Interaction of cadmium with phosphate on goethite

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

Venema, P.; Hiemstra, T.; Riemsdijk, W.H. van

1997-08-01

Interactions between different ions are of importance in understanding chemical processes in natural systems. In this study simultaneous adsorption of phosphate and cadmium on goethite is studied in detail. The charge distribution (CD)-multisite complexation (MUSIC) model has been successful in describing extended data sets of cadmium adsorption and phosphate adsorption on goethite. In this study, the parameters of this model for these two data sets were combined to describe a new data set of simultaneous adsorption of cadmium and phosphate on goethite. Attention is focused on the surface speciation of cadmium. With the extra information that can be obtained frommore » the interaction experiments, the cadmium adsorption model is refined. For a perfect description of the data, the singly coordinated surface groups at the 110 face of goethite were assumed to form both monodentate and bidentate surface species with cadmium. The CD-MUSIC model is able to describe data sets of both simultaneous and single adsorption of cadmium and phosphate with the same parameters. The model calculations confirmed the idea that only singly coordinated surface groups are reactive for specific ion binding.« less

Mechanism of groundwater arsenic removal by goethite-coated mineral sand

NASA Astrophysics Data System (ADS)

Cashion, J. D.; Khan, S. A.; Patti, A. F.; Adeloju, S.; Gates, W. P.

2017-11-01

Skye sand (Vic, Australia) has been considered for arsenic removal from groundwater. Analysis showed that the silica sand is coated with poorly crystalline goethite, hematite and clay minerals. Mössbauer spectra taken following arsenic adsorption revealed changes in the recoilless fraction and relaxation behaviour of the goethite compared to the original state, showing that the goethite is the main active species.

The role of defects in Fe(II) – goethite electron transfer

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

Andrade de Notini, Luiza; Latta, Drew; Neumann, Anke

Despite accumulating experimental evidence for Fe(II)-Fe(III) oxide electron transfer, computational chemical calculations suggest that oxidation of sorbed Fe(II) is not energetically feasible unless defects are present. Here we used isotope specific 57Fe Mössbauer spectroscopy to investigate whether Fe(II)-goethite electron transfer is influenced by defects. Specifically, we heated the mineral to try to anneal the goethite surface and ground goethite to try to create defects. We found that heating goethite results in less oxidation of sorbed Fe(II) by goethite. When goethite was re-ground after heating, electron transfer was partially restored. X-ray absorption spectroscopy (XAS) and X-ray magnetic circular dichroism (XMCD) ofmore » heated and ground goethite confirm that heating and grinding alter the surface structure of the goethite. We propose that the heating process annealed the surface and decreased the number of sites where electron transfer could occur. Our experimental findings suggest that surface defects play an important role in Fe(II)-goethite electron transfer as suggested by computational calculations. Our finding that defects influence heterogeneous Fe(II)-goethite electron transfer has important implications for Fe(II) driven recrystallization of Fe oxides, as well as X and Y.« less

Immobilization of 99-Technetium (VII) by Fe(II)-Goethite and Limited Reoxidation

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

Um, Wooyong; Chang, Hyun-Shik; Icenhower, Jonathan P.

2011-05-04

Synthesized goethite was successfully used with addition of Fe(II) to sequester Tc present in both deionized water and simulated off-gas scrubber waste solutions. Pertechnetate concentration in solution decreased immediately when the pH was raised above 7 by addition of sodium hydroxide. Removal of Tc(VII) from solution occurred most likely as a result of heterogeneous surface-catalyzed reduction to Tc(IV) and subsequent co-precipitation onto the goethite. The final Tc-bearing solid was identified as goethite-dominated Fe(III)-(oxy)hydroxide based on XRD analysis, confirming the widespread observation of its characteristic acicular habit by TEM/SEM images. Analysis of the solid precipitate by XAFS showed that the dominantmore » oxidation state of Tc was Tc(IV) and was in octahedral coordination with Tc-O, Fe-O, and Tc-Fe bond distances that are consistent with direct substitution of Tc for Fe in the goethite structure. In some experiments the final Tc-goethite product was subsequently armored with additional layers of freshly precipitated goethite. Successful incorporation of Tc(IV) within the goethite mineral lattice and subsequent goethite armoring can limit re-oxidation of Tc(IV) and its subsequent release from Tc-goethite waste forms, even when the final product is placed in oxidizing environments that typify shallow waste burial facilities.« less

Interactions of calcium and fulvic acid at the goethite-water interface

NASA Astrophysics Data System (ADS)

Weng, Li Ping; Koopal, Luuk K.; Hiemstra, Tjisse; Meeussen, Johannes C. L.; Van Riemsdijk, Willem H.

2005-01-01

Interactions of calcium and fulvic acid (Strichen ) with the surface of goethite were studied with batch and titration experiments. The mutual influence of the interactions on the adsorption of fulvic acid, calcium ions and protons were examined. Adsorption of the fulvic acid to goethite decreased with increase in pH (pH range 3-11). Addition of Ca (1.0 mM) at intermediate and high pH significantly enhanced the adsorption of fulvic acid. Compared to the adsorption to pure goethite, the presence of fulvic acid enhanced the adsorption of Ca significantly. In comparison to the simple linear sum of Ca bound to fulvic acid and goethite, the interactions between goethite and fulvic acid led to a reduced adsorption of Ca at low pH and an enhanced adsorption at high pH. With the adsorption of fulvic acid, protons were released at low pH and coadsorbed at high pH. When Ca was added, fewer protons were released at low pH and fewer coadsorbed at high pH. The experimental results can be adequately described using a surface complexation model, the Ligand and Charge Distribution (LCD) model, in which the CD-MUSIC model for ion adsorption to mineral oxides and the NICA model for ion binding to humics are integrated. In the model calculations, adequate descriptions of the ternary system data (Ca-fulvic acid-goethite) were obtained with parameters derived from three binary systems (fulvic acid-goethite, Ca-goethite and Ca-fulvic acid) without further adjustment. The model calculations suggest that the interactions between Ca and fulvic acid at the surface of goethite are mainly due to the electrostatic effects.

Water vapor adsorption on goethite.

PubMed

Song, Xiaowei; Boily, Jean-François

2013-07-02

Goethite (α-FeOOH) is an important mineral contributing to processes of atmospheric and terrestrial importance. Their interactions with water vapor are particularly relevant in these contexts. In this work, molecular details of water vapor (0.0-19.0 Torr; 0-96% relative humidity at 25 °C) adsorption at surfaces of synthetic goethite nanoparticles reacted with and without HCl and NaCl were resolved using vibrational spectroscopy. This technique probed interactions between surface (hydr)oxo groups and liquid water-like films. Molecular dynamics showed that structures and orientations adopted by these waters are comparable to those adopted at the interface with liquid water. Particle surfaces reacted with HCl accumulated less water than acid-free surfaces due to disruptions in hydrogen bond networks by chemisorbed waters and chloride. Particles reacted with NaCl had lower loadings below ∼10 Torr water vapor but greater loadings above this value than salt-free surfaces. Water adsorption reactions were here affected by competitive hydration of coexisting salt-free surface regions, adsorbed chloride and sodium, as well as precipitated NaCl. Collectively, the findings presented in this study add further insight into the initial mechanisms of thin water film formation at goethite surfaces subjected to variations in water vapor pressure that are relevant to natural systems.

Susceptibility of Goethite to Fe2+-Catalyzed Recrystallization over Time.

PubMed

Joshi, Prachi; Fantle, Matthew S; Larese-Casanova, Philip; Gorski, Christopher A

2017-10-17

Recent work has shown that iron oxides, such as goethite and hematite, may recrystallize in the presence of aqueous Fe 2+ under anoxic conditions. This process, referred to as Fe 2+ -catalyzed recrystallization, can influence water quality by causing the incorporation/release of environmental contaminants and biological nutrients. Accounting for the effects of Fe 2+ -catalyzed recrystallization on water quality requires knowing the time scale over which recrystallization occurs. Here, we tested the hypothesis that nanoparticulate goethite becomes less susceptible to Fe 2+ -catalyzed recrystallization over time. We set up two batches of reactors in which 55 Fe 2+ tracer was added at two different time points and tracked the 55 Fe partitioning in the aqueous and goethite phases over 60 days. Less 55 Fe uptake occurred between 30 and 60 days than between 0 and 30 days, suggesting goethite recrystallization slowed with time. Fitting the data with a box model indicated that 17% of the goethite recrystallized after 30 days of reaction, and an additional 2% recrystallized between 30 and 60 days. The decreasing susceptibility of goethite to recrystallize as it reacted with aqueous Fe 2+ suggested that recrystallization is likely only an important process over short time scales.

Impact of environmental conditions on aggregation kinetics of hematite and goethite nanoparticles

NASA Astrophysics Data System (ADS)

Xu, Chen-yang; Deng, Kai-ying; Li, Jiu-yu; Xu, Ren-kou

2015-10-01

Hematite and goethite nanoparticles were used as model minerals to investigate their aggregation kinetics under soil environmental conditions in the present study. The hydrodynamic diameters of hematite and goethite nanoparticles were 34.4 and 66.3 nm, respectively. The positive surface charges and zeta potential values for goethite were higher than for hematite. The effective diameter for goethite was much larger than for hematite due to anisotropic sticking of needle-shaped goethite during aggregation. Moreover, the critical coagulation concentration (CCC) values of nanoparticles in solutions of NaNO3, NaCl, NaF, and Na2SO4 were 79.2, 75.0, 7.8, and 0.5 mM for hematite and they were 54.7, 62.6, 5.5, and 0.2 mM for goethite, respectively. The disparity of anions in inducing hematite or goethite aggregation lay in the differences in interfacial interactions. NO3 - and Cl- could decrease the zeta potential and enhance aggregation mainly through increasing ionic strength and compressing electric double layers of hematite and goethite nanoparticles. F- and SO4 2- highly destabilized the suspensions of nanoparticles mainly through specific adsorption and then neutralizing the positive surface charges of nanoparticles. Specific adsorption of cations could increase positive surface charges and stabilize hematite and goethite nanoparticles. The Hamaker constants of hematite and goethite nanoparticles were calculated to be 2.87 × 10-20 and 2.29 × 10-20 J-1, respectively. The predicted CCC values based on DLVO theory were consistent well with the experimentally determined CCC values in NaNO3, NaCl, NaF, and Na2SO4 systems, which demonstrated that DLVO theory could successfully predict the aggregation kinetics even when specific adsorption of ions occurred.

Spectral masking of goethite in abandoned mine drainage systems: implications for Mars

USGS Publications Warehouse

Cull, Selby; Cravotta, Charles A.; Klinges, Julia Grace; Weeks, Chloe

2014-01-01

Remote sensing studies of the surface of Mars use visible- to near-infrared (VNIR) spectroscopy to identify hydrated and hydroxylated minerals, which can be used to constrain past environmental conditions on the surface of Mars. However, due to differences in optical properties, some hydrated phases can mask others in VNIR spectra, complicating environmental interpretations. Here, we examine the role of masking in VNIR spectra of natural precipitates of ferrihydrite, schwertmannite, and goethite from abandoned mine drainage (AMD) systems in southeastern Pennsylvania. Mixtures of ferrihydrite, schwertmannite, and goethite were identified in four AMD sites by using X-ray diffractometry (XRD), and their XRD patterns compared to their VNIR spectra. We find that both ferrihydrite and schwertmannite can mask goethite in VNIR spectra of natural AMD precipitates. These findings suggest that care should be taken in interpreting environments on Mars where ferrihydrite, schwertmannite, or goethite are found, as the former two may be masking the latter. Additionally, our findings suggest that outcrops on Mars with both goethite and ferrihydrite/schwertmannite VNIR signatures may have high relative abundances of goethite, or the goethite may exist in a coarsely crystalline phase.

INFLUENCE OF PEAT ON FENTON OXIDATION

EPA Science Inventory

A diagnostic probe was used to estimate the activity of Fenton-derived hydroxyl radicals (@OH), reaction kinetics, and oxidation efficiency in batch suspensions comprised of silica sand, crushed goethite ("-FeOOH) ore, peat, and H2O2 (0.13 mM). A simple method of kinetic analysi...

Effect of humic acids on the adsorption of paraquat by goethite.

PubMed

Brigante, Maximiliano; Zanini, Graciela; Avena, Marcelo

2010-12-15

The adsorption of the herbicide paraquat (PQ(2+)) on goethite and on the binary system humic acid-goethite has been studied in batch experiments by performing adsorption isotherms under different conditions of pH, supporting electrolyte concentration and temperature. The results were completed with capillary electrophoresis (CE) in order to measure the binding isotherm between PQ(2+) and humic acid (HA) molecules in solution. PQ(2+) adsorption is negligible on the bare goethite surface but important on the HA-goethite adsorbent. In this last case, the adsorption increases by increasing pH and decreasing electrolyte concentration. There are no significant effects of temperature on the adsorption. The adsorption takes place by direct binding of PQ(2+) to adsorbed HA molecules leading to the formation of surface species of the type goethite-HA-PQ(2+). The results are consistent with a mechanism where PQ(2+) binds negatively charged groups of HA (carboxylates and phenolates) forming ionic pairs or outer-sphere complexes. Since goethite in nature usually contains adsorbed HA molecules, it may act as a good adsorbent for cationic herbicides. This will not only benefit the deactivation of the herbicides but also reduce their leaching and transport through groundwater. Copyright © 2010 Elsevier B.V. All rights reserved.

The adsorption of amino acids and cations onto goethite: a prebiotic chemistry experiment.

PubMed

Farias, Ana Paula S F; Carneiro, Cristine E A; de Batista Fonseca, Inês C; Zaia, Cássia T B V; Zaia, Dimas A M

2016-06-01

Few prebiotic chemistry experiments have assessed the adsorption of biomolecules by iron oxide-hydroxides. The present work investigated the effects of cations in artificial seawaters on the adsorption of Gly, α-Ala and β-Ala onto goethite, and vice versa. Goethite served to concentrate K and Mg cations from solution; these effects could have played important roles in peptide nucleoside formation. Goethite showed low adsorption of Gly and α-Ala. On the other hand, β-Ala (a non-protein amino acid) was highly adsorbed by goethite. Because Gly and α-Ala are the most common amino acids in living beings, and iron oxide-hydroxides are widespread on Earth, additional iron oxides should be studied. Increased ionic strength in artificial seawaters decreased the adsorption of amino acids by goethite. Because Na was highly abundant in the artificial seawater, it showed the highest effect on amino acid adsorption. β-Ala increased the adsorption of K and Ca by goethite, this effect could have been important for peptide synthesis.

Authigenic magnetite formation from goethite and hematite and chemical remanent magnetization acquisition

NASA Astrophysics Data System (ADS)

Till, J. L.; Nowaczyk, N.

2018-06-01

The iron oxyhydroxide goethite is unstable at elevated temperatures and can transform to magnetite under reducing conditions. In this study, various heating experiments were conducted to simulate Fe-mineral transformations during pyrogenic or burial diagenesis alteration in the presence of organic matter. Thermomagnetic measurements, capsule heating experiments and thermochemical remanence acquisition measurements were performed to determine the effect of organic carbon additions on samples containing synthetic microcrystalline goethite, microcrystalline hematite or nanocrystalline goethite. Changes in magnetic properties with heating were monitored to characterize the magnetic behaviour of secondary magnetite and hematite formed during the experiments. Authigenic magnetite formed in all samples containing organic C, while goethite heated without organic C altered to poorly crystalline pseudomorphic hematite. The concentration of organic matter was found to have little influence on the rate or extent of reaction or on the characteristics of the secondary phases. Authigenic magnetite formed from microcrystalline goethite and hematite dominantly behaves as interacting single-domain particles, while nanophase goethite alters to a mixture of small single-domain and superparamagnetic magnetite. Authigenic magnetite and hematite both acquire a stable thermochemical remanence on heating to temperatures between 350 and 600 °C, although the remanence intensity acquired below 500 °C is much weaker than that at higher temperatures. Reductive transformation of fine-grained goethite or hematite is therefore a potential pathway for the production of authigenic magnetite and the generation of stable chemical remanence that may be responsible for remagnetization in organic-matter-bearing sedimentary rocks.

On the anomalous adsorption of [Pd(edta)]2- at the water/Goethite interface: spectroscopic evidence for two types of surface complexes.

PubMed

Kaplun, Marina; Nordin, Agneta; Persson, Per

2008-01-15

The structure of palladium(II) ethylenediaminetetraacetate (edta) in aqueous solutions and its adsorption on the surface of goethite (alpha-FeOOH) were studied using extended X-ray absorption fine structure spectroscopy and attenuated total reflection Fourier transform infrared spectroscopy. The obtained results show that in aqueous solutions, Pd-edta exists as a 1:1 complex, [Pd(edta)]2-, with edta acting as a quadridentate ligand. On the surface of goethite, [Pd(edta)]2- forms two different types of complexes over a pH range of 3.40-8.12. At pH < 5, [Pd(edta)]2- adsorbs as an outer-sphere species with possible hydrogen bonding. At higher pH values, the formation of inner-sphere complexes of the cation-type sets in after a cleavage of one glycinate ring and the formation of an (edta)Pd-O-Fe linkage.

Synergistic effect of reductive and ligand-promoted dissolution of goethite.

PubMed

Wang, Zimeng; Schenkeveld, Walter D C; Kraemer, Stephan M; Giammar, Daniel E

2015-06-16

Ligand-promoted dissolution and reductive dissolution of iron (hydr)oxide minerals control the bioavailability of iron in many environmental systems and have been recognized as biological iron acquisition strategies. This study investigated the potential synergism between ligands (desferrioxamine B (DFOB) or N,N'-Di(2-hydroxybenzyl)ethylenediamine-N,N'-diacetic acid (HBED)) and a reductant (ascorbate) in goethite dissolution. Batch experiments were performed at pH 6 with ligand or reductant alone and in combination, and under both oxic and anoxic conditions. Goethite dissolution in the presence of reductant or ligand alone followed classic surface-controlled dissolution kinetics. Ascorbate alone does not promote goethite dissolution under oxic conditions due to rapid reoxidation of Fe(II). The rate coefficients for goethite dissolution by ligands are closely correlated with the stability constants of the aqueous Fe(III)-ligand complexes. A synergistic effect of DFOB and ascorbate on the rate of goethite dissolution was observed (total rates greater than the sum of the individual rates), and this effect was most pronounced under oxic conditions. For HBED, macroscopically the synergistic effect was hidden due to the inhibitory effect of ascorbate on HBED adsorption. After accounting for the concentrations of adsorbed ascorbate and HBED, a synergistic effect could still be identified. The potential synergism between ligand and reductant for iron (hydr)oxide dissolution may have important implications for iron bioavailability in soil environments.

Effect of Natural Organic Matter on Plutonium Sorption to Goethite

DOE PAGES

Conroy, Nathan A.; Zavarin, Mavrik; Kersting, Annie B.; ...

2016-11-21

For this research, the effect of citric acid (CA), desferrioxamine B (DFOB), fulvic acid (FA), and humic acid (HA) on plutonium (Pu) sorption to goethite was studied as a function of organic carbon concentration and pH using batch sorption experiments at 5 mg C·L –1 and 50 mg C·L –1 natural organic matter (NOM), 10 –9–10 –10 M 238Pu, and 0.1 g·L –1 goethite concentrations, at pH 3, 5, 7, and 9. Low sorption of ligands coupled with strong Pu complexation decreased Pu sorption at pH 5 and 7, relative to a ligand-free system. Conversely, CA, FA, and HA increasedmore » Pu sorption to goethite at pH 3, suggesting ternary complex formation or, in the case of humic acid, incorporation into HA aggregates. Mechanisms for ternary complex formation were characterized by Fourier transform infrared spectroscopy in the absence of Pu. CA and FA demonstrated clear surface interactions at pH 3, HA appeared unchanged suggesting HA aggregates had formed, and no DFOB interactions were observed. Plutonium sorption decreased in the presence of DFOB (relative to a ligand free system) at all pH values examined. Thus, DFOB does not appear to facilitate formation of ternary Pu-DFOB-goethite complexes. At pH 9, Pu sorption in the presence of all NOM increased relative to pH 5 and 7; speciation models attributed this to Pu(IV) hydrolysis competing with ligand complexation, increasing sorption. In conclusion, the results indicate that in simple Pu-NOM-goethite ternary batch systems, NOM will decrease Pu sorption to goethite at all but particularly low pH conditions.« less

Effect of Natural Organic Matter on Plutonium Sorption to Goethite

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

Conroy, Nathan A.; Zavarin, Mavrik; Kersting, Annie B.

For this research, the effect of citric acid (CA), desferrioxamine B (DFOB), fulvic acid (FA), and humic acid (HA) on plutonium (Pu) sorption to goethite was studied as a function of organic carbon concentration and pH using batch sorption experiments at 5 mg C·L –1 and 50 mg C·L –1 natural organic matter (NOM), 10 –9–10 –10 M 238Pu, and 0.1 g·L –1 goethite concentrations, at pH 3, 5, 7, and 9. Low sorption of ligands coupled with strong Pu complexation decreased Pu sorption at pH 5 and 7, relative to a ligand-free system. Conversely, CA, FA, and HA increasedmore » Pu sorption to goethite at pH 3, suggesting ternary complex formation or, in the case of humic acid, incorporation into HA aggregates. Mechanisms for ternary complex formation were characterized by Fourier transform infrared spectroscopy in the absence of Pu. CA and FA demonstrated clear surface interactions at pH 3, HA appeared unchanged suggesting HA aggregates had formed, and no DFOB interactions were observed. Plutonium sorption decreased in the presence of DFOB (relative to a ligand free system) at all pH values examined. Thus, DFOB does not appear to facilitate formation of ternary Pu-DFOB-goethite complexes. At pH 9, Pu sorption in the presence of all NOM increased relative to pH 5 and 7; speciation models attributed this to Pu(IV) hydrolysis competing with ligand complexation, increasing sorption. In conclusion, the results indicate that in simple Pu-NOM-goethite ternary batch systems, NOM will decrease Pu sorption to goethite at all but particularly low pH conditions.« less

Variability in goethite surface site density: evidence from proton and carbonate sorption.

PubMed

Villalobos, Mario; Trotz, Maya A; Leckie, James O

2003-12-15

Goethite is a representative iron oxide in natural environments due to its abundance and thermodynamic stability and may be responsible for many surface-mediated processes, including ion retention and mobility in aqueous settings. A large variability in morphologies and specific surface areas of goethite crystals exists but little work has been done to compare surface reactivity between them. The present work offers experimental evidence for the existence of an inverse relationship between sorption capacity for protons and carbonate ions and specific surface area of goethite for three synthetic goethite preparations spanning surface area differences by a factor of 2. An explanation for this was found by assuming a variable reactive site density between preparations in direct relationship to their sorption capacity based on congruency of carbonate sorption computed on a per-site basis. Previous evidence of maximum sorption capacities supports this explanation, and site density ratios between the goethites studied here were obtained. Triple layer surface complexation modeling was successful in describing adsorption data for all goethite preparations using equal stoichiometries. A new formulation of standard state for activities of surface species based on a 1.0 mole fraction of sites on the solid allowed transformation of the conventional molar concentration-based affinity constants to values based on site occupancy. In this fashion, by applying the appropriate site density ratios, a single set of affinity constant values was found that described accurately the adsorption data for all preparations.

(U-Th)/He geochronology of goethite and the origin and evolution of cangas

NASA Astrophysics Data System (ADS)

Monteiro, Hevelyn S.; Vasconcelos, Paulo M.; Farley, Kenneth A.; Spier, Carlos A.; Mello, Claudio L.

2014-04-01

(U-Th)/He geochronology of 147 grains of goethite cements extracted from ferruginous duricrusts (cangas) developed on banded iron-formations from the Quadrilátero Ferrífero region, Minas Gerais, Brazil, records a history of protracted mineral dissolution-reprecipitation that started at ca. 48.1 ± 4.8 Ma and continues intermittently until the Present. A large majority of the samples (more than 30%) are younger than 2 Ma, revealing active mineral dissolution-reprecipitation in the recent past. Within cangas, goethite cements are younger near the surface and become progressively older towards the bottom of the weathering profile, indicating that iron is more effectively cycled in the parts of the weathering profile more strongly affected by biogenic activity. (U-Th)/He geochronology of 14 goethite grains from saprolites in the same profiles yield results ranging from 55.3 ± 5.5 to 25.7 ± 2.6 Ma. For a single weathering profile, goethite cements from cangas are invariably younger than goethite grains from the underlying saprolite, indicating that the duricrust and the saprolite behave as independent and separate systems responding to different environmental controls. Thorium shows conservative behaviour during goethite dissolution-reprecipitation, and it is enriched towards the surface of the weathering profile. Uranium, on the other hand, is preferentially leached from the surface into the saprolite or out of the weathering profile. Recurrent goethite dissolution-reprecipitation lends great textural complexities to cangas, but it is also responsible for its capacity to reheal when physically disrupted. This self-healing property accounts for canga’s role in armoring banded iron-formation landscapes.

Goethite promoted biodegradation of 2,4-dinitrophenol under nitrate reduction condition.

PubMed

Tang, Ting; Yue, Zhengbo; Wang, Jin; Chen, Tianhu; Qing, Chengsong

2018-02-05

Iron oxide may interact with other pollutants in the aquatic environments and further influence their toxicity, transport and fate. The current study was conducted to investigate the biodegradation of 2,4-dinitrophenol (2,4-DNP) in the presence of iron oxide of goethite under anoxic condition using nitrate as the electron acceptor. Experiment results showed that the degradation rate of 2,4-DNP was improved by goethite. High performance liquid chromatography-mass spectra analysis results showed that goethite promoted degradation and transformation of 2,4-diaminophenol and 2-amino-4-nitrophenol (2-nitro-4-aminophenol). Microbial community analysis results showed that the abundance of Actinobacteria, which have the potential ability to degrade PAHs, was increased when goethite was available. This might partially explain the higher degradation of 2,4-DNP. Furthermore, another bacterium of Desulfotomaculum reducens which could reduce soluble Fe(III) and nitrate was also increased. Results further confirmed that nanomaterials in the aquatic environment will influence the microbial community and further change the transformation process of toxic pollutants. Copyright © 2017 Elsevier B.V. All rights reserved.

Synthesis of goethite in solutions of artificial seawater and amino acids: a prebiotic chemistry study

NASA Astrophysics Data System (ADS)

Carneiro, Cristine E. A.; Ivashita, Flávio F.; de Souza, Ivan Granemann; de Souza, Cláudio M. D.; Paesano, Andrea; da Costa, Antonio C. S.; di Mauro, Eduardo; de Santana, Henrique; Zaia, Cássia T. B. V.; Zaia, Dimas A. M.

2013-04-01

This study investigated the synthesis of goethite under conditions resembling those of the prebiotic Earth. The artificial seawater used contains all the major elements as well as amino acids (α-Ala, β-Ala, Gly, Cys, AIB) that could be found on the prebiotic Earth. The spectroscopic methods (FT-IR, EPR, Raman), scanning electron microscopy (SEM) and X-ray diffraction showed that in any condition Gly and Cys favoured the formation of goethite, artificial seawater plus β-Ala and distilled water plus AIB favoured the formation of hematite and for the other synthesis a mixture of goethite and hematite were obtained. Thus in general no protein amino acids (β-Ala, AIB) favoured the formation of hematite. As shown by surface enhanced Raman spectroscopy (SERS) spectra the interaction between Cys and Fe3+ of goethite is very complex, involving decomposition of Cys producing sulphur, as well as interaction of carboxylic group with Fe3+. SERS spectra also showed that amino/CN and C-CH3 groups of α-Ala are interacting with Fe3+ of goethite. For the other samples the shifting of several bands was observed. However, it was not possible to say which amino acid groups are interacting with Fe3+. The pH at point of zero charge of goethites increased with artificial seawater and decreased with amino acids. SEM images showed when only goethite was synthesized the images of the samples were acicular and when only hematite was synthesized the images of the samples were spherical. SEM images for the synthesis of goethite with Cys were spherical crystal aggregates with radiating acicular crystals. The highest resonance line intensities were obtained for the samples where only hematite was obtained. Electron paramagnetic resonance (EPR) and Mössbauer spectra showed for the synthesis of goethite with artificial seawater an isomorphic substitution of iron by seawater cations. Mössbauer spectra also showed that for the synthesis goethite in distilled water plus Gly only goethite was

Rate constants and mechanisms for the crystallization of Al nano-goethite under environmentally relevant conditions

NASA Astrophysics Data System (ADS)

Bazilevskaya, Ekaterina; Archibald, Douglas D.; Martínez, Carmen Enid

2012-07-01

Mobile inorganic and organic nanocolloidal particles originate-from and interact-with bulk solid phases in soil and sediment environments, and as such, they contribute to the dynamic properties of environmental systems. In particular, ferrihydrite and (nano)goethite are the most abundant of nanocolloidal Fe oxy(hydr)oxides in these environments. We therefore investigated the ferrihydrite to goethite phase transformation using experimental reaction conditions that mimicked environmental conditions where the formation of nanocolloidal Fe oxy(hydr)oxides may occur: slow titration of dilute solutions to pH 5 at 25 °C with and without 2 mol% Al. Subsequently, the rate constants from 54-d nano-goethite aging/crystallization experiments at 50 °C were determined using aliquots pulled for vibrational spectroscopy (including multivariate curve resolution, MCR, analyses of infrared spectra) and synchrotron-based X-ray diffraction (XRD). We also present a mechanistic model that accounts for the nano-goethite crystallization observed by the aforementioned techniques, and particle structural characteristics observed by dynamic light scattering (DLS) and transmission electron microscopy (TEM). In contrast to the common assumption that metastable ferrihydrite precipitates first, before it transforms to goethite, the presence of characteristic infrared bands in freshly synthesized nanoparticle suspensions indicate goethite can precipitate directly from solution under environmentally relevant conditions: low Fe concentration, ambient temperature, and pH maintained at 5. However, the presence of 2 mol% Al prevented direct goethite precipitation. Rate constants obtained by fitting the contributions from the MCR-derived goethite-like component to the OH-stretching region were (7.4 ± 1.1) × 10-7 s-1 for 0% Al and (4.2 ± 0.4) × 10-7 s-1 for 2 mol% Al suspensions. Rate constants derived from intensities of OH-bending infrared vibrations (795 and 895 cm-1) showed similar values

Goethite surface reactivity: a macroscopic investigation unifying proton, chromate, carbonate, and lead(II) adsorption.

PubMed

Villalobos, Mario; Pérez-Gallegos, Ayax

2008-10-15

The goethite surface structure has been extensively studied, but no convincing quantitative description of its highly variable surface reactivity as inversely related to its specific surface area (SSA) has been found. The present study adds experimental evidence and provides a unified macroscopic explanation to this anomalous behavior from differences in average adsorption capacities, and not in average adsorption affinities. We investigated the chromate anion and lead(II) cation adsorption behavior onto three different goethites with SSA varying from 50 to 94 m(2)/g, and analyzed an extensive set of published anion adsorption and proton charging data for variable SSA goethites. Maximum chromate adsorption was found to occupy on average from 3.1 to 9.7 sites/nm(2), inversely related to SSA. Congruency of oxyanion and Pb(II) adsorption behavior based on fractional site occupancy using these values, and a site density analysis suggest that: (i) ion binding occurs to singly and doubly coordinated sites, (ii) proton binding occurs to singly and triply coordinated sites (ranging from 6.2 to 8 total sites/nm(2), in most cases), and (iii) a predominance of (210) and/or (010) faces explains the high reactivity of low SSA goethites. The results imply that the macroscopic goethite adsorption behavior may be predicted without a need to investigate extensive structural details of each specific goethite of interest.

Colloidal behavior of goethite nanoparticles modified with humic acid and implications for aquifer reclamation

NASA Astrophysics Data System (ADS)

Tiraferri, Alberto; Saldarriaga Hernandez, Laura Andrea; Bianco, Carlo; Tosco, Tiziana; Sethi, Rajandrea

2017-03-01

Nanosized colloids of iron oxide adsorb heavy metals, enhance the biodegradation of contaminants, and represent a promising technology to clean up contaminated aquifers. Goethite particles for aquifer reclamation were recently synthesized with a coating of humic acids to reduce aggregation. This study investigates the stability and the mobility in porous media of this material as a function of aqueous chemistry, and it identifies the best practices to maximize the efficacy of the related remediation. Humic acid-coated nanogoethite (hydrodynamic diameter ˜90 nm) displays high stability in solutions of NaCl, consistent with effective electrosteric stabilization. However, particle aggregation is fast when calcium is present and, to a lesser extent, also in the presence of magnesium. This result is rationalized with complexation phenomena related to the interaction of divalent cations with humic acid, inducing rapid flocculation and sedimentation of the suspensions. The calcium dose, i.e., the amount of calcium ions with respect to solids in the dispersion, is the parameter governing stability. Therefore, more concentrated slurries may be more stable and mobile in the subsurface than dispersions of low particle concentration. Particle concentration during field injection should be thus chosen based on concentration and proportion of divalent cations in groundwater.

Facet-Dependent Oxidative Goethite Growth As a Function of Aqueous Solution Conditions.

PubMed

Strehlau, Jennifer H; Stemig, Melissa S; Penn, R Lee; Arnold, William A

2016-10-04

Nitroaromatic compounds are groundwater pollutants that can be degraded through reactions with Fe(II) adsorbed on iron oxide nanoparticles, although little is known about the evolving reactivity of the minerals with continuous pollutant exposure. In this work, Fe(II)/goethite reactivity toward 4-chloronitrobenzene (4-ClNB) as a function of pH, organic matter presence, and reactant concentrations was explored using sequential-spike batch reactors. Reaction rate constants were smaller with lower pH, introduction of organic matter, and diluted reactant concentrations as compared to a reference condition. Reaction rate constants did not change with the number of 4-ClNB spikes for all reaction conditions. Under all conditions, oxidative goethite growth was demonstrated through X-ray diffraction, magnetic characterization, and transmission electron microscopy. Nonparametric statistics were applied to compare histograms of lengths and widths of goethite nanoparticles as a function of varied solution conditions. The conditions that slowed the reaction also resulted in statistically shorter and wider particles than for the faster reactions. Additionally, added organic matter interfered with particle growth on the favorable {021} faces to a greater extent, with statistically reduced rate of growth on the tip facets and increased rate of growth on the side facets. These data demonstrate that oxidative growth of goethite in aqueous systems is dependent on major groundwater variables, such as pH and the presence of organic matter, which could lead to the evolving reactivity of goethite particles in natural environments.

Low-temperature, non-stoichiometric oxygen isotope exchange coupled to Fe(II)-goethite interactions

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

Frierdich, Andrew J.; Beard, Brian L.; Rosso, Kevin M.

2015-07-01

The oxygen isotope composition of natural iron oxide minerals has been widely used as a paleoclimate proxy. Interpretation of their stable isotope compositions, however, requires accurate knowledge of isotopic fractionation factors and an understanding of their isotopic exchange kinetics, the latter of which informs us how diagenetic processes may alter their isotopic compositions. Prior work has demonstrated that crystalline iron oxides do not significantly exchange oxygen isotopes with pure water at low temperature, which has restricted studies of isotopic fractionation factors to precipitation experiments or theoretical calculations. Using a double three-isotope method (¹⁸O-¹⁷O-¹⁶O and ⁵⁷Fe-⁵⁶Fe-⁵⁴Fe) we compare O and Femore » isotope exchange kinetics, and demonstrate, for the first time, that O isotope exchange between structural O in crystalline goethite and water occurs in the presence of aqueous Fe(II) (Fe(II) aq) at ambient temperature (i.e., 22–50 °C). The three-isotope method was used to extrapolate partial exchange results to infer the equilibrium, mass-dependent isotope fractionations between goethite and water. In addition, this was combined with a reversal approach to equilibrium by reacting goethite in two unique waters that vary in composition by about 16‰ in ¹⁸O/¹⁶O ratios. Our results show that interactions between Fe(II) aq and goethite catalyzes O isotope exchange between the mineral and bulk fluid; no exchange (within error) is observed when goethite is suspended in ¹⁷O-enriched water in the absence of Fe(II) aq. In contrast, Fe(II)-catalyzed O isotope exchange is accompanied by significant changes in ¹⁸O/¹⁶O ratios. Despite significant O exchange, however, we observed disproportionate amounts of Fe versus O exchange, where Fe isotope exchange in goethite was roughly three times that of O. This disparity provides novel insight into the reactivity of oxide minerals in aqueous solutions, but presents a

Fe(II)-induced transformation from ferrihydrite to lepidocrocite and goethite

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

Liu Hui; Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan 030001 China; Li Ping

2007-07-15

The transformation of Fe(II)-adsorbed ferrihydrite was studied. Data tracking the formation of products as a function of pH, temperature and time is presented. The results indicate that trace of Fe(II) adsorbed on ferrihydrite can accelerate its transformation obviously. The products are lepidocrocite and/or goethite and/or hematite, which is different from those without Fe(II). That is, Fe(II) not only accelerates the transformation of ferrihydrite but also leads to the formation of lepidocrocite by a new path. The behavior of Fe(II) is shown in two aspects-catalytic dissolution-reprecipitation and catalytic solid-state transformation. The results indicate that a high temperature and a high pH(inmore » the range from 5 to 9) are favorable to solid-state transformation and the formation of hematite, while a low temperature and a low pH are favorable to dissolution-reprecipitation mechanism and the formation of lepidocrocite. Special attentions were given to the formation mechanism of lepidocrocite and goethite. - Graphical abstract: Fe(II)-adsorbed ferrihydrite can rapidly transform into lepidocrocite or/and goethite or/and hematite. Which product dominates depends on the transformation conditions of ferrihydrite such as temperature, pH, reaction time, etc. In the current system, there exist two transformation mechanisms. One is dissolution/reprecipitation and the other is solid-state transformation. The transformation mechanisms from Fe(II)-adsorbed ferrihydrite to lepidocrocite and goethite were investigated.« less

Water adsorption on goethite: Application of multilayer adsorption models

NASA Astrophysics Data System (ADS)

Hatch, C. D.; Tumminello, R.; Meredith, R.

2016-12-01

Adsorbed water on the surface of atmospheric mineral dust has recently been shown to significantly affect the ability of mineral dust aerosol to act as cloud condensation nuclei. We have studied water adsorption as a function of relative humidity (RH) on goethite (α-FeO(OH)), a common component of atmospheric mineral dust. The goethite surface area and particle size was determined using BET analysis and with N2 as an adsorbate and scanning electron microscopy, respectively. Water adsorption on the sample was monitored using horizontal attenuated total reflectance Fourier transform infrared (HATR-FTIR) spectroscopy equipped with a flow cell. Water content was determined using Beer's law and the optical constants for bulk water. The results were analyzed using Type II adsorption isotherms to model multilayer adsorption, including BET (Brunauer, Emmet and Teller), FHH (Frenkel, Halsey and Hill) and Freundlich. BET fits to experimental data provide parameters of monolayer coverage, while the FHH and Freundlich isotherms provide insights into multilayer adsorption mechanisms. Results indicate that goethite contains 5% H2O by mass at 50% RH, which increases to 12% by mass at 90% RH. Adsorption parameters and experimental results will be presented.

Mineral transformations associated with goethite reduction by Methanosarcina barkeri

USGS Publications Warehouse

Liu, D.; Wang, Hongfang; Dong, H.; Qiu, X.; Dong, X.; Cravotta, C.A.

2011-01-01

To investigate the interaction between methanogens and iron-containing minerals in anoxic environments, we conducted batch culture experiments with Methanosarcina barkeri in a phosphate-buffered basal medium (PBBM) to bioreduce structural Fe(III) in goethite with hydrogen as the sole substrate. Fe(II) and methane concentrations were monitored over the course of the bioreduction experiments with wet chemistry and gas chromatography, respectively. Subsequent mineralogical changes were characterized with X-ray diffraction (XRD) and scanning electron microscopy (SEM). In the presence of an electron shuttle anthraquinone-2,6-disulfonate (AQDS), 30% Fe(III) in goethite (weight basis) was reduced to Fe(II). In contrast, only 2% Fe(III) (weight basis) was bioreduced in the absence of AQDS. Most of the bioproduced Fe(II) was incorporated into secondary minerals including dufr??nite and vivianite. Our data implied a dufr??nite-vivianite transformation mechanism where a metastable dufr??nite transformed to a more stable vivianite over extended time in anaerobic conditions. Methanogenesis was greatly inhibited by bioreduction of goethite Fe(III). These results have important implications for the methane flux associated with Fe(III) bioreduction and ferrous iron mineral precipitation in anaerobic soils and sediments. ?? 2011 Elsevier B.V.

Dispersions of Goethite Nanorods in Aprotic Polar Solvents

PubMed Central

Coursault, Delphine; Dozov, Ivan; Nobili, Maurizio; Dupont, Laurent; Chanéac, Corinne

2017-01-01

Colloidal suspensions of anisotropic nanoparticles can spontaneously self-organize in liquid-crystalline phases beyond some concentration threshold. These phases often respond to electric and magnetic fields. At lower concentrations, usual isotropic liquids are observed but they can display very strong Kerr and Cotton-Mouton effects (i.e., field-induced particle orientation). For many examples of these colloidal suspensions, the solvent is water, which hinders most electro-optic applications. Here, for goethite (α-FeOOH) nanorod dispersions, we show that water can be replaced by polar aprotic solvents, such as N-methyl-2-pyrrolidone (NMP) and dimethylsulfoxide (DMSO), without loss of colloidal stability. By polarized-light microscopy, small-angle X-ray scattering and electro-optic measurements, we found that the nematic phase, with its field-response properties, is retained. Moreover, a strong Kerr effect was also observed with isotropic goethite suspensions in these polar aprotic solvents. Furthermore, we found no significant difference in the behavior of both the nematic and isotropic phases between the aqueous and non-aqueous dispersions. Our work shows that goethite nanorod suspensions in polar aprotic solvents, suitable for electro-optic applications, can easily be produced and that they keep all their outstanding properties. It also suggests that this solvent replacement method could be extended to the aqueous colloidal suspensions of other kinds of charged anisotropic nanoparticles. PMID:29039797

Gallium isotope fractionation during Ga adsorption on calcite and goethite

NASA Astrophysics Data System (ADS)

Yuan, Wei; Saldi, Giuseppe D.; Chen, JiuBin; Vetuschi Zuccolini, Marino; Birck, Jean-Louis; Liu, Yujie; Schott, Jacques

2018-02-01

Gallium (Ga) isotopic fractionation during its adsorption on calcite and goethite was investigated at 20 °C as a function of the solution pH, Ga aqueous concentration and speciation, and the solid to solution ratio. In all experiments Ga was found to be enriched in light isotopes at the solid surface with isotope fractionation △71Gasolid-solution up to -1.27‰ and -0.89‰ for calcite and goethite, respectively. Comparison of Ga isotopic data of this study with predictions for 'closed system' equilibrium and 'Rayleigh fractionation' models indicates that the experimental data are consistent with a 'closed system' equilibrium exchange between the fluid and the solid. The results of this study can be interpreted based on Ga aqueous speciation and the structure of Ga complexes formed at the solid surfaces. For calcite, Ga isotope fractionation is mainly triggered by increased Ga coordination and Ga-O bond length, which vary respectively from 4 and 1.84 Å in Ga(OH)4- to 6 and 1.94 Å in the >Ca-O-GaOH(OH2)4+ surface complex. For goethite, despite the formation of Ga hexa-coordinated >FeOGa(OH)20 surface complexes (Ga-O distances of 1.96-1.98 Å) both at acid and alkaline pH, a similar extent of isotope fractionation was found at acid and alkaline pH, suggesting that Ga(OH)4- is preferentially adsorbed on goethite for all investigated pH conditions. In addition, the observed decrease of Ga isotope fractionation magnitude observed with increasing Ga surface coverage for both calcite and goethite is likely related to the formation of Ga surface polymers and/or hydroxides with reduced Ga-O distances. This first study of Ga isotope fractionation during solid-fluid interactions suggests that the adsorption of Ga by oxides, carbonates or clay minerals could yield significant Ga isotope fractionation between secondary minerals and surficial fluids including seawater. Ga isotopes thus should help to better characterize the surficial biogeochemical cycles of gallium and its

Protonation of Different Goethite Surfaces - Unified Models for NaNO3 and NaCl Media.

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

Lutzenkirchen, Johannes; Boily, Jean F.; Gunneriusson, Lars

2008-01-01

Acid-base titration data for two goethites samples in sodium nitrate and sodium chloride media are discussed. The data are modelled based on various surface complexation models in the framework of the MUlti SIte Complexation (MUSIC) model. Various assumptions with respect to the goethite morphology are considered in determining the site density of the surface functional groups. The results from the various model applications are not statistically significant in terms of goodness of fit. More importantly, various published assumptions with respect to the goethite morphology (i.e. the contributions of different crystal planes and their repercussions on the “overall” site densities ofmore » the various surface functional groups) do not significantly affect the final model parameters. The simultaneous fit of the chloride and nitrate data results in electrolyte binding constants, which are applicable over a wide range of electrolyte concentrations including mixtures of chloride and nitrate. Model parameters for the high surface area goethite sample are in excellent agreement with parameters that were independently obtained by another group on different goethite titration data sets.« less

Technetium incorporation into goethite (α-FeOOH): An atomic-scale investigation

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

Smith, Frances N.; Taylor, Christopher D.; Um, Wooyong

2015-11-17

During the processing of low-activity radioactive waste to generate solid waste forms (e.g., glass), technetium-99 (Tc) is of concern because of its volatility. A variety of materials are under consideration to capture Tc from waste streams, including the iron oxyhydroxide, goethite (α-FeOOH), which was experimentally shown to sequester Tc(IV). This material could ultimately be incorporated into glass or other low-temperature waste form matrices. However, questions remain regarding the incorporation mechanism for Tc(IV) in goethite, which has implications for predicting the long-term stability of Tc in waste forms under changing conditions. Here, quantum-mechanical calculations were used to evaluate the energy ofmore » five different charge-compensated Tc(IV) incorporation scenarios in goethite. The two most stable incorporation mechanisms involve direct substitution of Tc(IV) onto Fe(III) lattice sites and charge balancing either by removing one nearby H+ (i.e., within 5 Å), or by creating an Fe(III) vacancy when substituting 3 Tc(IV) for 4 Fe(III), with the former being preferred over the latter relative to gas-phase ions. When corrections for hydrated references phases are applied, the Fe(III)-vacancy mechanism becomes more energetically competitive. Calculated incorporation energies and optimized bond-lengths are presented. Proton movement is observed to satisfy under-coordinated bonds surrounding vacancies in the goethite structure.« less

Periodic density functional theory calculations of bulk and the (010) surface of goethite

PubMed Central

Kubicki, James D; Paul, Kristian W; Sparks, Donald L

2008-01-01

Background Goethite is a common and reactive mineral in the environment. The transport of contaminants and anaerobic respiration of microbes are significantly affected by adsorption and reduction reactions involving goethite. An understanding of the mineral-water interface of goethite is critical for determining the molecular-scale mechanisms of adsorption and reduction reactions. In this study, periodic density functional theory (DFT) calculations were performed on the mineral goethite and its (010) surface, using the Vienna Ab Initio Simulation Package (VASP). Results Calculations of the bulk mineral structure accurately reproduced the observed crystal structure and vibrational frequencies, suggesting that this computational methodology was suitable for modeling the goethite-water interface. Energy-minimized structures of bare, hydrated (one H2O layer) and solvated (three H2O layers) (010) surfaces were calculated for 1 × 1 and 3 × 3 unit cell slabs. A good correlation between the calculated and observed vibrational frequencies was found for the 1 × 1 solvated surface. However, differences between the 1 × 1 and 3 × 3 slab calculations indicated that larger models may be necessary to simulate the relaxation of water at the interface. Comparison of two hydrated surfaces with molecularly and dissociatively adsorbed H2O showed a significantly lower potential energy for the former. Conclusion Surface Fe-O and (Fe)O-H bond lengths are reported that may be useful in surface complexation models (SCM) of the goethite (010) surface. These bond lengths were found to change significantly as a function of solvation (i.e., addition of two extra H2O layers above the surface), indicating that this parameter should be carefully considered in future SCM studies of metal oxide-water interfaces. PMID:18477389

Influence of alloying elements in rust formed on low alloyed steels. A study by x-ray diffraction and Mössbauer spectroscopy

NASA Astrophysics Data System (ADS)

Haces, C.; Furet, N. R.; Muleshkova, L.

1991-11-01

In this research, three Bulgarian steels were employed, one carbon (08KP) and other two low alloyed (KBC) and (KORAT). These three steels were exposed on a test site affected with industrial pollution in the Cuban climate, for a period of one, two and three years. The phase composition obtained by means of XRD and Mössbauer spectroscopy is mainly a mixture of Goethite (α-FeOOH) and Lepidocrocite (γ-FEOOH) in the three steels. The mean width of the Goethite reflexions, as determined in the diffractograms, is increased in the case of the low alloyed steels, while in Mössbauer spectra two types of magnetic arrangement for Goethite appear, one antiferromagnetic (sextet) and the other superparamagnetic (doublet). This behaviour is due to the effect of the small particle size and the presence of alloying elements in the structure. In this paper, the values of the areas of both effects are discussed from the greater formation of superparamagnetic Goethite in the KORAT steel which exibits the lowest corrosion rate.

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.

Red mud carbonation using carbon dioxide: Effects of carbonate and calcium ions on goethite surface properties and settling.

PubMed

Liang, Gaojie; Chen, Wenmi; Nguyen, Anh V; Nguyen, Tuan A H

2018-05-01

Carbonation using CO 2 appears as an attractive solution for disposing of red mud suspensions, an aluminum industry hazardous waste since it also offers an option for CO 2 sequestration. Here we report the novel findings that CO 3 2- together with Ca 2+ can significantly affect the surface properties and settling of goethite, a major component of red mud. Specifically, their effects on the goethite surface chemistry, colloidal interaction forces and settling in alkaline solutions are investigated. The surface potential becomes more negative by the formation of carbonate inner-sphere complexes on goethite surface. It is consistent with the strong repulsion, decreased particle size and settling velocity with increased carbonate concentrations as measured by atomic force microscopy, particle size analysis, and particle settling. Adding Ca 2+ that forms outer-sphere complexes with pre-adsorbed carbonate changes goethite surface charge negligibly. Changing repulsion to the attraction between goethite surfaces by increasing calcium dosage indicates the surface bridging, in accordance with the increased settling velocity. The adverse effect of carbonate on goethite flocculation is probably due to its specific chemisorption and competition with flocculants. By forming outer-sphere complexes together with the flocculant-calcium bridging effect, calcium ions can eliminate the negative influence of carbonate and improve the flocculation of goethite particles. These findings contribute to a better understanding of goethite particle interaction with salt ions and flocculants in controlling the particle behavior in the handling processes, including the red mud carbonation. Copyright © 2018 Elsevier Inc. All rights reserved.

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.

Control of Earth-like magnetic fields on the transformation of ferrihydrite to hematite and goethite

PubMed Central

Jiang, Zhaoxia; Liu, Qingsong; Dekkers, Mark J.; Barrón, Vidal; Torrent, José; Roberts, Andrew P.

2016-01-01

Hematite and goethite are the two most abundant iron oxides in natural environments. Their formation is controlled by multiple environmental factors; therefore, their relative concentration has been used widely to indicate climatic variations. In this study, we aimed to test whether hematite and goethite growth is influenced by ambient magnetic fields of Earth-like values. Ferrihydrite was aged at 95 °C in magnetic fields ranging from ~0 to ~100 μT. Our results indicate a large influence of the applied magnetic field on hematite and goethite growth from ferrihydrite. The synthesized products are a mixture of hematite and goethite for field intensities <~60 μT. Higher fields favour hematite formation by accelerating ferrimagnetic ferrihydrite aggregation. Additionally, hematite particles growing in a controlled magnetic field of ~100 μT appear to be arranged in chains, which may be reduced to magnetite keeping its original configuration, therefore, the presence of magnetic particles in chains in natural sediments cannot be used as an exclusive indicator of biogenic magnetite. Hematite vs. goethite formation in our experiments is influenced by field intensity values within the range of geomagnetic field variability. Thus, geomagnetic field intensity could be a source of variation when using iron (oxyhydr-)oxide concentrations in environmental magnetism. PMID:27458091

Control of Earth-like magnetic fields on the transformation of ferrihydrite to hematite and goethite.

PubMed

Jiang, Zhaoxia; Liu, Qingsong; Dekkers, Mark J; Barrón, Vidal; Torrent, José; Roberts, Andrew P

2016-07-26

Hematite and goethite are the two most abundant iron oxides in natural environments. Their formation is controlled by multiple environmental factors; therefore, their relative concentration has been used widely to indicate climatic variations. In this study, we aimed to test whether hematite and goethite growth is influenced by ambient magnetic fields of Earth-like values. Ferrihydrite was aged at 95 °C in magnetic fields ranging from ~0 to ~100 μT. Our results indicate a large influence of the applied magnetic field on hematite and goethite growth from ferrihydrite. The synthesized products are a mixture of hematite and goethite for field intensities <~60 μT. Higher fields favour hematite formation by accelerating ferrimagnetic ferrihydrite aggregation. Additionally, hematite particles growing in a controlled magnetic field of ~100 μT appear to be arranged in chains, which may be reduced to magnetite keeping its original configuration, therefore, the presence of magnetic particles in chains in natural sediments cannot be used as an exclusive indicator of biogenic magnetite. Hematite vs. goethite formation in our experiments is influenced by field intensity values within the range of geomagnetic field variability. Thus, geomagnetic field intensity could be a source of variation when using iron (oxyhydr-)oxide concentrations in environmental magnetism.

Thermal Stability of Goethite-Bound Natural Organic Matter Is Impacted by Carbon Loading.

PubMed

Feng, Wenting; Klaminder, Jonatan; Boily, Jean-François

2015-12-24

Dissolved natural organic matter (NOM) sorption at mineral surfaces can significantly affect the persistence of organic carbon in soils and sediments. Consequently, determining the mechanisms that stabilize sorbed NOM is crucial for predicting the persistence of carbon in nature. This study determined the effects of loadings and pH on the thermal stability of NOM associated with synthetic goethite (α-FeOOH) particle surfaces, as a proxy for NOM-mineral interactions taking place in nature. NOM thermal stability was investigated using temperature-programmed desorption (TPD) in the 30-700 °C range to collect vibration spectra of thermally decomposing goethite-NOM assemblages, and to concomitantly analyze evolved gases using mass spectrometry. Results showed that NOM thermal stability, indicated by the range of temperatures in which CO2 evolved during thermal decomposition, was greatest in unbound NOM and lowest when NOM was bound to goethite. NOM thermal stability was also loading dependent. It decreased when loadings were in increased the 0.01 to 0.42 mg C m(-2) range, where the upper value corresponds to a Langmuirian adsorption maximum. Concomitant Fourier transform infrared (FTIR) spectroscopy measurement showed that these lowered stabilities could be ascribed to direct NOM-goethite interactions that dominated the NOM binding environment. Mineral surface interactions at larger loadings involved, on the contrary, a smaller fraction of the sorbed NOM, thus increasing thermal stability toward that of its unbound counterpart. This study thus identifies a sorption threshold below which NOM sorption to goethite decreases NOM thermal stability, and above which no strong effects are manifested. This should likely influence the fate of organic carbon exposed to thermal gradients in natural environments.

Characteristics and Kinetic Analysis of AQS Transformation and Microbial Goethite Reduction:Insight into "Redox mediator-Microbe-Iron oxide" Interaction Process.

PubMed

Zhu, Weihuang; Shi, Mengran; Yu, Dan; Liu, Chongxuan; Huang, Tinglin; Wu, Fengchang

2016-03-29

The characteristics and kinetics of redox transformation of a redox mediator, anthraquinone-2-sulfonate (AQS), during microbial goethite reduction by Shewanella decolorationis S12, a dissimilatory iron reduction bacterium (DIRB), were investigated to provide insights into "redox mediator-iron oxide" interaction in the presence of DIRB. Two pre-incubation reaction systems of the "strain S12- goethite" and the "strain S12-AQS" were used to investigate the dynamics of goethite reduction and AQS redox transformation. Results show that the concentrations of goethite and redox mediator, and the inoculation cell density all affect the characteristics of microbial goethite reduction, kinetic transformation between oxidized and reduced species of the redox mediator. Both abiotic and biotic reactions and their coupling regulate the kinetic process for "Quinone-Iron" interaction in the presence of DIRB. Our results provide some new insights into the characteristics and mechanisms of interaction among "quinone-DIRB- goethite" under biotic/abiotic driven.

Sulfur Adsorption on the Goethite (110) Surface

NASA Astrophysics Data System (ADS)

Simonetti, S.; Damiani, D.; Brizuela, G.; Juan, A.

The electronic structure of S adsorption on goethite (110) surface has been studied by ASED-MO cluster calculations. For S location, the most exposed surface atoms of goethite surface were selected. The calculations show that the surface offers several places for S adsorption. The most energetically stable system corresponds to S location above H atom. We studied in detail the configurations that correspond to the higher OP values. For these configurations, the H-S and Fe-S computed distances are 2.1 and 3.7 Å, respectively. The H-S and Fe-S are mainly bonding interaction with OP values of 0.156 and 0.034, respectively. The Fe-S interaction mainly involves Fe 3dx2-y2 atomic orbitals with lesser participation of Fe 4py and Fe 3dyz atomic orbitals. The O-S interaction shows the same bonding and antibonding contributions giving a small OP value. The O-S interaction involves O 2p orbitals. There is an electron transfer to the Fe atom from the S atom. On the other hand, there is an electron transfer to S atom from the H and O atoms, respectively.

Effects of Al(3+) doping on the structure and properties of goethite and its adsorption behavior towards phosphate.

PubMed

Li, Wei; Wang, Longjun; Liu, Fan; Liang, Xiaoliang; Feng, Xionghan; Tan, Wenfeng; Zheng, Lirong; Yin, Hui

2016-07-01

Al substitution in goethite is common in soils, and has strong influence on the structure and physicochemical properties of goethite. In this research, a series of Al-doped goethites were synthesized, and characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR) and extended X-ray absorption fine structure (EXAFS) spectroscopy. The adsorption behavior of these samples towards PO4(3-) was also investigated. Characterization results demonstrated that increasing Al content in goethite led to a reduction in crystallinity, increase in specific surface area (SSA), and morphology change from needle-like to granular. Rietveld structure refinement revealed that the lattice parameter a remained almost constant and b slightly decreased, but c was significantly reduced, and the calculated crystal density increased. EXAFS analysis demonstrated that the Fe(Al)-O distance in the structure of the doped goethites was almost the same, but the Fe-Fe(Al) distance decreased with increasing Al content. Surface analysis showed that, with increasing Al content, the content of OH groups on the mineral surface increased. The adsorption of phosphate per unit mass of Al-doped goethite increased, while adsorption per unit area decreased owing to the decrease of the relative proportion of (110) facets in the total surface area of the minerals. The results of this research facilitate better understanding of the effect of Al substitution on the structure and properties of goethite and the cycling of phosphate in the environment. Copyright © 2016. Published by Elsevier B.V.

18O/16O in CO2 evolved from goethite during some unusually rapid solid state α-FeOOH to α-Fe2O3 phase transitions: Test of an exchange model for possible use in oxygen isotope analyses of goethite

NASA Astrophysics Data System (ADS)

Yapp, Crayton J.

2015-12-01

The initial ∼60% of an isothermal vacuum dehydration of goethite can commonly be approximated by first order kinetics. Also, natural goethites contain small amounts of an Fe(CO3)OH component in apparent solid solution. The 18O/16O of CO2 evolved from the Fe(CO3)OH during isothermal vacuum dehydrations is related to the 18O/16O of the goethite by an apparent fractionation factor (αapp) that is, in turn, correlated with a first order rate constant, |m|. A kinetic exchange model predicts that αapp should decrease as |m| increases for a range of |m| that corresponds to relatively slow rates of dehydration. This pattern has been observed in published results. In contrast, for rapid rates of dehydration, αapp is predicted to increase with increasing |m|. Isothermal vacuum dehydrations of two natural goethites had unusually large values of |m| and provided serendipitous tests of this rapid-rate prediction. For these experiments, the measured values of αapp were consistent with patterns of variation predicted by the model. This allowed an estimate of the activation energy (E2) of a model parameter, K2, which is the rate constant for oxygen isotope exchange between CO2 and H2O during the solid-state goethite to hematite phase transition. The estimated value of E2 is only ∼9 kJ/mol. Heterogeneous catalysis tends to decrease the activation energies of gas reactions. Consequently, the inferred value of E2 suggests that goethite and/or hematite catalyze oxygen isotope exchange between CO2 and H2O during the solid-state phase change. Yield, δ13C, and δ18O values are routinely measured for increments of CO2 evolved from the Fe(CO3)OH component during isothermal vacuum dehydration of goethite. Model-predicted values of αapp can be combined with plateau δ18O values of the evolved CO2 to estimate the δ18O of the goethite with a less than optimal, but potentially useful, precision of about ±0.8‰. Therefore, a single analytical procedure (incremental dehydration

Reduced partition function ratios of iron and oxygen in goethite

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

Blanchard, M.; Dauphas, N.; Hu, M. Y.

