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Sample records for ng n2o-n g-1

Photocatalytic decomposition of N2O over TiO2/g-C3N4 photocatalysts heterojunction

Science.gov (United States)

Kočí, K.; Reli, M.; Troppová, I.; Šihor, M.; Kupková, J.; Kustrowski, P.; Praus, P.

2017-02-01

TiO2/g-C3N4 photocatalysts with the various TiO2/g-C3N4 weight ratios from 1:2 to 1:6 were fabricated by mechanical mixing in water suspension followed by calcination. Pure TiO2 was prepared by thermal hydrolysis and pure g-C3N4 was prepared from commercial melamine by thermal annealing at 620 °C. All the nanocomposites were characterized by X-ray powder diffraction, UV-vis diffuse reflectance spectroscopy, Raman spectroscopy, infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, photoelectrochemical measurements and nitrogen physisorption. The prepared mixtures along with pure TiO2 and g-C3N4 were tested for the photocatalytic decomposition of nitrous oxide under UVC (λ = 254 nm), UVA (λ = 365 nm) and Vis (λ > 400 nm) irradiation. The TiO2/g-C3N4 nanocomposites showed moderate improvement compared to pure g-C3N4 but pure TiO2 proved to be a better photocatalyst under UVC irradiation. However, under UVA irradiation conditions, the photocatalytic activity of TiO2/g-C3N4 (1:2) nanocomposite exhibited an increase compared to pure TiO2. Nevertheless, further increase of g-C3N4 amount leads/led to a decrease in reactivity. These results are suggesting the nanocomposite with the optimal weight ratio of TiO2 and g-C3N4 have shifted absorption edge energy towards longer wavelengths and decreased the recombination rate of charge carriers compared to pure g-C3N4. This is probably due to the generation of heterojunction on the TiO2/g-C3N4 interface.
N.G. Basov and early works on semiconductor lasers at P.N. Lebedev Physics Institute

International Nuclear Information System (INIS)

Eliseev, P G

2012-01-01

A survey is presented of works on creation and investigation of semiconductor lasers during 1957 – 1977 at the P.N. Lebedev Physics Institute. Many of these works were initiated by N.G. Basov, starting from pre-laser time, when N.G. Basov and his coworkers formulated principal conditions of creation of lasers on interband transitions in semiconductors. Main directions of further works were diode lasers based on various materials and structures, their characteristics of output power, high-speed operation and reliability. (special issue devoted to the 90th anniversary of n.g. basov)
Photocatalytic decomposition of N{sub 2}O over TiO{sub 2}/g-C{sub 3}N{sub 4} photocatalysts heterojunction

Energy Technology Data Exchange (ETDEWEB)

Kočí, K., E-mail: kamila.koci@vsb.cz [Institute of Environmental technologies, VŠB Technical University of Ostrava 17. listopadu 15/2172, 708 00 Ostrava (Czech Republic); Reli, M.; Troppová, I.; Šihor, M. [Institute of Environmental technologies, VŠB Technical University of Ostrava 17. listopadu 15/2172, 708 00 Ostrava (Czech Republic); Kupková, J. [Nanotechnology center, VŠB Technical University of Ostrava 17. listopadu 15/2172, 708 00 Ostrava (Czech Republic); Kustrowski, P. [Faculty of Chemistry, Jagiellonian University in Kraków, ul. Ingardena 3, 30-060 Kraków (Poland); Praus, P. [Institute of Environmental technologies, VŠB Technical University of Ostrava 17. listopadu 15/2172, 708 00 Ostrava (Czech Republic); Department of Chemistry, VŠB Technical University of Ostrava 17. listopadu 15/2172, 708 00 Ostrava (Czech Republic)

2017-02-28

Highlights: • TiO{sub 2}/g-C{sub 3}N{sub 4} photocatalysts with the various TiO{sub 2}/g-C{sub 3}N{sub 4} weight ratios. • N{sub 2}O photocatalytic decomposition under UVC and UVA irradiation. • Heterojunction on the TiO{sub 2}/g-C{sub 3}N{sub 4} interface play an important role. • Optimal ratio of TiO{sub 2}:g-C{sub 3}N{sub 4} was 1:2 for the highest activity at UVA irradiation. - Abstract: TiO{sub 2}/g-C{sub 3}N{sub 4} photocatalysts with the various TiO{sub 2}/g-C{sub 3}N{sub 4} weight ratios from 1:2 to 1:6 were fabricated by mechanical mixing in water suspension followed by calcination. Pure TiO{sub 2} was prepared by thermal hydrolysis and pure g-C{sub 3}N{sub 4} was prepared from commercial melamine by thermal annealing at 620 °C. All the nanocomposites were characterized by X-ray powder diffraction, UV–vis diffuse reflectance spectroscopy, Raman spectroscopy, infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, photoelectrochemical measurements and nitrogen physisorption. The prepared mixtures along with pure TiO{sub 2} and g-C{sub 3}N{sub 4} were tested for the photocatalytic decomposition of nitrous oxide under UVC (λ = 254 nm), UVA (λ = 365 nm) and Vis (λ > 400 nm) irradiation. The TiO{sub 2}/g-C{sub 3}N{sub 4} nanocomposites showed moderate improvement compared to pure g-C{sub 3}N{sub 4} but pure TiO{sub 2} proved to be a better photocatalyst under UVC irradiation. However, under UVA irradiation conditions, the photocatalytic activity of TiO{sub 2}/g-C{sub 3}N{sub 4} (1:2) nanocomposite exhibited an increase compared to pure TiO{sub 2}. Nevertheless, further increase of g-C{sub 3}N{sub 4} amount leads/led to a decrease in reactivity. These results are suggesting the nanocomposite with the optimal weight ratio of TiO{sub 2} and g-C{sub 3}N{sub 4} have shifted absorption edge energy towards longer wavelengths and decreased the recombination rate of charge carriers compared to pure g-C{sub 3}N{sub 4}. This is
Nitrous Oxide (N2O) Emissions by Termites: Does the Feeding Guild Matter?

Science.gov (United States)

Brauman, Alain; Majeed, Muhammad Zeeshan; Buatois, Bruno; Robert, Alain; Pablo, Anne-Laure; Miambi, Edouard

2015-01-01

In the tropics, termites are major players in the mineralization of organic matter leading to the production of greenhouse gases including nitrous oxide (N2O). Termites have a wide trophic diversity and their N-metabolism depends on the feeding guild. This study assessed the extent to which N2O emission levels were determined by termite feeding guild and tested the hypothesis that termite species feeding on a diet rich in N emit higher levels of N2O than those feeding on a diet low in N. An in-vitro incubation approach was used to determine the levels of N2O production in 14 termite species belonging to different feeding guilds, collected from a wide range of biomes. Fungus-growing and soil-feeding termites emit N2O. The N2O production levels varied considerably, ranging from 13.14 to 117.62 ng N2O-N d(-1) (g dry wt.)(-1) for soil-feeding species, with Cubitermes spp. having the highest production levels, and from 39.61 to 65.61 ng N2O-N d(-1) (g dry wt.)(-1) for fungus-growing species. Wood-feeding termites were net N2O consumers rather than N2O producers with a consumption ranging from 16.09 to 45.22 ng N2O-N d(-1) (g dry wt.)(-1). Incubating live termites together with their mound increased the levels of N2O production by between 6 and 13 fold for soil-feeders, with the highest increase in Capritermes capricornis, and between 14 and 34 fold for fungus-growers, with the highest increase in Macrotermes muelleri. Ammonia-oxidizing (amoA-AOB and amoA-AOA) and denitrifying (nirK, nirS, nosZ) gene markers were detected in the guts of all termite species studied. No correlation was found between the abundance of these marker genes and the levels of N2O production from different feeding guilds. Overall, these results support the hypothesis that N2O production rates were higher in termites feeding on substrates with higher N content, such as soil and fungi, compared to those feeding on N-poor wood.
Nitrous Oxide (N2O Emissions by Termites: Does the Feeding Guild Matter?

Directory of Open Access Journals (Sweden)

Alain Brauman

Full Text Available In the tropics, termites are major players in the mineralization of organic matter leading to the production of greenhouse gases including nitrous oxide (N2O. Termites have a wide trophic diversity and their N-metabolism depends on the feeding guild. This study assessed the extent to which N2O emission levels were determined by termite feeding guild and tested the hypothesis that termite species feeding on a diet rich in N emit higher levels of N2O than those feeding on a diet low in N. An in-vitro incubation approach was used to determine the levels of N2O production in 14 termite species belonging to different feeding guilds, collected from a wide range of biomes. Fungus-growing and soil-feeding termites emit N2O. The N2O production levels varied considerably, ranging from 13.14 to 117.62 ng N2O-N d(-1 (g dry wt.(-1 for soil-feeding species, with Cubitermes spp. having the highest production levels, and from 39.61 to 65.61 ng N2O-N d(-1 (g dry wt.(-1 for fungus-growing species. Wood-feeding termites were net N2O consumers rather than N2O producers with a consumption ranging from 16.09 to 45.22 ng N2O-N d(-1 (g dry wt.(-1. Incubating live termites together with their mound increased the levels of N2O production by between 6 and 13 fold for soil-feeders, with the highest increase in Capritermes capricornis, and between 14 and 34 fold for fungus-growers, with the highest increase in Macrotermes muelleri. Ammonia-oxidizing (amoA-AOB and amoA-AOA and denitrifying (nirK, nirS, nosZ gene markers were detected in the guts of all termite species studied. No correlation was found between the abundance of these marker genes and the levels of N2O production from different feeding guilds. Overall, these results support the hypothesis that N2O production rates were higher in termites feeding on substrates with higher N content, such as soil and fungi, compared to those feeding on N-poor wood.
Facile synthesis of Fe3O4/g-C3N4/HKUST-1 composites as a novel biosensor platform for ochratoxin A.

Science.gov (United States)

Hu, Shuisheng; Ouyang, Wenjun; Guo, Longhua; Lin, Zhenyu; Jiang, Xiaohua; Qiu, Bin; Chen, Guonan

2017-06-15

A fluorescent biosensor for ochratoxin A was fabricated on the basis of a new nanocomposite (Fe 3 O 4 /g-C 3 N 4 /HKUST-1 composites). Fe 3 O 4 /g-C 3 N 4 /HKUST-1 was synthesized in this work for the first time, which combined HKUST-1 with g-C 3 N 4 to improve its chemical stability. Fe 3 O 4 /g-C 3 N 4 /HKUST-1 composites have strong adsorption capacity for dye-labeled aptamer and are able to completely quench the fluorescence of the dye through the photoinduced electron transfer (PET) mechanism. In the presence of ochratoxin A (OTA), it can bind with the aptamer with high affinity, causing the releasing of the dye-labeled aptamer from the Fe 3 O 4 /g-C 3 N 4 /HKUST-1 and therefore results in the recovery of fluorescence. The fluorescence intensity of the biosensor has a linear relationship with the OTA concentration in the range of 5.0-160.0ng/mL. The LOD of sensor is 2.57ng/mL (S/N=3). This fluorescence sensor based on the Fe 3 O 4 /g-C 3 N 4 /HKUST-1 composites has been applied to detect OTA in corn with satisfying results. Copyright © 2016. Published by Elsevier B.V.
Theoretical study of [Li(H2O)n]+ and [K(H2O)n]+ (n = 1-4) complexes

International Nuclear Information System (INIS)

Wojcik, M.J.; Mains, G.J.; Devlin, J.P.

1995-01-01

The geometries, successive binding energies, vibrational frequencies, and infrared intensities are calculated for the [Li(H 2 O) n ] + and [K(H 2 O) n ] + (n = 1-4) complexes. The basis sets used are 6-31G * and LANL1DZ (Los Alamos ECP+DZ) at the SCF and MP2 levels. There is an agreement for calculated structures and frequencies between the MP2/6-31G * and MP2/LANL1DZ basis sets, which indicates that the latter can be used for calculations of water complexes with heavier ions. Our results are in a reasonable agreement with available experimental data and facilitate experimental study of these complexes. 19 refs., 4 figs., 6 tabs
Theoretical study of the interaction of N2 with water molecules. (H2O)/sub n/:N2, n = 1--8

International Nuclear Information System (INIS)

Curtiss, L.A.; Eisgruber, C.L.

1984-01-01

Ab initio molecular orbital calculations including correlation energy have been carried out on the interaction of a single H 2 O molecule with N 2 . The potential energy surface for H 2 O:N 2 is found to have a minimum corresponding to a HOH xxx N 2 structure with a weak ( -1 ) hydrogen bond. A second, less stable, configuration corresponding to a H 2 O xxx N 2 structure with N 2 bonded side on to the oxygen of H 2 O was found to be either a minimum or a saddle point in the potential energy surface depending on the level of calculation. The minimal STO-3G basis set was used to investigate the interaction of up to eight H 2 O molecules with N 2 . Two types of clusters, one containing only HOH xxx N 2 interactions and the other containing both HOH xxxN 2 and H 2 O xxx N 2 interactions, were investigated for [N 2 :(H 2 O)/sub n/, n = 2--8
Unconventionally prepared TiO2/g-C3N4 photocatalysts for photocatalytic decomposition of nitrous oxide

Science.gov (United States)

Troppová, Ivana; Šihor, Marcel; Reli, Martin; Ritz, Michal; Praus, Petr; Kočí, Kamila

2018-02-01

The TiO2/g-C3N4 nanocomposites with the various TiO2:g-C3N4 weight ratios from 1:1 to 1:3 were prepared unconventionally by pressurized hot water processing in a flow regime. The parent TiO2 and g-C3N4 was prepared by thermal hydrolysis and thermal annealing, respectively. The nanocomposites as well as parent TiO2 and g-C3N4 were characterized using several complementary characterization methods and investigated in the photocatalytic decomposition of N2O under UVA (λ = 365 nm) irradiation. All the prepared TiO2/g-C3N4 nanocomposites showed higher photocatalytic activity in comparison with the pure g-C3N4 and chiefly pure TiO2. The photocatalytic activity of TiO2/g-C3N4 nanocomposites was decreasing in the following sequence: TiO2/g-C3N4 (1:3) > TiO2/g-C3N4 (1:2) > TiO2/g-C3N4 (1:1). In comparison with the parent TiO2 or g-C3N4, the TiO2/g-C3N4 nanocomposites' photocatalytic capability was significantly enhanced by coupling TiO2 with g-C3N4. The generation of TiO2/g-C3N4 Z-scheme photocatalyst mainly benefited from the effective separation of photoinduced electron-hole pairs and the extended optical absorption range. The TiO2/g-C3N4 (1:3) nanocomposite showed the best photocatalytic behavior in a consequence of the optimal weight ratio of TiO2:g-C3N4 and the lowest band gap energy from all nanocomposites. The N2O conversion in its presence was 70.6% after 20 h of UVA irradiation.
Comparison and mechanism of photocatalytic activities of N-ZnO and N-ZrO2 for the degradation of rhodamine 6G.

Science.gov (United States)

Sudrajat, Hanggara; Babel, Sandhya

2016-05-01

N-doped ZnO (N-ZnO) and N-doped ZrO2 (N-ZrO2) are synthesized by novel, simple thermal decomposition methods. The catalysts are evaluated for the degradation of rhodamine 6G (R6G) under visible and UV light. N-ZnO exhibits higher dye degradation under both visible and UV light compared to N-ZrO2 due to possessing higher specific surface area, lower crystalline size, and lower band gap. However, it is less reusable than N-ZrO2 and its photocatalytic activity is also deteriorated at low pH. At the same intensity of 3.5 W/m(2), UVC light is shown to be a better UV source for N-ZnO, while UVA light is more suitable for N-ZrO2. At pH 7 with initial dye concentration of 10 mg/L, catalyst concentration of 1 g/L, and UVC light, 94.3 % of R6G is degraded by N-ZnO within 2 h. Using UVA light under identical experimental conditions, 93.5 % degradation of R6G is obtained by N-ZrO2. Moreover, the type of light source is found to determine the reactive species produced in the R6G degradation by N-ZnO and N-ZrO2. Less oxidative reactive species such as superoxide radical and singlet oxygen play a major role in the degradation of R6G under visible light. On the contrary, highly oxidative hydroxyl radicals are predominant under UVC light. Based on the kinetic study, the adsorption of R6G on the catalyst surface is found to be the controlling step.
DFT Calculation of IR Absorption Spectra for PCE-nH2O, TCE-nH2O, DCE-nH2O, VC-nH2O for Small and Water-Dominated Molecular Clusters

Science.gov (United States)

2017-10-31

VC-nH2O for Small and Water-Dominated Molecular Clusters October 31, 2017 Approved for public release; distribution is unlimited. L. Huang S.g...Calculation of IR Absorption Spectra for PCE-nH2O, TCE-nH2O, DCE-nH2O, VC-nH2O for Small and Water-Dominated Molecular Clusters L. Huang,1 S.G...nH2O molecular clusters using density function theory (DFT). DFT can provide interpretation of absorption spectra with respect to molecular
Oxygen vibrations in the series Bi2Sr2Ca{_{n-1}}Cu{n}O{_{4+2 n+y}}

Science.gov (United States)

Faulques, E.; Dupouy, P.; Lefrant, S.

1991-06-01

We present a discussion of the oxygen vibrations in the Bi{2}Sr{2}Ca{n-1}Cu{n}O{4+2 n+y} high T_c superconductors with the aim of interpreting Raman spectra in the case of the non-symmorphic Amaa structure. Group theory shows that the oxygen atoms belonging to the central CuO{2} plane generate a Raman activity for the n=1,3 phases. Consequently, we propose a novel assignment for the lines of weak intensity at 297, 316 and 333 cm^{-1}. It is shown that the two components of the 460 cm^{-1} band may be consistent with the Amma structure. Spectra recorded in crossed polarization exhibit weak lines which could be assigned to B {1g} modes expected for the three phases. Nous présentons une discussion sur les vibrations des atomes d'oxygène dans la série des supraconducteurs Bi{2}Sr{2}Ca{n-1}Cu{n}O{4+2 n+y} dans le but d'interpréter les spectres Raman. L'analyse des modes normaux de vibration de la structure Amaa pour les phases n=1 ou 3 montre que les atomes d'oxygène du plan CuO{2} contenant les centres d'inversion donnent lieu à une activité Raman. En conséquence, nous proposons une nouvelle attribution pour les raies de faible intensité à 297, 316 et 333 cm^{-1}. Nous montrons que le dédoublement de la bande à 460 cm^{-1} pourrait être dû à la structure Amaa. Les spectres enregistrés en polarization croisée montrent de faibles bandes qui peuvent être attribuées aux modes B {1g} attendus pour les trois phases.
An Asymmetric Supercapacitor with Mesoporous NiCo2O4 Nanorod/Graphene Composite and N-Doped Graphene Electrodes

Science.gov (United States)

Mao, J. W.; He, C. H.; Qi, J. Q.; Zhang, A. B.; Sui, Y. W.; He, Y. Z.; Meng, Q. K.; Wei, F. X.

2018-01-01

In the present work, mesoporous NiCo2O4 nanorod/graphene oxide (NiCo2O4/GO) composite was prepared by a facile and cost-effective hydrothermal method and meanwhile, N-doped graphene (N-G) was fabricated also by a hydrothermal synthesis process. NiCo2O4/GO composite and N-G were used as positive and negative electrodes for the supercapacitor, respectively, which all displayed excellent electrochemical performances. The NiCo2O4/GO composite electrode exhibited a high specific capacitance of 709.7 F g-1 at a current density of 1 A g-1 and excellent rate capability as well as good cycling performance with 84.7% capacitance retention at 6 A g-1 after 3000 cycles. A high-voltage asymmetric supercapacitor (ASC) was successfully fabricated using NiCo2O4/GO composite and N-G as the positive and negative electrodes, respectively, in 1 M KOH aqueous electrolyte. The ASC delivered a high energy density of 34.4 Wh kg-1 at a power density of 800 W kg-1 and still maintained 28 Wh kg-1 at a power density of 8000 W kg-1. Furthermore, this ASC showed excellent cycling stability with 94.3% specific capacitance retained at 5 A g-1 after 5000 cycles. The impressive results can be ascribed to the positive synergistic effects of the two electrodes. Evidently, our work provides useful information for assembling high-performance supercapacitor devices.
Association equilibrium constants and populations of clusters (H2O)n(g) and (D2O)n(g): differences between isotopomers and a possible relation to isotope enrichment

International Nuclear Information System (INIS)

Slanina, Z.

1986-01-01

Equilibrium constants of H 2 O(g) and D 2 O(g) associations to clusters (H 2 O) n (g) and (D 2 O) n (g) were calculated on the basis of the ab initio SCF CI MCY-B water-water pair potential. Populations of the components of equilibrium cluster mixtures were evaluated at various temperatures and pressures for both isotopomeric series. Differences between the H and D steam are pointed out and possible consequences are discussed. (author)
Bradykinin-activated transmembrane signals are coupled via N/sub o/ or N/sub i/ to production of inositol 1,4,5-trisphosphate, a second messenger in NG108-15 neuroblastoma-glioma hybrid cells

International Nuclear Information System (INIS)

Higashida, H.; Streaty, R.A.; Klee, W.; Nirenberg, M.

1986-01-01

The addition of bradykinin to NG108-15 cells results in a transient hyperpolarization followed by prolonged cell depolarization. Injection of inositol 1,4,5-trisphosphate or Ca 2+ into the cytoplasm of NG108-15 cells also elicits cell hyperpolarization followed by depolarization. Tetraethylammonium ions inhibit the hyperpolarizing response of cells to bradykinin or inositol 1,4,5-trisphosphate. Thus, the hyperpolarizing phase of the cell response may be due to inositol 1,4,5-trisphosphate-dependent release of stored 45 Ca-labelled Ca 2+ into the cytoplasm, which activates Ca 2+ -dependent K + channels. The depolarizing phase of the cell response to bradykinin is due largely to inhibition of M channels, thereby decreasing the rate of K + efflux from cells and, to a lesser extent, to activation of Ca 2+ -dependent ion channels and Ca 2+ channels. In contrast, injection of inositol 1,4,5-trisphosphate or Ca 2+ into the cytosol did not alter M channel activity. Incubation of NG108-15 cells with pertussis toxin inhibits bradykinin-dependent cell hyperpolarization and depolarization. Bradykinin stimulates low K/sub m/ GTPase activity and inhibits adenylate cyclase in NG108-15 membrane preparations but not in membranes prepared from cells treated with pertussis toxin. These results show that [bradykinin-receptor] complexes interact with N/sub o/ or N/sub i/ and suggest that N/sub o/ and/or N/sub i/ mediate the transduction of signals from bradykinin receptors to phospholipase C and adenylate cyclase
An ingenious strategy of preparing TiO2/g-C3N4 heterojunction photocatalyst: In situ growth of TiO2 nanocrystals on g-C3N4 nanosheets via impregnation-calcination method

Science.gov (United States)

Zhang, Guanghui; Zhang, Tianyong; Li, Bin; Jiang, Shuang; Zhang, Xia; Hai, Li; Chen, Xingwei; Wu, Wubin

2018-03-01

An ingenious method was employed to design and fabricate the TiO2/g-C3N4 heterojunction photocatalysts in this study. The thermal oxidation etching of g-C3N4 nanosheets and the in situ growth of TiO2 nanocrystal on the surface of g-C3N4 nanosheets were completed simultaneously by the calcination process. The g-C3N4 nanosheets played a crucial role in regulating and assembling the structures and morphologies of TiO2. Furthermore, the thickness and content of g-C3N4, and the crystallinity of TiO2 in TiO2/g-C3N4 composites could be regulated and controlled by the calcination temperature. Among the resultant TiO2/g-C3N4 samples, the TiO2/g-C3N4 sample with 41.6 wt% g-C3N4 exhibited the highest photocatalytic activity. It could degrade almost all MO molecules under visible light irradiation within 3 h. Moreover, it displayed higher visible light photocatalytic performance for degrading MO solution than pure g-C3N4 and D-TiO2. The synergistic effect between TiO2 and g-C3N4 makes significant contributions to the enhancement of the visible light photocatalytic activity. In addition, the favorable photocatalytic performance of TiO2/g-C3N4 nanocomposites is also attributed to the porous structures and uniform morphologies, and large surface area. Furthermore, the resultant TiO2/g-C3N4 exhibits excellent photocatalytic stability. Radical trapping experiments indicated that rad O2- and h+ were the main reactive species during the photodegradation process under visible light irradiation. Hopefully, the results can offer new design and strategy for preparing other g-C3N4-based nanocomposites for environmental and energy applications.
O movimento Yīn e Yáng na cosmologia da medicina chinesa

Directory of Open Access Journals (Sweden)

Bernardo Diniz Coutinho

2015-09-01

Full Text Available Após ter se desenvolvido no Oriente, embasada pela cosmologia taoista, a medicina chinesa vem sendo praticada no Ocidente baseada na fundamentação científica e no paradigma biomédico, abandonando alguns elementos tradicionais dessa racionalidade, como a teoria Yīn e Yáng, conhecimento essencial para o entendimento do processo saúde-doença decorrente da circulação do sopro vital pelo corpo. Este artigo estuda o movimento da dupla Yīn e Yáng na doutrina médica chinesa, buscando conhecer como se desenvolveu essa linha de pensamento e a sua contribuição na elaboração do sistema diagnóstico e terapêutico. A metodologia utilizada foi a análise da literatura que aborda o objeto a partir do referencial teórico do pensamento taoista e da medicina tradicional chinesa.
Upwelling intensity modulates N2O concentrations over the western Indian shelf

Digital Repository Service at National Institute of Oceanography (India)

Sudheesh, V.; Gupta, G.V.M.; Sudharma, K.V.; Naik, H.; Shenoy, D.M.; Sudhakar, M.; Naqvi, S.W.A.

Pacific Ocean (off central Chile and Peru) have been identified as ‘‘hot spots’’ of N2O production with N2O saturations up to 8250% and 2426–12,244%, respectively [Naqvi et al., 2005; Cornejo et al., 2007; Ar�evalo-Mart�ınez et al., 2015]. The N2O flux per... Peru. (ETSP) 7.6–986 27–1825 Ar�evalo-Mart�ınez et al. [2015] Off central Chile (ETSP) 6.7–59 245 (30 m) 29.8–195 Cornejo et al. [2007] 5.1–30.1 206 (40 m) 27.7–42.9 Farias et al. [2009] Oman shelf 9.7–24.7 48.8 (50 m) N.G. Naqvi et al. [2010] Eastern...
Magnetism of Bi2Sr2Can-1CunO2n+4+δ (n = 1,2,3)

International Nuclear Information System (INIS)

Ishida, T.; Koga, K.; Kanoda, K.; Takahashi, T.

1992-01-01

The normal-state dc susceptibility χ dc of the Bi 2 Sr 2 Ca n-1 Cu n O 2n+4+δ (n=1, 2, 3) pellet is of the order of +10 -7 emu/g. A large Curie-Weiss component is found in χ dc and the ESR spin susceptibility χ ESR of the pulverized 2201, 2212 and 2223 samples but it almost disappears by annealing. The relative magnitudes of χ ESR to χ dc for the annealed powders are dissimilar among the three phases: ESR of the 2201 sample is silent, χ ESR of the 2212 phase has almost the same magnitude as χ dc and χ ESR of the 2223 phase is appreciable but smaller than χ dc . (orig.)
Nitrous Oxide (N2O) Emissions from Vehicles

International Nuclear Information System (INIS)

Becker, K.H.; Kurtenbach, R.; Lorzer, J.C.; Wiesen, P.; Jensen, T.; Wallington, T.J.

2000-01-01

N2O is an important greenhouse gas and accurate emission data are required to assess its impact on global climate. It is well established that automobiles, particularly those equipped with 3-way catalysts, emit N2O. However, the vehicle contribution to the global N2O budget is uncertain. We report results of N2O emission measurements performed in a road tunnel in Germany and using a chassis dynamometer system in the USA. We estimate that the global vehicle fleet emits (0.12±0.06) Tg yr-1 of N2O. From the emission factor (g N2O/g CO2) determined an annual N2O emission of (0.12±0.06) Tg yr-1 of N2O (0.08±0.04 Tg N yr-1) for the global vehicle fleet has been estimated which represents 1-4% of the atmospheric growth rate of this species. 9 refs

High sensitivity cavity ring down spectroscopy of N_2O near 1.22 µm: (II) "1"4N_2"1"6O line intensity modeling and global fit of "1"4N_2"1"8O line positions

International Nuclear Information System (INIS)

Tashkun, S.A.; Perevalov, V.I.; Karlovets, E.V.; Kassi, S.; Campargue, A.

2016-01-01

In a recent work (Karlovets et al., 2016 [1]), we reported the measurement and rovibrational assignments of more than 3300 transitions belonging to 64 bands of five nitrous oxide isotopologues ("1"4N_2"1"6O, "1"4N"1"5N"1"6O, "1"5N"1"4N"1"6O, "1"4N_2"1"8O and "1"4N_2"1"7O) in the high sensitivity CRDS spectrum recorded in the 7915–8334 cm"−"1 spectral range. The assignments were performed by comparison with predictions of the effective Hamiltonian models developed for each isotopologue. In the present paper, the large amount of measurements from our previous work mentioned above and literature are gathered to refine the modeling of the nitrous oxide spectrum in two ways: (i) improvement of the intensity modeling for the principal isotopologue, "1"4N_2"1"6O, near 8000 cm"−"1 from a new fit of the relevant effective dipole moment parameters, (ii) global modeling of "1"4N_2"1"8O line positions from a new fit of the parameters of the global effective Hamiltonian using an exhaustive input dataset collected in the literature in the 12–8231 cm"−"1 region. The fitted set of 81 parameters allowed reproducing near 5800 measured line positions with an RMS deviation of 0.0016 cm"−"1. The dimensionless weighted standard deviation of the fit is 1.22. As an illustration of the improvement of the predictive capabilities of the obtained effective Hamiltonian, two new "1"4N_2"1"8O bands could be assigned in the CRDS spectrum in the 7915–8334 cm"−"1 spectral range. A line list at 296 K has been generated in the 0–10,700 cm"−"1 range for "1"4N_2"1"8O in natural abundance with a 10"−"3"0 cm/molecule intensity cutoff. - Highlights: • Line parameters of two new "1"4N_2"1"8O bands centered at 7966 cm"−"1 and at 8214 cm"−"1. • Refined sets of the "1"4N_2"1"6O effective dipole moment parameters for ΔP=13,14 series. • Global modeling of "1"4N_2"1"8O line positions and intensities in the 12–8231 cm"−"1 range. • 5800 observed of "1"4N_2"1"8O line positions
Effect of rutile TiO{sub 2} on the photocatalytic performance of g-C{sub 3}N{sub 4}/brookite-TiO{sub 2-x}N{sub y} photocatalyst for NO decomposition

Energy Technology Data Exchange (ETDEWEB)

Li, Huihui, E-mail: lihh@lzu.edu.cn [Key Laboratory for Magnetism Magnetic Materials of the Ministry of Education, Lanzhou University, 222 south Tianshui Road, Lanzhou, 730000 (China); Wu, Xiaoyong [Wuhan University of Technology, 122 Luoshi Road, Wuhan 430070 (China); Yin, Shu [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); Katsumata, Kenichi [Photocatalysis International Research Center, Research Institute for Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba, 278-8510 (Japan); Wang, Yuhua [Key Laboratory for Magnetism Magnetic Materials of the Ministry of Education, Lanzhou University, 222 south Tianshui Road, Lanzhou, 730000 (China)

2017-01-15

Graphical abstract: g-C{sub 3}N{sub 4}/rutile-brookite TiO{sub 2-x}Ny forms a Z-scheme photocatalytic system, which shows improvement on the photocatalytic activity than that of g-C{sub 3}N{sub 4}/single brookite TiO{sub 2-x}N{sub y}. - Highlights: • g-C{sub 3}N{sub 4}/rutile-brookite TiO{sub 2-x}N{sub y} forms a Z-scheme photocatalytic system. • Photogenerated electrons can efficiently transfer from rutile TiO{sub 2} to g-C{sub 3}N{sub 4}. • Single brookite TiO{sub 2-x}N{sub y} shows lower photo-utilization efficiency than rutile-brookite mixed one. • DeNO{sub x} activities of brookite TiO{sub 2-x}N{sub y} hybrids decrease with g-C{sub 3}N{sub 4} amount increase. - Abstract: Novel g-C{sub 3}N{sub 4}/rutile-brookite TiO{sub 2-x}N{sub y} composite photocatalysts were fabricated through a facile solvothermal approach. The effect of rutile phase TiO{sub 2} with brookite TiO{sub 2} and g-C{sub 3}N{sub 4} on the photocatalytic activity of g-C{sub 3}N{sub 4}/nitrogen-doped TiO{sub 2} composite was studied. The photocatalytic performance of the photocatalyst was evaluated by measuring the degradation of NO gas under visible and UV light irradiation. It is suggested that g-C{sub 3}N{sub 4}/rutile-brookite TiO{sub 2-x}N{sub y} forms a Z-scheme photocatalytic system, which shows improvement on the photocatalytic activity than that of g-C{sub 3}N{sub 4}/single brookite TiO{sub 2-x}N{sub y}. By importing rutile phase TiO{sub 2-x}N{sub y}, the photogenerated electrons can efficiently transfer from rutile TiO{sub 2} to g-C{sub 3}N{sub 4}, which results in the separation of electron and hole pairs, enhancing the photocatalytic ability. However, single brookite TiO{sub 2-x}N{sub y} can not remove the photogenerated electrons efficiently and the photocatalytic performances of composites decrease with g-C{sub 3}N{sub 4} amount increase.
M(4-PridinkarboksialdehidNi(CN4.nG Hofmann Tipi Konak-Konuk Bileşiklerinin Kırmızıaltı Spektroskopik Özelliklerinin İncelenmesi (M = Ni, Cd ve G = 1,4-Dioksan

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Zeki KARTAL

2014-12-01

M(4-PyridinecarboxaldehydeNi(CN4.nG Hofmann Type Clathrates (M = Ni, Cd and G = 1,4-Dioxane Abstract: In this study, clathrate of 4-pyridinecarboxaldehyde tetracyanonickel-dioxane, given by the formula M(4-PyridinecarboxaldehydeNi(CN4 nG (m = Ni, Cd and G = 1,4-dioxane, is obtained for the first time through chemical methods. The FT-IR spectroscopic data in the region of (3000–400 cm-1 was recorded and the IR vibrational modes frequencies were given and explained in detail. The spectral analyzes results of the newly synthesized clathrate of 4-pyridinecarboxaldehyde tetracyanonickel- dioxane suggests that these clathrates are new examples of the Hofmann-type dioxane clathrates. In our study, the Hofmann-type dioxane clathrates formed by bounding electrons of nitrogen-donor atom of pyridine ring and electrons of oxygen-donor atom of aldehyde group (-CH=O of 4-pyridinecarboxaldehyde ligand molecule to transition metal atoms consist of the corrugated |M–Ni(CN4|ï‚¥ polymeric layers which are held in parallel through the chain of (–M–4PCA–M–. Key words: Infrared Spectroscopy, Hofmann Types Clathrates, Tetracyanonickelate, 4-pyridinecarboxaldehyde, 1,4-dioxane
Uptake properties of Ni2+ by nCaO.Al2O3.2SiO2 (n=1-4) prepared from solid-state reaction of kaolinite and calcite.

Science.gov (United States)

Jha, Vinay Kumar; Kameshima, Yoshikazu; Nakajima, Akira; Okada, Kiyoshi; MacKenzie, Kenneth J D

2005-08-31

A series of nCaO.Al2O3.2SiO2 samples (n=1-4) were prepared by solid-state reaction of mechanochemically treated mixtures of kaolinite and calcite fired at 600-1000 degrees C for 24 h. All the samples were X-ray amorphous after firing at 600-800 degrees C but had crystallized by 900 degrees C. The main crystalline phases were anorthite (n=1), gehlenite (n=2 and 3) and larnite (n=4). The uptake of Ni2+ by nCaO.Al2O3.2SiO2 samples fired at 800 and 900 degrees C was investigated at room temperature using solutions with initial Ni2+ concentrations of 0.1-50 mmol/l. Amorphous samples (fired at 800 degrees C) showed a higher Ni2+ uptake capacity than crystalline samples (fired at 900 degrees C). Ni2+ uptake was found to increase with increasing of CaO content. Amorphous 4CaO.Al2O3.2SiO2 showed the highest Ni2+ uptake capacity (about 9 mmol/g). The Ni2+ uptake abilities of the present samples are higher than those of other materials reported in the literature. Since the sorbed Ni2+/released Ca2+ ratios of these samples are close to unity, ion replacement of Ni2+ for Ca2+ is thought to be the principal mechanism of Ni2+ uptake by the present samples.
N Güngör

Indian Academy of Sciences (India)

Home; Journals; Bulletin of Materials Science. N Güngör. Articles written in Bulletin of Materials Science. Volume 27 Issue 3 June 2004 pp 317-322 Surfactants. Effect of sodium dodecyl sulfate on flow and electrokinetic properties of Na-activated bentonite dispersions · E Günıster S İşçı A Alemdar N Güngör · More Details ...
Construction of g-C3N4/CeO2/ZnO ternary photocatalysts with enhanced photocatalytic performance

Science.gov (United States)

Yuan, Yuan; Huang, Gui-Fang; Hu, Wang-Yu; Xiong, Dan-Ni; Zhou, Bing-Xin; Chang, Shengli; Huang, Wei-Qing

2017-07-01

Promoting the spatial separation of photoexcited charge carriers is of paramount significance for photocatalysis. In this work, binary g-C3N4/CeO2 nanosheets are first prepared by pyrolysis and subsequent exfoliation method, then decorated with ZnO nanoparticles to construct g-C3N4/CeO2/ZnO ternary nanocomposites with multi-heterointerfaces. Notably, the type-II staggered band alignments existing between any two of the constituents, as well as the efficient three-level transfer of electron-holes in unique g-C3N4/CeO2/ZnO ternary composites, leads to the robust separation of photoexcited charge carriers, as verified by its photocurrent increased by 8 times under visible light irradiation. The resulting g-C3N4/CeO2/ZnO ternary nanocomposites unveil appreciably increased photocatalytic activity, faster than that of pure g-C3N4, ZnO and g-C3N4/CeO2 by a factor of 11, 4.6 and 3.7, respectively, and good stability toward methylene blue (MB) degradation. The remarkably enhanced photocatalytic activity of g-C3N4/CeO2/ZnO ternary heterostructures can be interpreted in terms of lots of active sites of nanosheet shapes and the efficient charge separation owing to the resulting type-II band alignment with more than one heterointerface and the efficient three-level electron-hole transfer. A plausible mechanism is also elucidated via active species trapping experiments with various scavengers, which indicating that the photogenerated holes and •OH radicals play a crucial role in photodegradation reaction under visible light irradiation. This work suggest that the rational design and construction of type II multi-heterostructures is powerful for developing highly efficient and reusable visible-light photocatalysts for environmental purification and energy conversion.
Diaqua-2κ2O-bis(μ-1-oxido-2-naphthoato-1:2κ3O1,O2:O2′;2:3κ3O2:O1,O2′-bis(1-oxido-2-naphthoato-1κ1O2,O2;3κ2O1,O2-hexapyridine-1κ2N,2κ2N,3κ2N-trimanganese(II/III pyridine disolvate dihydrate

Directory of Open Access Journals (Sweden)

Daqi Wang

2008-12-01

Full Text Available The title complex, [Mn3(C11H6O34(C5H5N6(H2O2]·2H2O·2C5H5N, is a trinuclear mixed oxidation state complex of overline1 symmetry. The three Mn atoms are six-coordinated in the shape of distorted octahedra, each coordinated with an O4N2 set of donor atoms, where the ligands exhibit mono- and bidentate modes. However, the coordination of the MnII ion located on the inversion centre involves water molecules at two coordination sites, whereas that of the two symmetry-related MnIII ions involves an O4N2 set of donor atoms orginating from the organic ligands. Intramolecular C—H...π interactions between neighbouring pyridine ligands stabilize this arrangement. A two-dimensional network parallel to (001 is formed by intermolecular O—H...O hydrogen bonds.
Enhanced visible light photocatalytic activity in SnO{sub 2}@g-C{sub 3}N{sub 4} core-shell structures

Energy Technology Data Exchange (ETDEWEB)

Shen, Hao; Zhao, Xiaoru, E-mail: xrzhao@nwpu.edu.cn; Duan, Libing; Liu, Ruidi; Li, Hui

2017-04-15

Highlights: • Novel SnO{sub 2}@g-C{sub 3}N{sub 4} core-shell structures were successfully synthesized. • The core-shell structures exhibited enhanced visible light photocatalytic activity. • The enhanced photocatalytic activity was due to synergic action of SnO{sub 2} and g-C{sub 3}N{sub 4}. - Abstract: SnO{sub 2}@g-C{sub 3}N{sub 4} core-shell structures were successfully synthesized by simple calcination of SnO{sub 2} microspheres and urea in a muffle furnace. The investigation of morphologies and microstructures showed that g-C{sub 3}N{sub 4} was wrapped tightly on the surface of SnO{sub 2} microspheres with large intimate interface contact areas between the g-C{sub 3}N{sub 4} shells and SnO{sub 2} cores. The X-ray photoelectron spectroscopy results and photoluminescence spectra demonstrated that the intimate interface contacts could facilitate the transfer and separation of the photogenerated charge carriers at their interface, thus the recombination of the photogenerated electron-hole pairs was impeded. The photocatalytic activity of the synthesized composites was evaluated by the photodegradation of methyl orange under visible light irradiation. It was found that SnO{sub 2}@g-C{sub 3}N{sub 4} exhibited higher photodegradation rate (k = 0.013 min{sup −1}) than that of g-C{sub 3}N{sub 4} (k = 0.008 min{sup −1}) and pure SnO{sub 2}. The enhanced photocatalytic activity could be attributed to the synergic action of SnO{sub 2} and g-C{sub 3}N{sub 4}.
Vibrational spectroscopy of NO + (H2O)n: Evidence for the intracluster reaction NO + (H2O)n --> H3O + (H2O)n - 2 (HONO) at n => 4

Science.gov (United States)

Choi, Jong-Ho; Kuwata, Keith T.; Haas, Bernd-Michael; Cao, Yibin; Johnson, Matthew S.; Okumura, Mitchio

1994-05-01

Infrared spectra of mass-selected clusters NO+(H2O)n for n=1 to 5 were recorded from 2700 to 3800 cm-1 by vibrational predissociation spectroscopy. Vibrational frequencies and intensities were also calculated for n=1 and 2 at the second-order Møller-Plesset (MP2) level, to aid in the interpretation of the spectra, and at the singles and doubles coupled cluster (CCSD) level energies of n=1 isomers were computed at the MP2 geometries. The smaller clusters (n=1 to 3) were complexes of H2O ligands bound to a nitrosonium ion NO+ core. They possessed perturbed H2O stretch bands and dissociated by loss of H2O. The H2O antisymmetric stretch was absent in n=1 and gradually increased in intensity with n. In the n=4 clusters, we found evidence for the beginning of a second solvation shell as well as the onset of an intracluster reaction that formed HONO. These clusters exhibited additional weak, broad bands between 3200 and 3400 cm-1 and two new minor photodissociation channels, loss of HONO and loss of two H2O molecules. The reaction appeared to go to completion within the n=5 clusters. The primary dissociation channel was loss of HONO, and seven vibrational bands were observed. From an analysis of the spectrum, we concluded that the n=5 cluster rearranged to form H3O+(H2O)3(HONO), i.e., an adduct of the reaction products.
XANES study on Ruddlesdan-Popper phase, Lan+1NinO3n+1 (n = 1, 2 and ∞)

International Nuclear Information System (INIS)

Park, Jung-Chul; Kim, Dong-Kuk; Byeon, Song-Hu; Kim, Don

2001-01-01

Ruddlesden-Popper phase, La n+1 Ni n O 3n+ 1 (n = 1, 2, and ∞) compounds were prepared by citrate sol-gel method. We revealed the origin of the variation of the electrical conductivities in La n+1 Ni n O 3n+1 (n= 1, 2, and ∞) using resistivity measurements, Rietveld analysis, and X-ray absorption spectroscopy. According to the XANES spectra, it is found that the degree of 4pπ - 4pσ energy splitting between 8345 eV and 8350 eV is qualitatively proportional to the elongation of the out-of-plane Ni-O bond length. With the decrease of 4pπ-4pσ splitting, the strong hybridization of the σ-bonding between Ni-3d and O-2p orbitals creates narrow antibonding σ bands, which finally results in the lower electrical resistivity. (au)
Raman study of HgBa 2Ca n-1 Cu nO 2 n+2+ δ ( n=1,2,3,4 and 5) superconductors

Science.gov (United States)

Zhou, Xingjiang; Cardona, M.; Chu, C. W.; Lin, Q. M.; Loureiro, S. M.; Marezio, M.

1996-02-01

Polarized micro-Raman scattering measurements have been performed on the five members of the HgBa 2Ca n-1 Cu nO 2 n+2+ δ ( n=1,2,3,4 and 5) high- Tc superconductor family using different laser frequencies. Local laser annealing measurements were carried out to investigate the variation of the Raman spectra with the excess oxygen content, δ. A systematic evolution of the spectra, which display mainly peaks near 590, 570, 540 and 470 cm -1, with increasing number of CuO 2 layers has been observed; its origin has been shown to lie in the variation of the interstitial oxygen content. In addition to confirming that the 590 cm -1 mode represents vibration of apical oxygens in the absence of neighboring excess oxygen, the 570 cm -1 mode, which may be composed of some finer structures, has been assigned to the vibration of the apical oxygen modified by the presence of the neighboring excess oxygens. The 540 and 470 cm -1 modes may represent the direct vibration of excess oxygens. The implication of possible different distribution sites of excess oxygens is discussed. All other observed lower-frequency modes are also assigned.
Infrared spectroscopic and theoretical study of the HC2n+1O+ (n = 2-5) cations

Science.gov (United States)

Jin, Jiaye; Li, Wei; Liu, Yuhong; Wang, Guanjun; Zhou, Mingfei

2017-06-01

The carbon chain cations, HC2n+1O+ (n = 2-5), are produced via pulsed laser vaporization of a graphite target in supersonic expansions containing carbon monoxide and hydrogen. The infrared spectra are measured via mass-selected infrared photodissociation spectroscopy of the CO "tagged" [HC2n+1O.CO]+ cation complexes in the 1600-3500 cm-1 region. The geometries and electronic ground states of these cation complexes are determined by their infrared spectra compared to the predications of theoretical calculations. All of the HC2n+1O+ (n = 2-5) core cations are characterized to be linear carbon chain derivatives terminated by hydrogen and oxygen, which have the closed-shell singlet ground states with polyyne-like carbon chain structures.
An oxygen-vacancy-rich Z-scheme g-C3N4/Pd/TiO2 heterostructure for enhanced visible light photocatalytic performance

Science.gov (United States)

Guo, Yanru; Xiao, Limin; Zhang, Min; Li, Qiuye; Yang, Jianjun

2018-05-01

An oxygen-vacancy-rich Z-scheme g-C3N4/Pd/TiO2 ternary nanocomposite was fabricated using nanotubular titanic acid as precursors via a simple photo-deposition of Pd nanoparticles and calcination process. The prepared nanocomposites were investigated by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, and UV-visible diffuse reflectance spectroscopy, respectively. For g-C3N4/TiO2 binary nanocomposites, at the optimal content of g-C3N4 (2%), the apparent photocatalytic activity of 2%g-C3N4/TiO2 was 9 times higher than that of pure TiO2 under visible-light illumination. After deposition of Pd (1 wt%) at the contact interface between g-C3N4 and TiO2, the 2%g-C3N4/Pd/TiO2 ternary nanocomposites demonstrated the highest visible-light-driven photocatalytic activity for the degradation of gaseous propylene, which was 16- and 2-fold higher activities than pure TiO2 and 2%g-C3N4/TiO2, respectively. The mechanism for the enhanced photocatalytic performance of the g-C3N4/Pd/TiO2 photo-catalyst is proposed to be based on the efficient separation of photo-generated electron-hole pairs through Z-scheme system, in which uniform dispersity of Pd nanoparticles at contact interface between g-C3N4 and TiO2 and oxygen vacancies promote charge separation.
Insights into the photocatalytic mechanism of mediator-free direct Z-scheme g-C3N4/Bi2MoO6(010) and g-C3N4/Bi2WO6(010) heterostructures: A hybrid density functional theory study

Science.gov (United States)

Opoku, Francis; Govender, Krishna Kuben; Sittert, Cornelia Gertina Catharina Elizabeth van; Govender, Penny Poomani

2018-01-01

Graphite-like carbon nitride (g-C3N4)-based heterostructures have received much attention due to their prominent photocatalytic activity. The g-C3N4/Bi2WO6 and g-C3N4/Bi2MoO6 heterostructures, which follow a typical hetero-junction charge transfer mechanisms show a weak potential for hydrogen evolution and reactive radical generation under visible light irradiation. A mediator-free Z-scheme g-C3N4/Bi2MoO6(010) and g-C3N4/Bi2WO6(010) heterostructures photocatalyst are designed for the first time using first-principles studies. Moreover, theoretical understanding of the underlying mechanism, the effects of interfacial composition and the role the interface play in the overall photoactivity is still unexplained. The calculated band gap of the heterostructures is reduced compared to the bulk Bi2WO6 and Bi2MoO6. In this study, we systematically calculated energy band structure, optical properties and charge transfer of the g-C3N4/Bi2MoO6(010) and g-C3N4/Bi2WO6(010) heterostructures using the hybrid density functional theory approach. The results show that the charge transfer at the interface of the heterostructures induces a built-in potential, which benefits the separation of photogenerated charge carriers. The g-C3N4/Bi2MoO6(010) heterostructure with more negative adhesion energy (-1.10 eVA-2) is predicted to have a better adsorptive ability and can form more easily compared to the g-C3N4/Bi2WO6(010) interface (-1.16 eVA-2). Therefore, our results show that the g-C3N4 interaction with Bi2MoO6 is stronger than Bi2WO6, which is also verified by the smaller vertical separation (3.25 Å) between Bi2MoO6 and g-C3N4 compared to the g-C3N4/Bi2WO6(010) interface (3.36 Å). The optical absorption verifies that these proposed Z-scheme heterostructures are excellent visible light harvesting semiconductor photocatalyst materials. This enhancement is ascribed to the role of g-C3N4 monolayer as an electron acceptor and the direct Z-scheme charge carrier transfer at the interface of
Synthesis, characterization and electrochemical performance of graphene decorated with 1D NiMoO4.nH2O nanorods

Science.gov (United States)

Ghosh, Debasis; Giri, Soumen; Das, Chapal Kumar

2013-10-01

One-dimensional NiMoO4.nH2O nanorods and their graphene based hybrid composite with good electrochemical properties have been synthesized by a cost effective hydrothermal procedure. The formation of the mixed metal oxide and the composite was confirmed by XRD, XPS and Raman analyses. The morphological characterizations were carried out using FESEM and TEM analyses. The materials were subjected to electrochemical characterization through cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS) studies with 6 M KOH as the supporting electrolyte. For NiMoO4.nH2O, a maximum specific capacitance of 161 F g-1 was obtained at 5 A g-1 current density, accompanied with an energy density of 4.53 W h kg-1 at a steady power delivery rate of 1125 W kg-1. The high utility of the pseudocapacitive NiMoO4.nH2O was achieved in its graphene based composite, which exhibited a high specific capacitance of 367 F g-1 at 5 A g-1 current density and a high energy density of 10.32 W h kg-1 at a power density of 1125 W kg-1 accompanied with long term cyclic stability.One-dimensional NiMoO4.nH2O nanorods and their graphene based hybrid composite with good electrochemical properties have been synthesized by a cost effective hydrothermal procedure. The formation of the mixed metal oxide and the composite was confirmed by XRD, XPS and Raman analyses. The morphological characterizations were carried out using FESEM and TEM analyses. The materials were subjected to electrochemical characterization through cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS) studies with 6 M KOH as the supporting electrolyte. For NiMoO4.nH2O, a maximum specific capacitance of 161 F g-1 was obtained at 5 A g-1 current density, accompanied with an energy density of 4.53 W h kg-1 at a steady power delivery rate of 1125 W kg-1. The high utility of the pseudocapacitive NiMoO4.nH2O was achieved in its graphene
A weak-light-responsive TiO2/g-C3N4 composite film: photocatalytic activity under low-intensity light irradiation.

