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Sample records for alkali labile sites

  1. Localization of alkali-labile sites in donkey (Equus asinus) and stallion (Equus caballus) spermatozoa.

    PubMed

    Cortés-Gutiérrez, Elva I; Dávila-Rodríguez, Martha I; López-Fernández, Carmen; Fernández, José Luis; Crespo, Francisco; Gosálvez, Jaime

    2014-01-15

    The presence of constitutive alkali-labile sites (ALS) has been investigated using a protocol of DNA breakage detection-fluorescence in situ hybridization and comet assay in spermatozoa of donkey (Equus asinus) and stallion (Equus caballus). These results were compared with those obtained using a similar experimental approach using somatic cells. The relative abundance of ALS was of the order of four times more in spermatozoa than in somatic cells. Alkali-labile sites showed a tendency to cluster localized at the equatorial-distal regions of the sperm. The amount of hybridized signal in the ALS in the sperm of donkey (Equus asinus) was 1.3 times greater than in stallion (Equus caballus), and the length of the comet tail obtained in donkey sperm was 1.6 times longer than that observed in stallion (P < 0.05); however, these differences were not appreciated in somatic cells. In conclusion, ALS localization in sperm is not a randomized event and a different pattern of ALS distribution occurs for each species. These results suggest that ALS represents a species-specific issue related to chromatin organization in sperm and somatic cells in mammalian species, and they might diverge even with very short phylogenetic distances.

  2. Alkali-labile sites in sperm cells from Sus and Ovis species.

    PubMed

    Cortés-Gutiérrez, Elva I; Dávila-Rodríguez, Martha I; López-Fernández, Carmen; Fernández, José Luis; Gosálvez, Jaime

    2008-06-01

    Constitutive alkali-labile sites (ALSs) have been investigated using a protocol of DNA breakage detection-fluorescence in situ hybridization (DBD-FISH) in sperm cells from Sus domesticus (pig), Ovis gmelini musimon (mouflon) and Ovis aries (sheep). The results were compared with those obtained using leucocytes from the same species. Whole comparative genomic hybridization (W-CGH) showed that most of the constitutive ALSs in somatic and germ line cells in all species examined were constrained to particular repetitive satellite DNA sequences located in the pericentromeric constitutive heterochromatin of each chromosome. However, their relative abundance was different among cells of the same organism (leucocytes/sperm cells), and this trend was not maintained when the different species were compared. Thus, in mouflon, the density of ALSs in leucocytes when compared with that observed in sperm cells indicated abundance of the order of eight times less. In sheep, both leucocytes and sperm cells exhibited a large quantity of ALSs, being of the order of four times more abundant in sperm cells. In the pig genome, leucocytes showed a high abundance of ALSs (of the order of 12 times more that in sperm cells) but only involved the metacentric chromosomes of the karyotype. ALSs were not present in the acrocentric chromosomes. Contrary to mouflon and sheep, ALSs were relatively scarce in sperm cells from pig. These results suggest that ALSs are a transient structural feature in the cells of any organisms and point to a non-universal model of chromatin organization in sperm cells among mammals.

  3. Localisation and quantification of alkali-labile sites in human spermatozoa by DNA breakage detection-fluorescence in situ hybridisation.

    PubMed

    Cortés-Gutiérrez, E I; Dávila-Rodríguez, M I; Cerda-Flores, R M; Fernández, J L; López-Fernández, C; Aragón Tovar, A R; Gosálvez, J

    2015-03-01

    The localisation and quantification of constitutive alkali-labile sites (ALSs) were investigated using a protocol of DNA breakage detection plus fluorescence in situ hybridisation (DBD-FISH) and alkaline single-cell gel electrophoresis (SCGE or comet assay), in spermatozoa of infertile and fertile men. Semen samples from 10 normozoospermic patients undergoing infertility treatment and 10 fertile men were included in this study. ALSs were localised and quantified by DBD-FISH. The region most sensitive to alkali treatment in human spermatozoa was located in the basal region of the head. ALSs were more frequent in spermatozoa of infertile men than in those of fertile men. These results were confirmed by SCGE comet assays. In conclusion, the most intense localisation of hybridisation signals in human spermatozoa, representing the highest density of constitutive ALSs, was not randomly distributed and was predominantly located in the base of the head. Moreover, infertile men presented with an increase in ALS frequency. Further studies are necessary to determine the association between ALS, sperm chromatin organisation and infertility.

  4. [Effect of dimethyl sulfoxide on the extent of DNA single-strand breaks and alkali-labile sites induced by 365 nm UV-radiation in human blood lymphocyte nucleoids].

    PubMed

    Smetanina, N M; Pustovalova, M V; Osipov, A N

    2014-01-01

    It is shown that exposure of 365 nm UV radiation at doses of 10, 20 and 50 kJ/m2 induces a dose-dependent increase in DNA single-strand breaks and alkali-labile sites (SSB and ALS) detected by comet and halo assays in human blood lymphocyte nucleoids. Adding 10% dimethyl sulfoxide (DMSO) reduces the SSB and ALS yields--in 3 times. A strong drop in the output of UV-A-induced SSB and ALS in lymphocyte nucleoids in the presence of DMSO shows the leading role of *OH radicals in this DNA damage formation under exposure to 365-nm UV-radiation.

  5. Role of G-->T transversions in the mutagenicity of alkylperoxyl radicals: induction of alkali-labile sites in bacteriophage M13mp19.

    PubMed

    Harkin, L A; Butler, L M; Burcham, P C

    1997-05-01

    The mutagenicity of peroxyl radicals, ubiquitous products of lipid peroxidation, was assessed using an in vitro M13 forward mutational assay. Single-stranded M13mp19 plasmids were incubated with a range of concentrations of the azo initiator 2,2'-azobis(2-amidinopropane) hydrochloride, and then transfected into competent, SOS-induced Escherichia coli JM105 cells. Incubation with peroxyl radicals produced a concentration-dependent decrease in phage survival, with a 500 microM concentration of the azo initiator reducing the transfection efficiency by more than 90% while inducing a corresponding 6-fold increase in lacZ alpha mutation frequencies. Peroxyl radical-induced mutagenesis was completely prevented by the peroxyl radical scavenger Trolox. Automated DNA sequence analysis of the lacZ alpha gene of 100 peroxyl radical-induced mutants revealed that the most frequent sequence changes were base pair substitutions (92/95), with G-->T transversions predominating (73/92). Alkaline treatment prior to transfection diminished the mutagenicity of damaged plasmids to a level resembling that of unmodified DNA. While abasic sites might account for the sensitivity to alkaline cleavage, the possibility that unidentified nonabasic alkaline-labile lesions also contribute to peroxyl radical mutagenesis cannot be excluded. Collectively, these findings raise the possibility that DNA damage caused by a major class of endogenous radicals contributes to one of the most common spontaneous mutational events, the G-->T transversion.

  6. Further characterization of some heterophile agglutinins reacting with alkali-labile carbohydrate chains of human erythrocyte glycoproteins.

    PubMed

    Dahr, W; Uhlenbruck, G; Bird, G W

    1975-01-01

    The nature of the receptor sites for several agglutinins is characterized by hemagglutination inhibition assays. The inhibitory activity of human erythrocytes glycoproteins, from which sialic acid, sialic acid and galactose or alkali-labile oligosaccharides have been removed, is compared to the inhibitory effect of compounds with known structure. It is shown that the lectin from Arachis hypogea and anti-T bind to alkali-labile galactosyl-residues. Agglutinins from Bauhinia purpurea and variegata (non- or N-specific), Maclura aurantiaca, Iberis amara, sempervirens, umbellata hybrida and umbellata nana (M- or nonspecific), Moluccella laevis (A- plus N-specific), Helix pomatia, Helix aspersa, Helix lucorum and Caucasotachea atrolabiata interact with alkali-labile N-acetylgalactosamine. The results obtained with the anti-A agglutinins from various snails suggest that human erythrocyte glycoproteins contain, besides the alkali-labile tetrasaccharide, a peptide-linked sialyl-N-acetyl-galactosaminyl-residue. The investigations do not allow a precise definition of the receptor sites for the lectins having M- or N-specificity.

  7. Diepoxybutane induces the formation of DNA-DNA rather than DNA-protein cross-links, and single-strand breaks and alkali-labile sites in human hepatocyte L02 cells.

    PubMed

    Wen, Ying; Zhang, Pan-Pan; An, Jing; Yu, Ying-Xin; Wu, Ming-Hong; Sheng, Guo-Ying; Fu, Jia-Mo; Zhang, Xin-Yu

    2011-11-01

    1,3-Butadiene (BD) is an air pollutant and a known carcinogen. 1,2,3,4-Diepoxybutane (DEB), one of the major in vivo metabolites of BD, is considered the ultimate culprit of BD mutagenicity/carcinogenicity. DEB is a bifunctional alkylating agent, being capable of inducing the formation of monoalkylated DNA adducts and DNA cross-links, including DNA-DNA and DNA-protein cross-links (DPC). In the present study, we investigated DEB-caused DNA cross-links and breaks in human hepatocyte L02 cells using comet assay. With alkaline comet assay, it was observed that DNA migration increased with the increase of DEB concentration at lower concentrations (10-200μM); however, at higher concentrations (200-1000μM), DNA migration decreased with the increase of DEB concentration. This result indicated the presence of cross-links at >200μM, which was confirmed by the co-treatment experiments using the second genotoxic agents, tert-butyl hydroperoxide and methyl methanesulfonate. At 200μM, which appeared as a threshold, the DNA migration-retarding effect of cross-links was just observable by the co-treatment experiments. At <200μM, the effect of cross-links was too weak to be detected. The DEB-induced cross-links were determined to be DNA-DNA ones rather than DPC through incubating the liberated DNA with proteinase K prior to unwinding and electrophoresis. However, at the highest DEB concentration tested (1000μM), a small proportion of DPC could be formed. In addition, the experiments using neutral and weakly alkaline comet assays showed that DEB did not cause double-strand breaks, but did induce single-strand breaks (SSB) and alkali-labile sites (ALS). Since SSB and ALS are repaired more rapidly than cross-links, the results suggested that DNA-DNA cross-links, rather than DPC, were probably responsible for mutagenicity/carcinogenicity of DEB.

  8. UVA and visible light photons produce frank strand breaks in human P3 cell DNA as well as a new class of alkali-labile lesion

    SciTech Connect

    Peak, M.J.; Peak, J.G.

    1994-05-01

    Human P3 epithelioid cells were exposed to UVA (290--400 nm), as well as to blue and green photons in the 400--520 mm region of the spectrum, and the production of strand breaks in their DNA was measured by using elution. After exposure to blue photons the profiles were convex (downturning), shown to be due to the induction of a mixture of frank single-strand DNA breaks (SSB) plus rapidly developing alkali-labile sites (ALS). as well as latent breaks that develop during the first 6 h of the elution, termed slowly developing alkali-labile sites (SDALS). A significant proportion of the lesions produced by P3 cells by blue light photons are SDALS, whereas green light photons at 520 nm and UVA photons at 365 nm produce no SDALS and the elution profiles are exponential. This is also the case for Chinese hamster ovary cells exposed to 405 nm, evidence that a unique chromophore in P3 cells that absorbs strongly in the blue region leads to the formation of SDALS. The similarity in induction of SDALS at 460 and 405 nm is evidence that the chromophore is not a porphyrin, because these compounds have sharp absorption maxima in the lower 400 nm region. The chemical nature of these lesions as well as the cellular responses to them remain enigmatic.

  9. Determination of alkali-labile phosphoprotein phosphorus from fish plasma using the Tb(3+)-tiron complex as a fluorescence probe.

    PubMed

    Lv, Xue-Fei; Zhao, Yi-Bing; Zhou, Qun-Fang; Jiang, Gui-Bin; Song, Mao-Yong

    2007-01-01

    A sensitive method based on the fluorescence quenching effect of the Tb(3+)-Tiron complex is proposed for the determination of alkali-labile phosphoprotein phosphorus (ALP) released from fish plasma. The detection limit was 5.4 ng/ml (S/N = 2), and the relative standard deviation of the quenching effect (6 replicates) was 4.6%. The results obtained by the proposed method were in good agreement with those obtained by the colorimetric assay. The advantages of the present method are its relatively simple detection procedure, the lack of toxic organic solvents, and high sensitivity.

  10. Radiation-induced heat-labile sites that convert into DNA double-strand breaks

    NASA Technical Reports Server (NTRS)

    Rydberg, B.; Chatterjee, A. (Principal Investigator)

    2000-01-01

    The yield of DNA double-strand breaks (DSBs) in SV40 DNA irradiated in aqueous solution was found to increase by more than a factor of two as a result of postirradiation incubation of the DNA at 50 degrees C and pH 8.0 for 24 h. This is in agreement with data from studies performed at 37 degrees C that were published previously. Importantly, similar results were also obtained from irradiation of mammalian DNA in agarose plugs. These results suggest that heat-labile sites within locally multiply damaged sites are produced by radiation and are subsequently transformed into DSBs. Since incubation at 50 degrees C is typically employed for lysis of cells in commonly used pulsed-field gel assays for detection of DSBs in mammalian cells, the possibility that heat-labile sites are present in irradiated cells was also studied. An increase in the apparent number of DSBs as a function of lysis time at 50 degrees C was found with kinetics that was similar to that for irradiated DNA, although the magnitude of the increase was smaller. This suggests that heat-labile sites are also formed in the cell. If this is the case, a proportion of DSBs measured by the pulsed-field gel assays may occur during the lysis step and may not be present in the cell as breaks but as heat-labile sites. It is suggested that such sites consist mainly of heat-labile sugar lesions within locally multiply damaged sites. Comparing rejoining of DSBs measured with short and long lysis procedure indicates that the heat-labile sites are repaired with fast kinetics in comparison with repair of the bulk of DSBs.

  11. Characterization of a labile naloxone binding site (lambda site) in rat brain.

    PubMed

    Grevel, J; Yu, V; Sadée, W

    1985-05-01

    A high-affinity binding site selective for naloxone and other 4,5-epoxymorphinans (lambda site) has been previously described in rat brain. Following homogenization of freshly dissected brain, the lambda sites convert from a high-affinity to a low-affinity state. When measured with [3H]naloxone, the decay is very rapid at 20 degrees C (t 1/2 less than 2 min), whereas it is progressively slowed at lower temperatures. Proteinase inhibitors, antoxidants, and sulfhydryl group-protecting agents failed to prevent this conversion. Kinetic measurements of mu and lambda binding at varying temperatures demonstrated that the decrease in lambda binding does not coincide with the concurrent increase in mu binding and that the loss of high-affinity lambda binding at 20 degrees C can be partially restored when the temperature is lowered to 0 degrees C. The low-affinity state of the lambda site is rather stable in the Tris buffer homogenates and is susceptible to digestion by a protease. The (-)-isomer of WIN 44,441, a benzomorphan drug, binds to lambda sites with moderate affinity (dissociation constant, KD = 63 nM), whereas the (+)-isomer does not (KD greater than 10,000 nM), thus establishing stereoselectivity of the binding process. Neither the high-affinity nor the low-affinity state of lambda binding is significantly affected by the presence of 100 mM sodium chloride or 50 microM Gpp(NH)p, (a GTP analog), which is in contrast to the dramatic effect of these agents on the established opioid receptor system. Naltrexone, naloxone, nalorphine, and morphine (in this order of decreasing potency) bind to the lambda site in vivo in intact rat brain over dosage ranges that are commonly employed in pharmacological studies.

  12. Process for carbonaceous material conversion and recovery of alkali metal catalyst constituents held by ion exchange sites in conversion residue

    DOEpatents

    Sharp, David W.

    1980-01-01

    In a coal gasification operation or similar conversion process carried out in the presence of an alkali metal-containing catalyst wherein solid particles containing alkali metal residues are produced, alkali metal constituents are recovered for the particles by contacting or washing them with an aqueous solution containing calcium or magnesium ions in an alkali metal recovery zone at a low temperature, preferably below about 249.degree. F. During the washing or leaching process, the calcium or magnesium ions displace alkali metal ions held by ion exchange sites in the particles thereby liberating the ions and producing an aqueous effluent containing alkali metal constituents. The aqueous effluent from the alkali metal recovery zone is then recycled to the conversion process where the alkali metal constituents serve as at least a portion of the alkali metal constituents which comprise the alkali metal-containing catalyst.

  13. Development of biomarkers of stress related to endocrine disruption in gastropods: alkali-labile phosphates, protein-bound lipids and vitellogenin-like proteins.

    PubMed

    Gagnaire, Beatrice; Gagné, François; André, Chantale; Blaise, Christian; Abbaci, Khedidja; Budzinski, Hélène; Dévier, Marie-Hélène; Garric, Jeanne

    2009-05-05

    The occurrence in aquatic environments of compounds capable of acting as endocrine disruptors (ED) is of concern for wildlife. Elevated levels of the egg-yolk precursor protein vitellogenin (Vg) are widely accepted as a biomarker for xenoestrogen exposure in aquatic organisms. The purpose of this study was to develop a method for tracking changes in levels of Vg-like proteins in gastropods. Vg-like and egg-yolk proteins were analyzed in three freshwater gastropods having different modes of reproduction: Potamopyrgus antipodarum (asexual reproduction), Valvata piscinalis (hermaphroditism) and Lithoglyphus naticoides (sexual reproduction). Vitellogenin-like protein levels were examined by the alkali-labile phosphate (ALP) technique, a novel protein-bound lipid (PBL) assay, and by gradient gel electrophoresis with silver staining. The first phase of the study was dedicated to the development and optimization of an analytical method for detecting Vg-like proteins in these three gastropod species. In the second phase, the snails P. antipodarum and V. piscinalis were exposed to bisphenol A (BPA), octylphenol (OP) and tributyltin (TBT) for 14 and 28 days. Vg-like proteins were resolved in one major band at 250-300 kDa for L. naticoides and V. piscinalis and in two bands at 100 and 30 kDa for P. antipodarum. After 14 days of exposure, all techniques showed an increase in Vg-like protein levels at 100 microg/L BPA and at 1 microg/L OP in P. antipodarum. A decrease in these proteins was observed with high concentrations of OP (100 microg/L) and TBT (>or=5 ng/L). In V. piscinalis, a decrease in Vg-like proteins was shown after 14 days of exposure for OP >or=10 microg/L and TBT >or=5 ng/L; however, at 28 days, gel electrophoresis revealed an increase in these proteins. Histological observations showed significant necrosis in ovotestes of V. piscinalis with the three endocrine-disrupting compounds, while tissue modifications were not detected for P. antipodarum. A method for

  14. Induction of heat-labile sites in DNA of mammalian cells by the antitumor alkylating drug CC-1065

    SciTech Connect

    Zsido, T.J.; Woynarowski, J.M.; Baker, R.M.; Gawron, L.S.; Beerman, T.A. )

    1991-04-16

    CC-1065 is a very potent antitumor antibiotic capable of covalent and noncovalent binding to the minor groove of naked DNA. Upon thermal treatment, covalent adducts formed between CC-1065 and DNA generate strand break. The authors have shown that this molecular damage can be detected following CC-1065 treatment of mammalian whole cells. Using alkaline sucrose gradient analysis, They observe thermally induced breakage of ({sup 14}C)thymidine-prelabeled DNA from drug-treated African green monkey kidney BSC-1 cells. Very little damage to cellular DNA by CC-1065 can be detected without first heating the drug-treated samples. CC-1065 can also generate heat-labile sites within DNA during cell lysis and heating, subsequent to the exposure of cells to drug, suggesting that a pool of free and noncovalently bound drug is available for posttreatment adduct formation. This effect was controlled for by mixing ({sup 3}H)thymidine-labeled untreated cells with the ({sup 14}C)thymidine-labeled drug-treated samples. The lowest drug dose at which heat-labile sites were detected was 3 nM CC-1065 (3 single-stranded breaks/10{sup 6} base pairs). This concentration reduced survival of BSC-1 cells to 0.1% in cytotoxicity assays. The generation of CC-1065-induced lesions in cellular DNA is time dependent (the frequency of lesions caused by a 60 nM treatment reaching a plateau at 2 h) and is not readily reversible. The results of this study demonstrate that CC-1065 does generate heat-labile sites with the cellular DNA of intact cells and suggest that a mechanism of cytotoxic action of CC-1065 involves formation of covalent adducts to DNA.

  15. Repair of radiation-induced heat-labile sites is independent of DNA-PKcs, XRCC1 or PARP

    SciTech Connect

    Stenerlöw, Bo; Karlsson, Karin H.; Radulescu, Irina; Rydberg, Bjorn; Stenerlow, Bo

    2008-04-29

    Ionizing radiation induces a variety of different DNA lesions: in addition to the most critical DNA damage, the DSB, numerous base alterations, SSBs and other modifications of the DNA double-helix are formed. When several non-DSB lesions are clustered within a short distance along DNA, or close to a DSB, they may interfere with the repair of DSBs and affect the measurement of DSB induction and repair. We have previously shown that a substantial fraction of DSBs measured by pulsed-field gel electrophoresis (PFGE) are in fact due to heat-labile sites (HLS) within clustered lesions, thus reflecting an artifact of preparation of genomic DNA at elevated temperature. To further characterize the influence of HLS on DSB induction and repair, four human cell lines (GM5758, GM7166, M059K, U-1810) with apparently normal DSB rejoining were tested for bi-phasic rejoining after gamma irradiation. When heat-released DSBs were excluded from the measurements the fraction of fast rejoining decreased to less than 50% of the total. However, neither the half-times of the fast (t{sub 1/2} = 7-8 min) or slow (t{sub 1/2} = 2.5 h) DSB rejoining were changed significantly. At t=0 the heat-released DSBs accounted for almost 40% of the DSBs, corresponding to 10 extra DSB/cell/Gy in the initial DSB yield. These heat-released DSBs were repaired within 60-90 min in all tested cells, including M059K cells treated with wortmannin or DNA-PKcs defect M059J cells. Furthermore, cells lacking XRCC1 or Poly(ADP-ribose) polymerase-1 (PARP-1) rejoined both total DSBs and heat-released DSBs similar to normal cells. In summary, the presence of heat-labile sites have a substantial impact on DSB induction yields and DSB rejoining rates measured by pulsed-field gel electrophoresis, and HLS repair is independent of DNA-PKcs, XRCC1 and PARP.

  16. Oxidation of guanine in G, GG, and GGG sequence contexts by aromatic pyrenyl radical cations and carbonate radical anions: relationship between kinetics and distribution of alkali-labile lesions.

    PubMed

    Lee, Young Ae; Durandin, Alexander; Dedon, Peter C; Geacintov, Nicholas E; Shafirovich, Vladimir

    2008-02-14

    Oxidatively generated DNA damage induced by the aromatic radical cation of the pyrene derivative 7,8,9,10-tetrahydroxytetrahydrobenzo[a]pyrene (BPT), and by carbonate radicals anions, was monitored from the initial one-electron transfer, or hole injection step, to the formation of hot alkali-labile chemical end-products monitored by gel electrophoresis. The fractions of BPT molecules bound to double-stranded 20-35-mer oligonucleotides with noncontiguous guanines G and grouped as contiguous GG and GGG sequences were determined by a fluorescence quenching method. Utilizing intense nanosecond 355 nm Nd:YAG laser pulses, the DNA-bound BPT molecules were photoionized to BPT*+ radicals by a consecutive two-photon ionization mechanism. The BPT*+ radicals thus generated within the duplexes selectively oxidize guanine by intraduplex electron-transfer reactions, and the rate constants of these reactions follow the trend 5'-..GGG.. > 5'-..GG.. > 5'-..G... In the case of CO3*- radicals, the oxidation of guanine occurs by intermolecular collision pathways, and the bimolecular rate constants are independent of base sequence context. However, the distributions of the end-products generated by CO3*- radicals, as well as by BPT*+, are base sequence context-dependent and are greater than those in isolated guanines at the 5'-G in 5'-...GG... sequences, and the first two 5'- guanines in the 5'-..GGG sequences. These results help to clarify the conditions that lead to a similar or different base sequence dependence of the initial hole injection step and the final distribution of oxidized, alkali-labile guanine products. In the case of the intermolecular one-electron oxidant CO3*-, the rate constant of hole injection is similar for contiguous and isolated guanines, but the subsequent equilibration of holes by hopping favors trapping and product formation at contiguous guanines, and the sequence dependence of these two phenomena are not correlated. In contrast, in the case of the DNA

  17. CD44 Binding to Hyaluronic Acid Is Redox Regulated by a Labile Disulfide Bond in the Hyaluronic Acid Binding Site

    PubMed Central

    Kellett-Clarke, Helena; Stegmann, Monika; Barclay, A. Neil; Metcalfe, Clive

    2015-01-01

    CD44 is the primary leukocyte cell surface receptor for hyaluronic acid (HA), a component of the extracellular matrix. Enzymatic post translational cleavage of labile disulfide bonds is a mechanism by which proteins are structurally regulated by imparting an allosteric change and altering activity. We have identified one such disulfide bond in CD44 formed by Cys77 and Cys97 that stabilises the HA binding groove. This bond is labile on the surface of leukocytes treated with chemical and enzymatic reducing agents. Analysis of CD44 crystal structures reveal the disulfide bond to be solvent accessible and in the–LH hook configuration characteristic of labile disulfide bonds. Kinetic trapping and binding experiments on CD44-Fc chimeric proteins show the bond is preferentially reduced over the other disulfide bonds in CD44 and reduction inhibits the CD44-HA interaction. Furthermore cells transfected with CD44 no longer adhere to HA coated surfaces after pre-treatment with reducing agents. The implications of CD44 redox regulation are discussed in the context of immune function, disease and therapeutic strategies. PMID:26379032

  18. Bacillus thuringiensis subsp. kurstaki HD1 as a factory to synthesize alkali-labile ChiA74∆sp chitinase inclusions, Cry crystals and spores for applied use

    PubMed Central

    2014-01-01

    . Conclusions Alkali-labile ChiA74∆sp inclusion bodies can be synthesized in E. coli and B. thuringiensis strains. We demonstrated for the first time the applied utility of synthesis of ChiA74∆sp inclusions, Cry crystals and spores in the same sporangium of HD1, a strain used successfully worldwide to control economically significant lepidopteran pests of agriculture. Our findings will allow to us develop strategies to modify expression of ChiA74∆sp while maximizing Cry crystal synthesis in commercial strains of B. thuringiensis. PMID:24460864

  19. Contrasting microbial functional genes in two distinct saline-alkali and slightly acidic oil-contaminated sites.

    PubMed

    Liang, Yuting; Zhao, Huihui; Zhang, Xu; Zhou, Jizhong; Li, Guanghe

    2014-07-15

    To compare the functional gene structure and diversity of microbial communities in saline-alkali and slightly acidic oil-contaminated sites, 40 soil samples were collected from two typical oil exploration sites in North and South China and analyzed with a comprehensive functional gene array (GeoChip 3.0). The overall microbial pattern was significantly different between the two sites, and a more divergent pattern was observed in slightly acidic soils. Response ratio was calculated to compare the microbial functional genes involved in organic contaminant degradation and carbon, nitrogen, phosphorus, and sulfur cycling. The results indicated a significantly low abundance of most genes involved in organic contaminant degradation and in the cycling of nitrogen and phosphorus in saline-alkali soils. By contrast, most carbon degradation genes and all carbon fixation genes had similar abundance at both sites. Based on the relationship between the environmental variables and microbial functional structure, pH was the major factor influencing the microbial distribution pattern in the two sites. This study demonstrated that microbial functional diversity and heterogeneity in oil-contaminated environments can vary significantly in relation to local environmental conditions. The limitation of nitrogen and phosphorus and the low degradation capacity of organic contaminant should be carefully considered, particularly in most oil-exploration sites with saline-alkali soils.

  20. Organochlorine compounds in Purple Heron eggs (Ardea purpurea) nesting in sites located around a chlor-alkali plant (Ebro River).

    PubMed

    Huertas, David; Grimalt, Joan O; Jover, Lluís; Sanpera, Carola; Ruiz, Xavier

    2016-01-01

    Eggs of Purple Heron (Ardea purpurea) were collected from three sampled sites inside the Ebro River basin in years 2006 and 2007. These sites were located besides (Flix), upstream (Aiguabarreig) and downstream (Delta) a chlor-alkali plant. Organochlorine compounds (OCs) such as dichlorodiphenyltrichloroethanes (DDTs), polychlorobiphenyls (PCBs), polychlorostyrenes (PCSs), hexachlorobenzene (HCB), pentachlorobenzene (PeCB) and hexachlorocyclohexanes (HCHs) were analysed to assess what are the accumulation patterns of these compounds in aquatic migratory birds breeding in the area of influence of the emissions from this industrial installation. Comparison of the egg concentrations between the three sites show higher concentrations of compounds manufactured in the past in the factory (PCBs, p,p'-DDT) or by-products of OC synthesis (HCB, PeCB and PCSs) in Flix than in Aiguabarreig reflecting a clear influence from the emissions of the chlor-alkali plant. The eggs collected in the Ebro Delta showed higher concentrations of total DDTs (mainly p,p'-DDE) than in the reference site (Aiguabarreig) which could reflect past applications of this insecticide in the area for agriculture. In contrast, HCHs were found in higher concentrations in the Delta and Aiguabarreig than in the Flix Reservoir. These compounds have been used as insecticides in agriculture and were not manufactured in the chlor-alkali plant. The present results show that despite Purple Herons are migratory birds, the food web transfer of OCs during the breeding season is sufficient for the accumulation of these compounds in the eggs, leading to statistically significant concentration differences between sites. These differences are consistent with the emissions of these pollutants from industrial or agricultural sources to the aquatic environments. Some of the p,p'-DDE concentrations observed in the area nearby the chlor-alkali plant are above the threshold effects for reproductive impairment.

  1. Mechanism of the alkali degradation of (6-4) photoproduct-containing DNA.

    PubMed

    Arichi, Norihito; Inase, Aki; Eto, Sachise; Mizukoshi, Toshimi; Yamamoto, Junpei; Iwai, Shigenori

    2012-03-21

    The (6-4) photoproduct is one of the major damaged bases produced by ultraviolet light in DNA. This lesion is known to be alkali-labile, and strand breaks occur at its sites when UV-irradiated DNA is treated with hot alkali. We have analyzed the product obtained by the alkali treatment of a dinucleoside monophosphate containing the (6-4) photoproduct, by HPLC, NMR spectroscopy, and mass spectrometry. We previously found that the N3-C4 bond of the 5' component was hydrolyzed by a mild alkali treatment, and the present study revealed that the following reaction was the hydrolysis of the glycosidic bond at the 3' component. The sugar moiety of this component was lost, even when a 3'-flanking nucleotide was not present. Glycosidic bond hydrolysis was also observed for a dimer and a trimer containing 5-methyl-2-pyrimidinone, which was used as an analog of the 3' component of the (6-4) photoproduct, and its mechanism was elucidated. Finally, the alkali treatment of a tetramer, d(GT(6-4)TC), yielded 2'-deoxycytidine 5'-monophosphate, while 2'-deoxyguanosine 3'-monophosphate was not detected. This result demonstrated the hydrolysis of the glycosidic bond at the 3' component of the (6-4) photoproduct and the subsequent strand break by β-elimination. It was also shown that the glycosidic bond at the 3' component of the Dewar valence isomer was more alkali-labile than that of the (6-4) photoproduct.

  2. Analysis of Heat-Labile Sites Generated by Reactions of Depleted Uranium and Ascorbate in Plasmid DNA

    PubMed Central

    Wilson, Janice; Young, Ashley; Civitello, Edgar R.

    2013-01-01

    The goal of this study was to characterize how depleted uranium (DU) causes DNA damage. Procedures were developed to assess the ability of organic and inorganic DNA adducts to convert to single strand breaks (SSB) in pBR322 plasmid DNA in the presence of heat or piperidine. DNA adducts formed by methyl methanesulfonate (MMS), cis-platin (cis-Pt), and chromic chloride were compared to those formed by reaction of uranyl acetate (UA) and ascorbate (Asc). Uranyl ion in the presence of Asc produced U-DNA adducts that converted to SSB upon heating. Piperidine, which acted on DNA methylated by MMS to convert methyl-DNA adducts to SSB, served in the opposite fashion with U-DNA adducts by decreasing SSB. The observation that piperidine also decreased the gel shift for metal-DNA adducts formed by monofunctional cis-Pt and chromic chloride was interpreted to suggest that piperidine served to remove U-DNA adducts. Radical scavengers did not affect formation of U-induced SSB, suggesting that SSB arose from the presence of U-DNA adducts and not from free radicals. A model is proposed to predict how U-DNA adducts may serve as initial lesions that convert to SSB or AP sites. Results suggest that DU can act as a chemical genotoxin that does not require radiation for its mode of action. Characterizing the DNA lesions formed by DU is necessary to assess the relative importance of different DNA lesions in the formation of DU-induced mutations. Understanding mechanisms of formation of DU-induced mutations may contribute to identification of biomarkers of DU exposures in humans. PMID:24218036

  3. Influence of a chlor-alkali superfund site on mercury bioaccumulation in periphyton and low-trophic level fauna.

    PubMed

    Buckman, Kate L; Marvin-DiPasquale, Mark; Taylor, Vivien F; Chalmers, Ann; Broadley, Hannah J; Agee, Jennifer; Jackson, Brian P; Chen, Celia Y

    2015-07-01

    In Berlin, New Hampshire, USA, the Androscoggin River flows adjacent to a former chlor-alkali facility that is a US Environmental Protection Agency Superfund site and source of mercury (Hg) to the river. The present study was conducted to determine the fate and bioaccumulation of methylmercury (MeHg) to lower trophic-level taxa in the river. Surface sediment directly adjacent to the source showed significantly elevated MeHg (10-40× increase, mean ± standard deviation [SD]: 20.1 ± 24.8 ng g(-1) dry wt) and total mercury (THg; 10-30× increase, mean ± SD: 2045 ± 2669 ng g(-1) dry wt) compared with all other reaches, with sediment THg and MeHg from downstream reaches elevated (3-7× on average) relative to the reference (THg mean ± SD: 33.5 ± 9.33 ng g(-1) dry wt; MeHg mean ± SD: 0.52 ± 0.21 ng g(-1) dry wt). Water column THg concentrations adjacent to the point source for both particulate (0.23 ng L(-1)) and dissolved (0.76 ng L(-1)) fractions were 5-fold higher than at the reference sites, and 2-fold to 5-fold higher than downstream. Methylmercury production potential of periphyton material was highest (2-9 ng g(-1) d(-1) dry wt) adjacent to the Superfund site; other reaches were close to or below reporting limits (0. 1 ng g(-1) d(-1) dry wt). Total Hg and MeHg bioaccumulation in fauna was variable across sites and taxa, with no clear spatial patterns downstream of the contamination source. Crayfish, mayflies, and shiners showed a weak positive relationship with porewater MeHg concentration.

  4. INFLUENCE OF A CHLOR-ALKALI SUPERFUND SITE ON MERCURY BIOACCUMULATION IN PERIPHYTON AND LOW-TROPHIC LEVEL FAUNA

    PubMed Central

    Buckman, Kate L.; Marvin-DiPasquale, Mark; Taylor, Vivien F.; Chalmers, Ann; Broadley, Hannah J.; Agee, Jennifer; Jackson, Brian P.; Chen, Celia Y.

    2015-01-01

    In Berlin, NH, the Androscoggin River flows adjacent to a former chlor-alkali facility that is a US EPA Superfund site and source of mercury (Hg) to the river. A study was conducted to determine the fate and bioaccumulation of methylmercury (MeHg) to lower trophic-level taxa in the river. Surface sediment directly adjacent to the source showed significantly elevated MeHg (10–40x increase, mean±sd: 20.1±24.8 ng g−1 DW) and total mercury (THg, 10–30x increase, mean±sd: 2045±2669 ng g−1 DW) compared to all other reaches, with sediment THg and MeHg from downstream reaches elevated (3–7x on average) relative to the reference (THg mean±sd: 33.5±9.33 ng g−1 DW; MeHg mean±sd: 0.52±0.21 ng g−1 DW). Water column THg concentrations adjacent to the point source for both particulate (0.23 ng L−1) and dissolved (0.76 ng L−1) fractions were 5-fold higher than at the reference sites, and 2–5-fold higher than downstream. Methylmercury production potential (MPP) of periphyton material was highest (2–9 ng g−1 d−1 DW) adjacent to the Superfund site; other reaches were close to or below reporting limits (0. 1 ng g−1 d−1 DW). Total Hg and MeHg bioaccumulation in fauna was variable across sites and taxa, with no clear spatial patterns downstream of the contamination source. Crayfish, mayflies and shiners showed a weak positive relationship with porewater MeHg concentration. PMID:25732794

  5. Alkali element enrichments on the BABBs at the IODP Expedition 333 Site C0012 in the northern Shikoku Basin

    NASA Astrophysics Data System (ADS)

    Haraguchi, S.; Nakamura, K.; Fujinaga, K.

    2015-12-01

    The Shikoku Basin is a back arc basin located westside of the Izu-Ogasawara (Bonin) arc, spreading was from 25 to 15 Ma. The drilling of the DSDP, ODP and IODP recovered the backarc basin basalt (BABB) of the Shikoku Basin. Site C0012, south of the Kii Peninsula, was operated during the IODP Exp 333, and BABB was recovered 100m thickness under the 520m of sediment. This BABB is divided into upper aphyric pillow (Unit 1) and lower massive flow (Unit 2) divided at the 560 mbsf, and show variable degree of alteration, clay mineral and zeolite depositions. SiO2 and MgO contents of these basalts are 47-55 and 5-8 wt%. These basalts show wide variation of enrichment of alkali elements, 2.3-7.5 and 0.4-4.2 wt% of Na2O and K2O. Na2O+K2O contents show 3.2-8.0 wt%, and 2 wt% higher trends than other BABBs in the Shikoku Basin at the same SiO2 contents. Na2O and K2O show proportional and anti-proportional trends with increasing LOI. Therefore, both alkali element enrichments in these rocks are caused by secondary mineralization, and host phase of Na2O is hydrous and that of K2O is anhydrous minerals. Secondary mineral phases was mainly identified by XRD. The identified host phases of Na are analcime and thomsonite. Analcime is observed in rocks of more than 4 wt% of Na2O. Chlorite and smectite are identified to clay minerals. This mineral assemblage indicates the high-temperature zeolite facies alteration. The host phases of K are mainly identified into K-feldspar. We assume that secondary mineralization of K-fd is associated with low-temperature albitization. Compared to the lithostratigraphy, the Na enrichment is prominent in the Unit 1 and upper 20 m of the Unit 2, and the K enrichment is prominent in lower part of the Unit 2. We consider that the Na enrichment associated with zeolite depositions occurred under high water/rock ratio with active hydrothermal circulation because of high water permeability of pillow lava, and K enrichment associated with albitization occurred

  6. Isomer-specific analysis and toxic evaluation of polychlorinated naphthalenes in soil, sediment, and biota collected near the site of a former chlor-alkali plant

    SciTech Connect

    Kannan, K.; Blankenship, A.L.; Giesy, J.P.; Imagawa, T.

    1998-09-01

    Concentrations and composition of polychlorinated naphthalene (PCN) congeners were determined in soil, sediments, blue crab, striped mullet, and boat-tailed grackle collected near a chlor-alkali plant to determine their congener profile, bioaccumulation properties, and toxic potential. Concentrations of total PCNs as high as 23 {micro}g/g, dry wt, were found in sediments collected at the marsh contaminated by disposal of wastes from the chlor-alkali process. The spatial distribution of sediment-PCN concentrations was not related with those observed for polychlorinated biphenyls (PCBs). The PCN congener profile did not resemble those of any technical mixtures. Hepta- and octa-chloronaphthalenes were the most abundant congeners accounting for greater than 50% of the total PCN concentrations in soil and sediments. A characteristic profile of PCNs in samples collected at the chlor-alkali site suggests the formation of chloronaphthalene congeners during chlor-alkali process, as has been suggested for polychlorinated dibenzofurans (PCDFs). Concentrations of total PCNs in biota were 3--5 orders of magnitude less than in sediments. The profile of PCN congeners in biota was predominated by tetra- or penta-chloronaphthalenes, while hepta- and octa-chloronaphthalenes were not detected.

  7. Influence of a chlor-alkali superfund site on mercury bioaccumulation in periphyton and low-trophic level fauna

    USGS Publications Warehouse

    Buckman, Kate L.; Marvin-DiPasquale, Mark C.; Taylor, Vivien F.; Chalmers, Ann T.; Broadley, Hannah J.; Agee, Jennifer L.; Jackson, Brian P.; Chen, Celia Y.

    2015-01-01

    In Berlin, New Hampshire, USA, the Androscoggin River flows adjacent to a former chlor-alkali facility that is a US Environmental Protection Agency Superfund site and source of mercury (Hg) to the river. The present study was conducted to determine the fate and bioaccumulation of methylmercury (MeHg) to lower trophic-level taxa in the river. Surface sediment directly adjacent to the source showed significantly elevated MeHg (10–40× increase, mean ± standard deviation [SD]: 20.1 ± 24.8 ng g–1 dry wt) and total mercury (THg; 10–30× increase, mean ± SD: 2045 ± 2669 ng g–1 dry wt) compared with all other reaches, with sediment THg and MeHg from downstream reaches elevated (3–7× on average) relative to the reference (THg mean ± SD: 33.5 ± 9.33 ng g–1 dry wt; MeHg mean ± SD: 0.52 ± 0.21 ng g–1 dry wt). Water column THg concentrations adjacent to the point source for both particulate (0.23 ng L–1) and dissolved (0.76 ng L–1) fractions were 5-fold higher than at the reference sites, and 2-fold to 5-fold higher than downstream. Methylmercury production potential of periphyton material was highest (2–9 ng g–1 d–1 dry wt) adjacent to the Superfund site; other reaches were close to or below reporting limits (0. 1 ng g–1 d–1 dry wt). Total Hg and MeHg bioaccumulation in fauna was variable across sites and taxa, with no clear spatial patterns downstream of the contamination source. Crayfish, mayflies, and shiners showed a weak positive relationship with porewater MeHg concentration.

  8. MEASUREMENT OF TOTAL SITE MERCURY EMISSIONS FROM A CHLOR-ALKALI PLANT USING OPEN-PATH UV-DOAS

    EPA Science Inventory

    In December 2003, the EPA promulgated the National Emission Standard for Hazardous Air Pollutants for mercury cell chlor-alkali plants. In February 2004, the Natural Resources Defense Council filed petitions on the final rule in U.S. district court citing, among other issues, th...

  9. Localization of the labile disulfide bond between SU and TM of the murine leukemia virus envelope protein complex to a highly conserved CWLC motif in SU that resembles the active-site sequence of thiol-disulfide exchange enzymes.

    PubMed Central

    Pinter, A; Kopelman, R; Li, Z; Kayman, S C; Sanders, D A

    1997-01-01

    Previous studies have indicated that the surface (SU) and transmembrane (TM) subunits of the envelope protein (Env) of murine leukemia viruses (MuLVs) are joined by a labile disulfide bond that can be stabilized by treatment of virions with thiol-specific reagents. In the present study this observation was extended to the Envs of additional classes of MuLV, and the cysteines of SU involved in this linkage were mapped by proteolytic fragmentation analyses to the CWLC sequence present at the beginning of the C-terminal domain of SU. This sequence is highly conserved across a broad range of distantly related retroviruses and resembles the CXXC motif present at the active site of thiol-disulfide exchange enzymes. A model is proposed in which rearrangements of the SU-TM intersubunit disulfide linkage, mediated by the CWLC sequence, play roles in the assembly and function of the Env complex. PMID:9311907

  10. Evidence for New Excess Electron Localization Sites in Na{sub {ital n}}F{sub {ital n}{minus}1 } Alkali-Halide Clusters

    SciTech Connect

    Durand, G.; Spiegelmann, F.; Labastie, P.; LHermite, J.; Poncharal, P.

    1997-07-01

    This Letter examines new types of localization sites for an excess electron in finite alkali-halide clusters resulting from defects on cuboidal structures, namely {open_quotes}edge states,{close_quotes} R center, and other surface defects. We present theoretical calculations on Na{sub n}F {sub n{minus}1} clusters with one excess electron. Comparisons with experimental results are presented for different cluster sizes (n=17 , 23, 28, and 29). Structures with edge or surface defects are relevant for n=23 , 28, and 29. {copyright} {ital 1997} {ital The American Physical Society}

  11. Highly labile elements. [in meteorites

    NASA Technical Reports Server (NTRS)

    Lipschutz, Michael E.; Woolum, Dorothy S.

    1988-01-01

    Certain elements of high lability are very responsive to thermal processes, being either highly volatile during primary nebular condensation or highly mobile by postaccretionary metamorphic or shock heating. Data for highly labile elements indicate that different thermal processes were important in the genesis of each of the chondritic groups and a discussion of each is given. Contents of highly labile elements in a given group of contemporary falls differ from those of the same group that fell in Antarctica more than 0.1 Myr ago. This difference is due either to a time-dependent change in meteorite sources or, less likely, orbital variation of the meteorite flux to Earth.

  12. Analyzing relationships between surface perturbations and local chemical reactivity of metal sites: Alkali promotion of O2 dissociation on Ag(111)

    NASA Astrophysics Data System (ADS)

    Xin, Hongliang; Linic, Suljo

    2016-06-01

    Many commercial heterogeneous catalysts are complex structures that contain metal active sites promoted by multiple additives. Developing fundamental understanding about the impact of these perturbations on the local surface reactivity is crucial for catalyst development and optimization. In this contribution, we develop a general framework for identifying underlying mechanisms that control the changes in the surface reactivity of a metal site (more specifically the adsorbate-surface interactions) upon a perturbation in the local environment. This framework allows us to interpret fairly complex interactions on metal surfaces in terms of specific, physically transparent contributions that can be evaluated independently of each other. We use Cs-promoted dissociation of O2 as an example to illustrate our approach. We concluded that the Cs adsorbate affects the outcome of the chemical reaction through a strong alkali-induced electric field interacting with the static dipole moment of the O2/Ag(111) system.

  13. Analyzing relationships between surface perturbations and local chemical reactivity of metal sites: Alkali promotion of O2 dissociation on Ag(111).

    PubMed

    Xin, Hongliang; Linic, Suljo

    2016-06-21

    Many commercial heterogeneous catalysts are complex structures that contain metal active sites promoted by multiple additives. Developing fundamental understanding about the impact of these perturbations on the local surface reactivity is crucial for catalyst development and optimization. In this contribution, we develop a general framework for identifying underlying mechanisms that control the changes in the surface reactivity of a metal site (more specifically the adsorbate-surface interactions) upon a perturbation in the local environment. This framework allows us to interpret fairly complex interactions on metal surfaces in terms of specific, physically transparent contributions that can be evaluated independently of each other. We use Cs-promoted dissociation of O2 as an example to illustrate our approach. We concluded that the Cs adsorbate affects the outcome of the chemical reaction through a strong alkali-induced electric field interacting with the static dipole moment of the O2/Ag(111) system.

  14. Post-depositional memory record of mercury in sediment near the effluent disposal site of a chlor-alkali plant in Thane Creek-Mumbai Harbour, India.

    PubMed

    Rama, Anirudh; Rokade, M A; Zingde, D; Boroleb, D V

    2009-07-01

    A mercury-cell chlor-alkali plant, operating for 40 years at Airoli (eastern bank of Thane Creek), India, has caused widespread contamination of the surrounding environment. Untreated wastewater from the plant was discharged to Thane Creek for several years. Thane Creek joins the Ulhas Estuary by a narrow arm and opens to the Arabian Sea through Mumbai Harbour. The Ulhas Estuary is impacted by mercury (Hg) released from several industries including two chlor-alkali industries. In order to understand the historical record of anthropogenic Hg and its association to Al, Fe and total organic carbon (TOC), estimation of Hg, Al, Fe and TOC was made in surface sediments and cores from Thane Creek-Mumbai Harbour and the adjacent coastal area. Though 70% of the chlor-alkali plant has been changed to membrane cell technology, surficial sediment in the vicinity of effluent release contains a high concentration (up to 1.19 microg g(-1) dry wt) of Hg compared with its background value (0.10 microg g(-1) dry wt). The contaminated creek sediments are prone to current-driven resuspension and are acting as a strong source of Hg to the sediment of the coastal region. Several rocks and sediments from the catchment area were analysed to find out the natural background level of Hg. A high suspended load transported from the catchment region provides natural dilution to the Hg-contaminated sediment of the Bay. Lithogenic and anthropogenic Hg buried in marine sediments is quantified based on normalization with Al, Fe and TOC, and inter-comparisons of the results indicate comparable values obtained by using Al and Fe, while discernible deviations are found when normalization is carried out using TOC. The Hg profile in the core, from the effluent release site for which sedimentation rate has been established, is discussed in terms of the progressive removal of Hg from the effluent after the mid-1970s and partial changeover of the manufacturing process from Hg cell to membrane cell

  15. Site-isolated luminescent europium complexes with polyester macroligands: metal-centered heteroarm stars and nanoscale assemblies with labile block junctions.

    PubMed

    Bender, Jessica L; Corbin, Perry S; Fraser, Cassandra L; Metcalf, David H; Richardson, Frederick S; Thomas, Edwin L; Urbas, Augustine M

    2002-07-24

    The synthesis of a series of polymeric Eu(III) complexes with polyester ligands, along with supporting emission spectra, luminescence lifetimes, and, for a Eu block copolymer film, atomic force microscopy (AFM) data, is presented. Dibenzoylmethane was derivatized with a hydroxyl initiator site (dbmOH, 1) for tin octoate catalyzed ring opening polymerization of dl-lactide. The resulting poly(lactic acid) macroligand, dbmPLA (2), was combined with EuCl3 to generate Eu(dbmPLA)3 (3). Chelation of both dbmPLA and a polycaprolactone-functionalized bipyridine ligand (bpyPCL2) led to the Eu(III)-centered heteroarm star Eu(dbmPLA)3(bpyPCL2) (4). Unpolarized emission spectra and luminescence lifetimes were recorded for the Eu polymers in CH2Cl2 and for Eu(dbmPLA)3, as a film. Solution data for Eu(dbm)3 and Eu(dbm)3(bpy) were collected for comparison. For Eu tris(dbm) complexes, data were fit to a double exponential decay, indicating the presence of multiple species. Relative amounts of the longer lifetime component increase in the series Eu(dbm)3 solutions to Eu(dbmPLA)3 solutions to Eu(dbmPLA)3 films, perhaps suggesting benefits of the "polymer shell effect" and the diminishment of aquo adducts known to shorten lifetimes. As with the nonpolymeric analogue, data for Eu(dbmPLA)3(bpyPCL2) fit to a single-exponential decay. The sharpness of the feature at 579.7 nm, attributable to the 5D0 --> 7F0 transition in the emission spectrum of 4, lends further support for a homogeneous sample. AFM studies of "as cast" thin films of 4 reveal a lamellar structure with a 17.5 nm repeat. These microstructures, inferred to contain Eu luminophores at the glassy PLA-crystalline PCL domain interfaces, are modified by thermal treatment.

  16. Conformational Lability in Serine Protease Active Sites: Structures of Hepatocyte Growth Factor Activator (HGFA) Alone and with the Inhibitory Domain from HGFA Inhibitor-1B

    SciTech Connect

    Shia, Steven; Stamos, Jennifer; Kirchhofer, Daniel; Fan, Bin; Wu, Judy; Corpuz, Raquel T.; Santell, Lydia; Lazarus, Robert A.; Eigenbrot, Charles

    2010-07-20

    Hepatocyte growth factor activator (HGFA) is a serine protease that converts hepatocyte growth factor (HGF) into its active form. When activated HGF binds its cognate receptor Met, cellular signals lead to cell growth, differentiation, and migration, activities which promote tissue regeneration in liver, kidney and skin. Intervention in the conversion of HGF to its active form has the potential to provide therapeutic benefit where HGF/Met activity is associated with tumorigenesis. To help identify ways to moderate HGF/Met effects, we have determined the molecular structure of the protease domain of HGFA. The structure we determined, at 2.7 {angstrom} resolution, with no pseudo-substrate or inhibitor bound is characterized by an unconventional conformation of key residues in the enzyme active site. In order to find whether this apparently non-enzymatically competent arrangement would persist in the presence of a strongly-interacting inhibitor, we also have determined, at 2.6 {angstrom} resolution, the X-ray structure of HGFA complexed with the first Kunitz domain (KD1) from the physiological inhibitor hepatocyte growth factor activator inhibitor 1B (HAI-1B). In this complex we observe a rearranged substrate binding cleft that closely mirrors the cleft of other serine proteases, suggesting an extreme conformational dynamism. We also characterize the inhibition of 16 serine proteases by KD1, finding that the previously reported enzyme specificity of the intact extracellular region of HAI-1B resides in KD1 alone. We find that HGFA, matriptase, hepsin, plasma kallikrein and trypsin are potently inhibited, and use the complex structure to rationalize the structural basis of these results.

  17. Selectivity of externally facing ion-binding sites in the Na/K pump to alkali metals and organic cations.

    PubMed

    Ratheal, Ian M; Virgin, Gail K; Yu, Haibo; Roux, Benoît; Gatto, Craig; Artigas, Pablo

    2010-10-26

    The Na/K pump is a P-type ATPase that exchanges three intracellular Na(+) ions for two extracellular K(+) ions through the plasmalemma of nearly all animal cells. The mechanisms involved in cation selection by the pump's ion-binding sites (site I and site II bind either Na(+) or K(+); site III binds only Na(+)) are poorly understood. We studied cation selectivity by outward-facing sites (high K(+) affinity) of Na/K pumps expressed in Xenopus oocytes, under voltage clamp. Guanidinium(+), methylguanidinium(+), and aminoguanidinium(+) produced two phenomena possibly reflecting actions at site III: (i) voltage-dependent inhibition (VDI) of outwardly directed pump current at saturating K(+), and (ii) induction of pump-mediated, guanidinium-derivative-carried inward current at negative potentials without Na(+) and K(+). In contrast, formamidinium(+) and acetamidinium(+) induced K(+)-like outward currents. Measurement of ouabain-sensitive ATPase activity and radiolabeled cation uptake confirmed that these cations are external K(+) congeners. Molecular dynamics simulations indicate that bound organic cations induce minor distortion of the binding sites. Among tested metals, only Li(+) induced Na(+)-like VDI, whereas all metals tested except Na(+) induced K(+)-like outward currents. Pump-mediated K(+)-like organic cation transport challenges the concept of rigid structural models in which ion specificity at site I and site II arises from a precise and unique arrangement of coordinating ligands. Furthermore, actions by guanidinium(+) derivatives suggest that Na(+) binds to site III in a hydrated form and that the inward current observed without external Na(+) and K(+) represents cation transport when normal occlusion at sites I and II is impaired. These results provide insights on external ion selectivity at the three binding sites.

  18. Geophysical bed sediment characterization of the Androscoggin River from the former Chlor-Alkali Facility Superfund Site, Berlin, New Hampshire, to the state border with Maine, August 2009

    USGS Publications Warehouse

    Degnan, James R.; Teeple, Andrew; Johnston, Craig M.; Marvin-DiPasquale, Mark C.; Luce, Darryl

    2011-01-01

    The former Chlor-Alkali Facility in Berlin, New Hampshire, was listed on the U.S. Environmental Protection Agency National Priorities List in 2005 as a Superfund site. The Chlor-Alkali Facility lies on the east bank of the Androscoggin River. Elemental mercury currently discharges from that bank into the Androscoggin River. The nature, extent, and the speciation of mercury and the production of methyl mercury contamination in the adjacent Androscoggin River is the subject of continuing investigations. The U.S. Geological Survey, in cooperation with Region I of the U.S. Environmental Protection Agency, used geophysical methods to determine the distribution, thickness, and physical properties of sediments in the Androscoggin River channel at a small area of an upstream reference reach and downstream from the site to the New Hampshire–Maine State border. Separate reaches of the Androscoggin River in the study area were surveyed with surface geophysical methods including ground-penetrating radar and step-frequency electromagnetics. Results were processed to assess sediment characteristics including grain size, electrical conductivity, and pore-water specific conductance. Specific conductance measured during surface- and pore-water sampling was used to help interpret the results of the geophysical surveys. The electrical resistivity of sediment samples was measured in the laboratory with intact pore water for comparison with survey results. In some instances, anthropogenic features and land uses, such as roads and power lines affected the detection of riverbed properties using geophysical methods; when this occurred, the data were removed. Through combining results, detailed riverbed sediment characterizations were made. Results from ground-penetrating radar surveys were used to image and measure the depth to the riverbed, depth to buried riverbeds, riverbed thickness and to interpret material-type variations in terms of relative grain size. Fifty two percent of the

  19. Role of black carbon in the sorption of polychlorinated dibenzo-p-dioxins and dibenzofurans at the Diamond Alkali superfund site, Newark Bay, New Jersey.

    PubMed

    Lambert, Matthew K; Friedman, Carey; Luey, Pamela; Lohmann, Rainer

    2011-05-15

    The sorption of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) to organic carbon (OC) and black carbon (BC) was measured in two sediment cores taken near the Diamond Alkali superfund site (DA) in the Passaic River and Newark Bay, New Jersey (U.S.A.). An OC partitioning model and a BC-inclusive, Freundlich distribution model were used to interpret measurements of freely dissolved PCDD/Fs using passive samplers in sediment incubations, together with measured sedimentary concentrations of OC, BC, and PCDD/Fs. Samples were also analyzed for polycyclic aromatic hydrocarbons (PAHs) as controls on the two distribution models. The OC partitioning model underpredicted the distribution of PAHs and PCDD/Fs by 10-100-fold. The Freundlich model predicted the distribution of PAHs at the DA to within a factor of 2-3 of observations. Black carbon-water partition coefficients (K(iBC)) for PCDD/Fs, derived from literature results of both field and laboratory studies differed up to 1000-fold from values derived from this study. Contrary to expectations, PCDDs displayed stronger sorption than either PCDFs or PAHs relative to their subcooled liquid aqueous solubilities. Even though the presence of BC in the sediments reduced the overall bioavailability of PCDD/Fs by >90%, the sediments at 2 m depth continue to display the highest pore water activities of PCDD/Fs.

  20. Alkali metal nitrate purification

    DOEpatents

    Fiorucci, Louis C.; Morgan, Michael J.

    1986-02-04

    A process is disclosed for removing contaminants from impure alkali metal nitrates containing them. The process comprises heating the impure alkali metal nitrates in solution form or molten form at a temperature and for a time sufficient to effect precipitation of solid impurities and separating the solid impurities from the resulting purified alkali metal nitrates. The resulting purified alkali metal nitrates in solution form may be heated to evaporate water therefrom to produce purified molten alkali metal nitrates suitable for use as a heat transfer medium. If desired, the purified molten form may be granulated and cooled to form discrete solid particles of purified alkali metal nitrates.

  1. Milk-alkali syndrome

    MedlinePlus

    ... this page: //medlineplus.gov/ency/article/000332.htm Milk-alkali syndrome To use the sharing features on this page, please enable JavaScript. Milk-alkali syndrome is a condition in which there ...

  2. Measurement of Total Site Mercury Emissions from a Chlor-Alkali Plant Using Ultraviolet Differential Optical Absorption Spectroscopy and Cell Room Roof-Vent Monitoring

    EPA Science Inventory

    Mercury-cell chlor-alkali plants can emit significant quantities of fugitive elemental mercury vapor to the air as part of production operations and maintenance activities. In the fall of 2006, the U.S. Environmental Protection Agency (EPA) conducted a measurement project at a ch...

  3. Measurement of Total Site Mercury Emissions from Chlor-Alkali Plant Using Ultraviolet Differential Optical Absorption Spectroscopy and Cell Room Roof-Vent Monitoring

    EPA Science Inventory

    This technical note describes a United States Environmental Protection Agency (U.S. EPA) measurement project to determine elemental mercury (Hg0) emissions from a mercury cell chlor-alkali (MCCA) facility in the southeastern U.S. during a 53-day monitoring campaign in the fall of...

  4. Site Preference in Multimetallic Nanoclusters: Incorporation of Alkali Metal Ions or Copper Atoms into the Alkynyl-Protected Body-Centered Cubic Cluster [Au7 Ag8 (C≡C(t) Bu)12 ]().

    PubMed

    Wang, Yu; Su, Haifeng; Ren, Liting; Malola, Sami; Lin, Shuichao; Teo, Boon K; Häkkinen, Hannu; Zheng, Nanfeng

    2016-11-21

    The synthesis, structure, substitution chemistry, and optical properties of the gold-centered cubic monocationic cluster [Au@Ag8 @Au6 (C≡C(t) Bu)12 ](+) are reported. The metal framework of this cluster can be described as a fragment of a body-centered cubic (bcc) lattice with the silver and gold atoms occupying the vertices and the body center of the cube, respectively. The incorporation of alkali metal atoms gave rise to [Mn Ag8-n Au7 (C≡C(t) Bu)12 ](+) clusters (n=1 for M=Na, K, Rb, Cs and n=2 for M=K, Rb), with the alkali metal ion(s) presumably occupying the vertex site(s), whereas the incorporation of copper atoms produced [Cun Ag8 Au7-n (C≡C(t) Bu)12 ](+) clusters (n=1-6), with the Cu atom(s) presumably occupying the capping site(s). The parent cluster exhibited strong emission in the near-IR region (λmax =818 nm) with a quantum yield of 2 % upon excitation at λ=482 nm. Its photoluminescence was quenched upon substitution with a Na(+) ion. DFT calculations confirmed the superatom characteristics of the title compound and the sodium-substituted derivatives.

  5. Effects of carbon substrate lability on carbon mineralization dynamics of tropical peat

    NASA Astrophysics Data System (ADS)

    Jauhiainen, Jyrki; Silvennoinen, Hanna; Könönen, Mari; Limin, Suwido; Vasander, Harri

    2016-04-01

    Extensive draining at tropical ombrotrophic peatlands in Southeast Asia has made them global 'hot spots' for greenhouse gas emissions. Management practises and fires have led to changed substrate status, which affects microbial processes. Here, we present the first data on how management practises affect carbon (C) mineralization processes at these soils. We compared the carbon mineralization potentials of pristine forest soils to those of drained fire affected soils at various depths, with and without additional labile substrates (glucose, glutamate and NO3-N) and in oxic and anoxic conditions by dedicated ex situ experiments. Carbon mineralization (CO2 and CH4 production) rates were higher in the pristine site peat, which contains more labile carbon due to higher input via vegetation. Production rates decreased with depth together with decreasing availability of labile carbon. Consequently, the increase in production rates after labile substrate addition was relatively modest from pristine site as compared to the managed site and from the top layers as compared to deeper layers. Methanogenesis had little importance in total carbon mineralization. Adding labile C and N enhanced heterotrophic CO2 production more than the sole addition of N. Surprisingly, oxygen availability was not an ultimate requirement for substantial CO2 production rates, but anoxic respiration yielded comparable rates, especially at the pristine soils. Flooding of these sites will therefore reduce, but not completely cease, peat carbon loss. Reintroduced substantial vegetation and fertilization in degraded peatlands can enrich recalcitrant peat with simple C and N compounds and thus increase microbiological activity.

  6. PAH repartitioning in field-contaminated sediment following removal of the labile chemical fraction.

    PubMed

    Birdwell, Justin E; Thibodeaux, Louis J

    2009-11-01

    The effect of removing the labile chemical fraction associated with sediment particles followed by internal chemical redistribution was examined in a field-contaminated sediment. Using data from desorption equilibrium (organic carbon-water partition coefficients, K(OC)) and kinetic (rate of release) experiments, estimates of polynuclear aromatic hydrocarbon biphasic partitioning and desorption rates for both the labile and nonlabile chemical fractions or organic matter compartments were obtained. Sediment K(OC) values increased between 50 and 150% after removal of the labile chemical fraction. Following depletion of the labile chemical fraction during desorption experiments, sediment was stored 30 and 90 days to allow for chemical redistribution between the labile and nonlabile compartments. The subsequent desorption data indicated repartitioning had occurred with the nonlabile chemical fraction recharging the labile compartment. The results provide evidence that chemical transfer between organic matter compartments, either through interparticle porewater or via direct intraparticle compartmental exchange, is a real phenomenon that occurs over relatively short times (weeks to months). This calls into question the idea that hydrophobic organic pollutants in the nonlabile chemical fraction are sequestered or less bioavailable over the long-term and has implications for water quality impacts during contaminated sediment resuspension events, risk assessment of polluted sites, and selection of sediment remediation strategies.

  7. Quercetin as a shuttle for labile iron.

    PubMed

    Baccan, Mayara Marinovic; Chiarelli-Neto, Orlando; Pereira, Regina Mara Silva; Espósito, Breno Pannia

    2012-02-01

    The antioxidant activity of flavonoids may involve their ability to complex body iron in non-redox-active forms. In this study, it was found that the catechol flavonoids rutin and quercetin are able to suppress redox-active labile plasma iron (LPI) in both buffered solution and in iron-overloaded sera. Both flavonoids are effective in loading the metal into the iron-transport protein transferrin. Iron derivatives of quercetin and rutin are able to permeate cell membranes, however, only free quercetin is able to gain access to the cytosol and decrease intracellular labile iron pools. These results suggest that the antioxidant activity of quercetin may be dependent on its ability to shuttle labile iron from cell compartments followed by its transfer to transferrin.

  8. Alkali cation specific adsorption onto fcc(111) transition metal electrodes.

    PubMed

    Mills, J N; McCrum, I T; Janik, M J

    2014-07-21

    The presence of alkali cations in electrolyte solutions is known to impact the rate of electrocatalytic reactions, though the mechanism of such impact is not conclusively determined. We use density functional theory (DFT) to examine the specific adsorption of alkali cations to fcc(111) electrode surfaces, as specific adsorption may block catalyst sites or otherwise impact surface catalytic chemistry. Solvation of the cation-metal surface structure was investigated using explicit water models. Computed equilibrium potentials for alkali cation adsorption suggest that alkali and alkaline earth cations will specifically adsorb onto Pt(111) and Pd(111) surfaces in the potential range of hydrogen oxidation and hydrogen evolution catalysis in alkaline solutions.

  9. Lability of drinking water treatment residuals (WTR) immobilized phosphorus: aging and pH effects.

    PubMed

    Agyin-Birikorang, Sampson; O'Connor, George A

    2007-01-01

    Time constraints associated with conducting long-term (>20 yr) field experiments to test the stability of drinking water treatment residuals (WTR) sorbed phosphorus (P) inhibit improved understanding of the fate of sorbed P in soils when important soil properties (e.g., pH) change. We used artificially aged samples to evaluate aging and pH effects on lability of WTR-immobilized P. Artificial aging was achieved through incubation at elevated temperatures (46 or 70 degrees C) for 4.5 yr, and through repeated wetting and drying for 2 yr. Using a modified isotopic ((32)P) dilution technique, coupled with a stepwise acidification procedure, we monitored changes in labile P concentrations over time. This technique enabled evaluation of the effect of pH on the lability of WTR-immobilized P. Within the pH range of 4 to 7, WTR amendment, coupled with artificial aging, ultimately reduced labile P concentrations by > or = 75% relative to the control (no-WTR) samples. Soil samples with different physicochemical properties from two 7.5-yr-old, one-time WTR-amended field sites were utilized to validate the trends observed with the artificially aged samples. Despite the differences in physicochemical properties among the three (two field-aged and one artificially aged) soil samples, similar trends of aging and pH effects on lability of WTR-immobilized P were observed. Labile P concentrations of the WTR-amended field-aged samples of the two sites decreased 6 mo after WTR amendment and the reduction persisted for 7.5 yr, ultimately resulting in > or = 70% reduction, compared to the control plots. We conclude that WTR application is capable of reducing labile P concentration in P-impacted soils, doing so for a long time, and that within the commonly encountered range of pH values for agricultural soils WTR-immobilized P should be stable.