2015-02-01

First-principles calculations based on the density functional theory (DFT) with or without the addition of a Hubbard U correction, are performed on goethite in order to determine the iron and oxygen reduced partition function ratios (beta-factors). The calculated iron phonon density of states (pDOS), force constant and beta-factor are compared with reevaluated experimental beta-factors obtained from Nuclear Resonant Inelastic X-ray Scattering (NRIXS) measurements. The reappraisal of old experimental data is motivated by the erroneous previous interpretation of the low- and high-energy ends of the NRIXS spectrum of goethite and jarosite samples (Dauphas et al., 2012). Here the NRIXS data aremore » analyzed using the SciPhon software that corrects for non-constant baseline. New NRIXS measurements also demonstrate the reproducibility of the results. Unlike for hematite and pyrite, a significant discrepancy remains between DFT, NRIXS and the existing Mossbauer-derived data. Calculations suggest a slight overestimation of the NRIXS signal possibly related to the baseline definition. The intrinsic features of the samples studied by NRIXS and Mossbauer spectroscopy may also contribute to the discrepancy (e. g., internal structural and/or chemical defects, microstructure, surface contribution). As for oxygen, DFT results indicate that goethite and hematite have similar beta-factors, which suggests almost no fractionation between the two minerals at equilibrium.« less

Magnetic properties of chemical remanent magnetization in synthetic and natural goethite - Prospects for a natural remanent magnetization/thermoremanent magnetization ratio paleomagnetic stability test?

NASA Astrophysics Data System (ADS)

Dekkers, Mark J.; Rochette, Pierre

1992-11-01

Results are presented of measurements of chemical remanent magnetization properties in natural goethite and in goethite samples synthesized under controlled field conditions (horizontally directed field of 0.30 mT) at 30 C and 55 C, with and without the presence of microfiber glass filters. Results indicate that both the temperature and the presence of a substrate (microfiber glass filters) affect the goethite aging process and the magnetic properties of the resulting goethite. The goethite aging from ferrihydrite was much faster at 55 C than at 30 C, likely because of increased ion diffusion velocity in solution. Results of goethite aging in the presence of other mineral substrate (gibbsite) indicate that the type of mineral substrate is important.

Effect of fulvic acid surface coatings on plutonium sorption and desorption kinetics on goethite

DOE PAGES

Tinnacher, Ruth M.; Begg, James D.; Mason, Harris; ...

2015-01-21

The rates and extent of plutonium (Pu) sorption and desorption onto mineral surfaces are important parameters for predicting Pu mobility in subsurface environments. The presence of natural organic matter, such as fulvic acid (FA), may influence these parameters. We investigated the effects of FA on Pu(IV) sorption/desorption onto goethite in two scenarios: when FA was (1) initially present in solution or (2) found as organic coatings on the mineral surface. A low pH was used to maximize FA coatings on goethite. Experiments were combined with kinetic modeling and speciation calculations to interpret variations in Pu sorption rates in the presencemore » of FA. Our results indicate that FA can change the rates and extent of Pu sorption onto goethite at pH 4. Differences in the kinetics of Pu sorption were observed as a function of the concentration and initial form of FA. The fraction of desorbed Pu decreased in the presence of FA, indicating that organic matter can stabilize sorbed Pu on goethite. These results suggest that ternary Pu–FA–mineral complexes could enhance colloid-facilitated Pu transport. In conclusion, more representative natural conditions need to be investigated to quantify the relevance of these findings.« less

Lead and selenite adsorption at water–goethite interfaces from first principles

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

Leung, Kevin; Criscenti, Louise J.

Here, the complexation of toxic and/or radioactive ions on to mineral surfaces is an important topic in geochemistry. We apply periodic-boundary-conditions density functional theory (DFT) molecular dynamics simulations to examine the coordination of Pb(II),more » $${\\rm SeO}_3^{2-}$$ , and their contact ion pairs to goethite (1 0 1) and (2 1 0) surfaces. The multitude of Pb(II) adsorption sites and possibility of Pb(II)-induced FeOH deprotonation make this a complex problem. At surface sites where Pb(II) is coordinated to three FeO and/or FeOH groups, and with judicious choices of FeOH surface group protonation states, the predicted Fe–Pb distances are in good agreement with EXAFS measurements. Trajectories where Pb(II) is in part coordinated to only two surface Fe–O groups exhibit larger fluctuations in Pb–O distances. Pb(II)/$${\\rm SeO}_3^{2-}$$ contact ion pairs are at least metastable on goethite (2 1 0) surfaces if the $${\\rm SeO}_3^{2-}$$ has a monodentate Se–O–Fe bond. Our DFT-based molecular dynamics calculations are a prerequisite for calculations of finite temperature equilibrium binding constants of Pb(II) and Pb(II)/$${\\rm SeO}_3^{2-}$$ ion pairs to goethite adsorption sites.« less

Lead and selenite adsorption at water–goethite interfaces from first principles

DOE PAGES

Leung, Kevin; Criscenti, Louise J.

2017-08-04

Here, the complexation of toxic and/or radioactive ions on to mineral surfaces is an important topic in geochemistry. We apply periodic-boundary-conditions density functional theory (DFT) molecular dynamics simulations to examine the coordination of Pb(II),more » $${\\rm SeO}_3^{2-}$$ , and their contact ion pairs to goethite (1 0 1) and (2 1 0) surfaces. The multitude of Pb(II) adsorption sites and possibility of Pb(II)-induced FeOH deprotonation make this a complex problem. At surface sites where Pb(II) is coordinated to three FeO and/or FeOH groups, and with judicious choices of FeOH surface group protonation states, the predicted Fe–Pb distances are in good agreement with EXAFS measurements. Trajectories where Pb(II) is in part coordinated to only two surface Fe–O groups exhibit larger fluctuations in Pb–O distances. Pb(II)/$${\\rm SeO}_3^{2-}$$ contact ion pairs are at least metastable on goethite (2 1 0) surfaces if the $${\\rm SeO}_3^{2-}$$ has a monodentate Se–O–Fe bond. Our DFT-based molecular dynamics calculations are a prerequisite for calculations of finite temperature equilibrium binding constants of Pb(II) and Pb(II)/$${\\rm SeO}_3^{2-}$$ ion pairs to goethite adsorption sites.« less

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

Goethite surface reactivity: III. Unifying arsenate adsorption behavior through a variable crystal face - Site density model

NASA Astrophysics Data System (ADS)

Salazar-Camacho, Carlos; Villalobos, Mario

2010-04-01

We developed a model that describes quantitatively the arsenate adsorption behavior for any goethite preparation as a function of pH and ionic strength, by using one basic surface arsenate stoichiometry, with two affinity constants. The model combines a face distribution-crystallographic site density model for goethite with tenets of the Triple Layer and CD-MUSIC surface complexation models, and is self-consistent with its adsorption behavior towards protons, electrolytes, and other ions investigated previously. Five different systems of published arsenate adsorption data were used to calibrate the model spanning a wide range of chemical conditions, which included adsorption isotherms at different pH values, and adsorption pH-edges at different As(V) loadings, both at different ionic strengths and background electrolytes. Four additional goethite-arsenate systems reported with limited characterization and adsorption data were accurately described by the model developed. The adsorption reaction proposed is: lbond2 FeOH +lbond2 SOH +AsO43-+H→lbond2 FeOAsO3[2-]…SOH+HO where lbond2 SOH is an adjacent surface site to lbond2 FeOH; with log K = 21.6 ± 0.7 when lbond2 SOH is another lbond2 FeOH, and log K = 18.75 ± 0.9, when lbond2 SOH is lbond2 Fe 2OH. An additional small contribution of a protonated complex was required to describe data at low pH and very high arsenate loadings. The model considered goethites above 80 m 2/g as ideally composed of 70% face (1 0 1) and 30% face (0 0 1), resulting in a site density for lbond2 FeOH and for lbond2 Fe 3OH of 3.125/nm 2 each. Below 80 m 2/g surface capacity increases progressively with decreasing area, which was modeled by considering a progressively increasing proportion of faces (0 1 0)/(1 0 1), because face (0 1 0) shows a much higher site density of lbond2 FeOH groups. Computation of the specific proportion of faces, and thus of the site densities for the three types of crystallographic surface groups present in

Effect of ionic strength on barium transport in porous media

NASA Astrophysics Data System (ADS)

Ye, Zi; Prigiobbe, Valentina

2018-02-01

Hydraulic fracturing (or fracking) is a well stimulation technique used to extract resources from a low permeability formation. Currently, the most common application of fracking is for the extraction of oil and gas from shale. During the operation, a large volume of brine, rich in hazardous chemicals, is produced. Spills of brine from wells or pits might negatively impact underground water resources and, in particular, one of the major concerns is the migration of radionuclides, such as radium (Ra2+), into the shallow subsurface. However, the transport behaviour of Ra2+ through a reactive porous medium under conditions typical of a brine, i.e., high salinity, is not well understood, yet. Here, a study on the transport behaviour of barium (Ba2+, congener of radium) through a porous medium containing a common mineral such as goethite (FeO(OH)) is presented. Batch and column flood tests were carried out at conditions resembling the produced brine, i.e., large values of ionic strength (I), namely, 1 to 3 mol/kg. The measurements were described with the triple layer surface complexation model coupled with the Pitzer activity coefficient method and a reactive transport model, in the case of the transport tests. The experimental results show that the adsorption of Ba2+ onto FeO(OH) increases with pH but decreases with I and it becomes negligible at the brine conditions. Moreover, even if isotherms show adsorption at large I, at the same conditions during transport, Ba2+ travels without retardation through the FeO(OH) porous medium. The triple layer model agrees very well with all batch data but it does not describe well the transport tests in all cases. In particular, the model cannot match the pH measurements at large I values. This suggests that the chemical reactions at the solid-liquid interface do not capture the mechanism of Ba2+ adsorption onto FeO(OH) at large salinity. Finally, this study suggests that barium, and potentially its congeners, namely, radium

Can Dynamic Bubble Templating Play a Role in Corrosion Product Morphology?

DTIC Science & Technology

2012-02-01

FeOOH (goethite) with moderate amounts of metallic luster Fe304 (magnetite), and trace amounts of CaC03 (calcite). In addition, the core was marbled ...cathodically produced gas bubbles (i.e., H2). By physically separating the anode and cathode. Stone and Goldstein26 generated tubular structures electro...D.A. Stone , RE. Goldstein. Proc. MatL Acad. Set U.S-A. 101 (2004): p. 11537. G. Butler, H.C.K. Ison, Nature 182 (1958): p. 1229. B. McEnaney. D.C

Crystal Face Distributions and Surface Site Densities of Two Synthetic Goethites: Implications for Adsorption Capacities as a Function of Particle Size.

PubMed

Livi, Kenneth J T; Villalobos, Mario; Leary, Rowan; Varela, Maria; Barnard, Jon; Villacís-García, Milton; Zanella, Rodolfo; Goodridge, Anna; Midgley, Paul

2017-09-12

Two synthetic goethites of varying crystal size distributions were analyzed by BET, conventional TEM, cryo-TEM, atomic resolution STEM and HRTEM, and electron tomography in order to determine the effects of crystal size, shape, and atomic scale surface roughness on their adsorption capacities. The two samples were determined by BET to have very different site densities based on Cr VI adsorption experiments. Model specific surface areas generated from TEM observations showed that, based on size and shape, there should be little difference in their adsorption capacities. Electron tomography revealed that both samples crystallized with an asymmetric {101} tablet habit. STEM and HRTEM images showed a significant increase in atomic-scale surface roughness of the larger goethite. This difference in roughness was quantified based on measurements of relative abundances of crystal faces {101} and {201} for the two goethites, and a reactive surface site density was calculated for each goethite. Singly coordinated sites on face {210} are 2.5 more dense than on face {101}, and the larger goethite showed an average total of 36% {210} as compared to 14% for the smaller goethite. This difference explains the considerably larger adsorption capacitiy of the larger goethite vs the smaller sample and points toward the necessity of knowing the atomic scale surface structure in predicting mineral adsorption processes.

Experimental and modeling study of the uranium (VI) sorption on goethite.

PubMed

Missana, Tiziana; García-Gutiérrez, Miguel; Maffiotte, Cesar

2003-04-15

Acicular goethite was synthesized in the laboratory and its main physicochemical properties (composition, microstructure, surface area, and surface charge) were analyzed as a previous step to sorption experiments. The stability of the oxide, under the conditions used in sorption studies, was also investigated. The sorption of U(VI) onto goethite was studied under O(2)- and CO(2)-free atmosphere and in a wide range of experimental conditions (pH, ionic strength, radionuclide, and solid concentration), in order to assess the validity of different surface complexation models available for the interpretation of sorption data. Three different models were used to fit the experimental data. The first two models were based on the diffuse double layer concept. The first one (Model 1) considered two different monodentate complexes with the goethite surface and the second (Model 2) a single binuclear bidentate complex. A nonelectrostatic (NE) approach was used as a third model and, in that case, the same species considered in Model 1 were used. The results showed that all the models are able to describe the sorption behavior fairly well as a function of pH, electrolyte concentration, and U(VI) concentration. However, Model 2 fails in the description of the uranium sorption behavior as a function of the sorbent concentration. This demonstrates the importance of checking the validity of any surface complexation model under the widest possible range of experimental conditions.

Reductive Dissolution of Goethite and Hematite by Reduced Flavins

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

Shi, Zhi; Zachara, John M.; Wang, Zheming

2013-10-02

The abiotic reductive dissolution of goethite and hematite by the reduced forms of flavin mononucleotide (FMNH2) and riboflavin (RBFH2), electron transfer mediators (ETM) secreted by the dissimilatory iron-reducing bacterium Shewanella, was investigated under stringent anaerobic conditions. In contrast to the rapid redox reaction rate observed for ferrihydrite and lepidocrocite (Shi et al., 2012), the reductive dissolution of crystalline goethite and hematite was slower, with the extent of reaction limited by the thermodynamic driving force at circumneutral pH. Both the initial reaction rate and reaction extent increased with decreasing pH. On a unit surface area basis, goethite was less reactive thanmore » hematite between pH 4.0 and 7.0. AH2DS, the reduced form of the well-studied synthetic ETM anthraquinone-2,6-disulfonate (AQDS), yielded higher rates than FMNH2 under most reaction conditions, despite the fact that FMNH2 was a more effective reductant than AH2DS for ferryhydrite and lepidocrocite. Two additional model compounds, methyl viologen and benzyl viologen, were investigated under similar reaction conditions to explore the relationship between reaction rate and thermodynamic properties. Relevant kinetic data from the literature were also included in the analysis to span a broad range of half-cell potentials. Other conditions being equal, the surface area normalized initial reaction rate (ra) increased as the redox potential of the reductant became more negative. A non-linear, parabolic relationship was observed between log ra and the redox potential for eight reducants at pH 7.0, as predicted by Marcus theory for electron transfer. When pH and reductant concentration were fixed, log ra was positively correlated to the redox potential of four Fe(III) oxides over a wide pH range, following a non-linear parabolic relationship as well.« less

Interaction between calcium and phosphate adsorption on goethite.

PubMed

Rietra, R P; Hiemstra, T; van Riemsdijk, W H

2001-08-15

Quantitatively, little is known about the ion interaction processes that are responsible for the binding of phosphate in soil, water, and sediment, which determine the bioavailability and mobility of phosphate. Studies have shown that metal hydroxides are often responsible for the binding of PO4 in soils and sediments, but the binding behavior of PO4 in these systems often differs significantly from adsorption studies on metal hydroxides in laboratory. The interaction between PO4 and Ca adsorption was studied on goethite because Ca can influence the PO4 adsorption equilibria. Since adsorption interactions are very difficult to discriminate from precipitation reactions, conditions were chosen to prevent precipitation of Ca-PO4 solids. Adsorption experiments of PO4 and Ca, individually and in combination, show a strong interaction between adsorbed Ca and PO4 on goethite for conditions below the saturation index of apatite. It is shown that it is possible to predict the adsorption and interaction of PO4 and Ca on electrostatic arguments using the model parameter values derived from the single-ion systems and without invoking ternary complex formation or precipitation. The model enables the prediction of the Ca-PO4 interaction for environmentally relevant calcium and phosphate concentrations.

Adsorption of Phosphate on Goethite: An Undergraduate Research Laboratory Project

ERIC Educational Resources Information Center

Tribe, Lorena; Barja, Beatriz C.

2004-01-01

A laboratory experiment on the adsorption of phosphate on goethite is presented, which also includes discussion on surface properties, interfaces, acid-base equilibrium, molecular structure and solid state chemistry. It was seen that many students were able to produce qualitatively correct results for a complex system of real interest and they…

Effects of different crystal faces on the surface charge of colloidal goethite (α-FeOOH) particles: an experimental and modeling study

NASA Astrophysics Data System (ADS)

Gaboriaud, Fabien; Ehrhardt, Jean-Jacques

2003-03-01

The surface charge of colloidal particles is usually determined by potentiometric titration. These acid-base titrations make it possible to measure the pH of point-of-zero charge (pzc) for oxide minerals. This macroscopic property is the most important parameter used in surface complexation modeling to reproduce experimental data. The pzc values of goethite reported in the literature vary between 7.0 and 9.5. Carbonate adsorption and/or surface morphology are thought to account for this wide range. We demonstrate a procedure for the removal of the carbonate ions that initially adsorb on goethite and strongly affect the titration curves and pzc determination. We also investigated the crystal-face-specific reactivity of two morphologically different goethites. The z-profiles obtained from atomic force microscopy (AFM) images showed that the goethite with the smallest specific surface area ( S = 49 m 2/g, denoted G49) exhibits 70% of the (001) face, whereas this value is only 30% for the goethite with largest specific surface area ( S = 95 m 2/g, denoted G95). This morphologic difference results in slightly different pzc values: 9.0 for G49 goethite and 9.1 for G95 geothite. These experimental pzc values have been correlated with multisite complexation calculations using both the full-site and the 1-pK approaches. We used the full-site approach to consider all of the configurations of hydrogen bond interactions with surface site. The resulting mean charges gave estimated pzc values of 8.9 and 9.2 for the (001) and (101) faces, respectively. Considering these theoretical pzc values for individual faces and the face distributions obtained from AFM analysis, the calculated pzc values are in full agreement with the experimental pzc values. However, this morphologic difference is more expressed in surface charge values than in the pzc values. Indeed, the surface charge of G49 goethite is much higher than that of G95 goethite, and the 1-pK calculations make it possible to

Equilibrium isotherms, kinetics, and thermodynamics studies for congo red adsorption using calcium alginate beads impregnated with nano-goethite.

PubMed

Munagapati, Venkata Subbaiah; Kim, Dong-Su

2017-07-01

The present study is concerned with the batch adsorption of congo red (CR) from an aqueous solution using calcium alginate beads impregnated with nano-goethite (CABI nano-goethite) as an adsorbent. The optimum conditions for CR removal were determined by studying operational variables viz. pH, adsorbent dose, contact time, initial dye ion concentration and temperature. The CABI nano-goethite was characterized by Fourier transform infrared spectroscopy (FTIR), X- ray diffraction (XRD) and Scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS) analysis. The CR sorption data onto CABI nano-goethite were described using Langmuir, Freundlich, Dubinin-Radushkevich and Temkin isotherm models. The results show that the best fit was achieved with the Langmuir isotherm model. The maximum adsorption capacity (181.1mg/g) of CR was occurred at pH 3.0. Kinetic studies showed that the adsorption followed a pseudo-second-order model. Desorption experiments were carried out to explore the feasibility of regenerating the adsorbent and the adsorbed CR from CABI nano-goethite. The best desorbing agent was 0.1M NaOH with an efficiency of 94% recovery. The thermodynamic parameters ΔG°, ΔH°, and ΔS° for the CR adsorption were determined by using adsorption capacities at five different temperatures (293, 303, 313, 323 and 303K). Results show that the adsorption process was endothermic and favoured at high temperature. Copyright © 2017 Elsevier Inc. All rights reserved.

Imaging of Al/Fe ratios in synthetic Al-goethite revealed by nanoscale secondary ion mass spectrometry.

PubMed

Pohl, Lydia; Kölbl, Angelika; Werner, Florian; Mueller, Carsten W; Höschen, Carmen; Häusler, Werner; Kögel-Knabner, Ingrid

2018-04-30

Aluminium (Al)-substituted goethite is ubiquitous in soils and sediments. The extent of Al-substitution affects the physicochemical properties of the mineral and influences its macroscale properties. Bulk analysis only provides total Al/Fe ratios without providing information with respect to the Al-substitution of single minerals. Here, we demonstrate that nanoscale secondary ion mass spectrometry (NanoSIMS) enables the precise determination of Al-content in single minerals, while simultaneously visualising the variation of the Al/Fe ratio. Al-substituted goethite samples were synthesized with increasing Al concentrations of 0.1, 3, and 7 % and analysed by NanoSIMS in combination with established bulk spectroscopic methods (XRD, FTIR, Mössbauer spectroscopy). The high spatial resolution (50-150 nm) of NanoSIMS is accompanied by a high number of single-point measurements. We statistically evaluated the Al/Fe ratios derived from NanoSIMS, while maintaining the spatial information and reassigning it to its original localization. XRD analyses confirmed increasing concentration of incorporated Al within the goethite structure. Mössbauer spectroscopy revealed 11 % of the goethite samples generated at high Al concentrations consisted of hematite. The NanoSIMS data show that the Al/Fe ratios are in agreement with bulk data derived from total digestion and demonstrated small spatial variability between single-point measurements. More advantageously, statistical analysis and reassignment of single-point measurements allowed us to identify distinct spots with significantly higher or lower Al/Fe ratios. NanoSIMS measurements confirmed the capacity to produce images, which indicated the uniform increase in Al-concentrations in goethite. Using a combination of statistical analysis with information from complementary spectroscopic techniques (XRD, FTIR and Mössbauer spectroscopy) we were further able to reveal spots with lower Al/Fe ratios as hematite. Copyright © 2018 John

Oxidative C-H activation of amines using protuberant lychee-like goethite

EPA Science Inventory

Goethite with protuberant lychee morphology has been synthesized that accomplishes C-H activation of N-methylanilines to generate α-aminonitriles; the catalyst takes oxygen from air and uses it as a cooxidant in the process. Inspired by nature, we aspired to design a protocol for...

Modeling of Cd adsorption to goethite-bacteria composites

DOE PAGES

Qu, Chenchen; Ma, Mingkai; Chen, Wenli; ...

2017-11-21

The accurate modeling of heavy metal adsorption in complex systems is fundamental for risk assessments in soils and associated environments. Bacteria-iron (hydr)oxide associations in soils and sediments play a critical role in heavy metal immobilization. The reduced adsorption of heavy metals on these composites have been widely reported using the component additivity (CA) method. However, there is a lack of a mechanism model to account for these deviations. In this study, we established models for Cd adsorption on goethite-Pseudomonas putida composites at 1:1 and 5:1 mass ratios. Cadmium adsorption on the 5:1 composite was consistent with the additivity method. But,more » the CA method over predicted Cd adsorption by approximately 8% on the 1:1 composite at high Cd concentration. The deviation was corrected by adding the site blockage reactions between P. putida and goethite. Both CA and “CA-site masking” models for Cd adsorption onto the composites were in line with the ITC data. These results indicate that CA method in simulating Cd adsorption on bacteria-iron oxides composites is limited to low bacterial and Cd concentrations. Thus the interfacial complexation reactions that occur between iron (hydr)oxides and bacteria should be taken into account when high concentrations of bacteria and heavy metals are present.« less

Modeling of Cd adsorption to goethite-bacteria composites

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

Qu, Chenchen; Ma, Mingkai; Chen, Wenli

The accurate modeling of heavy metal adsorption in complex systems is fundamental for risk assessments in soils and associated environments. Bacteria-iron (hydr)oxide associations in soils and sediments play a critical role in heavy metal immobilization. The reduced adsorption of heavy metals on these composites have been widely reported using the component additivity (CA) method. However, there is a lack of a mechanism model to account for these deviations. In this study, we established models for Cd adsorption on goethite-Pseudomonas putida composites at 1:1 and 5:1 mass ratios. Cadmium adsorption on the 5:1 composite was consistent with the additivity method. But,more » the CA method over predicted Cd adsorption by approximately 8% on the 1:1 composite at high Cd concentration. The deviation was corrected by adding the site blockage reactions between P. putida and goethite. Both CA and “CA-site masking” models for Cd adsorption onto the composites were in line with the ITC data. These results indicate that CA method in simulating Cd adsorption on bacteria-iron oxides composites is limited to low bacterial and Cd concentrations. Thus the interfacial complexation reactions that occur between iron (hydr)oxides and bacteria should be taken into account when high concentrations of bacteria and heavy metals are present.« less

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.

Controls on Fe(II)-Activated Trace Element Release from Goethite and Hematite

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

Frierdich, Andrew J.; Catalano, Jeffrey G.

2012-03-26

Electron transfer and atom exchange (ETAE) between aqueous Fe(II) and Fe(III) oxides induces surface growth and dissolution that affects trace element fate and transport. We have recently demonstrated Ni(II) cycling through goethite and hematite (adsorbed Ni incorporates into the mineral structure and preincorporated Ni releases to solution) during Fe(II)-Fe(III) ETAE. However, the chemical parameters affecting net trace element release remain unknown. Here, we examine the chemical controls on Ni(II) and Zn(II) release from Ni- and Zn-substituted goethite and hematite during reaction with Fe(II). Release follows a rate law consistent with surface reaction limited mineral dissolution and suggests that release occursmore » near sites of Fe(III) reductive dissolution during Fe(II)-Fe(III) ETAE. Metal substituent type affects reactivity; Zn release is more pronounced from hematite than goethite, whereas the opposite trend occurs for Ni. Buildup of Ni or Zn in solution inhibits further release but this resumes upon fluid exchange, suggesting that sustained release is possible under flow conditions. Mineral and aqueous Fe(II) concentrations as well as pH strongly affect sorbed Fe(II) concentrations, which directly control the reaction rates and final metal concentrations. Our results demonstrate that structurally incorporated trace elements are mobilized from iron oxides into fluids without abiotic or microbial net iron reduction. Such release may affect micronutrient availability, contaminant transport, and the distribution of redox-inactive trace elements in natural and engineered systems.« less

Reconstructing Holocene hematite and goethite variations in the Indus Canyon to trace changes in the Asian monsoon system

NASA Astrophysics Data System (ADS)

Koehler, Cornelia; Clift, Peter; Pressling, Nicola; Limmer, David; Giosan, Liviu; Tabrez, Ali

2010-05-01

In order to study Holocene Asian monsoon variations, we reconstructed changes in chemical weathering by examining sediments from the Indus Canyon. During the late Holocene, the Asian monsoon system had periods of high and low intensities that influenced the civilisations living in its realm. For example, the demise of the Harappan civilisation has been linked to a weakened monsoon system around 4 ka. The sediments in the Indus Canyon, which originate from the River Indus and its Himalayan tributaries, provide an ideal, natural environmental archive of the South Asian monsoon system. In order to investigate the alternation between arid and humid monsoonal climatic conditions, variations are traced using the magnetic minerals hematite and goethite, which form under distinct environmental conditions: goethite is stable under humid conditions, whereas hematite forms from the dehydration of goethite under arid conditions. The two minerals are characterised and quantified using environmental magnetic measurements, as well as diffuse reflectance spectrometry. Combining both approaches will enable us to reconstruct variations in chemical weathering over time. Furthermore, because this is governed by temperature and the availability of moisture, our weathering record will allow us to understand monsoon variability during the Holocene and test whether summer rain intensity has been decreasing in SW Asia since 8 ka. In addition, the multi-component analysis of colour reflectance spectra identifies different mineral components including hematite/goethite, clay mineral mixtures, calcite and organics. We will present our results from the multi-sensor core logger equipped with a Minolta spectrometer, measuring both magnetic susceptibility and the optical properties of the split sediment cores. Initial results indicate the presence of hematite and goethite in the sediment. There is an increasing hematite content up the cores, indicating an aridification trend during the Holocene

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

Characteristics and kinetic analysis of AQS transformation and microbial goethite reduction: Insight into “redox mediator-microbe-iron oxide” interaction process

DOE PAGES

Zhu, Weihuang; Shi, Mengran; Yu, Dan; ...

2016-03-29

Here, the characteristics and kinetics of redox transformation of a redox mediator, anthraquinone-2-sulfonate (AQS), during microbial goethite reduction by Shewanella decolorationis S12, a dissimilatory iron reduction bacterium (DIRB), were investigated to provide insights into “redox mediator-iron oxide” interaction in the presence of DIRB. Two pre-incubation reaction systems of the “strain S12-goethite” and the “strain S12-AQS” were used to investigate the dynamics of goethite reduction and AQS redox transformation. Results show that the concentrations of goethite and redox mediator, and the inoculation cell density all affect the characteristics of microbial goethite reduction, kinetic transformation between oxidized and reduced species of themore » redox mediator. Both abiotic and biotic reactions and their coupling regulate the kinetic process for “Quinone-Iron” interaction in the presence of DIRB. Our results provide some new insights into the characteristics and mechanisms of interaction among “quinone-DIRB- goethite” under biotic/abiotic driven.« less

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.

Fungal biomineralization of montmorillonite and goethite to short-range-ordered minerals

NASA Astrophysics Data System (ADS)

Li, Huan; Hu, Shuijin; Polizzotto, Matthew L.; Chang, Xiaoli; Shen, Qirong; Ran, Wei; Yu, Guanghui

2016-10-01

Highly reactive nano-scale minerals, e.g., short-range-ordered minerals (SROs) and other nanoparticles, play an important role in soil carbon (C) retention. Yet, the mechanisms that govern biomineralization from bulk minerals to highly reactive nano-scale minerals remain largely unexplored, which critically hinders our efforts toward managing nano-scale minerals for soil C retention. Here we report the results from a study that explores structural changes during Aspergillus fumigatus Z5 transformation of montmorillonite and goethite to SROs. We examined the morphology and structure of nano-scale minerals, using high-resolution transmission electron microscopy, time-resolved solid-state 27Al and 29Si NMR, and Fe K-edge X-ray absorption fine structure spectroscopy combined with two dimensional correlation spectroscopy (2D COS) analysis. Our results showed that after a 48-h cultivation of montmorillonite and goethite with Z5, new biogenic intracellular and extracellular reactive nano-scale minerals with a size of 3-5 nm became abundant. Analysis of 2D COS further suggested that montmorillonite and goethite were the precursors of the dominant biogenic nano-scale minerals. Carbon 1s near edge X-ray absorption fine structure (NEXAFS) spectra and their deconvolution results demonstrated that during fungus Z5 growth, carboxylic C (288.4-289.1 eV) was the dominant organic group, accounting for approximately 34% and 59% in the medium and aggregates, respectively. This result suggested that high percentage of the production of organic acids during the growth of Z5 was the driving factor for structural changes during biomineralization. This is, to the best of our knowledge, the first report of the structural characterization of nano-scale minerals by 2D COS, highlighting its potential to elucidate biomineralization pathways and thus identify the precursors of nano-scale minerals.

Surface reaction of SnII on goethite (α-FeOOH): surface complexation, redox reaction, reductive dissolution, and phase transformation.

PubMed

Dulnee, Siriwan; Scheinost, Andreas C

2014-08-19

To elucidate the potential risk of (126)Sn migration from nuclear waste repositories, we investigated the surface reactions of Sn(II) on goethite as a function of pH and Sn(II) loading under anoxic condition with O2 level < 2 ppmv. Tin redox state and surface structure were investigated by Sn K edge X-ray absorption spectroscopy (XAS), goethite phase transformations were investigated by high-resolution transmission electron microscopy and selected area electron diffraction. The results demonstrate the rapid and complete oxidation of Sn(II) by goethite and formation of Sn(IV) (1)E and (2)C surface complexes. The contribution of (2)C complexes increases with Sn loading. The Sn(II) oxidation leads to a quantitative release of Fe(II) from goethite at low pH, and to the precipitation of magnetite at higher pH. To predict Sn sorption, we applied surface complexation modeling using the charge distribution multisite complexation approach and the XAS-derived surface complexes. Log K values of 15.5 ± 1.4 for the (1)E complex and 19.2 ± 0.6 for the (2)C complex consistently predict Sn sorption across pH 2-12 and for two different Sn loadings and confirm the strong retention of Sn(II) even under anoxic conditions.

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.

Aquatic photolysis: photolytic redox reactions between goethite and adsorbed organic acids in aqueous solutions

USGS Publications Warehouse

Goldberg, M.C.; Cunningham, K.M.; Weiner, Eugene R.

1993-01-01

Photolysis of mono and di-carboxylic acids that are adsorbed onto the surface of the iron oxyhydroxide (goethite) results in an oxidation of the organic material and a reduction from Fe(III) to Fe(II) in the iron complex. There is a subsequent release of Fe2+ ions into solution. At constant light flux and constant solution light absorption, the factors responsible for the degree of photolytic reaction include: the number of lattice sites that are bonded by the organic acid; the rate of acid readsorption to the surface during photolysis; the conformation and structure of the organic acid; the degree of oxidation of the organic acid; the presence or absence of an ??-hydroxy group on the acid, the number of carbons in the di-acid chain and the conformation of the di-acid. The ability to liberate Fe(III) at pH 6.5 from the geothite lattice is described by the lyotropic series: tartrate>citrate> oxalate > glycolate > maleate > succinate > formate > fumarate > malonate > glutarate > benzoate = butanoate = control. Although a larger amount of iron is liberated, the series is almost the same at pH 5.5 except that oxalate > citrate and succinate > maleate. A set of rate equations are given that describe the release of iron from the goethite lattice. It was observed that the pH of the solution increases during photolysis if the solutions are not buffered. There is evidence to suggest the primary mechanism for all these reactions is an electron transfer from the organic ligand to the Fe(III) in the complex. Of all the iron-oxyhydroxide materials, crystalline goethite is the least soluble in water; yet, this study indicates that in an aqueous suspension, iron can be liberated from the goethite lattice. Further, it has been shown that photolysis can occur in a multiphase system at the sediment- water interface which results in an oxidation of the organic species and release of Fe2+ to solution where it becomes available for further reaction. ?? 1993.

Hierarchical paramecium-like hollow and solid Au/Pt bimetallic nanostructures constructed using goethite as template

NASA Astrophysics Data System (ADS)

Liu, Wei; Repo, Eveliina; Heikkilä, Mikko; Leskelä, Markku; Sillanpää, Mika

2010-10-01

Novel hollow and solid paramecium-like hierarchical Au/Pt bimetallic nanostructures were constructed using goethite as template via a seed-mediated growth method. Transmission electron microscopy (TEM), ξ-potential measurement, UV-vis spectroscopy, energy dispersive x-ray spectroscopy (EDS), ICP-AES measurement, x-ray powder diffraction (XRD) and x-ray photoelectron spectroscopy (XPS) were utilized to systematically characterize the bimetallic nanostructures. It is found that the core structure of the paramecium-like bimetallic nanomaterial is closely related to reducing agent. When ascorbic acid is used as reducing agent, goethite serves as in situ sacrificed template and hollow paramecium-like bimetallic structure is obtained. When NH2OH·HCl is used, solid nanostructure with preserved goethite core is produced. Heating the reaction solution is necessary to obtain the paramecium-like morphology with rough interconnected Pt cilia shell. The thickness of Pt cilia layer can be controlled by adjusting the molar ratio of H2PtCl6 to Au nanoseeds. The overgrowth of the rough Pt cilia is proposed to be via an autocatalytic and three-dimensional heterogeneous nucleation process first through flower-like morphology. Both the hollow and solid hierarchical paramecium-like Au/Pt bimetallic nanostructures show good catalytic activities.

Hierarchical paramecium-like hollow and solid Au/Pt bimetallic nanostructures constructed using goethite as template.

PubMed

Liu, Wei; Repo, Eveliina; Heikkilä, Mikko; Leskelä, Markku; Sillanpää, Mika

2010-10-01

Novel hollow and solid paramecium-like hierarchical Au/Pt bimetallic nanostructures were constructed using goethite as template via a seed-mediated growth method. Transmission electron microscopy (TEM), xi-potential measurement, UV-vis spectroscopy, energy dispersive x-ray spectroscopy (EDS), ICP-AES measurement, x-ray powder diffraction (XRD) and x-ray photoelectron spectroscopy (XPS) were utilized to systematically characterize the bimetallic nanostructures. It is found that the core structure of the paramecium-like bimetallic nanomaterial is closely related to reducing agent. When ascorbic acid is used as reducing agent, goethite serves as in situ sacrificed template and hollow paramecium-like bimetallic structure is obtained. When NH(2)OH.HCl is used, solid nanostructure with preserved goethite core is produced. Heating the reaction solution is necessary to obtain the paramecium-like morphology with rough interconnected Pt cilia shell. The thickness of Pt cilia layer can be controlled by adjusting the molar ratio of H(2)PtCl(6) to Au nanoseeds. The overgrowth of the rough Pt cilia is proposed to be via an autocatalytic and three-dimensional heterogeneous nucleation process first through flower-like morphology. Both the hollow and solid hierarchical paramecium-like Au/Pt bimetallic nanostructures show good catalytic activities.

Plutonium(IV) and (V) sorption to goethite at sub-femtomolar to micromolar concentrations: Redox transformations and surface precipitation

DOE PAGES

Zhao, Pihong; Begg, James D.; Zavarin, Mavrik; ...

2016-06-06

Here, Pu(IV) and Pu(V) sorption to goethite was investigated over a concentration range of 10 –15–10 –5 M at pH 8. Experiments with initial Pu concentrations of 10 –15 – 10 –8 M produced linear Pu sorption isotherms, demonstrating that Pu sorption to goethite is not concentration-dependent across this concentration range. Equivalent Pu(IV) and Pu(V) sorption Kd values obtained at 1 and 2-week sampling time points indicated that Pu(V) is rapidly reduced to Pu(IV) on the goethite surface. Further, it suggested that Pu surface redox transformations are sufficiently rapid to achieve an equilibrium state within 1 week, regardless of themore » initial Pu oxidation state. At initial concentrations >10 –8 M, both Pu oxidation states exhibited deviations from linear sorption behavior and less Pu was adsorbed than at lower concentrations. NanoSIMS and HRTEM analysis of samples with initial Pu concentrations of 10 –8 – 10 –6 M indicated that Pu surface and/or bulk precipitation was likely responsible for this deviation. In 10 –6 M Pu(IV) and Pu(V) samples, HRTEM analysis showed the formation of a body centered cubic (bcc) Pu 4O 7 structure on the goethite surface, confirming that reduction of Pu(V) had occurred on the mineral surface and that epitaxial distortion previously observed for Pu(IV) sorption occurs with Pu(V) as well.« less

Surface speciation of phosphate on goethite as seen by InfraRed Surface Titrations (IRST)

NASA Astrophysics Data System (ADS)

Arroyave, Jeison Manuel; Puccia, Virginia; Zanini, Graciela P.; Avena, Marcelo J.

2018-06-01

Phosphate adsorption at the metal oxide-water interface has been intensely studied, and the system phosphate-goethite in aqueous media is normally used as a model system with abundant information regarding adsorption-desorption under very different conditions. In spite of this, there is still discussion on whether the main inner-sphere surface complexes that phosphate forms on goethite are monodentate or bidentate. A new spectroscopic technique, InfraRed Surface Titration (IRST), is presented here and used to systematically explore the surface speciation of phosphate on goethite in the pH range 4.5-9.5 at different surface coverages. IRST enabled to construct distribution curves of surface species and distribution curves of dissolved phosphate species. In combination with the CD-MUSIC surface complexation model it was possible to conclude that surface complexes are monodentate. Very accurate distribution curves were obtained, showing a crossing point at pH 5.5 at a surface coverage of 2.0 μmol m-2, with a mononuclear monoprotonated species predominating at pH > 5.5 and a mononuclear diprotonated species prevailing at pH < 5.5. On the contrary, at the low surface coverage of 0.7 μmol m-2 there is no crossing point, with the mononuclear monoprotonated species prevailing at all pH. IRST can become a powerful technique to investigate structure, properties and reactions of any IR-active surface complex at the solid-water interface.

Effect of goethite coating and humic acid on the transport of bacteriophage PRD1 in columns of saturated sand

NASA Astrophysics Data System (ADS)

Foppen, J. W. A.; Okletey, S.; Schijven, J. F.

2006-05-01

The transport of bacteriophage PRD1, a model virus, was studied in columns containing sediment mixtures of quartz sand with goethite-coated sand and using various solutions consisting of monovalent and divalent salts and humic acid (HA). Without HA and in the absence of sand, the inactivation rate of PRD1 was found to be as low as 0.014 day - 1 (at 5 ± 3 °C), but in the presence of HA it was much lower (0.0009 day - 1 ), indicating that HA helps PRD1 to survive. When the fraction of goethite in the sediment was increased, the removal of PRD1 also increased. However, in the presence of HA, C/ C0 values of PRD1 increased by as much as 5 log units, thereby almost completely eliminating the effect of addition of goethite. The sticking efficiency was not linearly dependent on the amount of goethite added to the quartz sand; this is apparently due to surface charge heterogeneity of PRD1. Our results imply that, in the presence of dissolved organic matter (DOM), viruses can be transported for long distances thanks to two effects: attachment is poor because DOM has occupied favourable sites for attachment and inactivation of virus may have decreased. This conclusion justifies making conservative assumptions about the attachment of viruses when calculating protection zones for groundwater wells.

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.

Hydrogen and oxygen stable isotope signatures of goethite hydration waters by thermogravimetry-enabled laser spectroscopy

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

Oerter, Erik; Singleton, Michael; Davisson, Lee

The hydrogen and oxygen stable isotope composition (δ 2H and δ 18O values) of mineral hydration waters can give information on the environment of mineral formation. Here we present and validate an approach for the stable isotope analysis of mineral hydration waters based on coupling a thermogravimetric analyzer with a laser-based isotope ratio infrared spectroscopy instrument (Picarro L-2130i), which we abbreviate as TGA-IRIS. TGA-IRIS generates δ 2H and δ 18O values of liquid water samples with precision for δ 2H of ± 1.2‰, and for δ 18O of ± 0.17‰. For hydration waters in goethite, precision for δ 2H rangesmore » from ± 0.3‰ to 1.6‰, and for δ 18O ranges from ± 0.17‰ to 0.27‰. The ability of TGA-IRIS to generate detailed water yield data and δ 2H and δ 18O values of water at varying temperatures allows for the differentiation of water in varying states of binding on mineral surfaces and within the mineral matrix. TGA-IRIS analyses of hydrogen isotopes in goethite yields δ 2H values that reflect the hydrogen of the OH – phase in the mineral and are comparable to that made by IRMS and found in the literature. In contrast, δ 18O values on goethite reflect the oxygen in OH – groups bound to Fe (Fe-OH group), and not the oxygen bound only to Fe (Fe-O group) in the mineral crystal lattice, and may not be comparable to literature δ 18O values made by IRMS that reflect the total O in the mineral. TGA-IRIS presents the possibility to isotopically differentiate the various oxygen reservoirs in goethite, which may allow the mineral to be used as a single mineral geothermometer. As a result, TGA-IRIS measurements of hydration waters are likely to open new avenues and possibilities for research on hydrated minerals.« less

Hydrogen and oxygen stable isotope signatures of goethite hydration waters by thermogravimetry-enabled laser spectroscopy

DOE PAGES

Oerter, Erik; Singleton, Michael; Davisson, Lee

2017-10-22

The hydrogen and oxygen stable isotope composition (δ 2H and δ 18O values) of mineral hydration waters can give information on the environment of mineral formation. Here we present and validate an approach for the stable isotope analysis of mineral hydration waters based on coupling a thermogravimetric analyzer with a laser-based isotope ratio infrared spectroscopy instrument (Picarro L-2130i), which we abbreviate as TGA-IRIS. TGA-IRIS generates δ 2H and δ 18O values of liquid water samples with precision for δ 2H of ± 1.2‰, and for δ 18O of ± 0.17‰. For hydration waters in goethite, precision for δ 2H rangesmore » from ± 0.3‰ to 1.6‰, and for δ 18O ranges from ± 0.17‰ to 0.27‰. The ability of TGA-IRIS to generate detailed water yield data and δ 2H and δ 18O values of water at varying temperatures allows for the differentiation of water in varying states of binding on mineral surfaces and within the mineral matrix. TGA-IRIS analyses of hydrogen isotopes in goethite yields δ 2H values that reflect the hydrogen of the OH – phase in the mineral and are comparable to that made by IRMS and found in the literature. In contrast, δ 18O values on goethite reflect the oxygen in OH – groups bound to Fe (Fe-OH group), and not the oxygen bound only to Fe (Fe-O group) in the mineral crystal lattice, and may not be comparable to literature δ 18O values made by IRMS that reflect the total O in the mineral. TGA-IRIS presents the possibility to isotopically differentiate the various oxygen reservoirs in goethite, which may allow the mineral to be used as a single mineral geothermometer. As a result, TGA-IRIS measurements of hydration waters are likely to open new avenues and possibilities for research on hydrated minerals.« less

Impacts of Goethite Particles on UV Disinfection of Drinking Water

PubMed Central

Wu, Youxian; Clevenger, Thomas; Deng, Baolin

2005-01-01

A unique association between bacterial cells and small goethite particles (∼0.2 by 2 μm) protected Escherichia coli and Pseudomonas putida from UV inactivation. The protection increased with the particle concentration in the turbidity range of 1 to 50 nephelometric turbidity units and with the bacterium-particle attachment time prior to UV irradiation. The lower degree of bacterial inactivation at longer attachment time was mostly attributed to the particle aggregation surrounding bacteria that provided shielding from UV radiation. PMID:16000835

Hydroxylamine Promoted Goethite Surface Fenton Degradation of Organic Pollutants.

PubMed

Hou, Xiaojing; Huang, Xiaopeng; Jia, Falong; Ai, Zhihui; Zhao, Jincai; Zhang, Lizhi

2017-05-02

In this study, we construct a surface Fenton system with hydroxylamine (NH 2 OH), goethite (α-FeOOH), and H 2 O 2 (α-FeOOH-HA/H 2 O 2 ) to degrade various organic pollutants including dyes (methyl orange, methylene blue, and rhodamine B), pesticides (pentachlorophenol, alachlor, and atrazine), and antibiotics (tetracycline, chloramphenicol, and lincomycin) at pH 5.0. In this surface Fenton system, the presence of NH 2 OH could greatly promote the H 2 O 2 decomposition on the α-FeOOH surface to produce ·OH without releasing any detectable iron ions during the alachlor degradation, which was different from some previously reported heterogeneous Fenton counterparts. Moreover, the ·OH generation rate constant of this surface Fenton system was 10 2 -10 4 times those of previous heterogeneous Fenton processes. The interaction between α-FeOOH and NH 2 OH was investigated with using attenuated total reflectance Fourier transform infrared spectroscopy and density functional theory calculations. The effective degradation of organic pollutants in this surface Fenton system was ascribed to the efficient Fe(III)/Fe(II) cycle on the α-FeOOH surface promoted by NH 2 OH, which was confirmed by X-ray photoelectron spectroscopy analysis. The degradation intermediates and mineralization of alachlor in this surface Fenton system were then systematically investigated using total organic carbon and ion chromatography, liquid chromatography-mass spectrometry, and gas chromatography-mass spectrometry. This study offers a new strategy to degrade organic pollutants and also sheds light on the environmental effects of goethite.

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

Nano-sized structured layered positive electrode materials to enable high energy density and high rate capability lithium batteries

DOEpatents

Deng, Haixia; Belharouak, Ilias; Amine, Khalil

2012-10-02

Nano-sized structured dense and spherical layered positive active materials provide high energy density and high rate capability electrodes in lithium-ion batteries. Such materials are spherical second particles made from agglomerated primary particles that are Li.sub.1+.alpha.(Ni.sub.xCo.sub.yMn.sub.z).sub.1-tM.sub.tO.sub.2-dR.sub.d- , where M is selected from can be Al, Mg, Fe, Cu, Zn, Cr, Ag, Ca, Na, K, In, Ga, Ge, V, Mo, Nb, Si, Ti, Zr, or a mixture of any two or more thereof, R is selected from F, Cl, Br, I, H, S, N, or a mixture of any two or more thereof, and 0.ltoreq..alpha..ltoreq.0.50; 0

Molecular-Scale Study of Aspartate Adsorption on Goethite and Competition with Phosphate.

PubMed

Yang, Yanli; Wang, Shengrui; Xu, Yisheng; Zheng, Binghui; Liu, Jingyang

2016-03-15

Knowledge of the interfacial interactions between aspartate and minerals, especially its competition with phosphate, is critical to understanding the fate and transport of amino acids in the environment. Adsorption reactions play important roles in the mobility, bioavailability, and degradation of aspartate and phosphate. Attenuated total reflectance Fourier-transform infrared (ATR-FTIR) measurements and density functional theory (DFT) calculations were used to investigate the interfacial structures and their relative contributions in single-adsorbate and competition systems. Our results suggest three dominant mechanisms for aspartate: bidentate inner-sphere coordination involving both α- and γ-COO(-), outer-sphere complexation via electrostatic attraction and H-bonding between aspartate NH2 and goethite surface hydroxyls. The interfacial aspartate is mainly governed by pH and is less sensitive to changes of ionic strength and aspartate concentration. The phosphate competition significantly reduces the adsorption capacity of aspartate on goethite. Whereas phosphate adsorption is less affected by the presence of aspartate, including the relative contributions of diprotonated monodentate, monoprotonated bidentate, and nonprotonated bidentate structures. The adsorption process facilitates the removal of bioavailable aspartate and phosphate from the soil solution as well as from the sediment pore water and the overlying water.

The reactivity of Fe(II) associated with goethite formed during short redox cycles toward Cr(VI) reduction under oxic conditions

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

Tomaszewski, Elizabeth J.; Lee, Seungyeol; Rudolph, Jared

Chromium (Cr) is a toxic metal that causes a myriad of health problems and enters the environment as a result of anthropogenic activities and/or natural processes. The toxicity and solubility of chromium is linked to its oxidation state; Cr(III) is poorly soluble and relatively nontoxic, while Cr(VI) is soluble and a known carcinogen. Solid Fe(II) in iron-bearing minerals, such as pyrite, magnetite, and green rusts, reduce the oxidation state of chromium, reducing its toxicity and mobility. However, these minerals are not the only potential sources of solid-associated Fe(II) available for Cr(VI) reduction. For example, ferric (Fe(III)) (hydr)oxides, such as goethitemore » or hematite, can have Fe(II) in the solid without phase transformation; however, the reactivity of Fe(II) within Fe(III) (hydr)oxides with contaminants, has not been previously investigated. Here, we cyclically react goethite with dissolved Fe(II) followed by dissolved O2, leading to the formation of reactive Fe(II) associated with goethite. In separate reactors, the reactivity of this Fe(II) is probed under oxic conditions, by exposure to chromate (CrO42 -) after either one, two, three or four redox cycles. Cr is not present during redox cycling; rather, it is introduced to a subset of the solid after each oxidation half-cycle. Analysis of X-ray absorption near edge structure (XANES) spectra reveals that the extent of Cr(VI) reduction to Cr(III) depends not only on solid Fe(II) content but also surface area and mean size of ordered crystalline domains, determined by BET surface area analysis and X-ray diffraction (XRD), respectively. Shell-by-shell fitting of the extended X-ray absorption fine structure (EXAFS) spectra demonstrates chromium forms both single and double corner sharing complexes on the surface of goethite, in addition to sorbed Cr(III) species. Finally, transmission electron microscope (TEM) imaging and X-ray energy-dispersive spectroscopy (EDS) illustrate that Cr preferentially

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.

Transformation of goethite/ferrihydrite to hematite and maghemite under temperate humid conditions in Denmark

NASA Astrophysics Data System (ADS)

Nørnberg, P.; Finster, K.; Gunnlaugsson, H. P.; Jensen, S. K.; Merrison, J. P.; Vendelboe, A. L.

2012-04-01

At a number of sandy soil sites in Mid Jutland, Denmark, with iron content of 1-2%, very red spots (Munsell colour: dusky red 10R 3/4) of a few square meters are found. These spots are most likely due to burning events. After the fire ashes raised pH. This dispersed silt and clay size soil particles which were then transported with seepage water down into lower soil horizons. These particles contain hematite and maghemite due to influence of the fire. However, a long-standing unresolved question is how hematite and maghemite can also be present along with goethite and ferrihydrite, in the same geographical region, and in extended areas with high iron content (8-40 %) in the topsoil. Hematite and particularly maghemite would normally not be expected to form under the temperate humid Danish climate, but be interpreted as the result of high temperature as found in tropical regions or as seen in soils exposed to fire. The high iron content most likely has its origin in pyrite dissolution in top of the groundwater zone in deeper Miocene deposits. From there Fe2+ is brought to the surface by the groundwater, and in wells oxidized by meeting the atmosphere and precipitated as two line ferrihydrite. This is later transformed into goethite. However, along with these two minerals hematite and maghemite are present in the topsoil around the well area. Forest fires would be a likely explanation to the hematite and maghemite. But a body of evidence argues against these sites having been exposed to fire. 1) The pH in the topsoil is 3.6 - 4.8 and thus not raised by ashes. 2) No charcoal is present. 3) There is no indication of fire outside the high iron content areas. 4) Goethite is present along with hematite and maghemite in microparticles, and the mineralogical zonation produced in a forest fire is not seen. The natural sites contain a uniform mixture of goethite/ferrihydrite, hematite and maghemite down to 20 cm depth. An experimental forest fire left charcoal and ashes at

Adsorption and fractionation of a muck fulvic acid on kaolinite and goethite at pH 3.7,6, and 8

USGS Publications Warehouse

Namjesnik-Dejanovic, K.; Maurice, P.A.; Aiken, G.R.; Cabaniss, S.; Chin, Y.-P.; Pullin, M.J.

2000-01-01

Molecular weight (MW) of humic materials is a key factor controlling proton and metal binding and organic pollutant partitioning. Several studies have suggested preferential adsorption of higher MW, more aromatic moieties to mineral surfaces; quantification of such processes is fundamental to development of predictive models. We used high pressure size exclusion chromatography (HPSEC) to quantify MW changes upon adsorption of a muck fulvic acid (MFA) extracted from a peat deposit to kaolinite and goethite, at pH 3.7,6, and 8 at 22 ??C, I = 0.01 (NaC1), 24-h reaction time. MFA adsorption affinity was greater for goethite than for kaolinite. At concentrations less than the adsorption maximum (A(max)) for both adsorbents, the weight-average MW (M(w)) of MFA remaining in solution decreased by as much as several hundred Daltons relative to control samples, indicating preferential adsorption of the higher MW components. At concentrations more than A(max), M(w) of MFA in solution did not change appreciably. Although total adsorption decreased significantly as pH increased, fractionation as measured by change in M(w) remained similar, perhaps indicating greater selectivity for higher MW components at higher pH. Absorptivities at ?? = 280 nm normalized to mg C L-1 (??) suggested preferential adsorption of more aromatic moieties to kaolinite. ?? could not be used for goethite-reacted samples because high Fe concentrations in the aqueous phase brought about by goethite dissolution interfered with the spectroscopic analysis. Preliminary kinetic experiments suggested that smaller molecules adsorbed first and were replaced by larger molecules whose adsorption was thermodynamically favored.

The aqueous photolysis of ethylene glycol adsorbed on geothite

USGS Publications Warehouse

Cunningham, Kirkwood M.; Goldberg, Marvin C.; Weiner, E.R.

1985-01-01

Suspensions of goethite (α-FeOOH) were photolyzed in aerated ethylene glycol-water solutions at pH 6.5, with ultraviolet light in the wavelength range300–400 nm. Under these conditions, formaldehyde and glycolaldehyde were detected as photoproducts. Quantum yields of formaldehyde production ranged from 1.9 7times; 10-5 to 2.9 × 10-4 over the ethylene glycol concentration range of 0.002-2.0 mol/ℓ, and gave evidence that the reaction occurred at the goethite surface. Quantum yields of glycolaldehyde were 20% less than those of formaldehyde, and displayed a concentration-dependent relationship with ethylene glycol similar to that of formaldehyde. Immediately after photolysis, Fe2+ was measured to be 4.6 × 10-7 mol/ℓ in an aerated suspension containing 1.3 mol/ℓ ethylene glycol, and 8.5 × 10-6 mol/ℓ in the corresponding deoxygenated suspension. Glycolaldehyde was not generated in the deoxygenated suspensions. These results are consistent with a mechanism involving the transfer of an electron from an adsorbed ethylene glycol molecule to an excited state of Fe3+ (Iron[III]) in the goethite lattice, to produce Fe2+ and an organic cation. In a series of reactions involving O2, FeOOH, and Fe2+, the organic cation decomposes to form formaldehyde and the intermediate radicals “OH and” CH2OH. OH reacts further with ethylene glycol in the presence of O2to yield glycolaldehyde. Aqueous photolysis of ethylene glycol sorbed onto goethite is typical of reactions that can occur in the aquatic environment.

Degradation and Mineralization of Phenol Compounds with Goethite Catalyst and Mineralization Prediction Using Artificial Intelligence

PubMed Central

Tisa, Farhana; Davoody, Meysam; Abdul Raman, Abdul Aziz; Daud, Wan Mohd Ashri Wan

2015-01-01

The efficiency of phenol degradation via Fenton reaction using mixture of heterogeneous goethite catalyst with homogeneous ferrous ion was analyzed as a function of three independent variables, initial concentration of phenol (60 to 100 mg /L), weight ratio of initial concentration of phenol to that of H2O2 (1: 6 to 1: 14) and, weight ratio of initial concentration of goethite catalyst to that of H2O2 (1: 0.3 to 1: 0.7). More than 90 % of phenol removal and more than 40% of TOC removal were achieved within 60 minutes of reaction. Two separate models were developed using artificial neural networks to predict degradation percentage by a combination of Fe3+ and Fe2+ catalyst. Five operational parameters were employed as inputs while phenol degradation and TOC removal were considered as outputs of the developed models. Satisfactory agreement was observed between testing data and the predicted values (R2 Phenol = 0.9214 and R2TOC= 0.9082). PMID:25849556

Microwave-Assisted Synthesis of Goethite Nanoparticles Used for Removal of Cr(VI) from Aqueous Solution

PubMed Central

Kynicky, Jindrich; Adam, Vojtech

2017-01-01

The microwave-assisted synthesis of goethite nanoparticles has been studied. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), differential thermal analysis (DTA) and Brunauer–Emmett–Teller (BET) method. Goethite rod-like nanoparticles have been successfully synthesized in 10 min of microwave treating at 100 °C. Particle size is in the range from 30 to 60 nm in width and from 200 to 350 nm in length. BET analysis indicated that the surface area of the product is 158.31 m2g−1. The feasibility of Cr(VI) removal fromaqueous solution depends on the pH of the solution and contact time. The maximum adsorptionis reached at pH 4.0 and 540 min of contact time. The adsorption kinetics was analyzedby the pseudo-first- and second-order models and the results reveal that the adsorption process obeys the pseudo-second-order model. The adsorption data were fitted well with the Langmuir adsorption isotherm. PMID:28773142

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.

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

Surface chemistry of ferrihydrite: Part 1. EXAFS studies of the geometry of coprecipitated and adsorbed arsenate

USGS Publications Warehouse

Waychunas, G.A.; Rea, B.A.; Fuller, C.C.; Davis, J.A.

1993-01-01

EXAFS spectra were collected on both the As and Fe K-edges from samples of two-line ferrihydrite with adsorbed (ADS) and coprecipitated (CPT) arsenate prepared over a range of conditions and arsenate surface coverages. Spectra also were collected for arsenate adsorbed on the surfaces of three FeOOH crystalline polymorphs, ?? (goethite), ?? (akaganeite), and ?? (lepidocrocite), and as a free ion in aqueous: solution. Analyses of the As EXAFS show clear evidence for inner sphere bidentate (bridging) arsenate complexes on the ferrihydrite surface and on the surfaces of the crystalline FeOOH polymorphs. The bridging arsenate is attached to adjacent apices of edge-sharing Fe oxyhydroxyl octahedra. The arsenic-iron distance at the interface (3.28 ??0.01 A ??) is close to that expected for this geometry on the FeOOH polymorph surfaces, but is slightly shorter on the ferrihydrite surfaces (3.25 ?? 0.02 A ??). Mono-dentate arsenate linkages (3.60 ?? 0.03 A ??) also occur on the ferrihydrite, but are not generally observed on the crystalline FeOOH polymorphs. The proportion of monodentate bonds appears largest for adsorption samples with the smallest As Fe molar ratio. In all cases the arsenate tetrahedral complex is relatively undistorted with As-O bonds of 1.66 ?? 0.01 A ??. Precipitation of arsenate or scorodite-like phases was not observed for any samples, all of which were prepared at a pH value of 8. The Fe EXAFS results confirm that the Fe-Fe correlations in the ferrihydrite are progressively disrupted in the CPT samples as the As Fe ratio is increased. Coherent crystallite size is probably no more than 10 A?? in diameter and no Fe oxyhydroxyl octahedra corner-sharing linkages (as would be present in FeOOH polymorphs) are observed at the largest As Fe ratios. Comparison of the number and type of Fe-Fe neighbors with the topological constraints imposed by the arsenate saturation limit in the CPT samples (about 0.7 As Fe) indicates ferrihydrite units consisting mainly

[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.

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.

Modeling the adsorption of hydrogen, sodium, chloride and phthalate on goethite using a strict charge-neutral ion-exchange theory.

