were synthesized using a multi-anvil press at 1.0-2.0 GPa and 1200-1400 °C. The starting materials were natural Mesozoic basalts from the eastern North China Craton (NCC). Their sound velocities and elastic properties were measured by Brillouin scattering spectroscopy. The longitudinal ( V P) and shear ( V S) wave velocities decreased with increasing water content. Increasing the synthesis pressure resulted in the glass becoming denser, and finally led to an increase in V P. As the degree of depolymerization increased, the V P, V S, and shear and bulk moduli of the hydrous basalt glasses decreased, whereas the adiabatic compressibility increased. The partial molar volumes of water (ν) under ambient conditions were independent of composition, having values of 11.6 ± 0.8, 10.9 ± 0.6 and 11.5 ± 0.5 cm3/mol for the FX (Feixian), FW (Fuxin), and SHT (Sihetun) basalt glasses, respectively. However, the {{V}_{{{{H}}_{{2}}}{O}}} values measured at elevated temperatures and pressures are increasing with increasing temperature or decreasing pressure. The contrasting densities of these hydrous basalt melts with those previously reported for mid-ocean ridge basalt and preliminary reference Earth model data indicate that hydrous basalt melts may not maintain gravitational stability at the base of the upper mantle.

  20. Removal of Iron and Manganese in Groundwater using Natural Biosorbent

    NASA Astrophysics Data System (ADS)

    Baharudin, F.; Tadza, M. Y. Mohd; Imran, S. N. Mohd; Jani, J.

    2018-04-01

    This study was conducted to measure and compare the concentration of iron, manganese and hardness of the river and groundwater and to determine the effectiveness of iron and manganese removal by using natural biosorbent which is banana peels. The samples of river and groundwater were collected at riverbank filtration site at Jenderam Hilir, Dengkil. Based on the water quality investigation, the concentration of iron and manganese in the samples of groundwater have exceeded the drinking water quality standard which are 0.3 mg/L for iron and 0.1 mg/L for manganese. The removal process of the iron and manganese in the groundwater was done by using 2, 4 and 8 grams of banana peels activated carbon. It is found that with higher amount of activated banana peels, the removal of iron and manganese is more effective. The ranges of percentage of iron and manganese removal are between 82.25% to 90.84% and 98.79% to 99.43% respectively. From the result, banana peels activated carbon can be concluded as a one of the most effective low-cost adsorbent for groundwater treatment.

  1. Photogeochemical reactions of manganese under anoxic conditions

    NASA Astrophysics Data System (ADS)

    Liu, W.; Yee, N.; Piotrowiak, P.; Falkowski, P. G.

    2017-12-01

    Photogeochemistry describes reactions involving light and naturally occurring chemical species. These reactions often involve a photo-induced electron transfer that does not occur in the absence of light. Although photogeochemical reactions have been known for decades, they are often ignored in geochemical models. In particular, reactions caused by UV radiation during an ozone free early Earth could have influenced the available oxidation states of manganese. Manganese is one of the most abundant transition metals in the crust and is important in both biology and geology. For example, the presence of manganese (VI) oxides in the geologic record has been used as a proxy for oxygenic photosynthesis; however, we suggest that the high oxidation state of Mn can be produced abiotically by photochemical reactions. Aqueous solutions of manganese (II) as well as suspensions of rhodochrosite (MnCO3) were irradiated under anoxic condition using a 450 W mercury lamp and custom built quartz reaction vessels. The photoreaction of the homogeneous solution of Mn(II) produced H2 gas and akhtenskite (ɛ-MnO2) as the solid product . This product is different than the previously identified birnessite. The irradiation of rhodochrosite suspensions also produced H2 gas and resulted in both a spectral shift as well as morphology changes of the mineral particles in the SEM images. These reactions offer alternative, abiotic pathways for the formation of manganese oxides.

  2. Presence of nano-sized silica during in vitro digestion of foods containing silica as a food additive.

    PubMed

    Peters, Ruud; Kramer, Evelien; Oomen, Agnes G; Rivera, Zahira E Herrera; Oegema, Gerlof; Tromp, Peter C; Fokkink, Remco; Rietveld, Anton; Marvin, Hans J P; Weigel, Stefan; Peijnenburg, Ad A C M; Bouwmeester, Hans

    2012-03-27

    The presence, dissolution, agglomeration state, and release of materials in the nano-size range from food containing engineered nanoparticles during human digestion is a key question for the safety assessment of these materials. We used an in vitro model to mimic the human digestion. Food products subjected to in vitro digestion included (i) hot water, (ii) coffee with powdered creamer, (iii) instant soup, and (iv) pancake which either contained silica as the food additive E551, or to which a form of synthetic amorphous silica or 32 nm SiO(2) particles were added. The results showed that, in the mouth stage of the digestion, nano-sized silica particles with a size range of 5-50 and 50-500 nm were present in food products containing E551 or added synthetic amorphous silica. However, during the successive gastric digestion stage, this nano-sized silica was no longer present for the food matrices coffee and instant soup, while low amounts were found for pancakes. Additional experiments showed that the absence of nano-sized silica in the gastric stage can be contributed to an effect of low pH combined with high electrolyte concentrations in the gastric digestion stage. Large silica agglomerates are formed under these conditions as determined by DLS and SEM experiments and explained theoretically by the extended DLVO theory. Importantly, in the subsequent intestinal digestion stage, the nano-sized silica particles reappeared again, even in amounts higher than in the saliva (mouth) digestion stage. These findings suggest that, upon consumption of foods containing E551, the gut epithelium is most likely exposed to nano-sized silica. © 2012 American Chemical Society

  3. SEPARATING PROTOACTINIUM WITH MANGANESE DIOXIDE

    DOEpatents

    Seaborg, G.T.; Gofman, J.W.; Stoughton, R.W.

    1958-04-22

    The preparation of U/sup 235/ and an improved method for isolating Pa/ sup 233/ from foreign products present in neutronirradiated thorium is described. The method comprises forming a solution of neutron-irradiated thorium together with a manganous salt, then adding potassium permanganate to precipitate the manganese as manganese dioxide whereby protoactinium is carried down with the nnanganese dioxide dissolving the precipitate, adding a soluble zirconium salt, and adding phosphate ion to precipitate zirconium phosphate whereby protoactinium is then carried down with the zirconium phosphate to effect a further concentration.

  4. Metal Doped Manganese Oxide Thin Films for Supercapacitor Application.

    PubMed

    Tung, Mai Thanh; Thuy, Hoang Thi Bich; Hang, Le Thi Thu

    2015-09-01

    Co and Fe doped manganese oxide thin films were prepared by anodic deposition at current density of 50 mA cm(-2) using the electrolyte containing manganese sulfate and either cobalt sulfate or ferrous sulfate. Surface morphology and crystal structure of oxides were studied by scanning electron microscope (SEM) and X-ray diffraction (XRD). Chemical composition of materials was analyzed by X-ray energy dispersive spectroscope (EDS), iodometric titration method and complexometric titration method, respectively. Supercapacitive behavior of Co and Fe doped manganese oxide films were characterized by cyclic voltammetry (CV) and impedance spectroscopy (EIS). The results show that the doped manganese oxides are composed of nano fiber-like structure with radius of 5-20 nm and remain amorphous structure after heat treatment at 100 degrees C for 2 hours. The average valence of manganese increases from +3.808 to +3.867 after doping Co and from +3.808 to +3.846 after doping Fe. The doped manganese oxide film electrodes exhibited preferably ideal pseudo-capacitive behavior. The specific capacitance value of deposited manganese oxide reaches a maximum of 175.3 F/g for doping Co and 244.6 F/g for doping Fe. The thin films retained about 84% of the initial capacity even after 500 cycles of charge-discharge test. Doping Co and Fe decreases diffusion and charge transfer resistance of the films. The electric double layer capacitance and capacitor response frequency are increased after doping.

  5. Stratigraphy of the pedogenic manganese nodules in the Carletonville area, North West Province of South Africa: A case study of the General Nice Manganese Mine

    NASA Astrophysics Data System (ADS)

    Pharoe, Benedict Kinshasa; Liu, Kuiwu

    2018-07-01

    The lithostratigraphy of pedogenic manganese (Mn) nodules in the Carletonville area is similar to the Klipkuil, Ryedale, Wes Wits, and Houtkoppies deposits in the West Rand region of the Gauteng and North West Provinces and to a lesser extent the Bronkhorstfontein manganese deposit in the Limpopo Province of South Africa. The lithostratigraphy of the ore deposit at the General Nice Manganese Mine consists of a basal manganese wad, preserved in a typical karst setting on top of the underlying Malmani stromatolitic dolomites and Tertiary fluvial and secondary mineral deposits consisting of manganese nodules of variable size in a finer-grained soil matrix. At the top of the deposit is a Mn-depleted Quaternary sand cover. The Tertiary alluvial succession hosting Mn nodules was informally subdivided into A, B, C, D, E, F, G and H zones on the basis of geochemical analyses (XRD, XRF and SEM) of bulk zone samples and the manganese nodule size and concentration.

  6. Preparation and performance of manganese-oxide-coated zeolite for the removal of manganese-contamination in groundwater.

    PubMed

    Lyu, Cong; Yang, Xuejiao; Zhang, Shengyu; Zhang, Qihui; Su, Xiaosi

    2017-12-29

    A promising and easily prepared catalytic filler media, manganese-oxide-coated zeolite (MOCZ), for the removal of Mn (II) contamination in groundwater was studied. The optimal condition for MOCZ preparation was given as follows: acid activation of zeolite with 5% HCl mass percent for 12 h, then soaking of acid-activated zeolite with 7% KMnO 4 mass percent for 8 h, and finally calcination at 300°C for 5 h. Acid activation significantly enlarged the specific surface area of the zeolite (>79 m 2  g -1 ), subsequently enhancing the coating of manganese oxides onto the surface of the zeolite. This was further supported by the manganese-to-zeolite ratio (γ Mn ) and Energy dispersive analysis-mapping. The γ Mn was over 12.26 mg Mn g -1 zeolite, representing more active sites for the adsorption and catalytic-oxidation of Mn (II). As such, great performance of Mn (II) removal by MOCZ was obtained in the filter experiment. An estimated 98-100% removal efficiency of Mn (II) was achieved in a greatly short startup time (only 2 h). During the filtration process, newborn flocculent manganese oxides with a mixed-valence of manganese (Mn (II) and Mn (IV)) were generated on the MOCZ surface, further facilitating the adsorption and catalytic-oxidation of Mn (II). The filter with MOCZ as adsorbent had a great performance on the Mn (II) removal in a wide range of hydraulic retention time (HRT) (4-40 min), particularly in a short HRT. Besides, the filter prolonged the filtration period (60 days), which would significantly reduce the frequency of backwash. Thus, it could be concluded that MOCZ prepared in this study showed a good performance in terms of Mn (II) removal in waterworks, especially small waterworks in the villages/towns.

  7. Characterization of nano-sized oxides in Fe-12Cr oxide-dispersion-strengthened ferritic steel using small-angle neutron scattering

    NASA Astrophysics Data System (ADS)

    Han, Young-Soo; Mao, Xiaodong; Jang, Jinsung; Kim, Tae-Kyu

    2015-04-01

    The ferritic ODS steel was manufactured by hot isostatic pressing and heat treatment. The nano-sized microstructures such as yttrium oxides and Cr oxides were quantitatively analyzed by small-angle neutron scattering (SANS). The effects of the fabrication conditions on the nano-sized microstructure were investigated in relation to the quantitative analysis results obtained by SANS. The ratio between magnetic and nuclear scattering components was calculated, and the characteristics of the nano-sized yttrium oxides are discussed based on the SANS analysis results.

  8. Hyperspectral characteristics of Celosia argentea which lived in manganese stress environment and inversion model for concentration effect of manganese

    NASA Astrophysics Data System (ADS)

    Chen, Sanming; Lin, Gang; Yin, Xianyang; Sun, Xiaolin; Xu, Jiasheng; Liu, Zhiying

    2015-12-01

    Sedimentary manganese deposits widely distribute in North Guangxi with the characteristic existing Celosia argentea. Celosia argentea is a kind of plant which has a strong ability to enrich manganese. In order to study the relationship between the hyperspectral characteristics of Celosia argentea and the concentration effect of manganese in the soil, we used soil of B layer in mining area, background soil and the soil adding reagent of MnCl4 to make up experimental sample soil with 10 levels Manganese content for the same batch Celosia argentea. The levels are 0mg/kg, 4500mg/kg, 9000mg/kg, 13500mg/kg, 18000mg/kg, 18020mg/kg, 18040mg/kg, 18080mg/kg, 18160mg/kg. ASD FieldSpec-4 has been used to measure the abnormal spectrums of these Celosia argentea through a whole growth cycle. After pretreating the spectral data, we used Successive Projections Algorithm (SPA) to extract the characteristic variables for extracting 1603 bands into 8 bands. Finally, the relationship between the spectral variables and the concentration of manganese was predicted by the Model of Partial Least Squares Regression (PLSR). The results show that the correlation coefficient-r2 are 0.8714 and 0.9141 in two sets of data. The prediction results are satisfactory, but the front 5 groups are closer to the regression line than the last 5 groups.

  9. Geological Sequestration of CO2 by Hydrous Carbonate Formation with Reclaimed Slag

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Von L. Richards; Kent Peaslee; Jeffrey Smith

    The concept of this project is to develop a process that improves the kinetics of the hydrous carbonate formation reaction enabling steelmakers to directly remove CO2 from their furnace exhaust gas. It is proposed to bring the furnace exhaust stream containing CO2 in contact with reclaimed steelmaking slag in a reactor that has an environment near the unit activity of water resulting in the production of carbonates. The CO2 emissions from the plant would be reduced by the amount sequestered in the formation of carbonates. The main raw materials for the process are furnace exhaust gases and specially prepared slag.

  10. The sensitized luminescence of manganese-activated calcite

    USGS Publications Warehouse

    Schulman, J.H.; Evans, L.W.; Ginther, R.J.; Murata, K.J.

    1947-01-01

    Synthetic manganese-activated calcites are shown to be practically inert to ultraviolet excitation in the range 2000-3500A, while they are luminescent under cathode-ray excitation. The incorporation of small amounts of an auxiliary impurity along with the manganese produces the strong response to ultraviolet radiation hitherto ascribed to CaCO3:Mn itself. Three such impurities have been studied: lead, thallium, and cerium. The first two induce excitation in the neighborhood of the mercury resonance line, while the cerium introduces a response principally to longer wave ultraviolet. The strong response to 2537A excitation shown by some natural calcites is likewise found to be due to the presence of lead along with the manganese, rather than to the manganese alone. The data do not warrant ascribing the longer wave-length ultraviolet-excited luminescence of all natural calcites to the action of an auxiliary impurity. The essential identity of the cathode-ray excited luminescence spectra of CaCO 3:Mn, CaCO3: (Pb+Mn), CaCO3:(Tl+Mn), and CaCO3:(Ce+Mn) with the 2537A-excited spectra of the latter three is evidence that the luminescent center in all cases is the manganese ion or the MnO6 group. It is shown that a "cascade" mechanism for the action of the auxiliary impurities, lead, thallium, and cerium, is incorrect; and that the phenomenon must be considered as a case of sensitized luminescence. Owing to the nature of cathode-ray excitation, the manganese activator can be excited by this agent even in the absence of a second impurity. For optical excitation, however, an absorption band for the ultraviolet must be established by building into the CaCO3:Mn a second impurity or "sensitizer.".

  11. Simultaneous stripping recovery of ammonia-nitrogen and precipitation of manganese from electrolytic manganese residue by air under calcium oxide assist.

    PubMed

    Chen, Hongliang; Liu, Renlong; Shu, Jiancheng; Li, Wensheng

    2015-01-01

    Leaching tests of electrolytic manganese residue (EMR) indicated that high contents of soluble manganese and ammonia-nitrogen posed a high environmental risk. This work reports the results of simultaneous stripping recovery of ammonia-nitrogen and precipitation of manganese by air under calcium oxide assist. The ammonia-nitrogen stripping rate increased with the dosage of CaO, the air flow rate and the temperature of EMR slurry. Stripped ammonia-nitrogen was absorbed by a solution of sulfuric acid and formed soluble (NH4)2SO4 and (NH4)3H(SO4)3. The major parameters that effected soluble manganese precipitation were the dosage of added CaO and the slurry temperature. Considering these two aspects, the efficient operation conditions should be conducted with 8 wt.% added CaO, 60°C, 800 mL min(-1) air flow rate and 60-min reaction time. Under these conditions 99.99% of the soluble manganese was precipitated as Mn3O4, which was confirmed by XRD and SEM-EDS analyses. In addition, the stripping rate of ammonia-nitrogen was 99.73%. Leaching tests showed the leached toxic substances concentrations of the treated EMR met the integrated wastewater discharge standard of China (GB8978-1996).

  12. Nanostructured manganese oxide thin films as electrode material for supercapacitors

    NASA Astrophysics Data System (ADS)

    Xia, Hui; Lai, Man On; Lu, Li

    2011-01-01

    Electrochemical capacitors, also called supercapacitors, are alternative energy storage devices, particularly for applications requiring high power densities. Recently, manganese oxides have been extensively evaluated as electrode materials for supercapacitors due to their low cost, environmental benignity, and promising supercapacitive performance. In order to maximize the utilization of manganese oxides as the electrode material for the supercapacitors and improve their supercapacitive performance, the nanostructured manganese oxides have therefore been developed. This paper reviews the synthesis of the nanostructured manganese oxide thin films by different methods and the supercapacitive performance of different nanostructures.

  13. Remote Pulsed Laser Raman Spectroscopy System for Detecting Qater, Ice, and Hydrous Minerals

    NASA Technical Reports Server (NTRS)

    Garcia, Christopher S.; Abedin, M. Nuraul; Sharma, Shiv K.; Misra, Anupam K.; Ismail, Syed; Singh, Upendra; Refaat, Tamer F.; Elsayed-Ali, Hani; Sandford, Steve

    2006-01-01

    For exploration of planetary surfaces, detection of water and ice is of great interest in supporting existence of life on other planets. Therefore, a remote Raman spectroscopy system was demonstrated at NASA Langley Research Center in collaboration with University of Hawaii for detecting ice-water and hydrous minerals on planetary surfaces. In this study, a 532 nm pulsed laser is utilized as an excitation source to allow detection in high background radiation conditions. The Raman scattered signal is collected by a 4-inch telescope positioned in front of a spectrograph. The Raman spectrum is analyzed using a spectrograph equipped with a holographic super notch filter to eliminate Rayleigh scattering, and a holographic transmission grating that simultaneously disperses two spectral tracks onto the detector for higher spectral range. To view the spectrum, the spectrograph is coupled to an intensified charge-coupled device (ICCD), which allows detection of very weak Stokes line. The ICCD is operated in gated mode to further suppress effects from background radiation and long-lived fluorescence. The sample is placed at 5.6 m from the telescope, and the laser is mounted on the telescope in a coaxial geometry to achieve maximum performance. The system was calibrated using the spectral lines of a Neon lamp source. To evaluate the system, Raman standard samples such as calcite, naphthalene, acetone, and isopropyl alcohol were analyzed. The Raman evaluation technique was used to analyze water, ice and other hydrous minerals and results from these species are presented.

  14. Diamondoid hydrocarbons as a molecular proxy for thermal maturity and oil cracking: Geochemical models from hydrous pyrolysis

    USGS Publications Warehouse

    Wei, Z.; Moldowan, J.M.; Zhang, S.; Hill, R.; Jarvie, D.M.; Wang, Hongfang; Song, F.; Fago, F.

    2007-01-01

    A series of isothermal hydrous pyrolysis experiments was performed on immature sedimentary rocks and peats of different lithology and organic source input to explore the generation of diamondoids during the thermal maturation of sediments. Oil generation curves indicate that peak oil yields occur between 340 and 360 ??C, followed by intense oil cracking in different samples. The biomarker maturity parameters appear to be insensitive to thermal maturation as most of the isomerization ratios of molecular biomarkers in the pyrolysates have reached their equilibrium values. Diamondoids are absent from immature peat extracts, but exist in immature sedimentary rocks in various amounts. This implies that they are not products of biosynthesis and that they may be generated during diagenesis, not just catagenesis and cracking. Most importantly, the concentrations of diamondoids are observed to increase with thermal stress, suggesting that they can be used as a molecular proxy for thermal maturity of source rocks and crude oils. Their abundance is most sensitive to thermal exposure above temperatures of 360-370 ??C (R0 = 1.3-1.5%) for the studied samples, which corresponds to the onset of intense cracking of other less stable components. Below these temperatures, diamondoids increase gradually due to competing processes of generation and dilution. Calibrations were developed between their concentrations and measured vitrinite reflectance through hydrous pyrolysis maturation of different types of rocks and peats. The geochemical models obtained from these methods may provide an alterative approach for determining thermal maturity of source rocks and crude oils, particularly in mature to highly mature Paleozoic carbonates. In addition, the extent of oil cracking was quantified using the concentrations of diamondoids in hydrous pyrolysates of rocks and peats, verifying that these hydrocarbons are valuable indicators of oil cracking in nature. ?? 2006 Elsevier Ltd. All rights

  15. Nano-sized Fe2O3/Fe3O4 facilitate anaerobic transformation of hexavalent chromium in soil-water systems.

    PubMed

    Zhang, Yaxian; Li, Hua; Gong, Libo; Dong, Guowen; Shen, Liang; Wang, Yuanpeng; Li, Qingbiao

    2017-07-01

    The purpose of this study is to investigate the effects of nano-sized or submicro Fe 2 O 3 /Fe 3 O 4 on the bioreduction of hexavalent chromium (Cr(VI)) and to evaluate the effects of nano-sized Fe 2 O 3 /Fe 3 O 4 on the microbial communities from the anaerobic flooding soil. The results indicated that the net decreases upon Cr(VI) concentration from biotic soil samples amended with nano-sized Fe 2 O 3 (317.1±2.1mg/L) and Fe 3 O 4 (324.0±22.2mg/L) within 21days, which were approximately 2-fold of Cr(VI) concentration released from blank control assays (117.1±5.6mg/L). Furthermore, the results of denaturing gradient gel electrophoresis (DGGE) and high-throughput sequencing indicated a greater variety of microbes within the microbial community in amendments with nano-sized Fe 2 O 3 /Fe 3 O 4 than the control assays. Especially, Proteobacteria occupied a predominant status on the phylum level within the indigenous microbial communities from chromium-contaminated soils. Besides, some partial decrease of soluble Cr(VI) in abiotic nano-sized Fe 2 O 3 /Fe 3 O 4 amendments was responsible for the adsorption of nano-sized Fe 2 O 3 /Fe 3 O 4 to soluble Cr(VI). Hence, the presence of nano-sized Fe 2 O 3 /Fe 3 O 4 could largely facilitate the mobilization and biotransformation of Cr(VI) from flooding soils by adsorption and bio-mediated processes. Copyright © 2017. Published by Elsevier B.V.

  16. Nanosized iron based permeable reactive barriers for nitrate removal - Systematic review

    NASA Astrophysics Data System (ADS)

    Araújo, Rui; Castro, Ana C. Meira; Santos Baptista, João; Fiúza, António

    2016-08-01

    It is unquestionable that an effective decision concerning the usage of a certain environmental clean-up technology should be conveniently supported. Significant amount of scientific work focussing on the reduction of nitrate concentration in drinking water by both metallic iron and nanomaterials and their usage in permeable reactive barriers has been worldwide published over the last two decades. This work aims to present in a systematic review of the most relevant research done on the removal of nitrate from groundwater using nanosized iron based permeable reactive barriers. The research was based on scientific papers published between 2004 and June 2014. It was performed using 16 combinations of keywords in 34 databases, according to PRISMA statement guidelines. Independent reviewers validated the selection criteria. From the 4161 records filtered, 45 met the selection criteria and were selected to be included in this review. This study's outcomes show that the permeable reactive barriers are, indeed, a suitable technology for denitrification and with good performance record but the long-term impact of the use of nanosized zero valent iron in this remediation process, in both on the environment and on the human health, is far to be conveniently known. As a consequence, further work is required on this matter, so that nanosized iron based permeable reactive barriers for the removal of nitrate from drinking water can be genuinely considered an eco-efficient technology.

  17. Generation of aliphatic acid anions and carbon dioxide by hydrous pyrolysis of crude oils

    USGS Publications Warehouse

    Kharaka, Y.K.; Lundegard, P.D.; Ambats, G.; Evans, William C.; Bischoff, J.L.

    1993-01-01

    Two crude oils with relatively high (0.60 wt%) and low (0.18 wt%) oxygen contents were heated in the presence of water in gold-plated reactors at 300??C for 2348 h. The high-oxygen oil was also heated at 200??C for 5711 h. The compositions of aqueous organic acid anions of the oils and of the headspace gases were monitored inn order to investigate the distribution of organic acids that can be generated from liquid petroleum. The oil with higher oxygen content generated about five times as much organic anions as the other oil. The dominant organic anions produced were acetate, propionate and butyrate. Small amounts of formate, succinate, methyl succinate and oxalate were also produced. The dominant oxygen-containing product was CO2, as has been observed in similar studies on the hydrous pyrolysis of kerogen. These results indicate that a significant portion (10-30%) of organic acid anions reported i be generated by thermal alteration of oils in reservoir rocks. The bulk of organic acid anions present in formation waters, however, is most likely generated by thermal alteration of kerogen in source rocks. Kerogen is more abundant than oil in sedimentary basins and the relative yields of organic acid anions reported from the hydrous pyrolysis of kerogen are much higher than the yields obtained for the two oils. ?? 1993.

  18. Nano-Sized Grain Refinement Using Friction Stir Processing

    DTIC Science & Technology

    2013-03-01

    friction stir weld is a very fine grain microstructure produced as a result of dynamic recrystallization. The friction stir ... Friction Stir Processing, Magnesium, Nano-size grains Abstract A key characteristic of a friction stir weld is a very fine grain microstructure...state process developed on the basis of the friction stir welding (FSW) technique invented by The Welding Institute (TWI) in 1991 [2]. During

  19. Determination of NH(3) gas by combination of nanosized LaCoO(3) converter with chemiluminescence detector.

    PubMed

    Shi, Jinjun; Yan, Ruoxue; Zhu, Yongfa; Zhang, Xinrong

    2003-10-17

    Combination of a novel NH(3) converter based on nanosized materials with chemiluminescence (CL) detector for the determination of NH(3) gas was demonstrated in this paper. NH(3) gas is oxidized on different nanosized catalysts to produce NO(x), which can react with luminol to generate CL emission. Eight nanosized materials were investigated as catalyst, and CL was detected from seven of them. The nanosized LaCoO(3) was chosen as the catalyst for preparing the converter because of its higher activity than others. Under the optimized conditions, the linear range of CL intensity versus concentration of NH(3) gas is 0.04-10 ppm (r=0.9951, n=14) with the detection limit of 0.014 ppm. The method offers advantages of long lifetime of the converter, fast response and high selectivity to NH(3). There was no response while the foreign substances, such as hydrogen, oxygen, nitrogen, formaldehyde, acetone and gasoline passing through the CL detection system, and the interference of CCl(4), ethanol, ethylene and toluene was insignificant.

  20. A strongly hydrated microclast in the Rumuruti chondrite NWA 6828: Implications for the distribution of hydrous material in the solar system

    NASA Astrophysics Data System (ADS)

    Greshake, Ansgar

    2014-05-01

    Hydrous carbonaceous microclasts are by far the most abundant foreign fragments in stony meteorites and mostly resemble CI1-, CM2-, or CR2-like material. Their occurrence is of great importance for understanding the distribution and migration of water-bearing volatile-rich matter in the solar system. This paper reports the first finding of a strongly hydrated microclast in a Rumuruti chondrite. The R3-6 chondrite Northwest Africa 6828 contains a 420 × 325 μm sized angular foreign fragment exhibiting sharp boundaries to the surrounding R-type matrix. The clast is dominantly composed of magnetite, pyrrhotite, rare Ca-carbonate, and very rare Mg-rich olivine set in an abundant fine-grained phyllosilicate-rich matrix. Phyllosilicates are serpentine and saponite. One region of the clast is dominated by forsteritic olivine (Fa<2) supported by a network of interstitial Ca-carbonate. The clast is crosscut by Ca-carbonate-filled veins and lacks any chondrules, calcium-aluminum-rich inclusions, or their respective pseudomorphs. The hydrous clast contains also a single grain of the very rare phosphide andreyivanovite. Comparison with CI1, CM2, and CR2 chondrites as well as with the ungrouped C2 chondrite Tagish Lake shows no positive match with any of these types of meteorites. The clast may, thus, either represent a fragment of an unsampled lithology of the hydrous carbonaceous chondrite parent asteroids or constitute a sample from an as yet unknown parent body, maybe even a comet. Rumuruti chondrites are a unique group of highly oxidized meteorites that probably accreted at a heliocentric distance >1 AU between the formation regions of ordinary and carbonaceous chondrites. The occurrence of a hydrous microclast in an R chondrite attests to the presence of such material also in this region at least at some point in time and documents the wide distribution of water-bearing (possibly zodiacal cloud) material in the solar system.

  1. Nanosized aerosols from consumer sprays: experimental analysis and exposure modeling for four commercial products

    NASA Astrophysics Data System (ADS)

    Lorenz, Christiane; Hagendorfer, Harald; von Goetz, Natalie; Kaegi, Ralf; Gehrig, Robert; Ulrich, Andrea; Scheringer, Martin; Hungerbühler, Konrad

    2011-08-01

    Consumer spray products are already on the market in the cosmetics and household sector, which suggest by their label that they contain engineered nanoparticles (ENP). Sprays are considered critical for human health, because the lungs represent a major route for the uptake of ENP into the human body. To contribute to the exposure assessment of ENP in consumer spray products, we analyzed ENP in four commercially available sprays: one antiperspirant, two shoe impregnation sprays, and one plant-strengthening agent. The spray dispersions were analyzed by inductively coupled plasma mass spectrometry (ICPMS) and (scanning-) transmission electron microscopy ((S)TEM). Aerosols were generated by using the original vessels, and analyzed by scanning mobility particle sizer (SMPS) and (S)TEM. On the basis of SMPS results, the nanosized aerosol depositing in the respiratory tract was modeled for female and male consumers. The derived exposure levels reflect a single spray application. We identified ENP in the dispersions of two products (shoe impregnation and plant spray). Nanosized aerosols were observed in three products that contained propellant gas. The aerosol number concentration increased linearly with the sprayed amount, with the highest concentration resulting from the antiperspirant. Modeled aerosol exposure levels were in the range of 1010 nanosized aerosol components per person and application event for the antiperspirant and the impregnation sprays, with the largest fraction of nanosized aerosol depositing in the alveolar region. Negligible exposure from the application of the plant spray (pump spray) was observed.

  2. Investigation of nanosized crystalline form to improve the oral bioavailability of poorly water soluble cilostazol.

    PubMed

    Miao, Xiaoqing; Sun, Changshan; Jiang, Tongying; Zheng, Li; Wang, Tianyi; Wang, Siling

    2011-01-01

    The aim of this study was to develop cilostazol (CLT) nanocrystals intended to improve its dissolution rate and enhance its bioavailability. In this study, CLT nanosuspension was prepared by the anti-solvent and high-pressure homogenization method. The effects of the production parameters, such as the stabilizer concentration, pressure and number of cycles, were investigated. Characterization of the product was performed by scanning electron microscopy (SEM), Nitrogen adsorption, differential scanning calorimetry (DSC), X-ray powder diffraction analysis (XRPD), X-ray Photoelectron Spectroscopy (XPS), particle size analysis and dissolution testing. Additionally, the comparison studies of oral bioavailability in beagle dogs of three type tables were performed. The images of SEM showed a spherical smooth CLT powder, and Nitrogen adsorption test revealed spray dried powder were porous with high BET surface area compared with that of raw CLT. DSC and XRPD results demonstrated that the combination of preferred polymorph B and C of CLT were prepared successfully, the saturation solubility of the nanosized crystalline powder is about 5 fold greater than that of raw CLT, and the dissolution rate was enhanced 4 fold than that of raw CLT. The Cmax and AUC0-48h of CLT nanosized crystalline tablets were 2.1 fold and 1.9 fold, and 3.0 fold and 2.3 fold compared with those of the nanosized tablets and commercial tablets, respectively. The anti-solvent-high-pressure homogenization technique was employed successfully to produce cilostazol nanosuspensions. The bioavailability of CLT tablets prepared using spray dried nanosized crystalline powder after oral administration to dogs was markedly increased compared with that produced by nanosized tablets and commercial tablets, because of its greater dissolution rate owing to its transition of the crystalline state to form C and form B, reduced particle size and porous structure with increased surface area.

  3. Iron and manganese oxides modified maize straw to remove tylosin from aqueous solutions.

    PubMed

    Yin, Yongyuan; Guo, Xuetao; Peng, Dan

    2018-08-01

    Maize straw modified by iron and manganese oxides was synthesized via a simple and environmentally friendly method. Three maize straw materials, the original maize straw, maize straw modified by manganese oxides and maize straw modified by iron and manganese oxides, were detected by SEM, BET, XPS, XRD and FTIR. The results showed that maize straw was successfully modified and maize straw modified by iron and manganese oxides has a larger surface area than MS. According to the experimental data, the sorption trend could conform to the pseudo-second-order kinetic model well, and the sorption ability of tylosin on sorbents followed the order of original maize straw < maize straw modified by manganese oxides < maize straw modified by iron and manganese oxides. The study indicated that manganese oxides and iron-manganese oxides could significantly enhance the sorption capacity of original maize straw. The sorption isotherm data of tylosin on original maize straw fit a linear model well, while Freundlich models were more suitable for maize straw modified by manganese oxides and maize straw modified by iron and manganese oxides. The pH, ionic strength and temperature can affect the sorption process. The sorption mechanisms of tylosin on iron and manganese oxides modified maize straw were attribute to the surface complexes, electrostatic interactions, H bonding and hydrophobic interactions. Copyright © 2018 Elsevier Ltd. All rights reserved.

  4. Spatial mapping of mineralization with manganese-enhanced magnetic resonance imaging

    USGS Publications Warehouse

    Chesnick, I.E.; Centeno, J.A.; Todorov, T.I.; Koenig, A.E.; Potter, K.

    2011-01-01

    Paramagnetic manganese can be employed as a calcium surrogate to sensitize the magnetic resonance imaging (MRI) technique to the processing of calcium during the bone formation process. At low doses, after just 48h of exposure, osteoblasts take up sufficient quantities of manganese to cause marked reductions in the water proton T1 values compared with untreated cells. After just 24h of exposure, 25??M MnCl2 had no significant effect on cell viability. However, for mineralization studies 100??M MnCl2 was used to avoid issues of manganese depletion in calvarial organ cultures and a post-treatment delay of 48h was implemented to ensure that manganese ions taken up by osteoblasts is deposited as mineral. All specimens were identified by their days in vitro (DIV). Using inductively coupled plasma optical emission spectroscopy (ICP-OES), we confirmed that Mn-treated calvariae continued to deposit mineral in culture and that the mineral composition was similar to that of age-matched controls. Notably there was a significant decrease in the manganese content of DIV18 compared with DIV11 specimens, possibly relating to less manganese sequestration as a result of mineral maturation. More importantly, quantitative T1 maps of Mn-treated calvariae showed localized reductions in T1 values over the calvarial surface, indicative of local variations in the surface manganese content. This result was verified with laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). We also found that ??R1 values, calculated by subtracting the relaxation rate of Mn-treated specimens from the relaxation rate of age-matched controls, were proportional to the surface manganese content and thus mineralizing activity. From this analysis, we established that mineralization of DIV4 and DIV11 specimens occurred in all tissue zones, but was reduced for DIV18 specimens because of mineral maturation with less manganese sequestration. In DIV25 specimens, active mineralization was observed for

  5. Characterizing thermogenic coalbed gas from Polish coals of different ranks by hydrous pyrolysis

    USGS Publications Warehouse

    Kotarba, M.J.; Lewan, M.D.

    2004-01-01

    To provide a better characterization of origin and volume of thermogenic gas generation from coals, hydrous pyrolysis experiments were conducted at 360??C for 72 h on Polish coals ranging in rank from lignite (0.3% R r) to semi-anthracite (2.0% Rr). Under these conditions, the lignites attained a medium-volatile bituminous rank (1.5% Rr), high-volatile bituminous coals attained a low-volatile bituminous rank (1.7% Rr), and the semi-anthracite obtained an anthracite rank (4.0% R r). Hydrous pyrolysis of a coal, irrespective of rank, provides a diagnostic ??13C value for its thermogenic hydrocarbon gases. This value can be used quantitatively to interpret mixing of indigenous thermogenic gas with microbial methane or exogenous thermogenic gas from other sources. Thermogenic methane quantities range from 20 dm3/kg of lignite (0.3% Rr) to 0.35 dm3/kg of semi-anthracite (2.0% Rr). At a vitrinite reflectance of 1.7% Rr, approximately 75% of the maximum potential for a coal to generate thermogenic methane has been expended. At a vitrinite reflectance of 1.7% Rr, more than 90% of the maximum potential for a coal to generate CO2 has been expended. Assuming that these quantities of generated CO2 remain associated with a sourcing coal bed as uplift or erosion provide conditions conducive for microbial methanogenesis, the resulting quantities of microbial methane generated by complete CO2 reduction can exceed the quantities of thermogenic methane generated from the same coal bed by a factor of 2-5. ?? 2004 Elsevier Ltd. All rights reserved.

  6. 40 CFR 721.10008 - Manganese strontium oxide (MnSrO3).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Manganese strontium oxide (MnSrO3... Specific Chemical Substances § 721.10008 Manganese strontium oxide (MnSrO3). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as manganese strontium oxide...

  7. 40 CFR 721.10008 - Manganese strontium oxide (MnSrO3).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Manganese strontium oxide (MnSrO3... Specific Chemical Substances § 721.10008 Manganese strontium oxide (MnSrO3). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as manganese strontium oxide...

  8. 40 CFR 721.10008 - Manganese strontium oxide (MnSrO3).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Manganese strontium oxide (MnSrO3... Specific Chemical Substances § 721.10008 Manganese strontium oxide (MnSrO3). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as manganese strontium oxide...

  9. 40 CFR 721.10008 - Manganese strontium oxide (MnSrO3).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Manganese strontium oxide (MnSrO3... Specific Chemical Substances § 721.10008 Manganese strontium oxide (MnSrO3). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as manganese strontium oxide...

  10. 40 CFR 721.10008 - Manganese strontium oxide (MnSrO3).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Manganese strontium oxide (MnSrO3... Specific Chemical Substances § 721.10008 Manganese strontium oxide (MnSrO3). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as manganese strontium oxide...

  11. Catalase-like activity studies of the manganese(II) adsorbed zeolites

    NASA Astrophysics Data System (ADS)

    ćiçek, Ekrem; Dede, Bülent

    2013-12-01

    Preparation of manganese(II) adsorbed on zeolite 3A, 4A, 5A. AW-300, ammonium Y zeolite, organophilic, molecular sieve and catalase-like enzyme activity of manganese(II) adsorbed zeolites are reported herein. Firstly zeolites are activated at 873 K for two hours before contact manganese(II) ions. In order to observe amount of adsorption, filtration process applied for the solution. The pure zeolites and manganese(II) adsorbed zeolites were analysed by FT-IR. As a result according to the FT-IR spectra, the incorporation of manganese(II) cation into the zeolite structure causes changes in the spectra. These changes are expected particularly in the pseudolattice bands connected with the presence of alumino and silicooxygen tetrahedral rings in the zeolite structure. Furthermore, the catalytic activities of the Mn(II) adsorbed zeolites for the disproportionation of hydrogen peroxide were investigated in the presence of imidazole. The Mn(II) adsorbed zeolites display efficiency in the disproportion reactions of hydrogen peroxide, producing water and dioxygen in catalase-like activity.

  12. Sol-gel synthesis and adsorption properties of mesoporous manganese oxide

    NASA Astrophysics Data System (ADS)

    Ivanets, A. I.; Kuznetsova, T. F.; Prozorovich, V. G.

    2015-03-01

    Sol-gel synthesis of mesoporous xerogels of manganese oxide with different phase compositions has been performed. The manganese oxide sols were obtained by redox reactions of potassium permanganate with hydrogen peroxide or manganese(II) chloride in aqueous solutions. The isotherms of the low-temperature adsorption-desorption of nitrogen with manganese oxide xerogels treated at 80, 200, 400, and 600°C were measured. The samples were studied by electron microscopy and thermal and XRD analysis. The phase transformation and the changes in the adsorption and capillary-condensation properties of manganese oxide were shown to depend on the sol synthesis conditions and the temperature of the thermal treatment of the gel. The X-ray amorphous samples heated at 80°C were shown to have low values of the specific surface; at higher temperatures, the xerogel crystallized into mixed phases with various compositions and its surface area increased at 200-400°C and decreased at 600°C.

  13. Matrix Infrared Spectra of Manganese and Iron Isocyanide Complexes.

    PubMed

    Chen, Xiuting; Li, Qingnuan; Andrews, Lester; Gong, Yu

    2017-11-22

    Mono and diisocyanide complexes of manganese and iron were prepared via the reactions of laser-ablated manganese and iron atoms with (CN) 2 in an argon matrix. Product identifications were performed based on the characteristic infrared absorptions from isotopically labeled (CN) 2 experiments as compared with computed values for both cyanides and isocyanides. Manganese atoms reacted with (CN) 2 to produce Mn(NC) 2 upon λ > 220 nm irradiation, during which MnNC was formed mainly as a result of the photoinduced decomposition of Mn(NC) 2 . Similar reaction products FeNC and Fe(NC) 2 were formed during the reactions of Fe and (CN) 2 . All the product molecules together with the unobserved cyanide isomers were predicted to have linear geometries at the B3LYP level of theory. The cyanide complexes of manganese and iron were computed to be more stable than the isocyanide isomers with energy differences between 0.4 and 4 kcal/mol at the CCSD(T) level. Although manganese and iron cyanide molecules are slightly more stable according to the theory, no absorption can be assigned to these isomers in the region above the isocyanides possibly due to their low infrared intensities.