  10. Alkali metal ionization detector

    DOEpatents

    Bauerle, James E.; Reed, William H.; Berkey, Edgar

    1978-01-01

    Variations in the conventional filament and collector electrodes of an alkali metal ionization detector, including the substitution of helical electrode configurations for either the conventional wire filament or flat plate collector; or, the substitution of a plurality of discrete filament electrodes providing an in situ capability for transferring from an operationally defective filament electrode to a previously unused filament electrode without removing the alkali metal ionization detector from the monitored environment. In particular, the helical collector arrangement which is coaxially disposed about the filament electrode, i.e. the thermal ionizer, provides an improved collection of positive ions developed by the filament electrode. The helical filament design, on the other hand, provides the advantage of an increased surface area for ionization of alkali metal-bearing species in a monitored gas environment as well as providing a relatively strong electric field for collecting the ions at the collector electrode about which the helical filament electrode is coaxially positioned. Alternatively, both the filament and collector electrodes can be helical. Furthermore, the operation of the conventional alkali metal ionization detector as a leak detector can be simplified as to cost and complexity, by operating the detector at a reduced collector potential while maintaining the sensitivity of the alkali metal ionization detector adequate for the relatively low concentration of alkali vapor and aerosol typically encountered in leak detection applications.

  11. In Situ, High-Resolution Profiles of Labile Metals in Sediments of Lake Taihu

    PubMed Central

    Wang, Dan; Gong, Mengdan; Li, Yangyang; Xu, Lv; Wang, Yan; Jing, Rui; Ding, Shiming; Zhang, Chaosheng

    2016-01-01

    Characterizing labile metal distribution and biogeochemical behavior in sediments is crucial for understanding their contamination characteristics in lakes, for which in situ, high-resolution data is scare. The diffusive gradient in thin films (DGT) technique was used in-situ at five sites across Lake Taihu in the Yangtze River delta in China to characterize the distribution and mobility of eight labile metals (Fe, Mn, Zn, Ni, Cu, Pb, Co and Cd) in sediments at a 3 mm spatial resolution. The results showed a great spatial heterogeneity in the distributions of redox-sensitive labile Fe, Mn and Co in sediments, while other metals had much less marked structure, except for downward decreases of labile Pb, Ni, Zn and Cu in the surface sediment layers. Similar distributions were found between labile Mn and Co and among labile Ni, Cu and Zn, reflecting a close link between their geochemical behaviors. The relative mobility, defined as the ratio of metals accumulated by DGT to the total contents in a volume of sediments with a thickness of 10 mm close to the surface of DGT probe, was the greatest for Mn and Cd, followed by Zn, Ni, Cu and Co, while Pb and Fe had the lowest mobility; this order generally agreed with that defined by the modified BCR approach. Further analyses showed that the downward increases of pH values in surface sediment layer may decrease the lability of Pb, Ni, Zn and Cu as detected by DGT, while the remobilization of redox-insensitive metals in deep sediment layer may relate to Mn cycling through sulphide coprecipitation, reflected by several corresponding minima between these metals and Mn. These in situ data provided the possibility for a deep insight into the mechanisms involved in the remobilization of metals in freshwater sediments. PMID:27608033

  12. Apparatus enables accurate determination of alkali oxides in alkali metals

    NASA Technical Reports Server (NTRS)

    Dupraw, W. A.; Gahn, R. F.; Graab, J. W.; Maple, W. E.; Rosenblum, L.

    1966-01-01

    Evacuated apparatus determines the alkali oxide content of an alkali metal by separating the metal from the oxide by amalgamation with mercury. The apparatus prevents oxygen and moisture from inadvertently entering the system during the sampling and analytical procedure.

  13. Glycosyltransfer in mutants of putative catalytic residue Glu303 of the human ABO(H) A and B blood group glycosyltransferases GTA and GTB proceeds through a labile active site.

    PubMed

    Blackler, Ryan J; Gagnon, Susannah M L; Polakowski, Robert; Rose, Natisha L; Zheng, Ruixiang B; Letts, James A; Johal, Asha R; Schuman, Brock; Borisova, Svetlana N; Palcic, Monica M; Evans, Stephen V

    2016-11-22

    The homologous glycosyltransferases α-1,3-N-acetylgalactosaminyltransferase (GTA) and α-1,3-galactosyltransferase (GTB) carry out the final synthetic step of the closely related human ABO(H) blood group A and B antigens. The catalytic mechanism of these model retaining enzymes remains under debate, where Glu303 has been suggested to act as a putative nucleophile in a double displacement mechanism, a local dipole stabilizing the intermediate in an orthogonal associative mechanism or a general base to stabilize the reactive oxocarbenium ion-like intermediate in an S N i-like mechanism. Kinetic analysis of GTA and GTB point mutants E303C, E303D, E303Q and E303A shows that despite the enzymes having nearly identical sequences, the corresponding mutants of GTA/GTB have up to a 13-fold difference in their residual activities relative to wild type. High-resolution single crystal X-ray diffraction studies reveal, surprisingly, that the mutated Cys, Asp and Gln functional groups are no more than 0.8 Å further from the anomeric carbon of donor substrate compared to wild type. However, complicating the analysis is the observation that Glu303 itself plays a critical role in maintaining the stability of a strained "double-turn" in the active site through several hydrogen bonds, and any mutation other than E303Q leads to significantly higher thermal motion or even disorder in the substrate recognition pockets. Thus, there is a remarkable juxtaposition of the mutants E303C and E303D, which retain significant activity despite disrupted active site architecture, with GTB/E303Q, which maintains active site architecture but exhibits zero activity. These findings indicate that nucleophilicity at position 303 is more catalytically valuable than active site stability and highlight the mechanistic elasticity of these enzymes.

  14. Alkali metal ion battery with bimetallic electrode

    DOEpatents

    Boysen, Dane A; Bradwell, David J; Jiang, Kai; Kim, Hojong; Ortiz, Luis A; Sadoway, Donald R; Tomaszowska, Alina A; Wei, Weifeng; Wang, Kangli

    2015-04-07

    Electrochemical cells having molten electrodes having an alkali metal provide receipt and delivery of power by transporting atoms of the alkali metal between electrode environments of disparate chemical potentials through an electrochemical pathway comprising a salt of the alkali metal. The chemical potential of the alkali metal is decreased when combined with one or more non-alkali metals, thus producing a voltage between an electrode comprising the molten the alkali metal and the electrode comprising the combined alkali/non-alkali metals.

  15. Ideas about Acids and Alkalis.

    ERIC Educational Resources Information Center

    Toplis, Rob

    1998-01-01

    Investigates students' ideas, conceptions, and misconceptions about acids and alkalis before and after a teaching sequence in a small-scale research project. Concludes that student understanding of acids and alkalis is lacking. (DDR)

  16. Methods of recovering alkali metals

    DOEpatents

    Krumhansl, James L; Rigali, Mark J

    2014-03-04

    Approaches for alkali metal extraction, sequestration and recovery are described. For example, a method of recovering alkali metals includes providing a CST or CST-like (e.g., small pore zeolite) material. The alkali metal species is scavenged from the liquid mixture by the CST or CST-like material. The alkali metal species is extracted from the CST or CST-like material.

  17. Chlor-Alkali Technology.

    ERIC Educational Resources Information Center

    Venkatesh, S.; Tilak, B. V.

    1983-01-01

    Chlor-alkali technology is one of the largest electrochemical industries in the world, the main products being chlorine and caustic soda (sodium hydroxide) generated simultaneously by the electrolysis of sodium chloride. This technology is reviewed in terms of electrochemical principles and manufacturing processes involved. (Author/JN)

  18. Reduced contribution of thermally-labile sugar lesions to DNA double-strand break formation after exposure to neutrons.

    PubMed

    Singh, Satyendra K; Wu, Wenqi; Stuschke, Martin; Bockisch, Andreas; Iliakis, George

    2012-12-01

    In cells exposed to ionizing radiation, double-strand breaks (DSBs) form within clustered damage sites from lesions disrupting the DNA sugar-phosphate backbone. It is commonly assumed that DSBs form promptly and are immediately detected and processed by the cellular DNA damage response apparatus. However, DSBs also form by delayed chemical conversion of thermally-labile sugar lesions (TLSL) to breaks. We recently reported that conversion of thermally-labile sugar lesions to breaks occurs in cells maintained at physiological temperatures. Here, we investigate the influence of radiation quality on the formation of thermally-labile sugar lesions dependent DSBs. We show that, although the yields of total DSBs are very similar after exposure to neutrons and X rays, the yields of thermally-labile sugar lesions dependent DSBs from neutrons are decreased in comparison to that from X rays. Thus, the yields of prompt DSBs for neutrons are greater than for X rays. Notably, after neutron irradiation the decreased yield of thermally-labile sugar lesion dependent DSBs is strongly cell line dependent, likely reflecting subtle differences in DNA organization. We propose that the higher ionization density of neutrons generates with higher probability prompt DSBs within ionization clusters and renders the ensuing chemical evolution of thermally-labile sugar lesions inconsequential to DNA integrity. Modification of thermally-labile sugar lesion evolution may define novel radiation protection strategies aiming at decreasing DSB formation by chemically preserving thermally-labile sugar lesions until other DSB contributing lesions within the clustered damage site are removed by non-DSB repair pathways.

  19. Modelling the cis-oxo-labile binding site motif of non-heme iron oxygenases. Water exchange and remarkable oxidation reactivity of a novel non-heme iron(IV)-oxo compound bearing a tripodal tetradentate ligand

    PubMed Central

    Company, Anna; Prat, Irene; Frisch, Jonathan R.; Ballesté, Ruben Mas; Güell, Mireia; Juhász, Gergely; Ribas, Xavi; Münck, Eckard; Luis, Josep M.; Que, Lawrence

    2011-01-01

    The spectroscopic and chemical characterization of a new synthetic non-heme iron(IV)-oxo species [FeIV(O)(Me,HPytacn)(S)]2+ (2, Me,HPytacn = 1-(2′-pyridylmethyl)-4,7-dimethyl-1,4,7-triazacyclononane, S = CH3CN or H2O) is described. 2 has been prepared by reaction of [FeII(CF3SO3)2(Me,HPytacn)] (1) with peracetic acid. Complex 2 bears a tetradentate N4 ligand that leaves two cis- sites available for binding an oxo group and a second external ligand but, unlike related iron(IV)-oxo of tetradentate ligands, it is remarkably stable at room temperature (t1/2 > 2h at 288 K). Its ability to exchange the oxygen atom of the oxo ligand with water has been analyzed in detail by means of kinetic studies, and a mechanism has been proposed on the basis of DFT calculations. Hydrogen-atom abstraction from C-H bonds and oxygen atom transfer to sulfides by 2 have also been studied. Despite its thermal stability, 2 proves to be a very powerful oxidant that is capable of breaking the strong C-H bond of cyclohexane (BDE = 99.3 kcal·mol−1). PMID:21268165

  20. Hydrothermal alkali metal recovery process

    DOEpatents

    Wolfs, Denise Y.; Clavenna, Le Roy R.; Eakman, James M.; Kalina, Theodore

    1980-01-01

    In a coal gasification operation or similar conversion process carried out in the presence of an alkali metal-containing catalyst wherein solid particles containing alkali metal residues are produced, alkali metal constituents are recovered from the particles by treating them with a calcium or magnesium-containing compound in the presence of water at a temperature between about 250.degree. F. and about 700.degree. F. and in the presence of an added base to establish a pH during the treatment step that is higher than would otherwise be possible without the addition of the base. During the treating process the relatively high pH facilitates the conversion of water-insoluble alkali metal compounds in the alkali metal residues into water-soluble alkali metal constituents. The resultant aqueous solution containing water-soluble alkali metal constituents is then separated from the residue solids, which consist of the treated particles and any insoluble materials formed during the treatment step, and recycled to the gasification process where the alkali metal constituents serve as at least a portion of the alkali metal constituents which comprise the alkali metal-containing catalyst. Preferably, the base that is added during the treatment step is an alkali metal hydroxide obtained by water washing the residue solids produced during the treatment step.

  1. Alkalis in alternative biofuels

    SciTech Connect

    Miles, T.R.; Miles, T.R. Jr.; Bryers, R.W.; Baxter, L.L.; Jenkins, B.M.; Oden, L.L.

    1994-12-31

    The alkali content and behavior of inorganic material of annually produced biofuels severely limits their use for generating electrical power in conventional furnaces. A recent eighteen-month investigation of the chemistry and firing characteristics of 26 different biofuels has been conducted. Firing conditions were simulated in the laboratory for eleven biofuels. This paper describes some results from the investigation including fuel properties, deposits, deposition mechanisms, and implications for biomass boiler design, fuel sampling and characterizations. Urban wood fuel, agricultural residues, energy crops, and other potential alternate fuels are included in the study. Conventional methods for establishing fuel alkali content and determining ash sticky temperatures were deceptive. The crux of the problem was found to be the high concentration of potassium in biofuels and its reactions with other fuel constituents which lower the ``sticky temperature`` of the ash to the 650 C to 760 C (1,200 F-1,400 F).

  2. Alkali-vapor lasers

    NASA Astrophysics Data System (ADS)

    Zweiback, J.; Komashko, A.; Krupke, W. F.

    2010-02-01

    We report on the results from several of our alkali laser systems. We show highly efficient performance from an alexandrite-pumped rubidium laser. Using a laser diode stack as a pump source, we demonstrate up to 145 W of average power from a CW system. We present a design for a transversely pumped demonstration system that will show all of the required laser physics for a high power system.

  3. Rhizosphere Environment and Labile Phosphorus Release from Organic Waste-Amended Soils.

    NASA Astrophysics Data System (ADS)

    Dao, Thanh H.

    2015-04-01

    Crop residues and biofertilizers are primary sources of nutrients for organic crop production. However, soils treated with large amounts of nutrient-enriched manure have elevated phosphorus (P) levels in regions of intensive animal agriculture. Surpluses occurred in these amended soils, resulting in large pools of exchangeable inorganic P (Pi) and enzyme-labile organic P (Po) that averaging 30.9 and 68.2 mg kg-1, respectively. Organic acids produced during crop residue decomposition can promote the complexation of counter-ions and decouple and release unbound Pi from metal and alkali metal phosphates. Animal manure and cover crop residues also contain large amounts of soluble organic matter, and likely generate similar ligands. However, a high degree of heterogeneity in P spatial distribution in such amended fields, arising from variances in substrate physical forms ranging from slurries to dried solids, composition, and diverse application methods and equipment. Distinct clusters of Pi and Po were observed, where accumulation of the latter forms was associated with high soil microbial biomass C and reduced phosphomonoesterases' activity. Accurate estimates of plant requirements and lability of soil P pools, and real-time plant and soil P sensing systems are critical considerations to optimally manage manure-derived nutrients in crop production systems. An in situ X-ray fluorescence-based approach to sensing canopy and soil XRFS-P was developed to improve the yield-soil P relationship for optimal nutrient recommendations in addition to allowing in-the-field verification of foliar P status.

  4. Lability of Secondary Organic Particulate Matter

    SciTech Connect

    Liu, Pengfei; Li, Yong Jie; Wang, Yan; Giles, Mary K.; Zaveri, Rahul A.; Bertram, Allan K.; Martin, Scot T.

    2016-10-24

    Accurate simulations of the consenctrations of atmospheric organic particulate matter (PM) are needed for predicting energy flow in the Earth’s climate system. In the past, simulations of organic PM widely assume equilibrium partitioning of semivolatile organic compounds (SVOCs) between the PM and surrounding vapor. Herein, we test this assumption by measuring evaporation rates and associated vapor mass concentration of organic films representative of atmospheric PM. For films representing anthropogenic PM, evaporation rates and vapor mass concentrations increased above a threshold relative humidity (RH), indicating equilibrium partitioning above a transition RH but not below. In contrast for films representing biogenic PM, no threshold was observed, indicating equilibrium partitioning at all RHs. The results suggest that the mass lability of atmospheric organic PM can differ in consequential ways among Earth’s natural biomes, polluted regions, and regions of land-use change, and these differences need to be considered when simulating atmospheric organic PM.

  5. Fate and lability of silver in soils: Effect of ageing

    EPA Science Inventory

    The fate and lability of added soluble Ag in soils over time was examined by measurement of labile metal (E-value) by isotopic dilution using the 110mAg radioactive isotope and the solid-phase speciation of Ag by X-ray absorption near edge structure (XANES) spectrosco...

  6. THE ASSAY AND PROPERTIES OF LABILE FACTOR (FACTOR V)

    PubMed Central

    Quick, Armand J.

    1960-01-01

    Human oxalated plasma stored at 4° C. until the prothrombin time is increased beyond 60 sec. is a reliable medium for assaying labile factor (factor V) because its response to added labile factor corresponds quantitatively to that of plasma from patients with congenital deficiency of this factor. Such an agreement is not obtained with plasma stored at 37°C. The stability of labile factor is closely associated with ionized calcium. The addition of thrombin to fresh oxalated plasma causes an apparent hyperactivity of labile factor, but this is completely removed by adsorption with Ca3(PO)2. Oxalated plasma when adsorbed with Ca3(PO4)2 before treatment with thrombin does not develop this adventitious activity, nor does it occur in stored plasma treated with thrombin. The seemingly high labile factor activity in serum can be explained by the activation of this factor which is independent of labile factor but acts synergistically with it. The true labile factor concentration can be determined only after the accelerator is removed by adsorption with Ca3(PO4)2. A close agreement between the consumption of prothrombin and the loss of labile factor during clotting is observed. PMID:13738700

  7. DNA-AP sites generation by Etoposide in whole blood cells

    PubMed Central

    2009-01-01

    Background Etoposide is currently one of the most commonly used antitumor drugs. The mechanisms of action proposed for its antitumor activity are based mainly on its interaction with topoisomerase II. Etoposide effects in transformed cells have been described previously. The aim of the present study was to evaluate the genotoxic effects of this drug in non-transformed whole blood cells, such as occurs as collateral damage induced by some chemotherapies. Methods To determine etoposide genotoxicity, we employed Comet assay in two alkaline versions. To evaluate single strand breaks and delay repair sites we use pH 12.3 conditions and pH >13 to evidence alkali labile sites. With the purpose to quantified apurinic or apyrimidine (AP) sites we employed a specific restriction enzyme. Etoposide effects were determined on whole blood cells cultured in absence or presence of phytohemagglutinin (PHA) treated during 2 and 24 hours of cultured. Results Alkaline (pH > 13) single cell gel electrophoresis (SCGE) assay experiments revealed etoposide-induced increases in DNA damage in phytohemaglutinine (PHA)-stimulated blood and non-stimulated blood cells. When the assay was performed at a less alkaline pH, 12.3, we observed DNA damage in PHA-stimulated blood cells consistent with the existence of alkali labile sites (ALSs). In an effort to elucidate the molecular events underlying this result, we applied exonuclease III (Exo III) in conjunction with a SCGE assay, enabling detection of DNA-AP sites along the genome. More DNA AP-sites were revealed by Exo III and ALSs were recognized by the SCGE assay only in the non-stimulated blood cells treated with etoposide. Conclusion Our results indicate that etoposide induces DNA damage specifically at DNA-AP sites in quiescent blood cells. This effect could be involved in the development of secondary malignancies associated with etoposide chemotherapy. PMID:19917085

  8. The 4843 Alkali Metal Storage Facility Closure Plan

    SciTech Connect

    Not Available

    1991-06-01

    The 4843 AMSF has been used primarily to provide a centralized building to receive and store dangerous and mixed alkali metal waste, including sodium and lithium, which has been generated at the Fast Flux Test Facility and at various other Hanford Site operations that used alkali metals. Most of the dangerous and mixed alkali metal waste received consists of retired equipment from liquid sodium processes. The unit continues to store material. In general, only solid alkali metal waste that is water reactive is stored at the 4843 AMSF. The 4843 AMSF will be closed in a manner consistent with Ecology guidelines and regulations (WAC 173-303-610). The general closure procedure is detailed as follows.

  9. Removal of Retired Alkali Metal Test Systems

    SciTech Connect

    Brehm, W. F.; Church, W. R.; Biglin, J. W.

    2003-02-26

    This paper describes the successful effort to remove alkali metals, alkali metal residues, and piping and structures from retired non-radioactive test systems on the Hanford Site. These test systems were used between 1965 and 1982 to support the Fast Flux Test Facility and the Liquid Metal Fast Breeder Reactor Program. A considerable volume of sodium and sodium-potassium alloy (NaK) was successfully recycled to the commercial sector; structural material and electrical material such as wiring was also recycled. Innovative techniques were used to safely remove NaK and its residues from a test system that could not be gravity-drained. The work was done safely, with no environmental issues or significant schedule delays.

  10. K{sub 2}NaOsO{sub 5.5} and K{sub 3}NaOs{sub 2}O{sub 9}: The first osmium perovskites containing alkali cations at the 'A' site

    SciTech Connect

    Mogare, Kailash M.; Klein, Wilhelm; Jansen, Martin

    2012-07-15

    K{sub 2}NaOsO{sub 5.5} and K{sub 3}NaOs{sub 2}O{sub 9} were obtained from solid-state reactions of potassium superoxide, sodium peroxide and osmium metal at elevated oxygen pressures. K{sub 2}NaOsO{sub 5.5} crystallizes as an oxygen-deficient cubic double perovskite in space group Fm3{sup Macron }m with a=8.4184(5) A and contains isolated OsO{sub 6} octahedra. K{sub 3}NaOs{sub 2}O{sub 9} crystallizes hexagonally in P6{sub 3}/mmc with a=5.9998(4) A and c=14.3053(14) A. K{sub 3}NaOs{sub 2}O{sub 9} consists of face sharing Os{sub 2}O{sub 9} pairs of octahedra. According to magnetic measurements K{sub 2}NaOsO{sub 5.5} is diamagnetic, whereas K{sub 3}NaOs{sub 2}O{sub 9} displays strong antiferromagnetic coupling (T{sub N}=140 K), indicating enhanced magnetic interactions within the octahedral pair. - Graphical abstract: High oxidation states of Os, obtained by high oxygen pressure synthesis, are accommodated in double and triple perovskite matrices. K{sub 3}NaOs{sub 2}O{sub 9} displays enhanced magnetic interactions. Highlights: Black-Right-Pointing-Pointer New osmates containing highly oxidized Os were obtained by high O{sub 2} pressure synthesis. Black-Right-Pointing-Pointer High oxidation states of Os are accommodated in double and triple perovskite matrices. Black-Right-Pointing-Pointer Both compounds represent the first Os perovskites with an alkali metal at the A site. Black-Right-Pointing-Pointer K{sub 3}NaOs{sub 2}O{sub 9} displays enhanced magnetic interactions within the octahedral pair.

  11. Preparation of alkali metal dispersions

    NASA Technical Reports Server (NTRS)

    Rembaum, A.; Landel, R. F. (Inventor)

    1968-01-01

    A method is described for producing alkali metal dispersions of high purity. The dispersions are prepared by varying the equilibrium solubility of the alkali metal in a suitable organic solvent in the presence of aromatic hydrocarbons. The equilibrium variation is produced by temperature change. The size of the particles is controlled by controlling the rate of temperature change.

  12. PROCESS OF RECOVERING ALKALI METALS

    DOEpatents

    Wolkoff, J.

    1961-08-15

    A process is described of recovering alkali metal vapor by sorption on activated alumina, activated carbon, dehydrated zeolite, activated magnesia, or Fuller's earth preheated above the vaporization temperature of the alkali metal and subsequent desorption by heating the solvent under vacuum. (AEC)

  13. Purification of alkali metal nitrates

    DOEpatents

    Fiorucci, Louis C.; Gregory, Kevin M.

    1985-05-14

    A process is disclosed for removing heavy metal contaminants from impure alkali metal nitrates containing them. The process comprises mixing the impure nitrates with sufficient water to form a concentrated aqueous solution of the impure nitrates, adjusting the pH of the resulting solution to within the range of between about 2 and about 7, adding sufficient reducing agent to react with heavy metal contaminants within said solution, adjusting the pH of the solution containing reducing agent to effect precipitation of heavy metal impurities and separating the solid impurities from the resulting purified aqueous solution of alkali metal nitrates. The resulting purified solution of alkali metal nitrates may be heated to evaporate water therefrom to produce purified molten alkali metal nitrate suitable for use as a heat transfer medium. If desired, the purified molten form may be granulated and cooled to form discrete solid particles of alkali metal nitrates.

  14. Alkali metal and alkali earth metal gadolinium halide scintillators

    DOEpatents

    Bourret-Courchesne, Edith; Derenzo, Stephen E.; Parms, Shameka; Porter-Chapman, Yetta D.; Wiggins, Latoria K.

    2016-08-02

    The present invention provides for a composition comprising an inorganic scintillator comprising a gadolinium halide, optionally cerium-doped, having the formula A.sub.nGdX.sub.m:Ce; wherein A is nothing, an alkali metal, such as Li or Na, or an alkali earth metal, such as Ba; X is F, Br, Cl, or I; n is an integer from 1 to 2; m is an integer from 4 to 7; and the molar percent of cerium is 0% to 100%. The gadolinium halides or alkali earth metal gadolinium halides are scintillators and produce a bright luminescence upon irradiation by a suitable radiation.

  15. In situ high-resolution evaluation of labile arsenic and mercury in sediment of a large shallow lake.

    PubMed

    Wang, Chao; Yao, Yu; Wang, Peifang; Hou, Jun; Qian, Jin; Yuan, Ye; Fan, Xiulei

    2016-01-15

    The precise evaluation of arsenic (As) and mercury (Hg) bioavailability in sediment is crucial to controlling As and Hg contamination, but traditional ex situ measurements hamper comprehensive analysis of labile As and Hg in sediment. In this study, we characterized in situ labile As and Hg in sediment of Lake Hongze using the zirconium (Zr) oxide diffusive gradients in thin films (DGT) technique and 3-mercaptopropyl functionalized silica gel DGT, respectively. The concentrations of DGT-labile As and Hg in the sediment profiles were found to exhibit considerable variation, ranging from 0.15 to 4.15 μg L(-1) for As and from 0.04 to 1.35 μg L(-1) for Hg. As and Hg flux values, calculated based on the concentration gradients measured from the DGT profiles for both the overlying water and sediment close to the sediment-water interface, were used to determine the contamination status of As and Hg. Flux values of As and Hg were between -0.066 and 0.067 ng cm(-2)d(-1) and between -0.0187 and 0.0181 ng cm(-2)d(-1), respectively. The GNU's Not Unix R (GNU R) programming language was used to identify outliers of As and Hg at various depths at the sampling sites. The results indicate that the sites with the most outliers were all located in the regions that were seriously affected by contaminants from the Huai River. The DGT-labile As and Hg concentrations in the 0-30 mm layer were found to be significantly correlated with concentrations of labile As and Hg, total dissolved As and Hg, and total As and Hg in the overlying water, as indicated by ex situ measurements. Results show that DGT is a reliable and high-resolution technique that can be used for in situ monitoring of the labile fractions of As and Hg in sediment in fresh water bodies.

  16. Why is firefly oxyluciferin a notoriously labile substance?

    PubMed

    Maltsev, Oleg V; Nath, Naba K; Naumov, Panče; Hintermann, Lukas

    2014-01-13

    The chemistry of firefly bioluminescence is important for numerous applications in biochemistry and analytical chemistry. The emitter of this bioluminescent system, firefly oxyluciferin, is difficult to handle. The cause of its lability was clarified while its synthesis was reinvestigated. A side product was identified and characterized by NMR spectroscopy and X-ray crystallography. The reason for the lability of oxyluciferin is now ascribed to autodimerization of the coexisting enol and keto forms in a Mannich-type reaction.

  17. Upgrading platform using alkali metals

    DOEpatents

    Gordon, John Howard

    2017-01-17

    A method for removing sulfur, nitrogen or metals from an oil feedstock. The method involves reacting the oil feedstock with an alkali metal and a radical capping substance. The alkali metal reacts with the metal, sulfur or nitrogen content to form one or more inorganic products and the radical capping substance reacts with the carbon and hydrogen content to form a hydrocarbon phase. The inorganic products may then be separated out from the hydrocarbon phase.

  18. Upgrading platform using alkali metals

    SciTech Connect

    Gordon, John Howard

    2014-09-09

    A process for removing sulfur, nitrogen or metals from an oil feedstock (such as heavy oil, bitumen, shale oil, etc.) The method involves reacting the oil feedstock with an alkali metal and a radical capping substance. The alkali metal reacts with the metal, sulfur or nitrogen content to form one or more inorganic products and the radical capping substance reacts with the carbon and hydrogen content to form a hydrocarbon phase. The inorganic products may then be separated out from the hydrocarbon phase.

  19. Synergistic capture mechanisms for alkali and sulphur species from combustion. Quarterly report No. 10, December 1992--February 1993

    SciTech Connect

    Peterson, T.W.; Shadman, F.; Wendt, J.O.L.; Wu, Baochun

    1993-07-26

    A number of sorbents with alumina-silicate base and sulfur capturing active sites have been developed for simultaneous removal of alkali metal compounds and sulfur dioxide. Current report will focus on bauxite sorbents, which includes experiments on sulfur dioxide absorption, alkali capturing and alkali/sulfur absorption simultaneously by bauxite-based sorbents. The alkali compound used here is sodium chloride. Experiments show an effective adsorption of sulfur or alkali separately, and the combined adsorption of alkali/sulfur. Atomic absorption analysis of reaction products shows that there is a much higher sodium content in the combined reaction products than that of the single reaction of alkali absorption by bauxite. Further X-ray diffraction analysis shows that there is sodium sulfate in the final products of simultaneous reaction, which indicates the formation and then condensation of sodium sulfate in the reaction system.

  20. The response of gross nitrogen mineralization to labile carbon inputs

    NASA Astrophysics Data System (ADS)

    Bengtson, Per

    2014-05-01

    Input of labile carbon sources to forest soils commonly result in priming, i.e. an increase in the microbial decomposition of soil organic matter. Efforts aimed at quantifying the extent of priming have, to date, largely focused on soil organic matter decomposition manifested as soil respiration. Less is known about how gross nitrogen mineralization responds to input of labile carbon. It is often assumed that increased priming results in decreased soil carbon stocks. However, microbial mineralization of organic nitrogen into plant available forms is a major factor limiting primary production in forests. If increased decomposition of soil organic matter in response to labile carbon is accompanied by a concurrent increased nitrogen mineralization, this could result in elevated primary production and higher rates of plant derived organic matter input to soils. Therefore, in order to fully understand the effect of priming on net ecosystem exchange and soil carbon stocks, it is vital to consider if increased decomposition of soil organic matter caused by priming also results in increased nitrogen mineralization. Here I present the results from a series of experiments aimed at determining if, and to which extent, gross nitrogen mineralization is stimulated by input of labile carbon. The results suggest that it is by no means uncommon to find an increase in gross N mineralization rates in response to labile carbon inputs. The magnitude of the increase seems dependent on the nitrogen status of the soil, as well as the concentration and rate of labile carbon inputs. However, continuous input of labile carbon sources that also contains nitrogen, e.g. amino acids, seems to inhibit rather than increase the mineralization of organic nitrogen. These findings suggest that there is a potential for a positive feedback between priming and primary production that needs to be considered in order to fully understand the influence of priming on net ecosystem exchange and soil carbon

  1. The final deprotection step in oligonucleotide synthesis is reduced to a mild and rapid ammonia treatment by using labile base-protecting groups.

    PubMed Central

    Schulhof, J C; Molko, D; Teoule, R

    1987-01-01

    Phenoxyacetyl (pac) and methoxyacetyl (mac) for adenine and guanine, isobutyryl for cytosine, were successfully applied as amino protecting groups both in phosphotriester and phosphoramidite approaches. As shown by N.M.R. and H.P.L.C. analysis, they are completely deblocked in less than four hours in 29% ammonia at room temperature allowing the preparation of modified DNA containing alkali labile bases such as saturated pyrimidines. The stability of N6-phenoxyacetyl-deoxyadenosine versus depurination in acidic conditions used in the detritylation step was favorably compared with that of the classic N6-benzoyl protected adenine. Images PMID:3822812

  2. High-resolution imaging of labile phosphorus and its relationship with iron redox state in lake sediments.

    PubMed

    Gao, Yulu; Liang, Tao; Tian, Shuhan; Wang, Lingqing; Holm, Peter E; Bruun Hansen, Hans Christian

    2016-12-01

    A thorough understanding of the labile status and dynamics of phosphorus (P) and iron (Fe) across the sediment-water interface (SWI) is essential for managing internal P release in eutrophic lakes. Fe-coupled inactivation of P in sediments is an important factor which affects internal P release in freshwater lakes. In this study, two in-situ high-resolution diffusive gradients in thin films (DGT) techniques, Zr-Oxide DGT and ZrO-Chelex DGT, were used to investigate the release characteristics of P from sediments in a large freshwater lake (Dongting Lake, China; area of 2691 km(2)) experiencing a regional summer algal bloom. Two-dimensional distributions of labile P in sediments were imaged with the Zr-Oxide DGT without destruction of the original structure of the sediment layer at four sites of the lake. The concentration of DGT-labile P in the sediments, ranging from 0.007 to 0.206 mg L(-1), was highly heterogeneous across the profiles. The values of apparent diffusion flux (Fd) and release flux (Fr) of P varied between -0.027-0.197 mg m(-2) d(-1) and 0.037-0.332 mg m(-2) d(-1), respectively. Labile P showed a high and positive correlation (p < 0.01) with labile Fe(II) in the profiles, providing high-resolution evidence for the key role of Fe-redox cycling in labile P variation in sediments.

  3. [Using a modified remote sensing imagery for interpreting changes in cultivated saline-alkali land].

    PubMed

    Gao, Hui; Liu, Hui-tao; Liu, Hong-juan; Liu, Jin-tong

    2015-04-01

    This paper developed a new interpretation symbol system for grading and classifying saline-alkali land, using Huanghua, a cosatal city in Hebei Province as a case. The system was developed by inverting remote sensing images from 1992 to 2011 based on site investigation, plant cover characteristics and features of remote sensing images. Combining this interpretation symbol system with supervising classification method, the information on arable land was obtained for the coastal saline-alkali ecosystem of Huanghua City, and the saline-alkali land area, changes in intensity of salinity-alkalinity and spatial distribution from 1992 to 2011 were analyzed. The results showed that salinization of arable land in Huanghua City alleviated from 1992 to 2011. The severely and moderately saline-alkali land area decreased in 2011 compared with 1992, while the non/slightly saline land area increased. The moderately saline-alkali land in southeast transformed to non/slightly saline-alkaline, while the severely saline-alkali land in west of the city far from the coastal zone became moderately saline-alkaline. The center of gravity (CG) of severely and non/slightly saline-alkali land moved closer the coastline, while that of the moderately saline-alkali land moved from southwest coastal line to northwest. Factors influencing changes in arable land within the saline-alkali ecosystem of Huanghua City were climate, hydrology and human activities.

  4. Effects of inherent alkali and alkaline earth metallic species on biomass pyrolysis at different temperatures.

    PubMed

    Hu, Song; Jiang, Long; Wang, Yi; Su, Sheng; Sun, Lushi; Xu, Boyang; He, Limo; Xiang, Jun

    2015-09-01

    This work aimed to investigate effects of inherent alkali and alkaline earth metallic species (AAEMs) on biomass pyrolysis at different temperatures. The yield of CO, H2 and C2H4 was increased and that of CO2 was suppressed with increasing temperature. Increasing temperature could also promote depolymerization and aromatization reactions of active tars, forming heavier polycyclic aromatic hydrocarbons, leading to decrease of tar yields and species diversity. Diverse performance of inherent AAEMs at different temperatures significantly affected the distribution of pyrolysis products. The presence of inherent AAEMs promoted water-gas shift reaction, and enhanced the yield of H2 and CO2. Additionally, inherent AAEMs not only promoted breakage and decarboxylation/decarbonylation reaction of thermally labile hetero atoms of the tar but also enhanced thermal decomposing of heavier aromatics. Inherent AAEMs could also significantly enhance the decomposition of levoglucosan, and alkaline earth metals showed greater effect than alkali metals.

  5. Neuropsychological correlates of emotional lability in children with ADHD

    PubMed Central

    Banaschewski, Tobias; Jennen-Steinmetz, Christine; Brandeis, Daniel; Buitelaar, Jan K.; Kuntsi, Jonna; Poustka, Luise; Sergeant, Joseph A.; Sonuga-Barke, Edmund J.; Frazier-Wood, Alexis C.; Albrecht, Björn; Chen, Wai; Uebel, Henrik; Schlotz, Wolff; van der Meere, Jaap J.; Gill, Michael; Manor, Iris; Miranda, Ana; Mulas, Fernando; Oades, Robert D.; Roeyers, Herbert; Rothenberger, Aribert; Steinhausen, Hans-Christoph; Faraone, Stephen V.; Asherson, Philip

    2012-01-01

    Background Emotional lability (EL) is commonly seen in patients with Attention Deficit/Hyperactivity Disorder (ADHD). The reasons for this association are currently unknown. To address this question we examined the relationship between ADHD and EL symptoms, and performance on a range of neuropsychological tasks to clarify whether EL symptoms are predicted by particular cognitive and/or motivational dysfunctions and whether these associations are mediated by the presence of ADHD symptoms. Methods A large multi-site sample of 424 carefully diagnosed ADHD cases and 564 unaffected siblings and controls aged 6 to 18 years performed a broad neuropsychological test battery, including a Go/No-Go Task, a warned 4-choice Reaction Time task, the Maudsley Index of Childhood Delay Aversion, and Digit span backwards. Neuropsychological variables were aggregated as indices of processing speed, response variability, executive functions, choice impulsivity and the influence of energetic and/or motivational factors. EL and ADHD symptoms were regressed on each neuropsychological variable in separate analyses controlling for age, gender and IQ, and, in subsequent regression analyses, for ADHD and EL symptoms respectively. Results Neuropsychological variables significantly predicted ADHD and EL symptoms with moderate to low regression coefficients. However, the association between neuropsychological parameters on EL disappeared entirely when the effect of ADHD symptoms was taken into account, revealing that the association between the neuropsychological performance measures and EL is completely mediated statistically by variations in ADHD symptoms. Conversely, neuropsychological effects on ADHD symptoms remained after EL symptom severity was taken into account. Conclusions The neuropsychological parameters examined here predict ADHD more strongly than EL. They cannot explain EL symptoms beyond what is already accounted for by ADHD symptom severity. The association between EL and ADHD

  6. Repeated Labilization-Reconsolidation Processes Strengthen Declarative Memory in Humans

    PubMed Central

    Forcato, Cecilia; Rodríguez, María L. C.; Pedreira, María E.

    2011-01-01

    The idea that memories are immutable after consolidation has been challenged. Several reports have shown that after the presentation of a specific reminder, reactivated old memories become labile and again susceptible to amnesic agents. Such vulnerability diminishes with the progress of time and implies a re-stabilization phase, usually referred to as reconsolidation. To date, the main findings describe the mechanisms associated with the labilization-reconsolidation process, but little is known about its functionality from a biological standpoint. Indeed, two functions have been proposed. One suggests that destabilization of the original memory after the reminder allows the integration of new information into the background of the original memory (memory updating), and the other suggests that the labilization-reconsolidation process strengthens the original memory (memory strengthening). We have previously reported the reconsolidation of human declarative memories, demonstrating memory updating in the framework of reconsolidation. Here we deal with the strengthening function attributed to the reconsolidation process. We triggered labilization-reconsolidation processes successively by repeated presentations of the proper reminder. Participants learned an association between five cue-syllables and their respective response-syllables. Twenty-four hours later, the paired-associate verbal memory was labilized by exposing the subjects to one, two or four reminders. The List-memory was evaluated on Day 3 showing that the memory was improved when at least a second reminder was presented in the time window of the first labilization-reconsolidation process prompted by the earlier reminder. However, the improvement effect was revealed on Day 3, only when at least two reminders were presented on Day2 and not as a consequence of only retrieval. Therefore, we propose central concepts for the reconsolidation process, emphasizing its biological role and the parametrical constrains

  7. Hydrothermal alkali metal catalyst recovery process

    DOEpatents

    Eakman, James M.; Clavenna, LeRoy R.

    1979-01-01

    In a coal gasification operation or similar conversion process carried out in the presence of an alkali metal-containing catalyst wherein solid particles containing alkali metal residues are produced, alkali metal constituents are recovered from the particles primarily in the form of water soluble alkali metal formates by treating the particles with a calcium or magnesium-containing compound in the presence of water at a temperature between about 250.degree. F. and about 700.degree. F. and in the presence of added carbon monoxide. During the treating process the water insoluble alkali metal compounds comprising the insoluble alkali metal residues are converted into water soluble alkali metal formates. The resultant aqueous solution containing water soluble alkali metal formates is then separated from the treated particles and any insoluble materials formed during the treatment process, and recycled to the gasification process where the alkali metal formates serve as at least a portion of the alkali metal constituents which comprise the alkali metal-containing catalyst. This process permits increased recovery of alkali metal constituents, thereby decreasing the overall cost of the gasification process by reducing the amount of makeup alkali metal compounds necessary.

  8. Labile trace elements in carbonaceous chondrites - A survey

    NASA Technical Reports Server (NTRS)

    Xiao, Xiaoyue; Lipschutz, Michael E.

    1992-01-01

    Data are presented on 14 trace elements, including Co, Au, Ga, Rb, Sb, Ag, Se, Cs, Te, Zn, Cd, Bi, Tl, and In (nearly all of which are moderately or highly labile in meteorites), obtained by radiochemical neutron activation analyses of 42 C2-C6 chondrites, all but three from Antarctica. The data indicate that carbonaceous chondrites of petrographic types 2-6 define compositional continua. It is suggested that carbonaceous C2-C6 chondrites may reflect a mixture of material that formed at low temperatures and that contained cosmic levels of highly labile elements, with material that was devoid of them.

  9. Alkali Metal Cluster Theory.

    NASA Astrophysics Data System (ADS)

    Chen, Jian

    Available from UMI in association with The British Library. Requires signed TDF. In this thesis, we apply the tight-binding Hubbard model to alkali metal clusters with Hartree-Fock self-consistent methods and perturbation methods for the numerical calculations. We have studied the relation between the equilibrium structures and the range of the hopping matrix elements in the Hubbard Hamiltonian. The results show that the structures are not sensitive to the interaction range but are determined by the number of valence electrons each atom has. Inertia tensors are used to analyse the symmetries of the clusters. The principal axes of the clusters are determined and they are the axes of rotational symmetries of clusters if the clusters have any. The eigenvalues of inertia tensors which are the indication of the deformation of clusters are compared between our model and the ellipsoidal jellium model. The agreement is good for large clusters. At a finite temperature, the thermal motion fluctuates the structures. We defined a fluctuation function with the distance matrix of a cluster. The fluctuation has been studied with the Monte-Carlo simulation method. Our studies show that the clusters remain in the solid state when temperature is low. The small values of fluctuation functions indicates the thermal vibration of atoms around their equilibrium positions. If the temperature is high, the atoms are delocalized. The cluster melts and enters the liquid region. The cluster melting is simulated by the Monte-Carlo simulation with the fluctuation function we defined. Energy levels of clusters are calculated from the Hubbard model. Ionization potentials and magic numbers are also obtained from these energy levels. The results confirm that the Hubbard model is a good approximation for a small cluster. The excitation energy is presented by the difference between the original level and excited level, and the electron-hole interactions. We also have studied cooling of clusters

  10. Electrolytic method to make alkali alcoholates using ion conducting alkali electrolyte/separator

    DOEpatents

    Joshi, Ashok V [Salt Lake City, UT; Balagopal, Shekar [Sandy, UT; Pendelton, Justin [Salt Lake City, UT

    2011-12-13

    Alkali alcoholates, also called alkali alkoxides, are produced from alkali metal salt solutions and alcohol using a three-compartment electrolytic cell. The electrolytic cell includes an anolyte compartment configured with an anode, a buffer compartment, and a catholyte compartment configured with a cathode. An alkali ion conducting solid electrolyte configured to selectively transport alkali ions is positioned between the anolyte compartment and the buffer compartment. An alkali ion permeable separator is positioned between the buffer compartment and the catholyte compartment. The catholyte solution may include an alkali alcoholate and alcohol. The anolyte solution may include at least one alkali salt. The buffer compartment solution may include a soluble alkali salt and an alkali alcoholate in alcohol.

  11. Process for recovering alkali metals and sulfur from alkali metal sulfides and polysulfides

    DOEpatents

    Gordon, John Howard; Alvare, Javier

    2016-10-25

    Alkali metals and sulfur may be recovered from alkali monosulfide and polysulfides in an electrolytic process that utilizes an electrolytic cell having an alkali ion conductive membrane. An anolyte solution includes an alkali monosulfide, an alkali polysulfide, or a mixture thereof and a solvent that dissolves elemental sulfur. A catholyte includes molten alkali metal. Applying an electric current oxidizes sulfide and polysulfide in the anolyte compartment, causes alkali metal ions to pass through the alkali ion conductive membrane to the catholyte compartment, and reduces the alkali metal ions in the catholyte compartment. Liquid sulfur separates from the anolyte solution and may be recovered. The electrolytic cell is operated at a temperature where the formed alkali metal and sulfur are molten.

  12. How to Compute Labile Metal-Ligand Equilibria

    ERIC Educational Resources Information Center

    de Levie, Robert

    2007-01-01

    The different methods used for computing labile metal-ligand complexes, which are suitable for an iterative computer solution, are illustrated. The ligand function has allowed students to relegate otherwise tedious iterations to a computer, while retaining complete control over what is calculated.

  13. Neuropsychological Correlates of Emotional Lability in Children with ADHD

    ERIC Educational Resources Information Center

    Banaschewski, Tobias; Jennen-Steinmetz, Christine; Brandeis, Daniel; Buitelaar, Jan K.; Kuntsi, Jonna; Poustka, Luise; Sergeant, Joseph A.; Sonuga-Barke, Edmund J.; Frazier-Wood, Alexis C.; Albrecht, Bjorn; Chen, Wai; Uebel, Henrik; Schlotz, Wolff; van der Meere, Jaap J.; Gill, Michael; Manor, Iris; Miranda, Ana; Mulas, Fernando; Oades, Robert D.; Roeyers, Herbert; Rothenberger, Aribert; Steinhausen, Hans-Christoph; Faraone, Stephen V.; Asherson, Philip

    2012-01-01

    Background: Emotional lability (EL) is commonly seen in patients with attention-deficit/hyperactivity disorder (ADHD). The reasons for this association remain currently unknown. To address this question, we examined the relationship between ADHD and EL symptoms, and performance on a range of neuropsychological tasks to clarify whether EL symptoms…

  14. Electrical Resistivity of Alkali Elements.

    DTIC Science & Technology

    1976-01-01

    rubidium, cesium, and francium ) and contains recommended reference values (or provisional or typical values). The compiled data include all the...and information on the electrical resistivity of alkali elements (lithium, sodium, potassium, rubidium, cesium, and francium ) and contains...107Ic. Magnetic Flux Density Dependence o.. .. ... .... 112 4.6. Francium ..........................115j a. Temperature Dependence

  15. Non-labile silver species in biosolids remain stable throughout ...

    EPA Pesticide Factsheets

    Increasing commercial use of nanosilver has focussed attention on the fate of silver (Ag) in the wastewater release pathway. This paper reports the speciation and lability of Ag in archived, stockpiled, and contemporary biosolids from the UK, USA and Australia, and indicates that biosolids Ag concentrations have decreased significantly over recent decades. XANES revealed the importance of reduced-sulfur binding environments for Ag speciation in materials ranging from freshly produced sludge to biosolids weathered under ambient environmental conditions for more than 50 years. Isotopic dilution with 110mAg showed that Ag was predominantly non-labile in both fresh and aged biosolids (13.7% mean lability), with E-values ranging from 0.3 to 60 mg/kg and 5 mM CaNO3 extractable Ag from 1.2 to 609 µg/kg (0.002 - 3.4% of the total Ag). This study indicates that at the time of soil application, biosolids Ag will be predominantly Ag-sulfides and characterised by low isotopic lability. This paper presents an overview of biosolids Ag chemistry in historic and contemporary biosolids sourced from the UK, USA and Australia from the 1950s until today by drawing on a unique collection of archived, stockpiled and contemporary biosolids samples. Characteristics of biosolids Ag chemistry determined in this study included total Ag measurement by neutron activation analysis (NAA); the assessment of Ag lability by 110mAg isotopic dilution (E-values); and Ag speciation by X-ray Absorp

  16. Quantification of Labile Soil Mercury by Stable Isotope Dilution Techniques

    NASA Astrophysics Data System (ADS)

    Shetaya, Waleed; Huang, Jen-How; Osterwalder, Stefan; Alewell, Christine

    2016-04-01

    Mercury (Hg) is a toxic element that can cause severe health problems to humans. Mercury is emitted to the atmosphere from both natural and anthropogenic sources and can be transported over long distances before it is deposited to aquatic and terrestrial environments. Aside from accumulation in soil solid phases, Hg deposited in soils may migrate to surface- and ground-water or enter the food chain, depending on its lability. There are many operationally-defined extraction methods proposed to quantify soil labile metals. However, these methods are by definition prone to inaccuracies such as non-selectivity, underestimation or overestimation of the labile metal pool. The isotopic dilution technique (ID) is currently the most promising method for discrimination between labile and non-labile metal fractions in soil with a minimum disturbance to soil-solid phases. ID assesses the reactive metal pool in soil by defining the fraction of metal both in solid and solution phases that is isotopically-exchangeable known as the 'E-value'. The 'E-value' represents the metal fraction in a dynamic equilibrium with the solution phase and is potentially accessible to plants. This is carried out by addition of an enriched metal isotope to soil suspensions and quantifying the fraction of metal that is able to freely exchange with the added isotope by measuring the equilibrium isotopic ratio by ICP-MS. E-value (mg kg-1) is then calculated as follows: E-Value = (Msoil/ W) (CspikeVspike/ Mspike) (Iso1IAspike -Iso2IAspikeRss / Iso2IAsoil Rss - Iso1IAsoil) where M is the average atomic mass of the metal in the soil or the spike, W is the mass of soil (kg), Cspike is the concentration of the metal in the spike (mg L-1), Vspike is the volume of spike (L), IA is isotopic abundance, and Rss is the equilibrium ratio of isotopic abundances (Iso1:Iso2). Isotopic dilution has been successfully applied to determine E-values for several elements. However, to our knowledge, this method has not yet

  17. Total and Labile Phosphorus Concentrations as Influenced by Riparian Buffer Soil Properties.

    PubMed

    Young, Eric O; Ross, Donald S

    2016-01-01

    Riparian buffers can act as a phosphorus (P) source under active stream bank erosion. Using soil and landscape variables (soil series, drainage class, organic matter, and pH) to index P concentrations could improve P loss risk tools for buffers. The objectives of this study were (i) to determine if soil properties could predict total and labile P concentrations within a 10-ha riparian buffer and (ii) to quantify the degree of spatial dependence of P and related properties. Soil samples were taken in 15-cm increments to a depth of 60 cm using a grid ( = 71) from an established riparian buffer along the Rock River in Vermont. Total soil P (TP), plant-available P determined by Modified Morgan extraction (MM-P), pH, soil organic matter (SOM), soil texture, and select cations were measured. We found that TP (152-1536 mg P kg) and MM-P (0.4-14.6 mg kg) ranged widely, with distinct differences between soil series. Mean TP and MM-P were greater in alluvial and glaciolacustrine soils compared with glacial till. Across all samples, MM-P was weakly related to soil properties; however, total labile P (orthophosphate + organic P measured by ICP) and unreactive labile P (ICP-P - colorimetric-P) could both be predicted by SOM ( = 0.59 and 0.73, respectively). Strong spatial dependence was found for P and related properties as revealed by geospatial analyses. Results show that P availability in the buffer was strongly related to soil genesis and support site-specific approaches for P loss risk evaluation in buffers.

  18. Positron-alkali atom scattering

    NASA Technical Reports Server (NTRS)

    Mceachran, R. P.; Horbatsch, M.; Stauffer, A. D.; Ward, S. J.

    1990-01-01

    Positron-alkali atom scattering was recently investigated both theoretically and experimentally in the energy range from a few eV up to 100 eV. On the theoretical side calculations of the integrated elastic and excitation cross sections as well as total cross sections for Li, Na and K were based upon either the close-coupling method or the modified Glauber approximation. These theoretical results are in good agreement with experimental measurements of the total cross section for both Na and K. Resonance structures were also found in the L = 0, 1 and 2 partial waves for positron scattering from the alkalis. The structure of these resonances appears to be quite complex and, as expected, they occur in conjunction with the atomic excitation thresholds. Currently both theoretical and experimental work is in progress on positron-Rb scattering in the same energy range.

  19. Alkali metal/sulfur battery

    DOEpatents

    Anand, Joginder N.

    1978-01-01

    Alkali metal/sulfur batteries in which the electrolyte-separator is a relatively fragile membrane are improved by providing means for separating the molten sulfur/sulfide catholyte from contact with the membrane prior to cooling the cell to temperatures at which the catholyte will solidify. If the catholyte is permitted to solidify while in contact with the membrane, the latter may be damaged. The improvement permits such batteries to be prefilled with catholyte and shipped, at ordinary temperatures.

  20. DGT-labile As, Cd, Cu and Ni monitoring in freshwater: toward a framework for interpretation of in situ deployment.

    PubMed

    Buzier, Rémy; Charriau, Adeline; Corona, David; Lenain, Jean-François; Fondanèche, Patrice; Joussein, Emmanuel; Poulier, Gaëlle; Lissalde, Sophie; Mazzella, Nicolas; Guibaud, Gilles

    2014-09-01

    The use of the Diffusive Gradient in Thin Film sampler (DGT) as a monitoring tool for regulatory programs is currently evaluated. In this context, the impact of commonly followed procedures on the accuracy of DGT-labile As, Cd, Cu, and Ni quantification was studied. Initial sampler contamination yields to define quantification limits instead of using blank subtraction, thus avoiding artifact concentrations. Not considering the alteration of element diffusion by the filter membrane leads to significant underestimation. However, diffusion coefficients determined on a non-fouled membrane were found to be suitable for the studied site, making it possible to use data from the literature. When diffusive boundary layer formation is neglected, no loss of accuracy is recorded provided the layer is thinner than 0.5 mm. Finally, exploration of potential biases allowed initiating a framework that might help limit inaccuracies in DGT-labile concentration estimation and interpretation, especially in a low contamination context.

  1. Two clusters of GABAergic ellipsoid body neurons modulate olfactory labile memory in Drosophila.

    PubMed

    Zhang, Zhiping; Li, Xiaoting; Guo, Jing; Li, Yan; Guo, Aike

    2013-03-20

    In Drosophila, aversive olfactory memory is believed to be stored in a prominent brain structure, the mushroom body (MB), and two pairs of MB intrinsic neurons, the dorsal paired medial (DPM) and the anterior paired lateral (APL) neurons, are found to regulate the consolidation of middle-term memory (MTM). Here we report that another prominent brain structure, the ellipsoid body (EB), is also involved in the modulation of olfactory MTM. Activating EB R2/R4m neurons does not affect the learning index, but specifically eliminates anesthesia-sensitive memory (ASM), the labile component of olfactory MTM. We further demonstrate that approximately two-thirds of these EB neurons are GABAergic and are responsible for the suppression of ASM. Using GRASP (GFP reconstitution across synaptic partners), we reveal potential synaptic connections between the EB and MB in regions covering both the presynaptic and postsynaptic sites of EB neurons, suggesting the presence of bidirectional connections between these two important brain structures. These findings suggest the existence of direct connections between the MB and EB, and provide new insights into the neural circuit basis for olfactory labile memory in Drosophila.

  2. Alkali-Resistant Mechanism of a Hollandite DeNOx Catalyst.

    PubMed

    Hu, Pingping; Huang, Zhiwei; Gu, Xiao; Xu, Fei; Gao, Jiayi; Wang, Yue; Chen, Yaxin; Tang, Xingfu

    2015-06-02

    A thorough understanding of the deactivation mechanism by alkalis is of great importance for rationally designing improved alkali-resistant deNOx catalysts, but a traditional ion-exchange mechanism cannot often accurately describe the nature of the deactivation, thus hampering the development of superior catalysts. Here, we establish a new exchange-coordination mechanism on the basis of the exhaustive study on the strong alkali resistance of a hollandite manganese oxide (HMO) catalyst. A combination of isothermal adsorption measurements of ammonia with X-ray absorption near-edge structure spectra and X-ray photoelectron spectra reveals that alkali metal ions first react with protons from Brønsted acid sites of HMO via the ion exchange. Synchrotron X-ray diffraction patterns and extended X-ray absorption fine structure spectra coupled with theoretical calculations demonstrate that the exchanged alkali metal ions are subsequently stabilized at size-suitable cavities in the HMO pores via a coordination model with an energy savings. This exchange-coordination mechanism not only gives a wholly convincing explanation for the intrinsic nature of the deactivation of the reported catalysts by alkalis but also provides a strategy for rationally designing improved alkali-resistant deNOx catalysts in general.

  3. Regenerable activated bauxite adsorbent alkali monitor probe

    DOEpatents

    Lee, Sheldon H. D.

    1992-01-01

    A regenerable activated bauxite adsorber alkali monitor probe for field applications to provide reliable measurement of alkali-vapor concentration in combustion gas with special emphasis on pressurized fluidized-bed combustion (PFBC) off-gas. More particularly, the invention relates to the development of a easily regenerable bauxite adsorbent for use in a method to accurately determine the alkali-vapor content of PFBC exhaust gases.

  4. Regenerable activated bauxite adsorbent alkali monitor probe

    SciTech Connect

    Lee, S.H.D.

    1991-01-22

    This invention relates to a regenerable activated bauxite adsorber alkali monitor probe for field applications to provide reliable measurement of alkali-vapor 5 concentration in combustion gas with special emphasis on pressurized fluidized-bed combustion (PFBC) off-gas. More particularly, the invention relates to the development of a easily regenerable bauxite adsorbent for use in a method to accurately determine the alkali-vapor content of PFBC 10 exhaust gases.

  5. Regenerable activated bauxite adsorbent alkali monitor probe

    DOEpatents

    Lee, S.H.D.

    1992-12-22

    A regenerable activated bauxite adsorber alkali monitor probe for field applications to provide reliable measurement of alkali-vapor concentration in combustion gas with special emphasis on pressurized fluidized-bed combustion (PFBC) off-gas. More particularly, the invention relates to the development of a easily regenerable bauxite adsorbent for use in a method to accurately determine the alkali-vapor content of PFBC exhaust gases. 6 figs.

  6. Temporal Changes in Photochemically Labile DOM and Implications for Carbon Budgets in Peatland Aquatic Systems

    NASA Astrophysics Data System (ADS)

    Pickard, A.

    2015-12-01

    Aquatic systems in peatland catchments are subject to high loading of dissolved organic matter (DOM) from surrounding terrestrial environments. However the significance of photochemical transformation of DOM in peatland carbon budgets remains poorly constrained. In this study UV irradiation experiments were conducted on water samples collected over one year from two contrasting systems in Scotland: a stream draining a peatland with high levels of DOM and a reservoir draining a peat catchment with low levels of DOM. Further samples were collected from the high DOM system during two storm events. After experimental exposure, optical and chemical analyses were employed to determine photochemical lability of the DOM pool. At both sites irradiation-induced decreases in dissolved organic carbon (DOC) as a percentage of the total carbon pool were greatest in winter, suggesting that DOM was depleted in photo-reactive molecules in summer. Seasonal variability in DOC was high at the stream site and was positively correlated with CO₂ and CO photoproduction (r2 = 0.81 and 0.83, respectively; p<0.05). Lignin phenol analyses indicate considerable contribution of peat to the DOM pool at the stream site, particularly during summer. Whilst DOC concentrations did not vary greatly during storm events, UV-Vis absorbance indicators did, signifying changing DOM source material from activation of different hydrological pathways. The most photo-reactive DOM occurred 5-10 hours after peak discharge, suggesting that storms replenish photochemically labile DOM in headwater streams. Conservative estimates using data from this study suggest that up to 7% of the DOM pool of peatland streams can be lost (primarily as CO₂ and CO) upon exposure to 8 hours of environmentally representative UV irradiation. Further investigation in field campaigns under natural UV exposure are underway to assess the importance of photodegradation of DOM as a loss pathway of carbon based gases from aquatic systems.

  7. Vibrational Spectroscopic Studies on Some Double Alkali Tungstates Belonging to Orthorhombic Class at Room Temperature

    SciTech Connect

    Sharaff, Usha; Bajpai, P. K.; Choudhary, R. N. P.

    2011-11-22

    Room temperature IR and Raman spectra of rubidium lithium tungstate and sodium lithium tungstates belonging to double alkali tungstate family are investigated using group theoretical methods. Observed internal and lattice modes in both systems studied are assigned. Analysis of spectral behavior reveals that the effect of site potential around tungstates ion is weak and the factor group splitting is operative. Differences in the lattice mode mixing and splitting of internal modes is influenced by the statistical ordering between two alkali ions having large and small ionic radii and is explained using size and charge effect observed earlier in scheelite type of structure. Thus, vibrational spectroscopic analysis may be a tool to understand the alkali ion ordering in double alkali systems.

  8. Phonon spectra of alkali metals

    NASA Astrophysics Data System (ADS)

    Zeković, S.; Vukajlović, F.; Veljković, V.

    1982-10-01

    In this work we used a simple local model pseudopotential which includes screening for the phonon spectra calculations of alkali metals. The results obtained are in very good agreement with experimental data. In some branches of phonon spectra the differences between theoretical and experimental results are within 1-2%, while the maximum error is about 6%. The suggested form of the pseudopotential allows us to describe the phonon spectra of Na, K and Rb with only one, and, at the same time, a unique, parameter. In this case, the maximum disagreements from experiment are 9% for Na, 8% for K and 7% for Rb.

  9. Process for the disposal of alkali metals

    DOEpatents

    Lewis, Leroy C.

    1977-01-01

    Large quantities of alkali metals may be safely reacted for ultimate disposal by contact with a hot concentrated caustic solution. The alkali metals react with water in the caustic solution in a controlled reaction while steam dilutes the hydrogen formed by the reaction to a safe level.

  10. Method of handling radioactive alkali metal waste

    DOEpatents

    Wolson, R.D.; McPheeters, C.C.

    Radioactive alkali metal is mixed with particulate silica in a rotary drum reactor in which the alkali metal is converted to the monoxide during rotation of the reactor to produce particulate silica coated with the alkali metal monoxide suitable as a feed material to make a glass for storing radioactive material. Silica particles, the majority of which pass through a 95 mesh screen or preferably through a 200 mesh screen, are employed in this process, and the preferred weight ratio of silica to alkali metal is 7 to 1 in order to produce a feed material for the final glass product having a silica to alkali metal monoxide ratio of about 5 to 1.

  11. Method of handling radioactive alkali metal waste

    DOEpatents

    Wolson, Raymond D.; McPheeters, Charles C.

    1980-01-01

    Radioactive alkali metal is mixed with particulate silica in a rotary drum reactor in which the alkali metal is converted to the monoxide during rotation of the reactor to produce particulate silica coated with the alkali metal monoxide suitable as a feed material to make a glass for storing radioactive material. Silica particles, the majority of which pass through a 95 mesh screen or preferably through a 200 mesh screen, are employed in this process, and the preferred weight ratio of silica to alkali metal is 7 to 1 in order to produce a feed material for the final glass product having a silica to alkali metal monoxide ratio of about 5 to 1.

  12. [Universal implementation of pathogen inactivation in labile blood products is a major step towards transfusion safety].

    PubMed

    Cazenave, Jean-Pierre

    2010-12-01

    Transfusion of labile blood products (red cell concentrates, platelet concentrates and plasma) is vital in the absence of alternatives. Patients and doctors have always feared infections transmitted by blood, blood components and blood-derived drugs. It is potentially dangerous to delay implementation of pathogen inactivation in labile blood products pending a perfect process. Universal implementation of pathogen inactivation in labile blood products is a major step towards transfusion safety.

  13. An ultrahigh-resolution mass spectrometry index to estimate natural organic matter lability

    PubMed Central

    D'Andrilli, Juliana; Cooper, William T; Foreman, Christine M; Marshall, Alan G

    2015-01-01

    Rationale Determining the chemical constituents of natural organic matter (NOM) by Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FTICRMS) remains the ultimate measure for probing its source material, evolution, and transport; however, lability and the fate of organic matter (OM) in the environment remain controversial. FTICRMS-derived elemental compositions are presented in this study to validate a new interpretative method to determine the extent of NOM lability from various environments. Methods FTICRMS data collected over the last decade from the same 9.4 tesla instrument using negative electrospray ionization at the National High Magnetic Field Laboratory in Tallahassee, Florida, was used to validate the application of a NOM lability index. Solid-phase extraction cartridges were used to isolate the NOM prior to FTICRMS; mass spectral peaks were calibrated internally by commonly identified NOM homologous series, and molecular formulae were determined for NOM composition and lability analysis. Results A molecular lability boundary (MLB) was developed from the FTICRMS molecular data, visualized from van Krevelen diagrams, dividing the data into more and less labile constituents. NOM constituents above the MLB at H/C ≥1.5 correspond to more labile material, whereas NOM constituents below the MLB, H/C <1.5, exhibit less labile, more recalcitrant character. Of all marine, freshwater, and glacial environments considered for this study, glacial ecosystems were calculated to contain the most labile OM. Conclusions The MLB extends our interpretation of FTICRMS NOM molecular data to include a metric of lability, and generally ranked the OM environments from most to least labile as glacial > marine > freshwater. Applying the MLB is useful not only for individual NOM FTICRMS studies, but also provides a lability threshold to compare and contrast molecular data with other FTICRMS instruments that survey NOM from around the world. Copyright © 2015

  14. The Labile Side of Iron Supplementation in CKD

    PubMed Central

    Cabantchik, Zvi Ioav

    2015-01-01

    The practice of intravenous iron supplementation has grown as nephrologists have gradually moved away from the liberal use of erythropoiesis-stimulating agents as the main treatment for the anemia of CKD. This approach, together with the introduction of large-dose iron preparations, raises the future specter of inadvertent iatrogenic iron toxicity. Concerns have been raised in original studies and reviews about cardiac complications and severe infections that result from long-term intravenous iron supplementation. Regarding the iron preparations specifically, even though all the currently available preparations appear to be relatively safe in the short term, little is known regarding their long-term safety. In this review we summarize current knowledge of iron metabolism with an emphasis on the sources and potentially harmful effects of labile iron, highlight the approaches to identifying labile iron in pharmaceutical preparations and body fluids and its potential toxic role as a pathogenic factor in the complications of CKD, and propose methods for its early detection in at-risk patients. PMID:25999405

  15. Labile neurotoxin in serum of calves with "nervous" coccidiosis.

    PubMed Central

    Isler, C M; Bellamy, J E; Wobeser, G A

    1987-01-01

    Mouse inoculation was used to test for the presence of a toxin in the serum, cerebrospinal fluid, and intestinal contents collected from cases of bovine enteric coccidiosis, with and without neurological signs, and from control calves. Intravenous inoculation of mice with 10 mL/kg of serum from calves showing nervous signs caused effects significantly different from those caused by the inoculation of serum from calves not showing nervous signs and from control calves. The effect was particularly evident in female mice. At this dosage severe neurological signs such as loss of righting reflex, seizures and death occurred only with serum from calves with "nervous coccidiosis". The results suggest that serum from the calves with neurological signs contains a neurotoxin. This toxin appears to be highly labile. It was not present in the cerebrospinal fluid at levels comparable to those in the serum. The significance of this labile neurotoxin with respect to the pathogenesis of the neurological signs associated with bovine enteric coccidiosis is unknown. PMID:2955865

  16. Pharmacological ascorbate and ionizing radiation (IR) increase labile iron in pancreatic cancer.

    PubMed

    Moser, Justin C; Rawal, Malvika; Wagner, Brett A; Du, Juan; Cullen, Joseph J; Buettner, Garry R

    2013-01-01

    Labile iron, i.e. iron that is weakly bound and is relatively unrestricted in its redox activity, has been implicated in both the pathogenesis as well as treatment of cancer. Two cancer treatments where labile iron may contribute to their mechanism of action are pharmacological ascorbate and ionizing radiation (IR). Pharmacological ascorbate has been shown to have tumor-specific toxic effects due to the formation of hydrogen peroxide. By catalyzing the oxidation of ascorbate, labile iron can enhance the rate of formation of hydrogen peroxide; labile iron can also react with hydrogen peroxide. Here we have investigated the magnitude of the labile iron pool in tumor and normal tissue. We also examined the ability of pharmacological ascorbate and IR to change the size of the labile iron pool. Although a significant amount of labile iron was seen in tumors (MIA PaCa-2 cells in athymic nude mice), higher levels were seen in murine tissues that were not susceptible to pharmacological ascorbate. Pharmacological ascorbate and irradiation were shown to increase the labile iron in tumor homogenates from this murine model of pancreatic cancer. As both IR and pharmacological ascorbate may rely on labile iron for their effects on tumor tissues, our data suggest that pharmacological ascorbate could be used as a radio-sensitizing agent for some radio-resistant tumors.