Science.gov (United States)

Wang, Peifang; Guo, Xiang; Rao, Lei; Wang, Chao; Guo, Yong; Zhang, Lixin

2018-05-10

A TiO 2 /g-C 3 N 4 composite photocatalytic film was prepared by in situ synthesis method and its photocatalytic capability under weak-visible-light condition was studied. The co-precursor with different ratio of melamine and TiO 2 sol-gel precursor were treated using ultrasonic mixing, physical deposition, and co-sintering method to form the smooth, white-yellow, and compact TiO 2 /g-C 3 N 4 composite films. The prepared TiO 2 /g-C 3 N 4 materials were characterized by SEM, TEM, EDS, XRD, BET, VBXPS, and UV-vis diffuse reflectance spectra. The results of composite showed that TiO 2 and g-C 3 N 4 have close interfacial connections which are favorable to charge transfer between these two semiconductors with suitable band structure, g-C 3 N 4 retard the anatase-to-rutile phase transition of TiO 2 significantly, the specific surface area were increased with g-C 3 N 4 ratio raised. Under weak-light irradiation, composite films photocatalytic experiments exhibited RhB removal efficiency approaching 90% after three recycles. Powders suspension degradation experiments revealed the removal efficiency of TiO 2 /g-C 3 N 4 (90.8%) was higher than pure TiO 2 (52.1%) and slightly lower than pure g-C 3 N 4 (96.6%). By control experiment, the enhanced photocatalysis is ascribed to the combination of TiO 2 and g-C 3 N 4 , which not only produced thin films with greater stability but also formed heterojunctions that can be favorable to charge transfer between these two semiconductors with suitable band structure. This study presents the potential application of photocatalytic film in the wastewater treatment under weak-light situation.
The temperature dependences of the N2+ + N2 → N4+ and O2+ + O2 → O4+ association reactions

International Nuclear Information System (INIS)

Boehringer, H.; Arnold, F.; Smith, D.; Adams, N.G.

1983-01-01

The temperature dependencies of three body association reactions have been investigated in attempts to elucidate the mechanisms of ion-molecule association. The variation with temperature of the three-body rate coefficients is described usually as a power law k approximately Tsup(-n). Experience has shown that with measurements over limited temperature ranges as with previous methods the derived coefficients n are wrong and measurements over large temperature ranges are desirable. The selected ion flow-tube and the drift tube methods developed in Birmingham and Heidelberg provide measurements over (overlapping) wide temperature rang. In collaboration of the Birmingham and the Heidelberg group the He stabilized reactions N 2 + + N 2 + He → N 4 + + He and O 2 + + O 2 + He → O 4 + + He reactions over 30 to 600 deg K. A power law dependence is found above 100 K. The temperature dependencies of the rate constants are interpred and used as a critical test of recent theories of association reactions by D.R. Bates and E. Herbst. (G.Q.)
The vibration-rotation-tunneling levels of N2-H2O and N2-D2O

Science.gov (United States)

Wang, Xiao-Gang; Carrington, Tucker

2015-07-01

In this paper, we report vibration-rotation-tunneling levels of the van der Waals clusters N2-H2O and N2-D2O computed from an ab initio potential energy surface. The only dynamical approximation is that the monomers are rigid. We use a symmetry adapted Lanczos algorithm and an uncoupled product basis set. The pattern of the cluster's levels is complicated by splittings caused by H-H exchange tunneling (larger splitting) and N-N exchange tunneling (smaller splitting). An interesting result that emerges from our calculation is that whereas in N2-H2O, the symmetric H-H tunnelling state is below the anti-symmetric H-H tunnelling state for both K = 0 and K = 1, the order is reversed in N2-D2O for K = 1. The only experimental splitting measurements are the D-D exchange tunneling splittings reported by Zhu et al. [J. Chem. Phys. 139, 214309 (2013)] for N2-D2O in the v2 = 1 region of D2O. Due to the inverted order of the split levels, they measure the sum of the K = 0 and K = 1 tunneling splittings, which is in excellent agreement with our calculated result. Other splittings we predict, in particular those of N2-H2O, may guide future experiments.
Indirect N2O emission due to atmospheric N deposition for the Netherlands

International Nuclear Information System (INIS)

Denier van der Gon, H.; Bleeker, A.

2005-10-01

Nitrous oxide (N2O) is a potent greenhouse gas produced in soils and aquatic systems. The UNFCCC requires participants to report 'indirect' N2O emissions, following from agricultural N losses to ground- and surface water and N deposition on (other) ecosystems due to agricultural sources. Indirect N2O emission due to atmospheric N deposition is presently not reported by the Netherlands. In this paper, we quantify the consequences of various tiers to estimate indirect N2O due to deposition for a country with a high agricultural N use and discuss the reliability and potential errors in the IPCC methodology. A literature review suggests that the current IPCC default emission factor for indirect N2O from N deposition is underestimated by a factor 2. Moreover, considering anthropogenic N emissions from agriculture only and not from e.g., traffic and industry, results in further underestimation of indirect N2O emissions. We calculated indirect N2O emissions due to Dutch anthropogenic N emissions to air by using official Dutch N emission data as input in an atmospheric transport and deposition model in combination with land use databases. Next, land use-specific emission factors were used to estimate the indirect N2O emission. This revealed that (1) for some countries, like the Netherlands, most agricultural N emitted will be deposited on agricultural soils, not on natural ecosystems and, (2) indirect N2O emissions are at least 20% higher because more specific emission factors can be applied that are higher than the IPCC default. The results suggest that indirect N2O emission due to deposition is underestimated in current N2O budgets
Production of N₂O in soil during decomposition of dead yeast cells with different spatial distributions

DEFF Research Database (Denmark)

Ambus, P.

1996-01-01

Production and sources of N2O were determined in soil columns amended with autoclaved yeast cells either mixed into or added as 0.5 cm(3) lumps to the soil in combination with no or 200 mu g NO3--Ng(-1). At four occasions over a two-week study period, subsets of cores were measured for N2O...... production during 4-hour incubations under atmospheres of ambient air, 10 Pa of C2H2, and N-2, respectively. Denitrification enzyme activity (DEA) was assessed in subsamples of cores that had been incubated continuously under air. Autoclaved yeast provided a C-source readily available for denitrifying...

Surface modification of TiO2 with g-C3N4 for enhanced UV and visible photocatalytic activity

International Nuclear Information System (INIS)

Lei, Juying; Chen, Ying; Shen, Fan; Wang, Lingzhi; Liu, Yongdi; Zhang, Jinlong

2015-01-01

Highlights: • g-C 3 N 4 /TiO 2 was prepared by a one-step preparation under mild conditions. • Photocatalysts showed excellent activity under both UV and visible light. • A neat surface modification process is proved, excluding influence of N doping. • Two photocatalytic mechanisms under different wavelengths are proposed. • A wide range of available wavelengths would greatly improve practicability of TiO 2 . - Abstract: g-C 3 N 4 modified TiO 2 composites were prepared through a simple calcination process of anatase and cyanamide. The as-prepared samples were characterized by X-ray diffraction (XRD), diffuse reflectance spectrophotometry (DRS), fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), thermogravimetry differential thermal analysis (TG–DTA) and X-ray photoelectron spectroscopy (XPS), proving a successful modification of TiO 2 with g-C 3 N 4 . Photodegradation of acid orange 7 (AO7) was used to evaluate the photocatalytic activities of the composites, showing excellent activity of them under both visible and UV light. In addition, base treatment was then introduced to investigate the interaction between g-C 3 N 4 and TiO 2 . After removing the g-C 3 N 4 modified on TiO 2 by base, no nitrogen doping is found in TiO 2 lattice, demonstrating the g-C 3 N 4 was surface attached on TiO 2 and attributing all improvement of photocatalytic activity of g-C 3 N 4 /TiO 2 composite to the synergy between the two semiconductors
Poly[[μ2-2,2′-diethyl-1,1′-(butane-1,4-diyldiimidazole-κ2N3:N3′](μ2-5-hydroxyisophthalato-κ2O1:O3zinc

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Ying-Ying Liu

2011-11-01

Full Text Available In the title coordination polymer, [Zn(C8H4O5(C14H22N4]n, the ZnII cation is coordinated by an O2N2 donor set in a distorted tetrahedral geometry. The ZnII ions are linked by μ2-OH-bdc (OH-H2bdc = 5-hydroxyisophthalic acid and bbie ligands [bbie = 2,2′-diethyl-1,1′-(butane-1,4-diyldiimidazole], forming a two-dimensional layer parallel to the ab plane. The layers are further connected through intermolecular C—H...O and O—H...O hydrogen bonds, forming a three-dimensional supramolecular structure. In the bbie ligand, the two C atoms in the ethyl group are each disordered over two positions with a site-occupancy ratio of 0.69:0.31.
Octa-akis(4-amino-pyridine)-1κN,2κN-aqua-2κO-μ-carbonato-1:2κO,O':O''-dinickel(II) dichloride penta-hydrate.

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Fun, Hoong-Kun; Sinthiya, A; Jebas, Samuel Robinson; Ravindran Durai Nayagam, B; Alfred Cecil Raj, S

2008-10-18

In the title compound, [Ni(2)(CO(3))(C(5)H(6)N(2))(8)(H(2)O)]Cl(2)·5H(2)O, one of the the Ni(II) ions is six-coordinated in a distorted octa-hedral geometry, with the equatorial plane defined by four pyridine N atoms from four amino-pyridine ligands, the axial positions being occupied by one water O and a carbonate O atom. The other Ni(II) ion is also six-coordinated, by four other pyridine N atoms from four other amino-pyridine ligands and two carbonate O atoms to complete a distorted octa-hedral geometry. In the crystal structure, mol-ecules are linked into an infinite three-dimensional network by O-H⋯O, N-H⋯Cl, N-H⋯O, O-H⋯N, C-H⋯O, C-H⋯N and C/N-H⋯π inter-actions involving the pyridine rings.
Toxic effect of Cr(VI) in presence of n-TiO2 and n-Al2O3 particles towards freshwater microalgae.

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Dalai, Swayamprava; Pakrashi, Sunandan; Bhuvaneshwari, M; Iswarya, V; Chandrasekaran, N; Mukherjee, Amitava

2014-01-01

The reactivity and toxicity of the soluble toxicants in the presence of the engineered nanomaterials is not well explored. In this study, the probable effects of TiO2 and Al2O3 nanoparticles (n-TiO2, n-Al2O3) on the toxicity of Cr(VI) were assessed with the dominant freshwater algae, Scenedesmus obliquus, in a low range of exposure concentrations (0.05, 0.5 and 1μg/mL). In the presence of 0.05μg/mL n-TiO2, the toxicity of Cr(VI) decreased considerably, which was presumably due to the Cr(VI) adsorption on the nanoparticle surface leading to its aggregation and precipitation. The elevated n-TiO2 concentrations (0.5 and 1μg/mL) did not significantly influence Cr(VI) bio-availability, and a dose dependent toxicity of Cr(VI) was observed. On the other hand, n-Al2O3 did not have any significant effect on the Cr(VI) toxicity. The microscopic observations presented additional information on the morphological changes of the algal cells in the presence of the binary toxicants. The generation of reactive oxygen species (ROS) suggested contribution of oxidative stress on toxicity and LDH release confirmed membrane permeability of algal cells upon stress. Copyright © 2013 Elsevier B.V. All rights reserved.
Self-assembled hierarchical direct Z-scheme g-C3N4/ZnO microspheres with enhanced photocatalytic CO2 reduction performance

Science.gov (United States)

Nie, Ning; Zhang, Liuyang; Fu, Junwei; Cheng, Bei; Yu, Jiaguo

2018-05-01

Photocatalytic reduction of CO2 into hydrocarbon fuels has been regarded as a promising approach to ease the greenhouse effect and the energy shortage. Herein, an electrostatic self-assembly method was exploited to prepare g-C3N4/ZnO composite microsphere. This method simply utilized the opposite surface charge of each component, achieving a hierarchical structure with intimate contact between them. A much improved photocatalytic CO2 reduction activity was attained. The CH3OH production rate was 1.32 μmol h-1 g-1, which was 2.1 and 4.1 times more than that of the pristine ZnO and g-C3N4, respectively. This facile design bestowed the g-C3N4/ZnO composite an extended light adsorption caused by multi-light scattering effect. It also guaranteed the uniform distribution of g-C3N4 nanosheets on the surface of ZnO microspheres, maximizing their advantage and synergistic effect. Most importantly, the preeminent performance was proposed and validated based on the direct Z-scheme. The recombination rate was considerably suppressed. This work features the meliority of constructing hierarchical direct Z-scheme structures in photocatalytic CO2 reduction reactions.
Visible-light-driven g-C{sub 3}N{sub 4}/Ti{sup 3+}-TiO{sub 2} photocatalyst co-exposed {0 0 1} and {1 0 1} facets and its enhanced photocatalytic activities for organic pollutant degradation and Cr(VI) reduction

Energy Technology Data Exchange (ETDEWEB)

Lu, Dan; Zhang, Gaoke, E-mail: gkzhang@whut.edu.cn; Wan, Zhen

2015-12-15

Graphical abstract: Schematic illustration for the mechanism of photo-generated charge carrier transfers in g-C{sub 3}N{sub 4}/Ti{sup 3+}-TiO{sub 2} photocatalyst and its visible-light photocatalytic performance. - Highlights: • g-C{sub 3}N{sub 4}/Ti{sup 3+}-TiO{sub 2} composite co-exposed {0 0 1} and {1 0 1} facets of TiO{sub 2} was synthesized. • RhB and Cr(VI) aqueous solutions were used to evaluate the photocatalytic activities. • h{sup +} and ·O{sub 2}{sup −} are the critical reactive species in the degradation of RhB solution. • Surface heterojunction of co-exposed {1 0 1} and {0 0 1} facets improve the separation. - Abstract: Novel g-C{sub 3}N{sub 4/}Ti{sup 3+}-TiO{sub 2} photocatalyst co-exposed {0 0 1} and {1 0 1} facets of TiO{sub 2} was synthesized via a hydrothermal–sonication assisted strategy. The photocatalytic activities of the as-obtained photocatalyst were evaluated by the degradation of rhodamine B (RhB) and the reduction of Cr(VI) under visible-light irradiation. It was found that the g-C{sub 3}N{sub 4}/Ti{sup 3+}-TiO{sub 2} composites with 6 wt% g-C{sub 3}N{sub 4} exhibited the highest visible-light photocatalytic efficiency, which is also higher than the pure g-C{sub 3}N{sub 4} and Ti{sup 3+}-TiO{sub 2}. A possible photocatalytic mechanism was discussed on the basis of the theoretical analyses and scavenger experiments. Results show that holes (h{sup +}) and superoxide anions (·O{sub 2}{sup −}) reactive species participated in the degradation of RhB solution over the g-C{sub 3}N{sub 4}/Ti{sup 3+}-TiO{sub 2} composites. The enhanced photocatalytic activities of g-C{sub 3}N{sub 4}/Ti{sup 3+}-TiO{sub 2} composites can be attributed to the wide optical adsorption of g-C{sub 3}N{sub 4} and Ti{sup 3+} as well as the effectively separation and transportation of photo-generated electrons and holes pairs, which was resulted from the surface heterojunction between the g-C{sub 3}N{sub 4} and Ti{sup 3+}-TiO{sub 2} nanosheets co-exposed {1
Magnetically Separable Fe2O3/g-C3N4 Nanocomposites with Cocoon-Like Shape: Magnetic Properties and Photocatalytic Activities

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Yu, Xiaojia; Yang, Xiaoyu; Li, Guang

2018-01-01

We report magnetically separable Fe2O3/g-C3N4 nanocomposites as a photocatalyst under visible-light irradiation in this study. The Fe2O3/g-C3N4 nanocomposites were synthesized through a two-step hydrothermal method. The Fe2O3 with cocoon-like shape was obviously dispersed on the surface of g-C3N4 with porous and layered nanostructure as seen from micrographs of the particles. Furthermore, the magnetic conversion of the samples was studied via vibrating sample magnetometer technology. It was found that the saturated magnetization Ms of the Fe2O3/g-C3N4 nanoparticles obviously decreased in the presence of g-C3N4, and the photocatalytic activity of the samples investigated by degrading Rhodamine B suggested that the Fe2O3/g-C3N4 photocatalyst was prior to the pure Fe2O3 and g-C3N4 samples. In addition, the magnetically separable ability of Fe2O3/g-C3N4 nanocomposites was efficiently exhibited by an external magnet.
Contribution of vehicle exhaust to the global N2O budget

International Nuclear Information System (INIS)

Becker, K.H.; Loerzer, J.C.; Kurtenbach, R.; Wiesen, P.; Jensen, T.E.; Wallington, T.J.

2000-01-01

Assessment of the impact of vehicle emissions on the global environment requires accurate data concerning nitrous oxide (N 2 O) emissions. We report herein 'real world' N 2 O emissions from road vehicles in a tunnel in Wuppertal, Germany, together with 'laboratory' emission measurements conducted at the Ford Motor Company using a chassis dynamometer with a standard driving cycle for 26 different cars and trucks. Consistent results were obtained from both approaches suggesting that a good approximation of the average emission factor (g N 2 O/g CO 2 )=(4±2) x 10 -5 . This corresponds to an emission rate of 11-5 mg N 2 O/km for vehicles with fuel economies of 12-6 1/100 km (20-40 miles/US gallon). N 2 O emissions from vehicles have a global warming impact, which is 1-2% of that of the CO 2 emissions from vehicles. We estimate an annual emission of (0.12±0.06) Tg yr -1 of N 2 O (0.08±0.04 Tg N yr -1 ) from the global vehicle fleet which represents 1-4% of the atmospheric growth rate of this species. These results update and supersede our previous study of N 2 O emissions from vehicles. (author)
The cocrystal μ-oxalato-κ4O1,O2:O1′,O2′-bis(aqua(nitrato-κO{[1-(2-pyridyl-κNethylidene]hydrazine-κN}copper(II μ-oxalato-κ4O1,O2:O1′,O2′-bis((methanol-κO(nitrato-κO{[1-(2-pyridyl-κNethylidene]hydrazine-κN}copper(II (1/1

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Youssouph Bah

2008-09-01

Full Text Available The title cocrystal, [Cu2(C2O4(NO32(C7H9N32(H2O2][Cu2(C2O4(NO32(C7H9N32(CH4O2], is a 1:1 cocrystal of two centrosymmetric CuII complexes with oxalate dianions and Schiff base ligands. In each molecule, the CuII centre is in a distorted octahedral cis-CuN2O4 environment, the donor atoms of the N,N′-bidentate Schiff base ligand and the bridging O,O′-bidentate oxalate group lying in the equatorial plane. In one molecule, a monodentate nitrate anion and a water molecule occupy the axial sites, and in the other, a monodentate nitrate anion and a methanol molecule occupy these sites. In the crystal structure, intermolecular N—H...O, O—H...O and N—H...N hydrogen bonds link the molecules into a network. Weak intramolecular N—H...O interactions are also observed.
Hierarchical Honeycomb Br-, N-Codoped TiO2 with Enhanced Visible-Light Photocatalytic H2 Production.

Science.gov (United States)

Zhang, Chao; Zhou, Yuming; Bao, Jiehua; Sheng, Xiaoli; Fang, Jiasheng; Zhao, Shuo; Zhang, Yiwei; Chen, Wenxia

2018-06-06

The halogen elements modification strategy of TiO 2 encounters a bottleneck in visible-light H 2 production. Herein, we have for the first time reported a hierarchical honeycomb Br-, N-codoped anatase TiO 2 catalyst (HM-Br,N/TiO 2 ) with enhanced visible-light photocatalytic H 2 production. During the synthesizing process, large amounts of meso-macroporous channels and TiO 2 nanosheets were fabricated in massive TiO 2 automatically, constructing the hierarchical honeycomb structure with large specific surface area (464 m 2 g -1 ). cetyl trimethylammonium bromide and melamine played a key role in constructing the meso-macroporous channels. Additionally, HM-Br,N/TiO 2 showed a high visible-light H 2 production rate of 2247 μmol h -1 g -1 , which is far more higher than single Br- or N-doped TiO 2 (0 or 63 μmol h -1 g -1 , respectively), thereby demonstrating the excellent synergistic effects of Br and N elements in H 2 evolution. In HM-Br,N/TiO 2 catalytic system, the codoped Br-N atoms could reduce the band gap of TiO 2 to 2.88 eV and the holes on acceptor levels (N acceptor) can passivate the electrons on donor levels (Br donor), thereby preventing charge carriers recombination significantly. Furthermore, the proposed HM-Br,N/TiO 2 fabrication strategy had a wide range of choices for N source (e.g., melamine, urea, and dicyandiamide) and it can be applied to other TiO 2 materials (e.g., P25) as well, thereby implying its great potential application in visible-light H 2 production. Finally, on the basis of experimental results, a possible photocatalytic H 2 production mechanism for HM-Br,N/TiO 2 was proposed.
Fabrication of flower-like direct Z-scheme β-Bi2O3/g-C3N4 photocatalyst with enhanced visible light photoactivity for Rhodamine B degradation

Science.gov (United States)

Zhang, Liping; Wang, Guohong; Xiong, Zhenzhong; Tang, Hua; Jiang, Chuanjia

2018-04-01

A combined hydrothermal-calcination approach is developed to synthesize hierarchical β-Bi2O3/g-C3N4 direct Z-scheme photocatalyst with enhanced visible light photoactivity for Rhodamine B (RhB) degradation. First, Bi2O2CO3 microflowers were hydrothermally prepared using Bi(NO3)3·5H2O as feedstocks, and then a series of β-Bi2O3/g-C3N4 direct Z-scheme photocatalysts were synthesized via a facile calcination method using Bi2O2CO3 and g-C3N4 as precursors. The samples were systematically characterized by various characterization technologies including X-ray diffraction, scanning and transmission electron microscopes, Fourier transform infrared spectroscopy and N2 absorption-desorption equipment. It was found that the g-C3N4 content in the precursors played a key role in affecting the photocatalytic activity of the final products. The β-Bi2O3/g-C3N4 heterojunction exhibited higher photocatalytic activity than single active components (β-Bi2O3 and g-C3N4), indicating the presence of a synergistic effect between two active components in β-Bi2O3/g-C3N4 heterojunction. Among all as-prepared catalysts, the 70 wt.% g-C3N4/Bi2O2CO3 exhibits the highest activity for RhB degradation, and the apparent reaction rate constant k (42.2 × 10-3 min-1) is 3.1 and 1.7 times as high as that of pure β-Bi2O3 (13.5 × 10-3 min-1) and g-C3N4 (25.2 × 10-3 min-1), respectively. The enhanced photocatalytic performance of β-Bi2O3/g-C3N4 heterostructure photocatalysts is mainly due to the high surface area, closely contacted interfaces between the β-Bi2O3 and g-C3N4 component, and the formation of direct Z-scheme structure in the β-Bi2O3/g-C3N4 composites.
Interface engineered construction of porous g-C3N4/TiO2 heterostructure for enhanced photocatalysis of organic pollutants

Science.gov (United States)

Li, Ya-Nan; Chen, Zhao-Yang; Wang, Min-Qiang; Zhang, Long-zhen; Bao, Shu-Juan

2018-05-01

A porous g-C3N4/TiO2 with hierarchical heterostructure has been successfully fabricated through a in situ assembling of small needle-like TiO2 on the surface of ultrathin g-C3N4 sheets. The ultrathin g-C3N4 sheets with carbon vacancies and rich hydroxyl groups were found to facilitate the nucleation and in situ growth of TiO2 and also to modulate the surface chemical activity of the g-C3N4/TiO2 hierarchical heterostructure. The as-designed photocatalytic heterojunction degraded Acid Orange with 82% efficiency after 10 min under simulated solar light, and possessed excellent cycle stability. Relative physical characterizations and photochemical experiments reveal that engineering the interface/surface of g-C3N4 plays a vital role in effectively constructing heterostructures of g-C3N4/TiO2, thus realizing efficient photoinduced electron-hole separation during photocatalytic process.
(2-Formyl-6-methoxyphenolato-κ2O1,O2(perchlorato-κO(1,10-phenanthroline-κ2N,N′copper(II

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Zhi-Yong Wu

2008-05-01

Full Text Available In the title molecule, [Cu(C8H7O3(ClO4(C12H8N2], the CuII ion is five-coordinated by two N atoms [Cu—N = 1.995 (3 and 2.022 (3 Å] from a 1,10-phenanthroline ligand, two O atoms [Cu—O = 1.908 (2 and 1.927 (2 Å] from an o-vanillin ligand and one O atom [Cu—O = 2.510 (3 Å] from a perchlorate anion in a distorted square-pyramidal geometry. Three O atoms of the perchlorate anion are rotationally disordered between two orientations, with occupancies of 0.525 (13 and 0.475 (13. In the crystal structure, two molecules related by a centre of symmetry are paired in such a way that the phenolate O atom from one molecule completes the distorted octahedral Cu coordination in another molecule [Cu...O = 2.704 (2 Å].
(μ-3-Acetyl-5-carboxylato-4-methylpyrazolido-1:2κ4N2,O3:N1,O5-μ-chlorido-tetrapyridine-1κ2N,2κ2N-chlorido-1κCl-dicopper(II propan-2-ol solvate

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Sergey Malinkin

2009-10-01

Full Text Available The title compound, [Cu2(C7H6N2O3Cl2(C5H5N4]·C3H8O, is a binuclear pyrazolate complex, in which the two CuII atoms have different coordination numbers and are connected by a bridging Cl atom. One CuII atom has a distorted square-pyramidal coordination environment formed by two pyridine N atoms, one bridging Cl atom and an N,O-chelating pyrazolate ligand. The other CuII atom adopts an octahedral geometry defined by two pyridine N atoms at the axial positions, two Cl atoms and the coordinated pyrazolate ligand in the equatorial plane. An O—H...O hydrogen bond connects the complex molecules and propan-2-ol solvent molecules into pairs. These pairs form columns along the a axis.
[μ-N,N′-Bis(2-aminoethylethane-1,2-diamine-κ4N1,N1′:N2,N2′]bis{[N,N′-bis(2-aminoethylethane-1,2-diamine-κ4N,N′,N′′,N′′′]cadmium} tetrakis(perchlorate

Directory of Open Access Journals (Sweden)

Hamid Goudarziafshar

2012-09-01

Full Text Available The centrosymmetric dinuclear cadmium title complex, [Cd2(C6H18N43](ClO44, was obtained by the reaction of N,N′-bis(2-aminoethylethane-1,2-diamine (trien with Cd(NO32·4H2O and sodium perchlorate in methanol. The CdII cation is coordinated by four N atoms of a non-bridging trien ligand and by two N atoms of a bridging trien ligand in a slightly distorted octahedral coordination geometry. The bridging ligand shares another two N atoms with a neighboring symmetry-equivalent CdII cation. The structure displays C—H...O and N—H...O hydrogen bonding. The perchlorate anion is disordered over two sets of sites in a 0.854 (7: 0.146 (7 ratio.
Structure and stability of small Li2 +(X2Σ+ g )-Xen (n = 1-6) clusters

Science.gov (United States)

Saidi, Sameh; Ghanmi, Chedli; Berriche, Hamid

2014-04-01

We have studied the structure and stability of the Li2 +(X2Σ+ g )Xe n ( n = 1-6) clusters for special symmetry groups. The potential energy surfaces of these clusters, are described using an accurate ab initio approach based on non-empirical pseudopotential, parameterized l-dependent polarization potential and analytic potential forms for the Li+Xe and Xe-Xe interactions. The pseudopotential technique has reduced the number of active electrons of Li2 +(X2Σ+ g )-Xe n ( n = 1-6) clusters to only one electron, the Li valence electron. The core-core interactions for Li+Xe are included using accurate CCSD(T) potential fitted using the analytical form of Tang and Toennies. For the Xe-Xe potential interactions we have used the analytical form of Lennard Jones (LJ6 - 12). The potential energy surfaces of the Li2 +(X2Σ+ g )Xe n ( n = 1-6) clusters are performed for a fixed distance of the Li2 +(X2Σ+ g ) alkali dimer, its equilibrium distance. They are used to extract information on the stability of the Li2 +(X2Σ+ g Xe n ( n = 1-6) clusters. For each n, the stability of the different isomers is examined by comparing their potential energy surfaces. Moreover, we have determined the quantum energies ( D 0), the zero-point-energies (ZPE) and the ZPE%. To our best knowledge, there are neither experimental nor theoretical works realized for the Li2 +(X2Σ+ g Xe n ( n = 1-6) clusters, our results are presented for the first time.
Double Z-scheme ZnO/ZnS/g-C3N4 ternary structure for efficient photocatalytic H2 production

Science.gov (United States)

Dong, Zhifang; Wu, Yan; Thirugnanam, Natarajan; Li, Gonglin

2018-02-01

In the present work, a novel ZnO/ZnS/g-C3N4 ternary nanocomposite with double Z-scheme heterojunction has been designed via a two-step facile chemical conversion route. The spherical ZnS nanoparticles were uniformly loaded onto ZnO nanoflowers surface. And then the ZnO/ZnS nanocomposite was further hybridized with g-C3N4 nanosheets. Ternary ZnO/ZnS/g-C3N4 nanocomposite displays the largest specific surface area (about 76.2 m2/g), which provides plentiful activated sites for photocatalytic reaction. Furthermore, the ternary material exhibits the highest methylene blue photodegradation rate of about 0.0218 min-1 and the optimum photocatalytic H2 production (1205 μmol/g) over water splitting at 4 h under solar light irradiation. Moreover, it showed the highest photocurrent effect and the minimum charge-transfer resistance. These results implied that the higher photoactivity of ZnO/ZnS/g-C3N4 nanocomposite could be attributed to the multi-steps charge transfer and effective electron-hole separation in the double Z-scheme system.
Multiple anion...π interactions in tris(1,10-phenanthroline-κ(2)N,N')iron(II) bis[1,1,3,3-tetracyano-2-(2-hydroxyethyl)propenide] monohydrate.

Science.gov (United States)

Setifi, Zouaoui; Domasevitch, Konstantin V; Setifi, Fatima; Mach, Pavel; Ng, Seik Weng; Petříček, Vaclav; Dušek, Michal

2013-11-01

In the ionic structure of the title compound, [Fe(C12H8N2)3](C9H5N4O2)2·H2O, the octahedral tris-chelate [Fe(phen)3](2+) dications [Fe-N = 1.9647 (14)-1.9769 (14) Å; phen is 1,10-phenathroline] afford one-dimensional chains by a series of slipped π-π stacking interactions [centroid-to-centroid distances = 3.792 (3) and 3.939 (3) Å]. The 1,1,3,3-tetracyano-2-(2-hydroxyethyl)propenide anions, denoted tcnoetOH(-), reveal an appreciable delocalization of π-electron density, involving the central propenide [C-C = 1.383 (3)-1.401 (2) Å] fragment and four nitrile groups, and this is also supported by density functional theory (DFT) calculations at the B97D/6-311+G(2d,2p) level. Primary noncovalent inter-moiety interactions comprise conventional O-H...O(N) and weak C-H...O(N) hydrogen bonding [O...O(N) = 2.833 (2)-3.289 (5) Å and C...O(N) = 3.132 (2)-3.439 (2) Å]. The double anion...π interaction involving a nitrile group of tcnoetOH(-) and two cis-positioned pyridine rings (`π-pocket') of [Fe(phen)3](2+) [N...centroid = 3.212 (2) and 3.418 (2) Å] suggest the relevance of anion...π stackings for charge-diffuse polycyanoanions and common M-chelate species.
Fabrication of AgFeO{sub 2}/g-C{sub 3}N{sub 4} nanocatalyst with enhanced and stable photocatalytic performance

Energy Technology Data Exchange (ETDEWEB)

Tang, Dandan [School of Resources and Environmental Engineering, Wuhan University of Technology, 122 Luoshi Road, Wuhan 430070 (China); Hubei Provincial Collaborative Innovation Center for High Efficient Utilization of Vanadium Resources, Wuhan 430070 (China); Zhang, Gaoke, E-mail: gkzhang@whut.edu.cn [School of Resources and Environmental Engineering, Wuhan University of Technology, 122 Luoshi Road, Wuhan 430070 (China); Hubei Provincial Collaborative Innovation Center for High Efficient Utilization of Vanadium Resources, Wuhan 430070 (China)

2017-01-01

Highlights: • AgFeO{sub 2}/g-C{sub 3}N{sub 4} nanocatalyst was synthesized via a facile precipitation method. • The composite displays superior e{sup ∧}/h{sup +} pair separation compared to AgFeO{sub 2} and g-C{sub 3}N{sub 4}. • The composite shows high and stable photocatalytic activity both in water and air. • The active h{sup +} plays the dominate role in the degradation process. - Abstract: This work reported a novel AgFeO{sub 2}/g-C{sub 3}N{sub 4} composite with enhanced photocatalytic activity, which was fabricated by a simple precipitation method. The g-C{sub 3}N{sub 4} sheets with thickness of 2• 4 nm were successfully loaded on the surface of the AgFeO{sub 2} particles. As compared to pure AgFeO{sub 2} and pure g-C{sub 3}N{sub 4}, the as-prepared AgFeO{sub 2}/g-C{sub 3}N{sub 4} photocatalysts exhibited superior absorption in the visible-light region and displayed promising visible-light photocatalytic performance in the degradation of organic contaminations both in water and in air. About 94% of Acid red G (ARG) can be degraded by the optimized AgFeO{sub 2}/g-C{sub 3}N{sub 4} sample, which is ∱/47.5 and ∱/410.7 times higher than that by pure AgFeO{sub 2} and pure g-C{sub 3}N{sub 4}, respectively. Meanwhile, it can also effectively degrade ∱/487% of gaseous formaldehyde to CO{sub 2} within 9 h. The enhanced photocatalytic property and stability of the AgFeO{sub 2}/g-C{sub 3}N{sub 4} composite can be attributed to its specific nanostructure, effective electron-hole separation and the formation of Z-scheme heterostructure between AgFeO{sub 2} and g-C{sub 3}N{sub 4}. This work could provide new and helpful insights into the photocatalytic application of Ag-based delafossite materials.
Hierarchical Cu2O foam/g-C3N4 photocathode for photoelectrochemical hydrogen production

Science.gov (United States)

Ma, Xinzhou; Zhang, Jingtao; Wang, Biao; Li, Qiuguo; Chu, Sheng

2018-01-01

Solar photoelectrochemical (PEC) hydrogen production is a promising way for solving energy and environment problems. Earth-abundant Cu2O is a potential light absorber for PEC hydrogen production. In this article, hierarchical porous Cu2O foams are prepared by thermal oxidation of the electrochemically deposited Cu foams. PEC performances of the Cu2O foams are systematically studied and discussed. Benefiting from their higher light harvesting and more efficient charge separation, the Cu2O foams demonstrate significantly enhanced photocurrents and photostability compared to their film counterparts. Moreover, by integrating g-C3N4, hierarchical Cu2O foam/g-C3N4 composites are prepared with further improved photocurrent and photostability, appearing to be potential photocathodes for solar PEC hydrogen production. This study may provide a new and useful insight for the development of Cu2O-based photocathodes for PEC hydrogen production.

Carbon/CuO nanosphere-anchored g-C3N4 nanosheets as ternary electrode material for supercapacitors

Science.gov (United States)

Vattikuti, S. V. Prabhakar; Reddy, B. Purusottam; Byon, Chan; Shim, Jaesool

2018-06-01

Novel electrode materials for supercapacitors comprised of carbon and copper oxide (CuO) nanospheres on graphitic carbon nitride (g-C3N4) nanosheets, denoted as C/CuO@g-C3N4 are self-assembled via a one-step co-pyrolysis decomposition method. The pure g-C3N4 and C/CuO@g-C3N4 were confirmed by powder X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), thermal gravimetric and differential thermal analysis (TG-DTA), X-ray photoelectron spectroscopy (XPS), N2 adsorption/desorption studies and Fourier-transform infrared spectroscopy (FTIR). The specific capacitance was 247.2 F g-1 in 0.5 M NaOH at a current density of 1 A g-1, and more than 92.1% of the capacitance was retained after 6000 cycles. The property enhancement was ascribed to the synergistic effects of the three components in the composite. These results suggest that C/CuO@g-C3N4 possessed an excellent cyclic stability with respect to their capacity performance as electrode materials.
Epitaxial growth of mixed conducting layered Ruddlesden–Popper La{sub n+1}Ni{sub n}O{sub 3n+1} (n = 1, 2 and 3) phases by pulsed laser deposition

Energy Technology Data Exchange (ETDEWEB)

Wu, Kuan-Ting; Soh, Yeong-Ah; Skinner, Stephen J., E-mail: s.skinner@imperial.ac.uk

2013-10-15

Graphical abstract: - Highlights: • High quality epitaxial thin films of layered Ruddlesden–Popper nickelates were prepared. • For the first time this has been achieved by the PLD process. • n = 1, 2 and 3 films were successfully deposited on SrTiO{sub 3} and NdGaO{sub 3} substrates. • c-Axis oriented films were confirmed by XRD analysis. • In-plane and out-of-plane strain effects on lattice are discussed. - Abstract: Layered Ruddlesden–Popper phases of composition La{sub n+1}Ni{sub n}O{sub 3n+1} (n = 1, 2 and 3) have been epitaxially grown on SrTiO{sub 3} (0 0 1) or NdGaO{sub 3} (1 1 0) single crystal substrates using the pulsed laser deposition technique. X-ray diffraction analyses (θ/2θ, rocking curves, and φ-scans) and atomic force microscopy confirms the high-quality growth of the series of films with low surface roughness values (less than 1 nm). In particular, epitaxial growth of the higher order phases (n = 2 and 3) of lanthanum nickelate have been demonstrated for the first time.
Rational construction of Z-scheme Ag_2CrO_4/g-C_3N_4 composites with enhanced visible-light photocatalytic activity

International Nuclear Information System (INIS)

Luo, Jin; Zhou, Xiaosong; Ma, Lin; Xu, Xuyao

2016-01-01

Highlights: • Novel visible-light driven Ag_2CrO_4/g-C_3N_4 composites were synthesized. • Ag_2CrO_4/g-C_3N_4 exhibited enhanced visible-light photocatalytic activity. • The reasons for the enhanced photocatalytic activity were revealed. - Abstract: Novel visible-light driven Z-scheme Ag_2CrO_4/g-C_3N_4 composites with different contents of Ag_2CrO_4 were fabricated by a facile chemical precipitation method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance spectroscopy (UV-vis DRS), photoluminescence (PL) spectroscopy and photoelectrochemical measurements. Compared with individual g-C_3N_4 and Ag_2CrO_4, the Ag_2CrO_4/g-C_3N_4 composites displayed much larger photocatalytic activities for the photocatalytic degradation of methyl orange (MO) solution at room temperature under visible light irradiation (λ > 420 nm). Importantly, the optimum photodegradation rate constant of the Ag_2CrO_4/g-C_3N_4 composite at a theoretical weight content of 8.0% Ag_2CrO_4 for the photodegradation of MO was 0.0068 min"−"1, which was 5.7 and 4.3 times higher than that of pure g-C_3N_4 and Ag_2CrO_4, respectively. Such enormous enhancement in photocatalytic performance was predominantly ascribed to the efficient separation and transfer of photogenerated electrons and holes at the Ag_2CrO_4/g-C_3N_4 interface imparted through the Z-scheme electron transfer. Furthermore, radical trap experiments depicted that both the holes and superoxide radical anions were thought to dominate oxidative species of the Ag_2CrO_4/g-C_3N_4 composite for MO degradation under visible light irradiation. Ultimately, a tentative Z-scheme photodegradation mechanism was proposed. This work may be useful for the rational design of new types of Z-scheme photocatalysts and provide some illuminate insights into the Z-scheme transfer mechanism for application in energy
Structure and stability of nonstoichiometric cubic phase δ-NbN1.2(O,C)

International Nuclear Information System (INIS)

Shalaeva, E.V.; Mitrofanov, B.V.; Shveikin, G.P.

1996-01-01

The nonstoichiometric δ-niobium nitride with surplus content of nitrogen atoms and the NaCl-type structure (a=0.439 nm), i.e. δ-NbN 1.2 (O, C), is stabilized in epitaxial deposited films. The diffraction patterns of these films display intensive diffuse scattering with regular intensity vanishings in the form of plane regions in the vicinity of structural and superstructural reciprocal space points of the δ-phase and in the form of spherical surfaces in the neighbourhood of structural points. The analysis performed shows that this scattering can be associated with the presence of mixed-nature short-range order regions in the nonstoichiometric δ-NbN 1.2 (O, C) phase which are characterized by longitudinal uncorrelated atomic displacement waves, as well as by concentration-type waves. The ordered oxycarbonitride phase (X-phase) described in the first approximation by the cubic lattice with parameter a=0.392 nm is found to precipitate when annealing the films at T=873 K. It has been established that the diffuse scattering occurring in δ-NbN 1.2 (O, C) and the structure of short-range order regions exhibit certain correlation with the structure of the precipitated ordered phase - G 100 x ∼1.1G 100 δ = K 1 ; G 010 x ∼1.1G 010 δ = K 2 (where K 1 and K 2 are wave vectors of longitudinal atomic displacement waves characterizing short-range order). (orig.)
O2(b1∑+g) relaxation in active medium of oxygen-iodine laser

Science.gov (United States)

Tolstov, G. I.; Zagidullin, M. V.; Khvatov, N. A.; Medvedkov, I. A.; Mikheyev, P. A.

2018-04-01

Rate constants for the removal of O2 b1∑+g by collisions with O2, N2, CO2 and H2O have been determined at temperature 297 K. O2(b1 ∑+g) was excited by pulses from a tunable dye laser, and the deactivation kinetics were followed by observing the temporal behavior of the b1∑+g - X3∑-g fluorescence. The removal rate constants for CO2, N2 and H2O were not strongly dependent on temperature, and could be represented by the expressions kCO2=(1.8+/-0.05)×10-16 kN2=(2.2 +/- 0.2)×10-15, and kH2O=(6.12+/-0.67)×10-12 cm3 molecule-1 s-1. Rate constant for O2(b1∑+ ) removal by O2(X), being orders of magnitude lower, represented by the fitted expression kO2=(3.67 +/- 0.06)×10-17 cm3 molecule-1 s-1. All of the rate constants measured at room temperature were found to be in good agreement with previously reported values.
(3-Methylbenzonitrile-1κN-cis-tetrakis(μ-N-phenylacetamidato-1:2κ4N:O;1:2κ4O:N-dirhodium(II(Rh—Rh

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Cassandra T. Eagle

2014-08-01

Full Text Available The complex molecule of the title compound, [Rh2{N(C6H5COCH3}4(NCC7H7], has crystallographically-imposed mirror symmetry. The four acetamide ligands bridging the dirhodium core are arranged in a 2,2-cis manner with two N atoms and two O atoms coordinating to the unique RhII atom cis to one another. The Neq—Rh—Rh—Oeq torsion angles on the acetamide bridge are 0.75 (7 and 1.99 (9°. The axial nitrile ligand completes the distorted octahedral coordination sphere of one RhII atom and shows a nonlinear coordination, with an Rh—N—C bond angle of 162.8 (5°; the N—C bond length is 1.154 (7 Å.
Investigation of N2O Production from 266 and 532 nm Laser Flash Photolysis of O3/N2/O2 Mixtures

Science.gov (United States)

Estupinan, E. G.; Nicovich, J. M.; Li, J.; Cunnold, D. M.; Wine, P. H.

2002-01-01

Tunable diode laser absorption spectroscopy has been employed to measure the amount of N2O produced from laser flash photolysis of O3/N2/O2 mixtures at 266 and 532 nm. In the 532 nm photolysis experiments very little N2O is observed, thus allowing an upper limit yield of 7 x 10(exp -8) to be established for the process O3 + N2 yield N2O + O2, where O3 is nascent O3 that is newly formed via O(3P(sub J)) + O2 recombination (with vibrational excitation near the dissociation energy of O3). The measured upper limit yield is a factor of approx. 600 smaller than a previous literature value and is approximately a factor of 10 below the threshold for atmospheric importance. In the 266 nm photolysis experiments, significant N2O production is observed and the N2O quantum yield is found to increase linearly with pressure over the range 100 - 900 Torr in air bath gas. The source of N2O in the 266 nm photolysis experiments is believed to be the addition reaction O(1D(sub 2)) + N2 + M yields (k(sub sigma)) N2O + M, although reaction of (very short-lived) electronically excited O3 with N2 cannot be ruled out by the available data. Assuming that all observed N2O comes from the O(1D(sub 2)) + N2 + M reaction, the following expression describes the temperature dependence of k(sub sigma) (in its third-order low-pressure limit) that is consistent with the N2O yield data: k(sub sigma) = (2.8 +/- 0.1) x 10(exp -36)(T/300)(sup -(0-88+0.36)) cm(sup 6) molecule(sup -2)/s, where the uncertainties are 2(sigma) and represent precision only. The accuracy of the reported rate coefficients at the 95% confidence level is estimated to be 30 - 40% depending on the temperature. Model calculations suggest that gas phase processes initiated by ozone absorption of a UV photon represent about 1.4% of the currently estimated global source strength of atmospheric N2O. However, these processes could account for a significant fraction of the oxygen mass-independent enrichment observed in atmospheric N2O, and
Thermal expansion of superconducting phases Bi sub 2 Sr sub 2 Ca sub n-1 Cu sub n O sub 2n+2+. delta. with n=1,2,3. Termicheskoe rasshirenie sverkhprovodyashchikh faz Bi sub 2 Sr sub 2 Ca sub n-1 Cu sub n O sub 2n+2+. delta. s n=1,2,3

Energy Technology Data Exchange (ETDEWEB)

Zhurov, V V; Ivanov, S A [Nauchno-Issledovatel' skij Fiziko-Khimicheskij Inst., Moscow (USSR); Bush, A A; Romanov, B N [Moskovskij Inst. Radiotekhniki, Ehlektroniki i Avtomatiki, Moscow (USSR)

1990-10-01

Consideration is given to results of X-ray diffraction studies of temperature dependences of a{sub 0},c{sub 0} sublattice parameters of Bi{sub 2}Sr{sub 2}Ca{sub n-1}Cu{sub n}O{sub 2n+2+}{delta} superconducting phases with n=1,2,3 (2201, 2212, 2223) in 90-1000 K range. The obtained dependences are composed of some temperature linear sections, where values of thermal coefficients of linear expansion {alpha}{sub a}, {alpha}{sub c} were determined for all examined phases. During first heating of samples of 2212 phase a{sub 0}(T), c{sub 0}(T) dependences deviate in {approx equal}500-700 K range from linear ones till the occurence of a section with negative a{sub c}. After heating of 2212 phase up to T>{approx equal}700 K and cooling down to 300 K, a{sub 0},c{sub 0} parameters decrease by {approx equal}0.006 and 0.08 A respectively. Data on the effect of preparation method and thermal prehistory of 2212 samples and on relative content of calcium atoms in them for these anomalies were obtained. Some possible reasons of their occurence were analyzed.
A novel one-step strategy toward ZnMn2O4/N-doped graphene nanosheets with robust chemical interaction for superior lithium storage

International Nuclear Information System (INIS)

Wang, Dong; Zhou, Weiwei; Zhang, Yong; Wang, Yali; Wu, Gangan; Yu, Kun; Wen, Guangwu

2016-01-01

Ingenious hybrid electrode design, especially realized with a facile strategy, is appealing yet challenging for electrochemical energy storage devices. Here, we report the synthesis of a novel ZnMn 2 O 4 /N-doped graphene (ZMO/NG) nanohybrid with sandwiched structure via a facile one-step approach, in which ultrafine ZMO nanoparticles with diameters of 10–12 nm are well dispersed on both surfaces of N-doped graphene (NG) nanosheets. Note that one-step synthetic strategies are rarely reported for ZMO-based nanostructures. Systematical control experiments reveal that the formation of well-dispersed ZMO nanoparticles is not solely ascribed to the restriction effect of the functional groups on graphene oxide (GO), but also to the presence of ammonia. Benefitting from the synergistic effects and robust chemical interaction between ZMO nanoparticles and N-doped graphene nanosheets, the ZMO/NG hybrids deliver a reversible capacity up to 747 mAh g −1 after 200 cycles at a current density of 500 mA g −1 . Even at a high current density of 3200 mA g −1 , an unrivaled capacity of 500 mAh g −1 can still be retained, corroborating the good rate capability. (paper)
Construction of g-C_3N_4/Al_2O_3 hybrids via in-situ acidification and exfoliation with enhanced photocatalytic activity

International Nuclear Information System (INIS)

Wang, Xiao-jing; Liu, Chao; Li, Xu-li; Li, Fa-tang; Li, Yu-pei; Zhao, Jun; Liu, Rui-hong

2017-01-01

Highlights: • Ultrathin g-C_3N_4/Al_2O_3 hybrids are prepared via in-situ reaction. • The structure modification role of in-situ formed HNO_3 for g-C_3N_4 is found. • The ultrathin g-C_3N_4 nanosheets are formed by the acidified melamine and Al(OH)_3. • In-situ calcination of melamine and Al(OH)_3 benefits the contact of C_3N_4 and Al_2O_3. • The activity of g-C_3N_4/Al_2O_3 is 16.6 times that of pristine g-C_3N_4 in degrading RhB. - Abstract: Homogeneous ultrathin g-C_3N_4 nanosheets/Al_2O_3 heterojunctions are synthesized using melamine and Al(NO_3)_3 via in-situ reaction and the following thermal polymerization approach. The in-situ reaction between melamine and Al(NO_3)_3 results in the existence of HNO_3-acidified melamine and Al(OH)_3 aggregates via the hydrolysis of Al(NO_3)_3. After thermal polymerization, the aggregates are converted to g-C_3N_4/Al_2O_3 composites. The thermal polymerization of acidified melamine and the support effect of aluminum hydroxide for g-C_3N_4 during the calcination process lead to highly dispersed amrophous Al_2O_3 on ultrathin g-C_3N_4 nanosheets, which is beneficial for the separation of photogenerated electron-hole pairs in the heterojunction. The degradation rate for Rhodamine B (RhB) over the most activie sample is 16.6 times than that of pristine g-C_3N_4 under visible light irradiation, which can be attributed to the high specific surface area, highly dispersion of amorphous Al_2O_3 on ultrathin g-C_3N_4 nanosheet, and the effective electrons transfer from g-C_3N_4 to the amorphous Al_2O_3.
Suitability of quantum cascade laser spectroscopy for CH4 and N2O eddy covariance flux measurements

Directory of Open Access Journals (Sweden)

A. T. Vermeulen

2007-08-01

Full Text Available A quantum cascade laser spectrometer was evaluated for eddy covariance flux measurements of CH4 and N2O using three months of continuous measurements at a field site. The required criteria for eddy covariance flux measurements including continuity, sampling frequency, precision and stationarity were examined. The system operated continuously at a dairy farm on peat grassland in the Netherlands from 17 August to 6 November 2006. An automatic liquid nitrogen filling system for the infrared detector was employed to provide unattended operation of the system. The electronic sampling frequency was 10 Hz, however, the flow response time was 0.08 s, which corresponds to a bandwidth of 2 Hz. A precision of 2.9 and 0.5 ppb Hz−1/2 was obtained for CH4 and N2O, respectively. Accuracy was assured by frequent calibrations using low and high standard additions. Drifts in the system were compensated by using a 120 s running mean filter. The average CH4 and N2O exchange was 512 ngC m−2 s−1 (2.46 mg m−2 hr−1 and 52 ngN m−2 s−1 (0.29 mg m−2 hr−1. Given that 40% of the total N2O emission was due to a fertilizing event.
Thermochemical characteristics of La n+1Ni nO3n+1 oxides

International Nuclear Information System (INIS)

Bannikov, D.O.; Safronov, A.P.; Cherepanov, V.A.