PubMed

Schulthess, Cristian P; Ndu, Udonna

2017-01-01

Simultaneous adsorption modeling of four ions was predicted with a strict net charge-neutral ion-exchange theory and its corresponding equilibrium and mass balance equations. An important key to the success of this approach was the proper collection of all the data, particularly the proton adsorption data, and the inclusion of variable concentrations of conjugate ions from the experimental pH adjustments. Using IExFit software, the ion-exchange model used here predicted the competitive retention of several ions on goethite by assuming that the co-adsorption or desorption of all ions occurred in the correct stoichiometries needed to maintain electroneutrality. This approach also revealed that the retention strength of Cl- ions on goethite increases in the presence of phthalate ions. That is, an anion-anion enhancement effect was observed. The retention of Cl- ions was much weaker than phthalate ions, and this also resulted in a higher sensitivity of the Cl- ions toward minor variations in the surface reactivity. The proposed model uses four goethite surface sites. The drop in retention of phthalate ions at low pH was fully described here as resulting from competitive Cl- reactions, which were introduced in increasing concentrations into the matrix as the conjugate base to the acid added to lower the pH.

Modeling the adsorption of hydrogen, sodium, chloride and phthalate on goethite using a strict charge-neutral ion-exchange theory

PubMed Central

Ndu, Udonna

2017-01-01

Simultaneous adsorption modeling of four ions was predicted with a strict net charge-neutral ion-exchange theory and its corresponding equilibrium and mass balance equations. An important key to the success of this approach was the proper collection of all the data, particularly the proton adsorption data, and the inclusion of variable concentrations of conjugate ions from the experimental pH adjustments. Using IExFit software, the ion-exchange model used here predicted the competitive retention of several ions on goethite by assuming that the co-adsorption or desorption of all ions occurred in the correct stoichiometries needed to maintain electroneutrality. This approach also revealed that the retention strength of Cl− ions on goethite increases in the presence of phthalate ions. That is, an anion-anion enhancement effect was observed. The retention of Cl− ions was much weaker than phthalate ions, and this also resulted in a higher sensitivity of the Cl− ions toward minor variations in the surface reactivity. The proposed model uses four goethite surface sites. The drop in retention of phthalate ions at low pH was fully described here as resulting from competitive Cl− reactions, which were introduced in increasing concentrations into the matrix as the conjugate base to the acid added to lower the pH. PMID:28464020

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

Multisite adsorption of cadmium on goethite

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

Venema, P.; Hiemstra, T.; Riemsdijk, W.H. van

1996-11-10

Recently a new general ion adsorption model has been developed for ion binding to mineral surfaces (Hiemstra and van Riemsdijk, 1996). The model uses the Pauling concept of charge distribution (CD) and is an extension of the multi-site complexation (MUSIC) approach. In the CD-MUSIC model the charge of an adsorbing ion that forms an inner sphere complex is distributed over its ligands, which are present in two different electrostatic planes. In this paper the authors have applied the CD-MUSIC model to the adsorption of metal cations, using an extended data set for cadmium adsorbing on goethite. The adsorption of cadmiummore » and the cadmium-proton exchange ratio were measured as function of metal ion concentration, pH, and ionic strength. The data could be described well, taking into account the surface heterogeneity resulting from the presence of two different crystal planes (the dominant 110 face and the minor 021 face). The surface species used in the model are consistent with recent EXAFS data. In accordance with the EXAFS results, high-affinity complexes at the 021 face were used in the model.« less

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.

Adsorption of Nucleic Acid/Protein Supramolecular Complexes on Goethite: The Influence of Solution Interactions on Behavior at the Solution-Mineral Interface

NASA Astrophysics Data System (ADS)

Schmidt, M.; Martinez, C. E.

2017-12-01

Adsorption of biomolecule rich supramolecular complexes onto mineral surfaces plays an important role in the development of organo-mineral associations in soils. In this study, a series of supramolecular complexes of a model nucleic acid (deoxyribonucleic acid (DNA)) and protein (bovine serum albumin (BSA)) are synthesized, characterized and exposed to goethite to probe their adsorption behavior. To synthesize DNA/BSA complexes, a fixed DNA concentration (0.1 mg/mL) was mixed with a range of BSA concentrations (0.025-0.5 mg/mL) in 5 mM KCl at pH=5.0. Circular dichroism spectroscopy demonstrates strong, cooperative, Hill-type binding between DNA and BSA (Ka= 4.74 x 105 M-1) with DNA saturation achieved when BSA concentration reaches 0.4 mg/mL. Dynamic light scattering measurements of DNA/BSA complexes suggest binding accompanies disruption of DNA-DNA intermolecular electrostatic repulsion, resulting in a decrease of the DNA slow relaxation mode with increasing amount of BSA. Zeta potential measurements show increasing amounts of BSA lead to a reduction of negative charge on DNA/BSA complexes, in line with light scattering results. In situ attenuated total reflectance Fourier transform infrared spectroscopic studies of adsorption of DNA/BSA complexes onto goethite show that complexation of BSA with DNA appears to hinder direct coordination of DNA backbone phosphodiester groups with goethite, relative to DNA by itself. Furthermore, increasing amount of BSA (up to 0.4 mg/mL) in DNA/BSA complexes enhances DNA adsorption, possibly as a result of reduced repulsion between adsorbed DNA helices. When BSA concentration exceeds 0.4 mg/mL, a decrease in adsorbed DNA is observed. We hypothesize that this discrepancy in behavior between systems with BSA concentrations below and above saturation of DNA is caused by initial fast adsorption of loosely associated BSA on goethite, restricting access to goethite surface sites. Overall, these results highlight the impact of solution

Cosmogenic 3He in hematite and goethite from Brazilian "canga" duricrust demonstrates the extreme stability of these surfaces

NASA Astrophysics Data System (ADS)

Shuster, David L.; Farley, Kenneth A.; Vasconcelos, Paulo M.; Balco, Greg; Monteiro, Hevelyn S.; Waltenberg, Kathryn; Stone, John O.

2012-05-01

Helium isotopes were measured in hematite and goethite samples from several lateritiric duricrusts (canga) developed on banded iron formations. These samples uniformly have high 3He concentrations which must arise from long periods of cosmic ray exposure. From coexisting phases from the Quadrilátero Ferrífero in east central Brazil, we determined the ratio of cosmogenic 3He in hematite to that of 21Ne in quartz to be 3.96 ± 0.19. Combined with best current estimates of the 21Ne production rate in quartz, this ratio implies a sea-level high latitude (SLHL) 3He production rate in hematite of 68.1 ± 8.1 atoms/g/yr; from the chemical composition we estimate the 3He production rate in goethite to be ~ 5% higher. We use these production rate estimates to interpret 3He concentrations measured in goethite and hematite from a ~ 10 m depth profile collected from a surface canga in Carajás, in the Amazon basin of Brazil. We find that the Carajás canga has experienced a very low rate of surface erosion (~ 0.16-0.54 m/Myr) over at least the last few millions of years. This iron-rich canga surface is remarkably resistant to erosion despite its location in a wet tropical environment. Details of the depth profile suggest that despite its stability, the canga has also been internally dynamic (translocation of material; solution and reprecipitation) over million-year timescales.

Aluminum Coprecipitates with Fe (hydr)oxides: Does Isomorphous Substitution of Al3plus for Fe3plus in Goethite Occur

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

E Bazilevskaya; D Archibald; M Aryanpour

2011-12-31

Iron (hydr)oxides are common in natural environments and typically contain large amounts of impurities, presumably the result of coprecipitation processes. Coprecipitation of Al with Fe (hydr)oxides occurs, for example, during alternating reduction-oxidation cycles that promote dissolution of Fe from Fe-containing phases and its re-precipitation as Fe-Al (hydr)oxides. We used chemical and spectroscopic analyses to study the formation and transformation of Al coprecipitates with Fe (hydr)oxides. In addition, periodic density functional theory (DFT) computations were performed to assess the structural and energetic effects of isolated or clustered Al atoms at 8 and 25 mol% Al substitution in the goethite structure. Coprecipitatesmore » were synthesized by raising the pH of dilute homogeneous solutions containing a range of Fe and Al concentrations (100% Fe to 100% Al) to 5. The formation of ferrihydrite in initial suspensions with {<=}20 mol% Al, and of ferrihydrite and gibbsite in initial suspensions with {>=}25 mol% Al was confirmed by infrared spectroscopic and synchrotron-based X-ray diffraction analyses. While base titrations showed a buffer region that corresponded to the hydrolysis of Fe in initial solutions with {<=}25 mol% Al, all of the Al present in these solutions was retained by the solid phases at pH 5, thus indicating Al coprecipitation with the primary Fe hydroxide precipitate. In contrast, two buffer regions were observed in solutions with 30 mol% Al (at pH {approx}2.25 for Fe{sup 3+} and at pH {approx}4 for Al{sup 3+}), suggesting the formation of Fe and Al (hydr)oxides as two separate phases. The Al content of initial coprecipitates influenced the extent of ferrihydrite transformation and of its transformation products as indicated by the presence of goethite, hematite and/or ferrihydrite in aged suspensions. DFT experiments showed that: (i) optimized unit cell parameters for Al-substituted goethites (8 and 25 Mol% Al) in clustered arrangement (i

Miocene weathering environments in Western Australia-Inferences from the abundance and 13C/12C of Fe(CO3)OH in CID goethite

NASA Astrophysics Data System (ADS)

Fritz, Tyler O.; Yapp, Crayton J.

2018-04-01

The channel iron deposits (CID) of the Hamersley Province in Western Australia are dominated by pedogenic goethite/hematite-rich ooids and pisoids that were transported to, and deposited in, the meandering channels of Miocene rivers. Information about the Miocene weathering environments that produced the Fe(III) oxides is archived in the mole fraction (X) and δ13C of the Fe(CO3)OH component in solid solution in oolitic CID goethite (α-FeOOH). Values of X and δ13C were measured for 12 oolitic goethite samples from different depths in two cores drilled in CID of the Robe Formation of Mesa J. The weighted-average plateau values of X ranged from 0.0098 to 0.0334, which suggest ambient CO2 concentrations that ranged from ∼50,000 ppm V to perhaps as much as ∼200,000 ppm V at the time of goethite crystallization. In a vadose zone characterized by in situ production of CO2 with steady-state Fickian diffusive transport of the gas, such concentrations would correspond to modeled soil respiration rates (Q) ranging from about 10 to 30 mmol/m2/h. Values for Q of about 10 mmol/m2/h are reported for soils in modern tropical forests with MAP ≥ ∼2000 mm. However, model-derived values of Q that exceed 15 mmol/m2/h are larger than observed in modern systems. This could indicate that some of the CID goethites crystallized in conditions that were phreatic or near phreatic rather than vadose. The δ13C values of the Fe(CO3)OH component in these 12 CID samples ranged from -24.0‰ to -22.3‰, which are among the most negative measured to date. If they reflect steady-state diffusive transport of CO2 in vadose environments, the soil CO2 would have been derived from a source with δ13C values that ranged from ∼-31‰ to -29‰. If, on the other hand, the goethites crystallized in a nearly phreatic environment that was moderately acidic, the inferred δ13C of the ancient CO2 source would have been about -27.6‰ to -25.8‰. In either case, the δ13C values point to in situ

Detonation Synthesis of Alpha-Variant Silicon Carbide

NASA Astrophysics Data System (ADS)

Langenderfer, Martin; Johnson, Catherine; Fahrenholtz, William; Mochalin, Vadym

2017-06-01

A recent research study has been undertaken to develop facilities for conducting detonation synthesis of nanomaterials. This process involves a familiar technique that has been utilized for the industrial synthesis of nanodiamonds. Developments through this study have allowed for experimentation with the concept of modifying explosive compositions to induce synthesis of new nanomaterials. Initial experimentation has been conducted with the end goal being synthesis of alpha variant silicon carbide (α-SiC) in the nano-scale. The α-SiC that can be produced through detonation synthesis methods is critical to the ceramics industry because of a number of unique properties of the material. Conventional synthesis of α-SiC results in formation of crystals greater than 100 nm in diameter, outside nano-scale. It has been theorized that the high temperature and pressure of an explosive detonation can be used for the formation of α-SiC in the sub 100 nm range. This paper will discuss in detail the process development for detonation nanomaterial synthesis facilities, optimization of explosive charge parameters to maximize nanomaterial yield, and introduction of silicon to the detonation reaction environment to achieve first synthesis of nano-sized alpha variant silicon carbide.

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.

Occurrence and Characterization Microstructure of Iron Impurities in Halloysite.

PubMed

Liu, Rong; Yan, Chunjie; Wang, Hongquan; Xiao, Guoqi; Tu, Dong

2015-09-01

The quality of the clays and over all halloysite are mostly associated with minor amounts of ferruginous impurities content, since this element gives an undesirable reddish color to the halloysite mineral. Hence, finding out the modes of occurrence of iron in halloysite is of prime importance in the value addition and optimum utilization of halloysite. In order to analyze the occurrence of iron impurities in halloysite, Transmission Electron Microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were combined with wet chemical analysis methods to study the low-grade halloysite. The results indicated that the mineral phases of iron impurities in the concentrates are mainly composed of amounts of magnetite, goethite and hematite. Two types of occurrences for iron impurities have been found. One is single crystalline mineral consist in the halloysite, which contains three different phases of Goethite FeO(OH) (44.75%), Magnetite Fe3O4 (27.43%) and Hematite Fe2O3 (31.96%). The other is amorphous Fe-Al-Si glial materials. This study is of significance in the theoretical research on the halloysite mineralogy and in the developmental practice of halloysite in coal measures.

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.

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.

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.

Goethite colloid enhanced Pu transport through a single saturated fracture in granite.

PubMed

Lin, Jianfeng; Dang, Haijun; Xie, Jinchuan; Li, Mei; Zhou, Guoqing; Zhang, Jihong; Zhang, Haitao; Yi, Xiaowei

2014-08-01

α-FeOOH, a stable iron oxide in nature, can strongly absorb the low-solubility plutonium (Pu) in aquifers. However, whether Pu transports though a single saturated fracture can be enhanced in the presence of α-FeOOH colloids remains unknown. Experimental studies were carried out to evaluate Pu mobilization at different water flow velocity, as affected by goethite colloids with various concentrations. Goethite nanorods were used to prepare (α-FeOOH)-associated Pu suspensions with α-FeOOH concentration of (0-150) mgL(-1). The work experimentally evidenced that α-FeOOH colloid does enhance transport of Pu through fractured granites. The fraction of mobile (239)Pu (RPu, m=41.5%) associated with the α-FeOOH of an extremely low colloid concentration (0.2mgL(-1)) is much larger than that in absence of α-FeOOH (RPu, m=6.98%). However, plutonium mobility began to decrease when α-FeOOH concentration was increased to 1.0mgL(-1). On the other hand, the fraction of mobile Pu increased gradually with the water flow velocity. Based on the experimental data, the mechanisms underlying the (α-FeOOH)-associated plutonium transport are comprehensively discussed in view of its dynamic deposition onto the granite surfaces, which is decided mainly by the relative interaction between the colloid particle and the immobile surface. This interaction is a balance of electrostatic force (may be repulsive or attractive), the van der Walls force, and the shear stress of flow. Copyright © 2014 Elsevier B.V. All rights reserved.

Iron Isotopes in Spherical Hematite and Goethite Concretions from the Navajo Sandstone (Utah, USA): A Prospective Study for "Martian Blueberries"

NASA Astrophysics Data System (ADS)

Busigny, V.; Dauphas, N.

2006-03-01

Iron isotopes of terrestrial hematite and goethite concretions provide clues on fluid transport, reservoir sizes, redox variations and biotic versus abiotic processes. This opens several avenues of research for future work on Martian blueberries.

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.

Ab Initio Molecular Dynamics of Uranium Incorporated in Goethite (α-FeOOH): Interpretation of X-ray Absorption Spectroscopy of Trace Polyvalent Metals.

PubMed

Kerisit, Sebastien; Bylaska, Eric J; Massey, Michael S; McBriarty, Martin E; Ilton, Eugene S

2016-11-21

Incorporation of economically or environmentally consequential polyvalent metals into iron (oxyhydr)oxides has applications in environmental chemistry, remediation, and materials science. A primary tool for characterizing the local coordination environment of such metals, and therefore building models to predict their behavior, is extended X-ray absorption fine structure spectroscopy (EXAFS). Accurate structural information can be lacking yet is required to constrain and inform data interpretation. In this regard, ab initio molecular dynamics (AIMD) was used to calculate the local coordination environment of minor amounts of U incorporated in the structure of goethite (α-FeOOH). U oxidation states (VI, V, and IV) and charge compensation schemes were varied. Simulated trajectories were used to calculate the U L III -edge EXAFS function and fit experimental EXAFS data for U incorporated into goethite under reducing conditions. Calculations that closely matched the U EXAFS of the well-characterized mineral uraninite (UO 2 ), and constrained the S 0 2 parameter to be 0.909, validated the approach. The results for the U-goethite system indicated that U(V) substituted for structural Fe(III) in octahedral uranate coordination. Charge balance was achieved by the loss of one structural proton coupled to addition of one electron into the solid (-1 H + , +1 e - ). The ability of AIMD to model higher energy states thermally accessible at room temperature is particularly relevant for protonated systems such as goethite, where proton transfers between adjacent octahedra had a dramatic effect on the calculated EXAFS. Vibrational effects as a function of temperature were also estimated using AIMD, allowing separate quantification of thermal and configurational disorder. In summary, coupling AIMD structural modeling and EXAFS experiments enables modeling of the redox behavior of polyvalent metals that are incorporated in conductive materials such as iron (oxyhydr)oxides, with

Ab Initio Molecular Dynamics of Uranium Incorporated in Goethite (α-FeOOH): Interpretation of X-ray Absorption Spectroscopy of Trace Polyvalent Metals

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

Kerisit, Sebastien; Bylaska, Eric J.; Massey, Michael S.

2016-11-21

Incorporation of economically or environmentally consequential polyvalent metals into iron (oxyhydr)oxides has applications in environmental chemistry, remediation, and materials science. A primary tool for characterizing the local coordination environment of such metals, and therefore building models to predict their behavior, is extended X-ray absorption fine structure spectroscopy (EXAFS). Accurate structural information can be lacking, yet is required to constrain and inform data interpretation. In this regard, ab initio molecular dynamics (AIMD) was used to calculate the local coordination environment of minor amounts of U incorporated in the structure of goethite (α-FeOOH). U oxidation state (VI, V, and IV) and chargemore » compensation scheme (CCS) were varied. Simulated trajectories were used to calculate the U LIII-edge EXAFS function and fit experimental EXAFS data for U incorporated into goethite under reducing conditions. Calculations that closely matched the U EXAFS of the well-characterized mineral uraninite (UO2), and constrained the S02 parameter to be 0.909, validated the approach. The results for the U-goethite system indicated that U(V) substituted for structural Fe(III) in octahedral uranate coordination. Charge balance was achieved by the loss of one structural proton coupled to injection of one electron into the solid (–1 H+, + 1 e-). The ability of AIMD to model higher-energy states thermally accessible at room temperature is particularly relevant for protonated systems such as goethite, where proton transfers between adjacent octahedra had a dramatic effect on the calculated EXAFS. Vibrational effects as a function of temperature were also estimated using AIMD, allowing separate quantification of thermal and configurational disorder. In summary, coupling AIMD structural modeling and EXAFS experiments enables modeling of the redox behavior of polyvalent metals that are incorporated in conductive materials such as iron (oxyhydr

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.

Late Mio-Pliocene chemical weathering of the Yulong porphyry Cu deposit in the eastern Tibetan Plateau constrained by goethite (U-Th)/He dating: Implication for Asian summer monsoon

NASA Astrophysics Data System (ADS)

Deng, Xiao-Dong; Li, Jian-Wei; Shuster, David L.

2017-08-01

Chemical weathering has provided a potentially important feedback between tectonic forcing and climate evolution of the Asian continent, although precise constraints on the timing and history of weathering are only variably documented. Here, we use goethite (U-Th)/He and 4He/3He geochronology to constrain the timing and rates of chemical weathering at the Yulong porphyry Cu deposit on the eastern Tibetan Plateau. Goethite grains have (U-Th)/He ages ranging from 6.73 ± 0.51 to 0.53 ± 0.04 Ma that correlate with independent paleoclimatic proxies inferred from supergene Mn-oxides and loess deposits under variable tectonic regimes and vegetation zones over the southeastern Asia. This correlation indicates that regional climatic conditions, especially monsoonal precipitation, controlled chemical weathering and goethite precipitation in a vast area of southeastern Asia. The goethite ages suggest that the Asian summer monsoon was relatively strong from 7 to 4.6 Ma, but weakened between 4.6 and 4 Ma, and then significantly intensified from 4 to 2 Ma. The precipitation ages of goethites collected along a 100-m-thick weathering profile decrease with depth, and indicate a downward propagation of the weathering front at rates of <6.7, 53.5 ± 10.8, and 4.8 ± 0.6 m/Ma during the intervals of 7-4, 4-2, and 2-0.7 Ma, respectively. The rapid propagation of weathering front during 4-2 Ma was caused by abrupt lowering of the water table, which was possibly related to local surface uplift or reorganization of the river systems in southeastern Tibet during this period.

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.

Do goethite surfaces really control the transport and retention of multi-walled carbon nanotubes in chemically heterogeneous porous media?

USDA-ARS?s Scientific Manuscript database

Transport and retention behavior of multiwalled carbon nanotubes (MWCNTs) was studied in mixtures of negatively charged quartz sand (QS) and positively charged goethite-coated sand (GQS) to assess the role of chemical heterogeneity. The linear equilibrium sorption model provided a good description o...

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.

Influence of Oxalate on Ni Fate during Fe(II)-Catalyzed Recrystallization of Hematite and Goethite.

PubMed

Flynn, Elaine D; Catalano, Jeffrey G

2018-06-05

During biogeochemical iron cycling at redox interfaces, dissolved Fe(II) induces the recrystallization of Fe(III) oxides. Oxalate and other organic acids promote dissolution of these minerals and may also induce recrystallization. These processes may redistribute trace metals among the mineral bulk, mineral surface, and aqueous solution. However, the impact of interactions among organic acids, dissolved Fe(II), and iron oxide minerals on trace metal fate in such systems is unclear. The present study thus explores the effect of oxalate on Ni release from and incorporation into hematite and goethite in the absence and presence of Fe(II). When Ni is initially structurally incorporated into the iron oxides, both oxalate and dissolved Fe(II) promote the release of Ni to aqueous solution. When both species are present, their effects on Ni release are synergistic at pH 7 but inhibitory at pH 4, indicating that cooperative and competitive interactions vary with pH. In contrast, oxalate suppresses Ni incorporation into goethite and hematite during Fe(II)-induced recrystallization, decreasing the proportion of Ni substituting in a mineral structure by up to 36%. These observations suggest that at redox interfaces oxalate largely enhances trace metal mobility. In such settings, oxalate, and likely other organic acids, may thus enhance micronutrient availability and inhibit contaminant sequestration.

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

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.

Changes in water extractable organic matter during incubation of forest floor material in the presence of quartz, goethite and gibbsite surfaces

NASA Astrophysics Data System (ADS)

Heckman, Katherine; Vazquez-Ortega, Angelica; Gao, Xiaodong; Chorover, Jon; Rasmussen, Craig

2011-08-01

The release of dissolved organic matter (DOM) from forest floor material constitutes a significant flux of C to the mineral soil in temperate forest ecosystems, with estimates on the order of 120-500 kg C ha -1 year -1. Interaction of DOM with minerals and metals results in sorptive fractionation and stabilization of OM within the soil profile. Iron and aluminum oxides, in particular, have a significant effect on the quantity and quality of DOM transported through forest soils due to their high surface area and the toxic effects of dissolved aluminum on microbial communities. We directly examined these interactions by incubating forest floor material, including native microbiota, for 154 days in the presence of (1) goethite (α-FeOOH), (2) gibbsite (γ-Al(OH) 3), and (3) quartz (α-SiO 2) sand (as a control). Changes in molecular and thermal properties of water extractable organic matter (WEOM, as a proxy for DOM) were evaluated. WEOM was harvested on days 5, 10, 20, 30, 60, 90, and 154, and examined by thermogravimetry/differential thermal analysis (TG/DTA) and diffuse reflectance Fourier transform infrared (DRIFT) spectroscopy. Results indicated significant differences in WEOM quality among treatments, though the way in which oxide surfaces influenced WEOM properties did not seem to change significantly with increasing incubation time. Dissolved organic C concentrations were significantly lower in WEOM from the oxide treatments in comparison to the control treatment. Incubation with goethite produced WEOM with mid-to-high-range thermal lability that was depleted in both protein and fatty acids relative to the control. The average enthalpy of WEOM from the goethite treatment was significantly higher than either the gibbsite or control treatment, suggesting that interaction with goethite surfaces increases the energy content of WEOM. Incubation with gibbsite produced WEOM rich in thermally recalcitrant and carboxyl-rich compounds in comparison to the control

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.

Twenty-Eight-Day Repeated Inhalation Toxicity Study of Nano-Sized Neodymium Oxide in Male Sprague-Dawley Rats

PubMed Central

Kim, Yong-Soon; Lim, Cheol-Hong; Shin, Seo-Ho; Kim, Jong-Choon

2017-01-01

Neodymium is a future-oriented material due to its unique properties, and its use is increasing in various industrial fields worldwide. However, the toxicity caused by repeated exposure to this metal has not been studied in detail thus far. The present study was carried out to investigate the potential inhalation toxicity of nano-sized neodymium oxide (Nd2O3) following a 28-day repeated inhalation exposure in male Sprague-Dawley rats. Male rats were exposed to nano-sized Nd2O3-containing aerosols via a nose-only inhalation system at doses of 0 mg/m3, 0.5 mg/m3, 2.5 mg/m3, and 10 mg/m3 for 6 hr/day, 5 days/week over a 28-day period, followed by a 28-day recovery period. During the experimental period, clinical signs, body weight, hematologic parameters, serum biochemical parameters, necropsy findings, organ weight, and histopathological findings were examined; neodymium distribution in the major organs and blood, bronchoalveolar lavage fluid (BALF), and oxidative stress in lung tissues were analyzed. Most of the neodymium was found to be deposited in lung tissues, showing a dose-dependent relationship. Infiltration of inflammatory cells and pulmonary alveolar proteinosis (PAP) were the main observations of lung histopathology. Infiltration of inflammatory cells was observed in the 2.5 mg/m3 and higher dose treatment groups. PAP was observed in all treatment groups accompanied by an increase in lung weight, but was observed to a lesser extent in the 0.5 mg/m3 treatment group. In BALF analysis, total cell counts, including macrophages and neutrophils, lactate dehydrogenase, albumin, interleukin-6, and tumor necrosis factor-alpha, increased significantly in all treatment groups. After a 4-week recovery period, these changes were generally reversed in the 0.5 mg/m3 group, but were exacerbated in the 10 mg/m3 group. The lowest-observed-adverse-effect concentration of nano-sized Nd2O3 was determined to be 0.5 mg/m3, and the target organ was determined to be the lung

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.

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.

Stochastic Simulation of Isotopic Exchange Mechanisms for Fe(II)-Catalyzed Recrystallization of Goethite.

PubMed

Zarzycki, Piotr; Rosso, Kevin M

2017-07-05

Understanding Fe(II)-catalyzed transformations of Fe(III)-(oxyhydr)oxides is critical for correctly interpreting stable isotopic distributions and for predicting the fate of metal ions in the environment. Recent Fe isotopic tracer experiments have shown that goethite undergoes rapid recrystallization without phase change when exposed to aqueous Fe(II). The proposed explanation is oxidation of sorbed Fe(II) and reductive Fe(II) release coupled 1:1 by electron conduction through crystallites. Given the availability of two tracer exchange data sets that explore pH and particle size effects (e.g., Handler et al. Environ. Sci. Technol. 2014 , 48 , 11302 - 11311 ; Joshi and Gorski Environ. Sci. Technol. 2016 , 50 , 7315 - 7324 ), we developed a stochastic simulation that exactly mimics these experiments, while imposing the 1:1 constraint. We find that all data can be represented by this model, and unifying mechanistic information emerges. At pH 7.5 a rapid initial exchange is followed by slower exchange, consistent with mixed surface- and diffusion-limited kinetics arising from prominent particle aggregation. At pH 5.0 where aggregation and net Fe(II) sorption are minimal, that exchange is quantitatively proportional to available particle surface area and the density of sorbed Fe(II) is more readily evident. Our analysis reveals a fundamental atom exchange rate of ∼10 -5 Fe nm -2 s -1 , commensurate with some of the reported reductive dissolution rates of goethite, suggesting Fe(II) release is the rate-limiting step in the conduction mechanism during recrystallization.

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.

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

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.

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

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...

2H and 27Al solid-state NMR study of the local environments in Al-doped 2-line ferrihydrite, goethite, and lepidocrocite

DOE PAGES

Kim, Jongsik; Ilott, Andrew J.; Middlemiss, Derek S.; ...

2015-05-13

Although substitution of aluminum into iron oxides and oxyhydroxides has been extensively studied, it is difficult to obtain accurate incorporation levels. Assessing the distribution of dopants within these materials has proven especially challenging because bulk analytical techniques cannot typically determine whether dopants are substituted directly into the bulk iron oxide or oxyhydroxide phase or if they form separate, minor phase impurities. These differences have important implications for the chemistry of these iron-containing materials, which are ubiquitous in the environment. In this work, 27Al and 2H NMR experiments are performed on series of Al-substituted goethite, lepidocrocite, and 2-line ferrihydrite in ordermore » to develop an NMR method to track Al substitution. The extent of Al substitution into the structural frameworks of each compound is quantified by comparing quantitative 27Al MAS NMR results with those from elemental analysis. Magnetic measurements are performed for the goethite series to compare with NMR measurements. Static 27Al spin–echo mapping experiments are used to probe the local environments around the Al substituents, providing clear evidence that they are incorporated into the bulk iron phases. As a result, predictions of the 2H and 27Al NMR hyperfine contact shifts in Al-doped goethite and lepidocrocite, obtained from a combined first-principles and empirical magnetic scaling approach, give further insight into the distribution of the dopants within these phases.« less

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

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.

Adsorption of Selenium and Strontium on Goethite: EXAFS Study and Surface Complexation Modeling of the Ternary Systems.

PubMed

Nie, Zhe; Finck, Nicolas; Heberling, Frank; Pruessmann, Tim; Liu, Chunli; Lützenkirchen, Johannes

2017-04-04

Knowledge of the geochemical behavior of selenium and strontium is critical for the safe disposal of radioactive wastes. Goethite, as one of the most thermodynamically stable and commonly occurring natural iron oxy-hydroxides, promisingly retains these elements. This work comprehensively studies the adsorption of Se(IV) and Sr(II) on goethite. Starting from electrokinetic measurements, the binary and ternary adsorption systems are investigated and systematically compared via batch experiments, EXAFS analysis, and CD-MUSIC modeling. Se(IV) forms bidentate inner-sphere surface complexes, while Sr(II) is assumed to form outer-sphere complexes at low and intermediate pH and inner-sphere complexes at high pH. Instead of a direct interaction between Se(IV) and Sr(II), our results indicate an electrostatically driven mutual enhancement of adsorption. Adsorption of Sr(II) is promoted by an average factor of 5 within the typical groundwater pH range from 6 to 8 for the concentration range studied here. However, the interaction between Se(IV) and Sr(II) at the surface is two-sided, Se(IV) promotes Sr(II) outer-sphere adsorption, but competes for inner-sphere adsorption sites at high pH. The complexity of surfaces is highlighted by the inability of adsorption models to predict isoelectric points without additional constraints.

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.

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.

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

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.

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.

D/H of late Miocene meteoric waters in Western Australia: Paleoenvironmental conditions inferred from the δD of (U-Th)/He-dated CID goethite

NASA Astrophysics Data System (ADS)

Yapp, Crayton J.; Shuster, David L.

2017-09-01

Nineteen (U-Th)/He ages were determined for eight samples from a core drilled in an ore-grade channel iron deposit (CID) of the Robe Pisolite (Robe Formation) of Mesa J in Western Australia. With one exception, uncorrected ages of the analyzed aliquots range from 6.7(±0.4) Ma to 30.2(±3.1) Ma, while molar ratios of Th/U range from 0.42 to 5.06. The exception is an aliquot with an apparent age of 2.7 Ma and Th/U of 5.70. A three-component mixing model involving one generation of goethite and two generations of hematite suggests that the age of crystallization of the oolitic goethites is ∼7(±1) Ma. If so, the goethites have effectively been closed systems for ∼7 million years and should preserve a stable hydrogen isotope record of late Miocene rainfall in the vicinity of Mesa J. Cenozoic movement of the Australian continent had placed Mesa J and environs in the subtropics at a paleolatitude of about 29 °S during the late Miocene. Al-adjusted δD values of oolitic goethite in the eight CID samples range from -153‰ to -146‰ and imply that the δD of the late Miocene meteoric waters ranged from -61‰ to -53‰, with an average of -56‰. These relatively negative δD values might indicate that near-coastal, late Miocene rain was derived primarily from summer-season tropical cyclones with storm tracks that extended into the subtropics of western Australia. The postulated late Miocene tropical cyclones would have occurred more often and/or exhibited greater intensity at a paleolatitude of 29 °S than is the case for modern sites at approximately 30 °S on the west coast of Australia (e.g., Perth). Higher fluxes of meteoric water in the Miocene summers would have facilitated dissolution and removal of BIF-sourced silica with concomitant enrichment in oxidized Fe. Moreover, wetter late Miocene summers could have promoted multiple cycles of microbially mediated dissolution and recrystallization of Fe(III) oxides in the aerobic systems. The oolitic textures may

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.

Fractionation of aquatic natural organic matter upon sorption to goethite and kaolinite

USGS Publications Warehouse

Meier, M.; Namjesnik-Dejanovic, K.; Maurice, P.A.; Chin, Y.-P.; Aiken, G.R.

1999-01-01

Natural organic matter (NOM) consists of a complex mixture of organic molecules; previous studies have suggested that preferential sorption of higher molecular weight, more hydrophobic, and more aromatic components may lead to fractionation of the NOM pool upon passage through porous media. Our work expands upon previous studies by quantifying the change in solution-phase weight average molecular weight (M(w)) upon sorption of bulk (rather than isolated) surface water NOM from the Suwannee River (SR) and the Great Dismal Swamp (GDS) to goethite and kaolinite at different sorption densities and at pH 4, 22??C. High pressure size exclusion chromatography (HPSEC) was used to quantify changes in M(w) upon sorption, and molar absorptivities at ?? = 280 nm were used to approximate changes in solution NOM aromaticity. Two SR water samples were used, with M(w) = 2320 and 2200 Da; a single GDS sample was used, with M(w) = 1890 Da. The SR NOM was slightly more hydrophobic and aromatic. These differences were reflected in greater sorption of SR NOM than GDS NOM. Both surface water NOMs showed a much greater affinity for goethite than for kaolinite. HPSEC analysis of the NOM remaining in solution after 24 h reaction time with geothite revealed that the largest changes in solution phase M(w)s (decreases by 900-1700 Da) occurred at relatively low equilibrium sorbate concentrations (approximately 5-20 mg C 1-1); the decrease in solution M(w) suggested that reactive surface sites were occupied disproportionately by large and intermediate size NOM moieties. At higher equilibrium NOM concentrations (>20 mg C 1-1), as percent adsorption decreased, M(w) in solution was similar to original samples. A smaller decrease in solution NOM M(w) (300-500 Da at 10-20 mg C 1-1 ~ 100 Da at > 20 mg) also occurred upon sorption to kaolinite. Overall, our results showed that factors (as related to NOM composition, clay mineral surface properties, and position along the sorption isotherm) which

Interactions of low molecular weight aromatic acids and amino acids with goethite, kaolinite and bentonite with or without organic matter coating

NASA Astrophysics Data System (ADS)

Gao, Jiajia; Jansen, Boris; Cerli, Chiara; Kalbitz, Karsten

2015-04-01

Interaction of organic matter molecules with the soil's solid phase is a key factor influencing the stabilization of carbon in soils and thus forms a crucial aspect of the global carbon cycle. While subject of much research attention so far, we still have much to learn about such interactions at the molecular level; in particular in the light of competition between different classes of organic molecules and in the presence of previously adsorbed soil organic matter. We studied the interaction of a group of low molecular weight (LMW) aromatic acids (salicylic, syringic, vanillic and ferulic acid) and amino acids (lysine, glutamic, leucine and phenylalanine) on goethite, kaolinite and bentonite with and without previously adsorbed dissolved organic matter (DOM). For this we used batch experiments at pH = 6.0 where some of the organic compounds were positively charged (i.e. lysine) or negatively charged (i.e. glutamic and salicylic acid) while the minerals also displayed positively (i.e. goethite) or negatively charged surfaces (i.e. bentonite). We found much higher sorption of salicylic acid and lysine than other compounds. On the bare minerals we found a great variety of sorption strength, with salicylic acid strongly adsorbed, while syringic, vanillic and ferulic acid showed little or no adsorption. For the amino acids, protonated lysine showed a stronger affinity to negatively charged kaolinite and bentonite than other amino acids. While deprotonated glutamic acid showed the strongest adsorption on goethite. Leucine and phenylalanine showed hardly any adsorption on any of the minerals. When present concurrently, amino acids decreased the sorption of salicylic acid on the three types of mineral, while the presence of LMW aromatic acids increased the sorption of lysine on kaolinite and bentonite and the sorption of glutamic acid on goethite. The presence of previously adsorbed DOM reduced the sorption of salicylic acid and lysine. The results confirm that

EXAFS study of mercury(II) sorption to Fe- and Al-(hydr)oxides - II. Effects of chloride and sulfate

USGS Publications Warehouse

Kim, C.S.; Rytuba, J.J.; Brown, Gordon E.

2004-01-01

Common complexing ligands such as chloride and sulfate can significantly impact the sorption of Hg(II) to particle surfaces in aqueous environmental systems. To examine the effects of these ligands on Hg(II) sorption to mineral sorbents, macroscopic Hg(II) uptake measurements were conducted at pH 6 and [Hg]i=0.5 mM on goethite (??-FeOOH), ??-alumina (??-Al2O3), and bayerite (??-Al(OH)3) in the presence of chloride or sulfate, and the sorption products were characterized by extended X-ray absorption fine structure (EXAFS) spectroscopy. The presence of chloride resulted in reduced uptake of Hg(II) on all three substrates over the Cl- concentration ([Cl-]) range 10-5 to 10-2 M, lowering Hg surface coverages on goethite, ??-alumina, and bayerite from 0.42 to 0.07 ??mol/m2, 0.06 to 0.006 ??mol/m2, and 0.55 to 0.39 ??mol/m2 ([Cl -]=10-5 to 10-3 M only), respectively. This reduction in Hg(II) uptake is primarily a result of the formation of stable, nonsorbing aqueous HgCl2 complexes in solution, limiting the amount of free Hg(II) available to sorb. At higher [Cl-] beam reduction of Hg(II) to Hg(I) was observed, resulting in the possible formation of aqueous Hg2Cl2 species and the precipitation of calomel, Hg 2Cl2(s). The presence of sulfate caused enhanced Hg(II) uptake over the sulfate concentration ([SO42-]) range 10-5 to 0.9 M, increasing Hg surface coverages on goethite, ??-alumina, and bayerite from 0.39 to 0.45 ??mol/m2, 0.11 to 0.38 ??mol/m2, and 0.36 to 3.33 ??mol/m2, respectively. This effect is likely due to the direct sorption or accumulation of sulfate ions at the substrate interface, effectively reducing the positive surface charge that electrostatically inhibits Hg(II) sorption. Spectroscopic evidence for ternary surface complexation was observed in isolated cases, specifically in the Hg-goethite-sulfate system at high [SO42-] and in the Hg-goethite-chloride system. ?? 2003 Elsevier Inc. All rights reserved.

Aggregation Rates of Sediments (Montmorillonite, Kaolinite, Illite and Goethite) with the Enveloped Φ6 Bacteriophage

NASA Astrophysics Data System (ADS)

Katz, A.; Block, K. A.; Peña, S.; Alimova, A.; Gottlieb, P.

2015-12-01

The interaction between sediments and viruses has been studied extensively from the prospective of virus survivability and infectivity. However, the role of soil organisms, including viruses in C and N sequestration in soil has not been studied as extensively. Φ6, a member of the cystoviridae family, is a bacteriophage that infects Pseudomonas syringae, a common plant pathogen known to readily form biofilms.The small mineral fraction (< 0.2 μm) of soil and Φ6 are colloidal particles, therefore aggregation can be explained by DLVO (Derjaguin & Landau, Verwey & Overbeek) theory. Time-resolved visible-light turbidity measurements were used to calculate the heteroaggregation rates of Φ6 with the sediments. Samples were suspended in a low-concentration cation buffer so that the kinetics were in the reaction limited cluster aggregation (RLCA) regime in where the probability of two particles adhering after collision is determined by the interaction forces between the particles.At neutral pH to slightly acidic pH, Φ6 is slightly negatively charged; montmorillonite and illite are negatively charged; and kaolinite and goethite are positively charged. In isolation, neither Φ6 nor the sediments aggregated in the modified buffer. However, in mixtures, Φ6 and montmorillonite, and Φ6 and illite, exhibited increases in turbidity, indicating heteroaggregation. Neither Φ6 and kaolinite, nor Φ6 and goethite, exhibited increased turbidity upon mixing indicating little or no aggregation. These results suggest that the interaction of the virus with the sediments is governed by hydrophobic rather than electrostatic forces. Heteroaggregation rates were calculated from the time rate of change of the turbidity.

Dehydrogenation of goethite in Earth’s deep lower mantle

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

Hu, Qingyang; Kim, Duck Young; Liu, Jin

2017-01-31

The cycling of hydrogen influences the structure, composition, and stratification of Earth’s interior. Our recent discovery of pyrite-structured iron peroxide (designated as the P phase) and the formation of the P phase from dehydrogenation of goethite FeO 2H implies the separation of the oxygen and hydrogen cycles in the deep lower mantle beneath 1,800 km. Here we further characterize the residual hydrogen, x, in the P-phase FeO 2Hx. Using a combination of theoretical simulations and high-pressure–temperature experiments, we calibrated the x dependence of molar volume of the P phase. Within the current range of experimental conditions, we observed a compositionalmore » range of P phase of 0.39 < x < 0.81, corresponding to 19–61% dehydrogenation. Increasing temperature and heating time will help release hydrogen and lower x, suggesting that dehydrogenation could be approaching completion at the high-temperature conditions of the lower mantle over extended geological time. Our observations indicate a fundamental change in the mode of hydrogen release from dehydration in the upper mantle to dehydrogenation in the deep lower mantle, thus differentiating the deep hydrogen and hydrous cycles.« less

Relationship between chemistry, microstructure and mechanical properties of alpha-silicon aluminum oxynitride

NASA Astrophysics Data System (ADS)

Shuba, Roman

The aim of this thesis was to improve the mechanical properties of Y-alpha-SiAlON ceramics by controlling microstructure and tailoring grain boundary composition. Three properties of importance for engineering applications were targeted: strength retention and oxidation resistance at high temperature, fracture toughness at room temperature, and machinability. As a result of this work, several ceramics with one or more of the above properties optimized have been developed. The performance of Si3N4/SiAlON-based ceramics at high (>1000 degree C) temperature is generally limited by the softening of grain-boundary glass. Refractory alpha-SiAlONs was obtained by three methods: reducing residual liquid by minimizing nitride powder oxidation during processing, promoting liquid/SiAlON conversion by adding excess AlN, and improving refractoriness by incorporating La2O3 into glass. Ceramics thus, obtained featured excellent room-temperature strength (1050 MPa) and high-temperature strength (650 MPa at 1300 degree C), as well as good oxidation resistance. In all cases grain growth was inhibited, which resulted in a relatively low toughness (5--7 MPa x m1/2). In-situ toughened Y-alpha-SiAlON (9 MPa x m1/2) was obtained through growth of large elongated grains with low debonding strength. This was achieved by introducing seed crystals to the starting powder mixtures, in addition to using sintering aids and dopants. Additives modified the properties of grain boundary glass, while dopants lowered the strength of glass/grain interface. Through the use of nanosized turbostratic BN precursor obtained via pyrolysis of melamine borate salt, which yielded finely dispersed hexagonal BN particles in alpha-SiAlON, high-strength (800 MPa) Y-alpha-SiAlON/BN composites, machinable using WC/Co tools, were also fabricated.

Effect of ionic strength on barium transport in porous media

NASA Astrophysics Data System (ADS)

Prigiobbe, V.; Ye, Z.

2017-12-01

Hydraulic fracturing (or fracking) is a well stimulation technique used to extract resourcesfrom a low permeability formation. During the operation large volumes of brine, rich ofhazardous chemicals, are produced. Spills of brine from a well or a pit might negativelyimpact underground water resources and one of the major concerns is for the migrationof radionuclides, such as, e.g., radium (Ra2+), into the shallow subsurface [1]. However, thetransport behaviour of Ra2+ through a reactive porous medium under conditions typical of abrine, i.e., high salinity, is not well understood, yet. Here, a study on the transport behaviour ofbarium (Ba2+, congener of radium) through a porous medium containing a common mineralsuch as goethite (FeO(OH)) is presented [2]. Batch and column flood tests were carried out atconditions resembling the produced water, i.e., large values of ionic strength (I), namely, 1to 3 mol/kg. The measurements were described with the triple layer surface complexationmodel coupled with the Pitzer activity coefficient method and a reactive transport model,in the case of the transport tests. The experimental results show that the adsorption of Ba2+onto FeO(OH) increases with pH but decreases with I and it becomes negligible at the brineconditions. Moreover, even if isotherms show adsorption at large I, at the same conditionsduring transport, Ba2+ travels without retardation through the FeO(OH) porous medium. The triple layer model agrees very well with all batch data but it cannot capture wellthe transport test, in particular, at large I values (Figure 1). This may suggest that thechemical reactions at the solid-liquid interface cannot describe well the adsorption of Ba2+onto FeO(OH) at large salinity. Finally, observations in this study suggest that in the case of a produced water spill, barium and potentially its congeners, namely, radium, calcium,magnesium, and strontium, contained in the brine may travel at the average flow velocity through a soil

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.

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

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.

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.

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.

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

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.

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.

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

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...

Silicic acid competes for dimethylarsinic acid (DMA) immobilization by the iron hydroxide plaque mineral goethite.

PubMed

Kersten, Michael; Daus, Birgit

2015-03-01

A surface complexation modeling approach was used to extend the knowledge about processes that affect the availability of dimethylarsinic acid (DMA) in the soil rhizosphere in presence of a strong sorbent, e.g., Fe plaques on rice roots. Published spectroscopic and molecular modeling information suggest for the organoarsenical agent to form bidentate-binuclear inner-sphere surface complexes with Fe hydroxides similar to the inorganic As oxyanions. However, since also the ubiquitous silicic acid oxyanion form the same bidentate binuclear surface complexes, our hypothesis was that it may have an effect on the adsorption of DMA by Fe hydroxides in soil. Our experimental batch equilibrium data show that DMA is strongly adsorbed in the acidic pH range, with a steep adsorption edge in the circumneutral pH region between the DMA acidity constant (pKa=6.3) and the point of zero charge value of the goethite adsorbent (pHpzc=8.6). A 1-pK CD-MUSIC surface complexation model was chosen to fit the experimental adsorption vs. pH data. The same was done for silicic acid batch equilibrium data with our goethite adsorbent. Both model parameters for individual DMA and silicic acid adsorption were then merged into one CD-MUSIC model to predict the binary DMA+Si adsorption behavior. Silicic acid (500 μM) was thus predicted by the model to strongly compete for DMA with up to 60% mobilization of the latter at a pH6. This model result could be verified subsequently by experimental batch equilibrium data with zero adjustable parameters. The thus quantified antagonistic relation between DMA and silicic acid is discussed as one of factors to explain the increase of the DMA proportion in rice grains as observed upon silica fertilization of rice fields. Copyright © 2014 Elsevier B.V. All rights reserved.

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

Single-molecule study of thymidine glycol and i-motif through the alpha-hemolysin ion channel

NASA Astrophysics Data System (ADS)

He, Lidong

Nanopore-based devices have emerged as a single-molecule detection and analysis tool for a wide range of applications. Through electrophoretically driving DNA molecules across a nanosized pore, a lot of information can be received, including unfolding kinetics and DNA-protein interactions. This single-molecule method has the potential to sequence kilobase length DNA polymers without amplification or labeling, approaching "the third generation" genome sequencing for around $1000 within 24 hours. alpha-Hemolysin biological nanopores have the advantages of excellent stability, low-noise level, and precise site-directed mutagenesis for engineering this protein nanopore. The first work presented in this thesis established the current signal of the thymidine glycol lesion in DNA oligomers through an immobilization experiment. The thymidine glycol enantiomers were differentiated from each other by different current blockage levels. Also, the effect of bulky hydrophobic adducts to the current blockage was investigated. Secondly, the alpha-hemolysin nanopore was used to study the human telomere i-motif and RET oncogene i-motif at a single-molecule level. In Chapter 3, it was demonstrated that the alpha-hemolysin nanopore can differentiate an i-motif form and single-strand DNA form at different pH values based on the same sequence. In addition, it shows potential to differentiate the folding topologies generated from the same DNA sequence.

Effect of interactions between Co(2+) and surface goethite layer on the performance of α-FeOOH coated hollow fiber ceramic ultrafiltration membranes.

PubMed

Zhu, Zhiwen; Zhu, Li; Li, Jianrong; Tang, Jianfeng; Li, Gang; Hsieh, Yi-Kong; Wang, TsingHai; Wang, Chu-Fang

2016-03-15

The consideration of water energy nexus inspires the environmental engineering community to pursue a more sustainable strategy in the wastewater treatment. One potential response would be to enhance the performance of the low-pressure driven filtration system. To reach this objective, it is essential to have a better understanding regarding the surface interaction between the target substance and the surface of membrane. In this study, the hollow fiber ceramic membranes were coated with a goethite layer in order to enhance the Co(2+) rejection. Experimental results indicate that higher Co(2+) rejections are always accompanied with the significant reduction in the permeability. Based on the consideration of electroviscous effect, the surface interactions including the induced changes in viscosity, pore radius and Donnan effect in the goethite layer are likely responsible for the pH dependent behaviors in the rejection and permeability. These results could be valuable references to develop the filtration system with high rejection along with acceptable degree of permeability in the future. Copyright © 2015 Elsevier Inc. All rights reserved.

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.

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.

Surface Behavior of Iron Sulfide Ore during Grinding with Alumina Media

NASA Astrophysics Data System (ADS)

Martín, Reyes P.; Elia, Palácios B.; Patiño, Francisco C.; Escudero, Ramiro G.; Mizraim, Uriel Flores G.; Reyes, Iván A. D.; Palazuelos, Laura Angeles

This research was conducted to study the oxidation and surface modification of pyrite in an inert mill and alumina grinding media at different pH values. The extent and progress of the oxidation function of milling time, by measuring some physicochemical variables, zeta potential (ZP), infrared analysis and monitoring. The results indicate pyrite oxidation during grinding, releasing iron and sulfur ions to the solution increasing its concentration with the initial pH and the milling time, the ORP and DO decrease the grinding time, on the other hand presents negative values ZP pH of 9, 11 and 12, whereas at pH 5, 7 and 13, the ZP is positive, FTIR generally detect the presence of free sulfate ion molecule 1084 cm-1, goethite with the absorption band at about 794 cm-1, also occurs in a band assigned to 470 cm-1 lepidocrocite oxy iron hydroxide γ- FeOOH, nucleated species or formed during milling.

From iron(III) precursor to magnetite and vice versa

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

Gotic, M., E-mail: gotic@irb.hr; Jurkin, T.; Music, S.

2009-10-15

The syntheses of nanosize magnetite particles by wet-chemical oxidation of Fe{sup 2+} have been extensively investigated. In the present investigation the nanosize magnetite particles were synthesised without using the Fe(II) precursor. This was achieved by {gamma}-irradiation of water-in-oil microemulsion containing only the Fe(III) precursor. The corresponding phase transformations were monitored. Microemulsions (pH {approx} 12.5) were {gamma}-irradiated at a relatively high dose rate of {approx}22 kGy/h. Upon 1 h of {gamma}-irradiation the XRD pattern of the precipitate showed goethite and unidentified low-intensity peaks. Upon 6 h of {gamma}-irradiation, reductive conditions were achieved and substoichiometric magnetite ({approx}Fe{sub 2.71}O{sub 4}) particles with insignificantmore » amount of goethite particles found in the precipitate. Hydrated electrons (e{sub aq}{sup -}), organic radicals and hydrogen gas as radiolytic products were responsible for the reductive dissolution of iron oxide in the microemulsion and the reduction Fe{sup 3+} {yields} Fe{sup 2+}. Upon 18 h of {gamma}-irradiation the precipitate exhibited dual behaviour, it was a more oxidised product than the precipitate obtained after 6 h of {gamma}-irradiation, but it contained magnetite particles in a more reduced form ({approx}Fe{sub 2.93}O{sub 4}). It was presumed that the reduction and oxidation processes existed as concurrent competitive processes in the microemulsion. After 18 h of {gamma}-irradiation the pH of the medium shifted from the alkaline to the acidic range. The high dose rate of {approx}22 kGy/h was directly responsible for this shift to the acidic range. At a slightly acidic pH a further reduction of Fe{sup 3+} {yields} Fe{sup 2+} resulted in the formation of more stoichiometric magnetite particles, whereas the oxidation conditions in the acidic medium permitted the oxidation Fe{sup 2+} {yields} Fe{sup 3+}. The Fe{sup 3+} was much less soluble in the acidic medium and it

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...

Redox characterization of the Fe(II)-catalyzed transformation of ferrihydrite to goethite

NASA Astrophysics Data System (ADS)

Jones, Adele M.; Collins, Richard N.; Waite, T. David

2017-12-01

The reduction potential of Fe(II)-Fe(III) (oxyhydr)oxide systems provides an important control on the biogeochemical cycling of redox-sensitive elements such as carbon and nitrogen as well as trace metals and organic contaminants in natural systems. As such, an in-depth understanding of the factors controlling the reduction potential of such systems is critical to predicting the likely transformation, transport and fate of these species in natural and perturbed environments. In this study the mineralogy and reduction potential of ferrihydrite suspensions at pH 6.50 and pH 7.00 were determined over the course of their Fe(II)-catalyzed transformation to lepidocrocite and goethite using X-ray absorption spectroscopy and mediated electrochemical approaches. The measured reduction potentials were compared to those of analogous Fe(II)-Fe(III) (oxyhydr)oxide suspensions reacted for 5 min containing pure ferrihydrite (Fh), lepidocrocite (L) and goethite (Gt). The reduction potentials of the pure Fe(II)-Fe(III) (oxyhydr)oxide suspensions were, respectively, +47.5, -13.5 and -122.3 mV vs. SHE at pH 6.5, and -22.9, -84.1 and -189.7 mV vs. SHE at pH 7. These values are in good agreement with reduction potentials calculated using the Nernst equation and reported thermodynamic solubility products indicating that these suspensions had reached equilibrium within 5 min. The reduction potential of the pH 6.50 Fe(II)-ferrihydrite suspension decreased from +47.4 mV to -126.4 mV over a week, and from -20.1 mV to -188.4 mV (all vs. SHE) after 24 h at pH 7. The changes in reduction potential over time matched well to those calculated from the relative proportion of each pure Fe(III) (oxyhydr)oxide present suggesting that Fe3+ activity was influenced by the mix of iron oxides present rather than the most insoluble solid species. Finally, evidence is provided that adsorbed Fe(II) has the capacity to reduce a significantly larger fraction of a reducible species than the aqueous Fe

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.

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.

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.

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

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.

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.

A piezoelectric immunosensor for the detection of alpha-fetoprotein using an interface of gold/hydroxyapatite hybrid nanomaterial.

PubMed

Ding, Yanjun; Liu, Jia; Wang, Hua; Shen, Guoli; Yu, Ruqin

2007-04-01

The ideal immobilization methods that are suitable for binding immuno-active materials with high efficiency onto the sensing surface are the key target to pursue in the current biosensor design. In this paper, a new hybrid material formed by assembling gold nanoparticles (GNP) onto nano-sized hydroxyapatite (HA) has been employed for the interface design of piezoelectric immunosensor, on which the antibodies were bound. The detection performances of the resulting immunosensor were investigated by use of the antibody-antigen model system of alpha-Fetoprotein (AFP), an important indicator in the diagnosis of clinical cancers. The hybrid material was characterized by the UV-vis spectroscopy, the SEM and TEM measurements. The frequency and electrochemical impedance responses characteristics for the processes of immobilization and immunoreaction of anchored anti-AFP antibodies were studied in detail. The immunoresponse of the proposed immunosensor was compared with those antibodies immobilized by using HA or GNP alone. It was found that the developed sensing interface has some advantages such as the activation-free immobilization and the high antigen-binding activities of antibodies. The as-prepared immunosensor can allow for the determination of AFP in the concentration range of 15.3-600.0ngml(-1). Such an interface design with the nano-sized hybrid materials should be tailored as a new alternative used for biosensor design.

The relationship between structural stability and electrochemical performance of multi-element doped alpha nickel hydroxide

NASA Astrophysics Data System (ADS)

Miao, Chengcheng; Zhu, Yanjuan; Huang, Liangguo; Zhao, Tengqi

2015-01-01

The multi-element doped alpha nickel hydroxide has been prepared by supersonic co-precipitation method. Three kinds of samples A, B and C are prepared by chemically coprecipitating Ni/Al, Ni/Al/Mn and Ni/Al/Mn/Yb, respectively. Inductively coupled plasma atomic emission spectroscopy (ICP-AES), Particle size distribution (PSD) measurement, X-ray diffraction (XRD), scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FT-IR) are used to characterize the physical properties of the synthesized α-Ni(OH)2 samples, such as chemical composition, morphology, structural stability of the crystal. The results show that all samples are nano-sized materials and the interlayer spacing becomes larger and the structural stability becomes better with the increase of doped elements and doped ratio. The prepared alpha nickel hydroxide samples are added into micro-sized beta nickel hydroxide to form biphase electrode materials for Ni-MH battery. The electrochemical characterization of the biphase electrodes, including cyclic voltammetry (CV) and charge/discharge test, are also performed. The results demonstrate that the biphase electrode with sample C exhibits better electrochemical reversibility and cyclic stability, higher charge efficient and discharge potential, larger proton diffusion coefficient (5.81 × 10-12 cm2 s-1) and discharge capacity (309.0 mAh g-1). Hence, it indicates that all doped elements can produce the synergic effect and further improve the electrochemical properties of the alpha nickel hydroxide.

Mössbauer spectroscopy on Mars: goethite in the Columbia Hills at Gusev crater

NASA Astrophysics Data System (ADS)

Klingelhöfer, G.; Degrave, E.; Morris, R. V.; van Alboom, A.; de Resende, V. G.; de Souza, P. A.; Rodionov, D.; Schröder, C.; Ming, D. W.; Yen, A.

2005-11-01

In January 2004 the USA space agency NASA landed two rovers on the surface of Mars, both carrying the Mainz Mössbauer spectrometer MIMOS II. The instrument on the Mars-Exploration-Rover (MER) Spirit analyzed soils and rocks on the plains and in the Columbia Hills of Gusev crater landing site on Mars. The surface material in the plains have an olivine basaltic signature [1, 5] suggesting physical rather than chemical weathering processes present in the plains. The Mössbauer signature for the Columbia Hills surface material is very different ranging from nearly unaltered material to highly altered material. Some of the rocks, in particular a rock named Clovis, contain a significant amount of the Fe oxyhydroxide goethite, α-FeOOH, which is mineralogical evidence for aqueous processes because it is formed only under aqueous conditions. In this paper we describe the analysis of these data using hyperfine field distributions (HFD) and discuss the results in comparison to terrestrial analogues.

Unraveling climatic changes from intra-profile variation in oxygen and hydrogen isotopic composition of goethite and kaolinite in laterites: An integrated study from Yaou, French Guiana

NASA Astrophysics Data System (ADS)

Girard, Jean-Pierre; Freyssinet, Philippe; Chazot, Gilles

2000-02-01

An integrated study of O and H isotopes in the lateritic profile of Yaou, French Guiana, was undertaken to investigate the usefulness of stable isotopes as tracers of climatic changes in continental environments. The studied profile is composed of a 27 m thick saprolite, mostly developed in the past under wet-and-dry tropical climate in association with a duricrust, overlain by a 3 m thick yellow latosol formed more recently under present equatorial hot and humid climate. δ 18O-δD values determined for weathering goethite (pseudomorphs after pyrite) and kaolinite (microcrystalline clay groundmass) throughout the 30 m deep profile reflect formation temperatures consistent with present (25°C) and realistic past climatic temperatures (20°C-30°C), indicating that weathering minerals formed in isotopic equilibrium with their genetic environment and were not subjected to significant isotope exchange after formation. A distinct shift downward (2‰ for δ 18O, 15‰ for δD) from low to high δ 18O-δD values occurs around 20 m depth in the saprolite. It is interpreted as recording the change from the past tropical to the present equatorial climate. Goethite and kaolinite in the 5-10 m thick saprolite interval immediately above the active basement weathering front are in isotopic equilibrium with modern water and must have formed under present equatorial-humid conditions. In contrast, goethite and kaolinite found higher up in the saprolite and in the duricrust formed in the past under tropical wet and dry climate from waters distinctly depleted in 18O and D relative to modern water. The marked depletion of paleo-meteoric water at Yaou most likely reflects a more contrasted or "monsoonal" character of the ancient tropical climate. The present study shows that ancient weathering minerals in lateritic profiles preserve their δ 18O-δD values and carry a time signal. The time signal is best expressed in minerals formed rapidly at the weathering front and not subjected

Mineralogical effects of an experimental forest fire on a goethite/ferrihydrite soil - an attempt to solve the presence of hematite and maghemite in topsoils in a temperate region

NASA Astrophysics Data System (ADS)

Nørnberg, Per; Vendelboe, Anders L.; Gunnlaugsson, Haraldur P.; Merrison, Jonathan P.; Finster, Kai; Jensen, Svend K.