  14. Intellectual impairment in school-age children exposed to manganese from drinking water.

    PubMed

    Bouchard, Maryse F; Sauvé, Sébastien; Barbeau, Benoit; Legrand, Melissa; Brodeur, Marie-Ève; Bouffard, Thérèse; Limoges, Elyse; Bellinger, David C; Mergler, Donna

    2011-01-01

    Manganese is an essential nutrient, but in excess it can be a potent neurotoxicant. Despite the common occurrence of manganese in groundwater, the risks associated with this source of exposure are largely unknown. Our first aim was to assess the relations between exposure to manganese from drinking water and children's intelligence quotient (IQ). Second, we examined the relations between manganese exposures from water consumption and from the diet with children's hair manganese concentration. This cross-sectional study included 362 children 6-13 years of age living in communities supplied by groundwater. Manganese concentration was measured in home tap water (MnW) and children's hair (MnH). We estimated manganese intake from water ingestion and the diet using a food frequency questionnaire and assessed IQ with the Wechsler Abbreviated Scale of Intelligence. The median MnW in children's home tap water was 34 µg/L (range, 1-2,700 µg/L). MnH increased with manganese intake from water consumption, but not with dietary manganese intake. Higher MnW and MnH were significantly associated with lower IQ scores. A 10-fold increase in MnW was associated with a decrease of 2.4 IQ points (95% confidence interval: -3.9 to -0.9; p < 0.01), adjusting for maternal intelligence, family income, and other potential confounders. There was a 6.2-point difference in IQ between children in the lowest and highest MnW quintiles. MnW was more strongly associated with Performance IQ than Verbal IQ. The findings of this cross-sectional study suggest that exposure to manganese at levels common in groundwater is associated with intellectual impairment in children.

  15. Manganese silicide nanowires on Si(001).

    PubMed

    Liu, H J; Owen, J H G; Miki, K; Renner, Ch

    2011-05-04

    A method for promoting the growth of manganese silicide nanowires on Si(001) at 450 °C is described. The anisotropic surface stress generated by bismuth nanolines blocks the formation of embedded structures and stabilizes the nucleation of manganese silicide islands which grow in a preferred direction, forming nanowires with a band gap of approximately 0.6 eV, matching the reported band gap of MnSi(1.7). This method may also provide a means to form silicide nanowires of other metals where they do not otherwise form. © 2011 IOP Publishing Ltd

  16. 40 CFR 721.10010 - Barium manganese oxide (BaMnO3).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Substances § 721.10010 Barium manganese oxide (BaMnO3). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as barium manganese oxide (BaMnO3) (PMN P-00... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Barium manganese oxide (BaMnO3). 721...

  17. 40 CFR 721.10010 - Barium manganese oxide (BaMnO3).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Substances § 721.10010 Barium manganese oxide (BaMnO3). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as barium manganese oxide (BaMnO3) (PMN P-00... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Barium manganese oxide (BaMnO3). 721...

  18. 40 CFR 721.10010 - Barium manganese oxide (BaMnO3).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Barium manganese oxide (BaMnO3). 721... Substances § 721.10010 Barium manganese oxide (BaMnO3). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as barium manganese oxide (BaMnO3) (PMN P-00...

  19. 40 CFR 721.10010 - Barium manganese oxide (BaMnO3).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Barium manganese oxide (BaMnO3). 721... Substances § 721.10010 Barium manganese oxide (BaMnO3). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as barium manganese oxide (BaMnO3) (PMN P-00...

  20. 40 CFR 721.10010 - Barium manganese oxide (BaMnO3).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Barium manganese oxide (BaMnO3). 721... Substances § 721.10010 Barium manganese oxide (BaMnO3). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as barium manganese oxide (BaMnO3) (PMN P-00...

  1. Synthesis of nanosize MCM-41 loaded with TiO 2 and study of its photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Sadjadi, M. S.; Farhadyar, N.; Zare, K.

    2009-07-01

    In recent years, nanosized mesoporous materials have received significant attention due to their impact in different processes. Several diverse applications of these materials, e.g. high density magnetic recording, magnetic fluids, magnetic refrigeration as well as in photocatalysis, solar cells, photosensors, have triggered considerable research activities in the area of nanotechnology. In this work, nanosize MCM-41 was synthesized and loaded then with TiO 2 using tetra butoxy titanium (TBT). As prepared TiO 2 loaded materials was investigated by using X-ray diffraction (XRD), Transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR). The photocatalytic activity of the prepared TiO 2 loaded MCM-41 was finally evaluated by the degradation of methyl orange under irradiation of UV light. The result showed that TiO 2 loaded on nanosize MCM-41 has higher photocatalytic activity than that of TiO 2.

  2. In vitro response of Heterobasidion annosum to manganese

    Treesearch

    W.J. Otrosina; B.L. Illman

    1994-01-01

    Manganese (Mn) is postulated to play a role in wood decay caused by certain basidiomycetes. We determined the in vitro response of Heterobasidion annosum (Fr.) Bref. to Mn and compared differences between three isolates each of the S and the P intersterility groups from the Western United States.On manganese-amended malt agar plates, H. annosum produced a brownish-...

  3. Synthesis of manganese stearate for high density polyethylene (HDPE) and its biodegradation

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Aras, Neny Rasnyanti M., E-mail: neny.rasnyanti@gmail.com; Arcana, I Made, E-mail: arcana@chem.itb.ac.id

    An oxidant additive is one type of additive used for oxo-biodegradable polymers. This additive was prepared by reaction multivalent transition metals and fatty acids to accelerate the degradation process of polymers by providing a thermal treatment or irradiation with light. This study focused on the synthesis of manganese stearate as an additive for application in High Density Polyethylene (HDPE), and the influence of manganese stearate on the characteristics of HDPE including their biodegradability. Manganese stearate was synthesized by the reaction of stearic acid with sodium hydroxide, and sodium stearate formed was reacted with manganese chloride tetrahydrate to form manganese stearatemore » with a melting point of 100-110 °C. Based on the FTIR spectrum showed absorption peak at wave number around 1560 cm{sup −1} which is an asymmetric vibration of CO functional group that binds to the manganese. The films of oxo-biodegradable polymer were prepared by blending HDPE and manganese stearate additives at various concentrations with using the polymer melting method, followed heating at a temperature of 50°C and 70°C for 10 days. The characterizations of the oxo-biodegradable polymers were carried out by analysis the functional groups (FTIR and ATR),thermal properties (TGA), surface properties (SEM), as well as analysis of the biodegradability (the biodegradation test by using activated sludge, % weight loss). Based on COi indicate that the additive of manganese stearate is active in oxidizing polymer by heating treatment. Results of biodegradation by microorganisms from activated sludge showed that the percentage weight loss of polymers increase with the increasing incubation time and the concentration of manganese stearate in HDPE. Biodegradability of HDPE with the addition of manganese stearate and followed by heating at a higher temperature was better observed. The highest percentage weight loss was obtained at the polymer with concentration of 0

  4. Synthesis of manganese stearate for high density polyethylene (HDPE) and its biodegradation

    NASA Astrophysics Data System (ADS)

    Aras, Neny Rasnyanti M.; Arcana, I. Made

    2015-09-01

    An oxidant additive is one type of additive used for oxo-biodegradable polymers. This additive was prepared by reaction multivalent transition metals and fatty acids to accelerate the degradation process of polymers by providing a thermal treatment or irradiation with light. This study focused on the synthesis of manganese stearate as an additive for application in High Density Polyethylene (HDPE), and the influence of manganese stearate on the characteristics of HDPE including their biodegradability. Manganese stearate was synthesized by the reaction of stearic acid with sodium hydroxide, and sodium stearate formed was reacted with manganese chloride tetrahydrate to form manganese stearate with a melting point of 100-110 °C. Based on the FTIR spectrum showed absorption peak at wave number around 1560 cm-1 which is an asymmetric vibration of CO functional group that binds to the manganese. The films of oxo-biodegradable polymer were prepared by blending HDPE and manganese stearate additives at various concentrations with using the polymer melting method, followed heating at a temperature of 50°C and 70°C for 10 days. The characterizations of the oxo-biodegradable polymers were carried out by analysis the functional groups (FTIR and ATR),thermal properties (TGA), surface properties (SEM), as well as analysis of the biodegradability (the biodegradation test by using activated sludge, % weight loss). Based on COi indicate that the additive of manganese stearate is active in oxidizing polymer by heating treatment. Results of biodegradation by microorganisms from activated sludge showed that the percentage weight loss of polymers increase with the increasing incubation time and the concentration of manganese stearate in HDPE. Biodegradability of HDPE with the addition of manganese stearate and followed by heating at a higher temperature was better observed. The highest percentage weight loss was obtained at the polymer with concentration of 0.2% manganese stearate

  5. Synergistic Heterobimetallic Manifold for Expedient Manganese(I)-Catalyzed C-H Cyanation.

    PubMed

    Liu, Weiping; Richter, Sven C; Mei, Ruhuai; Feldt, Milica; Ackermann, Lutz

    2016-12-12

    The manganese-catalyzed cyanation of inert C-H bonds was achieved within a heterobimetallic catalysis regime. The manganese(I) catalysis proved widely applicable and enabled C-H cyanations on indoles, pyrroles and thiophenes by facile C-H manganesation. The robustness of the manganese catalyst set the stage for the racemization-free C-H cyanation of amino acids with excellent levels of positional and chemo selectivity by the new cyanating agent NCFS. Experimental and computational mechanistic studies provided strong support for a synergistic heterobimetallic activation mode, facilitating the key C-C formation. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Influence of oxalic acid on the dissolution kinetics of manganese oxide

    NASA Astrophysics Data System (ADS)

    Godunov, E. B.; Artamonova, I. V.; Gorichev, I. G.; Lainer, Yu. A.

    2012-11-01

    The kinetics and electrochemical processes of the dissolution of manganese oxides with various oxidation states in sulfuric acid solutions containing oxalate ion additives is studied under variable conditions (concentration, pH, temperature). The parameters favoring a higher degree of the dissolution of manganese oxides in acidic media are determined. The optimal conditions are found for the dissolution of manganese oxides in acidic media in the presence of oxalate ions. The mechanism proposed for the dissolution of manganese oxides in sulfuric acid solutions containing oxalic acid is based on the results of kinetic and electrochemical studies. The steps of the dissolution mechanism are discussed.

  7. Reactions of metal ions at surfaces of hydrous iron oxide

    USGS Publications Warehouse

    Hem, J.D.

    1977-01-01

    Cu, Ag and Cr concentrations in natural water may be lowered by mild chemical reduction involving ferric hydroxide-ferrous ion redox processes. V and Mo solubilities may be controlled by precipitation of ferrous vanadate or molybdate. Concentrations as low as 10-8.00 or 10-9.00 M are readily attainable for all these metals in oxygen-depleted systems that are relatively rich in Fe. Deposition of manganese oxides such as Mn3O4 can be catalyzed in oxygenated water by coupling to ferrous-ferric redox reactions. Once formed, these oxides may disproportionate, giving Mn4+ oxides. This reaction produces strongly oxidizing conditions at manganese oxide surfaces. The solubility of As is significantly influenced by ferric iron only at low pH. Spinel structures such as chromite or ferrites of Cu, Ni, and Zn, are very stable and if locally developed on ferric hydroxide surfaces could bring about solubilities much below 10-9.00 M for divalent metals near neutral pH. Solubilities calculated from thermodynamic data are shown graphically and compared with observed concentrations in some natural systems. ?? 1977.

  8. Intellectual Impairment in School-Age Children Exposed to Manganese from Drinking Water

    PubMed Central

    Bouchard, Maryse F.; Sauvé, Sébastien; Barbeau, Benoit; Legrand, Melissa; Brodeur, Marie-Ève; Bouffard, Thérèse; Limoges, Elyse; Bellinger, David C.; Mergler, Donna

    2011-01-01

    Background Manganese is an essential nutrient, but in excess it can be a potent neurotoxicant. Despite the common occurrence of manganese in groundwater, the risks associated with this source of exposure are largely unknown. Objectives Our first aim was to assess the relations between exposure to manganese from drinking water and children’s intelligence quotient (IQ). Second, we examined the relations between manganese exposures from water consumption and from the diet with children’s hair manganese concentration. Methods This cross-sectional study included 362 children 6–13 years of age living in communities supplied by groundwater. Manganese concentration was measured in home tap water (MnW) and children’s hair (MnH). We estimated manganese intake from water ingestion and the diet using a food frequency questionnaire and assessed IQ with the Wechsler Abbreviated Scale of Intelligence. Results The median MnW in children’s home tap water was 34 μg/L (range, 1–2,700 μg/L). MnH increased with manganese intake from water consumption, but not with dietary manganese intake. Higher MnW and MnH were significantly associated with lower IQ scores. A 10-fold increase in MnW was associated with a decrease of 2.4 IQ points (95% confidence interval: −3.9 to −0.9; p < 0.01), adjusting for maternal intelligence, family income, and other potential confounders. There was a 6.2-point difference in IQ between children in the lowest and highest MnW quintiles. MnW was more strongly associated with Performance IQ than Verbal IQ. Conclusions The findings of this cross-sectional study suggest that exposure to manganese at levels common in groundwater is associated with intellectual impairment in children. PMID:20855239

  9. Effects of smectite on the oil-expulsion efficiency of the Kreyenhagen Shale, San Joaquin Basin, California, based on hydrous-pyrolysis experiments

    USGS Publications Warehouse

    Lewan, Michael D.; Dolan, Michael P.; Curtis, John B.

    2014-01-01

    The amount of oil that maturing source rocks expel is expressed as their expulsion efficiency, which is usually stated in milligrams of expelled oil per gram of original total organic carbon (TOCO). Oil-expulsion efficiency can be determined by heating thermally immature source rocks in the presence of liquid water (i.e., hydrous pyrolysis) at temperatures between 350°C and 365°C for 72 hr. This pyrolysis method generates oil that is compositionally similar to natural crude oil and expels it by processes operative in the subsurface. Consequently, hydrous pyrolysis provides a means to determine oil-expulsion efficiencies and the rock properties that influence them. Smectite in source rocks has previously been considered to promote oil generation and expulsion and is the focus of this hydrous-pyrolysis study involving a representative sample of smectite-rich source rock from the Eocene Kreyenhagen Shale in the San Joaquin Basin of California. Smectite is the major clay mineral (31 wt. %) in this thermally immature sample, which contains 9.4 wt. % total organic carbon (TOC) comprised of type II kerogen. Compared to other immature source rocks that lack smectite as their major clay mineral, the expulsion efficiency of the Kreyenhagen Shale was significantly lower. The expulsion efficiency of the Kreyenhagen whole rock was reduced 88% compared to that of its isolated kerogen. This significant reduction is attributed to bitumen impregnating the smectite interlayers in addition to the rock matrix. Within the interlayers, much of the bitumen is converted to pyrobitumen through crosslinking instead of oil through thermal cracking. As a result, smectite does not promote oil generation but inhibits it. Bitumen impregnation of the rock matrix and smectite interlayers results in the rock pore system changing from water wet to bitumen wet. This change prevents potassium ion (K+) transfer and dissolution and precipitation reactions needed for the conversion of smectite to

  10. Motoric impairment following manganese exposure in asteroid echinoderms.

    PubMed

    Sköld, Helen Nilsson; Baden, Susanne P; Looström, Jakob; Eriksson, Susanne P; Hernroth, Bodil E

    2015-10-01

    In the oceans, naturally occurring manganese (Mn) is released from the sediments during events of hypoxia. While neuro- and immuno-toxic effects of bioavailable manganese are well documented for crustaceans, studies of similar effects of manganese on other marine invertebrates are comparatively few. Here, we developed a new functional test "the repeated turning assay" to investigate if manganese exposure at ∼12 mg L(-1) affected motoric behaviour of two asteroid echinoderms, the Common sea star, Asterias rubens, and the Black brittle star, Ophiocomina nigra. By measuring of the turning-over capacity, from dorsal to ventral position, after one and two weeks of manganese exposure, we showed that for both species Mn exposure significantly delayed the ability to turn. After a recovery period of two weeks, the capacity of turning-over was not restored to that of unexposed animals neither for A. rubens nor for O. nigra. Further investigation of sea stars showed that Mn accumulated ∼5 fold in the tube feet, organs involved in their turning-over activity, and the high concentration remained after the recovery period. In the tube feet we also recorded an increased activity of acetylcholinesterase (AChE), here used as a proxy for neuromuscular disturbances. The results indicated that Mn induces neuromuscular disturbance in echinoderms which is important news, given that previous studies have concluded that adult echinoderms are relatively tolerant to Mn. Copyright © 2015 Elsevier B.V. All rights reserved.

  11. Modifications in Glass Ionomer Cements: Nano-Sized Fillers and Bioactive Nanoceramics

    PubMed Central

    Najeeb, Shariq; Khurshid, Zohaib; Zafar, Muhammad Sohail; Khan, Abdul Samad; Zohaib, Sana; Martí, Juan Manuel Nuñez; Sauro, Salvatore; Matinlinna, Jukka Pekka; Rehman, Ihtesham Ur

    2016-01-01

    Glass ionomer cements (GICs) are being used for a wide range of applications in dentistry. In order to overcome the poor mechanical properties of glass ionomers, several modifications have been introduced to the conventional GICs. Nanotechnology involves the use of systems, modifications or materials the size of which is in the range of 1–100 nm. Nano-modification of conventional GICs and resin modified GICs (RMGICs) can be achieved by incorporation of nano-sized fillers to RMGICs, reducing the size of the glass particles, and introducing nano-sized bioceramics to the glass powder. Studies suggest that the commercially available nano-filled RMGIC does not hold any significant advantage over conventional RMGICs as far as the mechanical and bonding properties are concerned. Conversely, incorporation of nano-sized apatite crystals not only increases the mechanical properties of conventional GICs, but also can enhance fluoride release and bioactivity. By increasing the crystallinity of the set matrix, apatites can make the set cement chemically more stable, insoluble, and improve the bond strength with tooth structure. Increased fluoride release can also reduce and arrest secondary caries. However, due to a lack of long-term clinical studies, the use of nano-modified glass ionomers is still limited in daily clinical dentistry. In addition to the in vitro and in vivo studies, more randomized clinical trials are required to justify the use of these promising materials. The aim of this paper is to review the modification performed in GIC-based materials to improve their physicochemical properties. PMID:27428956

  12. 40 CFR 721.10011 - Barium calcium manganese strontium oxide.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Barium calcium manganese strontium... Specific Chemical Substances § 721.10011 Barium calcium manganese strontium oxide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as barium calcium...

  13. 40 CFR 721.10011 - Barium calcium manganese strontium oxide.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Barium calcium manganese strontium... Specific Chemical Substances § 721.10011 Barium calcium manganese strontium oxide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as barium calcium...

  14. The sorption of silver by poorly crystallized manganese oxides

    USGS Publications Warehouse

    Anderson, B.J.; Jenne, E.A.; Chao, T.T.

    1973-01-01

    The sorption of silver by poorly crystallized manganese oxides was studied using synthesized samples of three members of the manganous manganite (birnessite) group, of different chemical composition and crystallinity, and a poorly organized ??-MnO2. All four oxides sorbed significant quantities of silver. The manganous manganites showed the greatest sorption (up to 0.5 moles silver/mole MnOx at pH 7) while the ??-MnO2 showed the least (0.3 moles silver/ mole MnOx at pH 7). Sorption of silver was adequately described by the Langmuir equation over a considerable concentration range. The relationship failed at low pH values and high equilibrium silver concentrations. The sorption capacity showed a direct relationship with pH. However, the rate of increase of sorption capacity decreased at the higher pH values. Silver sorption maxima. were not directly related to surface area but appeared to vary with the amount of occluded sodium and potassium present in the manganese oxide. The important processes involved in the uptake of silver by the four poorly crystallized manganese oxides ara considered to be surface exchange for manganese, potassium and sodium as well as exchange for structural manganese, potassium and sodium. ?? 1973.

  15. Low-spin manganese(II) and high-spin manganese(III) complexes derived from disalicylaldehyde oxaloyldihydrazone: Synthesis, spectral characterization and electrochemical studies

    NASA Astrophysics Data System (ADS)

    Syiemlieh, Ibanphylla; Kumar, Arvind; Kurbah, Sunshine D.; De, Arjune K.; Lal, Ram A.

    2018-01-01

    Low-spin manganese(II) complexes [MnII(H2slox)].H2O (1), [MnII(H2slox)(SL)] (where SL (secondary ligand) = pyridine (py, 2), 2-picoline (2-pic, 3), 3-picoline (3-pic, 4), and 4-picoline (4-pic, 5) and high-spin manganese(III) complex Na(H2O)4[MnIII(slox)(H2O)2].2.5H2O have been synthesized from disalicyaldehyde oxaloyldihydrazone in methanolic - water medium. The composition of complexes has been established by elemental analyses and thermoanalytical data. The structures of the complexes have been discussed on the basis of data obtained from molar conductance, UV visible, 1H NMR, infrared spectra, magnetic moment and electron paramagnetic resonance spectroscopic studies. Conductivity measurements in DMF suggest that the complexes (1-5) are non-electrolyte while the complex (6) is 1:1 electrolyte. The electronic spectral studies and magnetic moment data suggest five - coordinate square pyramidal structure for the complexes (2-5) and square planar geometry for manganese(II) in complex (1). In complex (6), both sodium and manganese(III) have six coordinate octahedral geometry. IR spectral studies reveal that the dihydrazone coordinates to the manganese centre in keto form in complexes (1-5) and in enol form in complex (6). In all complexes, the ligand is present in anti-cis configuration. Magnetic moment and EPR studies indicate manganese in +2 oxidation state in complexes (1-5), with low-spin square planar complex (1) and square pyramidal stereochemistries complexes (2-5) while in +3 oxidation state in high-spin distorted octahedral stereochemistry in complex (6). The complex (1) involves significant metal - metal interaction in the solid state. All of the complexes show only one metal centred electron transfer reaction in DMF solution in cyclic voltammetric studies. The complexes (1-5) involve MnII→MnI redox reaction while the complex (6) involves MnIII→MnII redox reaction, respectively.

  16. Six-coordinate manganese(3+) in catalysis by yeast manganese superoxide dismutase

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sheng, Yuewei; Gralla, Edith Butler; Schumacher, Mikhail

    Reduction of superoxide (O{sub 2}{sup -}) by manganese-containing superoxide dismutase occurs through either a 'prompt protonation' pathway, or an 'inner-sphere' pathway, with the latter leading to formation of an observable Mn-peroxo complex. We recently reported that wild-type (WT) manganese superoxide dismutases (MnSODs) from Saccharomyces cerevisiae and Candida albicans are more gated toward the 'prompt protonation' pathway than human and bacterial MnSODs and suggested that this could result from small structural changes in the second coordination sphere of manganese. We report here that substitution of a second-sphere residue, Tyr34, by phenylalanine (Y34F) causes the MnSOD from S. cerevisiae to react exclusivelymore » through the 'inner-sphere' pathway. At neutral pH, we have a surprising observation that protonation of the Mn-peroxo complex in the mutant yeast enzyme occurs through a fast pathway, leading to a putative six-coordinate Mn3+ species, which actively oxidizes O{sub 2}{sup -} in the catalytic cycle. Upon increasing pH, the fast pathway is gradually replaced by a slow proton-transfer pathway, leading to the well-characterized five-coordinate Mn{sup 3+}. We here propose and compare two hypothetical mechanisms for the mutant yeast enzyme, diffeeing in the structure of the Mn-peroxo complex yet both involving formation of the active six-coordinate Mn{sup 3+} and proton transfer from a second-sphere water molecule, which has substituted for the -OH of Tyr34, to the Mn-peroxo complex. Because WT and the mutant yeast MnSOD both rest in the 2+ state and become six-coordinate when oxidized up from Mn{sup 2+}, six-coordinate Mn{sup 3+} species could also actively function in the mechanism of WT yeast MnSODs.« less

  17. Prenatal co-exposure to manganese and depression and 24-months neurodevelopment.

    PubMed

    Muñoz-Rocha, Teresa Verenice; Tamayo Y Ortiz, Marcela; Romero, Martín; Pantic, Ivan; Schnaas, Lourdes; Bellinger, David; Claus-Henn, Birgit; Wright, Rosalind; Wright, Robert O; Téllez-Rojo, Martha María

    2018-01-01

    Normal prenatal neurodevelopment follows stages that are potentially influenced by both chemical and psychosocial environments. Exposure to elevated manganese during this critically vulnerable period has been found to be neurotoxic. Independently, maternal prenatal depression has been associated with subsequent neurodevelopmental decrements in children. The association between child neurodevelopment and prenatal co-exposure to manganese and maternal depression has not been sufficiently studied. During pregnancy and at birth, we measured maternal blood and cord blood manganese levels respectively. Maternal depression was assessed in the 3rd trimester of pregnancy using the Edinburgh Depression Scale. Neurodevelopment was evaluated at 24 months of age with the Bayley Scales of Infant Development. A multivariate multiple regression model was used to analyze cognitive, language and motor scores simultaneously for 473 children from the PROGRESS birth cohort in Mexico City. Over 25% of our study participants reported having depressive symptoms. 3rd trimester blood manganese as well as depressive symptoms were independently negatively associated with all neurodevelopment scores in adjusted models. In stratified analyses, the negative association between manganese (maternal as well as cord blood) and 24-month language scores was stronger among women with depressive symptoms. Receptive language was mostly affected. Inverted U-shaped curves were seen for the association between with cord blood manganese and neurodevelopment scores. Our findings are in line with previous studies of manganese and depression neurotoxicity. The prenatal period may be particularly sensitive to manganese and depression co-exposures and should be of interest for public health interventions to promote healthy emotional and nutritional pregnancies. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Silver manganese oxide electrodes for lithium batteries

    DOEpatents

    Thackeray, Michael M.; Vaughey, John T.; Dees, Dennis W.

    2006-05-09

    This invention relates to electrodes for non-aqueous lithium cells and batteries with silver manganese oxide positive electrodes, denoted AgxMnOy, in which x and y are such that the manganese ions in the charged or partially charged electrodes cells have an average oxidation state greater than 3.5. The silver manganese oxide electrodes optionally contain silver powder and/or silver foil to assist in current collection at the electrodes and to improve the power capability of the cells or batteries. The invention relates also to a method for preparing AgxMnOy electrodes by decomposition of a permanganate salt, such as AgMnO4, or by the decomposition of KMnO4 or LiMnO4 in the presence of a silver salt.

  19. Electronic structure and magnetic ordering in manganese hydride

    NASA Astrophysics Data System (ADS)

    Magnitskaya, M. V.; Kulikov, N. I.

    1991-03-01

    The self-consistent electron energy bands of antiferromagnetic (AFM) and non-magnetic manganese hydride are calculated using the linear muffintin orbital method (LMTO). The calculated values of equilibrium volume and of magnetic moment on the manganese site are in good agreement with experiment. The Fermi surface of paramagnetic MnH contains two nesting parts, and their superposition gives rise to AFM gap.

  20. New insights on timing of oil and gas generation in the central Gulf Coast interior zone based on hydrous-pyrolysis kinetic parameters

    USGS Publications Warehouse

    Lewan, Michael D.; Dutton, Shirley P.; Ruppel, Stephen C.; Hentz, Tucker F.

    2002-01-01

    Timing of oil and gas generation from Turonian and Smackover source rocks in the central Gulf CoastInterior Zone was determined in one-dimensional burial-history curves (BHCs) using hydrous-pyrolysis kinetic parameters. The results predict that basal Smackover source-rock intervals with Type-IIS kerogen completed oil generation between 121 and 99 Ma, and Turonian source-rocks with Type-II kerogen remain immature over most of the same area. The only exception to the latter occurs in the northwestern part of the Mississippi salt basin, where initial stages of oil generation have started as a result of higher thermal gradients. This maturity difference between Turonian and Smackover source rocks is predicted with present-day thermal gradients. Predicted oil generation prior to the Sabine and Monroe uplifts suggests that a significant amount of the oil emplaced in Cretaceous reservoirs of these uplifts would have been lost during periods of erosion. Hydrous-pyrolysis kineticparameters predict that cracking of Smackover oil to gas started 52 Ma, which postdates major uplift and erosional events of the Sabine and Monroe uplifts. This generated gas would accumulate and persist in these uplift areas as currently observed. The predicted timing of oil and gas generation with hydrous-pyrolysis kinetic parameters is in accordance with the observed scarcity of oil from Turonian source rocks, predominance of gas accumulations on the Sabine and Monroe uplifts, and predominance of oil accumulations along the northern rim of the Interior Zone.

  1. Timing of Neogene Manganese Deposit Formation in the Paleo-Japan Sea, northeast Japan

    NASA Astrophysics Data System (ADS)

    Ito, T.; Orihashi, Y.; Yanagisawa, Y.; Sakai, S.; Motoyama, I.; Kamikuri, S. I.; Komuro, K.; Suzuki, K.

    2017-12-01

    The generation ages of the two Neogene manganese deposits in northeast Japan were determined by diatom and radiolarian biostratigraphic analyses and zircon U-Pb dating. The manganese deposits analyzed were from the Kitaichi and Maruyama mines in the Fukaura district, northeast Japan. Manganese oxide layers of 0.5 m (Kitaichi) and 1.5 m (Maruyama) in thickness were predominantly composed of todorokite and occur conformably within volcanogenic sediments, which stratigraphically had correlated to middle Miocene in previous studies. The ages of the manganese oxide layers were 12.4 Ma. There was no time gap between the Kitaichi and the Maruyama manganese oxide layers, between the manganese oxide layer and the underlying tuffaceous sandstone in the Kitaichi mine, or within the manganese oxide layer of ca. 1.5 m thickness in the Maruyama mine. On the other hand, the overlying tuffaceous sandstone was dated at 4.5 Ma. The results suggest that the manganese oxide layers were formed immediately after the deposition of the tuffaceous sandstone at 12.4 Ma and that the restricted supply of volcanogenic and/or other detrital matter had kept for a long time (ca. 7 m.y.). The timing of the manganese deposit generation, 12.4 Ma, is identical to the age of the base of the Onnagawa Stage on the Nishikurosawa Stage in the Neogene stratotype section on the Japan Sea side, northeast Japan. And this is equivalent to the age of the start of diatom blooming. Paleogeographically, the manganese oxide deposition happened in a shallower area on a paleo-hill or a small island surrounded by stagnant mid to deep basins with diatom and organically carbon-rich, laminated, and fine-grained mud. It is highly probable that upwelling of mid to deep water rich in both dissolved manganese and nutrients is the trigger for the manganese deposit generation in shallower areas and the deposition of diatomaceous sediments in mid and deep basins. Eustatic regression might be the reason for the short

  2. Manganese-Catalyzed Carbonylative Annulations for Redox-Neutral Late-Stage Diversification.

    PubMed

    Liang, Yu-Feng; Steinbock, Ralf; Münch, Annika; Stalke, Dietmar; Ackermann, Lutz

    2018-05-04

    An inexpensive, nontoxic manganese catalyst enabled unprecedented redox-neutral carbonylative annulations under ambient pressure. The manganese catalyst outperformed all other typically used base and precious-metal catalysts. The outstanding versatility of the manganese catalysis manifold was reflected by ample substrate scope, setting the stage for effective late-stage manipulations under racemization-free conditions of a wealth of marketed drugs and natural products, including alkaloids, amino acids, steroids, and carbohydrates. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Manganese toxicity to chlorophyll synthesis in tobacco callus. [Nicotiana tabacum

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Clairmont, K.B.; Hagar, W.G.; Davis, E.A.

    1986-01-01

    Tobacco (Nicotiana tabacum) pith explants were grown on manganese containing medium. At moderate concentration (10 millimolar), manganese selectivity inhibited chlorophyll synthesis, resulting initially in growth of white callus. Several weeks later the white callus turned brown due to the accumulation of a pigment identified as protoporphyrin IX by its elution profile using high performance liquid chromatography, by its absorption spectrum, and by its fluorescence properties. At a concentration of 100 millimolar manganese the pigment accumulated without growth of the explant.

  4. Manganese oxide micro-supercapacitors with ultra-high areal capacitance

    NASA Astrophysics Data System (ADS)

    Wang, Xu; Myers, Benjamin D.; Yan, Jian; Shekhawat, Gajendra; Dravid, Vinayak; Lee, Pooi See

    2013-05-01

    A symmetric micro-supercapacitor is constructed by electrochemically depositing manganese oxide onto micro-patterned current collectors. High surface-to-volume ratio of manganese oxide and short diffusion distance between electrodes give an ultra-high areal capacitance of 56.3 mF cm-2 at a current density of 27.2 μA cm-2.A symmetric micro-supercapacitor is constructed by electrochemically depositing manganese oxide onto micro-patterned current collectors. High surface-to-volume ratio of manganese oxide and short diffusion distance between electrodes give an ultra-high areal capacitance of 56.3 mF cm-2 at a current density of 27.2 μA cm-2. Electronic supplementary information (ESI) available: Experimental procedures; optical images of micro-supercapacitors; areal capacitances of samples M-0.3C, M-0.6C and M-0.9C; illustration of interdigital finger electrodes; Nyquist plot of Co(OH)2 deposited on micro-electrodes. See DOI: 10.1039/c3nr00210a

  5. The desorption of antimony(V) from sediments, hydrous oxides, and clay minerals by carbonate, phosphate, sulfate, nitrate, and chloride.

    PubMed

    Biver, Marc; Krachler, Michael; Shotyk, William

    2011-01-01

    The desorption of antimony, Sb(V), from two sediment samples by phosphate, carbonate, sulfate, chloride, and nitrate at pH 8 was examined. One highly contaminated sediment sample was taken from an Sb mine (Goesdorf, Luxembourg); the other sample was the certified reference material PACS-2 (marine sediment). Phosphate was found to have a strong mobilizing ability, whereas that of carbonate was in general weaker. For comparison, and to understand better the possible importance of individual components of the sediments, desorption experiments were performed on pure phases (i.e., hydrous oxides of Fe, Mn, and Al) and the clay minerals kaolinite and montmorillonite. In the cases of hydrous metal oxides, Sb(V) was most effectively desorbed by phosphate, followed by carbonate. Phosphate also desorbed Sb(V) from the clay minerals, whereas carbonate had no effect. The pH dependence of adsorption of Sb(V) in the absence and presence of carbonate revealed that adsorption densities were higher (except in the case of montmorillonite) in the absence of carbonate, suggesting a competition between carbonate and [Sb(OH)] for surface sites generally and a lowering of surface charge in the case of hydrous aluminum oxide. The observations are unlikely to be due to ionic strength effects because activity coefficients in the blank and spiked solutions differ by <4%. Desorption experiments on sediments with varying concentrations of phosphate and carbonate demonstrated that at environmentally relevant concentrations, desorption by phosphate is negligible, whereas the effect of carbonate is not. Sulfate, chloride, and nitrate generally had little effect. The proportion of Sb desorbed in blank experiments coincides with that mobilized in the first fraction of the Bureau Communautaire de Référence (BCR) sequential extraction (easily exchangeable and carbonate-bound fraction). Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of

  6. Origin of Capacity Fading in Nano-Sized Co3O4 Electrodes: Electrochemical Impedance Spectroscopy Study

    NASA Astrophysics Data System (ADS)

    Kang, Jin-Gu; Ko, Young-Dae; Park, Jae-Gwan; Kim, Dong-Wan

    2008-10-01

    Transition metal oxides have been suggested as innovative, high-energy electrode materials for lithium-ion batteries because their electrochemical conversion reactions can transfer two to six electrons. However, nano-sized transition metal oxides, especially Co3O4, exhibit drastic capacity decay during discharge/charge cycling, which hinders their practical use in lithium-ion batteries. Herein, we prepared nano-sized Co3O4 with high crystallinity using a simple citrate-gel method and used electrochemical impedance spectroscopy method to examine the origin for the drastic capacity fading observed in the nano-sized Co3O4 anode system. During cycling, AC impedance responses were collected at the first discharged state and at every subsequent tenth discharged state until the 100th cycle. By examining the separable relaxation time of each electrochemical reaction and the goodness-of-fit results, a direct relation between the charge transfer process and cycling performance was clearly observed.

  7. Neurobehavioral function in school-age children exposed to manganese in drinking water.

    PubMed

    Oulhote, Youssef; Mergler, Donna; Barbeau, Benoit; Bellinger, David C; Bouffard, Thérèse; Brodeur, Marie-Ève; Saint-Amour, Dave; Legrand, Melissa; Sauvé, Sébastien; Bouchard, Maryse F

    2014-12-01

    Manganese neurotoxicity is well documented in individuals occupationally exposed to airborne particulates, but few data are available on risks from drinking-water exposure. We examined associations of exposure from concentrations of manganese in water and hair with memory, attention, motor function, and parent- and teacher-reported hyperactive behaviors. We recruited 375 children and measured manganese in home tap water (MnW) and hair (MnH). We estimated manganese intake from water ingestion. Using structural equation modeling, we estimated associations between neurobehavioral functions and MnH, MnW, and manganese intake from water. We evaluated exposure-response relationships using generalized additive models. After adjusting for potential confounders, a 1-SD increase in log10 MnH was associated with a significant difference of -24% (95% CI: -36, -12%) SD in memory and -25% (95% CI: -41, -9%) SD in attention. The relations between log10 MnH and poorer memory and attention were linear. A 1-SD increase in log10 MnW was associated with a significant difference of -14% (95% CI: -24, -4%) SD in memory, and this relation was nonlinear, with a steeper decline in performance at MnW > 100 μg/L. A 1-SD increase in log10 manganese intake from water was associated with a significant difference of -11% (95% CI: -21, -0.4%) SD in motor function. The relation between log10 manganese intake and poorer motor function was linear. There was no significant association between manganese exposure and hyperactivity. Exposure to manganese in water was associated with poorer neurobehavioral performances in children, even at low levels commonly encountered in North America.

  8. Process for the electrodeposition of low stress nickel-manganese alloys

    DOEpatents

    Kelly, James John; Goods, Steven Howard; Yang, Nancy Yuan-Chi; Cadden, Charles Henry

    2005-06-07

    A process for electrodepositing a low stress nickel-manganese multilayer alloy on an electrically conductive substrate is provided. The process includes the steps of immersing the substrate in an electrodeposition solution containing a nickel salt and a manganese salt and repeatedly passing an electric current through an immersed surface of the substrate. The electric current is alternately pulsed for predetermined durations between a first electrical current that is effective to electrodeposit nickel and a second electrical current that is effective to electrodeposit nickel and manganese. A multilayered alloy having adjacent layers of nickel and a nickel-manganese alloy on the immersed surface of the substrate is thereby produced. The resulting multilayered alloy exhibits low internal stress, high strength and ductility, and high strength retention upon exposure to heat.

  9. 76 FR 47996 - Cobalt Lithium Manganese Nickel Oxide; Significant New Use Rule

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-08-08

    ... 2070-AB27 Cobalt Lithium Manganese Nickel Oxide; Significant New Use Rule AGENCY: Environmental... lithium manganese nickel oxide (CAS No. 182442-95-1), which was the subject of premanufacture notice (PMN... 5(a)(2) (15 U.S.C. 2604(a)(2)) for the chemical substance identified as cobalt lithium manganese...

  10. The effect of spices and manganese on meat starter culture activity.

    PubMed

    Coventry, M J; Hickey, M W

    1993-01-01

    Three species, two proprietary spice blends and six starter preparations used in commercial salami manufacture were analysed for manganese and magnesium content. A mettwurst spices blend showed the highest levels of manganese (0·77 ppm expressed as effective product level assuming a 1% spice content) while mild and hot paprika and milano blend contained levels of manganese 1 4 - 1 3 lower. Magnesium levels for spices ranged from 3·14 to 25·81 ppm. Only two of the six meat starter cultures showed high levels of manganese (7·77 and 16·12 ppm as effective product level based on inoculation rate) while magnesium levels for all starter cultures did not exceed 0·37 ppm. The pH of salami products made with starter cultures containing no added manganese lagged behind that of products made with added mangenese (5 ppm) by 0·2 pH units at 48 h. The effect of manganese ions on the fermentation rate of starter bacteria was studied further in a salami model system, in the absence and presence of added spices. The mettwurst blend produced greatest stimulation and the milano the least. A level of 1·2 ppm of added manganese was sufficient to achieve an optimal (< 4·9 pH units within 48 h) fermentation in the presence of all five spices tested in the salami model system. Copyright © 1993. Published by Elsevier Ltd.

  11. Constrained Geometry Organotitanium Catalysts Supported on Nanosized Silica for Ethylene (co)Polymerization.

    PubMed

    Li, Kuo-Tseng; Wu, Ling-Huey

    2017-05-05

    Supported olefin polymerization catalysts can prevent reactor-fouling problems and produce uniform polymer particles. Constrained geometry complexes (CGCs) have less sterically hindered active sites than bis-cyclopentadienyl metallocene catalysts. In the literature, micrometer-sized silica particles were used for supporting CGC catalysts, which might have strong mass transfer limitations. This study aims to improve the activity of supported CGC catalysts by using nanometer-sized silica. Ti[(C₅Me₄)SiMe₂(N t Bu)]Cl₂, a "constrained-geometry" titanium catalyst, was supported on MAO-treated silicas (nano-sized and micro-sized) by an impregnation method. Ethylene homo-polymerization and co-polymerization with 1-octene were carried out in a temperature range of 80-120 °C using toluene as the solvent. Catalysts prepared and polymers produced were characterized. For both catalysts and for both reactions, the maximum activities occurred at 100 °C, which is significantly higher than that (60 °C) reported before for supported bis-cyclopentadienyl metallocene catalysts containing zirconium, and is lower than that (≥140 °C) used for unsupported Ti[(C₅Me₄)SiMe₂(N t Bu)]Me₂ catalyst. Activities of nano-sized catalyst were 2.6 and 1.6 times those of micro-sized catalyst for homopolymerization and copolymerization, respectively. The former produced polymers with higher crystallinity and melting point than the latter. In addition, copolymer produced with nanosized catalyst contained more 1-octene than that produced with microsized catalyst.