  17. Design strategies for development of SCR catalyst: improvement of alkali poisoning resistance and novel regeneration method.

    PubMed

    Peng, Yue; Li, Junhua; Shi, Wenbo; Xu, Jiayu; Hao, Jiming

    2012-11-20

    Based on the ideas of the additives modification and regeneration method update, two different strategies were designed to deal with the traditional SCR catalyst poisoned by alkali metals. First, ceria doping on the V(2)O(5)-WO(3)/TiO(2) catalyst could promote the SCR performance even reducing the V loading, which resulted in the enhancement of the catalyst's alkali poisoning resistance. Then, a novel method, electrophoresis treatment, was employed to regenerate the alkali poisoned V(2)O(5)-WO(3)/TiO(2) catalyst. This novel technique could dramatically enhance the SCR activities of the alkali poisoned catalysts by removing approximately 95% K or Na ions from the catalyst and showed less hazardous to the environment. Finally, the deactivation mechanisms by the alkali metals were extensively studied by employing both the experimental and DFT theoretical approaches. Alkali atom mainly influences the active site V species rather than W oxides. The decrease of catalyst surface acidity might directly reduce the catalytic activity, while the reducibility of catalysts could be another important factor.

  18. The effects of potassium and rubidium hydroxide on the alkali-silica reaction

    SciTech Connect

    Shomglin, K.; Turanli, L.; Wenk, H.-R.; Monteiro, P.J.M.; Sposito, G

    2003-11-01

    Expansion of mortar specimens prepared with an aggregate of mylonite from the Santa Rosa mylonite zone in southern California was studied to investigate the effect of different alkali ions on the alkali-silica reaction in concrete. The expansion tests indicate that mortar has a greater expansion when subjected to a sodium hydroxide bath than in a sodium-potassium-rubidium hydroxide bath. Electron probe microanalysis (EPMA) of mortar bars at early ages show that rubidium ions, used as tracer, were present throughout the sample by the third day of exposure. The analysis also shows a high concentration of rubidium in silica gel from mortar bars exposed to bath solutions containing rubidium. The results suggest that expansion of mortar bars using ASTM C 1260 does not depend on the diffusion of alkali ions. The results indicate that the expansion of alkali-silica gel depends on the type of alkali ions present. Alkali-silica gel containing rubidium shows a lower concentration of calcium, suggesting competition for the same sites.

  19. Measurement of alkali in PFBC exhaust

    SciTech Connect

    Schmalzer, D.K.; Steindler, M.J.; Lee, S.H.D.; Swift, W.M.

    1992-12-01

    This project supports the DOE/METC Fossil Energy Program for the development of Pressurized fluidized bed combustion (PFBC) technology. Based on the analytical activated-bauxite sorber-bed technique, we are developing the RABSAM as an alternative to the on-line alkali analyzer for field application. RABSAM is a sampling probe containing a regenerable activated-bauxite adsorbent (RABA). It can be inserted directly into the PFBC exhaust duct and requires no high temperature/high pressure (HTHP) sampling line. Alkali vapors are captured by the adsorbent purely through physical adsorption. The adsorbent is regenerated by a simple water-reaching process, which also recovers the adsorbed alkalis. The alkali analysis of the leachate by atomic absorption (AA) provides a basis for calculating the time-averaged alkali-vapor concentration in the PFBC exhaust. If the RABA is to use commercial-grade activated bauxite, the clay impurities in activated bauxite can react with alkali vapors and, therefore, need to be either removed or deactivated. In earlier work, a 6{und M}-LiCl-solution impregnation technique was shown to deactivate these impurities in fresh activated bauxite. During this year, RABA prepared by this technique was tested in a pressurized alkali-vapor sorption test unit to determine its NaCl-vapor capture efficiency and the regenerability of the sorbent by water extraction. Results of this study are presented and discussed in the following.

  20. Measurement of alkali in PFBC exhaust

    SciTech Connect

    Schmalzer, D.K.; Steindler, M.J.; Lee, S.H.D.; Swift, W.M.

    1992-01-01

    This project supports the DOE/METC Fossil Energy Program for the development of Pressurized fluidized bed combustion (PFBC) technology. Based on the analytical activated-bauxite sorber-bed technique, we are developing the RABSAM as an alternative to the on-line alkali analyzer for field application. RABSAM is a sampling probe containing a regenerable activated-bauxite adsorbent (RABA). It can be inserted directly into the PFBC exhaust duct and requires no high temperature/high pressure (HTHP) sampling line. Alkali vapors are captured by the adsorbent purely through physical adsorption. The adsorbent is regenerated by a simple water-reaching process, which also recovers the adsorbed alkalis. The alkali analysis of the leachate by atomic absorption (AA) provides a basis for calculating the time-averaged alkali-vapor concentration in the PFBC exhaust. If the RABA is to use commercial-grade activated bauxite, the clay impurities in activated bauxite can react with alkali vapors and, therefore, need to be either removed or deactivated. In earlier work, a 6[und M]-LiCl-solution impregnation technique was shown to deactivate these impurities in fresh activated bauxite. During this year, RABA prepared by this technique was tested in a pressurized alkali-vapor sorption test unit to determine its NaCl-vapor capture efficiency and the regenerability of the sorbent by water extraction. Results of this study are presented and discussed in the following.

  1. Measurement of alkali in PFBC exhaust

    SciTech Connect

    Lee, S.H.D.; Swift, W.M.

    1992-01-01

    This project supports the DOE/METC Fossil Energy Program for the development of PFBC technology. Based on the analytical activated-bauxite sorber-bed technique, we are developing the RABSAM as an altemative to the on-line alkali analyzer for field application. As shown in Fig. 1, the RABSAM is a sampling probe containing a regenerable activated-bauxite adsorbent (RABA). It can be inserted directly into the PFBC exhaust duct and requires no HTHP sampling line. Alkali vapors are captured by the adsorbent purely through physical adsorption. The adsorbent is regenerated by a simple water-leaching process, which also recovers the adsorbed alkalis. The alkali analysis of the leachate by atomic absorption (AA) provides a basis for calculating the time-averaged alkali-vapor concentration in the PFBC exhaust. If the RABA is to use commercial grade activated bauxite, the clay impurities in activated bauxite can react with alkali vapors and, therefore, need to be either removed or deactivated. In earlier work, a 6M-LiCl-solution impregnation technique was shown to deactivate these impurities in fresh activated bauxite [8]. During this year, RABA prepared by this technique was tested in a pressurized alkali-vapor sorption test unit to determine its NaCl-vapor capture efficiency and the regenerability of the sorbent by water extraction. Results of this study are presented and discussed.

  2. Measurement of alkali in PFBC exhaust

    SciTech Connect

    Lee, S.H.D.; Swift, W.M.

    1992-11-01

    This project supports the DOE/METC Fossil Energy Program for the development of PFBC technology. Based on the analytical activated-bauxite sorber-bed technique, we are developing the RABSAM as an altemative to the on-line alkali analyzer for field application. As shown in Fig. 1, the RABSAM is a sampling probe containing a regenerable activated-bauxite adsorbent (RABA). It can be inserted directly into the PFBC exhaust duct and requires no HTHP sampling line. Alkali vapors are captured by the adsorbent purely through physical adsorption. The adsorbent is regenerated by a simple water-leaching process, which also recovers the adsorbed alkalis. The alkali analysis of the leachate by atomic absorption (AA) provides a basis for calculating the time-averaged alkali-vapor concentration in the PFBC exhaust. If the RABA is to use commercial grade activated bauxite, the clay impurities in activated bauxite can react with alkali vapors and, therefore, need to be either removed or deactivated. In earlier work, a 6M-LiCl-solution impregnation technique was shown to deactivate these impurities in fresh activated bauxite [8]. During this year, RABA prepared by this technique was tested in a pressurized alkali-vapor sorption test unit to determine its NaCl-vapor capture efficiency and the regenerability of the sorbent by water extraction. Results of this study are presented and discussed.

  3. Alkali-stable high-pI isoelectric membranes for isoelectric trapping separations.

    PubMed

    Lalwani, Sanjiv; Shave, Evan; Fleisher, Helen C; Nzeadibe, Kingsley; Busby, M Brent; Vigh, Gyula

    2004-07-01

    Alkali-stable, high-pI isoelectric membranes have been synthesized from quaternary ammonium derivatives of cyclodextrins and poly(vinyl alcohol), and bifunctional cross-linkers, such as glycerol-1,3-diglycidyl ether. The new, high-pI isoelectric membranes were successfully applied as cathodic membranes in isoelectric trapping separations in place of the hydrolytically more labile, polyacrylamide-based cathodic isoelectric membranes, and permitted the use of catholytes as alkaline as 1 M NaOH. The new high-pI isoelectric membranes have shown excellent mechanical stability, low electric resistance and long life times, even when subjected to electrophoresis with current densities as high as 80 mA/cm2.

  4. Diode pumped alkali vapor fiber laser

    DOEpatents

    Payne, Stephen A.; Beach, Raymond J.; Dawson, Jay W.; Krupke, William F.

    2006-07-26

    A method and apparatus is provided for producing near-diffraction-limited laser light, or amplifying near-diffraction-limited light, in diode pumped alkali vapor photonic-band-gap fiber lasers or amplifiers. Laser light is both substantially generated and propagated in an alkali gas instead of a solid, allowing the nonlinear and damage limitations of conventional solid core fibers to be circumvented. Alkali vapor is introduced into the center hole of a photonic-band-gap fiber, which can then be pumped with light from a pump laser and operated as an oscillator with a seed beam, or can be configured as an amplifier.

  5. Diode pumped alkali vapor fiber laser

    DOEpatents

    Payne, Stephen A.; Beach, Raymond J.; Dawson, Jay W.; Krupke, William F.

    2007-10-23

    A method and apparatus is provided for producing near-diffraction-limited laser light, or amplifying near-diffraction-limited light, in diode pumped alkali vapor photonic-band-gap fiber lasers or amplifiers. Laser light is both substantially generated and propagated in an alkali gas instead of a solid, allowing the nonlinear and damage limitations of conventional solid core fibers to be circumvented. Alkali vapor is introduced into the center hole of a photonic-band-gap fiber, which can then be pumped with light from a pump laser and operated as an oscillator with a seed beam, or can be configured as an amplifier.

  6. Advancements in flowing diode pumped alkali lasers

    NASA Astrophysics Data System (ADS)

    Pitz, Greg A.; Stalnaker, Donald M.; Guild, Eric M.; Oliker, Benjamin Q.; Moran, Paul J.; Townsend, Steven W.; Hostutler, David A.

    2016-03-01

    Multiple variants of the Diode Pumped Alkali Laser (DPAL) have recently been demonstrated at the Air Force Research Laboratory (AFRL). Highlights of this ongoing research effort include: a) a 571W rubidium (Rb) based Master Oscillator Power Amplifier (MOPA) with a gain (2α) of 0.48 cm-1, b) a rubidium-cesium (Cs) Multi-Alkali Multi-Line (MAML) laser that simultaneously lases at both 795 nm and 895 nm, and c) a 1.5 kW resonantly pumped potassium (K) DPAL with a slope efficiency of 50%. The common factor among these experiments is the use of a flowing alkali test bed.

  7. Alkali metal for ultraviolet band-pass filter

    NASA Technical Reports Server (NTRS)

    Mardesich, Nick (Inventor); Fraschetti, George A. (Inventor); Mccann, Timothy A. (Inventor); Mayall, Sherwood D. (Inventor); Dunn, Donald E. (Inventor); Trauger, John T. (Inventor)

    1993-01-01

    An alkali metal filter having a layer of metallic bismuth deposited onto the alkali metal is provided. The metallic bismuth acts to stabilize the surface of the alkali metal to prevent substantial surface migration from occurring on the alkali metal, which may degrade optical characteristics of the filter. To this end, a layer of metallic bismuth is deposited by vapor deposition over the alkali metal to a depth of approximately 5 to 10 A. A complete alkali metal filter is described along with a method for fabricating the alkali metal filter.

  8. [Labile iron pool formation in rat's blood under rhabdomyolysis].

    PubMed

    Shandrenko, S H

    2012-01-01

    The labile nonheme iron pool formation in blood under glycerol induced rhabdomyolysis in rats has been investigated. This iron is not included in transferrin, thereby it is redox-active. Rhabdomyolysis was caused by intramuscular injection of 50% glycerol in a dose of 10 ml/kg. In the first day it has been registered that the blood plasma free heme content increased 10 times and the liver heme-oxigenase activity increased 6 times. Plasma redox-active iron pool formation has been registered by EPR method. Such iron was absent in the control group. This iron pool content in the interval from the 1st to the 6st day was more than 2 mg/l and significantly higher than the transferrin iron level. The plasma iron pool unshielded by transferrin may be one of oxidative stress causes.

  9. Lability of renal papillary tissue composition in the rat.

    PubMed Central

    Atherton, J C

    1978-01-01

    1. The acute effects of (a) a minor operative procedure using ether as the anaesthetic, and (b) the administration of 0.9% saline as a single I.V. injection in the conscious rat, on renal tissue composition were studied in hydropenic and normally hydrated rats. 2. The operative procedure and anaesthesia induced a rapid and transient decrease in papillary osmolality in both hydropenic and normally hydrated animals, the important contributing factor being a significant decrease in urea content. 3. Administration of a small volume of saline caused a rapid decrease in urea content, and an increase in water content. 4. It is concluded that papillary composition is extremely labile, large changes being produced by relatively minor experimental procedures. PMID:624997

  10. Chemical leaching methods and measurements of marine labile particulate Fe

    NASA Astrophysics Data System (ADS)

    Revels, B. N.; John, S.

    2012-12-01

    Iron (Fe) is an essential nutrient for life. Yet its low solubility and concentration in the ocean limits marine phytoplankton productivity in many regions of the world. Dissolved phase Fe (<0.4μm) has traditionally been considered the most biologically accessible form, however, the particulate phase (>0.4μm) may contain an important, labile reservoir of Fe that may also be available to phytoplankton. However, concentration data alone cannot elucidate the sources of particulate Fe to the ocean and to what extent particulate iron may support phytoplankton growth. Isotopic analysis of natural particles may help to elucidate the biogeochemical cycling of Fe, though it is important to find a leaching method which accesses bioavailable Fe. Thirty-three different chemical leaches were performed on a marine sediment reference material, MESS-3. The combinations included four different acids (25% acetic acid, 0.01M HCl, 0.5M HCl, 0.1M H2SO4 at pH2), various redox conditions (0.02M hydroxylamine hydrochloride or 0.02M H2O2), three temperatures (25°C, 60°C, 90°C), and three time points (10 minutes, 2 hours, 24 hours). Leached Fe concentrations varied from 1mg/g to 35mg/g, with longer treatment times, stronger acids, and hotter temperatures generally associated with an increase in leached Fe. δ56Fe in these leaches varied from -1.0‰ to +0.2‰. Interestingly, regardless of leaching method used, there was a very similar relationship between the amount of Fe leached from the particles and the δ56Fe of this iron. Isotopically lighter δ56Fe values were associated with smaller amounts of leached Fe whereas isotopically heavier δ56Fe values were associated with larger amounts of leached Fe. Two alternate hypotheses could explain these data. Either, the particles may contain pools of isotopically light Fe that are easily accessed early in dissolution, or isotopically light Fe may be preferentially leached from the particle due to a kinetic isotope effect during dissolution

  11. The role of labile sulfur compounds in thermochemical sulfate reduction

    USGS Publications Warehouse

    Amrani, A.; Zhang, T.; Ma, Q.; Ellis, G.S.; Tang, Y.

    2008-01-01

    The reduction of sulfate to sulfide coupled with the oxidation of hydrocarbons to carbon dioxide, commonly referred to as thermochemical sulfate reduction (TSR), is an important abiotic alteration process that most commonly occurs in hot carbonate petroleum reservoirs. In the present study we focus on the role that organic labile sulfur compounds play in increasing the rate of TSR. A series of gold-tube hydrous pyrolysis experiments were conducted with n-octane and CaSO4 in the presence of reduced sulfur (e.g. H2S, S??, organic S) at temperatures of 330 and 356 ??C under a constant confining pressure. The in-situ pH was buffered to 3.5 (???6.3 at room temperature) with talc and silica. For comparison, three types of oil with different total S and labile S contents were reacted under similar conditions. The results show that the initial presence of organic or inorganic sulfur compounds increases the rate of TSR. However, organic sulfur compounds, such as 1-pentanethiol or diethyldisulfide, were significantly more effective in increasing the rate of TSR than H2S or elemental sulfur (on a mole S basis). The increase in rate is achieved at relatively low concentrations of 1-pentanethiol, less than 1 wt% of the total n-octane, which is comparable to the concentration of organic S that is common in many oils (???0.3 wt%). We examined several potential reaction mechanisms to explain the observed reactivity of organic LSC. First, the release of H2S from the thermal degradation of thiols was discounted as an important mechanism due to the significantly greater reactivity of thiol compared to an equivalent amount of H2S. Second, we considered the generation of olefines in association with the elimination of H2S during thermal degradation of thiols because olefines are much more reactive than n-alkanes during TSR. In our experiments, olefines increased the rate of TSR, but were less effective than 1-pentanethiol and other organic LSC. Third, the thermal decomposition of

  12. The role of labile sulfur compounds in thermochemical sulfate reduction

    NASA Astrophysics Data System (ADS)

    Amrani, Alon; Zhang, Tongwei; Ma, Qisheng; Ellis, Geoffrey S.; Tang, Yongchun

    2008-06-01

    The reduction of sulfate to sulfide coupled with the oxidation of hydrocarbons to carbon dioxide, commonly referred to as thermochemical sulfate reduction (TSR), is an important abiotic alteration process that most commonly occurs in hot carbonate petroleum reservoirs. In the present study we focus on the role that organic labile sulfur compounds play in increasing the rate of TSR. A series of gold-tube hydrous pyrolysis experiments were conducted with n-octane and CaSO4 in the presence of reduced sulfur (e.g. H2S, S°, organic S) at temperatures of 330 and 356 °C under a constant confining pressure. The in-situ pH was buffered to 3.5 (∼6.3 at room temperature) with talc and silica. For comparison, three types of oil with different total S and labile S contents were reacted under similar conditions. The results show that the initial presence of organic or inorganic sulfur compounds increases the rate of TSR. However, organic sulfur compounds, such as 1-pentanethiol or diethyldisulfide, were significantly more effective in increasing the rate of TSR than H2S or elemental sulfur (on a mole S basis). The increase in rate is achieved at relatively low concentrations of 1-pentanethiol, less than 1 wt% of the total n-octane, which is comparable to the concentration of organic S that is common in many oils (∼0.3 wt%). We examined several potential reaction mechanisms to explain the observed reactivity of organic LSC. First, the release of H2S from the thermal degradation of thiols was discounted as an important mechanism due to the significantly greater reactivity of thiol compared to an equivalent amount of H2S. Second, we considered the generation of olefines in association with the elimination of H2S during thermal degradation of thiols because olefines are much more reactive than n-alkanes during TSR. In our experiments, olefines increased the rate of TSR, but were less effective than 1-pentanethiol and other organic LSC. Third, the thermal decomposition of

  13. Lability criteria for successive metal complexes in steady-state planar diffusion.

    PubMed

    Salvador, José; Puy, Jaume; Galceran, Josep; Cecília, Joan; Town, Raewyn M; van Leeuwen, Herman P

    2006-01-19

    The lability of sequential metal complexes, ML, ML2, ML3, ... , up to a general 1:n metal/ligand stoichiometric ratio is considered for the case of metal ions (M) being accumulated at a surface (analytical sensor or organism). The analytical solution for the steady-state diffusion of M within a sequential complexation scheme allows quantification of the contribution from the dissociation of all of the complex species to the metal flux through the so-called lability degree, xi. A lability degree for each sequential complexation step is also defined which, due to the sequential character of the complexation scheme, depends not only on the proper kinetic constants of the given complexation step but also on the kinetics of the previous ones. When all contributions from the complexes are diffusion limited, the system is fully labile and xi=1. To provide simple lability criteria, the reaction layer approximation is extended to specifically deal with this sequential complexation scheme, so that a reaction layer thickness is defined when the existence of one particular rate-limiting step is assumed. Expressions for the classical lability parameter, L, are formulated using the reaction layer approximation. The change of the lability of the system as the diffusion layer thickness is modified is analyzed in detail. The contribution of the complex flux reflects the evolution of the system from labile to inert as the thickness of the sensor is appropriately decreased.

  14. Knowledge lability: Within-person changes in parental knowledge and their associations with adolescent problem behavior

    PubMed Central

    Lippold, Melissa A.; Fosco, Gregory; Ram, Nilam; Feinberg, Mark E.

    2015-01-01

    Higher levels of parental knowledge about youth activities has been associated with lower levels of youth risky behavior. Yet little is known about how parental knowledge fluctuates during early adolescence and how those fluctuations are associated with the development of problem behavior. We use the term lability to describe within-person fluctuations in knowledge over time with higher lability indicating greater fluctuations in knowledge from year-to-year. This longitudinal study of rural adolescents (N = 840) investigated if change in parental knowledge across four waves of data from Grades 6 to 8 is characterized by lability, and if greater lability is associated with higher youth substance use, delinquency, and internalizing problems in Grade 9. Our models indicated that only some of the variance in parental knowledge was accounted for by developmental trends. The remaining residual variance reflects within-person fluctuations around these trends, lability, plus measurement and occasion-specific error. Even controlling for level and developmental trends in knowledge, higher knowledge lability (i.e., more fluctuation) was associated with increased risk for later alcohol and tobacco use, and for girls, higher delinquency and internalizing problems. Our findings suggest that lability in parental knowledge has unique implications for adolescent outcomes. The discussion focuses on mechanisms that may link knowledge lability to substance use. Interventions may be most effective if they teach parents to consistently and predictably decrease knowledge across early adolescence. PMID:26381431

  15. Elemental composition and functional groups in soil labile organic matter fractions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Labile organic matter fractions are major components involved in nutrient cycle in soil. In this chapter, we examine three labile organic matter fraction: light fraction (LF), humic acid (HA) and fulvic acid (HA) in Alabama cotton soils (ultisol) amended with chemical fertilizer (NH4NO3) and poult...

  16. Improved alkali-metal/silicate binders

    NASA Technical Reports Server (NTRS)

    Schutt, J.

    1978-01-01

    Family of inorganic binders utilizes potassium or sodium oxide/silicate dispersion and employs high mole ratio of silicon dioxide to alkali-metal binder. Binders are stable, inexpensive, extremely water resistant, and easy to apply.

  17. Alkali Metal Handling Practices at NASA MSFC

    NASA Technical Reports Server (NTRS)

    Salvail, Patrick G.; Carter, Robert R.

    2002-01-01

    NASA Marshall Space Flight Center (MSFC) is NASA s principle propulsion development center. Research and development is coordinated and carried out on not only the existing transportation systems, but also those that may be flown in the near future. Heat pipe cooled fast fission cores are among several concepts being considered for the Nuclear Systems Initiative. Marshall Space Flight Center has developed a capability to handle high-purity alkali metals for use in heat pipes or liquid metal heat transfer loops. This capability is a low budget prototype of an alkali metal handling system that would allow the production of flight qualified heat pipe modules or alkali metal loops. The processing approach used to introduce pure alkali metal into heat pipe modules and other test articles are described in this paper.

  18. Alkali metal propellants for MPD thrusters

    NASA Technical Reports Server (NTRS)

    Polk, J. E.; Pivirotto, T. J.

    1991-01-01

    Experiments performed in the United States in the 1960s and early 1970s and in the Soviet Union with alkali metal-fuelled MPD thrusters indicate performance levels substantially better than those achieved with gaseous propellants. Cathode wear appears to be less in engines with alkali metal propellants also. A critical review of the available data indicates that the data are consistent and reliable. An analysis of testing and systems-level considerations shows that pumping requirements for testing are substantially decreased and reductions in tankage fraction can be expected. In addition, while care must be exercised in handling the alkali metals, it is not prohibitively difficult or hazardous. The greatest disadvantage seems to be the potential for spacecraft contamination, but there appear to be viable strategies for minimizing the impact of propellant deposition on spacecraft surfaces. Renewed examination of alkali metal-fuelled MPD thrusters for ambitious SEI missions is recommended.

  19. Desulfurizing Coal With an Alkali Treatment

    NASA Technical Reports Server (NTRS)

    Ravindram, M.; Kalvinskas, J. J.

    1987-01-01

    Experimental coal-desulfurization process uses alkalies and steam in fluidized-bed reactor. With highly volatile, high-sulfur bituminous coal, process removed 98 percent of pyritic sulfur and 47 percent of organic sulfur. Used in coal liquefaction and in production of clean solid fuels and synthetic liquid fuels. Nitrogen or steam flows through bed of coal in reactor. Alkalies react with sulfur, removing it from coal. Nitrogen flow fluidizes bed while heating or cooling; steam is fluidizing medium during reaction.

  20. Alteration of alkali reactive aggregates autoclaved in different alkali solutions and application to alkali-aggregate reaction in concrete

    SciTech Connect

    Lu Duyou; Xu Zhongzi; Tang Mingshu; Fournier, Benoit

    2006-06-15

    Surface alteration of typical aggregates with alkali-silica reactivity and alkali-carbonate reactivity, i.e. Spratt limestone (SL) and Pittsburg dolomitic limestone (PL), were studied by XRD and SEM/EDS after autoclaving in KOH, NaOH and LiOH solutions at 150 deg. C for 150 h. The results indicate that: (1) NaOH shows the strongest attack on both ASR and ACR aggregates, the weakest attack is with LiOH. For both aggregates autoclaved in different alkali media, the crystalline degree, morphology and distribution of products are quite different. More crystalline products are formed on rock surfaces in KOH than that in NaOH solution, while almost no amorphous product is formed in LiOH solution; (2) in addition to dedolomitization of PL in KOH, NaOH and LiOH solutions, cryptocrystalline quartz in PL involves in reaction with alkaline solution and forms typical alkali-silica product in NaOH and KOH solutions, but forms lithium silicate (Li{sub 2}SiO{sub 3}) in LiOH solution; (3) in addition to massive alkali-silica product formed in SL autoclaved in different alkaline solutions, a small amount of dolomite existing in SL may simultaneously dedolomitize and possibly contribute to expansion; (4) it is promising to use the duplex effect of LiOH on ASR and ACR to distinguish the alkali-silica reactivity and alkali-carbonate reactivity of aggregate when both ASR and ACR might coexist.

  1. Lability of trace metals in submerged soils: a column study

    NASA Astrophysics Data System (ADS)

    Nimirciag, Ramona; Ajmone-Marsan, Franco

    2013-04-01

    The reduction of Fe (III) and Mn (IV) and the decomposition of organic matter exert a great influence on the biogeochemical cycles of many trace metals and nutrients in the environment. In the particular case of intermittently submerged soils, metals associated with Fe and Mn oxides become readily available due to the reductive dissolution of Fe and Mn oxides. The effects of oxido-reductive conditions on the release of Cu and Zn from heavy metal contaminated soils and the changes in their chemical speciation were studied. Column experiments were performed, using Rhizon soil moisture samplers inserted at different heights to monitor the mobility and transport of metals in the submerged soil samples. Cu was released in solution immediately, in the first red-ox cycle, either due to the solubilization of Fe and Mn oxides, or to the oxidation of organic matter with which Cu is commonly complexed, or both. During the following reductive half-cycles, the amount of Cu extracted from the soil solution decreased. However, the concentration of Cu in the solution leached from the column, which was percolated in aerobic conditions, increased. Since in the successive red-ox cycles the Eh decreases faster and to lower values, it is possible that Cu might have been removed from pore water by sulfide precipitation during the anaerobic half-cycle and released during the aerobic half-cycle, due to the oxidation of sulfides to sulfates. The release of Zn was similar to the dissolution of Fe and Mn oxyhydroxydes, and the amount extracted by Rhizon and by leaching increased during the four red-ox cycles. The chemical fractionation of the soils was also studied and the results showed that the alternate oxidative-reductive conditions cause, in general, an increase in the lability of trace metals. While Zn speciation suffers little change, Cu showed a much higher exchangeable fraction in the submerged soils, as compared to the initial, not submerged ones. The results of this study indicate

  2. Structural Lability of Barley Stripe Mosaic Virus Virions

    PubMed Central

    Semenyuk, Pavel I.; Abashkin, Dmitry A.; Kalinina, Natalya O.; Arutyunyan, Alexsandr M.; Solovyev, Andrey G.; Dobrov, Eugeny N.

    2013-01-01

    Virions of Barley stripe mosaic virus (BSMV) were neglected for more than thirty years after their basic properties were determined. In this paper, the physicochemical characteristics of BSMV virions and virion-derived viral capsid protein (CP) were analyzed, namely, the absorption and intrinsic fluorescence spectra, circular dichroism spectra, differential scanning calorimetry curves, and size distributions by dynamic laser light scattering. The structural properties of BSMV virions proved to be intermediate between those of Tobacco mosaic virus (TMV), a well-characterized virus with rigid rod-shaped virions, and flexuous filamentous plant viruses. The BSMV virions were found to be considerably more labile than expected from their rod-like morphology and a distant sequence relation of the BSMV and TMV CPs. The circular dichroism spectra of BSMV CP subunits incorporated into the virions, but not subunits of free CP, demonstrated a significant proportion of beta-structure elements, which were proposed to be localized mostly in the protein regions exposed on the virion outer surface. These beta-structure elements likely formed during virion assembly can comprise the N- and C-terminal protein regions unstructured in the non-virion CP and can mediate inter-subunit interactions. Based on computer-assisted structure modeling, a model for BSMV CP subunit structural fold compliant with the available experimental data was proposed. PMID:23613760

  3. Continuous flow analysis of labile iron in ice-cores.

    PubMed

    Hiscock, William T; Fischer, Hubertus; Bigler, Matthias; Gfeller, Gideon; Leuenberger, Daiana; Mini, Olivia

    2013-05-07

    The important active and passive role of mineral dust aerosol in the climate and the global carbon cycle over the last glacial/interglacial cycles has been recognized. However, little data on the most important aeolian dust-derived biological micronutrient, iron (Fe), has so far been available from ice-cores from Greenland or Antarctica. Furthermore, Fe deposition reconstructions derived from the palaeoproxies particulate dust and calcium differ significantly from the Fe flux data available. The ability to measure high temporal resolution Fe data in polar ice-cores is crucial for the study of the timing and magnitude of relationships between geochemical events and biological responses in the open ocean. This work adapts an existing flow injection analysis (FIA) methodology for low-level trace Fe determinations with an existing glaciochemical analysis system, continuous flow analysis (CFA) of ice-cores. Fe-induced oxidation of N,N'-dimethyl-p-pheylenediamine (DPD) is used to quantify the biologically more important and easily leachable Fe fraction released in a controlled digestion step at pH ~1.0. The developed method was successfully applied to the determination of labile Fe in ice-core samples collected from the Antarctic Byrd ice-core and the Greenland Ice-Core Project (GRIP) ice-core.

  4. Inactivation of viruses in labile blood derivatives. II. Physical methods

    SciTech Connect

    Horowitz, B.; Wiebe, M.E.; Lippin, A.; Vandersande, J.; Stryker, M.H.

    1985-11-01

    The thermal inactivation of viruses in labile blood derivatives was evaluated by addition of marker viruses (VSV, Sindbis, Sendai, EMC) to anti-hemophilic factor (AHF) concentrates. The rate of virus inactivation at 60 degrees C was decreased by at least 100- to 700-fold by inclusion of 2.75 M glycine and 50 percent sucrose, or 3.0 M potassium citrate, additives which contribute to retention of protein biologic activity. Nonetheless, at least 10(4) infectious units of each virus was inactivated within 10 hours. Increasing the temperature from 60 to 70 or 80 degrees C caused a 90 percent or greater loss in AHF activity. An even greater decline in the rate of virus inactivation was observed on heating AHF in the lyophilized state, although no loss in AHF activity was observed after 72 hours of heating at 60 degrees C. Several of the proteins present in lyophilized AHF concentrates displayed an altered electrophoretic mobility as a result of exposure to 60 degrees C for 24 hours. Exposure of lyophilized AHF to irradiation from a cobalt 60 source resulted in an acceptable yield of AHF at 1.0, but not at 2.0, megarads. At 1 megarad, greater than or equal to 6.0 logs of VSV and 3.3 logs of Sindbis virus were inactivated.

  5. Labile aggregation stimulating substance, free fatty acids, and platelet aggregation.

    PubMed

    Gerrard, J M; White, J G; Krivit, W

    1976-01-01

    Labile aggregation stimulating substance (LASS), an intermediate produced during platelet biosynthesis of PGE2 and PGF2alpha, acts as a physiologic intercellular messenger to promote platelet aggregation and the release reaction. The activity is formed by intact cells after physiologic stimulation or can be generated from platelet membrane fractions after combination with arachidonate. In the present investigation, small amounts of polyunsaturated fatty acids added to an incubation mixture of platelet microsomes and arachidonate were found to significantly inhibit subsequent platelet aggregation. Saturated and mono-unsaturated fatty acids in the same concentrations were without effect. However, in higher concentrations mono-unsaturated fatty acids were found to be inhibitory and stearic acid was found to enhance subsequent platelet aggregation. The inhibition caused by the polyunsaturated fatty acid, linoleate, was shown to be the result of an effect on the production of LASS through an interaction with the platelet enzyme responsible for conversion of arachidonate to LASS. In contrast, stearic acid was found to enhance platelet aggregation by acting on the platelets and not directly on LASS production. The results suggest that small changes in the fatty acid composition of platelet phospholipids could significantly influence platelet reactivity.

  6. Metabolically Labile Fumarate Esters Impart Kinetic Selectivity to Irreversible Inhibitors.

    PubMed

    Zaro, Balyn W; Whitby, Landon R; Lum, Kenneth M; Cravatt, Benjamin F

    2016-12-14

    Electrophilic small molecules are an important class of chemical probes and drugs that produce biological effects by irreversibly modifying proteins. Examples of electrophilic drugs include covalent kinase inhibitors that are used to treat cancer and the multiple sclerosis drug dimethyl fumarate. Optimized covalent drugs typically inactivate their protein targets rapidly in cells, but ensuing time-dependent, off-target protein modification can erode selectivity and diminish the utility of reactive small molecules as chemical probes and therapeutics. Here, we describe an approach to confer kinetic selectivity to electrophilic drugs. We show that an analogue of the covalent Bruton's tyrosine kinase (BTK) inhibitor Ibrutinib bearing a fumarate ester electrophile is vulnerable to enzymatic metabolism on a time-scale that preserves rapid and sustained BTK inhibition, while thwarting more slowly accumulating off-target reactivity in cell and animal models. These findings demonstrate that metabolically labile electrophilic groups can endow covalent drugs with kinetic selectivity to enable perturbation of proteins and biochemical pathways with greater precision.

  7. Microscopic analysis of alkali-aggregate reaction products in a 50-year-old concrete

    SciTech Connect

    Fernandes, Isabel . E-mail: ifernand@fc.up.pt; Noronha, Fernando . E-mail: fmnoronh@fc.up.pt; Teles, Madalena . E-mail: mteles@fe.up.pt

    2004-11-15

    Fifty-year-old concrete from a large dam was examined in the scope of an investigation program concerning the properties of granite as aggregate material for concrete. Site inspection, which was developed in order to detect possible signs of deterioration of the concrete, revealed the existence of efflorescence and exudations. Scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS) analyses were attempted to identify the composition of these materials and their morphology. From the analyses, it was concluded that some of the exudations were composed by alkali-silica gel. In these samples, an interesting behavior was observed in different moments after a 3-month interval. It was noticed that the initially noncrystalline alkali-silica gel transformed into sodium-rich needles and tablets after a few months kept in a desiccator in the laboratory. Therefore, it was concluded that the materials identified corresponded to different stages of evolution of an alkali-aggregate reaction product.

  8. Alkali-Stabilized Pt-OHx Species Catalyze Low-Temperature Water-Gas Shift Reactions

    SciTech Connect

    Zhai, Y.; Pierre, D; Si, R; Deng, W; Ferrin, P; Nilekar, A; Peng, G; Herron, J; Bell, D; et. al.

    2010-01-01

    We report that alkali ions (sodium or potassium) added in small amounts activate platinum adsorbed on alumina or silica for the low-temperature water-gas shift (WGS) reaction (H{sub 2}O + CO {yields} H{sub 2} + CO{sub 2}) used for producing H{sub 2}. The alkali ion-associated surface OH groups are activated by CO at low temperatures ({approx}100 C) in the presence of atomically dispersed platinum. Both experimental evidence and density functional theory calculations suggest that a partially oxidized Pt-alkali-O{sub x}(OH){sub y} species is the active site for the low-temperature Pt-catalyzed WGS reaction. These findings are useful for the design of highly active and stable WGS catalysts that contain only trace amounts of a precious metal without the need for a reducible oxide support such as ceria.

  9. Rapid and nondestructive measurement of labile Mn, Cu, Zn, Pb and As in DGT by using field portable-XRF.

    PubMed

    Chen, Zheng; Williams, Paul N; Zhang, Hao

    2013-09-01

    The technique of diffusive gradients in thin films (DGT) is often employed to quantify labile metals in situ; however, it is a challenge to perform the measurements in-field. This study evaluated the capability of field-portable X-ray fluorescence (FP-XRF) to swiftly generate elemental speciation information with DGT. Biologically available metal ions in environmental samples passively preconcentrate in the thin films of DGT devices, providing an ideal and uniform matrix for XRF nondestructive detection. Strong correlation coefficients (r > 0.992 for Mn, Cu, Zn, Pb and As) were obtained for all elements during calibration. The limits of quantitation (LOQ) for the investigated elements of FP-XRF on DGT devices are 2.74 for Mn, 4.89 for Cu, 2.89 for Zn, 2.55 for Pb, and 0.48 for As (unit: μg cm(-2)). When Pb and As co-existed in the solution trials, As did not interfere with Pb detection when using Chelex-DGT. However, there was a significant enhancement of the Pb reading attributed to As when ferrihydrite binding gels were tested, consistent with Fe-oxyhydroxide surfaces absorbing large quantities of As. This study demonstrates the value of the FP-XRF technique to rapidly and nondestructively detect the metals accumulated in DGT devices, providing a new and simple diagnostic tool for on-site environmental monitoring of labile metals/metalloids.

  10. Isolation and evolution of labile sulfur allotropes via kinetic encapsulation in interactive porous networks

    PubMed Central

    Kitagawa, Hakuba; Ohtsu, Hiroyoshi; Cruz-Cabeza, Aurora J.; Kawano, Masaki

    2016-01-01

    The isolation and characterization of small sulfur allotropes have long remained unachievable because of their extreme lability. This study reports the first direct observation of disulfur (S2) with X-ray crystallography. Sulfur gas was kinetically trapped and frozen into the pores of two Cu-based porous coordination networks containing interactive iodide sites. Stabilization of S2 was achieved either through physisorption or chemisorption on iodide anions. One of the networks displayed shape selectivity for linear molecules only, therefore S2 was trapped and remained stable within the material at room temperature and higher. In the second network, however, the S2 molecules reacted further to produce bent-S3 species as the temperature was increased. Following the thermal evolution of the S2 species in this network using X-ray diffraction and Raman spectroscopy unveiled the generation of a new reaction intermediate never observed before, the cyclo-tri­sulfur dication (cyclo-S3 2+). It is envisaged that kinetic guest trapping in interactive crystalline porous networks will be a promising method to investigate transient chemical species. PMID:27437110

  11. An intermetallic Au24Ag20 superatom nanocluster stabilized by labile ligands.

    PubMed

    Wang, Yu; Su, Haifeng; Xu, Chaofa; Li, Gang; Gell, Lars; Lin, Shuichao; Tang, Zichao; Häkkinen, Hannu; Zheng, Nanfeng

    2015-04-08

    An intermetallic nanocluster containing 44 metal atoms, Au24Ag20(2-SPy)4(PhC≡C)20Cl2, was successfully synthesized and structurally characterized by single-crystal analysis and density funtional theory computations. The 44 metal atoms in the cluster are arranged as a concentric three-shell Au12@Ag20@Au12 Keplerate structure having a high symmetry. For the first time, the co-presence of three different types of anionic ligands (i.e., phenylalkynyl, 2-pyridylthiolate, and chloride) was revealed on the surface of metal nanoclusters. Similar to thiolates, alkynyls bind linearly to surface Au atoms using their σ-bonds, leading to the formation of two types of surface staple units (PhC≡C-Au-L, L = PhC≡C(-) or 2-pyridylthiolate) on the cluster. The co-presence of three different surface ligands allows the site-specific surface and functional modification of the cluster. The lability of PhC≡C(-) ligands on the cluster was demonstrated, making it possible to keep the metal core intact while removing partial surface capping. Moreover, it was found that ligand exchange on the cluster occurs easily to offer various derivatives with the same metal core but different surface functionality and thus different solubility.

  12. Facile Generation of Tumor-pH-Labile Linkage-Bridged Block Copolymers for Chemotherapeutic Delivery.

    PubMed

    Sun, Chun-Yang; Liu, Yang; Du, Jin-Zhi; Cao, Zhi-Ting; Xu, Cong-Fei; Wang, Jun

    2016-01-18

    Successful bench-to-bedside translation of nanomedicine relies heavily on the development of nanocarriers with superior therapeutic efficacy and high biocompatibility. However, the optimal strategy for improving one aspect often conflicts with the other. Herein, we report a tactic of designing tumor-pH-labile linkage-bridged copolymers of clinically validated poly(D,L-lactide) and poly(ethylene glycol) (PEG-Dlink(m)-PDLLA) for safe and effective drug delivery. Upon arriving at the tumor site, PEG-Dlink(m)-PDLLA nanoparticles will lose the PEG layer and increase zeta potential by responding to tumor acidity, which significantly enhances cellular uptake and improves the in vivo tumor inhibition rate to 78.1% in comparison to 47.8% of the non-responsive control. Furthermore, PEG-Dlink(m)-PDLLA nanoparticles show comparable biocompatibility with the clinically used PEG-b-PDLLA micelle. The improved therapeutic efficacy and safety demonstrate great promise for our strategy in future translational studies.

  13. DETERMINATION OF APPARENT QUANTUM YIELD SPECTRA FOR THE FORMATION OF BIOLOGICALLY LABILE PHOTOPRODUCTS

    EPA Science Inventory

    Quantum yield spectra for the photochemical formation of biologically labile photoproducts from dissolved organic matter (DOM) have not been available previously, although they would greatly facilitate attempts to model photoproduct formation rates across latitudinal, seasonal, a...

  14. Recovery of alkali metal constituents from catalytic coal conversion residues

    DOEpatents

    Soung, W.Y.

    In a coal gasification operation (32) or similar conversion process carried out in the presence of an alkali metal-containing catalyst wherein particles containing alkali metal residues are produced, alkali metal constituents are recovered from the particles by contacting them with water or an aqueous solution to remove water-soluble alkali metal constituents and produce an aqueous solution enriched in said constituents. The aqueous solution thus produced is then contacted with carbon dioxide to precipitate silicon constituents, the pH of the resultant solution is increased, preferably to a value in the range between about 12.5 and about 15.0, and the solution of increased pH is evaporated to increase the alkali metal concentration. The concentrated aqueous solution is then recycled to the conversion process where the alkali metal constituents serve as at least a portion of the alkali metal constituents which comprise the alkali metal-containing catalyst.

  15. Alkali metal vapors - Laser spectroscopy and applications

    NASA Technical Reports Server (NTRS)

    Stwalley, W. C.; Koch, M. E.

    1980-01-01

    The paper examines the rapidly expanding use of lasers for spectroscopic studies of alkali metal vapors. Since the alkali metals (lithium, sodium, potassium, rubidium and cesium) are theoretically simple ('visible hydrogen'), readily ionized, and strongly interacting with laser light, they represent ideal systems for quantitative understanding of microscopic interconversion mechanisms between photon (e.g., solar or laser), chemical, electrical and thermal energy. The possible implications of such understanding for a wide variety of practical applications (sodium lamps, thermionic converters, magnetohydrodynamic devices, new lasers, 'lithium waterfall' inertial confinement fusion reactors, etc.) are also discussed.

  16. Alkali-aggregate reaction in concrete containing high-alkali cement and granite aggregate

    SciTech Connect

    Owsiak, Z

    2004-01-01

    The paper discusses results of the research into the influence of high-alkali Portland cement on granite aggregate. The deformation of the concrete structure occurred after 18 months. The research was carried out by means of a scanning electron microscope equipped with a high-energy dispersive X-ray analyzer that allowed observation of unpolished sections of concrete bars exhibiting the cracking pattern typical of the alkali-silica reaction. Both the microscopic observation and the X-ray elemental analysis confirm the presence of alkali-silica gel and secondary ettringite in the cracks.

  17. Mineralization of organic-matter labile fragments in the humus-accumulative horizon of soddy-podzolic soil

    NASA Astrophysics Data System (ADS)

    Trofimov, S. Ya.; Lazarev, A. S.; Fokin, A. D.

    2012-12-01

    The mineralization rate of the 14C-labeled organic matter (OM) in the humus-accumulative AE horizon of a soddy-podzolic soil was determined in a laboratory experiment. The labeling was performed in a field experiment when microamounts of 14C-labeled glucose, glycine, and uracil were added to tree waste in sacks embedded in the upper layer of the forest litter. Samples containing 14C were taken from the AE horizon (above which the sacks with the labeled material were placed) 7 and 20 months after the beginning of the experiment. The soil samples were wetted to a water content corresponding to ˜80% of the total water capacity and placed in hermetic vessels containing vials with a periodically renewed alkali solution. The incubation was performed at room temperature for 3.5 months; the alkali solutions in the vials were replaced and titrated 12 times during this period. Mineralization curves were plotted from the amounts of carbon dioxide absorbed by a 0.3 N NaOH solution, which were calculated for each time interval; its 14C content was determined by the scintillation method. The experimental treatments also included the determination of the OM mineralization rate in material from the AE horizon pretreated with a heavy liquid or a heavy liquid and a 0.1 N NaOH solution. The differences between the mineralization rates of the labeled organic matter applied to the soil in the form of glucose, glycine, and uracil under the field conditions after the interaction for 7 and 20 months were revealed. The changes in the mineralization rate after the successive extraction of the labile organic matter with a heavy liquid and a 0.1 N NaOH solution were studied. It was shown that the transformation of the labeled low-molecular-weight organic compounds in the soil over 20 months included their strong inclusion into the humus composition, which was confirmed by the similar values of the mineralization constants of the native and 14C-labeled OM. In addition, the treatments with the

  18. Altered exoskeleton composition and vitellogenesis in the crustacean Gammarus sp. collected at polluted sites in the Saguenay Fjord, Quebec, Canada.

    PubMed

    Gagné, F; Blaise, C; Pellerin, J

    2005-05-01

    Gammarus sp. individuals were collected at four intertidal sites subjected to direct sources of pollution (marinas, ferry traffic, and harbors) and at one site with no direct source of pollution. Levels of vitellogenin-like proteins (Vtg), metallothioneins (MT), alkali-labile phosphates (ALPs) in proteins, and lipogenic enzyme activities (i.e., glucose-6-dehydrogenase, isocitrate dehydrogenase, and malate enzyme) were measured in whole soft tissues. In exoskeletons, levels of pH-dependent extractable protein and chitin were determined to assess the possible impacts of pollution on exoskeleton integrity and the molting process. Results show that males were consistently heavier than females regardless of site quality but that the whole-body weight of both sexes was significantly lower at polluted sites. Females displayed either induced or decreased Vtg-like proteins at polluted sites, indicating significant changes in gametogenesis activity. MT levels were not sex dependent and tended to be induced at all impacted sites. ALP levels in acetone-fractionated proteins indicate altered phosphate mobilization at some impacted sites, where females tended to display higher ALP levels. Lipogenic enzyme activities did not vary by sex but were readily increased at impacted sites, suggesting a delay in gonad maturation rates. Exoskeleton protein characteristics revealed that the proportion of chitin in exoskeletons was a lower at most impacted site, suggesting disruption of chitin and pH-dependent protein mobilization. Principal component analysis revealed that gammarids collected at affected sites displayed substantial changes in the proportion of chitin, arthropodin, sclerotin, MTs, and intermediary glucose metabolism (glucose-6-phosphate dehydrogenase, and isocitrate dehydrogenase in soft tissues) and thus suffered from disturbed gametogenesis and exoskeleton integrity.

  19. Salts of alkali metal anions and process of preparing same

    DOEpatents

    Dye, James L.; Ceraso, Joseph M.; Tehan, Frederick J.; Lok, Mei Tak

    1978-01-01

    Compounds of alkali metal anion salts of alkali metal cations in bicyclic polyoxadiamines are disclosed. The salts are prepared by contacting an excess of alkali metal with an alkali metal dissolving solution consisting of a bicyclic polyoxadiamine in a suitable solvent, and recovered by precipitation. The salts have a gold-color crystalline appearance and are stable in a vacuum at -10.degree. C. and below.

  20. Maternal emotion socialization differentially predicts third-grade children's emotion regulation and lability.

    PubMed

    Rogers, Megan L; Halberstadt, Amy G; Castro, Vanessa L; MacCormack, Jennifer K; Garrett-Peters, Patricia

    2016-03-01

    Numerous parental emotion socialization factors have been implicated as direct and indirect contributors to the development of children's emotional competence. To date, however, no study has combined parents' emotion-related beliefs, behaviors, and regulation strategies in one model to assess their cumulative-as well as unique-contributions to children's emotion regulation. We considered the 2 components that have recently been distinguished: emotion regulation and emotional lability. We predicted that mothers' beliefs about the value of and contempt for children's emotions, mothers' supportive and nonsupportive reactions to their children's emotions, as well as mothers' use of cognitive reappraisal and suppression of their own emotions would each contribute unique variance to their children's emotion regulation and lability, as assessed by children's teachers. The study sample consisted of an ethnically and socioeconomically diverse group of 165 mothers and their third-grade children. Different patterns emerged for regulation and lability: Controlling for family income, child gender, and ethnicity, only mothers' lack of suppression as a regulatory strategy predicted greater emotion regulation in children, whereas mothers' valuing of children's emotions, mothers' lack of contempt for children's emotions, mothers' use of cognitive reappraisal to reinterpret events, and mothers' lack of emotional suppression predicted less lability in children. These findings support the divergence of emotion regulation and lability as constructs and indicate that, during middle childhood, children's lability may be substantially and uniquely affected by multiple forms of parental socialization.

  1. Low Bacterial Diversity and High Labile Organic Matter Concentrations in the Sediments of the Medee Deep-Sea Hypersaline Anoxic Basin

    PubMed Central

    Akoumianaki, Ioanna; Nomaki, Hidetaka; Pachiadaki, Maria; Kormas, Konstantinos Ar.; Kitazato, Hiroshi; Tokuyama, Hidekazu

    2012-01-01

    Studies in the center and margin of the Medee Basin, a Mediterranean deep-sea hypersaline anoxic basin, and at a reference site during Penelope cruise (2007), revealed the existence of a 7 m-thick halocline, with high salinity (328 psu), and high sedimentary organic carbon and biopolymer concentrations. The 194 16S rRNA sequences retrieved were grouped into 118 unique phylotypes. Pseudomonas gessardii, dominated in the center, while 33 phylotypes were detected at the margin and 73 at the reference site. The study suggested conditions hostile to bacteria in the sediments of the Medee Basin and preservation of sedimentary labile organic matter. PMID:22504432

  2. 40 CFR 721.8900 - Substituted halogenated pyridinol, alkali salt.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ..., alkali salt. 721.8900 Section 721.8900 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.8900 Substituted halogenated pyridinol, alkali salt. (a) Chemical... as substituted halogenated pyridinols, alkali salts (PMNs P-88-1271 and P-88-1272) are subject...

  3. 40 CFR 721.5278 - Substituted naphthalenesulfonic acid, alkali salt.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ..., alkali salt. 721.5278 Section 721.5278 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.5278 Substituted naphthalenesulfonic acid, alkali salt. (a) Chemical... as a substituted naphthalenesulfonic acid, alkali salt (PMN P-95-85) is subject to reporting...

  4. 40 CFR 721.5278 - Substituted naphthalenesulfonic acid, alkali salt.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ..., alkali salt. 721.5278 Section 721.5278 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.5278 Substituted naphthalenesulfonic acid, alkali salt. (a) Chemical... as a substituted naphthalenesulfonic acid, alkali salt (PMN P-95-85) is subject to reporting...

  5. 40 CFR 721.8900 - Substituted halogenated pyridinol, alkali salt.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ..., alkali salt. 721.8900 Section 721.8900 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.8900 Substituted halogenated pyridinol, alkali salt. (a) Chemical... as substituted halogenated pyridinols, alkali salts (PMNs P-88-1271 and P-88-1272) are subject...

  6. 40 CFR 721.5278 - Substituted naphthalenesulfonic acid, alkali salt.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ..., alkali salt. 721.5278 Section 721.5278 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.5278 Substituted naphthalenesulfonic acid, alkali salt. (a) Chemical... as a substituted naphthalenesulfonic acid, alkali salt (PMN P-95-85) is subject to reporting...

  7. 40 CFR 721.5278 - Substituted naphthalenesulfonic acid, alkali salt.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ..., alkali salt. 721.5278 Section 721.5278 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.5278 Substituted naphthalenesulfonic acid, alkali salt. (a) Chemical... as a substituted naphthalenesulfonic acid, alkali salt (PMN P-95-85) is subject to reporting...

  8. 40 CFR 721.8900 - Substituted halogenated pyridinol, alkali salt.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ..., alkali salt. 721.8900 Section 721.8900 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.8900 Substituted halogenated pyridinol, alkali salt. (a) Chemical... as substituted halogenated pyridinols, alkali salts (PMNs P-88-1271 and P-88-1272) are subject...

  9. 40 CFR 721.8900 - Substituted halogenated pyridinol, alkali salt.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ..., alkali salt. 721.8900 Section 721.8900 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.8900 Substituted halogenated pyridinol, alkali salt. (a) Chemical... as substituted halogenated pyridinols, alkali salts (PMNs P-88-1271 and P-88-1272) are subject...

  10. 40 CFR 721.8900 - Substituted halogenated pyridinol, alkali salt.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ..., alkali salt. 721.8900 Section 721.8900 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.8900 Substituted halogenated pyridinol, alkali salt. (a) Chemical... as substituted halogenated pyridinols, alkali salts (PMNs P-88-1271 and P-88-1272) are subject...

  11. 40 CFR 721.5278 - Substituted naphthalenesulfonic acid, alkali salt.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ..., alkali salt. 721.5278 Section 721.5278 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.5278 Substituted naphthalenesulfonic acid, alkali salt. (a) Chemical... as a substituted naphthalenesulfonic acid, alkali salt (PMN P-95-85) is subject to reporting...

  12. 40 CFR 721.4740 - Alkali metal nitrites.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Alkali metal nitrites. 721.4740... Substances § 721.4740 Alkali metal nitrites. (a) Chemical substances and significant new use subject to reporting. (1) The category of chemical substances which are nitrites of the alkali metals (Group IA in...

  13. 40 CFR 721.4660 - Alcohol, alkali metal salt.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Alcohol, alkali metal salt. 721.4660... Substances § 721.4660 Alcohol, alkali metal salt. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance generically identified as alcohol, alkali metal salt (PMN P-91-151)...

  14. 40 CFR 721.4660 - Alcohol, alkali metal salt.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Alcohol, alkali metal salt. 721.4660... Substances § 721.4660 Alcohol, alkali metal salt. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance generically identified as alcohol, alkali metal salt (PMN P-91-151)...

  15. 40 CFR 721.1878 - Alkali metal alkyl borohydride (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Alkali metal alkyl borohydride... Specific Chemical Substances § 721.1878 Alkali metal alkyl borohydride (generic). (a) Chemical substance... alkali metal alkyl borohydride (PMN P-00-1089) is subject to reporting under this section for...

  16. 40 CFR 721.1878 - Alkali metal alkyl borohydride (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Alkali metal alkyl borohydride... Specific Chemical Substances § 721.1878 Alkali metal alkyl borohydride (generic). (a) Chemical substance... alkali metal alkyl borohydride (PMN P-00-1089) is subject to reporting under this section for...

  17. 40 CFR 721.4740 - Alkali metal nitrites.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Alkali metal nitrites. 721.4740... Substances § 721.4740 Alkali metal nitrites. (a) Chemical substances and significant new use subject to reporting. (1) The category of chemical substances which are nitrites of the alkali metals (Group IA in...

  18. 40 CFR 721.4660 - Alcohol, alkali metal salt.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Alcohol, alkali metal salt. 721.4660... Substances § 721.4660 Alcohol, alkali metal salt. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance generically identified as alcohol, alkali metal salt (PMN P-91-151)...

  19. 40 CFR 721.4740 - Alkali metal nitrites.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Alkali metal nitrites. 721.4740... Substances § 721.4740 Alkali metal nitrites. (a) Chemical substances and significant new use subject to reporting. (1) The category of chemical substances which are nitrites of the alkali metals (Group IA in...

  20. 40 CFR 721.4740 - Alkali metal nitrites.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Alkali metal nitrites. 721.4740... Substances § 721.4740 Alkali metal nitrites. (a) Chemical substances and significant new use subject to reporting. (1) The category of chemical substances which are nitrites of the alkali metals (Group IA in...

  1. 40 CFR 721.1878 - Alkali metal alkyl borohydride (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Alkali metal alkyl borohydride... Specific Chemical Substances § 721.1878 Alkali metal alkyl borohydride (generic). (a) Chemical substance... alkali metal alkyl borohydride (PMN P-00-1089) is subject to reporting under this section for...

  2. 40 CFR 721.4660 - Alcohol, alkali metal salt.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Alcohol, alkali metal salt. 721.4660... Substances § 721.4660 Alcohol, alkali metal salt. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance generically identified as alcohol, alkali metal salt (PMN P-91-151)...

  3. 40 CFR 721.1878 - Alkali metal alkyl borohydride (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Alkali metal alkyl borohydride... Specific Chemical Substances § 721.1878 Alkali metal alkyl borohydride (generic). (a) Chemical substance... alkali metal alkyl borohydride (PMN P-00-1089) is subject to reporting under this section for...

  4. 40 CFR 721.4740 - Alkali metal nitrites.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Alkali metal nitrites. 721.4740... Substances § 721.4740 Alkali metal nitrites. (a) Chemical substances and significant new use subject to reporting. (1) The category of chemical substances which are nitrites of the alkali metals (Group IA in...

  5. 40 CFR 721.1878 - Alkali metal alkyl borohydride (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Alkali metal alkyl borohydride... Specific Chemical Substances § 721.1878 Alkali metal alkyl borohydride (generic). (a) Chemical substance... alkali metal alkyl borohydride (PMN P-00-1089) is subject to reporting under this section for...

  6. 40 CFR 721.4660 - Alcohol, alkali metal salt.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Alcohol, alkali metal salt. 721.4660... Substances § 721.4660 Alcohol, alkali metal salt. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance generically identified as alcohol, alkali metal salt (PMN P-91-151)...

  7. Initial cloning and sequencing of hydHG, an operon homologous to ntrBC and regulating the labile hydrogenase activity in Escherichia coli K-12.

    PubMed Central

    Stoker, K; Reijnders, W N; Oltmann, L F; Stouthamer, A H

    1989-01-01

    To isolate genes from Escherichia coli which regulate the labile hydrogenase activity, a plasmid library was used to transform hydL mutants lacking the labile hydrogenase. A single type of gene, designated hydG, was isolated. This gene also partially restored the hydrogenase activity in hydF mutants (which are defective in all hydrogenase isoenzymes), although the low hydrogenase 1 and 2 levels were not induced. Therefore, hydG apparently regulates, specifically, the labile hydrogenase activity. Restoration of this latter activity in hydF mutants was accompanied by a proportional increase of the H2 uptake activity, suggesting a functional relationship. H2:fumarate oxidoreductase activity was not restored in complemented hydL mutants. These latter strains may therefore lack, in addition to the labile hydrogenase, a second component (provisionally designated component R), possibly an electron carrier coupling H2 oxidation to the anerobic respiratory chain. Sequence analysis showed an open reading frame of 1,314 base pairs for hydG. It was preceded by a ribosome-binding site but apparently lacked a promoter. Minicell experiments revealed a single polypeptide of approximately 50 kilodaltons. Comparison of the predicted amino acid sequence with a protein sequence data base revealed strong homology to NtrC from Klebsiella pneumoniae, a DNA-binding transcriptional activator. The 411 base pairs upstream from pHG40 contained a second open reading frame overlapping hydG by four bases. The deduced amino acid sequence showed considerable homology with the C-terminal part of NtrB. This sequence was therefore assumed to be part of a second gene, encoding the NtrB-like component, and was designated hydH. The labile hydrogenase activity in E. coli is apparently regulated by a multicomponent system analogous to the NtrB-NtrC system. This conclusion is in agreement with the results of Birkmann et al. (A. Birkmann, R. G. Sawers, and A. Böck, Mol. Gen. Genet. 210:535-542, 1987), who

  8. Alkali resistant optical coatings for alkali lasers and methods of production thereof

    DOEpatents

    Soules, Thomas F; Beach, Raymond J; Mitchell, Scott C

    2014-11-18

    In one embodiment, a multilayer dielectric coating for use in an alkali laser includes two or more alternating layers of high and low refractive index materials, wherein an innermost layer includes a thicker, >500 nm, and dense, >97% of theoretical, layer of at least one of: alumina, zirconia, and hafnia for protecting subsequent layers of the two or more alternating layers of high and low index dielectric materials from alkali attack. In another embodiment, a method for forming an alkali resistant coating includes forming a first oxide material above a substrate and forming a second oxide material above the first oxide material to form a multilayer dielectric coating, wherein the second oxide material is on a side of the multilayer dielectric coating for contacting an alkali.

  9. Computational studies of solid-state alkali conduction in rechargeable alkali-ion batteries

    SciTech Connect

    Deng, Zhi; Mo, Yifei; Ong, Shyue Ping

    2016-03-25

    The facile conduction of alkali ions in a crystal host is of crucial importance in rechargeable alkali-ion batteries, the dominant form of energy storage today. In this review, we provide a comprehensive survey of computational approaches to study solid-state alkali diffusion. We demonstrate how these methods have provided useful insights into the design of materials that form the main components of a rechargeable alkali-ion battery, namely the electrodes, superionic conductor solid electrolytes and interfaces. We will also provide a perspective on future challenges and directions. Here, the scope of this review includes the monovalent lithium- and sodium-ion chemistries that are currently of the most commercial interest.

  10. Computational studies of solid-state alkali conduction in rechargeable alkali-ion batteries

    DOE PAGES

    Deng, Zhi; Mo, Yifei; Ong, Shyue Ping

    2016-03-25

    The facile conduction of alkali ions in a crystal host is of crucial importance in rechargeable alkali-ion batteries, the dominant form of energy storage today. In this review, we provide a comprehensive survey of computational approaches to study solid-state alkali diffusion. We demonstrate how these methods have provided useful insights into the design of materials that form the main components of a rechargeable alkali-ion battery, namely the electrodes, superionic conductor solid electrolytes and interfaces. We will also provide a perspective on future challenges and directions. Here, the scope of this review includes the monovalent lithium- and sodium-ion chemistries that aremore » currently of the most commercial interest.« less

  11. Ingestion of caustic alkali farm products.

    PubMed

    Neidich, G

    1993-01-01

    Since the Poison Prevention Packaging Act took effect, the number of ingestions of caustic alkali from household products has been significantly reduced. Commercial caustic alkalis used on farms, however, were not included in this legislation. Fourteen children over a 5 year period were seen after ingestion of commercial caustic alkalis used on farms. Seven of the children had ingested liquid pipeline cleaners and seven had ingested solid agents used for a variety of reasons. Six of seven children ingesting liquid agents did so from nonoriginal containers into which the caustic had been transferred for convenience. All seven children ingesting solid agents did so from the original container. Eight of the 14 children were found to have second-degree or worse esophageal involvement. Both solid and liquid caustic agents used commercially on farms can cause significant morbidity. Development of a child-resistant container for daily transfer of liquid pipeline agents could be helpful in preventing injuries from liquid pipeline cleaners. Pediatric gastroenterologists as well as primary care physicians in rural areas should be familiar with this type of injury and should take an active role in instructing parents of children living on farms to prevent such injuries. Extension of the Poison Prevention Packaging Act to caustic alkalis used on farms needs to be considered.

  12. The Additive Coloration of Alkali Halides

    ERIC Educational Resources Information Center

    Jirgal, G. H.; and others

    1969-01-01

    Describes the construction and use of an inexpensive, vacuum furnace designed to produce F-centers in alkali halide crystals by additive coloration. The method described avoids corrosion or contamination during the coloration process. Examination of the resultant crystals is discussed and several experiments using additively colored crystals are…

  13. Cohesive Energy of the Alkali Metals.

    ERIC Educational Resources Information Center

    Poole, R. T.

    1980-01-01

    Describes a method, considered appropriate for presentation to undergraduate students in materials science and related courses, for the calculation of cohesive energies of the alkali metals. Uses a description based on the free electron model and gives results to within 0.1 eV of the experimental values. (Author/GS)

  14. Terahertz radiation in alkali vapor plasmas

    SciTech Connect

    Sun, Xuan; Zhang, X.-C.

    2014-05-12

    By taking advantage of low ionization potentials of alkali atoms, we demonstrate terahertz wave generation from cesium and rubidium vapor plasmas with an amplitude nearly one order of magnitude larger than that from nitrogen gas at low pressure (0.02–0.5 Torr). The observed phenomena are explained by the numerical modeling based upon electron tunneling ionization.