2010-05-01

Isolated soil spots, a few square metres in size, as red as Munsell colour 10R ¾ are found in Denmark. These spots are well known as places that have been exposed to fire. However, a long-standing unresolved puzzle is the presence of extended areas with high iron content (8-40 %) where goethite and ferrihydrite are present in the topsoil along with hematite and maghemite. Hematite and particularly maghemite would normally not be expected to occur under the temperate humid Danish climate, but be interpreted as the result of high temperature as found in tropical areas or after forest fires. However, a body of evidence argues against these sites having been exposed to fire. In an attempt to get closer to an explanation of this iron mineralogy, an experimental forest fire was produced. The results showed a clear mineralogical zonation down to 10 cm depth. This was not observed at the natural sites, which contained a uniform mixture of goethite/ferrihydrite, hematite and maghemite down to 20 cm depth. The experimental forest fire furthermore left charcoal and ashes at the topsoil, produced high pH and decreased organic matter content, all of which is in contrast to the natural sites. Physical and chemical date as well as XRD, Mössbauer spectroscopic data and TEM micrographs from the sites will be presented. The conclusion from this work is that the mineralogy of these sites is not consistent with exposure to fire, but may rather result from long term transformation within a reducing environment, possibly involving microorganisms. References: Nørnberg, P., Vendelboe, A.L., Gunnlaugsson, H.P., Merrison, J.P., Finster, K., Jensen, S.K. 2009 Mineralogy after an experimental forest fire on Quaternary soil goethite, compared with a hematite, maghemite, goethite containing topsoil. Clay Minerals, 44, 239-247. Nørnberg, P., Gunnlaugsson, H.P., Merrison, J.P., Vendelboe, A.L. 2009: Salten Skov I: A Martian dust analogue. Planetary and Space Science, 57, 628-631. Nørnberg, P

Prevalence of -alpha(3.7) and alpha alpha alpha(anti3.7) alleles in sickle cell trait and beta-thalassemia patients in Mexico.

PubMed

Nava, María Paulina; Ibarra, Bertha; Magaña, María Teresa; de la Luz Chávez, María; Perea, F Javier

2006-01-01

The aim of this study was to determine the frequency of alpha-globin gene mutations in three groups of Mexican unrelated individuals. The first two groups were normal and sickle cell trait individuals from the Costa Chica region, a place with a 12.8% frequency of HbS carriers, and the third group comprised of Mexican mestizo patients with beta-thalassemia. We searched for -alpha(3.7) and -alpha(4.2) alpha(+)-thalassemia deletion alleles, as well as the alpha alpha alpha(anti3.7) triplication through long-gap PCR. The alleles -alpha(3.7) and alpha alpha alpha(anti3.7) were found in the heterozygote state only; 19% of the normal subjects had the -alpha(3.7) allele, and 2% showed the alpha alpha alpha(anti3.7) allele. In individuals with the sickle cell trait, 17% had the -alpha(3.7) deletion, and the alpha alpha alpha(anti3.7) triplication was observed in 3% of these individuals. We revealed that 16% of the subjects with beta-thalassemia showed the -alpha(3.7) deletion and 28% the alpha alpha alpha(anti3.7) triplication. The -alpha(4.2) deletion was not detected in any individual. The frequency of the -alpha(3.7) allele was roughly the same in the three groups studied; this can be explained by the fact that the three groups have common genes from Africa and the Mediterranean, where a high prevalence of alpha(+)-thalassemia has been observed. To our knowledge, the frequency of alpha alpha alpha(anti3.7) triplication observed in the Mexican beta-thalassemia patients is the highest reported. As the -alpha(3.7) and alpha alpha alpha(anti3.7) alleles are very common in our selected populations, we believe that there is a need to investigate systematically the alpha-globin gene mutations in all hemoglobinopathies in the Mexican population.

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.

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.

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).

Jellyfish mesogloea collagen. Characterization of molecules as alpha 1 alpha 2 alpha 3 heterotrimers.

PubMed

Miura, S; Kimura, S

1985-12-05

The mesogloea collagen of a primitive animal, the jellyfish Stomolophus nomurai, belonging to the class Scyphozoa in the Coelenterata, was studied with respect to its chain structure. Most of the mesogloea collagen was solubilized by limited digestion with pepsin and isolated by selective precipitation at 0.9 m NaCl in 0.5 M acetic acid. Upon denaturation, the pepsin-solubilized collagen produced three distinct alpha chains, alpha 1, alpha 2, and alpha 3, in comparable amounts which were separable by CM-cellulose chromatography. The nonidentity of these alpha chains was confirmed by amino acid and carbohydrate analyses and peptide mapping. Furthermore, the introduction of intramolecular cross-links into native molecules by formaldehyde yielded a large proportion of gamma 123 chain with chain structure alpha 1 alpha 2 alpha 3, as judged by chromatographic behavior and peptide maps. We concluded that mesogloea collagen is comprised of alpha 1 alpha 2 alpha 3 heterotrimers and is chemically like vertebrate Type V collagen. On the other hand, sea anemone mesogloea collagen from the class Anthozoa was previously reported to comprise (alpha)3 homotrimers (Katzman, R. L., and Kang, A. H. (1972) J. Biol. Chem. 247, 5486-5489). On the basis of these findings, we assume that alpha 1 alpha 2 alpha 3 heterotrimers arose in evolution with the divergence of Scyphozoa and Anthozoa.

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

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

The effect of biogenic Fe(II) on the stability and sorption of Co(II)EDTA 2- to goethite and a subsurface sediment

NASA Astrophysics Data System (ADS)

Zachara, John M.; Smith, Steven C.; Fredrickson, James K.

2000-04-01

Laboratory experiments were conducted with suspensions of goethite (α-FeOOH) and a subsurface sediment to assess the influence of bacterial iron reduction on the fate of Co(II)EDTA 2-, a representative metal-ligand complex of intermediate stability (log K Co(II)EDTA = 17.97). The goethite was synthetic (ca. 55 m 2/g) and the sediment was a Pleistocene age, Fe(III) oxide-containing material from the Atlantic coastal plain (Milford). Shewanella alga strain BrY, a dissimilatory iron reducing bacterium (DIRB), was used to promote Fe(III) oxide reduction. Sorption isotherms and pH adsorption edges were measured for Co 2+, Fe 2+, Co(II)EDTA 2-, and Fe(II)EDTA 2- on the two sorbents in 0.001 mol/L Ca(ClO 4) 2 to aid in experiment interpretation. Anoxic suspensions of the sorbents in PIPES buffer at pH 6.5-7.0 were spiked with Co(II)EDTA 2- (10 -5 mol/L, 60Co and 14EDTA labeled), inoculated with BrY (1-6 × 10 8 organisms/mL), and the headspace filled with a N 2/H 2 gas mix. The experiments were conducted under non-growth conditions. The medium did not contain PO 43- (with one exception), trace elements, or vitamins. The tubes were incubated under anoxic conditions at 25°C for time periods in excess of 100 d. Replicate tubes were sacrificed and analyzed at desired time periods for pH, Fe(II) TOT, Fe (aq)2+, 60Co, and 14EDTA. Abiotic analogue experiments were conducted where Fe (aq)2+ was added in increasing concentration to Co(II)EDTA 2-/mineral suspensions to simulate the influence of bacterial Fe(II) evolution. The DIRB generated Fe(II) from both goethite and the Milford sediment that was strongly sorbed by mineral surfaces. Aqueous Fe 2+ increased during the experiment as surfaces became saturated; Fe (aq)2+ induced the dissociation of Co(II)EDTA 2- into a mixture of Co 2+, Co(II)EDTA 2-, and Fe(II)EDTA 2- (log K Fe(II)EDTA = 15.98). The extent of dissociation of Co(II)EDTA 2- was greater in the subsurface sediment because it sorbed Fe(II) less strongly than did

The uptake of HNO3 on meteoric smoke analogues

NASA Astrophysics Data System (ADS)

Frankland, Victoria L.; James, Alexander D.; Feng, Wuhu; Plane, John M. C.

2015-05-01

The uptake of HNO3, H2O, NO2 and NO was studied on meteoric smoke particle analogues using a low-pressure Knudsen cell operating at 295 K. The analogues used were olivine (MgFeSiO4) and a haematite/goethite (Fe2O3/FeO(OH)) mixture synthesised by the sol-gel process. For uptake on MgFeSiO4, the following uptake coefficients were obtained: γ(HNO3)=(1.8±0.3)×10-3, γ(H2O)=(4.0±1.3)×10-3, γ(NO2)=(5.7±0.2)×10-4 and γ(NO)<3×10-4. γ(HNO3) did not show a dependence on the mass of MgFeSiO4 in the Knudsen cell (when varied by a factor of 6) implying that, because of relatively efficient uptake, HNO3 is removed only by near-surface particles. This was corroborated by application of a surface uptake model. Saturating the MgFeSiO4 particles with water vapour before exposing them to NO2 increased γ(NO2) to (2.1±0.7)×10-3, but had a very small effect on γ(HNO3). For uptake on Fe2O3/FeO(OH), γ(HNO3)=(1.5±0.2)×10-3. These results were then included in a whole atmosphere chemistry-climate model, which shows that the heterogeneous removal on meteoric smoke particles in the winter polar vortex between 30 and 60 km appears to provide an important sink for HNO3.

Progesterone's 5 alpha-reduced metabolite, 3 alpha,5 alpha-THP, mediates lateral displacement of hamsters.

PubMed

Frye, Cheryl A; Rhodes, Madeline E

2005-03-15

5 alpha-Pregnan-3 alpha-ol-20-one (3 alpha,5 alpha-THP), progesterone (P4)'s 5 alpha-reduced, 3 alpha-hydroxysteroid oxidoreduced product, facilitates lordosis of rodents in part via agonist-like actions at GABA(A)/benzodiazepine receptor complexes in the ventral tegmental area (VTA). Whether 3 alpha,5 alpha-THP influences another reproductively-relevant behavior, lateral displacement, of hamsters was investigated. Lateral displacement is the movement that female hamsters make with their perineum towards male-like tactile stimulation. This behavior facilitates, and is essential for, successful mating. Hamsters in behavioral estrus had greater lateral displacement responses when endogenous progestin levels were elevated compared to when progestin levels were lower. Administration of P4, a prohormone for 3 alpha,5 alpha-THP, dose-dependently (500 > 200 > 100, 50, or 0 microg) enhanced lateral displacement of ovariectomized hamsters that had been primed with SC estradiol benzoate (5 or 10 microg). Inhibiting P4's metabolism to 3 alpha,5 alpha-THP by co-administering finasteride, a 5 alpha-reductase inhibitor, or indomethacin, a 3 alpha-hydroxysteroid oxidoreductase inhibitor, either systemically or to the VTA, significantly decreased lateral displacement and midbrain progestin levels of naturally receptive or hormone-primed hamsters compared to controls. These data suggest that lateral displacement is progestin-sensitive and requires the formation of 3 alpha,5 alpha-THP in the midbrain VTA.

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.

Synthesis of methyl 3-O-alpha-D-mannopyranosyl-alpha-D-talopyranoside and methyl 3-O-alpha-D-talopyranosyl-alpha-D-talopyranoside.

PubMed

Dubey, R; Jain, R K; Abbas, S A; Matta, K L

1987-08-01

Methyl 2-O-benzyl-3-O-(2,3,4,6-tetra-O-acetyl-alpha-D-mannopyranosyl)-alpha- D-mannopyranoside (4) and methyl 2-O-benzyl-3-O-alpha-D-mannopyranosyl-alpha-D-mannopyranoside (6) were prepared from a common intermediate, namely, methyl 2-O-benzyl-4,6-O-benzylidene-3-O-(2,3,4,6-tetra-O-acetyl-alpha-D- mannopyranosyl)-alpha-D-mannopyranoside. On treatment with tert-butylchlorodiphenylsilane, in N,N-dimethylformamide in the presence of imidazole, 4 and 6 afforded methyl 2-O-benzyl-6-O-tert-butyldiphenylsilyl-3-O-(2,3,4,6-tetra-O-acetyl -alpha-D- mannopyranosyl)-alpha-D-mannopyranoside (7), and methyl 2-O-benzyl-6-O-tert-butyldiphenylsilyl-3-O-(6-O-tert- butyldiphenylsilyl-alpha-D-mannopyranosyl)-alpha-D-mannopyranoside (8), respectively. Compound 8 was converted into its 2,3-O-isopropylidene derivative (9), and oxidation of 7 and 9 with pyridinium chlorochromate, and reduction of the resulting carbonyl intermediates gave methyl 2-O-benzyl-6-O-tert-butyldiphenylsilyl-3-O-(2,3,4,6-tetra-O-acetyl -alpha-D- mannopyranosyl)-alpha-D-talopyranoside and methyl 2-O-benzyl-6-O-tert-butyldiphenylsilyl-3-O-(6-O-tert-butyldiphe nylsilyl- 2,3-O-isopropylidene-alpha-D-talopyranosyl)-alpha-D-talopyranoside , respectively. Removal of the protecting groups furnished the title disaccharides.

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.

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

Synthesis of methyl 2-O-alpha-D-mannopyranosyl-alpha-D-talopyranoside and methyl 2-O-alpha-D-talopyranosyl-alpha-D-talopyranoside.

PubMed

Jain, R K; Dubey, R; Abbas, S A; Matta, K L

1987-03-15

Treatment of methyl 3-O-benzyl-2-O-(2,3,4,6-tetra-O-acetyl-alpha-D-mannopyranosyl)-alpha-D- mannopyranoside (1) with tert-butyldiphenylsilyl chloride in N,N-dimethylformamide afforded methyl 3-O-benzyl-6-O-tert-butyldiphenylsilyl-2-O-(2,3,4,6-tetra-O-acetyl -alpha-D- mannopyranosyl)-alpha-D-mannopyranoside (2). Oxidation of 2 with pyridinium chlorochromate, followed by reduction of the carbonyl group, and subsequent O-deacetylation afforded methyl 3-O-benzyl-6-O-tert-butyldiphenylsilyl-2-O-alpha-D-mannopyranosyl- alpha-D- talopyranoside (5). Cleavage of the tert-butyldiphenylsilyl group of 5 with tetrabutylammonium fluoride in oxolane, followed by hydrogenolysis, gave methyl 2-O-alpha-D-mannopyranosyl-alpha-D-talopyranoside (7). O-Deacetylation of 1 gave methyl 3-O-benzyl-2-O-alpha-D-mannopyranosyl-alpha-D-mannopyranoside (8). Treatment of 8 with tert-butyldiphenylsilyl chloride afforded a 6,6'-disilyl derivative, which was converted into a 2',3'-O-isopropylidene derivative, and then further oxidized with pyridinium chlorochromate. The resulting diketone was reduced and removal of the protecting groups gave methyl 2-O-alpha-D-talopyranosyl-alpha-D-talopyranoside (15). The structures of both 7 and 15 were established by 13C-n.m.r. spectroscopy.

Synthesis of 3 alpha, 5 alpha-tetrahydroaldosterone.

PubMed

Harnik, M; Kashman, Y; Morris, D J

1984-06-01

3 alpha, 5 alpha-Tetrahydroaldosterone (12a), a metabolite of aldosterone, has been synthesized from the lactone 2a or, preferably 11 beta, 21-dihydroxy-5-pregnene-3,20-dione-18-oic acid 3,20-di-(ethylene glycol)-ketal (18----11) lactone 21-acetate (6b), via 11 beta, 21-dihydroxy-5 alpha-pregnane-3,20-dione-18-oic acid 3,20-di-(ethylene glycol) ketal (18----11) lactone 21-acetate (4b). Selective hydrolysis of the latter at C-3 furnished the monoketal 5 which, on reduction with potassium tri-sec-butylborohydride, yielded predominantly 3 alpha, 11 beta, 21-trihydroxy-5 alpha-pregnan-20-one-18-oic acid 20-(ethylene glycol)-ketal (18----11) lactone (8a) and its acetate 8b. Further reduction with diisobutylaluminum hydride afforded 3 alpha, 5 alpha-tetrahydroaldosterone-20-ketal (10a), which was directly hydrolyzed to 12a with dilute acid in tetrahydrofuran-dioxan. Periodate oxidation led to the gamma-etiolactone 14a, which was then further converted into 5 alpha-dihydroaldosterone-gamma-etiolactone (14c).

Fe(II)/Cu(II) interaction on goethite stimulated by an iron-reducing bacteria Aeromonas Hydrophila HS01 under anaerobic conditions.

PubMed

Tao, Liang; Zhu, Zhen-Ke; Li, Fang-Bai; Wang, Shan-Li

2017-11-01

Copper is a trace element essential for living creatures, but copper content in soil should be controlled, as it is toxic. The physical-chemical-biological features of Cu in soil have a significant correlation with the Fe(II)/Cu(II) interaction in soil. Of significant interest to the current study is the effect of Fe(II)/Cu(II) interaction conducted on goethite under anaerobic conditions stimulated by HS01 (a dissimilatory iron reduction (DIR) microbial). The following four treatments were designed: HS01 with α-FeOOH and Cu(II) (T1), HS01 with α-FeOOH (T2), HS01 with Cu(II) (T3), and α-FeOOH with Cu(II) (T4). HS01 presents a negligible impact on copper species transformation (T3), whereas the presence of α-FeOOH significantly enhanced copper aging contributing to the DIR effect (T1). Moreover, the violent reaction between adsorbed Fe(II) and Cu(II) leads to the decreased concentration of the active Fe(II) species (T1), further inhibiting reactions between Fe(II) and iron (hydr)oxides and decelerating the phase transformation of iron (hydr)oxides (T1). From this study, the effects of the Fe(II)/Cu(II) interaction on goethite under anaerobic conditions by HS01 are presented in three aspects: (1) the accelerating effect of copper aging, (2) the reductive transformation of copper, and (3) the inhibition effect of the phase transformation of iron (hydr)oxides. Copyright © 2017 Elsevier Ltd. All rights reserved.

alpha-Hexachlorocyclohexane (alpha-HCH)

Integrated Risk Information System (IRIS)

alpha - Hexachlorocyclohexane ( alpha - HCH ) ; CASRN 319 - 84 - 6 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 Ass

Simultaneous quantification of GABAergic 3alpha,5alpha/3alpha,5beta neuroactive steroids in human and rat serum.

PubMed

Porcu, Patrizia; O'Buckley, Todd K; Alward, Sarah E; Marx, Christine E; Shampine, Lawrence J; Girdler, Susan S; Morrow, A Leslie

2009-01-01

The 3alpha,5alpha- and 3alpha,5beta-reduced derivatives of progesterone, deoxycorticosterone, dehydroepiandrosterone and testosterone enhance GABAergic neurotransmission and produce inhibitory neurobehavioral and anti-inflammatory effects. Despite substantial information on the progesterone derivative (3alpha,5alpha)-3-hydroxypregnan-20-one (3alpha,5alpha-THP, allopregnanolone), the physiological significance of the other endogenous GABAergic neuroactive steroids has remained elusive. Here, we describe the validation of a method using gas chromatography-mass spectrometry to simultaneously identify serum levels of the eight 3alpha,5alpha- and 3alpha,5beta-reduced derivatives of progesterone, deoxycorticosterone, dehydroepiandrosterone and testosterone. The method shows specificity, sensitivity and enhanced throughput compared to other methods already available for neuroactive steroid quantification. Administration of pregnenolone to rats and progesterone to women produced selective effects on the 3alpha,5alpha- and 3alpha,5beta-reduced neuroactive steroids, indicating differential regulation of their biosynthetic pathways. Pregnenolone administration increased serum levels of 3alpha,5alpha-THP (+1488%, p<0.001), (3alpha,5alpha)-3,21-dihydroxypregnan-20-one (3alpha,5alpha-THDOC, +205%, p<0.01), (3alpha,5alpha)-3-hydroxyandrostan-17-one (3alpha,5alpha-A, +216%, p<0.001), (3alpha,5alpha,17beta)-androstane-3,17-diol (3alpha,5alpha-A-diol, +190%, p<0.01). (3alpha,5beta)-3-hydroxypregnan-20-one (3alpha,5beta-THP) and (3alpha,5beta)-3-hydroxyandrostan-17-one (3alpha,5beta-A) were not altered, while (3alpha,5beta)-3,21-dihydroxypregnan-20-one (3alpha,5beta-THDOC) and (3alpha,5beta,17beta)-androstane-3,17-diol (3alpha,5beta-A-diol) were increased from undetectable levels to 271+/-100 and 2.4+/-0.9 pg+/-SEM, respectively (5/8 rats). Progesterone administration increased serum levels of 3alpha,5alpha-THP (+1806%, p<0.0001), 3alpha,5beta-THP (+575%, p<0.001), 3alpha,5alpha

EXAFS study of mercury(II) sorption to Fe- and Al-(hydr)oxides: I. Effects of pH

USGS Publications Warehouse

Kim, C.S.; Rytuba, J.J.; Brown, Gordon E.

2004-01-01

The study of mercury sorption products in model systems using appropriate in situ molecular-scale probes can provide detailed information on the modes of sorption at mineral/water interfaces. Such studies are essential for assessing the influence of sorption processes on the transport of Hg in contaminated natural systems. Macroscopic uptake of Hg(II) on goethite (??-FeOOH), ??-alumina (??-Al2O3), and bayerite (??-Al(OH)3) as a function of pH has been combined with Hg L III-edge EXAFS spectroscopy, FTIR spectroscopy, and bond valence analysis of possible sorption products to provide this type of information. Macroscopic uptake measurements show that Hg(II) sorbs strongly to fine-grained powders of synthetic goethite (Hg sorption density ??=0.39-0.42 ??mol/m2) and bayerite (??=0.39-0.44 ??mol/m2), while sorbing more weakly to ??-alumina (??=0.04-0.13 ??mol/m 2). EXAFS spectroscopy on the sorption samples shows that the dominant mode of Hg sorption on these phases is as monodentate and bidentate inner-sphere complexes. The mode of Hg(II) sorption to goethite was similar over the pH range 4.3-7.4, as were those of Hg(II) sorption to bayerite over the pH range 5.1-7.9. Conversion of the ??-Al2O3 sorbent to a bayerite-like phase in addition to the apparent reduction of Hg(II) to Hg(I), possibly by photoreduction during EXAFS data collection, resulted in enhanced Hg uptake from pH 5.2-7.8 and changes in the modes of sorption that correlate with the formation of the bayerite-like phase. Bond valence calculations are consistent with the sorption modes proposed from EXAFS analysis. EXAFS analysis of Hg(II) sorption products on a natural Fe oxyhydroxide precipitate and Al/Si-bearing flocculent material showed sorption products and modes of surface attachment similar to those for the model substrates, indicating that the model substrates are useful surrogates for the natural sediments. ?? 2003 Elsevier Inc. All rights reserved.

Chemical conversion of corticosteroids to 3 alpha,5 alpha-tetrahydro derivatives. Synthesis of 5 alpha-cortol 3-glucuronides and 5 alpha-cortolone 3-glucuronides.

PubMed

Hosoda, H; Osanai, K; Nambara, T

1991-12-01

The synthesis of the 3-glucuronides of 5 alpha-cortol-20 alpha, 5 alpha-cortolone-20 alpha and their 20 beta-epimers is described. The 5 alpha-cortol 20,21-diacetates (12, 17) and 5 alpha-cortolone 20,21-diacetates (14, 19) were the key intermediates. Sodium borohydride reduction of the carbonyl group at C-20 in 5 alpha-tetrahydrocortisol 3-tert-butyldimethylsilyl ether 17,21-acetonide (8) gave the 20 alpha-hydroxy-acetonide (9). Selective removal of the acetonide ring was successful when the 20 alpha-acetoxy-17 alpha,21-acetonide (10) was treated with 50% acetic acid. Subsequent acetylation with acetic anhydride in pyridine, followed by removal of the protecting group at C-3 in the silyl ether-acetate (11) gave the desired 20 alpha-intermediate (12). The 11-ketone (14) was prepared from 11 by oxidation with pyridinium chlorochromate, followed by desilylation. The 20 beta-acetates (17, 19) were synthesized from 21-acetoxy-3 alpha,11 beta,17 alpha-trihydroxy-5 alpha-pregnan-20-one 3-tert-butyldimethylsilyl ether (15). Introduction of the glucuronyl residue at C-3 was carried out by means of the Koenigs-Knorr reaction.

Stereoselective Synthesis of [alpha, alpha][superscript ']-Biprolines

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

Vartak, Ashish P.; Young, Jr., Victor G.; Johnson, Rodney L.

2010-11-10

A means to induce dehydrodimerization of Seebach's oxazolidinone (5), the stereochemical outcome of which is entirely temperature dependent, is described. The resultant dimers 3 and 4 are precursors to (R,R)-alpha,alpha'-biproline (1) and meso-alpha,alpha'-biproline (2), respectively. An organohypobromite and an iminium halide are proposed to serve as electrophiles in the reaction with the enolate of 5 to give 3 and 4, respectively.

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

Hydrogen-bearing iron peroxide and its implications to the deep Earth

NASA Astrophysics Data System (ADS)

Liu, J.; Hu, Q.; Kim, D. Y.; Wu, Z.; Wang, W.; Alp, E. E.; Yang, L.; Xiao, Y.; Meng, Y.; Chow, P.; Greenberg, E.; Prakapenka, V. B.; Mao, H. K.; Mao, W. L.

2017-12-01

Hydrous materials subducted into the deep mantle may play a significant role in the geophysical and geochemical processes of the lower mantle through geological time, but their roles have not become clear yet in the region. Hydrogen-bearing iron peroxide (FeO2Hx) was recently discovered to form through dehydrogenation of goethite (e.g., FeOOH) and the reaction between hematite (Fe2O3) and water under deep lower mantle conditions. We conducted synchrotron Mössbauer, X-ray absorption, and X-ray emission spectroscopy measurements to investigate the electronic spin and valence states of iron in hydrogen-bearing iron peroxide (FeO2Hx) in-situ at high pressures. Combined with theoretical calculations and other high-pressure experiments (i.e., nuclear resonant inelastic x-ray scattering spectroscopy and X-ray diffraction coupled with laser-heated diamond-anvil cell techniques), we find that the intriguing properties of FeO2Hx could shed light on the origin of a number of the observed geochemical and geophysical anomalies in the deep Earth.

Imaging of Jurassic fossils from the Talbragar Fish Bed using fluorescence, photoluminescence, and elemental and mineralogical mapping.

PubMed

Frese, Michael; Gloy, Gerda; Oberprieler, Rolf G; Gore, Damian B

2017-01-01

The Talbragar Fish Bed is one of Australia's most important Jurassic deposits for freshwater fishes, land plants and aquatic and terrestrial insects. The site has yielded many well preserved fossils, which has led to the formal description of numerous new species and higher taxa. The excellent preservation of many fossils has allowed detailed anatomical studies, e.g. of the early teleost fish Cavenderichthys talbragarensis (Woodward, 1895). Here we report on the fluorescent characteristics and mineral composition of a range of Talbragar fossils. Most specimens fluoresce under ultraviolet, blue and green light. Elemental and mineralogical analyses revealed that the Talbragar fossils consist predominantly of quartz (SiO2), a mineral that is likely to account for the observed fluorescence, with trace kaolinite (Al2Si2O5(OH)4) in some of the fish fossils. Rock matrices are predominantly composed of quartz and goethite (FeO(OH)). Closer inspection of a plant leaf (Pentoxylon australicum White, 1981) establishes fluorescence as a useful tool for the visualisation of anatomical details that are difficult to see under normal light conditions.

Imaging of Jurassic fossils from the Talbragar Fish Bed using fluorescence, photoluminescence, and elemental and mineralogical mapping

PubMed Central

Gloy, Gerda; Oberprieler, Rolf G.; Gore, Damian B.

2017-01-01

The Talbragar Fish Bed is one of Australia’s most important Jurassic deposits for freshwater fishes, land plants and aquatic and terrestrial insects. The site has yielded many well preserved fossils, which has led to the formal description of numerous new species and higher taxa. The excellent preservation of many fossils has allowed detailed anatomical studies, e.g. of the early teleost fish Cavenderichthys talbragarensis (Woodward, 1895). Here we report on the fluorescent characteristics and mineral composition of a range of Talbragar fossils. Most specimens fluoresce under ultraviolet, blue and green light. Elemental and mineralogical analyses revealed that the Talbragar fossils consist predominantly of quartz (SiO2), a mineral that is likely to account for the observed fluorescence, with trace kaolinite (Al2Si2O5(OH)4) in some of the fish fossils. Rock matrices are predominantly composed of quartz and goethite (FeO(OH)). Closer inspection of a plant leaf (Pentoxylon australicum White, 1981) establishes fluorescence as a useful tool for the visualisation of anatomical details that are difficult to see under normal light conditions. PMID:28582427

Effect of functional groups on the crystallization of ferric oxides/oxyhydroxides in suspension environment

NASA Astrophysics Data System (ADS)

Zhou, Qiong; Albert, Olga; Deng, Hua; Yu, Xiao-Long; Cao, Yang; Li, Jian-Bao; Huang, Xin

2012-12-01

This paper investigated the effects of five kinds of Au surfaces terminated with and without functional groups on the crystallization of ferric oxides/oxyhydroxides in the suspension condition. Self-assembled monolayers (SAMs) were used to create hydroxyl (-OH), carboxyl (-COOH), amine (-NH2) and methyl (-CH3) functionalized surfaces, which proved to be of the same surface density. The immersion time of substrates in the Fe(OH)3 suspension was divided into two time portions. During the first period of 2 h, few ferric oxide/oxyhydroxide was deposited except that ɛ-Fe2O3 was detected on -NH2 surface. Crystallization for 10 h evidenced more kinds of iron compounds on the functional surfaces. Goethite and maghemite were noticed on four functional surfaces, and maghemite also grew on Au surface. Deposition of ɛ-Fe2O3 was found on -OH surface, while the growth of orthorhombic and hexagon FeOOH were indicated on -NH2 surface. Considering the wide existence of iron compounds in nature, our investigation is a precedent work to the study of iron biomineralization in the suspension area.

Distribution of alpha3, alpha5 and alpha(v) integrin subunits in mature and immature human oocytes.

PubMed

Capmany, G; Mart, M; Santaló, J; Bolton, V N

1998-10-01

The distribution of three integrin subunits, alpha3, alpha5 and alpha(v), in immature and mature human oocytes has been examined using immunofluorescence and confocal microscopy. The results demonstrate that both alpha5 and alpha(v) are present at the germinal vesicle stage, while alpha3 was only detected in oocytes after germinal vesicle breakdown, in metaphase I and II stage oocytes. The cortical concentration of integrin subunits alpha3 and alpha5 is consistent with their localization in the oolemma. In contrast, the homogeneous distribution of alpha(v) throughout the oocyte suggests the existence of cytoplasmic reservoirs of this protein in the oocyte.

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.

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...

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

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.

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.

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.

Nano-Se attenuates cyclophosphamide-induced pulmonary injury through modulation of oxidative stress and DNA damage in Swiss albino mice.

PubMed

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

2015-07-01

Chemotherapy is an integral part of modern day treatment regimen but anticancer drugs fail to demarcate between cancerous and normal cells thereby causing severe form of systemic toxicity. Among which pulmonary toxicity is a dreadful complication developed in cancer patients upon cyclophosphamide (CP) therapy. Oxidative stress, fibrosis, and apoptosis are the major patho-mechanisms involved in CP-induced pulmonary toxicity. In the present study, we have synthesized Nano-Se, nanotechnology-based new form of elemental selenium which has significantly lower toxicity and acceptable bioavailability. In order to meet the need of effective drugs against CP-induced adverse effects, nano selenium (Nano-Se) was tested for its possible protective efficacy on CP-induced pulmonary toxicity and bone marrow toxicity. CP intoxication resulted in structural and functional lung impairment which was revealed by massive histopathological changes. Lung injury was associated with oxidative stress/lipid peroxidation as evident by increased in reactive oxygen species, nitric oxide level, and malondialdehyde (MDA) formation with decreased in level of antioxidants such as reduced glutathione, glutathione-S-transferase, glutathione peroxidase, superoxide dismutase, and catalase. Furthermore, CP at a dose of 25 mg/kg b.w. increased pulmonary DNA damage ('comet tail') and triggered DNA fragmentation and apoptosis in mouse bone marrow cells. On the other hand, Nano-Se at a dose of 2 mg Se/kg b.w., significantly inhibited CP-induced DNA damage in bronchoalveolar lavage cells, and decreased the apoptosis and percentage of DNA fragmentation in bone marrow cells and also antagonized the reduction of the activities of antioxidant enzymes and the increase level of MDA. Thus, our results suggest that Nano-Se in pre- and co-administration may serve as a promising preventive strategy against CP-induced pulmonary toxicity.

Orthopositronium Lifetime: Analytic Results in O({alpha}) and O({alpha}{sup 3}ln{alpha})

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

Kniehl, Bernd A.; Kotikov, Anatoly V.; Veretin, Oleg L.

2008-11-07

We present the O({alpha}) and O({alpha}{sup 3}ln{alpha}) corrections to the total decay width of orthopositronium in closed analytic form, in terms of basic irrational numbers, which can be evaluated numerically to arbitrary precision.

The use of nano-sized eggshell powder for calcium fortification of cow?s and buffalo?s milk yogurts.

PubMed

El-Shibiny, Safinaze; El-Gawad, Mona Abd El-Kader Mohamed Abd; Assem, Fayza Mohamed; El-Sayed, Samah Mosbah

2018-01-01

Calcium is an essential element for the growth, activity, and maintenance of the human body. Eggshells are a waste product which has received growing interest as a cheap and effective source of dietary calcium. Yogurt is a food which can be fortified with functional additives, including calcium. The aim of this study was to produce yogurt with a high calcium content by fortification with nano-sized eggshell powder (nano-ESP). Nano-sized ESP was prepared from pre-boiled and dried eggshell, using a ball mill. Yogurt was prepared from cow’s milk supplemented with 3% skimmed milk powder, and from buffalo’s milk fortified with 0.1, 0.2 and 0.3% and 0.1, 0.3 and 0.5% nano-ESP respectively. Electron microscopic transmission showed that the powder consisted of nano-sized crystalline struc- tures (~10 nm). Laser scattering showed that particles followed a normal distribution pattern with z-average of 590.5 nm, and had negative zeta-potential of –9.33 ±4.2 mV. Results regarding changes in yogurt composi- tion, acid development, calcium distribution, biochemical changes, textural parameters and sensory attributes have been presented and discussed. The addition of up to 0.3% nano-ESP made cow and buffalo high-calcium yogurts with an acceptable composition and quality. High-calcium yogurt may offer better health benefits, such as combating osteoporosis.

Core-shell nanosized assemblies mediated by the alpha-beta cyclodextrin dimer with a tumor-triggered targeting property.

PubMed

Quan, Chang-Yun; Chen, Jing-Xiao; Wang, Hui-Yuan; Li, Cao; Chang, Cong; Zhang, Xian-Zheng; Zhuo, Ren-Xi

2010-07-27

In this paper, the alpha-beta cyclodextrin dimer is designed via "click" chemistry to connect the hydrophilic and hydrophobic segments to form self-assembled noncovalently connected micelles (NCCMs) through host-guest interactions. A peptide containing the Arg-Gly-Asp (RGD) sequence was introduced to NCCMs as a target ligand to improve the cell uptake efficacy, while PEGylated technology was employed via benzoic-imine bonds to protect the ligands in normal tissues and body fluid. In addition, two fluorescent dyes were conjugated to different segments to track the formation of the micelles as well as the assemblies. It was found that the targeting property of NCCMs was switched off before reaching the tumor sites and switched on after removing the poly(ethylene glycol) (PEG) segment in the tumor sites, which was called "tumor-triggered targeting". With deshielding of the PEG segment, the drugs loaded in NCCMs could be released rapidly due to the thermoinduced phase transition. The new concept of "tumor-triggered targeting" proposed here has great potential for cancer treatment.

Improved synthesis of 3 alpha, 7 alpha, 12 alpha, 24 = xi-tetrahydroxy-5 beta-cholestan-26-oic acid.

PubMed

Batta, A K; Tint, G S; Dayal, B; Shefer, S; Salen, G

1982-06-01

This paper describes three simple and short methods for the conversion of cholic acid into cholylaldehyde with protected hydroxyl groups. The first method involves lithium aluminum hydride reduction of the tetrahydropyranyl ether of methyl cholate and oxidation of the resulting primary alcohol with pyridinium chlorochromate. The second method employs diborane for the reduction of the -COOH group to the -CH2OH group, while the third method involves the reduction of 3 alpha, 7 alpha, 12 alpha-triformyloxy-5 beta-cholan-24-oic acid (as the acid chloride) directly into 3 alpha, 7 alpha, 12 alpha-triformyloxy-5 beta-cholan-24-al with TMA-ferride (tetramethylammonium hydridoirontetracarbonyl). The aldehyde obtained by any of the above methods underwent smooth Reformatsky reaction with ethyl alpha-bromopropionate to yield 3 alpha, 7 alpha, 12 alpha, 24 xi-tetrahydroxy-5 beta-cholestan-26-oic acid.

Snow-borne nanosized particles: Abundance, distribution, composition, and significance in ice nucleation processes

NASA Astrophysics Data System (ADS)

Rangel-Alvarado, Rodrigo Benjamin; Nazarenko, Yevgen; Ariya, Parisa A.

2015-11-01

Physicochemical processes of nucleation constitute a major uncertainty in understanding aerosol-cloud interactions. To improve the knowledge of the ice nucleation process, we characterized physical, chemical, and biological properties of fresh snow using a suite of state-of-the-art techniques based on mass spectrometry, electron microscopy, chromatography, and optical particle sizing. Samples were collected at two North American Arctic sites, as part of international campaigns (2006 and 2009), and in the city of Montreal, Canada, over the last decade. Particle size distribution analyses, in the range of 3 nm to 10 µm, showed that nanosized particles are the most numerous (38-71%) in fresh snow, with a significant portion (11 to 19%) less than 100 nm in size. Particles with diameters less than 200 nm consistently exhibited relatively high ice-nucleating properties (on average ranged from -19.6 ± 2.4 to -8.1 ± 2.6°C). Chemical analysis of the nanosized fraction suggests that they contain bioorganic materials, such as amino acids, as well as inorganic compounds with similar characteristics to mineral dust. The implication of nanoparticle ubiquity and abundance in diverse snow ecosystems are discussed in the context of their importance in understanding atmospheric nucleation processes.

Nanosized TiO[subscript 2] for Photocatalytic Water Splitting Studied by Oxygen Sensor and Data Logger

ERIC Educational Resources Information Center

Zhang, Ruinan; Liu, Song; Yuan, Hongyan; Xiao, Dan; Choi, Martin M. F.

2012-01-01

Photocatalytic water splitting by semiconductor photocatalysts has attracted considerable attention in the past few decades. In this experiment, nanosized titanium dioxide (nano-TiO[subscript 2]) particles are used to photocatalytically split water, which is then monitored by an oxygen sensor. Sacrificial reagents such as organics (EDTA) and metal…

NANOSIZED MAGNESIUM OXIDE AS CATALYST FOR THE RAPID AND GREEN SYNTHESIS OF SUBSTITUTED 2-AMINO-2-CHROMENES

EPA Science Inventory

A nanosized magnesium oxide catalyzed three-component condensation reaction of aldehyde, malononitrile and ¿-naphthol proceeded rapidly in water/PEG to afford corresponding 2-amino-2-chromenes in high yields at room temperature. The greener protocol was found to be fairly general...

Electrodeposition of nano-sized bismuth on copper foil as electrocatalyst for reduction of CO2 to formate

NASA Astrophysics Data System (ADS)

Lv, Weixin; Zhou, Jing; Bei, Jingjing; Zhang, Rui; Wang, Lei; Xu, Qi; Wang, Wei

2017-01-01

Electrochemical reduction of carbon dioxide (CO2) to formate is energetically inefficient because high overpotential is required for reduction of CO2 to formate on most traditional catalysts. In this paper, a novel nano-sized Bi-based electrocatalyst deposited on a Cu foil has been synthesized, which can be used as a cathode for electrochemical reduction of CO2 to formate with a low overpotential (0.69 V) and a high selectivity (91.3%). The electrocatalyst can show excellent catalytic performance toward reduction of CO2 which can probably be attributed to the nano-sized structure and the surface oxide layer. The energy efficiency for reduction of CO2 to formate can reach to 50% when an IrxSnyRuzO2/Ti electrode is used as anode, it is one of the highest values found in the literatures and very practicable for sustainable fuel synthesis.

Reflection characterization of nano-sized dielectric structure in Morpho butterfly wings

NASA Astrophysics Data System (ADS)

Zhu, Dong

2017-10-01

Morpho butterflies living in Central and South America are well-known for their structural-colored blue wings. The blue coloring originates from the interaction of light with nano-sized dielectric structures that are equipped on the external surface of scales covering over their wings. The high-accuracy nonstandard finite-difference time domain (NS-FDTD) method is used to investigate the reflection characterization from the nanostructures. In the NS-FDTD calculation, a computational model is built to mimic the actual tree-like multilayered structures wherever possible using the hyperbolic tangent functions. It is generally known that both multilayer interference and diffraction grating phenomena can occur when light enters the nano-sized multilayered structure. To answer the question that which phenomenon is mainly responsible for the blue coloring, the NS-FDTD calculation is performed under various incidence angles at wavelengths from 360 to 500 nm. The calculated results at one incident wavelength under different incidence angles are visualized in a two-dimensional mapping image, where horizontal and vertical axes are incidence and reflection angles, respectively. The images demonstrate a remarkable transition from a ring-like pattern at shorter wavelengths to a retro-reflection pattern at longer wavelengths. To clarify the origin of the pattern transition, the model is separated into several simpler parts and compared their mapping images with the theoretical diffraction calculations. It can be concluded that the blue coloring at longer wavelengths is mainly caused by the cooperation of multilayer interference and retro-reflection while the effect of diffraction grating is predominant at shorter wavelengths.

Anticonvulsant properties of alpha, gamma, and alpha, gamma-substituted gamma-butyrolactones.

PubMed

Klunk, W E; Covey, D F; Ferrendelli, J A

1982-09-01

Derivatives of gamma-butyrolactone (GBL) substituted on the alpha- and/or gamma-positions were synthesized and tested for their effects on behavior in mice, on the electroencephalographs and blood pressure of paralyzed-ventilated guinea pigs, and on electrical activity of incubated hippocampal slices. Several compounds, including alpha-ethyl-alpha-methyl GBL (alpha-EMGBL), alpha, alpha-dimethyl GBL, alpha, gamma-diethyl-alpha, gamma-dimethyl GBL, and gamma-ethyl-gamma-methyl GBL, prevented seizures induced by pentylenetetrazol, beta-ethyl-beta-methyl-gamma-butyrolactone (beta-EMGBL), picrotoxin, or all three compounds in mice and guinea pigs but had no effect on seizures induced by maximal electroshock or bicuculline. Neither gamma-hydroxybutyrate (GHB) nor alpha-isopropylidine GBL had any anticonvulsant activity. The anticonvulsant alpha-substituted compounds had a potent hypotensive effect and antagonized the hypertensive effect of beta-EMGBL, alpha-EMGBL was tested in incubated hippocampal slices and was found to depress basal activity and antagonize excitation induced by beta-EMGBL. These results demonstrate that alpha-alkyl-substituted GBL and, to a lesser extent, gamma-substituted derivatives are anticonvulsant agents and that their effects are strikingly different from those of GHB or beta-alkyl-substituted GBLs, which are epileptogenic. Possibly beta- and alpha-substituted GBLs act at the same site as agonists and antagonists, respectively.

Cellulose-derived carbon aerogels supported goethite (α-FeOOH) nanoneedles and nanoflowers for electromagnetic interference shielding.

PubMed

Wan, Caichao; Jiao, Yue; Qiang, Tiangang; Li, Jian

2017-01-20

We describe a rapid and facile chemical precipitation method to grow goethite (α-FeOOH) nanoneedles and nanoflowers on the carbon aerogels which was obtained from the pyrolysis of cellulose aerogels. When evaluated as electromagnetic interference (EMI) shielding materials, the α-FeOOH/cellulose-derived carbon aerogels composite displays the highest SE total value of 34.0dB at the Fe 3+ /Fe 2+ concentration of 0.01M, which is about 4.8 times higher than that of the individual α-FeOOH (5.9dB). When the higher or lower Fe 3+ /Fe 2+ concentrations were used, the EMI shielding performance deterioration occurred. The integration of α-FeOOH with the carbon aerogels transforms the reflection-dominant mechanism for α-FeOOH into the adsorption-dominant mechanism for the composite. The adsorption-dominant mechanism undoubtedly makes contribution to alleviating secondary radiation, which is regarded as more attractive alternative for developing electromagnetic radiation protection products. Copyright © 2016 Elsevier Ltd. All rights reserved.

Sonochemical syntheses of a new nano-sized porous lead(II) coordination polymer as precursor for preparation of lead(II) oxide nanoparticles

NASA Astrophysics Data System (ADS)

Ranjbar, Zohreh Rashidi; Morsali, Ali

2009-11-01

Nano-scale of a new Pb(II) coordination polymer, {[Pb(bpacb)(OAc)]·DMF} n ( 1); bpacbH = 3,5-bis[(4-pyridylamino)carbonyl]benzoic acid], were synthesized by a sonochemical method. The nano-material was characterized by scanning electron microscopy, X-ray powder diffraction (XRD), 1H, 13C NMR, IR spectroscopy and elemental analyses. Crystal structure of compound 1 was determined by X-ray crystallography. Calcination of the nano-sized compound 1 at 700 °C under air atmospheres yields PbO nanoparticles. Thermal stability of nano-sized and single crystalline samples of compound 1 were studied and compared with each other.

Effects of ultrasonic vibration on microstructure and mechanical properties of nano-sized SiC particles reinforced Al-5Cu composites.

PubMed

Li, Jianyu; Lü, Shulin; Wu, Shusen; Gao, Qi

2018-04-01

Ultrasonic vibration (UV) treatment has been successfully applied to improve the particles distribution of nano-sized SiC particles (SiC p ) reinforced Al-5Cu alloy matrix composites which were prepared by combined processes of dry high energy ball milling and squeeze casting. When UV treatment is applied, the distribution of nano-sized SiC p has been greatly improved. After UV for 1 min, large particles aggregates are broken up into small aggregates due to effects of cavitation and the acoustic streaming. After UV for 5 min, all the particles aggregates are dispersed and the particles are uniformly distributed in the composites. Compared with the Al-5Cu matrix alloy, the ultimate tensile strength, yield strength and elongation of the 1 wt% nano-sized SiC p /Al-5Cu composites treated by UV for 5 min are 270 MPa, 173 MPa and 13.3%, which are increased by 7.6%, 6.8% and 29%, respectively. The improvements of mechanical properties after UV are attributed to the uniform distribution of nano particles, grain refinement of aluminum matrix alloy and reduction of porosity in the composites. Copyright © 2017 Elsevier B.V. All rights reserved.

In Situ Synthesis of Vertical Standing Nanosized NiO Encapsulated in Graphene as Electrodes for High-Performance Supercapacitors.

PubMed

Lin, Jinghuang; Jia, Henan; Liang, Haoyan; Chen, Shulin; Cai, Yifei; Qi, Junlei; Qu, Chaoqun; Cao, Jian; Fei, Weidong; Feng, Jicai

2018-03-01

NiO is a promising electrode material for supercapacitors. Herein, the novel vertically standing nanosized NiO encapsulated in graphene layers (G@NiO) are rationally designed and synthesized as nanosheet arrays. This unique vertical standing structure of G@NiO nanosheet arrays can enlarge the accessible surface area with electrolytes, and has the benefits of short ion diffusion path and good charge transport. Further, an interconnected graphene conductive network acts as binder to encapsulate the nanosized NiO particles as core-shell structure, which can promote the charge transport and maintain the structural stability. Consequently, the optimized G@NiO hybrid electrodes exhibit a remarkably enhanced specific capacity up to 1073 C g -1 and excellent cycling stability. This study provides a facial strategy to design and construct high-performance metal oxides for energy storage.

A novel copper (II) complex containing a tetradentate Schiff base: Synthesis, spectroscopy, crystal structure, DFT study, biological activity and preparation of its nano-sized metal oxide

NASA Astrophysics Data System (ADS)

Tohidiyan, Zeinab; Sheikhshoaie, Iran; Khaleghi, Mouj; Mague, Joel T.

2017-04-01

A new nano-sized copper (II) complex, [Cu(L)] with a tetra dentate Schiff base ligand, 2-((E)-(2-(E-5- bromo-2-hydroxybezenylideneamino) methyl)-4-bromophenol [H2L] was prepared by the reaction between of Cu (CH3COO)2·2H2O and (H2L) ligand with the ratio of 1:1, at the present of triethylamine by sonochemical method. The structure of [Cu (L)] complex was determined by FT-IR, UV-Vis, FESEM and molar conductivity. The structure of [Cu (L)] complex was characterized by single crystal X-ray diffraction. The geometry of [Cu (L)] complex was optimized using density functional theory (DFT) method with the B3LYP/6-31(d) level of theory. The calculated bond lengths and bond angles are in good agreement with the X-ray data. This complex was used as a novel precursor for preparing of CuO nano particles by the thermal decomposition method. The antibacterial activities of [H2L] ligand, nano-sized [Cu (L)] complex and nano-sized CuO have been screened against various strains of bacteria. According to the results, nano-sized CuO can be considered as an appropriate antibiotic agent.

Photo-triggered release in polyamide nanosized capsules

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

Marturano, V.; Ambrogi, V.; Cerruti, P.

2014-05-15

In this work, nanosized capsules based on a lightly cross-linked polyamide containing azobenzene moieties in the main chain were synthesized by miniemulsion interfacial polymerization. The obtained nanocapsules were loaded either with toluene or with the fluorescent probe coumarin-6 as a core. Diameters of the nanocapsules were in the 100-900 nm range, depending on the selected emulsion conditions. The morphology and shape of the samples were observed by TEM and SEM while the emulsion droplets and nanocapsules size was measured by DLS. Under continuous UV irradiation the polymer underwent E-Z photoisomerization allowing the release of the encapsulated material. Variation in diametermore » of the nanocapsules with the time of UV irradiation was detected through DLS analysis. 10-30% growth was observed, depending on the sample. The kinetics of release of coumarin-6 was followed by spectrofluorimetry in ethanol. In absence of irradiation, the fluorescence intensity appeared to be constant over time, while it increased when the sample was irradiated with 360 nm UV light.« less

The Effects of Natural Clinoptilolite and Nano-Sized Clinoptilolite Supplementation on Glucose Levels and Oxidative Stress in Rats With Type 1 Diabetes.

PubMed

Hossein Nia, Behnoosh; Khorram, Sirous; Rezazadeh, Hassan; Safaiyan, Abdolrasol; Tarighat-Esfanjani, Ali

2018-02-01

Oxidative stress has a major role in development of diabetic complications. In this study we investigated whether clinoptilolite and nano-sized clinoptilolite could reduce hyperglycemia and oxidative stress in streptozotocin-induced diabetic rats and attempted to determine which intervention was more effective. Thirty-six rats were randomly allocated to 2 groups; 1 group was randomly chosen as a diabetic group and injected with streptozotocin (60 mg/kg body weight in 0.1 mol/L sodium citrate buffer, pH 4.5) to induce diabetes. Three days after diabetes induction, each group (diabetic group and nondiabetic group) was randomly divided into 3 subgroups of 6 animals each ([1] control, [2] 1% clinoptilolite/food, [3] 1% nano-sized clinoptilolite/food). Supplementation was continued for 28 days. Blood glucose was measured 3 times, at the beginning of the study and on the 14th and 28th days. Activity of antioxidant enzymes, including glutathione peroxidase and superoxide dismutase, and levels of total antioxidant capacity, as well as malondialdehyde, were evaluated. Blood glucose and malondialdehyde were significantly elevated, but there were no statistically significant changes in superoxide dismutase, glutathione peroxidase or total antioxidant capacity in diabetic rats. In diabetic rats treated with nano-sized clinoptilolite, blood glucose decreased to near normal levels (12.4 vs. 27.5 mmol/L). No significant changes were found in the other groups. None of the oxidative stress indices showed significant changes in either the treated or untreated rats. Nano-sized clinoptilolite exerted a hypoglycemic effect in streptozotocin-induced diabetic rats but had no significant influence on oxidative stress markers. Copyright © 2018. Published by Elsevier Inc.

Sol-gel-Derived nano-sized double layer anti-reflection coatings (SiO2/TiO2) for low-cost solar cell fabrication.

PubMed

Lee, Seung Jun; Hur, Man Gyu; Yoon, Dae Ho

2013-11-01

We investigate nano-sized double layer anti-reflection coatings (ARCs) using a TiO2 and SiO2 sol-gel solution process for mono-crystalline silicon solar cells. The process can be easily adapted for spraying sol-gel coatings to reduce manufacturing cost. The spray-coated SiO2/TiO2 nano-sized double layer ARCs were deposited on mono-crystalline silicon solar cells, and they showed good optical properties. The spray coating process is a lower-cost fabrication process for large-scale coating than vacuum deposition processes such as PECVD. The measured average optical reflectance (300-1200 nm) was about approximately 8% for SiO2/TiO2 nano-sized double layer ARCs. The electrical parameters of a mono-crystalline silicon solar cell and reflection losses show that the SiO2/TiO2 stacks can improve cell efficiency by 0.2% compared to a non-coated mono-crystalline silicon solar cell. In the results, good correlation between theoretical and experimental data was obtained. We expect that the sol-gel spray-coated mono-crystalline silicon solar cells have high potential for low-cost solar cell fabrication.

Nanosized thin SnO₂ layers doped with Te and TeO₂ as room temperature humidity sensors.

PubMed

Georgieva, Biliana; Podolesheva, Irena; Spasov, Georgy; Pirov, Jordan

2014-05-21

In this paper the humidity sensing properties of layers prepared by a new method for obtaining doped tin oxide are studied. Different techniques-SEM, EDS in SEM, TEM, SAED, AES and electrical measurements-are used for detailed characterization of the thin layers. The as-deposited layers are amorphous with great specific area and low density. They are built up of a fine grained matrix, consisting of Sn- and Te-oxides, and a nanosized dispersed phase of Te, Sn and/or SnTe. The chemical composition of both the matrix and the nanosized particles depends on the ratio R(Sn/Te) and the evaporation conditions. It is shown that as-deposited layers with R(Sn/Te) ranging from 0.4 to 0.9 exhibit excellent characteristics as humidity sensors operating at room temperature-very high sensitivity, good selectivity, fast response and short recovery period. Ageing tests have shown that the layers possess good long-term stability. Results obtained regarding the type of the water adsorption on the layers' surface help better understand the relation between preparation conditions, structure, composition and humidity sensing properties.

Organocatalyzed asymmetric alpha-oxidation, alpha-aminoxylation and alpha-amination of carbonyl compounds.

PubMed

Vilaivan, Tirayut; Bhanthumnavin, Worawan

2010-02-11

Organocatalytic asymmetric alpha-oxidation and amination reactions of carbonyl compounds are highly useful synthetic methodologies, especially in generating chiral building blocks that previously have not been easily accessible by traditional methods. The concept is relatively new and therefore the list of new catalysts, oxidizing and aminating reagents, as well as new substrates, are expanding at an amazing rate. The scope of this review includes new reactions and catalysts, mechanistic aspects and synthetic applications of alpha-oxidation, hydroxylation, aminoxylation, amination, hydrazination, hydroxyamination and related alpha-heteroatom functionalization of aldehydes, ketones and related active methylene compounds published during 2005-2009.

Bile alcohol metabolism in man. Conversion of 5beta-cholestane-3alpha, 7alpha,12alpha, 25-tetrol to cholic acid.

PubMed Central

Salen, G; Shefer, S; Setoguchi, T; Mosbach, E H

1975-01-01

To study the role of C25-HYDROXY BILE ALCOHOLS AS PRECURSORS OF CHOlic acid, [G-3-H]5beta-cholestane-3alpha,7alpha12alpha,25-tetrol was administered intravenously to two subjects with cerebrotendinous xanthomatosis (CTX) and two normal individuals. One day after pulse labeling, radioactivity was present in the cholic acid isolated from the bile and feces of the subjects with CTX and the bile of the normal individuals. In the two normal subjects, the sp act decay curves of [G-3-H]-cholic acid were exponential, and no traces of [G-3-H]-5beta-cholestane-3alpha,7alpha,12alpha,25-tetrol were detected. In contrast, appreciable quantities of labeled 5beta-cholestane-3alpha,-7aopha,12alpha,25-tetrol were present in the bile and feces of the CTX subjects. The sp act vs. time curves of fecal [G-3-H]5beta-cholestane-3alpha,7alpha,12alpha,25-tetrol and [G-3-H]-cholic acid showed a precursor-product relationship. Although these results suggest that 5beta-cholestane-3alpha,7alpha,12alpha,25-tetrol may be a precursor of cholic acid in man, the possibility that C26-hydroxy intermediates represent the normal pathway can not be excluded. PMID:1141434

Comparison of selective flocculation of low grade goethitic iron ore fines using natural and synthetic polymers and a graft copolymer

NASA Astrophysics Data System (ADS)

Tudu, Kichakeswari; Pal, Sagar; Mandre, N. R.

2018-05-01

This study aims to beneficiate low grade goethitic iron ore fines using a selective flocculation process. Selective flocculation studies were conducted using different polymers such as starch amylopectin (AP), poly acrylic acid (PAA), and a graft copolymer (AP-g-PAA). The obtained results were analyzed; they indicate the enhancement of the iron ore grade from 58.49% to 67.52% using AP-g-PAA with a recovery of 95.08%. In addition, 64.45% Fe with a recovery of 88.79% was obtained using AP. Similarly, using PAA, the grade increased to 63.46% Fe with a recovery of 82.10%. The findings are also supported by characterizing concentrates using X-ray diffraction (XRD) and electron probe microanalysis (EPMA) techniques.

Constitution of green rust and its significance to the corrosion of steel in Portland cement

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

Sagoe-Crentsil, K.K.; Glasser, F.P.

1993-06-01

Studies of the corrosion of pure iron showed green rust, approximately Fe[sub 4][sup 2+]Fe[sub 2][sup 3+] (OH)[sub 12](Cl,OH)[sub 2], was a stable corrosion product at high pH and low E[sub h] in the presence of chloride. The structure, constitution, preparation, and characterization of green rust was reviewed. A diagram relevant to the corrosion of iron in cement, constructed for pH 12, showed stability fields of green rust, [alpha],[delta] FeO(OH), and [beta]FeO(OH,Cl). Overall implications of chloride to the corrosion process were investigated.

Contribution of alpha3(IV)alpha4(IV)alpha5(IV) Collagen IV to the Mechanical Properties of the Glomerular Basement Membrane

NASA Astrophysics Data System (ADS)

Gyoneva, Lazarina

The glomerular basement membrane (GBM) is a vital part of the blood-urine filtration barrier in the kidneys. In healthy GBMs, the main tension-resisting component is alpha3(IV)alpha4(IV)alpha5(IV) type IV collagen, but in some diseases it is replaced by other collagen IV isoforms. As a result, the GBM becomes leaky and disorganized, ultimately resulting in kidney failure. Our goal is to understanding the biomechanical aspects of the alpha3(IV)alpha4(IV)alpha5(IV) chains and how their absence could be responsible for (1) the initial injury to the GBM and (2) progression to kidney failure. A combination of experiments and computational models were designed for that purpose. A model basement membrane was used to compare experimentally the distensibility of tissues with the alpha3(IV)alpha4(IV)alpha5(IV) chains present and missing. The experiments showed basement membranes containing alpha3(IV)alpha4(IV)alpha5(IV) chains were less distensible. It has been postulated that the higher level of lateral cross-linking (supercoiling) in the alpha3(IV)alpha4(IV)alpha5(IV) networks contributes additional strength/stability to basement membranes. In a computational model of supercoiled networks, we found that supercoiling greatly increased the stiffness of collagen IV networks but only minimally decreased the permeability, which is well suited for the needs of the GBM. It is also known that the alpha3(IV)alpha4(IV)alpha5(IV) networks are more protected from enzymatic degradation, and we explored their significance in GBM remodeling. Our simulations showed that the more protected network was needed to prevent the system from entering a dangerous feedback cycle due to autoregulation mechanisms in the kidneys. Overall, the work adds to the evidence of biomechanical differences between the alpha3(IV)alpha4(IV)alpha5(IV) networks and other collagen IV networks, points to supercoiling as the main source of biomechanical differences, discusses the suitability of alpha3(IV)alpha4(IV)alpha

Flow-induced voltage generation by moving a nano-sized ionic liquids droplet over a graphene sheet: Molecular dynamics simulation.

PubMed

Shao, Qunfeng; Jia, Jingjing; Guan, Yongji; He, Xiaodong; Zhang, Xiaoping

2016-03-28

In this work, the phenomenon of the voltage generation is explored by using the molecular dynamics simulations, which is performed by driving a nano-sized droplet of room temperature ionic liquids moving along the monolayer graphene sheet for the first time. The studies show that the cations and anions of the droplet will move with velocity nonlinearly increasing to saturation arising by the force balance. The traditional equation for calculating the induced voltage is developed by taking the charge density into consideration, and larger induced voltages in μV-scale are obtained from the nano-size simulation systems based on the ionic liquids (ILs) for its enhanced ionic drifting velocities. It is also derived that the viscosity acts as a reduction for the induced voltage by comparing systems composed of two types of ILs with different viscosity and temperature.