  12. Effect of fluoride toothpaste with nano-sized trimetaphosphate on enamel demineralization: An in vitro study.

    PubMed

    Danelon, Marcelle; Pessan, Juliano Pelim; Souza-Neto, Francisco Nunes; de Camargo, Emerson Rodrigues; Delbem, Alberto Carlos Botazzo

    2017-06-01

    This study evaluated the effect of toothpastes containing 1100ppm F associated or not with micrometric or nano-sized sodium trimetaphosphate (TMP) on enamel demineralization in vitro, using a pH cycling model. Bovine enamel blocks (4mm×4mm, n=96) were randomly allocated into eight groups (n=12), according to the test toothpastes: Placebo (without fluoride or TMP); 1100ppm F (1100F); 1100F plus micrometric TMP at concentrations of 1%, 3% or 6%; and 1100F plus nanosized TMP at 1%, 3% or 6%. Blocks were treated 2×/day with slurries of toothpastes and submitted to a pH cycling regimen for five days. Next, final surface hardness (SHf), integrated hardness loss (IHL), differential profile of integrated hardness loss (ΔIHL) and enamel fluoride (F) concentrations were determined. Data were analyzed by ANOVA and Student-Newman-Keuls' test (p<0.05). The use of 1100F/3%TMPnano led to SHf 30% higher (p<0.001) and IHL∼80% lower (p<0.001) when compared to 1100F. This toothpaste also resulted in ∼64% reduction of mineral loss (ΔIHL) when compared to 1100F. Moreover, the addition of nano-sized TMP promoted increases in enamel F uptake of 90%, 160% and 100%, respectively for the concentrations of 1%, 3% and 6%, when compared to 1100F (p<0.001). The addition of nano-sized TMP at 3% to a conventional toothpaste significantly decreased enamel demineralization when compared to its counterparts without TMP or supplemented with micrometric TMP. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Nanosizing of drugs: Effect on dissolution rate

    PubMed Central

    Dizaj, S. Maleki; Vazifehasl, Zh.; Salatin, S.; Adibkia, Kh.; Javadzadeh, Y.

    2015-01-01

    The solubility, bioavailability and dissolution rate of drugs are important parameters for achieving in vivo efficiency. The bioavailability of orally administered drugs depends on their ability to be absorbed via gastrointestinal tract. For drugs belonging to Class II of pharmaceutical classification, the absorption process is limited by drug dissolution rate in gastrointestinal media. Therefore, enhancement of the dissolution rate of these drugs will present improved bioavailability. So far several techniques such as physical and chemical modifications, changing in crystal habits, solid dispersion, complexation, solubilization and liquisolid method have been used to enhance the dissolution rate of poorly water soluble drugs. It seems that improvement of the solubility properties ofpoorly water soluble drugscan translate to an increase in their bioavailability. Nowadays nanotechnology offers various approaches in the area of dissolution enhancement of low aqueous soluble drugs. Nanosizing of drugs in the form of nanoparticles, nanocrystals or nanosuspensions not requiring expensive facilities and equipment or complicated processes may be applied as simple methods to increase the dissolution rate of poorly water soluble drugs. In this article, we attempted to review the effects of nanosizing on improving the dissolution rate of poorly aqueous soluble drugs. According to the reviewed literature, by reduction of drug particle size into nanometer size the total effective surface area is increased and thereby dissolution rate would be enhanced. Additionally, reduction of particle size leads to reduction of the diffusion layer thickness surrounding the drug particles resulting in the increment of the concentration gradient. Each of these process leads to improved bioavailability. PMID:26487886

  14. Immobilization of iron- and manganese-oxidizing bacteria with a biofilm-forming bacterium for the effective removal of iron and manganese from groundwater.

    PubMed

    Li, Chunyan; Wang, Shuting; Du, Xiaopeng; Cheng, Xiaosong; Fu, Meng; Hou, Ning; Li, Dapeng

    2016-11-01

    In this study, three bacteria with high Fe- and Mn-oxidizing capabilities were isolated from groundwater well sludge and identified as Acinetobacter sp., Bacillus megaterium and Sphingobacterium sp. The maximum removal ratios of Fe and Mn (99.75% and 96.69%) were obtained by an optimal combination of the bacteria at a temperature of 20.15°C, pH 7.09 and an inoculum size of 2.08%. Four lab-scale biofilters were tested in parallel for the removal of iron and manganese ions from groundwater. The results indicated that the Fe/Mn removal ratios of biofilter R4, which was inoculated with iron- and manganese-oxidizing bacteria and a biofilm-forming bacterium, were approximately 95% for each metal during continuous operation and were better than the other biofilters. This study demonstrated that the biofilm-forming bacterium could promote the immobilization of the iron- and manganese-oxidizing bacteria on the biofilters and enhance the removal efficiency of iron and manganese ions from groundwater. Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. Performance of point-of-use devices to remove manganese from drinking water.

    PubMed

    Carrière, Annie; Brouillon, Manon; Sauvé, Sébastien; Bouchard, Maryse F; Barbeau, Benoit

    2011-01-01

    A recent epidemiological study reported significant cognitive deficits among children in relation with consumption of water with manganese concentrations in the order of 50-100 ug/L. Concerns for neurotoxic effects of manganese raises the need for evaluating the efficiency of domestic water treatment systems for removal of this metal. The objective of the present study was to determine whether POU devices are efficient at reducing dissolved manganese concentration in drinking water. Various devices were tested according to the NSF 53 protocol for general metals for high pH test water. Based on these assays, the pour-through filters were identified as the most promising POU devices, with dissolved manganese removal greater than 60% at 100% rated capacity, and greater than 45% at 200% rated capacity (influent Mn ≈1,000 μg/L). Under-the-sink filters using cationic exchange resins (i.e., water softeners) were also efficient at removing dissolved manganese but over a shorter operating life. Manganese leaching was also observed beyond their rated capacity, making them less robust treatments. The activated carbon block filters and other proprietary technologies were found to be inappropriate for dissolved manganese removal. Further evaluation of POU devices performance should evaluate the impact of hardness on process performance. The impact of particulate Mn should also be evaluated.

  16. 40 CFR 721.4587 - Lithium manganese oxide (LiMn204) (generic name).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Lithium manganese oxide (LiMn204... Specific Chemical Substances § 721.4587 Lithium manganese oxide (LiMn204) (generic name). (a) Chemical... as lithium manganese oxide (LiMn204) (P-96-175) is subject to reporting under this section for the...

  17. 40 CFR 721.4587 - Lithium manganese oxide (LiMn204) (generic name).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Lithium manganese oxide (LiMn204... Specific Chemical Substances § 721.4587 Lithium manganese oxide (LiMn204) (generic name). (a) Chemical... as lithium manganese oxide (LiMn204) (P-96-175) is subject to reporting under this section for the...

  18. 40 CFR 721.4587 - Lithium manganese oxide (LiMn204) (generic name).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Lithium manganese oxide (LiMn204... Specific Chemical Substances § 721.4587 Lithium manganese oxide (LiMn204) (generic name). (a) Chemical... as lithium manganese oxide (LiMn204) (P-96-175) is subject to reporting under this section for the...

  19. 40 CFR 721.4587 - Lithium manganese oxide (LiMn204) (generic name).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Lithium manganese oxide (LiMn204... Specific Chemical Substances § 721.4587 Lithium manganese oxide (LiMn204) (generic name). (a) Chemical... as lithium manganese oxide (LiMn204) (P-96-175) is subject to reporting under this section for the...

  20. 40 CFR 721.4587 - Lithium manganese oxide (LiMn204) (generic name).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Lithium manganese oxide (LiMn204... Specific Chemical Substances § 721.4587 Lithium manganese oxide (LiMn204) (generic name). (a) Chemical... as lithium manganese oxide (LiMn204) (P-96-175) is subject to reporting under this section for the...

  1. First Principles Study for Proton Transport and Diffusion Behavior in Hydrous Hexagonal WO3

    NASA Astrophysics Data System (ADS)

    Liu, Chi-Ping; Zhou, Fei; Ozolins, Vidvuds; QPAM Team

    2013-03-01

    Proton transport is of great importance in biological species and energy storage and conversion systems. Previous studies have shown fast proton conduction in liquids and polymers but seldom in inorganic materials. In this work, first principles density functional theory (DFT) reveals that the formation of hydronium and water chains inside the hexagonal channels plays the key roles for the anomalously fast proton transport, by following modified Grotthuss mechanism. Our DFT study shows the detailed microscopic proton diffusion mechanism along the channel in hydrous WO3 with 50% water composition, which is proper for water chain formation. The water chain in the channel serves as a possible diffusion media for hydronium (H3O +) . With the continuous formation and cleavage of hydrogen bonds in the channel, the hydronium diffuses by hydrogen bonds exchange between water molecules. This mechanism is very similar with Grotthuss relay mechanism for proton transport in liquid. The possible proton diffusion were studied for hydronium is either far away from the water chain bond defect or next to H2O defect at the end of water chain. The diffusion barriers for both conditions are around 150 meV to 200 meV, and water defects reorganization in the chain is the rate-limited step for proton diffusion. These small diffusion barriers could explain the fast 1-D proton transport in hydrous WO3 channel. Further studies about fast proton transport in other inorganic materials could be an important topic in not only biochemistry but also clean energy applications like fuel cell applications.

  2. Neurobehavioral Function in School-Age Children Exposed to Manganese in Drinking Water

    PubMed Central

    Oulhote, Youssef; Mergler, Donna; Barbeau, Benoit; Bellinger, David C.; Bouffard, Thérèse; Brodeur, Marie-Ève; Saint-Amour, Dave; Legrand, Melissa; Sauvé, Sébastien

    2014-01-01

    Background: Manganese neurotoxicity is well documented in individuals occupationally exposed to airborne particulates, but few data are available on risks from drinking-water exposure. Objective: We examined associations of exposure from concentrations of manganese in water and hair with memory, attention, motor function, and parent- and teacher-reported hyperactive behaviors. Methods: We recruited 375 children and measured manganese in home tap water (MnW) and hair (MnH). We estimated manganese intake from water ingestion. Using structural equation modeling, we estimated associations between neurobehavioral functions and MnH, MnW, and manganese intake from water. We evaluated exposure–response relationships using generalized additive models. Results: After adjusting for potential confounders, a 1-SD increase in log10 MnH was associated with a significant difference of –24% (95% CI: –36, –12%) SD in memory and –25% (95% CI: –41, –9%) SD in attention. The relations between log10 MnH and poorer memory and attention were linear. A 1-SD increase in log10 MnW was associated with a significant difference of –14% (95% CI: –24, –4%) SD in memory, and this relation was nonlinear, with a steeper decline in performance at MnW > 100 μg/L. A 1-SD increase in log10 manganese intake from water was associated with a significant difference of –11% (95% CI: –21, –0.4%) SD in motor function. The relation between log10 manganese intake and poorer motor function was linear. There was no significant association between manganese exposure and hyperactivity. Conclusion: Exposure to manganese in water was associated with poorer neurobehavioral performances in children, even at low levels commonly encountered in North America. Citation: Oulhote Y, Mergler D, Barbeau B, Bellinger DC, Bouffard T, Brodeur ME, Saint-Amour D, Legrand M, Sauvé S, Bouchard MF. 2014. Neurobehavioral function in school-age children exposed to manganese in drinking water. Environ Health

  3. Effect of Manganese on some aspects of carbohydrate metabolism in rats. [None

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Husain, R.; Mushtaq, M.; Seth, P.K.

    1980-10-01

    Numerous biochemical and toxicological studies have indicated that chronic exposure to manganese leads to neurological abnormalities. Increasing use of manganese compounds as antiknocks in gasoline and diesel fuel has aroused a great concern over the toxicological potential of this metal and stressed the need for understanding the mechanism of its poisoning. Reports of alerations in the levels of biogenic amines have helped in understanding the basis of neurological disorders. However, little is known about the mechanism by which manganese exposure leads to hypoglycemia in workers. This study deals with the influence of manganese exposure on metabolism of glucose, the chiefmore » fuel of the brain, and some enzymes involved in its oxidation. These studies will provide an assessment of the extent to which manganese affects the various processes controlling carbohydrate metabolism.« less

  4. Low copper and high manganese levels in prion protein plaques

    USGS Publications Warehouse

    Johnson, Christopher J.; Gilbert, P.U.P.A.; Abrecth, Mike; Baldwin, Katherine L.; Russell, Robin E.; Pedersen, Joel A.; McKenzie, Debbie

    2013-01-01

    Accumulation of aggregates rich in an abnormally folded form of the prion protein characterize the neurodegeneration caused by transmissible spongiform encephalopathies (TSEs). The molecular triggers of plaque formation and neurodegeneration remain unknown, but analyses of TSE-infected brain homogenates and preparations enriched for abnormal prion protein suggest that reduced levels of copper and increased levels of manganese are associated with disease. The objectives of this study were to: (1) assess copper and manganese levels in healthy and TSE-infected Syrian hamster brain homogenates; (2) determine if the distribution of these metals can be mapped in TSE-infected brain tissue using X-ray photoelectron emission microscopy (X-PEEM) with synchrotron radiation; and (3) use X-PEEM to assess the relative amounts of copper and manganese in prion plaques in situ. In agreement with studies of other TSEs and species, we found reduced brain levels of copper and increased levels of manganese associated with disease in our hamster model. We also found that the in situ levels of these metals in brainstem were sufficient to image by X-PEEM. Using immunolabeled prion plaques in directly adjacent tissue sections to identify regions to image by X-PEEM, we found a statistically significant relationship of copper-manganese dysregulation in prion plaques: copper was depleted whereas manganese was enriched. These data provide evidence for prion plaques altering local transition metal distribution in the TSE-infected central nervous system.

  5. Influence of Fe content on the creep properties of olivine under anhydrous and hydrous conditions

    NASA Astrophysics Data System (ADS)

    Trimmer, M. B.; Zhao, Y.; Zimmerman, M. E.; Kohlstedt, D. L.

    2007-12-01

    High-temperature, high-pressure compressive creep experiments were performed on both wet and dry aggregates of Fa75 in a gas-medium deformation apparatus. The results from these experiments are compared with those for San Carlos olivine, Fa10, and our previous results on Fa30 and Fa50 in order to provide a basis for comparing convection models for the mantle of Earth with those for the more iron-rich mantle of Mars. Samples were fabricated from powders of Fa75 that were synthesized from mixtures of Fe2O3 and SiO2 combined with San Carlos olivine. The Fa75 powders were cold-pressed into Fe capsules and then hot-pressed at 300 MPa, 1473 K for 3 h. The average grain size of the resultant hot-pressed samples was ~40 μm. For experiments under hydrous conditions, three drops of deionized water were added before sealing the sample within telescoping Fe cans for deformation. Water bubbles were present both within olivine grains and along grain boundaries, demonstrating that the samples were water-saturated. Triaxial compressive creep experiments were carried out in a servo-controlled, internally heated gas-medium apparatus at 50 K intervals between 1273 and 1423 K and a confining pressure of 300 MPa with differential stress of 10 to 300 MPa. For each sample, creep tests were performed at several differential stresses at a constant temperature to determine the stress exponent or at several temperatures to determine the activation energy for creep. Under anhydrous conditions the viscosity of samples of Fa75 is more than a factor of 10 lower than the viscosity of Fa50. Previous experiments showed a similar relationship between Fa50 and Fa30 and Fa30 and Fa10. Under hydrous conditions the viscosity of samples of Fa75 are about a factor of 5 lower than the viscosity of Fa50, which is less than that observed between Fa50 and Fa30 or Fa30 and Fa10. The viscosity of a sample of a specific Fe:Mg ratio deformed under hydrous conditions is a factor of 10 lower than its counterpart

  6. The Manganese Health Research Program (MHRP): status report and future research needs and directions.

    PubMed

    Aschner, M; Lukey, B; Tremblay, A

    2006-09-01

    The manganese (Mn) research health program (MHRP) symposium was a full day session at the 22nd International Neurotoxicology Conference. Mn is a critical metal in many defense and defense-related private sector applications including steel making and fabrication, improved fuel efficiency, and welding, and a vital and large component in portable power sources (batteries). At the current time, there is much debate concerning the potential adverse health effects of the use of manganese in these and other applications. Due to the significant use of manganese by the Department of Defense, its contractors and its suppliers, the Manganese Health Research Program (MHRP) seeks to use the resources of the federal government, in tandem with manganese researchers, as well as those industries that are involved with manganese, to determine the exact health effects of manganese, as well as to devise proper safeguard measures for both public and private sector workers. Humans require manganese as an essential element; however, exposure to high levels of this metal is sometimes associated with adverse health effects, most notably within the central nervous system. Exposure scenarios vary extensively in relation to geographical location, urban versus rural environment, lifestyles, diet, and occupational setting. Furthermore, exposure may be brief or chronic, it may be to different types of manganese compounds (aerosols or salts of manganese with different physical and/or chemical properties), and it may occur at different life-stages (e.g., in utero, neonatal life, puberty, adult life, or senescence). These factors along with diverse genetic composition that imposes both a background and disease occurrence likely reflect on differential sensitivity of individuals to manganese exposure. Unraveling these complexities requires a multi-pronged research approach to address multiple questions about the role of manganese as an essential metal as well as its modulation of disease processes

  7. Targeted Therapy for Acute Autoimmune Myocarditis with Nano-Sized Liposomal FK506 in Rats.

    PubMed

    Okuda, Keiji; Fu, Hai Ying; Matsuzaki, Takashi; Araki, Ryo; Tsuchida, Shota; Thanikachalam, Punniyakoti V; Fukuta, Tatsuya; Asai, Tomohiro; Yamato, Masaki; Sanada, Shoji; Asanuma, Hiroshi; Asano, Yoshihiro; Asakura, Masanori; Hanawa, Haruo; Hao, Hiroyuki; Oku, Naoto; Takashima, Seiji; Kitakaze, Masafumi; Sakata, Yasushi; Minamino, Tetsuo

    2016-01-01

    Immunosuppressive agents are used for the treatment of immune-mediated myocarditis; however, the need to develop a more effective therapeutic approach remains. Nano-sized liposomes may accumulate in and selectively deliver drugs to an inflammatory lesion with enhanced vascular permeability. The aims of this study were to investigate the distribution of liposomal FK506, an immunosuppressive drug encapsulated within liposomes, and the drug's effects on cardiac function in a rat experimental autoimmune myocarditis (EAM) model. We prepared polyethylene glycol-modified liposomal FK506 (mean diameter: 109.5 ± 4.4 nm). We induced EAM by immunization with porcine myosin and assessed the tissue distribution of the nano-sized beads and liposomal FK506 in this model. After liposomal or free FK506 was administered on days 14 and 17 after immunization, the cytokine expression in the rat hearts along with the histological findings and hemodynamic parameters were determined on day 21. Ex vivo fluorescent imaging revealed that intravenously administered fluorescent-labeled nano-sized beads had accumulated in myocarditic but not normal hearts on day 14 after immunization and thereafter. Compared to the administration of free FK506, FK506 levels were increased in both the plasma and hearts of EAM rats when liposomal FK506 was administered. The administration of liposomal FK506 markedly suppressed the expression of cytokines, such as interferon-γ and tumor necrosis factor-α, and reduced inflammation and fibrosis in the myocardium on day 21 compared to free FK506. The administration of liposomal FK506 also markedly ameliorated cardiac dysfunction on day 21 compared to free FK506. Nano-sized liposomes may be a promising drug delivery system for targeting myocarditic hearts with cardioprotective agents.

  8. Origin of hydrous alkali feldspar-silica intergrowth in spherulites from intra-plate A2-type rhyolites at the Jabal Shama, Saudi Arabia

    NASA Astrophysics Data System (ADS)

    Surour, Adel A.; El-Nisr, Said A.; Bakhsh, Rami A.

    2016-03-01

    Miocene rhyolites (19.2 ± 0.9 Ma) at the Jabal Shama in western Saudi Arabia represent an example of rift-related silicic volcanism that took place during the formation of the Red Sea. They mostly consist of tuffaceous varieties with distinct flow banding, and pea-sized spherulites, obsidian and perlitized rhyolite tuffs. Although they have the geochemical signature of A2-type rhyolites, these silicic rocks are not typically alkaline but alkali-calcic to calc-alkaline. They developed in a within-plate regime and possibly derived from a recycled mafic subducted slab in depleted sub-continental mantle beneath the western Arabian plate. The Jabal Shama rhyolites are younger in age than their Miocene counterparts in Yemen and Ethiopia. The Jabal Shama spherulites consist of hydrous alkali feldspar-silica radial intergrowths with an occasional brown glass nucleus. Carbonate- and glass-free spherulites give up to 4.45 wt% L.O.I. The hydrous nature of these silicates and the absence of magnetite in the spherulites is a strong indication of oxidizing conditions. The spherulites contain hydrous feldspars with up to ∼6 wt% H2O, and they develop by diffusion and devitrification of glass in the rhyolite tuff at ∼800 °C. Owing to higher undercooling due to supersaturation, the radial hydrous phases within spherulites might grow faster and led to coagulation. The polygonal contacts between spherulites and the ∼120° dihedral angle suggest solid-state modification and recrystallization as the process of devitrification proceeds as low as ∼300 °C. The sum of FeO + MgO is positively correlated with total alkalies along with magnetite oxidation in the matrix to Fe-oxyhydroxides, and to the incorporation of OH- into silicates within the spehrulites themselves. Structural H2O in glass of the Jabal Shama perlite (obsidian) is considerable (∼9-12 wt%) with 3.72-5.6 wt% L.O.I. of the whole-rock. The presence of deleterious silica impurities would lower the ore grade due to

  9. Iron and manganese oxide mineralization in the Pacific

    USGS Publications Warehouse

    Hein, J. R.; Koschinsky, A.; Halbach, P.; Manheim, F. T.; Bau, M.; Jung-Keuk, Kang; Lubick, N.

    1997-01-01

    Iron, manganese, and iron-manganese deposits occur in nearly all geomorphologic and tectonic environments in the ocean basins and form by one or more of four processes: (1) hydrogenetic precipitation from cold ambient seawater, (2) precipitation from hydrothermal fluids, (3) precipitation from sediment pore waters that have been modified from bottom water compositions by diagenetic reactions in the sediment column and (4) replacement of rocks and sediment. These processes are discussed.

  10. The Chassigny meteorite - A cumulate dunite with hydrous amphibole-bearing melt inclusions

    NASA Technical Reports Server (NTRS)

    Floran, R. J.; Prinz, M.; Hlava, P. F.; Keil, K.; Nehru, C. E.; Hinthorne, J. R.

    1978-01-01

    The Chassigny meteorite, an iron-rich dunite (Fo 68), is a moderately shocked olivine achondrite or chassignite with features indicative of a cumulate origin with some subsolidus annealing. The evidence that the meteorite experienced shock pressures of approximately 150-200 kbar is described. Kaersutitic amphibole, found only in melt inclusions, represents the first extraterrestrial occurence of hydrous amphibole and the first meteoritic amphibole type other than fluorichterite. Fractionation data indicate that Chassigny formed under relatively more oxidizing conditions than most other achondrites, which implies that its parental melt could not have been directly derived from a chondritic composition in a simple single-stage process. Similarities and differences with the Brachina meteorite, the only other meteorite of the Chassigny type, are considered.

  11. Partitioning of Mg, Ca, and Na between carbonatite melt and hydrous fluid at 0.1-0.2 GPa

    NASA Astrophysics Data System (ADS)

    Veksler, Ilya V.; Keppler, Hans

    Experimental studies of the element distribution between carbonatite melts and hydrous fluids are hampered by the fact that neither the fluid nor the melt can be isochemically quenched in conventional high-pressure vessels. In order to overcome this problem, we used a double-capsule technique to separate immiscible fluid and melt phases during and after the runs. The inner platinum capsules were charged with carbonate mixtures (CaCO3, MgCO3 and Na2CO3) and placed inside the outer capsules charged with distilled water and diamond powder. The latter was used as an inert trap for solids precipitating from the fluid on quenching. Carbonate melt and hydrous fluid equilibrated through a small hole left in the upper end of the inner capsule. The runs were performed in rapid-quench cold-seal pressure vessels at 0.1-0.2 GPa and 700-900°C in the two-phase (fluid+melt) stability region. Both quenched melt and quenched fluid were dissolved in dilute HCl and analysed by inductively coupled plasma atomic emission spectroscopy. The results show that under all conditions investigated, fluid/melt partition coefficients for Ca and Mg are similar and several times smaller than those for Na. At 0.1 GPa and a water/carbonatite ratio of 1 (by weight), the partition coefficients are DNa= 0.35+/- 0.02, DCa=0.09+/-0.02, and DMg=0.13+/- 0.01. Between 700 and 900°C, the effect of temperature on partitioning is negligible. However, DNa increases significantly with decreasing water/carbonatite ratio in the system. Our data show that the release of a hydrous fluid enriched in sodium and simultaneous crystallisation of calcite can transform an alkaline, vapour-saturated carbonatite melt into a body of pure calcite surrounded by zones of sodium metasomatism. Thus, it is quite possible that carbonate magmas with substantial amounts of alkalies were common parental liquids of plutonic carbonatites.

  12. Sub-chronic inhalation of high concentrations of manganese sulfate induces lower airway pathology in rhesus monkeys

    PubMed Central

    Dorman, David C; Struve, Melanie F; Gross, Elizabeth A; Wong, Brian A; Howroyd, Paul C

    2005-01-01

    Background Neurotoxicity and pulmonary dysfunction are well-recognized problems associated with prolonged human exposure to high concentrations of airborne manganese. Surprisingly, histological characterization of pulmonary responses induced by manganese remains incomplete. The primary objective of this study was to characterize histologic changes in the monkey respiratory tract following manganese inhalation. Methods Subchronic (6 hr/day, 5 days/week) inhalation exposure of young male rhesus monkeys to manganese sulfate was performed. One cohort of monkeys (n = 4–6 animals/exposure concentration) was exposed to air or manganese sulfate at 0.06, 0.3, or 1.5 mg Mn/m3 for 65 exposure days. Another eight monkeys were exposed to manganese sulfate at 1.5 mg Mn/m3 for 65 exposure days and held for 45 or 90 days before evaluation. A second cohort (n = 4 monkeys per time point) was exposed to manganese sulfate at 1.5 mg Mn/m3 and evaluated after 15 or 33 exposure days. Evaluations included measurement of lung manganese concentrations and evaluation of respiratory histologic changes. Tissue manganese concentrations were compared for the exposure and control groups by tests for homogeneity of variance, analysis of variance, followed by Dunnett's multiple comparison. Histopathological findings were evaluated using a Pearson's Chi-Square test. Results Animals exposed to manganese sulfate at ≥0.3 mg Mn/m3 for 65 days had increased lung manganese concentrations. Exposure to manganese sulfate at 1.5 mg Mn/m3 for ≥15 exposure days resulted in increased lung manganese concentrations, mild subacute bronchiolitis, alveolar duct inflammation, and proliferation of bronchus-associated lymphoid tissue. Bronchiolitis and alveolar duct inflammatory changes were absent 45 days post-exposure, suggesting that these lesions are reversible upon cessation of subchronic high-dose manganese exposure. Conclusion High-dose subchronic manganese sulfate inhalation is associated with increased

  13. The Escherichia coli Small Protein MntS and Exporter MntP Optimize the Intracellular Concentration of Manganese

    PubMed Central

    Martin, Julia E.; Waters, Lauren S.; Storz, Gisela; Imlay, James A.

    2015-01-01

    Escherichia coli does not routinely import manganese, but it will do so when iron is unavailable, so that manganese can substitute for iron as an enzyme cofactor. When intracellular manganese levels are low, the cell induces the MntH manganese importer plus MntS, a small protein of unknown function; when manganese levels are high, the cell induces the MntP manganese exporter and reduces expression of MntH and MntS. The role of MntS has not been clear. Previous work showed that forced MntS synthesis under manganese-rich conditions caused bacteriostasis. Here we find that when manganese is scarce, MntS helps manganese to activate a variety of enzymes. Its overproduction under manganese-rich conditions caused manganese to accumulate to very high levels inside the cell; simultaneously, iron levels dropped precipitously, apparently because manganese-bound Fur blocked the production of iron importers. Under these conditions, heme synthesis stopped, ultimately depleting cytochrome oxidase activity and causing the failure of aerobic metabolism. Protoporphyrin IX accumulated, indicating that the combination of excess manganese and iron deficiency had stalled ferrochelatase. The same chain of events occurred when mutants lacking MntP, the manganese exporter, were exposed to manganese. Genetic analysis suggested the possibility that MntS exerts this effect by inhibiting MntP. We discuss a model wherein during transitions between low- and high-manganese environments E. coli uses MntP to compensate for MntH overactivity, and MntS to compensate for MntP overactivity. PMID:25774656

  14. Dispersion of nanosized ceramic powders in aqueous suspensions

    NASA Astrophysics Data System (ADS)

    Chera, L.; Palcevskis, E.; Berzins, M.; Lipe, A.; Jansone, I.

    2007-12-01

    Seven commercially available dispersants have been applied to produce high concentrated aqueous suspensions of the nanosized alumina and partially stabilized zirconia powders processed by the plasma technique. Simultaneously, the electrokinetic behaviour of powders has been investigated in diluted suspensions by microelectrophoresis method. Zeta potential measurements are used to estimate the influence of selected dispersants on the electrokinetic properties of the powder surface. On the basis of obtained data the correlation between the surface electrokinetic properties in dilute suspensions and reached maximal suspension concentration is discussed.

  15. The nature of nano-sized precipitates in ferritic/martensitic steel P92 produced by thermomechanical treatment

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Shen, Yinzhong, E-mail: shenyz@sjtu.edu.cn

    Thermomechanical treatment (TMT) can effectively improve the mechanical properties of high-Cr ferritic/martensitic (F/M) steels, which has been mainly attributed to a dense dispersion of nano-sized precipitates. Precipitate phases in high-Cr F/M steels produced by TMT require further investigations. Precipitates in commercial F/M steel P92 produced by a TMT process, warm-rolled at 650 °C plus tempered at 650 °C for 1 h, were investigated by transmission electron microscopy. Nano-sized precipitates with a high number density in the steel after the TMT were found to be Cr-rich M{sub 2}(C,N) carbonitride, rather than MX or M{sub 23}C{sub 6} phase. The M{sub 2}(C,N) carbonitridemore » has a hexagonal lattice with the lattice parameters about a/c = 0.299/0.463 nm. These M{sub 2}(C,N) carbonitrides with a typical composition of (Cr{sub 0.85}V{sub 0.06}Fe{sub 0.06}Mo{sub 0.03}){sub 2}(C,N) have an average diameter smaller than 30 nm, and mainly distribute on dislocations and at the boundaries of equiaxed ferrite grains in the TMT steel. The TMT process inhibits the precipitation of M{sub 23}C{sub 6} and M{sub 5}C{sub 2} phases. Enhanced creep properties of the P92 steel after the TMT, as reported previously, were considered to be mainly attributed to plenty of nano-sized Cr-rich M{sub 2}(C,N) carbonitrides produced by the TMT rather than to MX and M{sub 23}C{sub 6} precipitates. - Graphical abstract: TEM micrographs of precipitates on extraction carbon replicas prepared from ferritic/martensitic (F/M) steel P92. (a) After conventional heat treatment, normalized at 1050 °C for 30 min plus tempered at 765 °C for 1 h. (b) After a thermomechanical treatment (TMT), warm-rolled at 650 °C plus tempered at 650 °C for 1 h. Nano-sized precipitates with a high number density in the steel produced by the TMT were found to be Cr-rich M{sub 2}(C,N) carbonitride, rather than MX or M{sub 23}C{sub 6} phase. The TMT process inhibits the precipitation of M{sub 23}C{sub 6} and M

  16. NANOSIZE TITANIA STIMULATES REACTIVE OXYGEN SPECIES IN BRAIN MICROGLIA AND DAMAGES NEURONS.

    EPA Science Inventory

    Research that addresses the environmental impact and biological consequences of widely distributed, commonly used nanoparticles is needed. Nanosize titanium dioxide (i.e., titania, TiO2) is used in air and water remediation and in numerous products designed for direct human us...

  17. Manganese: it turns iron into steel (and does so much more)

    USGS Publications Warehouse

    Cannon, William F.

    2014-01-01

    Manganese is a common ferrous metal with atomic weight of 25 and the chemical symbol Mn. It constitutes roughly 0.1 percent of the Earth’s crust, making it the 12th most abundant element. Its early uses were limited largely to pigments and oxidants in chemical processes and experiments, but the significance of manganese to human societies exploded with the development of modern steelmaking technology in the 1860s. U.S consumption of manganese is about 500,000 metric tons each year, predominantly by the steel industry. Because manganese is essential and irreplaceable in steelmaking and its global mining industry is dominated by just a few nations, it is considered one of the most critical mineral commodities for the United States.

  18. Microbial oxidation and reduction of manganese: consequences in groundwater and applications.

    PubMed

    Gounot, A M

    1994-08-01

    In the natural environment, manganese is found as reduced soluble or adsorbed Mn(II) and insoluble Mn(III) and Mn(IV) oxides. Mn oxidation has been reported in various microorganisms. Several possible pathways, indirect or direct, have been proposed. A wider variety of Mn-reducing microorganisms, from highly aerobic to strictly anaerobic, has been described. The mechanisms of Mn reduction can be either an indirect process resulting from interactions with organic or inorganic compounds, or a direct enzymatic (electron-transfer) reaction. The role of microorganisms in Mn cycle is now well demonstrated by various methods in superficial natural environments, and research has been initiated on subsurface sediments. Observations in vivo (Rhône valley) and under in vitro suggested that bacterial activities are the main processes that promote manganese evolution and migration in shallow aquifers. After the building of hydroelectric dams, the stream of the Rhône was modified, giving rise to mud deposition on the bank. In the mud, bacteria are stimulated by the high organic content and consume oxygen. The redox potential drops. The manganese oxides previously formed under aerobic conditions are reduced and soluble manganese (Mn(II)) migrates into the aquifer. If the subsurface sediments are coarse-grained, the aquifer is well aerated, allowing the re-oxidation of Mn(II) by the oligotrophic attached bacteria in aquifer sediments. If the aquifer is confined, aeration is not sufficient for Mn-reoxidation. Mn(II) remains in a reduced state and migrates to the wells. Furthermore, the presence of organic matter in subsurface sediments results in the reduction of previously formed Mn oxides. Pseudo-amorphous manganese oxides, which were probably recently formed by bacteria, are more readily reduced than old crystalline manganese oxides. Although the concentrations of soluble manganese found in groundwaters are not toxic, it still is a problem since its oxidation results in

  19. Hydrous metasomatism of oceanic sub-arc mantle, Lihir, Papua New Guinea. Part 2. Trace element characteristics of slab-derived fluids

    NASA Astrophysics Data System (ADS)

    Grégoire, Michel; McInnes, Brent I. A.; O'Reilly, Suzanne Y.

    2001-11-01

    Spinel peridotite xenoliths recovered from the Tubaf and Edison volcanoes, south of Lihir Island in the Tabar-Lihir-Tanga-Feni island arc in Papua New Guinea, are predominantly fresh, refractory harzburgites. Many of the harzburgite xenoliths have cross-cutting vein networks and show evidence of modal metasomatism. These metasomatic veins contain a secondary mineral assemblage consisting of fibrous, radiating orthopyroxene and fine-grained Fe-Ni sulfide with minor olivine, clinopyroxene, phlogopite, amphibole and magnetite. Adjacent to the veins, primary clinopyroxene is cloudy while orthopyroxene exhibits replacement by secondary fibrous orthopyroxene, similar in habit to orthopyroxene occurring in the veins. The mineralogical and geochemical characteristics of the Tubaf mantle xenoliths are the product of two major processes: an early partial melting depletion event that was overprinted by oxidation and alkali enrichment related to percolation of slab-derived, hydrous melts. HREE and MREE concentrations in clinopyroxene from the least metasomatised harzburgites indicate that they are the residues from a 15% to 25% partial melting event, consistent with formation in a MOR setting. The secondary vein assemblages show strong enrichment in the LILE (primarily Sr, Ba, Rb, Th, U and Pb) and the REE (primarily La, Ce, Nd, Sm, Eu and Gd), while the HFSE (Nb, Ta, Zr, Hf, and Ti) are neither enriched nor depleted. The mineral precipitates in the vein assemblages have high LREE/HFSE and LILE/HFSE, and reflect the relative solubility of these elements in hydrous melts. These trace element characteristics are similar to those of the Tabar-Lihir-Tanga-Feni arc lavas, and display the commonly observed HFSE depletion of arc magmatism. These findings support the hypothesis that this so-called "arc signature" is primarily dependent on the relative solubility of elements in slab-derived, hydrous melts, and the enrichment of these soluble elements in metasomatised mantle regions

  20. Inhibition of chlorophyll synthesis and carotenoid accumulation by manganese and cobalt

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Clairmont, K.B.; Davis, E.; Hagar, W.

    1986-05-01

    The authors have developed methods for the separation and identification of the major pigments of the photosynthetic apparatus in plants using reversed phase microbore high performance liquid chromatography. Using these methods they have monitored the concentrations of pigments in tissue cultured tobacco callus in the absence and presence of excess manganese and cobalt. Manganese and cobalt were reported to inhibit chlorophyll synthesis in blue green algae. They have found that excess manganese blocks chlorophyll synthesis in tobacco callus also. In the manganese inhibited callus there is an increase in the concentration of protoporphyrin IX- the last common precursor to bothmore » the chlorophyll and heme synthetic pathways. They have found that cobalt also blocks chlorophyll synthesis in tissue cultured tobacco callus, but at a much lower concentration. In addition to the inhibition of chlorophyll synthesis by excess manganese and cobalt, the accumulation of carotenoids is reduced by several orders of magnitude in this tissue. The absence of chlorophyll may prevent assembly of any components of the photosynthetic apparatus in these cells.« less

  1. Development of a field method for measuring manganese in welding fume.

    PubMed

    Dale Marcy, A; Drake, Pamela L

    2007-11-01

    Workers who perform routine welding tasks are potentially exposed to fume that may contain manganese. Manganese may cause respiratory problems and is implicated in causing the occurrence of Parkinson-like symptoms. In this study, a field colorimetric method for extracting and measuring manganese in welding fume was developed. The method uses ultrasonic extraction with an acidic hydrogen peroxide solution to extract welding fume collected on polyvinyl chloride filters. Commercially available pre-packaged reagents are used to produce a colored solution, created by a reaction of manganese(ii) with 1-(2-pyridylazo)-2-naphthol. Absorbance measurements are then made using a portable spectrophotometer. The method detection limit and limit of quantification (LOQ) were 5.2 microg filter(-1) and 17 microg filter(-1), respectively, with a dynamic range up to 400 microg filter(-1). When the results are above the LOQ for the colorimetric method, the manganese masses are equivalent to those measured by the International Organization for Standardization Method 15202-2, which employs a strong acid digestion and analysis using inductively coupled plasma-optical emission spectrometry.

  2. Low level exposure to manganese from drinking water and cognition in school-age children.

    PubMed

    Bouchard, Maryse F; Surette, Céline; Cormier, Pierre; Foucher, Delphine

    2018-01-01

    Manganese (Mn) is an element found in the environment and certain geographic areas have elevated concentrations in soil and water du to natural conditions or anthropic activities. A growing body of data suggests that exposure to manganese in drinking water could be neurotoxic. Firstly, we aimed to examine the association between exposure to manganese from drinking water and cognition in children consuming well water. Secondly, we also aimed to examine the relation between cognition and manganese concentrations in children's hair, nail, and saliva. A total 259 children from 189 households consuming well water were included in the present study (ages 5.9 to 13.7 years). We assessed children's cognition with the WISC-IV, and we used five indicators of manganese exposure: concentration in tap water, intake from the consumption of water divided by child's weight, manganese concentration in children's hair, toe nail, and saliva. We used General Estimating Equation analysis to assess the relation between manganese exposure indicators and IQ scores, adjusting for potential confounders, and taking into account family clusters. Drinking water manganese concentrations were generally low, with 48% of children consuming water <5μg/L, 25% >50μg/L, and 4% >400μg/L. Results differed by sex. In girls, higher manganese concentration in water, hair, and toe nail were associated with poorer Performance IQ scores but this was significant only for toe nail (for a 10-fold increase in manganese, β: -5.65, 95% CIs: -10.97, -0.32). Opposite associations were observed in boys, i.e., better Performance IQ scores with higher manganese concentration hair, toe nail, and water, the latter being significant (β: 2.66, 95% CIs: 0.44, 4.89). Verbal IQ scores did not seem to be associated with manganese exposure indicators. Drinking water manganese levels were considerably lower than in previous studies reporting neurotoxic effects. There was no clear indication of an association between exposure

  3. Ocean manganese nodules as stromatolite with a fractal like-signature

    NASA Astrophysics Data System (ADS)

    Akai, Junji; Akiyama, Shigeki; Tsuchiyama, Akira; Akai, Kurumi

    Deep-sea manganese (Mn) nodules are problematic in terms of factors such as their characteristic form and genesis. There are many reports of bacterial species from manganese nodules. However, the genesis of these nodules has not been fully confirmed. Samples, mainly from the Clarion Clipperton Fracture zone in the Pacific Ocean, were examined by mineralogical methods and X-ray CT. Thin sections of these samples showed columnar stromatolite structures with rhythmic bands. Mineralized bacteria were observed by SEM and TEM. Surface morphology could be described as having a fractal-like nature. The fractal characteristics of spherical to dome-like forms were fundamentally composed of at least four ranks. The 4th order form corresponds to the stromatolite dome top shapes. Similar granular domain units and porous characteristics in manganese nodules were clearly observed by X-ray CT sections. Mathematical simulation based on fractal models reproduced similar morphological characteristics to the natural samples. So, we arrived at the concluding hypothesis that manganese nodules are aggregated stromatolite with fractal-like characteristics. Furthermore, we discussed the possibility that the nature of the layer manganese oxide minerals as the major component of the nodule and associated Fe-oxyhydroxide minerals may become an absorber/scavenger of strategic heavy metals and also toxic metals in the environments.