  15. Calcium-Alkali Syndrome in the Modern Era

    PubMed Central

    Patel, Ami M.; Adeseun, Gbemisola A.; Goldfarb, Stanley

    2013-01-01

    The ingestion of calcium, along with alkali, results in a well-described triad of hypercalcemia, metabolic alkalosis, and renal insufficiency. Over time, the epidemiology and root cause of the syndrome have shifted, such that the disorder, originally called the milk-alkali syndrome, is now better described as the calcium-alkali syndrome. The calcium-alkali syndrome is an important cause of morbidity that may be on the rise, an unintended consequence of shifts in calcium and vitamin D intake in segments of the population. We review the pathophysiology of the calcium-alkali syndrome. PMID:24288027

  16. Amount and Lability of Dissolved Organic Carbon Entering Arctic Streams from Landscapes Disturbed by Fire and Thermokarst Terrain, North Slope, Alaska

    NASA Astrophysics Data System (ADS)

    Larouche, J. R.; Abbott, B. W.; Jones, J.; Bowden, W. B.

    2011-12-01

    The arctic climate is warming, which will have important impacts on stream ecosystems. In the Alaskan arctic, fire frequency and thermokarst formation (permafrost degradation and collapse) have become more common. Our previous research shows that these processes have important hydrologic and biogeochemical effects on streams including increased export of inorganic nutrients and sediment, both of which alter the metabolism and nutrient dynamics of impacted streams. Another potential impact of thermokarst and fire is the increased delivery of biologically reactive dissolved organic matter (DOM) to streams. We studied how fire and thermokarst formation affect the rate of DOM delivery and the input of labile DOM to streams in arctic Alaska. Recent work in both thermokarst and fire-impacted streams suggest an increase in dissolved organic carbon (DOC) as the summer progresses. We characterized the reactivity of DOC entering streams disturbed by thermokarst and burned conditions. Initial results of DOC decomposition rates suggest that thermokarst waters contain a higher fraction of labile DOC compared to water tracks and headwater streams. During the summer of 2011, we monitored streams at the watershed and individual thermokarst feature scale for inorganic nutrients, sediment, major cations, alkalinity, and DOC concentration and lability. We characterized potential DOC lability by sampling a time series (0, 10, and 40 d) of water samples from common sources that had been inoculated initially with the same microbial community and enriched with nutrients to stimulate maximum decomposition of the DOC. Specific Ultraviolet Absorbance (SUVA) was used to characterize DOC quality as a function of aromaticity. Four of the watersheds we sampled were affected by the 2007 Anaktuvuk River Burn, one of which experienced subsequent thermokarst formation, and two watersheds are reference sites. Determining rates of DOC decomposition and the potential controlling factors from streams

  17. Alkali metal recovery from carbonaceous material conversion process

    DOEpatents

    Sharp, David W.; Clavenna, LeRoy R.; Gorbaty, Martin L.; Tsou, Joe M.

    1980-01-01

    In a coal gasification operation or similar conversion process carried out in the presence of an alkali metal-containing catalyst wherein solid particles containing alkali metal residues are produced in the gasifier or similar reaction zone, alkali metal constitutents are recovered from the particles by withdrawing and passing the particles from the reaction zone to an alkali metal recovery zone in the substantial absence of molecular oxygen and treating the particles in the recovery zone with water or an aqueous solution in the substantial absence of molecular oxygen. The solution formed by treating the particles in the recovery zone will contain water-soluble alkali metal constituents and is recycled to the conversion process where the alkali metal constituents serve as at least a portion of the alkali metal constituents which comprise the alkali metal-containing catalyst. Preventing contact of the particles with oxygen as they are withdrawn from the reaction zone and during treatment in the recovery zone avoids the formation of undesirable alkali metal constituents in the aqueous solution produced in the recovery zone and insures maximum recovery of water-soluble alkali metal constituents from the alkali metal residues.

  18. The behaviour of alkali metals in biomass conversion systems

    SciTech Connect

    Hald, P.

    1995-12-31

    Alkali metals present in biomass contribute to problems as agglomeration, deposition and corrosion. In order to reduce the problems. It is of interest to describe the behavior of alkali metals in the conversion systems. Useful tools for die description are equilibrium calculations combined with measurements of gaseous alkali metal and analyses of solid materials. A comprehensive equilibrium study has been conducted and the results organized in tables, showing which alkali metal components can be present, dependent on the temperature and the ratios alkali metal to sulphur and alkali metal to chlorine. The tables presented can be used as a catalogue, giving easy access to equilibrium results. A sampling method for die measurement of gaseous alkali metal is described and the sampling efficiency is given. The developed tools are demonstrated for a straw gasifier and a fluidized bed combustor using a coal/straw mixture as a fuel.

  19. Radio-frequency dressed lattices for ultracold alkali atoms

    NASA Astrophysics Data System (ADS)

    Sinuco-León, German A.; Garraway, Barry M.

    2015-05-01

    Ultracold atomic gases in periodic potentials are powerful platforms for exploring quantum physics in regimes dominated by many-body effects as well as for developing applications that benefit from quantum mechanical effects. Further advances face a range of challenges including the realization of potentials with lattice constants smaller than optical wavelengths as well as creating schemes for effective addressing and manipulation of single sites. In this paper we propose a dressed-based scheme for creating periodic potential landscapes for ultracold alkali atoms with the capability of overcoming such difficulties. The dressed approach has the advantage of operating in a low-frequency regime where decoherence and heating effects due to spontaneous emission do not take place. These results highlight the possibilities of atom-chip technology in the future development of quantum simulations and quantum technologies, and provide a realistic scheme for starting such an exploration.

  20. Effect of alkali lignins with different molecular weights from alkali pretreated rice straw hydrolyzate on enzymatic hydrolysis.

    PubMed

    Li, Yun; Qi, Benkun; Luo, Jianquan; Wan, Yinhua

    2016-01-01

    This study investigated the effect of alkali lignins with different molecular weights on enzymatic hydrolysis of lignocellulose. Different alkali lignins fractions, which were obtained from cascade ultrafiltration, were added into the dilute acid pretreated (DAP) and alkali pretreated (AP) rice straws respectively during enzymatic hydrolysis. The results showed that the addition of alkali lignins enhanced the hydrolysis and the enhancement for hydrolysis increased with increasing molecular weights of alkali lignins, with maximum enhancement being 28.69% for DAP and 20.05% for AP, respectively. The enhancement was partly attributed to the improved cellulase activity, and filter paper activity increased by 18.03% when adding lignin with highest molecular weight. It was found that the enhancement of enzymatic hydrolysis was correlated with the adsorption affinity of cellulase on alkali lignins, and the difference in surface charge and hydrophobicity of alkali lignins were responsible for the difference in affinity between cellulase and lignins.

  1. Mzm1 Influences a Labile Pool of Mitochondrial Zinc Important for Respiratory Function*

    PubMed Central

    Atkinson, Aaron; Khalimonchuk, Oleh; Smith, Pamela; Sabic, Hana; Eide, David; Winge, Dennis R.

    2010-01-01

    Zinc is essential for function of mitochondria as a cofactor for several matrix zinc metalloproteins. We demonstrate that a labile cationic zinc component of low molecular mass exists in the yeast mitochondrial matrix. This zinc pool is homeostatically regulated in response to the cellular zinc status. This pool of zinc is functionally important because matrix targeting of a cytosolic zinc-binding protein reduces the level of labile zinc and interferes with mitochondrial respiratory function. We identified a series of proteins that modulate the matrix zinc pool, one of which is a novel conserved mitochondrial protein designated Mzm1. Mutant mzm1Δ cells have reduced total and labile mitochondrial zinc, and these cells are hypersensitive to perturbations of the labile pool. In addition, mzm1Δ cells have a destabilized cytochrome c reductase (Complex III) without any effects on Complexes IV or V. Thus, we have established that a link exists between Complex III integrity and the labile mitochondrial zinc pool. PMID:20404342

  2. Soil Microbial and Enzymatic Responses to Complex and Labile Nutrient Inputs

    NASA Astrophysics Data System (ADS)

    Allison, S. D.; Vitousek, P. M.

    2003-12-01

    Microbial extracellular enzymes are essential for converting complex organic compounds into smaller molecules that are available for plant and microbial uptake. However, enzyme production represents a substantial resource cost for microbes, and microbes may be under selection to produce enzymes only when benefits exceed costs. We predicted that soil enzyme activities would be highest when complex substrates were abundant, but available nutrients were scarce (large potential benefit from enzyme production). We also predicted that rates of nutrient and carbon mineralization would correspond to observed shifts in enzyme activities. To test these predictions, we added insoluble and available carbon, nitrogen, and phosphorus substrates to soil incubations and measured enzyme activities, CO2 respiration, microbial biomass, and nutrient mineralization. Labile carbon additions increased respiration rates and microbial biomass, while labile nutrient additions were taken up by microbes but did not increase respiration rates. Labile carbon + nitrogen additions increased acid phosphatase activity, while labile nitrogen additions suppressed aminopeptidase activity. Insoluble nutrients caused major increases in enzyme and microbial activities only when added in combination with complementary labile nutrients (e.g. insoluble carbon + available nitrogen and phosphorus). These results indicate that microbes respond to soil nutrient status by changing patterns of extracellular enzyme production. Such changes can allow microbes to access nutrients in complex molecules, but may be limited by the availability of resources to build enzymes.

  3. Quantification of labile heme in live malaria parasites using a genetically encoded biosensor

    PubMed Central

    Abshire, James R.; Rowlands, Christopher J.; Ganesan, Suresh M.; So, Peter T. C.; Niles, Jacquin C.

    2017-01-01

    Heme is ubiquitous, yet relatively little is known about the maintenance of labile pools of this cofactor, which likely ensures its timely bioavailability for proper cellular function. Quantitative analysis of labile heme is of fundamental importance to understanding how nature preserves access to the diverse chemistry heme enables, while minimizing cellular damage caused by its redox activity. Here, we have developed and characterized a protein-based sensor that undergoes fluorescence quenching upon heme binding. By genetically encoding this sensor in the human malarial parasite, Plasmodium falciparum, we have quantified cytosolic labile heme levels in intact, blood-stage parasites. Our findings indicate that a labile heme pool (∼1.6 µM) is stably maintained throughout parasite development within red blood cells, even during a period coincident with extensive hemoglobin degradation by the parasite. We also find that the heme-binding antimalarial drug chloroquine specifically increases labile cytosolic heme, indicative of dysregulation of this homeostatic pool that may be a relevant component of the antimalarial activity of this compound class. We propose that use of this technology under various environmental perturbations in P. falciparum can yield quantitative insights into fundamental heme biology. PMID:28242687

  4. Hard exercise, affect lability, and personality among individuals with bulimia nervosa.

    PubMed

    Brownstone, Lisa M; Fitzsimmons-Craft, Ellen E; Wonderlich, Stephen A; Joiner, Thomas E; Le Grange, Daniel; Mitchell, James E; Crow, Scott J; Peterson, Carol B; Crosby, Ross D; Klein, Marjorie H; Bardone-Cone, Anna M

    2013-12-01

    The current study explores the personality traits of compulsivity (e.g., sense of orderliness and duty to perform tasks completely) and restricted expression (e.g., emotion expression difficulties) as potential moderators of the relation between affect lability and frequency of hard exercise episodes in a sample of individuals with bulimic pathology. Participants were 204 adult females recruited in five Midwestern cities who met criteria for threshold or subthreshold bulimia nervosa (BN). Compulsivity was found to significantly moderate the relation between affect lability and number of hard exercise episodes over the past 28 days, such that among those with high compulsivity, level of affect lability was associated with the number of hard exercise episodes; whereas, among those with low compulsivity, affect lability was not associated with the number of hard exercise episodes. The same pattern of findings emerged for restricted expression; however, this finding approached, but did not reach statistical significance. As such, it appears that affect lability is differentially related to hard exercise among individuals with BN depending upon the level of compulsivity and, to a more limited extent, restricted expression. These results suggest that, for individuals with BN with either compulsivity or restricted expression, focusing treatment on increasing flexibility and/or verbal expression of emotions may help in the context of intense, fluctuating affect.

  5. Geopolymers and Related Alkali-Activated Materials

    NASA Astrophysics Data System (ADS)

    Provis, John L.; Bernal, Susan A.

    2014-07-01

    The development of new, sustainable, low-CO2 construction materials is essential if the global construction industry is to reduce the environmental footprint of its activities, which is incurred particularly through the production of Portland cement. One type of non-Portland cement that is attracting particular attention is based on alkali-aluminosilicate chemistry, including the class of binders that have become known as geopolymers. These materials offer technical properties comparable to those of Portland cement, but with a much lower CO2 footprint and with the potential for performance advantages over traditional cements in certain niche applications. This review discusses the synthesis of alkali-activated binders from blast furnace slag, calcined clay (metakaolin), and fly ash, including analysis of the chemical reaction mechanisms and binder phase assemblages that control the early-age and hardened properties of these materials, in particular initial setting and long-term durability. Perspectives for future research developments are also explored.

  6. Transcriptome Analysis of Alkali Shock and Alkali Adaptation in Listeria monocytogenes 10403S

    PubMed Central

    Giotis, Efstathios S.; Muthaiyan, Arunachalam; Natesan, Senthil; Wilkinson, Brian J.; Blair, Ian S.

    2010-01-01

    Abstract Alkali stress is an important means of inactivating undesirable pathogens in a wide range of situations. Unfortunately, Listeria monocytogenes can launch an alkaline tolerance response, significantly increasing persistence of the pathogen in such environments. This study compared transcriptome patterns of alkali and nonalkali-stressed L. monocytogenes 10403S cells, to elucidate the mechanisms by which Listeria adapts and/or grows during short- or long-term alkali stress. Transcription profiles associated with alkali shock (AS) were obtained by DNA microarray analysis of midexponential cells suspended in pH 9 media for 15, 30, or 60 min. Transcription profiles associated with alkali adaptation (AA) were obtained similarly from cells grown to midexponential phase at pH 9. Comparison of AS and AA transcription profiles with control cell profiles identified a high number of differentially regulated open-reading frames in all tested conditions. Rapid (15 min) changes in expression included upregulation of genes encoding for multiple metabolic pathways (including those associated with Na+/H+ antiporters), ATP-binding cassette transporters of functional compatible solutes, motility, and virulence-associated genes as well as the σB controlled stress resistance network. Slower (30 min and more) responses to AS and adaptation during growth in alkaline conditions (AA) involved a different pattern of changes in mRNA concentrations, and genes involved in proton export. PMID:20677981

  7. Alkali metal protective garment and composite material

    DOEpatents

    Ballif, III, John L.; Yuan, Wei W.

    1980-01-01

    A protective garment and composite material providing satisfactory heat resistance and physical protection for articles and personnel exposed to hot molten alkali metals, such as sodium. Physical protection is provided by a continuous layer of nickel foil. Heat resistance is provided by an underlying backing layer of thermal insulation. Overlying outer layers of fireproof woven ceramic fibers are used to protect the foil during storage and handling.

  8. Alkali Metal Heat Pipe Life Issues

    SciTech Connect

    Reid, Robert S.

    2004-07-01

    One approach to fission power system design uses alkali metal heat pipes for the core primary heat-transfer system. Heat pipes may also be used as radiator elements or auxiliary thermal control elements. This synopsis characterizes long-life core heat pipes. References are included where information that is more detailed can be found. Specifics shown here are for demonstration purposes and do not necessarily reflect current Nasa Project Prometheus point designs. (author)

  9. Thermal positron interactions with alkali covered tungsten

    NASA Astrophysics Data System (ADS)

    Yamashita, Takashi; Iida, Shimpei; Terabe, Hiroki; Nagashima, Yasuyuki

    2016-11-01

    The branching ratios of positron reemission, positronium emission, positronium negative ion emission and capture to the surface state for thermalized positrons at polycrystalline tungsten surfaces coated with Na, K and Cs have been measured. The data shows that the ratios depend on the coverage of the alkali-metal coating. The fraction of the emitted positronium increases with the coverage of the coating up to 90%.

  10. Alkali Metal Heat Pipe Life Issues

    NASA Technical Reports Server (NTRS)

    Reid, Robert S.

    2004-01-01

    One approach to space fission power system design is predicated on the use of alkali metal heat pipes, either as radiator elements, thermal management components, or as part of the core primary heat-transfer system. This synopsis characterizes long-life core heat pipes. References are included where more detailed information can be found. Specifics shown here are for demonstrational purposes and do not necessarily reflect current Project Prometheus point designs.

  11. Petrology and geochemistry of alkali gabbronorites from Lunar Breccia 67975

    NASA Astrophysics Data System (ADS)

    James, Odette B.; Lindstrom, Marilyn M.; Flohr, Marta K.

    Clasts of an unusual type of lunar highlands igneous rock, alkali gabbronorite, have been found in Apollo 16 breccia 67975. The alkali gabbronorites form two distinct subgroups, magnesian and ferroan. Modes and bulk compositions are highly varied. The magnesian alkali gabbronorites are composed of bytownitic plagioclase (Or2-5An82-89), hypersthene (Wo3-5En49-62), augite (Wo39-42En36-44), a silica mineral, and trace Ba-rich K-feldspar. The ferroan alkali gabbronorites are composed of ternary plagioclase (Or11-22An65-74), pigeonite (Wo6-9En35-47), augite (Wo38-40En29-35), Ba-rich K-feldspar, and a silica mineral. Trace minerals in both subgroups are apatite, REE-rich whitlockite, and zircon. The magnesian and ferroan alkali gabbronorites appear to have formed by progressive differentiation of the same, or closely related, parent magmas; the compositional data indicate that these magmas were REE-rich. The ternary plagioclase is probably a high-temperature metastable phase formed during crystallization. In composition and mineralogy, the 67975 alkali gabbronorites show many similarities to Apollo 12 and 14 alkali norites, alkali gabbronorites, and alkali anorthosites, and all these rocks together constitute a distinctive alkali suite. In addition, the alkali gabbronorites show some similarities to KREEP basalts, Mg-norites, and some felsites. These data suggest genetic links between some or all of these types of pristine rocks. Two types of relationships are possible. The first is that alkali-suite rocks crystallized in plutons of KREEP basalt magma, and KREEP basalts are their extrusive equivalents. The second is that the alkali-suite rocks and some felsites all crystallized in plutons of Mg-norite parent magmas, and KREEP basalt magmas formed by remelting of these plutons. Additional studies are needed to resolve which of these hypotheses is correct.

  12. Petrology and geochemistry of alkali gabbronorites from lunar breccia 67975

    NASA Astrophysics Data System (ADS)

    James, Odette B.; Lindstrom, Marilyn M.; Flohr, Marta K.

    1987-09-01

    Clasts of an unusual type of lunar highlands igneous rock, alkali gabbronorite, have been found in Apollo 16 breccia 67975. The alkali gabbronorites form two distinct subgroups, magnesian and ferroan. Modes and bulk compositions are highly varied. The magnesian alkali gabbronorites are composed of bytownitic plagioclase (Or2-5An82-89), hypersthene (Wo3-5En49-62), augite (Wo39-42En36-44), a silica mineral, and trace Ba-rich K-feldspar. The ferroan alkali gabbronorites are composed of ternary plagioclase (Or11-22An65-74), pigeonite (Wo6-9En35-47), augite (Wo38-40En29-35), Ba-rich K-feldspar, and a silica mineral. Trace minerals in both subgroups are apatite, REE-rich whitlockite, and zircon. The magnesian and ferroan alkali gabbronorites appear to have formed by progressive differentiation of the same, or closely related, parent magmas; the compositional data indicate that these magmas were REE-rich. The ternary plagioclase is probably a high-temperature metastable phase formed during crystallization. In composition and mineralogy, the 67975 alkali gabbronorites show many similarities to Appllo 12 and 14 alkali norites, alkali gabbronorites, and alkali anorthosites, and all these rocks together constitute a distinctive alkali suite. In addition, the alkali gabbronorites, show some similarities to KREEP basalts, Mg-norites, and some felsites. These data suggest genetic links between some or all of these types of pristine rocks. Two types of relationships are possible. The first is that alkali-suite rocks crystallized in plutons of KREEP basalt magma, and KREEP basalts are their extrusive equivalents. The second is that the alkali-suite rocks and some felsites all crystallized in plutons of Mg-norite parent magmas, and KREEP basalt magmas formed by remelting of these plutons. Additional studies are needed to resolve which of these hypotheses is correct.

  13. Transport properties of alkali metal doped fullerides

    SciTech Connect

    Yadav, Daluram Yadav, Nishchhal

    2015-07-31

    We have studied the intercage interactions between the adjacent C{sub 60} cages and expansion of lattice due to the intercalation of alkali atoms based on the spring model to estimate phonon frequencies from the dynamical matrix for the intermolecular alkali-C{sub 60} phonons. We considered a two-peak model for the phonon density of states to investigate the nature of electron pairing mechanism for superconducting state in fullerides. Coulomb repulsive parameter and the electron phonon coupling strength are obtained within the random phase approximation. Transition temperature, T{sub c}, is obtained in a situation when the free electrons in lowest molecular orbital are coupled with alkali-C{sub 60} phonons as 5 K, which is much lower as compared to reported T{sub c} (20 K). The superconducting pairing is mainly driven by the high frequency intramolecular phonons and their effects enhance it to 22 K. The importance of the present study, the pressure effect and normal state transport properties are calculated within the same model leading superconductivity.

  14. Chemically induced fracturing in alkali feldspar

    NASA Astrophysics Data System (ADS)

    Scheidl, K. S.; Schaeffer, A.-K.; Petrishcheva, E.; Habler, G.; Fischer, F. D.; Schreuer, J.; Abart, R.

    2014-01-01

    Fracturing in alkali feldspar during Na+-K+ cation exchange with a NaCl-KCl salt melt was studied experimentally. Due to a marked composition dependence of the lattice parameters of alkali feldspar, any composition gradient arising from cation exchange causes coherency stress. If this stress exceeds a critical level fracturing occurs. Experiments were performed on potassium-rich gem-quality alkali feldspars with polished (010) and (001) surfaces. When the feldspar was shifted toward more sodium-rich compositions over more than about 10 mole %, a system of parallel cracks with regular crack spacing formed. The cracks have a general (h0l) orientation and do not correspond to any of the feldspar cleavages. The cracks are rather oriented (sub)-perpendicular to the direction of maximum tensile stress. The critical stress needed to initiate fracturing is about 325 MPa. The critical stress intensity factor for the propagation of mode I cracks, K Ic, is estimated as 2.30-2.72 MPa m1/2 (73-86 MPa mm1/2) from a systematic relation between characteristic crack spacing and coherency stress. An orientation mismatch of 18° between the crack normal and the direction of maximum tensile stress is ascribed to the anisotropy of the longitudinal elastic stiffness which has pronounced maxima in the crack plane and a minimum in the direction of the crack normal.

  15. Comparison of metal lability in air-dried and fresh dewatered drinking water treatment residuals.

    PubMed

    Wang, Changhui; Pei, Yuansheng; Zhao, Yaqian

    2015-01-01

    In this work, the labilities of Al, As, Ba, Be, Ca, Cd, Co, Cr, Cu, Fe, Mg, Mn, Mo, Ni, Pb, Sr, V and Zn in air-dried (for 60 days) and fresh dewatered WTRs were compared using the Toxicity Characteristic Leaching Procedure (TCLP), fractionation, in vitro digestion and a plant enrichment test. The results showed that the air-dried and fresh dewatered WTRs had different properties, e.g., organic matter composition and available nutrients. The air-dried and fresh dewatered WTRs were non-haf zardous according to the TCLP assessment method used in the United States; however, the metals in the two types of WTRs had different lability. Compared with the metals in the fresh dewatered WTRs, those in the air-dried WTRs tended to be in more stable fractions and also exhibited lower bioaccessibility and bioavailability. Therefore, air-drying can decrease the metal lability and thereby reduce the potential metal pollution risk of WTRs.

  16. The Interactive Effects of Affect Lability, Negative Urgency, and Sensation Seeking on Young Adult Problematic Drinking

    PubMed Central

    Karyadi, Kenny; Coskunpinar, Ayca; Dir, Allyson L.; Cyders, Melissa A.

    2013-01-01

    Prior studies have suggested that affect lability might reduce the risk for problematic drinking among sensation seekers by compensating for their deficiencies in emotional reactivity and among individuals high on negative urgency by disrupting stable negative emotions. Due to the high prevalence of college drinking, this study examined whether affect lability interacted with sensation seeking and negative urgency to influence college student problematic drinking. 414 college drinkers (mean age: 20, 77% female, and 74% Caucasian) from a US Midwestern University completed self-administered questionnaires online. Consistent with our hypotheses, our results indicated that the effects of sensation seeking and negative urgency on problematic drinking weakened at higher levels of affect lability. These findings emphasize the importance of considering specific emotional contexts in understanding how negative urgency and sensation seeking create risk for problematic drinking among college students. These findings might also help us better understand how to reduce problematic drinking among sensation seekers and individuals high on negative urgency. PMID:24826366

  17. A reactivity-based probe of the intracellular labile ferrous iron pool

    PubMed Central

    Spangler, Benjamin; Morgan, Charles W.; Fontaine, Shaun D.; Vander Wal, Mark N.; Chang, Christopher J.; Wells, James A.; Renslo, Adam R.

    2016-01-01

    Improved methods for studying intracellular reactive iron(II) are of significant interest for studies of iron metabolism and disease relevant changes in iron homeostasis. Here we describe a highly-selective reactivity-based probe in which Fenton-type reaction with intracellular labile iron(II) leads to unmasking of the aminonucleoside puromycin. Puromycin leaves a permanent and dose-dependent mark on treated cells that can be detected with high sensitivity and precision using the high-content, plate-based immunofluorescence assay described. Using this new probe and screening approach, we detected alteration of cellular labile iron(II) in response extracellular iron conditioning, overexpression of iron storage and/or export proteins, and post-translational regulation of iron export. Finally, we utilized this new tool to demonstrate the presence of augmented labile iron(II) pools in cancer cells as compared to non-tumorigenic cells. PMID:27376690

  18. Adaptation of the staphylococcal coagglutination technique for detection of heat-labile enterotoxin of Escherichia coli.

    PubMed Central

    Brill, B M; Wasilauskas, B L; Richardson, S H

    1979-01-01

    Protein A-containing staphylococci coated with specific antiserum were tested for heat-labile enterotoxin of Escherichia coli. The immunological cross-reactivity of E. coli heat-labile enterotoxin with Vibrio cholerae toxin (choleragen) was the basis for sensitizing stabilized suspensions of the Cowan I strain of Staphylococcus aureus with anticholeragen. Unconcentrated culture supernatant fluid containing E. coli heat-labile enterotoxin produced macroscopic agglutination when mixed with sensitized staphylococci in capillary tubes. A total of 15 toxigenic and 61 nontoxigenic isolates were tested by the staphylococcal coagglutination technique in a coded fashion and found to be in agreement with previous results of the Chinese hamster ovary cell assay and the passive immune hemolysis test. The staphylococcal coagglutination technique is simple, relatively inexpensive to perform, and requires the immunoglobulin fraction of anticholeragen as the only specific reagent. The staphylococcal coagglutination technique appears to have potential for routine use in diagnostic microbiology laboratories. Images PMID:372214

  19. Biotic and abiotic controls on diurnal fluctuations in labile soil phosphorus of a wet tropical forest.

    PubMed

    Vandecar, Karen L; Lawrence, Deborah; Wood, Tana; Oberbauer, Steven F; Das, Rishiraj; Tully, Katherine; Schwendenmann, Luitgard

    2009-09-01

    The productivity of many tropical wet forests is generally limited by bioavailable phosphorus (P). Microbial activity is a key regulator of P availability in that it determines both the supply of P through organic matter decomposition and the depletion of bioavailable P through microbial uptake. Both microbial uptake and mineralization occur rapidly, and their net effect on P availability varies with soil moisture, temperature, and soil organic matter quantity and quality. Exploring the mechanisms driving P availability at fine temporal scales can provide insight into the coupling of carbon, water, and nutrient cycles, and ultimately, the response of tropical forests to climate change. Despite the recognized importance of P cycling to the dynamics of wet tropical forests and their potential sensitivity to short-term fluctuations in bioavailable P, the diurnal pattern of P remains poorly understood. This study quantifies diurnal fluctuations in labile soil P and evaluates the importance of biotic and abiotic factors in driving these patterns. To this end, measurements of labile P were made every other hour in a Costa Rican wet tropical forest oxisol. Spatial and temporal variation in Bray-extractable P were investigated in relation to ecosystem carbon flux, soil CO2 efflux, soil moisture, soil temperature, solar radiation, and sap-flow velocity. Spatially averaged bi-hourly (every two hours) labile P ranged from 0.88 to 2.48 microg/g across days. The amplitude in labile P throughout the day was 0.61-0.82 microg/g (41-54% of mean P concentrations) and was characterized by a bimodal pattern with a decrease at midday. Labile P increased with soil CO2 efflux and soil temperature and declined with increasing sap flow and solar radiation. Together, soil CO2 efflux, soil temperature, and sap flow explained 86% of variation in labile P.

  20. Alteration of alkali reactive aggregates autoclaved in different alkali solutions and application to alkali-aggregate reaction in concrete (II) expansion and microstructure of concrete microbar

    SciTech Connect

    Lu Duyou . E-mail: duyoulu@njut.edu.cn; Mei Laibao; Xu Zhongzi; Tang Mingshu; Mo Xiangyin; Fournier, Benoit

    2006-06-15

    The effect of the type of alkalis on the expansion behavior of concrete microbars containing typical aggregate with alkali-silica reactivity and alkali-carbonate reactivity was studied. The results verified that: (1) at the same molar concentration, sodium has the strongest contribution to expansion due to both ASR and ACR, followed by potassium and lithium; (2) sufficient LiOH can completely suppress expansion due to ASR whereas it can induce expansion due to ACR. It is possible to use the duplex effect of LiOH on ASR and ACR to clarify the ACR contribution when ASR and ACR may coexist. It has been shown that a small amount of dolomite in the fine-grained siliceous Spratt limestone, which has always been used as a reference aggregate for high alkali-silica reactivity, might dedolomitize in alkaline environment and contribute to the expansion. That is to say, Spratt limestone may exhibit both alkali-silica and alkali-carbonate reactivity, although alkali-silica reactivity is predominant. Microstructural study suggested that the mechanism in which lithium controls ASR expansion is mainly due to the favorable formation of lithium-containing less-expansive product around aggregate particles and the protection of the reactive aggregate from further attack by alkalis by the lithium-containing product layer.

  1. Labile carbon concentrations are strongly linked to plant production in Arctic tussock tundra soils

    NASA Astrophysics Data System (ADS)

    Darrouzet-Nardi, A.; Weintraub, M. N.; Euskirchen, E. S.; Steltzer, H.; Sullivan, P.

    2013-12-01

    The exchange of carbon and nutrients between plants and microbes is a key determinant of carbon balance in Arctic soils. Microbes rely on labile plant carbon for the energy they need to produce enzymes that can release nutrients and less energetically favorable carbon from soil organic matter. One of the main mechanisms of carbon transfer is rhizodeposition, the exudation of labile plant carbon such as sugars from roots into the rhizosphere. Despite the importance of this flow of energy and materials from plants to microbes, there have been few attempts to quantify labile carbon pools or fluxes in Arctic soils. To improve our knowledge of labile carbon dynamics in Arctic soils, we address two basic questions: (1) What are the seasonal patterns of labile carbon concentrations? and (2) How do seasonal patterns in labile carbon correlate with plant production, microbial biomass, and soil nutrients? We measured concentrations of total reducing sugars (TRS) in the soil solution of moist acidic tussock tundra on 28 dates during the 2012 growing season in 20 plots of an early snowmelt × warming experiment. We evaluated these total reducing sugar concentrations in the context of eddy flux carbon exchange data, plant NDVI, total dissolved carbon in soils, microbial biomass, and soil nutrients. Though we did not see treatment effects of the snowmelt × warming experiment, we did observe a clear seasonal pattern in TRS concentrations in which they started low at the time of thaw, then built to a maximum value around the time of peak plant physiology in July, followed by a decline as plants senesced. We observed a clear correlation between TRS and gross primary production (GPP). NDVI values also increased with TRS concentrations during the first half of the season and then leveled off as TRS began its decline. These relationships were in contrast to labile N concentrations, which remained at low concentrations all season. Our data suggest that rhizodeposition of labile carbon

  2. Using High Performance Computing to Understand Roles of Labile and Nonlabile U(VI) on Hanford 300 Area Plume Longevity

    SciTech Connect

    Lichtner, Peter C.; Hammond, Glenn E.

    2012-07-28

    Evolution of a hexavalent uranium [U(VI)] plume at the Hanford 300 Area bordering the Columbia River is investigated to evaluate the roles of labile and nonlabile forms of U(VI) on the longevity of the plume. A high fidelity, three-dimensional, field-scale, reactive flow and transport model is used to represent the system. Richards equation coupled to multicomponent reactive transport equations are solved for times up to 100 years taking into account rapid fluctuations in the Columbia River stage resulting in pulse releases of U(VI) into the river. The peta-scale computer code PFLOTRAN developed under a DOE SciDAC-2 project is employed in the simulations and executed on ORNL's Cray XT5 supercomputer Jaguar. Labile U(VI) is represented in the model through surface complexation reactions and its nonlabile form through dissolution of metatorbernite used as a surrogate mineral. Initial conditions are constructed corresponding to the U(VI) plume already in place to avoid uncertainties associated with the lack of historical data for the waste stream. The cumulative U(VI) flux into the river is compared for cases of equilibrium and multirate sorption models and for no sorption. The sensitivity of the U(VI) flux into the river on the initial plume configuration is investigated. The presence of nonlabile U(VI) was found to be essential in explaining the longevity of the U(VI) plume and the prolonged high U(VI) concentrations at the site exceeding the EPA MCL for uranium.

  3. Method for the safe disposal of alkali metal

    DOEpatents

    Johnson, Terry R.

    1977-01-01

    Alkali metals such as those employed in liquid metal coolant systems can be safely reacted to form hydroxides by first dissolving the alkali metal in relatively inert metals such as lead or bismuth. The alloy thus formed is contacted with a molten salt including the alkali metal hydroxide and possibly the alkali metal carbonate in the presence of oxygen. This oxidizes the alkali metal to an oxide which is soluble within the molten salt. The salt is separated and contacted with steam or steam-CO.sub.2 mixture to convert the alkali metal oxide to the hydroxide. These reactions can be conducted with minimal hydrogen evolution and with the heat of reaction distributed between the several reaction steps.

  4. A Modular Control Platform for a Diode Pumped Alkali Laser

    DTIC Science & Technology

    2008-09-01

    A Modular Control Platform for a Diode Pumped Alkali Laser Joshua Shapiro, Scott W. Teare New Mexico Institute of Mining and Technology, 801 Leroy...gain media, such as is done in diode pumped alkali lasers (DPALs), has been proposed and early experiments have shown promising results. However...REPORT TYPE 3. DATES COVERED 00-00-2008 to 00-00-2008 4. TITLE AND SUBTITLE A Modular Control Platform for a Diode Pumped Alkali Laser 5a

  5. Determination of the common and rare alkalies in mineral analysis

    USGS Publications Warehouse

    Wells, R.C.; Stevens, R.E.

    1934-01-01

    Methods are described which afford a determination of each member of the alkali group and are successful in dealing with the quantities of the rare alkalies found in rocks and minerals. The procedures are relatively rapid and based chiefly on the use of chloroplatinic acid, absolute alcohol and ether, and ammonium sulfate. The percentages of all the alkalies found in a number of minerals are given.

  6. The different poisoning behaviors of various alkali metal containing compounds on SCR catalyst

    NASA Astrophysics Data System (ADS)

    Du, Xuesen; Yang, Guangpeng; Chen, Yanrong; Ran, Jingyu; Zhang, Li

    2017-01-01

    Alkali metals are poisonous to the metal oxide catalyst for NO removal. The chemical configuration of alkali containing substance and interacting temperature can affect the poisoning profile. A computational method based on Frontier Molecular Orbital analysis was proposed to determine the reacting behavior of various alkali-containing substances with SCR catalyst. The results reveal that the poisoning reactivities of various substances can be ranked as: E (MOH) > E (M2SO4) > E(MCl) > E(MNO3) > E(MHSO4). The experimental activity tests of the catalysts calcined at stepped temperatures show that NaOH can react with the catalyst below 200 °C. NaCl and NaNO3 start to react with the catalyst at a temperature between 300 and 400 °C. Unlike MOH, MCl and MNO3, which can produce volatile or decomposable species for the anions after reacting with the catalyst, M2SO4 and MHSO4 will leave both cations and anions on the catalyst surface. The sulfate ions left on the catalyst can generate active acid sites for NH3 adsorption. The experimental results also show that Na2SO4 and NaHSO4 will not lower the NO conversion. The after-reaction influences of various alkali metals were studied using theoretical and experimental methods. The theoretical results show that the acidity decreases with doping of alkali metal. Experiments show a consistent result that the NO conversion decreases as undoped >LiCl > NaCl > KCl.

  7. The interactions of sorbates with gallosilicates and alkali-metal exchanged gallosilicates

    NASA Astrophysics Data System (ADS)

    Limtrakul, J.; Kuno, M.; Treesukol, P.

    1999-11-01

    Structures, energetics and vibrational frequencies of the interaction of adsorbates with H-aluminosilicates (H-AlZ), H-gallosilicates (H-GaZ), alkali-metal exchanged aluminosilicates (X-AlZ) and alkali-metal exchanged gallosilicates (X-GaZ), where X being Li, Na, or K, have been carried out at B3LYP and HF levels of theory with 6-31G(d) as the basis set. The charge compensating alkali-metal ions can affect the catalytically active site (Si-O-T where T=Al or Ga) by weakening the Si-O, Al-O, and Ga-O bonds as compared to their anionic frameworks. Comparing the net stabilization energies, Δ ENSE, of the naked alkali-metal/H 2O adducts with those of the alkali-metal exchanged zeolite/H 2O systems, the latter amounts only to about 50% of the former, which is partly due to the destabilizing role of the negative zeolitic oxygen frameworks surrounding the cations. The interaction of sorbates with the alkali-metal exchanged gallosilicates can be employed to probe the field strength inside the catalytic frameworks as indicated by the plot of the binding energy, Δ E, versus 1/ RX-O w2, with R(X-O w) being the distance between the cationic nucleus and the oxygen atom of the adsorbate. The IR spectra of H 2O adsorbed on Na-AlZ are calculated to be 3584, 3651, and 1686 cm -1. The obtained results are in excellent agreement with the very recent experimental IR spectra of water adsorbed on Na-ZSM-5 of Zecchina et al. (J. Phys. Chem., 100 (1996) 16 484). Other important features, i.e. the correlation between Δ νOH and, Δ E, R(X-O w) , and 1/ RX-O w2, cationic size, demonstrate that the interactions of sorbates with alkali-metal exchanged gallosilicates are well approximated by electrostatic contribution.

  8. Study on alkali removal technology from coal gasification gas

    SciTech Connect

    Inai, Motoko; Kajibata, Yoshihiro; Takao, Shoichi; Suda, Masamitsu

    1999-07-01

    The authors have proposed a new coal based combined cycle power plant concept. However, there are certain technical problems that must be overcome to establish this system. Major technical problem of the system is hot corrosion of gas turbine blades caused by sulfur and alkali vapor, because of high temperature dust removal without sulfur removal from the coal gas. So the authors have conducted several fundamental studies on dry type alkali removal sorbents for the purposed of reducing the corrosion on gas turbine blades. Based on the fundamental studies the authors found preferable alkali removal sorbents, and made clear their alkali removal performance.

  9. Electrochemical devices utilizing molten alkali metal electrode-reactant

    DOEpatents

    Hitchcock, David C.; Mailhe, Catherine C.; De Jonghe, Lutgard C.

    1986-01-01

    Electrochemical cells are provided with a reactive metal to reduce the oxide of the alkali metal electrode-reactant. Cells employing a molten alkali metal electrode, e.g., sodium, in contact with a ceramic electrolyte, which is a conductor of the ions of the alkali metal forming the electrode, exhibit a lower resistance when a reactive metal, e.g., vanadium, is allowed to react with and reduce the alkali metal oxide. Such cells exhibit less degradation of the electrolyte and of the glass seals often used to joining the electrolyte to the other components of the cell under cycling conditions.

  10. Electrochemical devices utilizing molten alkali metal electrode-reactant

    DOEpatents

    Hitchcock, D.C.; Mailhe, C.C.; De Jonghe, L.C.

    1985-07-10

    Electrochemical cells are provided with a reactive metal to reduce the oxide of the alkali metal electrode-reactant. Cells employing a molten alkali metal electrode, e.g., sodium, in contact with a ceramic electrolyte, which is a conductor of the ions of the alkali metal forming the electrode, exhibit a lower resistance when a reactive metal, e.g., vanadium, is allowed to react with and reduce the alkali metal oxide. Such cells exhibit less degradation of the electrolyte and of the glass seals often used to joining the electrolyte to the other components of the cell under cycling conditions.

  11. Changes in lead and zinc lability during weathering-induced acidification of desert mine tailings: Coupling chemical and micro-scale analyses

    PubMed Central

    Hayes, Sarah M.; White, Scott A.; Thompson, Thomas L.; Maier, Raina M.; Chorover, Jon

    2009-01-01

    Desert mine tailings may accumulate toxic metals in the near surface centimeters because of low water through-flux rates. Along with other constraints, metal toxicity precludes natural plant colonization even over decadal time scales. Since unconsolidated particles can be subjected to transport by wind and water erosion, potentially resulting in direct human and ecosystem exposure, there is a need to know how the lability and form of metals change in the tailings weathering environment. A combination of chemical extractions, X-ray diffraction, micro-X-ray fluorescence spectroscopy, and micro-Raman spectroscopy were employed to study Pb and Zn contamination in surficial arid mine tailings from the Arizona Klondyke State Superfund Site. Initial site characterization indicated a wide range in pH (2.5 to 8.0) in the surficial tailings pile. Ligand-promoted (DTPA) extractions, used to assess plant-available metal pools, showed decreasing available Zn and Mn with progressive tailings acidification. Aluminum shows the inverse trend, and Pb and Fe show more complex pH dependence. Since the tailings derive from a common source and parent mineralogy, it is presumed that variations in pH and “bioavailable” metal concentrations result from associated variation in particle-scale geochemistry. Four sub-samples, ranging in pH from 2.6 to 5.4, were subjected to further characterization to elucidate micro-scale controls on metal mobility. With acidification, total Pb (ranging from 5 – 13 g kg−1) was increasingly associated with Fe and S in plumbojarosite aggregates. For Zn, both total (0.4 – 6 g kg−1) and labile fractions decreased with decreasing pH. Zinc was found to be primarily associated with the secondary Mn phases manjiroite and chalcophanite. The results suggest that progressive tailings acidification diminishes the overall lability of the total Pb and Zn pools. PMID:20161492

  12. Non-labile silver species in biosolids remain stable throughout 50 years of weathering and ageing.

    EPA Science Inventory

    Increasing commercial use of nanosilver has focussed attention on the fate of silver (Ag) in the wastewater release pathway. This paper reports the speciation and lability of Ag in archived, stockpiled, and contemporary biosolids from the UK, USA and Australia, and indicates that...

  13. Occurrence and abundance of carbohydrates and amino compounds in sequentially extracted labile soil organic matter fractions.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study aimed to investigate the content of carbohydrates and amino compounds in three labile fraction of soil organic matter (SOM). Soil samples were collected from two agricultural fields in southern Italy and the light fraction (LF), the 500–53-µm particulate organic matter (POM) and the mobil...

  14. Endocrine correlates of personality traits: a comparison between emotionally stable and emotionally labile healthy young men.

    PubMed

    Adler, L; Wedekind, D; Pilz, J; Weniger, G; Huether, G

    1997-01-01

    An initial sample of 120 healthy young men was screened by a personality questionnaire and 15 subjects each with highest and lowest scores respectively on emotionality (emotionally labile, EL subjects and emotionally stable, ES subjects) were recruited for a study on the relationship between the degree of emotionality and the basal secretion of stress-sensitive hormones during night-time. The nocturnal urinary excretion of cortisol, testosterone, adrenaline, noradrenaline and melatonin was measured over a period of 5 consecutive nights. The average amounts of each hormone excreted per night were not different between the two extreme groups. The variability of the excretion during the 5 nights of cortisol and testosterone, but not of adrenaline, noradrenaline and melatonin, was significantly higher in EL compared to ES subjects. The larger fluctuations in the nocturnal secretion of these two (and no other) hormones in EL subjects indicate that emotional lability is associated with a more labile regulation of cortisol and testosterone secretion. The observed intraindividual variability of basal stress hormone secretion may contribute to the vast interindividual variability noticed in psychoneuroendocrine stress research, especially in emotionally labile subjects.

  15. (abstract) Fundamental Mechanisms of Electrode Kinetics and Alkali Metal Atom Transport at the Alkali Beta'-Alumina/Porous Electrode/Alkali Metal Vapor Three Phase Boundary

    NASA Technical Reports Server (NTRS)

    Williams, R. M.; Jeffries-Nakamura, B.; Ryan, M. A.; Underwood, M. L.; O'Connor, D.; Kisor, A.; Kikkert, S. K.

    1993-01-01

    The mechanisms of electrode kinetics and mass transport of alkali metal oxidation and alkali metal cation reduction at the solid electrolyte/porous electrode boundary as well as alkali metal transport through porous metal electrodes has important applications in optimizing device performance in alkali metal thermal to electric converter (AMTEC) cells which are high temperature, high current density electrochemical cells. Basic studies of these processes also affords the opportunity to investigate a very basic electrochemical reaction over a wide range of conditions; and a variety of mass transport modes at high temperatures via electrochemical techniques. The temperature range of these investigations covers 700K to 1240K; the alkali metal vapor pressures range from about 10(sup -2) to 10(sup 2) Pa; and electrodes studied have included Mo, W, Mo/Na(sub 2)MoO(sub 4), W/Na(sub 2)WO(sub 4), WPt(sub x), and WRh(sub x) (1.0 < x < 6.0 ) with Na at Na-beta'-alumina, and Mo with K at K-beta'-alumina. Both liquid metal/solid electrolyte/alkali metal vapor and alkali metal vapor/solid electrolyte/vapor cells have been used to characterize the reaction and transport processes. We have previously reported evidence of ionic, free molecular flow, and surface transport of sodium in several types of AMTEC electrodes.

  16. Alkali Halide Nanotubes: Structure and Stability

    PubMed Central

    Fernandez-Lima, Francisco A.; Henkes, Aline Verônica; da Silveira, Enio F.; Nascimento, Marco Antonio Chaer

    2013-01-01

    Accurate density functional theory (DFT) and coupled-cluster (CCSD) calculations on a series of (LiF)n=2,36 neutral clusters suggest that nanotube structures with hexagonal and octagonal transversal cross sections show stability equal to or greater than that of the typical cubic form of large LiF crystals. The nanotube stability was further corroborated by quantum dynamic calculations at room temperature. The fact that stable nanotube structures were also found for other alkali halides (e.g., NaCl and KBr) suggests that this geometry may be widely implemented in material sciences. PMID:24376901

  17. Cathode architectures for alkali metal / oxygen batteries

    DOEpatents

    Visco, Steven J; Nimon, Vitaliy; De Jonghe, Lutgard C; Volfkovich, Yury; Bograchev, Daniil

    2015-01-13

    Electrochemical energy storage devices, such as alkali metal-oxygen battery cells (e.g., non-aqueous lithium-air cells), have a cathode architecture with a porous structure and pore composition that is tailored to improve cell performance, especially as it pertains to one or more of the discharge/charge rate, cycle life, and delivered ampere-hour capacity. A porous cathode architecture having a pore volume that is derived from pores of varying radii wherein the pore size distribution is tailored as a function of the architecture thickness is one way to achieve one or more of the aforementioned cell performance improvements.

  18. Intensity Scaling for Diode Pumped Alkali Lasers

    DTIC Science & Technology

    2012-01-01

    unphased diode lasers is absorbed in the near IR by atomic potassium, rubidium , or cesium. The gain cell for a DPAL system using a heat pipe design is...demonstrated linear scaling of a rubidium laser to 32 times threshold.3 In our present work, we explore scaling to pump in- tensities of >100kW/cm2. The...of output power. Each alkali atom in the laser medium may be required to cycle as many as 1010 pump photons per second. We demonstrated a rubidium

  19. High power diode pumped alkali vapor lasers

    NASA Astrophysics Data System (ADS)

    Zweiback, J.; Krupke, B.

    2008-05-01

    Diode pumped alkali lasers have developed rapidly since their first demonstration. These lasers offer a path to convert highly efficient, but relatively low brightness, laser diodes into a single high power, high brightness beam. General Atomics has been engaged in the development of DPALs with scalable architectures. We have examined different species and pump characteristics. We show that high absorption can be achieved even when the pump source bandwidth is several times the absorption bandwidth. In addition, we present experimental results for both potassium and rubidium systems pumped with a 0.2 nm bandwidth alexandrite laser. These data show slope efficiencies of 67% and 72% respectively.

  20. Electrodes For Alkali-Metal Thermoelectric Converters

    NASA Technical Reports Server (NTRS)

    Williams, Roger M.; Wheeler, Bob L.; Jeffries-Nakamura, Barbara; Lamb, James L.; Bankston, C. Perry; Cole, Terry

    1989-01-01

    Combination of thin, porous electrode and overlying collector grid reduces internal resistance of alkali-metal thermoelectric converter cell. Low resistance of new electrode and grid boosts power density nearly to 1 W/cm2 of electrode area at typical operating temperatures of 1,000 to 1,300 K. Conductive grid encircles electrode film on alumina tube. Bus wire runs along tube to collect electrical current from grid. Such converters used to transform solar, nuclear, and waste heat into electric power.

  1. Using isotopic dilution to assess chemical extraction of labile Ni, Cu, Zn, Cd and Pb in soils.

    PubMed

    Garforth, J M; Bailey, E H; Tye, A M; Young, S D; Lofts, S

    2016-07-01

    Chemical extractants used to measure labile soil metal must ideally select for and solubilise the labile fraction, with minimal solubilisation of non-labile metal. We assessed four extractants (0.43 M HNO3, 0.43 M CH3COOH, 0.05 M Na2H2EDTA and 1 M CaCl2) against these requirements. For soils contaminated by contrasting sources, we compared isotopically exchangeable Ni, Cu, Zn, Cd and Pb (EValue, mg kg(-1)), with the concentrations of metal solubilised by the chemical extractants (MExt, mg kg(-1)). Crucially, we also determined isotopically exchangeable metal in the soil-extractant systems (EExt, mg kg(-1)). Thus 'EExt - EValue' quantifies the concentration of mobilised non-labile metal, while 'EExt - MExt' represents adsorbed labile metal in the presence of the extractant. Extraction with CaCl2 consistently underestimated EValue for Ni, Cu, Zn and Pb, while providing a reasonable estimate of EValue for Cd. In contrast, extraction with HNO3 both consistently mobilised non-labile metal and overestimated the EValue. Extraction with CH3COOH appeared to provide a good estimate of EValue for Cd; however, this was the net outcome of incomplete solubilisation of labile metal, and concurrent mobilisation of non-labile metal by the extractant (MExtEValue). The Na2H2EDTA extractant mobilised some non-labile metal in three of the four soils, but consistently solubilised the entire labile fraction for all soil-metal combinations (MExt ≈ EExt). Comparison of EValue, MExt and EExt provides a rigorous means of assessing the underlying action of soil chemical extraction methods and could be used to refine long-standing soil extraction methodologies.

  2. Glaciers as a source of ancient and labile organic matter to the marine environment.

    PubMed

    Hood, Eran; Fellman, Jason; Spencer, Robert G M; Hernes, Peter J; Edwards, Rick; D'Amore, David; Scott, Durelle

    2009-12-24

    Riverine organic matter supports of the order of one-fifth of estuarine metabolism. Coastal ecosystems are therefore sensitive to alteration of both the quantity and lability of terrigenous dissolved organic matter (DOM) delivered by rivers. The lability of DOM is thought to vary with age, with younger, relatively unaltered organic matter being more easily metabolized by aquatic heterotrophs than older, heavily modified material. This view is developed exclusively from work in watersheds where terrestrial plant and soil sources dominate streamwater DOM. Here we characterize streamwater DOM from 11 coastal watersheds on the Gulf of Alaska that vary widely in glacier coverage (0-64 per cent). In contrast to non-glacial rivers, we find that the bioavailability of DOM to marine microorganisms is significantly correlated with increasing (14)C age. Moreover, the most heavily glaciated watersheds are the source of the oldest ( approximately 4 kyr (14)C age) and most labile (66 per cent bioavailable) DOM. These glacial watersheds have extreme runoff rates, in part because they are subject to some of the highest rates of glacier volume loss on Earth. We estimate the cumulative flux of dissolved organic carbon derived from glaciers contributing runoff to the Gulf of Alaska at 0.13 +/- 0.01 Tg yr(-1) (1 Tg = 10(12) g), of which approximately 0.10 Tg is highly labile. This indicates that glacial runoff is a quantitatively important source of labile reduced carbon to marine ecosystems. Moreover, because glaciers and ice sheets represent the second largest reservoir of water in the global hydrologic system, our findings indicate that climatically driven changes in glacier volume could alter the age, quantity and reactivity of DOM entering coastal oceans.

  3. Effects of wetland recovery on soil labile carbon and nitrogen in the Sanjiang Plain.

    PubMed

    Huang, Jingyu; Song, Changchun; Nkrumah, Philip Nti

    2013-07-01

    Soil management significantly affects the soil labile organic factors. Understanding carbon and nitrogen dynamics is extremely helpful in conducting research on active carbon and nitrogen components for different kinds of soil management. In this paper, we examined the changes in microbial biomass carbon (MBC), microbial biomass nitrogen (MBN), dissolved organic carbon (DOC), and dissolved organic nitrogen (DON) to assess the effect and mechanisms of land types, organic input, soil respiration, microbial species, and vegetation recovery under Deyeuxia angustifolia freshwater marshes (DAMs) and recovered freshwater marsh (RFM) in the Sanjiang Plain, Northeast China. Identifying the relationship among the dynamics of labile carbon, nitrogen, and soil qualification mechanism using different land management practices is therefore important. Cultivation and land use affect intensely the DOC, DON, MBC, and MBN in the soil. After DAM soil tillage, the DOC, DON, MBC, and MBN at the surface of the agricultural soil layer declined significantly. In contrast, their recovery was significant in the RFM surface soil. A long time was needed for the concentration of cultivated soil total organic carbon and total nitrogen to be restored to the wetland level. The labile carbon and nitrogen fractions can reach a level similar to that of the wetland within a short time. Typical wetland ecosystem signs, such as vegetation, microbes, and animals, can be recovered by soil labile carbon and nitrogen fraction restoration. In this paper, the D. angustifolia biomass attained natural wetland level after 8 years, indicating that wetland soil labile fractions can support wetland eco-function in a short period of time (4 to 8 years) for reconstructed wetland under suitable environmental conditions.

  4. Microbial control of soil organic matter mineralization responses to labile carbon in subarctic climate change treatments.

    PubMed

    Rousk, Kathrin; Michelsen, Anders; Rousk, Johannes

    2016-12-01

    Half the global soil carbon (C) is held in high-latitude systems. Climate change will expose these to warming and a shift towards plant communities with more labile C input. Labile C can also increase the rate of loss of native soil organic matter (SOM); a phenomenon termed 'priming'. We investigated how warming (+1.1 °C over ambient using open top chambers) and litter addition (90 g m(-2)  yr(-1) ) treatments in the subarctic influenced the susceptibility of SOM mineralization to priming, and its microbial underpinnings. Labile C appeared to inhibit the mineralization of C from SOM by up to 60% within hours. In contrast, the mineralization of N from SOM was stimulated by up to 300%. These responses occurred rapidly and were unrelated to microbial successional dynamics, suggesting catabolic responses. Considered separately, the labile C inhibited C mineralization is compatible with previously reported findings termed 'preferential substrate utilization' or 'negative apparent priming', while the stimulated N mineralization responses echo recent reports of 'real priming' of SOM mineralization. However, C and N mineralization responses derived from the same SOM source must be interpreted together: This suggested that the microbial SOM-use decreased in magnitude and shifted to components richer in N. This finding highlights that only considering SOM in terms of C may be simplistic, and will not capture all changes in SOM decomposition. The selective mining for N increased in climate change treatments with higher fungal dominance. In conclusion, labile C appeared to trigger catabolic responses of the resident microbial community that shifted the SOM mining to N-rich components; an effect that increased with higher fungal dominance. Extrapolating from these findings, the predicted shrub expansion in the subarctic could result in an altered microbial use of SOM, selectively mining it for N-rich components, and leading to a reduced total SOM-use.

  5. Petrography study on altered flint aggregate by alkali-silica reaction

    SciTech Connect

    Bulteel, D. . E-mail: bulteel@ensm-douai.fr; Rafai, N.; Degrugilliers, P.; Garcia-Diaz, E.

    2004-11-15

    The aim of our study is to improve our understanding of an alkali-silica reaction (ASR) via petrography. We used a chemical concrete subsystem: flint aggregate, portlandite and KOH. The altered flint aggregate is followed by optical microscopy and scanning electron microscopy (SEM) before and after acid treatment at different intervals. After acid treatment, the observations showed an increase in aggregate porosity and revealed internal degradation of the aggregate. This degradation created amorphous zones. Before acid treatment, the analyses on polished sections by scanning electron microscopy coupled with energy dispersive spectroscopy (EDS) enabled visualization of K{sup +} and Ca{sup 2+} penetration into the aggregate. The appearance of amorphous zones and penetration of positive ions into the aggregate are correlated with the increase in the molar fraction of silanol sites. This degradation is specific to the alkali-silica reaction.

  6. Electronic states of alkali metal-NTCDA complexes: A DFT study

    NASA Astrophysics Data System (ADS)

    Tachikawa, Hiroto; Kawabata, Hiroshi

    2015-10-01

    Structures and electronic states of organic-inorganic compound of 1,4,5,8-naphthalene-tetracarboxylic-dianhydride (NTCDA) with alkali metals, Mn(NTCDA) (Mdbnd Li and Na, n = 0-2), have been investigated by means of hybrid density functional theory (DFT) calculations. From the DFT calculations, it was found that the electronic state of the complex at the ground state is characterized by a charge-transfer state expressed by (M)+(NTCDA)-. The alkali metals were bound equivalently to the carbonyl oxygen and ether oxygen atoms of NTCDA. The Cdbnd O double bond character of NTCDA was changed to a C-O single bond like character by the strong interaction of M to the Cdbnd O and O sites. This change was the origin of the red-shift of the IR spectrum. The UV-vis absorption spectra of Mn(NTCDA) were theoretically predicted on the basis of theoretical results.

  7. Chemical Approaches to Studying Labile Amino Acid Phosphorylation.

    PubMed

    Marmelstein, Alan M; Moreno, Javier; Fiedler, Dorothea

    2017-04-01

    Phosphorylation of serine, threonine, and tyrosine residues is the archetypal posttranslational modification of proteins. While phosphorylation of these residues has become standard textbook knowledge, phosphorylation of other amino acid side chains is underappreciated and minimally characterized by comparison. This disparity is rooted in the relative instability of these chemically distinct amino acid side chain moieties, namely phosphoramidates, acyl phosphates, thiophosphates, and phosphoanhydrides. In the case of the O-phosphorylated amino acids, synthetic constructs were critical to assessing their stability and developing tools for their study. As the chemical biology community has become more aware of these alternative phosphorylation sites, methodology has been developed for the synthesis of well-characterized standards and close mimics of these phosphorylated amino acids as well. In this article, we review the synthetic chemistry that is a prerequisite to progress in this field.

  8. Alkali sorber (RABSAM), September 1, 1990--August 30, 1991

    SciTech Connect

    Lee, S.H.D.; Swift, M.W.

    1991-01-01

    The objective of this work is to develop a regenerable activated-bauxite sorber alkali monitor that requires no high-temperature/high-pressure sampling line for the reliable in situ measurement of alkali-vapor concentration in the exhaust from the pressurized fluidized-bed combustion of coal. 11 refs., 2 figs., 1 tab.

  9. COMPLEX FLUORIDES OF PLUTONIUM AND AN ALKALI METAL

    DOEpatents

    Seaborg, G.T.

    1960-08-01

    A method is given for precipitating alkali metal plutonium fluorides. such as KPuF/sub 5/, KPu/sub 2/F/sub 9/, NaPuF/sub 5/, and RbPuF/sub 5/, from an aqueous plutonium(IV) solution by adding hydrogen fluoride and alkali-metal- fluoride.

  10. Formation of lysinoalanine in egg white under alkali treatment.

    PubMed

    Zhao, Yan; Luo, Xuying; Li, Jianke; Xu, Mingsheng; Tu, Yonggang

    2016-03-01

    To investigate the formation mechanism of lysinoalanine (LAL) in eggs during the alkali treatment process, NaOH was used for the direct alkali treatment of egg white, ovalbumin, and amino acids; in addition, the amount of LAL formed during the alkali treatment process was measured. The results showed that the alkali treatment resulted in the formation of LAL in the egg white. The LAL content increased with increasing pH and temperature, with the LAL content first increasing and then leveling off with increasing time. The amount of LAL formed in the ovalbumin under the alkali treatment condition accounted for approximately 50.51% to 58.68% of the amount of LAL formed in the egg white. Thus, the LAL formed in the ovalbumin was the main source for the LAL in the egg white during the alkali treatment process. Under the alkali treatment condition, free L-serine, L-cysteine, and L-cystine reacted with L-lysine to form LAL; therefore, they are the precursor amino acids of LAL formed in eggs during the alkali treatment process.

  11. [Raman spectra of endospores of Bacillus subtilis by alkali stress].

    PubMed

    Dong, Rong; Lu, Ming-qian; Li, Feng; Shi, Gui-yu; Huang, Shu-shi

    2013-09-01

    To research the lethal mechanism of spores stressed by alkali, laser tweezers Raman spectroscopy (LTRS) combined with principal components analysis (PCA) was used to study the physiological process of single spore with alkali stress. The results showed that both spores and germinated spores had tolerance with alkali in a certain range, but the ability of spores was obviously lower than that of spores due to the release of their Ca2+ -DPA which plays a key role in spores resistance as well as spores resistance to many stresses; A small amount of Ca2+ -DPA of spores was observed to release after alkali stress, however, the behavior of release was different with the normal Ca2+ -DPA release behavior induced by L-alanine; The data before and after alkali stress of the spores and g. spores with PCA reflected that alkali mainly injured the membrane of spores, and alkali could be easily enter into the inner structure of spores to damage the structure of protein backbone and injure the nucleic acid of spores. We show that the alkali could result in the small amount of Ca2+ -DPA released by destroying the member channel of spores.

  12. Self-discharge in bimetallic cells containing alkali metal

    NASA Technical Reports Server (NTRS)

    Foster, M. S.; Hesson, J. C.; Shimotake, H.

    1969-01-01

    Theoretical analysis of thermally regenerative bimetallic cells with alkali metal anodes shows a relation between the current drawn and the rate of discharge under open-circuit conditions. The self-discharge rate of the cell is due to the dissolution and ionization of alkali metal atoms in the fused-salt electrolyte

  13. Recovery of alkali metal constituents from catalytic coal conversion residues

    DOEpatents

    Soung, Wen Y.

    1984-01-01

    In a coal gasification operation (32) or similar conversion process carried out in the presence of an alkali metal-containing catalyst wherein particles containing alkali metal residues are produced, alkali metal constituents are recovered from the particles by contacting them (46, 53, 61, 69) with water or an aqueous solution to remove water-soluble alkali metal constituents and produce an aqueous solution enriched in said constituents. The aqueous solution thus produced is then contacted with carbon dioxide (63) to precipitate silicon constituents, the pH of the resultant solution is increased (81), preferably to a value in the range between about 12.5 and about 15.0, and the solution of increased pH is evaporated (84) to increase the alkali metal concentration. The concentrated aqueous solution is then recycled to the conversion process (86, 18, 17) where the alkali metal constituents serve as at least a portion of the alkali metal constituents which comprise the alkali metal-containing catalyst.

  14. Superconductivity in alkali metal intercalated iron selenides

    NASA Astrophysics Data System (ADS)

    Krzton-Maziopa, A.; Svitlyk, V.; Pomjakushina, E.; Puzniak, R.; Conder, K.

    2016-07-01

    Alkali metal intercalated iron selenide superconductors A x Fe2-y Se2 (where A  =  K, Rb, Cs, Tl/K, and Tl/Rb) are characterized by several unique properties, which were not revealed in other superconducting materials. The compounds crystallize in overall simple layered structure with FeSe layers intercalated with alkali metal. The structure turned out to be pretty complex as the existing Fe-vacancies order below ~550 K, which further leads to an antiferromagnetic ordering with Néel temperature fairly above room temperature. At even lower temperatures a phase separation is observed. While one of these phases stays magnetic down to the lowest temperatures the second is becoming superconducting below ~30 K. All these effects give rise to complex relationships between the structure, magnetism and superconductivity. In particular the iron vacancy ordering, linked with a long-range magnetic order and a mesoscopic phase separation, is assumed to be an intrinsic property of the system. Since the discovery of superconductivity in those compounds in 2010 they were investigated very extensively. Results of the studies conducted using a variety of experimental techniques and performed during the last five years were published in hundreds of reports. The present paper reviews scientific work concerning methods of synthesis and crystal growth, structural and superconducting properties as well as pressure investigations.

  15. Durability of Alkali Activated Blast Furnace Slag

    NASA Astrophysics Data System (ADS)

    Ellis, K.; Alharbi, N.; Matheu, P. S.; Varela, B.; Hailstone, R.

    2015-11-01

    The alkali activation of blast furnace slag has the potential to reduce the environmental impact of cementitious materials and to be applied in geographic zones where weather is a factor that negatively affects performance of materials based on Ordinary Portland Cement. The scientific literature provides many examples of alkali activated slag with high compressive strengths; however research into the durability and resistance to aggressive environments is still necessary for applications in harsh weather conditions. In this study two design mixes of blast furnace slag with mine tailings were activated with a potassium based solution. The design mixes were characterized by scanning electron microscopy, BET analysis and compressive strength testing. Freeze-thaw testing up to 100 freeze-thaw cycles was performed in 10% road salt solution. Our findings included compressive strength of up to 100 MPa after 28 days of curing and 120 MPa after freeze-thaw testing. The relationship between pore size, compressive strength, and compressive strength after freeze-thaw was explored.

  16. Lability of antiretroviral drug resistance mutations--correlates with immunological and virological responses.

    PubMed

    Al Mazari, Ali; Zomaya, Albert Y; Charleston, Michael; Salem, Hanan; Maher, AnnaMarie; Garsia, Roger J

    2007-07-01

    significant increase in mean CD4 cell count occurred thereafter (+242 cells/mm(3), P=0.0077). Similarly, in patients without EoR at the PR site there was no significant change in mean CD4 count during the first 36 months (-19 cells/mm(3), P=0.6647) and there was a significant increase in the last 52 months (+145 cells/mm(3), P=0.0348). The only significant decrease in mean value of VL levels occurred in patients without EoR associated with NRTIs thereafter (-1.33 log(10) copies/ml, P=0.0477), while no significant changes in mean value of VL levels in patients with/without EoR associated with any ARV drugs at any other time points (-0.65 to +0.15 log(10) copies/ml, P=0.1855 to 0.7958). Low CD4 cell counts (<250 cells/mm(3)) and high VL levels (>4.50 log(10) copies/ml) in the early stage of HIV infection, a significant decrease in CD4 cell counts during the first 36 months (-50 or more cells/mm(3)), and high frequencies of mutations during the first 36 months of antiretroviral regimen (>3 mutations) emerged as potential predictive factors of EoR associated with NRTI/PRI agents thereafter. Stable VL in the first 36 months correlated with lack of lability of resistance mutations thereafter.