2006-01-01

Lanthanum nickelates: La 2 NiO 4+δ , La 3 Ni 2 O 7-δ , La 4 Ni 3 O 10-δ and LaNiO 3-δ the members of Ruddlesden-Popper series La n+1 Ni n O 3n+1 were prepared using citrate route. Dissolution enthalpies of complex oxides as well as a number of subsidiary substances were measured by means of Calvet calorimeter in 1 M solution of hydrochloric acid at 25 deg. C. The dissolution scheme of complex oxides in hydrochloric acid was proposed and enthalpies of formation of the complex oxides from binary oxides were calculated considering oxygen nonstoichiometry of these substances. Enthalpies of step-by-step oxidation were evaluated. Partial enthalpy contribution of LaO layers was calculated endothermic equals to 30.9 J/mol while partial enthalpy contribution of perovskite LaNiO 3 layers was negative equals to -97.0 J/mol. Enthalpy of formation of any complex oxide of Ruddlesden-Popper series fits very well to the linear regression based on these values
Ab initio studies of O-2(-) (H2O)(n) and O-3(-) (H2O)(n) anionic molecular clusters, n

DEFF Research Database (Denmark)

Bork, Nicolai Christian; Kurten, T.; Enghoff, Martin Andreas Bødker

2011-01-01

that anionic O-2(-)(H2O)n and O-3(-)(H2O)n clusters are thermally stabilized at typical atmospheric conditions for at least n = 5. The first 4 water molecules are strongly bound to the anion due to delocalization of the excess charge while stabilization of more than 4 H2O is due to normal hydrogen bonding....... Although clustering up to 12 H2O, we find that the O-2 and O-3 anions retain at least ca. 80 % of the charge and are located at the surface of the cluster. The O-2(-) and O-3(-) speicies are thus accessible for further reactions. We consider the distributions of cluster sizes as function of altitude before...
Highly Enhanced Photoreductive Degradation of Polybromodiphenyl Ethers with g-C3N4/TiO2 under Visible Light Irradiation

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Weidong Ye

2017-04-01

Full Text Available A series of high activity photocatalysts g-C3N4-TiO2 were synthesized by simple one-pot thermal transformation method and characterized by transmission electron microscopy (TEM, scanning electron microscopy (SEM, X-ray diffraction (XRD, X-ray photoelectron spectroscopy, Brunauer–Emmett–Teller (BET surface area, and ultraviolet–visible diffuse reflectance spectroscopy (UV-Vis-DRS. The g-C3N4-TiO2 samples show highly improved photoreductive capability for the degradation of polybromodiphenyl ethers compared with g-C3N4 under visible light irradiation. Among all the hybrids, 0.02-C3N4-TiO2 with 2 wt % g-C3N4 loaded shows the highest reaction rate, which is 15 times as high as that in bare g-C3N4. The well-matched band gaps in heterojunction g-C3N4-TiO2 not only strengthen the absorption intensity, but also show more effective charge carrier separation, which results in the highly enhanced photoreductive performance under visible light irradiation. The trapping experiments show that holetrapping agents largely affect the reaction rate. The rate of electron accumulation in the conductive band is the rate-determining step in the degradation reaction. A possible photoreductive mechanism has been proposed.
Synthesis, structures, and magnetic properties of novel Roddlesden-Popper homologous series Srn+1ConO3n+1 (n=1,2,3,4, and ∞)

International Nuclear Information System (INIS)

Wang, X.L.; Sakurai, H.; Takayama-Muromachi, E.

2005-01-01

Roddlesden-Popper homologous series Sr n+1 Co n O 3n+1 (n=1,2,3,4, and ∞) compounds were successfully synthesized by a high pressure and high temperature technique. Structure refinement revealed that these compounds crystallize in tetragonal structures, while the compound n=∞ is cubic. These compounds are ferromagnetic with the Curie temperature decreasing from 255 K for n=1 to about 200 K for n=2-4 and down to 175 K for SrCoO 3 . Co 4+ ions present as intermediate spin states for n=1-4, but in the low spin state in SrCoO 3 . Negative magnetoresistance was observed for Sr 2 CoO 4 and found to be larger than that for SrCoO 3
Nitrous oxide (N2O) emission from aquaculture: a review.

Science.gov (United States)

Hu, Zhen; Lee, Jae Woo; Chandran, Kartik; Kim, Sungpyo; Khanal, Samir Kumar

2012-06-19

Nitrous oxide (N(2)O) is an important greenhouse gas (GHG) which has a global warming potential 310 times that of carbon dioxide (CO(2)) over a hundred year lifespan. N(2)O is generated during microbial nitrification and denitrification, which are common in aquaculture systems. To date, few studies have been conducted to quantify N(2)O emission from aquaculture. Additionally, very little is known with respect to the microbial pathways through which N(2)O is formed in aquaculture systems. This review suggests that aquaculture can be an important anthropogenic source of N(2)O emission. The global N(2)O-N emission from aquaculture in 2009 is estimated to be 9.30 × 10(10) g, and will increase to 3.83 × 10(11)g which could account for 5.72% of anthropogenic N(2)O-N emission by 2030 if the aquaculture industry continues to increase at the present annual growth rate (about 7.10%). The possible mechanisms and various factors affecting N(2)O production are summarized, and two possible methods to minimize N(2)O emission, namely aquaponic and biofloc technology aquaculture, are also discussed. The paper concludes with future research directions.
Nano-level determination of copper with atomic absorption spectrometry after pre-concentration on N,N-(4-methyl-1,2-phenylene)diquinoline-2-carboxamide-naphthalene

Energy Technology Data Exchange (ETDEWEB)

Rezaei, Behzad, E-mail: rezaei@cc.iut.ac.ir [Department of Chemistry, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Sadeghi, Elham; Meghdadi, Soraia [Department of Chemistry, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of)

2009-09-15

A novel, simple, sensitive and effective method has been developed for selective extraction and pre-concentration of copper on N,N-(4-methyl-1,2-phenylene)diquinoline-2-carboxamide-naphthalene. After pre-concentration, copper was eluted from sorbent with hydrochloric acid, and then flame atomic absorption spectrometry (FAAS) was used for its determination. The effect of pH, sample flow rate and the volume and concentration of eluent on the recovery of the analyte was investigated and the optimum conditions were established. A pre-concentration factor of 400, and an adsorption capacity of 6.9 mg g{sup -1} of the solid-phase sorbent or 82.8 mg g{sup -1} of ligand was achieved using the optimum conditions. The calibration graph was linear in the range of 1.0-4000 ng mL{sup -1} with the detection limit of 1.0 ng mL{sup -1}. A R.S.D. value of 2.4% was obtained by this method for 400 ng mL{sup -1} of Cu{sup 2+} solution. This procedure has been successfully applied to separate and determine the ultra trace levels of copper in the environmental samples, free from the interference of some diverse ions.
Poly[[sesqui[mu2-1,4-bis(imidazol-1-ylmethyl)benzene-kappa(2)N:N'](carbonato-kappa(2)O,O')copper(II)] 1,4-bis(imidazol-1-ylmethyl)benzene hemisolvate pentahydrate].

Science.gov (United States)

Dai, Yu-Mei; Tang, En; Huang, Jin-Feng; Yang, Qiu-Yan

2008-10-01

The asymmetric unit of the title compound, {[Cu(CO(3))(C(14)H(14)N(4))(1.5)] x 0.5 C(14)H(14)N(4) x 5 H(2)O}(n), contains one Cu(II) cation in a slightly distorted square-pyramidal coordination environment, one CO(3)(2-) anion, one full and two half 1,4-bis(imidazol-1-ylmethyl)benzene (bix) ligands, one half-molecule of which is uncoordinated, and five uncoordinated water molecules. One of the coordinated bix ligands and the uncoordinated bix molecule are situated about centers of symmetry, located at the centers of the benzene rings. The coordinated bix ligands link the copper(II) ions into a [Cu(bix)(1.5)](n) molecular ladder. These molecular ladders do not form interpenetrated ladders but are arranged in an ABAB parallel terrace, i.e. with the ladders arranged one above another, with sequence A translated with respect to B by 8 A. To best of our knowledge, this arrangement has not been observed in any of the molecular ladder frameworks synthesized to date. The coordination environment of the Cu(II) atom is completed by two O atoms of the CO(3)(2-) anion. The framework is further strengthened by extensive O-H...O and O-H...N hydrogen bonds involving the water molecules, the O atoms of the CO(3)(2-) anion and the N atoms of the bix ligands. This study describes the first example of a molecular ladder coordination polymer based on bix and therefore demonstrates further the usefulness of bix as a versatile multidentate ligand for constructing coordination polymers with interesting architectures.
Enhanced visible light activity on direct contact Z-scheme g-C{sub 3}N{sub 4}-TiO{sub 2} photocatalyst

Energy Technology Data Exchange (ETDEWEB)

Li, Juan [National & Local Joint Engineering Research Center for Applied Technology of Hybrid Nanomaterials, Henan University, Kaifeng, 475004 (China); Collaborative Innovation Center of Nano Functional Materials and Applications of Henan Province, Henan University, Kaifeng, 475004 (China); College of Chemistry and Chemical Engineering, Henan University, Kaifeng, 475004 (China); Zhang, Min [National & Local Joint Engineering Research Center for Applied Technology of Hybrid Nanomaterials, Henan University, Kaifeng, 475004 (China); Collaborative Innovation Center of Nano Functional Materials and Applications of Henan Province, Henan University, Kaifeng, 475004 (China); Li, Qiuye, E-mail: qiuyeli@henu.edu.cn [National & Local Joint Engineering Research Center for Applied Technology of Hybrid Nanomaterials, Henan University, Kaifeng, 475004 (China); Collaborative Innovation Center of Nano Functional Materials and Applications of Henan Province, Henan University, Kaifeng, 475004 (China); Yang, Jianjun, E-mail: yangjianjun@henu.edu.cn [National & Local Joint Engineering Research Center for Applied Technology of Hybrid Nanomaterials, Henan University, Kaifeng, 475004 (China); Collaborative Innovation Center of Nano Functional Materials and Applications of Henan Province, Henan University, Kaifeng, 475004 (China)

2017-01-01

Highlights: • The g-C{sub 3}N{sub 4}-TiO{sub 2} composites were obtained by simple solid state sintering. • The composites were direct contact Z-scheme without an electron mediator. • TiO{sub 2} with large amount of SETOV was obtained by dehydration of NTA. - Abstract: Direct contact Z-scheme g-C{sub 3}N{sub 4}-TiO{sub 2} nanocomposites without an electron mediator are prepared via simple annealing the mixture of bulk g-C{sub 3}N{sub 4} and nanotube titanic acid (NTA) in air at 600 °C for 2 h. In the process of annealing, the bulk g-C{sub 3}N{sub 4} transformed to ultra-thin g-C{sub 3}N{sub 4} nanosheets, and NTA converted to a novel anatase TiO{sub 2}, then the two components formed a close interaction. The XPS result reveals that some amount of nitrogen is doped into this novel-TiO{sub 2}, and g-C{sub 3}N{sub 4} nanosheets exist in the composites. The results of XRD, TEM and TG indicate that the thickness of g-C{sub 3}N{sub 4} nanosheets is very thin. The ESR spectrum shows the existence of Ti{sup 3+} and single-electron-trapped oxygen vacancy in the 30%g-C{sub 3}N{sub 4}-TiO{sub 2} composites. In photocatalytic activity test, the 30%g-C{sub 3}N{sub 4}-TiO{sub 2} nanocomposites showed an excellent photo-oxidation activity of propylene under visible light irradiation (λ≥ 420 nm), and the removal efficiency of propylene reached as high as 56.6%, and the activity kept nearly 82% after four consecutive recycles. Photoluminescence (PL) result using terephthalic acid (TA) as a probe molecule indicated that the g-C{sub 3}N{sub 4}-TiO{sub 2} nanocomposites displayed a Z-sheme photocatalytic reaction system and this should be the main reason for the high photocatalytic activity. A possible photocatalytic mechanism was proposed on the basis of PL result and transient photocurrent-time curves.
catena-Poly[[aquabis[N-(pyridin-3-ylisonicotinamide-κN1]copper(II]-μ-fumarato-κ2O1:O4

Directory of Open Access Journals (Sweden)

Sultan H. Qiblawi

2012-12-01

Full Text Available In the title compound, [Cu(C4H2O4(C11H9N3O2(H2O]n, CuII ions on crystallographic twofold rotation axes are coordinated in a square pyramidal environment by two trans O atoms belonging to two monodentate fumarate anions, two trans isonicotinamide pyridyl N-donor atoms from monodentate, pendant 3-pyridylisonicotinamide (3-pina ligands, and one apical aqua ligand, also sited on the crystallographic twofold rotation axis. The exobidentate fumarate ligands form [Cu(fumarate(3-pina2(H2O]n coordination polymer chains that are arranged parallel to [001]. In the crystal, these polymeric chains are anchored into supramolecular layers parallel to (100 by O—H...O hydrogen bonds between aqua ligands and unligating fumarate O atoms, and N—H...O(=C hydrogen bonds between 3-pina ligands. In turn, the layers aggregate by weak C—H...N and C—H...O hydrogen bonds, affording a three-dimensional network.

Higher spin currents in the critical O(N) vector model at 1/N2

International Nuclear Information System (INIS)

Manashov, A.N.; Strohmaier, M.

2017-06-01

We calculate the anomalous dimensions of higher spin singlet currents in the critical O(N) vector model at order 1/N 2 . The results are shown to be in agreement with the four-loop perturbative computation in φ 4 theory in 4-2ε dimensions. It is known that the order 1/N anomalous dimensions of higher-spin currents happen to be the same in the Gross-Neveu and the critical vector model. On the contrary, the order 1/N 2 corrections are different. The results can also be interpreted as a prediction for the two-loop computation in the dual higher-spin gravity.
Active species in a large volume N2-O2 post-discharge reactor

International Nuclear Information System (INIS)

Kutasi, K; Pintassilgo, C D; Loureiro, J; Coelho, P J

2007-01-01

A large volume post-discharge reactor placed downstream from a flowing N 2 -O 2 microwave discharge is modelled using a three-dimensional hydrodynamic model. The density distributions of the most populated active species present in the reactor-O( 3 P), O 2 (a 1 Δ g ), O 2 (b 1 Σ g + ), NO(X 2 Π), NO(A 2 Σ + ), NO(B 2 Π), NO 2 (X), O 3 , O 2 (X 3 Σ g - ) and N( 4 S)-are calculated and the main source and loss processes for each species are identified for two discharge conditions: (i) p = 2 Torr, f = 2450 MHz, and (ii) p = 8 Torr, f = 915 MHz; in the case of a N 2 -2%O 2 mixture composition and gas flow rate of 2 x 10 3 sccm. The modification of the species relative densities by changing the oxygen percentage in the initial gas mixture composition, in the 0.2%-5% range, are presented. The possible tuning of the species concentrations in the reactor by changing the size of the connecting afterglow tube between the active discharge and the large post-discharge reactor is investigated as well
Structure and thermal property of N,N-diethyl-N-methyl-N-2-methoxyethyl ammonium tetrafluoroborate-H2O mixtures

International Nuclear Information System (INIS)

Imai, Yusuke; Abe, Hiroshi; Goto, Takefumi; Yoshimura, Yukihiro; Michishita, Yosuke; Matsumoto, Hitoshi

2008-01-01

By in situ observations using simultaneous X-ray diffraction and differential scanning calorimetry method, complicated phase transitions were observed in N,N-diethyl-N-methyl-N-2-methoxyethyl ammonium tetrafluoroborate, [DEME][BF 4 ] and H 2 O mixtures. In pure [DEME][BF 4 ], two different crystal structures were determined below crystallization temperature, T c . Two kinds of crystals correspond to two stages of melting upon heating. T c decreases with increasing in the H 2 O content of [DEME][BF 4 ]-H 2 O mixture. Around 6.7 mol% H 2 O, an amorphous solid, however, was formed without crystallization on cooling. Glass transition temperature, T g , of the amorphous phase depends on cooling rate of the mixture. On heating, the amorphous solid transformed to a crystal accompanied by an exothermal peak. This unusual cold crystallization is induced by H 2 O molecules. Two different dynamic components were observed in a Raman spectrum of the amorphous phase, where the lower Raman band is crystal-like and the higher one is liquid-like. At higher H 2 O concentration, coexistence of the amorphous solid and crystal was realized below T c , and the cold crystallization also occurred. In spite of a variety of phase transitions, the crystal structure of [DEME][BF 4 ]-H 2 O mixtures is the same one as pure [DEME][BF 4
N2O isotopomers and N2:N2O ratio as indicators of denitrification in ecosystems

International Nuclear Information System (INIS)

Mander, Ülo; Zaman, Mohammad

2015-01-01

The world is experiencing climate change and variability due to increased greenhouse gas (GHG) emissions. The main GHG’s of concern are nitrous oxide (N 2 O), carbon dioxide (CO 2 ) and methane (CH 4 ). Agriculture contributes approximately 14% of the world’s GHG emissions. Nitrous oxide is one of the key GHG and ozone (O 3 ) depleting gas, constituting 7% of the anthropogenic greenhouse effect. On a molecular basis, N 2 O has a 310- and 16-fold greater global warming potential than each of CO 2 and CH 4 , respectively, over a 100-year period. Nitrous oxide can be produced through both chemical and biochemical pathways. They occur during denitrification (the stepwise conversion of nitrate (NO 3 - ) to nitrogen gas (N 2 ) and during nitrification by ammonia-oxidizing archea (bacteria) during the oxidation of hydroxylamine (NH 2 OH) to nitrite (NO 2 - ) which is then reduced to N 2 O and N 2 by nitrifier denitrification or heterotrophic denitrification
Preparation of MoO2/g-C3N4 composites with a high surface area and its application in deep desulfurization from model oil

Science.gov (United States)

Hou, Liang-pei; Zhao, Rong-xiang; Li, Xiu-ping; Gao, Xiao-han

2018-03-01

A series of catalysts of composition X-MoO2/g-C3N4 (X = 0, 0.5, 1, 3, 5 wt.%) were successfully synthesized by calcination of a mixture of (NH4)6Mo7O24·4H2O and g-C3N4. Oxidative desulfurization experiments were conducted using X-MoO2/g-C3N4 as a catalyst, H2O2 as an oxidant, and ionic liquids (ILs) as extraction agents. Catalysts were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared (FT-IR), scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS), and Brunauer-Emmett-Teller analysis (BET). Characterization results suggested that MoO2 was present in the catalyst and its crystallinity improved with increased Mo-loading. The catalysts had a larger specific surface area due to the presence of MoO2 dispersed on g-C3N4. Experimental results showed that 3%-MoO2/g-C3N4 had the highest catalytic activity among all the catalysts tested. A desulfurization rate of 96.0% was achieved under optimal conditions. Through gas chromatography-mass spectrometry (GC-MS) analysis, it was shown that dibenzothoiphene sulfone was the sole product of the oxidation desulfurization reaction. An apparent activation energy of 61.1 kJ/mol was estimated based on Arrhenius equation. The activity of 3%-MoO2/g-C3N4 slightly decreased after six runs. A possible mechanism for the reaction has been proposed.
N2O, NO, N2 and CO2 emissions from tropical savanna and grassland of northern Australia: an incubation experiment with intact soil cores

Directory of Open Access Journals (Sweden)

C. Werner

2014-11-01

Full Text Available Strong seasonal variability of hygric and thermal soil conditions are a defining environmental feature in northern Australia. However, how such changes affect the soil–atmosphere exchange of nitrous oxide (N2O, nitric oxide (NO and dinitrogen (N2 is still not well explored. By incubating intact soil cores from four sites (three savanna, one pasture under controlled soil temperatures (ST and soil moisture (SM we investigated the release of the trace gas fluxes of N2O, NO and carbon dioxide (CO2. Furthermore, the release of N2 due to denitrification was measured using the helium gas flow soil core technique. Under dry pre-incubation conditions NO and N2O emissions were very low (−2 h−1; 2O-N m−2 h−1 or in the case of N2O, even a net soil uptake was observed. Substantial NO (max: 306.5 μg N m−2 h−1 and relatively small N2O pulse emissions (max: 5.8 ± 5.0 μg N m−2 h−1 were recorded following soil wetting, but these pulses were short lived, lasting only up to 3 days. The total atmospheric loss of nitrogen was generally dominated by N2 emissions (82.4–99.3% of total N lost, although NO emissions contributed almost 43.2% to the total atmospheric nitrogen loss at 50% SM and 30 °C ST incubation settings (the contribution of N2 at these soil conditions was only 53.2%. N2O emissions were systematically higher for 3 of 12 sample locations, which indicates substantial spatial variability at site level, but on average soils acted as weak N2O sources or even sinks. By using a conservative upscale approach we estimate total annual emissions from savanna soils to average 0.12 kg N ha−1 yr−1 (N2O, 0.68 kg N ha−1 yr−1 (NO and 6.65 kg N ha−1 yr−1 (N2. The analysis of long-term SM and ST records makes it clear that extreme soil saturation that can lead to high N2O and N2 emissions only occurs a few days per year and thus has little impact on the annual total. The potential contribution of nitrogen released due to pulse events
The denitrification paradox: The role of O2 in sediment N2O production

Science.gov (United States)

Barnes, Jonathan; Upstill-Goddard, Robert C.

2018-01-01

We designed a novel laboratory sediment flux chamber in which we maintained the headspace O2 partial pressure at preselected values, allowing us to experimentally regulate "in-situ" O2 to evaluate its role in net N2O production by an intertidal estuarine sediment (Tyne, UK). In short-term (30 h) incubations with 10 L of overlying estuarine water (∼3 cm depth) and headspace O2 regulation (headspace: sediment/water ratio ∼9:1), net N2O production was highest at 1.2% O2 (sub-oxic; 32.3 nmol N2O m-2 d-1), an order of magnitude higher than at either 0.0% (anoxic; 2.5 N2O nmol m-2 d-1) or 20.85% (ambient; 2.3 nmol N2O m-2 d-1) O2. In a longer-term sealed incubation (∼490 h) without O2 control, time-dependent behaviour of N2O in the tank headspace was highly non-linear with time, showing distinct phases: (i) an initial period of no or little change in O2 or N2O up to ∼ 100 h; (ii) a quasi-linear, inverse correlation between O2 and N2O to ∼360 h, in which O2 declined to ∼2.1% and N2O rose to ∼7800 natm; (iii) over the following 50 h a slower O2 decline, to ∼1.1%, and a more rapid N2O increase, to ∼12000 natm; (iv) over the next 24 h a slowed O2 decline towards undetectable levels and a sharp fall in N2O to ∼4600 natm; (iv) a continued N2O decrease at zero O2, to ∼3000 natm by ∼ 490 h. These results show clearly that rapid N2O consumption (∼115 nmol m-2 d-1), presumably via heterotrophic denitrification (HD), occurs under fully anoxic conditions and therefore that N2O production, which was optimal for sub-oxic O2, results from other nitrogen transformation processes. In experiments in which we amended sediment overlying water to either 1 mM NH4+ or 1 mM NO3-, N2O production rates were 2-134 nmol N2O m-2 d-1 (NH4+ addition) and 0.4-2.2 nmol N2O m-2 d-1 (NO3- addition). We conclude that processes involving NH4+ oxidation (nitrifier nitrification; nitrifier denitrification; nitrification-coupled denitrification) are principally responsible for N2O
Ternary composite of TiO2 nanotubes/Ti plates modified by g-C3N4 and SnO2 with enhanced photocatalytic activity for enhancing antibacterial and photocatalytic activity.

Science.gov (United States)

Faraji, Masoud; Mohaghegh, Neda; Abedini, Amir

2018-01-01

A series of g-C 3 N 4 -SnO 2 /TiO 2 nanotubes/Ti plates were fabricated via simple dipping of TiO 2 nanotubes/Ti in a solution containing SnCl 2 and g-C 3 N 4 nanosheets and finally annealing of the plates. Synthesized plates were characterized by various techniques. The SEM analysis revealed that the g-C 3 N 4 -SnO 2 nanosheets with high physical stability have been successfully deposited onto the surface of TiO 2 nanotubes/Ti plate. Photocatalytic activity was investigated using two probe chemical reactions: oxidative decomposition of acetic acid and oxidation of 2-propanol under irradiation. Antibacterial activities for Escherichia coli (E. coli) bacteria were also investigated in dark and under UV/Vis illuminations. Detailed characterization and results of photocatalytic and antibacterial activity tests revealed that semiconductor coupling significantly affected the photocatalyst properties synthesized and hence their photocatalytic and antibacterial activities. Modification of TiO 2 nanotubes/Ti plates with g-C 3 N 4 -SnO 2 deposits resulted in enhanced photocatalytic activities in both chemical and microbial systems. The g-C 3 N 4 -SnO 2 /TiO 2 nanotubes/Ti plate exhibited the highest photocatalytic and antibacterial activity, probably due to the heterojunction between g-C 3 N 4 -SnO 2 and TiO 2 nanotubes/Ti in the ternary composite plate and thus lower electron/hole recombination rate. Based on the obtained results, a photocatalytic and an antibacterial mechanism for the degradation of E. coli bacteria and chemical pollutants over g-C 3 N 4 -SnO 2 /TiO 2 nanotubes/Ti plate were proposed and discussed. Copyright © 2017 Elsevier B.V. All rights reserved.
Synthesis and characterization of a pentadentate Schiff base N3O2 ligand and its neutral technetium(V) complex. X-ray structure of (N,N'-3-azapentane-1,5-diylbis(3-(1-iminoethyl)-6-methyl-2H-pyran-2,4(3H)-dionato)(3-)-O,O',N,N',N double-prime)oxotechnetium(V)

International Nuclear Information System (INIS)

Shuang Liu; Rettig, S.J.; Orvig, C.

1991-01-01

Preparations of a potentially pentadentate ligand, N,N'-3-azapentane-1,5-diylbis(3-(1-iminoethyl)-6-methyl-2H-pyran-2,4-(3H)-dione) (H 3 apa), and its neutral technetium(V) complex, [TcO(apa)], are described. The 13 C and 1 H NMR, infrared, optical, and mass spectra of the pentadentate ligand and its technetium(V) complex are reported. The X-ray structure of [TcO(apa)] has been determined. Crystals are orthorhombic, space group Pbca, with a = 12.833 (2) angstrom, b = 33.320 (5) angstrom, c = 9.942(4) angstrom, V = 4251 (2) angstrom, and Z = 8. The structure was solved by Patterson and Fourier methods and was refined by full-matrix least-squares procedures to R = 0.028 and R W = 0.032 for 4054 reflections with I ≥ 3σ(I). The technetium(V) complex has a highly distorted octahedral coordination geometry comprising a [TcO] 3+ core and the triply deprotonated pentadentate ligand wrapping around the metal center. One of the two oxygen donor atoms of the pentadentate ligand is located trans to the Tc double-bond O bond while the remaining four donor atoms, N 3 O, occupy the equatorial sites. The distance between the deprotonated N(1) atom to the Tc center is significantly shorter than a normal Tc-N single bond length of 2.10 angstroms, but longer than that for a Tc-N triple bond. 1 H NMR spectral data reveal a rigid solution structure for the complex, which undergoes no conformational and configurational exchange at temperatures up to 50C
Factors controlling regional differences in forest soil emission of nitrogen oxides (NO and N₂O)

DEFF Research Database (Denmark)

Pilegaard, K.; Skiba, U.; Ambus, P.

2006-01-01

-deposition. The site with the highest average annual emission (82 mu g NO-N m(-2) h(-1)) was a spruce forest in South-Germany (Hoglwald) receiving an annual N-deposition of 2.9 g m(-2). NO emissions close to the detection limit were observed from a pine forest in Finland where the N-deposition was 0.2 N m(-2) a(-1......). No significant correlation between N2O emission and N-deposition was found. The highest average annual N2O emission (20 mu g N2O-Nm(-2) h(-1)) was found in an oak forest in the Matra mountains (Hungary) receiving an annual N-deposition of 1.6 g m(-2). N2O emission was significantly negatively correlated...
μ-Acetato-κ2O:O′-[7,23-dibenzyl-15,31-dichloro-3,7,11,19,23,27-hexaazatricyclo[27.3.1.113,17]tetratriconta-1(32,2,11,13,15,17(34,18,27,29(33,30-decaene-33,34-diolato-κ10N4,N5,N6,O1,O2:N1,N2,N3,O1,O2]dinickel(II perchlorate acetonitrile disolvate

Directory of Open Access Journals (Sweden)

Juan Kong

2008-01-01

Full Text Available The title complex, [Ni2(C42H46Cl2N6O2(C2H3O2]ClO4·2CH3CN, was synthesized by condensation of 2,6-diformyl-4-chlorophenol with N,N-bis(aminopropylbenzylamine in the presence of NiII ions. The ligand is a 28-membered macrocycle with two identical pendant arms. The coordination geometries of the Ni atoms are both octahedral. The two Ni atoms are bridged by two phenolate O atoms of the macrocyclic ligand and one acetate ligand, with an Ni...Ni distance of 3.147 (4 Å.
Production of N2O in grass-clover pastures

International Nuclear Information System (INIS)

Carter, M.S.

2005-09-01

Agricultural soils are known to be a considerable source of the strong greenhouse gas nitrous oxide (N 2 O), and in soil N 2 O is mainly produced by nitrifying and denitrifying bacteria. In Denmark, grass-clover pastures are an important component of the cropping system in organic as well as conventional dairy farming, and on a European scale grass-clover mixtures represent a large part of the grazed grasslands. Biological dinitrogen (N 2 ) fixation in clover provides a major N input to these systems, but knowledge is sparse regarding the amount of fixed N 2 lost from the grasslands as N2O. Furthermore, urine patches deposited by grazing cattle are known to be hot-spots of N 2 O emission, but the mechanisms involved in the N 2 O production in urine-affected soil are very complex and not well understood. The aim of this Ph.D. project was to increase the knowledge of the biological and physical-chemical mechanisms, which control the production of N2O in grazed grass-clover pastures. Three experimental studies were conducted with the objectives of: 1: assessing the contribution of recently fixed N 2 as a source of N 2 O. 2: examining the link between N 2 O emission and carbon mineralization in urine patches. 3: investigating the effect of urine on the rates and N 2 O loss ratios of nitrification and denitrification, and evaluating the impact of the chemical conditions that arise in urine affected soil. The results revealed that only 3.2 ± 0.5 ppm of the recently fixed N 2 was emitted as N2O on a daily basis. Thus, recently fixed N released via easily degradable clover residues appears to be a minor source of N2O. Furthermore, increased N 2 O emission following urine application at rates up to 5.5 g N m -2 was not caused by enhanced denitrification stimulated by labile compounds released from scorched plant roots. Finally, the increase of soil pH and ammonium following urine application led to raised nitrification rate, which appeared to be the most important factor
Tc dependence on the number of CuO2 planes in multilayered Ba2Can-1CunO2n(O, F)2 superconductors

International Nuclear Information System (INIS)

Iyo, A; Tanaka, Y; Kodama, Y; Kito, H; Tokiwa, K; Watanabe, T

2006-01-01

Multilayered cuprates of Ba 2 Ca n-1 Cu n O 2n (O, F) 2 (F-02(n-1)n) with n = 5 - 9 have been synthesized by using high pressure synthesis method in order to investigate the variation of T c . The temperature dependence of susceptibility showed that the T c (about 80 K) does not depend on n for n 5 - 9. This result can be explained using the carrier imbalance model in multilayered cuprates. Charge reservoir layers supply most of the carriers to adjacent CuO 2 planes (OP) and the OP keeps the T c constant even for large n
Photocatalytic oxidation of aromatic amines using MnO2@g-C3N4

Data.gov (United States)

U.S. Environmental Protection Agency — An efficient and direct oxidation of aromatic amines to aromatic azo-compounds has been achieved using a MnO2@g-C3N4 catalyst under visible light as a source of...
N2O, NO, N2 and CO2 emissions from tropical savanna and grassland of northern Australia: an incubation experiment with intact soil cores

Science.gov (United States)

Werner, C.; Reiser, K.; Dannenmann, M.; Hutley, L. B.; Jacobeit, J.; Butterbach-Bahl, K.

2014-11-01

Strong seasonal variability of hygric and thermal soil conditions are a defining environmental feature in northern Australia. However, how such changes affect the soil-atmosphere exchange of nitrous oxide (N2O), nitric oxide (NO) and dinitrogen (N2) is still not well explored. By incubating intact soil cores from four sites (three savanna, one pasture) under controlled soil temperatures (ST) and soil moisture (SM) we investigated the release of the trace gas fluxes of N2O, NO and carbon dioxide (CO2). Furthermore, the release of N2 due to denitrification was measured using the helium gas flow soil core technique. Under dry pre-incubation conditions NO and N2O emissions were very low (soil uptake was observed. Substantial NO (max: 306.5 μg N m-2 h-1) and relatively small N2O pulse emissions (max: 5.8 ± 5.0 μg N m-2 h-1) were recorded following soil wetting, but these pulses were short lived, lasting only up to 3 days. The total atmospheric loss of nitrogen was generally dominated by N2 emissions (82.4-99.3% of total N lost), although NO emissions contributed almost 43.2% to the total atmospheric nitrogen loss at 50% SM and 30 °C ST incubation settings (the contribution of N2 at these soil conditions was only 53.2%). N2O emissions were systematically higher for 3 of 12 sample locations, which indicates substantial spatial variability at site level, but on average soils acted as weak N2O sources or even sinks. By using a conservative upscale approach we estimate total annual emissions from savanna soils to average 0.12 kg N ha-1 yr-1 (N2O), 0.68 kg N ha-1 yr-1 (NO) and 6.65 kg N ha-1 yr-1 (N2). The analysis of long-term SM and ST records makes it clear that extreme soil saturation that can lead to high N2O and N2 emissions only occurs a few days per year and thus has little impact on the annual total. The potential contribution of nitrogen released due to pulse events compared to the total annual emissions was found to be of importance for NO emissions
Novel microwave-assisted synthesis of porous g-C3N4/SnO2 nanocomposite for solar water-splitting

Science.gov (United States)

Seza, A.; Soleimani, F.; Naseri, N.; Soltaninejad, M.; Montazeri, S. M.; Sadrnezhaad, S. K.; Mohammadi, M. R.; Moghadam, H. Asgari; Forouzandeh, M.; Amin, M. H.

2018-05-01

Highly porous nanocomposites of graphitic-carbon nitride and tin oxide (g-C3N4/SnO2) were prepared through simple pyrolysis of urea molecules under microwave irradiation. The initial amount of tin was varied in order to investigate the effect of SnO2 content on preparation and properties of the composites. The synthesized nanocomposites were well-characterized by XRD, FE-SEM, HR-TEM, BET, FTIR, XPS, DRS, and PL. A homogeneous distribution of SnO2 nanoparticles with the size of less than 10 nm on the porous C3N4 sheets could be obtained, suggesting that in-situ synthesis of SnO2 nanoparticles was responsible for the formation of g-C3N4. The process likely occurred by the aid of the large amounts of OH groups formed on the surfaces of SnO2 nanoparticles during the polycondensation reactions of tin derivatives which could facilitate the pyrolysis of urea to carbon nitride. The porous nanocomposite prepared with initial tin amount of 0.175 g had high specific surface area of 195 m2 g-1 which showed high efficiency photoelectrochemical water-splitting ability. A maximum photocurrent density of 33 μA cm-2 was achieved at an applied potential of 0.5 V when testing this nanocomposite as photo-anode in water-splitting reactions under simulated visible light irradiation, introducing it as a promising visible light photoactive material.
[N,N-Bis(2-aminoethylethane-1,2-diamine](ethane-1,2-diaminenickel(II thiosulfate trihydrate

Directory of Open Access Journals (Sweden)

Beatrix Seidlhofer

2012-02-01

Full Text Available The title compound, [Ni(C2H8N2(C6H18N4]S2O3·3H2O, was accidentally synthesized under solvothermal conditions applying [Ni(en3]Cl2 (en is ethane-1,2-diamine as the Ni source. The asymmetric unit consists of one discrete [Ni(tren(en]2+ complex [tren is N,N-bis(2-aminoethylethane-1,2-diamine] in which the Ni2+ cation is sixfold coordinated within a slightly distorted octahedron, one thiosulfate anion and three water molecules. In the crystal, the complex cations, anions and water molecules are linked by an intricate hydrogen-bonding network. One C atom of the tren ligand, as well as one O atom of a water molecule, are disordered over two sites and were refined using a split model (occupancy ratios = 0.85:15 and 0.60:0.40, respectively.
Synthesis of g-C{sub 3}N{sub 4}/CeO{sub 2} nanocomposites with improved catalytic activity on the thermal decomposition of ammonium perchlorate

Energy Technology Data Exchange (ETDEWEB)

Tan, Linghua, E-mail: tanlinghua@njit.edu.cn [School of Materials Science and Engineering, Nanjing Institute of Technology, Jiangsu (China); Jiangsu Key Laboratory of Advanced Structural Materials and Application Technology, Jiangsu (China); Xu, Jianhua [School of Materials Science and Engineering, Nanjing Institute of Technology, Jiangsu (China); Zhang, Xiaojuan [School of Material Engineering, Jinling Institute of Technology, Nanjing 211169 (China); Hang, Zusheng [School of Materials Science and Engineering, Nanjing Institute of Technology, Jiangsu (China); Jiangsu Key Laboratory of Advanced Structural Materials and Application Technology, Jiangsu (China); Jia, Yongqiang; Wang, Shanbin [School of Materials Science and Engineering, Nanjing Institute of Technology, Jiangsu (China)

2015-11-30

Graphical abstract: The CeO{sub 2} nanoparticles were uniformly loaded on the surface of g-C{sub 3}N{sub 4} via a simple mixing-calcination method, and the heterostructure construction of resulting from g-C{sub 3}N{sub 4}/CeO{sub 2} nanocomposites effectively suppressed the charge recombination. Interestingly, g-C{sub 3}N{sub 4}/CeO{sub 2} nanocomposites showed an enhanced catalytic activity for thermal decomposition of ammonium perchlorate. - Highlights: • Novel g-C{sub 3}N{sub 4}/CeO{sub 2} nanocomposites were synthesized through a simple mixing-calcination method. • The g-C{sub 3}N{sub 4}/CeO{sub 2} nanocomposites were applied in catalyzing the thermal decomposition of ammonium perchlorate. • The synergetic effect of g-C{sub 3}N{sub 4} and CeO{sub 2} was the origin of the high catalytic activity. • The catalytic mechanism of g-C{sub 3}N{sub 4}/CeO{sub 2} nanocomposites to the thermal decomposition of AP was investigated. - Abstract: Novel g-C{sub 3}N{sub 4}/CeO{sub 2} nanocomposites were synthesized through a simple mixing-calcination method. The structure, morphology and composition of g-C{sub 3}N{sub 4}/CeO{sub 2} nanocomposites were characterized by X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), as well as X-ray photoelectron spectroscopy (XPS). The results indicated that CeO{sub 2} nanoparticles with a diameter of 50–100 nm were uniformly loaded on the surface of g-C{sub 3}N{sub 4.} Furthermore, the catalytic effect of our prepared novel g-C{sub 3}N{sub 4}/CeO{sub 2} nanocomposites on the thermal decomposition of ammonium perchlorate (AP) was investigated by utilizing thermogravimetric and differential thermal analyses (TG-DTA). Compared with pure g-C{sub 3}N{sub 4} and CeO{sub 2}, the g-C{sub 3}N{sub 4}/CeO{sub 2} nanocomposites were proved to catalyze the thermal decomposition
Implications of the (H2O)n + CO ↔ trans-HCOOH + (H2O)n-1 (n = 1, 2, and 3) reactions for primordial atmospheres of Venus and Earth

Science.gov (United States)

Vichietti, R. M.; Spada, R. F. K.; da Silva, A. B. F.; Machado, F. B. C.; Haiduke, R. L. A.

2018-04-01

The forward and backward (H2O)n + CO ↔ HCOOH + (H2O)n-1 (n = 1, 2, and 3) reactions were studied in order to furnish trustworthy thermochemical and kinetic data. Stationary point structures involved in these chemical processes were achieved at the B2PLYP/cc-pVTZ level so that the corresponding vibrational frequencies, zero-point energies, and thermal corrections were scaled to consider anharmonicity effects. A complete basis set extrapolation was also employed with the CCSD(T) method in order to improve electronic energy descriptions and providing therefore more accurate results for enthalpies, Gibbs energies, and rate constants. Forward and backward rate constants were encountered at the high-pressure limit between 200 and 4000 K. In turn, modified Arrhenius' equations were fitted from these rate constants (between 700 and 4000 K). Next, considering physical and chemical conditions that have supposedly prevailed on primitive atmospheres of Venus and Earth, our main results indicate that 85-88 per cent of all water forms on these atmospheres were monomers, whereas (H2O)2 and (H2O)3 complexes would represent 12-15 and ˜0 per cent, respectively. Besides, we estimate that Earth's and Venus' primitive atmospheres could have been composed by ˜0.001-0.003 per cent of HCOOH when their temperatures were around 1000-2000 K. Finally, the water loss process on Venus may have occurred by a mechanism that includes the formic acid as intermediate species.
Technical Note: Simultaneous measurement of sedimentary N2 and N2O production and a modified 15N isotope pairing technique

Science.gov (United States)

Hsu, T.-C.; Kao, S.-J.

2013-12-01

Dinitrogen (N2) and/or nitrous oxide (N2O) are produced through denitrification, anaerobic ammonium oxidation (anammox) or nitrification in sediments, of which entangled processes complicate the absolute rate estimations of gaseous nitrogen production from individual pathways. The classical isotope pairing technique (IPT), the most common 15N nitrate enrichment method to quantify denitrification, has recently been modified by different researchers to (1) discriminate between the N2 produced by denitrification and anammox or to (2) provide a more accurate denitrification rate under considering production of both N2O and N2. In case 1, the revised IPT focused on N2 production being suitable for the environments of a low N2O-to-N2 production ratio, while in case 2, anammox was neglected. This paper develops a modified method to refine previous versions of IPT. Cryogenic traps were installed to separately preconcentrate N2 and N2O, thus allowing for subsequent measurement of the two gases generated in one sample vial. The precision is better than 2% for N2 (m/z 28, m/z 29 and m/z 30), and 1.5% for N2O (m/z 44, m/z 45 and m/z 46). Based on the six m/z peaks of the two gases, the 15N nitrate traceable processes including N2 and N2O from denitrification and N2 from anammox were estimated. Meanwhile, N2O produced by nitrification was estimated via the production rate of unlabeled 44N2O. To validate the applicability of our modified method, incubation experiments were conducted using sediment cores taken from the Danshuei Estuary in Taiwan. Rates of the aforementioned nitrogen removal processes were successfully determined. Moreover, N2O yield was as high as 66%, which would significantly bias previous IPT approaches if N2O was not considered. Our modified method not only complements previous versions of IPT but also provides more comprehensive information to advance our understanding of nitrogen dynamics of the water-sediment interface.

Preliminary study of N[sub 2]O flux over irrigated Bermudagrass in a desert environment. [USA - Arizona

Energy Technology Data Exchange (ETDEWEB)

Matthias, A.D.; Artiola, J.F.; Musil, S.A. (Arizona University, Tucson, AZ (USA). Dept. of Soil and Water Science)

1993-04-01

The increase of atmospheric nitrous oxide is believed to be related to human activities, including increased agricultural use of nitrogen (N) fertilizers and irrigation. The purpose of this study was to evaluate N[sub 2]O flux (F(N)) into the atmosphere using chamber and gradient profile methods over an irrigated, N fertilized, bermudagrass (Cynodon dactylon cv. 'Midiron') field in the Sonoran Desert of Arizona. For the gradient profile method it was hypothesized that locally stable atmospheric conditions would enhance N[sub 2]O concentration differences sufficiently (more than approximately) 4 nl l[sup -1] to be resolved by gas chromatographic analysis of air samples collected at two heights (0.05 and 3.3 m) over the field. Significant differences (205 and 30 nl l[sup -1]) in mean concentration occurred during two sampling intervals in late afternoon and early morning of a 24 h period on 18-19 July 1991. During those intervals the surface layer was stable and relatively large F(N) estimated by the chamber method (371 and 48 ng m[sup -2] s[sup -1]) were comparable with F(N) estimated by the gradient profile method (283 and 101 ng m[sup -2] s[sup -1]). Simulations based on similarity theory indicate that resolution of N[sub 2]O concentration differences less than l nl l[sup -1] was required, but could not be achieved, when the surface layer was unstable and/or F(N) was small. Analysis also indicates that uncertainty of F(N) estimated by the chamber method was reduced slightly by estimation of temporal variation of vapour pressure in chamber air.
Preparation and infrared spectra of the Schiff base solid complexes [UO2(sal-O-phdn)(H2O)] and [UO2(sal-O-phdn) (Et3N)] (sal-O-phdn=n, n'-o-phenylenebissalicylideniminato)

International Nuclear Information System (INIS)

Sadeek, S.A.; Teleb, S.M.; Al-Kority, A.M.

1993-01-01

In the present communication, we report the preparation of the related two new complexes, [UO 2 (sal-o-phdn)(H 2 O)] and LUO 2 (sal-o-phdn)(Et 3 N)], where sal-o-phdn=N, N'-o-phenylenebis (salicylideneiminato); here U VI is seven-coordinate. The infrared spectra of these two complexes are recorded and assigned. (author). 10 refs., 1 tab
(μ-3-Acetyl-5-carboxylato-4-methylpyrazolido-1:2κ4 N 2,O 3:N 1,O 5)-μ-chlorido-tetrapyridine-1κ2 N,2κ2 N-chlorido-1κCl-dicopper(II) propan-2-ol solvate

Science.gov (United States)

Malinkin, Sergey; Penkova, Larisa; Pavlenko, Vadim A.; Haukka, Matti; Fritsky, Igor O.

2009-01-01

The title compound, [Cu2(C7H6N2O3)Cl2(C5H5N)4]·C3H8O, is a binuclear pyrazolate complex, in which the two CuII atoms have different coordination numbers and are connected by a bridging Cl atom. One CuII atom has a distorted square-pyramidal coordination environment formed by two pyridine N atoms, one bridging Cl atom and an N,O-chelating pyrazolate ligand. The other CuII atom adopts an octahedral geometry defined by two pyridine N atoms at the axial positions, two Cl atoms and the coordinated pyrazolate ligand in the equatorial plane. An O—H⋯O hydrogen bond connects the complex molecules and propan-2-ol solvent molecules into pairs. These pairs form columns along the a axis. PMID:21577764
Nitrogen loss from high N-input vegetable fields - a) direct N2O emissions b) Spatiotemporal variability of N species (N2O, NH4+, NO3-) in soils

Science.gov (United States)

Pfab, H.; Ruser, R.; Palmer, I.; Fiedler, S.