Increased virulence and competitive advantage of a/alpha over a/a or alpha/alpha offspring conserves the mating system of Candida albicans.

PubMed

Lockhart, Shawn R; Wu, Wei; Radke, Joshua B; Zhao, Rui; Soll, David R

2005-04-01

The majority of Candida albicans strains in nature are a/alpha and must undergo homozygosis to a/a or alpha/alpha to mate. Here we have used a mouse model for systemic infection to test the hypothesis that a/alpha strains predominate in nature because they have a competitive advantage over a/a and alpha/alpha offspring in colonizing hosts. Single-strain injection experiments revealed that a/alpha strains were far more virulent than either their a/a or alpha/alpha offspring. When equal numbers of parent a/alpha and offspring a/a or alpha/alpha cells were co-injected, a/alpha always exhibited a competitive advantage at the time of extreme host morbidity or death. When equal numbers of an engineered a/a/alpha2 strain and its isogenic a/a parent strain were co-injected, the a/a/alpha2 strain exhibited a competitive advantage at the time of host morbidity or death, suggesting that the genotype of the mating-type (MTL) locus, not associated genes on chromosome 5, provides a competitive advantage. We therefore propose that heterozygosity at the MTL locus not only represses white-opaque switching and genes involved in the mating process, but also affects virulence, providing a competitive advantage to the a/alpha genotype that conserves the mating system of C. albicans in nature.

THE LYMAN ALPHA REFERENCE SAMPLE: EXTENDED LYMAN ALPHA HALOS PRODUCED AT LOW DUST CONTENT

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

Hayes, Matthew; Oestlin, Goeran; Duval, Florent

2013-03-10

We report on new imaging observations of the Lyman alpha emission line (Ly{alpha}), performed with the Hubble Space Telescope, that comprise the backbone of the Lyman alpha Reference Sample. We present images of 14 starburst galaxies at redshifts 0.028 < z < 0.18 in continuum-subtracted Ly{alpha}, H{alpha}, and the far ultraviolet continuum. We show that Ly{alpha} is emitted on scales that systematically exceed those of the massive stellar population and recombination nebulae: as measured by the Petrosian 20% radius, R{sub P20}, Ly{alpha} radii are larger than those of H{alpha} by factors ranging from 1 to 3.6, with an average ofmore » 2.4. The average ratio of Ly{alpha}-to-FUV radii is 2.9. This suggests that much of the Ly{alpha} light is pushed to large radii by resonance scattering. Defining the Relative Petrosian Extension of Ly{alpha} compared to H{alpha}, {xi}{sub Ly{alpha}} = R {sup Ly{alpha}}{sub P20}/R {sup H{alpha}}{sub P20}, we find {xi}{sub Ly{alpha}} to be uncorrelated with total Ly{alpha} luminosity. However, {xi}{sub Ly{alpha}} is strongly correlated with quantities that scale with dust content, in the sense that a low dust abundance is a necessary requirement (although not the only one) in order to spread Ly{alpha} photons throughout the interstellar medium and drive a large extended Ly{alpha} halo.« less

Effect of a nano-sized TiC particle addition on the flow-assisted corrosion resistance of SA 106B carbon steel

NASA Astrophysics Data System (ADS)

Park, Jin-Ju; Park, Eun-Kwang; Lee, Gyoung-Ja; Rhee, Chang-Kyu; Lee, Min-Ku

2017-09-01

Carbon steel with dispersed nano-sized TiC ceramic particles was fabricated by the ex-situ introduction of the particles into the melt, with the flow-assisted corrosion (FAC) resistance then investigated in the presence and absence of TiC nanoparticles using a once-through type of FAC loop test. From the potentiodynamic polarization curves, the current density at any given anodic potential was decreased and the open-circuit potential was increased by the addition of TiC nanoparticles. In addition, when the nano-sized TiC particles were added, the FAC rate was 1.38 times lower than that of carbon steel without TiC nanoparticles, indicating an improvement of the FAC resistance due to the homogeneous distribution of the TiC reinforcing nanoparticles.

[Spectral studies on nano-sized titania photocatalysts prepared by different drying methods].

PubMed

Ye, Zhao; Zhang, Han-hui; Pan, Hai-bo; Pan, Hong-qing

2002-12-01

Nano-sized TiO2 photocatalysts were prepared by drying the ethanol gel of titanium tetrabutoxide through natural state, supercritical ethanol, supercritical carbon dioxide drying methods and characterized by XRD, FTIR spectroscopy, FT-Raman spectroscopy and fluorescent spectroscopy, respectively. We regard degradation of rhodamine B by photocatalyst as a model reaction, and compare photocatalytic activities of samples obtained. The experimental results show that different drying methods have strong effect on crystal structure, energy band structure, optical adsorption property, surface quality and photocatalytic activity, TiO2 photocatalyst prepared by supercritical carbon dioxide drying method has superior photocatalytic activity.

Efficient recovery of nano-sized iron oxide particles from synthetic acid-mine drainage (AMD) water using fuel cell technologies.

PubMed

Cheng, Shaoan; Jang, Je-Hun; Dempsey, Brian A; Logan, Bruce E

2011-01-01

Acid mine drainage (AMD) is an important contributor to surface water pollution due to the release of acid and metals. Fe(II) in AMD reacts with dissolved oxygen to produce iron oxide precipitates, resulting in further acidification, discoloration of stream beds, and sludge deposits in receiving waters. It has recently been shown that new fuel cell technologies, based on microbial fuel cells, can be used to treat AMD and generate electricity. Here we show that this approach can also be used as a technique to generate spherical nano-particles of iron oxide that, upon drying, are transformed to goethite (α-FeOOH). This approach therefore provides a relatively straightforward way to generate a product that has commercial value. Particle diameters ranged from 120 to 700 nm, with sizes that could be controlled by varying the conditions in the fuel cell, especially current density (0.04-0.12 mA/cm(2)), pH (4-7.5), and initial Fe(II) concentration (50-1000 mg/L). The most efficient production of goethite and power occurred with pH = 6.3 and Fe(II) concentrations above 200 mg/L. These results show that fuel cell technologies can not only be used for simultaneous AMD treatment and power generation, but that they can generate useful products such as iron oxide particles having sizes appropriate for used as pigments and other applications. Copyright © 2010 Elsevier Ltd. All rights reserved.

Remarkable Second-Order Optical Nonlinearity of Nano-Sized Au Cluster: A TDDFT Study

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

Wu, Kechen; Li, Jun; Lin, Chensheng

2004-04-21

The dipole polarizability, static first hyperpolarizability, and UV-vis spectrum of the recently identified nano-sized tetrahedral cluster of Au have been investigated by using time-dependent density functional response theory. We have discovered that the Au cluster possesses remarkably large molecular second-order optical nonlinearity with the first hyperpolarizabilty (xyz) calculated to be 14.3 x 10 electrostatic unit (esu). The analysis of the low-energy absorption band suggests that the charge transfer from the edged gold atoms to the vertex ones plays the key role in nonlinear optical (NLO) response of Au.

The mongoose acetylcholine receptor alpha-subunit: analysis of glycosylation and alpha-bungarotoxin binding.

PubMed

Asher, O; Jensen, B S; Lupu-Meiri, M; Oron, Y; Fuchs, S

1998-04-17

The mongoose AChR alpha-subunit has been cloned and shown to be highly homologous to other AChR alpha-subunits, with only six differences in amino acid residues at positions that are conserved in animal species that bind alpha-bungarotoxin (alpha-BTX). Four of these six substitutions cluster in the ligand binding site, and one of them, Asn-187, forms a consensus N-glycosylation site. The mongoose glycosylated alpha-subunit has a higher apparent molecular mass than that of the rat glycosylated alpha-subunit, probably resulting from the additional glycosylation at Asn-187 of the mongoose subunit. The in vitro translated mongoose alpha-subunit, in a glycosylated or non-glycosylated form, does not bind alpha-BTX, indicating that lack of alpha-BTX binding can be achieved also in the absence of glycosylation.

The dispersion releaser technology is an effective method for testing drug release from nanosized drug carriers.

PubMed

Janas, Christine; Mast, Marc-Phillip; Kirsamer, Li; Angioni, Carlo; Gao, Fiona; Mäntele, Werner; Dressman, Jennifer; Wacker, Matthias G

2017-06-01

The dispersion releaser (DR) is a dialysis-based setup for the analysis of the drug release from nanosized drug carriers. It is mounted into dissolution apparatus2 of the United States Pharmacopoeia. The present study evaluated the DR technique investigating the drug release of the model compound flurbiprofen from drug solution and from nanoformulations composed of the drug and the polymer materials poly (lactic acid), poly (lactic-co-glycolic acid) or Eudragit®RSPO. The drug loaded nanocarriers ranged in size between 185.9 and 273.6nm and were characterized by a monomodal size distribution (PDI<0.1). The membrane permeability constants of flurbiprofen were calculated and mathematical modeling was applied to obtain the normalized drug release profiles. For comparing the sensitivities of the DR and the dialysis bag technique, the differences in the membrane permeation rates were calculated. Finally, different formulation designs of flurbiprofen were sensitively discriminated using the DR technology. The mechanism of drug release from the nanosized carriers was analyzed by applying two mathematical models described previously, the reciprocal powered time model and the three parameter model. Copyright © 2017 Elsevier B.V. All rights reserved.

Degradation of simazine from aqueous solutions by diatomite-supported nanosized zero-valent iron composite materials.

PubMed

Sun, Zhiming; Zheng, Shuilin; Ayoko, Godwin A; Frost, Ray L; Xi, Yunfei

2013-12-15

A novel composite material based on deposition of nanosized zero-valent iron (nZVI) particles on acid-leached diatomite was synthesised for the removal of a chlorinated contaminant in water. The nZVI/diatomite composites were characterised by X-ray diffraction, scanning electron microscopy, elemental analysis, transmission electron microscopy and X-ray photoelectron spectroscopy. Compared with the pure nZVI particles, better dispersion of nZVI particles on the surface or inside the pores of diatom shells was observed. The herbicide simazine was selected as the model chlorinated contaminant and the removal efficiency by nZVI/diatomite composite was compared with that of the pristine nZVI and commercial iron powder. It was found that the diatomite supported nZVI composite material prepared by centrifugation exhibits relatively better efficient activity in decomposition of simazine than commercial Fe, lab synthesised nZVI and composite material prepared via rotary evaporation, and the optimum experimental conditions were obtained based on a series of batch experiments. This study on immobilising nZVI particles onto diatomite opens a new avenue for the practical application of nZVI and the diatomite-supported nanosized zero-valent iron composite materials have potential applications in environmental remediation. Copyright © 2013 Elsevier B.V. All rights reserved.

Structural and Morphological Evaluation of Nano-Sized MoSi2 Powder Produced by Mechanical Milling

NASA Astrophysics Data System (ADS)

Sameezadeh, Mahmood; Farhangi, Hassan; Emamy, Masoud

Nano-sized intermetallic powders have received great attention owing to their property advantages over conventional micro-sized counterparts. In the present study nano-sized MoSi2 powder has been produced successfully from commercially available MoSi2 (3 μm) by a mechanical milling process carried out for a period of 100 hours. The effects of milling time on size and morphology of the powders were studied by SEM and TEM and image analyzing system. The results indicate that the as-received micrometric powder with a wide size distribution of irregular shaped morphology changes to a narrow size distribution of nearly equiaxed particles with the progress of attrition milling up to 100 h, reaching an average particle size of 71 nm. Structural evolution of milled samples was characterized by XRD to determine the crystallite size and lattice microstrain using Williamson-Hall method. According to the results, the crystallite size of the powders decreases continuously down to 23 nm with increasing milling time up to 100 h and this size refinement is more rapid at the early stages of the milling process. On the other hand, the lattice strain increases considerably with milling up to 65 h and further milling causes no significant changes of lattice strain.

40 CFR 721.10300 - Benzeneacetic acid, .alpha.-chloro-.alpha.-phenyl-, ethyl ester.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Benzeneacetic acid, .alpha.-chloro-.alpha.-phenyl-, ethyl ester. 721.10300 Section 721.10300 Protection of Environment ENVIRONMENTAL... Significant New Uses for Specific Chemical Substances § 721.10300 Benzeneacetic acid, .alpha.-chloro-.alpha...

40 CFR 721.10300 - Benzeneacetic acid, .alpha.-chloro-.alpha.-phenyl-, ethyl ester.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Benzeneacetic acid, .alpha.-chloro-.alpha.-phenyl-, ethyl ester. 721.10300 Section 721.10300 Protection of Environment ENVIRONMENTAL... Significant New Uses for Specific Chemical Substances § 721.10300 Benzeneacetic acid, .alpha.-chloro-.alpha...

40 CFR 721.10300 - Benzeneacetic acid, .alpha.-chloro-.alpha.-phenyl-, ethyl ester.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Benzeneacetic acid, .alpha.-chloro-.alpha.-phenyl-, ethyl ester. 721.10300 Section 721.10300 Protection of Environment ENVIRONMENTAL... Significant New Uses for Specific Chemical Substances § 721.10300 Benzeneacetic acid, .alpha.-chloro-.alpha...

Mapping High-Velocity H-alpha and Lyman-alpha Emission from Supernova 1987A

NASA Technical Reports Server (NTRS)

France, Kevin; McCray, Richard; Fransson, Claes; Larsson, Josefin; Frank, Kari A.; Burrows, David N.; Challis, Peter; Kirshner, Robert P.; Chevalier, Roger A.; Garnavich, Peter;

Morphological characterization of the AlphaA- and AlphaB-crystallin double knockout mouse lens

PubMed Central

Boyle, Daniel L; Takemoto, Larry; Brady, James P; Wawrousek, Eric F

2003-01-01

Background One approach to resolving some of the in vivo functions of alpha-crystallin is to generate animal models where one or both of the alpha-crystallin gene products have been eliminated. In the single alpha-crystallin knockout mice, the remaining alpha-crystallin may fully or partially compensate for some of the functions of the missing protein, especially in the lens, where both alphaA and alphaB are normally expressed at high levels. The purpose of this study was to characterize gross lenticular morphology in normal mice and mice with the targeted disruption of alphaA- and alphaB-crystallin genes (alphaA/BKO). Methods Lenses from 129SvEvTac mice and alphaA/BKO mice were examined by standard scanning electron microscopy and confocal microscopy methodologies. Results Equatorial and axial (sagittal) dimensions of lenses for alphaA/BKO mice were significantly smaller than age-matched wild type lenses. No posterior sutures or fiber cells extending to the posterior capsule of the lens were found in alphaA/BKO lenses. Ectopical nucleic acid staining was observed in the posterior subcapsular region of 5 wk and anterior subcapsular cortex of 54 wk alphaA/BKO lenses. Gross morphological differences were also observed in the equatorial/bow, posterior and anterior regions of lenses from alphaA/BKO mice as compared to wild mice. Conclusion These results indicated that both alphaA- and alphaB-crystallin are necessary for proper fiber cell formation, and that the absence of alpha-crystallin can lead to cataract formation. PMID:12546709

Solution conformation of a neuronal nicotinic acetylcholine receptor antagonist {alpha}-conotoxin OmIA that discriminates {alpha}3 vs. {alpha}6 nAChR subtypes

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

Chi, Seung-Wook; Kim, Do-Hyoung; Olivera, Baldomero M.

2006-06-23

{alpha}-Conotoxin OmIA from Conus omaria is the only {alpha}-conotoxin that shows a {approx}20-fold higher affinity to the {alpha}3{beta}2 over the {alpha}6{beta}2 subtype of nicotinic acetylcholine receptor. We have determined a three-dimensional structure of {alpha}-conotoxin OmIA by nuclear magnetic resonance spectroscopy. {alpha}-Conotoxin OmIA has an '{omega}-shaped' overall topology with His{sup 5}-Asn{sup 12} forming an {alpha}-helix. Structural features of {alpha}-conotoxin OmIA responsible for its selectivity are suggested by comparing its surface characteristics with other functionally related {alpha}4/7 subfamily conotoxins. Reduced size of the hydrophilic area in {alpha}-conotoxin OmIA seems to be associated with the reduced affinity towards the {alpha}6{beta}2 nAChR subtype.

Proline-catalysed asymmetric amination of alpha,alpha-disubstituted aldehydes: synthesis of configurationally stable enantioenriched alpha-aminoaldehydes.

PubMed

Vogt, Henning; Vanderheiden, Sylvia; Bräse, Stefan

2003-10-07

Proline-catalysed amination of alpha,alpha-disubstituted racemic aldehydes with azodicarboxylates proceeds smoothly to give configurationally stable scalemic aldehydes and oxazolidinones in up to 86% ee.

Biological effects of four iron-containing nanoremediation materials on the green alga Chlamydomonas sp.

PubMed

Nguyen, Nhung H A; Von Moos, Nadia R; Slaveykova, Vera I; Mackenzie, Katrin; Meckenstock, Rainer U; Thűmmler, Silke; Bosch, Julian; Ševců, Alena

2018-06-15

As nanoremediation strategies for in-situ groundwater treatment extend beyond nanoiron-based applications to adsorption and oxidation, ecotoxicological evaluations of newly developed materials are required. The biological effects of four new materials with different iron (Fe) speciations ([i] FerMEG12 - pristine flake-like milled Fe(0) nanoparticles (nZVI), [ii] Carbo-Iron ® - Fe(0)-nanoclusters containing activated carbon (AC) composite, [iii] Trap-Ox® Fe-BEA35 (Fe-zeolite) - Fe-doped zeolite, and [iv] Nano-Goethite - 'pure' FeOOH) were studied using the unicellular green alga Chlamydomonas sp. as a model test system. Algal growth rate, chlorophyll fluorescence, efficiency of photosystem II, membrane integrity and reactive oxygen species (ROS) generation were assessed following exposure to 10, 50 and 500 mg L -1 of the particles for 2 h and 24 h. The particles had a concentration-, material- and time-dependent effect on Chlamydomonas sp., with increased algal growth rate after 24 h. Conversely, significant intracellular ROS levels were detected after 2 h, with much lower levels after 24 h. All Fe-nanomaterials displayed similar Z-average sizes and zeta-potentials at 2 h and 24 h. Effects on Chlamydomonas sp. decreased in the order FerMEG12 > Carbo-Iron® > Fe-zeolite > Nano-Goethite. Ecotoxicological studies were challenged due to some particle properties, i.e. dark colour, effect of constituents and a tendency to agglomerate, especially at high concentrations. All particles exhibited potential to induce significant toxicity at high concentrations (500 mg L -1 ), though such concentrations would rapidly decrease to mg or µg L -1 in aquatic environments, levels harmless to Chlamydomonas sp. The presented findings contribute to the practical usage of particle-based nanoremediation in environmental restoration. Copyright © 2018. Published by Elsevier Inc.

Modulation of gene expression by alpha-tocopherol and alpha-tocopheryl phosphate in thp-1 monocytes

USDA-ARS?s Scientific Manuscript database

The naturally occurring vitamin E analogue, alpha-tocopheryl phosphate (alphaTP), has been reported to be more potent than the un-phosphorylated alpha alpha-tocopherol (alphaT). We have now measured plasma levels of alphaTP and compared the cellular effects of alphaTP and gamma-tocopheryl phosphate ...

Nanosiderite is effective to alleviate iron chlorosis in sensitive plants growing on calcareous soils

NASA Astrophysics Data System (ADS)

Sánchez-Alcalá, I.; del Campillo, M. C.; Barrón, V.; Torrent, J.

2012-04-01

Key words: siderite, iron chlorosis, calcareous soil, goethite, lepidocrocite Nanosized siderite (FeCO3) prepared by mixing FeSO4 and K2CO3 solutions [either alone or in presence of phosphate (siderites SID and SIDP, respectively)] was used in our experiments. The products of oxidation of siderite in a calcite suspension were goethite or a mixture of goethite and lepidocrocite when phosphate was present. These iron oxides were nanosized and acid NH4oxalate-soluble, which suggested they could be a good source of iron (Fe) for plants sensitive to Fe deficiency yellowing (chlorosis). To evaluate the effectiveness and long-term effects of suspensions of siderite mixed with calcareous soil to prevent Fe chlorosis, a pot growth experiment was carried out with five consecutive crops: chickpea (twice), peanut (twice) and strawberry. Suspensions of siderites (SID and SIDP) were mixed with 220 g of soil at the beginning of the experiment at rates of 0.24, 0.46, 0.93 and 1.40 g siderite (0.12, 0.22, 0.45, and 0.67 g Fe) kg-1 soil. A control (no Fe added) and a positive control (Fe-chelate as FeEDDHA before each cropping) were included. The concentration of chlorophyll in the youngest leaves was estimated three times for chickpea and peanut, and five times for strawberry via the SPAD value (SPAD 502 portable chlorophyll meter). The SPAD for the control plants was lower than that for Fe-fertilized plants. For all crops, times and siderite types, SPAD tended to systematically increase with increasing siderite dose, and SID and SIDP had similar effectiveness. At harvest, the SPAD for the plants fertilized with the highest siderite dose (1.40 g kg-1) did not differ significantly from that for FeEDDHA-fertilized plants. Our results suggest in summary that siderite is effective in preventing iron chlorosis and has a long-lasting effect, as the likely result of the high specific surface and high solubility of the crystalline Fe oxides resulting from its oxidation. Futhermore

Alpha fetoprotein

MedlinePlus

... this page: //medlineplus.gov/ency/article/003573.htm Alpha fetoprotein To use the sharing features on this page, please enable JavaScript. Alpha fetoprotein (AFP) is a protein produced by the liver ...

Alpha-tocopherol and alpha-tocopheryl quinone levels in cervical intraepithelial neoplasia and cervical cancer.

PubMed

Palan, Prabhudas R; Woodall, Angela L; Anderson, Patrick S; Mikhail, Magdy S

2004-05-01

alpha-Tocopherol is a potent antioxidant that protects cell membranes against oxidative damage. Red blood cell alpha-tocopherol levels reflect membrane alpha-tocopherol concentrations, and altered levels may suggest membrane damage. The objective of this study was to determine the levels of alpha-tocopherol and alpha-tocopheryl quinone, the oxidized product of alpha-tocopherol, in plasma and red blood cells that were obtained from control subjects and patients with cervical intraepithelial neoplasia and cervical cancer. In this cross-sectional study, 72 women, (32 African American and 40 Hispanic) were recruited. Among these subjects, 37 women had cervical intraepithelial neoplasia; 14 women had cervical cancer, and 21 women were considered control subjects, who had normal Papanicolaou test results. alpha-Tocopherol and alpha-tocopheryl quinone levels were determined in red blood cell and plasma by high-pressure liquid chromatography. Plasma levels of alpha-tocopherol and alpha-tocopheryl quinone were decreased significantly (P=.012 and=.005, respectively, by Kruskal-Wallis test) in study groups compared with the control group; red blood cell levels of alpha-tocopherol and alpha-tocopheryl quinone were not altered significantly. The lower alpha-tocopherol level that was observed in this study is consistent with our previous reports of decreased antioxidant concentrations and increased oxidative stress in women with cervical intraepithelial neoplasia. Unaltered red blood cell alpha-tocopherol and alpha-tocopheryl quinone levels suggest undamaged cell membrane. Further studies are needed to investigate the potential role of oxidative stress in cervical intraepithelial neoplasia.

Catalytic transformation of persistent contaminants using a new composite material based on nanosized zero-valent metal - field experiment results

NASA Astrophysics Data System (ADS)

Dror, I.; Merom Jacov, O.; Berkowitz, B.

2010-12-01

A new composite material based on deposition of nanosized zero valent iron (ZVI) particles and cyanocobalamine (vitamin B12) on a diatomite matrix is presented. Cyanocobalamine is known to be an effective electron mediator, having strong synergistic effects with ZVI for reductive dehalogenation reactions. This composite material also improves the reducing capacity of nanosized ZVI by preventing agglomeration of iron particles, thus increasing their active surface area. The porous structure of the diatomite matrix allows high hydraulic conductivity, which favors channeling of contaminated water to the reactive surface of the composite material and in turn faster rates of remediation. The ability of the material to degrade or transform rapidly and completely a large spectrum of water pollutants will be demonstrated, based on results from two field site experiments where polluted groundwater containing a mixture of industrial and agricultural persistent pollutants was treated. In addition a set of laboratory experiments using individual contaminant solutions to analyze chemical transformations under controlled conditions will be presented.

Hippocampal 3alpha,5alpha-THP may alter depressive behavior of pregnant and lactating rats.

PubMed

Frye, Cheryl A; Walf, Alicia A

2004-07-01

The 5alpha-reduced metabolite of progesterone (P), 5alpha-pregnan-3alpha-ol-20-one (3alpha,5alpha-THP), may mediate progestins' effects to reduce depressive behavior of female rats in part through actions in the hippocampus. To investigate, forced swim test behavior and plasma and hippocampal progestin levels were assessed in groups of rats expected to differ in their 3alpha,5alpha-THP levels due to endogenous differences (pregnant and postpartum), administration of a 5alpha-reductase inhibitor (finasteride; 50 mg/kg sc), and/or gestational stress [prenatal stress (PNS)], an animal model of depression. Pregnant rats had higher plasma and hippocampal 3alpha,5alpha-THP levels and less depressive behavior (decreased immobility, increased struggling and swimming) in the forced swim test than did postpartum rats. Finasteride, compared to vehicle-administration, reduced plasma and hippocampal 3alpha,5alpha-THP levels and increased depressive behavior (increased immobility, decreased struggling and swimming). PNS was associated with lower hippocampal, but not plasma, 3alpha,5alpha-THP levels and increased swimming compared to that observed in control rats. Together, these data suggest that 3alpha,5alpha-THP in the hippocampus may mediate antidepressive behavior of female rats.

Preparation of 3 beta, 5 alpha-, 3 alpha, 5 alpha- and 3 alpha, 5 beta-tetrahydro derivatives of 19-noraldosterone by chemical synthesis and microbial bioconversion.

PubMed

Harnik, M; Kashman, Y; Carmely, S; Cojocaru, M

1988-07-01

The 3 beta, 5 alpha-, 3 alpha, 5 alpha- and 3 alpha, 5 beta-tetrahydro derivatives 19, 20 and 27 of 19-noraldosterone (1) were prepared to facilitate the search for these compounds in urine. The diketal 4, consisting of a 2:1 mixture of the 5,6- and 5(10)-ene isomers, was hydrogenated with Pd-C and partially hydrolyzed to 5 alpha, 10 alpha- and 5 alpha, 10 beta-dihydroketals 8 and 10 in a 1:2.5 ratio. Assignment of protons was done with aid of COSY 45 experiments. Compound 10 was reduced with diisobutylaluminum hydride (DIBAH) to 4 products: the 3 alpha- and 3 beta-ol hemiacetals 16 and 15, and the corresponding tetraols 14 and 13. Alternatively, hydrogenation of the 4-en-3-one 2 gave 10, its 5 beta, 10 beta-isomer 21 and the tetrahydro compound 22, in a 4:2:1 ratio. A better way to prepare the 5 beta, 10 beta-series involved microbial conversion of 2 with Clostridium paraputrificum, and the resulting tetrahydrolactone 23 was reduced with DIBAH to the hemiacetal 24. Acid hydrolysis of 16, 15 and 24 afforded 20, 19 and 27, respectively. According to [1H]-NMR, in solution 20 and 24 exist as mixtures of isomers, while 19 appears in one form only. Periodate oxidation converted 19 and 27 into their gamma-etiolactones 18 and 28. EI MS base peaks are different and characteristic for 19, 20 and 27.

Nanosized Thin SnO2 Layers Doped with Te and TeO2 as Room Temperature Humidity Sensors

PubMed Central

Georgieva, Biliana; Podolesheva, Irena; Spasov, Georgy; Pirov, Jordan

2014-01-01

In this paper the humidity sensing properties of layers prepared by a new method for obtaining doped tin oxide are studied. Different techniques—SEM, EDS in SEM, TEM, SAED, AES and electrical measurements—are used for detailed characterization of the thin layers. The as-deposited layers are amorphous with great specific area and low density. They are built up of a fine grained matrix, consisting of Sn- and Te-oxides, and a nanosized dispersed phase of Te, Sn and/or SnTe. The chemical composition of both the matrix and the nanosized particles depends on the ratio RSn/Te and the evaporation conditions. It is shown that as-deposited layers with RSn/Te ranging from 0.4 to 0.9 exhibit excellent characteristics as humidity sensors operating at room temperature—very high sensitivity, good selectivity, fast response and short recovery period. Ageing tests have shown that the layers possess good long-term stability. Results obtained regarding the type of the water adsorption on the layers' surface help better understand the relation between preparation conditions, structure, composition and humidity sensing properties. PMID:24854359

A polymer solution technique for the synthesis of nano-sized Li 2TiO 3 ceramic breeder powders

NASA Astrophysics Data System (ADS)

Jung, Choong-Hwan; Lee, Sang Jin; Kriven, Waltraud M.; Park, Ji-Yeon; Ryu, Woo-Seog

2008-02-01

Nano-sized Li 2TiO 3 powder was fabricated by an organic-inorganic solution route. A steric entrapment route employing ethylene glycol was used for the preparation of the nano-sized Li 2TiO 3 particles. Titanium isopropoxide and lithium nitrate were dissolved in liquid-type ethylene glycol without any precipitation. With the optimum amount of the polymer, the metal cations (Li and Ti) were dispersed in the solution and a homogeneous polymeric network was formed. The organic-inorganic precursor gels were turned to crystalline powders through an oxidation reaction during a calcination process. The dried precursor gel showed the carbon-free Li 2TiO 3 crystalline form which was observed above 400 °C. The primary particle size of the carbon-free Li 2TiO 3 was about 70 nm, and the structure of the crystallized powder was porous and agglomerated. The powder compact was densified to 92% of TD at a relatively low sintering temperature of 1100 °C for 2 h.

[Building immune microsphere against tumor necrosis factor-alpha (TNF-alpha)].

PubMed

Wang, Qin; Wu, Xiongfei; Wang, Junxia; Liu, Hong; Li, Lian; Jin, Xiyu

2005-12-01

We have constructed the immune microsphere against tumor necrosis factor-alpha (TNF-alpha) prospectively, hoping to establish the experiment groundwork in more researches which could be used in specific elimination of the TNF-alpha by blood purification method for the future. The recombinant human tumor necrosis factor-alpha monoclonal antibody (rHTNF-alpha McAb) was wrapped on the polystyrene microsphere (PSM) carrier connecting poly-L-lysine (PLL) beforehand. They were earmarked by the fluorescein isothiocyanate (FITC) respectively. The packing conditions were examined using the inversted and fluorescence microscopes and the spectrophotometer. The results showed that the best conditions for wrapping were 20 degrees C, pH9.5 and 60 minutes. The PLL content was not changed in the washing fluid after coating, which indicated the wrapping was quite firm. At the same temperature and same coating time, the rHTNF-alpha McAb coated on the PLL was obviously substantial when the concentration of glutaraldehyde solution was 0.2%. The findings demonstrated that the built immune microsphers can be used as a novel adsorption material. This method is simple and economic, and it offers a new approach to the related studies.

alpha-Mannosidosis in the guinea pig: cloning of the lysosomal alpha-mannosidase cDNA and identification of a missense mutation causing alpha-mannosidosis.

PubMed

Berg, Thomas; Hopwood, John J

2002-03-16

alpha-Mannosidosis is a lysosomal storage disorder caused by deficient activity of the lysosomal alpha-mannosidase. We report here the sequencing and expression of the lysosomal alpha-mannosidase cDNA from normal and alpha-mannosidosis guinea pigs. The amino acid sequence of the guinea pig enzyme displayed 82-85% identity to the lysosomal alpha-mannosidase in other mammals. The cDNA of the alpha-mannosidosis guinea pig contained a missense mutation, 679C>T, leading to substitution of arginine by tryptophan at amino acid position 227 (R227W). The R227W allele segregated with the alpha-mannosidosis genotype in the guinea pig colony and introduction of R227W into the wild-type sequence eliminated the production of recombinant alpha-mannosidase activity in heterologous expression studies. Furthermore, the guinea pig mutation has been found in human patients. Our results strongly indicate that the 679C>T mutation causes alpha-mannosidosis and suggest that the guinea pig will be an excellent model for investigation of pathogenesis and evaluation of therapeutic strategies for human alpha-mannosidosis.

Microbial surfactants: fundamentals and applicability in the formulation of nano-sized drug delivery vectors.

PubMed

Rodrigues, Ligia R

2015-07-01

Microbial surfactants, so-called biosurfactants, comprise a wide variety of structurally distinct amphipathic molecules produced by several microorganisms. Besides exhibiting surface activity at the interfaces, these molecules present powerful characteristics including high biodegradability, low toxicity and special biological activities (e.g. antimicrobial, antiviral, anticancer, among others), that make them an alternative to their chemical counterparts. Several medical-related applications have been suggested for these molecules, including some reports on their potential use in the formulation of nano-sized drug delivery vectors. However, despite their promises, due to the generalized lack of knowledge on microbial surfactants phase behavior and stability under diverse physicochemical conditions, these applications remain largely unexplored, thus representing an exciting field of research. These nano-sized vectors are a powerful approach towards the current medical challenges regarding the development of efficient and targeted treatments for several diseases. In this review, a special emphasis will be given to nanoparticles and microemulsions. Nanoparticles are very auspicious as their size, shape and stability can be manipulated by changing the environmental conditions. On the other hand, the easiness of formulation, as well as the broad possibilities of administration justifies the recent popularity of the microemulsions. Notwithstanding, both vector types still require further developments to overcome some critical limitations related with toxicity and costs, among others. Such developments may include the search for other system components, as the microbial surfactants, that can display improved features. Copyright © 2015 Elsevier Inc. All rights reserved.

Reversible Li storage for nanosize cation/anion-disordered rocksalt-type oxyfluorides: LiMoO2 - x LiF (0 ≤ x ≤ 2) binary system

NASA Astrophysics Data System (ADS)

Takeda, Nanami; Hoshino, Satoshi; Xie, Lixin; Chen, Shuo; Ikeuchi, Issei; Natsui, Ryuichi; Nakura, Kensuke; Yabuuchi, Naoaki

2017-11-01

A binary system of LiMoO2 - x LiF (0 ≤ x ≤ 2), Li1+xMoO2Fx, is systematically studied as potential positive electrode materials for rechargeable Li batteries. Single phase and nanosized samples on this binary system are successfully prepared by using a mechanical milling route. Crystal structures and Li storage properties on the binary system are also examined. Li2MoO2F (x = 1), which is classified as a cation-/anion-disordered rocksalt-type structure and is a thermodynamically metastable phase, delivers a large reversible capacity of over 300 mAh g-1 in Li cells with good reversibility. Highly reversible Li storage is realized for Li2MoO2F consisting of nanosized particles based on Mo3+/Mo5+ two-electron redox as evidenced by ex-situ X-ray absorption spectroscopy coupled with ex-situ X-ray diffractometry. Moreover, the presence of the most electronegative element in the framework structure effectively increases the electrode potential of Mo redox through an inductive effect. From these results, potential of nanosized lithium molybdenum oxyfluorides for high-capacity positive electrode materials of rechargeable Li batteries are discussed.

Role of the C-terminal extensions of alpha-crystallins. Swapping the C-terminal extension of alpha-crystallin to alphaB-crystallin results in enhanced chaperone activity.

PubMed

Pasta, Saloni Yatin; Raman, Bakthisaran; Ramakrishna, Tangirala; Rao, Ch Mohan

2002-11-29

Several small heat shock proteins contain a well conserved alpha-crystallin domain, flanked by an N-terminal domain and a C-terminal extension, both of which vary in length and sequence. The structural and functional role of the C-terminal extension of small heat shock proteins, particularly of alphaA- and alphaB-crystallins, is not well understood. We have swapped the C-terminal extensions between alphaA- and alphaB-crystallins and generated two novel chimeric proteins, alphaABc and alphaBAc. We have investigated the domain-swapped chimeras for structural and functional alterations. We have used thermal and non-thermal models of protein aggregation and found that the chimeric alphaB with the C-terminal extension of alphaA-crystallin, alphaBAc, exhibits dramatically enhanced chaperone-like activity. Interestingly, however, the chimeric alphaA with the C-terminal extension of alphaB-crystallin, alphaABc, has almost lost its activity. Pyrene solubilization and bis-1-anilino-8-naphthalenesulfonate binding studies show that alphaBAc exhibits more solvent-exposed hydrophobic pockets than alphaA, alphaB, or alphaABc. Significant tertiary structural changes are revealed by tryptophan fluorescence and near-UV CD studies upon swapping the C-terminal extensions. The far-UV CD spectrum of alphaBAc differs from that of alphaB-crystallin whereas that of alphaABc overlaps with that of alphaA-crystallin. Gel filtration chromatography shows alteration in the size of the proteins upon swapping the C-terminal extensions. Our study demonstrates that the unstructured C-terminal extensions play a crucial role in the structure and chaperone activity, in addition to generally believed electrostatic "solubilizer" function.

Direct conversion of bio-ethanol to isobutene on nanosized Zn(x)Zr(y)O(z) mixed oxides with balanced acid-base sites.

PubMed

Sun, Junming; Zhu, Kake; Gao, Feng; Wang, Chongmin; Liu, Jun; Peden, Charles H F; Wang, Yong

2011-07-27

We report the design and synthesis of nanosized Zn(x)Zr(y)O(z) mixed oxides for direct and high-yield conversion of bio-ethanol to isobutene (~83%). ZnO is addded to ZrO(2) to selectively passivate zirconia's strong Lewis acidic sites and weaken Brönsted acidic sites, while simultaneously introducing basicity. As a result, the undesired reactions of bio-ethanol dehydration and acetone polymerization/coking are suppressed. Instead, a surface basic site-catalyzed ethanol dehydrogenation to acetaldehyde, acetaldehyde to acetone conversion via a complex pathway including aldol-condensation/dehydrogenation, and a Brönsted acidic site-catalyzed acetone-to-isobutene reaction pathway dominates on the nanosized Zn(x)Zr(y)O(z) mixed oxide catalyst, leading to a highly selective process for direct conversion of bio-ethanol to isobutene.

No time to waste organic waste: Nanosizing converts remains of food processing into refined materials.

PubMed

Griffin, Sharoon; Sarfraz, Muhammad; Farida, Verda; Nasim, Muhammad Jawad; Ebokaiwe, Azubuike P; Keck, Cornelia M; Jacob, Claus

2018-03-15

Modern food processing results in considerable amounts of side-products, such as grape seeds, walnut shells, spent coffee grounds, and harvested tomato plants. These materials are still rich in valuable and biologically active substances and therefore of interest from the perspective of waste management and "up-cycling". In contrast to traditional, often time consuming and low-value uses, such as vermicomposting and anaerobic digestion, the complete conversion into nanosuspensions unlocks considerable potentials of and new applications for such already spent organic materials without the need of extraction and without producing any additional waste. In this study, nanosuspensions were produced using a sequence of milling and homogenization methods, including High Speed Stirring (HSS) and High Pressure Homogenization (HPH) which reduced the size of the particles to 200-400 nm. The resulting nanosuspensions demonstrated nematicidal and antimicrobial activity and their antioxidant activities exceeded the ones of the bulk materials. In the future, this simple nanosizing approach may fulfil several important objectives, such as reducing and turning readily available waste into new value and eventually closing a crucial cycle of agricultural products returning to their fields - with a resounding ecological impact in the fields of medicine, agriculture, cosmetics and fermentation. Moreover, up-cycling via nanosizing adds an economical promise of increased value to residue-free waste management. Copyright © 2018 Elsevier Ltd. All rights reserved.

Synthesis of nano-sized ZnO particles by co-precipitation method with variation of heating time

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

Purwaningsih, S. Y., E-mail: sriyanisaputri@gmail.com; Pratapa, S.; Triwikantoro

Zinc oxide powders have been synthesized by a co-precipitation method at low temperature (85 °C), using zinc acetate dihydrate, ammonia, hydrochloric acid solutions as the reactants. A number of process parameters such as reaction temperature, solution basicity or pH and heating time are the main factors affecting the morphology and physical properties of the ZnO nanostructures. In this work the effect of heating time on the morphology and particles size were studied. The as-synthesized ZnO powders were characterized using transmission electron microscopy (TEM) and X-ray diffraction (XRD) techniques. The samples were also analyzed using Fourier transform infrared (FTIR). Rietveld refinementmore » of XRD data confirms that ZnO crystallizes in the hexagonal wurtzite structure with high degree of purity and the (101) plane predominant. The XRD results show that the average crystallite sizes were about 66, 27 and 12 nm for 3, 4 and 5 h of heating times, respectively. The XRD analysis indicated that a fraction of nano-sized ZnO powders were in the form of aggregates, which was also verified by TEM image. The TEM photograph demonstrated that the nano-sized ZnO particles were a pseudo-spherical shape.« less

Synthesis of methyl 2-O- and 3-O-alpha-D-talopyranosyl-alpha-D-mannopyranoside.

PubMed

Rana, S S; Matta, K L

1986-09-01

Methyl 3,4,6-tri-O-benzyl-2-O-[6-O-(tert-butyldiphenylsilyl)-alpha-D- mannopyranosyl]-alpha-D-mannopyranoside (2) was synthesized by treatment of methyl 3,4,6-tri-O-benzyl-2-O-alpha-D-mannopyranosyl-alpha-D-mannopyranoside with tert-butylchlorodiphenylsilane in the presence of imidazole. Isopropylidenation, followed by oxidation with pyridinium chlorochromate, and stereoselective reduction with sodium borohydride, converted 2 into methyl 3,4,6-tri-O-benzyl-2-O-[6-O-(tert-butyldiphenylsilyl)-2,3-O-isopro pylidene- alpha-D-talopyranosyl]-alpha-D-mannopyranoside (5). Treatment of 5 with a molar solution of tetrabutylammonium fluoride in dry oxolane produced a diol which, on O-de-isopropylidenation followed by catalytic hydrogenolysis, afforded the disaccharide glycoside methyl 2-O-alpha-D-talopyranosyl-alpha-D-mannopyranoside. Synthesis of methyl 3-O-alpha-D-talopyranosyl-alpha-D-mannopyranoside was accomplished by a similar reaction-sequence. The structures of the final disaccharides, and of various other intermediates, were established by 1H- and 13C-n.m.r. spectroscopy.

Nanoscale Design of Nano-Sized Particles in Shape-Memory Polymer Nanocomposites Driven by Electricity

PubMed Central

Lu, Haibao; Huang, Wei Min; Liang, Fei; Yu, Kai

2013-01-01

In the last few years, we have witnessed significant progress in developing high performance shape memory polymer (SMP) nanocomposites, in particular, for shape recovery activated by indirect heating in the presence of electricity, magnetism, light, radio frequency, microwave and radiation, etc. In this paper, we critically review recent findings in Joule heating of SMP nanocomposites incorporated with nanosized conductive electromagnetic particles by means of nanoscale control via applying an electro- and/or magnetic field. A few different nanoscale design principles to form one-/two-/three- dimensional conductive networks are discussed. PMID:28788303

alpha-decay half-lives and Q{sub a}lpha values of superheavy nuclei

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

Dong Jianmin; Graduate University of Chinese Academy of Sciences, Beijing 100049; School of Nuclear Science and Technology, Lanzhou University, Lanzhou 730000

2010-06-15

The alpha-decay half-lives of recently synthesized superheavy nuclei (SHN) are investigated by employing a unified fission model (UFM) where a new method to calculate the assault frequency of alpha emission is used. The excellent agreement with the experimental data indicates the UFM is a useful tool to investigate these alpha decays. It is found that the alpha-decay half-lives become more and more insensitive to the Q{sub a}lpha values as the atomic number increases on the whole, which is favorable for us to predict the half-lives of SHN. In addition, a formula is proposed to compute the Q{sub a}lpha values formore » the nuclei with Z>=92 and N>=140 with a good accuracy, according to which the long-lived SHN should be neutron rich. Several weeks ago, two isotopes of a new element with atomic number Z=117 were synthesized and their alpha-decay chains have been observed. The Q{sub a}lpha formula is found to work well for these nuclei, confirming its predictive power. The experimental half-lives are well reproduced by employing the UFM with the experimental Q{sub a}lpha values. This fact that the experimental half-lives are compatible with experimental Q{sub a}lpha values supports the synthesis of a new element 117 and the experimental measurements to a certain extent.« less

An amorphous FeMoS4 nanorod array toward efficient hydrogen evolution electrocatalysis under neutral conditions.

PubMed

Ren, Xiang; Wang, Weiyi; Ge, Ruixiang; Hao, Shuai; Qu, Fengli; Du, Gu; Asiri, Abdullah M; Wei, Qin; Chen, Liang; Sun, Xuping

2017-08-08

It is highly attractive to develop efficient hydrogen-evolving electrocatalysts under neutral conditions. In this communication, we report an amorphous FeMoS 4 nanorod array on carbon cloth (FeMoS 4 NRA/CC) prepared by hydrothermal treatment of an FeOOH nanorod array on carbon cloth (FeOOH NRA/CC) in (NH 4 ) 2 MoS 4 solution. As a 3D electrode for hydrogen evolution electrocatalysis, this FeMoS 4 NRA/CC demonstrates superior catalytic activity and strong long-term electrochemical durability in 1.0 M phosphate buffered saline (pH: 7). It needs an overpotential of 204 mV to drive a geometrical current density of 10 mA cm -2 , which is 450 mV less than that for FeOOH NRA/CC. Density functional theory calculations suggest that FeMoS 4 has a more favourable hydrogen adsorption free energy than FeOOH.

Formation of iron nanoparticles and increase in iron reactivity in mineral dust during simulated cloud processing.

PubMed

Shi, Zongbo; Krom, Michael D; Bonneville, Steeve; Baker, Alex R; Jickells, Timothy D; Benning, Liane G

2009-09-01

The formation of iron (Fe) nanoperticles and increase in Fe reactivity in mineral dust during simulated cloud processing was investigated using high-resolution microscopy and chemical extraction methods. Cloud processing of dust was experimentally simulated via an alternation of acidic (pH 2) and circumneutral conditions (pH 5-6) over periods of 24 h each on presieved (<20 microm) Saharan soil and goethite suspensions. Microscopic analyses of the processed soil and goethite samples reveal the neo-formation of Fe-rich nanoparticle aggregates, which were not found initially. Similar Fe-rich nanoparticles were also observed in wet-deposited Saharen dusts from the western Mediterranean but not in dry-deposited dust from the eastern Mediterranean. Sequential Fe extraction of the soil samples indicated an increase in the proportion of chemically reactive Fe extractable by an ascorbate solution after simulated cloud processing. In addition, the sequential extractions on the Mediterranean dust samples revealed a higher content of reactive Fe in the wet-deposited dust compared to that of the dry-deposited dust These results suggestthat large variations of pH commonly reported in aerosol and cloud waters can trigger neo-formation of nanosize Fe particles and an increase in Fe reactivity in the dust

Preparation of alpha-alumina-supported mesoporous bentonite membranes for reverse osmosis desalination of aqueous solutions.

PubMed

Li, Liangxiong; Dong, Junhang; Lee, Robert

2004-05-15

In this study, mesoporous bentonite clay membranes approximately 2 microm thick were prepared on porous alpha-alumina substrates by a sol-gel method. Nanosized clay particles were obtained from commercial Na-bentonite powders (Wyoming) by a process of sedimentation, washing, and freeze-drying. X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and nitrogen adsorption-desorption were employed for membrane characterization. It was found that the content of solids, concentration of polymer binder, and pH value of the clay colloidal suspension had critical influences on membrane formation during the dip-coating process. The membranes were tested for reverse osmosis separation of a 0.1 M NaCl solution. Both water permeability and Na(+) rejection rate of the supported membranes were comparable to those of the compacted thick membranes reported in the literature. However, due to the drastically reduced membrane thickness, water permeance and flux of the supported membranes were significantly higher than those of the compacted thick membranes. It was also observed that the calcination temperature played a critical role in determining structural stability in water and desalination performance of the clay membrane.

Alpha1- and alpha2-containing GABAA receptor modulation is not necessary for benzodiazepine-induced hyperphagia.

PubMed

Morris, H V; Nilsson, S; Dixon, C I; Stephens, D N; Clifton, P G

2009-06-01

Benzodiazepines increase food intake, an effect attributed to their ability to enhance palatability. We investigated which GABA(A) receptor subtypes may be involved in mediating benzodiazepine-induced hyperphagia. The role of the alpha2 subtype was investigated by observing the effects of midazolam, on the behavioural satiety sequence in mice with targeted deletion of the alpha2 gene (alpha2 knockout). Midazolam (0.125, 0.25 and 0.5mg/kg) increased food intake and the amount of time spent feeding in alpha2 knockout mice, suggesting that BZ-induced hyperphagia does not involve alpha2-containing GABA(A) receptors. We further investigated the roles of alpha1- and alpha3-containing GABA(A) receptors in mediating BZ-induced hyperphagia. We treated alpha2(H101R) mice, in which alpha2-containing receptors are rendered benzodiazepine insensitive, with L-838417, a compound which acts as a partial agonist at alpha2-, alpha3- and alpha5-receptors but is inactive at alpha1-containing receptors. L-838417 (10 and 30 mg/kg) increased food intake and the time spent feeding in both wildtype and alpha2(H101R) mice, demonstrating that benzodiazepine-induced hyperphagia does not require alpha1- and alpha2-containing GABA(A) receptors. These observations, together with evidence against the involvement of alpha5-containing GABA(A) receptors, suggest that alpha3-containing receptors mediate BZ-induced hyperphagia in the mouse.

The neurosteroid 3 alpha-hydroxy-5 alpha-pregnan-20-one affects dopamine-mediated behavior in rodents.

PubMed

Khisti, Rahul T; Deshpande, Laxmikant S; Chopde, Chandrabhan T

2002-05-01

The neurosteroid 3alpha-hydroxy-5alpha-pregnan-20-one (3alpha,5alpha-THP) has been previously shown to induce catalepsy in mice that is modified by GABAergic, dopaminergic, adenosinergic and serotonergic agents. In light of the interaction of this endogenous neurosteroid with GABAergic and dopaminergic transmission, there is potential interest in the possible role of 3alpha,5alpha-THP in psychotic disorders. This study assessed the effect of 3alpha,5alpha-THP in certain dopamine-mediated behavioral paradigms that are widely used to predict antipsychotic-like activity. 3alpha,5alpha-THP (1-8 microg per animal, i.c.v.), the classic neuroleptic (dopamine receptor antagonist) haloperidol (0.25 mg/kg, i.p.), and the benzodiazepine diazepam (7 mg/kg, i.p.) were injected into different groups of animals, and their behavior was screened using the following animal tests: conditioned avoidance response, apomorphine-induced climbing, and amphetamine-induced motor hyperactivity. Separate groups of mice that received 3alpha,5alpha-THP (1-8 microg per animal, i.c.v.) were screened for catalepsy. Furthermore, the effect of a sub-cataleptic dose (0.1 microg per mouse, i.c.v.) of 3alpha,5alpha-THP, either alone or in combination with the GABA(A) receptor antagonist picrotoxin (0.8 mg/kg, i.p.) was measured on haloperidol-induced catalepsy. 3alpha,5alpha-THP like haloperidol reduced conditioned avoidance, apomorphine-induced cage climbing and amphetamine-induced motor hyperactivity. Diazepam only affected conditioned avoidance. 3alpha,5alpha-THP also induced dose-dependent catalepsy. Furthermore, sub-cataleptic doses of 3alpha,5alpha-THP potentiated haloperidol-induced catalepsy. This potentiation was blocked by prior treatment with the GABA(A) receptor antagonist picrotoxin. These findings suggest that 3alpha,5alpha-THP, by its action at the GABA(A) receptors, increases GABAergic tone leading to a behavioral profile similar to that of dopamine receptor antagonists.

[Age-related change in the alpha-tocopherolquinone/alpha-tocopherol ratio in the rat erythrocyte membrane].

PubMed

Yanagawa, K; Takeda, H; Matsumiya, T; Takasaki, M

1999-05-01

alpha-Tocopherol (alpha-Toc), a lipophilic phenolic antioxidant that is localized mainly in the biomembrane, protects cells against oxidation-associated cytotoxicity by prevention of membrane lipid peroxidation, maintenance of the redox balance intracellular thiols and stabilization of the membrane structure. We investigated the age-related changes in redox dynamics of alpha-Toc in plasma and erythrocyte membrane of an elderly (66 weeks old) and young group (10 weeks old). Total, alpha-, beta + gamma-, delta-Toc and alpha-tocopherolquinone (alpha-TocQ) in plasma and erythrocyte membrane were determined by high-performance liquid chromatography (HPLC) with a series of multiple coulometric working electrodes (CWE). Rat venous blood sample was divided into plasma and erythrocyte layers by centrifugation, and then erythrocyte membrane sample was prepared according to the method of Dodge et al. under a stream of nitrogen. In plasma, total and alpha-Toc concentrations were increased, and beta + gamma-, delta-Toc and alpha-TocQ concentrations were decreased age-dependently. In the erythrocyte membrane, total, alpha-TocQ concentrations and three fractions of tocopherols decreased age-dependently. Also, a decrease in the alpha-TocQ/alpha-Toc ratio in erythrocyte membrane was observed in the elderly group. These findings suggest that the alpha-Toc uptake in erythrocyte membrane and utilization rate of alpha-Toc in erythrocyte membrane decline age-dependently. This decline may promote membrane lipid peroxidation. alpha-Toc redox dynamics in erythrocyte membrane were useful to investigate the pathophysiology of aging mechanisms related to oxidative stress.

Folate receptor {alpha} regulates cell proliferation in mouse gonadotroph {alpha}T3-1 cells

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

Yao, Congjun; Evans, Chheng-Orn; Stevens, Victoria L.

We have previously found that the mRNA and protein levels of the folate receptor alpha (FR{alpha}) are uniquely over-expressed in clinically human nonfunctional (NF) pituitary adenomas, but the mechanistic role of FR{alpha} has not fully been determined. We investigated the effect of FR{alpha} over-expression in the mouse gonadotroph {alpha}T3-1 cell line as a model for NF pituitary adenomas. We found that the expression and function of FR{alpha} were strongly up-regulated, by Western blotting and folic acid binding assay. Furthermore, we found a higher cell growth rate, an enhanced percentage of cells in S-phase by BrdU assay, and a higher PCNAmore » staining. These observations indicate that over-expression of FR{alpha} promotes cell proliferation. These effects were abrogated in the same {alpha}T3-1 cells when transfected with a mutant FR{alpha} cDNA that confers a dominant-negative phenotype by inhibiting folic acid binding. Finally, by real-time quantitative PCR, we found that mRNA expression of NOTCH3 was up-regulated in FR{alpha} over-expressing cells. In summary, our data suggests that FR{alpha} regulates pituitary tumor cell proliferation and mechanistically may involve the NOTCH pathway. Potentially, this finding could be exploited to develop new, innovative molecular targeted treatment for human NF pituitary adenomas.« less

Effect of toothpaste with nano-sized trimetaphosphate on dental caries: In situ study.

PubMed

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

2015-07-01

This in situ study was to evaluate the remineralizing effect of a fluoride toothpaste supplemented with nano-sized sodium trimetaphosphate (TMP). This blind and cross-over study was performed in 4 phases of 3 days each. Twelve subjects used palatal appliances containing four bovine enamel blocks with artificial caries lesions. Volunteers were randomly assigned into the following treatment groups: Placebo (without F and TMP); 1100 ppm F (1100), 1100 supplemented with 3% micrometric TMP (1100 TMP) and with nano-sized TMP (1100 TMPnano). Volunteers were instructed to brush their natural teeth with the palatal appliances in the mouth during 1min (3 times/day), so that blocks were treated with natural slurries of toothpastes. After each phase, the percentage of surface hardness recovery (%SHR), integrated mineral recovery (IMR) and integrated differential mineral area profile (ΔIMR) in enamel lesions were calculated. F in enamel was also determined. Data were analyzed by ANOVA and Student-Newman-Keuls test. Enamel surface became 20% harder when treated with 1100 TMPnano in comparison with 1100 (p<0.001). 1100 TMPnano showed remineralizing capacity (IMR; ΔIMR) 66% higher when compared with 1100 TMP (p<0.001). Enamel F uptake in the 1100 TMPnano group was 2-fold higher when compared to its counterpart without TMP (p<0.001). The addition of 3% TMPnano to a conventional toothpaste was able to promote an additional remineralizing effect of artificial caries lesions. Toothpaste containing 1100 ppm F associated with TMPnano showed a potential of higher remineralization to 1100 ppm F and 1100 ppm F micrometric TMP. Copyright © 2015 Elsevier Ltd. All rights reserved.

Preparation of hemoglobin-loaded nano-sized particles with porous structure as oxygen carriers.

PubMed

Zhao, Jian; Liu, Chang-Sheng; Yuan, Yuan; Tao, Xin-Yi; Shan, Xiao-Qian; Sheng, Yan; Wu, Fan

2007-03-01

Hb (hemoglobin)-loaded particles (HbP) encapsulated by a biodegradable polymer used as oxygen carrier were prepared. A modified double emulsion and solvent diffusion/evaporation method was adopted. All experiments were performed based on two types of biodegradable polymers, poly(epsilon-caprolactone) (PCL) and poly(epsilon-caprolactone-ethylene glycol) (PCL-PEG). The biodistribution and the survival time in blood of the particles were investigated in a mouse model. Encapsulation efficiency and pore-connecting efficiency were evaluated by a novel sulfocyanate potassium method. The influence of process parameters on the particle size and pore-connecting efficiency (PCE%) of nanoparticles have been discussed. The prepared conditions: solvent, external aqueous phase, pressure were discussed. The system utilizing dichloromethane (DCM)/ethyl acetate (EA) as a solvent with an unsaturated external aqueous phase yielded the highest encapsulation efficiency (87.35%) with a small mean particle size (153 nm). The formation of porous channels was attributed to the diffusion of solvent. The PCE% was more sensitive to the rate of solvent diffusion that was obviously affected by the preparation temperature. The PCE% reached 87.47% when PCL-PEG was employed at 25 degrees C. P(50) of HbP was 27 mmHg, which does not seem to be greatly affected by the encapsulation procedure. In vivo, following intravenous injection of 6-coumarin labeled HbP, the major organ accumulating Hb-loaded particles was the liver. The half-life of nano-sized PCL HbP was 3.1 times as long as the micro-sized PCL HbP. Also, Nano-sized as well as a PEGylated surface on HbP is beneficial for prolonged blood residence (7.2 fold increase).

Human alpha-N-acetylgalactosaminidase (alpha-NAGA) deficiency: no association with neuroaxonal dystrophy?

PubMed

Bakker, H D; de Sonnaville, M L; Vreken, P; Abeling, N G; Groener, J E; Keulemans, J L; van Diggelen, O P

2001-02-01

Two new individuals with alpha-NAGA deficiency are presented. The index patient, 3 years old, has congenital cataract, slight motor retardation and secondary demyelinisation. Screening of his sibs revealed an alpha-NAGA deficiency in his 7-year-old healthy brother who had no clinical or neurological symptoms. Both sibs are homozygous for the E325K mutation, the same genotype that was found in the most severe form of alpha-NAGA deficiency presenting as infantile neuroaxonal dystrophy. Thus, at the age of 7 years the same genotype of alpha-NAGA may present as a 'non-disease' (present healthy case) and can be associated with the vegetative state (the first two patients described with alpha-NAGA deficiency). The clinical heterogeneity among the 11 known individuals with alpha-NAGA deficiency is extreme, with a 'non-disease' (two cases) and infantile neuroaxonal dystrophy (two cases) at the opposite sides of the clinical spectrum. The broad spectrum is completed by a very heterogeneous group of patients with various degrees of epilepsy/behavioural difficulties/psychomotor retardation (four patients) and a mild phenotype in adults without overt neurological manifestations who have angiokeratoma and clear vacuolisation in various cell types (three cases). These observations are difficult to reconcile with a straightforward genotype-phenotype correlation and suggest that factors or genes other than alpha-NAGA contribute to the clinical heterogeneity of the 11 patients with alpha-NAGA deficiency.

Identification of a novel bile acid in swans, tree ducks, and geese: 3alpha,7alpha,15alpha-trihydroxy-5beta-cholan-24-oic acid.

PubMed

Kakiyama, Genta; Iida, Takashi; Goto, Takaaki; Mano, Nariyasu; Goto, Junichi; Nambara, Toshio; Hagey, Lee R; Schteingart, Claudio D; Hofmann, Alan F

2006-07-01

By HPLC, a taurine-conjugated bile acid with a retention time different from that of taurocholate was found to be present in the bile of the black-necked swan, Cygnus melanocoryphus. The bile acid was isolated and its structure, established by (1)H and (13)C NMR and mass spectrometry, was that of the taurine N-acyl amidate of 3alpha,7alpha,15alpha-trihydroxy-5beta-cholan-24-oic acid. The compound was shown to have chromatographic and spectroscopic properties that were identical to those of the taurine conjugate of authentic 3alpha,7alpha,15alpha-trihydroxy-5beta-cholan-24-oic acid, previously synthesized by us from ursodeoxycholic acid. By HPLC, the taurine conjugate of 3alpha,7alpha,15alpha-trihydroxy-5beta-cholan-24-oic acid was found to be present in 6 of 6 species in the subfamily Dendrocygninae (tree ducks) and in 10 of 13 species in the subfamily Anserinae (swans and geese) but not in other subfamilies in the Anatidae family. It was also not present in species from the other two families of the order Anseriformes. 3alpha,7alpha,15alpha-Trihydroxy-5beta-cholan-24-oic acid is a new primary bile acid that is present in the biliary bile acids of swans, tree ducks, and geese and may be termed 15alpha-hydroxy-chenodeoxycholic acid.