  17. Refined structure of Escherichia coli heat-labile enterotoxin, a close relative of cholera toxin.

    PubMed

    Sixma, T K; Kalk, K H; van Zanten, B A; Dauter, Z; Kingma, J; Witholt, B; Hol, W G

    1993-04-05

    Heat-labile enterotoxin (LT) from Escherichia coli is a bacterial protein toxin with an AB5 multimer structure, in which the B pentamer has a membrane binding function and the A subunit is needed for enzymatic activity. The LT crystal structure has been solved using a combination of multiple isomorphous replacement, fivefold averaging and molecular dynamics refinement. Phase combination using all these sources of phase information was of crucial importance for the chain tracing. The structure has now been refined to 1.95 A resolution, resulting in a model containing 6035 protein atoms and 293 solvent molecules with a crystallographic R-factor of 18.2% and good stereochemistry. The B subunits are arranged as a highly stable pentamer with a donut shape. Each subunit takes part in approximately 30 inter-subunit hydrogen bonds and six salt bridges with its two neighbors, whilst burying a large surface area. The A subunit has higher temperature factors and less well-defined secondary structure than the B subunits. It interacts with the B pentamer mainly via the C-terminal A2 fragment, which runs through the highly charged central pore of the B subunits. The pore contains at least 66 water molecules, which fill the space left by the A2 fragment. A detailed analysis of the contacts between A and B subunits showed that most specific contacts occur at the entrance of the central pore of the B pentamer, while the contacts within the pore are mainly hydrophobic and water mediated, with the exception of two salt bridges. Only a few contacts exist between the A1 fragment and the B pentamer, showing that the A2 fragment functions as a "linker" of the A and B parts of the protein. Interacting with the A subunit by the B subunits does not cause large deviations from a common B subunit structure, and the 5-fold symmetry is well maintained. A potential NAD(+)-binding site is located in an elongated crevice at the interface of two small sheets in the A1 fragment. At the back of this

  18. Effects of alkali treatments on Ag nanowire transparent conductive films

    NASA Astrophysics Data System (ADS)

    Kim, Sunho; Kang, Jun-gu; Eom, Tae-yil; Moon, Bongjin; Lee, Hoo-Jeong

    2016-06-01

    In this study, we employ various alkali materials (alkali metals with different base strengths, and ammonia gas and solution) to improve the conductivity of silver nanowire (Ag NW)-networked films. The alkali treatment appears to remove the surface oxide and improve the conductivity. When applied with TiO2 nanoparticles, the treatment appears more effective as the alkalis gather around wire junctions and help them weld to each other via heat emitted from the reduction reaction. The ammonia solution treatment is found to be quick and aggressive, damaging the wires severely in the case of excessive treatment. On the other hand, the ammonia gas treatment seems much less aggressive and does not damage the wires even after a long exposure. The results of this study highlight the effectiveness of the alkali treatment in improving of the conductivity of Ag NW-networked transparent conductive films.

  19. Performance of Straight Steel Fibres Reinforced Alkali Activated Concrete

    NASA Astrophysics Data System (ADS)

    Faris, Meor Ahmad; Bakri Abdullah, Mohd Mustafa Al; Nizar Ismail, Khairul; Muniandy, Ratnasamy; Putra Jaya, Ramadhansyah

    2016-06-01

    This paper focus on the performance of alkali activated concrete produced by using fly ash activated by sodium silicate and sodium hydroxide solutions. These alkali activated concrete were reinforced with straight steel fibres with different weight percentage starting from 0 % up to 5 %. Chemical composition of raw material in the production alkali activated concrete which is fly ash was first identified by using X-ray fluorescence. Results reveal there have an effect of straight steel fibres inclusion to the alkali activated concrete. Highest compressive strength of alkali activated concrete which is 67.72 MPa was obtained when 3 % of straight fibres were added. As well as flexural strength, highest flexural strength which is 6.78 MPa was obtained at 3 % of straight steel fibres inclusions.

  20. Eating from the same plate? Revisiting the role of labile carbon inputs in the soil food web.

    PubMed

    de Vries, Franciska T; Caruso, Tancredi

    2016-11-01

    An increasing number of empirical studies are challenging the central fundamentals on which the classical soil food web model is built. This model assumes that bacteria consume labile substrates twice as fast as fungi, and that mycorrhizal fungi do not decompose organic matter. Here, we build on emerging evidence that points to significant consumption of labile C by fungi, and to the ability of ectomycorrhizal fungi to decompose organic matter, to show that labile C constitutes a major and presently underrated source of C for the soil food web. We use a simple model describing the dynamics of a recalcitrant and a labile C pool and their consumption by fungi and bacteria to show that fungal and bacterial populations can coexist in a stable state with large inputs into the labile C pool and a high fungal use of labile C. We propose a new conceptual model for the bottom trophic level of the soil food web, with organic C consisting of a continuous pool rather than two or three distinct pools, and saprotrophic fungi using substantial amounts of labile C. Incorporation of these concepts will increase our understanding of soil food web dynamics and functioning under changing conditions.

  1. Interaction between fine-scale landforms and vegetation patterns in alkali landscapes - case study based on remotely sensed data

    NASA Astrophysics Data System (ADS)

    Deák, Balázs; Valkó, Orsolya; Tóthmérész, Béla; Alexander, Cici; Mücke, Werner; Kania, Adam; Tamás, János; Heilmeier, Hermann

    2015-04-01

    Vertical position is an important driver of vegetation zonation at multiple scales, via determining abiotic environmental parameters like climate, soil properties and water balance. Despite small-scale elevation differences are proven to significantly influence soil salt content and water balance; relationships between elevation and vegetation types are rarely studied in inland alkali landscapes. Alkali landscapes of the Pannonian biogeographical region comprise the most connected salt-affected landscape in continental Europe which provides unique opportunities for studying elevation-vegetation relationships. For linking elevation data with vegetation patterns, remote sensing techniques offer a vital solution. Application of airborne laser scanning is a feasible tool for providing an elevation model of extent areas. Our goal was to test the correlation between fine-scale differences in vertical position and vegetation patterns in inland alkali landscapes by using field vegetation data and elevation data generated using airborne laser scanning. We studied whether the vertical position influences vegetation patterns at the level of main vegetation categories or even at the level of associations. Our study sites were situated in a lowland alkali landscape in Hortobágy National Park (East-Hungary). Associations of the study site can be grouped into four main vegetation categories: (i) loess grasslands, (ii) alkali steppes, (iii) open alkali swards and (iv) alkali meadows. Even though we detected a very limited range in the vertical position (121 cm) of the main vegetation categories; they were well separated along their vertical positions. The detected elevation gradient likely corresponds to environmental gradients (soil type, salt accumulation and water balance). At the level of association types, a more detailed elevation-based distinction was also possible in many cases. Based on the digital terrain model, we revealed a fine-scale vertical vegetation gradient. Our

  2. Alkali oxide-tantalum oxide and alkali oxide-niobium oxide ionic conductors

    NASA Technical Reports Server (NTRS)

    Roth, R. S.; Parker, H. S.; Brower, W. S.; Minor, D.

    1974-01-01

    A search was made for new cationic conducting phases in alkali-tantalate and niobate systems. The phase equilibrium diagrams were constructed for the six binary systems Nb2O5-LiNbO3, Nb2O5-NaNbO3, Nb2O5-KNbO3, Ta2O5-NaTaO3, Ta2O5-LiTaO3, and Ta2O5-KTaO3. Various other binary and ternary systems were also examined. Pellets of nineteen phases were evaluated (by the sponsoring agency) by dielectric loss measurements. Attempts were made to grow large crystals of eight different phases. The system Ta2O5-KTaO3 contains at least three phases which showed peaks in dielectric loss vs. temperature. All three contain structures related to the tungsten bronzes with alkali ions in non-stoichiometric crystallographic positions.

  3. Synergistic capture mechanisms for alkali and sulphur species from combustion. Quarterly report No. 11, March 1993--May 1993

    SciTech Connect

    Peterson, T.W.; Shadman, F.; Wendt, J.O.L.; Wu, Baochun

    1993-07-26

    Sulfur dioxide is one of the major pollutant from coal combustion application and gasification. The capture of sulfur from flue gas with lime has been investigated and proven to be effective. Previous work concluded that the overall conversion of lime is limited by the micro-structure of the particles and reaction temperature. Due to the larger specific volume of product of calcium sulfate than that of the raw sorbent of calcium carbonate, which may cause pore blockage at the pore mouth and increase the diffusion resistance of sulfur dioxide through the product layer, but this pore plugging will not apply to the particle less than 0.01 cm in diameter. The reaction temperature, which determined the chemical reaction kinetics, between 800{degrees}C to 850{degrees}C, is recommended to be the best chemical reaction temperature for sulfur removal by lime. The alkali vapor removal has been the subject of many studies due to the possible application of coal combustion and hot flue gas turbine combined cycle which requires alkali concentration in the flue gas phase of sub parts per billion (ppB) level. But this process will increase the coal utilization efficiency dramatically. Some clay materials such as kaolinite and alumina-silica mixture like bauxite are found to be a very good sorbent for the adsorption of alkali vapor. The main objective of this research is to develop sorbents with alumina-silica base for both as a carrier to calcium and sorbents to alkali. A number of sorbents, with bauxite based and calcium active sites, have been developed and tested in a series of experiments. The experimental results of adsorption of sulfur dioxide, alkali and combined adsorption of sulfur/alkali have been given in the previous report.

  4. Flocculated meltwater particles control Arctic land-sea fluxes of labile iron

    PubMed Central

    Markussen, Thor Nygaard; Elberling, Bo; Winter, Christian; Andersen, Thorbjørn Joest

    2016-01-01

    Glacial meltwater systems supply the Arctic coastal ocean with large volumes of sediment and potentially bioavailable forms of iron, nitrogen and carbon. The particulate fraction of this supply is significant but estuarine losses have been thought to limit the iron supply from land. Here, our results reveal how flocculation (particle aggregation) involving labile iron may increase horizontal transport rather than enhance deposition close to the source. This is shown by combining field observations in Disko Fjord, West Greenland, and laboratory experiments. Our data show how labile iron affects floc sizes, shapes and densities and consequently yields low settling velocities and extended sediment plumes. We highlight the importance of understanding the flocculation mechanisms when examining fluxes of meltwater transported iron in polar regions today and in the future, and we underline the influence of terrestrial hotspots on the nutrient and solute cycles in Arctic coastal waters. PMID:27050673

  5. Relationship between the lability of sediment-bound Cd and its bioaccumulation in edible oyster.

    PubMed

    Chakraborty, Parthasarathi; Ramteke, Darwin; Chakraborty, Sucharita; Chennuri, Kartheek; Bardhan, Pratirupa

    2015-11-15

    A linkage between Cd speciation in sediments and its bioaccumulation in edible oyster (Crassostrea sp.) from a tropical estuarine system was established. Bioaccumulation of Cd in edible oyster increased with the increasing lability and dissociation rate constants of Cd-sediment complexes in the bottom sediments. Total Cd concentration in sediment was not a good indicator of Cd-bioavailability. Increasing trace metal competition in sediments increased lability and bioavailability of Cd in the tropical estuarine sediment. Low thermodynamic stability and high bioavailability of Cd in the estuarine sediment were responsible for high bioaccumulation of Cd in edible oysters (3.2-12.2mgkg(-1)) even though the total concentration of Cd in the bottom sediment was low (0.17-0.49mgkg(-1)).

  6. Flocculated meltwater particles control Arctic land-sea fluxes of labile iron

    NASA Astrophysics Data System (ADS)

    Markussen, Thor Nygaard; Elberling, Bo; Winter, Christian; Andersen, Thorbjørn Joest

    2016-04-01

    Glacial meltwater systems supply the Arctic coastal ocean with large volumes of sediment and potentially bioavailable forms of iron, nitrogen and carbon. The particulate fraction of this supply is significant but estuarine losses have been thought to limit the iron supply from land. Here, our results reveal how flocculation (particle aggregation) involving labile iron may increase horizontal transport rather than enhance deposition close to the source. This is shown by combining field observations in Disko Fjord, West Greenland, and laboratory experiments. Our data show how labile iron affects floc sizes, shapes and densities and consequently yields low settling velocities and extended sediment plumes. We highlight the importance of understanding the flocculation mechanisms when examining fluxes of meltwater transported iron in polar regions today and in the future, and we underline the influence of terrestrial hotspots on the nutrient and solute cycles in Arctic coastal waters.

  7. [Pathogen inactivation in labile blood products: transfusion safety and economic impact].

    PubMed

    Cazenave, Jean-Pierre

    2006-01-01

    The safety of labile blood products (red blood cell concentrates, platelet concentrates and plasma) is currently ensured by medical and biological donor selection measures. Nonetheless, in addition to the residual risk of bacterial injection of platelet concentrates and parasitic infection of red cell concentrates, there is the emerging danger associated with new viruses. Pathogen inactivation based on chemical or photochemical genomic modifications is a broad-spectrum approach. These techniques are already used to inactivate plasma, and are being developed or application to platelet and erythrocyte concentrates. Universal inactivation of all labile blood products should be possible in a few years' time, but clinical and hemovigilance studies must first show that the biological properties and therapeutic efficacy of these products are not markedly affected, and that the methods used do not lead to long-term toxicity.

  8. Flocculated meltwater particles control Arctic land-sea fluxes of labile iron.

    PubMed

    Markussen, Thor Nygaard; Elberling, Bo; Winter, Christian; Andersen, Thorbjørn Joest

    2016-04-06

    Glacial meltwater systems supply the Arctic coastal ocean with large volumes of sediment and potentially bioavailable forms of iron, nitrogen and carbon. The particulate fraction of this supply is significant but estuarine losses have been thought to limit the iron supply from land. Here, our results reveal how flocculation (particle aggregation) involving labile iron may increase horizontal transport rather than enhance deposition close to the source. This is shown by combining field observations in Disko Fjord, West Greenland, and laboratory experiments. Our data show how labile iron affects floc sizes, shapes and densities and consequently yields low settling velocities and extended sediment plumes. We highlight the importance of understanding the flocculation mechanisms when examining fluxes of meltwater transported iron in polar regions today and in the future, and we underline the influence of terrestrial hotspots on the nutrient and solute cycles in Arctic coastal waters.

  9. Effect of combined ultrasonic and alkali pretreatment on enzymatic preparation of angiotensin converting enzyme (ACE) inhibitory peptides from native collagenous materials.

    PubMed

    Zhang, Yuhao; Ma, Liang; Cai, Luyun; Liu, Yi; Li, Jianrong

    2017-05-01

    The combined effect of ultrasonic and alkali pretreatment for the hydrolysis of native collagenous materials and release of ACE inhibitory peptides was investigated. The ultrasonic and alkali pretreatment of pig skin could accelerate the release of the ACE inhibitory peptides from the triple helix of collagen in early stages of hydrolysis. Furthermore, the pretreatment could also accelerate collapse of the triple helix and release more ACE inhibitory peptides during hydrolysis than collagen samples left untreated. Compared to untreated and alkali pretreated samples, the ultrasonic and alkali pretreatment could decrease the thermostability of pig skin significantly (P<0.05) because the ultrasonic and alkali pretreatment could weaken hydrogen bonds and break parts of covalent bonds in collagen, leading to damage of the triple helical structure in collagen. Therefore, the ultrasonic and alkali pretreatment could damage the triple helical structure of collagen in native collagenous materials and expose more inner sites for subsequent hydrolysis, and it could be a potential way to prepare ACE inhibitory peptides effectively from collagen-rich raw material.

  10. Heat pipes containing alkali metal working fluid

    NASA Technical Reports Server (NTRS)

    Morris, J. F. (Inventor)

    1981-01-01

    A technique for improving high temperature evaporation-condensation heat-transfer devices which have important and unique advantage in terrestrial and space energy processing is described. The device is in the form of a heat pipe comprising a sealed container or envelope which contains a capillary wick. The temperature of one end of the heat pipe is raised by the input of heat from an external heat source which is extremely hot and corrosive. A working fluid of a corrosive alkali metal, such as lithium, sodium, or potassium transfers this heat to a heat receiver remote from the heat source. The container and wick are fabricated from a superalloy containing a small percentage of a corrosion inhibiting or gettering element. Lanthanum, scandium, yttrium, thorium, and hafnium are utilized as the alloying metal.

  11. Volcanic Origin of Alkali Halides on Io

    NASA Technical Reports Server (NTRS)

    Schaefer, L.; Fegley, B., Jr.

    2003-01-01

    The recent observation of NaCl (gas) on Io confirms our earlier prediction that NaCl is produced volcanically. Here we extend our calculations by modeling thermochemical equilibrium of O, S, Li, Na, K, Rb, Cs, F, Cl, Br, and I as a function of temperature and pressure in a Pele-like volcanic gas with O/S/Na/Cl/K = 1.518/1/0.05/0.04/0.005 and CI chondritic ratios of the other (as yet unobserved) alkalis and halogens. For reference, the nominal temperature and pressure for Pele is 1760 plus or minus 210 K and 0.01 bars based on Galileo data and modeling.

  12. Ionic alkali halide XUV laser feasibility study

    SciTech Connect

    Yang, T.T.; Gylys, V.T.; Bower, R.D.; Harris, D.G.; Blauer, J.A.; Turner, C.E.; Hindy, R.N.

    1989-11-10

    The objective of this work is to assess the feasibility of a select set of ionic alkali halide XUV laser concepts by obtaining the relevant kinetic and spectroscopic parameters required for a proof-of-principle and conceptual design. The proposed lasers operate in the 80--200 nm spectral region and do not require input from outside radiation sources for their operation. Frequency up-conversion and frequency mixing techniques and therefore not considered in the work to be described. An experimental and theoretical study of a new type of laser operating in the extreme ultraviolet wavelength region has been conducted. The lasing species are singly ionized alkali halide molecules such as Rb{sup 2+}F{sub {minus}}, Rb{sup 2+}Br{sup {minus}} and Cs{sup 2+}F{sup {minus}}. These species are similar in electronic structure to the rare gas halide excimers, such as XeF and Krf, except that the ionic molecules emit at wavelengths of 80--200 nm, much shorter than the conventional rare-gas halide excimer laser. The radiative lifetime of these molecules are typically near 1 ns, which is about an order of magnitude shorter than that for rare-gas halide systems. The values of the cross section for stimulated emission are on the order of 1 {times} 10{sup {minus}16}cm{sup 2}. Because of the fundamental similarity to existing UV lasers, these systems show promise as a high power, efficient XUV lasers. 55 refs., 50 figs., 5 tabs.

  13. Mayolenes: labile defensive lipids from the glandular hairs of a caterpillar (Pieris rapae).

    PubMed

    Smedley, Scott R; Schroeder, Frank C; Weibel, Douglas B; Meinwald, Jerrold; Lafleur, Katie A; Renwick, J Alan; Rutowski, Ronald; Eisner, Thomas

    2002-05-14

    Larvae of the European cabbage butterfly, Pieris rapae (Pieridae), are beset with glandular hairs, bearing droplets of a clear oily secretion at their tip. The fluid consists primarily of a series of chemically labile, unsaturated lipids, the mayolenes, which are derived from 11-hydroxylinolenic acid. In bioassays with the ant Crematogaster lineolata, the secretion was shown to be potently deterrent, indicating that the fluid plays a defensive role in nature.

  14. Labile iron potentiates ascorbate-dependent reduction and mobilization of ferritin iron.

    PubMed

    Badu-Boateng, Charles; Pardalaki, Sofia; Wolf, Claude; Lajnef, Sonia; Peyrot, Fabienne; Naftalin, Richard J

    2017-03-21

    Ascorbate mobilizes iron from equine spleen ferritin by two separate processes. Ascorbate alone mobilizes ferritin iron with an apparent Km (ascorbate) ≈1.5mM. Labile iron >2μM, complexed with citrate (10mM), synergises ascorbate-dependent iron mobilization by decreasing the apparent Km (ascorbate) to ≈270μM and raising maximal mobilization rate by ≈5-fold. Catalase reduces the apparent Km(ascorbate) for both ascorbate and ascorbate+iron dependent mobilization by ≈80%. Iron mobilization by ascorbate alone has a higher activation energy (Ea=45.0±5.5kJ/mole) than when mediated by ascorbate with labile iron (10μM) (Ea=13.7±2.2kJ/mole); also mobilization by iron-ascorbate has a three-fold higher pH sensitivity (pH range 6.0-8.0) than with ascorbate alone. Hydrogen peroxide inhibits ascorbate's iron mobilizing action. EPR and autochemiluminescence studies show that ascorbate and labile iron within ferritin enhances radical formation, whereas ascorbate alone produces negligible radicals. These findings suggest that iron catalysed single electron transfer reactions from ascorbate, involving ascorbate or superoxide and possibly ferroxidase tyrosine radicals, accelerate iron mobilization from the ferroxidase centre more than EPR silent, bi-dentate two-electron transfers. These differing modes of electron transference from ascorbate mirror the known mono and bidentate oxidation reactions of dioxygen and hydrogen peroxide with di-ferrous iron at the ferroxidase centre. This study implies that labile iron, at physiological pH, complexed with citrate, synergises iron mobilization from ferritin by ascorbate (50-4000μM). This autocatalytic process can exacerbate oxidative stress in ferritin-containing inflamed tissue.

  15. Immunological Interrelationships of Coliform Heat-Labile and Heat-Stable Enterotoxins

    DTIC Science & Technology

    1981-09-01

    FA, Engert RF: Immunological interrelationships between cholera toxin and the heat -labile and hoat-stable enterotoxins of coliform bacteria . Infec...When Date Enterd) -3- SUMMARY These investigations (a) established the fact that species of coliform bacteria other than ETEC strains of E. coZi...elaborate enterotoxins which alter gastrointestinal physiology, and (b) showed that immunization with either E. coli (ETEC) LT or ST toxin arouses an

  16. Immunologic Interrelationships of Coliform Heat-Labile and Heat-Stable Enterotoxins

    DTIC Science & Technology

    1980-01-15

    immunization program to prevent diarrheal disease due to Intestinal contamination by enterotoxigenic straing of coliform bacteria . We have found that...pnotobiotic rats are challenged by intestinal contamination with strains of E. coli which produce the heat-labile toxin , FOB W 13 -niouos wI, soov esis...extended protection against challenge with either this toxin or viable strains of LT-producing E. coZi. Current investigations are addressed at

  17. Labile and stabilised fractions of soil organic carbon in some intensively cultivated alluvial soils.

    PubMed

    Verma, B C; Datta, S P; Rattan, R K; Singh, A K

    2013-11-01

    The present investigation was undertaken in view of the limited information on the relative proportion of labile and stabilized fractions of soil organic carbon (SOC) in intensively cultivated lands, particularly under tropics. The specific objectives were i) to study the comparative recovery of SOC by different methods of labile carbon estimation under intensively cultivated lands and ii) to evaluate the impact of agricultural practices on carbon management index. For this purpose, in all, 105 surface soil samples were collected from intensively cultivated tube well and sewage irrigated agricultural lands. These samples were analysed for total as well as labile pools of SOC. Results indicated that Walkley and Black, KMnO4-oxidizable and microbial biomass carbon constituted the total SOC to the extent of 10.2 to 47.4, 1.66 to 23.2 and 0.30 to 5.49%, respectively with the corresponding mean values of 26.2, 9.16 and 2.15%. Lability of SOC was considerably higher in sewage irrigated soils than tube well irrigated soils under intensive cropping. Under soybean-wheat, the higher values of carbon management index (CMI) (279 and 286) were associated with the treatments where entire amount of nitrogen was supplied through FYM. Similar results were obtained under rice-wheat, whereas in case of maize-wheat the highest value of CMI was recorded under treatment receiving NPK through chemical fertilizer along with green manure. There was also a significant improvement in CMI under integrated (chemical fertilizer + organics) and chemical fertilizer-treated plots. The values of CMI ranged from 220 to 272 under cultivated lands receiving irrigation through sewage and industrial effluents.

  18. Protein degradation by ubiquitin–proteasome system in formation and labilization of contextual conditioning memory

    PubMed Central

    Sol Fustiñana, María; de la Fuente, Verónica; Federman, Noel; Freudenthal, Ramiro

    2014-01-01

    The ubiquitin–proteasome system (UPS) of protein degradation has been evaluated in different forms of neural plasticity and memory. The role of UPS in such processes is controversial. Several results support the idea that the activation of this system in memory consolidation is necessary to overcome negative constrains for plasticity. In this case, the inhibition of the UPS during consolidation impairs memory. Similar results were reported for memory reconsolidation. However, in other cases, the inhibition of UPS had no effect on memory consolidation and reconsolidation but impedes the amnesic action of protein synthesis inhibition after retrieval. The last finding suggests a specific action of the UPS inhibitor on memory labilization. However, another interpretation is possible in terms of the synthesis/degradation balance of positive and negative elements in neural plasticity, as was found in the case of long-term potentiation. To evaluate these alternative interpretations, other reconsolidation-interfering drugs than translation inhibitors should be tested. Here we analyzed initially the UPS inhibitor effect in contextual conditioning in crabs. We found that UPS inhibition during consolidation impaired long-term memory. In contrast, UPS inhibition did not affect memory reconsolidation after contextual retrieval but, in fact, impeded memory labilization, blocking the action of drugs that does not affect directly the protein synthesis. To extend these finding to vertebrates, we performed similar experiments in contextual fear memory in mice. We found that the UPS inhibitor in hippocampus affected memory consolidation and blocked memory labilization after retrieval. These findings exclude alternative interpretations to the requirement of UPS in memory labilization and give evidence of this mechanism in both vertebrates and invertebrates. PMID:25135196

  19. Protein degradation by ubiquitin-proteasome system in formation and labilization of contextual conditioning memory.

    PubMed

    Sol Fustiñana, María; de la Fuente, Verónica; Federman, Noel; Freudenthal, Ramiro; Romano, Arturo

    2014-09-01

    The ubiquitin-proteasome system (UPS) of protein degradation has been evaluated in different forms of neural plasticity and memory. The role of UPS in such processes is controversial. Several results support the idea that the activation of this system in memory consolidation is necessary to overcome negative constrains for plasticity. In this case, the inhibition of the UPS during consolidation impairs memory. Similar results were reported for memory reconsolidation. However, in other cases, the inhibition of UPS had no effect on memory consolidation and reconsolidation but impedes the amnesic action of protein synthesis inhibition after retrieval. The last finding suggests a specific action of the UPS inhibitor on memory labilization. However, another interpretation is possible in terms of the synthesis/degradation balance of positive and negative elements in neural plasticity, as was found in the case of long-term potentiation. To evaluate these alternative interpretations, other reconsolidation-interfering drugs than translation inhibitors should be tested. Here we analyzed initially the UPS inhibitor effect in contextual conditioning in crabs. We found that UPS inhibition during consolidation impaired long-term memory. In contrast, UPS inhibition did not affect memory reconsolidation after contextual retrieval but, in fact, impeded memory labilization, blocking the action of drugs that does not affect directly the protein synthesis. To extend these finding to vertebrates, we performed similar experiments in contextual fear memory in mice. We found that the UPS inhibitor in hippocampus affected memory consolidation and blocked memory labilization after retrieval. These findings exclude alternative interpretations to the requirement of UPS in memory labilization and give evidence of this mechanism in both vertebrates and invertebrates.

  20. Mechanism-based design of labile precursors for chromium(I) chemistry

    DOE PAGES

    Akturk, Eser S.; Yap, Glenn P. A.; Theopold, Klaus H.

    2015-08-27

    Here, we report that dinitrogen complexes of the type TpR,RCr–N2–CrTpR,R are not the most labile precursors for Cr(I) chemistry, as they are sterically protected from obligatory associative ligand substitution. A mononuclear alkyne complex – TptBu,MeCr(η2-C2(SiMe3)2) – proved to be much more reactive.

  1. A Solvent-Free Thermosponge Nanoparticle Platform for Efficient Delivery of Labile Proteins

    PubMed Central

    2015-01-01

    Protein therapeutics have gained attention recently for treatment of a myriad of human diseases due to their high potency and unique mechanisms of action. We present the development of a novel polymeric thermosponge nanoparticle for efficient delivery of labile proteins using a solvent-free polymer thermo-expansion mechanism with clinical potential, capable of effectively delivering a range of therapeutic proteins in a sustained manner with no loss of bioactivity, with improved biological half-lives and efficacy in vivo. PMID:25333768

  2. Ultrasonic coal washing to leach alkali elements from coals.

    PubMed

    Balakrishnan, S; Reddy, V Midhun; Nagarajan, R

    2015-11-01

    Deposition of fly ash particles onto heat-transfer surfaces is often one of the reasons for unscheduled shut-downs of coal-fired boilers. Fouling deposits encountered in convective sections of a boiler are characterized by arrival of ash particles in solidified (solid) state. Fouling is most frequently caused by condensation and chemical reaction of alkali vapors with the deposited ash particles creating a wet surface conducive to collect impacting ash particles. Hence, the amount of alkali elements present in coals, which, in turn, is available in the flue gas as condensable vapors, determines the formation and growth of fouling deposits. In this context, removal of alkali elements becomes vital when inferior coals having high-ash content are utilized for power generation. With the concept of reducing alkali elements present in a coal entering the combustor, whereby the fouling deposits can either be minimized or be weakened due to absence of alkali gluing effect, the ultrasonic leaching of alkali elements from coals is investigated in this study. Ultrasonic water-washing and chemical-washing, in comparison with agitation, are studied in order to estimate the intensification of the alkali removal process by sonication.

  3. Alkali elemental and potassium isotopic compositions of Semarkona chondrules

    USGS Publications Warehouse

    Alexander, C.M. O'D.; Grossman, J.N.

    2005-01-01

    We report measurements of K isotope ratios in 28 Semarkona chondrules with a wide range of petrologic types and bulk compositions as well as the compositions of CPX-mesostasis pairs in 17 type I Semarkona chondrules, including two chondrules with radial alkali zonation and 19 type II chondrules. Despite the wide range in K/Al ratios, no systematic variations in K isotopic compositions were found. Semarkona chondrules do not record a simple history of Rayleigh-type loss of K. Experimentally determined evaporation rates suggest that considerable alkali evaporation would have occurred during chondrule formation. Nevertheless, based on Na CPX-mesostasis distribution coefficients, the alkali contents of the cores of most chondrules in Semarkona were probably established at the time of final crystallization. However, Na CPX-mesostasis distribution coefficients also show that alkali zonation in type I Semarkona chondrules was produced by entry of alkalis after solidification, probably during parent body alteration. This alkali metasomatism may have gone to completion in some chondrules. Our preferred explanation for the lack of systematic isotopic enrichments, even in alkali depleted type I chondrule cores, is that they exchanged with the ambient gas as they cooled. ?? The Meteoritical Society, 2005.

  4. Controlled in-situ dissolution of an alkali metal

    DOEpatents

    Jones, Jeffrey Donald; Dooley, Kirk John; Tolman, David Donald

    2012-09-11

    A method for the controllable dissolution of one or more alkali metals from a vessel containing a one or more alkali metals and/or one or more partially passivated alkali metals. The vessel preferably comprising a sodium, NaK or other alkali metal-cooled nuclear reactor that has been used. The alkali metal, preferably sodium, potassium or a combination thereof, in the vessel is exposed to a treatment liquid, preferably an acidic liquid, more preferably citric acid. Preferably, the treatment liquid is maintained in continuous motion relative to any surface of unreacted alkali metal with which the treatment liquid is in contact. The treatment liquid is preferably pumped into the vessel containing the one or more alkali metals and the resulting fluid is extracted and optionally further processed. Preferably, the resulting off-gases are processed by an off-gas treatment system and the resulting liquids are processed by a liquid disposal system. In one preferred embodiment, an inert gas is pumped into the vessel along with the treatment liquid.

  5. Evolution of carbonated melt to alkali basalt in the South China Sea

    NASA Astrophysics Data System (ADS)

    Zhang, Guo-Liang; Chen, Li-Hui; Jackson, Matthew G.; Hofmann, Albrecht W.

    2017-01-01

    CO2 is considered to play a key role in the melting of the deep upper mantle, and carbonated silicate melts have been widely predicted by partial melting experiments to exist at mantle depths of greater than 80 km. However, such melts have not been shown to exist in nature. Thus, the relationship between CO2 and the origin of silicate melts is highly speculative. Here we present geochemical analyses of rocks sampled from the South China Sea, at the Integrated Ocean Discovery Program Site U1431. We identify natural carbonated silicate melts, which are enriched in light rare earth elements and depleted in Nb and Ta, and show that they were continuously transformed to alkali basalts that are less enriched in light rare earth elements and enriched in Nb and Ta. This shows that carbonated silicate melts can survive in the shallow mantle and penetrate through the hot asthenosphere. Carbonated silicate melts were converted to alkali basaltic melts through reactions with the lithospheric mantle, during which precipitation of apatite accounts for reduction of light rare earth elements and genesis of positive Nb-Ta anomalies. We propose that an extremely thin lithosphere (less than 20 km in the South China Sea) facilitates extrusion of the carbonated silicate melts, whereas a thickened lithosphere tends to modify carbonated silicate melt to alkali basalt.

  6. Narrowband Angular Reflectance Properties of the Alkali Flats at White Sands, New Mexico

    NASA Technical Reports Server (NTRS)

    Whitlock, Charles H.; LeCroy, Stuart R.; Wheeler, Robert J.

    1994-01-01

    Results from helicopter measurements of the angular properties of surface reflectance for the alkali flats regions of the White Sands Missile Range are presented for the wavelength interval of 0.4 to 0.85 microns. This work was performed to allow accurate radiative transfer calculations over the region. Detailed tables and interpolation equations are given that permit other investigators to perform satellite calibrations over the alkali flats site. The effects of wavelength and soil moisture on narrowband angular reflectance are also investigated. Although there is a spectral variation in surface albedo, there is little spectral effect in Anisotropic Factor except in the forward scattering peak at solar zenith angles greater than 60 deg. The magnitude of the forward-scattering peak is also sensitive to soil moisture, with wet conditions causing a larger peak. The significance of this result is that angular reflectance properties at the center of the alkali flats usually will be different than those at the flats edge because moisture differences typically exist.

  7. Labile soil carbon inputs mediate the soil microbial community composition and plant residue decomposition rates

    SciTech Connect

    De Graaff, Marie-Anne; Classen, Aimee T; Castro Gonzalez, Hector F; Schadt, Christopher Warren

    2010-01-01

    Root carbon (C) inputs may regulate decomposition rates in soil, and in this study we ask: how do labile C inputs regulate decomposition of plant residues, and soil microbial communities? In a 14 d laboratory incubation, we added C compounds often found in root exudates in seven different concentrations (0, 0.7, 1.4, 3.6, 7.2, 14.4 and 21.7 mg C g{sup -1} soil) to soils amended with and without {sup 13}C-labeled plant residue. We measured CO{sub 2} respiration and shifts in relative fungal and bacterial rRNA gene copy numbers using quantitative polymerase chain reaction (qPCR). Increased labile C input enhanced total C respiration, but only addition of C at low concentrations (0.7 mg C g{sup -1}) stimulated plant residue decomposition (+2%). Intermediate concentrations (1.4, 3.6 mg C g{sup -1}) had no impact on plant residue decomposition, while greater concentrations of C (> 7.2 mg C g{sup -1}) reduced decomposition (-50%). Concurrently, high exudate concentrations (> 3.6 mg C g{sup -1}) increased fungal and bacterial gene copy numbers, whereas low exudate concentrations (< 3.6 mg C g{sup -1}) increased metabolic activity rather than gene copy numbers. These results underscore that labile soil C inputs can regulate decomposition of more recalcitrant soil C by controlling the activity and relative abundance of fungi and bacteria.

  8. The effect of acidification on the bioavailability and electrochemical lability of zinc in seawater

    NASA Astrophysics Data System (ADS)

    Kim, Ja-Myung; Baars, Oliver; Morel, François M. M.

    2016-11-01

    A poorly studied but potentially important consequence of the CO2-induced acidification of the surface ocean is a possible change in the bioavailability of trace metals, which play a critical role in the productivity and population dynamics of marine ecosystems. We report laboratory and field experiments designed to compare quantitatively the effects of acidification on the bioavailability of Zn, a metal essential to the growth of phytoplankton and on the extent of its complexation by model and natural ligands. We observed a good correspondence between the effects of pH on the rate of Zn uptake by a model diatom and the chemical lability of Zn measured by anodic stripping voltammetry (ASV). In model laboratory systems, the chemical lability and the bioavailability of Zn could either increase or decrease at low pH depending on the mix of complexing ligands. In a sample of coastal surface water, we observed similar increases in the ASV-labile and bioavailable Zn concentrations upon acidification, a result contrary to previous observations. These results, which can likely be generalized to other bioactive trace metals, mutatis mutandis, demonstrate the intricacy of the effects of ocean acidification on the chemistry and the ecology of surface seawater. This article is part of the themed issue 'Biological and climatic impacts of ocean trace element chemistry'.

  9. Evolution of phenotypic plasticity and environmental tolerance of a labile quantitative character in a fluctuating environment.

    PubMed

    Lande, R

    2014-05-01

    Quantitative genetic models of evolution of phenotypic plasticity are used to derive environmental tolerance curves for a population in a changing environment, providing a theoretical foundation for integrating physiological and community ecology with evolutionary genetics of plasticity and norms of reaction. Plasticity is modelled for a labile quantitative character undergoing continuous reversible development and selection in a fluctuating environment. If there is no cost of plasticity, a labile character evolves expected plasticity equalling the slope of the optimal phenotype as a function of the environment. This contrasts with previous theory for plasticity influenced by the environment at a critical stage of early development determining a constant adult phenotype on which selection acts, for which the expected plasticity is reduced by the environmental predictability over the discrete time lag between development and selection. With a cost of plasticity in a labile character, the expected plasticity depends on the cost and on the environmental variance and predictability averaged over the continuous developmental time lag. Environmental tolerance curves derived from this model confirm traditional assumptions in physiological ecology and provide new insights. Tolerance curve width increases with larger environmental variance, but can only evolve within a limited range. The strength of the trade-off between tolerance curve height and width depends on the cost of plasticity. Asymmetric tolerance curves caused by male sterility at high temperature are illustrated. A simple condition is given for a large transient increase in plasticity and tolerance curve width following a sudden change in average environment.

  10. Memory labilization in reconsolidation and extinction--evidence for a common plasticity system?

    PubMed

    Almeida-Corrêa, Suellen; Amaral, Olavo B

    2014-01-01

    Reconsolidation and extinction are two processes occurring upon memory retrieval that have received great attention in memory research over the last decade, partly due to their purported potential in the treatment of anxiety disorders. Due to their opposite behavioral effects, the two phenomena have usually been considered as separate entities, with few attempts to build a unified view of how both could be produced by similar mechanisms. Based on computational modeling, we have previously proposed that reconsolidation and extinction are behavioral outcomes of the same set of plasticity systems, albeit working at different synapses. One of these systems seems to be pharmacologically similar to the one involved in initial memory consolidation, and likely involves traditional Hebbian plasticity, while the second seems to be more involved with the labilization of existing memories and/or synaptic changes. In this article, we review the evidence for the existence of a plasticity system specifically involved in memory labilization, as well as its possible molecular requirements, anatomical substrates, synaptic mechanisms and physiological roles. Based on these data, we propose that the field of memory updating might ultimately benefit from a paradigm shift in which reconsolidation and extinction are viewed not as separate processes but as different instantiations of plasticity systems responsible for reinforcement and labilization of synaptic changes.

  11. Substrate lability and plant activity controls greenhouse gas release from Neotropical peatland

    NASA Astrophysics Data System (ADS)

    Sjogersten, Sofie; Hoyos, Jorge; Lomax, Barry; Turner, Ben; Wright, Emma

    2014-05-01

    Almost one third of global CO2 emissions resulting from land use change and substantial CH4 emissions originate from tropical peatlands. However, our understanding of the controls of CO2 and CH4 release from tropical peatlands are limited. The aim of this study was to investigate the role of peat lability and the activity of the vegetation on gas release using a combination of field and laboratory experiments. We demonstrated that peat lability constrained CH4 production to the surface peat under anaerobic conditions. The presence of plants shifted the C balance from a C source to a C sink with respect to CO2 while the activity of the root system strongly influenced CH4 emissions through its impact on soil O2 inputs. Both field and laboratory data suggest a coupling between the photosynthetic activity of the vegetation and the release of both CO2 and CH4 following the circadian rhythm of the dominant plant functional types. Forest clearance for agriculture resulted in elevated CH4 release, which we attribute in part to the cessation of root O2 inputs to the peat. We conclude that high emissions of CO2 and CH4 from forested tropical peatlands are likely driven by labile C inputs from the vegetation but that root O2 release may limit CH4 emissions.

  12. Lability of heavy metal species in aquatic humic substances characterized by ion exchange with cellulose phosphate.

    PubMed

    Rocha, J C; Toscano, I A; Burba, P

    1997-01-01

    Labile metal species in aquatic humic substances (HSs) were characterized by ion exchange on cellulose phosphate (CellPhos) by applying an optimized batch procedure. The HSs investigated were pre-extracted from humic-rich waters by ultrafiltration and a resin XAD 8 procedure. The HS-metal species studied were formed by complexation with Cd(II), Ni(II), Cu(II), Mn(II) and Pb(II) as a function of time and the ratio ions to HSs. The kinetics and reaction order of this exchange process were studied. At the beginning (<3 min), the labile metal fractions are separated relatively quickly. After 3 min, the separation of the metal ions proceeds with uniform half-lives of about 12-14 min, revealing rather slow first-order kinetics. The metal exchange between HSs and CellPhos exhibited the following order of metal lability with the studied HSs: Cu > Pb > Mn > Ni > Cd. The required metal determinations were carried out by atomic absorption spectrometry.

  13. Treatment of PCR products with exonuclease I and heat-labile alkaline phosphatase improves the visibility of combined bisulfite restriction analysis

    SciTech Connect

    Watanabe, Kousuke; Emoto, Noriko; Sunohara, Mitsuhiro; Kawakami, Masanori; Kage, Hidenori; Nagase, Takahide; Ohishi, Nobuya; Takai, Daiya

    2010-08-27

    Research highlights: {yields} Incubating PCR products at a high temperature causes smears in gel electrophoresis. {yields} Smears interfere with the interpretation of methylation analysis using COBRA. {yields} Treatment with exonuclease I and heat-labile alkaline phosphatase eliminates smears. {yields} The elimination of smears improves the visibility of COBRA. -- Abstract: DNA methylation plays a vital role in the regulation of gene expression. Abnormal promoter hypermethylation is an important mechanism of inactivating tumor suppressor genes in human cancers. Combined bisulfite restriction analysis (COBRA) is a widely used method for identifying the DNA methylation of specific CpG sites. Here, we report that exonuclease I and heat-labile alkaline phosphatase can be used for PCR purification for COBRA, improving the visibility of gel electrophoresis after restriction digestion. This improvement is observed when restriction digestion is performed at a high temperature, such as 60 {sup o}C or 65 {sup o}C, with BstUI and TaqI, respectively. This simple method can be applied instead of DNA purification using spin columns or phenol/chloroform extraction. It can also be applied to other situations when PCR products are digested by thermophile-derived restriction enzymes, such as PCR restriction fragment length polymorphism (RFLP) analysis.

  14. Near atomically smooth alkali antimonide photocathode thin films

    NASA Astrophysics Data System (ADS)

    Feng, Jun; Karkare, Siddharth; Nasiatka, James; Schubert, Susanne; Smedley, John; Padmore, Howard

    2017-01-01

    Nano-roughness is one of the major factors degrading the emittance of electron beams that can be generated by high efficiency photocathodes, such as the thermally reacted alkali antimonide thin films. In this paper, we demonstrate a co-deposition based method for producing alkali antimonide cathodes that produce near atomic smoothness with high reproducibility. We calculate the effect of the surface roughness on the emittance and show that such smooth cathode surfaces are essential for operation of alkali antimonide cathodes in high field, low emittance radio frequency electron guns and to obtain ultracold electrons for ultrafast electron diffraction applications.

  15. Increasing Class C fly ash reduces alkali silica reactivity

    SciTech Connect

    Hicks, J.K.

    2007-07-01

    Contrary to earlier studies, it has been found that incremental additions of Class C fly ash do reduce alkali silica reactivity (ASR), in highly reactive, high alkali concrete mixes. AST can be further reduced by substituting 5% metakaolin or silica fume for the aggregate in concrete mixes with high (more than 30%) Class C fly ash substitution. The paper reports results of studies using Class C fly ash from the Labadie Station plant in Missouri which typically has between 1.3 and 1.45% available alkalis by ASTM C311. 7 figs.

  16. Control of alkali species in gasification systems: Final report

    SciTech Connect

    Turn, S.; Kinoshita, C.; Ishimura, D. Zhou, J.; Hiraki, T.; Masutani, S.

    2000-07-13

    Gas-phase alkali metal compounds contribute to fouling, slagging, corrosion, and agglomeration problems in energy conversion facilities. One mitigation strategy applicable at high temperature is to pass the gas stream through a fixed bed sorbent or getter material, which preferentially absorbs alkali via physical adsorption or chemisorption. This report presents results of an experimental investigation of high-temperature alkali removal from a hot filtered gasifier product gas stream using a packed bed of sorbent material. Two getter materials, activated bauxite and emathlite, were tested at two levels of space time by using two interchangeable reactors of different internal diameters. The effect of getter particle size was also investigated.

  17. Electrochemical cell utilizing molten alkali metal electrode-reactant

    DOEpatents

    Virkar, Anil V.; Miller, Gerald R.

    1983-11-04

    An improved electrochemical cell comprising an additive-modified molten alkali metal electrode-reactant and/or electrolyte is disclosed. Various electrochemical cells employing a molten alkali metal, e.g., sodium, electrode in contact with a cationically conductive ceramic membrane experience a lower resistance and a lower temperature coefficient of resistance whenever small amounts of selenium are present at the interface of the electrolyte and the molten alkali metal. Further, cells having small amounts of selenium present at the electrolyte-molten metal interface exhibit less degradation of the electrolyte under long term cycling conditions.

  18. Hydride encapsulation by molecular alkali-metal clusters.

    PubMed

    Haywood, Joanna; Wheatley, Andrew E H

    2008-07-14

    The sequential treatment of group 12 and 13 Lewis acids with alkali-metal organometallics is well established to yield so-called ''ate' complexes, whereby the Lewis-acid metal undergoes nucleophilic attack to give an anion, at least one group 1 metal acting to counter this charge. However, an alternative, less well recognised, reaction pathway involves the Lewis acid abstracting hydride from the organolithium reagent via a beta-elimination mechanism. It has recently been shown that in the presence of N,N'-bidentate ligands this chemistry can be harnessed to yield a new type of molecular main-group metal cluster in which the abstracted LiH is effectively trapped, with the hydride ion occupying an interstitial site in the cluster core. Discussion focuses on the development of this field, detailing advances in our understanding of the roles of Lewis acid, organolithium, and amine substrates in the syntheses of these compounds. Structure-types are discussed, as are efforts to manipulate cluster geometry and composition as well as hydride-coordination. Embryonic mechanistic studies are reported, as well as attempts to generate hydride-encapsulation clusters under catalytic control.

  19. Synthesis and self-assembly of spin-labile and redox-active manganese(III) complexes.

    PubMed

    Gandolfi, Claudio; Cotting, Tatiana; Martinho, Paulo N; Sereda, Olha; Neels, Antonia; Morgan, Grace G; Albrecht, Martin

    2011-03-07

    New amphiphilic and spin-labile Mn(III) complexes based on dianionic N(4)O(2)-hexadentate sal(2)trien or sal(2)bapen ligands, which contain OC(6)H(13), OC(12)H(25), or OC(18)H(37) alkoxy substituents at different positions of the salicylidene unit were prepared (H(2)sal(2)trien = N,N'''-bis(salicylidene)-1,4,7,10-tetraazadecane, H(2)sal(2)bapen = N,N'''-bis(salicylidene)-1,5,8,12-tetraazadodecane). According to electrochemical measurements, these complexes undergo two (quasi)reversible redox processes. Temperature-dependent magnetic measurements revealed a high-spin configuration for all sal(2)trien complexes (S = 2) and gradual spin crossover for sal(2)bapen complexes from high to low spin (S = 1). The chain length strongly influences the spin crossover, as C(18)-functionalization stabilizes the low spin state at much higher temperatures than shorter alkyl chains. Moreover, long alkyl chains allow for spontaneous self-assembly of the molecules, which was investigated in single crystals and in Langmuir-films at the air-water interface. Long alkyl chains (C(12) or C(18)) as well as a mutual syn-orientation of these molecular recognition sites were required for the Langmuir monolayers to be stable.

  20. Contact-facilitated drug delivery with Sn2 lipase labile prodrugs optimize targeted lipid nanoparticle drug delivery

    PubMed Central

    Pan, Dipanjan; Pham, Christine TN; Weilbaecher, Katherine N; Tomasson, Michael H; Wickline, Samuel A; Lanza, Gregory M

    2016-01-01

    Sn2 lipase labile phospholipid prodrugs in conjunction with contact-facilitated drug delivery offer an important advancement in Nanomedicine. Many drugs incorporated into nanosystems, targeted or not, are substantially lost during circulation to the target. However, favorably altering the pharmacokinetics and volume of distribution of systemic drug delivery can offer greater efficacy with lower toxicity, leading to new prolonged-release nanoexcipients. However, the concept of achieving Paul Erhlich's inspired vision of a ‘magic bullet’ to treat disease has been largely unrealized due to unstable nanomedicines, nanosystems achieving low drug delivery to target cells, poor intracellular bioavailability of endocytosed nanoparticle payloads, and the substantial biological barriers of extravascular particle penetration into pathological sites. As shown here, Sn2 phospholipid prodrugs in conjunction with contact-facilitated drug delivery prevent premature drug diffusional loss during circulation and increase target cell bioavailability. The Sn2 phospholipid prodrug approach applies equally well for vascular constrained lipid-encapsulated particles and micelles the size of proteins that penetrate through naturally fenestrated endothelium in the bone marrow or thin-walled venules of an inflamed microcirculation. At one time Nanomedicine was considered a ‘Grail Quest’ by its loyal opposition and even many in the field adsorbing the pains of a long-learning curve about human biology and particles. However, Nanomedicine with innovations like Sn2 phospholipid prodrugs has finally made ‘made the turn’ toward meaningful translational success. PMID:26296541

  1. Assessing the Selectivity of Extractant Solutions for Recovering Labile Arsenic Associated with Iron (Hydr)oxides and Sulfides in Sediments

    EPA Science Inventory

    Sequential extractions can provide analytical constraints on the identification of mineral phases that control arsenic speciation in sediments. Model solids were used in this study to evaluate different solutions designed to extract arsenic from relatively labile solid phases. ...

  2. Detection of heat-labile enterotoxin-like activity in stools of patients with cholera and Escherichia coli diarrhea.

    PubMed Central

    Echeverria, P; Verheart, L; Ulyanco, C V; Santiago, L T

    1978-01-01

    The Y1 adrenal cell tissue culture assay was used to detect heat-labile enterotoxin-like activity in the stools of 14 of 74 patients with diarrhea. A positive effect of the stool on the adrenal cells was heat-labile and neutralized by cholera antitoxin. Enterotoxin-like activity was detected in the stools of 10 of 30 patients with cholera and in those of 2 of 4 from whom heat-labile Escherichia coli were isolated. None of the stools from nine individuals with Vibrio parahaemolyticus, Salmonella, or Shigella infections were positive. Two of 31 individuals from whom no pathogens were isolated had detectable toxin-like activity in their stools. The Y1 adrenal cell assay provides a rapid method of diagnosing heat-labile enterotoxigenic diarrhea and could be an adjunct in epidemiological studies of gastroenteritis. PMID:342414

  3. Molecular insights into the microbial formation of marine dissolved organic matter: recalcitrant or labile?

    NASA Astrophysics Data System (ADS)

    Koch, B. P.; Kattner, G.; Witt, M.; Passow, U.

    2014-08-01

    The degradation of marine dissolved organic matter (DOM) is an important control variable in the global carbon cycle. For our understanding of the kinetics of organic matter cycling in the ocean, it is crucial to achieve a mechanistic and molecular understanding of its transformation processes. A long-term microbial experiment was performed to follow the production of non-labile DOM by marine bacteria. Two different glucose concentrations and dissolved algal exudates were used as substrates. We monitored the bacterial abundance, concentrations of dissolved and particulate organic carbon (DOC, POC), nutrients, amino acids and transparent exopolymer particles (TEP) for 2 years. The molecular characterization of extracted DOM was performed by ultrahigh resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) after 70 days and after ∼2 years of incubation. Although glucose quickly degraded, a non-labile DOC background (5-9% of the initial DOC) was generated in the glucose incubations. Only 20% of the organic carbon from the algal exudate degraded within the 2 years of incubation. The degradation rates for the non-labile DOC background in the different treatments varied between 1 and 11 μmol DOC L-1 year-1. Transparent exopolymer particles, which are released by microorganisms, were produced during glucose degradation but decreased back to half of the maximum concentration within less than 3 weeks (degradation rate: 25 μg xanthan gum equivalents L-1 d-1) and were below detection in all treatments after 2 years. Additional glucose was added after 2 years to test whether labile substrate can promote the degradation of background DOC (co-metabolism; priming effect). A priming effect was not observed but the glucose addition led to a slight increase of background DOC. The molecular analysis demonstrated that DOM generated during glucose degradation differed appreciably from DOM transformed during the degradation of the algal exudates. Our

  4. Effect of cavitation on removal of alkali elements from coal

    NASA Astrophysics Data System (ADS)

    Srivalli, H.; Nirmal, L.; Nagarajan, R.

    2015-12-01

    The main impurities in coal are sulphur, ash and alkali. On combustion, the volatile forms of these impurities are either condensed on the boilers, or emitted in the form of potentially hazardous gases. The alkali elements present in coal help the fly ash particles adhere to boiler surfaces by providing a wet surface on which collection of these particles can take place. Use of ultrasonic techniques in cleaning of coal has stirred interest among researchers in recent times. Extraction of alkali elements by cavitation effect using low-frequency ultrasound, in the presence of reagents (HNO3 and H2O2) is reported in this paper. Powdered coal was dissolved with the reagent and exposed to ultrasonic fields of various frequencies at different time intervals. The treated solution is filtered and tested for alkali levels.

  5. Method for intercalating alkali metal ions into carbon electrodes

    DOEpatents

    Doeff, M.M.; Ma, Y.; Visco, S.J.; DeJonghe, L.

    1995-08-22

    A low cost, relatively flexible, carbon electrode for use in a secondary battery is described. A method is provided for producing same, including intercalating alkali metal salts such as sodium and lithium into carbon.

  6. Electric field-induced softening of alkali silicate glasses

    SciTech Connect

    McLaren, C.; Heffner, W.; Jain, H.; Tessarollo, R.; Raj, R.

    2015-11-02

    Motivated by the advantages of two-electrode flash sintering over normal sintering, we have investigated the effect of an external electric field on the viscosity of glass. The results show remarkable electric field-induced softening (EFIS), as application of DC field significantly lowers the softening temperature of glass. To establish the origin of EFIS, the effect is compared for single vs. mixed-alkali silicate glasses with fixed mole percentage of the alkali ions such that the mobility of alkali ions is greatly reduced while the basic network structure does not change much. The sodium silicate and lithium-sodium mixed alkali silicate glasses were tested mechanically in situ under compression in external electric field ranging from 0 to 250 V/cm in specially designed equipment. A comparison of data for different compositions indicates a complex mechanical response, which is observed as field-induced viscous flow due to a combination of Joule heating, electrolysis and dielectric breakdown.

  7. Method for intercalating alkali metal ions into carbon electrodes

    DOEpatents

    Doeff, Marca M.; Ma, Yanping; Visco, Steven J.; DeJonghe, Lutgard

    1995-01-01

    A low cost, relatively flexible, carbon electrode for use in a secondary battery is described. A method is provided for producing same, including intercalating alkali metal salts such as sodium and lithium into carbon.

  8. Hall Determination of Atomic Radii of Alkali Metals

    ERIC Educational Resources Information Center

    Houari, Ahmed

    2008-01-01

    I will propose here an alternative method for determining atomic radii of alkali metals based on the Hall measurements of their free electron densities and the knowledge of their crystal structure. (Contains 2 figures.)

  9. DuraLith Alkali-Aluminosilicate Geopolymer Waste Form Testing for Hanford Secondary Waste

    SciTech Connect

    Gong, W. L.; Lutz, Werner; Pegg, Ian L.

    2011-07-21

    The primary objective of the work reported here was to develop additional information regarding the DuraLith alkali aluminosilicate geopolymer as a waste form for liquid secondary waste to support selection of a final waste form for the Hanford Tank Waste Treatment and Immobilization Plant secondary liquid wastes to be disposed in the Integrated Disposal Facility on the Hanford Site. Testing focused on optimizing waste loading, improving waste form performance, and evaluating the robustness of the waste form with respect to waste variability.

  10. Electrochemical cell having an alkali-metal-nitrate electrode

    DOEpatents

    Roche, M.F.; Preto, S.K.

    1982-06-04

    A power-producing secondary electrochemical cell includes a molten alkali metal as the negative-electrode material and a molten-nitrate salt as the positive-electrode material. The molten material in the respective electrodes are separated by a solid barrier of alkali-metal-ion conducting material. A typical cell includes active materials of molten sodium separated from molten sodium nitrate and other nitrates in mixture by a layer of sodium ..beta..'' alumina.

  11. Alkali absorption and citrate excretion in calcium nephrolithiasis

    NASA Technical Reports Server (NTRS)

    Sakhaee, K.; Williams, R. H.; Oh, M. S.; Padalino, P.; Adams-Huet, B.; Whitson, P.; Pak, C. Y.

    1993-01-01

    The role of net gastrointestinal (GI) alkali absorption in the development of hypocitraturia was investigated. The net GI absorption of alkali was estimated from the difference between simple urinary cations (Ca, Mg, Na, and K) and anions (Cl and P). In 131 normal subjects, the 24 h urinary citrate was positively correlated with the net GI absorption of alkali (r = 0.49, p < 0.001). In 11 patients with distal renal tubular acidosis (RTA), urinary citrate excretion was subnormal relative to net GI alkali absorption, with data from most patients residing outside the 95% confidence ellipse described for normal subjects. However, the normal relationship between urinary citrate and net absorbed alkali was maintained in 11 patients with chronic diarrheal syndrome (CDS) and in 124 stone-forming patients devoid of RTA or CDS, half of whom had "idiopathic" hypocitraturia. The 18 stone-forming patients without RTA or CDS received potassium citrate (30-60 mEq/day). Both urinary citrate and net GI alkali absorption increased, yielding a significantly positive correlation (r = 0.62, p < 0.0001), with the slope indistinguishable from that of normal subjects. Thus, urinary citrate was normally dependent on the net GI absorption of alkali. This dependence was less marked in RTA, confirming the renal origin of hypocitraturia. However, the normal dependence was maintained in CDS and in idiopathic hypocitraturia, suggesting that reduced citrate excretion was largely dietary in origin as a result of low net alkali absorption (from a probable relative deficiency of vegetables and fruits or a relative excess of animal proteins).

  12. Rock Degradation by Alkali Metals: A Possible Lunar Erosion Mechanism.

    PubMed

    Naughton, J J; Barnes, I L; Hammond, D A

    1965-08-06

    When rocks melt under ultrahigh-vacuum conditions, their alkali components volatilize as metals. These metal vapors act to comminute polycrystalline rocks to their component minerals. The resultant powder is porous and loosely packed and its characteristics may be compatible with the lunar surface as revealed by the Ranger photographs. If meteorite impact or lunar volcanism has produced vaporization or areas of molten lava, alkali erosion may have given dust of this character in adjacent solid areas.

  13. Interactions of hydrogen with alkali promoted Ru/SiO2 catalysts: A proton NMR study

    SciTech Connect

    Uner, Denis Ozbay

    1994-05-10

    Role of H spillover to the silica support was studied using chemisorption; a strongly bound component of spilled over H was found in the silica support which interfered with accurate measurements of active metal sites via volumetric strong H chemisorption. The volumetric chemisorption technique was modified so that measurement times were reduced from 12--36 h to 1 h. The active Ru surface was characterized means of changes in proton spin counts and NMR Knight shifts vs alkali loading. Na, K blocked the active surface of Ru metal, but Cs was pushed off by H chemisorption. The alkali promoters restricted H mobility on both metal surface and at the metal support interfaces; this is consistent with effects on Fischer-Tropsch synthesis. 1H NMR was used to study the effect of the active metal and promoter on support hydroxyl groups. The OH group density in the silica support decreased with metal and/or promoter loading, but not on a one-to-one basis; the exchange efficiency of the hydroxyls decreased with atomic size of the alkali metal. An additional downfield proton resonance was detected which was assigned to the alkali hydroxide species in the support.

  14. Vibrations of alkali metal overlayers on metal surfaces

    NASA Astrophysics Data System (ADS)

    Rusina, G. G.; Eremeev, S. V.; Echenique, P. M.; Benedek, G.; Borisova, S. D.; Chulkov, E. V.

    2008-06-01

    We review the current progress in the understanding of vibrations of alkalis adsorbed on metal surfaces. The analysis of alkali vibrations was made on the basis of available theoretical and experimental results. We also include in this discussion our recent calculations of vibrations in K/Pt(111) and Li(Na)/Cu(001) systems. The dependence of alkali adlayer localized modes on atomic mass, adsorption position and coverage as well as the dependence of vertical vibration frequency on the substrate orientation is discussed. The square root of atomic mass dependence of the vertical vibration energy has been confirmed by using computational data for alkalis on the Al(111) and Cu(001) substrates. We have confirmed that in a wide range of submonolayer coverages the stretch mode energy remains nearly constant while the energy of in-plane polarized modes increases with the increase of alkali coverage. It was shown that the spectrum of both stretch and in-plane vibrations can be very sensitive to the adsorption position of alkali atoms and substrate orientation.

  15. Alkali metal yttrium neo-pentoxide double alkoxide precursors to alkali metal yttrium oxide nanomaterials

    DOE PAGES

    Boyle, Timothy J.; Neville, Michael L.; Sears, Jeremiah Matthew; ...

    2016-03-15

    In this study, a series of alkali metal yttrium neo-pentoxide ([AY(ONep)4]) compounds were developed as precursors to alkali yttrium oxide (AYO2) nanomaterials. The reaction of yttrium amide ([Y(NR2)3] where R=Si(CH3)3) with four equivalents of H-ONep followed by addition of [A(NR2)] (A=Li, Na, K) or Ao (Ao=Rb, Cs) led to the formation of a complex series of AnY(ONep)3+n species, crystallographically identified as [Y2Li3(μ3-ONep)(μ3-HONep)(μ-ONep)5(ONep)3(HONep)2] (1), [YNa2(μ3-ONep)4(ONep)]2 (2), {[Y2K3(μ3-ONep)3(μ-ONep)4(ONep)2(ηξ-tol)2][Y4K2(μ4-O)(μ3-ONep)8(ONep)4]•ηx-tol]} (3), [Y4K2(μ4-O)(μ3-ONep)8(ONep)4] (3a), [Y2Rb3(μ4-ONep)3(μ-ONep)6] (4), and [Y2Cs4(μ6-O)(μ3-ONep)6(μ3-HONep)2(ONep)2(ηx-tol)4]•tol (5). Compounds 1–5 were investigated as single source precursors to AYOx nanomaterials following solvothermal routes (pyridine, 185 °C for 24h). The final products after thermal processing weremore » found by powder X-ray diffraction experiments to be Y2O3 with variable sized particles based on transmission electron diffraction. Energy dispersive X-ray spectroscopy studies indicated that the heavier alkali metal species were present in the isolated nanomaterials.« less

  16. Relation between the electroforming voltage in alkali halide-polymer diodes and the bandgap of the alkali halide

    SciTech Connect

    Bory, Benjamin F.; Wang, Jingxin; Janssen, René A. J.; Meskers, Stefan C. J.; Gomes, Henrique L.; De Leeuw, Dago M.

    2014-12-08

    Electroforming of indium-tin-oxide/alkali halide/poly(spirofluorene)/Ba/Al diodes has been investigated by bias dependent reflectivity measurements. The threshold voltages for electrocoloration and electroforming are independent of layer thickness and correlate with the bandgap of the alkali halide. We argue that the origin is voltage induced defect formation. Frenkel defect pairs are formed by electron–hole recombination in the alkali halide. This self-accelerating process mitigates injection barriers. The dynamic junction formation is compared to that of a light emitting electrochemical cell. A critical defect density for electroforming is 10{sup 25}/m{sup 3}. The electroformed alkali halide layer can be considered as a highly doped semiconductor with metallic transport characteristics.

  17. The Stable and Radio- Carbon Isotopic Content of Labile and Refractory Carbon in Atmospheric Particulate Matter

    NASA Astrophysics Data System (ADS)

    McNichol, A. P.; Rosenheim, B. E.; Gerlach, D. S.; Hayes, J. M.

    2006-12-01

    Studies of the isotopic content of atmospheric particulate matter are hampered by difficulties in chemically defining the pools of carbon and analytically isolating the different pools. We are conducting studies on reference materials and atmospheric aerosol samples to develop a method to measure stable and radio- carbon isotopes on the labile and refractory carbon. We are using a flow-through combustion system that allows us to combust, collect and measure the isotopic content of the gases produced at all stages of heating/oxidizing. We compare our results to those measured using a chemothermal oxidation method (CTO) (Gustafsson et al., 2001). In this method, refractory carbon is defined as the material remaining after pre- combusting a sample at 375°C in the presence of oxygen for 24 hours. The reference materials are diesel soot, apple leaves and a hybrid of the two (DiesApple), all from NIST. These provide carbon with two well-defined fractions -- the soot provides refractory carbon that is radiocarbon dead and the apple leaves provide organic carbon that is radiocarbon modern. Radiocarbon results from DiesApple indicate that the "refractory" carbon defined by the CTO method is actually a mixture of old and modern carbon that contains over 25% modern carbon. This suggests that charred material formed from the apples leaves during the pre-combustion step is contributing to the fraction we identify as refractory carbon. We are studying this by analyzing the individual materials and the mixture using our flow-through system. First results with this system indicate that the refractory fraction trapped from the DiesApple contains much less modern carbon than the CTO method, less than 7%. We will present detailed concentration and isotopic results of the generation of carbon dioxide during programmed combustion of each of the reference materials. We studied the radiocarbon content of both the total carbon (TC) and refractory carbon in the fine particulate matter (PM

  18. Dissolved gaseous mercury concentration and mercury evasional flux from seawater in front of a chlor-alkali plant.

    PubMed

    Ferrara, R; Lanzillotta, E; Ceccarini, C

    2001-08-01

    The dissolved gaseous mercury concentration and mercury degassing rate have been measured in a marine area polluted by a chlor-alkali plant (Rosignano Solvay, Italy), which uses mercury in chlorine production. During the summer the DGM concentration (130 pg l(-1)) and the evasional flux (14 ng m(-2) h(-1)) were 3-4 times higher than those measured at the control stations. A seasonal behaviour has been highlighted at all the sampling sites, with minimum levels in the winter.