2009-04-01

Nitrous oxide is a climate relevant trace gas. It contributes 7.9 % to the total anthropogenic greenhouse gas emission and it is also involved in stratospheric ozone depletion. Approximately 85 % of the anthropogenic N2O emissions result from agricultural activities, more than 50 % are produced during microbial N-turnover processes in soils. Especially soils with high N-input (N-fertilizer and high amount of N in plant residues) like vegetable cropped soils are assumed to cause high N2O losses. The aims of the study presented were (i) to quantify the N2O loss from a vegetable field (lettuce-cauliflower crop rotation), (ii) to calculate an emission factor for the study site in Southwest Germany and to compare this factor with the default value provided by the IPCC (2006) and (iii) to test the emission reduction potential (Ammonium Sulfate Nitrate fertilizer, ASN either by reduced N-fertilization) in comparison with common N doses used for good agricultural practice or by the use of a nitrification inhibitor (DMPP), a banded N-application (lettuce) or a depot fertilization measure (pseudo-CULTAN in order to suppress nitrification). N2O fluxes determined with the closed chamber method were highly variable in time with strongly increased flux rates after N-fertilization in combination with rainfall or irrigation measures and after the incorporation of cauliflower crop residues. Using the mean soil nitrate contents of the top soil of our investigated treatments (0-25 cm depth), we could explain approximately 60 % of the variability of the cumulative N2O losses during the vegetation period of lettuce and cauliflower. The cumulative N2O emissions ranged between 0,99 kg N2O-N ha-1 from the unfertilized control plots (vegetation period) and 6,81 kg N2O-N ha-1 from the plots with the highest N-dose. Based on the guidelines of the IPCC (2006), we calculated an emission factor around 0,9 % for the cropping season. This value is in good agreement with the default value of the
N2O emission from organic barley cultivation as affected by green manure management

Directory of Open Access Journals (Sweden)

P. Dörsch

2012-07-01

Full Text Available Legumes are an important source of nitrogen in stockless organic cereal production. However, substantial amounts of N can be lost from legume-grass leys prior to or after incorporation as green manure (GM. Here we report N2O emissions from a field experiment in SE Norway exploring different green manure management strategies: mulching versus removal of grass-clover herbage during a whole growing season and return as biogas residue to a subsequent barley crop. Grass-clover ley had small but significantly higher N2O emissions as compared with a non-fertilised cereal reference during the year of green manure (GM production in 2009. Mulching of herbage induced significantly more N2O emission (+0.37 kg N2O-N ha−1 throughout the growing season than removing herbage. In spring 2010, all plots were ploughed (with and without GM and sown with barley, resulting in generally higher N2O emissions than during the previous year. Application of biogas residue (60 kg NH4+-N + 50 kg organic N ha−1 before sowing did not increase emissions neither when applied to previous ley plots nor when applied to previously unfertilised cereal plots. Ley management (mulching vs. removing biomass in 2009 had no effect on N2O emissions during barley production in 2010. In general, GM ley (mulched or harvested increased N2O emissions relative to a cereal reference with low mineral N fertilisation (80 kg N ha−1. Based on measurements covering the growing season 2010, organic cereal production emitted 95 g N2O-N kg−1 N yield in barley grain, which was substantially higher than in the cereal reference treatment with 80 kg mineral N fertilisation (47 g N2O-N kg−1 N yield in barley grain.
Effects of calcining temperature on photocatalysis of g-C{sub 3}N{sub 4}/TiO{sub 2} composites for hydrogen evolution from water

Energy Technology Data Exchange (ETDEWEB)

Qu, Ailan, E-mail: elainqal@163.com; Xu, Xinmei; Xie, Haolong; Zhang, Yangyu; Li, Yuyu; Wang, Junxian

2016-08-15

Highlights: • TiO{sub 2} promotes melon to form at 400 °C, whereas it forms at 500 °C for only melamine. • The highest photocatalytic activity was achieved when calcination was performed at 400 °C. • Coordinated N−Ti−N bonds were formed in MA/TiO{sub 2} (400) and disappeared at high temperature. • The surface area decreased and the pore size increased with increasing of temperature. • Only MA/TiO{sub 2} (400) has a narrower band gap than pure g-C{sub 3}N{sub 4}. - Abstract: A composite of graphitic carbon nitride and TiO{sub 2} (g-C{sub 3}N{sub 4}/TiO{sub 2}) with enhanced photocatalytic hydrogen evolution capacity was achieved by calcining melamine and TiO{sub 2} sol-gel precursor. Characterization results reveal that heating temperature had a great influence on the structure, surface area and properties of the composites. Compared with the polycondensation of pure melamine, the presence of TiO{sub 2} precursor can promote the formation of melon at a low temperature. The highest photocatalytic activity of g-C{sub 3}N{sub 4}/TiO{sub 2}(400) was achieved when the calcination was performed at 400 °C, exhibiting H{sub 2} production rate of 76.25 μmol/h under UV–vis light irradiation (λ > 320 nm) and 35.44 μmol/h under visible light irradiation (λ > 420 nm). The highest photocatalytic performance of g-C{sub 3}N{sub 4}/TiO{sub 2}(400) can be attributed to: (1) the strong UV–vis light absorption due to the narrow bandgap caused by synergic effect of TiO{sub 2} and g-C{sub 3}N{sub 4}, (2) high surface area and porosity, (3) the effective separation of photo-generated electron-holes owing to the favorable heterojunction between TiO{sub 2} and g-C{sub 3}N{sub 4}.
Stability analysis and structural rules of titanium dioxide clusters (TiO2)n with n = 1-9

International Nuclear Information System (INIS)

Zhang Weiwei; Han Ye; Yao Shuyu; Sun Haiqing

2011-01-01

Highlights: · We investigated the structure and stability of (TiO 2 ) n clusters with n = 1-9. · Some initial structures are introduced and proved to be the real global minimum. · We summarized the structural rules for small (TiO 2 ) n clusters. · The bonding features for the energy increment or decrement of the clusters are investigated. · A general shift of stability and reactivity with size for (TiO 2 ) n clusters. - Abstract: Atomic clusters have been considered as models for fundamental mechanistic insight into complex surfaces and catalysts. The structure and stability of (TiO 2 ) n clusters with n = 1-9 are investigated using the b3lyp hybrid density functional method in this paper. Some of the clusters are proposed initially and proved to be the real global minima. The stability and band gap of the clusters as a function of size are also investigated. The structural rules of the clusters are first summarized. The lowest-lying (TiO 2 ) n isomers tend to form some compact rather than quasi-linear or circular structures. The oxygen atom in 4-fold coordination and the titanium atom in 4-fold coordination favor the cluster stability. The 5-fold coordinated Ti-atom, the Ti-Ti bond and the terminal Ti-O bond lead to stability penalty for the clusters. No evidence for a regular variation in stability or reactivity with size of the clusters has shown. The structural rules can serve as guiding factors for formation research and structure design of (TiO 2 ) n and other transition metal oxide clusters.
Design of Cu-Cu{sub 2}O/g-C{sub 3}N{sub 4} nanocomponent photocatalysts for hydrogen evolution under visible light irradiation using water-soluble Erythrosin B dye sensitization

Energy Technology Data Exchange (ETDEWEB)

Zhang, Piyong; Wang, Tingting; Zeng, Heping, E-mail: hpzeng@scut.edu.cn

2017-01-01

Highlights: • A novel photocatalyst Cu-Cu{sub 2}O/g-C{sub 3}N{sub 4} was designed, synthesized and characterized. • Cu-Cu{sub 2}O/g-C{sub 3}N{sub 4} was sensitized by Erythrosin B and a significant enhancement of H{sub 2} evolution rate was achieved. • Electrochemical properties were measured and a possible mechanism of H{sub 2} evolution was proposed. - Abstract: Cu-Cu{sub 2}O nanoparticles (NPs) decorated porous graphitic carbon nitride (g-C{sub 3}N{sub 4}) (Cu-Cu{sub 2}O/g-C{sub 3}N{sub 4}) photocatalysts were prepared. When investment of copper source materials in the experiment increased to 7 wt%, the highest H{sub 2} evolution rate (400 μmol g{sup −1} h{sup −1}) was obtained under visible light irradiation in triethanolamine solution. This is about triple of pure g-C{sub 3}N{sub 4} (140 μmol g{sup −1} h{sup −1}). Moreover, various amount of Erythrosin B dye was added into Cu-Cu{sub 2}O/g-C{sub 3}N{sub 4} photoreaction solution and a significant enhancement of H{sub 2} production rate was achieved. The highest H{sub 2} production rate was 5000 μmol g{sup −1} h{sup −1} with 5 mg Erythrosin B in photoreaction system. Erythrosin B dye sensitized Cu-Cu{sub 2}O/g-C{sub 3}N{sub 4} presented stable photocatalytic H{sub 2} evolution ability and no noticeable degradation or change of photocatalyst were detected after six recycles. A possible photocatalytic mechanism of Erythrosin B dye sensitized Cu-Cu{sub 2}O/g-C{sub 3}N{sub 4} for the enhancement of photocatalytic H{sub 2} evolution is proposed.
Higher spin currents in the critical O(N) vector model at 1/N{sup 2}

Energy Technology Data Exchange (ETDEWEB)

Manashov, A.N. [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik; Regensburg Univ. (Germany). Inst. fuer Theoretische Physik; Skvortsov, E.D. [Munich Univ. (Germany). Arnold Sommerfeld Center for Theoretical Physics; Lebedev Institute of Physics, Moscow (Russian Federation); Strohmaier, M. [Regensburg Univ. (Germany). Inst. fuer Theoretische Physik

2017-06-15

We calculate the anomalous dimensions of higher spin singlet currents in the critical O(N) vector model at order 1/N{sup 2}. The results are shown to be in agreement with the four-loop perturbative computation in φ{sup 4} theory in 4-2ε dimensions. It is known that the order 1/N anomalous dimensions of higher-spin currents happen to be the same in the Gross-Neveu and the critical vector model. On the contrary, the order 1/N{sup 2} corrections are different. The results can also be interpreted as a prediction for the two-loop computation in the dual higher-spin gravity.
Variability of N{sub 2}O emissions during the production of poplar and rye

Energy Technology Data Exchange (ETDEWEB)

Kern, Juergen; Hellebrand, Hans Juergen; Scholz, Volkhard [ATB Potsdam (Germany)], E-mail: jkern@atb-potsdam.de

2008-07-01

The emission of N{sub 2}O from the soil has a significant impact on the greenhouse gas balance of energy crops. Soil type, temperature, precipitation, tillage practice and level of fertilization may affect the source strength of N{sub 2}O emissions and fertilizer-induced N{sub 2}O emissions. The N{sub 2}O-fluxes from different sites of an experimental field were measured by the flux chamber method over a period of four years (2003-2006). Poplar and rye as one perennial and one annual crop were fertilized at levels of 0 kg N ha{sup -1} yr{sup -1}, 75 kg N ha{sup -1} yr{sup -1} and 150 kg N ha{sup -1} yr{sup -1}. Enhanced N{sub 2}O emission spots with maxima of up to 1653 {mu}g N{sub 2}O m{sup -2} h{sup -1} were observed at fertilized sites for several weeks. The emissions ranged between 0.4 kg N{sub 2}O-N ha{sup -1} yr{sup -1} and 2.7 kg N{sub 2}O-N ha{sup -1} yr{sup -1} depending on fertilization level, crop variety and year. The mean conversion factor was 2.1% for poplar and 0.9% for rye. The CO{sub 2}-advantage of energy crops is reduced by N{sub 2}O emissions by up to 10%. (author)
Liquid-exfoliation of layered MoS{sub 2} for enhancing photocatalytic activity of TiO{sub 2}/g-C{sub 3}N{sub 4} photocatalyst and DFT study

Energy Technology Data Exchange (ETDEWEB)

Zhang, Weiping; Xiao, Xinyan, E-mail: cexyxiao@scut.edu.cn; Li, Yang; Zeng, Xingye; Zheng, Lili; Wan, Caixia

2016-12-15

Highlights: • MoS{sub 2} nano-sheets were obtained by Liquid-Exfoliation technique. • TiO{sub 2}/g-C{sub 3}N{sub 4}/MoS{sub 2} composites were synthesized by solvothermal method. • The formation mechanism of TiO{sub 2}/g-C{sub 3}N{sub 4}/MoS{sub 2} was studied by DFT method. • The electron-transfer of photocatalyst was discussed at a molecular cluster level. - Abstract: A new combined method of liquid-exfoliation and solvothermal process was employed for synthesizing TiO{sub 2}/g-C{sub 3}N{sub 4}/MoS{sub 2} photocatalysts. In this typical process, the MoS{sub 2}/g-C{sub 3}N{sub 4} nano-sheets was prepared by liquid-exfoliation method from the bulk MoS{sub 2} and bulk carbon nitride in the alcohol system, and then the TiO{sub 2} nanoparticles (NPs) were grown on the MoS{sub 2}/g-C{sub 3}N{sub 4} nano-sheets by in-situ synthesis technique. The evaluation of photocatalytic degradation reaction showed that the as-prepared TiO{sub 2}/g-C{sub 3}N{sub 4}/MoS{sub 2} photocatalysts exhibited higher photocatalytic activity as compared to the pure TiO{sub 2}, pure g-C{sub 3}N{sub 4} and TiO{sub 2}/g-C{sub 3}N{sub 4} composite. The enhanced photocatalytic activities of TiO{sub 2}/g-C{sub 3}N{sub 4}/MoS{sub 2} photocatalysts are attributed to positive synergetic effect of heterostructure between g-C{sub 3}N{sub 4}/MoS{sub 2} hybrid and TiO{sub 2} nano-structure, which not only enlarged spectral response and also enhanced the utilization rate of photons. Furthermore, DFT (Density Functional Theory) was employed to investigate the formation mechanism of the interfaces between TiO{sub 2} NPs and g-C{sub 3}N{sub 4}/MoS{sub 2} nano-sheets, which would be of great importance in revealing the electron-transfer at the interfaces of composites and the mechanism for the great improvement for the activity of TiO{sub 2}/g-C{sub 3}N{sub 4}/MoS{sub 2} photocatalysts.
Associação de níveis plasmáticos de PAI-1 e polimorfismo 4G/5G em pacientes com doença arterial coronariana

Directory of Open Access Journals (Sweden)

Luciana Moreira Lima

2011-12-01

Full Text Available FUNDAMENTO: O polimorfismo 4G/5G do inibidor ativador do plasminogênio tipo 1 (PAI-1 pode influenciar a expressão do PAI-1. Níveis plasmáticos elevados de PAI-1 estão associados com Doença Arterial Coronariana (DAC. OBJETIVO: O presente estudo investigou a influência do polimorfismo 4G/5G do PAI-1 nos níveis plasmáticos de PAI-1 e sua associação com DAC avaliada por angiografia coronária. MÉTODOS: Foi avaliada amostra de sangue de 35 indivíduos com artérias coronárias angiograficamente normais, 31 indivíduos apresentando ateromatose leve/moderada, 57 indivíduos apresentando ateromatose grave e 38 indivíduos saudáveis (controles. Em pacientes e controles, o polimorfismo 4G/5G do PAI-1 foi determinado por amplificação da proteína-C reativa utilizando primers específicos de alelo. Os níveis plasmáticos de PAI-1 foram quantificados pelo ensaio ELISA (American Diagnostica. RESULTADOS: Não houve diferença entre os grupos quanto a sexo, idade e índice de massa corporal. Níveis plasmáticos de PAI-1 e frequência do genótipo 4G/4G mostravam-se significativamente maiores no grupo com ateromatose grave em comparação com os outros grupos (p 70% (p < 0,001. CONCLUSÃO: O achado mais importante deste estudo foi a associação entre o genótipo 4G/4G, elevados níveis plasmáticos de PAI-1 e estenose coronariana superior a 70% em indivíduos brasileiros. Ainda não foi estabelecido se elevados níveis plasmáticos de PAI-1 são um fator decisivo para o agravamento da aterosclerose ou se são uma consequência.
Epitaxial growth of mixed conducting layered Ruddlesden–Popper Lan+1NinO3n+1 (n = 1, 2 and 3) phases by pulsed laser deposition

International Nuclear Information System (INIS)

Wu, Kuan-Ting; Soh, Yeong-Ah; Skinner, Stephen J.

2013-01-01

Graphical abstract: - Highlights: • High quality epitaxial thin films of layered Ruddlesden–Popper nickelates were prepared. • For the first time this has been achieved by the PLD process. • n = 1, 2 and 3 films were successfully deposited on SrTiO 3 and NdGaO 3 substrates. • c-Axis oriented films were confirmed by XRD analysis. • In-plane and out-of-plane strain effects on lattice are discussed. - Abstract: Layered Ruddlesden–Popper phases of composition La n+1 Ni n O 3n+1 (n = 1, 2 and 3) have been epitaxially grown on SrTiO 3 (0 0 1) or NdGaO 3 (1 1 0) single crystal substrates using the pulsed laser deposition technique. X-ray diffraction analyses (θ/2θ, rocking curves, and φ-scans) and atomic force microscopy confirms the high-quality growth of the series of films with low surface roughness values (less than 1 nm). In particular, epitaxial growth of the higher order phases (n = 2 and 3) of lanthanum nickelate have been demonstrated for the first time
Oxide, interface, and border traps in thermal, N2O, and N2O-nitrided oxides

International Nuclear Information System (INIS)

Fleetwood, D.M.; Saks, N.S.

1996-01-01

We have combined thermally stimulated-current (TSC) and capacitance endash voltage (C endash V) measurements to estimate oxide, interface, and effective border trap densities in 6 endash 23 nm thermal, N 2 O, and N 2 O-nitrided oxides exposed to ionizing radiation or high-field electron injection. Defect densities depend strongly on oxide processing, but radiation exposure and moderate high-field stress lead to similar trapped hole peak thermal energy distributions (between ∼1.7 and ∼2.0 eV) for all processes. This suggests that similar defects dominate the oxide charge trapping properties in these devices. Radiation-induced hole and interface trap generation efficiencies (0.1%endash 1%) in the best N 2 O and N 2 O-nitrided oxides are comparable to the best radiation hardened oxides in the literature. After ∼10 Mrad(SiO 2 ) x-ray irradiation or ∼10 mC/cm 2 constant current Fowler endash Nordheim injection, effective border trap densities as high as ∼5x10 11 cm -2 are inferred from C endash V hysteresis. These measurements suggest irradiation and high-field stress cause similar border trap energy distributions. In each case, even higher densities of compensating trapped electrons in the oxides (up to 2x10 12 cm -2 ) are inferred from combined TSC and C endash V measurements. These trapped electrons prevent conventional C endash V methods from providing accurate estimates of the total oxide trap charge density in many irradiation or high-field stress studies. Fewer compensating electrons per trapped hole (∼26%±5%) are found for irradiation of N 2 O and N 2 O-nitrided oxides than for thermal oxides (∼46%±7%). (Abstract Truncated)
Soil and vegetation-atmosphere exchange of NO, NH3, and N2O from field measurements in a semi arid grazed ecosystem in Senegal

Science.gov (United States)

Delon, C.; Galy-Lacaux, C.; Serça, D.; Loubet, B.; Camara, N.; Gardrat, E.; Saneh, I.; Fensholt, R.; Tagesson, T.; Le Dantec, V.; Sambou, B.; Diop, C.; Mougin, E.

2017-05-01

The alternating between dry and wet seasons and the consecutive microbial responses to soil water content in semiarid ecosystems has significant consequences on nitrogen exchanges with the atmosphere. Three field campaigns were carried out in a semi arid sahelian rangeland in Dahra (Ferlo, Senegal), two at the beginning of the wet season in July 2012 and July 2013, and the third one in November 2013 at the end of the wet season. The ammonia emission potentials of the soil ranged from 271 to 6628, indicating the soil capacity to emit NH3. The ammonia compensation point in the soil ranged between 7 and 150 ppb, with soil temperatures between 32 and 37 °C. Ammonia exchange fluctuated between emission and deposition (from -0.1-1.3 ng N.m-2 s-1), depending on meteorology, ambient NH3 concentration (5-11 ppb) and compensation point mixing ratios. N2O fluxes are supposed to be lower than NO fluxes in semi arid ecosystems, but in Dahra N2O fluxes (5.5 ± 1.3 ng N m-2 s-1 in July 2013, and 3.2 ± 1.7 ng N m-2 s-1 in November 2013) were similar to NO fluxes (5.7 ± 3.1 ng N m-2 s-1 in July 2012, 5.1 ± 2.1 ng N m-2 s-1 in July 2013, and 4.0 ± 2.2 ngN m-2 s-1 in November 2013). Possible reasons are the influence of soil moisture below the surface (where N2O is produced) after the beginning of the wet season, the potential aerobic denitrification in microsites, the nitrifier denitrification, and nitrification processes. The presence of litter and standing straw, and their decomposition dominated N compounds emissions in November 2013, whereas emissions in July 2012 and 2013, when the herbaceous strata was sparse, were dominated by microbial processes in the soil. CO2 respiration fluxes were high in the beginning (107 ± 26 mg m-2 h-1 in July 2013) and low in the end of the wet season (32 ± 5 mg m-2 h-1 in November 2013), when autotrophic and heterotrophic activity is reduced due to low soil moisture conditions These results confirm that contrasted ecosystem conditions due
Insights into the photocatalytic mechanism of mediator-free direct Z-scheme g-C3N4/Bi2MoO6(010) and g-C3N4/Bi2WO6(010) heterostructures: A hybrid density functional theory study

CSIR Research Space (South Africa)

Opoku, F

2018-01-01

Full Text Available Graphite-like carbon nitride (g-C3N4)-based heterostructures have received much attention due to their prominent photocatalytic activity. The g-C3N4/Bi2WO6 and g-C3N4/Bi2MoO6 heterostructures, which follow a typical hetero-junction charge transfer...
A Cost-Effective Solid-State Approach to Synthesize g-C3N4 Coated TiO2 Nanocomposites with Enhanced Visible Light Photocatalytic Activity

Directory of Open Access Journals (Sweden)

Min Fu

2013-01-01

Full Text Available Novel graphitic carbon nitride (g-C3N4 coated TiO2 nanocomposites were prepared by a facile and cost-effective solid-state method by thermal treatment of the mixture of urea and commercial TiO2. Because the C3N4 was dispersed and coated on the TiO2 nanoparticles, the as-prepared g-C3N4/TiO2 nanocomposites showed enhanced absorption and photocatalytic properties in visible light region. The as-prepared g-C3N4 coated TiO2 nanocomposites under 450°C exhibited efficient visible light photocatalytic activity for degradation of aqueous MB due to the increased visible light absorption and enhanced MB adsorption. The g-C3N4 coated TiO2 nanocomposites would have wide applications in both environmental remediation and solar energy conversion.
N-point g-loop vertex for a free fermionic theory with arbitrary spin

International Nuclear Information System (INIS)

Di Vecchia, P.; Pezzella, F.; Frau, M.; Hornfeck, K.

1990-01-01

We use the sewing procedure of the operator formalism to construct explicitly the N-point g-loop vertex V N;g for a free fermionic (b, c)-system with conformal weight (λ, 1-λ). We show that this vertex has the structure we expect from geometrical arguments. We obtain also several geometrical objects, e.g. the holomorphic λ-differentials on an arbitrary Riemann surface, which turn out to be expressed as a Poincare θ-series over all elements of the Schottky group. From V N;g we compute explicitly correlation functions for our system, finding agreement with the geometrical procedure. (orig.)
N-point g-loop vertex for a free fermionic theory with arbitrary spin

International Nuclear Information System (INIS)

Di Vecchia, P.; Pezzella, F.; Frau, M.; Hornfeck, K.

1989-07-01

We use the sewing procedure of the operator fomalism to construct explicitly the N-Point g-Loop Vertex V N;g for a free fermionic (b, c)-system with conformal weight (λ, 1-λ). We show that this Vertex has the structure we expect from geometrical arguments. We obtain also several geometrical objects, e.g. the holomorphic λ differentials on an arbitrary Riemann surface, which turn out to be expressed as a Poincare θ series over all elements of the Schottky group. From V N;g we compute explicitly correlation functions for our system, finding agreement with the geometrical procedure. (orig.)
Analysis of SAW properties in ZnO/AlxGa1-xN/c-Al2O3 structures.

Science.gov (United States)

Chen, Ying; Emanetoglu, Nuri William; Saraf, Gaurav; Wu, Pan; Lu, Yicheng; Parekh, Aniruddh; Merai, Vinod; Udovich, Eric; Lu, Dong; Lee, Dong S; Armour, Eric A; Pophristic, Milan

2005-07-01

Piezoelectric thin films on high acoustic velocity nonpiezoelectric substrates, such as ZnO, AlN, or GaN deposited on diamond or sapphire substrates, are attractive for high frequency and low-loss surface acoustic wave devices. In this work, ZnO films are deposited on AlxGa1-xN/c-Al2O3 (0 structure provides several advantages, including higher order wave modes with higher velocity and larger electromechanical coupling coefficient (K2). The surface acoustic wave (SAW) velocities and coupling coefficients of the ZnO/AlxGa1-xN/c-Al2O3 structure are tailored as a function of the Al mole percentage in AlxGa1-xN films, and as a function of the ZnO (h1) to AlxGa1-xN (h2) thickness ratio. It is found that a wide thickness-frequency product (hf) region in which coupling is close to its maximum value, K(2)max, can be obtained. The K(2)max of the second order wave mode (h1 = h2) is estimated to be 4.3% for ZnO/GaN/c-Al2O3, and 3.8% for ZnO/AlN/c-Al2O3. The bandwidth of second and third order wave modes, in which the coupling coefficient is within +/- 0.3% of K(2)max, is calculated to be 820 hf for ZnO/GaN/c-Al2O3, and 3620 hf for ZnO/AlN/c-Al2O3. Thus, the hf region in which the coupling coefficient is close to the maximum value broadens with increasing Al content, while K(2)max decreases slightly. When the thickness ratio of AlN to ZnO increases, the K(2)max and hf bandwidth of the second and third higher wave modes increases. The SAW test devices are fabricated and tested. The theoretical and experimental results of velocity dispersion in the ZnO/AlxGa1-xN/c-Al2O3 structures are found to be well matched.

Tillage effects on N2O emissions as influenced by a winter cover crop

DEFF Research Database (Denmark)

Petersen, Søren O; Mutegi, James; Hansen, Elly Møller

2011-01-01

emissions may be more important than the effect on soil C. This study monitored emissions of N2O between September 2008 and May 2009 in three tillage treatments, i.e., conventional tillage (CT), reduced tillage (RT) and direct drilling (DD), all with (+CC) or without (−CC) fodder radish as a winter cover...... application by direct injection N2O emissions were stimulated in all tillage treatments, reaching 250–400 μg N m−2 h−1 except in the CT + CC treatment, where emissions peaked at 900 μg N m−2 h−1. Accumulated emissions ranged from 1.6 to 3.9 kg N2O ha−1. A strong positive interaction between cover crop......Conservation tillage practices are widely used to protect against soil erosion and soil C losses, whereas winter cover crops are used mainly to protect against N losses during autumn and winter. For the greenhouse gas balance of a cropping system the effect of reduced tillage and cover crops on N2O...
Efecto de las nanopartículas industriales TiO 2 , SiO 2 y ZnO sobre la viabilidad celular y expresión génica en médula ósea roja de mus musculus

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Jacquelyne Zarria-Romero

Full Text Available RESUMEN Objetivos Evaluar el efecto de las nanopartículas de ZnO, TiO2 y SiO2 sobre la viabilidad celular y la expresión génica de las interleuquinas 7 y 3 y del factor estimulante de colonias de granulocito - macrófago (GM-CSF en Mus musculus. Materiales y métodos Se extrajo médula ósea roja de cinco roedores (Balb/c para el estudio de viabilidad celular mediante la prueba de MTT. Por otro lado, grupos cinco roedores fueron inoculados vía intraperitoneal con dosis de 0,5; 1; 2,5; 5 y 10 mg/kg de nanopartículas de ZnO y SiO2 y de 5; 10; 15; 20 y 25 mg/kg de nanopartículas de TiO2, 30 h después, se obtuvo el ARN a partir de la médula ósea roja para los análisis de expresión génica empleando las técnicas de PCR y RT-PCR cuantitativa. Resultados Las nanopartículas de ZnO y SiO2 redujeron la viabilidad celular de una manera dosis-dependiente en un 37 y 26%, respectivamente, a partir de una dosis de 1 mg/kg. En cuanto al efecto sobre la expresión génica, a las dosis 5 y 10 mg/kg, las nanopartículas de TiO2 redujeron en mayor porcentaje la expresión de las interleuquinas 7 y 3 (55,3 y 70,2% respectivamente, con respecto a la expresión del GM-CSF, el mayor porcentaje de reducción lo produjo las nanopartículas de SiO2 (91%. Las nanopartículas de ZnO redujeron a partir de las dosis de 20 y 25 mg/kg. Conclusiones Las nanopartículas de ZnO, SiO2 y TiO2 alteran la viabilidad celular y la expresión génica en la médula ósea de ratón.
In Situ Growth of MnO2 Nanosheets on N-Doped Carbon Nanotubes Derived from Polypyrrole Tubes for Supercapacitors.

Science.gov (United States)

Ou, Xu; Li, Qi; Xu, Dan; Guo, Jiangna; Yan, Feng

2018-03-02

Nitrogen-doped porous carbon nanotubes@MnO 2 (N-CNTs@MnO 2 ) nanocomposites are prepared through the in situ growth of MnO 2 nanosheets on N-CNTs derived from polypyrrole nanotubes (PNTs). Benefiting from the synergistic effects between N-CNTs (high conductivity and N doping level) and MnO 2 nanosheets (high theoretical capacity), the as-prepared N-CNTs@MnO 2 -800 nanocomposites show a specific capacitance of 219 F g -1 at a current density of 1.0 A g -1 , which is higher than that of pure MnO 2 nanosheets (128 F g -1 ) and PNTs (42 F g -1 ) in 0.5 m Na 2 SO 4 solution. Meanwhile, the capacitance retention of 86.8 % (after 1000 cycles at 10 A g -1 ) indicates an excellent electrochemical performance of N-CNTs@MnO 2 prepared in this work. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
2D-2D stacking of graphene-like g-C{sub 3}N{sub 4}/Ultrathin Bi{sub 4}O{sub 5}Br{sub 2} with matched energy band structure towards antibiotic removal

Energy Technology Data Exchange (ETDEWEB)

Ji, Mengxia; Di, Jun; Ge, Yuping; Xia, Jiexiang, E-mail: xjx@ujs.edu.cn; Li, Huaming, E-mail: lhm@ujs.edu.cn

2017-08-15

Highlights: • 2D-2D graphene-like g-C{sub 3}N{sub 4}/ultrathin Bi{sub 4}O{sub 5}Br{sub 2} materials have been prepared. • With matched energy band structure, the effective charge separation can be achieved. • The holes and O{sub 2}{sup −} are determined to be the main active species. - Abstract: A novel visible-light-driven 2D-2D graphene-like g-C{sub 3}N{sub 4}/ultrathin Bi{sub 4}O{sub 5}Br{sub 2} photocatalyst was prepared via a facile solvothermal method in the presence of reactable ionic liquid 1-hexadecyl-3-methylimidazolium bromide ([C{sub 16}mim]Br) for the first time. FT-IR, XPS and TEM analysis results demonstrated the successful introduction of the 2D graphene-like g-C{sub 3}N{sub 4} material to the Bi{sub 4}O{sub 5}Br{sub 2} system. DRS and BET analysis results indicated the existence of the g-C{sub 3}N{sub 4} could lead to the broaden absorption edge and larger surface area of the ultrathin Bi{sub 4}O{sub 5}Br{sub 2} nanosheets. The electrochemical analysis implied a fast transfer of the interfacial electrons and low recombination rate of photogenerated charge carriers in g-C{sub 3}N{sub 4}/Bi{sub 4}O{sub 5}Br{sub 2}, which could be assigned to the sufficient and tight contact between ultrathin Bi{sub 4}O{sub 5}Br{sub 2} and graphene-like g-C{sub 3}N{sub 4}. The quinolone antibiotic ciprofloxacin (CIP) was chosen as the target pollutant to evaluate the photocatalytic performance of the as-prepared samples under visible light irradiation. 1 wt% g-C{sub 3}N{sub 4}/Bi{sub 4}O{sub 5}Br{sub 2} composite exhibited the highest photocatalytic degradation performance among all of the as-prepared photocatalysts. The enhancement of photocatalytic activity was attributed to the maximum contact between graphene-like g-C{sub 3}N{sub 4} and ultrathin Bi{sub 4}O{sub 5}Br{sub 2} material with matched energy band structure, which enable the efficient charge seperation. A possible photocatalytic mechanism also was proposed.
N2O Emission from energy crop fields

International Nuclear Information System (INIS)

Joergensen, B.J.; Nyholm Joergensen, R.

1996-03-01

The interest in N 2 O emissions from soils with energy crops is a results of its properties as a greenhouse gas, since the global warming potential of N 2 O per unit mass is about 320 times greater than CO 2 . The contribution of N 2 O from the soil to the atmosphere may increase due to agricultural management. Consequently, large N 2 O emissions can lower the reduction of the greenhouse effect achieved by the substitution of fossil fuels by energy crops. For this reason it is crucial to find the crops for combustion with the lowest potential for emission of N 2 O from the soil per produced energy unit. The aims of this study were to assess the annual N 2 O flux from a Miscanthus 'Giganteus' (M. 'Giganteus') and winter rye (Secale cereale) field, and to investigate the factors affecting the N 2 O emission. To obtain these aims a method was developed for measurements in tall crops. The thesis contains a literature review on the N 2 O emission from the soils, a section with development of the technique for N 2 O flux measurements, and an experimental section. Finally, the thesis contains a section where the results are discussed in relation to the use of energy crops. In all the filed studies, the N 2 O emission was measured by using a new developed closed-chamber technique. The main advantages of the chamber method were the ability to contain growing plants up to a height of 3 m, and the relatively large area (2X2m) covered by each other. Soils with annual and perennial crops can be expected to emit less then 3 kg N 2 O ha -1 yr -1 . This amount corresponds to 960 kg CO 2 ha -1 yr -1 compared to a total CO 2 reduction of 10 to 19 tons CO 2 ha -1 yr -1 using the energy crops as substitution for fossil fuels. An efficient way to reduce the N 2 O emission is to exclude use of fertiliser but this also reduces the dry matter yield and consequently also the CO 2 reduction per unit dry matter. Following the guidelines for good agricultural practice concerning the
An automated GC-C-GC-IRMS setup to measure palaeoatmospheric δ13C-CH4, δ15N-N2O and δ18O-N2O in one ice core sample

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P. Sperlich

2013-08-01

Full Text Available Air bubbles in ice core samples represent the only opportunity to study the mixing ratio and isotopic variability of palaeoatmospheric CH4 and N2O. The highest possible precision in isotope measurements is required to maximize the resolving power for CH4 and N2O sink and source reconstructions. We present a new setup to measure δ13C-CH4, δ15N-N2O and δ18O-N2O isotope ratios in one ice core sample and with one single IRMS instrument, with a precision of 0.09, 0.6 and 0.7‰, respectively, as determined on 0.6–1.6 nmol CH4 and 0.25–0.6 nmol N2O. The isotope ratios are referenced to the VPDB scale (δ13C-CH4, the N2-air scale (δ15N-N2O and the VSMOW scale (δ18O-N2O. Ice core samples of 200–500 g are melted while the air is constantly extracted to minimize gas dissolution. A helium carrier gas flow transports the sample through the analytical system. We introduce a new gold catalyst to oxidize CO to CO2 in the air sample. CH4 and N2O are then separated from N2, O2, Ar and CO2 before they get pre-concentrated and separated by gas chromatography. A combustion unit is required for δ13C-CH4 analysis, which is equipped with a constant oxygen supply as well as a post-combustion trap and a post-combustion GC column (GC-C-GC-IRMS. The post-combustion trap and the second GC column in the GC-C-GC-IRMS combination prevent Kr and N2O interferences during the isotopic analysis of CH4-derived CO2. These steps increase the time for δ13C-CH4 measurements, which is used to measure δ15N-N2O and δ18O-N2O first and then δ13C-CH4. The analytical time is adjusted to ensure stable conditions in the ion source before each sample gas enters the IRMS, thereby improving the precision achieved for measurements of CH4 and N2O on the same IRMS. The precision of our measurements is comparable to or better than that of recently published systems. Our setup is calibrated by analysing multiple reference gases that were injected over bubble-free ice samples. We show
Effect of COD/N ratio on N2O production during nitrogen removal by aerobic granular sludge.

Science.gov (United States)

Velho, V F; Magnus, B S; Daudt, G C; Xavier, J A; Guimarães, L B; Costa, R H R

2017-12-01

N 2 O-production was investigated during nitrogen removal using aerobic granular sludge (AGS) technology. A pilot sequencing batch reactor (SBR) with AGS achieved an effluent in accordance with national discharge limits, although presented a nitrite accumulation rate of 95.79% with no simultaneous nitrification-denitrification. N 2 O production was 2.06 mg L -1 during the anoxic phase, with N 2 O emission during air pulses and the aeration phase of 1.6% of the nitrogen loading rate. Batch tests with AGS from the pilot reactor verified that at the greatest COD/N ratio (1.55), the N 2 O production (1.08 mgN 2 O-N L -1 ) and consumption (up to 0.05 mgN 2 O-N L -1 ), resulted in the lowest remaining dissolved N 2 O (0.03 mgN 2 O-N L -1 ), stripping the minimum N 2 O gas (0.018 mgN 2 O-N L -1 ). Conversely, the carbon supply shortage, under low C/N ratios, increased N 2 O emission (0.040 mgN 2 O-N L -1 ), due to incomplete denitrification. High abundance of ammonia-oxidizing and low abundance of nitrite-oxidizing bacteria were found, corroborating the fact of partial nitrification. A denitrifying heterotrophic community, represented mainly by Pseudoxanthomonas, was predominant in the AGS. Overall, the AGS showed stable partial nitrification ability representing capital and operating cost savings. The SBR operation flexibility could be advantageous for controlling N 2 O emissions, and extending the anoxic phase would benefit complete denitrification in cases of low C/N influents.
Enhanced performance of dye-sensitized solar cells based on organic dopant incorporated PVDF-HFP/PEO polymer blend electrolyte with g-C3N4/TiO2 photoanode

International Nuclear Information System (INIS)

Senthil, R.A.; Theerthagiri, J.; Madhavan, J.; Murugan, K.; Arunachalam, Prabhakarn; Arof, A.K.

2016-01-01

This work describes the effect of 2-aminopyrimidine (2-APY) on poly(vinylidinefluoride-co-hexafluoropropylene) (PVDF-HFP)/polyethylene oxide (PEO) blend polymer electrolyte along with binary iodide salts (tetrabutylammonium iodide (TBAI) and potassium iodide (KI)) and iodine (I 2 ) were studied for enhancing the efficiency of the dye-sensitized solar cells (DSSCs) consisting of g-C 3 N 4 /TiO 2 composite as photoanode. The g-C 3 N 4 was synthesized from low cost urea by thermal condensation method. It was used as a precursor to synthesize the various weight percentage ratios (5%, 10% and 15%) of g-C 3 N 4 /TiO 2 composites by wet-impregnation method. The pure and 2-APY incorporated PVDF-HFP/PEO polymer blend electrolytes were arranged by wet chemical process (casting method) using DMF as a solvent. The synthesized g-C 3 N 4 /TiO 2 composites and polymer blend electrolytes were studied and analyzed by Fourier transform infrared (FT-IR) spectroscopy, X-ray diffractometer (XRD) and scanning electron microscopy (SEM). The ionic conductivity values of the pure and 2-APY incorporated PVDF-HFP/PEO blend electrolytes were estimated to be 4.53×10 −5 and 1.87×10 −4 Scm −1 respectively. The UV–vis absorption spectroscopy was carried out for the pure and different wt% of g-C 3 N 4 /TiO 2 composites coated FTO films after N3 dye-sensitization. The 10 wt% g-C 3 N 4 /TiO 2 composite film showed a maximum absorption compared to the others. The DSSC assembled with 10 wt% g-C 3 N 4 /TiO 2 as photoanode using the pure polymer blend electrolyte exhibited a power conversion efficiency (PCE) of 3.17% , which was superior than that of DSSC based pure TiO 2 (2.46%). However, the PCE was increased to 4.73% for the DSSC assembled using 10 wt% g-C 3 N 4 /TiO 2 as photoanode with 2-APY incorporated polymer blend electrolyte. Hence, the present study is a successful attempt to provide a new pathway to enhance the performance of DSSCs. - Graphical abstract: In this study, the g-C 3 N
Thermal expansion of superconducting phases Bi2Sr2Can-1CunO2n+2+δ with n=1,2,3

International Nuclear Information System (INIS)

Zhurov, V.V.; Ivanov, S.A.; Bush, A.A.; Romanov, B.N.

1990-01-01

Consideration is given to results of X-ray diffraction studies of temperature dependences of a 0 ,c 0 sublattice parameters of Bi 2 Sr 2 Ca n-1 Cu n O 2n+2+ δ superconducting phases with n=1,2,3 (2201, 2212, 2223) in 90-1000 K range. The obtained dependences are composed of some temperature linear sections, where values of thermal coefficients of linear expansion α a , α c were determined for all examined phases. During first heating of samples of 2212 phase a 0 (T), c 0 (T) dependences deviate in ≅500-700 K range from linear ones till the occurence of a section with negative a c . After heating of 2212 phase up to T>≅700 K and cooling down to 300 K, a 0 ,c 0 parameters decrease by ≅0.006 and 0.08 A respectively. Data on the effect of preparation method and thermal prehistory of 2212 samples and on relative content of calcium atoms in them for these anomalies were obtained. Some possible reasons of their occurence were analyzed
Magnetic properties of Aurivillius lanthanide-bismuth (LnFeO3nBi4Ti3O12 (n = 1,2 layered titanates

Directory of Open Access Journals (Sweden)

Tartaj, J.

2008-06-01

Full Text Available Bismuth titanates of Aurivillius layer-structure (BiFeO3nBi4Ti3O12, are of great technological interest because of their applications as non-volatile ferroelectric memories and high-temperature piezoelectric materials. The synthesis and crystallographic characterization of a new family of compounds (LnFeO3nBi4Ti3O12 was recently reported, in which the layers consist of LnFeO3 perovskites with a lanthanide Ln3+ substituting diamagnetic Bi3+. We report herein the magnetic properties of bulk samples, with Ln = Nd, Eu, Gd and Tb, and n = 1 and 2. Single-layer materials are paramagnetic, similar to non-substituted bismuth titanate Bi5FeTi3O15, and show crystal field effects due to the crystallographic environment of Eu3+ and Tb3+. Several anomalies are detected in the magnetization M(T of double-layer (LnFeO32Bi4Ti3O12 compounds, related to the strong magnetism of Tb and Gd, since they weakly appear for Nd and they are absent in the VanVleck Eu3+ ion and in the parent Bi6Fe2Ti3O18 compound.Los titanatos de hierro y bismuto con estructura laminar tipo Aurivillius, (BiFeO3nBi4Ti3O12, tienen un gran interés tecnológico debido a sus aplicaciones como memorias ferroeléctricas no volátiles y como piezoeléctrico cerámico de alta temperatura. La síntesis y la caracterización cristalina de una nueva familia de compuestos (LnFeO3nBi4Ti3O12 han sido recientemente reportadas, en la que el catión diamagnético Bi3+ ha sido sustituido por los paramagnéticos Ln3+ en los bloques de perovskita. Se estudian las propiedades magnéticas de muestras cerámicas en volumen con Ln = Nd, Eu, Gd y Tb, y n = 1 y 2. Los materiales con n=1 son paramagnéticos y similares al no sustituido Bi5FeTi3O15, y muestran efectos de campo cristalino debido al entorno cristalino de Eu3+ y Tb3+. Se han detectado algunas anomalías en la magnetización M(T de los compuestos n=2 (LnFeO32Bi4Ti3O12 que están relacionadas con el fuerte magnetismo de Tb y Gd, que aparecen d
Improved performance of AlGaN/GaN HEMT by N2O plasma pre-treatment

International Nuclear Information System (INIS)

Mi Min-Han; Zhang Kai; Zhao Sheng-Lei; Wang Chong; Zhang Jin-Cheng; Ma Xiao-Hua; Hao Yue

2015-01-01

The influence of an N 2 O plasma pre-treatment technique on characteristics of AlGaN/GaN high electron mobility transistor (HEMT) prepared by using a plasma-enhanced chemical vapor deposition (PECVD) system is presented. After the plasma treatment, the peak transconductance (g m ) increases from 209 mS/mm to 293 mS/mm. Moreover, it is observed that the reverse gate leakage current is lowered by one order of magnitude and the drain current dispersion is improved in the plasma-treated device. From the analysis of frequency-dependent conductance, it can be seen that the trap state density (D T ) and time constant (τ T ) of the N 2 O-treated device are smaller than those of a non-treated device. The results indicate that the N 2 O plasma pre-pretreatment before the gate metal deposition could be a promising approach to enhancing the performance of the device. (paper)
Investigation of nitrous oxide (N2O) abatement technologies. 2; Asanka chisso (N2O) no teigen taisaku ni kansuru chosa. 2

Energy Technology Data Exchange (ETDEWEB)

NONE

1997-03-01

Emission amount of nitrous oxide (N2O) from anthropogenic sources is analyzed, and reduction effects by the abatement technologies are evaluated. The concentration of nitrous oxide in the atmosphere continues to increase and emissions from agricultural and ecosystem sources are drawing particular attention. For the emission of N2O in Japan, 8.28 Gg-N2O per year is emitted from fossil fuel combustion facilities, 6.95 from waste incineration facilities, 22.5 from transportation vehicles including automobiles, 26.7 from the chemical industry including establishments engaged in adipic acid production, 2.1 from sewage treatment facilities including septic tanks, 6.3 from farmland, and 7.1 from livestock excrement. For the N2O abatement technologies for different sources, fuel improvement, high temperature combustion, acceleration of reduction decomposition reaction, and development of catalysts are significant for the combustion technologies. In connection with N2O discharged in the process of adipic acid production, major businesses have internationally committed to up to 99% abatement of the N2O emissions by 1998. With regard to wastewater and sewage treatment facilities and septic tanks, improvement in COD/NO-N ratio, retention period, pH level, and reduction process is pointed out. 204 refs., 70 figs., 53 tabs.
Microsolvation effect and hydrogen-bonding pattern of taurine-water TA-(H2O)n (n = 1-3) complexes.

Science.gov (United States)

Dai, Yumei; Wang, Yuhua; Huang, Zhengguo; Wang, Hongke; Yu, Lei

2012-01-01

The microsolvation of taurine (TA) with one, two or three water molecules was investigated by a density functional theory (DFT) approach. Quantum theory of atoms in molecules (QTAIM) analyses were employed to elucidate the hydrogen bond (H-bond) interaction characteristics in TA-(H(2)O)(n) (n = 1-3) complexes. The results showed that the intramolecular H-bond formed between the hydroxyl and the N atom of TA are retained in most TA-(H(2)O)(n) (n = 1-3) complexes, and are strengthened via cooperative effects among multiple H-bonds from n = 1-3. A trend of proton transformation exists from the hydroxyl to the N atom, which finally results in the cleavage of the origin intramolecular H-bond and the formation of a new intramolecular H-bond between the amino and the O atom of TA. Therefore, the most stable TA-(H(2)O)(3) complex becomes a zwitterionic complex rather than a neutral type. A many-body interaction analysis showed that the major contributors to the binding energies for complexes are the two-body energies, while three-body energies and relaxation energies make significant contributions to the binding energies for some complexes, whereas the four-body energies are too small to be significant.
Pyrrolic-N-doped graphene oxide/Fe2O3 mesocrystal nanocomposite: Efficient charge transfer and enhanced photo-Fenton catalytic activity

Science.gov (United States)

Liu, Bing; Tian, Lihong; Wang, Ran; Yang, Jinfeng; Guan, Rong; Chen, Xiaobo

2017-11-01

Though α-Fe2O3 has attracted much attention in photocatalytic or Fenton-catalytic degradation of organic contaminants, its performance is still unsatisfactory due to fast recombination of electrons and holes in photocatalytic process and the difficult conversion of Fe(II) and Fe(III) in Fenton reaction. Herein, a pyrrolic N-doped graphene oxide/Fe2O3 mesocrystal (NG-Fe2O3) nanocomposite with good distribution is synthesized by a simple solvothermal method and adjusting the oxygen-containing groups on graphene oxide. The morphology of NG-Fe2O3 contributes to a relatively large BET surface area and an intimate contact between NG and Fe2O3. These two important factors along with the excellent electro-conductivity of pyrrolic-N doped GO result in the efficient separation of electron-hole pairs and fast conversion of Fe(II)and Fe(III) in photo-Fenton synergistic reaction. Thus, a remarkably improved photo-Fenton catalytic activity of NG-Fe2O3 is obtained. The degrading rate on methyl blue increases by 1.5 times and the conversion rate of glyphosate increases by 2.3 times under visible light irradiation, compared to pristine α-Fe2O3 mesocrystals.
Ethanol oxidation reactions catalyzed by water molecules: CH3CH2OH+n H2O→ CH3CHO+ H2+n H2O (n=0,1,2)

Science.gov (United States)

Takahashi, H.; Hisaoka, S.; Nitta, T.

2002-09-01

Ab initio density functional theory calculations have been performed to investigate the catalytic role of water molecules in the oxidation reaction of ethanol: CH3CH2OH+n H2O→ CH3CHO+ H2+n H2O (n=0,1,2) . The results show that the potential energy barrier for the reaction is 88.0 kcal/mol in case of n=0, while it is reduced by ˜34 kcal/mol when two water molecules are involved ( n=2) in the reaction. As a result, the rate constant increases to 3.31×10 -4 s-1, which shows a significant catalytic role of water molecules in the ethanol oxidation reactions.
Production of N{sub 2}O in grass-clover pastures

Energy Technology Data Exchange (ETDEWEB)

Carter, M.S.

2005-09-01

Agricultural soils are known to be a considerable source of the strong greenhouse gas nitrous oxide (N{sub 2}O), and in soil N{sub 2}O is mainly produced by nitrifying and denitrifying bacteria. In Denmark, grass-clover pastures are an important component of the cropping system in organic as well as conventional dairy farming, and on a European scale grass-clover mixtures represent a large part of the grazed grasslands. Biological dinitrogen (N{sub 2}) fixation in clover provides a major N input to these systems, but knowledge is sparse regarding the amount of fixed N{sub 2} lost from the grasslands as N2O. Furthermore, urine patches deposited by grazing cattle are known to be hot-spots of N{sub 2}O emission, but the mechanisms involved in the N{sub 2}O production in urine-affected soil are very complex and not well understood. The aim of this Ph.D. project was to increase the knowledge of the biological and physical-chemical mechanisms, which control the production of N2O in grazed grass-clover pastures. Three experimental studies were conducted with the objectives of: 1: assessing the contribution of recently fixed N{sub 2} as a source of N{sub 2}O. 2: examining the link between N{sub 2}O emission and carbon mineralization in urine patches. 3: investigating the effect of urine on the rates and N{sub 2}O loss ratios of nitrification and denitrification, and evaluating the impact of the chemical conditions that arise in urine affected soil. The results revealed that only 3.2 {+-} 0.5 ppm of the recently fixed N{sub 2} was emitted as N2O on a daily basis. Thus, recently fixed N released via easily degradable clover residues appears to be a minor source of N2O. Furthermore, increased N{sub 2}O emission following urine application at rates up to 5.5 g N m{sup -2} was not caused by enhanced denitrification stimulated by labile compounds released from scorched plant roots. Finally, the increase of soil pH and ammonium following urine application led to raised
SnO2 nanocrystals anchored on N-doped graphene for high-performance lithium storage.