Iron oxide minerals in dust-source sediments from the Bodélé Depression, Chad: Implications for radiative properties and Fe bioavailability of dust plumes from the Sahara

USGS Publications Warehouse

Moskowitz, Bruce M; Reynolds, Richard L.; Goldstein, Harland L.; Beroquo, Thelma; Kokaly, Raymond F.; Bristow, Charlie S

2016-01-01

Atmospheric mineral dust can influence climate and biogeochemical cycles. An important component of mineral dust is ferric oxide minerals (hematite and goethite) which have been shown to influence strongly the optical properties of dust plumes and thus affect the radiative forcing of global dust. Here we report on the iron mineralogy of dust-source samples from the Bodélé Depression (Chad, north-central Africa), which is estimated to be Earth’s most prolific dust producer and may be a key contributor to the global radiative budget of the atmosphere as well as to long-range nutrient transport to the Amazon Basin. By using a combination of magnetic property measurements, Mössbauer spectroscopy, reflectance spectroscopy, chemical analysis, and scanning electron microscopy, we document the abundance and relative amounts of goethite, hematite, and magnetite in dust-source samples from the Bodélé Depression. The partition between hematite and goethite is important to know to improve models for the radiative effects of ferric oxide minerals in mineral dust aerosols. The combination of methods shows (1) the dominance of goethite over hematite in the source sediments, (2) the abundance and occurrences of their nanosize components, and (3) the ubiquity of magnetite, albeit in small amounts. Dominant goethite and subordinate hematite together compose about 2% of yellow-reddish dust-source sediments from the Bodélé Depression and contribute strongly to diminution of reflectance in bulk samples. These observations imply that dust plumes from the Bodélé Depression that are derived from goethite-dominated sediments strongly absorb solar radiation. The presence of ubiquitous magnetite (0.002–0.57 wt%) is also noteworthy for its potentially higher solubility relative to ferric oxide and for its small sizes, including PM < 0.1 μm. For all examined samples, the average iron apportionment is estimated at about 33% in ferric oxide minerals, 1.4% in magnetite, and 65

Effects of micro-sized and nano-sized WO3 on mass attenauation coefficients of concrete by using MCNPX code.

PubMed

Tekin, H O; Singh, V P; Manici, T

2017-03-01

In the present work the effect of tungsten oxide (WO 3 ) nanoparticles on mass attenauation coefficients of concrete has been investigated by using MCNPX (version 2.4.0). The validation of generated MCNPX simulation geometry has been provided by comparing the results with standard XCOM data for mass attenuation coefficients of concrete. A very good agreement between XCOM and MCNPX have been obtained. The validated geometry has been used for definition of nano-WO 3 and micro-WO 3 into concrete sample. The mass attenuation coefficients of pure concrete and WO 3 added concrete with micro-sized and nano-sized have been compared. It was observed that shielding properties of concrete doped with WO 3 increased. The results of mass attenauation coefficients also showed that the concrete doped with nano-WO 3 significanlty improve shielding properties than micro-WO 3 . It can be concluded that addition of nano-sized particles can be considered as another mechanism to reduce radiation dose. Copyright © 2016 Elsevier Ltd. All rights reserved.

Nanosized graphene sheets enhanced photoelectric behavior of carbon film on p-silicon substrate

NASA Astrophysics Data System (ADS)

Yang, Lei; Hu, Gaijuan; Zhang, Dongqing; Diao, Dongfeng

2016-07-01

We found that nanosized graphene sheets enhanced the photoelectric behavior of graphene sheets embedded carbon (GSEC) film on p-silicon substrate, which was deposited under low energy electron irradiation in electron cyclotron resonance plasma. The GSEC/p-Si photodiode exhibited good photoelectric performance with photoresponsivity of 206 mA/W, rise and fall time of 2.2, and 4.3 μs for near-infrared (850 nm) light. The origin of the strong photoelectric behavior of GSEC film was ascribed to the appearance of graphene nanosheets, which led to higher barrier height and photoexcited electron-collection efficiency. This finding indicates that GSEC film has the potential for photoelectric applications.

In vitro and in vivo expression of interleukin-1alpha and tumor necrosis factor-alpha mRNA in pemphigus vulgaris: interleukin-1alpha and tumor necrosis factor-alpha are involved in acantholysis.

PubMed

Feliciani, C; Toto, P; Amerio, P; Pour, S M; Coscione, G; Shivji, G; Wang, B; Sauder, D N

2000-01-01

Keratinocyte-derived cytokines have been implicated in the pathogenesis of a number of skin diseases. In this study we examined the possible role of keratinocyte-derived cytokines in the development of acantholysis in pemphigus vulgaris. Nineteen patients with pemphigus vulgaris, demonstrating the characteristic clinical, pathologic, and immunopathologic findings were studied. In situ immunolabeling demonstrated the presence of two cytokines interleukin-1alpha and tumor necrosis factor-alpha, in lesional and perilesional areas. Results were confirmed by reverse transcriptase-polymerase chain reaction, demonstrating overexpression of both cytokines in vivo. To study the role of these cytokines in the pathogenesis of pemphigus vulgaris both in vitro and in vivo studies were performed. The results of the in vitro study demonstrated that pemphigus vulgaris IgG induced interleukin-1alpha and tumor necrosis factor-alpha mRNA in the skin. The potential pathogenic role of these mediators was demonstrated by a blocking study using antibodies against human interleukin-1alpha and tumor necrosis factor-alpha in keratinocytes cultures. A combination of anti-interleukin-1alpha and anti-tumor necrosis factor-alpha antibodies inhibited in vitro pemphigus vulgaris IgG induced acantholysis. To confirm the role of interleukin-1 and tumor necrosis factor-alpha in pemphigus, we utilized passive transfer studies using interleukin-1 deficient mice (ICE-/-, interleukin-1beta-/-) and tumor necrosis factor-alpha receptor deficient mice (TNFR1R2-/-). Both groups demonstrated a decreased susceptibility to the passive transfer of pemphigus. Our data support the role of cytokines interleukin-1 and tumor necrosis factor-alpha in the pathogenesis of pemphigus vulgaris.

Bioequivalence of a Liquid Formulation of Alpha1-Proteinase Inhibitor Compared with Prolastin®-C (Lyophilized Alpha1-PI) in Alpha1-Antitrypsin Deficiency.

PubMed

Barker, Alan F; Campos, Michael A; Brantly, Mark L; Stocks, James M; Sandhaus, Robert A; Lee, Douglas; Steinmann, Kimberly; Lin, Jiang; Sorrells, Susan

2017-12-01

This study evaluated the bioequivalence, safety, and immunogenicity of a new liquid formulation of human plasma-derived alpha 1 -proteinase inhibitor, Liquid Alpha 1 -PI, compared with the Lyophilized Alpha 1 -PI formulation (Prolastin®-C), for augmentation therapy in patients with alpha 1 -antitrypsin deficiency (AATD). In this double-blind, randomized, 20-week crossover study, 32 subjects with AATD were randomized to receive 8 weekly infusions of 60 mg/kg of Liquid Alpha 1 -PI or Lyophilized Alpha 1 -PI. Serial blood samples were drawn for 7 days after the last dose followed by 8 weeks of the alternative treatment. The primary endpoint was bioequivalence at steady state, as measured by area under the concentration versus time curve from 0 to 7 days (AUC 0-7 days ) postdose using an antigenic content assay. Bioequivalence was defined as 90% confidence interval (CI) for the ratio of the geometric least squares (LS) mean of AUC 0-7 days for both products within the limits of 0.80 and 1.25. Safety and immunogenicity were assessed. Mean alpha 1 -PI concentration versus time curves for both formulations were superimposable. Mean AUC 0-7 days was 20 320 versus 19 838 mg × h/dl for Liquid Alpha 1 -PI and Lyophilized Alpha 1 -PI, respectively. The LS mean ratio of AUC 0-7 days (90% CI) for Liquid Alpha 1 -PI versus Lyophilized Alpha 1 -PI was 1.05 (1.03-1.08), indicating bioequivalence. Liquid Alpha 1 -PI was well tolerated and adverse events were consistent with Lyophilized Alpha 1 -PI. Immunogenicity to either product was not detected. In conclusion, Liquid Alpha 1 -PI is bioequivalent to Lyophilized Alpha 1 -PI, with a similar safety profile. The liquid formulation would eliminate the need for reconstitution and shorten preparation time for patients receiving augmentation therapy for AATD.

Methods for the synthesis and polymerization of .alpha.,.alpha.'-dihalo-p-xylenes

DOEpatents

Ferraris, John P.; Neef, Charles J.

2002-07-30

The present invention describes an improved method for the polymerization of .alpha.,.alpha.-dihalo-p-xylene's such as the .alpha.,.alpha.'-dihalo-2-methoxy-5-(2-ethylhexyloxy)-xylene's. The procedure for synthesis is based on the specific order of addition of reagents and the use of an anionic initiator that allows control of the molecular weight of the polymer. The molecular weight control allows processability of the polymer which is important for its utility in applications including in light-emitting-diodes, field effect transistors and photovoltaic devices.

Immunostimulatory effects of natural human interferon-alpha (huIFN-alpha) on carps Cyprinus carpio L.

PubMed

Watanuki, Hironobu; Chakraborty, Gunimala; Korenaga, Hiroki; Kono, Tomoya; Shivappa, R B; Sakai, Masahiro

2009-10-15

Human interferon-alpha (huIFN-alpha) is an important immunomodulatory substance used in the treatment and prevention of numerous infectious and immune-related diseases in animals. However, the immunostimulatory effects of huIFN-alpha in fish remain to be investigated. In the current study, the immune responses of the carp species Cyprinus carpio L. to treatment with huIFN-alpha were analyzed via measurement of superoxide anion production, phagocytic activity and the expression of cytokine genes including interleukin-1beta, tumor necrosis factor-alpha and interleukin 10. Low doses of huIFN-alpha were administered orally once a day for 3 days, and sampling was carried out at 1, 3 and 5 days post-treatment. Our results indicate that a low dose of huIFN-alpha significantly increased phagocytic activity and superoxide anion production in the carp kidney. The huIFN-alpha-treated fish also displayed a significant upregulation in cytokine gene expression. The current study demonstrates the stimulatory effects of huIFN-alpha on the carp immune system and highlights the immunomodulatory role of huIFN-alpha in fish.

Synthesis of 3 alpha,7 alpha,12 alpha,25-tetrahydroxy-5 beta-cholestan-24-one, an intermediate in the 25-hydroxylation pathway of cholic acid biosynthesis from cholesterol.

PubMed

Dayal, B; Tint, G S; Batta, A K; Shefer, S; Salen, G; Bose, A K; Pramanik, B N

1983-02-01

This paper describes the chemical synthesis of 3 alpha,7 alpha,12 alpha,25-tetrahydroxy-5 beta-cholestan-24-one via selective oxidation of 5 beta-cholestane-3 alpha,7 alpha,12 alpha, 24 xi,25-pentol with silver carbonate on celite. The structure of this 24-keto bile alcohol was confirmed by gas-liquid chromatography and mass spectrometry. Synthesis of this compound via pyridinium chlorochromate oxidation of the triacetoxy derivative of 5 beta-cholestane-3 alpha,7 alpha,12 alpha,24 xi,25-pentol followed by saponification further established its structure. 3 alpha,7 alpha,12 alpha,25-Tetrahydroxy-5 beta-cholestan-24-one was required for the in vivo and in vitro studies of side-chain oxidation and cleavage in the 25-hydroxylation pathway of cholic acid biosynthesis.

Ferromagnetic effects for nanofluid venture through composite permeable stenosed arteries with different nanosize particles

NASA Astrophysics Data System (ADS)

Akbar, Noreen Sher; Mustafa, M. T.

2015-07-01

In the present article ferromagnetic field effects for copper nanoparticles for blood flow through composite permeable stenosed arteries is discussed. The copper nanoparticles for the blood flow with water as base fluid with different nanosize particles is not explored upto yet. The equations for the Cu-water nanofluid are developed first time in literature and simplified using long wavelength and low Reynolds number assumptions. Exact solutions have been evaluated for velocity, pressure gradient, the solid volume fraction of the nanoparticles and temperature profile. Effect of various flow parameters on the flow and heat transfer characteristics are utilized.

A new stable alpha chain variant: Hb Basel [alpha14(A12)Trp-->Leu (alpha1)].

PubMed

Hergersberg, Martin; Brunner-Agten, Saskia; Kühne, Thomas; Paulussen, Michael; Huber, Andreas R

2010-06-01

We describe a heterozygosity for a new missense mutation on the alpha1-globin gene of an 18-year-old woman of Portuguese ancestry with severe hypochromic anemia and iron deficiency. Hemoglobin (Hb) analysis by high performance liquid chromatography (HPLC) found a prominent peak constituting about 12% of total Hb. Sequencing of the globin genes of the index patient found the mutation alpha14(A12)Trp-->Leu (alpha1), HBA1:c.44G

Determination of the alpha(s) using jet rates at LEP

NASA Astrophysics Data System (ADS)

Donkers, Michael A.

Jets are produced in any high energy collision of particles in which quarks are produced in the final state. Using the OPAL detector to measure particles produced in e+e- collisions at the LEP accelerator, the rate of jet formation has been measured at 91 GeV as well as each of the LEP2 energies, ranging from 161 GeV to 207 GeV. The jet rate observables, in particular the differential 2-jet rate and the average jet rate can be used to determine a value of the strong coupling constant, alphas, by fitting to various theoretical predictions. The value of alphas has been determined using data at 91 GeV and a combined sample comprising all of the LEP2 energies with a luminosity weighted centre-of-mass energy of 195.8 GeV for 10 theoretical predictions and two jet clustering algorithms. A fit of the 91 GeV and LEP2 values of alphas determined using the ln R matching prediction is also performed on the D2 and distributions to the 3-loop alphas prediction to produce 4 values of alphas(MZ 0).

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.

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.

Focusing of light by polymer-dispersed liquid-crystal films with nanosized droplets

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

Loiko, V. A., E-mail: loiko@dragon.bas-net.by; Konkolovich, A. V.

2006-12-15

An analysis is presented of polarization-independent electrically tunable light focusing by polymerdispersed liquid-crystal films with nanosized liquid-crystal droplets. Polymer-dispersed liquid-crystal films with axially symmetric distributions of liquid-crystal droplet concentration and layers with axially symmetric thickness profiles are considered. The paraxial, Rayleigh, and Rayleigh-Gans approximations, as well as the Foldy-Twersky equation, are used to examine the dependence of focal length on lens geometry, droplet size, concentration of nematic liquid-crystal droplets, and applied field. The tunable focusing ranges are evaluated for both lens types considered in the study. Dependence of the transmittance of polymer-dispersed liquid-crystal film on its characteristics is analyzed. Themore » results obtained are compared with those available from the literature.« less

Screening alpha-glucosidase and alpha-amylase inhibitors from natural compounds by molecular docking in silico.

PubMed

Jhong, Chien-Hung; Riyaphan, Jirawat; Lin, Shih-Hung; Chia, Yi-Chen; Weng, Ching-Feng

2015-01-01

The alpha-glucosidase inhibitor is a common oral anti-diabetic drug used for controlling carbohydrates normally converted into simple sugars and absorbed by the intestines. However, some adverse clinical effects have been observed. The present study seeks an alternative drug that can regulate the hyperglycemia by down-regulating alpha-glucosidase and alpha-amylase activity by molecular docking approach to screen the hyperglycemia antagonist against alpha-glucosidase and alpha-amylase activities from the 47 natural compounds. The docking data showed that Curcumin, 16-hydroxy-cleroda-3,13-dine-16,15-olide (16-H), Docosanol, Tetracosanol, Antroquinonol, Berberine, Catechin, Quercetin, Actinodaphnine, and Rutin from 47 natural compounds had binding ability towards alpha-amylase and alpha-glucosidase as well. Curcumin had a better biding ability of alpha-amylase than the other natural compounds. Analyzed alpha-glucosidase activity reveals natural compound inhibitors (below 0.5 mM) are Curcumin, Actinodaphnine, 16-H, Quercetin, Berberine, and Catechin when compared to the commercial drug Acarbose (3 mM). A natural compound with alpha-amylase inhibitors (below 0.5 mM) includes Curcumin, Berberine, Docosanol, 16-H, Actinodaphnine/Tetracosanol, Catechin, and Quercetin when compared to Acarbose (1 mM). When taken together, the implication is that molecular docking is a fast and effective way to screen alpha-glucosidase and alpha-amylase inhibitors as lead compounds of natural sources isolated from medicinal plants. © 2015 International Union of Biochemistry and Molecular Biology.

Event counting alpha detector

DOEpatents

Bolton, Richard D.; MacArthur, Duncan W.

1996-01-01

An electrostatic detector for atmospheric radon or other weak sources of alpha radiation. In one embodiment, nested enclosures are insulated from one another, open at the top, and have a high voltage pin inside and insulated from the inside enclosure. An electric field is produced between the pin and the inside enclosure. Air ions produced by collision with alpha particles inside the decay volume defined by the inside enclosure are attracted to the pin and the inner enclosure. With low alpha concentrations, individual alpha events can be measured to indicate the presence of radon or other alpha radiation. In another embodiment, an electrical field is produced between parallel plates which are insulated from a single decay cavity enclosure.

Support for the initial attachment, growth and differentiation of MG-63 cells: a comparison between nano-size hydroxyapatite and micro-size hydroxyapatite in composites

PubMed Central

Filová, Elena; Suchý, Tomáš; Sucharda, Zbyněk; Šupová, Monika; Žaloudková, Margit; Balík, Karel; Lisá, Věra; Šlouf, Miroslav; Bačáková, Lucie

2014-01-01

Hydroxyapatite (HA) is considered to be a bioactive material that favorably influences the adhesion, growth, and osteogenic differentiation of osteoblasts. To optimize the cell response on the hydroxyapatite composite, it is desirable to assess the optimum concentration and also the optimum particle size. The aim of our study was to prepare composite materials made of polydimethylsiloxane, polyamide, and nano-sized (N) or micro-sized (M) HA, with an HA content of 0%, 2%, 5%, 10%, 15%, 20%, 25% (v/v) (referred to as N0–N25 or M0–M25), and to evaluate them in vitro in cultures with human osteoblast-like MG-63 cells. For clinical applications, fast osseointegration of the implant into the bone is essential. We observed the greatest initial cell adhesion on composites M10 and N5. Nano-sized HA supported cell growth, especially during the first 3 days of culture. On composites with micro-size HA (2%–15%), MG-63 cells reached the highest densities on day 7. Samples M20 and M25, however, were toxic for MG-63 cells, although these composites supported the production of osteocalcin in these cells. On N2, a higher concentration of osteopontin was found in MG-63 cells. For biomedical applications, the concentration range of 5%–15% (v/v) nano-size or micro-size HA seems to be optimum. PMID:25125978

Preparation and characterization of uniform nanosized cephradine by combination of reactive precipitation and liquid anti-solvent precipitation under high gravity environment.

PubMed

Zhong, Jie; Shen, Zhigang; Yang, Yan; Chen, Jianfeng

2005-09-14

In this work, a novel direct method, which was combined with reactive precipitation and liquid anti-solvent precipitation under high gravity environment, had been developed to prepare nanosized cephradine with narrow particle size distribution. Compared with commercial crude cephradine, the prepared cephradine showed a significant decrease in particle size, a significant increase in the specific surface area and shorter dissolving time when used for injection. The characteristic particle size was between 200-400 nm. The specific surface area increased from 2.95 to 10.87 m2/g after micronization. When the amount of L-arginin decreased from 0.25 to 0.18 g, the mixture of nanosized cephradine and L-arginine could still dissolve in 1 min. The X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR) analysis indicated that the physical characteristics and molecular states remained unchanged after the recrystallization process. This method had potential application in industrial fields because of its low cost, efficient processing and the ease of scaling-up.

The Alpha Centauri System.

ERIC Educational Resources Information Center

Soderblom, David R.

1987-01-01

Describes the Alpha Centauri star system, which is the closest star system to the sun. Discusses the difficulties associated with measurements involving Alpha Centauri, along with some of the recent advances in stellar seismology. Raises questions about the possibilities of planets around Alpha Centauri. (TW)

Alpha Kappa Alpha Sorority's Reading Improvement Program for Minorities.

ERIC Educational Resources Information Center

Marable, June Morehead

This document discusses the founding and establishment of Alpha Kappa Alpha Sorority's reading experience pilot project. The efforts of this project were aligned with those of Right to Read and Reading Is Fundamental (RIF). Because of the response from parents and children, plans are being made to increase present operations within the next…

Solution structure of {alpha}-conotoxin PIA, a novel antagonist of {alpha}6 subunit containing nicotinic acetylcholine receptors

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

Chi, Seung-Wook; Lee, Si-Hyung; Kim, Do-Hyoung

2005-12-30

{alpha}-Conotoxin PIA is a novel nicotinic acetylcholine receptor (nAChR) antagonist isolated from Conus purpurascens that targets nAChR subtypes containing {alpha}6 and {alpha}3 subunits. {alpha}-conotoxin PIA displays 75-fold higher affinity for rat {alpha}6/{alpha}3{beta}2{beta}3 nAChRs than for rat {alpha}3{beta}2 nAChRs. We have determined the three-dimensional structure of {alpha}-conotoxin PIA by nuclear magnetic resonance spectroscopy. The {alpha}-conotoxin PIA has an '{omega}-shaped' overall topology as other {alpha}4/7 subfamily conotoxins. Yet, unlike other neuronally targeted {alpha}4/7-conotoxins, its N-terminal tail Arg{sup 1}-Asp{sup 2}-Pro{sup 3} protrudes out of its main molecular body because Asp{sup 2}-Pro{sup 3}-Cys{sup 4}-Cys{sup 5} forms a stable type I {beta}-turn. In addition, amore » kink introduced by Pro{sup 15} in the second loop of this toxin provides a distinct steric and electrostatic environment from those in {alpha}-conotoxins MII and GIC. By comparing the structure of {alpha}-conotoxin PIA with other functionally related {alpha}-conotoxins we suggest structural features in {alpha}-conotoxin PIA that may be associated with its unique receptor recognition profile.« less

The role of biomineralization in microbiologically influenced corrosion

NASA Technical Reports Server (NTRS)

Little, B.; Wagner, P.; Hart, K.; Ray, R.; Lavoie, D.; Nealson, K.; Aguilar, C.

1998-01-01

Synthetic iron oxides (goethite, alpha-FeO.OH; hematite, Fe2O3; and ferrihydrite, Fe(OH)3) were used as model compounds to simulate the mineralogy of surface films on carbon steel. Dissolution of these oxides exposed to pure cultures of the metal-reducing bacterium, Shewanella putrefaciens, was followed by direct atomic absorption spectroscopy measurement of ferrous iron coupled with microscopic analyses using confocal laser scanning and environmental scanning electron microscopies. During an 8-day exposure the organism colonized mineral surfaces and reduced solid ferric oxides to soluble ferrous ions. Elemental composition, as monitored by energy dispersive x-ray spectroscopy, indicated mineral replacement reactions with both ferrihydrite and goethite as iron reduction occurred. When carbon steel electrodes were exposed to S. putrefaciens, microbiologically influenced corrosion was demonstrated electrochemically and microscopically.

Alpha-Mannosidosis: Therapeutic Strategies.

PubMed

Ceccarini, Maria Rachele; Codini, Michela; Conte, Carmela; Patria, Federica; Cataldi, Samuela; Bertelli, Matteo; Albi, Elisabetta; Beccari, Tommaso

2018-05-17

Alpha-mannosidosis (α-mannosidosis) is a rare lysosomal storage disorder with an autosomal recessive inheritance caused by mutations in the gene encoding for the lysosomal α-d-mannosidase. So far, 155 variants from 191 patients have been identified and in part characterized at the biochemical level. Similarly to other lysosomal storage diseases, there is no relationship between genotype and phenotype in alpha-mannosidosis. Enzyme replacement therapy is at the moment the most effective therapy for lysosomal storage disease, including alpha-mannosidosis. In this review, the genetic of alpha-mannosidosis has been described together with the results so far obtained by two different therapeutic strategies: bone marrow transplantation and enzyme replacement therapy. The primary indication to offer hematopoietic stem cell transplantation in patients affected by alpha-mannosidosis is preservation of neurocognitive function and prevention of early death. The results obtained from a Phase I⁻II study and a Phase III study provide evidence of the positive clinical effect of the recombinant enzyme on patients with alpha-mannosidosis.

Cloning, expression, and mapping of allergenic determinants of alphaS1-casein, a major cow's milk allergen.

PubMed

Schulmeister, Ulrike; Hochwallner, Heidrun; Swoboda, Ines; Focke-Tejkl, Margarete; Geller, Beate; Nystrand, Mats; Härlin, Annika; Thalhamer, Josef; Scheiblhofer, Sandra; Keller, Walter; Niggemann, Bodo; Quirce, Santiago; Ebner, Christoph; Mari, Adriano; Pauli, Gabrielle; Herz, Udo; Valenta, Rudolf; Spitzauer, Susanne

2009-06-01

Milk is one of the first components introduced into human diet. It also represents one of the first allergen sources, which induces IgE-mediated allergies in childhood ranging from gastrointestinal, skin, and respiratory manifestations to severe life-threatening manifestations, such as anaphylaxis. Here we isolated a cDNA coding for a major cow's milk allergen, alphaS1-casein, from a bovine mammary gland cDNA library with allergic patients' IgE Abs. Recombinant alphaS1-casein was expressed in Escherichia coli, purified, and characterized by circular dichroism as a folded protein. IgE epitopes of alphaS1-casein were determined with recombinant fragments and synthetic peptides spanning the alphaS1-casein sequence using microarrayed components and sera from 66 cow's milk-sensitized patients. The allergenic activity of ralphaS1-casein and the alphaS1-casein-derived peptides was determined using rat basophil leukemia cells transfected with human FcepsilonRI, which had been loaded with the patients' serum IgE. Our results demonstrate that ralphaS1-casein as well as alphaS1-casein-derived peptides exhibit IgE reactivity, but mainly the intact ralphaS1-casein induced strong basophil degranulation. These results suggest that primarily intact alphaS1-casein or larger IgE-reactive portions thereof are responsible for IgE-mediated symptoms of food allergy. Recombinant alphaS1-casein as well as alphaS1-casein-derived peptides may be used in clinical studies to further explore pathomechanisms of food allergy as well as for the development of new diagnostic and therapeutic strategies for milk allergy.

Event counting alpha detector

DOEpatents

Bolton, R.D.; MacArthur, D.W.

1996-08-27

An electrostatic detector is disclosed for atmospheric radon or other weak sources of alpha radiation. In one embodiment, nested enclosures are insulated from one another, open at the top, and have a high voltage pin inside and insulated from the inside enclosure. An electric field is produced between the pin and the inside enclosure. Air ions produced by collision with alpha particles inside the decay volume defined by the inside enclosure are attracted to the pin and the inner enclosure. With low alpha concentrations, individual alpha events can be measured to indicate the presence of radon or other alpha radiation. In another embodiment, an electrical field is produced between parallel plates which are insulated from a single decay cavity enclosure. 6 figs.

Distinct expression pattern of IFN-alpha and TNF-alpha in juvenile idiopathic arthritis synovial tissue.

PubMed

Gattorno, M; Chicha, L; Gregorio, A; Ferlito, F; Rossi, F; Jarrossay, D; Lanzavecchia, A; Martini, A; Manz, M G

2007-04-01

Recent laboratory and clinical data suggest that two prototype autoimmune diseases, systemic lupus erythematosus and rheumatoid arthritis are mainly driven by distinct cytokines, interferon (IFN)-alpha and tumour necrosis factor (TNF)-alpha, respectively. We here investigated the presence and characteristics of natural type I IFN-producing cells (IPCs), as well as IFN-alpha and TNF-alpha expression at sites of inflammation in juvenile idiopathic arthritis (JIA). Peripheral blood (PB) and synovial fluid (SF) mononuclear cells (MNCs) (n = 25 each) from JIA patients with active disease were studied. IPCs were identified as BCDA-2(+)CD123(+)HLA-DR(+)CD45RA(+) cells, and dendritic cells (DCs) as CD11c(+)CD14(-/low)lin(-) cells by flow cytometry. IPCs and DCs were analysed for Toll-like receptor-7 and -9 mRNA expression by real-time polymerase chain reaction. IFN-alpha was measured by enzyme-linked immunosorbent assay in serum, SF and in supernatants of influenza virus-infected, cultured IPCs. Synovial tissues of n = 6 additional JIA patients were analysed by immunohistochemistry using mAbs against CD123, IFN-alpha, TNF-alpha, CD3, CD19 and CD138. IPCs were enriched in SF MNCs compared with PB MNCs in all JIA patients. Influenza-induced, but no spontaneous IFN-alpha release was detected from SF IPCs, and serum and SF IFN-alpha levels were not elevated. Nonetheless, in synovial tissue IFN-alpha producing cells accumulated at inflammatory lymph-follicular-like structures, while TNF-alpha producing cells were mostly found at the lining and sublining layers. These data suggest that besides TNF-alpha-expressing cells, IFN-alpha-producing IPCs are involved in initiation, maintenance or regulation of the inflammatory response in JIA.

A Silica-Supported Iron Oxide Catalyst Capable of Activating Hydrogen Peroxide at Neutral pH Values

PubMed Central

Pham, Anh Le-Tuan; Lee, Changha; Doyle, Fiona M.; Sedlak, David L.

2009-01-01

Iron oxides catalyze the conversion of hydrogen peroxide (H2O2) into oxidants capable of transforming recalcitrant contaminants. Unfortunately, the process is relatively inefficient at circumneutral pH values due to competing reactions that decompose H2O2 without producing oxidants. Silica- and alumina-containing iron oxides prepared by sol-gel processing of aqueous solutions containing Fe(ClO4)3, AlCl3 and tetraethyl orthosilicate efficiently catalyzed the decomposition of H2O2 into oxidants capable of transforming phenol at circumneutral pH values. Relative to hematite, goethite and amorphous FeOOH, the silica-iron oxide catalyst exhibited a stoichiometric efficiency, defined as the number of moles of phenol transformed per mole of H2O2 consumed, that was 10 to 40 times higher than that of the iron oxides. The silica-alumina-iron oxide catalyst had a stoichiometric efficiency that was 50 to 80 times higher than that of the iron oxides. The significant enhancement in oxidant production is attributable to the interaction of Fe with Al and Si in the mixed oxides, which alters the surface redox processes, favoring the production of strong oxidants during H2O2 decomposition. PMID:19943668

alpha-Adrenergic-mediated activation of human reconstituted fibrinogen receptor (integrin alphaIIbbeta3) in Chinese hamster ovary cells.

PubMed

Butta, Nora; Larrucea, Susana; Gonzalez-Manchon, Consuelo; Alonso, Sonia; Parrilla, Roberto

2004-12-01

This work reports the functional studies of CHO cells coexpressing alpha-adrenergic (alphaAR) and human fibrinogen (Fg) receptors (integrin alphaIIbbeta3). Stimulation of these cells with alpha-agonists produced a transient rise in the free cytosolic calcium (Ca(++)) accompanied by enhanced binding to soluble Fg, and these effects were prevented by specific alphaAR antagonists. The alpha-adrenergic-induced activation of alphaIIbbeta3 in CHO-alphaIIbbeta3-alphaAR increased the rate of adhesion and extension of cells onto Fg coated plates, and also induced a soluble Fg- and alphaIIbbeta3-dependent formation of cell aggregates, whereas no effects were observed by the stimulation of CHO-alphaIIbbeta3 cells. alpha-Adrenergic antagonists, the ligand mimetic peptide RGDS, pertussis toxin (PTX), or EDTA, they all prevented the alpha-adrenergic stimulation of adhesion and aggregation. However, inhibition of PKC prevented the alpha-adrenergic stimulation of cell adherence, whereas blocking the intracellular Ca(++) mobilization impeded the stimulation of cell aggregation. The alpha-adrenergic activation was associated with phosphorylation of a protein of approximately 100 kDa and proteins of the MAPK family. The former was selectively phosphorylated by alpha-adrenergic stimulation whereas the latter were phosphorylated by the binding of cells to Fg and markedly intensified by alpha-adrenergic stimulation.

Nanosized aluminum altered immune function.

PubMed

Braydich-Stolle, Laura K; Speshock, Janice L; Castle, Alicia; Smith, Marcus; Murdock, Richard C; Hussain, Saber M

2010-07-27

On the basis of their uses in jet fuels and munitions, the most likely scenario for aluminum nanoparticle (NP) exposure is inhalation. NPs have been shown to be capable of penetrating deep into the alveolar regions of the lung, and therefore human alveolar macrophages (U937) with human type II pneumocytes (A549) were cultured together and exposed to NPs dispersed in an artificial lung surfactant to more accurately mimic the lung microenvironment. Two types of NPs were evaluated: aluminum (Al) and aluminum oxide (Al2O3). Following a 24-h incubation, cell viability was assessed using MTS, and mild toxicity was observed at higher doses with the U937 cells affected more than the A549. Since the U937 cells provided protection from NP toxicity, the cocultures were exposed to a benign concentration of NPs and infected with the respiratory pathogen community-associated methicillin-resistant Staphylococcus aureus (ca-MRSA) to determine any changes in cellular function. Phagocytosis assays demonstrated that the NPs impaired phagocytic function, and bacterial growth curves confirmed that this reduction in phagocytosis was not related to NP-bacteria interactions. Furthermore, NFkappaB PCR arrays and an IL-6 and TNF-alpha real time PCR demonstrated that both types of NPs altered immune response activation. This change was confirmed by ELISA assays that evaluated the secretion of IL-6, IL-8, IL-10, IL-1beta, and TNF-alpha and illustrated that the NPs repressed secretion of these cytokines. Therefore, although the NPs were not toxic to the cells, they did impair the cell's natural ability to respond to a respiratory pathogen regardless of NP composition.

Urokinase plasminogen activator mRNA is induced by IL-1alpha and TNF-alpha in in vitro acantholysis.

PubMed

Feliciani, Claudio; Toto, Paola; Wang, Binghe; Sauder, Daniel N; Amerio, Pierluigi; Tulli, Antonio

2003-08-01

The role of urokinase type plasminogen activator (uPA) has been well documented in the pathogenesis of pemphigus vulgaris (PV). Activation of plasminogen into active serine protease plasmin initiates extracellular proteolysis leading to acantholysis but the mechanisms underlying this process are not clearly understood. We have previously shown that keratinocyte derived cytokines IL-1alpha and TNF-alpha are involved in PV-induced acantholysis. In the present study we sought to examine whether keratinocyte-derived IL-1alpha and TNF-alpha are correlated with uPA induction in keratinocytes during acantholysis. Normal human keratinocytes were incubated with diluted PV serum. mRNAs for IL-1alpha, TNF-alpha and uPA were examined with RT-PCR at various time points and acantholysis was measured. IL-1alpha, TNF-alpha and uPA mRNAs were all induced in keratinocytes following PV serum stimulation; IL-1alpha/TNF-alpha mRNAs' expression was earlier than the expression of uPA mRNA. To further examine the role of IL-1alpha, TNF-alpha and uPA in acantholysis, we performed antibody blocking studies. Anti-IL-1alpha, anti-TNF-alpha and anti-uPA antibodies suppressed acantholysis by 76%, 80% and 90%, respectively. In addition, anti-IL-1alpha and anti-TNF-alpha antibodies inhibited uPA mRNA induction, whereas anti-uPA antibodies did not alter IL-1alpha/TNF-alpha mRNAs' expression. Our results confirm the role of uPA in acantholysis and suggest an involvement of IL-1alpha/TNF-alpha in uPA induction.

Total alpha-fetoprotein and Lens culinaris agglutinin-reactive alpha-fetoprotein in fetal chromosomal abnormalities.

PubMed

Yamamoto, R; Azuma, M; Kishida, T; Yamada, H; Satomura, S; Fujimoto, S

2001-11-01

To examine the differences in multiples of the median (MoM) of total alpha-fetoprotein, and the proportion of Lens culinaris agglutinin reactive alpha-fetoprotein (% alpha-fetoprotein-L2 + L3) in the maternal serum and amniotic fluid of pregnant women whose fetuses were diagnosed with autosomal or sex chromosomal abnormalities. Prospective consecutive series. University hospital. Maternal sera and amniotic fluids from 46 pregnant women with trisomy 21 fetuses, 10 pregnant women with trisomy 18 fetuses, one pregnant woman with a trisomy 13 fetus, six pregnant women with fetal sex chromosomal abnormalities, and 100 pregnant women for whom the fetal karyotype was diagnosed as normal following a genetic amniocentesis. The proportion of alpha-fetoprotein-L2 + L3 in maternal serum for trisomy 21 (40.3%. P < 0.0001) and trisomy 18 (39.8%, P < 0.05) showed a significantly higher value compared with normal (32.6%). The proportion of alpha-fetoprotein-L2 + L3 in amniotic fluid was significantly higher (P < 0.0001) for trisomy 21 (46.6%) than for a normal karyotype (41.5%). Only for the trisomy 21 group was there a strong correlation in the % alpha-fetoprotein-L2 + L3 between maternal serum and amniotic fluid (r = 0.840, P < 0.0001). For all groups, there was no correlation between alpha-fetoprotein MoM and % alpha-fetoprotein-L2 + L3 in maternal serum and amniotic fluid. The proportion of alpha-fetoprotein-L2 + L3 in maternal serum is an appropriate choice for a trisomy 21 biochemical marker, and it is possible that combining alpha-fetoprotein-L2 + L3 analysis with assays of alpha-fetoprotein in maternal serum could further improve the sensitivity and specificity of multiple marker screening.

Localization and characterization of an alpha-thrombin-binding site on platelet glycoprotein Ib alpha.

PubMed

De Marco, L; Mazzucato, M; Masotti, A; Ruggeri, Z M

1994-03-04

Glycoprotein (GP) Ib alpha is required for expression of the highest affinity alpha-thrombin-binding site on platelets, possibly contributing to platelet activation through a pathway involving cleavage of a specific receptor. This function may be important for the initiation of hemostasis and may also play a role in the development of pathological vascular occlusion. We have now identified a discrete sequence in the extracytoplasmic domain of GP Ib alpha, including residues 271-284 of the mature protein, which appears to be part of the high affinity alpha-thrombin-binding site. Synthetic peptidyl mimetics of this sequence inhibit alpha-thrombin binding to GP Ib as well as platelet activation and aggregation induced by subnanomolar concentrations of the agonist; they also inhibit alpha-thrombin binding to purified glycocalicin, the isolated extracytoplasmic portion of GP Ib alpha. The inhibitory peptides interfere with the clotting of fibrinogen by alpha-thrombin but not with the amidolytic activity of the enzyme on a small synthetic substrate, a finding compatible with the concept that the identified GP Ib alpha sequence interacts with the anion-binding exosite of alpha-thrombin but not with its active proteolytic site. The crucial structural elements of this sequence necessary for thrombin binding appear to be a cluster of negatively charged residues as well as three tyrosine residues that, in the native protein, may be sulfated. GP Ib alpha has no significant overall sequence homology with the thrombin inhibitor, hirudin, nor with the specific thrombin receptor on platelets; all three molecules, however, possess a distinct region rich in negatively charged residues that appear to be involved in thrombin binding. This may represent a case of convergent evolution of unrelated proteins for high affinity interaction with the same ligand.

Functional coupling of rat myometrial alpha 1-adrenergic receptors to Gh alpha/tissue transglutaminase 2 during pregnancy.

PubMed

Dupuis, Morgan; Lévy, Arlette; Mhaouty-Kodja, Sakina

2004-04-30

Gh alpha protein, which exhibits both transglutaminase and GTPase activities, represents a new class of GTP-binding proteins. In the present study, we characterized Gh alpha in rat uterine smooth muscle (myometrium) and followed its expression during pregnancy by reverse transcription-PCR and Western blot. We also measured transglutaminase and GTP binding functions and used a smooth muscle cell line to evaluate the role of Gh alpha in cell proliferation. The results show that pregnancy is associated with an up-regulation of Gh alpha expression at both the mRNA and protein level. Gh alpha induced during pregnancy is preferentially localized to the plasma membrane. This was found associated with an increased ability of plasma membrane preparations to catalyze Ca(2+)-dependent incorporation of [(3)H]putrescine into casein in vitro. In the cytosol, significant changes in the level of immunodetected Gh alpha and transglutaminase activity were seen only at term. Activation of alpha1-adrenergic receptors (alpha1-AR) enhanced photoaffinity labeling of plasma membrane Gh alpha. Moreover, the level of alpha1-AR-coupled Gh alpha increased progressively with pregnancy, which parallels the active period of myometrial cell proliferation. Overexpression of wild type Gh alpha in smooth muscle cell line DDT1-MF2 increased alpha1-AR-induced [(3)H]thymidine incorporation. A similar response was obtained in cells expressing the transglutaminase inactive mutant (C277S) of Gh alpha. Together, these findings underscore the role of Gh alpha as signal transducer of alpha1-AR-induced smooth muscle cell proliferation. In this context, pregnant rat myometrium provides an interesting physiological model to study the mechanisms underlying the regulation of the GTPase function of Gh alpha

Preparation and photo-catalytic activities of FeOOH/ZnO/MMT composite

NASA Astrophysics Data System (ADS)

Zhou, Yao; Liu, Fusheng; Yu, Shitao

2015-11-01

Montmorillonite (MMT) was used as the carrier for synthesis of FeOOH and FeOOH/ZnO nano-material. FeOOH and FeOOH/ZnO were synthesized by the aqueous solutions of Fe(NO3)3-HNO3 and Zn(NO3)2-NaOH/Fe(NO3)3-HNO3 with the carrier of montmorillonite respectively. Transmission electron-microscopy (TEM) and X-ray diffraction (XRD) were used to study the morphology form and structure of the nano-materials. TEM was also used to demonstrate that FeOOH/ZnO can be formed with the appropriate interface. According to UV-vis absorption spectra, FeOOH/ZnO has a better response to visible light than FeOOH and ZnO, which indicates there is some coupling effect between FeOOH and ZnO. Pentachlorophenol (PCP) was used as a representative organic pollutant to evaluate the photo-catalytic efficiency of the FeOOH/ZnO and FeOOH catalysts in visible light (λ > 400 nm). The photo-catalytic efficiency of FeOOH/ZnO/MMT is better than FeOOH/MMT. According to FTIR, changes of pH and TOC, the degradation mechanism was also discussed. PCP was degraded to aromatic ketone and chloro-hydrocarbon compounds and then to H2O, CO2 and HCl.

The alpha channeling effect

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

Fisch, N. J.

2015-12-10

Alpha particles born through fusion reactions in a tokamak reactor tend to slow down on electrons, but that could take up to hundreds of milliseconds. Before that happens, the energy in these alpha particles can destabilize on collisionless timescales toroidal Alfven modes and other waves, in a way deleterious to energy confinement. However, it has been speculated that this energy might be instead be channeled into useful energy, so as to heat fuel ions or to drive current. Such a channeling needs to be catalyzed by waves Waves can produce diffusion in energy of the alpha particles in a waymore » that is strictly coupled to diffusion in space. If these diffusion paths in energy-position space point from high energy in the center to low energy on the periphery, then alpha particles will be cooled while forced to the periphery. The energy from the alpha particles is absorbed by the wave. The amplified wave can then heat ions or drive current. This process or paradigm for extracting alpha particle energy collisionlessly has been called alpha channeling. While the effect is speculative, the upside potential for economical fusion is immense. The paradigm also operates more generally in other contexts of magnetically confined plasma.« less

The alpha channeling effect

NASA Astrophysics Data System (ADS)

Fisch, N. J.

2015-12-01

Alpha particles born through fusion reactions in a tokamak reactor tend to slow down on electrons, but that could take up to hundreds of milliseconds. Before that happens, the energy in these alpha particles can destabilize on collisionless timescales toroidal Alfven modes and other waves, in a way deleterious to energy confinement. However, it has been speculated that this energy might be instead be channeled into useful energy, so as to heat fuel ions or to drive current. Such a channeling needs to be catalyzed by waves Waves can produce diffusion in energy of the alpha particles in a way that is strictly coupled to diffusion in space. If these diffusion paths in energy-position space point from high energy in the center to low energy on the periphery, then alpha particles will be cooled while forced to the periphery. The energy from the alpha particles is absorbed by the wave. The amplified wave can then heat ions or drive current. This process or paradigm for extracting alpha particle energy collisionlessly has been called alpha channeling. While the effect is speculative, the upside potential for economical fusion is immense. The paradigm also operates more generally in other contexts of magnetically confined plasma.

Influence of fast alpha diffusion and thermal alpha buildup on tokamak reactor performance

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

Uckan, N.A.; Tolliver, J.S.; Houlberg, W.A.

1987-11-01

The effect of fast alpha diffusion and thermal alpha accumulation on the confinement capability of a candidate Engineering Test Reactor (ETR) plasma (Tokamak Ignition/Burn Experimental Reactor (TIBER-II)) in achieving ignition and steady-state driven operation has been assessed using both global and 1-1/2-D transport models. Estimates are made of the threshold for radial diffusion of fast alphas and thermal alpha buildup. It is shown that a relatively low level of radial transport, when combined with large gradients in the fast alpha density, leads to a significant radial flow with a deleterious effect on plasma performance. Similarly, modest levels of thermal alphamore » concentration significantly influence the ignition and steady-state burn capability. 23 refs., 9 figs., 4 tabs.« less

Synthesis and Reaction Chemistry of Nanosize Monosodium Titanate

PubMed Central

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

2016-01-01

This paper describes the synthesis and peroxide-modification of nanosize monosodium titanate (nMST), along with an ion-exchange reaction to load the material with Au(III) ions. The synthesis method was derived from a sol-gel process used to produce micron-sized monosodium titanate (MST), with several key modifications, including altering reagent concentrations, omitting a particle seed step, and introducing a non-ionic surfactant to facilitate control of particle formation and growth. The resultant nMST material exhibits spherical-shaped particle morphology with a monodisperse distribution of particle diameters in the range from 100 to 150 nm. The nMST material was found to have a Brunauer-Emmett-Teller (BET) surface area of 285 m2g-1, which is more than an order of magnitude higher than the micron-sized MST. The isoelectric point of the nMST measured 3.34 pH units, which is a pH unit lower than that measured for the micron-size MST. The nMST material was found to serve as an effective ion exchanger under weakly acidic conditions for the preparation of an Au(III)-exchange nanotitanate. In addition, the formation of the corresponding peroxotitanate was demonstrated by reaction of the nMST with hydrogen peroxide. PMID:26967828

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.

Resting-State Alpha in Autism Spectrum Disorder and Alpha Associations with Thalamic Volume

ERIC Educational Resources Information Center

Edgar, J. Christopher; Heiken, Kory; Chen, Yu-Han; Herrington, John D.; Chow, Vivian; Liu, Song; Bloy, Luke; Huang, Mingxiong; Pandey, Juhi; Cannon, Katelyn M.; Qasmieh, Saba; Levy, Susan E.; Schultz, Robert T.; Roberts, Timothy P. L.

2015-01-01

Alpha circuits (8-12 Hz), necessary for basic and complex brain processes, are abnormal in autism spectrum disorder (ASD). The present study obtained estimates of resting-state (RS) alpha activity in children with ASD and examined associations between alpha activity, age, and clinical symptoms. Given that the thalamus modulates cortical RS alpha…

Molecular cloning and expression analysis of sea bass (Dicentrarchus labrax L.) tumor necrosis factor-alpha (TNF-alpha).

PubMed

Nascimento, Diana S; Pereira, Pedro J B; Reis, Marta I R; do Vale, Ana; Zou, Jun; Silva, Manuel T; Secombes, Christopher J; dos Santos, Nuno M S

2007-09-01

In the search for pro-inflammatory genes in sea bass a TNF-alpha gene was cloned and sequenced. The sea bass TNF-alpha (sbTNF-alpha) putative protein conserves the TNF-alpha family signature, as well as the two cysteines usually involved in the formation of a disulfide bond. The mouse TNF-alpha Thr-Leu cleavage sequence and a potential transmembrane domain were also found, suggesting that sbTNF-alpha exists as two forms: a approximately 28 kDa membrane-bound form and a approximately 18.4 kDa soluble protein. The single copy sbTNF-alpha gene contains a four exon-three intron structure similar to other known TNF-alpha genes. Homology modeling of sbTNF-alpha is compatible with the trimeric quaternary architecture of its mammalian counterparts. SbTNF-alpha is constitutively expressed in several unstimulated tissues, and was not up-regulated in the spleen and head-kidney, in response to UV-killed Photobacterium damselae subsp. piscicida. However, an increase of sbTNF-alpha expression was detected in the head-kidney during an experimental infection using the same pathogen.

Vortex assisted solid-phase extraction of lead(II) using orthorhombic nanosized Bi2WO6 as a sorbent.

PubMed

Baghban, Neda; Yilmaz, Erkan; Soylak, Mustafa

2017-12-07

Nanosized single crystal orthorhombic Bi 2 WO 6 was synthesized by a hydrothermal method and used as a sorbent for vortex assisted solid phase extraction of lead(II). The crystal and molecular structure of the sorbent was examined using XRD, Raman, SEM and SEM-EDX analysis. Various parameters affecting extraction efficiency were optimized by using multivariate design. The effect of diverse ions on the extraction also was studied. Lead was quantified by flame atomic absorption spectrometry (FAAS). The recoveries of lead(II) from spiked samples (at a typical spiking level of 200-400 ng·mL -1 ) are >95%. Other figures of merit includes (a) a detection limit of 6 ng·mL -1 , (b) a preconcentration factor of 50, (c) a relative standard deviation of 1.6%, and (d) and adsorption capacity of 6.6 mg·g -1 . The procedure was successfully applied to accurate determination of lead in (spiked) pomegranate and water samples. Graphical abstract Nanosized single crystal orthorhombic Bi 2 WO 6 was synthesized and characterized by a hydrothermal method and used as a sorbent for vortex assisted solid phase extraction of lead(II). The procedure was successfully applied to accurate determination of lead in (spiked) pomegranate and water samples.

Involvement of the Clock Gene Rev-erb alpha in the Regulation of Glucagon Secretion in Pancreatic Alpha-Cells

PubMed Central

Vieira, Elaine; Marroquí, Laura; Figueroa, Ana Lucia C.; Merino, Beatriz; Fernandez-Ruiz, Rebeca; Nadal, Angel; Burris, Thomas P.; Gomis, Ramon; Quesada, Ivan

2013-01-01

Disruption of pancreatic clock genes impairs pancreatic beta-cell function, leading to the onset of diabetes. Despite the importance of pancreatic alpha-cells in the regulation of glucose homeostasis and in diabetes pathophysiology, nothing is known about the role of clock genes in these cells. Here, we identify the clock gene Rev-erb alpha as a new intracellular regulator of glucagon secretion. Rev-erb alpha down-regulation by siRNA (60–70% inhibition) in alphaTC1-9 cells inhibited low-glucose induced glucagon secretion (p<0.05) and led to a decrease in key genes of the exocytotic machinery. The Rev-erb alpha agonist GSK4112 increased glucagon secretion (1.6 fold) and intracellular calcium signals in alphaTC1-9 cells and mouse primary alpha-cells, whereas the Rev-erb alpha antagonist SR8278 produced the opposite effect. At 0.5 mM glucose, alphaTC1-9 cells exhibited intrinsic circadian Rev-erb alpha expression oscillations that were inhibited by 11 mM glucose. In mouse primary alpha-cells, glucose induced similar effects (p<0.001). High glucose inhibited key genes controlled by AMPK such as Nampt, Sirt1 and PGC-1 alpha in alphaTC1-9 cells (p<0.05). AMPK activation by metformin completely reversed the inhibitory effect of glucose on Nampt-Sirt1-PGC-1 alpha and Rev-erb alpha. Nampt inhibition decreased Sirt1, PGC-1 alpha and Rev-erb alpha mRNA expression (p<0.01) and glucagon release (p<0.05). These findings identify Rev-erb alpha as a new intracellular regulator of glucagon secretion via AMPK/Nampt/Sirt1 pathway. PMID:23936124

Exposure to nano-size titanium dioxide causes oxidative damages in human mesothelial cells: The crystal form rather than size of particle contributes to cytotoxicity.

PubMed

Hattori, Kenji; Nakadate, Kazuhiko; Morii, Akane; Noguchi, Takumi; Ogasawara, Yuki; Ishii, Kazuyuki

2017-10-14

Exposure to nanoparticles such as carbon nanotubes has been shown to cause pleural mesothelioma similar to that caused by asbestos, and has become an environmental health issue. Not only is the percutaneous absorption of nano-size titanium dioxide particles frequently considered problematic, but the possibility of absorption into the body through the pulmonary route is also a concern. Nevertheless, there are few reports of nano-size titanium dioxide particles on respiratory organ exposure and dynamics or on the mechanism of toxicity. In this study, we focused on the morphology as well as the size of titanium dioxide particles. In comparing the effects between nano-size anatase and rutile titanium dioxide on human-derived pleural mesothelial cells, the anatase form was shown to be actively absorbed into cells, producing reactive oxygen species and causing oxidative damage to DNA. In contrast, we showed for the first time that the rutile form is not easily absorbed by cells and, therefore, does not cause oxidative DNA damage and is significantly less damaging to cells. These results suggest that with respect to the toxicity of titanium dioxide particles on human-derived mesothelial cells, the crystal form rather than the particle size has a greater effect on cellular absorption. Also, it was indicated that the difference in absorption is the primary cause of the difference in the toxicity against mesothelial cells. Copyright © 2017 Elsevier Inc. All rights reserved.

Noncatalytic hydrogenation of decene-1 with hydrogen accumulated in a hybrid carbon nanostructure in nanosized membrane reactors

NASA Astrophysics Data System (ADS)

Soldatov, A. P.

2014-08-01

Studies on the creation of nanosized membrane reactors (NMRs) of a new generation with accumulated hydrogen and a regulated volume of reaction zone were continued at the next stage. Hydrogenation was performed in the pores of ceramic membranes with hydrogen preliminarily adsorbed in mono- and multilayered orientated carbon nanotubes with graphene walls (OCNTGs)—a new hybrid carbon nanostructure formed on the inner pore surface. Quantitative determination of hydrogen adsorption in OCNTGs was performed using TRUMEM ultrafiltration membranes with D av = 50 and 90 nm and showed that hydrogen adsorption was up to ˜1.5% of the mass of OCNTG. The instrumentation and procedure for noncatalytic hydrogenation of decene-1 at 250-350°C using hydrogen accumulated and stored in OCNTG were developed. The conversion of decene-1 into decane was ˜0.2-1.8% at hydrogenation temperatures of 250 and 350°C, respectively. The rate constants and activation energy of hydrogenation were determined. The latter was found to be 94.5 kJ/mol, which is much smaller than the values typical for noncatalytic hydrogenations and very close to the values characteristic for catalytic reactions. The quantitative distribution of the reacting compounds in each pore regarded as a nanosized membrane reactor was determined. The activity of hydrogen adsorbed in a 2D carbon nanostructure was evaluated. Possible mechanisms of noncatalytic hydrogenation were discussed.

Porous carbon nanotubes decorated with nanosized cobalt ferrite as anode materials for high-performance lithium-ion batteries

NASA Astrophysics Data System (ADS)

Wang, Lingyan; Zhuo, Linhai; Cheng, Haiyang; Zhang, Chao; Zhao, Fengyu

2015-06-01

Generally, the fast ion/electron transport and structural stability dominate the superiority in lithium-storage applications. In this work, porous carbon nanotubes decorated with nanosized CoFe2O4 particles (p-CNTs@CFO) have been rationally designed and synthesized by the assistance of supercritical carbon dioxide (scCO2). When tested as anode materials for lithium-ion batteries, the p-CNTs@CFO composite exhibits outstanding electrochemical behavior with high lithium-storage capacity (1077 mAh g-1 after 100 cycles) and rate capability (694 mAh g-1 at 3 A g-1). These outstanding electrochemical performances are attributed to the synergistic effect of porous p-CNTs and nanosized CFO. Compared to pristine CNTs, the p-CNTs with substantial pores in the tubes possess largely increased specific surface area and rich oxygen-containing functional groups. The porous structure can not only accommodate the volume change during lithiation/delithiation processes, but also provide bicontinuous electron/ion pathways and large electrode/electrolyte interface, which facilitate the ion diffusion kinetics, improving the rate performance. Moreover, the CFO particles are bonded strongly to the p-CNTs through metal-oxygen bridges, which facilitate the electron fast capture from p-CNTs to CFO, and thus resulting in a high reversible capacity and excellent rate performance. Overall, the porous p-CNTs provide an efficient way for ion diffusion and continuous electron transport as anode materials.

Genetics Home Reference: alpha thalassemia

MedlinePlus

... Facebook Twitter Home Health Conditions Alpha thalassemia Alpha thalassemia Printable PDF Open All Close All Enable Javascript to view the expand/collapse boxes. Description Alpha thalassemia is a blood disorder that reduces the production ...

Coaching the alpha male.

PubMed

Ludeman, Kate; Erlandson, Eddie

2004-05-01

Highly intelligent, confident, and successful, alpha males represent about 70% of all senior executives. Natural leaders, they willingly take on levels of responsibility most rational people would find overwhelming. But many of their quintessential strengths can also make alphas difficult to work with. Their self-confidence can appear domineering. Their high expectations can make them excessively critical. Their unemotional style can keep them from inspiring their teams. That's why alphas need coaching to broaden their interpersonal tool kits while preserving their strengths. Drawing from their experience coaching more than 1,000 senior executives, the authors outline an approach tailored specifically for the alpha. Coaches get the alpha's attention by inundating him with data from 360-degree feedback presented in ways he will find compelling--both hard-boiled metrics and vivid verbatim comments from colleagues about his strengths and weaknesses. A 360-degree assessment is a wake-up call for most alphas, providing undeniable proof that their behavior doesn't work nearly as well as they think it does. That paves the way for a genuine commitment to change. In order to change, the alpha must venture into unfamiliar--and often uncomfortable--psychological territory. He must admit vulnerability, accept accountability not just for his own work for others', connect with his underlying emotions, learn to motivate through a balance of criticism and validation, and become aware of unproductive behavior patterns. The goal of executive coaching is not simply to treat the alpha as an individual problem but to improve the entire team dynamic. Initial success creates an incentive to persevere, and the virtuous cycle reverberates throughout the entire organization.

Experimental and Theoretical Electron Density Distribution of Alpha,Alpha-Trehalose Dihydrate

USDA-ARS?s Scientific Manuscript database

Alpha,alpha-rehalose is of interest because of its cryoprotective and antidessicant properties, and because it possesses various technical anomalies such as 13C NMR spectra that give misleading indications of intramolecular structural symmetry. It is a non-reducing disaccharide, with the glycosidic...

One-pot synthesis of carbon-coated nanosized LiTi2(PO4)3 as anode materials for aqueous lithium ion batteries

NASA Astrophysics Data System (ADS)

Liu, Zhantao; Qin, Xusong; Xu, Hui; Chen, Guohua

2015-10-01

In this study, a one-pot sintering process incorporating sol-gel preparation route and in-situ carbon coating was proposed for the synthesis of carbon-coated nanosized LiTi2(PO4)3. Experimental results show that the prepared LiTi2(PO4)3 particles are of high crystallinity and well-coated by turbostratic carbon. Attributed to nanosized particles and enhanced conductivity provided by turbostratic carbon coating, the carbon-coated LiTi2(PO4)3 showed high rate performance and good cycling life in aqueous electrolyte. Particularly, the carbon-coated LiTi2(PO4)3 exhibited initial specific capacities of 103 and 89 mAh g-1, and retained 80.6% and 97% of the initial capacities after 120 cycles at 1C and 10C in aqueous electrolyte, respectively. The high rate performance and good cycling life of carbon-coated LiTi2(PO4)3 in aqueous electrolyte reveal its potential as negative electrode in aqueous lithium-ion batteries for electric vehicles and industrial-scale energy storage systems.

Stimulated Brillouin scattering of laser in semiconductor plasma embedded with nano-sized grains

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

Sharma, Giriraj, E-mail: grsharma@gmail.com; Dad, R. C.; Ghosh, S.

2015-07-31

A high power laser propagating through semiconductor plasma undergoes Stimulated Brillouin scattering (SBS) from the electrostrictively generated acoustic perturbations. We have considered that nano-sized grains (NSGs) ions are embedded in semiconductor plasma by means of ion implantation. The NSGs are bombarded by the surrounding plasma particles and collect electrons. By considering a negative charge on the NSGs, we present an analytically study on the effects of NSGs on threshold field for the onset of SBS and Brillouin gain of generated Brillouin scattered mode. It is found that as the charge on the NSGs builds up, the Brillouin gain is significantlymore » raised and the threshold pump field for the onset of SBS process is lowered.« less

Background canceling surface alpha detector

DOEpatents

MacArthur, D.W.; Allander, K.S.; Bounds, J.A.