  19. Superconductivity in alkali-doped fullerene nanowhiskers

    NASA Astrophysics Data System (ADS)

    Takeya, Hiroyuki; Konno, Toshio; Hirata, Chika; Wakahara, Takatsugu; Miyazawa, Kun'ichi; Yamaguchi, Takahide; Tanaka, Masashi; Takano, Yoshihiko

    2016-09-01

    Superconductivity in alkali metal-doped fullerene nanowhiskers (C60NWs) was observed in K3.3C60NWs, Rb3.0C60NWs and Cs2.0Rb1.0C60NWs with transition temperatures at 17, 25 and 26 K, respectively. Almost full shielding volume fraction (~80%) was observed in K3.3C60NWs when subjected to thermal treatment at 200 °C for a duration of 24 h. In contrast, the shielding fraction of Rb3.0C60NWs and Cs2.0Rb1.0C60NWs were calculated to be 8% and 6%, respectively. Here we report on an extensive investigation of the superconducting properties of these AC60NWs (A  =  K3.3, Rb3.0 and Cs2.0Rb1.0). These properties are compared to the ones reported on the corresponding conventional (single-crystal or powder) K-doped fullerene. We also evaluated the critical current densities of these C60NWs using the Bean model under an applied magnetic field up to 50 kOe.

  20. Bioinorganic Chemistry of the Alkali Metal Ions.

    PubMed

    Kim, Youngsam; Nguyen, Thuy-Tien T; Churchill, David G

    2016-01-01

    The common Group 1 alkali metals are indeed ubiquitous on earth, in the oceans and in biological systems. In this introductory chapter, concepts involving aqueous chemistry and aspects of general coordination chemistry and oxygen atom donor chemistry are introduced. Also, there are nuclear isotopes of importance. A general discussion of Group 1 begins from the prevalence of the ions, and from a comparison of their ionic radii and ionization energies. While oxygen and water molecule binding have the most relevance to biology and in forming a detailed understanding between the elements, there is a wide range of basic chemistry that is potentially important, especially with respect to biological chelation and synthetic multi-dentate ligand design. The elements are widely distributed in life forms, in the terrestrial environment and in the oceans. The details about the workings in animal, as well as plant life are presented in this volume. Important biometallic aspects of human health and medicine are introduced as well. Seeing as the elements are widely present in biology, various particular endogenous molecules and enzymatic systems can be studied. Sodium and potassium are by far the most important and central elements for consideration. Aspects of lithium, rubidium, cesium and francium chemistry are also included; they help in making important comparisons related to the coordination chemistry of Na(+) and K(+). Physical methods are also introduced.

  1. Superconductivity in alkali-metal-doped picene.

    PubMed

    Mitsuhashi, Ryoji; Suzuki, Yuta; Yamanari, Yusuke; Mitamura, Hiroki; Kambe, Takashi; Ikeda, Naoshi; Okamoto, Hideki; Fujiwara, Akihiko; Yamaji, Minoru; Kawasaki, Naoko; Maniwa, Yutaka; Kubozono, Yoshihiro

    2010-03-04

    Efforts to identify and develop new superconducting materials continue apace, motivated by both fundamental science and the prospects for application. For example, several new superconducting material systems have been developed in the recent past, including calcium-intercalated graphite compounds, boron-doped diamond and-most prominently-iron arsenides such as LaO(1-x)F(x)FeAs (ref. 3). In the case of organic superconductors, however, no new material system with a high superconducting transition temperature (T(c)) has been discovered in the past decade. Here we report that intercalating an alkali metal into picene, a wide-bandgap semiconducting solid hydrocarbon, produces metallic behaviour and superconductivity. Solid potassium-intercalated picene (K(x)picene) shows T(c) values of 7 K and 18 K, depending on the metal content. The drop of magnetization in K(x)picene solids at the transition temperature is sharp (<2 K), similar to the behaviour of Ca-intercalated graphite. The T(c) of 18 K is comparable to that of K-intercalated C(60) (ref. 4). This discovery of superconductivity in K(x)picene shows that organic hydrocarbons are promising candidates for improved T(c) values.

  2. The timing of alkali metasomatism in paleosols

    NASA Technical Reports Server (NTRS)

    MacFarlane, A. W.; Holland, H. D.

    1991-01-01

    We have measured the concentrations of rubidium and strontium and 87Sr/86Sr values of whole-rock samples from three paleosols of different ages. The oldest of the three weathering horizons, the 2,760 Ma Mt. Roe #1 paleosol in the Fortescue Group of Western Australia, experienced addition of Rb, and probably Sr, at 2,168 +/- 10 Ma. The intermediate paleosol, developed on the Hekpoort Basalt in South Africa, is estimated to have formed at 2,200 Ma, and yields a Rb-Sr isochron age of 1,925 +/- 32 Ma. The youngest of the three paleosols, developed on the Ongeluk basalt in Griqualand West, South Africa ca. 1,900 Ma, yielded a Rb-Sr age of 1,257 +/- 11 Ma. The Rb-Sr systematics of all three paleosols were reset during post-weathering metasomatism related to local or regional thermal disturbances. The Rb-Sr systematics of the paleosols were not subsequently disturbed. The near-complete removal of the alkali and alkaline earth elements from these paleosols during weathering made them particularly susceptible to resetting of their Rb-Sr systematics. Paleosols of this type are therefore sensitive indicators of the timing of thermal disturbances.

  3. Efficient destruction of CF4 through in situ generation of alkali metals from heated alkali halide reducing mixtures.

    PubMed

    Lee, Myung Churl; Choi, Wonyong

    2002-03-15

    Perfluorocarbons (PFCs) are the most potent green house gases that are very recalcitrant at destruction. An effective way of converting PFCs using hot solid reagents into safe products has been recently introduced. By investigating the thermal reductive destruction of tetrafluoromethane (CF4) we provided new insight and more physicochemical consideration on this novel process. The complete destruction of CF4was successfully achieved by flowing the gas through a heated reagent bed (400-950 degrees C) that contained powder mixtures of alkali halides, CaO, and Si. The silicon acted as a reducing agent of alkali halides for the in-situ production of alkali metals, and the calcium oxide played the role of a halide ion acceptor. The absence of any single component in this ternary mixture drastically reduced the destruction efficiency of CF4. The CF4 destruction efficiencies with the solid reagent containing the alkali halide, MX, increased in the order of Li approximately Na < K < Cs for alkali cations and I < Br < Cl < F for halide anions. This trend agreed with the endothermicity of the alkali metal generation reaction: the higher the endothermicity, the lower the destruction efficiency. Alkali metal generation was indirectly detected by monitoring H2 production from its reaction with water. The production of alkali metals increased with NaF, KF, and CsF in this order. The CsF/CaO/Si system exhibited the complete destruction of CF4 at as low as 600 degrees C. The solid product analysis by X-ray diffraction (XRD) showed the formation of CaF2 and the depletion of Si with black carbon particles formed in the solid reagent residue. No CO/CO2 and toxic HF and SiF4 formation were detected in the exhaust gas.

  4. On-chip fabrication of alkali-metal vapor cells utilizing an alkali-metal source tablet

    NASA Astrophysics Data System (ADS)

    Tsujimoto, K.; Ban, K.; Hirai, Y.; Sugano, K.; Tsuchiya, T.; Mizutani, N.; Tabata, O.

    2013-11-01

    We describe a novel on-chip microfabrication technique for the alkali-metal vapor cell of an optically pumped atomic magnetometer (OPAM), utilizing an alkali-metal source tablet (AMST). The newly proposed AMST is a millimeter-sized piece of porous alumina whose considerable surface area holds deposited alkali-metal chloride (KCl) and barium azide (BaN6), source materials that effectively produce alkali-metal vapor at less than 400 °C. Our experiments indicated that the most effective pore size of the AMST is between 60 and 170 µm. The thickness of an insulating glass spacer holding the AMST was designed to confine generated alkali metal to the interior of the vapor cell during its production, and an integrated silicon heater was designed to seal the device using a glass frit, melted at an optimum temperature range of 460-490 °C that was determined by finite element method thermal simulation. The proposed design and AMST were used to successfully fabricate a K cell that was then operated as an OPAM with a measured sensitivity of 50 pT. These results demonstrate that the proposed concept for on-chip microfabrication of alkali-metal vapor cells may lead to effective replacement of conventional glassworking approaches.

  5. Alkali-aggregate reactivity of typical siliceious glass and carbonate rocks in alkali-activated fly ash based geopolymers

    NASA Astrophysics Data System (ADS)

    Lu, Duyou; Liu, Yongdao; Zheng, Yanzeng; Xu, Zhongzi; Shen, Xiaodong

    2013-08-01

    For exploring the behaviour of alkali-aggregate reactivity (AAR) in alkali-activated geopolymeric materials and assessing the procedures for testing AAR in geopolymers, the expansion behaviour of fly ash based geopolymer mortars with pure silica glass and typical carbonate rocks were studied respectively by curing at various conditions, i.e. 23°C and 38°C with relative humidity over 95%, immersed in 1M NaOH solution at 80°C. Results show that, at various curing conditions, neither harmful ASR nor harmful ACR was observed in geopolymers with the criteria specified for OPC system. However, with the change of curing conditions, the geopolymer binder and reactive aggregates may experience different reaction processes leading to quite different dimensional changes, especially with additional alkalis and elevated temperatures. It suggests that high temperature with additional alkali for accelerating AAR in traditional OPC system may not appropriate for assessing the alkali-aggregate reactivity behaviour in geopolymers designed for normal conditions. On the other hand, it is hopeful to control the dimensional change of geopolymer mortar or concrete by selecting the type of aggregates and the appropriate curing conditions, thus changing the harmful AAR in OPC into beneficial AAR in geopolymers and other alkali-activated cementitious systems.

  6. Mercury accumulation in transplanted Hypogymnia physodes lichens downwind of Wisconsin chlor-alkali plant

    USGS Publications Warehouse

    Makholm, M.M.; Bennett, J.P.

    1998-01-01

    Emissions of mercury from a chlor-alkali plant in central Wisconsin have raised concern about possible effects on biota in the area. Samples of the lichen Hypogymnia physodes, which no longer grows in the area, were transplanted from a site in northeastern Wisconsin and positioned on plastic stands at varying distances up to 1250 m from the plant and sampled for Hg quarterly for one year to test the hypothesis that Hg would be taken up by the lichens and would decline with distance. Average tissue concentrations were elevated when first sampled at three months and continued to increase at the nearest sites until the study ended after one year. Average concentrations after a year of exposure ranged from 4418 ppb at 250 m from the plant to 403 ppb at 1250 m from the plant. The decrease over distance followed a negative exponential pattern. Background concentrations at a control site in northern Wisconsin averaged 155 ppb.

  7. Interactions between recalcitrant and labile organic carbon in streams - Can stream biofilms mediate a priming effect?

    NASA Astrophysics Data System (ADS)

    Bengtsson, M. M.; Wagner, K.; Herberg, E. R.; Burns, N. R.; Wanek, W.; Battin, T. J.

    2012-04-01

    Inland waters - such as streams, rivers and lakes - are increasingly recognized as important components in the global carbon cycle. Dissolved organic carbon (DOC) in these systems is diverse in structure, origin and reactivity, and a fraction of it is regarded as recalcitrant to microbial degradation. In soils, degradation of recalcitrant carbon is often controlled by the availability of labile carbon sources. This is linked to the priming effect (PE). Mounting evidence suggests that PE is also important in aquatic ecosystems but there are so far very few studies addressing this topic. Biofilms are vital components of aquatic ecosystems. In stream biofilms, heterotrophic bacteria and algae coexist in close proximity, exposing the bacteria to both recalcitrant DOC of terrestrial origin and labile organic carbon from the algae. We hypothesize that this makes stream biofilms hotspots for PE. We used plug-flow bioreactors inoculated with natural stream biofilm bacterial communities to test the potential of a priming effect in aquatic ecosystems. The bioreactors were amended with an isotope-labeled plant extract serving as a model of recalcitrant DOC in streams. Labile carbon sources, in the form of glucose and an algal extract were added to induce PE. Nitrate and phosphate were also added to assess the role of these inorganic nutrients on carbon uptake. Microbial uptake of the different carbon sources was monitored by measuring the concentrations and isotopic ratios of respired CO2, biomass and DOC. Our results suggest that the priming effect plays a role in stream carbon cycling and that it is potentially an important process in other aquatic ecosystems.

  8. Biosolids application affects the competitive sorption and lability of cadmium, copper, nickel, lead, and zinc in fluvial and calcareous soils.

    PubMed

    Shaheen, Sabry M; Antoniadis, Vasileios; Kwon, Eilhann E; Biswas, Jayanta K; Wang, Hailong; Ok, Yong Sik; Rinklebe, Jörg

    2017-03-03

    The objective of this research was to investigate the effects of biosolids on the competitive sorption and lability of the sorbed Cd, Cu, Ni, Pb, and Zn in fluvial and calcareous soils. Competitive sorption isotherms were developed, and the lability of these metals was estimated by DTPA extraction following their sorption. Sorption of all metals was higher in the fluvial than in the calcareous soil. Sorption of Cu and Pb was stronger than that of Cd, Ni, and Zn in all soils. Biosolids application (2.5%) reduced the sorption of all metals especially Cu and Pb (28-43%) in both soils (especially the calcareous soil) at the lower added metal concentrations (50 and 100 mg L(-1)). However, it increased the sorption of all metals especially Pb and Cu in both soils (especially the calcareous soil; 15.5-fold for Cu) at the higher added concentrations (250 and 300 mg L(-1)). Nickel showed the highest lability followed by Cd, Zn, and Pb in both soils. Biosolids increased the lability of the sorbed Ni in the fluvial soils at all added concentrations and the lability of Cd, Pb, and Zn at 50 mg L(-1), but decreased the lability of Cd, Pb, and Zn at 250 and 300 mg L(-1) in both soils. We conclude that at low loading rate (e.g., 50 mg L(-1)) biosolids treatment might increase the lability and environmental risk of Cd, Cu, Pb, and Zn. However, at high loading rate (e.g., 300 mg L(-1)) biosolids may be used as an immobilizing agent for Cd, Cu, Pb, Zn and mobilizing agent for Ni.

  9. Enantiomeric Excesses of Acid Labile Amino Acid Precursors of the Murchison Meteorite

    NASA Technical Reports Server (NTRS)

    Pizzarello, Sandra

    1998-01-01

    Amino acids present in carbonaceous chondrite are extracted in water in part as free compounds and in approximately equal part as acid labile precursors. On the assumption that they would be free of contamination, the precursors of two Murchison amino acids that have terrestrial occurrence, alanine and glutamic acid, have been targeted for analysis of their enantiomeric ratios. Pyroglutamic acid, the precursor of glutamic acid, was found with an L-enantiomeric excess comparable to that of the free acid, while alanine's precursor, N-acetyl alanine, appears approximately racemic. Also alpha-imino propioacetic acid, a proposed end product of alanine synthesis in the meteorite, was analyzed and found racemic.

  10. Nature of chiral-induced equilibrium shifts in racemic labile lanthanide complexes

    SciTech Connect

    Wu, Shuguang; Hilmes, G.L.; Riehl, J.P. )

    1989-03-23

    An analysis of the chiral-induced equilibrium shift of racemic D{sub 3} tris-terdendate complexes of lanthanides with 2,6-pyridinedicarboxylate is presented in terms of the associated/dissociated models of Schipper. Results are presented which indicate that the so-called Pfeiffer effect in these lanthanide complexes is best described by the dissociated model, as was determined for similar labile transition-metal complexes. The nature of the chiral discriminatory interaction is shown to be largely electrostatic by measurements in mixed solvents of varying dielectric constant.

  11. Experimental Observation of the Nature of Weak Chemical Bonds in Labile Compounds.

    PubMed

    Hashizume, Daisuke

    2017-02-15

    Accurate single-crystal X-ray diffraction data afford a total electron density distribution for crystalline materials by employing an aspherical atomic model with comparable accuracy to that of theoretical calculations. Chemical bonds and intermolecular interactions in the crystalline state are characterized based on the electron density distribution of valence electrons, as well as structural parameters. Herein, the bonding nature of weak chemical bonds in labile compounds, such as hypervalent bonds and delocalized π-bonds, is explored on the basis of electronic structures derived from experimental electron density distribution analyses. In addition, the visualization of a radicalic orbital distribution on an sp(2) -hydridized carbon atom is demonstrated.

  12. Essential oil composition of the fruits of Periploca laevigata Aiton subsp. angustifolia (Labill.) Markgraf (Apocynaceae - Periplocoideae).

    PubMed

    Zito, Pietro; Sajeva, Maurizio; Bruno, Maurizio; Maggio, Antonella; Rosselli, Sergio; Senatore, Felice; Formisano, Carmen

    2011-08-01

    The essential oil of the fruits of Periploca laevigata Aiton subsp. angustifolia (Labill.) Markgraf (Apocynaceae) from Lampedusa Island was obtained by hydrodistillation and its composition was analysed. The analyses allowed the identification and quantification of 64 volatile compounds belonging to different classes. The most abundant compounds were nonacosane, heptacosane, hentriacontane and δ-cadinene. Among the volatile compounds identified in the fruits of P. laevigata subsp. angustifolia, 31 are present in other taxa of Apocynaceae, 19 have antimicrobial activity and four are pheromones for the butterfly Danaus chrysippus. The possible ecological role of the volatile compounds found is briefly discussed.

  13. Mechanism-based design of labile precursors for chromium(I) chemistry

    SciTech Connect

    Akturk, Eser S.; Yap, Glenn P. A.; Theopold, Klaus H.

    2015-08-27

    Here, we report that dinitrogen complexes of the type TpR,RCr–N2–CrTpR,R are not the most labile precursors for Cr(I) chemistry, as they are sterically protected from obligatory associative ligand substitution. A mononuclear alkyne complex – TptBu,MeCr(η2-C2(SiMe3)2) – proved to be much more reactive.

  14. The reaction dynamics of alkali dimer molecules and electronically excited alkali atoms with simple molecules

    SciTech Connect

    Hou, Hongtao

    1995-12-01

    This dissertation presents the results from the crossed molecular beam studies on the dynamics of bimolecular collisions in the gas phase. The primary subjects include the interactions of alkali dimer molecules with simple molecules, and the inelastic scattering of electronically excited alkali atoms with O2. The reaction of the sodium dimers with oxygen molecules is described in Chapter 2. Two reaction pathways were observed for this four-center molecule-molecule reaction, i.e. the formations of NaO2 + Na and NaO + NaO. NaO2 products exhibit a very anisotropic angular distribution, indicating a direct spectator stripping mechanism for this reaction channel. The NaO formation follows the bond breaking of O2, which is likely a result of a charge transfer from Na2 to the excited state orbital of O2-. The scattering of sodium dimers from ammonium and methanol produced novel molecules, NaNH3 and Na(CH3OH), respectively. These experimental observations, as well as the discussions on the reaction dynamics and the chemical bonding within these molecules, will be presented in Chapter 3. The lower limits for the bond dissociation energies of these molecules are also obtained. Finally, Chapter 4 describes the energy transfer between oxygen molecules and electronically excited sodium atoms.

  15. Mixed alkali effect on the spectroscopic properties of alkali-alkaline earth oxide borate glasses

    NASA Astrophysics Data System (ADS)

    Srinivas, G.; Ramesh, B.; Shareefuddin, Md.; Chary, M. N.; Sayanna, R.

    2016-05-01

    The mixed alkali and alkaline earth oxide borate glass with the composition xK2O - (25-x) Li2O-12.5BaO-12.5MgO-50B2O3 (x = 0, 5, 10, 15, 20 and 25mol %) and doped with 1mol% CuO were prepared by the melt quenching technique. From the optical absorption spectra the optical band gap, electronic polarizability(α02-), interaction parameter (A), theoretical and experimental optical basicity (Λ) values were evaluated. From the Electron Paramagnetic Resonance (EPR) spectral data the number of spins (N) and susceptibility (χ) were evaluated. The values of (α02-), and (Λ) increases with increasing of K2O content and electronic polarizability and interaction parameter show opposite behaviuor which may be due to the creation of non-bridging oxygens and expansion of borate network. The reciprocal of susceptibility (1/χ) and spin concentration (N) as a function of K2O content, varied nonlinearly which may be due to creation of non-bridging oxygens in the present glass system. This may be attributed to mixed alkali effect (MAE).

  16. Water Content of Lunar Alkali Fedlspar

    NASA Technical Reports Server (NTRS)

    Mills, R. D.; Simon, J. I.; Wang, J.; Alexander, C. M. O'D.; Hauri, E. H.

    2016-01-01

    Detection of indigenous hydrogen in a diversity of lunar materials, including volcanic glass, melt inclusions, apatite, and plagioclase suggests water may have played a role in the chemical differentiation of the Moon. Spectroscopic data from the Moon indicate a positive correlation between water and Th. Modeling of lunar magma ocean crystallization predicts a similar chemical differentiation with the highest levels of water in the K- and Th-rich melt residuum of the magma ocean (i.e. urKREEP). Until now, the only sample-based estimates of water content of KREEP-rich magmas come from measurements of OH, F, and Cl in lunar apatites, which suggest a water concentration of < 1 ppm in urKREEP. Using these data, predict that the bulk water content of the magma ocean would have <10 ppm. In contrast, estimate water contents of 320 ppm for the bulk Moon and 1.4 wt % for urKREEP from plagioclase in ferroan anorthosites. Results and interpretation: NanoSIMS data from granitic clasts from Apollo sample 15405,78 show that alkali feldspar, a common mineral in K-enriched rocks, can have approx. 20 ppm of water, which implies magmatic water contents of approx. 1 wt % in the high-silica magmas. This estimate is 2 to 3 orders of magnitude higher than that estimated from apatite in similar rocks. However, the Cl and F contents of apatite in chemically similar rocks suggest that these melts also had high Cl/F ratios, which leads to spuriously low water estimates from the apatite. We can only estimate the minimum water content of urKREEP (+ bulk Moon) from our alkali feldspar data because of the unknown amount of degassing that led to the formation of the granites. Assuming a reasonable 10 to 100 times enrichment of water from urKREEP into the granites produces an estimate of 100-1000 ppm of water for the urKREEP reservoir. Using the modeling of and the 100-1000 ppm of water in urKREEP suggests a minimum bulk silicate Moon water content between 2 and 20 ppm. However, hydrogen loss was

  17. Hydrogen Adsorption by Alkali Metal Graphite Intercalation Compounds

    NASA Astrophysics Data System (ADS)

    Purewal, Justin

    Adsorption occurs whenever a solid surface is exposed to a gas or liquid, and is characterized by an increase in fluid density near the interface. Adsorbents have drawn attention in the current effort to engineer materials that store hydrogen at high densities within moderate temperature and pressure regimes. Carbon adsorbents are a logical choice as a storage material due to their low costs and large surface areas. Unfortunately, carbon adsorbents suffer from a low binding enthalpy for H2 (about 5 kJ mol-1), well below the 15 to 18 kJ mol-1) that is considered optimal for hydrogen storage systems. Binding interactions can be increased by the following methods: (1) adjusting the graphite interplanar separation with a pillared structure, and (2) introducing dopant species that interact with H2 molecules by strong electrostatic forces. Graphite intercalation compounds are a class of materials that contain both pillared structures and chemical dopants, making them an excellent model system for studying the fundamentals of hydrogen adsorption in nanostructured carbons. Pressure-composition-temperature diagrams of the MC24(H 2)x graphite intercalation compounds were measured for M = (K, Rb, Cs). Adsorption enthalpies were measured as a function of H2 concentration. Notably, CsC24 had an average adsorption enthalpy of 14.9 kJ mol-1), nearly three times larger than that of pristine graphite. The adsorption enthalpies were found to be positively correlated with the alkali metal size. Adsorption capacities were negatively correlated with the size of the alkali metal. The rate of adsorption is reduced at large H2 compositions, due to the effects of site-blocking and correlation on the H2 diffusion. The strong binding interaction and pronounced molecular-sieving behavior of KC24 is likely to obstruct the translational diffusion of adsorbed H2 molecules. In this work, the diffusion of H2 adsorbed in KC24 was studied by quasielastic neutron scattering measurements and molecular

  18. Alkali content of alpine ultramafic rocks

    USGS Publications Warehouse

    Hamilton, W.; Mountjoy, W.

    1965-01-01

    The lower limit of abundance of sodium and potassium in ultramafic rocks is less than the threshold amount detectable by conventional analytical methods. By a dilutionaddition modification of the flame-spectrophotometric method, sodium and potassium have been determined in 40 specimens of alpine ultramafic rocks. Samples represent six regions in the United States and one in Australia, and include dunite, peridotite, pyroxenite, and their variably serpentinized and metamorphosed derivatives. The median value found for Na2O is 0.004 per cent, and the range of Na2O is 0.001-0.19. The median value for K2O is 0.0034 per cent and the range is 0.001-0.031 per cent. Alkali concentrations are below 0.01 per cent Na2O in 28 samples and below 0.01 per cent K2O in 35. Derivation of basalt magma from upper-mantle material similar to such ultramafic rocks, as has been postulated, is precluded by the relative amounts of sodium and potassium, which are from 200 to 600 times more abundant in basalt than in the ultramafic rocks. Similar factors apply to a number of other elements. No reasonable process could produce such concentrations in, for example, tens of thousands of cubic miles of uniform tholeiitic basalt. The ultramafic rocks might have originated either as magmatic crystal precipitates or as mantle residues left after fusion and removal of basaltic magma. Injection of ultramafic rocks to exposed positions is tectonic rather than magmatic. ?? 1965.

  19. 3718-F Alkali Metal Treatment and Storage Facility Closure Plan. Revision 1

    SciTech Connect

    1992-11-01

    The Hanford Site, located northwest of the city of Richland, Washington, houses reactors, chemical-separation systems, and related facilities used for the production of special nuclear materials, as well as for activities associated with nuclear energy development. The 300 Area of the Hanford Site contains reactor fuel manufacturing facilities and several research and development laboratories. The 3718-F Alkali Metal Treatment and Storage Facility (3718-F Facility), located in the 300 Area, was used to store and treat alkali metal wastes. Therefore, it is subject to the regulatory requirements for the storage and treatment of dangerous wastes. Closure will be conducted pursuant to the requirements of the Washington Administrative Code (WAC) 173-303-610 (Ecology 1989) and 40 CFR 270.1. Closure also will satisfy the thermal treatment facility closure requirements of 40 CFR 265.381. This closure plan presents a description of the 3718-F Facility, the history of wastes managed, and the approach that will be followed to close the facility. Only hazardous constituents derived from 3718-F Facility operations will be addressed.

  20. Effects of lability of metal complex on free ion measurement using DMT.

    PubMed

    Weng, Liping; Van Riemsdijk, Willem H; Temminghoff, Erwin J M

    2010-04-01

    Very low concentrations of free metal ion in natural samples can be measured using the Donnan membrane technique (DMT) based on ion transport kinetics. In this paper, the possible effects of slow dissociation of metal complexes on the interpretation of kinetic DMT are investigated both theoretically and experimentally. The expressions of the lability parameter, Lgrangian , were derived for DMT. Analysis of new experimental studies using synthetic solution containing NTA as the ligand and Cu(2+) ions shows that when the ionic strength is low (labile species measured using other dynamic sensors (DGT, GIME) in several freshwaters, it is concluded that in most waters ion transport in DMT is controlled by diffusion in the membrane. Only in very soft waters (<0.7 mM Ca+Mg), the dissociation rate of natural metal complex may influence ion transport in DMT. In this case, neglecting this effect may lead to an underestimation of the free metal ion concentration measured.

  1. Acid-Labile Amphiphilic PEO-b-PPO-b-PEO Copolymers: Degradable Poloxamer Analogs.

    PubMed

    Worm, Matthias; Kang, Biao; Dingels, Carsten; Wurm, Frederik R; Frey, Holger

    2016-05-01

    Poly ((ethylene oxide)-b-(propylene oxide)-b-(ethylene oxide)) triblock copolymers commonly known as poloxamers or Pluronics constitute an important class of nonionic, biocompatible surfactants. Here, a method is reported to incorporate two acid-labile acetal moieties in the backbone of poloxamers to generate acid-cleavable nonionic surfactants. Poly(propylene oxide) is functionalized by means of an acetate-protected vinyl ether to introduce acetal units. Three cleavable PEO-PPO-PEO triblock copolymers (Mn,total = 6600, 8000, 9150 g·mol(-1) ; Mn,PEO = 2200, 3600, 4750 g·mol(-1) ) have been synthesized using anionic ring-opening polymerization. The amphiphilic copolymers exhibit narrow molecular weight distributions (Ð = 1.06-1.08). Surface tension measurements reveal surface-active behavior in aqueous solution comparable to established noncleavable poloxamers. Complete hydrolysis of the labile junctions after acidic treatment is verified by size exclusion chromatography. The block copolymers have been employed as surfactants in a miniemulsion polymerization to generate polystyrene (PS) nanoparticles with mean diameters of ≈200 nm and narrow size distribution, as determined by dynamic light scattering and scanning electron microscopy. Acid-triggered precipitation facilitates removal of surfactant fragments from the nanoparticles, which simplifies purification and enables nanoparticle precipitation "on demand."

  2. Constraints on Transport and Emplacement Mechanisms of Labile Fractions in Lunar Cold Traps

    NASA Technical Reports Server (NTRS)

    Rickman, D.; Gertsch, L.

    2014-01-01

    Sustaining the scientific exploration of the Solar System will require a significant proportion of the necessary fuels and propellants, as well as other bulk commodities, to be produced from local raw materials [1]. The viability of mineral production depends on the ability to locate and characterize mineable deposits of the necessary feedstocks. This requires, among other things, a workable understanding of the mechanisms by which such deposits form, which is the subject of Economic Geology. Multiple deposition scenarios are possible for labile materials on the Moon. This paper suggests labile fractions moved diffusely through space; deposits may grow richer with depth until low porosity rock; lateral transport is likely to have occurred with the regolith, at least for short distances; crystalline ice may not exist; the constituent phases could be extremely complex. At present we can constrain the sources only mildly; once on the Moon, the transport mechanisms inherently mix and therefore obscure the origins. However, the importance of expanding our understanding of ore-forming processes on the Moon behooves us to make the attempt. Thus begins a time of new inquiry for Economic Geology.

  3. Constrained lability in floral evolution: counting convergent origins of hummingbird pollination in Penstemon and Keckiella.

    PubMed

    Wilson, Paul; Wolfe, Andrea D; Armbruster, W Scott; Thomson, James D

    2007-01-01

    In the clade of Penstemon and segregate genera, pollination syndromes are well defined among the 284 species. Most display combinations of floral characters associated with pollination by Hymenoptera, the ancestral mode of pollination for this clade. Forty-one species present characters associated with hummingbird pollination, although some of these ornithophiles are also visited by insects. The ornithophiles are scattered throughout the traditional taxonomy and across phylogenies estimated from nuclear (internal transcribed spacer (ITS)) and chloroplast DNA (trnCD/TL) sequence data. Here, the number of separate origins of ornithophily is estimated, using bootstrap phylogenies and constrained parsimony searches. Analyses suggest 21 separate origins, with overwhelming support for 10 of these. Because species sampling was incomplete, this is probably an underestimate. Penstemons therefore show great evolutionary lability with respect to acquiring hummingbird pollination; this syndrome acts as an attractor to which species with large sympetalous nectar-rich flowers have frequently been drawn. By contrast, penstemons have not undergone evolutionary shifts backwards or to other pollination syndromes. Thus, they are an example of both striking evolutionary lability and constrained evolution.

  4. Novel diffusive gradients in thin films technique to assess labile sulfate in soil.

    PubMed

    Hanousek, Ondrej; Mason, Sean; Santner, Jakob; Chowdhury, Md Mobaroqul Ahsan; Berger, Torsten W; Prohaska, Thomas

    2016-09-01

    A novel diffusive gradients in thin films (DGT) technique for sampling labile soil sulfate was developed, based on a strong basic anion exchange resin (Amberlite IRA-400) for sulfate immobilization on the binding gel. For reducing the sulfate background on the resin gels, photopolymerization was applied instead of ammonium persulfate-induced polymerization. Agarose cross-linked polyacrylamide (APA) hydrogels were used as diffusive layer. The sulfate diffusion coefficient in APA gel was determined as 9.83 × 10(-6) ± 0.35 × 10(-6) cm(2) s(-1) at 25 °C. The accumulated sulfate was eluted in 1 mol L(-1) HNO3 with a recovery of 90.9 ± 1.6 %. The developed method was tested against two standard extraction methods for soil sulfate measurement. The obtained low correlation coefficients indicate that DGT and conventional soil test methods assess differential soil sulfate pools, rendering DGT a potentially important tool for measuring labile soil sulfate.

  5. [Effects of stand structure regulation on soil labile organic carbon in Pinus elliottii plantation].

    PubMed

    Tan, Gui-Xia; Liu, Yuan-Qiu; Li, Lian-Lian; Liu, Wu; Zan, Yu-Ting; Huo, Bing-Nan; He, Mu-Jiao

    2014-05-01

    Taking 21-year-old Pinus elliottii pure plantation as the control, effects of enrichment planting with broadleaf trees (Liquidambar fornosana) after thinning the conifer trees (P. elliottii) on soil labile organic carbon of different plantations, including 3-year-old, 6-year-old, 9-year-old P. elliottii and 21-year-old P. elliottii-L. fornosana mixed plantations, were investigated. The results showed that the contents of soil dissolved organic carbon (DOC), readily oxidizable organic carbon (ROC), and microbial biomass carbon (MBC) significantly increased in the 6-year-old and 9-year-old plantations compared with those in the 21-year-old P. elliottii pure plantation. Soil labile organic carbon contents in the 21-year-old P. elliottii-L. fornosana mixed plantation increased significantly than those in 3-year-old, 6-year-old, 9-year-old stands, and the DOC, ROC and MBC contents increased by 113.1%, 53.3% and 54.6%, respectively, compared with those in the 21-year-old P. elliottii pure plantation. The results suggested that replanting with broadleaf trees are an effective measure to improve the soil ecological function in pure P. elliottii plantation.

  6. [Effects of land use change on soil labile organic carbon in Central Jiangxi of China].

    PubMed

    Du, Man-Yi; Fan, Shao-Hui; Liu, Guang-Lu; Qi, Liang-Hua; Guo, Bao-Hu; Tang, Xiao-Lu; Xiao, Fu-Ming

    2013-10-01

    Selecting the 15-year abandoned land (AL) and three forest lands [Phyllostachys edulis plantation (PE), Schima superba secondary forest (SS), and Cunninghamia Lanceolata plantation (CL)] in Anfu County of Jiangxi Province as test objects, this paper studied the effects of land use change on the soil organic carbon (SOC) pool and soil labile organic carbon (SLOC) contents. The soil organic carbon (SOC), microbial biomass carbon (MBC), hot- water extractable carbon (HWC), and readily oxidizable carbon (ROC) contents in the test lands were all in the order of PE>CL>SS>AL. As compared with those in AL, the SOC content, soil carbon stock, and soil labile organic carbon (SLOC) contents in the three forest lands all decreased with increasing soil depth, and had an obvious accumulation in surface soil. The proportions of different kinds of SLOC to soil total organic carbon differed markedly, among which, ROC had the highest proportion, while MBC had the smallest one. There existed significant relationships between SOC, MBC, HWC, and ROC. The MBC, HWC, and ROC contained higher content of active carbon, and were more sensitive to the land use change, being able to be used as the indicators for evaluating the soil quality and fertility in central Jiangxi Province.

  7. Structure and function of cholera toxin and the related Escherichia coli heat-labile enterotoxin.

    PubMed Central

    Spangler, B D

    1992-01-01

    Cholera and the related Escherichia coli-associated diarrheal disease are important problems confronting Third World nations and any area where water supplies can become contaminated. The disease is extremely debilitating and may be fatal in the absence of treatment. Symptoms are caused by the action of cholera toxin, secreted by the bacterium Vibrio cholerae, or by a closely related heat-labile enterotoxin, produced by Escherichia coli, that causes a milder, more common traveler's diarrhea. Both toxins bind receptors in intestinal epithelial cells and insert an enzymatic subunit that modifies a G protein associated with the adenylate cyclase complex. The consequent stimulated production of cyclic AMP, or other factors such as increased synthesis of prostaglandins by intoxicated cells, initiates a metabolic cascade that results in the excessive secretion of fluid and electrolytes characteristic of the disease. The toxins have a very high degree of structural and functional homology and may be evolutionarily related. Several effective new vaccine formulations have been developed and tested, and a growing family of endogenous cofactors is being discovered in eukaryotic cells. The recent elucidation of the three-dimensional structure of the heat-labile enterotoxin has provided an opportunity to examine and compare the correlations between structure and function of the two toxins. This information may improve our understanding of the disease process itself, as well as illuminate the role of the toxin in studies of signal transduction and G-protein function. Images PMID:1480112

  8. Protective effects of dimethyl sulfoxide on labile protein interactions during electrospray ionization.

    PubMed

    Landreh, Michael; Alvelius, Gunvor; Johansson, Jan; Jörnvall, Hans

    2014-05-06

    Electrospray ionization mass spectrometry is a valuable tool to probe noncovalent interactions. However, the integrity of the interactions in the gas-phase is heavily influenced by the ionization process. Investigating oligomerization and ligand binding of transthyretin (TTR) and the chaperone domain from prosurfactant protein C, we found that dimethyl sulfoxide (DMSO) can improve the stability of the noncovalent interactions during the electrospray process, both regarding ligand binding and the protein quaternary structure. Low amounts of DMSO can reduce in-source dissociation of native protein oligomers and their interactions with hydrophobic ligands, even under destabilizing conditions. We interpret the effects of DMSO as being derived from its enrichment in the electrospray droplets during evaporation. Protection of labile interactions can arise from the decrease in ion charges to reduce the contributions from Coulomb repulsions, as well as from the cooling effect of adduct dissociation. The protective effects of DMSO on labile protein interactions are an important property given its widespread use in protein analysis by electrospray ionization mass spectrometry (ESI-MS).

  9. Towards powerful experimental and statistical approaches to study intraindividual variability in labile traits

    PubMed Central

    Fanson, Benjamin G.; Beckmann, Christa; Biro, Peter A.

    2016-01-01

    There is a long-standing interest in behavioural ecology, exploring the causes and correlates of consistent individual differences in mean behavioural traits (‘personality’) and the response to the environment (‘plasticity’). Recently, it has been observed that individuals also consistently differ in their residual intraindividual variability (rIIV). This variation will probably have broad biological and methodological implications to the study of trait variation in labile traits, such as behaviour and physiology, though we currently need studies to quantify variation in rIIV, using more standardized and powerful methodology. Focusing on activity rates in guppies (Poecilia reticulata), we provide a model example, from sampling design to data analysis, in how to quantify rIIV in labile traits. Building on the doubly hierarchical generalized linear model recently used to quantify individual differences in rIIV, we extend the model to evaluate the covariance between individual mean values and their rIIV. After accounting for time-related change in behaviour, our guppies substantially differed in rIIV, and it was the active individuals that tended to be more consistent (lower rIIV). We provide annotated data analysis code to implement these complex models, and discuss how to further generalize the model to evaluate covariances with other aspects of phenotypic variation. PMID:27853550

  10. Heat-Labile Enterotoxin IIa, a Platform To Deliver Heterologous Proteins into Neurons

    PubMed Central

    Chen, Chen; Przedpelski, Amanda; Tepp, William H.; Pellett, Sabine; Johnson, Eric A.

    2015-01-01

    ABSTRACT Cholera toxin (CT) and the related heat-labile enterotoxins (LT) of Escherichia coli have been implicated as adjuvants in human therapies, but reactivity upon intranasal delivery dampened efforts to develop other clinical applications. However, each CT family member variant has unique biological properties that may warrant development as therapeutic platforms. In the current study, a nontoxic variant of the heat-labile enterotoxin IIa (LTIIa) was engineered to deliver heterologous, functional proteins into the cytosol of neurons. As proof of principle, the LTIIa variant delivered two cargos into neurons. LTIIa delivered β-lactamase efficiently into cells containing complex gangliosides, such as GD1b, as host receptors. LTIIa delivery of β-lactamase was sensitive to brefeldin A, an inhibitor that collapses the Golgi compartment into the endoplasmic reticulum, but not sensitive to treatment with botulinum neurotoxin D (BoNT/D), an inhibitor of synaptic vesicle cycling. LTIIa delivered a single-chain, anti-BoNT/A camelid antibody that inhibited SNAP25 cleavage during post-BoNT/A exposure of neurons. Delivery of functional, heterologous protein cargos into neurons demonstrates the potential of LTII variants as platforms to deliver therapies to inactivate toxins and microbial infections and to reverse the pathology of human neurodegenerative diseases. PMID:26265718

  11. Superconductivity in an Alkali Doped Polycyclic Aromatic Hydrocarbon, Picene

    NASA Astrophysics Data System (ADS)

    Tokumoto, Madoka; Shimizu, Fumihiko; Hata, Yoshiaki; Sawai, Shinya; Han, Jing; Inoue, Katsuya

    2010-03-01

    The effect of carrier doping into polycyclic aromatic hydrocarbons, including perylene and pentacene, has been extensively studied.[1] As a result of halogen or alkali metal doping, a drastic increase in electrical conductivity was observed. However, superconductivity has not been reported except the one by Sch"on et al.[2] Recently, Kubozono reported that one of them, i.e. picene (C22H14) showed superconductivity at 20 K by doping with potassium.[3] We anticipate that it will lead to surprising findings of hidden organic molecular superconductors. In this presentation, we will report on the characterization of superconducting properties of alkali doped picene. Instead of ordinary vapor phase alkali metal doping, we employ thermal decomposition of alkali azides, i.e. AN3 where A = K, Rb. We followed the doping procedure of thermal decomposition applied to fullerene C60.[4] A systematic variation of the superconducting transition temperature and fraction are studied as a function of alkali metal composition. [1] H. Akamatu, H. Inokuchi, and Y. Matsunaga, Nature 173 (1954) 168. [2] J. H. Sch"on, Ch. Kloc & B. Batlogg, Nature 406 (2000) 702; retraction, Nature 422 (2003) 93. [3] R. Mitsuhashi, Y. Kubozono et al.: private communication. [4] M. Tokumoto, et al. , J. Phys. Chem. Solids, 54 (1993) 1667.

  12. Lithium and Sodium Resistance of Alkali Metal Vapor Resistant Glasses

    NASA Astrophysics Data System (ADS)

    Kishinevski, Anatoly; Hall, Matthew

    2014-05-01

    A common challenge in atomic physics is that of containing an alkali metal vapor at an elevated temperature and concurrently being able to excite and probe atomic transitions within. Typically glass is used as the material to construct the container, as it is easy to manipulate into any geometry and offers thermal, mechanical, and optical properties that no other material is capable. Unfortunately it has been well established that alkali metal gasses/vapors react readily with silica containing glass and results in a progressive darkening of the material. As the darkening reaction progresses, the optical transmission properties of the glass progressively degrade to an eventual point of uselessness. Alkali metals have been used extensively in frequency standards and magnetometers. The finite life of these alkali metal vapor-containing devices has been accepted despite varying attempts by different teams to solve this problem. As a viable solution, it has been identified there exist a family of glass compositions that contain a marginal amount of silica, may be lampworked using traditional glassblowing techniques, and that offer substantially better alkali vapor resistance. The evaluation of these glasses and their resistance to sodium and lithium vapor at varying pressures and temperatures are discussed.

  13. Analysis of remineralisation, lability, temperature sensitivity and structural composition of organic matter from the upper ocean

    NASA Astrophysics Data System (ADS)

    Bendtsen, Jørgen; Hilligsøe, Karen Marie; Hansen, Jørgen L. S.; Richardson, Katherine

    2015-01-01

    Organic carbon (OC) synthesised by plankton is exported out of the surface layer as particulate (POC) and dissolved (DOC) organic carbon. This 'biological pump' constitutes a major pathway in the global marine carbon cycle, each year exporting about 10 Pg C into the ocean interior, where it is subsequently remineralised via biological decomposition. Remineralised inorganic nutrients and carbon are, ultimately, again brought to the surface by advection and turbulent mixing which closes the OC-cycle in the upper ocean. Thus, remineralisation rates of OC are a critical component of the biological pump. These rates are regulated by the lability of the material and the environmental conditions in the ambient water. Temperature is particularly important in regulating the rate of microbial respiration and, thus, remineralisation rates. A significant temperature dependence of the microbial metabolic activity in the ocean interior is expected, as this is a feature observed elsewhere in the biosphere. Such temperature dependence of microbial remineralisation of POC and DOC will alter the amount of material available for transport by the biological pump to the deep ocean. Very few studies on the lability of OC and temperature sensitivity of microbial degradation processes in the mesopelagic zone (∼100-1000 m) have, to date, been carried out. Here, we present a comprehensive new experimental data set from all major ocean basins and quantify remineralisation rates of OC and their temperature sensitivity in long-term incubations of water from the upper 350 m. Microbial respiration was measured by non-invasive oxygen optodes and oxygen consumption was used as a constraint for determining the remineralisation rates and temperature sensitivity by two complementary methods. First, we analysed the oxygen consumption from a multi-component OC-model where the concentration, remineralisation rates and temperature sensitivity of two bio-available (labile) pools of organic carbon were

  14. Metal contents of phytoplankton and labile particulate material in the North Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Twining, Benjamin S.; Rauschenberg, Sara; Morton, Peter L.; Vogt, Stefan

    2015-09-01

    Phytoplankton contribute significantly to global C cycling and serve as the base of ocean food webs. Phytoplankton require trace metals for growth and also mediate the vertical distributions of many metals in the ocean. We collected bulk particulate material and individual phytoplankton cells from the upper water column (<150 m) of the North Atlantic Ocean as part of the US GEOTRACES North Atlantic Zonal Transect cruise (GEOTRACES GA03). Particulate material was first leached to extract biogenic and potentially-bioavailable elements, and the remaining refractory material was digested in strong acids. The cruise track spanned several ocean biomes and geochemical regions. Particulate concentrations of metals associated primarily with lithogenic phases (Fe, Al, Ti) were elevated in surface waters nearest North America, Africa and Europe, and elements associated primarily with biogenic material (P, Cd, Zn, Ni) were also found at higher concentrations near the coasts. However metal/P ratios of labile particulate material were also elevated in the middle of the transect for Fe, Ni, Co, Cu, and V. P-normalized cellular metal quotas measured with synchrotron X-ray fluorescence (SXRF) were generally comparable to ratios in bulk labile particles but did not show mid-basin increases. Manganese and Fe ratios and cell quotas were higher in the western part of the section, nearest North America, and both elements were more enriched in bulk particles, relative to P, than in cells, suggesting the presence of labile oxyhydroxide particulate phases. Cellular Fe quotas thus did not increase in step with aeolian dust inputs, which are highest near Africa; these data suggest that the dust inputs have low bioavailability. Copper and Ni cell quotas were notably higher nearest the continental margins. Overall mean cellular metal quotas were similar to those measured in the Pacific and Southern Oceans except for Fe, which was approximately 3-fold higher in North Atlantic cells. Cellular Fe

  15. A simple and inexpensive enteric-coated capsule for delivery of acid-labile macromolecules to the small intestine.

    PubMed

    Miller, Darren S; Parsons, Anne Michelle; Bresland, John; Herde, Paul; Pham, Duc Minh; Tan, Angel; Hsu, Hung-yao; Prestidge, Clive A; Kuchel, Tim; Begg, Rezaul; Aziz, Syed Mahfuzul; Butler, Ross N

    2015-07-01

    Understanding the ecology of the gastrointestinal tract and the impact of the contents on the host mucosa is emerging as an important area for defining both wellness and susceptibility to disease. Targeted delivery of drugs to treat specific small intestinal disorders such as small bowel bacterial overgrowth and targeting molecules to interrogate or to deliver vaccines to the remote regions of the small intestine has proven difficult. There is an unmet need for methodologies to release probes/drugs to remote regions of the gastrointestinal tract in furthering our understanding of gut health and pathogenesis. In order to address this concern, we need to know how the regional delivery of a surrogate labeled test compound is handled and in turn, if delivered locally as a liquid or powder, the dynamics of its subsequent handling and metabolism. In the studies we report on in this paper, we chose (13)C sodium acetate ((13)C-acetate), which is a stable isotope probe that once absorbed in the small intestine can be readily measured non-invasively by collection and analysis of (13)CO2 in the breath. This would provide information of gastric emptying rates and an indication of the site of release and absorptive capacity. In a series of in vitro and in vivo pig experiments, we assessed the enteric-protective properties of a commercially available polymer EUDRAGIT(®) L100-55 on gelatin capsules and also on DRcaps(®). Test results demonstrated that DRcaps(®) coated with EUDRAGIT(®) L100-55 possessed enhanced enteric-protective properties, particularly in vivo. These studies add to the body of knowledge regarding gastric emptying in pigs and also begin the process of gathering specifications for the design of a simple and cost-effective enteric-coated capsule for delivery of acid-labile macromolecules to the small intestine.

  16. A simple and inexpensive enteric-coated capsule for delivery of acid-labile macromolecules to the small intestine*

    PubMed Central

    Miller, Darren S.; Parsons, Anne Michelle; Bresland, John; Herde, Paul; Pham, Duc Minh; Tan, Angel; Hsu, Hung-yao; Prestidge, Clive A.; Kuchel, Tim; Begg, Rezaul; Aziz, Syed Mahfuzul; Butler, Ross N.

    2015-01-01

    Understanding the ecology of the gastrointestinal tract and the impact of the contents on the host mucosa is emerging as an important area for defining both wellness and susceptibility to disease. Targeted delivery of drugs to treat specific small intestinal disorders such as small bowel bacterial overgrowth and targeting molecules to interrogate or to deliver vaccines to the remote regions of the small intestine has proven difficult. There is an unmet need for methodologies to release probes/drugs to remote regions of the gastrointestinal tract in furthering our understanding of gut health and pathogenesis. In order to address this concern, we need to know how the regional delivery of a surrogate labeled test compound is handled and in turn, if delivered locally as a liquid or powder, the dynamics of its subsequent handling and metabolism. In the studies we report on in this paper, we chose 13C sodium acetate (13C-acetate), which is a stable isotope probe that once absorbed in the small intestine can be readily measured non-invasively by collection and analysis of 13CO2 in the breath. This would provide information of gastric emptying rates and an indication of the site of release and absorptive capacity. In a series of in vitro and in vivo pig experiments, we assessed the enteric-protective properties of a commercially available polymer EUDRAGIT®L100-55 on gelatin capsules and also on DRcaps®. Test results demonstrated that DRcaps®coated with EUDRAGIT®L100-55 possessed enhanced enteric-protective properties, particularly in vivo. These studies add to the body of knowledge regarding gastric emptying in pigs and also begin the process of gathering specifications for the design of a simple and cost-effective enteric-coated capsule for delivery of acid-labile macromolecules to the small intestine. PMID:26160716

  17. Comparison of Y1 mouse adrenal cell and coagglutination assays for detection of Escherichia coli heat labile enterotoxin.

    PubMed Central

    Chapman, P A; Daly, C M

    1989-01-01

    A commercial coagglutination assay (COA; Phadebact LT-ETEC) was compared with a Y1 mouse adrenal cell assay for detecting the heat labile enterotoxin of Escherichia coli. Of four different media evaluated for use with the COA, only one (modified blood agar) gave a positive result with all strains known to produce heat labile enterotoxin. With modified blood agar, the COA detected 74 (85%) of 87 such strains. Eighty six strains negative by cell culture assay were also negative by COA, and one strain positive by COA could not be confirmed by cell culture. The Phadebact LT-ETEC kit provides a simple, sensitive, and economical method for detecting E coli heat labile enterotoxin. PMID:2668342

  18. Maternal exposure to alkali, alkali earth, transition and other metals: Concentrations and predictors of exposure.

    PubMed

    Hinwood, A L; Stasinska, A; Callan, A C; Heyworth, J; Ramalingam, M; Boyce, M; McCafferty, P; Odland, J Ø

    2015-09-01

    Most studies of metals exposure focus on the heavy metals. There are many other metals (the transition, alkali and alkaline earth metals in particular) in common use in electronics, defense industries, emitted via combustion and which are naturally present in the environment, that have received limited attention in terms of human exposure. We analysed samples of whole blood (172), urine (173) and drinking water (172) for antimony, beryllium, bismuth, cesium, gallium, rubidium, silver, strontium, thallium, thorium and vanadium using ICPMS. In general most metals concentrations were low and below the analytical limit of detection with some high concentrations observed. Few factors examined in regression models were shown to influence biological metals concentrations and explained little of the variation. Further study is required to establish the source of metals exposures at the high end of the ranges of concentrations measured and the potential for any adverse health impacts in children.

  19. Alpine pasture soils accumulate a large fraction of labile carbon due to combined effects of low temperature, low pH, and poor litter quality on decomposition

    NASA Astrophysics Data System (ADS)

    Budge, Karen; Leifeld, Jens; Hiltbrunner, Erika; Fuhrer, Jürg

    2010-05-01

    Alpine soils are expected to contain large amounts of labile carbon (C) which may result in a further increase in atmospheric CO2 levels in response to global warming. However, there is little data available on these soils and limited understanding of the influence environmental factors have on soil organic matter (SOM) turnover. We extracted 30 cm deep soil cores from 5 sites along an elevation gradient of an alpine pasture in the central Swiss Alps. Soil fractions obtained by size and density fractionation revealed a high proportion of labile particulate organic carbon (POC), particularly in the uppermost soil layers. POC values in the top 20 cm across the gradient of 2285-2653 m above sea level (a.s.l.) ranged from 39.6-57.6 % in comparison to 7.2-29.6 reported in lower elevation soils of 810-1960 m a.s.l. in previous studies. While soil at all elevations was found to be relatively acidic, C mean residence times (MRTs) were considerably shorter and phytomass was slightly higher at the single site found to have a comparatively less acidic soil pH, although SOC content did not vary from those sites of similar root/litter and stone contents. At all elevations, MRTs increased between fractions of increasing stability from free POM (fPOM) → occluded POM (oPOM) → mineral-associated material (mOM); e.g. at 2653 m MRTs increased in years from 90 in fPOM → 117 in oPOM → 534 in mOM. Depending on elevation and pH, plant community data indicated considerable variation in the source of litter input. The lowest site was dominated by sedges whereas the highest site by lichens and dwarf shrubs, this variation in litter source may be reflected in the dynamics of soil C. While temperature is likely to be a major influence in the low turnover rate observed, other factors such as litter quality and soil pH as well as the combination of these factors are likely to play an important role on the response of SOM in the event of soil warming and require consideration in model

  20. Neuropsychiatric manifestations of alkali metal deficiency and excess.

    PubMed

    Yung, C Y

    1984-01-01

    The alkali metals from the Group IA of the periodic table (lithium, sodium, potassium, rubidium, cesium and francium) are reviewed. The neuropsychiatric aspects of alkali metal deficiencies and excesses (intoxications) are described. Emphasis was placed on lithium due to its clinical uses. The signs and symptoms of these conditions are characterized by features of an organic brain syndrome with delirium and encephalopathy prevailing. There are no clinically distinctive features that could be reliably used for diagnoses. Sodium and potassium are two essential alkali metals in man. Lithium is used as therapeutic agent in bipolar affective disorders. Rubidium has been investigated for its antidepressant effect in a group of psychiatric disorders. Cesium is under laboratory investigation for its role in carcinogenesis and in depressive illness. Very little is known of francium due to its great instability for experimental study.

  1. Neuropsychiatric manifestations of alkali metal deficiency and excess

    SciTech Connect

    Yung, C.Y.

    1984-01-01

    The alkali metals from the Group IA of the periodic table (lithium, sodium, potassium, rubidium, cesium and francium) are reviewed. The neuropsychiatric aspects of alkali metal deficiencies and excesses (intoxications) are described. Emphasis was placed on lithium due to its clinical uses. The signs and symptoms of these conditions are characterized by features of an organic brain syndrome with delirium and encephalopathy prevailing. There are no clinically distinctive features that could be reliably used for diagnoses. Sodium and potassium are two essential alkali metals in man. Lithium is used as therapeutic agent in bipolar affective disorders. Rubidium has been investigated for its antidepressant effect in a group of psychiatric disorders. Cesium is under laboratory investigation for its role in carcinogenesis and in depressive illness. Very little is known of francium due to its great instability for experimental study.

  2. Superconductivity at 5 K in alkali-metal-doped phenanthrene.

    PubMed

    Wang, X F; Liu, R H; Gui, Z; Xie, Y L; Yan, Y J; Ying, J J; Luo, X G; Chen, X H

    2011-10-18

    Organic superconductors have π-molecular orbitals, from which electrons can become delocalized, giving rise to metallic conductivity due to orbital overlap between adjacent molecules. Here we report the discovery of superconductivity at a transition temperature (T(c)) of ~5 K in alkali-metal-doped phenanthrene. A 1-GPa pressure leads to a 20% increase of T(c), suggesting that alkali-metal-doped phenanthrene shows unconventional superconductivity. Raman spectra indicate that alkali-metal doping injects charge into the system to realize the superconductivity. The discovery of superconductivity in A(3)phenanthrene (where A can be either K or Rb) produces a novel broad class of superconductors consisting of fused hydrocarbon benzene rings with π-electron networks. An increase of T(c) with increasing number of benzene rings from three to five suggests that organic hydrocarbons with long chains of benzene rings are potential superconductors with high T(c).

  3. Alkali-vapor emission from PFBC of Illinois coals.

    SciTech Connect

    Lee, S. H. D.; Teats, F. G.; Swift, W. M.; Banerjee, D. D.; Chemical Engineering; Center for Research on Sulfur in Coal

    1992-01-01

    Two Illinois Herrin No. 6 coals and one Illinois Springfield No. 5 coal were combusted in a laboratory-scale PFBC/alkali sorber facility with a bed of Tymochtee dolomite at temperatures ranging from 910 to 950oC and a system pressure of 9.2 atm absolute. Alkali vapor emission (Na and K) from combustion was determined by analytical activated-bauxite sorber bed technique. The test results showed that sodium is the major alkali-vapor species present in the PFBC flue gas of these coals and that there is a positive linear relationship between the level of sodium-vapor emission with both Na and Cl contents in the coals.

  4. Formation and stability of high-spin alkali clusters.

    PubMed

    Schulz, C P; Claas, P; Schumacher, D; Stienkemeier, F

    2004-01-09

    Helium nanodroplet isolation has been applied to agglomerate alkali clusters at temperatures of 380 mK. The very weak binding to the surface of the droplets allows a selection of only weakly bound, high-spin states. Here we show that larger clusters of alkali atoms in high-spin states can be formed. The lack of strong bonds from pairing electrons makes these systems nonmetallic, van der Waals-like complexes of metal atoms. We find that sodium and potassium readily form such clusters containing up to 25 atoms. In contrast, this process is suppressed for rubidium and cesium. Apparently, for these heavy alkalis, larger high-spin aggregates are not stable and depolarize spontaneously upon cluster formation.

  5. Formation and Stability of High-Spin Alkali Clusters

    NASA Astrophysics Data System (ADS)

    Schulz, C. P.; Claas, P.; Schumacher, D.; Stienkemeier, F.

    2004-01-01

    Helium nanodroplet isolation has been applied to agglomerate alkali clusters at temperatures of 380mK. The very weak binding to the surface of the droplets allows a selection of only weakly bound, high-spin states. Here we show that larger clusters of alkali atoms in high-spin states can be formed. The lack of strong bonds from pairing electrons makes these systems nonmetallic, vanderWaals like complexes of metal atoms. We find that sodium and potassium readily form such clusters containing up to 25atoms. In contrast, this process is suppressed for rubidium and cesium. Apparently, for these heavy alkalis, larger high-spin aggregates are not stable and depolarize spontaneously upon cluster formation.

  6. A case of severe airbag related ocular alkali injury.

    PubMed

    Barnes, Shawn S; Wong, William; Affeldt, John C

    2012-08-01

    While airbags have saved many lives and are clearly beneficial overall, sodium hydroxide (NaOH) powder produced by the inflation reaction can cause significant alkali ocular injury if not irrigated promptly. Here we report a case of severe airbag related ocular alkali injury as a way to bring attention to the need for prompt ocular irrigation following motor vehicle accidents (MVA) with airbag deployment. A 47-year-old man was involved in a MVA with airbag deployment in a rural setting. Attention was paid to several other life-threatening traumatic injuries, however, ocular irrigation was not performed until some 6-7 hours after the MVA. Over the course of 6 months, airbag related alkali injury caused severe limbal ischemia, conjunctivalization of the cornea, corneal epithelial defects, cicatricial scarring, haze, and corneal/limbal vascularization despite amniotic membrane graft. Awareness of the importance of ocular irrigation following airbag deployment must be raised both in the ophthalmology and emergency medicine communities.

  7. Theoretical study of the alkali and alkaline-earth monosulfides

    NASA Technical Reports Server (NTRS)

    Partridge, Harry; Langhoff, Stephen R.; Bauschlicher, Charles W., Jr.

    1988-01-01

    Ab initio calculations have been used to obtain accurate spectroscopic constants for the X2Pi and A2Sigma(+) states of the alkali sulfides and the X1Sigma(+), a3Pi, and A1Pi states of the alkaline-earth sulfides. In contrast to the alkali oxides, the alkali sulfides are found to have X2Pi ground states, due to the larger electrostatic interaction. Dissociation energies of 3.27 eV for BeS, 2.32 eV for MgS, 3.29 eV for CaS, and 3.41 eV for SrS have been obtained for the X1Sigma(+) states of the alkaline-earth sulfides, in good agreement with experimental results. Core correlation is shown to increase the Te values for the a3Pi and A1Pi states of MgS, CaS, and SrS.

  8. Spectroscopic and theoretical study on alkali metal phenylacetates

    NASA Astrophysics Data System (ADS)

    Regulska, E.; Świsłocka, R.; Samsonowicz, M.; Lewandowski, W.

    2013-07-01

    The influence of lithium, sodium, potassium, rubidium and cesium cations on the electronic system of phenylacetic acid was studied. The FT-IR, FT-Raman and 1H and 13C NMR spectra were recorded for studied compounds. Characteristic shifts in IR and NMR spectra along alkali metal phenylacetates were observed. Good correlations between the wavenumbers of the vibrational bands in the IR spectra of phenylacetates and some alkali metal parameters such as ionic potential, electronegativity, inverse of atomic mass, atomic radius and ionization energy were found. The density functional hybrid method B3LYP with 6-311++G** basis set was used to calculate optimized geometrical structures of studied compounds. Aromaticity indices, atomic charges, dipole moments and energies were calculated as well as the wavenumbers and intensities of IR spectra and chemical shifts in NMR spectra. The theoretical parameters were compared to experimental characteristic of alkali metal phenylacetates.

  9. Labile trace elements in basaltic achondrites: Can they distinguish between meteorites from the Moon, Mars, and V-type asteroids?

    NASA Astrophysics Data System (ADS)

    Wolf, Stephen F.; Wang, Ming-Sheng; Lipschutz, Michael E.

    2009-06-01

    We report data for 14 mainly labile trace elements (Ag, Au, Bi, Cd, Cs, Ga, In, Rb, Sb, Se, Te, Tl, U, and Zn) in eight whole-rock lunar meteorites (Asuka [A-] 881757, Dar al Gani [DaG] 262, Elephant Moraine [EET] 87521, Queen Alexandra Range [QUE] 93069, QUE 94269, QUE 94281, Yamato [Y-] 793169, and Y-981031), and Martian meteorite (DaG 476) and incorporate these into a comparative study of basaltic meteorites from the Moon, Mars, and V-type asteroids. Multivariate cluster analysis of data for these elements in 14 lunar, 13 Martian, and 34 howardite, eucrite, and diogenite (HED) meteorites demonstrate that materials from these three parents are distinguishable using these markers of late, low-temperature episodes. This distinguishability is essentially as complete as that based on markers of high-temperature igneous processes. Concentrations of these elements in 14 lunar meteorites are essentially lognormally distributed and generally more homogeneous than in Martian and HED meteorites. Mean siderophile and labile element concentrations in the 14 lunar meteorites indicate the presence of a CI-equivalent micrometeorite admixture of 2.6% When only feldspathic samples are considered, our data show a slightly higher value of 3.4% consistent with an increasing micrometeorite content in regolith samples of higher maturity. Concentrations of labile elements in the 8 feldspathic samples hint at the presence of a fractionated highly labile element component, possibly volcanic in origin, at a level comparable to the micrometeorite component. Apparently, the process(es) that contributed to establishing lunar meteorite siderophile and labile trace element contents occurred in a system open to highly labile element transport.

  10. Spill-Resistant Alkali-Metal-Vapor Dispenser

    NASA Technical Reports Server (NTRS)

    Klipstein, William

    2005-01-01

    A spill-resistant vessel has been developed for dispensing an alkali-metal vapor. Vapors of alkali metals (most commonly, cesium or rubidium, both of which melt at temperatures slightly above room temperature) are needed for atomic frequency standards, experiments in spectroscopy, and experiments in laser cooling. Although the present spill-resistant alkali-metal dispenser was originally intended for use in the low-gravity environment of outer space, it can also be used in normal Earth gravitation: indeed, its utility as a vapor source was confirmed by use of cesium in a ground apparatus. The vessel is made of copper. It consists of an assembly of cylinders and flanges, shown in the figure. The uppermost cylinder is a fill tube. Initially, the vessel is evacuated, the alkali metal charge is distilled into the bottom of the vessel, and then the fill tube is pinched closed to form a vacuum seal. The innermost cylinder serves as the outlet for the vapor, yet prevents spilling by protruding above the surface of the alkali metal, no matter which way or how far the vessel is tilted. In the event (unlikely in normal Earth gravitation) that any drops of molten alkali metal have been shaken loose by vibration and are floating freely, a mesh cap on top of the inner cylinder prevents the drops from drifting out with the vapor. Liquid containment of the equivalent of 1.2 grams of cesium was confirmed for all orientations with rubbing alcohol in one of the prototypes later used with cesium.

  11. Thermal effects in Cs DPAL and alkali cell window damage

    NASA Astrophysics Data System (ADS)

    Zhdanov, B. V.; Rotondaro, M. D.; Shaffer, M. K.; Knize, R. J.

    2016-10-01

    Experiments on power scaling of Diode Pumped Alkali Lasers (DPALs) revealed some limiting parasitic effects such as alkali cell windows and gain medium contamination and damage, output power degradation in time and others causing lasing efficiency decrease or even stop lasing1 . These problems can be connected with thermal effects, ionization, chemical interactions between the gain medium components and alkali cells materials. Study of all these and, possibly, other limiting effects and ways to mitigate them is very important for high power DPAL development. In this talk we present results of our experiments on temperature measurements in the gain medium of operating Cs DPAL at different pump power levels in the range from lasing threshold to the levels causing damage of the alkali cell windows. For precise contactless in situ temperature measurements, we used an interferometric technique, developed in our lab2 . In these experiments we demonstrated that damage of the lasing alkali cell starts in the bulk with thermal breakdown of the hydrocarbon buffer gas. The degradation processes start at definite critical temperatures of the gain medium, different for each mixture of buffer gas. At this critical temperature, the hydrocarbon and the excited alkali metal begin to react producing the characteristic black soot and, possibly, some other chemical compounds, which both harm the laser performance and significantly increase the harmful heat deposition within the laser medium. This soot, being highly absorptive, is catastrophically heated to very high temperatures that visually observed as bulk burning. This process quickly spreads to the cell windows and causes their damage. As a result, the whole cell is also contaminated with products of chemical reactions.