Science.gov (United States)

Zhou, Wei; Wang, Jinxian; Zhang, Feifei; Liu, Shumin; Wang, Jianwei; Yin, Dongming; Wang, Limin

2015-02-28

A SnO2-N-doped graphene (SnO2-NG) composite is synthesized by a rapid, facile, one-step microwave-assisted solvothermal method. The composite exhibits excellent lithium storage capability and high durability, and is a promising anode material for lithium ion batteries.
Vibrational spectroscopy of NO^+(H_2O)_n: Evidence for the intracluster reaction NO^+(H_2O)_n→H_3O^+(H_2O)_(n-2)(HONO) at n≥4

OpenAIRE

Choi, Jong-Ho; Kuwata, Keith T.; Haas, Bernd-Michael; Cao, Yibin; Johnson, Matthew S.; Okumura, Mitchio

1994-01-01

Infrared spectra of mass‐selected clusters NO^+(H_2O)_n for n=1 to 5 were recorded from 2700 to 3800 cm^(−1) by vibrational predissociation spectroscopy. Vibrational frequencies and intensities were also calculated for n=1 and 2 at the second‐order Møller–Plesset (MP2) level, to aid in the interpretation of the spectra, and at the singles and doubles coupled cluster (CCSD) level energies of n=1 isomers were computed at the MP2 geometries. The smaller clusters (n=1 to 3) were complexes of H_2O...
Rational construction of Z-scheme Ag{sub 2}CrO{sub 4}/g-C{sub 3}N{sub 4} composites with enhanced visible-light photocatalytic activity

Energy Technology Data Exchange (ETDEWEB)

Luo, Jin, E-mail: lj328520504@126.com; Zhou, Xiaosong; Ma, Lin; Xu, Xuyao

2016-12-30

Highlights: • Novel visible-light driven Ag{sub 2}CrO{sub 4}/g-C{sub 3}N{sub 4} composites were synthesized. • Ag{sub 2}CrO{sub 4}/g-C{sub 3}N{sub 4} exhibited enhanced visible-light photocatalytic activity. • The reasons for the enhanced photocatalytic activity were revealed. - Abstract: Novel visible-light driven Z-scheme Ag{sub 2}CrO{sub 4}/g-C{sub 3}N{sub 4} composites with different contents of Ag{sub 2}CrO{sub 4} were fabricated by a facile chemical precipitation method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance spectroscopy (UV-vis DRS), photoluminescence (PL) spectroscopy and photoelectrochemical measurements. Compared with individual g-C{sub 3}N{sub 4} and Ag{sub 2}CrO{sub 4}, the Ag{sub 2}CrO{sub 4}/g-C{sub 3}N{sub 4} composites displayed much larger photocatalytic activities for the photocatalytic degradation of methyl orange (MO) solution at room temperature under visible light irradiation (λ > 420 nm). Importantly, the optimum photodegradation rate constant of the Ag{sub 2}CrO{sub 4}/g-C{sub 3}N{sub 4} composite at a theoretical weight content of 8.0% Ag{sub 2}CrO{sub 4} for the photodegradation of MO was 0.0068 min{sup −1}, which was 5.7 and 4.3 times higher than that of pure g-C{sub 3}N{sub 4} and Ag{sub 2}CrO{sub 4}, respectively. Such enormous enhancement in photocatalytic performance was predominantly ascribed to the efficient separation and transfer of photogenerated electrons and holes at the Ag{sub 2}CrO{sub 4}/g-C{sub 3}N{sub 4} interface imparted through the Z-scheme electron transfer. Furthermore, radical trap experiments depicted that both the holes and superoxide radical anions were thought to dominate oxidative species of the Ag{sub 2}CrO{sub 4}/g-C{sub 3}N{sub 4} composite for MO degradation under visible light irradiation. Ultimately, a tentative Z-scheme photodegradation mechanism
O{sub 2} adsorption and dissociation on the Pd{sub 13-n}Ni{sub n}@Pt{sub 42} (n = 0, 1, 12, and 13) tri-metallic nanoparticles: A DFT study

Energy Technology Data Exchange (ETDEWEB)

Li, Sha; Yang, Yongpeng; Huang, Shiping, E-mail: huangsp@mail.buct.edu.cn

2017-07-15

Highlights: • O{sub 2} adsorption and dissociation on Pd{sub 13-n}Ni{sub n}@Pt{sub 42} NPs are performed by DFT. • Adsorption energies of O{sub 2} and O are strongly affected by the coordination number. • Adsorption energy and d-band center displays the opposite change tendency. • Ni{sub 13}@Pt{sub 42} is the most active catalyst among Pd{sub 13-n}Ni{sub n}@Pt{sub 42} (n = 0, 1, 12, and 13) NPs. - Abstract: Density functional theory calculations are performed to investigate O{sub 2} adsorption and dissociation on the icosahedral Pd{sub 13-n}Ni{sub n}@Pt{sub 42} (n = 0, 1, 12, and 13) tri-metallic nanoparticles. The parallel adsorption of O{sub 2} on Pd{sub 13-n}Ni{sub n}@Pt{sub 42} (n = 0, 1, 12, and 13) is stronger than the vertical adsorption. The adsorption of O{sub 2} on the bridge site (B1) is favorable in the Pd{sub 13-n}Ni{sub n}@Pt{sub 42} (n = 0, 1, 12, and 13) nanoparticles, while the adsorption of O atom on the hollow site (H1) is preferred. The adsorption energies of O{sub 2} and O are strongly affected by the coordination number. Low coordination site shows strong adsorption of O{sub 2} and O on the Pd{sub 13-n}Ni{sub n}@Pt{sub 42} (n = 0, 1, 12, and 13) nanoparticles. The adsorption energies of O{sub 2} and O atoms are found to be correlated well with the d-band center of surface Pt. For the Pd{sub 13-n}Ni{sub n}@Pt{sub 42} (n = 0, 1, 12, and13) nanoparticles catalysts, the ORR activity follows the order of Ni{sub 13}@Pt{sub 42} > Pd{sub 13}@Pt{sub 42} > Pd{sub 12}Ni{sub 1}@Pt{sub 42} > Pd{sub 1}Ni{sub 12}@Pt{sub 42}, illustrating that the Ni{sub 13}@Pt{sub 42} is the strongest ORR activity among the Pd{sub 13-n}Ni{sub n}@Pt{sub 42} (n = 0, 1, 12, and13) nanoparticles catalysts. Our results have important significance to understand the mechanism of O{sub 2} dissociation on the Pd{sub 13-n}Ni{sub n}@Pt{sub 42} (n = 0, 1, 12, and 13) tri-metallic nanoparticles.

Broadband sensitized white light emission of g-C_3N_4/Y_2MoO_6:Eu"3"+ composite phosphor under near ultraviolet excitation

International Nuclear Information System (INIS)

Han, Bing; Xue, Yongfei; Li, Pengju; Zhang, Jingtao; Zhang, Jie; Shi, Hengzhen

2015-01-01

The g-C_3N_4/Y_2MoO_6:Eu"3"+ composite phosphors were synthesized and characterized by X-ray diffraction, Fourier transform-infrared spectroscopy, ultraviolet visible diffuse reflection spectra, photoluminescence spectra and luminescence decay curves. Under the excitation of 360 nm near ultraviolet light, these composite phosphors show tunable emission from blue to red region, in which white light emission can be obtained in term of appropriate quality proportion of Y_2MoO_6:Eu"3"+ relative to g-C_3N_4/Y_2MoO_6:Eu"3"+. In addition, the emission color can be also dependent on the excitation wavelength in g-C_3N_4/Y_2MoO_6:Eu"3"+ composite phosphor. - Graphical abstract: Under the excitation of 360 nm near ultraviolet light, the g-C_3N_4/Y_2MoO_6:Eu"3"+ composite phosphors show tunable emission from blue to red region, in which white light emission can be obtained. - Highlights: • The g-C3N4/Y2MoO6:Eu"3"+ composite phosphors were synthesized and characterized. • White light emission was realized in the g-C3N4/Y2MoO6:Eu"3"+ composites under UV excitation. • A novel idea to realize the broadband sensitized white light emission in phosphors was provided.
Bis[μ-2-(2,4-difluorophenyl-1,3-bis(1,2,4-triazol-1-ylpropan-2-olato-κ4N2,O:O,N2′]bis[(acetato-κ2O,O′nickel(II] methanol hemisolvate

Directory of Open Access Journals (Sweden)

Feng Zhang

2010-01-01

Full Text Available In the title complex, [Ni2(C13H11F2N6O2(C2H3O22]·0.5CH3OH, there are two half-molecules in the asymmetric unit. The two centrosymmetrically related NiII atoms, each attached to an acetate ligand, are linked by two fluconazole ligands. Each NiII atom is six-coordinated in a distorted octahedral geometry by two N atoms of the triazole groups and two bridging O atoms from two different fluconazole ligands and two O atoms from a chelating acetate ligand. In the crystal structure, the half-occupied methanol solvent molecule is linked to a triazole group via an O—H...N hydrogen bond.
Effects of Carbon and Cover Crop Residues on N2O and N2 Emissions

Science.gov (United States)

Burger, M.; Cooperman, Y.; Horwath, W. R.

2016-12-01

In Mediterranean climate, nitrous oxide emissions occurring with the first rainfall after the dry summer season can contribute up to 50% of agricultural systems' total annual emissions, but the drivers of these emissions have not been clearly identified, and there are only few measurements of atmospheric nitrogen (N2) production (denitrification) during these events. In lab incubations, we investigated N2O and N2 production, gross ammonification and nitrification, and microbial N immobilization with wet-up in soil from a vineyard that was previously fallow or where cover crop residue had been incorporated the previous spring. Before the first rainfall, we measured 120 mg dissolved organic carbon (DOC-C) kg-1 soil in the 0-5 cm layer of this vineyard, and after the rain 10 mg DOC-C kg-1, while nitrate levels before the rain were cover cropped soil. The N2O/N2 production was 2, 7, 9, and 86% in fallow, legume-grass mixture, rye, and legume cover cropped soil. The N2O/N2 ratio tended to increase with lower DOC (post-rain) levels in the soil. The results suggest that accumulated carbon in dry surface soil is the main driving factor of N2O and N2 emissions through denitrification with the first rainfall after prolonged dry periods.
[(Nitrato-κO,O')(nitrito-κO,O')(0.25/1.75)]bis-(1,10-phenanthroline-κN,N')cadmium(II).

Science.gov (United States)

Najafi, Ezzatollah; Amini, Mostafa M; Ng, Seik Weng

2011-01-22

The reaction of cadmium nitrate and sodium nitrite in the presence of 1,10-phenanthroline yields the mixed nitrate-nitrite title complex, [Cd(NO(2))(1.75)(NO(3))(0.25)(C(12)H(8)N(2))(2)]. The metal ion is bis-chelated by two N-heterocycles as well as by the nitrate/nitrite ions in a distorted dodeca-hedral CdN(4)O(4) coordination environment. One nitrite group is ordered; the other is disordered with respect to a nitrate group (ratio 0.75:0.25) concerning the O atom that is not involved in bonding to the metal ion.
Synthesis and properties of Ag/ZnO/g-C3N4 ternary micro/nano composites by microwave-assisted method

Science.gov (United States)

Zhang, Zijie; Li, Xuexue; Chen, Haitao; Shao, Gang; Zhang, Rui; Lu, Hongxia

2018-01-01

Ag/ZnO/g-C3N4 ternary micro/nanocomposites, as novel visible-light-driven photocatalysts, were prepared by a simple and convenient microwave-assisted method. The resulting ternary structure micro/nano composites were characterized by x-ray diffraction, x-ray photoelectron spectroscopy, scanning electron microscopy, ultraviolet-visible diffuse reflectance spectroscopy and infrared radiation techniques to examine its phase structure, valence state, morphological, thermal and optical properties. Well crystallized Ag/ZnO/g-C3N4 ternary micro/nano composites were synthesized under microwave-radiation for 15 min with the output of 240 W. Further experiments indicated Ag(5.0mol%)/ZnO/g-C3N4 photocatalyst in degradation of methylene blue exhibited an outstanding photocatalytic activity and its reaction rate constant (k, 0.0084 min-1) is 7.5, 2.4 2.9 and 3.5 times higher than that of monolithic ZnO (k, 0.0011 min-1), ZnO/g-C3N4(k, 0.0035 min-1), Ag(5 mol%)/ZnO(k, 0.0029 min-1) and Ag(5mol%)/g-C3N4 (k, 0.0024 min-1) respectively. Finally, a possible photocatalytic mechanism of Ag/ZnO/g-C3N4 photocatalyst in degradation process was proposed. This work provides a feasible strategy to synthesize an efficient ZnO-based photocatalyst which combines structure and properties of different dimensional components and made this ternary system an exciting candidate for sunlight-driven photocatalytic water treatment.
Study of epitaxial lateral overgrowth of semipolar (1 1 − 2 2) GaN by using different SiO2 pattern sizes

International Nuclear Information System (INIS)

Song, Ki-Ryong; Lee, Jae-Hwan; Han, Sang-Hyun; Yi, Hye-Rin; Lee, Sung-Nam

2013-01-01

Graphical abstract: - Highlights: • We examine comparative studies of semipolar ELO-GaN film. • Semipolar ELO-GaN film was grown by three step growth method. • The achievement of smooth surface morphology of semipolar ELO-GaN. • The crystal and optical properties was significantly improved by ELO process. - Abstract: We investigated the growth mode and the crystal properties of lateral epitaxial overgrowth (LEO) semipolar (1 1 − 2 2) GaN by using the various SiO 2 pattern sizes of 6, 8, 10 and 12 μm with the window width of 4.0 μm. By using three-step growth technique, we successfully obtained the fully-coalescenced semipolar (1 1 − 2 2) LEO-GaN films regardless of the SiO 2 pattern sizes. However, the coalescence thickness of LEO-GaN film was decreased with decreasing SiO 2 pattern size, indicating that the coalescence of semipolar (1 1 − 2 2) GaN was easily formed by decreasing the pattern size of SiO 2 mask. The full width at half maximums (FWHMs) of X-ray rocking curves (XRCs) of LEO-GaN films decreased with increasing SiO 2 pattern size. In the pattern size of 4 × 10 μm, we achieved the minimum XRCs FWHM of 537 and 368 arc s with two different X-ray incident beam directions of [1 1 − 2 − 3] and [1 − 1 0 0], respectively. Moreover, the photoluminescence bandedge emission of semipolar (1 1 − 2 2) GaN was 45 times increased by LEO process. Based on these results, we concluded that the LEO pattern size of 4 × 10 μm would effectively decrease crystal defects of semipolar (1 1 − 2 2) GaN epilayer, resulting in an improvement of the optical properties
Kinetic study of Ca({sup 1}S) + N{sub 2}O and Sr({sup 1}S) + N{sub 2}O reactions in the temperature ranges of, respectively, 303--1015 and 303--999 K

Energy Technology Data Exchange (ETDEWEB)

Vinckier, C.; Helaers, J.; Remeysen, J. [K.U. Leuven, Heverlee (Belgium). Dept. of Chemistry

1999-07-08

Metal/N{sub 2}O reactions in incinerators may reduce the emission of the greenhouse gas N{sub 2}O. The study of metal atom/N{sub 2}O reactions allows metal atom/N{sub 2}O reactions in the gas phase to be very exothermic, leading to product molecules being formed in an electronic excited state. When the metal oxides fall back to lower lying states, an intense chemiluminescence can occur. In this way such reactions can be suitable candidates for the development of chemical lasers in which the population inversion is obtained by means of a pure chemical reaction. A kinetic study of the second-order reactions Ca({sup 1}S) + N{sub 2}O(X{sup 1}{Sigma}{sup +}) {yields} CaO + N{sub 2} and Sr({sup 1}S) + N{sub 2}O(X{sup 1}{Sigma}{sup +}) {yields} SrO + N{sub 2} has been carried out in a fast-flow reactor in the temperature ranges of, respectively, 303--1015 and 303--999 K. The alkaline earth metal atoms were thermally generated from the solid metal pellets. Their decays as a function of the added N{sub 2}O concentration were followed by means of atomic absorption spectroscopy (AAS) at 422.7 nm for calcium and 460.7 nm for strontium atoms. Both reactions showed a non-Arrhenius behavior that can best be explained by the presence of two reaction product channels, resulting in a rate constant expressed as the sum of two exponential functions. The best fits over the entire temperature range are given by polynomial expressions. The results will be discussed in view of the literature data on the alkaline earth metal atom + N{sub 2}O reactions. The experimentally derived energy barriers will be compared with the calculated values on the basis of the semiempirical configuration interaction theory (SECI). Reasonably good correlations were obtained between the barrier heights of the reaction and the promotion energy of the metals involved.
Growth of epitaxial (Sr, Ba){sub n+1}Ru{sub n}O{sub 3n}P+{sub 1}films

Energy Technology Data Exchange (ETDEWEB)

Schlom, D.G.; Knapp, S.B.; Wozniak, S. [Department of Materials Science and Engineering, Penn State University, University Park, PA (United States); Zou, L.N.; Park, J.; Liu, Y. [Department of Physics, Penn State University, University Park, PA (United States); Hawley, M.E.; Brown, G.W. [Center for Materials Science, Los Alamos National Laboratory, Los Alamos, NM (United States); Dabkowski, A.; Dabkowska, H.A. [Institute of Materials Research, McMaster University, Hamilton, Ontario (Canada); Uecker, R.; Reiche, P. [Institute of Crystal Growth, Berlin (Germany)

1997-12-01

We have grown epitaxial (Sr,Ba){sub n+1}Ru{sub n}O{sub 3n+1} films, n = 1, 2 and {infinity}, by pulsed laser deposition (PLD) and controlled their orientation by choosing appropriate substrates. The growth conditions yielding phase-pure films have been mapped out. Resistivity versus temperature measurements show that both a-axis and c-axis films of Sr{sub 2}RuO{sub 4} are metallic, but not superconducting. The latter is probably due to the presence of low-level impurities that are difficult to avoid given the target preparation process involved in growing these films by PLD. (author)
Enhancement of acid treated g-C3N4sbnd Cu2O photocatalytic activity by PEG under visible light irradiation

Science.gov (United States)

Zuo, Shiyu; Xu, Haiming; Liao, Wei; Sun, Lei; Li, Qiang; Zan, Jie; Zhang, Binyang; Li, Dongya; Xia, Dongsheng

2018-05-01

In this study, g-C3N4sbnd Cu2O was successfully synthesized in the presence of PEG-400 surfactant via an acid treatment hydrothermal method and a high-temperature calcination method. The structures and properties of as-synthesized samples were characterized using a range of techniques, such as XPS, TEM, PL and BET. The g-C3N4sbnd Cu2O heterojunction exhibits the enhanced photocatalytic performance and high stability. It is revealed that the addition of PEG can promote the heterojunction effect of g-C3N4sbnd Cu2O, effectively improving the crystallinity and specific surface area of the photocatalyst, separation efficiency of photocarriers, and light absorption, thus enhancing the photocatalytic performance.
UV-light-assisted ethanol sensing characteristics of g-C3N4/ZnO composites at room temperature

Science.gov (United States)

Zhai, Jiali; Wang, Tao; Wang, Chuang; Liu, Dechen

2018-05-01

A highly efficient UV-light-assisted room temperature sensor based on g-C3N4/ZnO composites were prepared by an in situ precipitation method. The thermostability, composition, structure, and morphology properties of the as-prepared g-C3N4/ZnO composites were characterized by TGA, XRD, FT-IR, TEM, and XPS, respectively. And then, we studied the ethanol (C2H5OH) sensing performance of the g-C3N4/ZnO composites at the room temperature. Compared with pure ZnO and g-C3N4, the gas sensing activity of g-C3N4/ZnO composites was greatly improved at room temperature, for example, the g-C3N4/ZnO-8% composites showed an obvious response of 121-40 ppm C2H5OH at room temperature, which was 60 times higher than the pure ZnO based on the sensors under the same condition. The great enhancement of the C2H5OH sensing properties of composites can be understood by the efficient separation of photogenerated charge carriers of g-C3N4/ZnO heterogeneous and the UV-light catalytic effect. Finally, a possible mechanism for the gas sensing activity was proposed.
Highly enhanced photocatalytic degradation of methylene blue over the indirect all-solid-state Z-scheme g-C{sub 3}N{sub 4}-RGO-TiO{sub 2} nanoheterojunctions

Energy Technology Data Exchange (ETDEWEB)

Wu, Fangjun [College of Materials and Energy, South China Agricultural University, Guangzhou 510642 (China); Li, Xin [College of Materials and Energy, South China Agricultural University, Guangzhou 510642 (China); Institute of New Energy and New Materials, Key Laboratory of Energy Plants Resource and Utilization, Ministry of Agriculture, South China Agricultural University, Guangzhou 510642 (China); College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou 510642 (China); Liu, Wei, E-mail: wlscau@163.com [College of Materials and Energy, South China Agricultural University, Guangzhou 510642 (China); Zhang, Shuting [College of Materials and Energy, South China Agricultural University, Guangzhou 510642 (China)

2017-05-31

Highlights: • The indirect Z-scheme g-C{sub 3}N{sub 4}-RGO-TiO{sub 2} photocatalysts were successfully fabricated. • A 3.2-fold activity enhancement was achieved by inserting RGO into g-C{sub 3}N{sub 4}- TiO{sub 2}. • The indirect Z-scheme mechanism was verified by PL spectra and radical trapping. • The multi-functional roles of RGO in enhancing photodegradation were revealed. - Abstract: In the present research work, the ternary indirect all-solid-state Z-scheme nanoheterojunctions, graphitic-C{sub 3}N{sub 4}/reduced graphene oxide/anatase TiO{sub 2} (g-C{sub 3}N{sub 4}-RGO-TiO{sub 2}) with highly enhanced photocatalytic performance were successfully prepared via a simple liquid-precipitation strategy. The photocatalytic activities of indirect all-solid-state Z-scheme g-C{sub 3}N{sub 4}-RGO-TiO{sub 2} nanoheterojunctions were evaluated by the degradation of methylene blue (MB). The results showed that the introduction of RGO as an interfacial mediator into direct Z-scheme g-C{sub 3}N{sub 4}-TiO{sub 2} nanocomposites can remarkably enhance their photocatalytic activities. The as-obtained indirect all-solid-state Z-scheme g-C{sub 3}N{sub 4}-RGO-TiO{sub 2} nanoheterojunctions, with the optimal loading amount of 10 wt% RGO, exhibited the highest rate towards the photocatalytic degradation of MB under simulated solar light irradiation. The degradation kinetics of MB can be described by the apparent first-order kinetics model. The highest degradation rate constant of 0.0137 min{sup −1} is about 4.7 and 3.2 times greater than those of the pure g-C{sub 3}N{sub 4} (0.0029 min{sup −1}) and direct Z-scheme g-C{sub 3}N{sub 4}-TiO{sub 2} (0.0043 min{sup −1}), respectively. An indirect all-solid-state Z-scheme charge-separation mechanism was proposed based on the photoluminescence spectra and the trapping experiment procedure of the photo-generated active species. It was believed that the indirect all-solid-state Z-scheme charge separation mechanism in g-C{sub 3}N
Aquachlorido{6,6′-dimethoxy-2,2′-[ethane-1,2-diylbis(nitrilodimethylidyne]diphenolato-κ2O1,N,N′,O1′}cobalt(III monohydrate

Directory of Open Access Journals (Sweden)

Jianxin Xing

2009-04-01

Full Text Available The title compound, [Co(C18H18N2O4Cl(H2O]·H2O, contains a distorted octahedral cobalt(III complex with a 6,6′-dimethoxy-2,2′-[ethane-1,2-diylbis(nitrilodimethylidyne]diphenolate ligand, a chloride and an aqua ligand, and also a disordered water solvent molecule (half-occupancy. The CoIII ion is coordinated in an N2O3Cl manner. Weak O—H...O hydrogen bonds may help to stabilize the crystal packing.
Compaction stimulates denitrification in an urban park soil using 15N tracing technique

DEFF Research Database (Denmark)

Li, Shun; Deng, Huan; Rensing, Christopher Günther T

2014-01-01

Soils in urban areas are subjected to compaction with accelerating urbanization. The effects of anthropogenic compaction on urban soil denitrification are largely unknown. We conducted a study on an urban park soil to investigate how compaction impacts denitrification. By using 15N labeling method...... and acetylene inhibition technique, we performed three coherent incubation experiments to quantify denitrification in compacted soil under both aerobic and anaerobic conditions. Uncompacted soil was set as the control treatment. When monitoring soil incubation without extra substrate, higher nitrous oxide (N2O......) flux and denitrification enzyme activity were observed in the compacted soil than in the uncompacted soil. In aerobic incubation with the addition of K15NO3, N2O production in the compacted soil reached 10.11 ng N h-1 g-1 as compared to 0.02 ng N h-1 g-1 in the uncompacted soil. Denitrification...
Continuous Eddy Covariance Measurements of N2O Emissions and Controls from an Intensively Grazed Dairy Farm

Science.gov (United States)

Schipper, L. A.; Liang, L. L.; Wall, A.; Campbell, D.

2017-12-01

New Zealand's greenhouse gas (GHG) inventory is disproportionally dominated by methane and nitrous oxide which account for 54% of emissions. These GHGs are derived from pastoral agriculture that supports dairying and meat production. To date, most studies on quantifying or mitigating agricultural N2O emissions have used flux chamber measurements. Recent advances in detector technology now means that routine field-to-farm scale measurements of N2O emissions might be possible using the eddy covariance technique. In late 2016, we established an eddy covariance tower that measured N2O emissions from a dairy farm under year-round grazing. An Aerodyne quantum cascade laser (QCL) was used to measure N2O, CH4 and H2O concentration at 10 Hz and housed in a weatherproof and insulated enclosure (0.9 m ´ 1.2 m) and powered by mains power (240 VAC). The enclosure maintained a stable setpoint temperature (30±0.2°C) by using underground cooling pipes, fans and recirculating instrument heat. QCL (true 10 Hz digital) and CSAT3B sonic anemometer high frequency data are aligned using Network Time Protocol and EddyPro covariance maximisation during flux processing. Fluxes generally integrated over about 6-8 ha. Stable summertime baseline N2O fluxes (FN2O) were around 12-24 g N2O-N ha-1 d-1 (0.5-1.0 nmol N2O m-2 s-1). Grazing by cows during dry summer resulted in only modest increases in FN2O to 24-48 g N2O-N ha-1 d-1 (1.0-2.0 nmol N2O m-2 s-1). However, the first rain events after grazing resulted in large, short-lived (1-3 days) FN2O pulses reaching peaks of 144-192 g N2O-N ha-1 d-1 (6-8 nmol N2O m-2 s-1). During these elevated N2O emissions, FN2O displayed a significant diurnal signal, with peak fluxes mid-afternoon which was best explained by variation in shallow soil temperature in summer. In winter (both cooler and wetter) FN2O were not as easily explained on a daily basis but were generally greater than summer. Throughout the year, FN2O was strongly dependent on water filled
In situ hydrothermal synthesis of g-C{sub 3}N{sub 4}/TiO{sub 2} heterojunction photocatalysts with high specific surface area for Rhodamine B degradation

Energy Technology Data Exchange (ETDEWEB)

Hao, Ruirui [Hubei Key Laboratory of Pollutant Analysis and Reuse Technology, Institute for Advanced Materials, College of Chemistry and Chemical Engineering, Hubei Normal University, Huangshi 435002 (China); Wang, Guohong, E-mail: wanggh2003@163.com [Hubei Key Laboratory of Pollutant Analysis and Reuse Technology, Institute for Advanced Materials, College of Chemistry and Chemical Engineering, Hubei Normal University, Huangshi 435002 (China); Jiang, Chuanjia [State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Luoshi Road 122, Wuhan, 430070 (China); Tang, Hua [School of Materials Science and Engineering, Jiangsu University, Zhenjiang, 212013 (China); Xu, Qingchuan [Hubei Key Laboratory of Pollutant Analysis and Reuse Technology, Institute for Advanced Materials, College of Chemistry and Chemical Engineering, Hubei Normal University, Huangshi 435002 (China)

2017-07-31

Highlights: • High surface area g-C{sub 3}N4/TiO{sub 2} is obtained by combined hydrothermal-calcination method. • HCl formation from Ti precursor changed the structural properties of the composite. • Composite exhibited visible light photocatalytic performance for RhB degradation. • A 3 g of melamine for 0.5 mL TiCl{sub 4} was found to be the optimum content. - Abstract: Semiconductor-based photocatalysis is a promising method for degradation of environmental pollutants, but the activity of most widely used photocatalysts such as titania (TiO{sub 2}) is still unsatisfactory under visible light. Herein, we synthesized a highly efficient visible-light-responsive heterojunction catalysts based on graphitic carbon nitride (g-C{sub 3}N{sub 4}) and TiO{sub 2}. The g-C{sub 3}N{sub 4}/TiO{sub 2} heterojunction composites with high specific surface area were prepared via in situ hydrothermal synthesis followed by calcination, using titanium tetrachloride (TiCl{sub 4}) and melamine as precursors. Interesting, HCl from the hydrolysis of TiCl{sub 4} served as the proton source to acidify the melamine. The g-C{sub 3}N{sub 4}/TiO{sub 2} heterojunction composites exhibited higher photocatalytic performance for decomposition of Rhodamine B (RhB) than pure g-C{sub 3}N{sub 4} or TiO{sub 2} under visible light irradiation. The high activity can be ascribed to the high specific surface area (up to 115.6 m{sup 2} g{sup −1}) of the g-C{sub 3}N{sub 4}/TiO{sub 2} composites and a synergistic heterojunction structure between TiO{sub 2} and g-C{sub 3}N{sub 4}. Moreover, the photocatalytic performances of the g-C{sub 3}N{sub 4}/TiO{sub 2} composites rely on the content of melamine in the synthesis precursors: with an optimum melamine content (3 g for 0.5 mL of TiCl{sub 4}), the sample showed the highest photocatalytic performance, which is superior to pure TiO{sub 2} and g-C{sub 3}N{sub 4} by a factor of 18.7 and 3.5, respectively. Active species trapping experiments revealed that
Thin-barrier enhancement-mode AlGaN/GaN MIS-HEMT using ALD Al2O3 as gate insulator

International Nuclear Information System (INIS)

Wang Zheli; Zhou Jianjun; Kong Yuechan; Kong Cen; Dong Xun; Yang Yang; Chen Tangsheng

2015-01-01

A high-performance enhancement-mode (E-mode) gallium nitride (GaN)-based metal–insulator–semiconductor high electron mobility transistor (MIS-HEMT) that employs a 5-nm-thick aluminum gallium nitride (Al 0.3 Ga 0.7 N) as a barrier layer and relies on silicon nitride (SiN) passivation to control the 2DEG density is presented. Unlike the SiN passivation, aluminum oxide (Al 2 O 3 ) by atomic layer deposition (ALD) on AlGaN surface would not increase the 2DEG density in the heterointerface. ALD Al 2 O 3 was used as gate insulator after the depletion by etching of the SiN in the gate region. The E-mode MIS-HEMT with gate length (L G ) of 1 μm showed a maximum drain current density (I DS ) of 657 mA/mm, a maximum extrinsic transconductance (g m ) of 187 mS/mm and a threshold voltage (V th ) of 1 V. Comparing with the corresponding E-mode HEMT, the device performances had been greatly improved due to the insertion of Al 2 O 3 gate insulator. This provided an excellent way to realize E-mode AlGaN/GaN MIS-HEMTs with both high V th and I DS . (paper)
Difluorophosphoryl nitrene F2P(O)N: matrix isolation and unexpected rearrangement to F2PNO.

Science.gov (United States)

Zeng, Xiaoqing; Beckers, Helmut; Willner, Helge; Neuhaus, Patrik; Grote, Dirk; Sander, Wolfram

2009-12-14

Triplet difluorophosphoryl nitrene F(2)P(O)N (X(3)A'') was generated on ArF excimer laser irradiation (lambda=193 nm) of F(2)P(O)N(3) in solid argon matrix at 16 K, and characterized by its matrix IR, UV/Vis, and EPR spectra, in combination with DFT and CBS-QB3 calculations. On visible light irradiation (lambda>420 nm) at 16 K F(2)P(O)N reacts with molecular nitrogen and some of the azide is regenerated. UV irradiation (lambda=255 nm) of F(2)P(O)N (X(3)A'') induced a Curtius-type rearrangement, but instead of a 1,3-fluorine shift, nitrogen migration to give F(2)PON is proposed to be the first step of the photoisomerization of F(2)P(O)N into F(2)PNO (difluoronitrosophosphine). Formation of novel F(2)PNO was confirmed with (15)N- and (18)O-enriched isotopomers by IR spectroscopy and DFT calculations. Theoretical calculations predict a rather long P-N bond of 1.922 A [B3LYP/6-311+G(3df)] and low bond-dissociation energy of 76.3 kJ mol(-1) (CBS-QB3) for F(2)PNO.
Construction of g-C{sub 3}N{sub 4}/Al{sub 2}O{sub 3} hybrids via in-situ acidification and exfoliation with enhanced photocatalytic activity

Energy Technology Data Exchange (ETDEWEB)

Wang, Xiao-jing [College of Science, Hebei University of Science and Technology, Shijiazhuang 050018 (China); State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry, Jilin University, Changchun 130012 (China); Liu, Chao [College of Gemmology and Material Technics, Hebei GEO University, Shijiazhuang 050031 (China); Li, Xu-li [College of Science, Hebei University of Science and Technology, Shijiazhuang 050018 (China); Li, Fa-tang, E-mail: lifatang@126.com [College of Science, Hebei University of Science and Technology, Shijiazhuang 050018 (China); Li, Yu-pei [College of Science, Hebei University of Science and Technology, Shijiazhuang 050018 (China); Zhao, Jun [College of Science, Hebei University of Science and Technology, Shijiazhuang 050018 (China); State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry, Jilin University, Changchun 130012 (China); Liu, Rui-hong [College of Science, Hebei University of Science and Technology, Shijiazhuang 050018 (China)

2017-02-01

Highlights: • Ultrathin g-C{sub 3}N{sub 4}/Al{sub 2}O{sub 3} hybrids are prepared via in-situ reaction. • The structure modification role of in-situ formed HNO{sub 3} for g-C{sub 3}N{sub 4} is found. • The ultrathin g-C{sub 3}N{sub 4} nanosheets are formed by the acidified melamine and Al(OH){sub 3}. • In-situ calcination of melamine and Al(OH){sub 3} benefits the contact of C{sub 3}N{sub 4} and Al{sub 2}O{sub 3}. • The activity of g-C{sub 3}N{sub 4}/Al{sub 2}O{sub 3} is 16.6 times that of pristine g-C{sub 3}N{sub 4} in degrading RhB. - Abstract: Homogeneous ultrathin g-C{sub 3}N{sub 4} nanosheets/Al{sub 2}O{sub 3} heterojunctions are synthesized using melamine and Al(NO{sub 3}){sub 3} via in-situ reaction and the following thermal polymerization approach. The in-situ reaction between melamine and Al(NO{sub 3}){sub 3} results in the existence of HNO{sub 3}-acidified melamine and Al(OH){sub 3} aggregates via the hydrolysis of Al(NO{sub 3}){sub 3}. After thermal polymerization, the aggregates are converted to g-C{sub 3}N{sub 4}/Al{sub 2}O{sub 3} composites. The thermal polymerization of acidified melamine and the support effect of aluminum hydroxide for g-C{sub 3}N{sub 4} during the calcination process lead to highly dispersed amrophous Al{sub 2}O{sub 3} on ultrathin g-C{sub 3}N{sub 4} nanosheets, which is beneficial for the separation of photogenerated electron-hole pairs in the heterojunction. The degradation rate for Rhodamine B (RhB) over the most activie sample is 16.6 times than that of pristine g-C{sub 3}N{sub 4} under visible light irradiation, which can be attributed to the high specific surface area, highly dispersion of amorphous Al{sub 2}O{sub 3} on ultrathin g-C{sub 3}N{sub 4} nanosheet, and the effective electrons transfer from g-C{sub 3}N{sub 4} to the amorphous Al{sub 2}O{sub 3}.
Factors controlling regional differences in forest soil emission of nitrogen oxides (NO and N2O

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K. Pilegaard

2006-01-01

Full Text Available Soil emissions of NO and N2O were measured continuously at high frequency for more than one year at 15 European forest sites as part of the EU-funded project NOFRETETE. The locations represent different forest types (coniferous/deciduous and different nitrogen loads. Geographically they range from Finland in the north to Italy in the south and from Hungary in the east to Scotland in the west. The highest NO emissions were observed from coniferous forests, whereas the lowest NO emissions were observed from deciduous forests. The NO emissions from coniferous forests were highly correlated with N-deposition. The site with the highest average annual emission (82 μg NO-N m−2 h−1 was a spruce forest in South-Germany (Höglwald receiving an annual N-deposition of 2.9 g m−2. NO emissions close to the detection limit were observed from a pine forest in Finland where the N-deposition was 0.2 g N m−2 a−1. No significant correlation between N2O emission and N-deposition was found. The highest average annual N2O emission (20 μg N2O-N m−2 h−1 was found in an oak forest in the Mátra mountains (Hungary receiving an annual N-deposition of 1.6 g m−2. N2O emission was significantly negatively correlated with the C/N ratio. The difference in N-oxide emissions from soils of coniferous and deciduous forests may partly be explained by differences in N-deposition rates and partly by differences in characteristics of the litter layer and soil. NO was mainly derived from nitrification whereas N2O was mainly derived from denitrification. In general, soil moisture is lower at coniferous sites (at least during spring time and the litter layer of coniferous forests is thick and well aerated favouring nitrification and thus release of NO. Conversely, the higher rates of denitrification in deciduous forests due to a compact and moist litter layer lead to N2O production and NO consumption in the soil. The two factors soil moisture and soil temperature are
Diferencias según género en la intención de emigración en médicos recién egresados

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Reneé Pereyra-Elías

2013-07-01

Full Text Available Introducción: La emigración médica en el Perú supone un importante problema en la búsqueda de la consolidación de un sistema de salud sostenible. Objetivos: Estimar la prevalencia de intención de emigración y sus factores asociados según género en médicos peruanos recién egresados. Diseño y lugar de estudio: Estudio analítico de corte transversal llevado a cabo en Lima, Perú, durante el año 2010. Participantes: Se incluyó a 289 médicos egresados de universidades de peruanas. Intervenciones: Se aplicó una encuesta anónima y autoadministrada que evaluaba la intención de emigración para laborar y sus factores asociados. Los datos fueron analizados con el paquete estadístico STATA 11.2; se utilizó un modelo lineal generalizado log-binomial como método de regresión de múltiples variables. Principales medidas de resultados: Intención de emigración autorreportada. Resultados: La prevalencia de intención de emigración fue de 42,1%; esta fue mayor en el género masculino (50,0% versus 36,4%; p<0,01. Un manejo intermedio/avanzado del idioma inglés (RP: 1,77; IC95%: 1,04 a 2,98 y expectativas de ingreso económico mayor o igual a 3 600 dólares americanos mensuales en los siguientes cinco años (RP: 1,55; IC95%: 1,09 a 2,21 se encontraron asociados con la intención de emigrar en varones. En mujeres, estuvieron asociados el haber culminado la carrera sin retraso (RP: 1,66; IC95%: 1,02 a 2,71 y proyectarse a ganar 3 600 dólares o más (RP: 1,71; IC95%: 1,14 a 2,57. Conclusiones: Existe una alta prevalencia de intención en emigración médica; el factor económico se asocia independientemente; los idiomas y la regularidad académica difieren según género.

Room-temperature in situ fabrication of Bi2O3/g-C3N4 direct Z-scheme photocatalyst with enhanced photocatalytic activity

Science.gov (United States)

He, Rongan; Zhou, Jiaqian; Fu, Huiqing; Zhang, Shiying; Jiang, Chuanjia

2018-02-01

Constructing direct Z-scheme heterojunction is an effective approach to separating photogenerated charge carriers and improving the activity of semiconductor photocatalysts. Herein, a composite of bismuth(III) oxide (Bi2O3) and graphitic carbon nitride (g-C3N4) was in situ fabricated at room temperature by photoreductive deposition of Bi3+ and subsequent air-oxidation of the resultant metallic Bi. Quantum-sized ω-Bi2O3 nanoparticles approximately 6 nm in diameter were uniformly distributed on the surface of mesoporous g-C3N4. The as-prepared Bi2O3/g-C3N4 composite exhibited higher photocatalytic activity than pure Bi2O3 and g-C3N4 for photocatalytic degradation of phenol under visible light. Reactive species trapping experiments revealed that superoxide radicals and photogenerated holes played important roles in the photocatalytic degradation of phenol. The enhanced photocatalytic activity, identification of reactive species and higher rate of charge carrier recombination (as indicated by stronger photoluminescence intensity) collectively suggest that the charge migration within the Bi2O3/g-C3N4 composite followed a Z-scheme mechanism. Photogenerated electrons on the conduction band of Bi2O3 migrate to the valence band of g-C3N4 and combine with photogenerated holes therein. At the cost of these less reactive charge carriers, the Z-scheme heterojunction enables efficient charge separation, while preserving the photogenerated electrons and holes with stronger redox abilities, which is beneficial for enhanced photocatalytic activity.
Energy level alignments at the interface of N,N'-bis-(1-naphthyl)-N,N'-diphenyl-1,1′-biphenyl-4,4′-diamine (NPB)/Ag-doped In{sub 2}O{sub 3} and NPB/Sn-doped In{sub 2}O{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Jung, Kwanwook; Park, Soohyung; Lee, Younjoo; Youn, Yungsik [Institute of Physics and Applied Physics, Yonsei University, 50 Yonsei-ro, Seodaemoon-gu, Seoul, 03722 (Korea, Republic of); Shin, Hae-In; Kim, Han-Ki [Department of Advanced Materials Engineering for Information and Electronics, Kyung Hee University, 1732 Deogyeong-daero, Giheung-gu, Yongin-si, Gyeonggi-do, 17104 (Korea, Republic of); Lee, Hyunbok, E-mail: hyunbok@kangwon.ac.kr [Department of Physics, Kangwon National University, 1 Gangwondaehak-gil, Chuncheon-si, Gangwon-do, 24341 (Korea, Republic of); Yi, Yeonjin, E-mail: yeonjin@yonsei.ac.kr [Institute of Physics and Applied Physics, Yonsei University, 50 Yonsei-ro, Seodaemoon-gu, Seoul, 03722 (Korea, Republic of)

2016-11-30

Highlights: • The electronic structures of IAgO and its energy level alignment with a NPB HTL were investigated using in situ UPS and XPS. • As compared to ITO, IAgO has less oxygen vacancies leading to a high work function. • The hole injection barrier at the NPB/IAgO interface (0.87 eV) is significantly lower than that at the NPB/ITO interface (1.11 eV). • IAgO could be an efficient anode material for high performance optoelectronic devices. - Abstract: The electronic structures of Ag-doped In{sub 2}O{sub 3} (IAgO) and its energy level alignments with a N,N'-bis-(1-naphthyl)-N,N'-diphenyl-1,1′-biphenyl-4,4′-diamine (NPB) hole transport layer (HTL) were investigated using in situ ultraviolet and X-ray photoelectron spectroscopies (UPS and XPS). As compared to the conventional Sn-doped In{sub 2}O{sub 3} (ITO), IAgO has less oxygen vacancies leading to a higher work function (WF). The lower hole injection barrier (Φ{sub h}) from IAgO to a NPB HTL is observed, which is attributed mainly to its higher WF and interface dipoles. The UPS measurements reveal that the Φ{sub h} is 0.87 eV at NPB/IAgO while 1.11 eV is at NPB/ITO. Therefore, IAgO could be an alternative transparent anode in organic optoelectronics.
N,N′-(Ethane-1,2-diyldi-o-phenylenebis(pyridine-2-carboxamide

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Shuranjan Sarkar

2011-11-01

Full Text Available The title molecule, C26H22N4O2, is centrosymmetric and adopts an anti conformation. Two intramolecular hydrogen bonds, viz. amide–pyridine N—H...N and phenyl–amide C—H...O, stabilize the trans conformation of the (pyridine-2-carboxamidophenyl group about the amide plane. In the crystal, the presence of weak intermolecular C—H...O hydrogen bonds results in the formation of a three-dimensional network.
A detailed study of the dehydration process in synthetic strelkinite, Na[(UO2)(VO4)] . nH2O (n = 0, 1, 2)

International Nuclear Information System (INIS)

Suleimanov, Evgeny V.; Somov, Nikolay V.; Chuprunov, Evgeny V.; Mayatskikh, Ekaterina F.; Depmeier, Wulf

2012-01-01

Synthetic strelkinite Na[(UO 2 )(VO 4 )] . nH 2 O (n = 0, 1, 2) was systematically investigated by single crystal X-ray diffraction and thermoanalytical methods. The anhydrous form and two hydrates were isolated as single crystals and the structures of these phases solved: Na[(UO 2 )(VO 4 )], monoclinic, P2 1 /c, a = 6.0205(1) Aa, b = 8.3365(1) Aa, c = 10.4164(2) Aa, β = 100.466(2) , V = 514.10(1) Aa 3 , R 1 = 0.0337; Na[(UO 2 )(VO 4 )] . H 2 O, monoclinic, P2 1 /c, a = 7.722(2) Aa, b = 8.512(1) Aa, c = 10.480(4) Aa, β = 113.18(3) , V = 633.3(3) Aa 3 , R 1 = 0.1658; Na[(UO 2 )(VO 4 )] . 2 H 2 O, monoclinic, P2 1 /n, a = 16.2399(5) Aa, b = 8.2844(2) Aa, c = 10.5011(2) Aa, β = 97.644(2) , V = 1400.24(6) Aa 3 , R 1 = 0.0776. A possible mechanism of the structural transformation processes during dehydration is proposed based on the structures of the anhydrous phase and the hydrates. (orig.)
Tetrakis(6-methyl-2,2′-bipyridine-1κ2N,N′;2κ2N,N′;3κ2N,N′;4κ2N,N′-tetra-μ-nitrato-1:2κ2O:O′;2:3κ3O:O′,O′′;2:3κ3O,O′:O′′;3:4κ2O:O′-tetranitrato-1κ4O,O′;4κ2O,O′-tetralead(II

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Roya Ahmadi

2009-10-01

Full Text Available In the tetranuclear centrosymmetric title compound, [Pb4(NO38(C11H10N24], irregular PbN2O5 and PbN2O4 coordination polyhedra occur. The heptacoordinated lead(II ion is bonded to two bidentate and one monodentate nitrate ion and one bidentate 6-methyl-2,2′-bipyridine (mbpy ligand. The six-coordinate lead(II ion is bonded to one bidentate and two monodentate nitrate anions and one mbpy ligand. In the crystal, bridging nitrate anions lead to infinite chains propagating in [111]. A number of C—H...O hydrogen bonds may stabilize the structure.
Dissolution and Release of Gaseous Nitrogen (N2, N2O) in the Source Region of the Yellow River

Science.gov (United States)

Zhang, L.; Xia, X.; Wang, J.

2017-12-01

Nitrogen is an important biogenic element. The migration and transformation of nitrogen in rivers is an important process affecting global nitrogen cycling and greenhouse gas emissions. However, there is a lack of research on nitrogen removal and greenhouse gas emission characteristics of high altitude rivers. In this work, the spatial and temporal variations of dissolved nitrogen (N2 and N2O) concentrations, saturation, and release flux as well as their responses to environmental factors were studied in the Yellow River source area, a typical high altitude river. The results showed that the dissolved concentrations of N2 and N2O in the rivers were 8.24-137.75 μmol.L-1 and 2.57-31.94 nmol.L-1, respectively. N2 and N2O saturation were greater than 100% for all the sampling sites, indicating that the river is a release source for atmosphere N2 and N2O. Correspondingly, the fluxes of N2 and N2O from river water to atmosphere were 24.12-1606.57 mmol (m2.d) -1 and 12.96-276.81 μmol (m2.d) -1, respectively. Generally, the dissolution concentration and release flux of N2 and N2O in July were larger than that in May. The concentrations of N2 and N2O in river water were related to the environmental factors, and the dissolved concentration of N2 in the surface water was significantly positively correlated with water temperature, NH4+-N and total inorganic nitrogen (DIN) (p<0.01). The dissolved concentration of N2O was significantly positively correlated with the content of suspended particulates, DO, and DIN (p<0.01). Thus, DIN is a key factor in the process of N2 and N2O formation. This study can help to understand the nitrogen cycling in high-altitude rivers and provide basic data for a comprehensive assessment of global river nitrogen loss. Key Words: Source Region of the Yellow River; Gaseous Nitrogen; Nitrogen loss; High altitude river
Nitrous oxide (N(2)O) reduces postoperative opioid-induced hyperalgesia after remifentanil-propofol anaesthesia in humans.