1996-06-11

A background canceling long range alpha detector which is capable of providing output proportional to both the alpha radiation emitted from a surface and to radioactive gas emanating from the surface. The detector operates by using an electrical field between first and second signal planes, an enclosure and the surface or substance to be monitored for alpha radiation. The first and second signal planes are maintained at the same voltage with respect to the electrically conductive enclosure, reducing leakage currents. In the presence of alpha radiation and radioactive gas decay, the signal from the first signal plane is proportional to both the surface alpha radiation and to the airborne radioactive gas, while the signal from the second signal plane is proportional only to the airborne radioactive gas. The difference between these two signals is proportional to the surface alpha radiation alone. 5 figs.

Background canceling surface alpha detector

DOEpatents

MacArthur, Duncan W.; Allander, Krag S.; Bounds, John A.

1996-01-01

A background canceling long range alpha detector which is capable of providing output proportional to both the alpha radiation emitted from a surface and to radioactive gas emanating from the surface. The detector operates by using an electrical field between first and second signal planes, an enclosure and the surface or substance to be monitored for alpha radiation. The first and second signal planes are maintained at the same voltage with respect to the electrically conductive enclosure, reducing leakage currents. In the presence of alpha radiation and radioactive gas decay, the signal from the first signal plane is proportional to both the surface alpha radiation and to the airborne radioactive gas, while the signal from the second signal plane is proportional only to the airborne radioactive gas. The difference between these two signals is proportional to the surface alpha radiation alone.

Co-Binding of Pharmaceutical Compounds at Mineral Surfaces: Molecular Investigations of Dimer Formation at Goethite/Water Interfaces.

PubMed

Xu, Jing; Marsac, Rémi; Costa, Dominique; Cheng, Wei; Wu, Feng; Boily, Jean-François; Hanna, Khalil

2017-08-01

The emergence of antibiotic and anti-inflammatory agents in aquatic and terrestrial systems is becoming a serious threat to human and animal health worldwide. Because pharmaceutical compounds rarely exist individually in nature, interactions between various compounds can have unforeseen effects on their binding to mineral surfaces. This work demonstrates this important possibility for the case of two typical antibiotic and anti-inflammatory agents (nalidixic acid (NA) and niflumic acid (NFA)) bound at goethite (α-FeOOH) used as a model mineral surface. Our multidisciplinary study, which makes use of batch sorption experiments, vibration spectroscopy and periodic density functional theory calculations, reveals enhanced binding of the otherwise weakly bound NFA caused by unforeseen intermolecular interactions with mineral-bound NA. This enhancement is ascribed to the formation of a NFA-NA dimer whose energetically favored formation (-0.5 eV compared to free molecules) is predominantly driven by van der Waals interactions. A parallel set of efforts also showed that no cobinding occurred with sulfamethoxazole (SMX) because of the lack of molecular interactions with coexisting contaminants. As such, this article raises the importance of recognizing drug cobinding, and lack of cobinding, for predicting and developing policies on the fate of complex mixtures of antibiotics and anti-inflammatory agents in nature.

Imaging alpha particle detector

DOEpatents

Anderson, D.F.

1980-10-29

A method and apparatus for detecting and imaging alpha particles sources is described. A dielectric coated high voltage electrode and a tungsten wire grid constitute a diode configuration discharge generator for electrons dislodged from atoms or molecules located in between these electrodes when struck by alpha particles from a source to be quantitatively or qualitatively analyzed. A thin polyester film window allows the alpha particles to pass into the gas enclosure and the combination of the glass electrode, grid and window is light transparent such that the details of the source which is imaged with high resolution and sensitivity by the sparks produced can be observed visually as well. The source can be viewed directly, electronically counted or integrated over time using photographic methods. A significant increase in sensitivity over other alpha particle detectors is observed, and the device has very low sensitivity to gamma or beta emissions which might otherwise appear as noise on the alpha particle signal.

Imaging alpha particle detector

DOEpatents

Anderson, David F.

1985-01-01

A method and apparatus for detecting and imaging alpha particles sources is described. A conducting coated high voltage electrode (1) and a tungsten wire grid (2) constitute a diode configuration discharge generator for electrons dislodged from atoms or molecules located in between these electrodes when struck by alpha particles from a source (3) to be quantitatively or qualitatively analyzed. A thin polyester film window (4) allows the alpha particles to pass into the gas enclosure and the combination of the glass electrode, grid and window is light transparent such that the details of the source which is imaged with high resolution and sensitivity by the sparks produced can be observed visually as well. The source can be viewed directly, electronically counted or integrated over time using photographic methods. A significant increase in sensitivity over other alpha particle detectors is observed, and the device has very low sensitivity to gamma or beta emissions which might otherwise appear as noise on the alpha particle signal.

Characterization of Alpha-Toxin hla Gene Variants, Alpha-Toxin Expression Levels, and Levels of Antibody to Alpha-Toxin in Hemodialysis and Postsurgical Patients with Staphylococcus aureus Bacteremia

PubMed Central

Wu, Yuling; Tabor, David E.; Mok, Hoyin; Sellman, Bret R.; Jenkins, Amy; Yu, Li; Jafri, Hasan S.; Rude, Thomas H.; Ruffin, Felicia; Schell, Wiley A.; Park, Lawrence P.; Yan, Qin; Thaden, Joshua T.; Messina, Julia A.; Esser, Mark T.

2014-01-01

Alpha-toxin is a major Staphylococcus aureus virulence factor. This study evaluated potential relationships between in vitro alpha-toxin expression of S. aureus bloodstream isolates, anti-alpha-toxin antibody in serum of patients with S. aureus bacteremia (SAB), and clinical outcomes in 100 hemodialysis and 100 postsurgical SAB patients. Isolates underwent spa typing and hla sequencing. Serum anti-alpha-toxin IgG and neutralizing antibody levels were measured by using an enzyme-linked immunosorbent assay and a red blood cell (RBC)-based hemolysis neutralization assay. Neutralization of alpha-toxin by an anti-alpha-toxin monoclonal antibody (MAb MEDI4893) was tested in an RBC-based lysis assay. Most isolates encoded hla (197/200; 98.5%) and expressed alpha-toxin (173/200; 86.5%). In vitro alpha-toxin levels were inversely associated with survival (cure, 2.19 μg/ml, versus failure, 1.09 μg/ml; P < 0.01). Both neutralizing (hemodialysis, 1.26 IU/ml, versus postsurgical, 0.95; P < 0.05) and IgG (hemodialysis, 1.94 IU/ml, versus postsurgical, 1.27; P < 0.05) antibody levels were higher in the hemodialysis population. Antibody levels were also significantly higher in patients infected with alpha-toxin-expressing S. aureus isolates (P < 0.05). Levels of both neutralizing antibodies and IgG were similar among patients who were cured and those not cured (failures). Sequence analysis of hla revealed 12 distinct hla genotypes, and all genotypic variants were susceptible to a neutralizing monoclonal antibody in clinical development (MEDI4893). These data demonstrate that alpha-toxin is highly conserved in clinical S. aureus isolates. Higher in vitro alpha-toxin levels were associated with a positive clinical outcome. Although patients infected with alpha-toxin-producing S. aureus exhibited higher anti-alpha-toxin antibody levels, these levels were not associated with a better clinical outcome in this study. PMID:25392350

Adsorption Equilibrium and Kinetics at Goethite-Water and Related Interfaces

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

Katz, Lynn Ellen

This research study is an important component of a broader comprehensive project, “Geochemistry of Interfaces: From Surfaces to Interlayers to Clusters,” which sought to identify and evaluate the critical molecular phenomena at metal-oxide interfaces that control many geochemical and environmental processes. The primary goal of this research study was to better understand and predict adsorption of metal ions at mineral/water surfaces. Macroscopic data in traditional batch experiments was used to develop predictive models that characterize sorption in complex systems containing a wide range of background solution compositions. Our studies focused on systems involving alkaline earth metal (Mg 2+, Ca 2+,more » Sr 2+, Ba 2+) and heavy metal (Hg 2+, Co 2+, Cd 2+, Cu 2+, Zn 2+, Pb 2+) cations. The anions we selected for study included Cl -, NO 3 -, ClO 4 -, SO 4 2-, CO 3 2- and SeO 3 2- and the background electrolyte cations we examined included (Na +, K +, Rb + and Cs +) because these represent a range of ion sizes and have varying potentials for forming ion-pairs or ternary complexes with the metal ions studied. The research led to the development of a modified titration congruency approach for estimating site densities for mineral oxides such as goethite. The CD-MUSIC version of the surface complexation modeling approach was applied to potentiometric titration data and macroscopic adsorption data for single-solute heavy metals, oxyanions, alkaline earth metals and background electrolytes over a range of pH and ionic strength. The model was capable of predicting sorption in bi-solute systems containing multiple cations, cations and oxyanions, and transition metal cations and alkaline earth metal ions. Incorporation of ternary complexes was required for modeling Pb(II)-Se(IV) and Cd(II)-Se(IV) systems. -Both crystal face contributions and capacitance values were shown to be sensitive to varying specific surface area but were successfully accounted for in the

ON THE ORIGINS OF THE DIFFUSE H{alpha} EMISSION: IONIZED GAS OR DUST-SCATTERED H{alpha} HALOS?

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

Seon, Kwang-Il; Witt, Adolf N., E-mail: kiseon@kasi.re.kr

2012-10-20

It is known that the diffuse H{alpha} emission outside of bright H II regions not only are very extended, but also can occur in distinct patches or filaments far from H II regions, and the line ratios of [S II] {lambda}6716/H{alpha} and [N II] {lambda}6583/H{alpha} observed far from bright H II regions are generally higher than those in the H II regions. These observations have been regarded as evidence against the dust-scattering origin of the diffuse H{alpha} emission (including other optical lines), and the effect of dust scattering has been neglected in studies on the diffuse H{alpha} emission. In thismore » paper, we reexamine the arguments against dust scattering and find that the dust-scattering origin of the diffuse H{alpha} emission cannot be ruled out. As opposed to the previous contention, the expected dust-scattered H{alpha} halos surrounding H II regions are, in fact, in good agreement with the observed H{alpha} morphology. We calculate an extensive set of photoionization models by varying elemental abundances, ionizing stellar types, and clumpiness of the interstellar medium (ISM) and find that the observed line ratios of [S II]/H{alpha}, [N II]/H{alpha}, and He I {lambda}5876/H{alpha} in the diffuse ISM accord well with the dust-scattered halos around H II regions, which are photoionized by late O- and/or early B-type stars. We also demonstrate that the H{alpha} absorption feature in the underlying continuum from the dust-scattered starlight ({sup d}iffuse galactic light{sup )} and unresolved stars is able to substantially increase the [S II]/H{alpha} and [N II]/H{alpha} line ratios in the diffuse ISM.« less

{alpha}+{alpha} scattering reexamined in the context of the Sao Paulo potential

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

Chamon, L. C.; Gasques, L. R.; Carlson, B. V.

2011-03-15

We have analyzed a large set of {alpha}+{alpha} elastic scattering data for bombarding energies ranging from 0.6 to 29.5 MeV. Because of the complete lack of open reaction channels, the optical interaction at these energies must have a vanishing imaginary part. Thus, this system is particularly important because the corresponding elastic scattering cross sections are very sensitive to the real part of the interaction. The data were analyzed in the context of the velocity-dependent Sao Paulo potential, which is a successful theoretical model for the description of heavy-ion reactions from sub-barrier to intermediate energies. We have verified that, even inmore » this low-energy region, the velocity dependence of the model is quite important for describing the data of the {alpha}+{alpha} system.« less

Coordination polymer-derived nano-sized zinc ferrite with excellent performance in nitro-explosive detection.

PubMed

Singha, Debal Kanti; Mahata, Partha

2017-08-29

Herein, a mixed metal coordination polymer, {(H 2 pip)[Zn 1/3 Fe 2/3 (pydc-2,5) 2 (H 2 O)]·2H 2 O} 1 {where H 2 pip = piperazinediium and pydc-2,5 = pyridine-2,5-dicarboxylate}, was successfully synthesized using a hydrothermal technique. To confirm the structure and phase purity of 1, single crystals of an isomorphous pure Fe compound, {(H 2 pip)[Fe(pydc-2,5) 2 (H 2 O)]·2H 2 O} 1a, were synthesized based on similar synthetic conditions. Single crystal X-ray data of 1a confirmed the one-dimensional anionic metal-organic coordination polymer hydrogen bonded with protonated piprazine (piperazinediium) and lattice water molecules. The phase purity of 1 and 1a were confirmed via powder X-ray diffraction. Compound 1 was systematically characterized using IR, TGA, SEM, and EDX elemental mapping analysis. Compound 1 was used as a single source precursor for the preparation of nano-sized ZnFe 2 O 4 via thermal decomposition. The as-obtained ZnFe 2 O 4 was fully characterized using PXRD, SEM, TEM, and EDX elemental mapping analysis. It was found that ZnFe 2 O 4 was formed in its pure form with particle size in the nano-dimension. The aqueous dispersion of nano-sized ZnFe 2 O 4 exhibits a strong emission at 402 nm upon excitation at 310 nm. This emissive property was employed for luminescence-based detection of nitroaromatic explosives in an aqueous medium through luminescence quenching for the first time. Importantly, selective detections have been observed for phenolic nitroaromatics based on differential luminescence quenching behaviour along with a detection limit of 57 ppb for 2,4,6-trinitrophenol (TNP) in water.

Nanosized Drug Delivery Systems in Gastrointestinal Targeting: Interactions with Microbiota

PubMed Central

Karavolos, Michail; Holban, Alina

2016-01-01

The new age of nanotechnology has signaled a stream of entrepreneurial possibilities in various areas, form industry to medicine. Drug delivery has benefited the most by introducing nanostructured systems in the transport and controlled release of therapeutic molecules at targeted sites associated with a particular disease. As many nanosized particles reach the gastrointestinal tract by various means, their interactions with the molecular components of this highly active niche are intensively investigated. The well-characterized antimicrobial activities of numerous nanoparticles are currently being considered as a reliable and efficient alternative to the eminent world crisis in antimicrobial drug discovery. The interactions of nanosystems present in the gastrointestinal route with host microbiota is unavoidable; hence, a major research initiative is needed to explore the mechanisms and effects of these nanomaterials on microbiota and the impact that microbiota may have in the outcome of therapies entailing drug delivery nanosystems through the gastrointestinal route. These coordinated studies will provide novel techniques to replace or act synergistically with current technologies and help develop new treatments for major diseases via the discovery of unique antimicrobial molecules. PMID:27690060

Exceptional capability of nanosized CeO(2) materials to "dissolve" lanthanide oxides established by time-gated excitation and emission spectroscopy.

PubMed

Tiseanu, Carmen; Parvulescu, Vasile; Avram, Daniel; Cojocaru, Bogdan; Sanchez-Dominguez, Margarita

2014-05-28

The atomic scale homogeneity of Ce and Zr oxygen bonds represents the main reason for enhanced total oxygen storage capability of CeO2-ZrO2 (Ce/Zr = 1) as compared to that of CeO2. Here, we demonstrate that the addition of 10% Eu(3+) by wet impregnation on preformed nanosized CeO2-ZrO2 (Ce/Zr = 1) followed by calcination induces a remarkable homogeneity of 10% Eu(3+)-CeO2-ZrO2 solid solution. By use of time-resolved emission and excitation spectroscopies, the improvement of the nanoscale chemical and structural homogeneity of 10% Eu(3+)-CeO2-ZrO2 calcined at 1000 as compared to sample calcined at 750 °C is demonstrated. Based on the comparison of luminescence properties of 10% Eu(3+) impregnated on preformed nanosized CeO2-ZrO2 and CeO2, we also show that the presence of zirconium does not only preserve the ability of cerium oxide to "dissolve" lanthanide oxide, but also determines an important stabilization of defects (oxygen vacancies) generated upon Eu(3+) doping.

Importance of agonists in alpha-adrenoceptor classification and localisation of alpha1-adrenoceptors in human prostate.

PubMed

McGrath, J C; Naghadeh, M A; Pediani, J D; Mackenzie, J F; Daly, C J

1999-01-01

alpha-Adrenoceptor blocker drugs are commonly used in the clinical (non-surgical) treatment of BPH. alpha1-adrenoceptors were originally sub-divided using agonists but, subsequently, were sub-divided using only antagonists in ligand-ligand interactions, which did not require agonists at all. Ultimately, proof that adrenoceptors are functional receptors for the natural ligands, noradrenaline and adrenaline, requires that agonists be used. The earlier excitement engendered by finding varying agonist potency series in different tissues has not been revisited to place it in the context of current concepts of alpha1-adrenoceptor subtypes. This review will consider the advantages and limitations of different agonists for the study of alpha1-adrenoceptor subtypes including 'extreme' examples where the archetypal alpha1-adrenoceptor agonist phenylephrine activates alpha2-adrenoceptors and others where UK14304, often the alpha2-adrenoceptor agonist of choice, activates alpha1-adrenoceptors. New work will also be presented showing the interaction between agonists and the fluorescent alpha1-adrenoceptor antagonist QAPB. This introduces the novel point of view of studying the displacement of antagonists by agonists. Possible errors in antagonist classification arising from complexity in the actions of agonists and the recently developed method of fluorescent ligand binding on isolated living human prostatic smooth muscle cells will be discussed.

Growth of Nanosized Single Crystals for Efficient Perovskite Light-Emitting Diodes.

PubMed

Lee, Seungjin; Park, Jong Hyun; Nam, Yun Seok; Lee, Bo Ram; Zhao, Baodan; Di Nuzzo, Daniele; Jung, Eui Dae; Jeon, Hansol; Kim, Ju-Young; Jeong, Hu Young; Friend, Richard H; Song, Myoung Hoon

2018-04-24

Organic-inorganic hybrid perovskites are emerging as promising emitting materials due to their narrow full-width at half-maximum emissions, color tunability, and high photoluminescence quantum yields (PLQYs). However, the thermal generation of free charges at room temperature results in a low radiative recombination rate and an excitation-intensity-dependent PLQY, which is associated with the trap density. Here, we report perovskite films composed of uniform nanosized single crystals (average diameter = 31.7 nm) produced by introducing bulky amine ligands and performing the growth at a lower temperature. By effectively controlling the crystal growth, we maximized the radiative bimolecular recombination yield by reducing the trap density and spatially confining the charges. Finally, highly bright and efficient green emissive perovskite light-emitting diodes that do not suffer from electroluminescence blinking were achieved with a luminance of up to 55 400 cd m -2 , current efficiency of 55.2 cd A -1 , and external quantum efficiency of 12.1%.

In vitro toxicity test of nano-sized magnesium oxide synthesized via solid-phase transformation

NASA Astrophysics Data System (ADS)

Zheng, Jun; Zhou, Wei

2018-04-01

Nano-sized magnesium oxide (MgO) has been a promising potential material for biomedical pharmaceuticals. In the present investigation, MgO nanoparticles synthesized through in-situ solid-phase transformation based on the previous work (nano-Mg(OH)2 prepared by precipitation technique) using magnesium nitrate and sodium hydroxide. The phase structure and morphology of the MgO nanoparticles are characterized by X-ray powder diffraction (XRD), selected area electronic diffraction (SAED) and transmission electron microscopy (TEM) respectively. In vitro hemolysis tests are adopted to evaluate the toxicity of the synthesized nano-MgO. The results evident that nano-MgO with lower concentration is slightly hemolytic, and with concentration increasing nano-MgO exhibit dose-responsive hemolysis.

Nanosized Building Blocks for Customizing Novel Antibiofilm Approaches

PubMed Central

Paula, A.J.; Koo, H.

2016-01-01

Recent advances in nanotechnology provide unparalleled flexibility to control the composition, size, shape, surface chemistry, and functionality of materials. Currently available engineering approaches allow precise synthesis of nanocompounds (e.g., nanoparticles, nanostructures, nanocrystals) with both top-down and bottom-up design principles at the submicron level. In this context, these “nanoelements” (NEs) or “nanosized building blocks” can 1) generate new nanocomposites with antibiofilm properties or 2) be used to coat existing surfaces (e.g., teeth) and exogenously introduced surfaces (e.g., restorative or implant materials) for prevention of bacterial adhesion and biofilm formation. Furthermore, functionalized NEs 3) can be conceived as nanoparticles to carry and selectively release antimicrobial agents after attachment or within oral biofilms, resulting in their disruption. The latter mechanism includes “smart release” of agents when triggered by pathogenic microenvironments (e.g., acidic pH or low oxygen levels) for localized and controlled drug delivery to simultaneously kill bacteria and dismantle the biofilm matrix. Here we discuss inorganic, metallic, polymeric, and carbon-based NEs for their outstanding chemical flexibility, stability, and antibiofilm properties manifested when converted into bioactive materials, assembled on-site or delivered at biofilm-surface interfaces. Details are provided on the emerging concept of the rational design of NEs and recent technological breakthroughs for the development of a new generation of nanocoatings or functional nanoparticles for biofilm control in the oral cavity. PMID:27856967

Nanosized Building Blocks for Customizing Novel Antibiofilm Approaches.

PubMed

Paula, A J; Koo, H

2017-02-01

Recent advances in nanotechnology provide unparalleled flexibility to control the composition, size, shape, surface chemistry, and functionality of materials. Currently available engineering approaches allow precise synthesis of nanocompounds (e.g., nanoparticles, nanostructures, nanocrystals) with both top-down and bottom-up design principles at the submicron level. In this context, these "nanoelements" (NEs) or "nanosized building blocks" can 1) generate new nanocomposites with antibiofilm properties or 2) be used to coat existing surfaces (e.g., teeth) and exogenously introduced surfaces (e.g., restorative or implant materials) for prevention of bacterial adhesion and biofilm formation. Furthermore, functionalized NEs 3) can be conceived as nanoparticles to carry and selectively release antimicrobial agents after attachment or within oral biofilms, resulting in their disruption. The latter mechanism includes "smart release" of agents when triggered by pathogenic microenvironments (e.g., acidic pH or low oxygen levels) for localized and controlled drug delivery to simultaneously kill bacteria and dismantle the biofilm matrix. Here we discuss inorganic, metallic, polymeric, and carbon-based NEs for their outstanding chemical flexibility, stability, and antibiofilm properties manifested when converted into bioactive materials, assembled on-site or delivered at biofilm-surface interfaces. Details are provided on the emerging concept of the rational design of NEs and recent technological breakthroughs for the development of a new generation of nanocoatings or functional nanoparticles for biofilm control in the oral cavity.

Alpha-dispersion in human tissue

NASA Astrophysics Data System (ADS)

Grimnes, Sverre; Martinsen, Ørjan G.

2010-04-01

Beta dispersion is found in living tissue in the kilohertz - megahertz range and is caused by the cellular structure of biological materials with low frequency properties caused by cell membranes. Alpha dispersion is found in the hertz range and the causes are not so well known. Alpha dispersions are the first to disappear when tissue dies. Tissue data have often been based upon excised specimen from animals and are therefore not necessarily representative for human tissue alpha dispersions. Here we present data obtained with non-invasive skin surface electrodes for different segments of the living human body. We found alpha dispersions in all cases; the ankle-wrist results had the smallest. Large alpha dispersions were found where the distance between the electrodes and muscle masses was small, e.g. on the calf. Further studies on electrode technique and reciprocity, electrode positioning, statistical variations, gender, age and bodily constitutions are necessary in order to reveal more about the alpha dispersion, its appearance and disappearance.

Simultaneous measurements of the hydrogen airglow emissions of Lyman alpha, Lyman beta, and Balmer alpha.

NASA Technical Reports Server (NTRS)

Weller, C. S.; Meier, R. R.; Tinsley, B. A.

1971-01-01

Comparison of Lyman-alpha, 740- to 1050-A, and Balmer-alpha airglow measurements made at 134 deg solar-zenith angle on Oct. 13, 1969, with resonance-scattering models of solar radiation. Model comparison with Lyman-alpha data fixes the hydrogen column abundance over 215 km to 2 x 10 to the 13th per cu cm within a factor of 2. Differences between the Lyman-alpha model and data indicate a polar-equatorial departure from spherical symmetry in the hydrogen distribution. A Lyman-beta model based on the hydrogen distribution found to fit the Lyman-alpha data fits the spatial variation of the 740- to 1050-A data well from 100 to 130 km, but it does not fit the data well at higher altitudes; thus the presence of more rapidly absorbed shorter-wavelength radiation is indicated. This same resonance-scattering model yields Balmer-alpha intensities that result in good spatial agreement with the Balmer-alpha measurements, but a fivefold increase in the measured solar line center Lyman-beta flux is required (as required for the Lyman-beta measurement). The intensity ratio of Lyman-beta and Balmer-alpha at night is found to be a simple measure of the hydrogen optical depth if measurements with good accuracy can be made in the visible and ultraviolet spectrum.

21 CFR 882.1610 - Alpha monitor.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Alpha monitor. 882.1610 Section 882.1610 Food and... NEUROLOGICAL DEVICES Neurological Diagnostic Devices § 882.1610 Alpha monitor. (a) Identification. An alpha... electroencephalogram which is referred to as the alpha wave. (b) Classification. Class II (performance standards). ...

21 CFR 882.1610 - Alpha monitor.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Alpha monitor. 882.1610 Section 882.1610 Food and... NEUROLOGICAL DEVICES Neurological Diagnostic Devices § 882.1610 Alpha monitor. (a) Identification. An alpha... electroencephalogram which is referred to as the alpha wave. (b) Classification. Class II (performance standards). ...

21 CFR 882.1610 - Alpha monitor.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Alpha monitor. 882.1610 Section 882.1610 Food and... NEUROLOGICAL DEVICES Neurological Diagnostic Devices § 882.1610 Alpha monitor. (a) Identification. An alpha... electroencephalogram which is referred to as the alpha wave. (b) Classification. Class II (performance standards). ...

Spectral-optical-electrical-thermal properties of deposited thin films of nano-sized calcium(II)-8-hydroxy-5,7-dinitroquinolate complex.

PubMed

Farag, A A M; Haggag, Sawsan M S; Mahmoud, Mohamed E

2011-11-01

Spectral-optical-electrical-thermal properties of deposited thin films of nano-sized calcium(II)-8-hydroxy-5,7-dinitroquinolate complex, Ca[((NO(2))(2)-8HQ)(2)], were explored, studied and evaluated in this work. Thin films of Ca[((NO(2))(2)-8HQ)(2)] were assembled by using a direct, simple and efficient layer-by-layer (LBL) chemical deposition technique. The optical properties of thin films were investigated by using spectrophotometric measurements of transmittance and reflectance at normal incidence in the wavelength range 200-2500 nm. The refractive index, n, and the absorption index, k, of Ca[((NO(2))(2)-8HQ)(2)] films were determined from the measured transmittance and reflectance. The real and imaginary dielectric constants were also determined. The analysis of the spectral behavior of the absorption coefficient in the intrinsic absorption region reveals a direct allowed transition with band gaps of 1.1 eV and 2.4 eV for the optical and transport energy gaps, respectively. The current-voltage characteristics of Ca[((NO(2))(2)-8HQ)(2)] showed a trap-charge limited conduction in determining the current at the intermediate and high bias regimes. Graphical representation of the current-voltage characteristics yields three distinct linear parts indicating the existence of three conduction mechanisms. Structural characterization and identification were confirmed by using Fourier transform infrared spectroscopy (FT-IR). Scanning electron microscopy (SEM) was also used to image the surface morphology of the deposited nano-sized metal complex and such study revealed a high homogeneity in surface spherical particle distribution with average particles size in the range 20-40 nm. Thermal gravimetric analysis (TGA) was also studied for [(NO(2))(2)-8HQ] and Ca[((NO(2))(2)-8HQ)(2)] to evaluate and confirm the thermal stability characteristics incorporated into the synthesized nano-sized Ca[((NO(2))(2)-8HQ)(2)] complex. Copyright © 2011 Elsevier B.V. All rights reserved.

Contribution of HIF-1alpha or HIF-2alpha to erythropoietin expression: in vivo evidence based on chromatin immunoprecipitation.

PubMed

Yeo, Eun-Jin; Cho, Young-Suk; Kim, Myung-Suk; Park, Jong-Wan

2008-01-01

Circulating erythropoietin (EPO) is mainly produced by the kidneys and mediates erythrogenesis in bone marrow and nonhematopoietic cell survival. EPO is also produced in other tissues where it functions as a paracrine. Moreover, the hypoxic induction of EPO is known to be mediated by HIF-1alpha and HIF-2alpha, but it remains obscure as to which of these two mediators mainly contributes to EPO expression. Thus, we designed in vivo experiments to evaluate the contributions made by HIF-1alpha and HIF-2alpha to EPO expression. In mice exposed to mild whole body hypoxia, HIF-1alpha and HIF-2alpha were both induced in all tissues examined. However, EPO mRNA was expressed in kidney and brain, but not in liver and lung. Likewise, chromatin immunoprecipitation (CHIP) analyses demonstrated that HIF-1alpha or HIF-2alpha binding to the EPO gene increased under hypoxic conditions only in kidney and brain. A comparison of CHIP data and EPO mRNA levels suggested that, during mild hypoxia, renal EPO transcription is induced equally by HIF-1alpha and HIF-2alpha, but that brain EPO is mainly induced during hypoxia by HIF-2alpha. Thus, HIF-1alpha and HIF-2alpha appear to contribute to EPO expression tissue specifically.

Binding of actin to lens alpha crystallins

NASA Technical Reports Server (NTRS)

Gopalakrishnan, S.; Takemoto, L.; Spooner, B. S. (Principal Investigator)

1992-01-01

Actin has been coupled to a cyanogen bromide-activated Sepharose 4B column, then tested for binding to alpha, beta, and gamma crystallin preparations from the bovine lens. Alpha, but not beta or gamma, crystallins bound to the actin affinity column in a time dependent and saturable manner. Subfractionation of the alpha crystallin preparation into the alpha-A and alpha-B species, followed by incubation with the affinity column, demonstrated that both species bound approximately the same. Together, these studies demonstrate a specific and saturable binding of lens alpha-A and alpha-B with actin.

Mind Your p's and Alphas.

ERIC Educational Resources Information Center

Stallings, William M.

1985-01-01

In the educational research literature, alpha and p are often conflated. Paradoxically, alpha retains a prominent place in textbook discussions, but it is often supplanted by p in the results sections of journal articles. Because alpha and p have unique uses, researchers should continue to employ both conventions in summarizing the outcomes of…

Determination of the volume activity concentration of alpha artificial radionuclides with alpha spectrometer.

PubMed

Liu, B; Zhang, Q; Li, Y

1997-12-01

This paper introduces a method to determine the volume activity concentration of alpha and/or beta artificial radionuclides in the environment and radon/thoron progeny background-compensation based on a Si surface-barrier detector. By measuring the alpha peak counts of 218Po and 214Po in two time intervals, the activity concentration of 218Po, 214Pb and 214Bi aerosol particles were determined; meanwhile, the total beta count of 214Pb and 214Bi aerosols was also calculated from their decay scheme. With the average equilibrium factor of thoron progeny in general environment, the alpha and beta counts of thoron progeny were approximately evaluated by 212Po alpha peak counts. The alpha count of transuranic aerosols was determined by subtracting the trail counts of radon/thoron progeny alpha peaks. The total count of beta artificial radionuclides was determined by subtracting the beta counts of radon/thoron progeny aerosol particles. In our preliminary experiments, if the radon progeny concentration is less than 15 Bq m(-3), the lower limit of detection of transuranics concentration is less than 0.1 Bq m(-3). Even if the radon progeny concentration is as high as 75 Bq m(-3), the lower limit of detection of total beta activity concentration of artificial nuclides aerosols is less than 1 Bq m(-3).

The region of CQQQKPQRRP of PGC-1{alpha} interacts with the DNA-binding complex of FXR/RXR{alpha}

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

Kanaya, Eiko; Jingami, Hisato

2006-04-14

PGC-1{alpha} co-activates transcription by several nuclear receptors. To study the interaction among PGC-1{alpha}, RXR{alpha}/FXR, and DNA, we performed electrophoresis mobility shift assays. The RXR{alpha}/FXR proteins specifically bound to DNA containing the IR-1 sequence in the absence of ligand. When the fusion protein of GST-PGC-1{alpha} was added to the mixture of RXR{alpha}/FXR/DNA, the ligand-influenced retardation of the mobility was observed. The ligand for RXR{alpha} (9-cis-retinoic acid) was necessary for this retardation, whereas, the ligand for FXR, chenodeoxycholic acid, barely had an effect. The results obtained using truncated PGC-1{alpha} proteins suggested that two regions are necessary for PGC-1{alpha} to interact with themore » DNA-binding complex of RXR{alpha}/FXR. One is the region of the second leucine-rich motif, and the other is that of the amino acid sequence CQQQKPQRRP, present between the second and third leucine-rich motifs. The results obtained with the SPQSS mutation for KPQRR suggested that the basic amino acids are important for the interaction.« less

Geochemical and mineralogical composition of bog iron ore as a resource for prehistoric iron production - A case study of the Widawa catchment area in Eastern Silesia, Poland

NASA Astrophysics Data System (ADS)

Thelemann, Michael; Bebermeier, Wiebke; Hoelzmann, Philipp

2016-04-01

Spreading from the Near East in the declining Bronze Age from the 2nd millennium BCE onwards, the technique of iron smelting reached Eastern Silesia, Poland, in approximately the 2nd century BCE (pre-Roman Iron Age). At this time the region of the Widawa catchment area was inhabited by the Przeworsk culture. While the older moraine landscape of the study area lacks ores from geological rock formations, bog iron ores were relatively widespread and, due to their comparatively easy accessibility, were commonly exploited for early iron production. In this poster the mineralogical and elemental composition of local bog iron ore deposits and iron slag finds, as a by-product of the smelting process, are investigated. The crystalline mineralogical composition of local bog iron ores is dominated by quartz (SiO2) and goethite (α FeO(OH)), in contrast to slag samples in which fayalite (Fe2SiO4), wüstite (FeO) and quartz, with traces of goethite, represent the main minerals. Ores and slags are both characterized by notable hematite (Fe2O3), magnetite (Fe3O4) and maghemite (γ-Fe2O3) contents. Analyzed bog iron ore samples show iron contents of up to 64.9 mass% Fe2O3 (45.4 mass% Fe), whereas the iron contents of bloomery slags vary between 48.7 and 72.0 mass% FeO (37.9 and 56.0 mass% Fe). A principal component analysis of the element contents, which were quantified by portable energy-dispersive X-ray fluorescence spectrometry (p-ED-XRF), indicates local variations in the elemental composition. Our results show that bog iron ores are relatively widely distributed with spatially varying iron contents along the Widawa floodplain but present-day formation conditions (e.g. different ground-water levels) are negatively affected by modern land-use practices, such as agriculture and melioration measures.

Application of four anti-human interferon-alpha monoclonal antibodies for immunoassay and comparative analysis of natural interferon-alpha mixtures

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

Andersson, G.; Lundgren, E.; Ekre, H.P.

Four different mouse monoclonal antibodies to human interferon-alpha (IFN-alpha) were evaluated for application in quantitative and comparative analysis of natural IFN-alpha mixtures. Binding to IFN-alpha subtypes in solution revealed individual reactivity patterns. These patterns changed if the IFN-alpha molecules were immobilized either passively to a surface or bound by another antibody. Also, substitution of a single amino acid in IFN-alpha 2 affected the binding, apparently by altering the conformation. Isoelectric focusing of three natural IFN-alpha preparations from different sources, followed by immunoblotting, resulted in individual patterns with each of the four mAbs and also demonstrated variation in the composition ofmore » the IFN-alpha preparations. None of the mAbs was subtype specific, but by combining the different mAbs, and also applying polyclonal anti-human IFN-alpha antibodies, it was possible to design sensitive sandwich ELISAs with broad or more limited IFN-alpha subtype specificity.« less

Demonstration of 3 alpha(17 beta)-hydroxysteroid dehydrogenase distinct from 3 alpha-hydroxysteroid dehydrogenase in hamster liver.

PubMed Central

Ohmura, M; Hara, A; Nakagawa, M; Sawada, H

1990-01-01

NAD(+)-linked and NADP(+)-linked 3 alpha-hydroxysteroid dehydrogenases were purified to homogeneity from hamster liver cytosol. The two monomeric enzymes, although having similar molecular masses of 38,000, differed from each other in pI values, activation energy and heat stability. The two proteins also gave different fragmentation patterns by gel electrophoresis after digestion with protease. The NADP(+)-linked enzyme catalysed the oxidoreduction of various 3 alpha-hydroxysteroids, whereas the NAD(+)-linked enzyme oxidized the 3 alpha-hydroxy group of pregnanes and some bile acids, and the 17 beta-hydroxy group of testosterone and androstanes. The thermal stabilities of the 3 alpha- and 17 beta-hydroxysteroid dehydrogenase activities of the NAD(+)-linked enzyme were identical, and the two enzyme activities were inhibited by mixing 17 beta- and 3 alpha-hydroxysteroid substrates, respectively. Medroxyprogesterone acetate, hexoestrol and 3 beta-hydroxysteroids competitively inhibited 3 alpha- and 17 beta-hydroxysteroid dehydrogenase activities of the enzyme. These results show that hamster liver contains a 3 alpha(17 beta)-hydroxysteroid dehydrogenase structurally and functionally distinct from 3 alpha-hydroxysteroid dehydrogenase. Images Fig. 1. Fig. 2. PMID:2317205

Alpha channeling in a rotating plasma.

PubMed

Fetterman, Abraham J; Fisch, Nathaniel J

2008-11-14

The wave-particle alpha-channeling effect is generalized to include rotating plasma. Specifically, radio frequency waves can resonate with alpha particles in a mirror machine with ExB rotation to diffuse the alpha particles along constrained paths in phase space. Of major interest is that the alpha-particle energy, in addition to amplifying the rf waves, can directly enhance the rotation energy which in turn provides additional plasma confinement in centrifugal fusion reactors. An ancillary benefit is the rapid removal of alpha particles, which increases the fusion reactivity.

Structure and organization of nanosized-inclusion-containing bilayer membranes

NASA Astrophysics Data System (ADS)

Ren, Chun-Lai; Ma, Yu-Qiang

2009-07-01

Based on a considerable amount of experimental evidence for lateral organization of lipid membranes which share astonishingly similar features in the presence of different inclusions, we use a hybrid self-consistent field theory (SCFT)/density-functional theory (DFT) approach to deal with bilayer membranes embedded by nanosized inclusions and explain experimental findings. Here, the hydrophobic inclusions are simple models of hydrophobic drugs or other nanoparticles for biomedical applications. It is found that lipid/inclusion-rich domains are formed at moderate inclusion concentrations and disappear with the increase in the concentration of inclusions. At high inclusion content, chaining of inclusions occurs due to the effective depletion attraction between inclusions mediated by lipids. Meanwhile, the increase in the concentration of inclusions can also cause thickening of the membrane and the distribution of inclusions undergoes a layering transition from one-layer structure located in the bilayer midplane to two-layer structure arranged into the two leaflets of a bilayer. Our theoretical predictions address the complex interactions between membranes and inclusions suggesting a unifying mechanism which reflects the competition between the conformational entropy of lipids favoring the formation of lipid- and inclusion-rich domains in lipids and the steric repulsion of inclusions leading to the uniform dispersion.

{sup 110,116}Cd({alpha},{alpha}){sup 110,116}Cd elastic scattering and systematic investigation of elastic {alpha} scattering cross sections along the Z=48 isotopic and N=62 isotonic chains

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

Kiss, G. G.; Fueloep, Zs.; Gyuerky, Gy.

2011-06-15

The elastic scattering cross sections for the reactions {sup 110,116}Cd({alpha},{alpha}){sup 110,116}Cd at energies above and below the Coulomb barrier are presented to provide a sensitive test for the {alpha}-nucleus optical potential parameter sets. Additional constraints for the optical potential are taken from the analysis of elastic scattering excitation functions at backward angles which are available in literature. Moreover, the variation of the elastic {alpha} scattering cross sections along the Z=48 isotopic and N=62 isotonic chain is investigated by the study of the ratios of the {sup 106,110,116}Cd({alpha},{alpha}){sup 106,110,116}Cd scattering cross sections at E{sub cm{approx_equal}}15.6and18.8 MeV and the ratio of themore » {sup 110}Cd({alpha},{alpha}){sup 110}Cd and {sup 112}Sn({alpha},{alpha}){sup 112}Sn reaction cross sections at E{sub cm{approx_equal}}18.8 MeV, respectively. These ratios are sensitive probes for the {alpha}-nucleus optical potential parametrizations. The potentials under study are a basic prerequisite for the prediction of {alpha}-induced reaction cross sections (e.g., for the calculation of stellar reaction rates in the astrophysical p or {gamma} process).« less

Strengthening Effect of Extruded Mg-8Sn-2Zn-2Al Alloy: Influence of Micro and Nano-Size Mg₂Sn Precipitates.

PubMed

Cheng, Weili; Bai, Yang; Wang, Lifei; Wang, Hongxia; Bian, Liping; Yu, Hui

2017-07-18

In this study, Mg-8Sn-2Zn-2Al (TZA822) alloys with varying Mg₂Sn contents prior to extrusion were obtained by different pre-treatments (without and with T4), and the strengthening response related to micro and nano-size Mg₂Sn precipitates in the extruded TZA822 alloys was reported. The results showed that the morphology of nano-size Mg₂Sn precipitates exhibits a significant change in basal plane from rod-like to spherical, owing to the decrement in the fraction of micro-size particles before extrusion. Meanwhile, the spherical Mg₂Sn precipitates provided a much stronger strengthening effect than did the rod-like ones, which was ascribed to uniform dispersion and refinement of spherical precipitates to effectively hinder basal dislocation slip. As a consequence, the extruded TZA822 alloy with T4 showed a higher tensile yield strength (TYS) of 245 MPa, ultimate tensile strength (UTS) of 320 MPa and elongation (EL) of 26.5%, as well as a lower degree of yield asymmetry than their counterpart without T4. Detailed reasons for the strengthening effect were given and analyzed.

Alpha Thalassemia (For Parents)

MedlinePlus

... Safe Videos for Educators Search English Español Alpha Thalassemia KidsHealth / For Parents / Alpha Thalassemia What's in this ... Symptoms Diagnosis Treatment Print en español Alfa talasemia Thalassemias Thalassemias are a group of blood disorders that ...

Combinations of ERK and p38 MAPK inhibitors ablate tumor necrosis factor-alpha (TNF-alpha ) mRNA induction. Evidence for selective destabilization of TNF-alpha transcripts.

PubMed

Rutault, K; Hazzalin, C A; Mahadevan, L C

2001-03-02

Tumor necrosis factor-alpha (TNF-alpha) is a potent proinflammatory cytokine whose synthesis and secretion are implicated in diverse pathologies. Hence, inhibition of TNF-alpha transcription or translation and neutralization of its protein product represent major pharmaceutical strategies to control inflammation. We have studied the role of ERK and p38 mitogen-activated protein (MAP) kinase in controlling TNF-alpha mRNA levels in differentiated THP-1 cells and in freshly purified human monocytes. We show here that it is possible to produce virtually complete inhibition of lipopolysaccharide-stimulated TNF-alpha mRNA accumulation by using a combination of ERK and p38 MAP kinase inhibitors. Furthermore, substantial inhibition is achievable using combinations of 1 microm of each inhibitor, whereas inhibitors used individually are incapable of producing complete inhibition even at high concentrations. Finally, addressing mechanisms involved, we show that inhibition of p38 MAP kinase selectively destabilizes TNF-alpha transcripts but does not affect degradation of c-jun transcripts. These results impinge on the controversy in the literature surrounding the mode of action of MAP kinase inhibitors on TNF-alpha mRNA and suggest the use of combinations of MAP kinase inhibitors as an effective anti-inflammatory strategy.

Tumor necrosis factor-alpha-independent downregulation of hepatic cholesterol 7alpha-hydroxylase gene in mice treated with lead nitrate.

PubMed

Kojima, Misaki; Sekikawa, Kenji; Nemoto, Kiyomitsu; Degawa, Masakuni

2005-10-01

We previously reported that lead nitrate (LN), an inducer of hepatic tumor necrosis factor-alpha (TNF-alpha), downregulated gene expression of cholesterol 7alpha-hydroxylase. Herein, to clarify the role of TNF-alpha in LN-induced downregulation of cholesterol 7alpha-hydroxylase, effects of LN on gene expression of hepatic cholesterol 7alpha-hydroxylase (Cyp7a1) in TNF-alpha-knockout (KO) and TNF-alpha-wild-type (WT) mice were comparatively examined. Gene expression of hepatic Cyp7a1 in both WT and KO mice decreased to less than 5% of the corresponding controls at 6-12 h after treatment with LN (100 mumol/kg body weight, iv). Levels of hepatic TNF-alpha protein in either WT or KO mice were below the detection limit, although expression levels of the TNF-alpha gene markedly increased at 6 h in WT mice by LN treatment, but not in KO mice. In contrast, in both WT and KO mice, levels of hepatic IL-1beta protein, which is known to be a suppressor of the cholesterol 7alpha-hydroxylase gene in hamsters, were significantly increased 3-6 h after LN treatment. Furthermore, LN-induced downregulation of the Cyp7a1 gene did not necessarily result from altered gene expression of hepatic transcription factors, including positive regulators (liver X receptor alpha, retinoid X receptor alpha, fetoprotein transcription factor, and hepatocyte nuclear factor 4alpha) and a negative regulator small heterodimer partner responsible for expression of the Cyp7a1 gene. The present findings indicated that LN-induced downregulation of the Cyp7a1 gene in mice did not necessarily occur through a TNF-alpha-dependent pathway and might occur mainly through an IL-1beta-dependent pathway.

Reverse-phase HPLC analysis of human alpha crystallin.

PubMed

Swamy, M S; Abraham, E C

1991-03-01

A rapid and highly sensitive reverse-phase HPLC (RP-HPLC) method was used to separate crystallin subunits from human alpha crystallin. Three distinct peaks were separated; by electrophoretic and immunological analyses the first and second peaks were identified as alpha B and alpha A respectively. On the other hand, peak 3 appeared to be a modified form of alpha crystallin. The ratio of alpha A and alpha B proteins was 3:1 in 1 day old lenses which gradually changed to 2:1 in 17 year old lenses and to 1:1 in the 50 and 82 year old whole lenses and 82 year old lens cortex, with a concomitant increase in the modified alpha, suggesting that alpha A subunits are relatively more involved in aggregation. Analysis of the 82 year old lens nucleus also supported this conclusion. The RP-HPLC analysis of the HMW aggregate fraction showed substantial enrichment of the modified alpha. The alpha A and alpha B subunits independently reassociated to form polymeric alpha crystallin whereas the modified alpha reassociated to form HMW aggregates as shown by molecular sieve HPLC. Hence it appears that the HMW aggregate peak was constituted by modified alpha crystallin. Only in the peak 3 material the 280 nm absorbance was about 2-fold higher than what was expected from the actual protein content. The data suggest that the changes induced by post-translational modifications may have some role in the formation of modified alpha. The present RP-HPLC method is useful in separating these modified alpha from the unmodified alpha A and alpha B subunits.

Resolution of G(s)alpha and G(q)alpha/G(11)alpha proteins in membrane domains by two-dimensional electrophoresis: the effect of long-term agonist stimulation.

PubMed

Matousek, P; Novotný, J; Svoboda, P

2004-01-01

Low-density membrane-domain fractions were prepared from S49 lymphoma cells and clone e2m11 of HEK293 cells expressing a large number of thyrotropin-releasing hormone receptor (TRH-R) and G(11)alpha by flotation on sucrose density gradients. The intact cell structure was broken by detergent-extraction, alkaline-treatment or drastic homogenization. Three types of low-density membranes were resolved by two-dimensional electrophoresis and analyzed for G(s)alpha (S49) or G(q)alpha/G11) (e2m11) content. Four individual immunoblot signals of Gsalpha protein were identified in S49 lymphoma cells indicating complete resolution of the long G(s)alpha L+/-ser and short G(s)alpha S+/-ser variants of G(s)alpha. All these were diminished by prolonged agonist (isoprenaline) stimulation. In e2m11-HEK cells, five different immunoblot signals were detected indicating post-translational modification of G proteins of G(q)alpha/G(11)alpha family. The two major spots corresponding to exogenously (over)expressed G(11)alpha and endogenous G(q)alpha were reduced; the minor spots diminished by hormonal stimulation. Parallel analysis by silver staining of the total protein content indicated that no major changes in protein composition occurred under these conditions. Our data thus indicate that agonist-stimulation of target cells results in down-regulation of all different members of G(s) and G(q)/G(11) families. This agonist-specific effect may be demonstrated in crude membrane as well as domain/raft preparations and it is not accompanied by changes in overall protein composition.

Conformational restriction through C alpha i <--> C alpha i cyclization: Ac12c, the largest cycloaliphatic C alpha,alpha- disubstituted glycine known.

PubMed

Saviano, M; Iacovino, R; Menchise, V; Benedetti, E; Bonora, G M; Gatos, M; Graci, L; Formaggio, F; Crisma, M; Toniolo, C

2000-02-01

Two complete series of N-protected, monodispersed oligopeptide esters to the pentamer level from 1-aminocyclododecane-1-carboxylic acid (Ac(12)c), an alpha-amino acid conformationally constrained through C(alpha)(i) <--> C(alpha)(i) cyclization, and either L-Ala or Aib residues, along with the N-protected Ac(12)c homopeptide alkylamide series from monomer to trimer, have been synthesized by solution methods and fully characterized. The solution-preferred conformations of these peptides have been assessed by Fourier transform ir absorption and (1)H-nmr techniques. Moreover, the molecular structures of one derivative (Z-Ac(12)c-OH) and three peptides [the tripeptide ester Z-L-Ala-Ac(12)c-L-Ala-OMe, the tripeptide alkylamide Z-(Ac(12)c)(3)-NHiPr, and the tetrapeptide ester Z-(Aib)(2)-Ac(12)c-Aib-OtBu (Aib, alpha-aminoisobutyric acid)] have been determined in the crystal state by x-ray diffraction. The results obtained point to the conclusion that beta-bends and 3(10)-helices are preferentially adopted by peptides based on Ac(12)c, the largest cycloaliphatic C-disubstituted glycine known. A comparison with the structural tendencies extracted from published works on peptides from Aib, the prototype of C-disubstituted glycines, and the other extensively studied members of the class of 1-aminocycloalkane-1-carboxylic acids (Ac(n) c, with n = 3-9), is made and the implications for the use of the Ac(12)c residue in the Ac(n) c scan approach of conformationally restricted analogues of bioactive peptides are briefly discussed. Copyright 2000 John Wiley & Sons, Inc.

Optical filter based on Fabry-Perot structure using a suspension of goethite nanoparticles as electro-optic material

NASA Astrophysics Data System (ADS)

Abbas, Samir; Dupont, Laurent; Dozov, Ivan; Davidson, Patrick; Chanéac, Corinne

2018-02-01

We have investigated the feasibility of optical tunable filters based on a Fabry-Perot etalon that uses a suspension of goethite (α-FeOOH) nanorods as electro-optic material for application in optical telecommunications in the near IR range. These synthetic nanoparticles have a high optical anisotropy that give rise to a very strong Kerr effect in their colloidal suspensions. Currently, these particles are dispersed in aqueous solvent, with pH2 to ensure the colloidal electrostatic stability. However, the high conductivity of these suspensions requires using high-frequency electric fields (f > 1 MHz), which brings about a high power consumption of the driver. To decrease the field frequency, we have changed the solvent to ethylene glycol which has a lower electrical conductivity than the aqueous solvent. We have built a Fabry-Perot cell, filled with this colloidal suspension in the isotropic phase, and showed that a phase shift of 14 nm can be obtained in a field of 3V/μm. Therefore, the device can operate as a tunable filter. A key advantage of this filter is that it is, by principle, completely insensitive to the polarization of the input light. However, several technological issues still need to be solved, such as ionic contamination of the suspension from the blocking layers, and dielectrophoretic and thermal effects.

Identification of hydrogen peroxide oxidation sites of alpha A- and alpha B-crystallins.

PubMed

Smith, J B; Jiang, X; Abraham, E C

1997-02-01

The alpha-crystallins are the most abundant structural proteins of the lens and, because of their chaperone activity, contribute to the solubility of the other crystallins. With aging, the lens crystallins undergo a variety of modifications which correlate with a loss of solubility and the development of cataract. A recent study demonstrating that alpha-crystallins exposed in vitro to FeCl3 and H2O2 exhibit decreased chaperone activity, implicates metal catalyzed oxidations of alpha-crystallins in this loss of solubility. The present study has determined that alpha-crystallins incubated with FeCl3 and H2O2 are modified by the nearly complete oxidation of all methionine residues to methionine sulfoxide, with no other detectable reaction products. The modifications were identified from the molecular weights of peptides formed by enzymatic digestion of the alpha-crystallins and located by tandem mass spectrometric analysis of the fragmentation pattern of the mass spectra of the fragments from peptides with oxidized methionine is loss of 64 Da, which corresponds to loss of CH3SOH from the methionine sulfoxide. These fragments are useful in identifying peptides that include oxidized methionine residues.

Alpha-particle emission probabilities of ²³⁶U obtained by alpha spectrometry.

PubMed

Marouli, M; Pommé, S; Jobbágy, V; Van Ammel, R; Paepen, J; Stroh, H; Benedik, L

2014-05-01

High-resolution alpha-particle spectrometry was performed with an ion-implanted silicon detector in vacuum on a homogeneously electrodeposited (236)U source. The source was measured at different solid angles subtended by the detector, varying between 0.8% and 2.4% of 4π sr, to assess the influence of coincidental detection of alpha-particles and conversion electrons on the measured alpha-particle emission probabilities. Additional measurements were performed using a bending magnet to eliminate conversion electrons, the results of which coincide with normal measurements extrapolated to an infinitely small solid angle. The measured alpha emission probabilities for the three main peaks - 74.20 (5)%, 25.68 (5)% and 0.123 (5)%, respectively - are consistent with literature data, but their precision has been improved by at least one order of magnitude in this work. © 2013 Published by Elsevier Ltd.

15 beta-hydroxysteroids (Part IV). Steroids of the human perinatal period: the synthesis of 3 alpha,15 beta,17 alpha-trihydroxy-5 alpha-pregnan-20-one and its A/B-ring configurational isomers.

PubMed

Reeder, A Y; Joannou, G E

1995-12-01

In recent years several 15 beta-hydroxysteroids have emerged pathognomonic of adrenal disorders in human neonates of which 3 alpha,15 beta,17 alpha-trihydroxy-5 beta-pregnan-20-one (2) was the first to be identified in the urine of newborn infants affected with congenital adrenal hyperplasia. In this investigation we report the synthesis of the three remaining 3 xi,5 xi-isomers, namely 3 alpha,15 beta,17 alpha-trihydroxy-5 alpha-pregnan-20-one (3), 3 beta,15 beta,17 alpha-trihydroxy-5 alpha-pregnan-20-one (7) and 3 beta,15 beta,17 alpha-trihydroxy-5 beta-pregnan-20-one (8) for their definitive identification in pathological conditions in human neonates. 3 beta,15 beta-Diacetoxy-17 alpha-hydroxy-5-pregnen-20-one (11), a product of chemical synthesis was converted to the isomeric 3 and 7, while conversion of 15 beta,17 alpha-dihydroxy-4-pregnen-3,20-dione (4), a product of microbiological transformation, resulted in the preparation of 8. In brief, selective acetate hydrolysis of 11 gave 15 beta-acetoxy-3 beta,17 alpha-dihydroxy-5-pregnen-20-one (12) which on catalytic hydrogenation gave 15 beta-acetoxy-3 beta,17 alpha-dihydroxy-5 alpha-pregnan-20-one (13) a common intermediate for the synthesis of the 3 beta(and alpha),5 alpha-isomers. Hydrolysis of the 15 beta-acetate gave 7, whereas oxidation with pyridinium chlorochromate gave 15 beta-acetoxy-17 alpha-hydroxy-5 alpha-pregnan-3,20-dione (14) which on reduction with L-Selectride and hydrolysis of the 15 beta-acetate gave 3. Finally, hydrogenation of 4 gave 15 beta, 17 alpha-dihydroxy-5 beta-pregnan-3,20-dione (10) which on reduction with L-Selectride gave 8.

Turning Waste into Value: Nanosized Natural Plant Materials of Solanum incanum L. and Pterocarpus erinaceus Poir with Promising Antimicrobial Activities

PubMed Central

Griffin, Sharoon; Tittikpina, Nassifatou Koko; Al-marby, Adel; Alkhayer, Reem; Denezhkin, Polina; Witek, Karolina; Gbogbo, Koffi Apeti; Batawila, Komlan; Duval, Raphaël Emmanuel; Nasim, Muhammad Jawad; Awadh-Ali, Nasser A.; Kirsch, Gilbert; Chaimbault, Patrick; Schäfer, Karl-Herbert; Keck, Cornelia M.; Handzlik, Jadwiga; Jacob, Claus

2016-01-01

Numerous plants are known to exhibit considerable biological activities in the fields of medicine and agriculture, yet access to their active ingredients is often complicated, cumbersome and expensive. As a consequence, many plants harbouring potential drugs or green phyto-protectants go largely unnoticed, especially in poorer countries which, at the same time, are in desperate need of antimicrobial agents. As in the case of plants such as the Jericho tomato, Solanum incanum, and the common African tree Pterocarpus erinaceus, nanosizing of original plant materials may provide an interesting alternative to extensive extraction and isolation procedures. Indeed, it is straightforward to obtain considerable amounts of such common, often weed-like plants, and to mill the dried material to more or less uniform particles of microscopic and nanoscopic size. These particles exhibit activity against Steinernema feltiae or Escherichia coli, which is comparable to the ones seen for processed extracts of the same, respective plants. As S. feltiae is used as a model nematode indicative of possible phyto-protective uses in the agricultural arena, these findings also showcase the potential of nanosizing of crude “waste” plant materials for specific practical applications, especially—but not exclusively—in developing countries lacking a more sophisticated industrial infrastructure. PMID:27104554

Genomic structure of rat 3alpha-hydroxysteroid/dihydrodiol dehydrogenase (3alpha-HSD/DD, AKR1C9).

PubMed

Lin, H K; Hung, C F; Moore, M; Penning, T M

1999-11-01

Rat liver 3alpha-hydroxysteroid/dihydrodiol dehydrogenase (3alpha-HSD/DD) is a member of the aldo-keto reductase (AKR) superfamily. It is involved in the inactivation of steroid hormones and the metabolic activation of polycyclic aromatic hydrocarbons (PAH) by converting trans-dihydrodiols into reactive and redox-active o-quinones. The structure of the 5'-flanking region of the gene and factors involved in the constitutive and regulated expression of this gene have been reported [H.-K. Lin, T.M. Penning, Cloning, sequencing, and functional analysis of the 5'-flanking region of the rat 3alpha-hydroxysteroid/dihydrodiol dehydrogenase gene, Cancer Res. 55 (1995) 4105-4113]. We now describe the complete genomic structure of the rat type 1 3alpha-HSD/DD gene. Charon 4A and P1 genomic clones contained at least three rat genes (type 1, type 2 and type 3 3alpha-HSD/DD) each of which encoded for the same open reading frame (ORF) but differed in their exon-intron organization. 5'-RACE confirmed that the type 1 3alpha-HSD/DD gene encodes for the dominant transcript in rat liver and it was the regulation of this gene that was previously studied. The rat type 1 3alpha-HSD/DD gene is 30 kb in length and consists of nine exons and eight introns. Exon 9 encodes +931 to 966 bp of the ORF and the 1292 bp 3'-UTR implicated in mRNA stability. This genomic structure is nearly identical to the homologous human genes, type 1 3alpha-HSD (chlordecone reductase/DD4, AKR1C4), type 2 3alpha-HSD (AKR1C3) and type 3 3alpha-HSD (bile-acid binding protein, AKR1C2) genes. Three different cDNA's containing identical ORFs for 3alpha-HSD have been reported suggesting that all three genes may be expressed in rat liver. Using 5' primers corresponding to the 5'-UTR's of the three different cDNA's only one PCR fragment was obtained and corresponded to the type 1 3alpha-HSD/DD gene. These data suggested that the type 2 and type 3 3alpha-HSD/DD genes are not abundantly expressed in rat liver. It is unknown

Beta/alpha continuous air monitor

DOEpatents

Becker, Gregory K.; Martz, Dowell E.

1989-01-01

A single deep layer silicon detector in combination with a microcomputer, recording both alpha and beta activity and the energy of each pulse, distinguishing energy peaks using a novel curve fitting technique to reduce the natural alpha counts in the energy region where plutonium and other transuranic alpha emitters are present, and using a novel algorithm to strip out radon daughter contribution to actual beta counts.

Complete primary structure of rainbow trout type I collagen consisting of alpha1(I)alpha2(I)alpha3(I) heterotrimers.