  4. Geological reconnaissance of some Uruguayan iron and manganese deposits in 1962

    USGS Publications Warehouse

    Wallace, Roberts Manning

    1976-01-01

    Three mineralized areas lie in an area near the town of Minas de Corrales in the Departamento de Rivera; they are the Cerro Amelia, the Cerro de Papagayo, and the Cerro Iman. The Cerro Amelia is composed of small bands of iron-rich rock separated by an amphibolitic or mafic rock. Selective mining would be necessary to extract the 31,000 tons per meter of depth of iron-rich rock that ranges from 15 to 40 percent metallic iron. The Cerro de Papagayo district contains many small, rich deposits of ferruginous manganese ore. The ratio of Mn to Fe varies widely within each small deposit as well as from deposit to deposit. Some ferruginous manganese ore contains 50-55 percent manganese dioxide. Although there are many thousands of tons of ore in the district, small-scale mining operations are imperative. One deposit, the Cerro Avestuz manganese mine, was visited. The manganese ore body lies within contorted highly metamorphosed itabirite that contains both hard low grade and soft high grade ferruginous manganese ores estimated to average 40 percent Mn. About 38,000 tons of manganese ore is present in this deposit. The Cerro Iman is a large block of itabirite that contains about 40 percent Fe. The grade is variable and probably runs from less than 35 percent Fe to more than 50 percent Fe. No exploration has been done on this deposit. It is recommended that the Cerro de Iman area be geologically mapped in detail, and that a geological reconnaissance be made of the area that is between the Cuchilla de Corrales and the Cuchilla de Areycua/Cuchilla del Cerro Pelado area.

  5. A hydrous Ca-bearing magnesium carbonate from playa lake sediments, Salines Lake, Spain

    USGS Publications Warehouse

    Queralt, I.; Julia, R.; Plana, F.; Bischoff, J.L.

    1997-01-01

    Sediments of playa Lake Salines, SE, Spain, contain a carbonate mineral characterized by X-ray diffraction peaks very similar to, but systematically shifted from those of pure magnesite. Analyses (SEM, IR and Raman spectroscopy, DTA, TGA, and ICP) indicate the mineral is a hydrous Ca-bearing magnesium carbonate with the chemical formula (Mg0.92,Ca0.08)CO3??3H2O. Thermal characteristics of the mineral are similar to those of other known hydrated magnesium carbonates. X-ray and electron diffraction data suggests a monoclinic system (P21/n space group) with unit-cell parameters of a = 6.063(6), b = 10.668(5), and c = 6.014(4) A?? and ?? = 107.28??.

  6. Mutations in SLC39A14 disrupt manganese homeostasis and cause childhood-onset parkinsonism-dystonia.

    PubMed

    Tuschl, Karin; Meyer, Esther; Valdivia, Leonardo E; Zhao, Ningning; Dadswell, Chris; Abdul-Sada, Alaa; Hung, Christina Y; Simpson, Michael A; Chong, W K; Jacques, Thomas S; Woltjer, Randy L; Eaton, Simon; Gregory, Allison; Sanford, Lynn; Kara, Eleanna; Houlden, Henry; Cuno, Stephan M; Prokisch, Holger; Valletta, Lorella; Tiranti, Valeria; Younis, Rasha; Maher, Eamonn R; Spencer, John; Straatman-Iwanowska, Ania; Gissen, Paul; Selim, Laila A M; Pintos-Morell, Guillem; Coroleu-Lletget, Wifredo; Mohammad, Shekeeb S; Yoganathan, Sangeetha; Dale, Russell C; Thomas, Maya; Rihel, Jason; Bodamer, Olaf A; Enns, Caroline A; Hayflick, Susan J; Clayton, Peter T; Mills, Philippa B; Kurian, Manju A; Wilson, Stephen W

    2016-05-27

    Although manganese is an essential trace metal, little is known about its transport and homeostatic regulation. Here we have identified a cohort of patients with a novel autosomal recessive manganese transporter defect caused by mutations in SLC39A14. Excessive accumulation of manganese in these patients results in rapidly progressive childhood-onset parkinsonism-dystonia with distinctive brain magnetic resonance imaging appearances and neurodegenerative features on post-mortem examination. We show that mutations in SLC39A14 impair manganese transport in vitro and lead to manganese dyshomeostasis and altered locomotor activity in zebrafish with CRISPR-induced slc39a14 null mutations. Chelation with disodium calcium edetate lowers blood manganese levels in patients and can lead to striking clinical improvement. Our results demonstrate that SLC39A14 functions as a pivotal manganese transporter in vertebrates.

  7. Mutations in SLC39A14 disrupt manganese homeostasis and cause childhood-onset parkinsonism–dystonia

    PubMed Central

    Tuschl, Karin; Meyer, Esther; Valdivia, Leonardo E.; Zhao, Ningning; Dadswell, Chris; Abdul-Sada, Alaa; Hung, Christina Y.; Simpson, Michael A.; Chong, W. K.; Jacques, Thomas S.; Woltjer, Randy L.; Eaton, Simon; Gregory, Allison; Sanford, Lynn; Kara, Eleanna; Houlden, Henry; Cuno, Stephan M.; Prokisch, Holger; Valletta, Lorella; Tiranti, Valeria; Younis, Rasha; Maher, Eamonn R.; Spencer, John; Straatman-Iwanowska, Ania; Gissen, Paul; Selim, Laila A. M.; Pintos-Morell, Guillem; Coroleu-Lletget, Wifredo; Mohammad, Shekeeb S.; Yoganathan, Sangeetha; Dale, Russell C.; Thomas, Maya; Rihel, Jason; Bodamer, Olaf A.; Enns, Caroline A.; Hayflick, Susan J.; Clayton, Peter T.; Mills, Philippa B.; Kurian, Manju A.; Wilson, Stephen W.

    2016-01-01

    Although manganese is an essential trace metal, little is known about its transport and homeostatic regulation. Here we have identified a cohort of patients with a novel autosomal recessive manganese transporter defect caused by mutations in SLC39A14. Excessive accumulation of manganese in these patients results in rapidly progressive childhood-onset parkinsonism–dystonia with distinctive brain magnetic resonance imaging appearances and neurodegenerative features on post-mortem examination. We show that mutations in SLC39A14 impair manganese transport in vitro and lead to manganese dyshomeostasis and altered locomotor activity in zebrafish with CRISPR-induced slc39a14 null mutations. Chelation with disodium calcium edetate lowers blood manganese levels in patients and can lead to striking clinical improvement. Our results demonstrate that SLC39A14 functions as a pivotal manganese transporter in vertebrates. PMID:27231142

  8. Modeling U-shaped dose-response curves for manganese using categorical regression.

    PubMed

    Milton, Brittany; Krewski, Daniel; Mattison, Donald R; Karyakina, Nataliya A; Ramoju, Siva; Shilnikova, Natalia; Birkett, Nicholas; Farrell, Patrick J; McGough, Doreen

    2017-01-01

    Manganese is an essential nutrient which can cause adverse effects if ingested to excess or in insufficient amounts, leading to a U-shaped exposure-response relationship. Methods have recently been developed to describe such relationships by simultaneously modeling the exposure-response curves for excess and deficiency. These methods incorporate information from studies with diverse adverse health outcomes within the same analysis by assigning severity scores to achieve a common response metric for exposure-response modeling. We aimed to provide an estimate of the optimal dietary intake of manganese to balance adverse effects from deficient or excess intake. We undertook a systematic review of the literature from 1930 to 2013 and extracted information on adverse effects from manganese deficiency and excess to create a database on manganese toxicity following oral exposure. Although data were available for seven different species, only the data from rats was sufficiently comprehensive to support analytical modelling. The toxicological outcomes were standardized on an 18-point severity scale, allowing for a common analysis of all available toxicological data. Logistic regression modelling was used to simultaneously estimate the exposure-response profile for dietary deficiency and excess for manganese and generate a U-shaped exposure-response curve for all outcomes. Data were available on the adverse effects of 6113 rats. The nadir of the U-shaped joint response curve occurred at a manganese intake of 2.70mg/kgbw/day with a 95% confidence interval of 2.51-3.02. The extremes of both deficient and excess intake were associated with a 90% probability of some measurable adverse event. The manganese database supports estimation of optimal intake based on combining information on adverse effects from systematic review of published experiments. There is a need for more studies on humans. Translation of our results from rats to humans will require adjustment for interspecies

  9. Manganese and selenium concentrations in cerebrospinal fluid of seriously ill children.

    PubMed

    Franěk, Tomáš; Kotaška, Karel; Průša, Richard

    2017-11-01

    The homeostasis of essential trace elements such as selenium and manganese may be altered in patients with severe diseases of various etiologies (trauma brain injuries, tumors, leukemias, lymphomas, neurological diseases). Concentration of manganese and selenium were determined in cerebrospinal fluid by electrothermal atomic absorption spectrometry in 50 hospitalized children with various clinical ethiologies including oncological, neurological, and brain related diseases. The concentrations of manganese in cerebrospinal fluid of children were 0.97±0.67 μg/L. The concentrations of selenium were 13.3±3.5 μg/L. The concentrations were similar as published in adults. The values did not correlated with the age, gender and severity of the disease. We evaluated values of selenium and manganese in cerebrospinal fluid of seriously diseased children. © 2017 Wiley Periodicals, Inc.

  10. Stimulatory effect of boron and manganese salts on keratinocyte migration.

    PubMed

    Chebassier, Nathalie; Ouijja, El Houssein; Viegas, Isabelle; Dreno, Brigitte

    2004-01-01

    Keratinocyte proliferation and migration are essential for the reconstruction of the cutaneous barrier after skin injury. Interestingly, thermal waters which are rich in trace elements (e.g. boron and manganese), are known to be able to improve wound healing. In order to understand the mechanism of action of this effect, our study investigated the in vitro modulation of keratinocyte migration and proliferation by boron and manganese salts, which are present in high concentrations in a thermal water (Saint Gervais). Our in vitro study demonstrated that incubating keratinocytes for 24 h with boron salts at concentrations between 0.5 and 10 microg/ml or manganese salts at concentrations between 0.1 and 1.5 microg/ml accelerated wound closure compared with control medium (+20%). As this acceleration was not related to an increase in keratinocyte proliferation we suggest that boron and manganese act on wound healing mainly by increasing the migration of keratinocytes.

  11. High-density amorphous ice: nucleation of nanosized low-density amorphous ice

    NASA Astrophysics Data System (ADS)

    Tonauer, Christina M.; Seidl-Nigsch, Markus; Loerting, Thomas

    2018-01-01

    The pressure dependence of the crystallization temperature of different forms of expanded high-density amorphous ice (eHDA) was scrutinized. Crystallization at pressures 0.05-0.30 GPa was followed using volumetry and powder x-ray diffraction. eHDA samples were prepared via isothermal decompression of very high-density amorphous ice at 140 K to different end pressures between 0.07-0.30 GPa (eHDA0.07-0.3). At 0.05-0.17 GPa the crystallization line T x (p) of all eHDA variants is the same. At pressures  >0.17 GPa, all eHDA samples decompressed to pressures  <0.20 GPa exhibit significantly lower T x values than eHDA0.2 and eHDA0.3. We rationalize our findings with the presence of nanoscaled low-density amorphous ice (LDA) seeds that nucleate in eHDA when it is decompressed to pressures  <0.20 GPa at 140 K. Below ~0.17 GPa, these nanosized LDA domains are latent within the HDA matrix, exhibiting no effect on T x of eHDA<0.2. Upon heating at pressures  ⩾0.17 GPa, these nanosized LDA nuclei transform to ice IX nuclei. They are favored sites for crystallization and, hence, lower T x . By comparing crystallization experiments of bulk LDA with the ones involving nanosized LDA we are able to estimate the Laplace pressure and radius of ~0.3-0.8 nm for the nanodomains of LDA. The nucleation of LDA in eHDA revealed here is evidence for the first-order-like nature of the HDA  →  LDA transition, supporting water’s liquid-liquid transition scenarios.

  12. High manganese concentrations in rocks at Gale crater, Mars

    USGS Publications Warehouse

    Lanza, Nina L.; Fischer, Woodward W.; Wiens, Roger C.; Grotzinger, John P.; Ollila, Ann M.; Anderson, Ryan B.; Clark, Benton C.; Gellert, Ralf; Mangold, Nicolas; Maurice, Sylvestre; Le Mouélic, Stéphane; Nachon, Marion; Schmidt, Mariek E.; Berger, Jeffrey; Clegg, Samuel M.; Forni, Olivier; Hardgrove, Craig; Melikechi, Noureddine; Newsom, Horton E.; Sautter, Violaine

    2014-01-01

    The surface of Mars has long been considered a relatively oxidizing environment, an idea supported by the abundance of ferric iron phases observed there. However, compared to iron, manganese is sensitive only to high redox potential oxidants, and when concentrated in rocks, it provides a more specific redox indicator of aqueous environments. Observations from the ChemCam instrument on the Curiosity rover indicate abundances of manganese in and on some rock targets that are 1–2 orders of magnitude higher than previously observed on Mars, suggesting the presence of an as-yet unidentified manganese-rich phase. These results show that the Martian surface has at some point in time hosted much more highly oxidizing conditions than has previously been recognized.

  13. Spectroscopic characterization of manganese minerals.

    PubMed

    Lakshmi Reddy, S; Padma Suvarna, K; Udayabhaska Reddy, G; Endo, Tamio; Frost, R L

    2014-01-03

    Manganese minerals ardenite, alleghanyite and leucopoenicite originated from Madhya Pradesh, India, Nagano prefecture Japan, Sussex Country and Parker Shaft Franklin, Sussex Country, New Jersey respectively are used in the present work. In these minerals manganese is the major constituent and iron if present is in traces only. An EPR study of on all of the above samples confirms the presence of Mn(II) with g around 2.0. Optical absorption spectrum of the mineral alleghanyite indicates that Mn(II) is present in two different octahedral sites and in leucophoenicite Mn(II) is also in octahedral geometry. Ardenite mineral gives only a few Mn(II) bands. NIR results of the minerals ardenite, leucophoenicite and alleghanyite are due to hydroxyl and silicate anions which confirming the formulae of the minerals. Copyright © 2013 Elsevier B.V. All rights reserved.

  14. Medium-Alloy Manganese-Rich Transformation-Induced Plasticity Steels

    NASA Astrophysics Data System (ADS)

    Suh, Dong Woo; Ryu, Joo Hyun; Joo, Min Sung; Yang, Hong Seok; Lee, Kyooyoung; Bhadeshia, H. K. D. H.

    2013-01-01

    The manganese concentration of steels which rely on transformation-induced plasticity is generally less than 2 wt pct. Recent work has highlighted the potential for strong and ductile alloys containing some 6 wt pct of manganese, but with aluminum additions in order to permit heat treatments which are amenable to rapid production. However, large concentrations of aluminum also cause difficulties during continuous casting. Alloy design calculations have been carried out in an effort to balance these conflicting requirements, while maintaining the amount of retained austenite and transformation kinetics. The results indicate that it is possible by adjusting the carbon and manganese concentrations to reduce the aluminum concentration, without compromising the mechanical properties or transformation kinetics. The deformation-induced transformation of retained austenite is explained quantitatively, for a range of alloys, in terms of a driving force which takes into account the very fine state of the retained austenite.

  15. Manganese pollution in the city environment and its relationship to traffic density.

    PubMed Central

    Joselow, M M; Tobias, E; Koehler, R; Coleman, S; Bogden, J; Gause, D

    1978-01-01

    As lead is phased out of gasoline, other additives with anti-knock properties, particularly organic manganese compounds, are being substituted. Unavoidably, such compounds go through the combustion process, are eliminated in exhaust gases, and become part of the city environment. To obtain some indication of the extent of this new pollution street soils from various locations in a heavily trafficked city (Newark, NJ) were analyzed for manganese and lead by atomic absorption. Highly signigicant inverse relationships were found between the concentrations of both contaminants and distances from major traffic arteries. Strong circumstantial evidence is thus provided that: 1) manganese pollution is occurring, along with lead, in the city environment; 2) this new pollution is related to traffic density; and 3) the most likely sources are automobile exhausts. This suspicion is further strengthened by the significant correlations observed between manganese and lead contents in children's blood, suggesting a common source for both. Substantiation of the safety of this practice of adding manganese to gasoline is needed. PMID:655314

  16. Dynamic observation on the growth behaviors in manganese silicide/silicon nanowire heterostructures.

    PubMed

    Hsieh, Yu-Hsun; Chiu, Chung-Hua; Huang, Chun-Wei; Chen, Jui-Yuan; Lin, Wan-Jhen; Wu, Wen-Wei

    2015-02-07

    Metal silicide nanowires (NWs) are very interesting materials with diverse physical properties. Among the silicides, manganese silicide nanostructures have attracted wide attention due to their several potential applications, including in microelectronics, optoelectronics, spintronics and thermoelectric devices. In this work, we exhibited the formation of pure manganese silicide and manganese silicide/silicon nanowire heterostructures through solid state reaction with line contacts between manganese pads and silicon NWs. Dynamical process and phase characterization were investigated by in situ transmission electron microscopy (in situ TEM) and spherical aberration corrected scanning transmission electron microscopy (Cs-corrected STEM), respectively. The growth dynamics of the manganese silicide phase under thermal effects were systematically studied. Additionally, Al2O3, serving as the surface oxide, altered the growth behavior of the MnSi nanowire, enhancing the silicide/Si epitaxial growth and effecting the diffusion process in the silicon nanowire as well. In addition to fundamental science, this significant study has great potential in advancing future processing techniques in nanotechnology and related applications.

  17. Polydisulfide Manganese(II) Complexes as Non-Gadolinium Biodegradable Macromolecular MRI Contrast Agents

    PubMed Central

    Ye, Zhen; Jeong, Eun-Kee; Wu, Xueming; Tan, Mingqian; Yin, Shouyu; Lu, Zheng-Rong

    2011-01-01

    Purpose To develop safe and effective manganese(II) based biodegradable macromolecular MRI contrast agents. Materials and Methods In this study, we synthesized and characterized two polydisulfide manganese(II) complexes, Mn-DTPA cystamine copolymers and Mn-EDTA cystamine copolymers, as new biodegradable macromolecular MRI contrast agents. The contrast enhancement of the two manganese based contrast agents were evaluated in mice bearing MDA-MB-231 human breast carcinoma xenografts, in comparison with MnCl2. Results The T1 and T2 relaxivities were 4.74 and 10.38 mM−1s−1 per manganese at 3T for Mn-DTPA cystamine copolymers (Mn=30.50 kDa) and 6.41 and 9.72 mM−1s−1 for Mn-EDTA cystamine copolymers (Mn= 61.80 kDa). Both polydisulfide Mn(II) complexes showed significant liver, myocardium and tumor enhancement. Conclusion The manganese based polydisulfide contrast agents have a potential to be developed as alternative non-gadolinium contrast agents for MR cancer and myocardium imaging. PMID:22031457

  18. Hepatoprotective effect of manganese chloride against CCl4-induced liver injury in rats.

    PubMed

    Eidi, Akram; Mortazavi, Pejman; Behzadi, Khodabakhsh; Rohani, Ali Haeri; Safi, Shahabeddin

    2013-11-01

    The aim of the present study is to evaluate the protective effect of manganese chloride against carbon tetrachloride (CCl4)-induced liver injury in rats. Manganese chloride (0.001, 0.01, 0.05 and 0.1 g/kg bw) was administered intragastrically for 28 consecutive days to male CCl4-treated rats. The hepatoprotective activity was assessed using various biochemical parameters such as alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), γ-glutamyltransferase (GGT) and superoxide dismutase (SOD). Histopathological changes in the liver of different groups were also studied. Administration of CCl4 increased the serum ALT, AST, ALP and GGT but decreased SOD levels in rats. Treatment with manganese chloride significantly attenuated these changes to nearly normal levels. The animals treated with manganese chloride have shown decreased necrotic zones and hepatocellular degeneration when compared to the liver exposed to CCl4 intoxication alone. Thus, the histopathological studies also supported the protective effect of manganese chloride. Therefore, the results of this study suggest that manganese chloride exerts hepatoprotection via promoting antioxidative properties against CCl4-induced oxidative liver damage.

  19. Improvement of the tool life of a micro-end mill using nano-sized SiC/Ni electroplating method.

    PubMed

    Park, Shinyoung; Kim, Kwang-Su; Roh, Ji Young; Jang, Gyu-Beom; Ahn, Sung-Hoon; Lee, Caroline Sunyong

    2012-04-01

    High mechanical properties of a tungsten carbide micro-end-mill tool was achieved by extending its tool life by electroplating nano-sized SiC particles (< 100 nm) that had a hardness similar to diamond in a nickel-based material. The co-electroplating method on the surface of the micro-end-mill tool was applied using SiC particles and Ni particles. Organic additives (saccharin and ammonium chloride) were added in a Watts bath to improve the nickel matrix density in the electroplating bath and to smooth the surface of the co-electroplating. The morphology of the coated nano-sized SiC particles and the composition were measured using Scanning Electron Microscope and Energy Dispersive Spectrometer. As the Ni/SiC co-electroplating layer was applied, the hardness and friction coefficient improved by 50%. Nano-sized SiC particles with 7 wt% were deposited on the surface of the micro-end mill while the Ni matrix was smoothed by adding organic additives. The tool life of the Ni/SiC co-electroplating coating on the micro-end mill was at least 25% longer than that of the existing micro-end mills without Ni/SiC co-electroplating. Thus, nano-sized SiC/Ni coating by electroplating significantly improves the mechanical properties of tungsten carbide micro-end mills.

  20. Comparative compressibility of hydrous wadsleyite and ringwoodite: Effect of H 2 O and implications for detecting water in the transition zone: EFFECT OF WATER ON D K /D P OF WADSLEYITE

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Chang, Yun-Yuan; Jacobsen, Steven D.; Bina, Craig R.

    Review of recent mineral physics literature shows consistent trends for the influence of Fe and H 2O on the bulk modulus (K0) of wadsleyite and ringwoodite, the major phases of Earth's mantle transition zone (410–660 km). However, there is little consensus on the first pressure derivative, K0' = (dK/dP)P=0, which ranges from about 4 to >5 across experimental studies and compositions. Here we demonstrate the importance of K0' in evaluating the bulk sound velocity of the transition zone in terms of water content and provide new constraints on the effect of H 2O on K0' for wadsleyite and ringwoodite bymore » conducting a comparative compressibility study. In the experiment, multiple crystals of hydrous Fo90 wadsleyite containing 2.0 and 0.25 wt % H 2O were loaded into the same diamond anvil cell, along with hydrous ringwoodite containing 1.4 wt % H 2O. By measuring their pressure-volume evolution simultaneously up to 32 GPa, we constrain the difference in K0' independent of the pressure scale, finding that H 2O has no effect on K0', whereas the effect of H 2O on K0 is significant. The fitted K0' values of hydrous wadsleyite (0.25 and 2.0 wt % H 2O) and hydrous ringwoodite (1.4 wt % H 2O) examined in this study were found to be identical within uncertainty, with K0' ~3.7(2). New secondary-ion mass spectrometry measurements of the H 2O content of these and previously investigated wadsleyite samples shows the bulk modulus of wadsleyite is reduced by 7.0(5) GPa/wt % H 2O, independent of Fe content for upper mantle compositions. Because K0' is unaffected by H 2O, the reduction of bulk sound velocity in very hydrous regions of transition zone is expected to be on the order of 1.6%, which is potentially detectible in high-resolution, regional seismology studies.« less

  1. Comparative compressibility of hydrous wadsleyite and ringwoodite: Effect of H 2 O and implications for detecting water in the transition zone: EFFECT OF WATER ON D K /D P OF WADSLEYITE

    DOE PAGES

    Chang, Yun-Yuan; Jacobsen, Steven D.; Bina, Craig R.; ...

    2015-12-01

    Review of recent mineral physics literature shows consistent trends for the influence of Fe and H 2O on the bulk modulus (K0) of wadsleyite and ringwoodite, the major phases of Earth's mantle transition zone (410–660 km). However, there is little consensus on the first pressure derivative, K0' = (dK/dP)P=0, which ranges from about 4 to >5 across experimental studies and compositions. Here we demonstrate the importance of K0' in evaluating the bulk sound velocity of the transition zone in terms of water content and provide new constraints on the effect of H 2O on K0' for wadsleyite and ringwoodite bymore » conducting a comparative compressibility study. In the experiment, multiple crystals of hydrous Fo90 wadsleyite containing 2.0 and 0.25 wt % H 2O were loaded into the same diamond anvil cell, along with hydrous ringwoodite containing 1.4 wt % H 2O. By measuring their pressure-volume evolution simultaneously up to 32 GPa, we constrain the difference in K0' independent of the pressure scale, finding that H 2O has no effect on K0', whereas the effect of H 2O on K0 is significant. The fitted K0' values of hydrous wadsleyite (0.25 and 2.0 wt % H 2O) and hydrous ringwoodite (1.4 wt % H 2O) examined in this study were found to be identical within uncertainty, with K0' ~3.7(2). New secondary-ion mass spectrometry measurements of the H 2O content of these and previously investigated wadsleyite samples shows the bulk modulus of wadsleyite is reduced by 7.0(5) GPa/wt % H 2O, independent of Fe content for upper mantle compositions. Because K0' is unaffected by H 2O, the reduction of bulk sound velocity in very hydrous regions of transition zone is expected to be on the order of 1.6%, which is potentially detectible in high-resolution, regional seismology studies.« less

  2. Spatial mapping of mineralization with manganese-enhanced magnetic resonance imaging☆☆☆

    PubMed Central

    Chesnick, Ingrid E.; Centeno, Jose A.; Todorov, Todor I.; Koenig, Alan E.; Potter, Kimberlee

    2011-01-01

    Paramagnetic manganese can be employed as a calcium surrogate to sensitize the magnetic resonance imaging (MRI) technique to the processing of calcium during the bone formation process. At low doses, after just 48 h of exposure, osteoblasts take up sufficient quantities of manganese to cause marked reductions in the water proton T1 values compared with untreated cells. After just 24 h of exposure, 25 μM MnCl2 had no significant effect on cell viability. However, for mineralization studies 100 μM MnCl2 was used to avoid issues of manganese depletion in calvarial organ cultures and a post-treatment delay of 48 h was implemented to ensure that manganese ions taken up by osteoblasts is deposited as mineral. All specimens were identified by their days in vitro (DIV). Using inductively coupled plasma optical emission spectroscopy (ICP-OES), we confirmed that Mn-treated calvariae continued to deposit mineral in culture and that the mineral composition was similar to that of age-matched controls. Notably there was a significant decrease in the manganese content of DIV18 compared with DIV11 specimens, possibly relating to less manganese sequestration as a result of mineral maturation. More importantly, quantitative T1 maps of Mn-treated calvariae showed localized reductions in T1 values over the calvarial surface, indicative of local variations in the surface manganese content. This result was verified with laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). We also found that ΔR1 values, calculated by subtracting the relaxation rate of Mn-treated specimens from the relaxation rate of age-matched controls, were proportional to the surface manganese content and thus mineralizing activity. From this analysis, we established that mineralization of DIV4 and DIV11 specimens occurred in all tissue zones, but was reduced for DIV18 specimens because of mineral maturation with less manganese sequestration. In DIV25 specimens, active mineralization was

  3. [Factors affecting biological removal of iron and manganese in groundwater].

    PubMed

    Xue, Gang; He, Sheng-Bing; Wang, Xin-Ze

    2006-01-01

    Factors affecting biological process for removing iron and manganese in groundwater were analyzed. When DO and pH in groundwater after aeration were 7.0 - 7.5 mg/L and 6.8 - 7.0 respectively, not only can the activation of Mn2+ oxidizing bacteria be maintained, but also the demand of iron and manganese removal can be satisfied. A novel inoculating approach of grafting mature filter material into filter bed, which is easier to handle than selective culture media, was employed in this research. However, this approach was only suitable to the filter material of high-quality manganese sand with strong Mn2+ adsorption capacity. For the filter material of quartz sand with weak adsorption capacity, only culturing and domesticating Mn2+ oxidizing bacteria by selective culture media can be adopted as inoculation in filter bed. The optimal backwashing rate of biological filter bed filled with manganese sand and quartz sand should be kept at a relatively low level of 6 - 9 L/(m2 x s) and 7 -11 L/( m2 x s), respectively. Then the stability of microbial phase in filter bed was not disturbed, and iron and manganese removal efficiency recovered in less than 5h. Moreover, by using filter material with uniform particle size of 1.0 - 1.2 mm in filter bed, the filtration cycle reached as long as 35 - 38h.

  4. TRANSPORT AND DEPOSITION OF NANO-SIZE PARTICLES IN THE UPPER HUMAN RESPIRATORY AIRWAYS

    EPA Science Inventory

    TRANSPORT AND DEPOSITION OF NANO-SIZE PARTICLES IN THE UPPER HUMAN RESPIRATORY AIRWAYS. Zhe Zhang*, Huawei Shi, Clement Kleinstreuer, Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, NC 27695-7910; Chong S. Kim, National Health and En...

  5. Geochemical changes and fracture development in Woodford Shale cores following hydrous pyrolysis under uniaxial confinement

    USGS Publications Warehouse

    Birdwell, Justin E.; Lewan, Michael D.; Miller, Michael; Baez, Luis; Beeney, Ken; Sonnenberg, Steve

    2013-01-01

    A uniaxial confinement clamp was used on Woodford Shale cores in hydrous pyrolysis experiments to study fracture development during thermal maturation. The clamp simulates overburden in that it prevents cores from expanding perpendicular to bedding fabric during the volume-increasing reactions associated with petroleum generation. Cores were cut from a slab of immature Woodford Shale and subjected to hydrous pyrolysis under confinement at 300, 330, and 365 °C for 72 hours to induce thermal maturities ranging from early bitumen to maximum expelled-oil generation. Two additional cores were used as experimental controls: (1) a confined core was saturated with water by heating it to 100 °C under hydrous pyrolysis conditions for 72 hours to use for characterization of the original rock, and (2) an unconfined core was heated at 365 °C for 72 hours to evaluate the effects of confinement on petroleum generation and expulsion. X-ray computed tomography (X-CT) imaging and other analyses identified five distinct beds within the cored interval. Using a tentative classification system, beds 1, 2, and 3 are described as dolomitic marlstone (DM) with total organic carbon (TOC) contents of 7.7, 5.8, and 7.7 wt. %, respectively; bed 4 is a cherty quartzose claystone (CQC) with TOC content of 5.5 wt. %; and bed 5 is a quartzose claystone with TOC content of 10.9 wt. %. Bed samples all had similar Rock-Eval hydrogen indices (600 ± 46 mg S2/g-TOC) and Tmax values (433 ± 2 °C), demonstrating organic matter uniformity and low thermal maturity. The X-CT scan of the core heated to 100 °C showed preexisting fractures that were nearly perpendicular to the bedding fabric primarily in the low-TOC DM bed 2 and CQC bed 4. Heating led to enhancement of preexisting fractures in the confined cores with the greatest enhancement occurring in CQC bed 4. The fractures increased in size and intensity with temperature. This is attributed to the internal pressure generated by volume

  6. 21 CFR 184.1461 - Manganese sulfate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... hydroquinone. Other manufacturing processes include the action of sulfur dioxide on a slurry of manganese..., followed by leaching and crystallization. (b) The ingredient meets the specifications of the Food Chemicals...

  7. 21 CFR 184.1461 - Manganese sulfate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... hydroquinone. Other manufacturing processes include the action of sulfur dioxide on a slurry of manganese..., followed by leaching and crystallization. (b) The ingredient meets the specifications of the Food Chemicals...

  8. Effect of olfactory manganese exposure on anxiety-related behavior in a mouse model of iron overload hemochromatosis

    PubMed Central

    Ye, Qi; Kim, Jonghan

    2015-01-01

    Manganese in excess promotes unstable emotional behavior. Our previous study showed that olfactory manganese uptake into the brain is altered in Hfe−/− mice, a model of iron overload hemochromatosis, suggesting that Hfe deficiency could modify the neurotoxicity of airborne manganese. We determined anxiety-related behavior and monoaminergic protein expression after repeated intranasal instillation of MnCl2 to Hfe−/− mice. Compared with manganese-instilled wild-type mice, Hfe−/− mice showed decreased manganese accumulation in the cerebellum. Hfe−/− mice also exhibited increased anxiety with decreased exploratory activity and elevated dopamine D1 receptor and norepinephrine transporter in the striatum. Moreover, Hfe deficiency attenuated manganese-associated impulsivity and modified the effect of manganese on the expression of tyrosine hydroxylase, vesicular monoamine transporter and serotonin transporter. Together, our data indicate that loss of HFE function alters manganese-associated emotional behavior and further suggest that HFE could be a potential molecular target to alleviate affective disorders induced by manganese inhalation. PMID:26189056

  9. Effect of sulfate on the liquidus and sulfur concentration at anhydrite saturation (SCAS) of hydrous basalt at subduction zones

    NASA Astrophysics Data System (ADS)

    Chowdhury, P.; Dasgupta, R.

    2017-12-01

    Sulfur (S) as sulfide minerals, melts, and as S2- species in silicate melts is prevalent in many different tectono-magmatic settings in Earth. Yet, S as anhydrite or as SO42- species in fluids and melts is thought to be relevant for subduction zones, where the presence of sulfate over sulfide is argued to play a key role in processes such as mobility of chalcophile element [e.g., 1], oxidation of mantle and mantle-derived magmas [2], and release of excess S-rich gases [3]. However, it remains unclear what role the slab-released SO42-, dissolved in fluids or melts plays in magma genesis in sub-arc mantle. Furthermore, although oxidized arc magma is thought to transport SO42- from mantle to volcanic arc crust and atmosphere, the SO42- carrying capacity of arc basalts at mantle conditions are unknown as the existing S concentration at anhydrite saturation (SCAS) experiments are restricted to 1 GPa and mostly on felsic compositions [e.g. 4,5]. We performed piston-cylinder experiments in Au-Pd capsules at 1-3 GPa and 1000-1325 °C to investigate (a) the effect of variable dissolved SO42- (0-2 wt.% S) on the liquidus of a primary hydrous arc basalt with 4 wt.% H2O and (b) the SCAS of hydrous mafic magmas. Dissolved SO42- in the silicate melt was confirmed by S Kα X-ray peak position using electron microprobe. S-free hydrous liquidus of cpx at 2 GPa is 25 °C hotter than the liquidus with 0.1 wt.% S as SO42- and the liquidus depression with further S enrichment to anhydrite saturation ( 2 wt.% S) can be fitted by an empirical power function. Experiments on more mafic compositions show that SCAS increases with increasing temperature and CaO and decreases with SiO2. Calculations using a new SCAS model, fitted with our new data and previous experiments, and assuming 150-550 ppm S in the arc mantle [6] show that <10% melting would exhaust anhydrite, if present. The S content as SO42- of hydrous arc basalts produced by 10-20% melting [7] will be 500-4000 ppm, which is

  10. Manganese in Air: Associations in Residents with Tremor and Motor Function

    EPA Science Inventory

    Objective: An environmental study examined air manganese (Mn) exposed residents of two towns in Ohio: Marietta (near a ferro-manganese smelter) and East Liverpool (EL)(adjacent to an open-storage ore packaging facility). Air Mn inhalation is associated with neuropsychological/neu...

  11. Fate of manganese associated with the inhalation of welding fumes: potential neurological effects.

    PubMed

    Antonini, James M; Santamaria, Annette B; Jenkins, Neil T; Albini, Elisa; Lucchini, Roberto

    2006-05-01

    Welding fumes are a complex mixture composed of different metals. Most welding fumes contain a small percentage of manganese. There is an emerging concern among occupational health officials about the potential neurological effects associated with the exposure to manganese in welding fumes. Little is known about the fate of manganese that is complexed with other metals in the welding particles after inhalation. Depending on the welding process and the composition of the welding electrode, manganese may be present in different oxidation states and have different solubility properties. These differences may affect the biological responses to manganese after the inhalation of welding fumes. Manganese intoxication and the associated neurological symptoms have been reported in individual cases of welders who have been exposed to high concentrations of manganese-containing welding fumes due to work in poorly ventilated areas. However, the question remains as to whether welders who are exposed to low levels of welding fumes over long periods of time are at risk for the development of neurological diseases. For the most part, questions remain unanswered. There is still paucity of adequate scientific reports on welders who suffered significant neurotoxicity, hence there is a need for well-designed epidemiology studies that combine complete information on the occupational exposure of welders with both behavioral and biochemical endpoints of neurotoxicity.

  12. Nano-sized polystyrene affects feeding, behavior and physiology of brine shrimp Artemia franciscana larvae.

    PubMed

    Bergami, Elisa; Bocci, Elena; Vannuccini, Maria Luisa; Monopoli, Marco; Salvati, Anna; Dawson, Kenneth A; Corsi, Ilaria

    2016-01-01

    Nano-sized polymers as polystyrene (PS) constitute one of the main challenges for marine ecosystems, since they can distribute along the whole water column affecting planktonic species and consequently disrupting the energy flow of marine ecosystems. Nowadays very little knowledge is available on the impact of nano-sized plastics on marine organisms. Therefore, the present study aims to evaluate the effects of 40nm anionic carboxylated (PS-COOH) and 50nm cationic amino (PS-NH2) polystyrene nanoparticles (PS NPs) on brine shrimp Artemia franciscana larvae. No signs of mortality were observed at 48h of exposure for both PS NPs at naplius stage but several sub-lethal effects were evident. PS-COOH (5-100μg/ml) resulted massively sequestered inside the gut lumen of larvae (48h) probably limiting food intake. Some of them were lately excreted as fecal pellets but not a full release was observed. Likewise, PS-NH2 (5-100µg/ml) accumulated in larvae (48h) but also adsorbed at the surface of sensorial antennules and appendages probably hampering larvae motility. In addition, larvae exposed to PS-NH2 undergo multiple molting events during 48h of exposure compared to controls. The activation of a defense mechanism based on a physiological process able to release toxic cationic NPs (PS-NH2) from the body can be hypothesized. The general observed accumulation of PS NPs within the gut during the 48h of exposure indicates a continuous bioavailability of nano-sized PS for planktonic species as well as a potential transfer along the trophic web. Therefore, nano-sized PS might be able to impair food uptake (feeding), behavior (motility) and physiology (multiple molting) of brine shrimp larvae with consequences not only at organism and population level but on the overall ecosystem based on the key role of zooplankton on marine food webs. Copyright © 2015 Elsevier Inc. All rights reserved.

  13. 75 FR 70665 - Proposed Significant New Use Rule for Cobalt Lithium Manganese Nickel Oxide

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-18

    ... Proposed Significant New Use Rule for Cobalt Lithium Manganese Nickel Oxide AGENCY: Environmental... as cobalt lithium manganese nickel oxide (CAS No. 182442-95-1) which was the subject of... section 5(a)(2) of TSCA for the chemical substance identified as cobalt lithium manganese nickel oxide...

  14. Simultaneous removal of ammonia nitrogen and manganese from wastewater using nitrite by electrochemical method.

    PubMed

    Shu, Jiancheng; Liu, Renlong; Liu, Zuohua; Qiu, Jiang; Chen, Hongliang; Tao, Changyuan

    2017-02-01

    In this work, nitrite was developed to simultaneously remove manganese and ammonia nitrogen from wastewater by the electrochemical method. The characteristics of electrolytic reaction were observed via cyclic voltammograms. Moreover, the mole ratio of nitrite and ammonia nitrogen, voltage, and initial pH value, which affected the removal efficiency of ammonia nitrogen and manganese, were investigated. The results showed that the concentration of ammonia nitrogen in wastewater could be reduced from 120.2 to 6.0 mg L -1 , and manganese could be simultaneously removed from 302.4 to 1.5 mg L -1 at initial pH of 8.0, the mole ratios of nitrite and ammonia nitrogen of 1.5:1, and voltage of 20 V direct current electrolysis for 4.0 h. XRD analysis showed that manganese dioxide was deposited on the anode, and manganese was mainly removed in the form of manganese hydroxide precipitation in the cathode chamber.

  15. Manganese intoxication: the cause of an inexplicable epileptic syndrome in a 3 year old child.

    PubMed

    Herrero Hernandez, Elena; Discalzi, Gianluigi; Dassi, Patrizia; Jarre, Laura; Pira, Enrico

    2003-08-01

    Excess manganese (Mn) can cause several neurotoxic effects, however only a few studies have reported epileptic syndromes related to manganese intoxication. We describe an epileptic syndrome due to manganese intoxication in a 3 year old male child. His blood manganese was elevated, but no other abnormal values or toxic substances were found in blood or urine. The electroencephalogram (EEG) showed a picture of progressive encephalopathy, while brain magnetic resonance was normal. The patient's conditions rapidly worsened to epileptic status despite the use of antiepileptic drugs. Chelating treatment with CaNa(2)EDTA was initiated to remove excess manganese and promptly succeeded in reverting epileptic symptoms. Concurrently, manganese blood levels and electroencephalogram progressively normalized. Thereafter it has been possible to discontinue antiepileptic treatment, and the patient remains in excellent conditions without any treatment.

  16. Evaluation of particulate matter emissions from manganese alloy production using life-cycle assessment.

    PubMed

    Davourie, Julia; Westfall, Luke; Ali, Mohammed; McGough, Doreen

    2017-01-01

    Life-cycle assessments (LCAs) provide a wealth of industry data to assist in evaluating the environmental impacts of industrial processes and product supply chains. In this investigation, data from a recent LCA covering global manganese alloy production was used to evaluate sources of particulate matter (PM) emissions associated with the manganese alloy supply chain. The analysis is aimed at providing an empirical, industry-averaged breakdown of the contribution that processes and emissions controls have on total emissions, manganese releases and occupational exposure. The assessment shows that 66% of PM emissions associated with manganese production occur beyond manganese facilities. Direct or on-site emissions represent 34% of total PM and occur predominantly as disperse sources during mineral extraction and hauling, and as primary furnace emissions. The largest contribution of manganese-bearing PM at ground-level is associated with fugitive emissions from metal and slag tapping, casting, crushing and screening. The evaluation provides a high-level ranking of emissions by process area, to assist in identifying priority areas for industry-wide initiatives to reduce emissions and occupational exposure of manganese. The range of PM emission levels in industry indicate that further enhancements in PM emissions can be achieved by sharing of best practices in emissions controls, limiting furnace conditions which lead to by-passing of emissions controls and application of secondary emission controls to capture fugitive emissions during tapping and casting. The LCA approach to evaluating PM emissions underscores the important role that process optimization and resource efficiency have on reducing PM emissions throughout the manganese supply chain. Copyright © 2016. Published by Elsevier B.V.