Science.gov (United States)

Echevarría, G; Elgueta, F; Fierro, C; Bugedo, D; Faba, G; Iñiguez-Cuadra, R; Muñoz, H R; Cortínez, L I

2011-12-01

The aim of this study was to test if intraoperative administration of N(2)O during propofol-remifentanil anaesthesia prevented the onset of postoperative opioid-induced hyperalgesia (OIH). Fifty adult ASA I-II patients undergoing elective open septorhinoplasty under general anaesthesia were studied. Anaesthesia was with propofol, adjusted to bispectral index (40-50), and remifentanil (0.30 μg kg(-1) min(-1)). Patients were assigned to one of the two groups: with N(2)O (70%) and without N(2)O (100% oxygen). Mechanical pain thresholds were measured before surgery and 2 and 12-18 h after surgery. Pain measurements were performed on the arm using hand-held von Frey filaments. A non-parametric analysis of variance was used in the von Frey data analysis. P<0.05 was considered statistically significant. Baseline pain thresholds to mechanical stimuli were similar in both groups, with mean values of 69 [95% confidence interval (CI): 50.2, 95.1] g in the group without N(2)O and 71 (95% CI: 45.7, 112.1) g in the group with N(2)O. Postoperative pain scores and cumulative morphine consumption were similar between the groups. The analysis revealed a decrease in the threshold value in both groups. However, post hoc comparisons showed that at 12-18 h after surgery, the decrease in mechanical threshold was greater in the group without N(2)O than the group with N(2)O (post hoc analysis with Bonferroni's correction, P<0.05). Intraoperative 70% N(2)O administration significantly reduced postoperative OIH in patients receiving propofol-remifentanil anaesthesia.
Estimating N2O processes during grassland renewal and grassland conversion to maize cropping using N2O isotopocules

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Buchen, Caroline; Well, Reinhard; Flessa, Heinz; Fuß, Roland; Helfrich, Mirjam; Lewicka-Szczebak, Dominika

2017-04-01

Grassland break-up due to grassland renewal and grassland conversion to cropland can lead to a flush of mineral nitrogen from decomposition of the old grass sward and the decomposition of soil organic matter. Moreover, increased carbon and nitrogen mineralisation can result in enhanced nitrous oxide (N2O) emissions. As N2O is known to be an important greenhouse gas and a major precursor for ozone depletion, its emissions need to be mitigated by adjusting agricultural management practices. Therefore, it is necessary to understand the N2O processes involved, as well as the contribution of N2O reduction to N2. Apart from the widely used 15N gas flux method, natural abundance isotopic analysis of the four most abundant isotopocules of N2O species is a promising alternative to assess N2O production pathways. We used stable isotope analyses of soil-emitted N2O (δ18ON2O, δ15NN2Obulk and δ15NN2OSP= intramolecular distribution of 15N within the linear N2O molecule) with an isotopocule mapping approach to simultaneously estimate the magnitude of N2O reduction to N2 and the fraction of N2O originating from the bacterial denitrification pathway or fungal denitrification and/or nitrification. This approach is based on endmember areas of isotopic values for the N2O produced from different sources reported in the literature. For this purpose, we calculated two main scenarios with different assumptions for N2O produced: N2O is reduced to N2 before residual N2O is mixed with N2O of various sources (Scenario a) and vice versa (Scenario b). Based on this, we applied seven different scenario variations, where we evaluated the range of possible values for the potential N2O production pathways (heterotrophic bacterial denitrification and/or nitrifier denitrification and fungal denitrification and/or nitrification). This was done by using a range of isotopic endmember values and assuming different fractionation factors of N2O reduction in order to find the most reliable scenario
Improved photoelectrochemical performance of Z-scheme g-C{sub 3}N{sub 4}/Bi{sub 2}O{sub 3}/BiPO{sub 4} heterostructure and degradation property

Energy Technology Data Exchange (ETDEWEB)

Li, Junqi, E-mail: sfmlab@163.com; Yuan, Huan; Zhu, Zhenfeng

2016-11-01

Highlights: • A novel Z-scheme g-C{sub 3}N{sub 4}/Bi{sub 2}O{sub 3}/BiPO{sub 4} composite was synthesized. • The Z-scheme system we made can remain the strong reducibility and oxidizability of the photocatalysts. • The solar light was made the utmost use both the ultraviolet and visible region light through the g-C{sub 3}N{sub 4}/Bi{sub 2}O{sub 3}/BiPO{sub 4} composite. - Abstract: In g-C{sub 3}N{sub 4}/Bi{sub 2}O{sub 3}/BiPO{sub 4}, the p–n junction between p-type Bi{sub 2}O{sub 3} and n-type BiPO{sub 4} was encapsulated by g-C{sub 3}N{sub 4} and a direct Z-scheme was built between g-C{sub 3}N{sub 4} and Bi{sub 2}O{sub 3}. The optical, morphological and photoelectrochemical (PEC) properties of BiPO{sub 4}, g-C{sub 3}N{sub 4}/BiPO{sub 4}, Bi{sub 2}O{sub 3}/BiPO{sub 4} and g-C{sub 3}N{sub 4}/Bi{sub 2}O{sub 3}/BiPO{sub 4} hierarchical Z-scheme system were studied. More than 90% photodegradation of methyl orange (MO) with the exposure of simulated solar light was achieved within 160 min with the g-C{sub 3}N{sub 4}/Bi{sub 2}O{sub 3}/BiPO{sub 4}, which displayed remarkably promoted photocatalytic activities than other samples. The electrochemical impedance spectra and photocurrent results also proved that efficient charge separation and better electron transport properties were achieved by g-C{sub 3}N{sub 4}/Bi{sub 2}O{sub 3}/BiPO{sub 4}. In general, the addition of g-C{sub 3}N{sub 4} can guide the residual electrons on p-type Bi{sub 2}O{sub 3} to recombine with photoholes of g-C{sub 3}N{sub 4} and make sure the left carries exhibit stronger oxidation and reduction ability to boost the production of active groups.
Fabrication of novel ternary Au/CeO2@g-C3N4 nanocomposite: kinetics and mechanism investigation of 4-nitrophenol reduction, and benzyl alcohol oxidation

Science.gov (United States)

Kohantorabi, Mona; Gholami, Mohammad Reza

2018-06-01

Au nanoparticles supported on cerium oxide/graphitic carbon nitride (CeO2@g-C3N4) was synthesized and used as heterogeneous catalyst in redox reaction. The catalyst was characterized by different techniques such as FT-IR, XRD, FE-SEM, EDS, TEM, BET, TGA, and ICP. The as-prepared ternary nanocomposite was used as an effective catalyst for the reduction of toxic 4-nitrophenol to useful 4-aminophenol by NaBH4. The rate constant value of reduction reaction reached up to 0.106 s-1 by Au/CeO2@g-C3N4, which was 3.8, and 8.8 times higher than that of Au@CeO2 (0.028 s-1), and Au@g-C3N4 (0.012 s-1) nanocomposites, respectively. The superior catalytic performance of as-prepared catalyst in 4-NP reduction can be attributed to synergistic effect between Au nanoparticles and CeO2@g-C3N4 support, and efficient electron transfer. The reduction reaction was carried out at different temperatures, and the energy of activation ({Ea}), and thermodynamic parameters including, activation of entropy (Δ S^ ≠), enthalpy (Δ H^ ≠), and Gibbs free energy (Δ G^ ≠) were determined. Additionally, the mechanism of reaction was studied in details, and equilibrium constants of 4-NP ( K 4-NP), and {BH}4^{ - } ({K_{{BH}4^{{ - }} }}) were calculated using Langmuir-Hinshelwood model. Furthermore, this nanocomposite exhibited excellent catalytic activity in oxidation of benzyl alcohol by molecular oxygen as a green oxidant. This study revealed that the ternary Au/CeO2@g-C3N4 nanocomposite is an attractive candidate for catalytic applications.
Life on N2O: deciphering the ecophysiology of N2O respiring bacterial communities in a continuous culture.

Science.gov (United States)

Conthe, Monica; Wittorf, Lea; Kuenen, J Gijs; Kleerebezem, Robbert; van Loosdrecht, Mark C M; Hallin, Sara

2018-04-01

Reduction of the greenhouse gas N 2 O to N 2 is a trait among denitrifying and non-denitrifying microorganisms having an N 2 O reductase, encoded by nosZ. The nosZ phylogeny has two major clades, I and II, and physiological differences among organisms within the clades may affect N 2 O emissions from ecosystems. To increase our understanding of the ecophysiology of N 2 O reducers, we determined the thermodynamic growth efficiency of N 2 O reduction and the selection of N 2 O reducers under N 2 O- or acetate-limiting conditions in a continuous culture enriched from a natural community with N 2 O as electron acceptor and acetate as electron donor. The biomass yields were higher during N 2 O limitation, irrespective of dilution rate and community composition. The former was corroborated in a continuous culture of Pseudomonas stutzeri and was potentially due to cytotoxic effects of surplus N 2 O. Denitrifiers were favored over non-denitrifying N 2 O reducers under all conditions and Proteobacteria harboring clade I nosZ dominated. The abundance of nosZ clade II increased when allowing for lower growth rates, but bacteria with nosZ clade I had a higher affinity for N 2 O, as defined by μ max /K s . Thus, the specific growth rate is likely a key factor determining the composition of communities living on N 2 O respiration under growth-limited conditions.
Automated online measurement of N2, N2O, NO, CO2, and CH4 emissions based on a gas-flow-soil-core technique.

Science.gov (United States)

Liao, Tingting; Wang, Rui; Zheng, Xunhua; Sun, Yang; Butterbach-Bahl, Klaus; Chen, Nuo

2013-11-01

The gas-flow-soil-core (GFSC) technique allows to directly measure emission rates of denitrification gases of incubated soil cores. However, the technique was still suffering some drawbacks such as inadequate accuracy due to asynchronous detection of dinitrogen (N2) and other gases and low measurement frequency. Furthermore, its application was limited due to intensive manual operation. To overcome these drawbacks, we updated the GFSC system as described by Wang et al. (2011) by (a) using both a chemiluminescent detector and a gas chromatograph detector to measure nitric oxide (NO), (b) synchronizing the measurements of N2, NO, nitrous oxide (N2O), carbon dioxide (CO2) and methane (CH4), and (c) fully automating the sampling/analysis of all the gases. These technical modifications significantly reduced labor demands by at least a factor of two, increased the measurement frequency from 3 to 6 times per day and resulted in remarkable improvements in measurement accuracy (with detection limits of 0.5, 0.01, 0.05, 2.3 and 0.2μgN or Ch(-1)kg(-1)ds, or 17, 0.3, 1.8, 82, and 6μgN or Cm(-2)h(-1), for N2, N2O, NO, CO2, and CH4, respectively). In some circumstances, the modified system measured significantly more N2 and CO2 and less N2O and NO because of the enhanced measurement frequency. The modified system distinguished the differences in emissions of the denitrification gases and CO2 due to a 20% change in initial carbon supplies. It also remarkably recovered approximately 90% of consumed nitrate during incubation. These performances validate the technical improvement, and indicate that the improved GFSC system may provide a powerful research tool for obtaining deeper insights into the processes of soil carbon and nitrogen transformation during denitrification. Copyright © 2013. Published by Elsevier Ltd.
Atmospheric chemistry of CH3O(CF2CF2O)(n)CH3 (n=1-3): Kinetics and mechanism of oxidation initiated by Cl atoms and OH radicals, IR spectra, and global warmin potentials

DEFF Research Database (Denmark)

Andersen, Mads Peter Sulbæk; Hurley, MD; Wallington, TJ

2004-01-01

Smog chambers equipped with FTIR spectrometers were used to study the Cl atom and OH radical initiated oxidation of CH3O(CF2CF2O)(n)CH3 (n = 1-3) in 720 +/- 20 Torr of air at 296 +/- 3 K. Relative rate techniques were used to measure k(Cl + CH3O(CF2CF2O)(n)CH3) (3.7 +/- 10.7) x 10(-13) and k......(OH + CH3O(CF2CF2O)(n)CH3) = (2.9 +/- 0.5) x 10(-11) cm(3) molecule(-1) s(-1) leading to an estimated atmospheric lifetime of 2 years for CH3O(CF2CF2O),CH3. The Cl initiated oxidation of CH3O(CF2CF2O),CH3 in air diluent gives CH3O(CF2CF2O)(n)C(O)H in a yield which is indistinguishable from 100 Further...... oxidation leads to the diformate, H(O)CO(CF2CF2O)(n)C(O)H. A rate constant of k(Cl + CH3O(CF2CF2O)(n)CHO) = (1.81 +/- 0.36) x 10(-13) cm(3) molecule(-1) s-1 was determined. Quantitative infrared spectra for CH3O(CF2CF2O)(n)CH3 (n = 1-3) were recorded and used to estimate halocarbon global warming potentials...
Bis[2-(2-aminoethyl-1H-benzimidazole-κ2N2,N3](nitrato-κ2O,O′cobalt(II chloride trihydrate

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Jing Zhao

2012-06-01

Full Text Available In the title compound, [Co(NO3(C9H11N32]Cl·3H2O, the CoII atom is coordinated by four N atoms from two chelating 2-(2-aminoethyl-1H-benzimidazole ligands and two O atoms from one nitrate anion in a distorted octahedral coordination environment. In the crystal, N—H...Cl, N—H...O, O—H...Cl and O—H...O hydrogen bonds link the complex cations, chloride anions and solvent water molecules into a three-dimensional network. π–π interactions between the imidazole and benzene rings and between the benzene rings are observed [centroid–centroid distances = 3.903 (3, 3.720 (3, 3.774 (3 and 3.926 (3 Å].
{2-[(2-Acetylhydrazin-1-ylidenemethyl-κ2N1,O]-6-methoxyphenolato-κO1}(nitrato-κOcopper(II monohydrate

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Ibrahima Elhadj Thiam

2010-02-01

Full Text Available In the title complex, [Cu(C10H11N2O3(NO3]·H2O, prepared from the Schiff base N′-(3-methoxy-2-oxidobenzylideneacetohydrazide, the CuII atom is coordinated by two O atoms and one N atom from the ligand and one O atom from a nitrate group in a distorted square-planar geometry. The CuII atom has a weak interaction with another O atom of the nitrate group. The two O atoms of the tridentate Schiff base ligand are in a trans arrangement. O—H...O and N—H...O hydrogen bonds involving the uncoordinated water molecule are observed.
Synthesis of g-C3N4/Fe3O4 nanocomposites and application as a new sorbent for solid phase extraction of polycyclic aromatic hydrocarbons in water samples.

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Wang, Man; Cui, Shihai; Yang, Xiaodi; Bi, Wentao

2015-01-01

An easy preparation of g-C3N4/Fe3O4 nanocomposites by chemical co-precipitation has been demonstrated. The as-prepared materials were characterized by X-ray diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy and thermogravimetric analysis. The high affinity of g-C3N4 toward polycyclic aromatic hydrocarbons and the magnetic behavior of Fe3O4 were combined to provide an efficient and simple magnetic solid phase extraction (MSPE). The adsorption and desorption of polycyclic aromatic hydrocarbons on g-C3N4/Fe3O4 were examined. Different factors affecting the magnetic solid phase extraction of polycyclic aromatic hydrocarbons were assessed in terms of adsorption, desorption, and recovery. Under the optimized conditions, the proposed method showed good limits of detection (LOD, S/N=3) in the range of 0.05-0.1 ng mL(-1) and precision in the range of 1.8-5.3% (RSDs, n=3). This method was also successfully applied to the analysis of real water samples; good spiked recoveries over the range of 80.0-99.8% were obtained. Copyright © 2014 Elsevier B.V. All rights reserved.
Poly[(μ3-benzene-1,3,5-tricarboxylato-κ3O1:O3:O5(μ2-2-methylimidazolato-κ2N:N′tris(2-methylimidazole-κNdizinc(II

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Palanikumar Maniam

2011-06-01

Full Text Available Hydrothermal reaction involving zinc nitrate hexahydrate, trisodium benzene-1,3,5-tricarboxylate (Na3BTC and 2-methylimidazole (2-MeImH yielded the title compound, [Zn2(C9H3O6(C4H5N2(C4H6N23]. In this mixed-ligand metal-organic compound, Zn2+ ions are coordinated by N atoms from 2-MeImH molecules and (2-MeIm− ions, as well as by O atoms from (BTC3− ions. This results in two different distorted tetrahedra, viz. ZnN3O and ZnN2O2. These tetrahedra are interconnected via (BTC3− ions and N:N′-bridging (2-MeIm− ions, thus forming a layered structure in the bc plane. Hydrogen bonds between the O atoms of carboxylate ions and NH groups of 2-MeImH ligands link the layers into a three-dimensional structure.
cyclo-Tetrakis(μ-3-acetyl-4-methyl-1H-pyrazole-5-carboxylato-κ4N2,O3:N1,O5tetrakis[aquacopper(II] tetradecahydrate

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Sergey Malinkin

2011-09-01

Full Text Available The title compound, [Cu4(C7H6N2O34(H2O4]·14H2O, a tetranuclear [2 × 2] grid-type complex with S4 symmetry, contains four CuII atoms which are bridged by four pyrazolecarboxylate ligand anions and are additionally bonded to a water molecule. Each CuII atom is coordinated by two O atoms of the carboxylate and acetyl groups, two pyrazole N atoms of doubly deprotonated 3-acetyl-4-methyl-1H-pyrazole-5-carboxylic acid and one O atom of a water molecule. The geometry at each CuII atom is distorted square-pyramidal, with the two N and two O atoms in the equatorial plane and O atoms in the axial positions. O—H...O hydrogen-bonding interactions additionally stabilize the structure. One of the uncoordinated water molecules shows half-occupancy.
In situ synthesis of g-C3N4/TiO2 heterojunction nanocomposites as a highly active photocatalyst for the degradation of Orange II under visible light irradiation.

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Ren, Bin; Wang, Tiecheng; Qu, Guangzhou; Deng, Fang; Liang, Dongli; Yang, Wenli; Liu, Meishan

2018-05-04

As a highly active photocatalyst, g-C 3 N 4 /TiO 2 heterojunction nanocomposites were in situ synthesized by simple ultrasonic mixing and calcination by using TiO 2 and melamine as precursors. The morphology and structure of the prepared photocatalysts were characterized by field emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Fourier-transform infrared spectroscopy, UV-Vis diffuse reflectance spectroscopy, and X-ray photoelectron spectroscopy. The photocatalytic activities of g-C 3 N 4 /TiO 2 nanocomposites to degrade Orange II (AO7) under visible light irradiation were evaluated. Results showed that the photocatalytic rate of the prepared g-C 3 N 4 /TiO 2 photocatalyst to degrade AO7 was about three times than that of pristine TiO 2 and g-C 3 N 4 . The g-C 3 N 4 /TiO 2 composite with a ratio of 1:4 had the highest degradation efficiency for AO7 solution. Its degradation efficiency under acidic conditions was significantly higher than that under alkaline conditions. The enhancement of photocatalytic activity can be attributed to the formation of heterojunctions between g-C 3 N 4 and TiO 2 , which leads to rapid charge transfer and the efficient separation of photogenerated electron-hole pairs. The recycling experiment indicated that the photocatalyst of g-C 3 N 4 /TiO 2 nanocomposites still maintained good photochemical stability and recyclability after five cycles; this finding was important for its practical applications. A series of free radical trapping experiments showed that •O 2 - played a crucial role in the degradation of AO7. Graphical Abstract ᅟ.
Spectroscopic Studies of Semiconductor Materials for Aggressive-scaled Micro- and Opto-electronic Devices: nc-SiO2, GeO2; ng-Si, Ge and ng-Transition metal (TM) oxides

Science.gov (United States)

Cheng, Cheng

transitions. Intra-d states are observed in all high-K dielectrics regardless of morphology, e.g. ng-TiO2, nc- Ti silicate , c-LaTiO3, nc-HfSiON334. This dissertation also discussed spectroscopic studies of: (i) nc-SiO 2, nc-GeO2 and (ii) nc-(SiO2)x(GeO2) 1-x pseudo-binary alloys. These studies, and the interpretation of these spectra and those in Chapter 3 in the This dissertation also discussed spectroscopic studies of: (i) nc-SiO2, nc-GeO2 and (ii) nc-(SiO 2)x(GeO2)1-x pseudo-binary alloys. These studies, and the interpretation of these spectra and those in Chapter 3 in the context of ab-initio theory provide a science base for the implementation of nc-oxides onto Germaniumsubstrates for aggressively scaled CMOS FETs, imaging devices as well as photovoltaics. X-Ray photoelectron spectroscopy(XPS) and Auger electron spectroscopy(AES) were used to determine SiO2 and GeO2 concentration in (SiO2)x(GeO2)1-x alloys. A linear trend in chemical shifts with compositions is observed and explained with charge-potential model, which incorporates the results of calculated partial charge from an empirical model for ionicity. The compositional linear relationships between binding energies nc-SiO 2, nc-GeO2, and (SiO2)x(GeO2)1-x alloy concentration agrees with the calculated results in charge potential model. SE and XAS spectral results show relatively strong O-vacancy in nc-GeO 2. O-vacancy defects in c-SiO2 are weaker. This is due to differences between Ge-O and Si-O bond (657.5kJ/mol and 799.6kJ/mol respectively). SE data shows a strong defect feature in GeO2, while SiO2 has no significant and distinct defect signature. Percolation theory describes the interconnection of bonds, e.g. Si-O and Ge-O in an otherwise nc-material, a (SiO2)x(GeO2)1-x pseudo-binary alloy. Changes in the band-gap energy of binary Si-Ge alloys occur at 0%Si (or 100% Ge), and the band gap energy increases from ˜ 0.6 eV to ˜0.87 eV as the Si concentration increases. A inflection point is at the percolation

Epitaxial Gd2O3 on GaN and AlGaN: a potential candidate for metal oxide semiconductor based transistors on Si for high power application

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Ghosh, Kankat; Das, S.; Khiangte, K. R.; Choudhury, N.; Laha, Apurba

2017-11-01

We report structural and electrical properties of hexagonal Gd2O3 grown epitaxially on GaN/Si (1 1 1) and AlGaN/GaN/Si(1 1 1) virtual substrates. GaN and AlGaN/GaN heterostructures were grown on Si(1 1 1) substrates by plasma assisted molecular beam epitaxy (PA-MBE), whereas the Gd2O3 layer was grown by the pulsed laser ablation (PLA) technique. Initial structural characterizations show that Gd2O3 grown on III-nitride layers by PLA, exhibit a hexagonal structure with an epitaxial relationship as {{≤ft[ 0 0 0 1 \\right]}G{{d2}{{O}3}}}||{{≤ft[ 0 0 0 1 \\right]}GaN} and {{≤ft[ 1 \\bar{1} 0 0 \\right]}G{{d2}{{O}3}}}||{{≤ft[ 1 \\bar{1} 0 0 \\right]}GaN} . X-ray photoelectron measurements of the valence bands revealed that Gd2O3 exhibits band offsets of 0.97 eV and 0.4 eV, for GaN and Al0.3Ga0.7N, respectively. Electrical measurements such as capacitance-voltage and leakage current characteristics further confirm that epi-Gd2O3 on III-nitrides could be a potential candidate for future metal-oxide-semiconductor (MOS)-based transistors also for high power applications in radio frequency range.
Two years monitoring of soil N_{2}O emissions on durum wheat in a Mediterranean area: the effect of tillage intensity and N-fertilizer rate.

Science.gov (United States)

Volpi, Iride; Bosco, Simona; Triana, Federico; Di Nasso, Nicoletta Nassi o.; Laville, Patricia; Virgili, Giorgio; Bonari, Enrico

2016-04-01

Evaluating the magnitude and the key factors affecting N2O emissions from agriculture has a scientific and practical relevance, in fact emissions from agricultural and natural soils account for 56-70% of all global N2O sources (Syakila and Kroeze, 2011). Moreover, the necessity to increase the food production rate minimizing greenhouse gas emissions require a deeper understanding of the effect of the agricultural practices on direct soil emissions. Therefore, the aim of this work is to assess the effect of tillage intensity and nitrogen rate on soil N2O emissions on durum wheat. A two years monitoring campaign was carried out using a high-sensibility transportable instrument developed within the LIFE+ "Improved flux Prototypes for N2O emission from Agriculture" IPNOA project (Bosco et al., 2015; Laville et al., 2015). The project aims at improving the measurement technique of N2O flux directly in field using the flow-through non-steady state chamber technique. The monitoring campaign on durum wheat lasted for two growing seasons and two fallow periods (2013-14 and 2014-15). Treatment on the main plot was tillage intensity with two levels, ploughing and minimum tillage, and three different nitrogen rates were distributed to the subplots (N0: 0 kg ha-1, N1: 110 kg ha-1, N2: 170 kg ha-1). Ancillary measurements concerned meteorological data, soil temperature and moisture, NO3-, NH4+ soil concentration. Main results of the two years highlighted N rate as the main driver for both N2O daily flux and cumulative emissions during the growing season, while in the fallow period treatments did not affect the emission magnitude. Tillage intensity was not a key factor for N2O emissions. N2O emissions were significantly different in the two years. In particular, cumulative emissions of 2013-14 were about five times higher than in 2014-15, respectively on average 2885±260 g N-N2O ha-1 and 534±53 g N-N2O ha-1 for a similar monitoring period of about 300 days. Differences could be
(2,4-Dioxo-1,2,3,4-tetrahydropyrimidine-5-carboxylato-κ2O4,O5(4-oxido-2-oxo-1,2-dihydropyrimidine-5-carboxylato-κ2O4,O5bis(1,10-phenanthroline-κ2N,N′yttrium(III dihydrate

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Zilu Chen

2008-09-01

Full Text Available In the title compound, [Y(C5H2N2O4(C5H3N2O4(C12H8N22]·2H2O, the YIII ion lies on a twofold rotation axis and exhibits a distorted square-antiprismatic coordination geometry. It is chelated by two 1,10-phenanthroline ligands, a 2,4-dioxo-1,2,3,4-tetrahydropyrimidine-5-carboxylate monoanion and a 4-oxido-2-oxo-1,2-dihydropyrimidine-5-carboxylate dianion. The H atom involved in an N—H...N hydrogen bond between the 1,2-dihydropyrimidine units has half occupancy and is disordered around a twofold rotation axis.
Water-containing derivative phases of the Srn+1FenO3n+1 series

International Nuclear Information System (INIS)

Lehtimaeki, M.; Hirasa, A.; Matvejeff, M.; Yamauchi, H.; Karppinen, M.

2007-01-01

The n=1, 2, 3 and ∞ members of the homologous series Sr n+1 Fe n O 3n+1 of layered iron oxides are investigated for their tendency to accept additional layers of water in their crystals. The phases possess a Ruddlesden-Popper-type SrO-(SrO-FeO 2 ) n crystal structure, where the n=∞ limit is nothing but the perovskite structure. It is revealed that the n=1, 2 and 3 phases readily accommodate one or two layers of water between adjacent SrO layers, whereas the n=∞ member which lacks the SrO-SrO double-layer unit remains intact in the presence of water. The speed of the water intercalation process is found to decrease with increasing n. Among the layered water derivatives, the n=2 phase with two water molecules per formula unit, i.e. Sr 3 Fe 2 O 7 .2H 2 O, was found to be most stable. - Graphical abstract: Water-containing derivative phases obtained from the homologous series of Sr n+1 Fe n O 3n+1 Ruddlesden-Popper phases through topotactic water intercalation
N{sub 2}O Emission from energy crop fields

Energy Technology Data Exchange (ETDEWEB)

Joergensen, B.J. [The Royal Veterinary and Agricultural Univ., Dept. of Agricultural Sciences, Section of Soil, Water and Plant Nutrition (Denmark); Nyholm Joergensen, R. [Research Centre Foulum, The Danish Inst. of Plant and Soil Science, Dept. of Soil Science (Denmark)

1996-03-01

The interest in N{sub 2}O emissions from soils with energy crops is a results of its properties as a greenhouse gas, since the global warming potential of N{sub 2}O per unit mass is about 320 times greater than CO{sub 2}. The contribution of N{sub 2}O from the soil to the atmosphere may increase due to agricultural management. Consequently, large N{sub 2}O emissions can lower the reduction of the greenhouse effect achieved by the substitution of fossil fuels by energy crops. For this reason it is crucial to find the crops for combustion with the lowest potential for emission of N{sub 2}O from the soil per produced energy unit. The aims of this study were to assess the annual N{sub 2}O flux from a Miscanthus 'Giganteus' (M. 'Giganteus') and winter rye (Secale cereale) field, and to investigate the factors affecting the N{sub 2}O emission. To obtain these aims a method was developed for measurements in tall crops. The thesis contains a literature review on the N{sub 2}O emission from the soils, a section with development of the technique for N{sub 2}O flux measurements, and an experimental section. Finally, the thesis contains a section where the results are discussed in relation to the use of energy crops. In all the filed studies, the N{sub 2}O emission was measured by using a new developed closed-chamber technique. The main advantages of the chamber method were the ability to contain growing plants up to a height of 3 m, and the relatively large area (2X2m) covered by each other. Soils with annual and perennial crops can be expected to emit less then 3 kg N{sub 2}O ha{sup -1} yr{sup -1}. This amount corresponds to 960 kg CO{sub 2} ha{sup -1} yr{sup -1} compared to a total CO{sub 2} reduction of 10 to 19 tons CO{sub 2} ha{sup -1} yr{sup -1} using the energy crops as substitution for fossil fuels. An efficient way to reduce the N{sub 2}O emission is to exclude use of fertiliser but this also reduces the dry matter yield and consequently also the
N{sub 2}O Emission from energy crop fields

Energy Technology Data Exchange (ETDEWEB)

Joergensen, B.J. [The Royal Veterinary and Agricultural Univ., Dept. of Agricultural Sciences, Section of Soil, Water and Plant Nutrition (Denmark); Nyholm Joergensen, R. [Research Centre Foulum, The Danish Inst. of Plant and Soil Science, Dept. of Soil Science (Denmark)

1996-03-01

The interest in N{sub 2}O emissions from soils with energy crops is a results of its properties as a greenhouse gas, since the global warming potential of N{sub 2}O per unit mass is about 320 times greater than CO{sub 2}. The contribution of N{sub 2}O from the soil to the atmosphere may increase due to agricultural management. Consequently, large N{sub 2}O emissions can lower the reduction of the greenhouse effect achieved by the substitution of fossil fuels by energy crops. For this reason it is crucial to find the crops for combustion with the lowest potential for emission of N{sub 2}O from the soil per produced energy unit. The aims of this study were to assess the annual N{sub 2}O flux from a Miscanthus `Giganteus` (M. `Giganteus`) and winter rye (Secale cereale) field, and to investigate the factors affecting the N{sub 2}O emission. To obtain these aims a method was developed for measurements in tall crops. The thesis contains a literature review on the N{sub 2}O emission from the soils, a section with development of the technique for N{sub 2}O flux measurements, and an experimental section. Finally, the thesis contains a section where the results are discussed in relation to the use of energy crops. In all the filed studies, the N{sub 2}O emission was measured by using a new developed closed-chamber technique. The main advantages of the chamber method were the ability to contain growing plants up to a height of 3 m, and the relatively large area (2X2m) covered by each other. Soils with annual and perennial crops can be expected to emit less then 3 kg N{sub 2}O ha{sup -1} yr{sup -1}. This amount corresponds to 960 kg CO{sub 2} ha{sup -1} yr{sup -1} compared to a total CO{sub 2} reduction of 10 to 19 tons CO{sub 2} ha{sup -1} yr{sup -1} using the energy crops as substituion for fossil fuels. An efficient way to reduce the N{sub 2}O emission is to exclude use of fertiliser but this also reduces the dry matter yield and consequently also the CO{sub 2} reduction
Comparative analysis of the effects of tantalum doping and annealing on atomic layer deposited (Ta2O5)x(Al2O3)1−x as potential gate dielectrics for GaN/AlxGa1−xN/GaN high electron mobility transistors

International Nuclear Information System (INIS)

Partida-Manzanera, T.; Roberts, J. W.; Sedghi, N.; Potter, R. J.; Bhat, T. N.; Zhang, Z.; Tan, H. R.; Dolmanan, S. B.; Tripathy, S.

2016-01-01

This paper describes a method to optimally combine wide band gap Al 2 O 3 with high dielectric constant (high-κ) Ta 2 O 5 for gate dielectric applications. (Ta 2 O 5 ) x (Al 2 O 3 ) 1−x thin films deposited by thermal atomic layer deposition (ALD) on GaN-capped Al x Ga 1−x N/GaN high electron mobility transistor (HEMT) structures have been studied as a function of the Ta 2 O 5 molar fraction. X-ray photoelectron spectroscopy shows that the bandgap of the oxide films linearly decreases from 6.5 eV for pure Al 2 O 3 to 4.6 eV for pure Ta 2 O 5 . The dielectric constant calculated from capacitance-voltage measurements also increases linearly from 7.8 for Al 2 O 3 up to 25.6 for Ta 2 O 5 . The effect of post-deposition annealing in N 2 at 600 °C on the interfacial properties of undoped Al 2 O 3 and Ta-doped (Ta 2 O 5 ) 0.12 (Al 2 O 3 ) 0.88 films grown on GaN-HEMTs has been investigated. These conditions are analogous to the conditions used for source/drain contact formation in gate-first HEMT technology. A reduction of the Ga-O to Ga-N bond ratios at the oxide/HEMT interfaces is observed after annealing, which is attributed to a reduction of interstitial oxygen-related defects. As a result, the conduction band offsets (CBOs) of the Al 2 O 3 /GaN-HEMT and (Ta 2 O 5 ) 0.16 (Al 2 O 3 ) 0.84 /GaN-HEMT samples increased by ∼1.1 eV to 2.8 eV and 2.6 eV, respectively, which is advantageous for n-type HEMTs. The results demonstrate that ALD of Ta-doped Al 2 O 3 can be used to control the properties of the gate dielectric, allowing the κ-value to be increased, while still maintaining a sufficient CBO to the GaN-HEMT structure for low leakage currents
Effect of the thin Ga2O3 layer in n+-ZnO/n-Ga2O3/p-Cu2O heterojunction solar cells

International Nuclear Information System (INIS)

Minami, Tadatsugu; Nishi, Yuki; Miyata, Toshihiro

2013-01-01

The influence of inserting a Ga 2 O 3 thin film as an n-type semiconductor layer on the obtainable photovoltaic properties in Cu 2 O-based heterojunction solar cells was investigated with a transparent conductive Al-doped ZnO (AZO) thin film/n-Ga 2 O 3 thin film/p-Cu 2 O sheet structure. It was found that this Ga 2 O 3 thin film can greatly improve the performance of Cu 2 O-based heterojunction solar cells fabricated using polycrystalline Cu 2 O sheets that had been prepared by a thermal oxidization of copper sheets. The obtained photovoltaic properties in the AZO/Ga 2 O 3 /Cu 2 O heterojunction solar cells were strongly dependent on the deposition conditions of the Ga 2 O 3 films. The external quantum efficiency obtained in AZO/Ga 2 O 3 /Cu 2 O heterojunction solar cells was found to be greater at wavelengths below approximately 500 nm than that obtained in AZO/Cu 2 O heterojunction solar cells (i.e., prepared without a Ga 2 O 3 layer) at equivalent wavelengths. This improvement of photovoltaic properties is mainly attributed to a decrease in the level of defects at the interface between the Ga 2 O 3 thin film and the Cu 2 O sheet. Conversion efficiencies over 5% were obtained in AZO/Ga 2 O 3 /Cu 2 O heterojunction solar cells fabricated using an n-Ga 2 O 3 thin-film layer prepared with a thickness of 40–80 nm at an O 2 gas pressure of approximately 1.7 Pa by a pulsed laser deposition. - Highlights: • We demonstrate high-efficiency Cu 2 O-based p-n heterojunction solar cells. • A non-doped Ga 2 O 3 thin film was used as an n-type semiconductor layer. • The Ga 2 O 3 thin film was prepared at a low temperature by a low damage deposition. • p-type Cu 2 O sheets prepared by thermal oxidization of copper sheets were used. • Conversion efficiencies over 5% were obtained in AZO/n-Ga 2 O 3 /p-Cu 2 O solar cells
UV-induced N2O emission from plants

Science.gov (United States)

Bruhn, Dan; Albert, Kristian R.; Mikkelsen, Teis N.; Ambus, Per

2014-12-01

Nitrous oxide (N2O) is an important long-lived greenhouse gas and precursor of stratospheric ozone-depleting mono-nitrogen oxides. The atmospheric concentration of N2O is persistently increasing; however, large uncertainties are associated with the distinct source strengths. Here we investigate for the first time N2O emission from terrestrial vegetation in response to natural solar ultra violet radiation. We conducted field site measurements to investigate N2O atmosphere exchange from grass vegetation exposed to solar irradiance with and without UV-screening. Further laboratory tests were conducted with a range of species to study the controls and possible loci of UV-induced N2O emission from plants. Plants released N2O in response to natural sunlight at rates of c. 20-50 nmol m-2h-1, mostly due to the UV component. The emission response to UV-A is of the same magnitude as that to UV-B. Therefore, UV-A is more important than UV-B given the natural UV-spectrum at Earth's surface. Plants also emitted N2O in darkness, although at reduced rates. The emission rate is temperature dependent with a rather high activation energy indicative for an abiotic process. The prevailing zone for the N2O formation appears to be at the very surface of leaves. However, only c. 26% of the UV-induced N2O appears to originate from plant-N. Further, the process is dependent on atmospheric oxygen concentration. Our work demonstrates that ecosystem emission of the important greenhouse gas, N2O, may be up to c. 30% higher than hitherto assumed.
Ab initio studies of O2-(H2O)n and O3-(H2O)n anionic molecular clusters, n≤12

DEFF Research Database (Denmark)

Bork, Nicolai Christian; Kurtén, T.; Enghoff, Martin Andreas Bødker

2011-01-01

that anionic O2−(H2O)n and O3−(H2O)n clusters are thermally stabilized at typical atmospheric conditions for at least n = 5. The first 4 water molecules are strongly bound to the anion due to delocalization of the excess charge while stabilization of more than 4 H2O is due to normal hydrogen bonding. Although...... clustering up to 12 H2O, we find that the O2 and O3 anions retain at least ca. 80 % of the charge and are located at the surface of the cluster. The O2− and O3− speicies are thus accessible for further reactions. Finally, the thermodynamics of a few relevant cluster reactions are considered....
Diaqua[N,N′-bis(2-pyridylmethylenepropane-1,3-diamine]manganese(II dibromide–aquabromido[N,N′-bis(2-pyridylmethylenepropane-1,3-diamine]manganese(II bromide–dibromido[N,N′-bis(2-pyridylmethylenepropane-1,3-diamine]manganese(II (1/2/1

Directory of Open Access Journals (Sweden)

In-Chul Hwang

2009-01-01

Full Text Available There are three different MnII complexes in the asymmetric unit of the title compound, [Mn(C15H16N4(H2O2]Br2·2{[MnBr(C15H16N4(H2O]Br}·[MnBr2(C15H16N4]. In the neutral complex, the Mn2+ ion is six-coordinated in a distorted octahedral environment by four N atoms of the tetradentate ligand N,N′-bis(2-pyridylmethylenepropane-1,3-diamine (bppd and two bromide ligands. In the two cationic complexes, the Mn2+ ions are also six-coordinated in similar environments, but one Mn ion is coordinated by four N atoms of bppd, one Br atom and one O atom of a coordinating water molecule, whereas the other Mn ion is coordinated by four N atoms of bppd and two O atoms of water ligands. The complexes with two coordinated Br atoms or two H2O ligands are disposed about a twofold axis through Mn and C atoms with the special positions ({script{1over 2}}, y, 0 and (0, y, {script{1over 2}}, respectively. The compound displays intermolecular O—H...Br hydrogen bonding. There are intermolecular π–π interactions between adjacent pyridine rings, with centroid–centroid distances of 3.822 and 3.833 Å, and a C—H...O interaction is also present.
Potassium (2,2'-bipyridine-κN,N')bis-(carbonato-κO,O')cobaltate(III) dihydrate.

Science.gov (United States)

Wang, Jian-Fei; Lin, Jian-Li

2010-09-30

In the title compound, K[Co(CO(3))(2)(C(10)H(8)N(2))]·2H(2)O, the Co(III) atom is coordinated by two bipyridine N atoms and four O atoms from two bidentate chelating carbonate anions, and thus adopts a distorted octa-hedral N(2)O(4) environment. The [Co(bipy)(CO(3))(2)](-) (bipy is 2,2'-bipyridine) -units are stacked along [100] via π-π stacking inter-actions, with inter-planar distances between the bipyridine rings of 3.36 (4) and 3.44 (6) Å, forming chains. Classical O-H⋯O hydrogen-bonding inter-actions link the chains, forming channels along (100) in which the K(+) ions reside and leading to a three-dimensional supra-molecular architecture.
Excessive use of nitrogen in Chinese agriculture results in high N2O/(N2O+N2) product ratio of denitrification, primarily due to acidification of the soils

Science.gov (United States)

Qu, Zhi; Wang, Jingguo; Almøy, Trygve; Bakken, Lars R

2014-01-01

China is the world's largest producer and consumer of fertilizer N, and decades of overuse has caused nitrate leaching and possibly soil acidification. We hypothesized that this would enhance the soils' propensity to emit N2O from denitrification by reducing the expression of the enzyme N2O reductase. We investigated this by standardized oxic/anoxic incubations of soils from five long-term fertilization experiments in different regions of China. After adjusting the nitrate concentration to 2 mM, we measured oxic respiration (R), potential denitrification (D), substrate-induced denitrification, and the denitrification product stoichiometry (NO, N2O, N2). Soils with a history of high fertilizer N levels had high N2O/(N2O+N2) ratios, but only in those field experiments where soil pH had been lowered by N fertilization. By comparing all soils, we found a strong negative correlation between pH and the N2O/(N2O+N2) product ratio (r2 = 0.759, P soil pH. The immediate effect of liming acidified soils was lowered N2O/(N2O+N2) ratios. The results provide evidence that soil pH has a marginal direct effect on potential denitrification, but that it is the master variable controlling the percentage of denitrified N emitted as N2O. It has been known for long that low pH may result in high N2O/(N2O+N2) product ratios of denitrification, but our documentation of a pervasive pH-control of this ratio across soil types and management practices is new. The results are in good agreement with new understanding of how pH may interfere with the expression of N2O reductase. We argue that the management of soil pH should be high on the agenda for mitigating N2O emissions in the future, particularly for countries where ongoing intensification of plant production is likely to acidify the soils. PMID:24249526
Oriented growth of Sr n+1Ti n O3n+1 Ruddlesden-Popper phases in chemical solution deposited thin films

International Nuclear Information System (INIS)

Gutmann, Emanuel; Levin, Alexandr A.; Reibold, Marianne; Mueller, Jan; Paufler, Peter; Meyer, Dirk C.

2006-01-01

Oriented thin films of perovskite-related Sr n +1 Ti n O 3 n +1 Ruddlesden-Popper phases (n=1, 2, 3) were grown on (001) single-crystalline SrTiO 3 substrates. Preparation of the films was carried out by wet chemical deposition from metalorganic Sr-Ti solutions (rich in Sr) and subsequent conversion into the crystalline state by thermal treatment in air atmosphere at a maximum temperature of 700 deg. C. Solutions were prepared by a modified Pechini method. The films were investigated by wide-angle X-ray scattering and high-resolution transmission electron microscopy. The phase content of powders prepared from the dried solutions and annealed under similar conditions differed from that present in the films, i.e. only polycrystalline SrTiO 3 was detected together with oxides of Ti and Sr. - Graphical abstract: Cross-sectional image of an oriented chemical solution deposited thin film obtained by high-resolution transmission electron microscopy. Periodical spacings corresponding to SrTiO 3 substrate (right) and Sr 2 TiO 4 Ruddlesden-Popper phase (n=1) film region (left) are marked
FLAT TIME-LIKE SUBMANIFOLDS IN ANTI-DE SITTER SPACE H12n-1(-1)

Institute of Scientific and Technical Information of China (English)

ZUO DAFENG; CHEN QING; CHENG YI

2005-01-01

By using dressing actions of the Gn-1 1,1,n-1-system, the authors study geometric transformations for flat time-like n-submanifolds with flat, non-degenerate normal bun dle in anti-de Sitter space H1 2n-1(-1), where G1,1 n-1,n-1= O(2n - 2, 2)/O(n - 1, 1) ×O(n - 1, 1).
Fabrication, characterization, and photocatalytic performance of exfoliated g-C{sub 3}N{sub 4}–TiO{sub 2} hybrids

Energy Technology Data Exchange (ETDEWEB)

Chang, Fei, E-mail: feichang@usst.edu.cn [School of Environment and Architecture, University of Shanghai for Science and Technology, Shanghai 200093 (China); Zhang, Jian; Xie, Yunchao; Chen, Juan; Li, Chenlu; Wang, Jie; Luo, Jieru; Deng, Baoqing [School of Environment and Architecture, University of Shanghai for Science and Technology, Shanghai 200093 (China); Hu, Xuefeng, E-mail: xfhu@yic.ac.cn [Key Laboratory of Coastal Zone Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai 264003, Shandong (China)

2014-08-30

Highlights: • Synthesis of TiO{sub 2} hybrids with exfoliated g-C{sub 3}N{sub 4} was provided. • Heterojunction structures were formed and identified by several analytic techniques. • Newly prepared CNs–TiO{sub 2} hybrids showed obviously enhanced photocatalytic ability toward degradation of dye RhB. • Photoinduced holes made an important role on photocatalytic process. - Abstract: A series of TiO{sub 2} hybrids composited with exfoliated g-C{sub 3}N{sub 4} nanosheets (CNs) were successfully synthesized through a facile sol–gel method and fully characterized by X-ray diffraction patterns (XRD), Fourier transform-infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and UV–vis diffuse reflectance spectra (UV–vis DRS). The CNs–TiO{sub 2} hybrids were exposed to visible light irradiation and showed much higher catalytic capability toward degrading dye rhodamine B (RhB) comparing with bare TiO{sub 2} and N-TiO{sub 2}. The sample CNs–TiO{sub 2}-0.05 exhibited the largest apparent reaction rate constant among all CNs–TiO{sub 2} hybrids, which was 2.4 times and 7.0 times as high as bare TiO{sub 2} and N-TiO{sub 2}, respectively. The enhanced catalytic efficiency could be mainly attributed to the well-matched band gap structure with heterojunction interface, suitable specific surface area, and favorable optical property. In addition, active species trapping experiments were conducted, revealing that photoinduced holes (h{sup +}) had a severe influence on catalytic outcome, through which a possible catalytic mechanism was finally realized and proposed.
Air-Sea Interactions of Natural Long-Lived Greenhouse Gases (CO2, N2O, CH4) in a Changing Climate

Digital Repository Service at National Institute of Oceanography (India)

Bakker, D.C.E.; Bange, H.W.; Gruber, N.; Johannessen, T.; Upstill-Goddard, R.C.; Borges, A.V.; Delille, B.; Loscher, C.R.; Naqvi, S.W.A.; Omar, A.M.; Santana-Casiano, J.M.

at m o sp h er ic li fe ti m es G as R o le in at m o sp h er ic ch em is tr y O ce an ic co n tr ib u ti o n to co n te m p o ra ry at m o sp h er ic b u d g et Im p ac t o f en v ir o n m en ta l ch an g e o n ai r- se a g as ex ch an g e in th e tw... en ty -fi rs t ce n tu ry G lo b al w ar m in g O ce an ac id ifi ca ti o n O p en o ce an d eo x y g en at io n C o as ta l eu tr o p h ic at io n an d h y p o x ia C O 2 In er t N et o ce an si n k fo r ab o u t 3 0 % o f C O 2 em is si o n s fr o m...
Spatial and temporal variability of N2O emissions in a subtropical forest catchment in China

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J. Zhu

2013-03-01

Full Text Available Subtropical forests in southern China have received chronically large amounts of atmogenic nitrogen (N, causing N saturation. Recent studies suggest that a significant proportion of the N input is returned to the atmosphere, in part as nitrous oxide (N2O. We measured N2O emission fluxes by closed chamber technique throughout two years in a Masson pine-dominated headwater catchment with acrisols (pH ~ 4 at Tieshanping (Chongqing, SW China and assessed the spatial and temporal variability in two landscape elements typical for this region: a mesic forested hillslope (HS and a hydrologically connected, terraced groundwater discharge zone (GDZ in the valley bottom. High emission rates of up to 1800 μg N2O-N m−2 h−1 were recorded on the HS shortly after rain storms during monsoonal summer, whereas emission fluxes during the dry winter season were generally low. Overall, N2O emission was lower in GDZ than on HS, rendering the mesic HS the dominant source of N2O in this landscape. Temporal variability of N2O emissions on HS was largely explained by soil temperature (ST and moisture, pointing at denitrification as a major process for N removal and N2O production. The concentration of nitrate (NO3− in pore water on HS was high even in the rainy season, apparently never limiting denitrification and N2O production. The concentration of NO3− decreased along the terraced GDZ, indicating efficient N removal, but with moderate N2O-N loss. The extrapolated annual N2O fluxes from soils on HS (0.54 and 0.43 g N2O-N m−2 yr−1 for a year with a wet and a dry summer, respectively are among the highest N2O fluxes reported from subtropical forests so far. Annual N2O-N emissions amounted to 8–10% of the annual atmogenic N deposition, suggesting that forests on acid soils in southern China are an important, hitherto overlooked component of the anthropogenic N2O budget.
Bis[N,N-bis(1-allyl-1H-benzimidazol-2-ylmethyl-κN3benzylamine-κN]cadmium dipicrate

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Jing-Kun Yuan

2011-06-01

Full Text Available The crystal structure of the title compound, [Cd(C29H29N52](C6H2N3O72, consists of CdII complex cations and picrate anions. In the complex cation, the CdII ion is chelated by two bis(1-allylbenzimidazol-2-ylmethylbenzylamine (babb ligands in a distorted octahedral geometry. Extensive C—H...O hydrogen bonding occurs between cations and anions in the crystal structure.
Poly[[[diaquacobalt(II]-bis[μ2-1,1′-(butane-1,4-diyldiimidazole-κ2N3:N3′

Directory of Open Access Journals (Sweden)

2009-03-01

Full Text Available In the title compound, {[Co(C10H14N42(H2O2](NO32}n, the CoII ion lies on an inversion center and is six-coordinated in an octahedral environment by four N atoms from four different 1,1′-butane-1,4-diyldiimidazole ligands and two O atoms from the two water molecules. The CoII atoms are bridged by ligands, generating a two-dimensional (4,4-network. Adjacent fishnet planes are linked to the nitrate anions via O—H...O hydrogen bonds, forming a three-dimensional supramolecular structure.

Crystal structure of 2-(thiophen-2-yl)-1-(5-thioxo-4,5-dihydro-1,3,4-oxadiazol-2-yl) ethenyl]benzamide: N,N-dimethylformamide (1 : 1)

Energy Technology Data Exchange (ETDEWEB)

Sharma, P. [University of Jammu, X-ray Crystallography Laboratory, Department of Physics (India); Subbulakshmi, K. N.; Narayana, B. [Mangalore University, Department of Chemistry (India); Sarojini, B. K. [Mangalore University, Industrial Chemistry Division, Department of Studies in Chemistry (India); Kant, R., E-mail: rkant.ju@gmail.com [University of Jammu, X-ray Crystallography Laboratory, Department of Physics (India)

2016-03-15

The title compound, 2-(thiophen-2-yl)-1-(5-thioxo-4,5-dihydro-1,3,4-oxadiazol-2-yl)ethenyl] benzamide:N,N-dimethylformamide (1: 1), (C{sub 15}H{sub 11}N{sub 3}O{sub 2}S{sub 2} · C{sub 3}H{sub 7}NO), was synthesized, and its structure was established by spectral analysis and X-ray diffraction studies. The compound crystallizes in the monoclinic space group P2{sub 1}/n with a = 10.8714(7), b = 9.0497(5), c = 19.8347(13) Å, β = 91.093(5)°, Z = 4. The crystal structure is stabilized by N–H···S, C–H···O and N–H···O hydrogen bonds. The π···π interactions are also observed between the rings.
Atmospheric chemistry of n-CxF2x+1CHO (x = 1, 2, 3, 4)

DEFF Research Database (Denmark)

Hurley, M. D.; Ball, J. C.; Wallington, T. J.

2006-01-01

Smog chamber/FTIR techniques were used to study the atmospheric fate of n-C(x)F(2)(x)(+1)C(O) (x = 1, 2, 3, 4) radicals in 700 Torr O(2)/N(2) diluent at 298 +/- 3 K. A competition is observed between reaction with O(2) to form n-C(x)()F(2)(x)()(+1)C(O)O(2) radicals and decomposition to form n-C(x...... to the atmospheric chemistry of n-C(x)F(2)(x)(+1)C(O) radicals and their possible role in contributing to the formation of perfluorocarboxylic acids in the environment....
Continuous measurements of N2O emissions from arable fields

Science.gov (United States)

Wallman, Magdalena; Lammirato, Carlo; Rütting, Tobias; Delin, Sofia; Weslien, Per; Klemedtsson, Leif

2017-04-01

Agriculture represents 59 % of the anthropogenic nitrous oxide (N2O) emissions, according to the IPCC (Ciais et al. 2013). N2O emissions are typically irregular and vary widely in time and space, which makes it difficult to get a good representation of the emissions (Henault et al. 2012), particularly if measurements have low frequency and/or cover only a short time period. Manual measurements are, for practical reasons, often short-term and low-frequent, or restricted to periods where emissions are expected to be high, e.g. after fertilizing. However, the nature of N2O emissions, being largely unpredictable, calls for continuous or near-continuous measurements over long time periods. So far, rather few long-term, high resolution measurements of N2O emissions from arable fields are reported; among them are Flessa et al. (2002) and Senapati et al. (2016). In this study, we have a two-year data set (2015-2017) with hourly measurements from ten automatic chambers, covering unfertilized controls as well as different nitrogen fertilizer treatments. Grain was produced on the field, and effects of tillage, harvest and other cropping measures were covered. What we can see from the experiment is that (a) the unfertilized control plots seem to follow the same emission pattern as the fertilized plots, at a level similar to the standard mineral fertilized plots (120 kg N ha-1 yr-1) and (b) freeze/thaw emissions are comparable in size to emissions after fertilizing. These two findings imply that the importance of fertilizing to the overall N2O emissions from arable soils may be smaller than previously expected. References: Ciais, P., C. Sabine, G. Bala, L. Bopp, V. Brovkin, J. Canadell et al. 2013: Carbon and Other Biogeochemical Cycles. In: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Stocker, T.F., D. Qin, G.-K. Plattner, M. Tignor, S.K. Allen, J. Boschung et
Greenhouse gas (N2O emission from Portuguese estuaries

Directory of Open Access Journals (Sweden)

Célia Gonçalves

2014-07-01

Tagus, Minho and Lima estuaries are source of N2O to the atmosphere. Particularly, in Lima estuary anthropogenic N input seems to play an important role on N2O emission. However, in a global perspective N2O attained emissions represent a reduced fraction (2O yr-1, Barnes and Upstill-Goddard, 2011. Values are comparable with those registered in some Portuguese estuaries and other European less eutrophic estuaries. However, it is known that higher N2O emissions in estuaries may occur during winter and spring (Sun et al., 2014. Thus, these systems may represent on an annual basis a larger source of N2O, which can only be clarified in future studies. Only a full comprehension of the global estuarine nitrogen cycle will provide an efficient basis of scientific knowledge for sustainably management of such ecosystems and ultimately reduce N2O emissions.
Synthesis, crystal structure and magnetic properties of (acetato-κ²O,O')bis(5,5'-dimethyl-2,2'-bipyridine-κ²N,N')nickel(II) perchlorate monohydrate.