PubMed

Saito, M; Takenouchi, Y; Kunisaki, N; Kimura, S

2001-05-01

The subunit compositions of skin and muscle type I collagens from rainbow trout were found to be alpha1(I)alpha2(I)alpha3(I) and [alpha1(I)](2)alpha2(I), respectively. The occurrence of alpha3(I) has been observed only for bonyfish. The skin collagen exhibited more susceptibility to both heat denaturation and MMP-13 digestion than the muscle counterpart; the former had a lower denaturation temperature by about 0.5 degrees C than the latter. The lower stability of skin collagen, however, is not due to the low levels of imino acids because the contents of Pro and Hyp were almost constant in both collagens. On the other hand, some cDNAs coding for the N-terminal and/or a part of triple-helical domains of proalpha(I) chains were cloned from the cDNA library of rainbow trout fibroblasts. These cDNAs together with the previously cloned collagen cDNAs gave information about the complete primary structure of type I procollagen. The main triple-helical domain of each proalpha(I) chain had 338 uninterrupted Gly-X-Y triplets consisting of 1014 amino acids and was unique in its high content of Gly-Gly doublets. In particular, the bonyfish-specific alpha(I) chain, proalpha3(I) was characterized by the small number of Gly-Pro-Pro triplets, 19, and the large number of Gly-Gly doublets, 38, in the triple-helical domain, compared to 23 and 22, respectively, for proalpha1(I). The small number of Gly-Pro-Pro and the large number of Gly-Gly in proalpha3(I) was assumed to partially loosen the triple-helical structure of skin collagen, leading to the lower stability of skin collagen mentioned above. Finally, phylogenetic analyses revealed that proalpha3(I) had diverged from proalpha1(I). This study is the first report of the complete primary structure of fish type I procollagen.

Alpha particle spectrometry using superconducting microcalorimeters

NASA Astrophysics Data System (ADS)

Horansky, Robert; Ullom, Joel; Beall, James; Hilton, Gene; Stiehl, Gregory; Irwin, Kent; Plionis, Alexander; Lamont, Stephen; Rudy, Clifford; Rabin, Michael

2009-03-01

Alpha spectrometry is the preferred technique for analyzing trace samples of radioactive material because the alpha particle flux can be significantly higher than the gamma-ray flux from nuclear materials of interest. Traditionally, alpha spectrometry is performed with Si detectors whose resolution is at best 8 keV FWHM. Here, we describe the design and operation of a microcalorimeter alpha detector with an energy resolution of 1.06 keV FWHM at 5 MeV. We demonstrate the ability of the microcalorimeter to clearly resolve the alpha particles from Pu-239 and Pu-240, whose ratio differentiates reactor-grade Pu from weapons-grade. We also show the first direct observation of the decay of Po-209 to the ground state of Pb-205 which has traditionally been obscured by a much stronger alpha line 2 keV away. Finally, the 1.06 keV resolution observed for alpha particles is far worse than the 0.12 keV resolution predicted from thermal fluctuations and measurement of gamma-rays. The cause of the resolution degradation may be ion damage in the tin. Hence, alpha particle microcalorimeters may provide a novel tool for studying ion damage and lattice displacement energies in bulk materials.

Alpha voltaic batteries and methods thereof

NASA Technical Reports Server (NTRS)

Jenkins, Phillip (Inventor); Scheiman, David (Inventor); Castro, Stephanie (Inventor); Raffaelle, Ryne P. (Inventor); Wilt, David (Inventor); Chubb, Donald (Inventor)

2011-01-01

An alpha voltaic battery includes at least one layer of a semiconductor material comprising at least one p/n junction, at least one absorption and conversion layer on the at least one layer of semiconductor layer, and at least one alpha particle emitter. The absorption and conversion layer prevents at least a portion of alpha particles from the alpha particle emitter from damaging the p/n junction in the layer of semiconductor material. The absorption and conversion layer also converts at least a portion of energy from the alpha particles into electron-hole pairs for collection by the one p/n junction in the layer of semiconductor material.

Thermal conductivity enhancement and sedimentation reduction of magnetorheological fluids with nano-sized Cu and Al additives

NASA Astrophysics Data System (ADS)

Rahim, M. S. A.; Ismail, I.; Choi, S. B.; Azmi, W. H.; Aqida, S. N.

2017-11-01

This work presents enhanced material characteristics of smart magnetorheological (MR) fluids by utilizing nano-sized metal particles. Especially, enhancement of thermal conductivity and reduction of sedimentation rate of MR fluids those are crucial properties for applications of MR fluids are focussed. In order to achieve this goal, a series of MR fluid samples are prepared using carbonyl iron particles (CIP) and hydraulic oil, and adding nano-sized particles of copper (Cu), aluminium (Al), and fumed silica (SiO2). Subsequently, the thermal conductivity is measured by the thermal property analyser and the sedimentation of MR fluids is measured using glass tubes without any excitation for a long time. The measured thermal conductivity is then compared with theoretical models such as Maxwell model at various CIP concentrations. In addition, in order to show the effectiveness of MR fluids synthesized in this work, the thermal conductivity of MRF-132DG which is commercially available is measured and compared with those of the prepared samples. It is observed that the thermal conductivity of the samples is much better than MRF-132DG showing the 148% increment with 40 vol% of the magnetic particles. It is also observed that the sedimentation rate of the prepared MR fluid samples is less than that of MRF-132DG showing 9% reduction with 40 vol% of the magnetic particles. The mixture optimized sample with high conductivity and low sedimentation was also obtained. The magnetization of the sample recorded an enhancement of 70.5% when compared to MRF-132DG. Furthermore, the shear yield stress of the sample were also increased with and without the influence of magnetic field.

Strategy for chemotherapeutic delivery using a nanosized porous metal-organic framework with a central composite design

PubMed Central

Li, Yingpeng; Li, Xiuyan; Guan, Qingxia; Zhang, Chunjing; Xu, Ting; Dong, Yujing; Bai, Xinyu; Zhang, Weiping

2017-01-01

Background Enhancing drug delivery is an ongoing endeavor in pharmaceutics, especially when the efficacy of chemotherapy for cancer is concerned. In this study, we prepared and evaluated nanosized HKUST-1 (nanoHKUST-1), nanosized metal-organic drug delivery framework, loaded with 5-fluorouracil (5-FU) for potential use in cancer treatment. Materials and methods NanoHKUST-1 was prepared by reacting copper (II) acetate [Cu(OAc)2] and benzene-1,3,5-tricarboxylic acid (H3BTC) with benzoic acid (C6H5COOH) at room temperature (23.7°C±2.4°C). A central composite design was used to optimize 5-FU-loaded nanoHKUST-1. Contact time, ethanol concentration, and 5-FU:material ratios were the independent variables, and the entrapment efficiency of 5-FU was the response parameter measured. Powder X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and nitrogen adsorption were used to determine the morphology of nanoHKUST-1. In addition, 5-FU release studies were conducted, and the in vitro cytotoxicity was evaluated. Results Entrapment efficiency and drug loading were 9.96% and 40.22%, respectively, while the small-angle X-ray diffraction patterns confirmed a regular porous structure. The SEM and TEM images of the nanoHKUST-1 confirmed the presence of round particles (diameter: approximately 100 nm) and regular polygon arrays of mesoporous channels of approximately 2–5 nm. The half-maximal lethal concentration (LC50) of the 5-FU-loaded nanoHKUST-1 was approximately 10 µg/mL. Conclusion The results indicated that nanoHKUST-1 is a potential vector worth developing as a cancer chemotherapeutic drug delivery system. PMID:28260892

Strategy for chemotherapeutic delivery using a nanosized porous metal-organic framework with a central composite design.

PubMed

Li, Yingpeng; Li, Xiuyan; Guan, Qingxia; Zhang, Chunjing; Xu, Ting; Dong, Yujing; Bai, Xinyu; Zhang, Weiping

2017-01-01

Enhancing drug delivery is an ongoing endeavor in pharmaceutics, especially when the efficacy of chemotherapy for cancer is concerned. In this study, we prepared and evaluated nanosized HKUST-1 (nanoHKUST-1), nanosized metal-organic drug delivery framework, loaded with 5-fluorouracil (5-FU) for potential use in cancer treatment. NanoHKUST-1 was prepared by reacting copper (II) acetate [Cu(OAc) 2 ] and benzene-1,3,5-tricarboxylic acid (H 3 BTC) with benzoic acid (C 6 H 5 COOH) at room temperature (23.7°C±2.4°C). A central composite design was used to optimize 5-FU-loaded nanoHKUST-1. Contact time, ethanol concentration, and 5-FU:material ratios were the independent variables, and the entrapment efficiency of 5-FU was the response parameter measured. Powder X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and nitrogen adsorption were used to determine the morphology of nanoHKUST-1. In addition, 5-FU release studies were conducted, and the in vitro cytotoxicity was evaluated. Entrapment efficiency and drug loading were 9.96% and 40.22%, respectively, while the small-angle X-ray diffraction patterns confirmed a regular porous structure. The SEM and TEM images of the nanoHKUST-1 confirmed the presence of round particles (diameter: approximately 100 nm) and regular polygon arrays of mesoporous channels of approximately 2-5 nm. The half-maximal lethal concentration (LC 50 ) of the 5-FU-loaded nanoHKUST-1 was approximately 10 µg/mL. The results indicated that nanoHKUST-1 is a potential vector worth developing as a cancer chemotherapeutic drug delivery system.

Spectral ellipsometry as a method for characterization of nanosized films with ferromagnetic layers

NASA Astrophysics Data System (ADS)

Hashim, H.; Singkh, S. P.; Panina, L. V.; Pudonin, F. A.; Sherstnev, I. A.; Podgornaya, S. V.; Shpetnyi, I. A.; Beklemisheva, A. V.

2017-11-01

Nanosized films with ferromagnetic layers are widely used in nanoelectronics, sensor systems and telecommunications. Their properties may strongly differ from those of bulk materials that is on account of interfaces, intermediate layers and diffusion. In the present work, spectral ellipsometry and magnetooptical methods are adapted for characterization of the optical parameters and magnetization processes in two- and three-layer Cr/NiFe, Al/NiFe and Cr(Al)/Ge/NiFe films onto a sitall substrate for various thicknesses of Cr and Al layers. At a layer thickness below 20 nm, the complex refractive coefficients depend pronouncedly on the thickness. In two-layer films, remagnetization changes weakly over a thickness of the top layer, but the coercive force in three-layer films increases by more than twice upon remagnetization, while increasing the top layer thickness from 4 to 20 nm.

Alpha-particle spectrometer experiment

NASA Technical Reports Server (NTRS)

Gorenstein, P.; Bjorkholm, P.

1972-01-01

Mapping the radon emanation of the moon was studied to find potential areas of high activity by detection of radon isotopes and their daughter products. It was felt that based on observation of regions overflown by Apollo spacecraft and within the field of view of the alpha-particle spectrometer, a radon map could be constructed, identifying and locating lunar areas of outgassing. The basic theory of radon migration from natural concentrations of uranium and thorium is discussed in terms of radon decay and the production of alpha particles. The preliminary analysis of the results indicates no significant alpha emission.

Potent and selective agonists of alpha-melanotropin (alphaMSH) action at human melanocortin receptor 5; linear analogs of alpha-melanotropin.

PubMed

Bednarek, Maria A; MacNeil, Tanya; Tang, Rui; Fong, Tung M; Cabello, M Angeles; Maroto, Marta; Teran, Ana

2007-05-01

Alpha-melanotropin, Ac-Ser(1)-Tyr-Ser-Met-Glu-His(6)-Phe(7)-Arg(8)-Trp(9)-Gly-Lys-Pro-Val(13)-NH(2)(1), is a non-selective endogenous agonist for the melanocortin receptor 5; the receptor present in various peripheral tissues and in the brain, cortex and cerebellum. Most of the synthetic analogs of alphaMSH, including a broadly used and more potent the NDP-alphaMSH peptide, Ac-Ser(1)-Tyr-Ser-Nle(4)-Glu-His(6)-D-Phe(7)-Arg(8)-Trp(9)-Gly-Lys-Pro-Val(13)-NH(2), are also not particularly selective for MC5R. To elucidate physiological functions of the melanocortin receptor 5 in rodents and humans, the receptor subtype selective research tools are needed. We report herein syntheses and pharmacological evaluation in vitro of several analogs of NDP-alphaMSH which are highly potent and specific agonists for the human MC5R. The new linear peptides, of structures and solubility properties similar to those of the endogenous ligand alphaMSH, are exemplified by compound 7, Ac-Ser(1)-Tyr-Ser-Met-Glu-Oic(6)-D-4,4'-Bip(7)-Pip(8)-Trp(9)-Gly-Lys-Pro-Val(13)-NH(2) (Oic: octahydroindole-2-COOH, 4,4'-Bip: 4,4'-biphenylalanine, Pip: pipecolic acid), shortly NODBP-alphaMSH, which has an IC(50)=0.74 nM (binding assay) and EC(50)=0.41 (cAMP production assay) at hMC5R nM and greater than 3500-fold selectivity with respect to the melanocortin receptors 1b, 3 and 4. A shorter peptide derived from NODBP-alphaMSH: Ac-Nle-Glu-Oic(6)-D-4,4'-Bip(7)-Pip(8)-Trp(9) -NH(2) (17) was measured to be an agonist only 10-fold less potent at hMC5R than the full length parent peptide. In the structure of this smaller analog, the Nle-Glu-Oic(6)-D-4,4'-Bip(7)-Pip(8) segment was found to be critical for high agonist potency, while the C-terminal Trp(9) residue was shown to be required for high hMC5R selectivity versus hMC1b,3,4R.

Plasma binding of an alpha-blocking agent, nicergoline--affinity for serum albumin and native and modified alpha 1-acid glycoprotein.

PubMed

Robert, L; Migne, J; Santonja, R; Zini, R; Schmid, K; Tillement, J P

1983-06-01

The binding of nicergoline, an alpha-blocking drug, by human plasma proteins was studied using gel filtration, polyacrylamide gel electrophoresis, and equilibrium dialysis techniques. 3H-labeled nicergoline added to plasma was eluted together with two major protein fractions, one containing mainly serum albumin, the other glycoproteins such as alpha 1-acid glycoprotein (alpha 1-AG). Equilibrium dialysis experiments with pure human serum albumin and alpha 1-AG as well as with its chemically modified forms, desialylated, carboxymethylated, and both desialylated and carboxymethylated alpha 1-AG gave the following results: nicergoline has about a 4-fold higher affinity for alpha 1-AG than for serum albumin. There are two binding sites per molecule on serum albumin and one on alpha 1-AG. The binding parameters of alpha 1-AG were not significantly modified by desialylation or carboxymethylation. Only desialylated and carboxymethylated alpha 1-AG showed a decreased binding for nicergoline, suggesting conformational modifications induced by these combined treatments. The fact that desialylated alpha 1-AG keeps its affinity for nicergoline suggests the possibility of a selective introduction of this drug in cells possessing the Ashwell-type specific receptor for desialylated alpha 1-AG, for instance hepatocytes. Increased serum alpha 1-AG concentration induced by inflammatory reactions will also modify the distribution of bound nicergoline between serum albumin and alpha 1-AG and as a consequence its half-life and cell distribution.

The dark side of the alpha rhythm: fMRI evidence for induced alpha modulation during complete darkness.

PubMed

Ben-Simon, Eti; Podlipsky, Ilana; Okon-Singer, Hadas; Gruberger, Michal; Cvetkovic, Dean; Intrator, Nathan; Hendler, Talma

2013-03-01

The unique role of the EEG alpha rhythm in different states of cortical activity is still debated. The main theories regarding alpha function posit either sensory processing or attention allocation as the main processes governing its modulation. Closing and opening eyes, a well-known manipulation of the alpha rhythm, could be regarded as attention allocation from inward to outward focus though during light is also accompanied by visual change. To disentangle the effects of attention allocation and sensory visual input on alpha modulation, 14 healthy subjects were asked to open and close their eyes during conditions of light and of complete darkness while simultaneous recordings of EEG and fMRI were acquired. Thus, during complete darkness the eyes-open condition is not related to visual input but only to attention allocation, allowing direct examination of its role in alpha modulation. A data-driven ridge regression classifier was applied to the EEG data in order to ascertain the contribution of the alpha rhythm to eyes-open/eyes-closed inference in both lighting conditions. Classifier results revealed significant alpha contribution during both light and dark conditions, suggesting that alpha rhythm modulation is closely linked to the change in the direction of attention regardless of the presence of visual sensory input. Furthermore, fMRI activation maps derived from an alpha modulation time-course during the complete darkness condition exhibited a right frontal cortical network associated with attention allocation. These findings support the importance of top-down processes such as attention allocation to alpha rhythm modulation, possibly as a prerequisite to its known bottom-up processing of sensory input. © 2012 Federation of European Neuroscience Societies and Blackwell Publishing Ltd.

New nanosized catalytic membrane reactors for hydrogenation with stored hydrogen: Prerequisites and the experimental basis for their creation

NASA Astrophysics Data System (ADS)

Soldatov, A. P.; Tsodikov, M. V.; Parenago, O. P.; Teplyakov, V. V.

2010-12-01

The prerequisites and prospects for creating a new generation of nanosized membrane reactors are considered. For the first time, hydrogenation reactions take place in ceramic membrane pores with hydrogen adsorbed beforehand in mono- and multilayered oriented carbon nanotubes with graphene walls (OCNTGs) formed on the internal pore surface. It is shown for Trumem microfiltration membranes with D avg ˜130 nm that oxidation reactions of CO on a Cu0.03Ti0.97O2 ± δ catalyst and the oxidative conversion of methane into synthesis gas and light hydrocarbons on La + Ce/MgO are considerably enhanced when they occur in membranes. Regularities of hydrogen adsorption, storage, and desorption in nanosized membrane reactors are investigated through OCNTG formation in Trumem ultrafiltration membrane pores with D avg = 50 and 90 nm and their saturation with hydrogen at a pressure of 10-13 MPa. It is shown that the amount of adsorbed hydrogen reaches 14.0% of OCNTG mass. Using thermogravimetric analysis in combination with mass-spectrometric analysis, hydrogen adsorption in OCNTG is first determined and its desorption is found to proceed at atmospheric pressure at a temperature of ˜175°C. It is shown that adsorbed hydrogen affects the transport properties of the membranes, reducing their efficiency with respect to liquids by 4-26 times. This is indirect confirmation of its high activity, due apparently the dissociative mechanism of adsorption.

A survey of the alpha-nucleon interaction

NASA Astrophysics Data System (ADS)

Ali, S.; Ahmad, A. A. Z.; Ferdous, N.

1985-10-01

This paper gives a survey of the alpha-nucleon interaction and then describes experimental work on angular distributions of differential scattering cross sections and polarizations in proton-alpha and neutron-alpha scattering. The phenomenological approach, which includes the study of both local and nonlocal potentials reproducing the experimental alpha-nucleon scattering data, is discussed. Basic studies of the alpha-nucleon interaction attempting to build an interaction between an alpha particle and a nucleon from first principles are then described. The authors then present a critical discussion of the results with some concluding remarks suggesting the direction for further investigation.

Neuroendocrine mediators up-regulate alpha1b- and alpha1d-adrenergic receptor subtypes in human monocytes.

PubMed

Rouppe van der Voort, C; Kavelaars, A; van de Pol, M; Heijnen, C J

1999-03-01

Beta2- and alpha2-adrenergic receptors (AR) are thought to be the main AR subtypes to exert the effects of catecholamines on the immune system. However, in the present study, we demonstrate that another subtype of AR can be induced in human monocytes. Expression of alpha1b- and alpha1d-AR mRNA can be obtained by culturing freshly isolated human peripheral blood monocytes with the neuroendocrine mediators dexamethasone or the beta2-AR agonist terbutaline. Using the human monocytic cell line THP-1, we demonstrate that increased levels of alpha1b- and alpha1d-mRNA are accompanied by increased levels of receptor protein as determined by Western blot analysis and radioligand binding assays. This study describes for the first time regulated expression of alpha1-AR subtypes in human monocytes.

Beta/alpha continuous air monitor

DOEpatents

Becker, G.K.; Martz, D.E.

1988-06-27

A single deep layer silicon detector in combination with a microcomputer, recording both alpha and beta activity and the energy of each pulse, distinquishing energy peaks using a novel curve fitting technique to reduce the natural alpha counts in the energy region where plutonium and other transuranic alpha emitters are present, and using a novel algorithm to strip out radon daughter contribution to actual beta counts. 7 figs.

ASYMMETRIC ABSORPTION PROFILES OF Ly{alpha} AND Ly{beta} IN DAMPED Ly{alpha} SYSTEMS

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

Lee, Hee-Won, E-mail: hwlee@sejong.ac.kr

2013-08-01

Damped Ly{alpha} systems observed in the quasar spectra are characterized by a high neutral hydrogen column density, N{sub HI} > 2 x 10{sup 20} cm{sup -2}. The absorption wing profiles are often fitted using the Voigt function due to the fact that the scattering cross section near the resonant line center is approximately described by the Lorentzian function. Since a hydrogen atom has infinitely many p states that participate in the electric dipole interaction, the cross section starts to deviate from the Lorentzian in an asymmetric way in the line wing regions. We investigate this asymmetry in the absorption linemore » profiles around Ly{alpha} and Ly{beta} as a function of the neutral hydrogen column density N{sub HI}. In terms of {Delta}{lambda} {identical_to} {lambda} - {lambda}{sub {alpha}}, we expand the Kramers-Heisenberg formula around Ly{alpha} to find {sigma}({lambda}) {approx_equal} (0.5f{sub 12}){sup 2}{sigma}{sub T}({Delta}{lambda}/{lambda}{sub {alpha}}){sup -2}[1 + 3.792({Delta}{lambda}/{lambda}{sub {alpha}})], where f{sub 12} and {sigma}{sub T} are the oscillator strength of Ly{alpha} and the Thomson scattering cross section, respectively. In terms of {Delta}{lambda}{sub 2} {identical_to} {lambda} - {lambda}{sub {beta}} in the vicinity of Ly{beta}, the total scattering cross section, given as the sum of cross sections for Rayleigh and Raman scattering, is shown to be {sigma}({lambda}) {approx_equal} {sigma}{sub T}(0.5f{sub 13}){sup 2}(1 + R{sub 0})({Delta}{lambda}{sub 2}/{lambda}{sub {beta}}){sup -2}[1 - 24.68({Delta}{lambda}{sub 2}/{lambda}{sub {beta}})] with f{sub 13} and the factor R{sub 0} = 0.1342 being the oscillator strength for Ly{beta} and the ratio of the Raman cross section to Rayleigh cross section, respectively. A redward asymmetry develops around Ly{alpha}, whereas a blue asymmetry is obtained for Ly{beta}. The absorption center shifts are found to be almost proportional to the neutral hydrogen column density.« less

Association of EEG alpha variants and alpha power with alcohol dependence in Mexican American young adults.

PubMed

Ehlers, Cindy L; Phillips, Evelyn

2007-02-01

Several studies support an association between electroencephalogram (EEG) voltage and alcohol dependence. However, the distribution of EEG variants also appears to differ depending on an individual's ethnic heritage, suggesting significant genetic stratification of this EEG phenotype. The present study's aims were to investigate the incidence of EEG alpha variants and spectral power in the alpha frequency range in Mexican American young adults based on gender, and personal and family history of alcohol dependence. Clinical ratings (high-, medium-, and low alpha voltage variants) and spectral characteristics of the EEG in the alpha frequency range (7.5-12 Hz) were investigated in young adult (age 18-25 years) Mexican American men (n=98) and women (n=138) who were recruited from the community. Nineteen percent (n=45) of the participants had a low-voltage alpha EEG variant, 18% had a high-voltage variant, and 63% had a medium-voltage variant. There were no significant differences in the distribution of the EEG variants based on family history of alcohol dependence. There was a significant relationship between gender and the three alpha variants (chi2=9.7; df=2; P<.008), and there were no male participants with alcohol dependence with high alpha variants (chi2=5.8; df=2; P<.056). Alcohol dependence, but not a family history of alcohol dependence, was associated with lower spectral power in the alpha frequency range in the right (F=4.4; df=1,96; P<.04) and left (F=5.3; df=1.96; P<.02) occipital areas in the men but not in the women. In conclusion, in this select population of Mexican American young adults, male gender and alcohol dependence are associated with an absence of high-voltage alpha variants and lower alpha power in the EEG. These data suggest that EEG low voltage, a highly heritable trait, may represent an important endophenotype in male Mexican Americans that may aid in linking brain function with genetic factors underlying alcohol dependence in this ethnic

Alpha-Driven MHD and MHD-Induced Alpha Loss in TFTR DT Experiments

NASA Astrophysics Data System (ADS)

Chang, Zuoyang

1996-11-01

Theoretical calculation and numerical simulation indicate that there can be interesting interactions between alpha particles and MHD activity which can adversely affect the performance of a tokamak reactor (e.g., ITER). These interactions include alpha-driven MHD, like the toroidicity-induced-Alfven-eigenmode (TAE) and MHD induced alpha particle losses or redistribution. Both phenomena have been observed in recent TFTR DT experiments. Weak alpha-driven TAE activity was observed in a NBI-heated DT experiment characterized by high q0 ( >= 2) and low core magnetic shear. The TAE mode appears at ~30-100 ms after the neutral beam turning off approximately as predicted by theory. The mode has an amplitude measured by magnetic coils at the edge tildeB_p ~1 mG, frequency ~150-190 kHz and toroidal mode number ~2-3. It lasts only ~ 30-70 ms and has been seen only in DT discharges with fusion power level about 1.5-2.0 MW. Numerical calculation using NOVA-K code shows that this type of plasma has a big TAE gap. The calculated TAE frequency and mode number are close to the observation. (2) KBM-induced alpha particle loss^1. In some high-β, high fusion power DT experiments, enhanced alpha particle losses were observed to be correlated to the high frequency MHD modes with f ~100-200 kHz (the TAE frequency would be two-times higher) and n ~5-10. These modes are localized around the peak plasma pressure gradient and have ballooning characteristics. Alpha loss increases by 30-100% during the modes. Particle orbit simulations show the added loss results from wave-particle resonance. Linear instability analysis indicates that the plasma is unstable to the kinetic MHD ballooning modes (KBM) driven primarily by strong local pressure gradients. ----------------- ^1Z. Chang, et al, Phys. Rev. Lett. 76 (1996) 1071. In collaberation with R. Nazikian, G.-Y. Fu, S. Batha, R. Budny, L. Chen, D. Darrow, E. Fredrickson, R. Majeski, D. Mansfield, K. McGuire, G. Rewoldt, G. Taylor, R. White, K

Emphysema and Alpha-1

MedlinePlus

... Healthy Alpha-1 Facts Alpha-1 Links Emphysema Emphysema, which is a form of chronic obstructive pulmonary disease, or COPD, can occur when a person inherits a defective copy of the AAT gene from both parents. People who ... of developing emphysema, but generally they will only develop the disease ...

The generalized liquid drop model alpha-decay formula: Predictability analysis and superheavy element alpha half-lives

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

Dasgupta-Schubert, N.; Reyes, M.A.

2007-11-15

The predictive accuracy of the generalized liquid drop model (GLDM) formula for alpha-decay half-lives has been investigated in a detailed manner and a variant of the formula with improved coefficients is proposed. The method employs the experimental alpha half-lives of the well-known alpha standards to obtain the coefficients of the analytical formula using the experimental Q{sub {alpha}} values (the DSR-E formula), as well as the finite range droplet model (FRDM) derived Q{sub {alpha}} values (the FRDM-FRDM formula). The predictive accuracy of these formulae was checked against the experimental alpha half-lives of an independent set of nuclei (TEST) that span approximatelymore » the same Z, A region as the standards and possess reliable alpha spectroscopic data, and were found to yield good results for the DSR-E formula but not for the FRDM-FRDM formula. The two formulae were used to obtain the alpha half-lives of superheavy elements (SHE) and heavy nuclides where the relative accuracy was found to be markedly improved for the FRDM-FRDM formula, which corroborates the appropriateness of the FRDM masses and the GLDM prescription for high Z, A nuclides. Further improvement resulted, especially for the FRDM-FRDM formula, after a simple linear optimization over the calculated and experimental half-lives of TEST was used to re-calculate the half-lives of the SHE and heavy nuclides. The advantage of this optimization was that it required no re-calculation of the coefficients of the basic DSR-E or FRDM-FRDM formulae. The half-lives for 324 medium-mass to superheavy alpha decaying nuclides, calculated using these formulae and the comparison with experimental half-lives, are presented.« less

Cortical Alpha Activity in Schizoaffective Patients

PubMed Central

Moeini, Mahdi; Khaleghi, Ali; Mohammadi, Mohammad Reza; Zarafshan, Hadi; Fazio, Rachel L.; Majidi, Hamid

2017-01-01

Objective: Electrophysiological studies have identified abnormal oscillatory activities in the cerebral cortex in schizophrenia and mood disorders. Biological and pathophysiological evidence suggests specific deficits in serotonin (5-HT) receptor function in schizoaffective disorder (SA), a clinical syndrome with characteristics of both schizophrenia and bipolar disorder. This study investigated alpha oscillations in patients with SA. Method: Electroencephalography was used to measure ongoing and evoked alpha oscillations in 38 adults meeting Diagnostic and Statistical Manual of Mental Disorders–Fourth Edition (DSM–IV) criteria for SA, and in 39 healthy controls. Results: Spontaneous alpha power of the participants with SA was significantly lower than that of healthy participants [F (1, 75) = 8.81, P < 0.01]. Evoked alpha activity was also decreased in SA compared to controls [F (1, 75) = 5.67, P = 0.025]. Conclusion: A strong reduction of alpha power in the posterior regions may reflect abnormality in the thalamocortical circuits. It is shown that hypoxia and reduced cerebral blood flow is associated with reduced alpha activity among different regions of the brain. Therefore, it can be concluded that greatly decreased alpha activity, particularly in centro-parietal and occipital regions, is related to SA symptoms such as hallucinations. PMID:28496495

Cortical Alpha Activity in Schizoaffective Patients.

PubMed

Moeini, Mahdi; Khaleghi, Ali; Mohammadi, Mohammad Reza; Zarafshan, Hadi; Fazio, Rachel L; Majidi, Hamid

2017-01-01

Objective: Electrophysiological studies have identified abnormal oscillatory activities in the cerebral cortex in schizophrenia and mood disorders. Biological and pathophysiological evidence suggests specific deficits in serotonin (5-HT) receptor function in schizoaffective disorder (SA), a clinical syndrome with characteristics of both schizophrenia and bipolar disorder. This study investigated alpha oscillations in patients with SA. Method: Electroencephalography was used to measure ongoing and evoked alpha oscillations in 38 adults meeting Diagnostic and Statistical Manual of Mental Disorders-Fourth Edition (DSM-IV) criteria for SA, and in 39 healthy controls. Results: Spontaneous alpha power of the participants with SA was significantly lower than that of healthy participants [F (1, 75) = 8.81, P < 0.01]. Evoked alpha activity was also decreased in SA compared to controls [F (1, 75) = 5.67, P = 0.025]. Conclusion : A strong reduction of alpha power in the posterior regions may reflect abnormality in the thalamocortical circuits. It is shown that hypoxia and reduced cerebral blood flow is associated with reduced alpha activity among different regions of the brain. Therefore, it can be concluded that greatly decreased alpha activity, particularly in centro-parietal and occipital regions, is related to SA symptoms such as hallucinations.

Strengthening Effect of Extruded Mg-8Sn-2Zn-2Al Alloy: Influence of Micro and Nano-Size Mg2Sn Precipitates

PubMed Central

Cheng, Weili; Bai, Yang; Wang, Lifei; Wang, Hongxia; Bian, Liping; Yu, Hui

2017-01-01

In this study, Mg-8Sn-2Zn-2Al (TZA822) alloys with varying Mg2Sn contents prior to extrusion were obtained by different pre-treatments (without and with T4), and the strengthening response related to micro and nano-size Mg2Sn precipitates in the extruded TZA822 alloys was reported. The results showed that the morphology of nano-size Mg2Sn precipitates exhibits a significant change in basal plane from rod-like to spherical, owing to the decrement in the fraction of micro-size particles before extrusion. Meanwhile, the spherical Mg2Sn precipitates provided a much stronger strengthening effect than did the rod-like ones, which was ascribed to uniform dispersion and refinement of spherical precipitates to effectively hinder basal dislocation slip. As a consequence, the extruded TZA822 alloy with T4 showed a higher tensile yield strength (TYS) of 245 MPa, ultimate tensile strength (UTS) of 320 MPa and elongation (EL) of 26.5%, as well as a lower degree of yield asymmetry than their counterpart without T4. Detailed reasons for the strengthening effect were given and analyzed. PMID:28773180

Fasting induces basolateral uptake transporters of the SLC family in the liver via HNF4alpha and PGC1alpha.

PubMed

Dietrich, Christoph G; Martin, Ina V; Porn, Anne C; Voigt, Sebastian; Gartung, Carsten; Trautwein, Christian; Geier, Andreas

2007-09-01

Fasting induces numerous adaptive changes in metabolism by several central signaling pathways, the most important represented by the HNF4alpha/PGC-1alpha-pathway. Because HNF4alpha has been identified as central regulator of basolateral bile acid transporters and a previous study reports increased basolateral bile acid uptake into the liver during fasting, we hypothesized that HNF4alpha is involved in fasting-induced bile acid uptake via upregulation of basolateral bile acid transporters. In rats, mRNA of Ntcp, Oatp1, and Oatp2 were significantly increased after 48 h of fasting. Protein expression as determined by Western blot showed significant increases for all three transporters 72 h after the onset of fasting. Whereas binding activity of HNF1alpha in electrophoretic mobility shift assays remained unchanged, HNF4alpha binding activity to the Ntcp promoter was increased significantly. In line with this result, we found significantly increased mRNA expression of HNF4alpha and PGC-1alpha. Functional studies in HepG2 cells revealed an increased endogenous NTCP mRNA expression upon cotransfection with either HNF4alpha, PGC-1alpha, or a combination of both. We conclude that upregulation of the basolateral bile acid transporters Ntcp, Oatp1, and Oatp2 in fasted rats is mediated via the HNF4alpha/PGC-1alpha pathway.

Serum concentrations of tumour necrosis factor-alpha (TNF-alpha) and soluble TNF-alpha receptor p55 in patients with hypothyroidism and hyperthyroidism before and after normalization of thyroid function.

PubMed

Díez, Juan J; Hernanz, Angel; Medina, Sonia; Bayón, Carmen; Iglesias, Pedro

2002-10-01

Tumour necrosis factor-alpha (TNF-alpha) is a cytokine with numerous immunological and metabolic activities. Receptors for TNF-alpha have been demonstrated in thyroid follicular cells and TNF-alpha and its receptors have been implicated in the cytotoxic mechanisms that characterize the thyroid destruction in autoimmune thyroid disease. In patients with Graves' disease, serum levels of TNF-alpha have been reported to be elevated and administration of TNF-alpha to humans has been shown to induce hormonal alterations resembling those seen in the nonthyroidal illness syndrome. To evaluate serum concentrations of TNF-alpha and the soluble receptor for TNF-alpha (sTNFR-I) in a group of patients with thyroid dysfunction before and after normalization of thyroid function with appropriate therapy. We studied 20 patients with hypothyroidism (18 women and 2 men, mean age +/- SD, 48.8 +/- 16.1 years) and 20 patients with hyperthyroidism (14 women and 6 men, age 44.6 +/- 15.9 years). Patients were assessed at the time of diagnosis and again after normalization of thyroid function tests with appropriate therapy. A group of 20 healthy subjects (15 women and 5 men, age 44.9 +/- 15.1 years) were also studied as a control group. All subjects were ambulatory and were studied as outpatients during visits to the endocrinology clinic. Serum concentrations of free T4 (FT4), total T3, TSH, TNF-alpha and sTNFR-I were measured in all subjects. TNF-alpha and sTNFR-I were measured using a quantitative enzyme immunoassay. In patients with hypothyroidism serum concentrations of TNF-alpha (3.17 +/- 1.18 pg/ml) and sTNFR-I (1273 +/- 364 pg/ml) were significantly higher than those found in controls (2.42 +/- 0.76 pg/ml, P < 0.05, and 971 +/- 235 pg/ml, P < 0.01, respectively). Normalization of thyroid function with l-thyroxine therapy did not significantly modify TNF-alpha or sTNFR-I levels. There were no differences in pre- and post-therapy values of TNF-alpha and sTNFR-I in patients with

21 CFR 882.1610 - Alpha monitor.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Alpha monitor. 882.1610 Section 882.1610 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES NEUROLOGICAL DEVICES Neurological Diagnostic Devices § 882.1610 Alpha monitor. (a) Identification. An alpha...

21 CFR 882.1610 - Alpha monitor.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Alpha monitor. 882.1610 Section 882.1610 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES NEUROLOGICAL DEVICES Neurological Diagnostic Devices § 882.1610 Alpha monitor. (a) Identification. An alpha...

Solution structure for Pandinus toxin K-alpha (PiTX-K alpha), a selective blocker of A-type potassium channels.

PubMed

Tenenholz, T C; Rogowski, R S; Collins, J H; Blaustein, M P; Weber, D J

1997-03-11

PiTX-K alpha, a 35-residue peptide recently isolated from the venom of Pandinus imperator, blocks the rapidly inactivating (A-type) K+ channel(s) in rat brain synaptosomes and the cloned Kv 1.2 potassium channel at very low toxin concentrations (6 nM and 32 pM, respectively) [Rogowski, R. S., Collins, J. H., O'Neil, T. J., Gustafson, T. A., Werkman, T. A., Rogawski, M. A., Tenenholz, T. C., Weber, D. J., & Blaustein, M. P. (1996) Mol. Pharmacol. 50, 1167-1177]. The three-dimensional structure of PiTX-K alpha was determined using NMR spectroscopy in order to understand its selectivity and affinity toward K+ channels. PiTX-K alpha was found to have an alpha-helix from residues 10 to 21 and two beta-strands (betaI, 26-28; betaII, 33-35) connected by a type II beta-turn to form a small antiparallel beta-sheet. Three disulfide bonds, which are conserved in all members of the charybdotoxin family (alpha-K toxins), anchor one face of the alpha-helix to the beta-sheet. The N-terminal portion of PiTX-K alpha has three fewer residues than other alpha-K toxins such as charybdotoxin. Rather than forming a third beta-strand as found for other alpha-K toxins, the N-terminal region of PiTX-K alpha adopts an extended conformation. This structural difference in PiTX-K alpha together with differences in sequence at Pro-10, Tyr-14, and Asn-25 (versus Ser-10, Trp-14, and Arg-25 in CTX) may explain why PiTX-K alpha does not block maxi-K+ channels. Differences in three-dimensional structure between PiTX-K alpha and charybdotoxin are also observed in both the tight turn and the loop that connects the first beta-strand to the alpha-helix. As a result, side chains of two residues (Tyr-23 and Arg-31) are in regions of PiTX-K alpha that probably interact with rapidly inactivating A-type K+ channels. The analogous residues in charybdotoxin are positioned differently on the toxin surface. Thus, the locations of Tyr-23 and Arg-31 side chains in PiTX-K alpha could explain why this toxin blocks A

Nanotip analysis for dielectrophoretic concentration of nanosized viral particles.

PubMed

Yeo, Woon-Hong; Lee, Hyun-Boo; Kim, Jong-Hoon; Lee, Kyong-Hoon; Chung, Jae-Hyun

2013-05-10

Rapid and sensitive detection of low-abundance viral particles is strongly demanded in health care, environmental control, military defense, and homeland security. Current detection methods, however, lack either assay speed or sensitivity, mainly due to the nanosized viral particles. In this paper, we compare a dendritic, multi-terminal nanotip ('dendritic nanotip') with a single terminal nanotip ('single nanotip') for dielectrophoretic (DEP) concentration of viral particles. The numerical computation studies the concentration efficiency of viral particles ranging from 25 to 100 nm in radius for both nanotips. With DEP and Brownian motion considered, when the particle radius decreases by two times, the concentration time for both nanotips increases by 4-5 times. In the computational study, a dendritic nanotip shows about 1.5 times faster concentration than a single nanotip for the viral particles because the dendritic structure increases the DEP-effective area to overcome the Brownian motion. For the qualitative support of the numerical results, the comparison experiment of a dendritic nanotip and a single nanotip is conducted. Under 1 min of concentration time, a dendritic nanotip shows a higher sensitivity than a single nanotip. When the concentration time is 5 min, the sensitivity of a dendritic nanotip for T7 phage is 10(4) particles ml(-1). The dendritic nanotip-based concentrator has the potential for rapid identification of viral particles.

Nanotip analysis for dielectrophoretic concentration of nanosized viral particles

NASA Astrophysics Data System (ADS)

Yeo, Woon-Hong; Lee, Hyun-Boo; Kim, Jong-Hoon; Lee, Kyong-Hoon; Chung, Jae-Hyun

2013-05-01

Rapid and sensitive detection of low-abundance viral particles is strongly demanded in health care, environmental control, military defense, and homeland security. Current detection methods, however, lack either assay speed or sensitivity, mainly due to the nanosized viral particles. In this paper, we compare a dendritic, multi-terminal nanotip (‘dendritic nanotip’) with a single terminal nanotip (‘single nanotip’) for dielectrophoretic (DEP) concentration of viral particles. The numerical computation studies the concentration efficiency of viral particles ranging from 25 to 100 nm in radius for both nanotips. With DEP and Brownian motion considered, when the particle radius decreases by two times, the concentration time for both nanotips increases by 4-5 times. In the computational study, a dendritic nanotip shows about 1.5 times faster concentration than a single nanotip for the viral particles because the dendritic structure increases the DEP-effective area to overcome the Brownian motion. For the qualitative support of the numerical results, the comparison experiment of a dendritic nanotip and a single nanotip is conducted. Under 1 min of concentration time, a dendritic nanotip shows a higher sensitivity than a single nanotip. When the concentration time is 5 min, the sensitivity of a dendritic nanotip for T7 phage is 104 particles ml-1. The dendritic nanotip-based concentrator has the potential for rapid identification of viral particles.

Peroxisome proliferator-activated receptor {alpha}-independent peroxisome proliferation

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

Zhang Xiuguo; Tanaka, Naoki; Nakajima, Takero

2006-08-11

Hepatic peroxisome proliferation, increases in the numerical and volume density of peroxisomes, is believed to be closely related to peroxisome proliferator-activated receptor {alpha} (PPAR{alpha}) activation; however, it remains unknown whether peroxisome proliferation depends absolutely on this activation. To verify occurrence of PPAR{alpha}-independent peroxisome proliferation, fenofibrate treatment was used, which was expected to significantly enhance PPAR{alpha} dependence in the assay system. Surprisingly, a novel type of PPAR{alpha}-independent peroxisome proliferation and enlargement was uncovered in PPAR{alpha}-null mice. The increased expression of dynamin-like protein 1, but not peroxisome biogenesis factor 11{alpha}, might be associated with the PPAR{alpha}-independent peroxisome proliferation at least in part.

TNF-alpha infusion impairs corpora cavernosa reactivity.

PubMed

Carneiro, Fernando S; Zemse, Saiprazad; Giachini, Fernanda R C; Carneiro, Zidonia N; Lima, Victor V; Webb, R Clinton; Tostes, Rita C

2009-03-01

Erectile dysfunction (ED), as well as cardiovascular diseases (CVDs), is associated with endothelial dysfunction and increased levels of proinflammatory cytokines, such as tumor necrosis factor-alpha (TNF-alpha). We hypothesized that increased TNF-alpha levels impair cavernosal function. In vitro organ bath studies were used to measure cavernosal reactivity in mice infused with vehicle or TNF-alpha (220 ng/kg/min) for 14 days. Gene expression of nitric oxide synthase isoforms was evaluated by real-time polymerase chain reaction. Corpora cavernosa from TNF-alpha-infused mice exhibited decreased nitric oxide (NO)-dependent relaxation, which was associated with decreased endothelial nitric oxide synthase (eNOS) and neuronal nitric oxide synthase (nNOS) cavernosal expression. Cavernosal strips from the TNF-alpha-infused mice displayed decreased nonadrenergic-noncholinergic (NANC)-induced relaxation (59.4 +/- 6.2 vs. control: 76.2 +/- 4.7; 16 Hz) compared with the control animals. These responses were associated with decreased gene expression of eNOS and nNOS (P < 0.05). Sympathetic-mediated, as well as phenylephrine (PE)-induced, contractile responses (PE-induced contraction; 1.32 +/- 0.06 vs. control: 0.9 +/- 0.09, mN) were increased in cavernosal strips from TNF-alpha-infused mice. Additionally, infusion of TNF-alpha increased cavernosal responses to endothelin-1 and endothelin receptor A subtype (ET(A)) receptor expression (P < 0.05) and slightly decreased tumor necrosis factor-alpha receptor 1 (TNFR1) expression (P = 0.063). Corpora cavernosa from TNF-alpha-infused mice display increased contractile responses and decreased NANC nerve-mediated relaxation associated with decreased eNOS and nNOS gene expression. These changes may trigger ED and indicate that TNF-alpha plays a detrimental role in erectile function. Blockade of TNF-alpha actions may represent an alternative therapeutic approach for ED, especially in pathologic conditions associated with increased levels

Long range alpha particle detector

DOEpatents

MacArthur, Duncan W.; Wolf, Michael A.; McAtee, James L.; Unruh, Wesley P.; Cucchiara, Alfred L.; Huchton, Roger L.

1993-01-01

An alpha particle detector capable of detecting alpha radiation from distant sources. In one embodiment, a high voltage is generated in a first electrically conductive mesh while a fan draws air containing air molecules ionized by alpha particles through an air passage and across a second electrically conductive mesh. The current in the second electrically conductive mesh can be detected and used for measurement or alarm. The detector can be used for area, personnel and equipment monitoring.

Long range alpha particle detector

DOEpatents

MacArthur, D.W.; Wolf, M.A.; McAtee, J.L.; Unruh, W.P.; Cucchiara, A.L.; Huchton, R.L.

1993-02-02

An alpha particle detector capable of detecting alpha radiation from distant sources. In one embodiment, a high voltage is generated in a first electrically conductive mesh while a fan draws air containing air molecules ionized by alpha particles through an air passage and across a second electrically conductive mesh. The current in the second electrically conductive mesh can be detected and used for measurement or alarm. The detector can be used for area, personnel and equipment monitoring.

[Interferon alpha-2b modified with polyethylene glycol].

PubMed

Wu, Yingxin; Zhai, Yanqin; Lei, Jiandu; Ma, Guanghui; Su, Zhiguo

2008-09-01

In order to obtain a more stable PEGylated interferon alpha-2b, and prolong its half life, interferon alpha-2b (IFN alpha-2b) was modified with monomethoxy polyethylene glycol propionaldehyde (mPEG-ALD) 20000. It was found that the optimized reaction condition for the maximum bioactivity and highest PEGylation degree of the mono PEGylated interferon alpha-2b was as follows: in 20 mmol/L, pH 6.5, citric acid and sodium dihydrogen phosphate buffer, the concentration of IFN alpha-2b was 4 mg/mL, and the molar ratio of PEG/IFN alpha-2b was 8:1, and the reaction time was 20 h at 4 degrees C. Under the optimized reaction condition, the mono PEGylation degree reached to 55%. Ion exchange chromatography was used to separate and purify mono PEGylated interferon alpha-2b from the reaction mixture. The purity of mono PEGylated interferon alpha-2b was higher than 97% characterized by HPLC. The bioactivity of the mono PEGylated interferon alpha-2b was 13.4% of the native IFN alpha-2b, while its half life in SD rat is much longer than the native IFN alpha-2b. The mono PEGylated interferon alpha-2b is also stable in aqueous.

Inhibitory spectrum of alpha 2-plasmin inhibitor.

PubMed Central

Saito, H; Goldsmith, G H; Moroi, M; Aoki, N

1979-01-01

alpha 2-Plasmin inhibitor (alpha 2PI) has been recently characterized as a fast-reacting inhibitor of plasmin in human plasma and appears to play an important role in the regulation of fibrinolysis in vivo. We have studied the effect of purified alpha 2PI upon various proteases participating in human blood coagulation and kinin generation. At physiological concentration (50 microgram/ml), alpha 2PI inhibited the clot-promoting and prekallikrein-activating activity of Hageman factor fragments, the amidolytic, kininogenase, and clot-promoting activities of plasma kallikrein, and the clot-promoting properties of activated plasma thromboplastin antecedent (PTA, Factor XIa) and thrombin. alpha 2PI had minimal inhibitory effect on surface-bound activated PTA and activated Stuart factor (Factor Xa). alpha 2PI did not inhibit the activity of activated Christmas factor (Factor IXa) or urinary kallikrein. Heparin (1.5-2.0 units/ml) did not enhance the inhibitory function of alpha 2PI. These results suggest that, like other plasma protease inhibitors, alpha 2PI possesses a broad in vitro spectrum of inhibitory properties. PMID:156364

Bacterial Disproportionation of Elemental Sulfur Coupled to Chemical Reduction of Iron or Manganese

PubMed Central

Thamdrup, Bo; Finster, Kai; Hansen, Jens Würgler; Bak, Friedhelm

1993-01-01

A new chemolithotrophic bacterial metabolism was discovered in anaerobic marine enrichment cultures. Cultures in defined medium with elemental sulfur (S0) and amorphous ferric hydroxide (FeOOH) as sole substrates showed intense formation of sulfate. Furthermore, precipitation of ferrous sulfide and pyrite was observed. The transformations were accompanied by growth of slightly curved, rod-shaped bacteria. The quantification of the products revealed that S0 was microbially disproportionated to sulfate and sulfide, as follows: 4S0 + 4H2O → SO42- + 3H2S + 2H+. Subsequent chemical reactions between the formed sulfide and the added FeOOH led to the observed precipitation of iron sulfides. Sulfate and iron sulfides were also produced when FeOOH was replaced by FeCO3. Further enrichment with manganese oxide, MnO2, instead of FeOOH yielded stable cultures which formed sulfate during concomitant reduction of MnO2 to Mn2+. Growth of small rod-shaped bacteria was observed. When incubated without MnO2, the culture did not grow but produced small amounts of SO42- and H2S at a ratio of 1:3, indicating again a disproportionation of S0. The observed microbial disproportionation of S0 only proceeds significantly in the presence of sulfide-scavenging agents such as iron and manganese compounds. The population density of bacteria capable of S0 disproportionation in the presence of FeOOH or MnO2 was high, > 104 cm-3 in coastal sediments. The metabolism offers an explanation for recent observations of anaerobic sulfide oxidation to sulfate in anoxic sediments. PMID:16348835

The effects of SB 216469, an antagonist which discriminates between the alpha 1A-adrenoceptor and the human prostatic alpha 1-adrenoceptor.

PubMed Central

Chess-Williams, R.; Chapple, C. R.; Verfurth, F.; Noble, A. J.; Couldwell, C. J.; Michel, M. C.

1996-01-01

1. The affinity of the alpha 1-adrenoceptor antagonist SB 216469 (also known as REC 15/2739) has been determined at native and cloned alpha 1-adrenoceptor subtypes by radioligand binding and at functional alpha 1-adrenoceptor subtypes in isolated tissues. 2. In radioligand binding studies with [3H]-prazosin, SB 216469 had a high affinity at the alpha 1A-adrenoceptors of the rat cerebral cortex and kidney (9.5-9.8) but a lower affinity at the alpha 1B-adrenoceptors of the rat spleen and liver (7.7-8.2). 3. At cloned rat alpha 1-adrenoceptor subtypes transiently expressed in COS-1 cells and also at cloned human alpha 1-adrenoceptor subtypes stably transfected in Rat-1 cells, SB 216469 exhibited a high affinity at the alpha 1a-adrenoceptors (9.6-10.4) with a significantly lower affinity at the alpha 1b-adrenoceptor (8.0-8.4) and an intermediate affinity at the alpha 1d-adrenoceptor (8.7-9.2). 4. At functional alpha 1-adrenoceptors, SB 216469 had a similar pharmacological profile, with a high affinity at the alpha 1A-adrenoceptors of the rat vas deferens and anococcygeus muscle (pA2 = 9.5-10.0), a low affinity at the alpha 1B-adrenoceptors of the rat spleen (6.7) and guinea-pig aorta (8.0), and an intermediate affinity at the alpha 1D-adrenoceptors of the rat aorta (8.8). 5. Several recent studies have concluded that the alpha 1-adrenoceptor present in the human prostate has the pharmacological characteristics of the alpha 1A-adrenoceptor subtype. However, the affinity of SB 216469 at human prostatic alpha 1-adrenoceptors (pA2 = 8.1) determined in isolated tissue strips, was significantly lower than the values obtained at either the cloned alpha 1a-adrenoceptors (human, rat, bovine) or the native alpha 1A-adrenoceptors in radioligand binding and functional studies in the rat. 6. Our results with SB 216469, therefore, suggest that the alpha 1-adrenoceptor mediating contractile responses of the human prostate has properties which distinguish it from the cloned alpha 1a

[Anti-TNF alpha in dermatology].

PubMed

Mahe, E; Descamps, V

2002-12-01

The discovery of the major role of TNF alpha in the physiopathology of certain inflammatory diseases and notably in rheumatoid arthritis and Crohn's disease has led to the development of anti-TNF alpha drugs. These new therapeutic arms issued from bio-technology have rapidly demonstrated their efficacy in the treatment of these two diseases. The anti-TNF alpha arsenal is currently dominated by etanercept, a fusion protein composed of a soluble TNF alpha receptor, and infliximab, a chimeric monoclonal antibody. However, new molecules will soon enrich this arsenal. TNF alpha is a major cytokine of inflammatory diseases of the skin. Many dermatological diseases will probably benefit from these new treatments. Two studies have already demonstrated their interest in cutaneous and articular psoriasis. Encouraging sporadic results suggest other potential indications (Behcet's disease, bullous dermatitis, neutrophilic dermatitis, toxic epidermal necrolysis, systemic vascularitis,.). These promising new treatments, although expensive, and with yet unknown long term side effects, justify rigorous assessment of their efficacy and tolerance in each indication. Here again the dermatologist has a major role to play in post-marketing pharmacovigilance.

Expression of alpha-AR subtypes in T lymphocytes and role of the alpha-ARs in mediating modulation of T cell function.

PubMed

Bao, Jing-Yin; Huang, Yan; Wang, Feng; Peng, Yu-Ping; Qiu, Yi-Hua

2007-01-01

Previous work in our laboratory has shown that alpha-adrenoreceptors (alpha-ARs) and beta-ARs exist on lymphocytes from functional profile, and that the receptors mediate the regulation of lymphocyte function by catecholamines. In the present study, we directly examined the expression of alpha-AR subtypes, alpha(1)-AR and alpha(2)-AR mRNAs, in T lymphocytes and explored the roles of the alpha-AR subtypes and intracellular signal transduction mechanisms linked to the receptors in mediating the modulation of T lymphocyte function. T lymphocytes from mesenteric lymph nodes of rats were purified by using a nylon wool column. Reverse transcription polymerase chain reaction was used to detect the expression of alpha(1)-AR and alpha(2)-AR mRNAs in the freshly isolated T cells and the mitogen concanavalin A (Con A)-activated lymphocytes. Colorimetric methylthiazoletetrazolium assay was employed to measure lymphocyte proliferation induced by Con A. Interferon-gamma (IFN-gamma) and interleukin-4 (IL-4) levels in the Con A-stimulated lymphocyte culture supernatants were examined by enzyme-linked immunosorbent assay. T cells expressed both alpha(1)-AR and alpha(2)-AR mRNAs. The expression of both alpha(1)-AR and alpha(2)-AR mRNAs was significantly higher in the Con A-activated lymphocytes than in the resting lymphocytes. Phenylephrine, a selective alpha(1)-AR agonist, had no evident effect on lymphocyte proliferation nor on IFN-gamma and IL-4 production induced by Con A. However, the selective alpha(2)-AR agonist clonidine attenuated Con A-induced lymphocyte proliferation as well as IFN-gamma and IL-4 production. The inhibited lymphocyte proliferation and IFN-gamma and IL-4 production by clonidine were blocked by yohimbine, an alpha(2)-AR antagonist. Either phospholipase C inhibitor U-73122 or protein kinase C inhibitor chelerythrine partially prevented the suppressive effect of clonidine on Con A-stimulated lymphocyte proliferation and IL-4 production. T lymphocytes express

Elemental selenium at nano size (Nano-Se) as a potential chemopreventive agent with reduced risk of selenium toxicity: comparison with se-methylselenocysteine in mice.

PubMed

Zhang, Jinsong; Wang, Xufang; Xu, Tongwen

2008-01-01

Selenium (Se) is an essential trace element with a narrow margin between beneficial and toxic effects. As a promising chemopreventive agent, its use requires consumption over the long term, so the toxicity of Se is always a crucial concern. Based on clinical findings and recent studies in selenoprotein gene-modified mice, it is likely that the antioxidant function of one or more selenoproteins is responsible for the chemopreventive effect of Se. Furthermore, upregulation of phase 2 enzymes by Se has been implicated as a possible chemopreventive mechanism at supranutritional dietary levels. Se-methylselenocysteine (SeMSC), a naturally occurring organic Se product, is considered as one of the most effective chemopreventive selenocompounds. The present study revealed that, as compared with SeMSC, elemental Se at nano size (Nano-Se) possessed equal efficacy in increasing the activities of glutathione peroxidase, thioredoxin reductase, and glutathione S-transferase, but had much lower toxicity as indicated by median lethal dose, acute liver injury, survival rate, and short-term toxicity. Our results suggest that Nano-Se can serve as a potential chemopreventive agent with reduced risk of Se toxicity.

Siderophores, the answer for micro to nanosized asbestos fibre related health hazard

NASA Astrophysics Data System (ADS)

Bhattacharya, Shabori; Ledwani, Lalita; John, P. J.

2016-04-01

Recent studies on the potential toxicity of High Aspect Ratio Nanoparticles (HARN) has yet once again reinforced the health hazard imposed by asbestos fibres ranging from nano to micro size. Asbestos a naturally occurring fibrous mineral declared a Group I definite carcinogen by IARC (International Agency for Research on Cancer), a unit of WHO in the year 1987, has been extensively used since World War II to the near past for various commercial products. According to the most recent World Health Organization (WHO) estimates, asbestos-related diseases, resulting from exposure at workplace claims more than 107000 lives every year worldwide. The various types of toxic effects induced by asbestos in humans include - i) inflammation and fibrogenesis of lung, ii) mesothelioma iii) asbestosis and iv) bronchogenic carcinoma. The stability of asbestos in natural environment and its biological aggressiveness is related to their fibrous structure and dimensions. The actual risk associated with the exposure to nanosized asbestos, which is still unknown and escapes most regulations worldwide, has been shown in various toxicity assessment studies conducted on various animal models.In an effort to reduce the size of asbestos and therby its toxicity by limiting its biopersistence, oxalic acid treatment of asbestos coupled to power ultrasound treatment was carried out. The nanosized particles formed were still found to retain their hazardous effect. Similar were the results obtained on strong acid treatment of asbestos as well. A probable solution to the asbestos toxicity problem therefore envisaged was bioremediation. This involved the secretion of iron chelating molecules termed siderophores by microbes, which are of significance due to their ability to form very stable and soluble complexes with iron. Iron in asbestos composition is a major factor responsible for its carcinogenicity, removal or extraction of which would prove to be an effective answer to the worldwide problem

Effect of alpha-tocopherol on bovine in vitro fertilization.

PubMed

Marques, A; Santos, P; Antunes, G; Chaveiro, A; Moreira da Silva, F

2010-02-01

The objectives of this work are to determine if exogenous supplementation with alpha-tocopherol increases the in vitro fertilization (IVF) rate of bovine oocytes and improves viability of selected spermatozoa after 'swim-up'. The percentage of fertilized oocytes was significantly but negatively correlated (r = -0.941, p < 0.01) with the concentration of alpha-tocopherol. The control resulted in 95% of fertilized oocytes, which decreased as follows: 25 microM alpha-tocopherol (alpha25) 86%, 50 microM alpha-tocopherol (alpha50) 74%, 100 microM alpha-tocopherol (alpha100) 66% and 200 microM alpha-tocopherol (alpha200) 56%. Relatively to sperm viability after 'swim-up' with alpha-tocopherol supplementation, this antioxidant proved to have a beneficial effect as its concentration increased up to alpha50, decreasing for the concentrations of alpha100 and alpha200. Control resulted in 83% of live cells and 16% of dead cells; alpha25 resulted in 88% of live cells and 12% of dead cells; alpha50 resulted in 91% of live cells and 9% of dead cells; alpha100 resulted in 67% of live cells and 33% of dead cells; and finally alpha200 resulted in 57% of live cells and 42% of dead cells. In summary, the present study allows to conclude that, in our conditions, supplementation with the antioxidant alpha-tocopherol in IVF of bovine oocytes has a detrimental effect on fertilization rates. Nevertheless, exogenous supplementation with alpha-tocopherol at a concentration of 50 mM in the sperm-TALP media during the 'swim-up' technique has a significant beneficial effect on the selected spermatozoa viability.

Emerging potential of stimulus-responsive nanosized anticancer drug delivery systems for systemic applications.

PubMed

Ruttala, Hima Bindu; Ramasamy, Thiruganesh; Madeshwaran, Thiagarajan; Hiep, Tran Tuan; Kandasamy, Umadevi; Oh, Kyung Taek; Choi, Han-Gon; Yong, Chul Soon; Kim, Jong Oh

2018-02-01

The development of novel drug delivery systems based on well-defined polymer therapeutics has led to significant improvements in the treatment of multiple disorders. Advances in material chemistry, nanotechnology, and nanomedicine have revolutionized the practices of drug delivery. Stimulus-responsive material-based nanosized drug delivery systems have remarkable properties that allow them to circumvent biological barriers and achieve targeted intracellular drug delivery. Specifically, the development of novel nanocarrier-based therapeutics is the need of the hour in managing complex diseases. In this review, we have briefly described the fundamentals of drug targeting to diseased tissues, physiological barriers in the human body, and the mechanisms/modes of drug-loaded carrier systems. To that end, this review serves as a comprehensive overview of the recent developments in stimulus-responsive drug delivery systems, with focus on their potential applications and impact on the future of drug delivery.