  17. Removal of iron and manganese using biological roughing up flow filtration technology.

    PubMed

    Pacini, Virginia Alejandra; María Ingallinella, Ana; Sanguinetti, Graciela

    2005-11-01

    The removal of iron and manganese from groundwater using biological treatment methods is almost unknown in Latin America. Biological systems used in Europe are based on the process of double rapid biofiltration during which dissolved oxygen and pH need to be strictly controlled in order to limit abiotic iron oxidation. The performance of roughing filter technology in a biological treatment process for the removal of iron and manganese, without the use of chemical agents and under natural pH conditions was studied. Two pilot plants, using two different natural groundwaters, were operated with the following treatment line: aeration, up flow roughing filtration and final filtration (either slow or rapid). Iron and manganese removal efficiencies were found to be between 85% and 95%. The high solid retention capability of the roughing filter means that it is possible to remove iron and manganese simultaneously by biotic and abiotic mechanisms. This system combines simple, low-cost operation and maintenance with high iron and manganese removal efficiencies, thus constituting a technology which is particularly suited to small waterworks.

  18. Pharmacokinetic Evaluation of the Equivalency of Gavage, Dietary, and Drinking Water Exposure to Manganese in F344 Rats

    PubMed Central

    Foster, Melanie L.; Bartnikas, Thomas B.; Johnson, Laura C.; Herrera, Carolina; Pettiglio, Michael A.; Keene, Athena M.; Taylor, Michael D.; Dorman, David C.

    2015-01-01

    Concerns exist as to whether individuals may be at greater risk for neurotoxicity following increased manganese (Mn) oral intake. The goals of this study were to determine the equivalence of 3 methods of oral exposure and the rate (mg Mn/kg/day) of exposure. Adult male rats were allocated to control diet (10 ppm), high manganese diet (200 ppm), manganese-supplemented drinking water, and manganese gavage treatment groups. Animals in the drinking water and gavage groups were given the 10 ppm manganese diet and supplemented with manganese chloride (MnCl2) in drinking water or once-daily gavage to provide a daily manganese intake equivalent to that seen in the high-manganese diet group. No statistically significant difference in body weight gain or terminal body weights was seen. Rats were anesthetized following 7 and 61 exposure days, and samples of bile and blood were collected. Rats were then euthanized and striatum, olfactory bulb, frontal cortex, cerebellum, liver, spleen, and femur samples were collected for chemical analysis. Hematocrit was unaffected by manganese exposure. Liver and bile manganese concentrations were elevated in all treatment groups on day 61 (relative to controls). Increased cerebellum manganese concentrations were seen in animals from the high-manganese diet group (day 61, relative to controls). Increased (relative to all treatment groups) femur, striatum, cerebellum, frontal cortex, and olfactory bulb manganese concentrations were also seen following gavage suggesting that dose rate is an important factor in the pharmacokinetics of oral manganese. These data will be used to refine physiologically based pharmacokinetic models, extending their utility for manganese risk assessment by including multiple dietary exposures. PMID:25724921

  19. Nanosizing and nanoconfinement: new strategies towards meeting hydrogen storage goals.

    PubMed

    de Jongh, Petra E; Adelhelm, Philipp

    2010-12-17

    Hydrogen is expected to play an important role as an energy carrier in a future, more sustainable society. However, its compact, efficient, and safe storage is an unresolved issue. One of the main options is solid-state storage in hydrides. Unfortunately, no binary metal hydride satisfies all requirements regarding storage density and hydrogen release and uptake. Increasingly complex hydride systems are investigated, but high thermodynamic stabilities as well as slow kinetics and poor reversibility are important barriers for practical application. Nanostructuring by ball-milling is an established method to reduce crystallite sizes and increase reaction rates. Since five years attention has also turned to alternative preparation techniques that enable particle sizes below 10 nanometers and are often used in conjunction with porous supports or scaffolds. In this Review we discuss the large impact of nanosizing and -confinement on the hydrogen sorption properties of metal hydrides. We illustrate possible preparation strategies, provide insight into the reasons for changes in kinetics, reversibility and thermodynamics, and highlight important progress in this field. All in all we provide the reader with a clear view of how nanosizing and -confinement can beneficially affect the hydrogen sorption properties of the most prominent materials that are currently considered for solid-state hydrogen storage.

  20. Mantle hydrous-fluid interaction with Archaean granite.

    NASA Astrophysics Data System (ADS)

    Słaby, E.; Martin, H.; Hamada, M.; Śmigielski, M.; Domonik, A.; Götze, J.; Hoefs, J.; Hałas, S.; Simon, K.; Devidal, J.-L.; Moyen, J.-F.; Jayananda, M.

    2012-04-01

    Water content/species in alkali feldspars from late Archaean Closepet igneous bodies as well as growth and re-growth textures, trace element and oxygen isotope composition have been studied (Słaby et al., 2011). Both processes growth and re-growth are deterministic, however they differ showing increasing persistency in element behaviour during interaction with fluids. The re-growth process fertilized domains and didn't change their oxygen-isotope signature. Water speciation showed persistent behaviour during heating at least up to 600oC. Carbonate crystals with mantle isotope signature are associated with the recrystallized feldspar domains. Fluid-affected domains in apatite provide evidence of halide exchange. The data testify that the observed recrystallization was a high-temperature reaction with fertilized, halide-rich H2O-CO2 mantle-derived fluids of high water activity. A wet mantle being able to generate hydrous plumes, which appear to be hotter during the Archean in comparison to the present time is supposed by Shimizu et al. (2001). Usually hot fluids, which can be strongly carbonic, precede asthenospheric mantle upwelling. They are supposed to be parental to most recognized compositions, which can be derived by their immiscible separation into saline aqueous-silicic and carbonatitic members (Klein-BenDavid et al., 2007). The aqueous fractions are halogen-rich with a significant proportion of CO2. Both admixed fractions are supposed to be fertile. The Closepet granite emplaced in a major shear zone that delimitates two different terrains. Generally such shear zones, at many places, are supposed to be rooted deep into the mantle. The drain, that favoured and controlled magma ascent and emplacement, seemed to remain efficient after granite crystallization. In the southern part of the Closepet batholiths an evidence of intensive interaction of a lower crust fluid (of high CO2 activity) is provided by the extensive charnockitization of amphibolite facies (St

  1. Associations of welding and manganese exposure with Parkinson disease

    PubMed Central

    Borenstein, Amy R.; Nelson, Lorene M.

    2012-01-01

    Objective: To examine associations of welding and manganese exposure with Parkinson disease (PD) using meta-analyses of data from cohort, case-control, and mortality studies. Methods: Epidemiologic studies related to welding or manganese exposure and PD were identified in a PubMed search, article references, published reviews, and abstracts. Inclusion criteria were 1) cohort, case-control, or mortality study with relative risk (RR), odds ratio (OR), or mortality OR (MOR) and 95 confidence intervals (95% CI); 2) RR, OR, and MOR matched or adjusted for age and sex; 3) valid study design and analysis. When participants of a study were a subgroup of those in a larger study, only results of the larger study were included to assure independence of datasets. Pooled RR/OR estimates and 95% CIs were obtained using random effects models; heterogeneity of study effects were evaluated using the Q statistic and I2 index in fixed effect models. Results: Thirteen studies met inclusion criteria for the welding meta-analysis and 3 studies for the manganese exposure meta-analysis. The pooled RR for the association between welding and PD for all study designs was 0.86 (95% CI 0.80–0.92), with absence of between-study heterogeneity (I2 = 0.0). Effect measures for cohort, case-control, and mortality studies were similar (0.91, 0.82, 0.87). For the association between manganese exposure and PD, the pooled OR was 0.76 (95% CI 0.41–1.42). Conclusions: Welding and manganese exposure are not associated with increased PD risk. Possible explanations for the inverse association between welding and PD include confounding by smoking, healthy worker effect, and hormesis. PMID:22965675

  2. A child with chronic manganese exposure from drinking water.

    PubMed Central

    Woolf, Alan; Wright, Robert; Amarasiriwardena, Chitra; Bellinger, David

    2002-01-01

    The patient's family bought a home in a suburb, but the proximity of the house to wetlands and its distance from the town water main prohibited connecting the house to town water. The family had a well drilled and they drank the well water for 5 years, despite the fact that the water was turbid, had a metallic taste, and left an orange-brown residue on clothes, dishes, and appliances. When the water was tested after 5 years of residential use, the manganese concentration was elevated (1.21 ppm; U.S. Environmental Protection Agency reference, < 0.05 ppm). The family's 10-year-old son had elevated manganese concentrations in whole blood, urine, and hair. The blood manganese level of his brother was normal, but his hair manganese level was elevated. The patient, the 10-year-old, was in the fifth grade and had no history of learning problems; however, teachers had noticed his inattentiveness and lack of focus in the classroom. Our results of cognitive testing were normal, but tests of memory revealed a markedly below-average performance: the patient's general memory index was at the 13th percentile, his verbal memory at the 19th percentile, his visual memory at the 14th percentile, and his learning index at the 19th percentile. The patient's free recall and cued recall tests were all 0.5-1.5 standard deviations (1 SD = 16th percentile) below normal. Psychometric testing scores showed normal IQ but unexpectedly poor verbal and visual memory. These findings are consistent with the known toxic effects of manganese, although a causal relationship cannot necessarily be inferred. PMID:12055054

  3. Manganese-Enhanced MRI: Biological Applications in Neuroscience.

    PubMed

    Malheiros, Jackeline Moraes; Paiva, Fernando Fernandes; Longo, Beatriz Monteiro; Hamani, Clement; Covolan, Luciene

    2015-01-01

    Magnetic resonance imaging (MRI) is an excellent non-invasive tool to investigate biological systems. The administration of the paramagnetic divalent ion manganese (Mn(2+)) enhances MRI contrast in vivo. Due to similarities between Mn(2+) and calcium (Ca(2+)), the premise of manganese-enhanced MRI (MEMRI) is that the former may enter neurons and other excitable cells through voltage-gated Ca(2+) channels. As such, MEMRI has been used to trace neuronal pathways, define morphological boundaries, and study connectivity in morphological and functional imaging studies. In this article, we provide a brief overview of MEMRI and discuss recently published data to illustrate the usefulness of this method, particularly in animal models.

  4. Atomic Force Microscopy Study on the Stiffness of Nanosized Liposomes Containing Charged Lipids.

    PubMed

    Takechi-Haraya, Yuki; Goda, Yukihiro; Sakai-Kato, Kumiko

    2018-06-18

    It has recently been recognized that the mechanical properties of lipid nanoparticles play an important role during in vitro and in vivo behaviors such as cellular uptake, blood circulation, and biodistribution. However, there have been no quantitative investigations of the effect of commonly used charged lipids on the stiffness of nanosized liposomes. In this study, by means of atomic force microscopy (AFM), we quantified the stiffness of nanosized liposomes composed of neutrally charged lipids combined with positively or negatively charged lipids while simultaneously imaging the liposomes in aqueous medium. Our results showed that charged lipids, whether negatively or positively charged, have the effect of reducing the stiffness of nanosized liposomes, independently of the saturation degree of the lipid acyl chains; the measured stiffness values of liposomes containing charged lipids are 30-60% lower than those of their neutral counterpart liposomes. In addition, we demonstrated that the Laurdan generalized polarization values, which are related to the hydration degree of the liposomal membrane interface and often used as a qualitative indicator of liposomal membrane stiffness, do not directly correlate with the physical stiffness values of the liposomes prepared in this study. However, our results indicate that direct quantitative AFM measurement is a valuable method to gain molecular-scale information about how the hydration degree of liposomal interfaces reflects (or does not reflect) liposome stiffness as a macroscopic property. Our AFM method will contribute to the quantitative characterization of the nano-bio interaction of nanoparticles and to the optimization of the lipid composition of liposomes for clinical use.

  5. Amphibole-bearing multiphase solid inclusions in olivine, the Murotomisaki Gabbro, Southwest Japan: An evidence of hydrous flux melting

    NASA Astrophysics Data System (ADS)

    Hoshide, T.; Obata, M.

    2009-12-01

    The Murotomisaki Gabbro is a sill-like layered intrusion of up to 220m thickness exposed near Cape Muroto, Southwest Japan. Despite the small size of the intrusion, it contains well-developed centimeter- to meter-scale layered structures of modal variation of olivine, plagioclase and augite. Hoshide et al (2006a, b) identified the ’crystal accumulation zone’ (40m from the bottom) that was formed by gravitational settling of olivine crystals and the ’crystal growth zone’ (40-100m from the bottom), in which olivine crystals grew significantly. The fine-scale compositional layering is best developed in the ’crystal growth zone’. Amphibole-bearing multiphase solid inclusions (called ‘the amphibole-clot inclusions’) are common in olivine crystals from both the crystal accumulation- and the crystal growth zones. The amphibole clot inclusions show spherical or convex-polygonal shapes and are composed of pargasitic amphibole, biotite and orthopyroxene, with minor amounts of augite, apatite and opaque minerals. Plagioclase rarely occurs in the amphibole clot inclusions. Bulk chemical compositions of the inclusions, obtained from mineral microprobe analyses and modal composition, are characteristically high in MgO content (16-23 wt %) and they roughly lie between presumable fractionated melt compositions and olivine compositions. From observations above, it is likely that amphibole clot inclusions are of melt origin, which had formed from some hydrous melts probably entrapped in growing olivine crystals. However, it may be difficult to explain both the very magnesian nature of the inclusion and absence of plagioclase in the inclusion by the crystallization of the normal hydrous basaltic melt. The difficulty may be resolved if we suppose, for a trapped melt composition, a more magnesian (i.e., picritic) composition. The highly magnesian nature of the amphibole clot inclusions may suggest that significant amount of olivine component had been added to

  6. Self-assembled Ag nanoparticle network passivated by a nano-sized ZnO layer for transparent and flexible film heaters

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Seo, Ki-Won; Kim, Han-Ki, E-mail: imdlhkkim@khu.ac.kr; Kim, Min-Yi

    2015-12-15

    We investigated a self-assembled Ag nanoparticle network electrode passivated by a nano-sized ZnO layer for use in high-performance transparent and flexible film heaters (TFFHs). The low temperature atomic layer deposition of a nano-sized ZnO layer effectively filled the uncovered area of Ag network and improved the current spreading in the self-assembled Ag network without a change in the sheet resistance and optical transmittance as well as mechanical flexibility. The time-temperature profiles and heat distribution analysis demonstrate that the performance of the TFTH with the ZnO/Ag network is superior to that of a TFFH with Ag nanowire electrodes. In addition, themore » TFTHs with ZnO/Ag network exhibited better stability than the TFFH with a bare Ag network due to the effective current spreading through the nano-sized ZnO layer.« less

  7. The adsorption interaction of a rutin-biopolymer complex with nanosized silica particles

    NASA Astrophysics Data System (ADS)

    Fedyanina, T. V.; Barvinchenko, V. N.; Lipkovskaya, N. A.; Pogorelyi, V. K.

    2008-10-01

    The influence of complex formation with biopolymers on the optical and acid properties of natural flavonoid rutin was studied. The adsorption interaction of biologically active flavonoids from officinal plants with the surface of nanosized silica particles was found to depend on the chemical nature of the biopolymer and adsorbate and solution properties.

  8. Dietary bioavailability of Cu adsorbed to colloidal hydrous ferric oxide

    USGS Publications Warehouse

    Cain, Daniel J.; Croteau, Marie-Noële; Fuller, Christopher C.

    2013-01-01

    The dietary bioavailability of copper (Cu) adsorbed to synthetic colloidal hydrous ferric oxide (HFO) was evaluated from the assimilation of 65Cu by two benthic grazers, a gastropod and a larval mayfly. HFO was synthesized, labeled with 65Cu to achieve a Cu/Fe ratio comparable to that determined in naturally formed HFO, and then aged. The labeled colloids were mixed with a food source (the diatom Nitzschia palea) to yield dietary 65Cu concentrations ranging from 211 to 2204 nmol/g (dry weight). Animals were pulse fed the contaminated diet and assimilation of 65Cu from HFO was determined following 1–3 days of depuration. Mass transfer of 65Cu from HFO to the diatom was less than 1%, indicating that HFO was the source of 65Cu to the grazers. Estimates of assimilation efficiency indicated that the majority of Cu ingested as HFO was assimilated (values >70%), implying that colloidal HFO potentially represents a source of dietary Cu to benthic grazers, especially where there is active formation and infiltration of these particles into benthic substrates.

  9. 75 FR 70583 - Cobalt Lithium Manganese Nickel Oxide; Withdrawal of Significant New Use Rule

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-18

    ... 2070-AB27 Cobalt Lithium Manganese Nickel Oxide; Withdrawal of Significant New Use Rule AGENCY... chemical substance identified as cobalt lithium manganese nickel oxide (CAS No. 182442-95-1), which was the... lithium manganese nickel oxide (PMN P-04-269; CAS No. 182442-95-1) at 40 CFR 721.10201 because the Agency...

  10. [Studies on semen quality in workers exposed to manganese and electric welding].

    PubMed

    Wu, W; Zhang, Y; Zhang, F

    1996-09-01

    Three hundred and ten workers were selected to study the effects of manganese and electric welding on male reproductive function, with 211 occupationally exposed to manganess and electric welding fume and 99 controls. Concentrations of manganese and welding fume in the air of the workplace were 0.14-5.5 mg/m3 and 6.5-82.3 mg/m3, respectively. Semen concentrations of manganese, copper, chromium, nickel, and iron in workers employed in electric welding were significantly higher than those in controls. Time from ejaculation to liquefaction of semen in exposed workers was longer than that in controls, and volume of semen, sperm count, viable sperm count and percentage were significantly lower in the exposed workers than in the controls. Stepwise regression analysis suggests a direct toxic effect of manganese on sperm production.

  11. Energetic basis of catalytic activity of layered nanophase calcium manganese oxides for water oxidation.

    PubMed

    Birkner, Nancy; Nayeri, Sara; Pashaei, Babak; Najafpour, Mohammad Mahdi; Casey, William H; Navrotsky, Alexandra

    2013-05-28

    Previous measurements show that calcium manganese oxide nanoparticles are better water oxidation catalysts than binary manganese oxides (Mn3O4, Mn2O3, and MnO2). The probable reasons for such enhancement involve a combination of factors: The calcium manganese oxide materials have a layered structure with considerable thermodynamic stability and a high surface area, their low surface energy suggests relatively loose binding of H2O on the internal and external surfaces, and they possess mixed-valent manganese with internal oxidation enthalpy independent of the Mn(3+)/Mn(4+) ratio and much smaller in magnitude than the Mn2O3-MnO2 couple. These factors enhance catalytic ability by providing easy access for solutes and water to active sites and facile electron transfer between manganese in different oxidation states.

  12. Nano-sized, quaternary titanium(IV) metal-organic frameworks with multidentate ligands.

    PubMed

    Baranwal, Balram Prasad; Singh, Alok Kumar

    2010-12-01

    Some mononuclear nano-sized, quaternary titanium(IV) complexes having the general formula [Ti(acac)(OOCR)2(SB)] (where Hacac=acetylacetone, R=C15H31 or C17H35, HSB=Schiff bases) have been synthesized using different multidentate ligands. These were characterized by elemental analyses, molecular weight determinations and spectral (FTIR, 1H NMR and powder XRD) studies. Conductance measurement indicated their non-conducting nature which may behave like insulators. Structural parameters like the values of limiting indices h, k, l, cell constants a, b, c, angles α, β, γ and particle size are calculated from powder XRD data for complex 1 which indicated nano-sized triclinic system in them. Bidentate chelating nature of acetylacetone, carboxylate and Schiff base anions in the complexes was established by their infrared spectra. Molecular weight determinations confirmed mononuclear nature of the complexes. On the basis of physico-chemical studies, coordination number 8 was assigned for titanium(IV) in the complexes. Transmission electron microscopy (TEM) and the selected area electron diffraction (SAED) studies indicated spherical particles with poor crystallinity. Copyright © 2010 Elsevier B.V. All rights reserved.

  13. Ternary manganese ferrite/graphene/polyaniline nanostructure with enhanced electrochemical capacitance performance

    NASA Astrophysics Data System (ADS)

    Xiong, Pan; Hu, Chenyao; Fan, Ye; Zhang, Wenyao; Zhu, Junwu; Wang, Xin

    2014-11-01

    A ternary manganese ferrite/graphene/polyaniline (MGP) nanostructure is designed and synthesized via a facile two-step approach. This nanostructure exhibits outstanding electrochemical performances, such as high specific capacitance (454.8 F g-1 at 0.2 A g-1), excellent rate capability (75.8% capacity retention at 5 A g-1), and good cycling stability (76.4% capacity retention after 5000 cycles at 2 A g-1), which are superior to those of its individual components (manganese ferrite, reduced-graphene oxide, polyaniline) and corresponding binary hybrids (manganese ferrite/graphene (MG), manganese ferrite/polyaniline (MP), and graphene/polyaniline (GP)). A symmetric supercapacitor device using the as-obtained hybrid has been fabricated and tested. The device exhibits a high specific capacitance of 307.2 F g-1 at 0.1 A g-1 with a maximum energy density of 13.5 W h kg-1. The high electrochemical performance of ternary MGP can be attributed to its well-designed nanostructure and the synergistic effect of the individual components.

  14. In situ study at high pressure and temperature of the environment of water in hydrous Na and Ca aluminosilicate melts and coexisting aqueous fluids

    NASA Astrophysics Data System (ADS)

    Le Losq, Charles; Dalou, Célia; Mysen, Bjorn O.

    2017-07-01

    The bonding and speciation of water dissolved in Na silicate and Na and Ca aluminosilicate melts were inferred from in situ Raman spectroscopy of the samples, in hydrothermal diamond anvil cells, while at crustal temperature and pressure conditions. Raman data were also acquired on Na silicate and Na and Ca aluminosilicate glasses, quenched from hydrous melts equilibrated at high temperature and pressure in a piston cylinder apparatus. In the hydrous melts, temperature strongly influences O-H stretching ν(O-H) signals, reflecting its control on the bonding of protons between different molecular complexes. Pressure and melt composition effects are much smaller and difficult to discriminate with the present data. However, the chemical composition of the melt + fluid system influences the differences between the ν(O-H) signals from the melts and the fluids and, hence, between their hydrogen partition functions. Quenching modifies the O-H stretching signals: strong hydrogen bonds form in the glasses below the glass transition temperature Tg, and this phenomenon depends on glass composition. Therefore, glasses do not necessarily record the O-H stretching signal shape in melts near Tg. The melt hydrogen partition function thus cannot be assessed with certainty using O-H stretching vibration data from glasses. From the present results, the ratio of the hydrogen partition functions of hydrous silicate melts and aqueous fluids mostly depends on temperature and the bulk melt + fluid system chemical composition. This implies that the fractionation of hydrogen isotopes between magmas and aqueous fluids in water-saturated magmatic systems with differences in temperature and bulk chemical composition will be different.

  15. Banana peel reductant for leaching medium grade manganese ore in sulfuric acid solution

    NASA Astrophysics Data System (ADS)

    Aripin, H.; Joni, I. Made; Busaeri, Nundang; Usrah, Ifkar; Sudiana, I. Nyoman; Sabchevski, Svilen

    2017-03-01

    In this investigation, manganese has been produced from medium grade manganese ore from Karangnunggal mine (West Java, Indonesia). The effects of weighed amount of banana peels on the structural and leaching properties have been studied. The material's properties have been characterized on the basis of the experimental data obtained using X-ray fluorescence (XRF), X-ray diffraction (XRD), and Fourier transforms infrared (FTIR) spectroscopy. It has been found that an increase of the weighed amount of banana peels up to 4 g leads to an increase of the leaching efficiency of manganese from manganese ore. Above 4 g, however, the leaching efficiency does not change significantly. The analysis based on the interpretation of both XRD patterns and FTIR spectrum allows one to explain the increase in the leaching efficiencies of manganese by the reduction of MnO2 minerals and by the removal of hemicelluloses groups of banana peel in the samples.

  16. Chronic organic manganese administration in the rat does not damage dopaminergic nigrostriatal neurons.

    PubMed

    Yong, V W; Perry, T L; Godolphin, W J; Jones, K A; Clavier, R M; Ito, M; Foulks, J G

    1986-01-01

    In an attempt to produce an animal model of Parkinson's disease, we injected rats repeatedly with high doses of methylcyclopentadienyl manganese tricarbonyl (MMT), a compound which has been reported to lower striatal dopamine content in mice. Chronic MMT administration for up to 5 months, even though it produced a substantial elevation in brain manganese content during the period of exposure, did not destroy dopaminergic nigrostriatal neurons. This was assessed by measurements of tyrosine hydroxylase activity and contents of dopamine and its metabolites in the striatum, and by histological examination of the substantia nigra. Our results differ from those of others who administered manganese chloride in drinking water to rats. This discrepancy is unlikely to be a consequence of differences in duration of exposure or route of administration. It could be due to our having used an organic rather than an inorganic manganese compound, or to a species difference in vulnerability to organic manganese between rats and mice.

  17. Proton conduction in electrolyte made of manganese dioxide for hydrogen gas sensor

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Koyanaka, Hideki; Ueda, Yoshikatsu; Takeuchi, K

    2012-01-01

    We propose a network model of oxygen-pairs to store and conduct protons on the surface of manganese dioxide with a weak covalent bond like protons stored in pressured ice. The atomic distances of oxygen-pairs were estimated between 2.57 and 2.60 angstroms in crystal structures of ramsdellite-type and lambda-type manganese dioxides by using protonated samples and inelastic neutron scattering measurements. Good properties for a hydrogen gas sensor using electrolytes made of manganese dioxides that contain such oxygen-pairs were confirmed experimentally.

  18. Diffusion of hydrous species in model basaltic melt

    NASA Astrophysics Data System (ADS)

    Zhang, Li; Guo, Xuan; Wang, Qinxia; Ding, Jiale; Ni, Huaiwei

    2017-10-01

    Water diffusion in Fe-free model basaltic melt with up to 2 wt% H2O was investigated at 1658-1846 K and 1 GPa in piston-cylinder apparatus using both hydration and diffusion couple techniques. Diffusion profiles measured by FTIR are consistent with a model in which both molecular H2O (H2Om) and hydroxyl (OH) contribute to water diffusion. OH diffusivity is roughly 13% of H2Om diffusivity, showing little dependence on temperature or water concentration. Water diffusion is dominated by the motion of OH until total H2O (H2Ot) concentration reaches 1 wt%. The dependence of apparent H2Ot diffusivity on H2Ot concentration appears to be overestimated by a previous study on MORB melt, but H2Ot diffusivity at 1 wt% H2Ot in basaltic melt is still greater than those in rhyolitic to andesitic melts. The appreciable contribution of OH to water diffusion in basaltic melt can be explained by enhanced mobility of OH, probably associated with the development of free hydroxyl bonded with network-modifying cations, as well as higher OH concentration. Calculation based on the Nernst-Einstein equation demonstrates that OH may serve as an effective charge carrier in hydrous basaltic melt, which could partly account for the previously observed strong influence of water on electrical conductivity of basaltic melt.

  19. Ab initio calculation of 1H, 17O, 27Al and 29Si NMR parameters, vibrational frequencies and bonding energetics in hydrous silica and Na-aluminosilicate glasses

    NASA Astrophysics Data System (ADS)

    Kubicki, J. D.; Sykes, D. G.

    2004-10-01

    Ab initio, molecular orbital (MO) calculations were performed on model systems of SiO 2, NaAlSi 3O 8 (albite), H 2O-SiO 2 and H 2O-NaAlSi 3O 8 glasses. Model nuclear magnetic resonance (NMR) isotropic chemical shifts (δ iso) for 1H, 17O, 27Al and 29Si are consistent with experimental data for the SiO 2, NaAlSi 3O 8, H 2O-SiO 2 systems where structural interpretations of the NMR peak assignments are accepted. For H 2O-NaSi 3AlO 8 glass, controversy has surrounded the interpretation of NMR and infrared (IR) spectra. Calculated δ iso1H, δ iso17O, δ iso27Al and δ iso29Si are consistent with the interpretation of Kohn et al. (1992) that Si-(OH)-Al linkages are responsible for the observed peaks in hydrous Na-aluminosilicate glasses. In addition, a theoretical vibrational frequency associated with the Kohn et al. (1992) model agrees well with the observed shoulder near 900 cm -1 in the IR and Raman spectra of hydrous albite glasses. MO calculations suggest that breaking this Si-(OH)-Al linkage requires ˜+56 to +82 kJ/mol which is comparable to the activation energies for viscous flow in hydrous aluminosilicate melts.

  20. Mercury distribution characteristics in primary manganese smelting plants.

    PubMed

    Back, Seung-Ki; Sung, Jin-Ho; Moon, Young-Hoon; Kim, Young-Hee; Seok, Kwang-Seol; Song, Geum-Ju; Seo, Yong-Chil

    2017-08-01

    The mercury (Hg) distribution characteristics were investigated in three primary manganese smelting plants in Korea for the assessment of anthropogenic Hg released. Input and output materials were sampled from each process, and Hg concentrations in the samples were analyzed. Among the input materials, the most mercury was found in the manganese ore (83.1-99.7%) and mercury was mainly released through fly ash or off gas, depending on the condition of off gas cleaning system. As off gas temperature decreases, proportion and concentration of emitted gaseous elemental mercury (Hg 0 ) in off gas decreases. Based on mass balance study from these three plants and national manganese production data, the total amount of mercury released from those Korean plants was estimated to 644 kg/yr. About half of it was emitted into the air while the rest was released to waste as fly ash. With the results of this investigation, national inventory for Hg emission and release could be updated for the response to Minamata Convention on Mercury. Copyright © 2017. Published by Elsevier Ltd.

  1. The corrosive nature of manganese in drinking water.

    PubMed

    Alvarez-Bastida, C; Martínez-Miranda, V; Vázquez-Mejía, G; Solache-Ríos, M; Fonseca-Montes de Oca, G; Trujillo-Flores, E

    2013-03-01

    Corrosion problems having to do with drinking water distribution systems are related to many processes and factors and two of them are ionic acidity and carbon dioxide, which were considered in this work. The corrosion character of water is determined by the corrosion indexes of Langelier, Ryznar, Larson, and Mojmir. The results show that pipes made of different materials, such as plastics or metals, are affected by corrosion, causing manganese to be deposited on materials and dissolved in water. The deterioration of the materials, the degree of corrosion, and the deposited corrosion products were determined by X-ray diffraction and Scanning Electron Microscopy. High levels of manganese and nitrate ions in water may cause serious damage to the health of consumers of water. Three wells were examined, one of them presented a high content of manganese; the others had high levels of nitrate ions, which increased the acidity of the water and, therefore, the amount of corrosion of the materials in the distribution systems. Copyright © 2013 Elsevier B.V. All rights reserved.

  2. Manganese in occupational arc welding fumes--aspects on physiochemical properties, with focus on solubility.

    PubMed

    Taube, Fabian

    2013-01-01

    Physicochemical properties, such as particle sizes, composition, and solubility of welding fumes are decisive for the bioaccessibility of manganese and thereby for the manganese cytotoxic and neurotoxic effects arising from various welding fumes. Because of the diverse results within the research on welding fume solubility, this article aims to review and discuss recent literature on physicochemical properties of gas metal arc welding, shielded metal arc welding, and flux-cored arc welding fumes, with focus on solubility properties. This article also presents a short introduction to the literature on arc welding techniques, health effects from manganese, and occupational exposure to manganese among welders.

  3. From lead to manganese through mercury: mythology, science, and lessons for prevention.

    PubMed

    Alessio, Lorenzo; Campagna, Marcello; Lucchini, Roberto

    2007-11-01

    Lead (Pb), mercury (Hg), and manganese (Mn) are well-known neurotoxic metals. The knowledge of toxicity was developed through an extensive amount of research, starting with lead and mercury and proceeding today with manganese. Unfortunately, the consequent implementation of preventive measures was generally delayed, causing important negative effects to the exposed populations. A review and historical reconstruction of the research development that yielded modern understanding of lead and mercury neurotoxicity was conducted to derive useful lessons for the prevention of manganese neurotoxicity. Medieval alchemists named planets and metals from gods since they were already aware of the toxicity and the adverse effects caused by lead and mercury. Historical lessons learned from these two metals may help to avoid the repetition of further mistakes regarding other neurotoxic metals like manganese. The knowledge and experience on the toxicokinetics and toxicodynamics of lead and mercury is useful and valuable to identify a proper approach to "safe" exposure levels for manganese. Further information is still needed on the early neurotoxic and neurobehavioral effects after prolonged exposure to very low doses of lead, mercury, and manganese. Nevertheless, according to the precautionary principle, effective preventive measures should be already undertaken to prevent the onset of more severe health effects in the population. This is the most important lesson to be learned and applied from more than 30 years of occupational and environmental neurotoxicology of metals. (c) 2007 Wiley-Liss, Inc.

  4. Dissection of the mechanism of manganese porphyrin-catalyzed chlorine dioxide generation.

    PubMed

    Umile, Thomas P; Wang, Dong; Groves, John T

    2011-10-17

    Chlorine dioxide, an industrially important biocide and bleach, is produced rapidly and efficiently from chlorite ion in the presence of water-soluble, manganese porphyrins and porphyrazines at neutral pH under mild conditions. The electron-deficient manganese(III) tetra-(N,N-dimethyl)imidazolium porphyrin (MnTDMImP), tetra-(N,N-dimethyl)benzimidazolium (MnTDMBImP) porphyrin, and manganese(III) tetra-N-methyl-2,3-pyridinoporphyrazine (MnTM23PyPz) were found to be the most efficient catalysts for this process. The more typical manganese tetra-4-N-methylpyridiumporphyrin (Mn-4-TMPyP) was much less effective. Rates for the best catalysts were in the range of 0.24-32 TO/s with MnTM23PyPz being the fastest. The kinetics of reactions of the various ClO(x) species (e.g., chlorite ion, hypochlorous acid, and chlorine dioxide) with authentic oxomanganese(IV) and dioxomanganese(V)MnTDMImP intermediates were studied by stopped-flow spectroscopy. Rate-limiting oxidation of the manganese(III) catalyst by chlorite ion via oxygen atom transfer is proposed to afford a trans-dioxomanganese(V) intermediate. Both trans-dioxomanganese(V)TDMImP and oxoaqua-manganese(IV)TDMImP oxidize chlorite ion by 1-electron, generating the product chlorine dioxide with bimolecular rate constants of 6.30 × 10(3) M(-1) s(-1) and 3.13 × 10(3) M(-1) s(-1), respectively, at pH 6.8. Chlorine dioxide was able to oxidize manganese(III)TDMImP to oxomanganese(IV) at a similar rate, establishing a redox steady-state equilibrium under turnover conditions. Hypochlorous acid (HOCl) produced during turnover was found to rapidly and reversibly react with manganese(III)TDMImP to give dioxoMn(V)TDMImP and chloride ion. The measured equilibrium constant for this reaction (K(eq) = 2.2 at pH 5.1) afforded a value for the oxoMn(V)/Mn(III) redox couple under catalytic conditions (E' = 1.35 V vs NHE). In subsequent processes, chlorine dioxide reacts with both oxomanganese(V) and oxomanganese(IV)TDMImP to afford chlorate

  5. Photodegradation of surfactants on the nanosized TiO2 prepared by hydrolysis of the alkoxide titanium.

    PubMed

    Zhang, Rubing; Gao, Lian; Zhang, Qinghong

    2004-01-01

    Nanosized TiO(2) was synthesized by hydrolysis of titanium tetraisopropoxide in the nanodroplets of microemulsions. The microemulsion provided by functionalized surfactants derived from the mixture of the commercially available sodium dodecylbenzensulfonate (DBS) and sodium dodecyl sulfate (DS). The resulting TiO(2) nanoparticles were characterized by transmission electron microscopy, X-ray diffraction, and differential thermal analysis. Nanosized TiO(2) of anatase was found to show good photocatalytic properties in the photodegradation of DBS and DS surfactants. The cleavage of the aromatic moiety, the intermediate products and ultimate mineralization to CO(2) were examined in the process of photodegradation. A mechanism is also proposed on the basis of these experimental results.

  6. Energetic basis of catalytic activity of layered nanophase calcium manganese oxides for water oxidation

    PubMed Central

    Birkner, Nancy; Nayeri, Sara; Pashaei, Babak; Najafpour, Mohammad Mahdi; Casey, William H.; Navrotsky, Alexandra

    2013-01-01

    Previous measurements show that calcium manganese oxide nanoparticles are better water oxidation catalysts than binary manganese oxides (Mn3O4, Mn2O3, and MnO2). The probable reasons for such enhancement involve a combination of factors: The calcium manganese oxide materials have a layered structure with considerable thermodynamic stability and a high surface area, their low surface energy suggests relatively loose binding of H2O on the internal and external surfaces, and they possess mixed-valent manganese with internal oxidation enthalpy independent of the Mn3+/Mn4+ ratio and much smaller in magnitude than the Mn2O3-MnO2 couple. These factors enhance catalytic ability by providing easy access for solutes and water to active sites and facile electron transfer between manganese in different oxidation states. PMID:23667149

  7. Solution combustion synthesis and characterization of nanosized bismuth ferrite

    NASA Astrophysics Data System (ADS)

    Sai Kumar, V. Sesha; Rao, K. Venkateswara; Krishnaveni, T.; Kishore Goud, A. Shiva; Reddy, P. Ranjith

    2012-06-01

    The present paper describes a simple method of nanosized BiFeO3 by the solution combustion synthesis using bismuth and iron nitrates as oxidizers and the combination fuel of citric acid and ammonium hydroxide, with fuel to oxidizer ratio (Ψ = 1) one. The X-ray Diffraction results indicated rhombohedral phase (R3m) with JCPDS data card no: 72-2035. The ferroelectric transition of the sample at 8310C was detected by differential thermal analysis. Thermal analysis was done by Thermal gravimetric-Differential thermal analyzer and obtained results were presented in this paper.

  8. Manganese-Enhanced MRI: Biological Applications in Neuroscience

    PubMed Central

    Malheiros, Jackeline Moraes; Paiva, Fernando Fernandes; Longo, Beatriz Monteiro; Hamani, Clement; Covolan, Luciene

    2015-01-01

    Magnetic resonance imaging (MRI) is an excellent non-invasive tool to investigate biological systems. The administration of the paramagnetic divalent ion manganese (Mn2+) enhances MRI contrast in vivo. Due to similarities between Mn2+ and calcium (Ca2+), the premise of manganese-enhanced MRI (MEMRI) is that the former may enter neurons and other excitable cells through voltage-gated Ca2+ channels. As such, MEMRI has been used to trace neuronal pathways, define morphological boundaries, and study connectivity in morphological and functional imaging studies. In this article, we provide a brief overview of MEMRI and discuss recently published data to illustrate the usefulness of this method, particularly in animal models. PMID:26217304

  9. Manganese oxide particles as cytoprotective, oxygen generating agents.

    PubMed

    Tootoonchi, Mohammad Hossein; Hashempour, Mazdak; Blackwelder, Patricia L; Fraker, Christopher A

    2017-09-01

    Cell culture and cellular transplant therapies are adversely affected by oxidative species and radicals. Herein, we present the production of bioactive manganese oxide nanoparticles for the purpose of radical scavenging and cytoprotection. Manganese comprises the core active structure of somatic enzymes that perform the same function, in vivo. Formulated nanoparticles were characterized structurally and surveyed for maximal activity (superoxide scavenging, hydrogen peroxide scavenging with resultant oxygen generation) and minimal cytotoxicity (48-h direct exposure to titrated manganese oxide concentrations). Cytoprotective capacity was tested using cell exposure to hydrogen peroxide in the presence or absence of the nanoparticles. Several ideal compounds were manufactured and utilized that showed complete disproportionation of superoxide produced by the xanthine/xanthine oxidase reaction. Further, the nanoparticles showed catalase-like activity by completely converting hydrogen peroxide into the corresponding concentration of oxygen. Finally, the particles protected cells (murine β-cell insulinoma) against insult from hydrogen peroxide exposure. Based on these observed properties, these particles could be utilized to combat oxidative stress and inflammatory response in a variety of cell therapy applications. Maintaining viability once cells have been removed from their physiological niche, e.g. culture and transplant, demands proper control of critical variables such as oxygenation and removal of harmful substances e.g. reactive oxygen species. Limited catalysts can transform reactive oxygen species into molecular oxygen and, thereby, have the potential to maintain cell viability and function. Among these are manganese oxide particles which are the subject of this study. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  10. Characteristics of nano-sized yttria powder synthesized by a polyvinyl alcohol solution route at low temperature.

    PubMed

    Lee, Sang-Jin; Jung, Choong-Hwan

    2012-01-01

    Nano-sized yttria (Y2O3) powders were successfully synthesized at a low temperature of 400 degrees C by a simple polymer solution route. PVA polymer, as an organic carrier, contributed to an atom-scale homogeneous precursor gel and it resulted in fully crystallized, nano-sized yttria powder with high specific surface area through the low temperature calcination. In this process, the content of PVA, calcination temperature and heating time affected the microstructure and crystallization behavior of the powders. The development of crystalline phase and the final particle size were strongly dependant on the oxidation reaction from the polymer burn-out step and the PVA content. In this paper, the PVA solution technique for the fabrication of nano-sized yttria powders is introduced. The effects of PVA content and holding time on the powder morphology and powder specific surface area are also studied. The characterization of the synthesized powders is examined by using XRD, DTA/TG, SEM, TEM and nitrogen gas adsorption. The yttria powder synthesized from the PVA content of 3:1 ratio and calcined at 400 degrees C had a crystallite size of about 20 nm or less with a high surface areas of 93.95-120.76 m2 g(-1).