Science.gov (United States)

Farkašová, Nela; Černák, Juraj; Falvello, Larry R; Orendáč, Martin; Boča, Roman

2015-04-01

The title hydrated ionic complex, [Ni(CH3COO)(C12H12N2)2]ClO4·H2O or [Ni(ac)(5,5'-dmbpy)2]ClO4·H2O (where 5,5'-dmbpy is 5,5'-dimethyl-2,2'-bipyridine and ac is acetate), (1), was isolated as violet crystals from the aqueous ethanolic nickel acetate-5,5'-dmbpy-KClO4 system. Within the complex cation, the Ni(II) atom is hexacoordinated by two chelating 5,5'-dmbpy ligands and one chelating ac ligand. The mean Ni-N and Ni-O bond lengths are 2.0628 (17) and 2.1341 (15) Å, respectively. The water solvent molecule is disordered over two partially occupied positions and links two complex cations and two perchlorate anions into hydrogen-bonded centrosymmetric dimers, which are further connected by π-π interactions. The magnetic properties of (1) at low temperatures are governed by the action of single-ion anisotropy, D, which arises from the reduced local symmetry of the cis-NiO2N4 chromophore. The fitting of the variable-temperature magnetic data (2-300 K) gives g(iso) = 2.134 and D/hc = 3.13 cm(-1).
A Family of Bipartite |Cardinality Matching Problems Solvable in O(n\\^2) Time

DEFF Research Database (Denmark)

Clausen, Jens; Krarup, J.

1995-01-01

For a given, unweighted bipartite graph G with 2n non isolated vertices, we consider the so called bipartite cardinality matching problem (BCMP) for which the time complexity of the fastest exact algorithm available is O(n/sup 5/2/ ). We devise a greedy algorithm which either finds a perfect...... matching in O(n/sup 2/ ) time or identifies cycle of length 4 in the complement G of G...
Poly[[(μ4-benzene-1,3,5-tricarboxylato-κ4O1:O1′:O2:O3bis(2,2-bipyridine-κ2N,N′(μ2-hydroxidodicopper(II] trihydrate

Directory of Open Access Journals (Sweden)

Mohamed N. El-kaheli

2014-07-01

Full Text Available In the title two-dimensional coordination polymer, {[Cu2(C9H3O6(OH(C10H8N22]·3H2O}n, each of the two independent CuII atoms is coordinated by a bridging OH group, two O atoms from two benzene-1,3,5-tricarboxylate (L ligands and two N atoms from a 2,2- bipyridine (bipy ligand in a distorted square-pyramidal geometry. Each L ligand coordinates four CuII atoms, thus forming a polymeric layer parallel to the bc plane with bipy molecules protruding up and down. The lattice water molecules involved in O—H...· O hydrogen bonding are situated in the inner part of each layer. The crystal packing is consolidated by π–π interactions between the aromatic rings of bipy ligands from neigbouring layers [intercentroid distance = 3.762 (3 Å].
Hydrogen bonded networks in formamide [HCONH2]n (n = 1 – 10 ...

Indian Academy of Sciences (India)

gns

Table S1: Comparison of interaction energy (I.E) in kcal/mol in four arrangements of formamide n=1-10 at B3LYP/D95** level of theory. n = #monomers. Table S2: O---H bond length (in Å) for formamide clusters n = (2-10). Table S3: N-H bond stretching frequency (in cm-1) for four arrangements of formamide clusters n.
Probing the Electronic Structure and Band Gap Evolution of Titanium Oxide Clusters (TiO2)n- (n=1-10) Using Photoelectron Spectroscopy

International Nuclear Information System (INIS)

Zhai, Hua-jin; Wang, Lai S.

2007-01-01

TiO2 is a wide-band gap semiconductor and it is an important material for photocatalysis. Here we report an experimental investigation of the electronic structure of (TiO2)n clusters and how their band gap evolves as a function of size using anion photoelectron spectroscopy (PES). PES spectra of (TiO2)n- clusters for n = 1-10 have been obtained at 193 (6.424 eV) and 157 nm (7.866 eV). The high photon energy at 157 nm allows the band gap of the TiO2 clusters to be clearly revealed up to n = 10. The band gap is observed to be strongly size-dependent for n 1 appears to be localized in a tricoordinated Ti atom, creating a single Ti3+ site and making these clusters ideal molecular models for mechanistic understanding of TiO2 surface defects and photocatalytic properties
Enhanced performance of dye-sensitized solar cells based on organic dopant incorporated PVDF-HFP/PEO polymer blend electrolyte with g-C{sub 3}N{sub 4}/TiO{sub 2} photoanode

Energy Technology Data Exchange (ETDEWEB)

Senthil, R.A.; Theerthagiri, J. [Solar Energy Lab, Department of Chemistry, Thiruvalluvar University, Vellore 632115 (India); Madhavan, J., E-mail: jagan.madhavan@gmail.com [Solar Energy Lab, Department of Chemistry, Thiruvalluvar University, Vellore 632115 (India); Murugan, K. [Department of Zoology, Bharathiar University, Coimbatore 641046 (India); Arunachalam, Prabhakarn [Electrochemistry Research Group, Chemistry Department, College of Science, King Saud University, Riyadh 11451 (Saudi Arabia); Arof, A.K. [Centre for Ionics University Malaya, Department of Physics, University of Malaya, Kuala Lumpur 50603 (Malaysia)

2016-10-15

This work describes the effect of 2-aminopyrimidine (2-APY) on poly(vinylidinefluoride-co-hexafluoropropylene) (PVDF-HFP)/polyethylene oxide (PEO) blend polymer electrolyte along with binary iodide salts (tetrabutylammonium iodide (TBAI) and potassium iodide (KI)) and iodine (I{sub 2}) were studied for enhancing the efficiency of the dye-sensitized solar cells (DSSCs) consisting of g-C{sub 3}N{sub 4}/TiO{sub 2} composite as photoanode. The g-C{sub 3}N{sub 4} was synthesized from low cost urea by thermal condensation method. It was used as a precursor to synthesize the various weight percentage ratios (5%, 10% and 15%) of g-C{sub 3}N{sub 4}/TiO{sub 2} composites by wet-impregnation method. The pure and 2-APY incorporated PVDF-HFP/PEO polymer blend electrolytes were arranged by wet chemical process (casting method) using DMF as a solvent. The synthesized g-C{sub 3}N{sub 4}/TiO{sub 2} composites and polymer blend electrolytes were studied and analyzed by Fourier transform infrared (FT-IR) spectroscopy, X-ray diffractometer (XRD) and scanning electron microscopy (SEM). The ionic conductivity values of the pure and 2-APY incorporated PVDF-HFP/PEO blend electrolytes were estimated to be 4.53×10{sup −5} and 1.87×10{sup −4} Scm{sup −1} respectively. The UV–vis absorption spectroscopy was carried out for the pure and different wt% of g-C{sub 3}N{sub 4}/TiO{sub 2} composites coated FTO films after N3 dye-sensitization. The 10 wt% g-C{sub 3}N{sub 4}/TiO{sub 2} composite film showed a maximum absorption compared to the others. The DSSC assembled with 10 wt% g-C{sub 3}N{sub 4}/TiO{sub 2} as photoanode using the pure polymer blend electrolyte exhibited a power conversion efficiency (PCE) of 3.17% , which was superior than that of DSSC based pure TiO{sub 2} (2.46%). However, the PCE was increased to 4.73% for the DSSC assembled using 10 wt% g-C{sub 3}N{sub 4}/TiO{sub 2} as photoanode with 2-APY incorporated polymer blend electrolyte. Hence, the present study is a
Closed-loop 15N measurement of N2O and its isotopomers for real-time greenhouse gas tracing

Science.gov (United States)

Slaets, Johanna; Mayr, Leopold; Heiling, Maria; Zaman, Mohammad; Resch, Christian; Weltin, Georg; Gruber, Roman; Dercon, Gerd

2016-04-01

Quantifying sources of nitrous oxide is essential to improve understanding of the global N cycle and to develop climate-smart agriculture, as N2O has a global warming potential 300 times higher than CO2. The isotopic signature and the intramolecular distribution (site preference) of 15N are powerful tools to trace N2O, but the application of these methods is limited as conventional methods cannot provide continuous and in situ data. Here we present a method for closed-loop, real time monitoring of the N2O flux, the isotopic signature and the intramolecular distribution of 15N by using off-axis integrated cavity output spectroscopy (ICOS, Los Gatos Research). The developed method was applied to a fertilizer inhibitor experiment, in which N2O emissions were measured on undisturbed soil cores for three weeks. The treatments consisted of enriched urea-N (100 kg urea-N/ha), the same fertilizer combined with the nitrification inhibitor nitrapyrin (375 g/100 kg urea), and control cores. Monitoring the isotopic signature makes it possible to distinguish emissions from soil and fertilizer. Characterization of site preference could additionally provide a tool to identify different microbial processes leading to N2O emissions. Furthermore, the closed-loop approach enables direct measurement on site and does not require removal of CO2 and H2O. Results showed that 75% of total N2O emissions (total=11 346 μg N2O-N/m2) in the fertilized cores originated from fertilizer, while only 55% of total emissions (total=2 450 μg N2ON/m2) stemmed from fertilizer for the cores treated with nitrapyrin. In the controls, N2O derived from soil was only 40% of the size of the corresponding pool from the fertilized cores, pointing towards a priming effect on the microbial community from the fertilizer and demonstrating the bias that could be introduced by relying on non-treated cores to estimate soil emission rates, rather than using the isotopic signature. The site preference increased linearly
Emissions of N2O from peat soils under different cropping systems

Science.gov (United States)

Norberg, Lisbet; Berglund, Örjan; Berglund, Kerstin

2016-04-01

Drainage of peatlands for agriculture use leads to an increase in nitrogen turnover rate causing emissions of N2O to the atmosphere. Agriculture contributes to a substantial part of the anthropogenic emissions of N2O therefore mitigation options for the farmers are important. Here we present a field study with the aim to investigate if the choice of cropping system can mitigate the emission of N2O from cultivated organic soils. The sites used in the study represent fen peat soils with a range of different soil properties located in different parts of southern Sweden. All sites are on active farms with good drainage. N2O emissions from the soil under two different crops grown on the same field, with the same soil type, drainage intensity and weather conditions, are compared by gas sampling. The crops included are oat, barley, carrot, potato and grassland. Three or four sampling occasions during the growing season in 2010 were carried out with static chambers. The N2O emission is calculated from the linear increase of gas concentration in the chamber headspace during the incubation time of 40 minutes. Parallel to the gas sampling soil temperature and soil moisture are measured and some soil properties determined. The result from the gas sampling and measurements show no significant difference in seasonal average N2O emission between the compared crops at any site. There are significant differences in N2O emissions between the compared crops at some of the single sampling occasions but the result vary and no crop can be pointed out as a mitigation option. The seasonal average N2O emissions varies from 16±17 to 1319±1971 μg N2O/m2/h with peaks up to 3317 μg N2O/m2/h. The N2O emission rate from peat soils are determined by other factors than the type of crops grown on the field. The emission rates vary during the season and especially between sites. Although all sites are fen peat soil the soil properties are different, e.g. carbon content varies between 27-43% and
Elu kui näitemäng / Helju Koger

Index Scriptorium Estoniae

Koger, Helju, 1943-

2007-01-01

VI kihelkonnapäevadest Juurus. Juuru Mihkli kirikus esines ansambel Resonabilis. Konverentsil räägiti Järlepa mõisast, Anu Allikvee pidas ettekande "August von Kotzebue elu nagu näitemäng" jm. Näitemängu "Pärmi Jaagu unenägu" nägi kohalike asjaarmastajate esituses
Explaining the doubling of N2 O emissions under elevated CO2 in the Giessen FACE via in-field 15 N tracing.

Science.gov (United States)

Moser, Gerald; Gorenflo, André; Brenzinger, Kristof; Keidel, Lisa; Braker, Gesche; Marhan, Sven; Clough, Tim J; Müller, Christoph

2018-03-23

Rising atmospheric CO 2 concentrations are expected to increase nitrous oxide (N 2 O) emissions from soils via changes in microbial nitrogen (N) transformations. Several studies have shown that N 2 O emission increases under elevated atmospheric CO 2 (eCO 2 ), but the underlying processes are not yet fully understood. Here, we present results showing changes in soil N transformation dynamics from the Giessen Free Air CO 2 Enrichment (GiFACE): a permanent grassland that has been exposed to eCO 2 , +20% relative to ambient concentrations (aCO 2 ), for 15 years. We applied in the field an ammonium-nitrate fertilizer solution, in which either ammonium (NH4+) or nitrate (NO3-) was labelled with 15 N. The simultaneous gross N transformation rates were analysed with a 15 N tracing model and a solver method. The results confirmed that after 15 years of eCO 2 the N 2 O emissions under eCO 2 were still more than twofold higher than under aCO 2 . The tracing model results indicated that plant uptake of NH4+ did not differ between treatments, but uptake of NO3- was significantly reduced under eCO 2 . However, the NH4+ and NO3- availability increased slightly under eCO 2 . The N 2 O isotopic signature indicated that under eCO 2 the sources of the additional emissions, 8,407 μg N 2 O-N/m 2 during the first 58 days after labelling, were associated with NO3- reduction (+2.0%), NH4+ oxidation (+11.1%) and organic N oxidation (+86.9%). We presume that increased plant growth and root exudation under eCO 2 provided an additional source of bioavailable supply of energy that triggered as a priming effect the stimulation of microbial soil organic matter (SOM) mineralization and fostered the activity of the bacterial nitrite reductase. The resulting increase in incomplete denitrification and therefore an increased N 2 O:N 2 emission ratio, explains the doubling of N 2 O emissions. If this occurs over a wide area of grasslands in the future, this positive feedback reaction may
Octaakis(4-aminopyridine)-1κ4 N 1,2κ4 N 1-aqua-2κO-μ-carbonato-1:2κ3 O,O′:O′′-dinickel(II) dichloride pentahydrate

Science.gov (United States)

Fun, Hoong-Kun; Sinthiya, A; Jebas, Samuel Robinson; Ravindran Durai Nayagam, B.; Alfred Cecil Raj, S.

2008-01-01

In the title compound, [Ni2(CO3)(C5H6N2)8(H2O)]Cl2·5H2O, one of the the NiII ions is six-coordinated in a distorted octahedral geometry, with the equatorial plane defined by four pyridine N atoms from four aminopyridine ligands, the axial positions being occupied by one water O and a carbonate O atom. The other NiII ion is also six-coordinated, by four other pyridine N atoms from four other aminopyridine ligands and two carbonate O atoms to complete a distorted octahedral geometry. In the crystal structure, molecules are linked into an infinite three-dimensional network by O—H⋯O, N—H⋯Cl, N—H⋯O, O—H⋯N, C—H⋯O, C—H⋯N and C/N—H⋯π interactions involving the pyridine rings. PMID:21580879
A new series of oxycarbonate superconductors (Cu{sub 0.5}C{sub 0.5}){sub m}Ba{sub m+1}Ca{sub n-1}Cu{sub n}O{sub 2}({sub m+n})+1

Energy Technology Data Exchange (ETDEWEB)

Takayama-Muromachi, E.; Kawashima, T.; Matsui, Y. [National Institute for Research in Inorganic Materials, Ibaraki (Japan)

1994-12-31

We found a new series of oxycarbonate superconductors in the Ba-Ca-Cu-C-O system under high pressure of 5 GPa. Their ideal formula is (Cu{sub 0.5}C{sub 0.5}){sub m}Ba{sub m+1}Ca{sub n-1}Cu{sub n}O{sub 2}({sub m+n})+1 ((Cu,C)-m(m+1)(n-1)n). Thus far, n=3, 4 members of the m=1 series, (Cu,C)-1223 and (Cu,C)-1234, have been prepared in bulk while n=4, 5 members, (Cu,C)-2334 and (Cu,C)-2345, have been prepared for the m=2 series. (Cu,C)-1223 shows superconductivity below 67 K while T{sub c}`s of other compounds are above 110 K. In particular, (Cu,C)=1234 has the highest T{sub c} of 117 K.
The diversity of the N2O reducers matters for the N2O:N2 denitrification end-product ratio across an annual and a perennial cropping system.

Science.gov (United States)

Domeignoz-Horta, Luiz A; Spor, Aymé; Bru, David; Breuil, Marie-Christine; Bizouard, Florian; Léonard, Joël; Philippot, Laurent

2015-01-01

Agriculture is the main source of terrestrial emissions of N2O, a potent greenhouse gas and the main cause of ozone layer depletion. The reduction of N2O into N2 by microorganisms carrying the nitrous oxide reductase gene (nosZ) is the only biological process known to eliminate this greenhouse gas. Recent studies showed that a previously unknown clade of N2O-reducers was related to the capacity of the soil to act as an N2O sink, opening the way for new strategies to mitigate emissions. Here, we investigated whether the agricultural practices could differently influence the two N2O reducer clades with consequences for denitrification end-products. The abundance of N2O-reducers and producers was quantified by real-time PCR, and the diversity of both nosZ clades was determined by 454 pyrosequencing. Potential N2O production and potential denitrification activity were used to calculate the denitrification gaseous end-product ratio. Overall, the results showed limited differences between management practices but there were significant differences between cropping systems in both the abundance and structure of the nosZII community, as well as in the [rN2O/r(N2O+N2)] ratio. More limited differences were observed in the nosZI community, suggesting that the newly identified nosZII clade is more sensitive than nosZI to environmental changes. Potential denitrification activity and potential N2O production were explained mainly by the soil properties while the diversity of the nosZII clade on its own explained 26% of the denitrification end-product ratio, which highlights the importance of understanding the ecology of this newly identified clade of N2O reducers for mitigation strategies.
Propuesta de clasificación técnica de los sistemas de explotación de las BN1G de producción (núcleos

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Nuria Castañeda Clemente

1999-01-01

Full Text Available Se propone una clasificación de los sistemas de explotación de las BN1G de producción a partir de las relaciones entre los distintos atributos que caracterizan a los núcleos. Esta clasificación se estructura en tres niveles. El primero discrimina los sistemas de explotación según su número de superficies de talla. En el segundo nivel, la característica jerarquizadora es la relación geométrica entre superficie /plataforma o entre superficies de talla. El tercer y último nivel atiende a la dirección en la que se explotan estas superficies. This work consists in a classification of the production BN1G (cores exploitation systems, based on tlie reiatlonsfíip between ttie different cíiaracteristic core forms features. Tfiere are tfiree levéis of classification.The first one discrimínate between exploitation systems by tlieir number of debitage surfaces. On the second level the hierarchical feature is the geomethcai relationship between the debitage surface and striking platform or between debitage surfaces. Third level is the direction on exploitation of surfaces.
N2O, NO and CH4 exchange, and microbial N turnover over a Mediterranean pine forest soil

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P. Rosenkranz

2006-01-01

Full Text Available Trace gas exchange of N2O, NO/NO2 and CH4 between soil and the atmosphere was measured in a typical Mediterranean pine (Pinus pinaster forest during two intensive field campaigns in spring and autumn 2003. Furthermore, gross and net turnover rates of N mineralization and nitrification as well as soil profiles of N2O and CH4 concentrations were determined. For both seasons a weak but significant N2O uptake from the atmosphere into the soil was observed. During the unusually dry and hot spring mean N2O uptake was −4.32 µg N m-2 h-1, whereas during the wet and mild autumn mean N2O uptake was −7.85 µg N m-2 h-1. The observed N2O uptake into the soil was linked to the very low availability of inorganic nitrogen at the study site. Organic layer gross N mineralization decreased from 5.06 mg N kg-1 SDW d-1 in springtime to 2.68 mg N kg-1 SDW d-1 in autumn. Mean NO emission rates were significantly higher in springtime (9.94 µg N m-2 h-1 than in autumn (1.43 µg N m-2 h-1. A significant positive correlation between NO emission rates and gross N mineralization as well as nitrification rates was found. The negative correlation between NO emissions and soil moisture was explained with a stimulation of aerobic NO uptake under N limiting conditions. Since NO2 deposition was continuously higher than NO emission rates the examined forest soil functioned as a net NOx sink. Observed mean net CH4 uptake rates were in spring significantly higher (−73.34 µg C m-2 h-1 than in autumn (−59.67 µg C m-2 h-1. Changes in CH4 uptake rates were strongly negatively correlated with changes in soil moisture. The N2O and CH4 concentrations in different soil depths revealed the organic layer and the upper 0.1 m of mineral soil as the most important soil horizons for N2O and CH4 consumption.
Structural and spectral analyses of N,N'-(2,2'-dithiodi-o-phenylene)bis-(furan-2-carboxamide)

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Yıldırım, Sema Öztürk; Büyükmumcu, Zeki; Pekdur, Özlem Savaş; Butcher, Ray J.; Doǧan, Şengül Dilem

2018-02-01

In this study we report structure determination of N,N'-(2,2'-dithiodi-o-phenylene)bis-(furan-2-carboxamide). 2,2'-Dithiobis(benzamide) derivatives have been reported to possess important biological properties such as antibacterial, antifungal activities and inhibition of blood platelet aggregation and redeterrmined at 100(2)K from the data published by Raftery, Lallbeeharry, Bhowon, Laulloo & Joulea [Acta Cryst. 2009, E65, o16]. 2,2'-Dithiobis(N-butyl-benzamide) has been reported to be useful as an antiseptic for cosmetics. The structural properties of the compound have been characterized by using 1H NMR and the structure were determined by single-crystal X-ray diffraction. Molecular structure crystallizes in triclinic form, space group with a = 9.6396(7) Å, b = 9.9115(7) Å, c = 12.0026(8) Å, α = 109.743(6)°, β = 103.653(6)°, γ = 104.633(6)° and V = 977.15(13) Å3. In the solid state of the molecular structure N-H…S, N-H…O and C-H…O, type interactions provide for stabilization. The geometries of the title compound have been optimized using density functional theory (DFT) method. The calculated values were found to be in agreement with the experimental data.

Synthesis, characterization and crystal structure of the new pentahydrate of bis(2,2'-bipyridine-κ(2)N,N')(oxalato-κ(2)O(1),O(2))nickel(II).

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Farkašová, Nela; Cernák, Juraj; Tomás, Milagros; Falvello, Larry R

2014-05-01

The reaction of NiCl2, K2C2O4·H2O and 2,2'-bipyridine (bpy) in water-ethanol solution at 281 K yields light-purple needles of the new pentahydrate of bis(2,2'-bipyridine)oxalatonickel(II), [Ni(C2O4)(C10H8N2)2]·5H2O or [Ni(ox)(bpy)2]·5H2O, while at room temperature, deep-pink prisms of the previously reported tetrahydrate [Ni(ox)(bpy)2]·4H2O [Román, Luque, Guzmán-Miralles & Beitia (1995), Polyhedron, 14, 2863-2869] were gathered. The asymmetric unit in the crystal structure of the new pentahydrate incorporates the discrete molecular complex [Ni(ox)(bpy)2] and five solvent water molecules. Within the complex molecule, all three ligands are bonded as chelates. The complex molecules are involved in an extended system of hydrogen bonds with the solvent water molecules. Additionally, π-π interactions also contribute to the stabilization of the extended structure. The dehydration of the pentahydrate starts at 323 K and proceeds in at least two steps as determined by thermal analysis.
Modified g-C3N4/TiO2 nanosheets/ZnO ternary facet coupled heterojunction for photocatalytic degradation of p-toluenesulfonic acid (p-TSA) under visible light

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Jiang, Dong; Yu, Han; Yu, Hongbing

2017-01-01

Novel ternary nanocomposites with facet coupled structure were synthesized by using modified g-C3N4, TiO2 nanosheets and nano-ZnO. Nanosheet/nanosheet heterojunction structure was investigated by TEM, XPS and XRD. FT-IR and Nitrogen adsorption were illustrated for chemical/physical structure analyses. Solution of p-Toluenesulfonic acid (p-TSA) was chosen as target pollutant for visible light photodegradation and the excellent removal efficiency was achieved by this structurally modified g-C3N4/TiO2/ZnO hybrid. The visible light absorption improvement and quantum efficiency enhancement, which were testified by UV-vis DRS, PL and p-TSA photodegradation measurements, due to the facet coupled structure and appropriate quantity of modified g-C3N4 in the nanocomposites.
Poly[aqua-μ-bromido-(μ2-5-methylpyrazine-2-carboxylato-κ4N1,O2:O2,O2′lead(II

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Pan Yang

2012-09-01

Full Text Available In the title coordination polymer, [PbBr(C6H5N2O2(H2O]n, the PbII atom is coordinated by one pyrazine N atom, two bridging Br atoms, a water molecule and three carboxylate O atoms. Bridging by the two anions generates a layer structure parallel to (001; the layers are linked by O—H...N and O—H...Br hydrogen bonds, forming a three-dimensional network. The lone pair is stereochemically active, resulting in a Ψ-dodecahedral coordination environment for PbII.
Construction of Z-scheme Ag{sub 2}CO{sub 3}/N-doped graphene photocatalysts with enhanced visible-light photocatalytic activity by tuning the nitrogen species

Energy Technology Data Exchange (ETDEWEB)

Song, Shaoqing [State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China); Key Laboratory of Radioactive Geology and Exploration Technology Fundamental Science for National Defense, East China Institute of Technology, Nanchang, Jiangxi Province 330013 (China); Meng, Aiyun [State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China); Jiang, Shujuan [Key Laboratory of Radioactive Geology and Exploration Technology Fundamental Science for National Defense, East China Institute of Technology, Nanchang, Jiangxi Province 330013 (China); Cheng, Bei [State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China); Jiang, Chuanjia, E-mail: jiangcj2016@yahoo.com [State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China)

2017-02-28

Highlights: • Z-scheme photocatalyst composed of Ag{sub 2}CO{sub 3} and N-doped graphene (NG). • Pyridinic nitrogen species of NG spontaneously promoted plasmonic Ag formation. • Graphitic N of NG facilitated the Z-scheme transfer option and O{sub 2} adsorption. • Z-scheme Ag{sub 2}CO{sub 3}-NG showed high photocatalytic performance. - Abstract: Semiconductor-based photocatalysis has great potential in various environmental and energy applications, and Z-scheme photocatalysts have many advantages over single-component photocatalysts. The construction of a highly efficient Z-scheme photocatalytic system depends on the geometric structure arrangement, microscopic and crystalline form of the stoichiometric species, and it has not been elucidated whether the Z-scheme photocatalysts can be designed by tuning the electronic structures of cocatalysts alone. Here, using N-doped graphene (NG) as cocatalyst, we successfully constructed Z-scheme Ag{sub 2}CO{sub 3}-NG photocatalysts with enhanced activity for the photooxidative degradation of phenol pollutant. It was found that the pyridinic nitrogen species (N{sub p}) of NG could spontaneously reduce Ag{sup +} to produce plasmonic Ag nanoparticles on Ag{sub 2}CO{sub 3}-NG, while the efficiency of the photogenerated charge separation, Z-scheme transfer option, and O{sub 2} adsorption were promoted by the graphitic nitrogen species (N{sub g}). Therefore, the as-designed Z-scheme Ag{sub 2}CO{sub 3}-NG photocatalysts showed much higher activity than Ag{sub 2}CO{sub 3} and its composites with graphene oxide (GO) or reduced GO as cocatalysts in the photocatalytic degradation of phenol. Hence, our results provide a new strategy for exploring advanced Z-scheme photocatalysts with NG as cocatalyst by rationally tuning the N{sub p} and N{sub g} species.
[2-(Dimethylaminoethanol-κ2N,O][2-(dimethylaminoethanolato-κ2N,O]iodidocopper(II

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Elena A. Buvaylo

2012-04-01

Full Text Available The title compound, [Cu(C4H10NOI(C4H11NO], was obtained unintentionally as the product of an attempted synthesis of a Cu/Zn mixed-metal complex using zerovalent copper, zinc(II oxide and ammonium iodide in pure 2-(dimethylaminoethanol, in air. The molecular complex has no crystallographically imposed symmetry. The coordination geometry around the metal atom is distorted square-pyramidal. The equatorial coordination around copper involves donor atoms of the bidentate chelating 2-(dimethylaminoethanol ligand and the 2-(dimethylaminoethanolate group, which are mutually trans to each other, with four approximately equal short Cu—O/N bond distances. The axial Cu—I bond is substantially elongated. Intermolecular hydrogen-bonding interactions involving the –OH group of the neutral 2-(dimethylaminoethanol ligand to the O atom of the monodeprotonated 2-(dimethylaminoethanolate group of the molecule related by the n-glide plane, as indicated by the O...O distance of 2.482 (12 Å, form chains of molecules propagating along [101].
Bis{μ-2,2′-[1,1′-(ethane-1,2-diyldinitrilodiethylidyne]diphenolato-κ5O,N,N′,O′:O}bis[chloridomanganese(III

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Robert D. Pike

2008-02-01

Full Text Available The title compound, [Mn2(C18H18N2O22Cl2], was synthesized by the reaction between manganese(II o-chlorobenzoate and the Schiff base generated in situ by the condensation of ethane-1,2-diamine and o-hydroxyacetophenone. The centrosymmetric dimer contains two Jahn–Teller-distorted manganese(III ions, each in an octahedral geometry, connected through two phenoxy bridges from two ligands.
Production of N2O5 and ClNO2 through Nocturnal Processing of Biomass-Burning Aerosol.

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Ahern, Adam T; Goldberger, Lexie; Jahl, Lydia; Thornton, Joel; Sullivan, Ryan C

2018-01-16

Biomass burning is a source of both particulate chloride and nitrogen oxides, two important precursors for the formation of nitryl chloride (ClNO 2 ), a source of atmospheric oxidants that is poorly prescribed in atmospheric models. We investigated the ability of biomass burning to produce N 2 O 5 (g) and ClNO 2 (g) through nocturnal chemistry using authentic biomass-burning emissions in a smog chamber. There was a positive relationship between the amount of ClNO 2 formed and the total amount of particulate chloride emitted and with the chloride fraction of nonrefractory particle mass. In every fuel tested, dinitrogen pentoxide (N 2 O 5 ) formed quickly, following the addition of ozone to the smoke aerosol, and ClNO 2 (g) production promptly followed. At atmospherically relevant relative humidities, the particulate chloride in the biomass-burning aerosol was rapidly but incompletely displaced, likely by the nitric acid produced largely by the heterogeneous uptake of N 2 O 5 (g). Despite this chloride acid displacement, the biomass-burning aerosol still converted on the order of 10% of reacted N 2 O 5 (g) into ClNO 2 (g). These experiments directly confirm that biomass burning is a potentially significant source of atmospheric N 2 O 5 and ClNO 2 to the atmosphere.
A consilience model to describe N2O production during biological N removal

DEFF Research Database (Denmark)

Domingo Felez, Carlos; Smets, Barth F.

2016-01-01

Nitrous oxide (N2O), a potent greenhouse gas, is produced during biological nitrogen conversion in wastewater treatment operations. Complex mechanisms underlie N2O production by autotrophic and heterotrophic organisms, which continue to be unravelled. Mathematical models that describe nitric oxide...... (NO) and N2O dynamics have been proposed. Here, a first comprehensive model that considers all relevant NO and N2O production and consumption mechanisms is proposed. The model describes autotrophic NO production by ammonia oxidizing bacteria associated with ammonia oxidation and with nitrite reduction......, followed by NO reduction to N2O. It also considers NO and N2O as intermediates in heterotrophic denitrification in a 4-step model. Three biological NO and N2O production pathways are accounted for, improving the capabilities of existing models while not increasing their complexity. Abiotic contributions...
Crystal structure of tetraaqua[2-(pyridin-2-yl-1H-imidazole-κ2N2,N3]iron(II sulfate

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Zouaoui Setifi

2015-04-01

Full Text Available In the title compound, [Fe(C8H7N3(H2O4]SO4, the central FeII ion is octahedrally coordinated by two N atoms from the bidentate 2-(pyridin-2-yl-1H-imidazole ligand and by four O atoms of the aqua ligands. The largest deviation from the ideal octahedral geometry is reflected by the small N—Fe—N bite angle of 76.0 (1°. The Fe—N coordination bonds have markedly different lengths [2.1361 (17 and 2.243 (2 Å], with the shorter one to the pyrimidine N atom. The four Fe—O coordination bond lengths vary from 2.1191 (18 to 2.1340 (17 Å. In the crystal, the cations and anions are arranged by means of medium-strength O—H...O hydrogen bonds into layers parallel to the ab plane. Neighbouring layers further interconnect by N—H...O hydrogen bonds involving the imidazole fragment as donor group to one sulfate O atom as an acceptor. The resulting three-dimensional network is consolidated by C—H...O, C—H...π and π–π interactions.
(Dimethylformamide-κO(2-hydroxybenzoato-κ2O1,O1′[tris(1-methyl-1H-benzimidazol-2-ylmethyl-κN3amine-κN]manganese(II perchlorate dimethylformamide monosolvate

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Baoliang Qi

2010-10-01

Full Text Available In the title complex, [Mn(C7H5O3(C27H27N7(C3H7NO]ClO4·C3H7NO, the MnII ion is coordinated in a slightly distorted monocapped trigonal-prismatic geometry. The tris(1-methyl-1H-benzimidazol-2-ylmethylamine (Mentb ligand coordinates in a tetradentate mode and the coordination is completed by a bis-chelating salicylate ligand and a dimethylformamide ligand. The hydroxy group and the ortho H atoms of the salicylate ligand were refined as disordered over two sites with occupancies of 0.581 (8 and 0.419 (8. Both disorder components of the hydroxy group form intramolecular O—H...O hydrogen bonds.
Bis(2,6-dihydroxybenzoato-κ2O1,O1′(nitrato-κ2O,O′bis(1,10-phenanthroline-κ2N,N′cerium(III

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Hongxiao Jin

2011-01-01

Full Text Available The mononuclear title complex, [Ce(C7H5O32(NO3(C12H8N22], is isostructural to other related lanthanide structures. The Ce atom is in a pseudo-bicapped square-antiprismatic geometry formed by four N atoms from two chelating 1,10-phenanthroline (phen ligands and by six O atoms, four from two 2,6-dihydroxybenzoate (DHB ligands and the other two from a nitrate anion. π–π stacking interactions between phen and DHB ligands [centroid–centroid distances = 3.513 (3 and 3.762 (2 Å] and phen and phen ligands [face-to-face separation = 3.423 (7 Å] of adjacent complexes stabilize the crystal structure. Intramolecular O—H...O hydrogen bonds are observed in the DHB ligands.
Fabrication of Heterostructured g-C{sub 3}N{sub 4}/Ag-TiO{sub 2} Hybrid Photocatalyst with Enhanced Performance in Photocatalytic Conversion of CO{sub 2} Under Simulated Sunlight Irradiation

Energy Technology Data Exchange (ETDEWEB)

Li, Hailong [School of Energy Science and Engineering, Central South University, Changsha, 410083 (China); Department of Civil Engineering, The University of Hong Kong, Hong Kong Special Administrative Region (Hong Kong); Gao, Yan; Wu, Xianying [School of Energy Science and Engineering, Central South University, Changsha, 410083 (China); Lee, Po-Heng [Department of Civil & Environmental Engineering, The Hong Kong Polytechnic University, Hong Kong Special Administrative Region (Hong Kong); Shih, Kaimin, E-mail: kshih@hku.hk [Department of Civil Engineering, The University of Hong Kong, Hong Kong Special Administrative Region (Hong Kong)

2017-04-30

Highlights: • Combination of g-C{sub 3}N{sub 4} and Ag-TiO{sub 2} resulted in significant synergy for CO{sub 2} reduction. • The optimal electron consumption rate for CN/AgTi was 12.7 times higher than that for TiO{sub 2}. • CN/AgTi was superior than g-C{sub 3}N{sub 4} and Ag-TiO{sub 2} in use of sunlight for CO{sub 2} conversion. - Abstract: Heterostructured g-C{sub 3}N{sub 4}/Ag-TiO{sub 2} (CN/AgTi) hybrid catalysts were fabricated through a facile solvent evaporation followed by a calcination process, using graphitic carbon nitride (g-C{sub 3}N{sub 4}) and Ag-TiO{sub 2} (AgTi) as precursors. The phase compositions, optical properties, and morphologies of the catalysts were systematically characterized. The heterostructured combination of g-C{sub 3}N{sub 4}, titania (TiO{sub 2}) and silver nanoparticles (Ag NPs) resulted in significant synergy for catalytic conversion of CO{sub 2} in the presence of water vapor under simulated sunlight irradiation. The optimal CN/AgTi composite with a g-C{sub 3}N{sub 4} to AgTi mass ratio of 8% exhibited the maximum CO{sub 2} photoreduction activity, achieving a CO{sub 2} conversion of 47 μmol, CH{sub 4} yield of 28 μmol, and CO yield of 19 μmol per gram of catalyst during a 3 h simulated sunlight irradiation. Under the experimental conditions, the rate of electron consumption was calculated to be 87.3 μmol/g·h, which was 12.7 times, 7.9 times, and 2.0 times higher than those for TiO{sub 2}, g-C{sub 3}N{sub 4} and AgTi, respectively. The combination of g-C{sub 3}N{sub 4} and AgTi resulted in more sunlight harvesting for electron and hole generations. Photoinduced electrons transferred through the heterjunction between g-C{sub 3}N{sub 4} and TiO{sub 2}, and further from TiO{sub 2} to Ag NPs with lower Fermi level greatly suppressed the recombination of electron-hole pairs, and hence resulted in electron accumulation on Ag NPs deposited on the TiO{sub 2} surface in the CN/AgTi. Abundant electrons accumulated on the Ag
Crystal structure of diaquabis(N,N-diethylnicotinamide-κN1bis(2,4,6-trimethylbenzoato-κO1cobalt(II

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Gülçin Şefiye Aşkın

2016-04-01

Full Text Available The centrosymmetric molecule in the monomeric title cobalt complex, [Co(C10H11O22(C10H14N2O2(H2O2], contains two water molecules, two 2,4,6-trimethylbenzoate (TMB ligands and two diethylnicotinamide (DENA ligands. All ligands coordinate to the CoII atom in a monodentate fashion. The four O atoms around the CoII atom form a slightly distorted square-planar arrangement, with the distorted octahedral coordination sphere completed by two pyridine N atoms of the DENA ligands. The dihedral angle between the planar carboxylate group and the adjacent benzene ring is 84.2 (4°, while the benzene and pyridine rings are oriented at a dihedral angle of 38.87 (10°. The water molecules exhibit both intramolecular (to the non-coordinating carboxylate O atom and intermolecular (to the amide carbonyl O atom O—H...O hydrogen bonds. The latter lead to the formation of layers parallel to (100, enclosing R44(32 ring motifs. These layers are further linked via weak C—H...O hydrogen bonds, resulting in a three-dimensional network. One of the two ethyl groups of the DENA ligand is disordered over two sets of sites with an occupancy ratio of 0.490 (13:0.510 (13.
Crystal and Molecular Structure of Bis(2,2-diphenyl-N-(di-n-propylcarbamothioyl acetamidocopper(II Complex

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Hakan Arslan

2011-01-01

Full Text Available Bis(2,2-diphenyl-N-(di-n-propylcarbamothioyl acetamidocopper(II complex has been synthesized and characterized by elemental analysis and FT-IR spectroscopy. The crystal and molecular structure of the title compound has been determined from single crystal X-ray diffraction data. It crystallizes in the triclinic space group P-1, with a = 13.046(2 Å, b = 13.135(2 Å, c = 13.179(2 Å, α= 67.083(4°, β= 67.968(4°, γ = 84.756(4° and Dcalc =1.330 g/cm3 for Z = 2. The crystal structure confirms that the complex is a mononuclear copper(II complex and the 2,2-diphenyl-N-(di-n-propyl-carbamothioylacetamide ligand is a bidentate chelating ligand, coordinating to the copper atom through the thiocarbonyl and carbonyl groups. This coordination has a slightly distorted square-planar geometry (O1-Cu1-O2: 86.48(11°, O1-Cu1-S1: 93.85(9°, O2-Cu1-S2: 94.20(9° and S1-Cu1-S2: 91.21(4°. The title molecule shows a cis-arrangement and C–O, C–S and C–N bond lengths of the complex suggest considerable electronic delocalization in the chelate rings.
Ab initio electron correlated studies on the intracluster reaction of NO+ (H2O)(n) → H3O+ (H2O)(n-2) (HONO) (n = 4 and 5).

Science.gov (United States)

Asada, Toshio; Nagaoka, Masataka; Koseki, Shiro

2011-01-28

Hydrated nitrosonium ion clusters NO(+)(H(2)O)(n) (n = 4 and 5) were investigated by using MP2/aug-cc-pVTZ level of theory to clarify isomeric reaction pathways for formation of HONO and fully hydrated hydride ions. We found some new isomers and transition state structures in each hydration number, whose lowest activation energies of the intracluster reactions were found to be 4.1 and 3.4 kcal mol(-1) for n = 4 and n = 5, respectively. These thermodynamic properties and full quantum mechanical molecular dynamics simulation suggest that product isomers with HONO and fully hydrated hydride ions can be obtained at n = 4 and n = 5 in terms of excess hydration binding energies which can overcome these activation barriers.
Zoledronate complexes. III. Two zoledronate complexes with alkaline earth metals: [Mg(C(5)H(9)N(2)O(7)P(2))(2)(H(2)O)(2)] and [Ca(C(5)H(8)N(2)O(7)P(2))(H(2)O)](n).

Science.gov (United States)

Freire, Eleonora; Vega, Daniel R; Baggio, Ricardo

2010-06-01

Diaquabis[dihydrogen 1-hydroxy-2-(imidazol-3-ium-1-yl)ethylidene-1,1-diphosphonato-kappa(2)O,O']magnesium(II), [Mg(C(5)H(9)N(2)O(7)P(2))(2)(H(2)O)(2)], consists of isolated dimeric units built up around an inversion centre and tightly interconnected by hydrogen bonding. The Mg(II) cation resides at the symmetry centre, surrounded in a rather regular octahedral geometry by two chelating zwitterionic zoledronate(1-) [or dihydrogen 1-hydroxy-2-(imidazol-3-ium-1-yl)ethylidene-1,1-diphosphonate] anions and two water molecules, in a pattern already found in a few reported isologues where the anion is bound to transition metals (Co, Zn and Ni). catena-Poly[[aquacalcium(II)]-mu(3)-[hydrogen 1-hydroxy-2-(imidazol-3-ium-1-yl)ethylidene-1,1-diphosphonato]-kappa(5)O:O,O':O',O''], [Ca(C(5)H(8)N(2)O(7)P(2))(H(2)O)](n), consists instead of a Ca(II) cation in a general position, a zwitterionic zoledronate(2-) anion and a coordinated water molecule. The geometry around the Ca(II) atom, provided by six bisphosphonate O atoms and one water ligand, is that of a pentagonal bipyramid with the Ca(II) atom displaced by 0.19 A out of the equatorial plane. These Ca(II) coordination polyhedra are ;threaded' by the 2(1) axis so that successive polyhedra share edges of their pentagonal basal planes. This results in a strongly coupled rhomboidal Ca(2)-O(2) chain which runs along [010]. These chains are in turn linked by an apical O atom from a -PO(3) group in a neighbouring chain. This O-atom, shared between chains, generates strong covalently bonded planar arrays parallel to (100). Finally, these sheets are linked by hydrogen bonds into a three-dimensional structure. Owing to the extreme affinity of zoledronic acid for bone tissue, in general, and with calcium as one of the major constituents of bone, it is expected that this structure will be useful in modelling some of the biologically interesting processes in which the drug takes part.
Controlling factors of nitrous oxide (N2O) emissions at the field-scale in an agricultural slope

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Vilain, Guillaume; Garnier, Josette; Tallec, Gaëlle; Tournebize, Julien; Cellier, Pierre; Flipo, Nicolas

2010-05-01

short period of one month. Landscape position strongly affected cumulative N2O emissions which were more than three times higher in footslope position (annual budget of 4 kg N-N2O ha-1 yr-1) than in shoulder (1.1 kg N-N2O ha-1 yr-1) or slope positions (1.1 and 1.2 kg N-N2O ha-1 yr-1), where soil water contents were higher (mean 68.4% WFPS in footslope position whereas mean WFPS were 50.4 and 60.5% in slope positions and 58% in shoulder position). N2O emissions were relatively low (0.5 kg N-N2O ha-1 yr-1) and did not show much annual variation in unfertilized riparian buffer. Garnier, J., Billen, G., Vilain, G., Martinez, A., Silvestre, M., Mounier, E., & Toche, F., 2009. Nitrous oxide (N2O) in the Seine river and basin: Observations and budgets. Agriculture, Ecosystems & Environment 133, 223-233. IPCC, 2007. Climate change 2007: the physical science basis. Summary for Policy Makers, Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Izaurralde, R. C., Lemke, R. L., Goddard, T. W., McConkey, B., & Zhang, Z., 2004. Nitrous Oxide Emissions from Agricultural Toposequences in Alberta and Saskatchewan. Soil Sci Soc Am J 68, 1285-1294.
The pH dependency of N-converting enzymatic processes, pathways and microbes: effect on net N₂O production

DEFF Research Database (Denmark)

Blum, Jan-Michael; Su, Qingxian; Ma, Yunjie

2018-01-01

causing steric changes in catalytic sites or proton/electron transfer routes that alter the enzymes' overall activity. Augmenting molecular information with, e.g., nitritation or denitrification rates yields explanations of changes in net N2 O production with pH. Ammonia oxidizing bacteria are of highest...... relevance for N2 O production, while heterotrophic denitrifiers are relevant for N2 O consumption at pH > 7.5. Net N2 O production in N-cycling water engineering systems is predicted to display a 'bell-shaped' curve in the range of pH 6.0-9.0 with a maximum at pH 7.0-7.5. Net N2 O production at acidic p...
Accelerated Rates of Nitrogen Cycling and N2O Production in Salt Marsh Sediments due to Long-Term Fertilization

Science.gov (United States)

Peng, X.; Ji, Q.; Angell, J.; Kearns, P.; Bowen, J. L.; Ward, B. B.

2014-12-01

Intensified sedimentary production of nitrous oxide (N2O), one of the most potent greenhouse gases, is one of the many possible environmental consequences of elevated nitrogen (N) loading into estuarine ecosystems. This study investigates the response to over 40 years of fertilization of nitrogen removal processes in the sediments of the Great Sippewissett Marsh in Falmouth, MA. Sediment slurries were incubated (1.5 hr) with trace amounts (fertilized sediments (0.89 nmol hr-1 g-1 wet weight) was 30-fold higher than in unfertilized sediments. The ratio of N2O to N2 production was also significantly higher in fertilized sediments (2.9%) than in unfertilized sediments (1.2%). This highlights the disproportionally large effect of long-term fertilization on N2O production in salt marsh sediments. The reduced oxygen level and higher ammonium concentrations in situ probably contributed to the significant rise in N2O production as a result of long-term fertilization. When detected, anammox and coupled nitrification-denitrification accounted for 10% and 14% of the total N2 production in fertilized sediments (30.5 nmol hr-1 g-1 wet weight), respectively, whereas neither was detected in unfertilized sediments. Thus these experiments indicate that N loading has important effects on multiple N cycle processes that result in N loss and N2O production.
[μ-1,1′-(Butane-1,4-diyldi-1H-benzimidazole-κ2N3:N3′]bis{[N,N′-bis(carboxymethylethylenediamine-N,N′-diacetato-κ5O,O′,O′′,N,N′]mercury(II} methanol disolvate

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Gang-Sen Li

2009-08-01

Full Text Available The binuclear title complex, [Hg2(C10H14N2O82(C18H18N4]·2CH3OH, lies on an inversion center with the unique HgII ion coordinated in a disorted octahedral environment with one Hg—N bond significantly shorter than the other two. In the crystal structure, intermolecular O—H...O hydrogen bonds link complex and solvent molecules into a three-dimensional network.

Effects of N2-O2 and CO2-O2 Tensions on Growth of Fungi Isolated from Damaged Flue-Cured Tobacco 1

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Yang, H.; Lucas, G. B.

1970-01-01

Ten fungi, Aspergillus niger, A. flavus, A. ochraceus, A. ruber, A. repens, A. amstelodami, Alternaria tenuis, Penicillium brevi-compactum, Cladosporium herbarum, and Chaetomium dolicotrichum, were isolated from moldy flue-cured tobacco and grown in various mixtures of N2-O2 or CO2-O2. A 1 to 5% concentration of O2 in an N2 atmosphere caused the greatest change in growth of the nine species, and a 10 to 20% concentration of O2 for A. flavus. All species, except A. amstelodami and A. ruber, grew faster in air than in mixtures containing 10% O2. High O2 concentrations generally inhibited furrow production in the mycelial mats. In an atmosphere of 5 to 40% O2 in the N2 atmosphere, furrows formed in mycelial mats between 5 and 40% O2 in the species except for A. ruber, A. repens, and A. amstelodami, which produced none in any concentration. As O2 decreased below 20%, spore production was progressively decreased, colony color faded to white, and cleistothecia formation was suppressed. In CO2-O2 mixtures radial growth of all species increased with each quantitative decrease of CO2. All species except A. niger grew faster in air than in 10% CO2. In contrast to N2-O2 mixtures, the fungi formed furrows, sporulation and cleistothecial formation were suppressed, and colony color changed to white in higher O2 concentrations. PMID:5461786
[(Nitrato-κ2 O,O′)(nitrito-κ2 O,O′)(0.25/1.75)]bis(1,10-phenanthroline-κ2 N,N′)cadmium(II)

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Najafi, Ezzatollah; Amini, Mostafa M.; Ng, Seik Weng

2011-01-01

The reaction of cadmium nitrate and sodium nitrite in the presence of 1,10-phenanthroline yields the mixed nitrate–nitrite title complex, [Cd(NO2)1.75(NO3)0.25(C12H8N2)2]. The metal ion is bis-chelated by two N-heterocycles as well as by the nitrate/nitrite ions in a distorted dodecahedral CdN4O4 coordination environment. One nitrite group is ordered; the other is disordered with respect to a nitrate group (ratio 0.75:0.25) concerning the O atom that is not involved in bonding to the metal ion. PMID:21522904
Temporal trends in N2O flux dynamics in a Danish wetland – effects of plant-mediated gas transport of N2O and O2 following changes in water level and soil mineral-N availability

DEFF Research Database (Denmark)

Jørgensen, Christian Juncher; Struwe, Sten; Elberling, Bo

2012-01-01

in subsurface N2O and O2 concentrations, water level (WL), light intensity as well as mineral-N availability. Weekly concentration profiles showed that seasonal variations in N2O concentrations were directly linked to the position of the WL and O2 availability at the capillary fringe above the WL. N2O flux....... Complex interactions between seasonal changes in O2 and mineral-N availability following near-surface WL fluctuations in combination with plant-mediated gas transport by P. arundinacea controlled the subsurface N2O concentrations and gas transport mechanisms responsible for N2O fluxes across the soil......–atmosphere interface. Results demonstrate the necessity for addressing this high temporal variability and potential plant transport of N2O in future studies of net N2O exchange across the soil–atmosphere interface....
[Characteristics of N2, N2O, NO, CO2 and CH4 Emissions in Anaerobic Condition from Sandy Loam Paddy Soil].