  12. Alkali Cation Chelation in Cold β-O-4 Tetralignol Complexes

    NASA Astrophysics Data System (ADS)

    DeBlase, Andrew F.; Dziekonski, Eric T.; Hopkins, John R.; Burke, Nicole L.; Kenttamaa, Hilkka I.; McLuckey, Scott A.; Zwier, Timothy S.

    2016-06-01

    Lignins are the second most abundant naturally occurring polymer class, contributing to about 30% of the organic carbon in the biosphere. Their primary function is to provide the structural integrity of plant cell walls and have recently come under consideration as a potential source of biofuels because they have an energy content similar to coal. Herein, we employ cold ion spectroscopy (UV action and IR-UV double resonance) to unravel the spectroscopic signatures of G-type alkali metal cationized (X = Li+, Na+, K+) lignin tetramers connected by β-O-4 linkages. The conformation-specific spectroscopy reveals a variety of conformers, each containing distinct infrared spectra in the OH stretching region building on recent studies on the neutral and alkali metal cationized β-O-4 dimers. Based on comparisons of our infrared spectra to density functional theory [M05-2X/6-31+G*] harmonic level calculations for structures derived from a Monte Carlo conformational search, the alkali metal ion is discovered to engage in M+-OH-O interactions as important motifs that determine the secondary structures of these complexes. This interaction disappears in the major conformer of the K+ adduct, suggesting a reemergence of a neutral dimer segment as the metal binding energy decreases. Chelation of the metal cation by oxygen lone pair(s) of nearby oxygens in the β-O-4 linkage is observed to be the predominant driving force for 3D structure around the charge site, relegating OH-O H-bonds as secondary stabilizing elements.

  13. [Amelioration of secondary bare alkali-saline patches in Songnen Plain through inserting cornstalk].

    PubMed

    He, Nianpeng; Wu, Ling; Jiang, Shicheng; Zhou, Daowei

    2004-06-01

    Based on the field experiment on Songnen grassland, a new method was established to ameliorate the secondary bare alkali-saline patches (SAP) through inserting cornstalk. The experiment was rested on the assumption that through inserting cornstalk in the secondary bare alkali-saline patches (SAP) to retain seeds moving over its surface, the necessary seed source could be gained; and these seeds should be able to germinate and survive successfully on the cornstalk itself or in its neighborhood, where should be more fit to grow than other sites in SAP, due to the decomposition of cornstalk and its special role, so that, the aim to restore vegetation of SAP could be achieved at a pretty low cost and rapid speed. The results showed that the seed bank in soil was increased significantly, owing to the inserted cornstalk and its operating processes. The seed number in ameliorated soil was 4020.0 +/- 1773.6 seeds x m(-2), while that in the secondary bare alkali-saline patches (SAP) was only 10.0 +/- 31.6 seeds x m(-2). Although the soil chemical and physical characters in ameliorated zone were improved to some extent, the overall situation of soil was still bad for plant growth, as the pH, soluble saline ion and organic matter were concerned. Most of Chloris virgata grew around or on the cornstalk, the plants around each cornstalk being 3.9 +/- 2.2, and the total being 48.64 +/- 38.72 g x m(-2). Therefore, this method demanded a few resources, and needed simple technology and low cost, which is potentially deserved to popularize.

  14. Feasibility of supersonic diode pumped alkali lasers: Model calculations

    SciTech Connect

    Barmashenko, B. D.; Rosenwaks, S.

    2013-04-08

    The feasibility of supersonic operation of diode pumped alkali lasers (DPALs) is studied for Cs and K atoms applying model calculations, based on a semi-analytical model previously used for studying static and subsonic flow DPALs. The operation of supersonic lasers is compared with that measured and modeled in subsonic lasers. The maximum power of supersonic Cs and K lasers is found to be higher than that of subsonic lasers with the same resonator and alkali density at the laser inlet by 25% and 70%, respectively. These results indicate that for scaling-up the power of DPALs, supersonic expansion should be considered.

  15. Alkali Metal/Salt Thermal-Energy-Storage Systems

    NASA Technical Reports Server (NTRS)

    Phillips, Wayne W.; Stearns, John W.

    1987-01-01

    Proposed thermal-energy-storage system based on mixture of alkali metal and one of its halide salts; metal and salt form slurry of two immiscible melts. Use of slurry expected to prevent incrustations of solidified salts on heat-transfer surfaces that occur where salts alone used. Since incrustations impede heat transfer, system performance improved. In system, charging heat-exchanger surface immersed in lower liquid, rich in halide-salt, phase-charge material. Discharging heat exchanger surface immersed in upper liquid, rich in alkali metal.

  16. Upgrading of petroleum oil feedstocks using alkali metals and hydrocarbons

    DOEpatents

    Gordon, John Howard

    2014-09-09

    A method of upgrading an oil feedstock by removing heteroatoms and/or one or more heavy metals from the oil feedstock composition. This method reacts the oil feedstock with an alkali metal and an upgradant hydrocarbon. The alkali metal reacts with a portion of the heteroatoms and/or one or more heavy metals to form an inorganic phase separable from the organic oil feedstock material. The upgradant hydrocarbon bonds to the oil feedstock material and increases the number of carbon atoms in the product. This increase in the number of carbon atoms of the product increases the energy value of the resulting oil feedstock.

  17. Mass spectrometry method to identify aging pathways of Sp- and Rp-tabun adducts on human butyrylcholinesterase based on the acid labile P-N bond.

    PubMed

    Jiang, Wei; Cashman, John R; Nachon, Florian; Masson, Patrick; Schopfer, Lawrence M; Lockridge, Oksana

    2013-04-01

    The phosphoramidate nerve agent tabun inhibits butyrylcholinesterase (BChE) and acetylcholinesterase by making a covalent bond on the active site serine. The adduct loses an alkyl group in a process called aging. The mechanism of aging of the tabun adduct is controversial. Some studies claim that aging proceeds through deamination, whereas crystal structure studies show aging by O-dealkylation. Our goal was to develop a method that clearly distinguishes between deamination and O-dealkylation. We began by studying the tetraisopropyl pyrophosphoramide adduct of BChE because this adduct has two P-N bonds. Mass spectra showed that the P-N bonds were stable during trypsin digestion at pH 8 but were cleaved during pepsin digestion at pH 2. The P-N bond in tabun was also acid labile, whereas the P-O bond was stable. A scheme to distinguish aging by deamination from aging by O-dealkylation was based on the acid labile P-N bond. BChE was inhibited with Sp- and Rp-tabun thiocholine nerve agent model compounds to make adducts identical to those of tabun with known stereochemistry. After aging and digestion with pepsin at pH 2, peptide FGES198AGAAS from Sp-tabun thiocholine had a mass of 902.2 m/z in negative mode, indicating that it had aged by deamination, whereas peptide FGES198AGAAS from Rp-tabun thiocholine had a mass of 874.2 m/z in negative mode, indicating that it had aged by O-dealkylation. BChE inhibited by authentic, racemic tabun yielded both 902.2 and 874.2 m/z peptides, indicating that both stereoisomers reacted with BChE and aged either by deamination or dealkylation.

  18. Mass Spectrometry Method to Identify Aging Pathways of Sp- and Rp-Tabun Adducts on Human Butyrylcholinesterase Based on the Acid Labile P-N Bond

    PubMed Central

    Lockridge, Oksana

    2013-01-01

    The phosphoramidate nerve agent tabun inhibits butyrylcholinesterase (BChE) and acetylcholinesterase by making a covalent bond on the active site serine. The adduct loses an alkyl group in a process called aging. The mechanism of aging of the tabun adduct is controversial. Some studies claim that aging proceeds through deamination, whereas crystal structure studies show aging by O-dealkylation. Our goal was to develop a method that clearly distinguishes between deamination and O-dealkylation. We began by studying the tetraisopropyl pyrophosphoramide adduct of BChE because this adduct has two P-N bonds. Mass spectra showed that the P-N bonds were stable during trypsin digestion at pH 8 but were cleaved during pepsin digestion at pH 2. The P-N bond in tabun was also acid labile, whereas the P-O bond was stable. A scheme to distinguish aging by deamination from aging by O-dealkylation was based on the acid labile P-N bond. BChE was inhibited with Sp- and Rp-tabun thiocholine nerve agent model compounds to make adducts identical to those of tabun with known stereochemistry. After aging and digestion with pepsin at pH 2, peptide FGES198AGAAS from Sp-tabun thiocholine had a mass of 902.2 m/z in negative mode, indicating that it had aged by deamination, whereas peptide FGES198AGAAS from Rp-tabun thiocholine had a mass of 874.2 m/z in negative mode, indicating that it had aged by O-dealkylation. BChE inhibited by authentic, racemic tabun yielded both 902.2 and 874.2 m/z peptides, indicating that both stereoisomers reacted with BChE and aged either by deamination or dealkylation. PMID:23345579

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

    SciTech Connect

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

    2015-02-10

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

  20. Significance of Isotopically Labile Organic Hydrogen in Thermal Maturation of Organic Matter

    SciTech Connect

    Arndt Schimmelmann; Maria Mastalerz

    2010-03-30

    Isotopically labile organic hydrogen in fossil fuels occupies chemical positions that participate in isotopic exchange and in chemical reactions during thermal maturation from kerogen to bitumen, oil and gas. Carbon-bound organic hydrogen is isotopically far less exchangeable than hydrogen bound to nitrogen, oxygen, or sulfur. We explore why organic hydrogen isotope ratios express a relationship with organic nitrogen isotope ratios in kerogen at low to moderate maturity. We develop and apply new techniques to utilize organic D/H ratios in organic matter fractions and on a molecular level as tools for exploration for fossil fuels and for paleoenvironmental research. The scope of our samples includes naturally and artificially matured substrates, such as coal, shale, oil and gas.

  1. Spinal cord injury: reversing the incorrect cortical maps by inductive lability procedure.

    PubMed

    Krishnan, R V

    2004-06-01

    Within the brain-stem and on the cerebral cortex there are locomotor control centers arranged in a ladder-form control system. These centers are somatotopic, self-organizing neural network maps capable of simultaneously learning and task execution. In spinal cord injury (SCI) these self-organized maps get erroneously re-organized and maladaptively stabilized. The extent and quality of sensory-motor recovery, if any appears, is affected by and compromised due to incorrect mapping processes. The treatment method based on inductive lability procedure (Krishnan, 2003a, 2003b, 2003c) uses botulinum toxin for the purpose. It recreates competition among synapses in a locomotor training-based corrective re-self-organization of the maps in various steps of the ladder.

  2. Developmental change and intraindividual variability: relating cognitive aging to cognitive plasticity, cardiovascular lability, and emotional diversity.

    PubMed

    Ram, Nilam; Gerstorf, Denis; Lindenberger, Ulman; Smith, Jacqui

    2011-06-01

    Repeated assessments obtained over years can be used to measure individuals' developmental change, whereas repeated assessments obtained over a few weeks can be used to measure individuals' dynamic characteristics. Using data from a burst of measurement embedded in the Berlin Aging Study (BASE; Baltes & Mayer, 1999), we illustrate and examine how long-term changes in cognitive ability are related to short-term changes in cognitive performance, cardiovascular function, and emotional experience. Our findings suggest that "better" cognitive aging over approximately 13 years was associated with greater cognitive plasticity, less cardiovascular lability, and less emotional diversity over approximately 2 weeks at age 90 years. The study highlights the potential benefits of multi-time scale longitudinal designs for the study of individual function and development.

  3. Bioavailability of labile and desorption-resistant phenanthrene sorbed to montmorillonite clay containing humic fractions

    SciTech Connect

    Lahlou, M.; Ortega-Calvo, J.J.

    1999-12-01

    The biodegradation of {sup 14}C-labeled phenanthrene in the presence of particles of montmorillonite and fulvic and humic acid-montmorillonite complexes was studied in a batch system. A mathematical model that takes into account the contribution to mineralization by the slowly desorbing compound was used to calculate the initial mineralization rates. Sorption of phenanthrene to the particles was determined in sorption isotherms, and desorption was measured during successive water extractions. Mineralization rates in equilibrated suspensions were higher than predicted from aqueous equilibrium concentrations, and in some cases, montmorillonite and fulvic acid-montmorillonite complexes stimulated the phenanthrene transformation rates. In contrast with the high bioavailability exhibited by phenanthrene sorbed as a labile form, biodegradation of the desorption-resistant phenanthrene occurred slowly and followed zero-order kinetics, which indicated a limitation caused by slow desorption. The results suggest that the mechanism of sorption may cause a differential bioavailability of the sorbed compound.

  4. The lateralized processing of affect in emotionally labile extraverts and introverts: central and autonomic effects.

    PubMed

    Smith, B D; Kline, R; Lindgren, K; Ferro, M; Smith, D A; Nespor, A

    1995-02-01

    The purpose of the present study was to better understand both the lateralized hemispheric processing of emotion and the differential neural processing of arousal in extraverts and introverts. We preselected right-handed male and female extraverts and introverts who were high in emotional lability. Each subject was exposed to two positive and two negative emotional stimuli under each of three counterbalanced conditions, including affective, cognitive, and neutral, while EEG and electrodermal activity (EDA) were recorded. Results showed that introverts are more aroused and that extraversion interacts with gender to produce differentiated patterns of lateralized neural activity. In addition, affective conditions produced higher levels of arousal than did cognitive or neutral conditions, particularly in the left hemisphere and under negative as opposed to positive stimuli. Finally, the hemispherically differentiated processing of positive and negative stimuli was affected by the contextual conditions under which they were experienced.

  5. Milk alkali syndrome—an unusual syndrome causing an unusual complication

    PubMed Central

    George, S; Clark, J

    2000-01-01

    Milk alkali syndrome is rare and although pancreatitis secondary to hypercalcaemia is well recognised, there has only been one other reported case of pancreatitis secondary to the milk alkali syndrome. Such a case, caused by self medication of over the counter medication, is reported.


Keywords: milk alkali syndrome; pancreatitis; over the counter medication PMID:10878206

  6. 40 CFR 721.2565 - Alkylated sulfonated diphenyl oxide, alkali and amine salts.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ..., alkali and amine salts. 721.2565 Section 721.2565 Protection of Environment ENVIRONMENTAL PROTECTION... New Uses for Specific Chemical Substances § 721.2565 Alkylated sulfonated diphenyl oxide, alkali and... substances identified as alkylated sulfonated diphenyl oxide, alkali salt (PMN P-93-352) and...

  7. 40 CFR 721.2565 - Alkylated sulfonated diphenyl oxide, alkali and amine salts.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ..., alkali and amine salts. 721.2565 Section 721.2565 Protection of Environment ENVIRONMENTAL PROTECTION... New Uses for Specific Chemical Substances § 721.2565 Alkylated sulfonated diphenyl oxide, alkali and... substances identified as alkylated sulfonated diphenyl oxide, alkali salt (PMN P-93-352) and...

  8. 40 CFR 721.2565 - Alkylated sulfonated diphenyl oxide, alkali and amine salts.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ..., alkali and amine salts. 721.2565 Section 721.2565 Protection of Environment ENVIRONMENTAL PROTECTION... New Uses for Specific Chemical Substances § 721.2565 Alkylated sulfonated diphenyl oxide, alkali and... substances identified as alkylated sulfonated diphenyl oxide, alkali salt (PMN P-93-352) and...

  9. Non-Adiabatic Atomic Transitions: Computational Cross Section Calculations of Alkali Metal-Noble Gas Collisions

    DTIC Science & Technology

    2011-09-01

    collisions were computationally simulated. The alkali metals were potassium, rubidium, and cesium and the noble gas partners were helium, neon, and argon...195 20. Spin-Orbit split energies of Potassium, Rubidium, and Cesium ...composed of an alkali metal typically Rubidium[26, 37] or Cesium [5, 18]. The unique character of the alkali atoms, having a single valence electron in

  10. 40 CFR 721.5985 - Fatty alkyl phosphate, alkali metal salt (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Fatty alkyl phosphate, alkali metal... Specific Chemical Substances § 721.5985 Fatty alkyl phosphate, alkali metal salt (generic). (a) Chemical... as a fatty alkyl phosphate, alkali metal salt (PMN P-99-0385) is subject to reporting under...

  11. 40 CFR 721.5452 - Alkali metal salt of halogenated organoborate (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Alkali metal salt of halogenated... Specific Chemical Substances § 721.5452 Alkali metal salt of halogenated organoborate (generic). (a... generically as alkali metal salt of halogenated organoborate (PMN P-00-0638) is subject to reporting...

  12. 40 CFR 721.5985 - Fatty alkyl phosphate, alkali metal salt (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Fatty alkyl phosphate, alkali metal... Specific Chemical Substances § 721.5985 Fatty alkyl phosphate, alkali metal salt (generic). (a) Chemical... as a fatty alkyl phosphate, alkali metal salt (PMN P-99-0385) is subject to reporting under...

  13. 40 CFR 721.5452 - Alkali metal salt of halogenated organoborate (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Alkali metal salt of halogenated... Specific Chemical Substances § 721.5452 Alkali metal salt of halogenated organoborate (generic). (a... generically as alkali metal salt of halogenated organoborate (PMN P-00-0638) is subject to reporting...

  14. 40 CFR 721.5985 - Fatty alkyl phosphate, alkali metal salt (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Fatty alkyl phosphate, alkali metal... Specific Chemical Substances § 721.5985 Fatty alkyl phosphate, alkali metal salt (generic). (a) Chemical... as a fatty alkyl phosphate, alkali metal salt (PMN P-99-0385) is subject to reporting under...

  15. 40 CFR 721.5452 - Alkali metal salt of halogenated organoborate (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Alkali metal salt of halogenated... Specific Chemical Substances § 721.5452 Alkali metal salt of halogenated organoborate (generic). (a... generically as alkali metal salt of halogenated organoborate (PMN P-00-0638) is subject to reporting...

  16. 40 CFR 721.5985 - Fatty alkyl phosphate, alkali metal salt (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Fatty alkyl phosphate, alkali metal... Specific Chemical Substances § 721.5985 Fatty alkyl phosphate, alkali metal salt (generic). (a) Chemical... as a fatty alkyl phosphate, alkali metal salt (PMN P-99-0385) is subject to reporting under...

  17. 40 CFR 721.5985 - Fatty alkyl phosphate, alkali metal salt (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Fatty alkyl phosphate, alkali metal... Specific Chemical Substances § 721.5985 Fatty alkyl phosphate, alkali metal salt (generic). (a) Chemical... as a fatty alkyl phosphate, alkali metal salt (PMN P-99-0385) is subject to reporting under...

  18. 40 CFR 721.5452 - Alkali metal salt of halogenated organoborate (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Alkali metal salt of halogenated... Specific Chemical Substances § 721.5452 Alkali metal salt of halogenated organoborate (generic). (a... generically as alkali metal salt of halogenated organoborate (PMN P-00-0638) is subject to reporting...

  19. 40 CFR 721.5452 - Alkali metal salt of halogenated organoborate (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Alkali metal salt of halogenated... Specific Chemical Substances § 721.5452 Alkali metal salt of halogenated organoborate (generic). (a... generically as alkali metal salt of halogenated organoborate (PMN P-00-0638) is subject to reporting...

  20. Formation of alkali-metal nanoparticles in alkali-silicate glasses under electron irradiation and thermal processing

    NASA Astrophysics Data System (ADS)

    Bochkareva, E. S.; Sidorov, A. I.; Ignat'ev, A. I.; Nikonorov, N. V.; Podsvirov, O. A.

    2017-02-01

    Experiments and numerical simulation show that the irradiation of alkali-containing glasses using electrons at an energy of 35 keV and the subsequent thermal processing at a temperature above the vitrification point lead to the formation of spherical metal (lithium, sodium, and potassium) nanoparticles with oxide sheaths that exhibit plasmon resonances in the visible spectral range. Glasses containing two alkali metals exhibit mutual effect of metals on the formation of nanoparticles with two compositions due to the difference of ion radii and mobilities of metal ions.

  1. Phenotypic lability and the evolution of predator-induced plasticity in tadpoles.

    PubMed

    Van Buskirk, J

    2002-02-01

    The hypothesis that predator-induced defenses in anuran larvae are maintained by divergent selection across multiple predation environments has not been fully supported by empirical results. One reason may be that traits that respond slowly to environmental variation experience a fitness cost not incorporated in the standard adaptive model, due to a time lag between detecting the state of the environment and expressing the phenotypic response. I measured the rate at which behavior and morphology of Rana temporaria tadpoles change when confronted with a switch in the predation environment at two points in development. Hatchling tadpoles that had been exposed during the egg stage to Aeshna dragonfly larvae were not phenotypically different from those exposed as eggs to predator-free conditions, and both responded similarly to post-hatching predator treatments. When 25-day-old tadpoles from treatments with and without dragonflies were subjected to a switch in the environment, their activity budgets reversed completely within 24-36 h, and their body and tail shape began changing significantly within 4 days. The behavioral response was conservative: Tadpoles switched from high-risk to predator-free treatments were slower to adjust their activity. The study confirmed that behavioral traits are relatively labile and exhibit strong plasticity, but it did not reveal such a pattern at the level of individual traits: Morphological traits that developed slowly did not show the least plasticity. Thus, I found that differences in lability of traits were useful for predicting the magnitude of plasticity only for fundamentally different kinds of characters.

  2. Molecular insights into the microbial formation of marine dissolved organic matter: recalcitrant or labile?

    NASA Astrophysics Data System (ADS)

    Koch, B. P.; Kattner, G.; Witt, M.; Passow, U.

    2014-02-01

    The degradation of marine dissolved organic matter (DOM) is an important control variable in the global carbon cycle and dependent on the DOM composition. For our understanding of the kinetics of organic matter cycling in the ocean, it is therefore crucial to achieve a mechanistic and molecular understanding of its transformation processes. A long-term microbial experiment was performed to follow the production of non-labile DOM by marine bacteria. Two different glucose concentrations and dissolved algal exudates were used as substrates. We monitored the bacterial abundance, concentrations of dissolved and particulate organic carbon (DOC, POC), nutrients, amino acids, and transparent exopolymer particles (TEP) for two years. Ultrahigh resolution Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR-MS) allowed the molecular characterization of extracted DOM after 70 days and after ∼2 years of incubation. Although glucose was quickly degraded, a DOC background was generated in glucose incubations. Only 20% of the organic carbon from algal exudate was degraded within the 2 years of incubation. TEP, which are released by micro-organisms, were produced during glucose degradation but decreased within less than three weeks back to half of the maximum concentration and were below detection in all treatments after 2 years. The molecular analysis demonstrated that DOM generated during glucose degradation differed appreciably from DOM produced during the degradation of the algal exudates. Our results led to several conclusions: (i) Higher substrate levels result in a higher level of non-labile DOC which is an important prerequisite for carbon sequestration in the ocean; (ii) TEP are generated by bacteria but are also degraded rapidly, thus limiting their potential contribution to carbon sequestration; (iii) The molecular signatures of DOM derived from algal exudates or glucose after 70 days of incubation differed strongly from refractory DOM. After 2 years

  3. Oxidative stress and labile plasmatic iron in anemic patients following blood therapy

    PubMed Central

    Fernandes, Marília Sabo; Rissi, Tatiana Tamborena; Zuravski, Luisa; Mezzomo, Juliana; Vargas, Carmen Regla; Folmer, Vanderlei; Soares, Félix Alexandre Antunes; Manfredini, Vanusa; Ahmed, Mushtaq; Puntel, Robson Luiz

    2014-01-01

    AIM: To determine the plasmatic iron content and evaluate the oxidative stress (OS) markers in subjects receiving blood therapy. METHODS: Thirty-nine individuals with unspecified anemia receiving blood transfusions and 15 healthy subjects were included in the study. Anemic subjects were divided into three subgrouP: (1) those that received up to five blood transfusions (n = 14); (2) those that received from five to ten transfusions (n = 11); and (3) those that received more than ten transfusions (n = 14). Blood samples were collected by venous arm puncture and stored in tubes containing heparin. The plasma and cells were separated by centrifugation and subsequently used for analyses. Statistical analyses were performed using Kruskal-Wallis analysis of variance followed by Dunn’s multiple comparison tests when appropriate. RESULTS: The eletrophoretic hemoglobin profiles of the subjects included in this study indicated that no patients presented with hemoglobinopathy. Labile plasmatic iron, ferritin, protein carbonyl, thiobarbituric acid-reactive substances (TBARS) and dichlorofluorescein diacetate oxidation were significantly higher (P < 0.05), whereas total thiol levels were significantly lower (P < 0.05) in transfused subjects compared to controls. Additionally, the activity of catalase, superoxide dismutase and glutathione peroxidase were significantly lower in the transfused subjects (P < 0.05). Antioxidant enzyme activities and total thiol levels were positively correlated (P < 0.05), and negatively correlated with the levels of protein carbonyl and TBARS (P < 0.05). In contrast, protein carbonyl and TBARS were positively correlated (P < 0.05). Altogether, these data confirm the involvement of OS in patients following therapy with repeated blood transfusions. CONCLUSION: Our data reveal that changes in OS markers are correlated with levels of labile plasmatic iron and ferritin and the number of transfusions. PMID:25254188

  4. The priming effect: Investigating the role of labile C quantity on subsoil C losses

    NASA Astrophysics Data System (ADS)

    Diochon, Amanda; Kellman, Lisa; Beltrami, Hugo

    2010-05-01

    In a study examining changes in soil organic carbon storage after clearcut harvesting, we previously reported a 50% decline in soil C stocks approximately 30 years after harvesting, with the greatest losses reported below 20 cm in the mineral soil. Physical and biological separation of organic matter indicated that the decline was greatest in the fractions of organic matter that are conceptually thought to be stable. Stable isotope analyses were consistent with increased mineralization post-harvest and we speculated that the deeper stores of C might have been primed by a flush of labile C post harvest. A recent review (Blagodatskyaya and Kuzyakov, 2008) reported that the direction (positive, negative, neutral) of the priming effect may be dependent not only upon the energy content of the added substrate, but the quantity of C added relative to microbial biomass carbon (MBC). In this study we test this hypothesis using a lab-based incubation of soils collected from the surface (0-10 cm) and subsoil (35-50 cm) of an 80 year old red spruce forest. We added 10, 100 and 1000 % C (glucose) relative to MBC and measured the rate of decomposition (microbial respiration) every 5 h for the first week, every 24 h for the second week, weekly for a month and biweekly for two months. After flushing the headspace with CO2 free air, we measured the rate of microbial respiration and the δ13C of the respired C using a Multiflow prep system with a Gilson autosampler coupled to an Isoprime mass spectrometer. We used an isotope-mixing model to partition the sources of respired C and determine the direction of priming. Our findings suggest that the quantity of added C can affect the direction of priming and that the relative priming effect differs between depths, suggesting that soil organic carbon stores in the subsoil are more sensitive to labile C additions.

  5. In vivo lability of glucose-6-phosphate dehydrogenase in GdA- and Gdmediterranean deficiency

    PubMed Central

    Piomelli, Sergio; Corash, Laurence M.; Davenport, Deatra D.; Miraglia, Janet; Amorosi, Edward L.

    1968-01-01

    A decreased level of glucose-6-phosphate dehydrogenase might result from decreased rate of synthesis, synthesis of an enzyme of lower catalytic efficiency, increased lability, or a combined mechanism. To test the hypothesis of increased lability, the rate of decline of the enzyme in vivo was measured in three groups of individuals, controls, Gd(—),A-males, and Gd(—), Mediterranean males, by the slope of decline of activity in fractions containing erythrocytes of progressively increasing mean age. These fractions were obtained by ultracentrifugation on a discontinuous density gradient of erythrocyte suspensions free of contaminating platelets and leukocytes. The rate of in vivo decline of pyruvate kinase (another age-dependent enzyme) was also measured and found very similar in the three groups. The in vivo decline of glucose-6-phosphate dehydrogenase was found to follow an exponential rate, with a half-life of 62 days for controls and 13 days for Gd(—),A- erythrocytes. The activity in normal reticulocytes was estimated at 9.7 U and in Gd(—),A- reticulocytes at 8.8 U. These estimates were confirmed by direct measurements in reticulocytes isolated from patients with extreme reticulocytosis. In Gd(—),Mediterranean erythrocytes activity could be demonstrated only in reticulocytes, which were estimated to average 1.4 U. The rate of decline is so extreme that no activity could be detected in mature erythrocytes. These data suggest that the glucose-6-phosphate dehydrogenase deficiency of both the GdA- and the GdMediterranean variant results from different degrees of in vivo instability of the abnormal enzyme. PMID:5641629

  6. Collagenase-labile polyurethane urea synthesis and processing into hollow fiber membranes.

    PubMed

    Fu, Hui-Li; Hong, Yi; Little, Steven R; Wagner, William R

    2014-08-11

    As a means to stimulate wound healing, a hollow fiber membrane system might be placed within a wound bed to provide local and externally regulated controlled delivery of regenerative factors. After sufficient healing, it would be desirable to triggerably degrade these fibers as opposed to pulling them out. Accordingly, a series of enzymatically degradable thermoplastic elastomers was developed as potential hollow fiber base material. Polyurethane ureas (PUUs) were synthesized based on 1, 4-diisocyanatobutane, polycaprolactone (PCL) diol and polyethylene glycol (PEG) at different molar fractions as soft segments, and collagenase-sensitive peptide GGGLGPAGGK-NH2 as a chain extender (defined as PUU-CLxEGy-peptide, where x and y are the respective molar percents). In these polymers, PEG in the polymer backbone decreased tensile strengths and initial moduli of solvent-cast films in the wet state, while increasing water absorption. Collagenase degradation was observed at 75% relative PEG content in the soft segment. Control PUUs with putrescine or nonsense peptide chain extenders did not degrade acutely in collagenase. Conduits electrospun from PUU-CL25EG75-peptide and PUU-CL50EG50-peptide exhibited appropriate mechanical strength and sustained release of a model protein from the tube lumen for 7 days. Collapse of PUU-CL25EG75-peptide tubes occurred after collagenase degradation for 3 days. In conclusion, through molecular design, synthesis and characterization, a collagenase-labile PUU-CL25EG75-peptide polymer was identified that exhibited the desired traits of triggerable lability, processability, and the capacity to act as a membrane to facilitate controlled protein release.

  7. Cathodoluminescence characterization of experimentally shocked alkali feldspar

    NASA Astrophysics Data System (ADS)

    Kayama, M.; Nishido, H.; Sekine, T.; Ninagawa, K.

    2009-12-01

    Cathodoluminescence (CL) spectroscopy and microscopy provide important information to know the existence and distribution of defects and trace elements in materials. CL features of materials depend on varieties of luminescence centers, host chemical compositions and crystal fields, all of which are closely related to the genetic processes. Advanced investigations on CL of shock-induced silica minerals have been attempted to estimate their shock pressures, although very few studies have been reported for feldspars. In this study, CL and Raman spectra of experimentally shocked alkali feldspar were measured to evaluate the shock metamorphic effect. A single crystal of sanidine (Or81Ab19) from Eifel, Germany was selected as a starting material for shock recovery experiments at peak pressures of about 10, 20, 32 and 40 GPa by a propellant gun. Polished thin sections of recovered samples were used for CL and Raman measurements. CL was collected in the range from 300 to 800 nm by a secondary electron microscopy-cathodoluminescence (SEM-CL) system. CL spectra of unshocked sample consist of two emission bands at around 420 nm in blue region and 720 nm in red-IR region assigned to Al-O--Al defect and Fe3+ impurity center, respectively. There are three features between unshocked and shocked sanidine. (1) The blue emission is absent in the shocked samples. (2) The peak wavelength of the red-IR emission shifts to a short wavelength side with an increase in shock pressure up to 20 GPa, suggesting the alteration of the crystal field related to Fe3+ activator by shock metamorphic effect. The Raman spectrum of the unshocked sample exhibits pronounced peaks at around 180, 205, 290, 490 and 520 cm-1. The intensities of these peaks decrease with an increase in shock pressure. The shocked samples above 32 GPa show only two weak peaks at around 490 and 580 cm-1 which were also observed in maskelynite in Martian meteorites. Shock pressure causes partly breaking of the framework structure

  8. Geochronology and petrogenesis of the western highlands alkali suite: Radiogenic isotopic evidence from Apollo 14

    NASA Astrophysics Data System (ADS)

    Snyder, Gregory A.; Taylor, Lawrence A.; Halliday, Alex N.

    1993-03-01

    Several rocks of alkalic affinity, from the western highlands of the Moon, have been analyzed for their Nd and Sr isotopic compositions. One sample yields a Sm-Nd mineral isochron of 4110 = 41 Ma. This age, in conjunction with U-Pb zircon ages on two other alkalic rocks from the Apollo 14 landing site suggests a distinct western highlands 'event' which was approximately 100 Ma in duration. Since the last dregs of the lunar magma ocean likely crystallized prior to 4.3 Ga, this alkalic 'event' may have included the re-melting of evolved plutons or the remobilization of urKREEP trapped liquid from upper mantle cumulates. Alkalic lithologies such as granites and felsites have been known from the Moon since the earliest days of the Apollo lunar sample returns. However, not until 1977 were alkali-rich rocks recognized from typical highlands suites such as ferroan anorthosites (FAN) and norites and Mg-suite rocks. In the intervening years, several other alkali suite samples have been discovered and characterized, mostly through labor-intesive breccia pull-apart studies of clasts and analyses of coarse-fine fractions of soils. We will speculate on the origins of this suite of lunar highlands rocks.

  9. Alkali Treatment of Acidic Solution from Hanford K Basin Sludge Dissolution

    SciTech Connect

    AA Bessonov; AB Yusov; AM Fedoseev; AV Gelis; AY Garnov; CH Delegard; GM Plavnik; LN Astafurova; MS Grigoriev; NA Budantseva; NN Krot; SI Nikitenko; TP Puraeva; VP Perminov; VP Shilov

    1998-12-22

    Nitric acid solutions will be created from the dissolution of Hanford K Basin sludge. These acidic dissolver solutions must be made alkaline by treatment with NaOH solution before they are disposed to ~ the Tank Waste Remediation System on the Hanford Site. During the alkali treatments, sodium diuranate, hydroxides of iron and aluminum, and radioelements (uranium, plutonium, and americium) will precipitate from the dissolver solution. Laboratory tests, discussed here, were pefiormed to provide information on these precipitates and their precipitation behavior that is important in designing the engineering flowsheet for the treatment process. Specifically, experiments were conducted to determine the optimum precipitation conditions; the completeness of uranium, plutonium, and americium precipitation; the rate of sedimentation; and the physico-chemical characteristics of the solids formed by alkali treatment of simulated acidic dissolver solutions. These experiments also determined the redistribution of uranium, plutonium, and americium flom the sodium di~ate and iron and al&inurn hydroxide precipitates upon contact with carbonate- and EDTA-bearing simulated waste solutions. Note: EDTA is the tetrasodium salt of ethylenediaminetetraacetate.

  10. Geochronology and petrogenesis of the western highlands alkali suite: Radiogenic isotopic evidence from Apollo 14

    NASA Technical Reports Server (NTRS)

    Snyder, Gregory A.; Taylor, Lawrence A.; Halliday, Alex N.

    1993-01-01

    Several rocks of alkalic affinity, from the western highlands of the Moon, have been analyzed for their Nd and Sr isotopic compositions. One sample yields a Sm-Nd mineral isochron of 4110 = 41 Ma. This age, in conjunction with U-Pb zircon ages on two other alkalic rocks from the Apollo 14 landing site suggests a distinct western highlands 'event' which was approximately 100 Ma in duration. Since the last dregs of the lunar magma ocean likely crystallized prior to 4.3 Ga, this alkalic 'event' may have included the re-melting of evolved plutons or the remobilization of urKREEP trapped liquid from upper mantle cumulates. Alkalic lithologies such as granites and felsites have been known from the Moon since the earliest days of the Apollo lunar sample returns. However, not until 1977 were alkali-rich rocks recognized from typical highlands suites such as ferroan anorthosites (FAN) and norites and Mg-suite rocks. In the intervening years, several other alkali suite samples have been discovered and characterized, mostly through labor-intesive breccia pull-apart studies of clasts and analyses of coarse-fine fractions of soils. We will speculate on the origins of this suite of lunar highlands rocks.

  11. Molecular dispersion energy parameters for alkali and halide ions in aqueous solution

    SciTech Connect

    Reiser, S.; Deublein, S.; Hasse, H.; Vrabec, J.

    2014-01-28

    Thermodynamic properties of aqueous solutions containing alkali and halide ions are determined by molecular simulation. The following ions are studied: Li{sup +}, Na{sup +}, K{sup +}, Rb{sup +}, Cs{sup +}, F{sup −}, Cl{sup −}, Br{sup −}, and I{sup −}. The employed ion force fields consist of one Lennard-Jones (LJ) site and one concentric point charge with a magnitude of ±1 e. The SPC/E model is used for water. The LJ size parameter of the ion models is taken from Deublein et al. [J. Chem. Phys. 136, 084501 (2012)], while the LJ energy parameter is determined in the present study based on experimental self-diffusion coefficient data of the alkali cations and the halide anions in aqueous solutions as well as the position of the first maximum of the radial distribution function of water around the ions. On the basis of these force field parameters, the electric conductivity, the hydration dynamics of water molecules around the ions, and the enthalpy of hydration is predicted. Considering a wide range of salinity, this study is conducted at temperatures of 293.15 and 298.15 K and a pressure of 1 bar.

  12. High capacity nickel battery material doped with alkali metal cations

    DOEpatents

    Jackovitz, John F.; Pantier, Earl A.

    1982-05-18

    A high capacity battery material is made, consisting essentially of hydrated Ni(II) hydroxide, and about 5 wt. % to about 40 wt. % of Ni(IV) hydrated oxide interlayer doped with alkali metal cations selected from potassium, sodium and lithium cations.

  13. Assesment of Alkali Resistance of Basalt Used as Concrete Aggregates

    NASA Astrophysics Data System (ADS)

    al-Swaidani, Aref M.; Baddoura, Mohammad K.; Aliyan, Samira D.; Choeb, Walid

    2015-11-01

    The objective of this paper is to report a part of an ongoing research on the influence of using crushed basalt as aggregates on one of durability-related properties of concrete (i.e. alkali-silica reaction which is the most common form of Alkali-Aggregate Reaction). Alkali resistance has been assessed through several methods specified in the American Standards. Results of petrographic examination, chemical test (ASTM C289) and accelerated mortar bar test (ASTM C1260) have particularly been reported. In addition, the weight change and compressive strength of 28 days cured concrete containing basaltic aggregates were also reported after 90 days of exposure to 10% NaOH solution. Dolomite aggregate were used in the latter test for comparison. The experimental results revealed that basaltic rocks quarried from As-Swaida'a region were suitable for production of aggregates for concrete. According to the test results, the studied basalt aggregates can be classified as innocuous with regard to alkali-silica reaction. Further, the 10% sodium hydroxide attack did not affect the compressive strength of concrete.

  14. Method of assembling and sealing an alkali metal battery

    DOEpatents

    Elkins, Perry E.; Bell, Jerry E.; Harlow, Richard A.; Chase, Gordon G.

    1983-01-01

    A method of initially assembling and then subsequently hermetically sealing a container portion of an alkali metal battery to a ceramic portion of such a battery is disclosed. Sealing surfaces are formed respectively on a container portion and a ceramic portion of an alkali metal battery. These sealing surfaces are brought into juxtaposition and a material is interposed therebetween. This interposed material is one which will diffuse into sealing relationship with both the container portion and the ceramic portion of the alkali metal battery at operational temperatures of such a battery. A pressure is applied between these sealing surfaces to cause the interposed material to be brought into intimate physical contact with such juxtaposed surfaces. A temporary sealing material which will provide a seal against a flow of alkali metal battery reactants therethrough at room temperatures and is applied over the juxtaposed sealing surfaces and material interposed therebetween. The entire assembly is heated to an operational temperature so that the interposed material diffuses into the container portion and the ceramic portion to form a hermetic seal therebetween. The pressure applied to the juxtaposed sealing surfaces is maintained in order to ensure the continuation of the hermetic seal.

  15. An analytical equation of state for molten alkali metals

    SciTech Connect

    Ghatee, M.H.; Boushehri, A.

    1995-11-01

    The paper brings the molten alkali metals into the scope of a new statistical mechanical equation of state that is known to satisfy normal fluids over the whole range. As for normal fluids, the latent heat of vaporization and density at freezing temperature are the only inputs (scaling factors). The corresponding-states correlation of normal fluids is used to calculate the second virial coefficient, B{sub 2}(T), of alkali metals, which is scarce experimentally and its calculation is complicated by dimer formation. Calculations of the other two temperature-dependent constants, {alpha}(T) and b (T), follow by scaling. The virial coefficients of alkali metals cannot be expected to obey a law of corresponding states for normal fluids. The fact that two potentials are involved may be the reason for this. Thus, alkali metals have the characteristics of interacting through singlet and triple potentials so that the treatment by a single potential here is fortuitous. The adjustable parameter of the equation of state, {Gamma}, compensates for the uncertainties in B{sub 2}(T). The procedure used to calculate the density of liquids Li through Cs from the freezing line up to several hundred degrees above the boiling temperatures. The results are within 5%.

  16. Influence of temperature on alkali stress adaptation in Listeria monocytogenes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Listeria monocytogenes cells may induce alkali stress adaptation when exposed to sublethal concentrations of alkaline cleaners and sanitizers that may be frequently used in the food processing environment. In the present study, the effect of temperature on the induction and the stability of such alk...

  17. Outer-core emission spectra of heavy alkali metals

    NASA Astrophysics Data System (ADS)

    Fink, R. L.; First, P. N.; Flynn, C. P.

    1988-09-01

    We report np5(n+1)s2-->np6(n+1)s emission spectra of K (n=3), Rb (n=4), and Cs (n=5), and compare emission-band characteristics through the series Na-Cs using earlier data for Na. The normalized band profiles of the different alkali metals are remarkably similar when scaled by the Fermi energy EF. However, the spin-orbit partner intensity ratios are far from the ideal value 2, reaching approximately 60 for Rb and above 65 for Cs, mainly owing to Coster-Kronig decays from higher levels. We confirm that the Mahan-Nozières-De Dominicis ``anomaly'' at EF is generally weaker in emission than in absorption. It decreases through the series to become undetectable for emission from Cs. A systematic increase of the core-hole-lifetime width occurs through the column of alkali metals from a reported estimate of 10 meV for Na to a value of 50 meV for Cs. A study of the Fermi-edge shape between 20 and 300 K reveals temperature-dependent phonon broadening in generally good agreement with theoretical predictions. Incomplete relaxation plays only a minor role in the edge processes of the heavy alkali metals. Additional Fermi-edge broadening and the shifted emission edges of surface atoms are observed for alkali-metal films 10-100 Å thick.

  18. Wellness Circles: The Alkali Lake Model in Community Recovery Processes.

    ERIC Educational Resources Information Center

    Ben, Leon W.; And Others

    The case study described here was conducted as a doctoral research project at Northern Arizona University. The study documents the success of the Shuswop Indian Band of Alkali Lake, British Columbia (Canada), in their 15-year battle with alcoholism, once the people themselves decided on recovery. The study looks back at the 95 percent recovery…

  19. Aqueous alkali metal hydroxide insoluble cellulose ether membrane

    NASA Technical Reports Server (NTRS)

    Hoyt, H. E.; Pfluger, H. L. (Inventor)

    1969-01-01

    A membrane that is insoluble in an aqueous alkali metal hydroxide medium is described. The membrane is a resin which is a water-soluble C2-C4 hydroxyalkyl cellulose ether polymer and an insolubilizing agent for controlled water sorption, a dialytic and electrodialytic membrane. It is particularly useful as a separator between electrodes or plates in an alkaline storage battery.

  20. Method of assembling and sealing an alkali metal battery

    DOEpatents

    Elkins, P.E.; Bell, J.E.; Harlow, R.A.; Chase, G.G.

    1983-03-01

    A method of initially assembling and then subsequently hermetically sealing a container portion of an alkali metal battery to a ceramic portion of such a battery is disclosed. Sealing surfaces are formed respectively on a container portion and a ceramic portion of an alkali metal battery. These sealing surfaces are brought into juxtaposition and a material is interposed there between. This interposed material is one which will diffuse into sealing relationship with both the container portion and the ceramic portion of the alkali metal battery at operational temperatures of such a battery. A pressure is applied between these sealing surfaces to cause the interposed material to be brought into intimate physical contact with such juxtaposed surfaces. A temporary sealing material which will provide a seal against a flow of alkali metal battery reactants there through at room temperatures and is applied over the juxtaposed sealing surfaces and material interposed there between. The entire assembly is heated to an operational temperature so that the interposed material diffuses into the container portion and the ceramic portion to form a hermetic seal there between. The pressure applied to the juxtaposed sealing surfaces is maintained in order to ensure the continuation of the hermetic seal. 4 figs.

  1. Chlor-Alkali Industry: A Laboratory Scale Approach

    ERIC Educational Resources Information Center

    Sanchez-Sanchez, C. M.; Exposito, E.; Frias-Ferrer, A.; Gonzalez-Garaia, J.; Monthiel, V.; Aldaz, A.

    2004-01-01

    A laboratory experiment for students in the last year of degree program in chemical engineering, chemistry, or industrial chemistry is presented. It models the chlor-alkali process, one of the most important industrial applications of electrochemical technology and the second largest industrial consumer of electricity after aluminium industry.

  2. Stabilized Alkali-Metal Ultraviolet-Band-Pass Filters

    NASA Technical Reports Server (NTRS)

    Mardesich, Nick; Fraschetti, George A.; Mccann, Timothy; Mayall, Sherwood D.; Dunn, Donald E.; Trauger, John T.

    1995-01-01

    Layers of bismuth 5 to 10 angstrom thick incorporated into alkali-metal ultraviolet-band-pass optical filters by use of advanced fabrication techniques. In new filters layer of bismuth helps to reduce surface migration of sodium. Sodium layer made more stable and decreased tendency to form pinholes by migration.

  3. Estimating rates and patterns of morphological evolution from phylogenies: lessons in limb lability from Australian Lerista lizards.

    PubMed

    Wiens, John J

    2009-01-01

    Squamates (lizards and snakes) offer an exciting model system for research on the evolution of body form. A new phylogenetic study in BMC Evolutionary Biology of Australian lizards shows remarkable evolutionary lability in digit numbers among closely related species, but also highlights important challenges in this area.

  4. On the Labile Memory Buffer in the Attentional Blink: Masking the T2 Representation by Onset Transients Mediates the AB

    ERIC Educational Resources Information Center

    Jannati, Ali; Spalek, Thomas M.; Di Lollo, Vincent

    2011-01-01

    Report of a second target (T2) is impaired when presented within 500 ms of the first (T1). This attentional blink (AB) is known to cause a delay in T2 processing during which T2 must be stored in a labile memory buffer. We explored the buffer's characteristics using different types of masks after T2. These characteristics were inferred by…

  5. Size-optimized galactose-capped gold nanoparticles for the colorimetric detection of heat-labile enterotoxin at nanomolar concentrations.

    PubMed

    Poonthiyil, Vivek; Golovko, Vladimir B; Fairbanks, Antony J

    2015-05-14

    The development of a galactose-capped gold nanoparticle-based colorimetric sensor for the detection of the lectin heat-labile enterotoxin is reported. Heat-labile enterotoxin is one of the pathogenic agents responsible for the intestinal disease called 'traveller's diarrhoea'. By means of specific interaction between galactose moieties attached to the surface of gold nanoparticles and receptors on the B-subunit of heat-labile enterotoxin (LTB), the gold nanoparticles reported here act as an efficient colorimetric sensor, which can detect the toxin at nanomolar concentrations. The effect of gold nanoparticle size on the detection sensitivity was investigated in detail. Amongst the various sizes of gold nanoparticles studied (2, 7, 12, and 20 nm), the 12 nm sized gold nanoparticles were found to be the most efficient, with a minimum heat-labile enterotoxin detection concentration of 100 nM. The red to purple colour change of the gold nanoparticle solution occurred within two minutes, indicating rapid toxin sensing.

  6. An anaerobic incubation study of metal lability in drinking water treatment residue with implications for practical reuse.

    PubMed

    Wang, Changhui; Yuan, Nannan; Pei, Yuansheng

    2014-06-15

    Drinking water treatment residue (WTR) is an inevitable by-product generated during the treatment of drinking water with coagulating agents. The beneficial reuse of WTR as an amendment for environmental remediation has attracted growing interest. In this work, we investigated the lability of Al, As, Ba, Be, Ca, Cd, Co, Cr, Cu, Fe, Mg, Mn, Mo, Ni, Pb, Sr, V and Zn in Fe/Al hydroxide-comprised WTR based on a 180-day anaerobic incubation test using fractionation, in vitro digestion and a toxicity characteristic leaching procedure. The results indicated that most metals in the WTR were stable during anaerobic incubation and that the WTR before and after incubation could be considered non-hazardous in terms of leachable metal contents according to US EPA Method 1311. However, the lability of certain metals in the WTR after incubation increased substantially, especially Mn, which may be due to the reduction effect. Therefore, although there is no evidence presented to restrict the use of WTR in the field, the lability of metals (especially Mn) in WTR requires further assessment prior to field application. In addition, fractionation (e.g., BCR) is recommended for use to determine the potential lability of metals under various conditions.

  7. Analysis and modeling of heat-labile enterotoxins of Escherichia coli suggests a novel space with insights into receptor preference.

    PubMed

    Krishna Raja, M; Ghosh, Asit Ranjan; Vino, S; Sajitha Lulu, S

    2015-01-01

    Features of heat-labile enterotoxins of Escherichia coli which make them fit to use as novel receptors for antidiarrheals are not completely explored. Data-set of 14 different serovars of enterotoxigenic Escherichia coli producing heat-labile toxins were taken from NCBI Genbank database and used in the study. Sequence analysis showed mutations in different subunits and also at their interface residues. As these toxins lack crystallography structures, homology modeling using Modeller 9.11 led to the structural approximation for the E. coli producing heat-labile toxins. Interaction of modeled toxin subunits with proanthocyanidin, an antidiarrheal showed several strong hydrogen bonding interactions at the cost of minimized energy. The hits were subsequently characterized by molecular dynamics simulation studies to monitor their binding stabilities. This study looks into novel space where the ligand can choose the receptor preference not as a whole but as an individual subunit. Mutation at interface residues and interaction among subunits along with the binding of ligand to individual subunits would help to design a non-toxic labile toxin and also to improve the therapeutics.

  8. Forms and lability of phosphorus in algae and aquatic macrophytes characterized by solution 31P NMR coupled with enzymatic hydrolysis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Increased information on forms and lability of phosphorus (P) in aquatic macrophytes and algae is crucial for better understanding of P biogeochemical cycling in eutrophic lakes. In this work, solution 31P nuclear magnetic resonance (NMR) spectroscopy coupled with enzymatic hydrolysis (EH) was used ...

  9. Tillage and rotational effects on exchangeable and enzyme-labile phosphorus forms in conventional and organic cropping systems

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The transformations of crop residues and bio-fertilizers used as primary sources of nutrients for organic grain and forage production are influenced by soil management practices. The effects of management of the near-surface zone on labile phosphorus (P) forms were studied in soil under three organ...

  10. Rapid latex particle agglutination test for Escherichia coli strains of porcine origin producing heat-labile enterotoxin.

    PubMed Central

    Finkelstein, R A; Yang, Z S; Moseley, S L; Moon, H W

    1983-01-01

    A latex particle agglutination test previously shown to be suitable for the rapid identification of Escherichia coli strains of human origin producing heat-labile enterotoxin (R. A. Finkelstein and Z. Yang, J. Clin. Microbiol. 18:23-28) is equally applicable to strains of porcine origin. PMID:6361056

  11. Thermal Analysis of Labile Trace Elements in CM and CV Carbonaceous Chondrites Using Inductively Coupled Plasma-Mass Spectrometry

    NASA Technical Reports Server (NTRS)

    Lauretta, D. S.; Klaue, B.; Blum, J. D.; Buseck, P. R.

    2001-01-01

    We developed a technique to measure the thermal release profiles of a suite of labile elements (Zn, As, Se, Cd, In, Sn, Sb, Te, Pt, Hg, Au, Tl, Pb, Bi). Conclusions are reached about the behavior of each element during parent-body alteration. Additional information is contained in the original extended abstract.

  12. Emotional Lability in Children and Adolescents with Attention Deficit/Hyperactivity Disorder (ADHD): Clinical Correlates and Familial Prevalence

    ERIC Educational Resources Information Center

    Sobanski, Esther; Banaschewski, Tobias; Asherson, Philip; Buitelaar, Jan; Chen, Wai; Franke, Barbara; Holtmann, Martin; Krumm, Bertram; Sergeant, Joseph; Sonuga-Barke, Edmund; Stringaris, Argyris; Taylor, Eric; Anney, Richard; Ebstein, Richard P.; Gill, Michael; Miranda, Ana; Mulas, Fernando; Oades, Robert D.; Roeyers, Herbert; Rothenberger, Aribert; Steinhausen, Hans-Christoph; Faraone, Stephen V.

    2010-01-01

    Background: The goal of this study was to investigate the occurrence, severity and clinical correlates of emotional lability (EL) in children with attention deficit/hyperactivity disorder (ADHD), and to examine factors contributing to EL and familiality of EL in youth with ADHD. Methods: One thousand, one hundred and eighty-six children with ADHD…

  13. A Longitudinal Study of Emotion Regulation, Emotion Lability-Negativity, and Internalizing Symptomatology in Maltreated and Nonmaltreated Children

    ERIC Educational Resources Information Center

    Kim-Spoon, Jungmeen; Cicchetti, Dante; Rogosch, Fred A.

    2013-01-01

    The longitudinal contributions of emotion regulation and emotion lability-negativity to internalizing symptomatology were examined in a low-income sample (171 maltreated and 151 nonmaltreated children, from age 7 to 10 years). Latent difference score models indicated that for both maltreated and nonmaltreated children, emotion regulation was a…

  14. Effects of neuroprotector cortexin on the dynamics of neuroendocrine system parameters in patients with organic emotionally labile (asthenic) disorders.

    PubMed

    Levchuk, L A; Ivanova, S A; Semke, V Ya

    2013-05-01

    Addition of neuroprotector Cortexin to standard drug therapy of patients with organic emotionally labile (asthenic) disorders had a great influence on the neuroendocrine system and neurosteroid content: normalization of blood concentration of cortisol, dehydroepiandrosterone sulphate, and thyroid hormones was observed. Clinical improvement was associated with the recovery of organism homeostatic systems.

  15. Oral immunization of mice with attenuated Salmonella enteritidis containing a recombinant plasmid which codes for production of the B subunit of heat-labile Escherichia coli enterotoxin.

    PubMed Central

    Clements, J D; Lyon, F L; Lowe, K L; Farrand, A L; el-Morshidy, S

    1986-01-01

    We used Salmonella enteritidis serotype dublin strain SL1438, a nonreverting, aromatic-dependent, histidine-requiring mutant, as a recipient for a recombinant plasmid coding for production of the nontoxic B subunit of the heat-labile Escherichia coli enterotoxin. The S. enteritidis derivative EL23 produced heat-labile enterotoxin subunit B that was indistinguishable from heat-labile enterotoxin subunit B produced by strains of E. coli or Salmonella typhi harboring the same plasmid. Mice immunized orally with strain EL23 developed progressively increasing mucosal and serum antibody responses to both heat-labile enterotoxin subunit B and to the lipopolysaccharide of the vaccine strain. The mucosal antibody response was shown to be immunoglobulin A specific and to be capable of neutralizing the biological activities of both E. coli heat-labile enterotoxin and cholera enterotoxin in vitro. Images PMID:3527989

  16. Alkali element constraints on Earth-Moon relations

    NASA Technical Reports Server (NTRS)

    Norman, M. D.; Drake, M. J.; Jones, J. H.

    1994-01-01

    Given their range of volatilities, alkali elements are potential tracers of temperature-dependent processes during planetary accretion and formation of the Earth-Moon system. Under the giant impact hypothesis, no direct connection between the composition of the Moon and the Earth is required, and proto-lunar material does not necessarily experience high temperatures. Models calling for multiple collisions with smaller planetesimals derive proto-lunar materials mainly from the Earth's mantle and explicitly invoke vaporization, shock melting and volatility-related fractionation. Na/K, K/Rb, and Rb/Cs should all increase in response to thermal volatization, so theories which derive the Moon substantially from Earth's mantle predict these ratios will be higher in the Moon than in the primitive mantle of the Earth. Despite the overall depletion of volatile elements in the Moon, its Na/K and K/Rb are equal to or less than those of Earth. A new model presented here for the composition of Earth's continental crust, a major repository of the alkali elements, suggests the Rb/Cs of the Moon is also less than that of Earth. Fractionation of the alkali elements between Earth and Moon are in the opposite sense to predictions based on the relative volatilities of these elements, if the Moon formed by high-T processing of Earth's mantle. Earth, rather than the Moon, appears to carry a signature of volatility-related fractionation in the alkali elements. This may reflect an early episode of intense heating on Earth with the Moon's alkali budget accreting from cooler material.

  17. A reactor system for studying the interactions between alkali vapors and ceramic compounds

    SciTech Connect

    Shadman, F.; Punjak, W.A.

    1987-01-01

    The kinetics and mechanism of interaction between alkali vapors and several ceramic compounds are studied. A unique micro-gravimetric reactor is designed and utilized for this study. Bauxite and kaolin are very good adsorbents for alkali chlorides and are potentially good additives for control of alkali during coal combustion and gasification. The experimental data shows that the alkali capturing process is a combination of physisorption, chemisorption and chemical reaction. An analytical model is developed assuming a multi-layer adsorption of alkali on substrate followed by a rate-controlling rection on the surface. The experimental results and model predictions are in good agreement.

  18. Highly Effective Pt-Based Water-Gas Shift Catalysts by Surface Modification with Alkali Hydroxide Salts

    SciTech Connect

    Kusche, Matthias; Bustillo, Karen; Agel, Friederike; Wasserscheid, Peter

    2015-01-29

    Here, we describe an economical and convenient method to improve the performance of Pt/alumina catalysts for the water–gas shift reaction through surface modification of the catalysts with alkali hydroxides according to the solid catalyst with ionic liquid layer approach. The results are in agreement with our findings reported earlier for methanol steam reforming. This report indicates that alkali doping of the catalyst plays an important role in the observed catalyst activation. In addition, the basic and hygroscopic nature of the salt coating contributes to a significant improvement in the performance of the catalyst. During the reaction, a partly liquid film of alkali hydroxide forms on the alumina surface, which increases the availability of H2O at the catalytically active sites. Kinetic studies reveal a negligible effect of the KOH coating on the rate dependence of CO and H2O partial pressures. In conclusion, TEM studies indicate an agglomeration of the active Pt clusters during catalyst preparation; restructuring of Pt nanoparticles occurs under reaction conditions, which leads to a highly active and stable system over 240h time on stream. Excessive pore fillings with KOH introduce a mass transfer barrier as indicated in a volcano-shaped curve of activity versus salt loading. The optimum KOH loading was found to be 7.5wt%.

  19. Highly Effective Pt-Based Water-Gas Shift Catalysts by Surface Modification with Alkali Hydroxide Salts

    DOE PAGES

    Kusche, Matthias; Bustillo, Karen; Agel, Friederike; ...

    2015-01-29

    Here, we describe an economical and convenient method to improve the performance of Pt/alumina catalysts for the water–gas shift reaction through surface modification of the catalysts with alkali hydroxides according to the solid catalyst with ionic liquid layer approach. The results are in agreement with our findings reported earlier for methanol steam reforming. This report indicates that alkali doping of the catalyst plays an important role in the observed catalyst activation. In addition, the basic and hygroscopic nature of the salt coating contributes to a significant improvement in the performance of the catalyst. During the reaction, a partly liquid filmmore » of alkali hydroxide forms on the alumina surface, which increases the availability of H2O at the catalytically active sites. Kinetic studies reveal a negligible effect of the KOH coating on the rate dependence of CO and H2O partial pressures. In conclusion, TEM studies indicate an agglomeration of the active Pt clusters during catalyst preparation; restructuring of Pt nanoparticles occurs under reaction conditions, which leads to a highly active and stable system over 240h time on stream. Excessive pore fillings with KOH introduce a mass transfer barrier as indicated in a volcano-shaped curve of activity versus salt loading. The optimum KOH loading was found to be 7.5wt%.« less

  20. Alkali solution extraction of rice residue protein isolates: Influence of alkali concentration on protein functional, structural properties and lysinoalanine formation.

    PubMed

    Hou, Furong; Ding, Wenhui; Qu, Wenjuan; Oladejo, Ayobami Olayemi; Xiong, Feng; Zhang, Weiwei; He, Ronghai; Ma, Haile

    2017-03-01

    This study evaluated the nutrient property and safety of the rice residue protein isolates (RRPI) product (extracted by different alkali concentrations) by exploring the protein functional, structural properties and lysinoalanine (LAL) formation. The results showed that with the rising of alkali concentration from 0.03M to 0.15M, the solubility, emulsifying and foaming properties of RRPI increased at first and then descended. When the alkali concentration was greater than 0.03M, the RRPI surface hydrophobicity decreased and the content of thiol and disulfide bond, Lys and Cys significantly reduced. By the analysis of HPLC, the content of LAL rose up from 276.08 to 15,198.07mg/kg and decreased to 1340.98mg/kg crude protein when the alkali concentration increased from 0.03 to 0.09M and until to 0.15M. These results indicated that RRPI alkaline extraction concentration above 0.03M may cause severe nutrient or safety problems of protein.

  1. Interactions and low-energy collisions between an alkali ion and an alkali atom of a different nucleus

    NASA Astrophysics Data System (ADS)

    Rakshit, Arpita; Ghanmi, Chedli; Berriche, Hamid; Deb, Bimalendu

    2016-05-01

    We study theoretically interaction potentials and low-energy collisions between different alkali atoms and alkali ions. Specifically, we consider systems such as X + {{{Y}}}+, where X({{{Y}}}+) is either Li(Cs+) or Cs(Li+), Na(Cs+) or Cs(Na+) and Li(Rb+) or Rb(Li+). We calculate the molecular potentials of the ground and first two excited states of these three systems using a pseudopotential method and compare our results with those obtained by others. We derive ground-state scattering wave functions and analyze the cold collisional properties of these systems for a wide range of energies. We find that, in order to get convergent results for the total scattering cross sections for energies of the order 1 K, one needs to take into account at least 60 partial waves. The low-energy scattering properties calculated in this paper may serve as a precursor for experimental exploration of quantum collisions between an alkali atom and an alkali ion of a different nucleus.

  2. Multivariate Statistical Analysis of Labile Trace Elements in H Chondrites: Evidence for Meteoroid Streams

    NASA Astrophysics Data System (ADS)

    Wolf, S. F.; Lipschutz, M. E.

    1992-07-01

    Differences have been observed between meteorite populations with vastly different terrestrial ages, i.e. Antarctic and non-Antarctic meteorite populations (Koeberl and Cassidy, 1991 and references therein). Comparisons of labile trace element contents (Wolf and Lipschutz, 1992) and induced TL parameters (Benoit and Sears, 1992) in samples from Victoria Land and Queen Maud Land, populations which also differ in mean terrestrial age (Nishiizumi et al, 1989), show significant differences consistent with different average thermal histories. These differences are consistent with the proposition that the flux of meteoritic material to Earth varied temporally. Variations in the flux of meteoritic material over time scales of 10^5 10^6 y require the existence of undispersed streams of meteoroids of asteroidal origin which were initially disputed by Wetherill ( 1986) but have since been observed (Olsson-Steele, 1988; Oberst, 1989; Halliday et al. 1990). Orbital evidence for meteoroid and asteroid streams has been independently obtained by others, particularly Halliday et al.(1990) and Drummond (1991). A group of H chondrites of various petrographic types and diverse CRE ages that yielded 16 falls from 1855 until 1895 in the month of May has been proposed to be two co-orbital meteoroid streams with a common source (R. T. Dodd, personal communication). Compositional evidence of a preterrestrial association of the proposed stream members, if it exists, might be observed in the most sensitive indicators of genetic thermal history, the labile trace elements. We report RNAA data for the concentrations of 14 trace elements, mostly labile ones, (Ag, Au, Bi, Cd, Cs, Co, Ga, In, Rb, Sb, Se, Te, Tl, and Zn) in H4-6 ordinary chondrites. Variance of elemental concentrations within a subpopulation, the members of a proposed co-orbital meteorite stream for example, could be expected to be smaller than the variance for the entire population. We utilize multivariate linear regression and

  3. Unified mechanism of alkali and alkaline earth catalyzed gasification reactions of carbon by CO2 and H2O

    USGS Publications Warehouse

    Chen, S.G.; Yang, R.T.

    1997-01-01

    From molecular orbital calculations, a unified mechanism is proposed for the gasification reactions of graphite by CO2 and H2O, both uncatalyzed and catalyzed by alkali and alkaline earth catalysts. In this mechanism, there are two types of oxygen intermediates that are bonded to the active edge carbon atoms: an in-plane semiquinone type, Cf(O), and an off-plane oxygen bonded to two saturated carbon atoms that are adjacent to the semiquinone species, C(O)Cf(O). The rate-limiting step is the decomposition of these intermediates by breaking the C-C bonds that are connected to Cf(O). A new rate equation is derived for the uncatalyzed reactions, and that for the catalyzed reactions is readily available from the proposed mechanism. The proposed mechanism can account for several unresolved experimental observations: TPD and TK (transient kinetics) desorption results of the catalyzed systems, the similar activation energies for the uncatalyzed and catalyzed reactions, and the relative activities of the alkali and alkaline earth elements. The net charge of the edge carbon active site is substantially changed by gaining electron density from the alkali or alkaline earth element (by forming C-O-M, where M stands for metal). The relative catalytic activities of these elements can be correlated with their abilities of donating electrons and changing the net charge of the edge carbon atom. As shown previously (Chen, S. G.; Yang, R. T. J. Catal. 1993, 141, 102), only clusters of the alkali compounds are active. This derives from the ability of the clusters to dissociate CO2 and H2O to form O atoms and the mobility of the dissociated O atoms facilitated by the clusters.

  4. [Enhancement of anaerobic digestion of excess sludge by acid-alkali pretreatment].

    PubMed

    Yuan, Guang-Huan; Zhou, Xing-Qiu; Wu, Jian-Dong

    2012-06-01

    In order to enhance the efficiency of anaerobic digestion of excess sludge, acid-alkali pretreatment method was studied. Three different pretreatment methods (alkali alone,acid-alkali, alkali-acid) were compared to investigate their impacts on hydrolysis and acidification of activated sludge. In addition, their influences on methane-producing in subsequent anaerobic digestion process were also studied. The results showed that the soluble chemical oxygen demand (SCOD) of alkaline treatment alone was about 16% higher than the combining of acid and alkali treatment, SCOD concentration increased to 5406.1 mg x L(-1) after 8 d pretreatment. After treated by acid (pH 4.0, 4 d) and alkali (pH 10.0, 4 d), the acetic acid production and its content in short-chain fatty acids (SCFAs) were higher than other pretreatment methods. And the acetic acid production (as COD/VSS) could reach 74.4 mg x g(-1), accounting for 60.5% of SCFAs. After acid-alkali pretreatment, the C: N ratio of the sludge mixed liquor was about 25, and the C: P ratio was between 35-40, which was more favorable than C: N and C: P ratio of alkali alone and alkali-acid to subsequent anaerobic digestion. The control experiments showed that, after acid-alkali pretreatment, anaerobic digestion cumulative methane yield (CH4/VSS(in)) reached to 136.1 mL x g(-1) at 15 d, which was about 2.5-, 1.6-, and 1.7-fold of the blank (unpretreated), alkali alone pretreatment and alkali-acid pretreatment, respectively. After acid-alkali pretreatment for 8 d and anaerobic digestion for 15 d, the removal efficiency of VSS was about 60.9%, and the sludge reduction effect was better than other pretreatments. It is obvious that the acid-alkali pretreatment method was more favorable to anaerobic digestion and sludge reduction.