  11. Manganese deposition in drinking water distribution systems.

    PubMed

    Gerke, Tammie L; Little, Brenda J; Barry Maynard, J

    2016-01-15

    This study provides a physicochemical assessment of manganese deposits on brass and lead components from two fully operational drinking water distributions systems. One of the systems was maintained with chlorine; the other, with secondary chloramine disinfection. Synchrotron-based in-situ micro X-ray adsorption near edge structure was used to assess the mineralogy. In-situ micro X-ray fluorescence mapping was used to demonstrate the spatial relationships between manganese and potentially toxic adsorbed metal ions. The Mn deposits ranged in thickness from 0.01 to 400 μm. They were composed primarily of Mn oxides/oxhydroxides, birnessite (Mn(3+) and Mn(4+)) and hollandite (Mn(2+) and Mn(4+)), and a Mn silicate, braunite (Mn(2+) and Mn(4+)), in varying proportions. Iron, chromium, and strontium, in addition to the alloying elements lead and copper, were co-located within manganese deposits. With the exception of iron, all are related to specific health issues and are of concern to the U.S. Environmental Protection Agency (U.S. EPA). The specific properties of Mn deposits, i.e., adsorption of metals ions, oxidation of metal ions and resuspension are discussed with respect to their influence on drinking water quality. Copyright © 2015 Elsevier B.V. All rights reserved.

  12. Elasticity of Pargasite Amphibole: A Hydrous Phase at Mid Lithospheric Discontinuity

    NASA Astrophysics Data System (ADS)

    Peng, Y.; Mookherjee, M.

    2017-12-01

    Mid Lithospheric Discontinuity (MLD) is characterized by a low shear wave velocity ( 3 to 10 %). In cratons, the depth of MLD varies between 80 and 100 km. The reduction of the shear wave velocity at MLD is similar to what is observed in the lithosphere-asthenosphere boundary (LAB). Such low velocity at MLD could be caused by partial melting, temperature induced grain boundary sliding, changes in the elastic anisotropy, and/or metasomatism which may lead to the formation of hydrous phases including mica and amphibole. Thus, it is clear that in order to assess the role of metasomatism at MLD, we need better constraints on the elasticity of hydrous phases. However, such elasticity data are scarce. In this study, we explore elasticity of pargasite amphibole [NaCa2(Mg4Al)(Si6Al2)O22(OH)2] using density functional theory (DFT) with local density approximation (LDA) and generalized gradient approximation (GGA). We find that the pressure-volume results can be adequately described by a finite strain equation with the bulk modulus, K0 being 102 and 85 GPa for LDA and GGA respectively. We also determined the full elastic constant tensor (Cij) using the finite difference method. The bulk modulus, K0 determined from the full elastic constant tensor is 104 GPa for LDA and 87 GPa for GGA. The shear modulus, G0 determined from the full elastic constant tensor is 64 GPa for LDA and 58 GPa for GGA. The bulk and shear moduli predicted with LDA are 5 and 1 % stiffer than the recent results [1]. In contrast, the bulk and shear moduli predicted with GGA are 12 and 10 % softer compared to the recent results [1]. The full elastic constant tensor for pargasite shows significant anisotropy. For instance, LDA predicts compressional (AVP) and shear (AVS) wave anisotropy of 22 and 20 % respectively. At higher pressure, elastic moduli stiffen. However, temperature is likely to have an opposite effect on the elasticity and this remains largely unknown for pargasite. Compared to the major mantle

  13. Discrete Responses to Limitation for Iron and Manganese in Agrobacterium tumefaciens: Influence on Attachment and Biofilm Formation

    PubMed Central

    Hibbing, Michael E.; Xu, Jing; Natarajan, Ramya; Buechlein, Aaron M.

    2015-01-01

    ABSTRACT Transition metals such as iron and manganese are crucial trace nutrients for the growth of most bacteria, functioning as catalytic cofactors for many essential enzymes. Dedicated uptake and regulatory systems have evolved to ensure their acquisition for growth, while preventing toxicity. Transcriptomic analysis of the iron- and manganese-responsive regulons of Agrobacterium tumefaciens revealed that there are discrete regulatory networks that respond to changes in iron and manganese levels. Complementing earlier studies, the iron-responsive gene network is quite large and includes many aspects of iron-dependent metabolism and the iron-sparing response. In contrast, the manganese-responsive network is restricted to a limited number of genes, many of which can be linked to transport and utilization of the transition metal. Several of the target genes predicted to drive manganese uptake are required for growth under manganese-limited conditions, and an A. tumefaciens mutant with a manganese transport deficiency is attenuated for plant virulence. Iron and manganese limitation independently inhibit biofilm formation by A. tumefaciens, and several candidate genes that could impact biofilm formation were identified in each regulon. The biofilm-inhibitory effects of iron and manganese do not rely on recognized metal-responsive transcriptional regulators, suggesting alternate mechanisms influencing biofilm formation. However, under low-manganese conditions the dcpA operon is upregulated, encoding a system that controls levels of the cyclic di-GMP second messenger. Mutation of this regulatory pathway dampens the effect of manganese limitation. IMPORTANCE Responses to changes in transition metal levels, such as those of manganese and iron, are important for normal metabolism and growth in bacteria. Our study used global gene expression profiling to understand the response of the plant pathogen Agrobacterium tumefaciens to changes of transition metal availability

  14. Discovery of Ni-smectite-rich saprolite at Loma Ortega, Falcondo mining district (Dominican Republic): geochemistry and mineralogy of an unusual case of "hybrid hydrous Mg silicate - clay silicate" type Ni-laterite

    NASA Astrophysics Data System (ADS)

    Tauler, Esperança; Lewis, John F.; Villanova-de-Benavent, Cristina; Aiglsperger, Thomas; Proenza, Joaquín A.; Domènech, Cristina; Gallardo, Tamara; Longo, Francisco; Galí, Salvador

    2017-10-01

    Hydrous Mg silicate-type Ni-laterite deposits, like those in the Falcondo district, Dominican Republic, are dominated by Ni-enriched serpentine and garnierite. Recently, abundant Ni-smectite in the saprolite zone have been discovered in Loma Ortega, one of the nine Ni-laterite deposits in Falcondo. A first detailed study on these Ni-smectites has been performed (μXRD, SEM, EPMA), in addition to a geochemical and mineralogical characterisation of the Loma Ortega profile (XRF, ICP-MS, XRD). Unlike other smectite occurrences in laterite profiles worldwide, the Loma Ortega smectites are trioctahedral and exhibit high Ni contents never reported before. These Ni-smectites may be formed from weathering of pyroxene and olivine, and their composition can be explained by the mineralogy and the composition of the Al-depleted, olivine-rich parent ultramafic rock. Our study shows that Ni-laterites are mineralogically complex, and that a hydrous Mg silicate ore and a clay silicate ore can be confined to the same horizon in the weathering profile, which has significant implications from a recovery perspective. In accordance, the classification of "hybrid hydrous Mg silicate - clay silicate" type Ni-laterite deposit for Loma Ortega would be more appropriate.

  15. Uniform manganese hexacyanoferrate hydrate nanocubes featuring superior performance for low-cost supercapacitors and nonenzymatic electrochemical sensors

    NASA Astrophysics Data System (ADS)

    Pang, Huan; Zhang, Yizhou; Cheng, Tao; Lai, Wen-Yong; Huang, Wei

    2015-09-01

    Uniform manganese hexacyanoferrate hydrate nanocubes are prepared via a simple chemical precipitation method at room temperature. Due to both micro/mesopores of the Prussian blue analogue and nanocubic structures, the manganese hexacyanoferrate hydrate nanocubes allow the efficient charge transfer and mass transport for electrolyte solution and chemical species. Thus, the manganese hexacyanoferrate hydrate nanocube electrode shows a good rate capability and cycling stability for electrochemical capacitors. Furthermore, electrodes modified with manganese hexacyanoferrate hydrate nanocubes demonstrate a sensitive electrochemical response to hydrogen peroxide (H2O2) in buffer solutions with a high selectivity.Uniform manganese hexacyanoferrate hydrate nanocubes are prepared via a simple chemical precipitation method at room temperature. Due to both micro/mesopores of the Prussian blue analogue and nanocubic structures, the manganese hexacyanoferrate hydrate nanocubes allow the efficient charge transfer and mass transport for electrolyte solution and chemical species. Thus, the manganese hexacyanoferrate hydrate nanocube electrode shows a good rate capability and cycling stability for electrochemical capacitors. Furthermore, electrodes modified with manganese hexacyanoferrate hydrate nanocubes demonstrate a sensitive electrochemical response to hydrogen peroxide (H2O2) in buffer solutions with a high selectivity. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr04322k

  16. Sulfur in Hydrous, Oxidized Basaltic Magmas: Phase Equilibria and Melt Solubilities

    NASA Astrophysics Data System (ADS)

    Pichavant, M.; Scaillet, B.; di Carlo, I.; Rotolo, S.; Metrich, N.

    2006-05-01

    Basaltic magmas from subduction zone settings are typically S-rich and may be the ultimate source of sulfur in vapor phases emitted during eruptions of more silicic systems. To understand processes of sulfur recycling in subduction zones, the behaviour of S in hydrous, oxidized, mafic arc magmas must be known. Although experimental data on S-bearing basaltic melts are available for dry conditions, and under both reduced and oxidized fO2, no study has yet examined the effect of S in hydrous mafic melts. In this work, 3 starting compositions were investigated, a basaltic andesite, a K basalt and a picritic basalt. For each composition, experimental data for S-added (1 wt % elemental sulfur) and S-free charges were obtained under similar P-T- H2O-fO2. All experiments were performed at 4 kbar and at either 950 ° C (basaltic andesite), 1100 ° C (K basalt) or 1150 ° C (picritic basalt). These were carried out in an internally heated vessel pressurized with Ar-H2 mixtures and fitted with a drop-quench device, and lasted for between 15 and 99 h. Either Au (950 ° C) or AuPd alloys (1100 and 1150 ° C) were used as containers. These latter perform satisfactorily under strongly oxidizing conditions, i.e., for fO2 above NNO+1 at 1100 and 1150 ° C. Below NNO+1, Pd- Au-S-Fe phases appear in the charges, suggesting extensive interaction between S and the capsule material. Experimental redox conditions, determined from Ni-Pd-O sensors, ranged between NNO+1.3 to +4.1 (basaltic andesite), +0.6 to +2.0 (K basalt), and +0.3 to +3.6 (picritic basalt). H2O concentrations in melt ranged from 8.2 wt % (basaltic andesite), decreasing to 2.2-3.9 wt % (K basalt) and 2.5-5.0 wt % (picritic basalt). All 3 compositions studied crystallize anhydrite and Fe-Ni-S-O sulphide as saturating S-bearing phases, anhydrite at high fO2 and sulphide at lower fO2, although melt composition also influences their stability. Anhydrite is present at a fO2 as low as NNO+1.5 in the K basalt. In the picritic

  17. Lignin from Micro- to Nanosize: Applications

    PubMed Central

    Friedl, Anton

    2017-01-01

    Micro- and nanosize lignin has recently gained interest due to improved properties compared to standard lignin available today. As the second most abundant biopolymer after cellulose, lignin is readily available but used for rather low-value applications. This review focuses on the application of micro- and nanostructured lignin in final products or processes that all show potential for high added value. The fields of application are ranging from improvement of mechanical properties of polymer nanocomposites, bactericidal and antioxidant properties and impregnations to hollow lignin drug carriers for hydrophobic and hydrophilic substances. Also, a carbonization of lignin nanostructures can lead to high-value applications such as use in supercapacitors for energy storage. The properties of the final product depend on the surface properties of the nanomaterial and, therefore, on factors like the lignin source, extraction method, and production/precipitation methods, as discussed in this review. PMID:29117142

  18. Nano-sized Contrast Agents to Non-Invasively Detect Renal Inflammation by Magnetic Resonance Imaging

    PubMed Central

    Thurman, Joshua M.; Serkova, Natalie J.

    2013-01-01

    Several molecular imaging methods have been developed that employ nano-sized contrast agents to detect markers of inflammation within tissues. Renal inflammation contributes to disease progression in a wide range of autoimmune and inflammatory diseases, and a biopsy is currently the only method of definitively diagnosing active renal inflammation. However, the development of new molecular imaging methods that employ contrast agents capable of detecting particular immune cells or protein biomarkers will allow clinicians to evaluate inflammation throughout the kidneys, and to assess a patient's response to immunomodulatory drugs. These imaging tools will improve our ability to validate new therapies and to optimize the treatment of individual patients with existing therapies. This review describes the clinical need for new methods of monitoring renal inflammation, and recent advances in the development of nano-sized contrast agents for detection of inflammatory markers of renal disease. PMID:24206601

  19. Sorption of lead ions on diatomite and manganese oxides modified diatomite.

    PubMed

    Al-Degs, Y; Khraisheh, M A; Tutunji, M F

    2001-10-01

    Naturally occurring diatomaceous earth (diatomite) has been tested as a potential sorbent for Pb(II) ions. The intrinsic exchange properties were further improved by modification with manganese oxides. Modified adsorbent (referred to as Mn-diatomite) showed a higher tendency for adsorbing lead ions from solution at pH 4. The high performance exhibited by Mn-diatomite was attributed to increased surface area and higher negative surface charge after modification. Scanning electron microscope pictures revealed a birnessite structure of manganese oxides, which was featured by a plate-like-crystal structure. Diatomite filtration quality was improved after modification by manganese oxides. Good filtration qualities combined with high exchange capacity emphasised the potential use of Mn-diatomite in filtration systems.

  20. Electrochemical oxidation of sulfites by DWCNTs, MWCNTs, higher fullerenes and manganese

    NASA Astrophysics Data System (ADS)

    Uzun, Dzhamal; Pchelarov, George; Dimitrov, Ognian; Vassilev, Sasho; Obretenov, Willi; Petrov, Konstantin

    2018-03-01

    Different electrocatalysts were tested for oxidation of sulfites to sulfates, namely, manganese thin films deposited on fullerenes and carbon nanotubes. The results presented clearly show that electrodes containing HFs (higher fullerenes), DWCNTs (double-wall carbon nanotubes) and manganese acetate are effective catalysts in S/O2 fuel cells. HFs and DWCNTs have high catalytic activity and can be employed as standalone catalysts. Manganese was deposited on DWCNTs, HFs and fullerenes C60/C70 by a thermal process. The electrocatalysts were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The electrochemical testing was carried out by plotting the E/V polarization curve. The polarization curves of the electrodes composed of pristine DWCNTs showed the lowest overpotentials.

  1. Effect of mass density on surface morphology of electrodeposited manganese oxide films

    NASA Astrophysics Data System (ADS)

    Singh, Avtar; Kumar, Davinder; Thakur, Anup; Kaur, Raminder

    2018-05-01

    This work focus on high surface area morphology of manganese oxide films which are currently required for electrochemical capacitor electrode to enhance their performance. Electrodeposition of manganese oxide films was carried out using Chronoamperometry for different deposition time ranging from 30 to 120 sec. Cronoamperomertic I-T integrated data have been used to analyze active mass of all electrodeposited films. Morphological study of the deposited films with different mass was carried out through scanning electron microscopy. Film deposited for 30 sec time show highest porous morphology than others. Manganese oxide films with high porosity are suitable for electrochemical capacitor electrode.

  2. Deficiency in the manganese efflux transporter SLC30A10 induces severe hypothyroidism in mice.

    PubMed

    Hutchens, Steven; Liu, Chunyi; Jursa, Thomas; Shawlot, William; Chaffee, Beth K; Yin, Weiling; Gore, Andrea C; Aschner, Michael; Smith, Donald R; Mukhopadhyay, Somshuvra

    2017-06-09

    Manganese is an essential metal that becomes toxic at elevated levels. Loss-of-function mutations in SLC30A10, a cell-surface-localized manganese efflux transporter, cause a heritable manganese metabolism disorder resulting in elevated manganese levels and parkinsonian-like movement deficits. The underlying disease mechanisms are unclear; therefore, treatment is challenging. To understand the consequences of loss of SLC30A10 function at the organism level, we generated Slc30a10 knock-out mice. During early development, knock-outs were indistinguishable from controls. Surprisingly, however, after weaning and compared with controls, knock-out mice failed to gain weight, were smaller, and died prematurely (by ∼6-8 weeks of age). At 6 weeks, manganese levels in the brain, blood, and liver of the knock-outs were ∼20-60-fold higher than controls. Unexpectedly, histological analyses revealed that the brain and liver of the knock-outs were largely unaffected, but their thyroid exhibited extensive alterations. Because hypothyroidism leads to growth defects and premature death in mice, we assayed for changes in thyroid and pituitary hormones. At 6 weeks and compared with controls, the knock-outs had markedly reduced thyroxine levels (∼50-80%) and profoundly increased thyroid-stimulating hormone levels (∼800-1000-fold), indicating that Slc30a10 knock-out mice develop hypothyroidism. Importantly, a low-manganese diet produced lower tissue manganese levels in the knock-outs and rescued the phenotype, suggesting that manganese toxicity was the underlying cause. Our unanticipated discovery highlights the importance of determining the role of thyroid dysfunction in the onset and progression of manganese-induced disease and identifies Slc30a10 knock-out mice as a new model for studying thyroid biology. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  3. Maternal and Cord Blood Manganese Concentrations and Early Childhood Neurodevelopment among Residents near a Mining-Impacted Superfund Site.

    PubMed

    Claus Henn, Birgit; Bellinger, David C; Hopkins, Marianne R; Coull, Brent A; Ettinger, Adrienne S; Jim, Rebecca; Hatley, Earl; Christiani, David C; Wright, Robert O

    2017-06-28

    Environmental manganese exposure has been associated with adverse neurodevelopmental outcomes among school-aged children; yet, few studies have evaluated prenatal exposure. Our study examines associations between prenatal manganese concentrations and placental transfer of manganese with neurodevelopment in 224 2-y-old children residing near the Tar Creek Superfund Site. We collected maternal and cord blood at delivery, measured manganese using inductively coupled plasma mass spectrometry, and assessed neurodevelopment using the Bayley Scales of Infant Development-II. Associations between manganese and mental (MDI) and psychomotor (PDI) development indices were estimated in multivariable models. Placental transfer, approximated by cord/maternal manganese ratio, cord/total manganese ratio (total=maternal+cord), and by joint classification according to high or low (above or below median) maternal and cord manganese, was evaluated as a predictor of neurodevelopment. Median levels [interquartile ranges (IQR)] of manganese in maternal and cord blood, respectively, were 24.0 (19.5-29.7) and 43.1 (33.5-52.1) μg/L. Adjusting for lead, arsenic, and other potential confounders, an IQR increase in maternal manganese was associated with -3.0 (95% CI: -5.3, -0.7) points on MDI and -2.3 (95% CI: -4.1, -0.4) points on PDI. Cord manganese concentrations were not associated with neurodevelopment scores. Cord/maternal and cord/total manganese ratios were positively associated with MDI [cord/maternal: β=2.6 (95% Cl: −0.04, 5.3); cord/total: β=22.0 (95% Cl: 3.2, 40.7)] and PDI (cord/maternal: β=1.7 (95% Cl: −0.5, 3.9); cord/total: β=15.6 (95% Cl: 0.3, 20.9)). Compared to mother-child pairs with low maternal and cord manganese, associations with neurodevelopment scores were negative for pairs with either high maternal, high cord, or high maternal and cord manganese. Maternal blood manganese concentrations were negatively associated with early

  4. Crystal structure, thermal expansivity, and elasticity of OH-chondrodite: Trends among dense hydrous magnesium silicates

    DOE PAGES

    Ye, Yu; Jacobsen, Steven D.; Mao, Zhu; ...

    2015-04-01

    Here, we report the structure and thermoelastic properties of OH-chondrodite. The sample was synthesized at 12 GPa and 1523 K, coexisting with hydroxyl-clinohumite and hydrous olivine. The Fe content Fe/(Fe+Mg) is 1.1 mol%, and the monoclinic unit-cell parameters are: a = 4.7459(2) Å, b = 10.3480(7) Å, c = 7.9002(6) Å, α = 108.702(7)°, and V = 367.50(4) Å3. At ambient conditions the crystal structure was refined in space group P 21/b from 1915 unique reflection intensities measured by single-crystal x-ray diffraction. The volume thermal expansion coefficient was measured between 150 and 800 K, resulting in α V = 2.8(5)×10more » -9(K -2) × T + 40.9(7) × 10 -6(K -1) – 0.81(3)(K)/T 2, with an average value of 38.0(9)×10 -6 K -1. Brillouin spectroscopy was used to measure a set of acoustic velocities from which all thirteen components (C ij) of the elastic tensor were determined. The Voigt-Reuss-Hill average of the moduli yield for the adiabatic bulk modulus, K S0 = 117.9(12) GPa, and for shear modulus, G 0 = 70.1(5) GPa. The Reuss bound on the isothermal bulk modulus (K T0) is 114.2(14) GPa. From the measured thermodynamic properties, the Grüneisen parameter (γ) is calculated to be 1.66(4). Fitting previous static compression data using our independently measured bulk modulus (isothermal Reuss bound) as a fixed parameter, we refined the first pressure derivative of the bulk modulus, K T’ = 5.5(1). Systematic trends between H 2O content and physical properties are evaluated among dense hydrous magnesium silicate (DHMS) phases along the forsterite-brucite join.« less

  5. Hydrous melts weaken the mantle, crystallization of pargasite and phlogopite does not: Insights from a petrostructural study of the Finero peridotites, southern Alps

    NASA Astrophysics Data System (ADS)

    Tommasi, Andréa; Langone, Antonio; Padrón-Navarta, José Alberto; Zanetti, Alberto; Vauchez, Alain

    2017-11-01

    This study reports petrostructural observations in the pargasite and phlogopite-bearing Finero peridotite massif (Italian Western Alps), which suggest that the pervasive foliation in this massif was formed by deformation concomitant with percolation of hydrous Si-rich melts: (1) diffuse contacts, but systematic parallelism between the pyroxenitic layers and the foliation of the peridotite (2) strong shape and crystal preferred orientations (SPO and CPO), but subhedral or interstitial shapes and weak intracrystalline deformation of the hydrous phases, (3) CPO, but interstitial shapes of the pyroxenes, (4) very coarse olivine grain sizes, which are correlated to the olivine abundance, and (5) elongated shapes, but weak intracrystalline deformation, and extremely weak and highly variable CPO of olivine. The pervasive deformation of the Finero peridotite occurred therefore under conditions that allowed coexistence of H2O-CO2-bearing melts, pargasite, and spinel, that is, temperatures of 980-1080 °C and pressures <2 GPa. The petrostructural observations suggest that the presence of hydrous melts results in accommodation of large amounts of deformation by stress-controlled dissolution-precipitation and advective transport of matter by the melts and in fast grain boundary migration in olivine. By consequence, it produces significant rheological weakening. Water contents in olivine are <4 ppm wt., implying limited contribution of hydration of olivine to weakening. In addition, the analysis of protomylonites composing the external domains of the shear zones that overprint the pervasive foliation indicates that the transition to melt-free conditions results in enhanced contribution of dislocation creep to the deformation. The associated increase of the peridotites' strength leads to onset of strain localization. The latter is not correlated to the local abundance in pargasite or phlogopite, implying that crystallization of amphiboles or phlogopite, even at concentrations of

  6. Application of uniaxial confining-core clamp with hydrous pyrolysis in petrophysical and geochemical studies of source rocks at various thermal maturities

    USGS Publications Warehouse

    Lewan, Michael D.; Birdwell, Justin E.; Baez, Luis; Beeney, Ken; Sonnenberg, Steve

    2013-01-01

    Understanding changes in petrophysical and geochemical parameters during source rock thermal maturation is a critical component in evaluating source-rock petroleum accumulations. Natural core data are preferred, but obtaining cores that represent the same facies of a source rock at different thermal maturities is seldom possible. An alternative approach is to induce thermal maturity changes by laboratory pyrolysis on aliquots of a source-rock sample of a given facies of interest. Hydrous pyrolysis is an effective way to induce thermal maturity on source-rock cores and provide expelled oils that are similar in composition to natural crude oils. However, net-volume increases during bitumen and oil generation result in expanded cores due to opening of bedding-plane partings. Although meaningful geochemical measurements on expanded, recovered cores are possible, the utility of the core for measuring petrophysical properties relevant to natural subsurface cores is not suitable. This problem created during hydrous pyrolysis is alleviated by using a stainless steel uniaxial confinement clamp on rock cores cut perpendicular to bedding fabric. The clamp prevents expansion just as overburden does during natural petroleum formation in the subsurface. As a result, intact cores can be recovered at various thermal maturities for the measurement of petrophysical properties as well as for geochemical analyses. This approach has been applied to 1.7-inch diameter cores taken perpendicular to the bedding fabric of a 2.3- to 2.4-inch thick slab of Mahogany oil shale from the Eocene Green River Formation. Cores were subjected to hydrous pyrolysis at 360 °C for 72 h, which represents near maximum oil generation. One core was heated unconfined and the other was heated in the uniaxial confinement clamp. The unconfined core developed open tensile fractures parallel to the bedding fabric that result in a 38 % vertical expansion of the core. These open fractures did not occur in the

  7. Microfluidic platform integrated with worm-counting setup for assessing manganese toxicity

    PubMed Central

    Zhang, Beibei; Li, Yinbao; He, Qidi; Qin, Jun; Yu, Yanyan; Li, Xinchun; Zhang, Lin; Yao, Meicun; Liu, Junshan; Chen, Zuanguang

    2014-01-01

    We reported a new microfluidic system integrated with worm responders for evaluating the environmental manganese toxicity. The micro device consists of worm loading units, worm observing chambers, and a radial concentration gradient generator (CGG). Eight T-shape worm loading units of the micro device were used to load the exact number of worms into the corresponding eight chambers with the assistance of worm responders and doorsills. The worm responder, as a key component, was employed for performing automated worm-counting assay through electric impedance sensing. This label-free and non-invasive worm-counting technique was applied to the microsystem for the first time. In addition, the disk-shaped CGG can generate a range of stepwise concentrations of the appointed chemical automatically and simultaneously. Due to the scalable architecture of radial CGG, it has the potential to increase the throughput of the assay. Dopaminergic (DAergic) neurotoxicity of manganese on C. elegans was quantitatively assessed via the observation of green fluorescence protein-tagged DAergic neurons of the strain BZ555 on-chip. In addition, oxidative stress triggered by manganese was evaluated by the quantitative fluorescence intensity of the strain CL2166. By scoring the survival ratio and stroke frequency of worms, we characterized the dose- and time-dependent mobility defects of the manganese-exposed worms. Furthermore, we applied the microsystem to investigate the effect of natural antioxidants to protect manganese-induced toxicity. PMID:25538805

  8. Water oxidation catalysed by manganese compounds: from complexes to 'biomimetic rocks'.

    PubMed

    Wiechen, Mathias; Berends, Hans-Martin; Kurz, Philipp

    2012-01-07

    One of the most fundamental processes of the natural photosynthetic reaction sequence is the light-driven oxidation of water to molecular oxygen. In vivo, this reaction takes place in the large protein ensemble Photosystem II, where a μ-oxido-Mn(4)Ca- cluster, the oxygen-evolving-complex (OEC), has been identified as the catalytic site for the four-electron/four-proton redox reaction of water oxidation. This Perspective presents recent progress for three strategies which have been followed to prepare functional synthetic analogues of the OEC: (1) the synthesis of dinuclear manganese complexes designed to act as water-oxidation catalysts in homogeneous solution, (2) heterogeneous catalysts in the form of clay hybrids of such Mn(2)-complexes and (3) the preparation of manganese oxide particles of different compositions and morphologies. We discuss the key observations from the studies of such synthetic manganese systems in order to shed light upon the catalytic mechanism of natural water oxidation. Additionally, it is shown how research in this field has recently been motivated more and more by the prospect of finding efficient, robust and affordable catalysts for light-driven water oxidation, a key reaction of artificial photosynthesis. As manganese is an abundant and non-toxic element, manganese compounds are very promising candidates for the extraction of reduction equivalents from water. These electrons could consecutively be fed into the synthesis of "solar fuels" such as hydrogen or methanol.

  9. D/H isotope ratios of kerogen, bitumen, oil, and water in hydrous pyrolysis of source rocks containing kerogen types I, II, IIS, and III

    USGS Publications Warehouse

    Schimmelmann, A.; Lewan, M.D.; Wintsch, R.P.

    1999-01-01

    Immature source rock chips containing different types of kerogen (I, II, IIS, III) were artificially matured in isotopically distinct waters by hydrous pyrolysis and by pyrolysis in supercritical water. Converging isotopic trends of inorganic (water) and organic (kerogen, bitumen, oil) hydrogen with increasing time and temperature document that water-derived hydrogen is added to or exchanged with organic hydrogen, or both, during chemical reactions that take place during thermal maturation. Isotopic mass-balance calculations show that, depending on temperature (310-381??C), time (12-144 h), and source rock type, between ca. 45 and 79% of carbon-bound hydrogen in kerogen is derived from water. Estimates for bitumen and oil range slightly lower, with oil-hydrogen being least affected by water-derived hydrogen. Comparative hydrous pyrolyses of immature source rocks at 330??C for 72 h show that hydrogen in kerogen, bitumen, and expelled oil/wax ranks from most to least isotopically influenced by water-derived hydrogen in the order IIS > II ~ III > I. Pyrolysis of source rock containing type II kerogen in supercritical water at 381 ??C for 12 h yields isotopic results that are similar to those from hydrous pyrolysis at 350??C for 72 h, or 330??C for 144 h. Bulk hydrogen in kerogen contains several percent of isotopically labile hydrogen that exchanges fast and reversibly with hydrogen in water vapor at 115??C. The isotopic equilibration of labile hydrogen in kerogen with isotopic standard water vapors significantly reduces the analytical uncertainty of D/H ratios when compared with simple D/H determination of bulk hydrogen in kerogen. If extrapolation of our results from hydrous pyrolysis is permitted to natural thermal maturation at lower temperatures, we suggest that organic D/H ratios of fossil fuels in contact with formation waters are typically altered during chemical reactions, but that D/H ratios of generated hydrocarbons are subsequently little or not affected

  10. Possible roles of manganese redox chemistry in the sulfur cycle

    NASA Technical Reports Server (NTRS)

    Nealson, K. H.

    1985-01-01

    Sulfate reducing bacteria (SRB) are very potent MnO2 reducers by virtue of their sulfide production: H2S reacts rapidly with MnO2 to yield Mn(2), elemental sulfur, and water. In manganese rich zones, Mn cycles rapidly if sulfate is present to drive the reduction and the MnO2 precipitates and sinks into anaerobic zones. The production of sulfide (by organisms requiring organic carbon compounds) to reduce manganese oxides might act to couple the carbon and sulfur cycles in water bodies in which the two cycles are physically separated. Iron has been proposed for this provision of reducing power by (Jorgensen, 1983), but since MnS is soluble and FeS is very insoluble in water, it is equally likely that manganese rather than iron provides the electrons to the more oxidized surface layers.

  11. Corrosion-induced release of the main alloying constituents of manganese-chromium stainless steels in different media.

    PubMed

    Herting, Gunilla; Wallinder, Inger Odnevall; Leygraf, Christofer

    2008-09-01

    The main focus of this paper is the assessment of release rates of chromium, nickel, iron and manganese from manganese-chromium stainless steel grades of low nickel content. The manganese content varied between 9.7 and 1.5 wt% and the corresponding nickel content between 1 and 5 wt%. All grades were exposed to artificial rain and two were immersed in a synthetic body fluid of similar pH but of different composition and exposure conditions. Surface compositional studies were performed using X-ray photoelectron spectroscopy (XPS) in parallel to correlate the metal release process with changes in surface oxide properties. All grades, independent of media, revealed a time-dependent metal release process with a preferential low release of iron and manganese compared to nickel and chromium while the chromium content of the surface oxide increased slightly. Manganese was detected in the surface oxide of all grades, except the grade of the lowest manganese bulk content. No nickel was observed in the outermost surface oxide. Stainless steel grades of the lowest chromium content (approximately 16 wt%) and highest manganese content (approximately 7-9 wt%), released the highest quantity of alloy constituents in total, and vice versa. No correlation was observed between the release rate of manganese and the alloy composition. Released main alloy constituents were neither proportional to the bulk alloy composition nor to the surface oxide composition.

  12. Nanodiamond-Manganese dual mode MRI contrast agents for enhanced liver tumor detection.

    PubMed

    Hou, Weixin; Toh, Tan Boon; Abdullah, Lissa Nurrul; Yvonne, Tay Wei Zheng; Lee, Kuan J; Guenther, Ilonka; Chow, Edward Kai-Hua

    2017-04-01

    Contrast agent-enhanced magnetic resonance (MR) imaging is critical for the diagnosis and monitoring of a number of diseases, including cancer. Certain clinical applications, including the detection of liver tumors, rely on both T1 and T2-weighted images even though contrast agent-enhanced MR imaging is not always reliable. Thus, there is a need for improved dual mode contrast agents with enhanced sensitivity. We report the development of a nanodiamond-manganese dual mode contrast agent that enhanced both T1 and T2-weighted MR imaging. Conjugation of manganese to nanodiamonds resulted in improved longitudinal and transverse relaxivity efficacy over unmodified MnCl 2 as well as clinical contrast agents. Following intravenous administration, nanodiamond-manganese complexes outperformed current clinical contrast agents in an orthotopic liver cancer mouse model while also reducing blood serum concentration of toxic free Mn 2+ ions. Thus, nanodiamond-manganese complexes may serve as more effective dual mode MRI contrast agent, particularly in cancer. Copyright © 2016 Elsevier Inc. All rights reserved.

  13. Compositions containing nucleosides and manganese and their uses

    DOEpatents

    Daly, Michael J.; Gaidamakova, Elena K.; Matrosova, Vera Y.; Levine, Rodney L.; Wehr, Nancy B.

    2015-11-17

    This invention encompasses methods of preserving protein function by contacting a protein with a composition comprising one or more purine or pyrimidine nucleosides (such as e.g., adenosine or uridine) and an antioxidant (such as e.g., manganese). In addition, the invention encompasses methods of treating and/or preventing a side effect of radiation exposure and methods of preventing a side effect of radiotherapy comprising administration of a pharmaceutically effective amount of a composition comprising one or more purine or pyrimidine nucleosides (such as e.g., adenosine or uridine) and an antioxidant (such as e.g., manganese) to a subject in need thereof. The compositions may comprise D. radiodurans extracts.

  14. Manganese-enhanced magnetic resonance imaging (MEMRI).

    PubMed

    Koretsky, Alan P; Silva, Afonso C

    2004-12-01

    Manganese ion (Mn2+) is an essential metal that participates as a cofactor in a number of critical biological functions, such as electron transport, detoxification of free radicals and synthesis of neurotransmitters. Mn2+ can enter excitable cells using some of the same transport systems as Ca2+ and it can bind to a number of intracellular sites because it has high affinity for Ca2+ and Mg2+ binding sites on proteins and nucleic acids. Paramagnetic forms of manganese ions are potent MRI relaxation agents. Indeed, Mn2+ was the first contrast agent proposed for use in MRI. Recently, there has been renewed interest in combining the strong MRI relaxation effects of Mn2+ with its unique biology, in order to further expand the already broad assortment of useful information that can be measured by MRI. Such an approach has been continuously developed in the past several years to provide unique tissue contrast, to assess tissue viability, to act as a surrogate marker of calcium influx into cells and to trace neuronal connections. This special issue of NMR in Biomedicine on manganese-enhanced MRI (MEMRI) is aimed at providing the readers of this journal with an extensive review of some of the most prominent applications of MEMRI in biological systems. Written by several of the leaders in the field, the reviews and original research articles featured in this special issue are likely to offer an exciting and inspiring view of the broad range of applications of MEMRI. Copyright 2004 John Wiley & Sons, Ltd.

  15. Novel MntR-Independent Mechanism of Manganese Homeostasis in Escherichia coli by the Ribosome-Associated Protein HflX

    PubMed Central

    Kaur, Gursharan; Sengupta, Sandeepan; Kumar, Vineet; Kumari, Aruna; Ghosh, Aditi; Parrack, Pradeep

    2014-01-01

    Manganese is a micronutrient required for activities of several important enzymes under conditions of oxidative stress and iron starvation. In Escherichia coli, the manganese homeostasis network primarily constitutes a manganese importer (MntH) and an exporter (MntP), which are regulated by the MntR dual regulator. In this study, we find that deletion of E. coli hflX, which encodes a ribosome-associated GTPase with unknown function, renders extreme manganese sensitivity characterized by arrested cell growth, filamentation, lower rate of replication, and DNA damage. We demonstrate that perturbation by manganese induces unprecedented influx of manganese in ΔhflX cells compared to that in the wild-type E. coli strain. Interestingly, our study indicates that the imbalance in manganese homeostasis in the ΔhflX strain is independent of the MntR regulon. Moreover, the influx of manganese leads to a simultaneous influx of zinc and inhibition of iron import in ΔhflX cells. In order to review a possible link of HflX with the λ phage life cycle, we performed a lysis-lysogeny assay to show that the Mn-perturbed ΔhflX strain reduces the frequency of lysogenization of the phage. This observation raises the possibility that the induced zinc influx in the manganese-perturbed ΔhflX strain stimulates the activity of the zinc-metalloprotease HflB, the key determinant of the lysis-lysogeny switch. Finally, we propose that manganese-mediated autophosphorylation of HflX plays a central role in manganese, zinc, and iron homeostasis in E. coli cells. PMID:24794564

  16. Electrical and magnetic properties of nano-sized magnesium ferrite

    NASA Astrophysics Data System (ADS)

    T, Smitha; X, Sheena; J, Binu P.; Mohammed, E. M.

    2015-02-01

    Nano-sized magnesium ferrite was synthesized using sol-gel techniques. Structural characterization was done using X-ray diffractometer and Fourier Transform Infrared Spectrometer. Vibration Sample Magnetometer was used to record the magnetic measurements. XRD analysis reveals the prepared sample is single phasic without any impurity. Particle size calculation shows the average crystallite size of the sample is 19nm. FTIR analysis confirmed spinel structure of the prepared samples. Magnetic measurement study shows that the sample is ferromagnetic with high degree of isotropy. Hysterisis loop was traced at temperatures 100K and 300K. DC electrical resistivity measurements show semiconducting nature of the sample.

  17. Release of sulfur- and oxygen-bound components from a sulfur-rich kerogen during simulated maturation by hydrous pyrolysis

    USGS Publications Warehouse

    Putschew, A.; Schaeffer-Reiss, C.; Schaeffer, P.; Koopmans, M.P.; De Leeuw, J. W.; Lewan, M.D.; Sinninghe, Damste J.S.; Maxwell, J.R.

    1998-01-01

    An immature sulfur-rich marl from the Gessosso-solfifera Formation of the Vena del Gesso Basin (Messinian, Italy) has been subjected to hydrous pyrolysis (160 to 330??C) to simulate maturation under natural conditions. The kerogen of the unheated and heated samples was isolated and the hydrocarbons released by selective chemical degradation (Li/EtNH2 and HI/LiAIH4) were analysed to allow a study of the fate of sulfur- and oxygen-bound species with increasing temperature. The residues from the chemical treatments were also subjected to pyrolysis-GC to follow structural changes in the kerogens. In general, with increasing hydrous pyrolysis temperature, the amounts of sulfide- and ether-bound components in the kerogen decreased significantly. At the temperature at which the generation of expelled oil began (260??C), almost all of the bound components initially present in the unheated sample were released from the kerogen. Comparison with an earlier study of the extractable organic matter using a similar approach and the same samples provides molecular evidence that, with increasing maturation, solvent-soluble macromolecular material was initially released from the kerogen, notably as a result of thermal cleavage of weak Carbon-heteroatom bonds (sulfide, ester, ether) even at temperatures as low as 220??C. This solvent-soluble macromolecular material then underwent thermal cleavage to generate hydrocarbons at higher temperatures. This early generation of bitumen may explain the presence of unusually high amounts of extractable organic matter of macromolecular nature in very immature S-rich sediments.

  18. Radio-manganese, -iron, -phosphorus uptake by water hyacinth and economic implications

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Colley, T.N.; Gonzalez, M.H.; Martin, D.F.

    To determine the effects of the deprivation of specific micronutrients on the water hyacinth (Eichhornia crassipes), the rate of uptake by the water hyacinth of iron and manganese in comparison with phosphorus was studied. Materials and methodology are described. Experimentation indicates that all three elements are actively absorbed by the root systems, but the rates of absorption differ markedly. The rate of absorption of manganese by roots is 13 and 21 times that for radio-iron and -phosphorous, and iron was taken up by the roots at nearly twice the rate of phosphorous. Manganese translocation appeared to be faster than phosphorusmore » translocation by an order of magnitude and 65 times faster than iron translocation. 9 references, 2 tables.« less

  19. Hot Ductility Behavior of Boron Containing Microalloyed Steels with Varying Manganese Contents

    NASA Astrophysics Data System (ADS)

    Brune, Tobias; Senk, Dieter; Walpot, Raphael; Steenken, Bernhard

    2015-02-01

    The hot ductility is measured for six different steel grades with different microalloying elements and with varying manganese contents using the hot tensile test machine with melting/solidification unit at the Department of Ferrous Metallurgy RWTH Aachen University. To identify the influence of manganese on hot ductility, tests are performed with varying the manganese content from 0.7 to 18.2 wt pct, a high manganese steel. Additionally, the effect of different cooling and strain rates is analyzed by changing the particular rate for selected samples in the minima. To investigate and detect the cause of cracking during testing, the fracture surfaces in the ductility minima are considered with scanning electron microscope-energy dispersive X-ray spectroscopy. Thermodynamic modeling is conducted on basis of the commercial software ThermoCalc©. A sharp decrease of the hot ductility is recognizable at 1398 K (1125 °C), at only 0.7 wt pct manganese because of the low manganese to sulfur ratio. The grades with a Mn content up to 1.9 wt pct show a good ductility with minimal ductility loss. In comparison, the steel grade with 18.2 wt pct has a poor hot ductility. Because of the formation of complex precipitates, where several alloying elements are involved, the influence of boron on hot ductility is not fully clarified. By increasing the cooling rate, the reduction of area values are shifted to smaller values. For high test temperatures, these measured values are decreased for lower strain rates. Thereby, an early drop of the ductility is noticeable for the high temperatures around 1373 K (1100 °C).

  20. Nano-sized metabolic precursors for heterogeneous tumor-targeting strategy using bioorthogonal click chemistry in vivo.

    PubMed

    Lee, Sangmin; Jung, Seulhee; Koo, Heebeom; Na, Jin Hee; Yoon, Hong Yeol; Shim, Man Kyu; Park, Jooho; Kim, Jong-Ho; Lee, Seulki; Pomper, Martin G; Kwon, Ick Chan; Ahn, Cheol-Hee; Kim, Kwangmeyung

    2017-12-01

    Herein, we developed nano-sized metabolic precursors (Nano-MPs) for new tumor-targeting strategy to overcome the intrinsic limitations of biological ligands such as the limited number of biological receptors and the heterogeneity in tumor tissues. We conjugated the azide group-containing metabolic precursors, triacetylated N-azidoacetyl-d-mannosamine to generation 4 poly(amidoamine) dendrimer backbone. The nano-sized dendrimer of Nano-MPs could generate azide groups on the surface of tumor cells homogeneously regardless of cell types via metabolic glycoengineering. Importantly, these exogenously generated 'artificial chemical receptors' containing azide groups could be used for bioorthogonal click chemistry, regardless of phenotypes of different tumor cells. Furthermore, in tumor-bearing mice models, Nano-MPs could be mainly localized at the target tumor tissues by the enhanced permeation and retention (EPR) effect, and they successfully generated azide groups on tumor cells in vivo after an intravenous injection. Finally, we showed that these azide groups on tumor tissues could be used as 'artificial chemical receptors' that were conjugated to bioorthogonal chemical group-containing liposomes via in vivo click chemistry in heterogeneous tumor-bearing mice. Therefore, overall results demonstrated that our nano-sized metabolic precursors could be extensively applied to new alternative tumor-targeting technique for molecular imaging and drug delivery system, regardless of the phenotype of heterogeneous tumor cells. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. Relative association of Rubisco with manganese and magnesium as a regulatory mechanism in plants.

    PubMed

    Bloom, Arnold J; Kameritsch, Petra

    2017-12-01

    Rubisco, the enzyme that constitutes as much as half of the protein in a leaf, initiates either the photorespiratory pathway that supplies reductant for the assimilation of nitrate into amino acids or the C3 carbon fixation pathway that generates carbohydrates. The relative rates of these two pathways depend both on the relative extent to which O 2 and CO 2 occupies the active site of Rubisco and on whether manganese or magnesium is bound to the enzyme. This study quantified the activities of manganese and magnesium in isolated tobacco chloroplasts and the thermodynamics of binding of these metals to Rubisco purified from tobacco or a bacterium. In tobacco chloroplasts, manganese was less active than magnesium, but Rubisco purified from tobacco had a higher affinity for manganese. The activity of each metal in the chloroplast was similar in magnitude to the affinity of tobacco Rubisco for each. This indicates that, in tobacco chloroplasts, Rubisco associates almost equally with both metals and rapidly exchanges one metal for the other. Binding of magnesium was similar in Rubisco from tobacco and a bacterium, whereas binding of manganese differed greatly between the Rubisco from these species. Moreover, the ratio of leaf manganese to magnesium in C3 plants increased as atmospheric CO 2 increased. These results suggest that Rubisco has evolved to improve the energy transfers between photorespiration and nitrate assimilation and that plants regulate manganese and magnesium activities in the chloroplast to mitigate detrimental changes in their nitrogen/carbon balance as atmospheric CO 2 varies. © 2017 Scandinavian Plant Physiology Society.

  2. Manganese and welding fume exposure and control in construction.

    PubMed

    Meeker, John D; Susi, Pam; Flynn, Michael R

    2007-12-01

    Overexposure to welding fume constituents, particularly manganese, is of concern in the construction industry due to the prevalence of welding and the scarcity of engineering controls. The control effectiveness of a commercially available portable local exhaust ventilation (LEV) unit was assessed. It consisted of a portable vacuum and a small bell-shaped hood connected by a flexible 2 inch (50.8 mm) diameter hose, in both experimental and field settings. The experimental testing was done in a semienclosed booth at a pipefitter training facility. Five paired trials of LEV control vs. no control, each approximately 1 hr in duration and conducted during two successive welds of 6 inch (152.4 mm) diameter carbon steel pipe were run in random order. Breathing zone samples were collected outside the welding hood during each trial. In the field scenario, full-shift breathing zone samples were collected from two pipefitters welding carbon steel pipe for a chiller installation on a commercial construction project. Eight days of full-shift sampling were conducted on both workers (n = 16), and the LEV was used by one of the two workers on an alternating basis for 7 of the days. All samples were collected with personal sample pumps calibrated at 2 L/min. Filter cassettes were analyzed for total particulate and manganese concentration by a certified laboratory. In the experimental setting, use of the portable LEV resulted in a 75% reduction in manganese exposure (mean 13 microg/m(3) vs. 51 microg/m(3); p < 0.05) and a 60% reduction in total particulate (mean 0.74 mg/m(3) vs. 1.83 mg/m(3); p < 0.05). In the field setting, LEV use resulted in a 53% reduction in manganese exposure (geometric mean 46 microg/m(3) vs. 97 microg/m(3); p < 0.05) but only a 10% reduction in total particulate (geometric mean 4.5 mg/m(3) vs. 5.0 mg/m(3); p > 0.05). These results demonstrate that LEV use can reduce manganese exposure associated with welding tasks in construction.

  3. Longitudinal and contemporaneous manganese exposure in apartheid-era South Africa: Implications for the past and future.

    PubMed

    Hess, Catherine A; Smith, Martin J; Trueman, Clive; Schutkowski, Holger

    2015-03-01

    Manganese is a potent environmental toxin, with significant effects on human health. Manganese exposure is of particular concern in South Africa where in the last decade, lead in gasoline has been replaced by methylcyclopentadienyl manganese tricarbonyl (MMT). We investigated recent historical levels of manganese exposure in urban Gauteng, South Africa prior to the introduction of MMT in order to generate heretofore non-existent longitudinal public health data on manganese exposure in urban South Africans. Cortical bone manganese concentration was measured by inductively coupled plasma mass spectrometer in 211 deceased adults with skeletal material from a fully identified archived tissue collection at the University of Pretoria, South Africa. All tissues came from individuals who lived and died in urban Gauteng (Transvaal), between 1958 and 1998. Median Mn concentration within the sampled tissues was 0.3μgg -1 , which is within reported range for bone manganese concentration in non-occupationally exposed populations and significantly below that reported in individuals environmentally exposed to MMT. No significant differences were seen in bone Mn between men and women or in individuals of different ethnicity, which further suggests environmental, as opposed to occupational exposure. There were no significant temporal or geographic differences in bone Mn. The results suggest that Mn exposure was low and uniformly distributed across the whole population prior to the introduction of MMT as a gasoline additive. In addition, should manganese exposure follow the same patterns as vehicle-emitted lead, a clear pattern of exposure will emerge with individuals in the urban core facing the greatest manganese exposure. Copyright © 2014 Elsevier Inc. All rights reserved.

  4. Manganese toxicity and Saccharomyces cerevisiae Mam3p, a member of the ACDP (ancient conserved domain protein) family

    PubMed Central

    2004-01-01

    Manganese is an essential, but potentially toxic, trace metal in biological systems. Overexposure to manganese is known to cause neurological deficits in humans, but the pathways that lead to manganese toxicity are largely unknown. We have employed the bakers' yeast Saccharomyces cerevisiae as a model system to identify genes that contribute to manganese-related damage. In a genetic screen for yeast manganese-resistance mutants, we identified S. cerevisiae MAM3 as a gene which, when deleted, would increase cellular tolerance to toxic levels of manganese and also increased the cell's resistance towards cobalt and zinc. By sequence analysis, Mam3p shares strong similarity with the mammalian ACDP (ancient conserved domain protein) family of polypeptides. Mutations in human ACDP1 have been associated with urofacial (Ochoa) syndrome. However, the functions of eukaryotic ACDPs remain unknown. We show here that S. cerevisiae MAM3 encodes an integral membrane protein of the yeast vacuole whose expression levels directly correlate with the degree of manganese toxicity. Surprisingly, Mam3p contributes to manganese toxicity without any obvious changes in vacuolar accumulation of metals. Furthermore, through genetic epistasis studies, we demonstrate that MAM3 operates independently of the well-established manganese-trafficking pathways in yeast, involving the manganese transporters Pmr1p, Smf2p and Pho84p. This is the first report of a eukaryotic ACDP family protein involved in metal homoeostasis. PMID:15498024

  5. Low potential manganese ions as efficient electron donors in native anoxygenic bacteria.

    PubMed

    Deshmukh, Sasmit S; Protheroe, Charles; Ivanescu, Matei-Alexandru; Lag, Sarah; Kálmán, László

    2018-04-01

    Systematic control over molecular driving forces is essential for understanding the natural electron transfer processes as well as for improving the efficiency of the artificial mimics of energy converting enzymes. Oxygen producing photosynthesis uniquely employs manganese ions as rapid electron donors. Introducing this attribute to anoxygenic photosynthesis may identify evolutionary intermediates and provide insights to the energetics of biological water oxidation. This work presents effective environmental methods that substantially and simultaneously tune the redox potentials of manganese ions and the cofactors of a photosynthetic enzyme from native anoxygenic bacteria without the necessity of genetic modification or synthesis. A spontaneous coordination with bis-tris propane lowered the redox potential of the manganese (II) to manganese (III) transition to an unusually low value (~400 mV) at pH 9.4 and allowed its binding to the bacterial reaction center. Binding to a novel buried binding site elevated the redox potential of the primary electron donor, a dimer of bacteriochlorophylls, by up to 92 mV also at pH 9.4 and facilitated the electron transfer that is able to compete with the wasteful charge recombination. These events impaired the function of the natural electron donor and made BTP-coordinated manganese a viable model for an evolutionary alternative. Copyright © 2018 Elsevier B.V. All rights reserved.

  6. A manganese-rich environment supports superoxide dismutase activity in a Lyme disease pathogen, Borrelia burgdorferi.

    PubMed

    Aguirre, J Dafhne; Clark, Hillary M; McIlvin, Matthew; Vazquez, Christine; Palmere, Shaina L; Grab, Dennis J; Seshu, J; Hart, P John; Saito, Mak; Culotta, Valeria C

    2013-03-22

    The Lyme disease pathogen Borrelia burgdorferi represents a novel organism in which to study metalloprotein biology in that this spirochete has uniquely evolved with no requirement for iron. Not only is iron low, but we show here that B. burgdorferi has the capacity to accumulate remarkably high levels of manganese. This high manganese is necessary to activate the SodA superoxide dismutase (SOD) essential for virulence. Using a metalloproteomic approach, we demonstrate that a bulk of B. burgdorferi SodA directly associates with manganese, and a smaller pool of inactive enzyme accumulates as apoprotein. Other metalloproteins may have similarly adapted to using manganese as co-factor, including the BB0366 aminopeptidase. Whereas B. burgdorferi SodA has evolved in a manganese-rich, iron-poor environment, the opposite is true for Mn-SODs of organisms such as Escherichia coli and bakers' yeast. These Mn-SODs still capture manganese in an iron-rich cell, and we tested whether the same is true for Borrelia SodA. When expressed in the iron-rich mitochondria of Saccharomyces cerevisiae, B. burgdorferi SodA was inactive. Activity was only possible when cells accumulated extremely high levels of manganese that exceeded cellular iron. Moreover, there was no evidence for iron inactivation of the SOD. B. burgdorferi SodA shows strong overall homology with other members of the Mn-SOD family, but computer-assisted modeling revealed some unusual features of the hydrogen bonding network near the enzyme's active site. The unique properties of B. burgdorferi SodA may represent adaptation to expression in the manganese-rich and iron-poor environment of the spirochete.

  7. Pilot scale application of nanosized iron oxides as electron acceptors for bioremediation

    NASA Astrophysics Data System (ADS)

    Bosch, Julian; Fritzsche, Andreas; Frank-Fahle, Beatrice; Lüders, Tilmann; Höss, Sebastian; Eisenmann, Heinrich; Held, Thomas; Totsche, Kai U.; Meckenstock, Rainer U.

    2014-05-01

    Microbial reduction of ferric iron is a major biogeochemical process in groundwater aquifer ecosystems and often associated with the degradation of organic contaminants, as bacteria couple iron reduction to the oxidation reduced carbon like e.g. BTEX. Yet in general the low bioavailability of natural iron oxides limits microbial reduction rates. However, nanosized iron oxides have an unequally enhanced bioavailability and reactivity compared to their respective bulk, macro-sized, and more crystalline materials. At the same time, nanosized iron oxides can be produced in stable colloidal suspensions, permitting efficient injections into contaminated aquifers. We examined the reactivity of nanosized synthetic colloidal iron oxides in microbial iron reduction. Application of colloidal nanoparticles led to a strong and sustainable enhancement of microbial reaction rates in batch experiments and sediment columns. Toluene oxidation was increased five-fold as compared to bulk, non-colloidal ferrihydrite as electron acceptor. Furthermore, we developed a unique approach for custom-tailoring the subsurface mobility of these particles after being injected into a contaminant plume. In a field pilot application, we injected 18 m3 of an iron oxide nanoparticle solution into a BTEX contaminated aquifer with a maximum excess pressure as low as 0.2 bar. The applied suspension showed a superior subsurface mobility, creating a reactive zone of 4 m height (corresponding to the height of the confined aquifer) and 6 m in diameter. Subsequent monitoring of BTEX, microbial BTEX degradation metabolites, ferrous iron generation, stable isotopes fractionation, microbial populations, and methanogenesis demonstrated the strong impact of our approach. Mathematic processed X-ray diffractograms and FTIR spectra provided a semi-quantitatively estimate of the long-term fate of the iron oxide colloids in the aquifer. Potential environmental risks of the injection itself were monitored with

  8. Uniform manganese hexacyanoferrate hydrate nanocubes featuring superior performance for low-cost supercapacitors and nonenzymatic electrochemical sensors.

    PubMed

    Pang, Huan; Zhang, Yizhou; Cheng, Tao; Lai, Wen-Yong; Huang, Wei

    2015-10-14

    Uniform manganese hexacyanoferrate hydrate nanocubes are prepared via a simple chemical precipitation method at room temperature. Due to both micro/mesopores of the Prussian blue analogue and nanocubic structures, the manganese hexacyanoferrate hydrate nanocubes allow the efficient charge transfer and mass transport for electrolyte solution and chemical species. Thus, the manganese hexacyanoferrate hydrate nanocube electrode shows a good rate capability and cycling stability for electrochemical capacitors. Furthermore, electrodes modified with manganese hexacyanoferrate hydrate nanocubes demonstrate a sensitive electrochemical response to hydrogen peroxide (H2O2) in buffer solutions with a high selectivity.

  9. Hydrogen concentration in plagioclaes as a hygrometer of magmas: Approaches from melt inclusion analyses and hydrous melting experiments

    NASA Astrophysics Data System (ADS)

    Hamada, M.; Ushioda, M.; Fujii, T.; Takahashi, E.

    2012-12-01

    Plagioclase is one of the nominally anhydrous minerals (NAMs) which accommodates hundreds wt. ppm of hydrogen. Hydrogen in igneous plagioclase (OH) can act as a proxy of dissolved H2O in silicate melt. In order to use it as a practical hygrometer of magmas, we studied partitioning of hydrogen between plagioclase and basaltic melt dis-solving H2O (0.3˜5.5 wt.%) by two approaches: analyses of plagioclase-hosted melt inclusions (H2O≈0.3 wt.%) from mid-ocean ridge basalt (MORB) and hydrogen partitioning experiments between An96 plagioclase and hydrous basaltic melt (0.8 wt.%≦H2O≦5.5 wt.%) at 0.35 GPa. Concentration hydrogen in plagioclase and concentration of H2O in basaltic glasses were analyzed by infrared spectroscopy. As a first series of this study, plagioclase-hosted melt inclusions in MORB (50.5% SiO2, 15.1% Al2O3, 7.4% MgO) from the Rodriguez triple junction in the Indian Ocean were analyzed. The hydrogen concentration of plagioclase is less than 50 wt. ppm water, and no correlation between hydrogen concentration and anorthite content is recognized. Average H2O concentrations in melt inclusions is 0.3 wt.%. Therefore, apparent partition coefficient of hydrogen between plagioclase and melt is ≈ 0.01 in molar basis. As a second series of this study, hydrous melting experiments of arc basaltic magma were performed at 350 MPa using internally-heated pressure vessel. Starting material was hydrous glass (0.8 wt.%≦H2O≦5.5 wt.%) of an undifferentiated rock from Miyakejima volcano, a frontal-arc volcano in Izu-arc (MTL rock: 50.5% SiO2, 18.1% Al2O3, 4.9% MgO). A grain of Ca-rich plagioclase (≈1 mg, about An96) and 10 mg of powdered glasses were sealed in Au80Pd20 alloy capsule, and then kept at temperature at around the liquidus. Liquidus phase of MTL rock at 350 MPa is always plagioclase with 0 to 5.5 wt.% H2O in melt, and therefore, a grain of plagioclase and hydrous melt were nearly in equilibrium. Oxygen fugacity (fO2) during the melting experiments

  10. Dynamics of manganese, cadmium, and lead in experimental power plant ponds

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Mathis, B.J.; Cummings, T.F.; Gower, M.

    1977-06-01

    This study was designed to determine the effect of heated power plant cooling water on the compartmentalization of manganese, lead, and cadmium in experimental ponds. Caged channel catfish and green sunfish were kept in an experimental pond and a control pond. Periodically, whole fishes, gill, heart, kidney, liver, and musculature were analyzed for the three metals. Concentrations of the three metals in fishes were not affected by the temperature differential maintained during the study. There was no correlation in concentrations of cadmium and lead with age (weight and length) of fishes but manganese concentrations declined slightly with age. Aquatic organismsmore » such as snails, fingernail clams, leeches, tubificid annelids, and dragonfly nymphs exhibited concentrations of cadmium higher than sediments while snails and duckweed more closely reflected concentrations of manganese in sediments.« less

  11. Analysis of the world distribution of metal-rich subsea manganese nodules

    USGS Publications Warehouse

    McKelvey, Vincent Ellis; Wright, Nancy A.; Bowen, Roger W.

    1983-01-01

    Publicly available data on the composition of subsea manganese nodules extend previous reports of differences in average metal contents from ocean to ocean and of variations related to latitude and depth. Pacific Ocean nodules have the highest average manganese, nickel, and copper contents, and Atlantic Ocean nodules have the highest average iron content. The average manganese, nickel, and copper contents generally increase toward the equator in both hemispheres, and iron content generally decreases. The variation of metal content with water depth is not linear; instead, there appears to be a threshold depth of about 2,900 to 3,000 m, above which combined nickel and copper contents are generally less than 1 percent and below which cobalt content is generally less than about 0.6 percent. The composition of the nodules varies widely, but three rarely overlapping types that are of possible economic interest can be recognized. (1) Nodules containing more than about 1 percent combined nickel and copper only exceptionally contain more than 0.5 percent cobalt and 35 percent manganese. (2) Nodules containing more than 0.5 percent cobalt rarely contain more than 1 percent combined nickel and copper and 35 percent manganese. (3) Nodules containing more than 35 percent manganese only exceptionally contain more than 0.5 percent cobalt, although they average nearly 1.1 percent combined nickel and copper. Current economic interest in nodule mining is focused on the Clarion-Clipperton zone in the northeastern equatorial Pacific Ocean, the largest known area in which nodules average 1.8 percent or more combined nickel and copper. Several other areas in which nodules are rich in these metals are found in the Pacific and Indian Oceans and may be viewed as targets for exploration. Nearly 60 chemical elements have been found in manganese nodules, many in concentrations far exceeding their crustal abundances. The amounts in which many minor elements are present vary with the amounts of

  12. MntABC and MntH Contribute to Systemic Staphylococcus aureus Infection by Competing with Calprotectin for Nutrient Manganese

    PubMed Central

    Kehl-Fie, Thomas E.; Zhang, Yaofang; Moore, Jessica L.; Farrand, Allison J.; Hood, M. Indriati; Rathi, Subodh; Chazin, Walter J.; Caprioli, Richard M.

    2013-01-01

    During infection, vertebrates limit access to manganese and zinc, starving invading pathogens, such as Staphylococcus aureus, of these essential metals in a process termed “nutritional immunity.” The manganese and zinc binding protein calprotectin is a key component of the nutrient-withholding response, and mice lacking this protein do not sequester manganese from S. aureus liver abscesses. One potential mechanism utilized by S. aureus to minimize host-imposed manganese and zinc starvation is the expression of the metal transporters MntABC and MntH. We performed transcriptional analyses of both mntA and mntH, which revealed increased expression of both systems in response to calprotectin treatment. MntABC and MntH compete with calprotectin for manganese, which enables S. aureus growth and retention of manganese-dependent superoxide dismutase activity. Loss of MntABC and MntH results in reduced staphylococcal burdens in the livers of wild-type but not calprotectin-deficient mice, suggesting that these systems promote manganese acquisition during infection. During the course of these studies, we observed that metal content and the importance of calprotectin varies between murine organs, and infection leads to profound changes in the anatomical distribution of manganese and zinc. In total, these studies provide insight into the mechanisms utilized by bacteria to evade host-imposed nutrient metal starvation and the critical importance of restricting manganese availability during infection. PMID:23817615

  13. High-rate lithium/manganese dioxide batteries; the double cell concept

    NASA Astrophysics Data System (ADS)

    Drews, Jürgen; Wolf, Rüdiger; Fehrmann, Gerd; Staub, Roland

    An implantable defibrillator battery has to provide pulse-power capabilities as well as high energy density. Low self-discharge rates are mandatory and an ability to check the state of charge is required. To accomplish these requirements, a lithium/manganese dioxide battery with a modified active cathode mass has been developed. Usage of a double cell design increases significantly the battery performance within an implantable defibrillator. The design features of a high-rate, pulse-power, manganese dioxide double cell are described.

  14. Effect of iron content on the creep behavior of Olivine: 2. Hydrous conditions

    NASA Astrophysics Data System (ADS)

    Zhao, Yong-Hong; Zimmerman, Mark E.; Kohlstedt, David L.

    2018-05-01

    We have undertaken an experimental investigation of the effect of iron content on the viscosity of Fe-Mg olivine aggregates deformed under hydrous conditions in order to provide a basis for comparing convection models for the mantle of Earth with those for the more iron-rich mantle of Mars. Fine-grained samples of Fe-bearing olivine with fayalite contents, Fax, of x = 100, 75, 50, 30 and 10 were deformed in triaxial compressive creep primarily in the dislocation creep regime under water-saturated conditions at temperatures of 1273 to 1473 K and a confining pressure of 300 MPa. Nickel sleeves around the samples of Fa10, Fa30 and Fa50 set the oxygen fugacity at the Ni:NiO buffer and thus the water fugacity at ≲300 MPa, while Fe sleeves around samples of Fa75 and Fa100 set the oxygen fugacity at the Fe:FeO buffer and thus the water fugacity at ≲200 MPa. Samples were deformed in triaxial compression to a maximum strain of 0.2 at differential stresses from 10 to 300 MPa and strain rates from 10-7 to 10-3 s-1. In the dislocation creep field at a given temperature, the viscosity of samples of Fa50 is a factor of ∼10 smaller than the viscosity of samples of Fa30, while the viscosity of samples of Fa30 is a factor of ∼10 smaller than that of samples of Fa10. Our experimental results can be described by the flow law ε˙disl =Cdisl(σ/μ) ndisl XFa pdisl exp(-(Qdisl0 +αdislXFa)/RT) fH2Omdisl with Cdisl = 99.7 MPa-5/4 s-1, ndisl = 3.7, pdisl = 0.5, Qdisl0 = 510 kJ/mol, αdisl = -120 kJ/mol, and mdisl = 5/4. This flow law indicates that the viscosity of olivine of a specific Fe:Mg ratio is a factor of ∼10 smaller than its counterpart deformed under anhydrous conditions. In a hydrous environment at the same thermodynamic conditions, the viscosity of the more Fe-rich mantle (∼Fa19) of Mars is a factor of ∼5 lower than that of the mantle (∼Fa8) of Earth.

  15. Structural and surface changes of cobalt modified manganese oxide during activation and ethanol steam reforming reaction

    NASA Astrophysics Data System (ADS)

    Gac, Wojciech; Greluk, Magdalena; Słowik, Grzegorz; Turczyniak-Surdacka, Sylwia

    2018-05-01

    Surface and structural changes of unmodified manganese and cobalt-manganese oxide during activation and ethanol steam reforming reaction conditions (ESR) were studied by means of X-ray diffraction, X-ray photoelectron spectroscopy, temperature-programmed reduction/oxidation (TPR/TPO) and transmission electron microscopy. It was shown that synthesis of cobalt manganese oxide by the redox precipitation method led to the formation of strongly dispersed cobalt ionic species within cryptomelane-based manganese oxide structure. Development of large cube-like MnO nanoparticles with spherical cobalt metallic crystallites decorated by manganese oxide on the high oxidation state and potassium species was observed during reduction. Cobalt manganese catalyst showed high initial activity and selectivity to H2 and CO2 in ethanol stem reforming reaction in the range of 390-480 °C. The drop of ethanol conversion and changes of selectivity with the time-on-stream were observed. An increase of reaction temperature led to intensification of deactivation phenomena. TEM studies evidenced coexistence of Co and CoOx nanoparticles formed under ethanol steam reforming conditions, partially covered by filamentous and encapsulating carbonaceous deposits.

  16. Hybrid ternary rice paper-manganese oxide-carbon nanotube nanocomposites for flexible supercapacitors.

    PubMed

    Jiang, Wenchao; Zhang, Kaixi; Wei, Li; Yu, Dingshan; Wei, Jun; Chen, Yuan

    2013-11-21

    Modern portable electronic devices create a strong demand for flexible energy storage devices. Paper based nanocomposites are attractive as sustainable materials for such applications. Here, we directly explored the hydroxyl chemistry of cellulose fibers to synthesize hybrid ternary nanocomposites, comprised of rice paper, single-walled carbon nanotubes (SWCNTs) and manganese oxide nanoparticles. The functional groups on cellulose fibers can react with adsorbed permanganate ions, resulting in uniform deposition of manganese oxide nanoparticles. SWCNTs coated on top of manganese oxide nanoparticles form a highly conductive network connecting individual manganese oxide particles. By using the hybrid ternary composites as electrodes, the assembled two-electrode supercapacitors demonstrated high capacitance (260.2 F g(-1)), energy (9.0 W h kg(-1)), power (59.7 kW kg(-1)), and cycle stability (12% drop after 3000 cycles). In addition, the nanocomposites show good strength and excellent mechanical flexibility, and their capacitance shows negligible changes after bending more than 100 times. These findings suggest that opportunities exist to further explore the rich chemistry of cellulose fibers for innovative energy applications.

  17. Highly Conductive One-Dimensional Manganese Oxide Wires by Coating with Graphene Oxides

    NASA Astrophysics Data System (ADS)

    Tojo, Tomohiro; Shinohara, Masaki; Fujisawa, Kazunori; Muramatsu, Hiroyuki; Hayashi, Takuya; Ahm Kim, Yoong; Endo, Morinobu

    2012-10-01

    Through coating with graphene oxides, we have developed a chemical route to the bulk production of long, thin manganese oxide (MnO2) nanowires that have high electrical conductivity. The average diameter of these hybrid nanowires is about 25 nm, and their average length is about 800 nm. The high electrical conductivity of these nanowires (ca. 189.51+/-4.51 µS) is ascribed to the homogeneous coating with conductive graphene oxides as well as the presence of non-bonding manganese atoms. The growth mechanism of the nanowires is theoretically supported by the initiation of morphological conversion from graphene oxide to wrapped structures through the formation of covalent bonds between manganese and oxygen atoms at the graphene oxide edge.

  18. Batch study of manganese removal from mine effluent using mixture of ferromanganese ore and humus

    NASA Astrophysics Data System (ADS)

    Kamal, Norinsafrina Mustaffa; Aziz, Hamidi Abdul; Sulaiman, Shamsul Kamal; Hussin, Hashim

    2017-10-01

    Environmental problem related to mining industry always associates with high heavy metal contents in mine effluent. Manganese is among the metals that need to be reduced before the mine effluent entering receiving waterways. In this batch study, mixture of ferromanganese ore and humus had been applied to remove manganese from mine effluent. Effect of particle size of ferromanganese ore, dosage, mix ratio, pH and contact time had been studied to examine the effectiveness of the mixture in removing manganese. Results from the study have shown that optimum manganese removal was 93.54% by using particle size of 0.25-0.5 mm of ferromanganese ore, 3g of dosage mixture, mix ratio of 20%;80%, solution pH of 7 and 210 minutes (3.5 hours) of contact time. Thus, it is proven that mixture of ferromanganese ore and humus has potential to be used for removal of manganese in mine effluent.

  19. Sulfur speciation in hydrous experimental glasses of varying oxidation state - Results from measured wavelength shifts of sulfur X-rays

    NASA Technical Reports Server (NTRS)

    Carroll, Michael R.; Rutherford, Malcolm J.

    1988-01-01

    The focusing geometry of an electron microprobe has been used to measure the wavelength shifts of sulfur X-rays from hydrous experimental melts synthesized at oxygen fugacities that range from near the iron-wustite buffer to the magnetite-hermatite buffer. It is found that the proportion of dissolved sulfur which is present as sulfate increases with increasing oxygen fugacity. It is noted that in natural melts that have equilibrated at or below fayalite-magnetite-quartz values of +1, sulfur is probably present mainly as S(2-).

  20. Determination of urinary manganese by the direct chelation-extraction method and flameless atomic absorption spectrophotometry.

    PubMed Central

    Watanabe, T; Tokunaga, R; Iwahana, T; Tati, M; Ikeda, M

    1978-01-01

    The direct chelation-extraction method, originally developed by Hessel (1968) for blood lead analysis, has been successfully applied to urinalysis for manganese. The analyses of 35 urine samples containing up to 100 microgram/1 of manganese from manganese-exposed workers showed that the data obtained by this method agree well with those by wet digestion-flame atomic absorption spectrophotometry and also by flameless atomic absorption spectrophotometry. PMID:629893

  1. Transport and thermodynamic properties of hydrous melts in the system An-Di.

    NASA Astrophysics Data System (ADS)

    Giordano, D.; Potuzak, M.; Romano, C.; Russell, J. K.; Nowak, M.; Dingwell, D. B.

    2006-12-01

    The thermodynamic and transport properties hydrous silicate melts are of fundamental importance for characterization of the dynamics and energetics associated with silicate melts in the Earth. The literature concerning the transport and calorimetric properties of hydrous silicate melts remains scarce. With few exceptions little has been effectively done in order to provide chemical models that bridge the gap between the description of both complex and simple systems. The An-Di system is of general interest to geochemists as well as petrologists because it serves as a simple analogue for basaltic compositions. It was chosen here due to the combination of its simple chemical description and the presence of an extensive database of published experimental data on both its transport and thermodynamic properties. We have measured the viscosity (η)), the glass transition temperatures (Tg) and the heat capacity (Cp) of silicate melts in the An-Di system containing up to 3 wt.% of dissolved H2O. Viscosity data were obtained by using the dilatometric method of micropenetration, whereas a differential scanning calorimeter (DSC) was employed to determine the glass transition temperatures and the heat capacities. In order to characterize the well-known cooling/heating rate dependence of the glass transition temperatures the calorimetric measurements were performed at heating/cooling rate of 5, 10, 15 and 20 K/min. These results together with those of previous experimental studies have been used to provide a compositional model capable of calculating the Newtonian viscosity of melts as well as the Tg and Cp values for the An- Di+H2O system. The non-Arrhenian T-dependence of viscosity is accounted for by the Vogel-Fulcher- Tammann (VFT) and the Adam Gibbs (AG) equations. Our optimizations assume a common, high-T limit (A) for silicate melt viscosity, consistent with values provided by both theoretical and experimental studies. In particular, we also show that glass transition

  2. Furfural and 5-hydroxymethyl-furfural degradation using recombinant manganese peroxidase.

    PubMed

    Yee, Kelsey L; Jansen, Lauren E; Lajoie, Curtis A; Penner, Michael H; Morse, Lettie; Kelly, Christine J

    2018-01-01

    Biomass pretreatment-derived degradation compounds, such as furfural and 5-hydroxymethyl-furfural (HMF), inhibit the growth of fermentation microorganisms that utilize biomass to produce fuels and chemicals. Here we report that recombinant manganese peroxidase (rMnP) produced from the yeast Pichia pastoris can degrade furfural and HMF making them less toxic to microorganisms. Treatment with rMnP or manganese(III) acetate reduced furfural and HMF concentrations in a dose-dependent manner. Furfural disappearance was accompanied by malonate disappearance and accumulation of four distinct degradation products. Furfural was more readily degraded by rMnP and manganese(III) acetate than HMF. Growth assays using Saccharomyces cerevisiae indicated that rMnP treatment reduced the toxicity of furfural and HMF. This work provides an avenue to use rMnP to increase the growth of fermentation microorganisms that are inhibited by toxic compounds derived from pretreatment of biomass. Copyright © 2017 Elsevier Inc. All rights reserved.

  3. Probing hydrogen positions in hydrous compounds: information from parametric neutron powder diffraction studies.

    PubMed

    Ting, Valeska P; Henry, Paul F; Schmidtmann, Marc; Wilson, Chick C; Weller, Mark T

    2012-05-21

    We demonstrate the extent to which modern detector technology, coupled with a high flux constant wavelength neutron source, can be used to obtain high quality diffraction data from short data collections, allowing the refinement of the full structures (including hydrogen positions) of hydrous compounds from in situ neutron powder diffraction measurements. The in situ thermodiffractometry and controlled humidity studies reported here reveal that important information on the reorientations of structural water molecules with changing conditions can be easily extracted, providing insight into the effects of hydrogen bonding on bulk physical properties. Using crystalline BaCl2·2H2O as an example system, we analyse the structural changes in the compound and its dehydration intermediates with changing temperature and humidity levels to demonstrate the quality of the dynamic structural information on the hydrogen atoms and associated hydrogen bonding that can be obtained without resorting to sample deuteration.

  4. Iron and manganese oxide mineralization in the Pacific

    USGS Publications Warehouse

    Hein, J.R.; Koschinsky, A.; Halbach, P.; Manheim, F.T.; Bau, M.; Kang, J.-K.; Lubick, N.

    1997-01-01

    Iron, manganese, and iron-manganese deposits occur in nearly all geomorphologic and tectonic environments in the ocean basins and form by one or more of four processes: (1) hydrogenetic precipitation from cold ambient seawater, (2) precipitation from hydrothermal fluids, (3) precipitation from sediment pore waters that have been modified from bottom water compositions by diagenetic reactions in the sediment column and (4) replacement of rocks and sediment. Iron and manganese deposits occur in five forms: nodules, crusts, cements, mounds and sediment-hosted stratabound layers. Seafloor oxides show a wide range of compositions from nearly pure iron to nearly pure manganese end members. Fe/Mn ratios vary from about 24 000 (up to 58% elemental Fe) for hydrothermal seamount ironstones to about 0.001 (up to 52% Mn) for hydrothermal stratabound manganese oxides from active volcanic arcs. Hydrogenetic Fe-Mn crusts that occur on most seamounts in the ocean basins have a mean Fe/Mn ratio of 0.7 for open-ocean seamount crusts and 1.2 for continental margin seamount crusts. Fe-Mn nodules of potential economic interest from the Clarion-Clipperton Zone have a mean Fe/Mn ratio of 0.3, whereas the mean ratio for nodules from elsewhere in the Pacific is about 0.7. Crusts are enriched in Co, Ni and Pt and nodules in Cu and Ni, and both have significant concentrations of Pb, Zn, Ba, Mo, V and other elements. In contrast, hydrothermal deposits commonly contain only minor trace metal contents, although there are many exceptions, for example, with Ni contents up to 0.66%, Cr to 1.2%, and Zn to 1.4%. Chondrite-normalized REE patterns generally show a positive Ce anomaly and abundant ΣREEs for hydrogenetic and mixed hydrogenetic-diagenetic deposits, whereas the Ce anomaly is negative for hydrothermal deposits and ΣREE contents are low. However, the Ce anomaly in crusts may vary from strongly positive in East Pacific crusts to slightly negative in West Pacific crusts, which may reflect

  5. Radon exhalation study of manganese clay residue and usability in brick production.

    PubMed

    Kovács, Tibor; Shahrokhi, Amin; Sas, Zoltán; Vigh, Tamás; Somlai, János

    2017-03-01

    The reuse of by-products and residue streams is an important topic due to environmental and financial aspects. Manganese clay is a residue of manganese ore processing and is generated in huge amounts. This residue may contain some radionuclides with elevated concentrations. In this study, the radon emanation features and the massic exhalation rate of the heat-treated manganese clay were determined with regard to brick production. From the manganese mud depository, 20 samples were collected and after homogenization radon exhalation characteristics were determined as a function of firing temperatures from 100 to 750 °C. The major naturally occurring radionuclides 40 K, 226 Ra and 232 Th concentrations were 607 ± 34, 52 ± 6 and 40 ± 5 Bq kg -1 , respectively, comparable with normal clay samples. Similar to our previous studies a strong correlation was found between the internal structure and the radon emanation. The radon emanation coefficient decreased by ∼96% from 0.23 at 100 °C to 0.01 at 750 °C. The massic radon exhalation rate of samples fired at 750 °C reduced by 3% compared to samples fired at 100 °C. In light of the results, reusing of manganese clay as a brick additive is possible without any constraints. Copyright © 2016 Elsevier Ltd. All rights reserved.

  6. Manganese Research Health Project (MHRP)

    DTIC Science & Technology

    2006-01-01

    ultrafine particles (or nanoparticles) on health (e.g. Royal Society 2004) and the apparent potential for translocation of these particles along the...evaluate the usefulness of particle counting methods (CPC) in assessing exposure to ultrafine particles in manganese production scenarios. Task 4. Database...R, Kreyling W, Cox C (2004). Translocation of Inhaled Ultrafine Particles to the Brain. Inhalation toxicology; 16:437 - 445 Ritchie P, Cherrie J

  7. Absorption of Manganese and Iron in a Mouse Model of Hemochromatosis

    PubMed Central

    Kim, Jonghan; Buckett, Peter D.; Wessling-Resnick, Marianne

    2013-01-01

    Hereditary hemochromatosis, an iron overload disease associated with excessive intestinal iron absorption, is commonly caused by loss of HFE gene function. Both iron and manganese absorption are regulated by iron status, but the relationships between the transport pathways of these metals and how they are affected by HFE-associated hemochromatosis remain poorly understood. Loss of HFE function is known to alter the intestinal expression of DMT1 (divalent metal transporter-1) and Fpn (ferroportin), transporters that have been implicated in absorption of both iron and manganese. Although the influence of HFE deficiency on dietary iron absorption has been characterized, potential effects on manganese metabolism have yet to be explored. To investigate the role of HFE in manganese absorption, we characterized the uptake and distribution of the metal in Hfe −/− knockout mice after intravenous, intragastric, and intranasal administration of 54Mn. These values were compared to intravenous and intragastric administration of 59Fe. Intestinal absorption of 59Fe was increased and clearance of injected 59Fe was also increased in Hfe−/− mice compared to controls. Hfe −/− mice displayed greater intestinal absorption of 54Mn compared to wild-type Hfe+/+ control mice. After intravenous injection, the distribution of 59Fe to heart and liver was greater in Hfe −/− mice but no remarkable differences were observed for 54Mn. Although olfactory absorption of 54Mn into blood was unchanged in Hfe −/− mice, higher levels of intranasally-instilled 54Mn were associated with Hfe−/− brain compared to controls. These results show that manganese transport and metabolism can be modified by HFE deficiency. PMID:23705020

  8. Phase constitution and interface structure of nano-sized Ag-Cu/AlN multilayers: Experiment and ab initio modeling

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Pigozzi, Giancarlo; Janczak-Rusch, Jolanta; Passerone, Daniele

    2012-10-29

    Nano-sized Ag-Cu{sub 8nm}/AlN{sub 10nm} multilayers were deposited by reactive DC sputtering on {alpha}-Al{sub 2}O{sub 3}(0001) substrates. Investigation of the phase constitution and interface structure of the multilayers evidences a phase separation of the alloy sublayers into nanosized grains of Ag and Cu. The interfaces between the Ag grains and the quasi-single-crystalline AlN sublayers are semi-coherent, whereas the corresponding Cu/AlN interfaces are incoherent. The orientation relationship between Ag and AlN is constant throughout the entire multilayer stack. These observations are consistent with atomistic models of the interfaces as obtained by ab initio calculations.