  5. 14C as a tracer of labile organic matter in Antarctic benthic food webs

    NASA Astrophysics Data System (ADS)

    Purinton, Brett L.; DeMaster, David J.; Thomas, Carrie J.; Smith, Craig R.

    2008-11-01

    14C measurements were made on surface plankton, particle-trap material, surface sediment, benthic invertebrate gut contents, and body tissue samples to assess the effectiveness of this radioisotope as a tracer of labile organic carbon in Antarctic benthic food webs. Samples were collected on five cruises to the West Antarctic Peninsula (WAP) shelf between November 1999 and March 2001 as part of the Food for Benthos on the ANtarctic Continental-Shelf (FOODBANCS) Project. The 14C contents of the body tissues from a variety of deposit feeders (-126±13 per mil) were substantially enriched relative to the surface sediment (-234±13 per mil) and statistically similar to the organic matter collected in plankton tows (-135±10 per mil), indicating that recently produced marine plankton are the primary source of nutrition for these deposit feeders on the West Antarctic shelf. Selective ingestion was the primary feeding strategy used by echiuran worms and certain holothurians (i.e. Peniagone vignoni) for incorporating labile organic carbon into their tissues as demonstrated by the large differences (105±13 per mil) between surface sediment and gut content 14C activities. In contrast, digestive and/or assimilatory selection was the predominant strategy used by an irregular urchin ( Amphipneustes lorioli) and several other holothurians ( Protelpidia murrayi, Bathyplotes fuscivinculum and the head-down conveyor belt feeder, Molpadia musculus), as demonstrated by large differences (42±7 per mil) between the 14C activities of their foregut or whole-gut organic contents and their body tissues. Despite large fluctuations in carbon export from the euphotic zone, benthic feeding strategies remained essentially constant over the 15-month sampling period. No seasonal variation was evident in either the 14C abundance of the deposit-feeder body tissues, or in the 14C abundance of their gut contents. The mean 14C abundance in the body tissues of the two sub-surface deposit feeders ( A

  6. Fluxes of phytopigments and labile organic matter to the deep ocean in the NE Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Fabiano, M.; Pusceddu, A.; Dell'Anno, A.; Armeni, M.; Vanucci, S.; Lampitt, R. S.; Wolff, G. A.; Danovaro, R.

    Downward fluxes of labile organic matter (phytopigments, proteins and carbohydrates) were measured between September 1996 and August 1998 at three depths 1000 m, 3000 m and 4700 m (c. 100 mab) over the Porcupine Abyssal Plain (PAP, NE Atlantic), to provide detailed information on the biochemical characteristics of organic inputs to the deep sea. Temporal changes in the carbohydrate and protein fluxes were compared to carbohydrate and protein contents of the surficial sediment on the seabed beneath the traps at 4850 m depth. Fluxes of carbohydrate, protein and phytopigments (chlorophylls-a and -b, and phaeophytins-a and -b) displayed strong seasonal variations, but limited interannual variability between the two years of measurement. Fluxes of labile organic matter were characterised by strong pulses which occurred in spring and early summer, suggesting that the deep PAP area experiences relatively predictable patterns of vertical fluxes. No major quantitative differences in organic matter fluxes were observed between traps at different depths, but highest carbohydrate fluxes (time-weighted mean 2.4 mg m -2 d -1) were observed at 4700 m, whereas highest protein fluxes were observed at 1000 m (time-weighted mean 2.1 mg m -2 d -1). Carbohydrate, protein and phytopigment fluxes were correlated significantly, suggesting that settling material was associated with primary organic matter (i.e., phytodetritus) inputs from the photic layer. The contributions of chlorophyll-a and -b, and of phaeophytin-a and -b did not change significantly with increasing depth. Nor did the ratio of total phaeopigments to total chlorophylls did change greatly with depth (0.3-0.4 at both 3000 m and 4700 m depth) suggesting that degradation rates in the sinking particles were low. Protein and carbohydrate concentrations in the sediments at 4850 m depth (collected during 6 cruises between 1996 and 1998) and vertical fluxes at 3000 m depth followed inverse temporal patterns; peak concentrations

  7. Preservation of labile organic matter in soils of drained thaw lakes in Northern Alaska

    NASA Astrophysics Data System (ADS)

    Mueller, Carsten W.; Rethemeyer, Janet; Kao-Kniffin, Jenny; Löppmann, Sebastian; Hinkel, Kenneth; Bockheim, James

    2014-05-01

    A large number of studies predict changing organic matter (OM) dynamics in arctic soils due to global warming. In contrast to rather slowly altering bulk soil properties, single soil organic matter (SOM) fractions can provide a more detailed picture of the dynamics of differently preserved SOM pools in climate sensitive arctic regions. By the study of the chemical composition of such distinctive SOM fractions using nuclear magnetic resonance spectroscopy (NMR) together with radiocarbon analyses it is possible to evaluate the stability of the major OM pools. Approximately 50-75% of Alaska's Arctic Coastal Plain is covered with thaw lakes and drained thaw lakes that follow a 5,000 yr cycle of development (between creation and final drainage), thus forming a natural soil chronosequence. The drained thaw lakes offer the possibility to study SOM dynamics affected by permafrost processes over millennial timescales. In April 2010 we sampled 16 soil cores (including the active and permanent layer) reaching from young drained lakes (0-50 years since drainage) to ancient drained lakes (3000-5500 years since drainage). Air dried soil samples from soil horizons of the active and permanent layer were subjected to density fractionation in order to differentiate particulate OM and mineral associated OM. The chemical composition of the SOM fractions was analyzed by 13C CPMAS NMR spectroscopy. For a soil core of a young and an ancient drained thaw lake basin we also analyzed the 14C content. For the studied soils we can show that up to over 25 kg OC per square meter are stored mostly as labile, easily degradable organic matter rich in carbohydrates. In contrast only 10 kg OC per square meter were sequestered as presumably more stable mineral associated OC dominated by aliphatic compounds. Comparable to soils of temperate regions, we found small POM (< 20 µm) occluded in aggregated soil structures which differed in the chemical composition from larger organic particles. This was

  8. First hyperpolarizability of cyclooctatetraene modulated by alkali and alkaline earth metals.

    PubMed

    Roy, Ria Sinha; Mondal, Avijit; Nandi, Prasanta K

    2017-03-01

    In the present investigation, the first hyperpolarizability of alkali and alkaline earth metal derivatives of cyclooctatetraene (COT) has been calculated using BHHLYP and CAM-B3LYP functional for 6-311++G(d,p), 6-311++G(3df,3pd), and aug-pc 2 basis sets. Introduction of Na/K atoms at the axial position of COT and Li, Na, K/Be, Mg, Ca metal atoms and cyanide groups at the equatorial sites leads to lager enhancement of first hyperpolarizability. The ring charge density can account for the variation of first hyperpolarizability. The two state model has been invoked to explain the variation of first hyperpolarizability.

  9. IRMPD Spectroscopy of Metalated Flavins: Structure and Bonding of Lumiflavin Complexes with Alkali and Coinage Metal Ions.

    PubMed

    Nieto, Pablo; Günther, Alan; Berden, Giel; Oomens, Jos; Dopfer, Otto

    2016-10-01

    Flavins are a fundamental class of biomolecules, whose photochemical properties strongly depend on their environment and their redox and metalation state. Infrared multiphoton dissociation (IRMPD) spectra of mass selected isolated metal-lumiflavin ionic complexes (M+LF) are analyzed in the fingerprint range (800-1830 cm-1) to determine the bonding of lumiflavin with alkali (M=Li, Na, K, Cs) and coinage (M=Cu, Ag) metal ions. The complexes are generated in an electrospray ionization source coupled to an ion cyclotron resonance mass spectrometer and the IR free electron laser FELIX. Vibrational and isomer assignments of the IRMPD spectra are accomplished by comparison to quantum chemical calculations at the B3LYP/cc-pVDZ level, yielding structure, binding energy, bonding mechanism, and spectral properties of the complexes. The most stable binding sites identified in the experiments involve metal bonding to the oxygen atoms of the two available CO groups of LF. Hence, CO stretching frequencies are a sensitive indicator of both the metal binding site and the metal bond strength. More than one isomer is observed for M=Li, Na, and K, and the preferred CO binding site changes with the size of the alkali ion. For Cs+LF only one isomer is identified although the energies of the two most stable structures differ by less than 7 kJ/mol. While the M+-LF bonds for alkali ions are mainly based on electrostatic forces, substantial covalent contributions lead to stronger bonds for the coinage metal ions. Comparison between lumiflavin and lumichrome reveals substantial differences in the metal binding motifs and interactions due to the different flavin structures.

  10. Generation and characterization of alkali metal clusters in Y-FAU zeolites. An ESR and MAS NMR spectroscopic study

    NASA Astrophysics Data System (ADS)

    Hannus, István; Béres, Attila; Nagy, János B.; Halász, János; Kiricsi, Imre

    1997-06-01

    Charged and neutral metal clusters of various compositions and sizes can be prepared by controlling the alkali metal content by the decomposition of alkali azides and the composition of the host zeolite by ion-exchange. ESR signals show that electron transfer from alkali metal atoms to alkali metal cations does occur, but in a direction opposite to that predicted by the gas-phase thermochemistry. Alkali metal clusters proved to be very active basic catalytic centers.

  11. Alkali Halide Microstructured Optical Fiber for X-Ray Detection

    NASA Technical Reports Server (NTRS)

    DeHaven, S. L.; Wincheski, R. A.; Albin, S.

    2014-01-01

    Microstructured optical fibers containing alkali halide scintillation materials of CsI(Na), CsI(Tl), and NaI(Tl) are presented. The scintillation materials are grown inside the microstructured fibers using a modified Bridgman-Stockbarger technique. The x-ray photon counts of these fibers, with and without an aluminum film coating are compared to the output of a collimated CdTe solid state detector over an energy range from 10 to 40 keV. The photon count results show significant variations in the fiber output based on the materials. The alkali halide fiber output can exceed that of the CdTe detector, dependent upon photon counter efficiency and fiber configuration. The results and associated materials difference are discussed.

  12. The optical properties of alkali nitrate single crystals

    NASA Astrophysics Data System (ADS)

    Anan'ev, Vladimir; Miklin, Mikhail

    2000-08-01

    Absorption of non-polarized light by a uniaxial crystal has been studied. The degree of absorption polarization has been calculated as a function of the ratio of optical densities in the region of low and high absorbances. This function is proposed for analysis of the qualitative and quantitative characteristics of uniaxial crystal absorption spectra. Non-polarized light spectra of alkali nitrate single crystals, both pure and doped with thallium, have been studied. It is shown that the absorption band at 300 nm is due to two transitions, whose intensities depend on temperature in various ways. There is a weak band in a short wavelength range of the absorption spectrum of potassium nitrate crystal, whose intensity increases with thallium doping. The band parameters of alkali nitrate single crystals have been calculated. Low-energy transitions in the nitrate ion have been located.

  13. Control of alkali vapors by a granular-bed filter

    SciTech Connect

    Lee, S.H.D.; Myles, K.M.; Jonke, A.A.

    1983-01-01

    Control of alkali vapors in the pressurized fluidized-bed combustion (PFBC) of coal is being studied in a laboratory-scale fixed granular-bed filter. The potential sorbents identified earlier were tested for their alkali vapor sorption in a gas stream with temperature (greater than or equal to 850/sup 0/C), pressure (10 atm absolute), and composition closely simulating actual PFBC flue gas. The NaCl-vapor sorption efficiency of activated bauxite is > 99.8% and was found not to be diminished by HCl in flue gas. Diatomaceous earth has lower sorption efficiencies than activated bauxite. Emathlite, a fuller's earth, has a capability for NaCl-vapor capture. Its sorption behavior and preliminary sorption efficiencies are presented and discussed.

  14. Petrology and geochemistry of alkali gabbronorites from lunar breccia 67975

    NASA Technical Reports Server (NTRS)

    James, Odette B.; Flohr, Marta K.; Lindstrom, Marilyn M.

    1987-01-01

    Detailed results of petrologic and compositional studies of three clasts found in thin sections of the Apollo 16 lunar breccia 67975 and of four clasts extracted from the breccia (for instrumental neutron activation analysis) prior to thin sectioning are reported. The alkali gabbronorites of the breccia form two distinct subgroups, magnesian and ferroan. The magnesian gabbronorites are composed of bytownitic plagioclase, hypersthene, augite, a silica mineral, and trace Ba-rich K-feldspar. The ferroan gabbronorites are composed of ternary plagioclase, pigeonite, augite, Ba-rich K-feldspar, and a silica mineral. Trace minerals in both subgroups are apatite, REE-rich whitlockite, and zircon. The magnesian and ferroan alkali gabbronorites appear to have formed by progressive differentiation of the same, or closely related, parent REE-rich magmas.

  15. Polymerization reactivity of sulfomethylated alkali lignin modified with horseradish peroxidase.

    PubMed

    Yang, Dongjie; Wu, Xiaolei; Qiu, Xueqing; Chang, Yaqi; Lou, Hongming

    2014-03-01

    Alkali lignin (AL) was employed as raw materials in the present study. Sulfomethylation was conducted to improve the solubility of AL, while sulfomethylated alkali lignin (SAL) was further polymerized by horseradish peroxidase (HRP). HRP modification caused a significant increase in molecular weight of SAL which was over 20 times. It was also found to increase the amount of sulfonic and carboxyl groups while decrease the amount of phenolic and methoxyl groups in SAL. The adsorption quantity of self-assembled SAL film was improved after HRP modification. Sulfonation and HRP modification were mutually promoted. The polymerization reactivity of SAL in HRP modification was increased with its sulfonation degree. Meanwhile, HRP modification facilitated SAL's radical-sulfonation reaction.

  16. Alkali elements in the Earth's core: Evidence from enstatite meteorites

    NASA Technical Reports Server (NTRS)

    Lodders, K.

    1995-01-01

    The abundances of alkali elements in the Earth's core are predicted by assuming that accretion of the Earth started from material similar in composition to enstatite chondrites and that enstatite achondrites (aubrites) provide a natural laboratory to study core-mantle differentiation under extremely reducing conditions. If core formation on the aubrite parent body is comparable with core formation on the early Earth, it is found that 2600 (+/- 1000) ppm Na, 550 (+/- 260) ppm K, 3.4 (+/- 2.1) ppm Rb, and 0.31 (+/- 0.24) ppm Cs can reside in the Earth's core. The alkali-element abundances are consistent with those predicted by independent estimates based on nebula condensation calculations and heat flow data.

  17. Properties and Performance of Alkali-Activated Concrete

    NASA Astrophysics Data System (ADS)

    Thomas, Robert J.

    Alkali-activated concrete (AAC) made with industrial byproducts as the sole binder is rapidly emerging as a sustainable alternative to ordinary portland cement concrete (PCC). Despite its exemplary mechanical performance and durability, there remain several barriers to widespread commercialization of AAC. This dissertation addresses several of these barriers. Mathematical models are proposed which efficiently and accurately predict the compressive strength of AAC as a function of activator composition, binder type, and curing condition. The relationships between compressive strength and other mechanical properties (i.e., tensile strength and modulus of elasticity) are discussed, as are stress-strain relationships. Several aspects related to the durability of AAC are also discussed, including dimensional stability under drying conditions, alkali-silica reactivity, and chloride permeability. The results of these experimental investigations are disseminated in the context of real-world applicability.

  18. Alkali halide microstructured optical fiber for X-ray detection

    SciTech Connect

    DeHaven, S. L. E-mail: russel.a.wincheski@nasa.gov; Wincheski, R. A. E-mail: russel.a.wincheski@nasa.gov; Albin, S.

    2015-03-31

    Microstructured optical fibers containing alkali halide scintillation materials of CsI(Na), CsI(Tl), and NaI(Tl) are presented. The scintillation materials are grown inside the microstructured fibers using a modified Bridgman-Stockbarger technique. The x-ray photon counts of these fibers, with and without an aluminum film coating are compared to the output of a collimated CdTe solid state detector over an energy range from 10 to 40 keV. The photon count results show significant variations in the fiber output based on the materials. The alkali halide fiber output can exceed that of the CdTe detector, dependent upon photon counter efficiency and fiber configuration. The results and associated materials difference are discussed.

  19. Alkali metal poisoning of a CeO2-WO3 catalyst used in the selective catalytic reduction of NOx with NH3: an experimental and theoretical study.

    PubMed

    Peng, Yue; Li, Junhua; Chen, Liang; Chen, Jinghuan; Han, Jian; Zhang, He; Han, Wei

    2012-03-06

    The alkali metal-induced deactivation of a novel CeO(2)-WO(3) (CeW) catalyst used for selective catalytic reduction (SCR) was investigated. The CeW catalyst could resist greater amounts of alkali metals than V(2)O(5)-WO(3)/TiO(2). At the same molar concentration, the K-poisoned catalyst exhibited a greater loss in activity compared with the Na-poisoned catalyst below 200 °C. A combination of experimental and theoretical methods, including NH(3)-TPD, DRIFTS, H(2)-TPR, and density functional theory (DFT) calculations, were used to elucidate the mechanism of the alkali metal deactivation of the CeW catalyst in SCR reaction. Experiments results indicated that decreases in the reduction activity and the quantity of Brønsted acid sites rather than the acid strength were responsible for the catalyst deactivation. The DFT calculations revealed that Na and K could easily adsorb on the CeW (110) surface and that the surface oxygen could migrate to cover the active tungsten, and then inhibit the SCR of NO(x) with ammonia. Hot water washing is a convenient and effective method to regenerate alkali metal-poisoned CeW catalysts, and the catalytic activity could be recovered 90% of the fresh catalyst.

  20. Membrane Transport Behavior and the Lability of Chloride on Polyphosphazenes Bearing Bulky Substituents

    SciTech Connect

    Frederick F. Stewart; John R. Klaehn; Christopher J. Orme

    2007-08-01

    Polyphosphazenes are an intriguing class of inorganic polymers where much of their functionality is derived from pendant groups attached to phosphorus. The backbone of the polymer consists of alternating phosphorus and nitrogen atoms where the bonding is conventionally drawn as alternating double and single bonds. Orbital nodes are located at each phosphorus atom resulting in electron delocalization between phosphorus atoms, but not through them. Thus, the polymer backbone has a high degree of flexibility where halogens or other leaving groups can be effectively displaced with nucleophiles. In this paper, the first known example of a polyphosphazene with large quantities of non-labile chloride substituents induced by neighboring group steric effects will be discussed. This example is the result of the substitution of poly[bis-chlorophosphazene] with the sodium salt of 3,5-di-tert-butylphenol where only 60% of the chlorines were displaced. This contrasts with the 100% substitution observed with other phenols (phenol, 4-tert-butylphenol, 3-methylphenol, etc.).

  1. Labile iron pool and ferritin content in developing rat brain gamma-irradiated in utero.

    PubMed

    Robello, Elizabeth; Galatro, Andrea; Puntarulo, Susana

    2009-05-01

    This study was aimed to assess the content of total Fe, Ferritin (Ft) and labile Fe pool (LIP) in developing rat brain exposed in utero to 1 Gy of gamma-irradiation. A significant increase (2.3-fold) in the total Fe content of the fetal rat brain irradiated in utero was observed from 1 to 4h post-irradiation, as compared to the content in non-irradiated brain. Ft was analyzed by immunoblotting. The Ft protein was composed by 20 kDa subunits. According to the analysis of the band density in the Western blot, the Ft content decreased by 77+/-15% 2h after gamma-irradiation, as compared to the values in non-irradiated samples. The effect of gamma-irradiation on the LIP was studied by both electron paramagnetic resonance (EPR) and by a fluorescence technique employing calcein (CA). A reduction on the LIP was detected at 2h post-irradiation, independently of the methodology employed for the assay. Since NO content increased in the same time frame of LIP decreasing, a protective role for NO is suggested in fetal rat brain exposed to gamma-irradiation. The data presented in this work are the first experimental evidence suggesting that, as part of the network of the cellular response to limit irradiation-dependent injury, a complex interaction between Fe and NO could be triggered.

  2. Stabilized liquid membrane device (SLMD) for the passive, integrative sampling of labile metals in water

    USGS Publications Warehouse

    Brumbaugh, W.G.; Petty, J.D.; Huckins, J.N.; Manahan, S.E.

    2002-01-01

    A stabilized liquid membrane device (SLMD) is described for potential use as an in situ, passive, integrative sampler for cadmium (Cd), cobalt (Co), copper (Cu), nickel (Ni), lead (Pb), and zinc (Zn) in natural waters. The SLMD (patent pending) consists of a 2.5-cm-wide by 15-cm-long strip of low-density polyethylene (LDPE) layflat tubing containing 1 mL of an equal mixture (v/v) of oleic acid (cis-9-octadecenoic acid) and EMO-8Q (7-[4-ethyl-1-methyloctyl]-8-quinolinol). The reagent mixture continuously diffuses to the exterior surface of the LDPE membrane, and provides for sequestration of several divalent metals for up to several weeks. Depending on sampler configuration, concentration factors of several thousand can be realized for these metal ions after just a few days. In addition to in situ deployment, the SLMD may be useful for laboratory determination of labile metal species in grab samples. Methods for minimizing the effects of water flow on the sampling rate are currently under investigation.

  3. Sample storage-induced changes in the quantity and quality of soil labile organic carbon

    PubMed Central

    Sun, Shou-Qin; Cai, Hui-Ying; Chang, Scott X.; Bhatti, Jagtar S.

    2015-01-01

    Effects of sample storage methods on the quantity and quality of labile soil organic carbon are not fully understood even though their effects on basic soil properties have been extensively studied. We studied the effects of air-drying and frozen storage on cold and hot water soluble organic carbon (WSOC). Cold- and hot-WSOC in air-dried and frozen-stored soils were linearly correlated with those in fresh soils, indicating that storage proportionally altered the extractability of soil organic carbon. Air-drying but not frozen storage increased the concentrations of cold-WSOC and carbohydrate in cold-WSOC, while both increased polyphenol concentrations. In contrast, only polyphenol concentration in hot-WSOC was increased by air-drying and frozen storage, suggesting that hot-WSOC was less affected by sample storage. The biodegradability of cold- but not hot-WSOC was increased by air-drying, while both air-drying and frozen storage increased humification index and changed specific UV absorbance of both cold- and hot-WSOC, indicating shifts in the quality of soil WSOC. Our results suggest that storage methods affect the quantity and quality of WSOC but not comparisons between samples, frozen storage is better than air-drying if samples have to be stored, and storage should be avoided whenever possible when studying the quantity and quality of both cold- and hot-WSOC. PMID:26617054

  4. Labile Zn ions on octacalcium phosphate-derived Zn-containing hydroxyapatite surfaces

    NASA Astrophysics Data System (ADS)

    Honda, Yoshitomo; Anada, Takahisa; Morimoto, Shinji; Suzuki, Osamu

    2013-05-01

    We previously synthesized and characterized zinc-containing octacalcium phosphate (OCP) and its hydrolyzed Ca-deficient hydroxyapatite (HA). In the present report, we attempted to define the state of Zn in the OCP-derived Zn-calcium phosphates (CaPs) in relation to the presence of specific amino acids. Zn-containing OCPs were prepared in solutions that included Zn ions up to a concentration of 3.5 mM, and their hydrolyzates [hydrolyzed (hy)-Zn-CaP] were obtained in hot water. The materials were characterized by x-ray diffraction and scanning electron microscopy. The concentration of Ca and Zn ions at room temperature was determined by analyzing the supernatant after incubating the materials in α-minimal essential medium (α-MEM) and HEPES buffer including cysteine, histidine, lysine, aspartic acid, and glutamic acid. Zn ions were more dissolved in α-MEM than HEPES buffer in the absence of amino acids. The inclusion of the amino acids enhanced Zn dissolution by several hundred fold, even in HEPES buffer. Among the amino acids, both cysteine and histidine enhanced the release of Zn. The effect was particularly remarkable with cysteine even in the presence of the other amino acids tested. These results indicate that Zn ions are present as a surface labile pool, which tends to be preferentially desorbed by cysteine, a ubiquitous molecule present in serum.

  5. Labile male morphology and intraspecific male polymorphism in the Philotrypesis fig wasps.

    PubMed

    Jousselin, Emmanuelle; van Noort, Simon; Greeff, Jaco M

    2004-12-01

    We investigate the evolution of male morphology in the fig wasps belonging to the genus Philotrypesis (Chalcidoidea, Sycorectinae). We first reconstruct the phylogenetic relationships of Philotrypesis associated with African figs using nuclear and mitochondrial DNA. We then determine male morphotypes in the species included in our phylogeny and show that intraspecific polymorphism is common. Most species present two types of males and some species have up to three types. These morphotypes are believed to represent alternative mating tactics: some males show morphological adaptations to fighting, others are winged dispersers and others are small sneakers. Mapping out these variations onto our phylogeny reveals that the combination of morphs changes randomly along the branches of the tree. Both parsimony and likelihood approaches indicate that there has been at least one transition from dimorphism to trimorphism, several gains and losses of the small morph and two independent acquisitions of the winged morph. Using maximum likelihood analyses of character evolution, we estimate transition rates for each morph and show that the evolution of each type of morph are not correlated and that forward and backward transition rates are not significantly different. Our results altogether suggest that male morphology is evolutionary labile, it responds quickly to selection imposed by the mating environment. This study, also suggests that seemingly complex phenotypes, such as winged males, can evolve several times and can even be recreated after having been lost.

  6. Uncaria tomentosa (Willd. ex. Roem. & Schult.) DC. and Eucalyptus globulus Labill. interactions when administered with diazepam.

    PubMed

    Quílez, A M; Saenz, M T; García, M D

    2012-03-01

    The safety of natural drugs is defined by their side effects and toxicity as well as any interactions that may occur if taken together with other drugs. In particular, it is essential to identify synergies, antagonisms and other types of interference with other drugs so that the correct choice can be made from the range of phytomedicines available. The aim of this work was to investigate changes in the pharmacological effect of diazepam (2 mg/kg) on the CNS when administered together with a medicinal plant: Eucalyptus globulus Labill. (eucalyptus 6 mg/kg and 3.25 mg/kg) or Uncaria tomentosa (Willd. ex Roem. & Schult). DC. (cat's claw, 7.14 mg/kg and 3.54 mg/kg). Various different psychopharmacological effects were evaluated through assessing exploratory behavior, muscle relaxation and spontaneous motor activity. Both phytodrugs interacted with the benzodiazepine. Eucalyptus had an inhibitory effect at both doses and could be useful at the highest dose in cases where the desired effect of the depressant is moderate anxiolytic activity without marked muscle relaxation. Cat's claw, at both doses, enhanced the action of diazepam on spontaneous motor activity and, at the lowest dose, exploratory ability. These herbal drugs could be useful for their antiinflammatory activity in musculoskeletal pathologies treated with benzodiazepines.

  7. Labile cochlear tuning in the mustached bat. I. Concomitant shifts in biosonar emission frequency.

    PubMed

    Huffman, R F; Henson, O W

    1993-01-01

    The cochlea of the mustached bat (Pteronotus parnellii) has sharp tuning characteristics and pronounced resonance within a narrow band near the second harmonic, constant frequency (CF2) component of the animal's biosonar signals. That fine frequency discrimination occurs within this narrow band is evident from Doppler-shift compensation, whereby bats in flight lower the frequency of emitted CF2s to maintain returning echoes within this band. This study examined various factors capable of producing shifts in both the cochlear resonance frequency (CRF) and CF2s emitted by stationary bats and bats actively Doppler-shift compensating on a pendulum. Each of three experimental factors shifted the CRF in a reversible manner. Changes in body temperature produced an average CRF shift of 39 +/- 18 Hz/degrees C. The CRF increased with flight by 150 +/- 100 Hz and returned to baseline values within 10 min after flight. Contralateral sound exposure produced smaller (100 +/- 20 Hz), rapid shifts in the CRF, suggesting that a mechanism different from the temperature- and flight-related shifts was involved. Changes in the CRF induced by temperature and flight were accompanied by shifts in the emitted CF2 of stationary and moving bats. Coupled with a companion study of associated shifts in neural tuning, the concomitant changes in CRF and CF2 provide evidence of cochlear tuning lability in the mustached bat.

  8. Sample storage-induced changes in the quantity and quality of soil labile organic carbon

    NASA Astrophysics Data System (ADS)

    Sun, Shou-Qin; Cai, Hui-Ying; Chang, Scott X.; Bhatti, Jagtar S.

    2015-11-01

    Effects of sample storage methods on the quantity and quality of labile soil organic carbon are not fully understood even though their effects on basic soil properties have been extensively studied. We studied the effects of air-drying and frozen storage on cold and hot water soluble organic carbon (WSOC). Cold- and hot-WSOC in air-dried and frozen-stored soils were linearly correlated with those in fresh soils, indicating that storage proportionally altered the extractability of soil organic carbon. Air-drying but not frozen storage increased the concentrations of cold-WSOC and carbohydrate in cold-WSOC, while both increased polyphenol concentrations. In contrast, only polyphenol concentration in hot-WSOC was increased by air-drying and frozen storage, suggesting that hot-WSOC was less affected by sample storage. The biodegradability of cold- but not hot-WSOC was increased by air-drying, while both air-drying and frozen storage increased humification index and changed specific UV absorbance of both cold- and hot-WSOC, indicating shifts in the quality of soil WSOC. Our results suggest that storage methods affect the quantity and quality of WSOC but not comparisons between samples, frozen storage is better than air-drying if samples have to be stored, and storage should be avoided whenever possible when studying the quantity and quality of both cold- and hot-WSOC.

  9. Sample storage-induced changes in the quantity and quality of soil labile organic carbon.

    PubMed

    Sun, Shou-Qin; Cai, Hui-Ying; Chang, Scott X; Bhatti, Jagtar S

    2015-11-30

    Effects of sample storage methods on the quantity and quality of labile soil organic carbon are not fully understood even though their effects on basic soil properties have been extensively studied. We studied the effects of air-drying and frozen storage on cold and hot water soluble organic carbon (WSOC). Cold- and hot-WSOC in air-dried and frozen-stored soils were linearly correlated with those in fresh soils, indicating that storage proportionally altered the extractability of soil organic carbon. Air-drying but not frozen storage increased the concentrations of cold-WSOC and carbohydrate in cold-WSOC, while both increased polyphenol concentrations. In contrast, only polyphenol concentration in hot-WSOC was increased by air-drying and frozen storage, suggesting that hot-WSOC was less affected by sample storage. The biodegradability of cold- but not hot-WSOC was increased by air-drying, while both air-drying and frozen storage increased humification index and changed specific UV absorbance of both cold- and hot-WSOC, indicating shifts in the quality of soil WSOC. Our results suggest that storage methods affect the quantity and quality of WSOC but not comparisons between samples, frozen storage is better than air-drying if samples have to be stored, and storage should be avoided whenever possible when studying the quantity and quality of both cold- and hot-WSOC.

  10. Soft antimicrobial agents: synthesis and activity of labile environmentally friendly long chain quaternary ammonium compounds.

    PubMed

    Thorsteinsson, Thorsteinn; Másson, Már; Kristinsson, Karl G; Hjálmarsdóttir, Martha A; Hilmarsson, Hilmar; Loftsson, Thorsteinn

    2003-09-11

    A series of soft quaternary ammonium antimicrobial agents, which are analogues to currently used quaternary ammonium preservatives such as cetyl pyridinium chloride and benzalkonium chloride, were synthesized. These soft analogues consist of long alkyl chain connected to a polar headgroup via chemically labile spacer group. They are characterized by facile nonenzymatic and enzymatic degradation to form their original nontoxic building blocks. However, their chemical stability has to be adequate in order for them to have antimicrobial effects. Stability studies and antibacterial and antiviral activity measurements revealed relationship between activity, lipophilicity, and stability. Their minimum inhibitory concentration (MIC) was as low as 1 microg/mL, and their viral reduction was in some cases greater than 6.7 log. The structure-activity studies demonstrate that the bioactive compounds (i.e., MIC for Gram-positive bacteria of <10 microg/mL) have an alkyl chain length between 12 and 18 carbon atoms, with a polar headgroup preferably of a small quaternary ammonium group, and their acquired inactivation half-life must be greater than 3 h at 60 degrees C.

  11. Effects of physical constraints on the lability of POM during summer in the Ross Sea

    NASA Astrophysics Data System (ADS)

    Misic, Cristina; Covazzi Harriague, Anabella; Mangoni, Olga; Aulicino, Giuseppe; Castagno, Pasquale; Cotroneo, Yuri

    2017-02-01

    The 0-200 m surface layer of the Ross Sea was studied during summer 2014 to investigate the lability of the particulate organic matter (POM) in response to physical parameters. With the use of satellite information, we selected three zones, characterised by different physical setting: a northern offshore area, crossing the summer-polynya area of the Ross Sea (hereafter called ROME 1), a more coastal area next to the Terra Nova Bay polynya (ROME 2); a southern offshore area, towards the Ross Ice Shelf (ROME 3). Ice-maps showed that the seasonal ice retreat had already occurred in early December for most of the stations. Statistical analysis of the quantitative and qualitative characteristics of the POM pointed to significant differences between the stations, especially in the upper mixed layer (UML). A comparison with previous studies showed that the localised pulses of POM accumulation in the UML were similar to those recorded at the highly productive marginal ice zones, providing notable trophic support to the ecosystem. The UML, although rather thin and easily subjected to alterations, confirmed its pivotal role in the ecosystem dynamics. A POM quality favourable to consumers was highlighted at several stations in ROME 1 and ROME 3. Reduced trophic support was, instead, found in ROME 2. Limited POM consumption where deep-water formation takes place would increase the POM role in the transfer of C to the depths.

  12. Anatomical variation in Cactaceae and relatives: Trait lability and evolutionary innovation.

    PubMed

    Ogburn, R Matthew; Edwards, Erika J

    2009-02-01

    The cacti have undergone extensive specialization in their evolutionary history, providing an excellent system in which to address large-scale questions of morphological and physiological adaptation. Recent molecular phylogenetic studies suggest that (1) Pereskia, the leafy genus long interpreted as the sister group of all other cacti, is likely paraphyletic, and (2) Cactaceae are nested within a paraphyletic Portulacaceae as a member of the "ACPT" clade (Anacampseroteae, Cactaceae, Portulaca, and Talinum). We collected new data on the vegetative anatomy of the ACPT clade and relatives to evaluate whether patterns in the distributions of traits may provide insight into early events in the evolutionary transition to the cactus life form. Many traits had high levels of homoplasy and were mostly equivocal with regard to infraclade relationships of ACPT, although several characters do lend further support to a paraphyletic Pereskia. These include a thick stem cuticle, prominent stem mucilage cells, and hypodermal calcium oxalate druses, all of which are likely to be important traits for stem water storage and photosynthesis. We hypothesize that high lability of many putative "precursor" traits may have been critical in generating the organismal context necessary for the evolution of an efficient and integrated photosynthetic stem.

  13. Facile synthesis of acid-labile polymers with pendent ortho esters.

    PubMed

    Cheng, Jing; Ji, Ran; Gao, Shi-Juan; Du, Fu-Sheng; Li, Zi-Chen

    2012-01-09

    This work presents a facile approach for preparation of acid-labile and biocompatible polymers with pendent cyclic ortho esters, which is based on the efficient and mild reactions between cyclic ketene acetal (CKA) and hydroxyl groups. Three CKAs, 2-ethylidene-1,3-dioxane (EDO), 2-ethylidene-1,3-dioxolane (EDL), and 2-ethylidene-4- methyl-1,3-dioxolane (EMD) were prepared from the corresponding cyclic vinyl acetals by catalytic isomerization of the double bond. The reaction of CKAs with different alcohols and diols was examined using trace of p-toluenesulfonic acid as a catalyst. For the monohydroxyl alcohols, cyclic ortho esters were formed by simple addition of the hydroxyl group toward CKAs with ethanol showing a much greater reactivity than iso-propanol. When 1,2- or 1,3-diols were used to react with the CKAs, we observed the isomerized cyclic ortho esters besides the simple addition products. Biocompatible polyols, that is, poly(2-hydroxyethyl acrylate) (PHEA) and poly(vinyl alcohol) (PVA) were then modified with CKAs, and the degree of substitution of the pendent ortho esters can be easily tuned by changing feed ratio. Both the small molecule ortho esters and the CKA-modified polymers demonstrate the pH-dependent hydrolysis profiles, which depend also on the chemical structure of the ortho esters as well as the polymer hydrophobicity.

  14. Protein kinase C-δ isoform mediates lysosome labilization in DNA damage-induced apoptosis

    PubMed Central

    PARENT, NICOLAS; SCHERER, MAX; LIEBISCH, GERHARD; SCHMITZ, GERD; BERTRAND, RICHARD

    2013-01-01

    A lysosomal pathway, characterized by the partial rupture or labilization of lysosomal membranes (LLM) and cathepsin release into the cytosol, is evoked during the early events of 20-S-camptothecin lactone (CPT)-induced apoptosis in human cancer cells, including human histiocytic lymphoma U-937 cells. These lysosomal events begin rapidly and simultaneously with mitochondrial permeabilization and caspase activation within 3 h after drug treatment. Recently, in a comparative proteomics analysis performed on highly-enriched lysosomal extracts, we identified proteins whose translocation to lysosomes correlated with LLM induction after CPT treatment, including protein kinase C-δ (PKC-δ). In this study, we show that the PKC-δ translocation to lysosomes is required for LLM, as silencing its expression with RNA interference or suppressing its activity with the inhibitor, rottlerin, prevents CPT-induced LLM. PKC-δ translocation to lysosomes is associated with lysosomal acidic sphingomyelinase (ASM) phosphorylation and activation, which in turn leads to an increase in ceramide (CER) content in lysosomes. The accumulation of endogenous CER in lysosomes is a critical event for CPT-induced LLM as suppressing PKC-δ or ASM activity reduces both the CPT-mediated CER generation in lysosomes and CPT-induced LLM. These findings reveal a novel mechanism by which PKC-δ mediates ASM phosphorylation/activation and CER accumulation in lysosomes in CPT-induced LLM, rapidly activating the lysosomal pathway of apoptosis after CPT treatment. PMID:21174057

  15. Expression of Escherichia coli heat-labile enterotoxin B subunit (LTB) in Saccharomyces cerevisiae.

    PubMed

    Rezaee, Mohammad Ahangarz; Rezaee, Abbas; Moazzeni, Seyed Mohammad; Salmanian, Ali Hatef; Yasuda, Yoko; Tochikubo, Kunio; Pirayeh, Shahin Najar; Arzanlou, Mohsen

    2005-08-01

    Heat-labile enterotoxin B subunit (LTB) of enterotoxigenic Escherichia coli (ETEC) is both a strong mucosal adjuvant and immunogen. It is a subunit vaccine candidate to be used against ETEC-induced diarrhea. It has already been expressed in several bacterial and plant systems. In order to construct yeast expressing vector for the LTB protein, the eltB gene encoding LTB was amplified from a human origin enterotoxigenic E. coli DNA by PCR. The expression plasmid pLTB83 was constructed by inserting the eltB gene into the pYES2 shuttle vector immediately downstream of the GAL1 promoter. The recombinant vector was transformed into S. cerevisiae and was then induced by galactose. The LTB protein was detected in the total soluble protein of the yeast by SDS-PAGE analysis. Quantitative ELISA showed that the maximum amount of LTB protein expressed in the yeast was approximately 1.9% of the total soluble protein. Immunoblotting analysis showed the yeast-derived LTB protein was antigenically indistinguishable from bacterial LTB protein. Since the whole-recombinant yeast has been introduced as a new vaccine formulation the expression of LTB in S. cerevisiae can offer an inexpensive yet effective strategy to protect against ETEC, especially in developing countries where it is needed most.

  16. Development and bioorthogonal activation of palladium-labile prodrugs of gemcitabine.

    PubMed

    Weiss, Jason T; Dawson, John C; Fraser, Craig; Rybski, Witold; Torres-Sánchez, Carmen; Bradley, Mark; Patton, E Elizabeth; Carragher, Neil O; Unciti-Broceta, Asier

    2014-06-26

    Bioorthogonal chemistry has become one of the main driving forces in current chemical biology, inspiring the search for novel biocompatible chemospecific reactions for the past decade. Alongside the well-established labeling strategies that originated the bioorthogonal paradigm, we have recently proposed the use of heterogeneous palladium chemistry and bioorthogonal Pd(0)-labile prodrugs to develop spatially targeted therapies. Herein, we report the generation of biologically inert precursors of cytotoxic gemcitabine by introducing Pd(0)-cleavable groups in positions that are mechanistically relevant for gemcitabine's pharmacological activity. Cell viability studies in pancreatic cancer cells showed that carbamate functionalization of the 4-amino group of gemcitabine significantly reduced (>23-fold) the prodrugs' cytotoxicity. The N-propargyloxycarbonyl (N-Poc) promoiety displayed the highest sensitivity to heterogeneous palladium catalysis under biocompatible conditions, with a reaction half-life of less than 6 h. Zebrafish studies with allyl, propargyl, and benzyl carbamate-protected rhodamines confirmed N-Poc as the most suitable masking group for implementing in vivo bioorthogonal organometallic chemistry.

  17. Antimicrobial activity of globulol isolated from the fruits of Eucalyptus globulus Labill.

    PubMed

    Tan, Manliang; Zhou, Ligang; Huang, Yongfu; Wang, Ye; Hao, Xiaojiang; Wang, Jingguo

    2008-05-10

    An antimicrobial sesquiterpene was separated by bioassay-guided isolation from the petroleum ether fraction of the ethanol crude extract of Eucalyptus globulus Labill (Myrtaceae) fruits, and was identified as globulol by physicochemical properties and spectroscopic analysis. Mycelial growth method revealed that the median effective inhibitory concentration (IC50) values of globulol on Alternaria solani, Fusarium oxysporum f.sp. niverum, F. graminearum, Rhizoctonia solani and Venturia pirina were 47.1 microg mL(-1), 114.3 microg mL(-1), 53.4 microg mL(-1), 56.9 microg mL(-1), 32.1 microg mL(-1) and 21.8 microg mL(-1), respectively. MTT-colorimetric assay revealed that IC50 values of globulol on Xanthomonas vesicatoria and Bacillus subtilis were 158.0 microg mL(-1) and 737.2 microg mL(-1), respectively. The results indicated that globulol could be a main antimicrobial compound in the ethanol crude extract of E. globulus fruits.

  18. Diffusive gradients in thin films measurement of sulfur stable isotope variations in labile soil sulfate.

    PubMed

    Hanousek, Ondrej; Santner, Jakob; Mason, Sean; Berger, Torsten W; Wenzel, Walter W; Prohaska, Thomas

    2016-11-01

    A diffusive gradient in thin films (DGT) technique, based on a strongly basic anion exchange resin (Amberlite IRA-400), was successfully tested for (34)S/(32)S analysis in labile soil sulfate. Separation of matrix elements (Na, K, and Ca) that potentially cause non-spectral interferences in (34)S/(32)S analysis by MC ICP-MS (multi-collector inductively coupled plasma-mass spectrometry) during sampling of sulfate was demonstrated. No isotopic fractionation caused by diffusion or elution of sulfate was observed below a resin gel disc loading of ≤79 μg S. Above this threshold, fractionation towards (34)S was observed. The method was applied to 11 different topsoils and one mineral soil profile (0-100 cm depth) and compared with soil sulfate extraction by water. The S amount and isotopic ratio in DGT-S and water-extractable sulfate correlated significantly (r (2) = 0.89 and r (2) = 0.74 for the 11 topsoils, respectively). The systematically lower (34)S/(32)S isotope ratios of the DGT-S were ascribed to mineralization of organic S.

  19. Effect of pH on Metal Lability in Drinking Water Treatment Residuals.

    PubMed

    Wang, Changhui; Yuan, Nannan; Pei, Yuansheng

    2014-01-01

    Drinking water treatment residuals (WTRs), by-products generated during treatment of drinking water, can be reused as environmental amendments to remediate contamination. However, this beneficial reuse may be hampered by the potential release of toxic contaminants (e.g., metals) in the WTRs. In present study, batch tests and then fractionation, in vitro digestion, and the toxicity characteristic leaching procedure were used to investigate the release and extractability of metals in the Fe/Al hydroxides comprised WTRs under differing pH. The results demonstrated that significant release from WTRs for Ba, Be, Ca, Cd, Co, Cr, Fe, Mg, Mn, Pb, Sr, and Zn occurred under low pH (acid condition); for As, Mo, and V under high pH (alkaline condition); and for Al, Cu, and Ni under both conditions. In comparison, most metals in the WTRs were more easily released under low pH, but the release was stable at a relatively low level between pH 6 and 9, especially under alkaline conditions. Further analysis indicated that the chemical extractability and bioaccessibility of many metals was found to increase in the WTRs after being leached, even though the leached WTRs could still be considered nonhazardous. These results demonstrated that pH had a substantial effect on the lability of metals in WTRs. Overall, caution should be used when considering pH conditions during WTRs reuse to avoid potential metal pollution.

  20. Heat-labile enterotoxin of Escherichia coli promotes intestinal colonization of Salmonella enterica.

    PubMed

    Verbrugghe, Elin; Van Parys, Alexander; Leyman, Bregje; Boyen, Filip; Arnouts, Sven; Lundberg, Urban; Ducatelle, Richard; Van den Broeck, Wim; Yekta, Maryam Atef; Cox, Eric; Haesebrouck, Freddy; Pasmans, Frank

    2015-12-01

    Enterotoxigenic Escherichia coli (ETEC) is an important cause of infantile and travellers' diarrhoea, which poses a serious health burden, especially in developing countries. In addition, ETEC bacteria are a major cause of illness and death in neonatal and recently weaned pigs. The production of a heat-labile enterotoxin (LT) promotes the colonization and pathogenicity of ETEC and may exacerbate co-infections with other enteric pathogens such as Salmonella enterica. We showed that the intraintestinal presence of LT dramatically increased the intestinal Salmonella Typhimurium load in experimentally inoculated pigs. This could not be explained by direct alteration of the invasion or survival capacity of Salmonella in enterocytes, in vitro. However, we demonstrated that LT affects the enteric mucus layer composition in a mucus-secreting goblet cell line by significantly decreasing the expression of mucin 4. The current results show that LT alters the intestinal mucus composition and aggravates a Salmonella Typhimurium infection, which may result in the exacerbation of the diarrhoeal illness.

  1. Inhibition of Escherichia coli heat-labile enterotoxin-induced diarrhea by Chaenomeles speciosa.

    PubMed

    Chen, Jaw-Chyun; Chang, Yuan-Shiun; Wu, Shih-Lu; Chao, De-Cheng; Chang, Chih-Shiang; Li, Chia-Cheng; Ho, Tin-Yun; Hsiang, Chien-Yun

    2007-09-05

    Enterotoxigenic Escherichia coli (ETEC) is responsible for millions of deaths in developing countries. Heat-labile enterotoxin (LT), the virulence factor of ETEC, induces diarrhea by initially binding to the G(M1) on the surface of intestinal epithelial cells and consequently leading to the massive loss of fluid and ions from cells. Fruit of Chaenomeles (FC), the dried fruit of Chaenomeles speciosa, has been used for diarrhea in China. However, the anti-diarrheal mechanism of FC is still unclear. In this study, we demonstrated that FC extract (FCE) inhibited the LT-induced diarrhea in mice by blocking the binding of the B subunit of LT (LTB) to G(M1). The ethyl acetate (EA) soluble fraction was the most active fraction of FC that significantly abolished the LTB and G(M1) interaction. Furthermore, the oleanolic acid, ursolic acid, and betulinic acid from EA fraction, blocked the toxin binding effects, resulting in the suppression of LT-induced diarrhea. Moreover, by docking techniques, these compounds fitted LTB well via hydrogen bonds and hydrophobic contacts with amino acid residues of LTB. In conclusion, our findings suggested that oleanolic acid, ursolic acid, and betulinic acid were the active constituents from FC and might be considered as lead therapeutic agents in the treatment of LT-induced diarrhea.

  2. Determination of labile copper, cobalt, and chromium in textile mill wastewater

    SciTech Connect

    Crain, J.S.; Essling, A.M.; Kiely, J.T.

    1997-01-01

    Copper, chromium, and cobalt species present in filtered wastewater effluent were separated by cation exchange and reverse phase chromatography. Three sample fractions were obtained: one containing metal cations (i.e., trivalent Cr, divalent Cu, and divalent Co), one containing organic species (including metallized dyes), and one containing other unretained species. The metal content of each fraction was determined by inductively coupled plasma atomic emission spectroscopy (ICP-AES). The sum of the corrected data was compared to the metal content of a filtered effluent aliquot digested totally with fuming sulfuric acid. Other aliquots of the filtered effluent were spiked with the metals of interest and digested to confirm chemical yield and accuracy. Method detection limits were consistently below 20 {mu}g L{sup -1} for Cu, 30 {mu}g L{sup -1} for Co, and 10 {mu}g L{sup -1} for Cr. Spike recoveries for undifferentiated Cu and Cr were statistically indistinguishable from unity; although Co spike recoveries were slightly low ({approximately}95%), its chemical yield was 98%. Copper retention on the sodium sulfonate cation exchange resin was closely correlated with the [EDTA]/[Cu] ratio, suggesting that metals retained upon the cation exchange column were assignable to labile metal species; however, mass balances for all three elements, though reasonable ({approximately}90%), were significantly different from unity. Mechanical factors may have contributed to the material loss, but other data suggest that some metal species reacted irreversibly with the reverse phase column. 3 refs., 2 figs., 4 tabs.

  3. (abstract) Experimental and Modeling Studies of the Exchange Current at the Alkali Beta'-Alumina/Porous Electrode/Alkali Metal Vapor Three Phase Boundary

    NASA Technical Reports Server (NTRS)

    Williams, R. M.; Jeffries-Nakamura, B.; Ryan, M. A.; Underwood, M. L.; O'Connor, D.; Kikkert, S.

    1993-01-01

    The microscopic mechanism of the alkali ion-electron recombination reaction at the three phase boundary zone formed by a porous metal electrode in the alkali vapor on the surface of an alkali beta'-alumina solid electrolyte (BASE) ceramic has been studied by comparison of the expected rates for the three simplest reaction mechanisms with known temperature dependent rate data; and the physical parameters of typical porous metal electrode/BASE/alkali metal vapor reaction zones. The three simplest reactions are tunneling of electrons from the alkali coated electrode to a surface bound alkali metal ion; emission of an electron from the electrode with subsequent capture by a surface bound alkali metal ion; and thermal emission of an alkali cation from the BASE and its capture on the porous metal electrode surface where it may recombine with an electron. Only the first reaction adequately accounts for both the high observed rate and its temperature dependence. New results include crude modeling of simple, one step, three phase, solid/solid/gas electrochemical reaction.

  4. Solid Electrolytes: Alkali-Ion Transport in Skeleton Structures

    DTIC Science & Technology

    1976-06-30

    side if necessary and identify by block number) solid electrolytes alkali -ion transport sodium -sulfur batteries fast -ion transport O ABSTRACT...molten Na 2 S4 for 10 days at 400’C indicated chemical stability, similar testing i-1 molten sodium was initiated, and it has been established that...tests under dynamic conditions are necessary before long-term stability of tile material can be established. Tests for stability in molten sodium have

  5. Optical Properties of Tm(3+) Ions in Alkali Germanate Glass

    NASA Technical Reports Server (NTRS)

    Walsh, Brian M.; Barnes, Norman P.; Reichle, Donald J.; Jiang, Shibin

    2006-01-01

    Tm-doped alkali germanate glass is investigated for use as a laser material. Spectroscopic investigations of bulk Tm-doped germanate glass are reported for the absorption, emission and luminescence decay. Tm:germanate shows promise as a fiber laser when pumped with 0.792 m diodes because of low phonon energies. Spectroscopic analysis indicates low nonradiative quenching and pulsed laser performance studies confirm this prediction by showing a quantum efficiency of 1.69.

  6. Transversely diode-pumped alkali metal vapour laser

    SciTech Connect

    Parkhomenko, A I; Shalagin, A M

    2015-09-30

    We have studied theoretically the operation of a transversely diode-pumped alkali metal vapour laser. For the case of high-intensity laser radiation, we have obtained an analytical solution to a complex system of differential equations describing the laser. This solution allows one to exhaustively determine all the energy characteristics of the laser and to find optimal parameters of the working medium and pump radiation (temperature, buffer gas pressure, and intensity and width of the pump spectrum). (lasers)

  7. High-energy transversely pumped alkali vapor laser

    NASA Astrophysics Data System (ADS)

    Zweiback, J.; Komashko, A.

    2011-03-01

    We report on the results from our transversely pumped alkali laser. This system uses an Alexandrite laser to pump a stainless steel laser head. The system uses methane and helium as buffer gasses. Using rubidium, the system produced up to 40 mJ of output energy when pumped with 63 mJ. Slope efficiency was 75%. Using potassium as the lasing species the system produced 32 mJ and a 53% slope efficiency.

  8. Diode pumped alkali vapor lasers for high power applications

    NASA Astrophysics Data System (ADS)

    Zweiback, J.; Krupke, B.; Komashko, A.

    2008-02-01

    General Atomics has been engaged in the development of diode pumped alkali vapor lasers. We have been examining the design space looking for designs that are both efficient and easily scalable to high powers. Computationally, we have looked at the effect of pump bandwidth on laser performance. We have also looked at different lasing species. We have used an alexandrite laser to study the relative merits of different designs. We report on the results of our experimental and computational studies.

  9. Resonances in low-energy positron-alkali scattering

    NASA Technical Reports Server (NTRS)

    Horbatsch, M.; Ward, S. J.; Mceachran, R. P.; Stauffer, A. D.

    1990-01-01

    Close-coupling calculations were performed with up to five target states at energies in the excitation threshold region for positron scattering from Li, Na and K. Resonances were discovered in the L = 0, 1 and 2 channels in the vicinity of the atomic excitation thresholds. The widths of these resonances vary between 0.2 and 130 MeV. Evidence was found for the existence of positron-alkali bound states in all cases.

  10. Radioisotope powered alkali metal thermoelectric converter design for space systems

    NASA Technical Reports Server (NTRS)

    Sievers, R. K.; Bankston, C. P.

    1988-01-01

    The design concept of an alkali-metal thermoelectric converter (AMTEC) for 15-30-percent-efficient conversion of heat from the General Purpose (radioisotope) Heat Source (GPHS) on spacecraft is presented. The basic physical principles of the conversion cycle are outlined; a theoretical model is derived; a modular design is described and illustrated with drawings; and the overall AMTEC/GPHS system design is characterized. Predicted performance data are presented in extensive tables and graphs and discussed in detail.

  11. Polarizabilities of the alkali anions: Li- to Fr-.

    PubMed

    Lupinetti, Concetta; Thakkar, Ajit J

    2006-11-21

    Static dipole polarizabilities are calculated for the ground states of the alkali anions from Li- to Fr-. The polarizabilities include scalar relativistic effects at the second-order Douglas-Kroll level and were computed using the finite-field, coupled-cluster CCSD(T) method with large, carefully optimized basis sets. The relativistic polarizabilities increase with Z, reach a maximum at Cs-, and then decrease again unlike their nonrelativistic counterparts which increase monotonically with Z.

  12. Antacids, altered mental status, and milk-alkali syndrome.

    PubMed

    Watson, Simon C; Dellinger, Bonnie B; Jennings, Katie; Scott, Lancer A

    2012-01-01

    The frequency of milk-alkali syndrome decreased rapidly after the development of histamine-2 antagonists and proton pump inhibitors for the treatment of peptic ulcer disease; however, the availability and overconsumption of antacids and calcium supplements can still place patients at risk (D. P. Beall et al., 2006). Here we describe a patient who presented with altered mental status, hypercalcemia, metabolic alkalosis, and acute renal failure in the context of ingesting large amounts of antacids to control dyspepsia.

  13. Lithological influence of aggregate in the alkali-carbonate reaction

    SciTech Connect

    Lopez-Buendia, A.M. . E-mail: angel.lopez@aidico.es; Climent, V. . E-mail: vcliment@grupogla.com; Verdu, P.

    2006-08-15

    The reactivity of carbonate rock with the alkali content of cement, commonly called alkali-carbonate reaction (ACR), has been investigated. Alkali-silica reaction (ASR) can also contribute in the alkali-aggregate reaction (AAR) in carbonate rock, mainly due to micro- and crypto-crystalline quartz or clay content in carbonate aggregate. Both ACR and ASR can occur in the same system, as has been also evidenced on this paper. Carbonate aggregate samples were selected using lithological reactivity criteria, taking into account the presence of dedolomitization, partial dolomitization, micro- and crypto-crystalline quartz. Selected rocks include calcitic dolostone with chert (CDX), calcitic dolostone with dedolomitization (CDD), limestone with chert (LX), marly calcitic dolostone with partial dolomitization (CD), high-porosity ferric dolostone with clays (FD). To evaluate the reactivity, aggregates were studied using expansion tests following RILEM AAR-2, AAR-5, a modification using LiOH AAR-5Li was also tested. A complementary study was done using petrographic monitoring with polarised light microscopy on aggregates immersed in NaOH and LiOH solutions after different ages. SEM-EDAX has been used to identify the presence of brucite as a product of dedolomitization. An ACR reaction showed shrinkage of the mortar bars in alkaline solutions explained by induced dedolomitization, while an ASR process typically displayed expansion. Neither shrinkage nor expansion was observed when mortar bars were immersed in solutions of lithium hydroxide. Carbonate aggregate classification with AAR pathology risk has been elaborated based on mechanical behaviours by expansion and shrinkage. It is proposed to be used as a petrographic method for AAR diagnosis to complement the RILEM AAR1 specifically for carbonate aggregate. Aggregate materials can be classified as I (non-reactive), II (potentially reactive), and III (probably reactive), considering induced dedolomitization ACR

  14. Historical and Experimental Studies of Alkali and Trinitrotoluene Reaction

    DTIC Science & Technology

    1975-04-01

    Certainly attempts at titration in aqueous media would be futile in light of the virtually non- Bxiste•ut acidic properties of TNT. B. Production of Red...to get an addition compound of TNT and methyl alcohol which is the nitronic acid from which the alkali metal salts are derived. Hantzsch 4 originally...of quinol nitrol acids . The colored compounds formed by nitro-substituted aromatic com- pounds in alcoholic alkaline media occur only when one or more

  15. Alkali Metal Cation Transport and Homeostasis in Yeasts

    PubMed Central

    Ariño, Joaquín; Ramos, José; Sychrová, Hana

    2010-01-01

    Summary: The maintenance of appropriate intracellular concentrations of alkali metal cations, principally K+ and Na+, is of utmost importance for living cells, since they determine cell volume, intracellular pH, and potential across the plasma membrane, among other important cellular parameters. Yeasts have developed a number of strategies to adapt to large variations in the concentrations of these cations in the environment, basically by controlling transport processes. Plasma membrane high-affinity K+ transporters allow intracellular accumulation of this cation even when it is scarce in the environment. Exposure to high concentrations of Na+ can be tolerated due to the existence of an Na+, K+-ATPase and an Na+, K+/H+-antiporter, which contribute to the potassium balance as well. Cations can also be sequestered through various antiporters into intracellular organelles, such as the vacuole. Although some uncertainties still persist, the nature of the major structural components responsible for alkali metal cation fluxes across yeast membranes has been defined within the last 20 years. In contrast, the regulatory components and their interactions are, in many cases, still unclear. Conserved signaling pathways (e.g., calcineurin and HOG) are known to participate in the regulation of influx and efflux processes at the plasma membrane level, even though the molecular details are obscure. Similarly, very little is known about the regulation of organellar transport and homeostasis of alkali metal cations. The aim of this review is to provide a comprehensive and up-to-date vision of the mechanisms responsible for alkali metal cation transport and their regulation in the model yeast Saccharomyces cerevisiae and to establish, when possible, comparisons with other yeasts and higher plants. PMID:20197501

  16. The unexpected properties of alkali metal iron selenide superconductors

    SciTech Connect

    Dagotto, Elbio R

    2013-01-01

    The iron-based superconductors that contain FeAs layers as the fundamental building block in the crystal structures have been rationalized in the past using ideas based on the Fermi surface nesting of hole and electron pockets when in the presence of weak Hubbard U interactions. This approach seemed appropriate considering the small values of the magnetic moments in the parent compounds and the clear evidence based on photoemission experiments of the required electron and hole pockets. However, recent results in the context of alkali metal iron selenides, with generic chemical composition AxFe2ySe2 (A alkali metal element), have challenged those previous ideas since at particular compositions y the low-temperature ground states are insulating and display antiferromagnetic order with large iron magnetic moments. Moreover, angle-resolved photoemission studies have revealed the absence of hole pockets at the Fermi level in these materials. The present status of this exciting area of research, with the potential to alter conceptually our understanding of the ironbased superconductors, is here reviewed, covering both experimental and theoretical investigations. Other recent related developments are also briefly reviewed, such as the study of selenide two-leg ladders and the discovery of superconductivity in a single layer of FeSe. The conceptual issues considered established for the alkali metal iron selenides, as well as several issues that still require further work, are discussed.

  17. Chlor-alkali producers evaluate safer alternatives to asbestos

    SciTech Connect

    Stadig, W.

    1993-03-01

    Until recently, 75% of all US capacity for producing chlor-alkali - more than 40% of the world's capacity - has used asbestos diaphragm-cell technology. Although the Environmental Protection Agency continues to exempt asbestos use in diaphragms from restrictions, producers are considering alternatives. In Germany, stringent regulations will ban asbestos in chlor-alkali production after 1994. Heavy fines were levied recently against some chlor-alkali producers in the United States when EPA inspectors found asbestos fibers in cell renewal areas. Restrictions on the mining of asbestos raise the cost of obtaining adequate amounts of high-quality asbestos and gradually raise the cost of transporting and discarding spent diaphragms. Two alternatives are to use newly developed, non-asbestos diaphragms or to convert to existing ion-exchange membrane-cell technology. Only the former seems economical in the United States. The non-asbestos diaphragm is based on an inorganic polymer composite developed in 1988 as an asbestos substitute. The composite received Du Pont's Plunkett Award for Innovation with Teflon[trademark], landed on the National Development Association's 1991 Honor Roll and became a 1991 R D 100 Award winner. 6 figs.

  18. The Interfacial Transition Zone in Alkali-Activated Slag Mortars

    NASA Astrophysics Data System (ADS)

    San Nicolas, Rackel; Provis, John

    2015-12-01

    The interfacial transition zone (ITZ) is known to strongly influence the mechanical and transport properties of mortars and concretes. This paper studies the ITZ between siliceous (quartz) aggregates and alkali activated slag binders in the context of mortar specimens. Backscattered electron images (BSE) generated in an environmental scanning electron microscope (ESEM) are used to identify unreacted binder components, reaction products and porosity in the zone surrounding aggregate particles, by composition and density contrast. X-ray mapping is used to exclude the regions corresponding to the aggregates from the BSE image of the ITZ, thus enabling analysis of only the binder phases, which are segmented into binary images by grey level discrimination. A distinct yet dense ITZ region is present in the alkali-activated slag mortars, containing a reduced content of unreacted slag particles compared to the bulk binder. The elemental analysis of this region shows that it contains a (C,N)-A-S-H gel which seems to have a higher content of Na (potentially deposited through desiccation of the pore solution) and a lower content of Ca than the bulk inner and outer products forming in the main binding region. These differences are potentially important in terms of long-term concrete performance, as the absence of a highly porous interfacial transition zone region is expected to provide a positive influence on the mechanical and transport properties of alkali-activated slag concretes.

  19. Plasma formation in diode pumped alkali lasers sustained in Cs

    NASA Astrophysics Data System (ADS)

    Markosyan, Aram H.; Kushner, Mark J.

    2016-11-01

    In diode pumped alkali lasers (DPALs), lasing action occurs on the resonant lines of alkali atoms following pumping by broadband semiconductor lasers. The goal is to convert the efficient but usually poor optical quality of inexpensive diode lasers into the high optical quality of atomic vapor lasers. Resonant excitation of alkali vapor leads to plasma formation through the excitation transfer from the 2P states to upper lying states, which then are photoionized by the pump and intracavity radiation. A first principles global model was developed to investigate the operation of the He/Cs DPAL system and the consequences of plasma formation on the efficiency of the laser. Over a range of pump powers, cell temperatures, excitation frequency, and mole fraction of the collision mixing agent (N2 or C2H6), we found that sufficient plasma formation can occur that the Cs vapor is depleted. Although N2 is not a favored collisional mixing agent due to large rates of quenching of the 2P states, we found a range of pump parameters where laser oscillation may occur. The poor performance of N2 buffered systems may be explained in part by plasma formation. We found that during the operation of the DPAL system with N2 as the collisional mixing agent, plasma formation is in excess of 1014-1015 cm-3, which can degrade laser output intensity by both depletion of the neutral vapor and electron collisional mixing of the laser levels.

  20. Inhibition of NUCKS Facilitates Corneal Recovery Following Alkali Burn

    PubMed Central

    Poon, Ming-Wai; Jiang, Dan; Qin, Peng; Zhang, Yuelin; Qiu, Beiying; Chanda, Sumit; Tergaonkar, Vinay; Li, Qing; Wong, Ian Y.; Yu, Zhendong; Tse, Hung-Fat; Wong, David S. H.; Lian, Qizhou

    2017-01-01

    Corneal wound healing involves a complex cascade of cytokine-controlled cellular events, including inflammatory and angiogenesis responses that are regulated by transcriptional chromatin remodeling. Nuclear Ubiquitous Casein and cyclin-dependent Kinase Substrate (NUCKS) is a key chromatin modifier and transcriptional regulator of metabolic signaling. In this study, we investigated the role of NUCKS in corneal wound healing by comparing its effects on corneal alkali burn in NUCKS knockout (NKO) and NUCKS wild-type (NWT) mice. Our data showed that following alkali-injury, inhibition of NUCKS (NKO) accelerated ocular resurfacing and suppressed neovascularization; the cytokine profile of alkali burned corneas in NKO mice showed suppressed expression of inflammation cytokines (IL1A & IL1B); upregulated expression of antiangiogenic factor (Pigment Epithelium-derived Factor; PEDF); and downregulated expression of angiogenic factor (Vascular Endothelial Growth Factor, VEGF); in vitro, following LPS-induced NFκB activation, NKO corneal cells showed reduced expression of IL6, IP10 and TNFα. In vitro, corneal epithelial cells showed reduced NF-κb activation on silencing of NUCKS and corresponding NFκB-mediated cytokine expression was reduced. Here, we illustrate that inhibition of NUCKS played a role in cytokine modulation and facilitated corneal recovery. This reveals a potential new effective strategy for ocular burn treatment. PMID:28106169