  9. Reduced Uptake of FDOPA PET in End-Stage Liver Disease with Elevated Manganese Levels

    PubMed Central

    Criswell, Susan R; Perlmutter, Joel S; Crippin, Jeffrey S; Videen, Tom O; Moerlein, Stephen M; Flores, Hubert P; Birke, Angela M; Racette, Brad A

    2013-01-01

    Objective To investigate whether manganese toxicity secondary to end state liver disease is associated with nigrastriatal dysfunction as measured by 6-[18F]fluoro-L-DOPA (FDOPA) PET imaging. Design Observational case report. Setting The Movement Disorder Center at Washington University in St. Louis. Patients An individual with manganese toxicity secondary to end stage liver disease. His FDOPA PET was compared with those of 10 idiopathic Parkinson disease patients and 10 age- and sex-matched healthy controls. Main Outcome Measure The average estimated net FDOPA uptake by Patlak graphical analysis for caudate, anterior putamen and posterior putamen. Results The FDOPA uptake for the patient with secondary manganese toxicity was reduced across all regions by more than 2 SDs compared with healthy controls: caudate (reduced 24.7%), anterior putamen (28.0%), and posterior putamen (29.3%). The ratio of uptake between the caudate/posterior putamen was 0.99 and was different from that of idiopathic Parkinson disease patients, in whom the greatest reduction of FDOPA was in the posterior putamen (mean [SD] ratio, 1.65 [0.41]). Conclusions Reduce striatal uptake of FDOPA uptake indicates dysfunction of the nigrostriatal pathways in manganese toxicity secondary to end stage liver disease. The pattern of striatal involvement with equal reduction of FDOPA uptake in the caudate compared with posterior putamen appears different from those previously reported in individuals with occupational manganese toxicity and idiopathic Parkinson disease and may be specific to manganese toxicity secondary to end stage liver disease. PMID:22410448

  10. Fe–Ni solid solutions in nano-size dimensions: Effect of hydrogen annealing

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kumar, Asheesh, E-mail: asheeshk@barc.gov.in; Meena, S.S.; Banerjee, S.

    Highlights: • Fe–Ni solid solution with nano-size dimensions were prepared and characterized. • Both as prepared and hydrogenated solid solutions have FCC structure of Ni. • Paramagnetic and ferromagnetic domains coexist in these samples. - Abstract: Nanoparticles of Ni{sub 0.50}Fe{sub 0.50} and Ni{sub 0.75}Fe{sub 0.25} alloys were prepared by chemical reduction in ethylene glycol medium. XRD and {sup 57}Fe Mössbauer studies have confirmed the formation of Fe–Ni solid solution in nano-size dimensions with FCC structure. These samples consist of both ferromagnetic and paramagnetic domains which have been attributed to the coexistence of large and small particles as confirmed by atomicmore » force microscopic (AFM) and {sup 57}Fe Mössbauer spectroscopic studies. Improved extent of Fe–Fe exchange interaction existing in Ni{sub 0.50}Fe{sub 0.50} alloy compared to Ni{sub 0.75}Fe{sub 0.25} alloy explains the observed increase in the relative extent of ferromagnetic domains compared to paramagnetic domains in the former sample. Increase in the relative extent of ferromagnetic domains for hydrogenated alloys is due to increase in particle size brought about by the high temperature activation prior to hydrogenation.« less

  11. Effects of manganese and manganese-nitrogen applications on growth and nutrition of Douglas-fir seedlings.

    Treesearch

    M. A. Radwan; John S. Shumway; Dean S. DeBell

    1979-01-01

    Effects of manganese (Mn) on Douglas-fir grown in soil, with and without urea, and in nutrient solution were investigated. In addition, Mn sorption by forest soils was evaluated. Results show that Douglas-fir does not respond to added Mn and is quite tolerant to high Mn levels. Moreover, Mn sorption by soils is high. It is doubtful that Mn toxicity is of practical...

  12. Manganese-modified asphalts : chemistry of the curing reaction, its effect on properties, and evidence for manganese inactivation following cure

    DOT National Transportation Integrated Search

    1986-06-01

    The chemical reactions and reaction kinetics of asphalt modified with a patented modifier supplied by Chemkrete Technologies, Inc. were investigated. The modifier, a manganese-carboxylic acid complex, has been shown to cause a rap; d react; on with a...

  13. Evidence for hydrous high-MgO melts in the Precambrian

    NASA Astrophysics Data System (ADS)

    Stone, William E.; Deloule, Etienne; Larson, Michelle S.; Lesher, C. Michael

    1997-02-01

    Prevailing petrogenetic models for Precambrian high-MgO melts such as komatiites invoke crystallization from nearly anhydrous melts (≪0.5% H2O) generated by partial melting of mantle peridotite at temperatures of (≤ 1900 °C and pressures of (18 GPa. However, ultramafic cumulate and gabbro zones of komatiitic and other high-MgO units in Precambrian greenstone belts contain vesicles and minor to major amounts (≤ 25%) of igneous amphibole. The textures (oikocrysts, rims on intercumulate pyroxene, and mineral inclusions within orthocumulate olivine) and the water-rich compositions (1.00% 2.50% H2O) of igneous amphiboles from the Archean Abitibi belt indicate crystallization in situ from significantly hydrous melts while the melt fraction was still as high as 40% 50%. Comparisons to experimental phase equilibria suggest that the residual melts from which the amphiboles crystallized contained 3% 4% H2O, and adjustments for fractional crystallization suggest that the initial melts may have contained as much as 2% H2O. H2O contents of this magnitude would require substantial revision of the nearly anhydrous models for Precambrian high-MgO melts, possibly permitting generation at lower temperatures and pressures, lowering their densities and viscosities, increasing their eruptibility, and enhancing the formation of spinifex textures.

  14. Thermal stability of ladderane lipids as determined by hydrous pyrolysis

    USGS Publications Warehouse

    Jaeschke, A.; Lewan, M.D.; Hopmans, E.C.; Schouten, S.; Sinninghe, Damste J.S.

    2008-01-01

    Anaerobic ammonium oxidation (anammox) has been recognized as a major process resulting in loss of fixed inorganic nitrogen in the marine environment. Ladderane lipids, membrane lipids unique to anammox bacteria, have been used as markers for the detection of anammox in marine settings. However, the fate of ladderane lipids after sediment burial and maturation is unknown. In this study, anammox bacterial cell material was artificially matured by hydrous pyrolysis at constant temperatures ranging from 120 to 365 ??C for 72 h to study the stability of ladderane lipids during progressive dia- and catagenesis. HPLC-MS/MS analysis revealed that structural alterations of ladderane lipids already occurred at 120 ??C. At temperatures >140 ??C, ladderane lipids were absent and only more thermally stable products could be detected, i.e., ladderane derivatives in which some of the cyclobutane rings were opened. These diagenetic products of ladderane lipids were still detectable up to temperatures of 260 ??C using GC-MS. Thus, ladderane lipids are unlikely to occur in ancient sediments and sedimentary rocks, but specific diagenetic products of ladderane lipids will likely be present in sediments and sedimentary rocks of relatively low maturity (i.e., C31 hopane 22S/(22S + 22R) ratio 0.5). ?? 2008 Elsevier Ltd.

  15. Structural Characterization of Biogenic Manganese Oxides Produced in Sea Water

    NASA Astrophysics Data System (ADS)

    Webb, S. M.; Bargar, J. R.; Tebo, B. M.

    2003-12-01

    Manganese oxides have been coined as the "scavengers of the sea" and play important roles in both marine and freshwater systems. Natural manganese oxide nanoparticles and grain coatings are ubiquitous in the environment and profoundly impact the quality of sediments via their ability to degrade and sequester contaminants. These oxides are believed to form dominantly via oxidation of Mn(II) by marine and freshwater bacteria and have extremely high sorptive capacities for heavy metals. We have used XANES, EXAFS, and synchrotron (SR)-XRD techniques to study biogenic manganese oxides produced by spores of the marine Bacillus sp., strain SG-1 in seawater as a function of reaction time under fully in-situ conditions. The primary biogenic solid-phase Mn oxide product is a hexagonal layered phyollomanganate with an oxidation state similar to that in delta-MnO2. XRD data show the biooxides to have a phyllomanganate 10 basal plane spacing, suggesting the interlayer is hydrated and contains calcium. As the experiment continues, the initial biooxide changes to show triclinic symmetry. Fits to these EXAFS spectra suggest the octahedral layers have low Mn octahedral site vacancies in the lattice and the latyers bend to accommodate Jahn-Teller distortions creating the change in symmetry. The oxides observed in this study as models of Mn(II) bio-oxidation may be representative of the most abundant manganese oxide phase suspended in the oxic and sub-oxic zones of the oceanic water column.

  16. Influence of metallic additives on manganese ferrites sintering

    NASA Astrophysics Data System (ADS)

    Shevelev, S. A.; Luchnikov, P. A.; Yarullina, A. R.

    2018-01-01

    Influence of cuprum nanopowder additive received by electric explosion on the process of manganese ferrites MgFe2O4 consolidating at thermal sintering was researched by dilatometry method. Cuprum nanopowder at a rate of 5 mass % was added into the original commercial-grade powder of manganese ferrite MgFe2O4. Powder mixture was numerously blended with screening for better blending before pressing. Powder compacts were formed by cold one-axle static pressing. It was proved that introduction of cuprum additive caused shrinkage increase at final heating stage. There was abnormal compact enlarging at sintering in the air at isothermal stage; the specified process was not observed in vacuum. This difference can be explained by changes in conditions of gaseous discharge from volume of pores.

  17. Durable rechargeable zinc-air batteries with neutral electrolyte and manganese oxide catalyst

    NASA Astrophysics Data System (ADS)

    Sumboja, Afriyanti; Ge, Xiaoming; Zheng, Guangyuan; Goh, F. W. Thomas; Hor, T. S. Andy; Zong, Yun; Liu, Zhaolin

    2016-11-01

    Neutral chloride-based electrolyte and directly grown manganese oxide on carbon paper are used as the electrolyte and air cathode respectively for rechargeable Zn-air batteries. Oxygen reduction and oxygen evolution reactions on manganese oxide show dependence of activities on the pH of the electrolyte. Zn-air batteries with chloride-based electrolyte and manganese oxide catalyst exhibit satisfactory voltage profile (discharge and charge voltage of 1 and 2 V at 1 mA cm-2) and excellent cycling stability (≈90 days of continuous cycle test), which is attributed to the reduced carbon corrosion on the air cathode and decreased carbonation in neutral electrolyte. This work describes a robust electrolyte system that improves the cycle life of rechargeable Zn-air batteries.

  18. Reduction in the Band Gap of Manganese-Doped Zinc Oxide: Role of the Oxidation State

    NASA Astrophysics Data System (ADS)

    Sharma, Sonia; Ramesh, Pranith; Swaminathan, P.

    2015-12-01

    Manganese-doped zinc oxide powders were synthesized by solid state reaction of the respective oxides. The high-temperature conditions were chosen such that multiple valence states of manganese were doped in the host zinc oxide lattice. Structural characterization was carried out to confirm the doping and to find the maximum amount of manganese that can be incorporated. Diffuse reflectance spectroscopy was used to measure the optical band gap of the doped sample and the lowering with respect to pure ZnO was attributed to the presence of higher oxidation states of manganese. The presence of these oxidation states was confirmed using x-ray photoelectron spectroscopy. The study shows that a solid state reaction is a viable route for synthesizing doped metal oxides with desired optical properties.

  19. Contribution of arginase to manganese metabolism of Aspergillus niger.

    PubMed

    Keni, Sarita; Punekar, Narayan S

    2016-02-01

    Aspects of manganese metabolism during normal and acidogenic growth of Aspergillus niger were explored. Arginase from this fungus was a Mn[II]-enzyme. The contribution of the arginase protein towards A. niger manganese metabolism was investigated using arginase knockout (D-42) and arginase over-expressing (ΔXCA-29) strains of A. niger NCIM 565. The Mn[II] contents of various mycelial fractions were found in the order: D-42 strain < parent strain < ΔXCA-29 strain. While the soluble fraction forms 60% of the total mycelial Mn[II] content, arginase accounted for a significant fraction of this soluble Mn[II] pool. Changes in the arginase levels affected the absolute mycelial Mn[II] content but not its distribution in the various mycelial fractions. The A. niger mycelia harvested from acidogenic growth media contain substantially less Mn[II] as compared to those from normal growth media. Nevertheless, acidogenic mycelia harbor considerable Mn[II] levels and a functional arginase. Altered levels of mycelial arginase protein did not significantly influence citric acid production. The relevance of arginase to cellular Mn[II] pool and homeostasis was evaluated and the results suggest that arginase regulation could occur via manganese availability.

  20. Manganese Deposits in the Artillery Mountains Region, Mohave County, Arizona

    USGS Publications Warehouse

    Lasky, S.G.; Webber, B.N.

    1944-01-01

    The manganese deposits of the Artillery Mountains region lie within an area of about 25 square miles between the Artillery and Rawhide Mountains, on the west side of the Bill Williams River in west-central Arizona. The richest croppings are on the northeast side of this area, among the foothills of the Artillery Mountains. They are 6 to 10 miles from Alamo. The nearest shipping points are Congress, about 50 miles to the east, and Aguila, about 50 miles to the southeast. The principal manganese deposits are part of a sequence of alluvial fan and playa material, probably of early Pliocene age, which were laid down in a fault basin. They are overlain by later Pliocene (?) basalt flows and sediments and by Quaternary basalt and alluvium. The Pliocene (?) rocks are folded into a shallow composite S1ncline ttat occupies the valley between the Artillery and Rawhide Mountains, and the folded rocks along either side of the valley, together with the overlying Quaternary basalt, are broken by faults that have produced a group of horsts, grabens, and step-fault blocks. The manganiferous beds, lie at two zones, 750 to 1,000 feet apart stratigraphically, each of which is locally as much as 300 to 400 feet thick. The main, or upper, zone contains three kinds of ore - sandstone ore, clay ore, and 'hard' ore. The sandstone and clay ores differ from the associated barren sandstone and clay, with which they are interlayered and into which they grade, primarily in containing a variable proportion of amorphous manganese oxides, besides iron oxides and clayey material such as are present in the barren beds. The 'hard' ore is sandstone that has been impregnated with opal and calcite and in which the original amorphous manganese oxides have been largely converted to psilomelane and manganite. The average manganese content of the sandstone and clay ores is between 3 and 4 percent and that of the 'hard' ore is between 6 and 7 percent. The ore contains an average of 3 percent of iron, 0

  1. Nano-sized Superlattice Clusters Created by Oxygen Ordering in Mechanically Alloyed Fe Alloys

    NASA Astrophysics Data System (ADS)

    Hu, Yong-Jie; Li, Jing; Darling, Kristopher A.; Wang, William Y.; Vanleeuwen, Brian K.; Liu, Xuan L.; Kecskes, Laszlo J.; Dickey, Elizabeth C.; Liu, Zi-Kui

    2015-07-01

    Creating and maintaining precipitates coherent with the host matrix, under service conditions is one of the most effective approaches for successful development of alloys for high temperature applications; prominent examples include Ni- and Co-based superalloys and Al alloys. While ferritic alloys are among the most important structural engineering alloys in our society, no reliable coherent precipitates stable at high temperatures have been found for these alloys. Here we report discovery of a new, nano-sized superlattice (NSS) phase in ball-milled Fe alloys, which maintains coherency with the BCC matrix up to at least 913 °C. Different from other precipitates in ferritic alloys, this NSS phase is created by oxygen-ordering in the BCC Fe matrix. It is proposed that this phase has a chemistry of Fe3O and a D03 crystal structure and becomes more stable with the addition of Zr. These nano-sized coherent precipitates effectively double the strength of the BCC matrix above that provided by grain size reduction alone. This discovery provides a new opportunity for developing high-strength ferritic alloys for high temperature applications.

  2. Partial oxidation (“aging”) and surface modification decrease the toxicity of nano-sized zero valent iron.

    EPA Science Inventory

    Nanosize zero-valent iron (nZVI) is used as a redox-active catalyst for in situ remediation of contaminated ground waters. In aqueous environments, nZVI oxidizes over time (i.e., “ages”) to magnetite and other oxides. For remediation, hi...

  3. Nano-sized ZnO powders prepared by co-precipitation method with various pH

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Purwaningsih, S. Y., E-mail: sriyanisaputri@gmail.com; Pratapa, S.; Triwikantoro,

    2016-04-19

    In this work, nano-sized ZnO powders have been synthesized by the co-precipitation method with Zn(CH3COOH)2.2H2O, HCl, and NH3.H2O as raw materials in various pH ranging from 8 to 10. The purity, microstructure, chemical group analysis, morphology of the prepared ZnO powders were studied by X-ray diffraction (XRD), Fourier transform infrared spectrometer (FTIR), energy dispersive X-ray spectrometry (EDX), and scanning electron microscope (SEM), respectively. Rietveld refinement of XRD data showed that ZnO crystallizes in the wurtzite structure with high purity. The obtained powders were nano-sized particles with the average crystallite size about 17.9 ± 2.1 nm synthesized with pH of 9.5, atmore » 85°C, and stirring time of 6 h. The SEM results have visualied the morphology of ZnO nanoparticles with spherical-like shape. The effect of processing conditions on morphology of ZnO was also discussed.« less

  4. Manganese and iron geochemistry in sediments underlying the redox-stratified Fayetteville Green Lake

    NASA Astrophysics Data System (ADS)

    Herndon, Elizabeth M.; Havig, Jeff R.; Singer, David M.; McCormick, Michael L.; Kump, Lee R.

    2018-06-01

    Manganese and iron are redox-sensitive elements that yield clues about biogeochemistry and redox conditions both in modern environments and in the geologic past. Here, we investigated Mn and Fe-bearing minerals preserved in basin sediments underlying Fayetteville Green Lake, a redox-stratified lake that serves as a geochemical analogue for Paleoproterozoic oceans. Synchrotron-source microprobe techniques (μXRF, μXANES, and μXRD) and bulk geochemical analyses were used to examine the microscale distribution and speciation of Mn, Fe, and S as a function of depth in the top 48 cm of anoxic lake sediments. Manganese was primarily associated with calcite grains as a manganese-rich carbonate that precipitated in the chemocline of the water column and settled through the euxinic basin to collect in lake sediments. Iron was preserved in framboidal iron sulfides that precipitated in euxinic bottom waters and underwent transformation to pyrite and marcasite in the sediments. Previous studies attribute the formation of manganese-rich carbonates to the diagenetic alteration of manganese oxides deposited in basins underlying oxygenated water. Our study challenges this paradigm by providing evidence that Mn-bearing carbonates form in the water column and accumulate in sediments below anoxic waters. Consequently, manganoan carbonates preserved in the rock record do not necessarily denote the presence of oxygenated bottom waters in ocean basins.

  5. High resolution photolithography using arrays of polystyrene and SiO2 micro- and nano-sized spherical lenses

    NASA Astrophysics Data System (ADS)

    Dvoretckaia, L. N.; Mozharov, A. M.; Mukhin, I. S.

    2017-11-01

    Photolithography mask made of close-packed array of micro- and nano-sized spherical lenses allows to obtain the ordered structures and provides highest “optical resolution/cost” ratio between all existing photolithography and laser direct writing methods. In this letter, we present results of modeling the propagation of a plane wave falling on the array of quartz (SiO2) microspherical lenses and focusing in the image reverse photoresist layer. We present here experimental results on fabrication of ordered arrays of submicron wells and columns and substrate preparation for growth of monocrystalline nanowires on metal surface using photolithography with mask of SiO2 microspheres. Such ordered nano-sized arrays of wells and columns can be used in fabrication of further growth of monocrystalline nanowires, quantum dots and production of plasmon structures.

  6. Sulfur solubility in hydrous Etna Basalt at temperatures from 1150 to 1250 °C and 200 MPa

    NASA Astrophysics Data System (ADS)

    Beermann, O.; Nowak, N.; Botcharnikov, R. E.; Holtz, F.

    2009-04-01

    Degassing of magmatic volatiles is strongly dependent on fluid-melt interaction at the oneset of degassing under given pressure and temperature. Most magmatic fluids are composed of hydrous multicomponental mixtures, e.g. H-O-C-S-Cl-F-Br bearing fluids. In particular the partitioning behaviour of S and Cl between basaltic melt and hydrous fluid is of interest, because the S/Cl ratio of emitted volcanic gasses correlate to the eruption style (e.g. [1], [2], [3]). In particular, this was also observed for the 2002 eruption of Mt. Etna (Sicily) [4], which is one of the worlds most active and best investigated volcanoes. Since now, there even exist no reliable data on the solubility of sulfur in hydrous silicic melts at geologic relevant temperatures for basaltic magmas (above 1050 °C), because sulfur is known to be a very aggressive component limiting the application of experimental approaches that use noble metal capsules, especially Pt and AuPd. Thus, the experiments in this study, concerning the solubility of S in natural hydrous Etna basalt at 200 MPa and temperatures from 1150 to 1250 °C at fO2 ~ NNO + 2.5 and 1200 °C at fO2 ~ NNO, were performed in olivine-AuPd double capsules, using single crystal olivine capsules (San Carlos olivine) as sample containers, which were inserted into outer Au80Pd20 capsules. The starting material was a fused and water presaturated trachybasalt from Mt. Etna (2001 eruption), containing 5 wt.% H2O. For sulfur source pyrrhotine (FeS) was used, obtaining initial S concentrations between 1-1.5 wt.% (with respect to the amount of starting material). For some experiments an olivine disc was placed between FeS and starting glass powder to avoid FeS dispersion in the melt. All experiments were conducted in internally heated argon pressure vessels (IHPV) equipped with rapid quench device. For the reduced runs an Ar-H2 mixture was load into the vessel and the H2 pressure was monitored, using the shaw membrane technique. The experimental

  7. Alteration of serum concentrations of manganese, iron, ferritin, and transferrin receptor following exposure to welding fumes among career welders.

    PubMed

    Lu, Ling; Zhang, Long-Lian; Li, G Jane; Guo, Wenrui; Liang, Wannian; Zheng, Wei

    2005-03-01

    This study was performed to determine airborne manganese levels during welding practice and to establish the relationship between long-term, low-level exposure to manganese and altered serum concentrations of manganese, iron, and proteins associated with iron metabolism in career welders. Ninety-seven welders (average age of 36 years) who have engaged in electric arc weld in a vehicle manufacturer were recruited as the exposed group. Welders worked 7-8h per day with employment duration of 1-33 years. Control subjects consisted of 91 employees (average age of 35 years) in the same factory but not in the welding profession. Ambient manganese levels in welders' breathing zone were the highest inside the vehicle (1.5 +/- 0.7 mg/m3), and the lowest in the center of the workshop (0.2 +/- 0.05 mg/m3). Since the filter size was 0.8 microm, it is possible that these values may be likely an underestimation of the true manganese levels. Serum levels of manganese and iron in welders were about three-fold (p < 0.01) and 1.2-fold (p < 0.01), respectively, higher than those of controls. Serum concentrations of ferritin and transferrin were increased among welders, while serum transferrin receptor levels were significantly decreased in comparison to controls. Linear regression analyses revealed a lack of association between serum levels of manganese and iron. However, serum concentrations of iron and ferritin were positively associated with years of welder experience (p < 0.05). Moreover, serum transferrin receptor levels were inversely associated with serum manganese concentrations (p < 0.05). These findings suggest that exposure to welding fume among welders disturbs serum homeostasis of manganese, iron, and the proteins associated with iron metabolism. Serum manganese may serve as a reasonable biomarker for assessment of recent exposure to airborne manganese.

  8. Sonocatalytic degradation of some dyestuffs and comparison of catalytic activities of nano-sized TiO2, nano-sized ZnO and composite TiO2/ZnO powders under ultrasonic irradiation.

    PubMed

    Wang, Jun; Jiang, Zhe; Zhang, Liqun; Kang, Pingli; Xie, Yingpeng; Lv, Yanhui; Xu, Rui; Zhang, Xiangdong

    2009-02-01

    Here, a novel sonocatalyst, composite TiO2/ZnO powder, was prepared through the combination of nano-sized TiO2 and ZnO powders. Because of the appropriate adsorbability to organic pollutants and special crystal interphase between TiO2 and ZnO particles, the composite TiO2/ZnO powder exhibits a high sonocatalytic activity under ultrasonic irradiation during the degradation of acid red B. Especially, the sonocatalytic activity of composite TiO2/ZnO powder with 4:1 molar proportion treated at 500 degrees C for 50 min showed obvious improvement compared with pure nano-sized TiO2 and ZnO powders. When the experimental conditions such as 10mg/L acid red B concentration, 1.0 g/L catalyst addition amount, pH=7.0, 20 degrees C system temperature, 100 min ultrasonic time and 50 mL total volume were adopted, the satisfactory degradation ratio and rate were obtained. All experiments indicate that the sonocatalytic method using composite TiO2/ZnO powder may be a more advisable choice for the treatments of non- or low-transparent organic wastewaters in future.

  9. Manganese distribution in brains of Sprague-Dawley rats after 60 days of stainless steel welding-fume exposure.

    PubMed

    Yu, Il Je; Park, Jung Duck; Park, Eon Sub; Song, Kyung Seuk; Han, Kuy Tae; Han, Jeong Hee; Chung, Yong Hyun; Choi, Byung Sun; Chung, Kyu Hyuck; Cho, Myung Haing

    2003-12-01

    Welders working in a confined space, as in the shipbuilding industry, are at risk of being exposed to high concentrations of welding fumes and developing pneumoconiosis or other welding-fume exposure related diseases. Among such diseases, manganism resulting from welding-fume exposure remains a controversial issue, as the movement of manganese into specific brain regions has not yet been clearly established. Accordingly, to investigate the distribution of manganese in the brain after welding-fume exposure, male Sprague-Dawley rats were exposed to welding fumes generated from manual metal arc-stainless steel (MMA-SS) at concentrations of 63.6 +/- 4.1 mg/m(3) (low dose, containing 1.6 mg/m(3) Mn) and 107.1 +/- 6.3 mg/m(3) (high dose, containing 3.5 mg/m(3) Mn) total suspended particulate (TSP) for 2 h per day in an inhalation chamber over a 60-day period. Blood, brain, lung, and liver samples were collected after 2 h, 15, 30, and 60 days of exposure and the tissues analyzed for their manganese concentrations using an atomic absorption spectrophotometer. Although dose- and time-dependent increases in the manganese concentrations were found in the lungs and livers of the rats exposed for 60 days, only slight manganese increases were observed in the blood during this period. Major statistically significant increases in the brain manganese concentrations were detected in the cerebellum after 15 days of exposure and up until 60 days. Slight increases in the manganese concentrations were also found in the substantia nigra, basal ganglia (caudate nucleus, putamen, and globus pallidus), temporal cortex, and frontal cortex, thereby indicating that the pharmacokinetics and distribution of the manganese inhaled from the welding fumes were different from those resulting from manganese-only exposure.

  10. Exposure to manganese: health effects on the general population, a pilot study in central Mexico.

    PubMed

    Santos-Burgoa, C; Rios, C; Mercado, L A; Arechiga-Serrano, R; Cano-Valle, F; Eden-Wynter, R A; Texcalac-Sangrador, J L; Villa-Barragan, J P; Rodriguez-Agudelo, Y; Montes, S

    2001-02-01

    To support a risk assessment of manganese exposure in two communities living within a manganese mining district a cross-sectional study was performed on a sample of the adult population of long-term residents. One community was exposed to a point source from an ore primary refining plant. Manganese is an essential mineral for human life. It is also the fourth in importance for industrial metal making. Data were collected on socioeconomic living conditions, emission sources, environmental media concentrations (air, water, soil, dust, food), respiratory symptomatology, and a neuropsychological examination (Mini-Mental Screening test, the Hooper Visual Organization test, the Ardila-Ostroski, and others). We examined 73 subjects (52 women), most of low socioeconomic status. Environmental air concentrations were 2 to 3 times higher than those in other urban concentrations. Manganese blood concentrations ranged from 7.5 to 88 microg/L, with a median concentration of 15, the upper quartile starting at 20 microg/L; the upper 10% was above 25 microg/L. Lead and manganese were highly correlated; there was an inverse relation to hemoglobin. Reduced levels of plasma lipid peroxidation were associated with blood manganese. Using multivariate logistic regression, we identified B-Mn as increasing the risk of deficient cognitive performance 12 times (Mini-Mental score of less than 17). Copyright 2001 Academic Press.

  11. Characterization of Total and Size-Fractionated Manganese Exposure by Work Area in a Shipbuilding Yard.

    PubMed

    Jeong, Jee Yeon; Park, Jong Su; Kim, Pan Gyi

    2016-06-01

    Shipbuilding involves intensive welding activities, and welders are exposed to a variety of metal fumes, including manganese, that may be associated with neurological impairments. This study aimed to characterize total and size-fractionated manganese exposure resulting from welding operations in shipbuilding work areas. In this study, we characterized manganese-containing particulates with an emphasis on total mass (n = 86, closed-face 37-mm cassette samplers) and particle size-selective mass concentrations (n = 86, 8-stage cascade impactor samplers), particle size distributions, and a comparison of exposure levels determined using personal cassette and impactor samplers. Our results suggest that 67.4% of all samples were above the current American Conference of Governmental Industrial Hygienists manganese threshold limit value of 100 μg/m(3) as inhalable mass. Furthermore, most of the particles containing manganese in the welding process were of the size of respirable particulates, and 90.7% of all samples exceeded the American Conference of Governmental Industrial Hygienists threshold limit value of 20 μg/m(3) for respirable manganese. The concentrations measured with the two sampler types (cassette: total mass; impactor: inhalable mass) were significantly correlated (r = 0.964, p < 0.001), but the total concentration obtained using cassette samplers was lower than the inhalable concentration of impactor samplers.

  12. Calcium manganese oxides as oxygen evolution catalysts: O2 formation pathways indicated by 18O-labelling studies.

    PubMed

    Shevela, Dmitriy; Koroidov, Sergey; Najafpour, M Mahdi; Messinger, Johannes; Kurz, Philipp

    2011-05-02

    Oxygen evolution catalysed by calcium manganese and manganese-only oxides was studied in (18)O-enriched water. Using membrane-inlet mass spectrometry, we monitored the formation of the different O(2) isotopologues (16)O(2), (16)O(18)O and (18)O(2) in such reactions simultaneously with good time resolution. From the analysis of the data, we conclude that entirely different pathways of dioxygen formation catalysis exist for reactions involving hydrogen peroxide (H(2)O(2)), hydrogen persulfate (HSO(5)(-)) or single-electron oxidants such as Ce(IV) and [Ru(III) (bipy)(3)](3+) . Like the studied oxide catalysts, the active sites of manganese catalase and the oxygen-evolving complex (OEC) of photosystem II (PSII) consist of μ-oxido manganese or μ-oxido calcium manganese sites. The studied processes show very similar (18)O-labelling behaviour to the natural enzymes and are therefore interesting model systems for in vivo oxygen formation by manganese metalloenzymes such as PSII. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Calcium manganese(IV) oxides: biomimetic and efficient catalysts for water oxidation.

    PubMed

    Najafpour, Mohammad Mahdi; Pashaei, Babak; Nayeri, Sara

    2012-04-28

    CaMnO(3) and Ca(2)Mn(3)O(8) were synthesized and characterized by SEM, XRD, FTIR and BET. Both oxides showed oxygen evolution activity in the presence of oxone, cerium(IV) ammonium nitrate and H(2)O(2). Oxygen evolution from water during irradiation with visible light (λ > 400 nm) was also observed upon adding these manganese oxides to an aqueous solution containing tris(2,2'-bipyridyl) ruthenium(II), as photosensitizer, and chloro pentaammine cobalt(III) chloride, as electron acceptor, in an acetate buffer. The amounts of dissolved manganese and calcium from CaMnO(3) and Ca(2)Mn(3)O(8) in the oxygen evolving reactions were reported and compared with other (calcium) manganese oxides. Proposed mechanisms of oxygen evolution and proposed roles for the calcium ions are also considered. This journal is © The Royal Society of Chemistry 2012

  14. Red-emitting manganese-doped aluminum nitride phosphor

    NASA Astrophysics Data System (ADS)

    Cherepy, Nerine J.; Payne, Stephen A.; Harvey, Nicholas M.; Åberg, Daniel; Seeley, Zachary M.; Holliday, Kiel S.; Tran, Ich C.; Zhou, Fei; Martinez, H. Paul; Demeyer, Jessica M.; Drobshoff, Alexander D.; Srivastava, Alok M.; Camardello, Samuel J.; Comanzo, Holly A.; Schlagel, Deborah L.; Lograsso, Thomas A.

    2016-04-01

    We report high efficiency luminescence with a manganese-doped aluminum nitride red-emitting phosphor under 254 nm excitation, as well as its excellent lumen maintenance in fluorescent lamp conditions, making it a candidate replacement for the widely deployed europium-doped yttria red phosphor. Solid-state reaction of aluminum nitride powders with manganese metal at 1900 °C, 10 atm N2 in a reducing environment results in nitrogen deficiency, as revealed diffuse reflectance spectra. When these powders are subsequently annealed in flowing nitrogen at 1650 °C, higher nitrogen content is recovered, resulting in white powders. Silicon was added to samples as an oxygen getter to improve emission efficiency. NEXAFS spectra and DFT calculations indicate that the Mn dopant is divalent. From DFT calculations, the UV absorption band is proposed to be due to an aluminum vacancy coupled with oxygen impurity dopants, and Mn2+ is assumed to be closely associated with this site. In contrast with some previous reports, we find that the highest quantum efficiency with 254 nm excitation (Q.E. = 0.86 ± 0.14) is obtained in aluminum nitride with a low manganese doping level of 0.06 mol.%. The principal Mn2+ decay of 1.25 ms is assigned to non-interacting Mn sites, while additional components in the microsecond range appear with higher Mn doping, consistent with Mn clustering and resultant exchange coupling. Slower components are present in samples with low Mn doping, as well as strong afterglow, assigned to trapping on shallow traps followed by detrapping and subsequent trapping on Mn.

  15. Barium and manganese-doped zinc silicate rods prepared by mesoporous template route and their luminescence property

    NASA Astrophysics Data System (ADS)

    Dang, Lingyan; Tian, Chen; Zhao, Shifeng; Lu, Qingshan

    2018-06-01

    Barium and manganese-doped zinc silicates was prepared under hydrothermal treatment by mesoporous template route employing mesoporous silica as an active template. The sample displays a rod-like morphology with a mean diameter of ∼40 nm and a mean length of ∼450 nm, which inherits the characteristics of mesoporous silica. The individual rods show single crystalline and assemble into bundle-like hierarchical structure along the channels of the mesoporous silica. When barium ions together with manganese ions are co-doped in zinc silicate, the green emission corresponding to manganese ions display a significant enhancement, especially for the sample with the barium doping concentration of 0.08, which indicates that an energy transfer from barium to manganese ions takes place. With further increasing barium concentration from 0.08 to 0.10, the recombination between the defects related to barium and the excitation states of the manganese dominates accompanying non-radiative transitions which can reduce the emission efficiency.

  16. Nanosized copper ferrite materials: Mechanochemical synthesis and characterization

    NASA Astrophysics Data System (ADS)

    Manova, Elina; Tsoncheva, Tanya; Paneva, Daniela; Popova, Margarita; Velinov, Nikolay; Kunev, Boris; Tenchev, Krassimir; Mitov, Ivan

    2011-05-01

    Nanodimensional powders of cubic copper ferrite are synthesized by two-steps procedure of co-precipitation of copper and iron hydroxide carbonates, followed by mechanochemical treatment. X-ray powder diffraction, Mössbauer spectroscopy and temperature-programmed reduction are used for the characterization of the obtained materials. Their catalytic behavior is tested in methanol decomposition to hydrogen and CO and total oxidation of toluene. Formation of nanosized ferrite material is registered even after one hour of milling time. It is established that the prolonging of treatment procedure decreases the dispersion of the obtained product with the appearance of Fe 2O 3. It is demonstrated that the catalytic behavior of the samples depends not only on their initial phase composition, but on the concomitant ferrite phase transformations by the influence of the reaction medium.

  17. Quantitative analysis of dinuclear manganese(II) EPR spectra

    NASA Astrophysics Data System (ADS)

    Golombek, Adina P.; Hendrich, Michael P.

    2003-11-01

    A quantitative method for the analysis of EPR spectra from dinuclear Mn(II) complexes is presented. The complex [(Me 3TACN) 2Mn(II) 2(μ-OAc) 3]BPh 4 ( 1) (Me 3TACN= N, N', N''-trimethyl-1,4,7-triazacyclononane; OAc=acetate 1-; BPh 4=tetraphenylborate 1-) was studied with EPR spectroscopy at X- and Q-band frequencies, for both perpendicular and parallel polarizations of the microwave field, and with variable temperature (2-50 K). Complex 1 is an antiferromagnetically coupled dimer which shows signals from all excited spin manifolds, S=1 to 5. The spectra were simulated with diagonalization of the full spin Hamiltonian which includes the Zeeman and zero-field splittings of the individual manganese sites within the dimer, the exchange and dipolar coupling between the two manganese sites of the dimer, and the nuclear hyperfine coupling for each manganese ion. All possible transitions for all spin manifolds were simulated, with the intensities determined from the calculated probability of each transition. In addition, the non-uniform broadening of all resonances was quantitatively predicted using a lineshape model based on D- and r-strain. As the temperature is increased from 2 K, an 11-line hyperfine pattern characteristic of dinuclear Mn(II) is first observed from the S=3 manifold. D- and r-strain are the dominate broadening effects that determine where the hyperfine pattern will be resolved. A single unique parameter set was found to simulate all spectra arising for all temperatures, microwave frequencies, and microwave modes. The simulations are quantitative, allowing for the first time the determination of species concentrations directly from EPR spectra. Thus, this work describes the first method for the quantitative characterization of EPR spectra of dinuclear manganese centers in model complexes and proteins. The exchange coupling parameter J for complex 1 was determined ( J=-1.5±0.3 cm-1; H ex=-2J S1· S2) and found to be in agreement with a previous

  18. Characterization of Synthetic and Natural Manganese Oxides as Martian Analogues

    NASA Technical Reports Server (NTRS)

    Fox, V. K.; Arvidson, R. E.; Jolliff, B. L.; Carpenter, P. K.; Catalano, J. G.; Hinkle, M. A. G.; Morris, R. V.

    2015-01-01

    Recent discoveries of highly concentrated manganese oxides in Gale Crater and on the rim of Endeavour Crater by the Mars Science Laboratory Curiosity and Mars Exploration Rover Opportunity, respectively, imply more highly oxidizing aqueous conditions than previously recognized. Manganese oxides are a significant environmental indicator about ancient aqueous conditions, provided the phases can be characterized reliably. Manganese oxides are typically fine-grained and poorly crystalline, making the mineral structures difficult to determine, and they generally have very low visible reflectance with few distinctive spectral features in the visible to near infrared, making them a challenge for interpretation from remote sensing data. Therefore, these recent discoveries motivate better characterization using methods available on Mars, particularly visible to near infrared (VNIR) spectroscopy, X-ray diffractometry (XRD), and compositional measurements. Both rovers have complementary instruments in this regard. Opportunity is equipped with its multispectral visible imager, Pancam, and an Alpha Particle X-ray Spectrometer (APXS), and Curiosity has the multispectral Mastcam, ChemCam (laser-induced breakdown spectroscopy and passive spectroscopy), and APXS for in situ characterization, and ChemMin (XRD) for collected samples.

  19. Hybrid ternary rice paper-manganese oxide-carbon nanotube nanocomposites for flexible supercapacitors

    NASA Astrophysics Data System (ADS)

    Jiang, Wenchao; Zhang, Kaixi; Wei, Li; Yu, Dingshan; Wei, Jun; Chen, Yuan

    2013-10-01

    Modern portable electronic devices create a strong demand for flexible energy storage devices. Paper based nanocomposites are attractive as sustainable materials for such applications. Here, we directly explored the hydroxyl chemistry of cellulose fibers to synthesize hybrid ternary nanocomposites, comprised of rice paper, single-walled carbon nanotubes (SWCNTs) and manganese oxide nanoparticles. The functional groups on cellulose fibers can react with adsorbed permanganate ions, resulting in uniform deposition of manganese oxide nanoparticles. SWCNTs coated on top of manganese oxide nanoparticles form a highly conductive network connecting individual manganese oxide particles. By using the hybrid ternary composites as electrodes, the assembled two-electrode supercapacitors demonstrated high capacitance (260.2 F g-1), energy (9.0 W h kg-1), power (59.7 kW kg-1), and cycle stability (12% drop after 3000 cycles). In addition, the nanocomposites show good strength and excellent mechanical flexibility, and their capacitance shows negligible changes after bending more than 100 times. These findings suggest that opportunities exist to further explore the rich chemistry of cellulose fibers for innovative energy applications.Modern portable electronic devices create a strong demand for flexible energy storage devices. Paper based nanocomposites are attractive as sustainable materials for such applications. Here, we directly explored the hydroxyl chemistry of cellulose fibers to synthesize hybrid ternary nanocomposites, comprised of rice paper, single-walled carbon nanotubes (SWCNTs) and manganese oxide nanoparticles. The functional groups on cellulose fibers can react with adsorbed permanganate ions, resulting in uniform deposition of manganese oxide nanoparticles. SWCNTs coated on top of manganese oxide nanoparticles form a highly conductive network connecting individual manganese oxide particles. By using the hybrid ternary composites as electrodes, the assembled two

  20. Thermodynamics of manganese oxides: Sodium, potassium, and calcium birnessite and cryptomelane

    PubMed Central

    Birkner, Nancy; Navrotsky, Alexandra

    2017-01-01

    Manganese oxides with layer and tunnel structures occur widely in nature and inspire technological applications. Having variable compositions, these structures often are found as small particles (nanophases). This study explores, using experimental thermochemistry, the role of composition, oxidation state, structure, and surface energy in the their thermodynamic stability. The measured surface energies of cryptomelane, sodium birnessite, potassium birnessite and calcium birnessite are all significantly lower than those of binary manganese oxides (Mn3O4, Mn2O3, and MnO2), consistent with added stabilization of the layer and tunnel structures at the nanoscale. Surface energies generally decrease with decreasing average manganese oxidation state. A stabilizing enthalpy contribution arises from increasing counter-cation content. The formation of cryptomelane from birnessite in contact with aqueous solution is favored by the removal of ions from the layered phase. At large surface area, surface-energy differences make cryptomelane formation thermodynamically less favorable than birnessite formation. In contrast, at small to moderate surface areas, bulk thermodynamics and the energetics of the aqueous phase drive cryptomelane formation from birnessite, perhaps aided by oxidation-state differences. Transformation among birnessite phases of increasing surface area favors compositions with lower surface energy. These quantitative thermodynamic findings explain and support qualitative observations of phase-transformation patterns gathered from natural and synthetic manganese oxides. PMID:28130549