Science.gov (United States)

Cao, Na; Wang, Rui; Liao, Ting-ting; Chen, Nuo; Zheng, Xun-hua; Yao, Zhi-sheng; Zhang, Hai; Butterbach-Bahl, Klaus

2015-09-01

Understanding the characteristics of the production of nitrogen gases (N2, N2O and NO), CO2 and CH4 in anaerobic paddy soils is not only a prerequisite for an improved mechanistic understanding of key microbial processes involved in the production of atmospheric greenhouse gases (GHG), but might also provide the basis for designing greenhouse gas mitigation strategies. Moreover, quantifying the composition fractions of denitrification gaseous products is of key importance for improving parameterization schemes of microbial processes in process-oriented models which are increasingly used for assessing soil GHG emissions at site and national scales. In our experiments we investigated two sandy loam soils from two paddy fields. The initial concentrations of soil nitrate and dissolved organic carbon (DOC) were set at approximately 50 mg.kg-1 and mg.kg-1, respectively, by adding a mixture solution of KNO3 and glucose. The emissions of N2, N2O NO, CO2 and CH4, as well as concentrations of carbon and nitrogen substrates for each soil sample were measured simultaneously, using a gas-flow-soil-core technique and a paralleling substrate monitoring system. The results showed that the accumulative emissions of N2, N2O and NO of the two soil samples for the entire incubation period were 6 - 8, 20, and 15 - 18 mg.kg-1, respectively. By measuring the cumulative emissions of denitrification gases (N, = N2 + N2O + NO) we were able to explain 95% to 98% of observed changes in s1ifr nilrate concentrations. The mass fractions of N2, N2O and NO emissions to Nt were approximately 15% -19%, 47% -49%, and 34% -36%, respectively. Thus, in our experiments N2O and NO were the main products of denitrification for the entire incubation period. However, as the temporal courses of hourly or daily production of the denitrification gases showed, NO production dominated and peaked firstly, and then N2O, before finally N2 became the dominant product. Our results show the high temporal dynamic of
Effects of dicyandiamide and dolomite application on N2O emission from an acidic soil.

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Shaaban, Muhammad; Wu, Yupeng; Peng, Qi-an; Lin, Shan; Mo, Yongliang; Wu, Lei; Hu, Ronggui; Zhou, Wei

2016-04-01

Soil acidification is a major problem for sustainable agriculture since it limits productivity of several crops. Liming is usually adopted to ameliorate soil acidity that can trigger soil processes such as nitrification, denitrification, and loss of nitrogen (N) as nitrous oxide (N2O) emissions. The loss of N following liming of acidic soils can be controlled by nitrification inhibitors (such as dicyandiamide). However, effects of nitrification inhibitors following liming of acidic soils are not well understood so far. Here, we conducted a laboratory study using an acidic soil to examine the effects of dolomite and dicyandiamide (DCD) application on N2O emissions. Three levels of DCD (0, 10, and 20 mg kg(-1); DCD0, DCD10, and DCD20, respectively) were applied to the acidic soil under two levels of dolomite (0 and 1 g kg(-1)) which were further treated with two levels of N fertilizer (0 and 200 mg N kg(-1)). Results showed that N2O emissions were highest at low soil pH levels in fertilizer-treated soil without application of DCD and dolomite. Application of DCD and dolomite significantly (P ≤ 0.001) reduced N2O emissions through decreasing rates of NH4 (+)-N oxidation and increasing soil pH, respectively. Total N2O emissions were reduced by 44 and 13% in DCD20 and dolomite alone treatments, respectively, while DCD20 + dolomite reduced N2O emissions by 54% when compared with DCD0 treatment. The present study suggests that application of DCD and dolomite to acidic soils can mitigate N2O emissions.
Hexaaquabis[3,5-bis(hydroxyimino-1-methyl-2,4,6-trioxocyclohexanido-κ2N3,O4]barium tetrahydrate

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Nguyen Dinh Do

2013-11-01

Full Text Available In the title compound, [Ba(C7H5N2O52(H2O6]·4H2O, the Ba2+ cation lies on a twofold rotation axis and is ten-coordinated by two 3,5-bis(hydroxyimino-1-methyl-2,4,6-trioxocyclohexanide oxo O atoms [Ba—O = 2.8715 (17 Å], two hydroxyimino N atoms [Ba—N = 3.036 (2 Å], and six water molecules [Ba—O = 2.847 (2, 2.848 (2, and 2.880 (2 Å]. The 3,5-bis(hydroxyimino-1-methyl-2,4,6-trioxocyclohexanide monoanions act in a bidentate chelating manner, coordinating through an N atom of the non-deprotonated hydroxyimino group and an O atom of the neighboring oxo group. Two lattice water molecules are located in the cavities of the framework and are involved in hydrogen bonding to O atoms of one of the coordinating water molecules and the O atom of a keto group of the ligand. As a result, a three-dimensional network is formed.
Regional N2O fluxes in Amazonia derived from aircraft vertical profiles

Science.gov (United States)

D'Amelio, M. T. S.; Gatti, L. V.; Miller, J. B.; Tans, P.

2009-11-01

Nitrous oxide (N2O) is the third most important anthropogenic greenhouse gas. Globally, the main sources of N2O are nitrification and denitrification in soils. About two thirds of the soil emissions occur in the tropics and approximately 20% originate in wet rainforest ecosystems, like the Amazon forest. The work presented here involves aircraft vertical profiles of N2O from the surface to 4 km over two sites in the Eastern and Central Amazon: Tapajós National Forest (SAN) and Cuieiras Biologic Reserve (MAN), and the estimation of N2O fluxes for regions upwind of these sites. To our knowledge, these regional scale N2O measurements in Amazonia are unique and represent a new approach to looking regional scale emissions. The fluxes upwind of MAN exhibited little seasonality, and the annual mean was 2.1±1.0 mg N2O m-2 day-1, higher than that for fluxes upwind of SAN, which averaged 1.5±1.6 mg N2O m-2 day-1. The higher rainfall around the MAN site could explain the higher N2O emissions, as a result of increased soil moisture accelerating microbial nitrification and denitrification processes. For fluxes from the coast to SAN seasonality is present for all years, with high fluxes in the months of March through May, and in November through December. The first peak of N2O flux is strongly associated with the wet season. The second peak of high N2O flux recorded at SAN occurs during the dry season and can not be easily explained. However, about half of the dry season profiles exhibit significant correlations with CO, indicating a larger than expected source of N2O from biomass burning. The average CO:N2O ratio for all profiles sampled during the dry season is 94±77 mol CO:mol N2O and suggests a larger biomass burning contribution to the global N2O budget than previously reported.
Etendatakse 10-aastase kirjamehe näitemäng

Index Scriptorium Estoniae

2003-01-01

Tartu katoliku kooli 3. klassi poisi Mario Raitari näitemäng "Kristoph Silvester von Tenderi lugu", mis on esimene lugu sarjast "Mario Raitari kroonika". Näidendit etendab Linnupuu Lastepereteatri trupp
Determination of the 54Fe(n, 2n)53gFe and 54Fe(n, 2n)53mFe cross sections averaged over a 235U fission neutron spectrum

International Nuclear Information System (INIS)

Ribeiro Guevara, S.; Arribere, M.; Kestelman, A.J.

2002-01-01

The reaction cross sections averaged over a 235 U fission neutron spectrum have been measured for the 54 Fe(n, 2n) 53g Fe and 54 Fe(n, 2n) 53m Fe threshold reactions. The values found are, respectively: (1.14 ± 0.13) μb, and (0.52 ± 0.16) μb. The measured cross sections are referred to the (111± 3) mb standard cross section of the 58 Ni(n, p) 58m+g Co reaction. The (81.7 ± 2.2) mb standard cross section value for the 54 Fe(n, p) 54 Mn reaction, was also used as a monitor to check the results obtained with the Ni standard, leading to an excellent agreement. (author)
Sintering of undoped SnO2 Sinterização de SnO2 não dopado

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E. R. Leite

2003-04-01

Full Text Available Pure SnO2 sintering was studied by constant heating rate and isothermal sintering. The constant heating rate study showed no macroscopic shrinkage during the sintering process up to 1500 ºC. Pore size distribution measurements, using gas desorption, and grain size and crystallite size measurements of isothermally sintered samples showed no formation of non-densifying microstructures during the sintering process. These results are a strong indication that densification was prevented by thermodynamic factors, mainly the high ratio of gammaGB/gSV. An explanation, based on the nature of covalent bonding and the balance between attractive and repulsive forces, was proposed to explain the high gammaGB/gammaSV ratio in SnO2.A sinterização de SnO2 puro foi estudado por taxa constante de aquecimento e por sinterização isotérmica. O estudo de taxa constante de aquecimento mostrou que não ocorre retração macroscópica durante o processo de sinterização até temperaturas de 1500 ºC. Medidas de distribuição de tamanho de poros, usando adsorção de gás, tamanho de grão e tamanho de cristalito para amostras sinterizadas isotermicamente mostrou a não formação de uma microestrutura não-densificante durante o processo de sinterização. Estes resultados são um forte indicativo que a densificação foi inibida por fatores termodinâmicos, principalmente o alto valor da razão de gamaGB/gSV. Uma explicação, baseada na natureza covalente da ligação química e no balanço entre forças atrativas e repulsivas, é apresentada para explicar o alto valor da razão gamaGB/gamaSV no SnO2.
Mannose-binding lectin contributes to deleterious inflammatory response in pandemic H1N1 and avian H9N2 infection.

Science.gov (United States)

Ling, Man To; Tu, Wenwei; Han, Yan; Mao, Huawei; Chong, Wai Po; Guan, Jing; Liu, Ming; Lam, Kwok Tai; Law, Helen K W; Peiris, J S Malik; Takahashi, K; Lau, Yu Lung

2012-01-01

Mannose-binding lectin (MBL) is a pattern-recognition molecule, which functions as a first line of host defense. Pandemic H1N1 (pdmH1N1) influenza A virus caused massive infection in 2009 and currently circulates worldwide. Avian influenza A H9N2 (H9N2/G1) virus has infected humans and has the potential to be the next pandemic virus. Antiviral function and immunomodulatory role of MBL in pdmH1N1 and H9N2/G1 virus infection have not been investigated. In this study, MBL wild-type (WT) and MBL knockout (KO) murine models were used to examine the role of MBL in pdmH1N1 and H9N2/G1 virus infection. Our study demonstrated that in vitro, MBL binds to pdmH1N1 and H9N2/G1 viruses, likely via the carbohydrate recognition domain of MBL. Wild-type mice developed more severe disease, as evidenced by a greater weight loss than MBL KO mice during influenza virus infection. Furthermore, MBL WT mice had enhanced production of proinflammatory cytokines and chemokines compared with MBL KO mice, suggesting that MBL could upregulate inflammatory responses that may potentially worsen pdmH1N1 and H9N2/G1 virus infections. Our study provided the first in vivo evidence that MBL may be a risk factor during pdmH1N1 and H9N2/G1 infection by upregulating proinflammatory response.
A combinatorial interpretation of the $κ^{\\star}_{g}(n)$ coefficients

DEFF Research Database (Denmark)

Li, Thomas Jiaxian; M. Reidys, Christian

2014-01-01

Studying the virtual Euler characteristic of the moduli space of curves, Harer and Zagier compute the generating function $C_g(z)$ of unicellular maps of genus $g$. They furthermore identify coefficients, $\\kappa^{\\star}_{g}(n)$, which fully determine the series $C_g(z)$. The main result of this ......Studying the virtual Euler characteristic of the moduli space of curves, Harer and Zagier compute the generating function $C_g(z)$ of unicellular maps of genus $g$. They furthermore identify coefficients, $\\kappa^{\\star}_{g}(n)$, which fully determine the series $C_g(z)$. The main result...... of this paper is a combinatorial interpretation of $\\kappa^{\\star}_{g}(n)$. We show that these enumerate a class of unicellular maps, which correspond $1$-to-$2^{2g}$ to a specific type of trees, referred to as O-trees. We furthermore prove a two term recursion for $\\kappa^{\\star}_{g}(n)$ and that for any fixed...
Determination of N-methylsuccinimide and 2-hydroxy-N-methylsuccinimide in human urine and plasma.

Science.gov (United States)

Jönsson, B A; Akesson, B

1997-12-19

A method for determination of N-methylsuccinimide (MSI) and 2-hydroxy-N-methylsuccinimide (2-HMSI) in human urine and of MSI in human plasma was developed. MSI and 2-HMSI are metabolites of the widely used organic solvent N-methyl-2-pyrrolidone (NMP). MSI and 2-HMSI were purified from urine and plasma by C8 solid-phase extraction and analysed by gas chromatography-mass spectrometry in the negative-ion chemical ionisation mode. The intra-day precisions in urine were 2-6% for MSI (50 and 400 ng/ml) and 3-5% for 2-HMSI (1000 and 8000 ng/ml). For MSI in plasma it was 2% (60 and 1200 ng/ml). The between-day precisions in urine were 3-4% for MSI (100 and 1000 ng/ml) and 2-4% for 2-HMSI (10,000 and 18,000 ng/ml) and 3-4% for MSI in plasma (100 and 900 ng/ml). The recoveries from urine were 109-117% for MSI (50 and 400 ng/ml) and 81-89% for 2-HMSI (1000 and 8000 ng/ml). The recovery of MSI from plasma was 91-101% (50 and 500 ng/ml). The detection limits for MSI were 3 ng/ml in urine and 1 ng/ml in plasma and that of 2-HMSI in urine was 200 ng/ml. The method is applicable for analysis of urine and plasma samples from workers exposed to NMP.
Top-down holographic G-structure glueball spectroscopy at (N)LO in N and finite coupling

International Nuclear Information System (INIS)

Sil, Karunava; Yadav, Vikas; Misra, Aalok

2017-01-01

The top-down type IIB holographic dual of large-N thermal QCD as constructed in Mia et al. (Nucl Phys B 839:187, 2010) involving a fluxed resolved warped deformed conifold, its delocalized type IIA Strominger-Yau-Zaslow-mirror (SYZ-mirror) as well as its M-theory uplift constructed in Dhuria and Misra (JHEP 1311:001, 2013) - both in the finite coupling g s 1/'MQGP' limit of Dhuria and Misra (JHEP 1311:001, 2013) - were shown explicitly to possess a local SU(3)/G 2 -structure in Sil and Misra (Nucl Phys B 910:754, 2016). Glueballs spectra in the finite-gauge-coupling limit (and not just large 't Hooft coupling limit) - a limit expected to be directly relevant to strongly coupled systems at finite temperature such as QGP (Natsuume in String theory and quark-gluon plasma, 2007) - has thus far been missing in the literature. In this paper, we fill this gap by calculating the masses of the 0 ++ , 0 -+ , 0 -- , 1 ++ , 2 ++ ('glueball') states (which correspond to fluctuations in the dilaton or complexified two-forms or appropriate metric components) in the aforementioned backgrounds of G-structure in the 'MQGP' limit of Dhuria and Misra (JHEP 1311:001, 2013). We use WKB quantization conditions on one hand and impose Neumann/Dirichlet boundary conditions at an IR cut-off ('r 0 ')/horizon radius ('r h ') on the solutions to the equations of motion on the other hand. We find that the former technique produces results closer to the lattice results. We also discuss the r h = 0 limits of all calculations. In this context we also calculate the 0 ++ , 0 -- , 1 ++ , 2 ++ glueball masses up to Next to Leading Order (NLO) in N and find a (g s M 2 )/(N)(g s N f )-suppression similar to and further validating semi-universality of NLO corrections to transport coefficients, observed in Sil and Misra (Eur Phys J C 76(11):618, 2016). (orig.)
Thermal expansion and magnetostriction in Pr(n+2)(n+1)Nin(n-1)+2Sin(n+1) compounds

International Nuclear Information System (INIS)

Jiles, D.C.; Song, S.H.; Snyder, J.E.; Pecharsky, V.K.; Lograsso, T.A.; Wu, D.; Pecharsky, A.O.; Mudryk, Ya.; Dennis, K.W.; McCallum, R.W.

2006-01-01

Thermal expansion and magnetostriction of members of a homologous series of compounds based on the alloy series Pr (n+2)(n+1) Ni n(n-1)+2 Si n(n+1) have been measured. The crystal structures of these compounds are closely interrelated because they form trigonal prismatic columns in which the number of trigonal prisms that form the base of the trigonal columns is determined by the value of n in the chemical formula. Two compositions were investigated, Pr 5 Ni 2 Si 3 and Pr 15 Ni 7 Si 10 , corresponding to n=3 and n=4, respectively. The results were analyzed and used to determine the location of magnetic phase transitions by calculating the magnetic contribution to thermal expansion using the Gruneisen-Debye theory. This allowed more precise determination of the magnetic transition temperatures than could be achieved using the total thermal expansion. The results show two phase transitions in each material, one corresponding to the Curie temperature and the other at a lower temperature exhibiting characteristics of a spin reorientation transition
Managed grassland alters soil N dynamics and N2O emissions in temperate steppe.

Science.gov (United States)

Xu, Lijun; Xu, Xingliang; Tang, Xuejuan; Xin, Xiaoping; Ye, Liming; Yang, Guixia; Tang, Huajun; Lv, Shijie; Xu, Dawei; Zhang, Zhao

2018-04-01

Reclamation of degraded grasslands as managed grasslands has been increasingly accelerated in recent years in China. Land use change affects soil nitrogen (N) dynamics and nitrous oxide (N 2 O) emissions. However, it remains unclear how large-scale grassland reclamation will impact the grassland ecosystem as a whole. Here, we investigated the effects of the conversion from native to managed grasslands on soil N dynamics and N2O emissions by field experiments in Hulunber in northern China. Soil (0-10cm), nitrate (NO 3 - ), ammonium (NH 4 + ), and microbial N were measured in plots in a temperate steppe (Leymus chinensis grassland) and two managed grasslands (Medicago sativa and Bromus inermis grasslands) in 2011 and 2012. The results showed conversion of L. chinensis grassland to M. sativa or B. inermis grasslands decreased concentrations of NO 3 - -N, but did not change NH 4 + -N. Soil microbial N was slightly decreased by the conversion of L. chinensis grassland to M. sativa, but increased by the conversion to B. inermis. The conversion of L. chinensis grassland to M. sativa (i.e., a legume grass) increased N 2 O emissions by 26.2%, while the conversion to the B. inermis (i.e., a non-legume grass) reduced N 2 O emissions by 33.1%. The conversion from native to managed grasslands caused large created variations in soil NO 3 - -N and NH 4 + -N concentrations. Net N mineralization rates did not change significantly in growing season or vegetation type, but to net nitrification rate. These results provide evidence on how reclamation may impact the grassland ecosystem in terms of N dynamics and N 2 O emissions. Copyright © 2017. Published by Elsevier B.V.
Theoretical study for the reduction of N2O with CO Mediated by alkaline-earth metal oxide cations 2MO+(M=Ca, Sr, Ba)

International Nuclear Information System (INIS)

Zhang Jianhui; Leng Yanli; Wang Yongcheng

2013-01-01

The reaction mechanism of the reaction N 2 O( 0 Σ + ) + CO ( 1 Σ + )→N 2 ( 1 Σ g + ) + CO 2 ( 1 Σ g + ) mediated by alkaline-earth metal oxide cations 2 MO + (m=Ca, Sr, Ba) have been investigated by using the UB3LYP and CCSD (T) levels of theory. The O-atom affinities (OA) testified that only the 2 CaO + can capture O from N 2 O and transfer O to CO is thermodynamically allowed in three ions. The processes can be expressed as channels l and 2 for the reaction of N 2 O and CO mediated by 2 MO + (M=Ca, Sr, Ba). For the former, the main reaction processes in a two-step manner to products, the 2 MO + , as a catalyzer, transports an oxygen atom from N 2 O to CO. For the latter, firstly, the N 2 O interact with the 2 MO + to form IM1, then IM1 interact with the CO to form IM2', along the reaction pathway the intermediate species convert into products 2 1MO + , N 2 and CO 2 . From above results, the following conclusion was drawn. The channel 2 is kinetically and thermodynamically feasible. Our calculated results show the title reactions are accord with the experiment. (authors)
Tris(2,2′-bipyridine-κ2N,N′cobalt(III bis[bis(pyridine-2,6-dicarboxylato-κ3O2,N,O6cobaltate(III] perchlorate dimethylformamide hemisolvate 1.3-hydrate

Directory of Open Access Journals (Sweden)

Irina A. Golenya

2012-10-01

Full Text Available In the title compound, [Co(C10H8N23][Co(C7H3NO42]2(ClO4·0.5C3H7NO·1.3H2O, the CoIII atom in the complex cation is pseudooctahedrally coordinated by six N atoms of three chelating bipyridine ligands. The CoIII atom in the complex anion is coordinated by two pyridine N atoms and four carboxylate O atoms of two doubly deprotonated pyridine-2,6-dicarboxylate ligands in a distorted octahedral geometry. One dimethylformamide solvent molecule and two water molecules are half-occupied and one water molecule is 0.3-occupied. O—H...O hydrogen bonds link the water molecules, the perchlorate anions and the complex anions. π–π interactions between the pyridine rings of the complex anions are also observed [centroid–centroid distance = 3.804 (3 Å].
Uncertainties in United States agricultural N2O emissions: comparing forward model simulations to atmospheric N2O data.

Science.gov (United States)

Nevison, C. D.; Saikawa, E.; Dlugokencky, E. J.; Andrews, A. E.; Sweeney, C.

2014-12-01

Atmospheric N2O concentrations have increased from 275 ppb in the preindustrial to about 325 ppb in recent years, a ~20% increase with important implications for both anthropogenic greenhouse forcing and stratospheric ozone recovery. This increase has been driven largely by synthetic fertilizer production and other perturbations to the global nitrogen cycle associated with human agriculture. Several recent regional atmospheric inversion studies have quantified North American agricultural N2O emissions using top-down constraints based on atmospheric N2O data from the National Oceanic and Atmospheric Administration (NOAA) Global Greenhouse Gas Reference Network, including surface, aircraft and tall tower platforms. These studies have concluded that global N2O inventories such as EDGAR may be underestimating the true U.S. anthropogenic N2O source by a factor of 3 or more. However, simple back-of-the-envelope calculations show that emissions of this magnitude are difficult to reconcile with the basic constraints of the global N2O budget. Here, we explore some possible reasons why regional atmospheric inversions might overestimate the U.S. agricultural N2O source. First, the seasonality of N2O agricultural sources is not well known, but can have an important influence on inversion results, particularly when the inversions are based on data that are concentrated in the spring/summer growing season. Second, boundary conditions can strongly influence regional inversions but the boundary conditions used may not adequately account for remote influences on surface data such as the seasonal stratospheric influx of N2O-depleted air. We will present a set of forward model simulations, using the Community Land Model (CLM) and two atmospheric chemistry tracer transport models, MOZART and the Whole Atmosphere Community Climate Model (WACCM), that examine the influence of terrestrial emissions and atmospheric chemistry and dynamics on atmospheric variability in N2O at U.S. and
Effect of sulfation on the surface activity of CaO for N2O decomposition

International Nuclear Information System (INIS)

Wu, Lingnan; Hu, Xiaoying; Qin, Wu; Dong, Changqing; Yang, Yongping

2015-01-01

Graphical abstract: - Highlights: • Sulfation of CaO (1 0 0) surface greatly deactivates its surface activity for N 2 O decomposition. • An increase of sulfation degree leads to a decrease of CaO surface activity for N 2 O decomposition. • Sulfation from CaSO 3 into CaSO 4 is the crucial step for deactivating the surface activity for N 2 O decomposition. • The electronic interaction CaO (1 0 0)/CaSO 4 (0 0 1) interface is limited to the bottom layer of CaSO 4 (0 0 1) and the top layer of CaO (1 0 0). • CaSO 4 (0 0 1) and (0 1 0) surfaces show negligible catalytic ability for N 2 O decomposition. - Abstract: Limestone addition to circulating fluidized bed boilers for sulfur removal affects nitrous oxide (N 2 O) emission at the same time, but mechanism of how sulfation process influences the surface activity of CaO for N 2 O decomposition remains unclear. In this paper, we investigated the effect of sulfation on the surface properties and catalytic activity of CaO for N 2 O decomposition using density functional theory calculations. Sulfation of CaO (1 0 0) surface by the adsorption of a single gaseous SO 2 or SO 3 molecule forms stable local CaSO 3 or CaSO 4 on the CaO (1 0 0) surface with strong hybridization between the S atom of SO x and the surface O anion. The formed local CaSO 3 increases the barrier energy of N 2 O decomposition from 0.989 eV (on the CaO (1 0 0) surface) to 1.340 eV, and further sulfation into local CaSO 4 remarkably increases the barrier energy to 2.967 eV. Sulfation from CaSO 3 into CaSO 4 is therefore the crucial step for deactivating the surface activity for N 2 O decomposition. Completely sulfated CaSO 4 (0 0 1) and (0 1 0) surfaces further validate the negligible catalytic ability of CaSO 4 for N 2 O decomposition.

Greenhouse Gas (CO2 AND N2O Emissions from Soils: A Review Emisión de Gases invernadero (CO2 y N2O desde Suelos

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Cristina Muñoz

2010-09-01

Full Text Available In agricultural activities, the main greenhouse gases (GHG are those related to C and N global cycles. The impact of agriculture on GHG emissions has become a key issue, especially when considering that natural C and N cycles are influenced by agricultural development. This review focuses on CO2 and N2O soil emissions in terrestrial ecosystems, with emphasis in Chilean and similar agro-ecosystems around the world. The influence of land use and crop management practices on CO2 and N2O emissions is analyzed; some mitigation measures to reduce such emissions are also discussed here. More knowledge on the biological processes that promote of GHG emissions from soil will allow creating opportunities for agricultural development under friendly-environmental conditions, where soil can act as a reservoir and/or emitter of GHG, depending on the balance of inputs and outputs.En actividades agrícolas los principales gases de efecto invernadero (GHG son los relacionados con los ciclos globales de C y N. El impacto de la agricultura sobre las emisiones GHG se ha convertido en una cuestión clave, especialmente si se considera que los ciclos naturales C y N se ven influidos por el desarrollo agrícola. Esta revisión se centra en emisiones de CO2 y N2O del suelo en los ecosistemas terrestres, con énfasis en agro-ecosistemas de Chile y similares alrededor del mundo. Se analiza la influencia del uso del suelo y las prácticas de manejo del cultivo sobre emisiones de CO2 y N2O, se discuten medidas de mitigación para reducir estas emisiones. Un mayor conocimiento sobre los procesos biológicos que promueven las emisiones GHG del suelo permitirá la creación de oportunidades para el desarrollo agrícola en condiciones ambientalmente amigables, donde el suelo puede actuar como un reservorio y/o emisor de GHG, dependiendo del balance de entradas y salidas.
On textual and contextual position of the ophthalmological treatise of bodhisattva nāgārjuna.

Science.gov (United States)

Kim, Seongsu; Kang, Sungyong

2013-04-01

Medical knowledge in India began to be introduced to China in earliest from the Later Han Dynasty period to the times of Wei-Qin and South & North Dynasties. This is proved by many Buddhist medical books appeared in those days. Of the contents of Indian medicine, the theory of four major elements affected Chinese medicine more than did the theory of body fluids. Based on the theory of four major elements that was began to be introduced in Fú shuō fú yī jīng, an attempt to establish a new medical system was made in Zhŏu hòu băi yīfāng written by Táo Hóng-jĭng and Sūn Sī-miăo who tried to develop etiology further but could not achieve any great outcomes. Unlike the foregoing situation, Indian medicine aroused a large echo in China in the field of ophthalmology with ophthalmological knowledge mentioned in Suśrutasa hitā and 'Jīnzhēn-shù'(cataract couching) introduced as a surgical treatment of cataract. The Suśrutasa hitā which is one of the three major texts of Indian medicine contains additional information on surgical operations not introduced in the Carakasa hitā. The technique of cataract surgery was particularly popular in the Tang and Song dynasty periods in China under the name Lóng shù pú sà yăn lùn(The Ophthalmological Treatise of Bodhisattva Nāgārjuna) or Lóng shù lùn and was even designated as a subject to educate medical officers. While the original text of Lóng shù pú sà yăn lùn was not handed down, the first testimony that show the trace of the introduction of this text into China was the Tiān zhú jīng lùn yăn mentioned in Wài tái mì yào(Arcane Essential from the Imperial Library) written by Wang Tao. Long shàng dào ren who was mentioned as the compiler of the book is assumed to be Lóng shù. Although Tiān zhú jīng lùn yăn introduced anatomical knowledge about the eyeball that could have not been in the traditional Chinese medicine, this book has only limited quantity of information in this
Crystal structure of an unknown solvate of bis(tetra-n-butylammonium [N,N′-(4-trifluoromethyl-1,2-phenylenebis(oxamato-κ4O,N,N′,O′]nickelate(II

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François Eya'ane Meva

2015-06-01

Full Text Available In the title compound, [N(C4H94]2[Ni(C11H3F3N2O6] or [N(n-Bu4]2[Ni(topbo] [n-Bu = n-butyl and topbo = 4-trifluoromethyl-1,2-phenylenebis(oxamate], the Ni2+ cation is coordinated by two deprotonated amido N atoms and two carboxylate O atoms, setting up a slightly distorted square-planar coordination environment. The [Ni(topbo]2− anion lies on a twofold rotation axis. Due to an incompatibility with the point-group symmetry of the complete molecule, orientational disorder of the CF3 group is observed. The tetrahedral ammonium cations and the anion are linked by weak intermolecular C—H...O and C—H...F hydrogen-bonding interactions into a three-dimensional network. A region of electron density was treated with the SQUEEZE procedure in PLATON [Spek (2015. Acta Cryst. C71, 9–18] following unsuccessful attempts to model it as plausible solvent molecule(s. The given chemical formula and other crystal data do not take into account the unknown solvent molecule.
Ti{sub 2}Al(O,N) formation by solid-state reaction between substoichiometric TiN thin films and Al{sub 2}O{sub 3} (0001) substrates

Energy Technology Data Exchange (ETDEWEB)

Persson, P.O.A., E-mail: perpe@ifm.liu.se; Hoeglund, C.; Birch, J.; Hultman, L.

2011-02-01

Titanium nitride TiN{sub x} (0.1 {<=} x {<=} 1) thin films were deposited onto Al{sub 2}O{sub 3}(0001) substrates using reactive magnetron sputtering at substrate temperatures (T{sub s}) ranging from 800 to 1000 {sup o}C and N{sub 2} partial pressures (pN{sub 2}) between 13.3 and 133 mPa. It is found that Al and O from the substrates diffuse into the substoichiometric TiN{sub x} films during deposition. Solid-state reactions between the film and substrate result in the formation of Ti{sub 2}O and Ti{sub 3}Al domains at low N{sub 2} partial pressures, while for increasing pN{sub 2}, the Ti{sub 2}AlN MAX phase nucleates and grows together with TiN{sub x}. Depositions at increasingly stoichiometric conditions result in a decreasing incorporation of substrate species into the growing film. Eventually, a stoichiometric deposition gives a stable TiN(111) || Al{sub 2}O{sub 3}(0001) structure without the incorporation of substrate species. Growth at T{sub s} 1000 {sup o}C yields Ti{sub 2}AlN(0001), leading to a reduced incorporation of substrate species compared to films grown at 900 {sup o}C, which contain also Ti{sub 2}AlN(101-bar3) grains. Finally, the Ti{sub 2}AlN domains incorporate O, likely on the N site, such that a MAX phase oxynitride Ti{sub 2}Al(O,N) is formed. The results were obtained by a combination of structural methods, including X-ray diffraction and (scanning) transmission electron microscopy, together with spectroscopy methods, which comprise elastic recoil detection analysis, energy dispersive X-ray spectroscopy, and electron energy loss spectroscopy.
Oceanic N2O emissions in the 21st century

Science.gov (United States)

Martinez-Rey, J.; Bopp, L.; Gehlen, M.; Tagliabue, A.; Gruber, N.

2014-12-01

The ocean is a substantial source of nitrous oxide (N2O) to the atmosphere, but little is known on how this flux might change in the future. Here, we investigate the potential evolution of marine N2O emissions in the 21st century in response to anthropogenic climate change using the global ocean biogeochemical model NEMO-PISCES. We implemented two different parameterizations of N2O production, which differ primarily at low oxygen (O2) conditions. When forced with output from a climate model simulation run under the business-as-usual high CO2 concentration scenario (RCP8.5), our simulations suggest a decrease of 4 to 12% in N2O emissions from 2005 to 2100, i.e., a reduction from 4.03/3.71 to 3.54/3.56 Tg N yr-1 depending on the parameterization. The emissions decrease strongly in the western basins of the Pacific and Atlantic oceans, while they tend to increase above the Oxygen Minimum Zones (OMZs), i.e., in the Eastern Tropical Pacific and in the northern Indian Ocean. The reduction in N2O emissions is caused on the one hand by weakened nitrification as a consequence of reduced primary and export production, and on the other hand by stronger vertical stratification, which reduces the transport of N2O from the ocean interior to the ocean surface. The higher emissions over the OMZ are linked to an expansion of these zones under global warming, which leads to increased N2O production associated primarily with denitrification. From the perspective of a global climate system, the averaged feedback strength associated with the projected decrease in oceanic N2O emissions amounts to around -0.009 W m-2 K-1, which is comparable to the potential increase from terrestrial N2O sources. However, the assesment for a compensation between the terrestrial and marine feedbacks calls for an improved representation of N2O production terms in fully coupled next generation of Earth System Models.
Diaquabis[5-(2-pyridyltetrazolato-κ2N1,N5]iron(II

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Min Hu

2009-04-01

Full Text Available The title complex, [Fe(C6H4N52(H2O2], was synthesized by the reaction of ferrous sulfate with 5-(2-pyridyl-2H-tetrazole (HL. The FeII atom, located on a crystallographic center of inversion, is coordinated by four N-atom donors from two planar trans-related deprotonated L ligands and two O atoms from two axial water molecules in a distorted octahedral geometry. The FeII mononuclear units are further connected by intermolecular O—H...N and C—H...O hydrogen-bonding interactions, forming a three-dimensional framework.
Controlled carrier screening in p-n NiO/GaN piezoelectric generators by an Al2O3 insertion layer

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Johar, Muhammad Ali; Jeong, Dae Kyung; Afifi Hassan, Mostafa; Kang, Jin-Ho; Ha, Jun-Seok; Key Lee, June; Ryu, Sang-Wan

2017-12-01

The performance of a piezoelectric generator (PG) depends significantly on the internal screening process inside the device. As piezoelectric charges appear on both ends of the piezoelectric crystal, internal screening starts to decrease the piezoelectric bias. Therefore, the piezoelectric energy generated by external stress is not fully utilized by external circuit, which is the most challenging aspect of high-efficiency PGs. In this work, the internal screening effect of a NiO/GaN p-n PG was analyzed and controlled with an Al2O3 insertion layer. Internal screening in the p-n diode PG was categorized into free-carrier screening in neutral regions and junction screening due to charge drift across the junction. It was observed that junction screening could be significantly suppressed by inserting an Al2O3 layer and that effect was dominant in a leaky diode PG. With this implementation, the piezoelectric bias of the NiO/GaN PG was improved by a factor of ~100 for high-leakage diodes and a factor of ~1.6 for low-leakage diodes. Consequently, NiO/Al2O3/GaN PGs under a stress of 5 MPa provided a piezoelectric bias of 12.1 V and a current density of 2.25 µA cm-2. The incorporation of a highly resistive Al2O3 layer between p-NiO and n-GaN layers in NiO/GaN heterojunctions provides an efficient means of improving the piezoelectric performance by controlling the internal screening of the piezoelectric field.
Structure of (Ga2O3)2(ZnO)13 and a unified description of the homologous series (Ga2O3)2(ZnO)(2n + 1).

Science.gov (United States)

Michiue, Yuichi; Kimizuka, Noboru; Kanke, Yasushi; Mori, Takao

2012-06-01

The structure of (Ga(2)O(3))(2)(ZnO)(13) has been determined by a single-crystal X-ray diffraction technique. In the monoclinic structure of the space group C2/m with cell parameters a = 19.66 (4), b = 3.2487 (5), c = 27.31 (2) Å, and β = 105.9 (1)°, a unit cell is constructed by combining the halves of the unit cell of Ga(2)O(3)(ZnO)(6) and Ga(2)O(3)(ZnO)(7) in the homologous series Ga(2)O(3)(ZnO)(m). The homologous series (Ga(2)O(3))(2)(ZnO)(2n + 1) is derived and a unified description for structures in the series is presented using the (3+1)-dimensional superspace formalism. The phases are treated as compositely modulated structures consisting of two subsystems. One is constructed by metal ions and another is by O ions. In the (3 + 1)-dimensional model, displacive modulations of ions are described by the asymmetric zigzag function with large amplitudes, which was replaced by a combination of the sawtooth function in refinements. Similarities and differences between the two homologous series (Ga(2)O(3))(2)(ZnO)(2n + 1) and Ga(2)O(3)(ZnO)(m) are clarified in (3 + 1)-dimensional superspace. The validity of the (3 + 1)-dimensional model is confirmed by the refinements of (Ga(2)O(3))(2)(ZnO)(13), while a few complex phenomena in the real structure are taken into account by modifying the model.
Spatial distribution of hydroxylamine and its role in aerobic N2O formation in a Norway spruce forest soil

Science.gov (United States)

Liu, S.; Weymann, D.; Gottselig, N.; Wiekenkamp, I.; Vereecken, H.; Brueggemann, N.

2014-12-01

Hydroxylamine (HA) as a crucial intermediate in the microbial oxidation of ammonium to nitrite (nitrification) is a potential precursor of abiotic N2O formation in the soil. However, the determination of HA concentration in natural soil samples has not been reported until now. Here, we determined the HA concentrations in organic (Oh) and mineral (Ah) layers of 135 soil samples collected from a spruce forest (Wüstebach, Eifel National Park, Germany) using a novel approach, based on the fast extraction of HA from the soil at a pH of 1.7, the oxidation of HA to N2O with Fe3+, and the analysis of produced N2O using gas chromatography (GC). Meanwhile, N2O emission rates were determined by means of aerobic laboratory incubations of 3-g soil in 22-mL vials. Subsequently, the spatial distribution of soil HA concentrations and N2O emission rates in the Oh and Ah layers of the whole sampling area were analyzed using a geostatistical approach. The correlations among soil HA, N2O emission rate, pH, soil C, N, Fe, Mn and soil water content (SWC) were further explored. The HA concentrations ranged from 0.3-44.6 μg N kg-1 dry soil and 0.02-16.2 μg N kg-1 dry soil in the Oh and the Ah layer, respectively. The spatial distribution of HA was similar in both layers, with substantial spatial variability dependent on soil type, tree density and distance to a stream. For example, HA concentration was greater at locations with a thick litter layer or at locations close to the stream. The average N2O emission rate in the Oh layer was 0.38 μg N kg-1 dry soil h-1, 10-fold larger than in the Ah layer. Interestingly, N2O emission rate exhibited high correlation with soil HA content in the Oh (R2 = 0.65, p < 0.01) and Ah (R2 = 0.45, p < 0.05) layer. The results demonstrated that HA is a crucial component for aerobic N2O formation and emission in spruce forest soils. Moreover, HA concentration was negatively correlated with pH and positively correlated with SWC in the Oh layer, while
Facile one-pot construction of α-Fe_2O_3/g-C_3N_4 heterojunction for arsenic removal by synchronous visible light catalysis oxidation and adsorption

International Nuclear Information System (INIS)

Sun, Suwen; Ji, Chunnuan; Wu, Lingling; Chi, Shenghua; Qu, Rongjun; Li, Yan; Lu, Yangxiao; Sun, Changmei; Xue, Zhongxin

2017-01-01

α-Fe_2O_3/g-C_3N_4 composites with heterojunction were prepared by facile one-pot synthesis using ferric chloride and dicyandiamide as precursors. The newly formed composites were applied to remove arsenic from aqueous solution for the first time through synchronous visible light catalysis oxidation and adsorption. α-Fe_2O_3/g-C_3N_4 composites were characterized by wide-angle X-ray powder diffraction, transmission electron microscopy, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, UV–Vis diffuse reflectance spectroscopy, and BET surface analysis. Under visible light irradiation, As(III) was oxidized to As(V) efficiently on the surface of α-Fe_2O_3/g-C_3N_4. In addition, the oxidized arsenic could be adsorbed in situ, resulting in the effective arsenic removal. The enhancement of photocatalytic activity the composites was attributed to the construction of heterojunction between α-Fe_2O_3 and g-C_3N_4. A possible oxidation mechanism of the as-composites for As(III) under visible light irradiation was also elucidated. - Highlights: • α-Fe_2O_3/g-C_3N_4 composites with heterojunction was prepared by facile one-pot synthesis. • The photocatalytic activity of α-Fe_2O_3/g-C_3N_4 composites under visible light irradiation for As(III) was evaluated. • Synchronous visible light catalysis oxidation and adsorption were achieved for the removal of arsenic. • The reasonable oxidation mechanism of the composites for As(III) under visible light irradiation was investigated.
The topotactic dehydration of monoclinic {[Co(pht)(bpy)(H2O)2]·2H2O}n into orthorhombic [Co(pht)(bpy)(H2O)2]n (pht is phthalate and bpy is 4,4'-bipyridine).

Science.gov (United States)

Harvey, Miguel Angel; Suarez, Sebastián; Cukiernik, Fabio D; Baggio, Ricardo

2014-10-01

Controlled heating of single crystals of the previously reported [Köferstein & Robl (2007). Z. Anorg. Allg. Chem. 633, 1127-1130] dihydrate {[Co(pht)(bpy)(H2O)2]·2H2O}n, (II) [where pht is phthalate (C8H4O4) and bpy is 4,4'-bipyridine (C10H8N2)], produced a topotactic transformation into an unreported diaqua anhydrate, namely poly[diaqua(μ2-benzene-1,2-dicarboxylato-κ(2)O(1):O(2))(μ2-4,4'-bipyridine-κ(2)N:N')cobalt(II)], [Co(C8H4O4)(C10H8N2)(H2O)2]n, (IIa). The structural change consists of the loss of the two solvent water molecules linking the original two-dimensional covalent substructures which are the `main frame' of the monoclinic P2/n hydrate (strictly preserved during the transformation), with further reaccommodation of the latter. The anhydrate organizes itself in the orthorhombic system (space group Pmn2(1)) in a disordered fashion, where the space-group-symmetry restrictions are achieved only in a statistical sense, with mirror-related two-dimensional planar substructures, mirrored in a plane perpendicular to [100]. Thus, the asymmetric unit in the refined model is composed of two superimposed mirror-related `ghosts' of half-occupancy each. Similarities and differences with the parent dihydrate and some other related structures in the literature are discussed.
Electrical characteristics and interface properties of ALD-HfO2/AlGaN/GaN MIS-HEMTs fabricated with post-deposition annealing

Science.gov (United States)

Kubo, Toshiharu; Egawa, Takashi

2017-12-01

HfO2/AlGaN/GaN metal-insulator-semiconductor (MIS)-type high electron mobility transistors (HEMTs) on Si substrates were fabricated by atomic layer deposition of HfO2 layers and post-deposition annealing (PDA). The current-voltage characteristics of the MIS-HEMTs with as-deposited HfO2 layers showed a low gate leakage current (I g) despite the relatively low band gap of HfO2, and a dynamic threshold voltage shift (ΔV th) was observed. After PDA above 500 °C, ΔV th was reduced from 2.9 to 0.7 V with an increase in I g from 2.2 × 10-7 to 4.8 × 10-2 mA mm-1. Effects of the PDA on the HfO2 layer and the HfO2/AlGaN interface were investigated by x-ray photoelectron spectroscopy (XPS) using synchrotron radiation. XPS data showed that oxygen vacancies exist in the as-deposited HfO2 layers and they disappeared with an increase in the PDA temperature. These results indicate that the deep electron traps that cause ΔV th are related to the oxygen vacancies in the HfO2 layers.
O{sub 2}(X{sup 3}Σ{sub g}{sup −}) and O{sub 2}(a{sup 1}Δ{sub g}) charge exchange with simple ions

Energy Technology Data Exchange (ETDEWEB)

Ziółkowski, Marcin; Schatz, George C., E-mail: schatz@chem.northwestern.edu [Department of Chemistry, Northwestern University, Evanston, Illinois 60208-3113 (United States); Viggiano, A. A.; Midey, Anthony [Air Force Research Laboratory, Space Vehicles Directorate, 3500 Aberdeen Ave, Kirtland AFB, New Mexico 87117 (United States); Dotan, Itzhak [Air Force Research Laboratory, Space Vehicles Directorate, 3500 Aberdeen Ave, Kirtland AFB, New Mexico 87117 (United States); Open University of Israel, 108 Ravutski St., Raanana 43107 (Israel)

2014-06-07

We present theory and experiments which describe charge transfer from the X{sup 3}Σ{sub g}{sup −} and a{sup 1}Δ{sub g} states of molecular oxygen and atomic and molecular cations. Included in this work are new experimental results for O{sub 2}(a{sup 1}Δ{sub g}) and the cations O{sup +}, CO{sup +}, Ar{sup +}, and N{sub 2}{sup +}, and new theory based on complete active space self-consistent field method calculations and an extended Langevin model to calculate rate constants for ground and excited O{sub 2} reacting with the atomic ions Ar{sup +}, Kr{sup +}, Xe{sup +}, Cl{sup +}, and Br{sup +}. The T-shaped orientation of the (X − O{sub 2}){sup +} potential surface is used for the calculations, including all the low lying states up to the second singlet state of the oxygen molecule b{sup 1}Σ{sub g}{sup +}. The calculated rate constants for both O{sub 2}(X{sup 3}Σ{sub g}{sup −}) and O{sub 2}(a{sup 1}Δ{sub g}) show consistent trends with the experimental results, with a significant dependence of rate constant on charge transfer exothermicity that does not depend strongly on the nature of the cation. The comparisons with theory show that partners with exothermicities of about 1 eV have stronger interactions with O{sub 2}, leading to larger Langevin radii, and also that more of the electronic states are attractive rather than repulsive, leading to larger rate constants. Rate constants for charge transfer involving O{sub 2}(a{sup 1}Δ{sub g}) are similar to those for O{sub 2}(X{sup 3}Σ{sub g}{sup −}) for a given exothermicity ignoring the electronic excitation of the O{sub 2}(a{sup 1}Δ{sub g}) state. This means (and the electronic structure calculations support) that the ground and excited states of O{sub 2} have about the same attractive interactions with ions.
Facile synthesis of Fe4N/Fe2O3/Fe/porous N-doped carbon nanosheet as high-performance anode for lithium-ion batteries

Science.gov (United States)

Zhang, Dan; Li, Guangshe; Yu, Meijie; Fan, Jianming; Li, Baoyun; Li, Liping

2018-04-01

Iron nitrides are considered as highly promising anode materials for lithium-ion batteries because of their nontoxicity, high abundance, low cost, and higher electrical conductivity. Unfortunately, their limited synthesis routes are available and practical application is still hindered by their fast capacity decay. Herein, a facile and green route is developed to synthesize Fe4N/Fe2O3/Fe/porous N-doped carbon nanosheet composite. The size of Fe4N/Fe2O3/Fe particles is small (10-40 nm) and they are confined in porous N-doped carbon nanosheet. These features are conducive to accommodate volume change well, shorten the diffusion distance and further elevate electrical conductivity. When tested as anode material for lithium-ion batteries, a high discharge capacity of 554 mA h g-1 after 100 cycles at 100 mA g-1 and 389 mA h g-1 after 300 cycles at 1000 mA g-1 are retained. Even at 2000 mA g-1, a high capacity of 330 mA h g-1 can be achieved, demonstrating superior cycling stability and rate performance. New prospects will be brought by this work for the synthesis and the potential application of iron nitrides materials as an anode for LIBs.
N2O Decomposition over Cu–Zn/γ–Al2O3 Catalysts

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Runhu Zhang

2016-12-01

Full Text Available Cu–Zn/γ–Al2O3 catalysts were prepared by the impregnation method. Catalytic activity was evaluated for N2O decomposition in a fixed bed reactor. The fresh and used catalysts were characterized by several techniques such as BET surface area, X-ray diffraction (XRD, and scanning electron microscopy (SEM. The Cu–Zn/γ–Al2O3 catalysts exhibit high activity and stability for N2O decomposition in mixtures simulating real gas from adipic acid production, containing N2O, O2, NO, CO2, and CO. Over the Cu–Zn/γ–Al2O3 catalysts, 100% of N2O conversion was obtained at about 601 °C at a gas hourly space velocity (GHSV of 7200 h−1. Cu–Zn/γ–Al2O3 catalysts also exhibited considerably good durability, and no obvious activity loss was observed in the 100 h stability test. The Cu–Zn/γ–Al2O3 catalysts are promising for the abatement of this powerful greenhouse gas in the chemical industry, particularly in adipic acid production.
Fourier transform infrared studies of the N2-O2 binary system

International Nuclear Information System (INIS)

Minenko, M.; Jodi, H.-J.

2006-01-01

Solid solutions (N 2 ) x (O 2 ) 1-x have been investigated by infrared absorption measurements mainly in the O 2 and N 2 stretching regions, between 60-10 K, completing former similar studies by Raman scattering. We produced thermodynamically stable samples by a careful thermal treatment, followed by cooling/heating cycles over weeks, during which we took spectra. From fingerprints in the infrared spectra we deduce phase-transition and solubility lines and suggest a refined, improved T-x % phase diagram in respect to the inconsistencies between those in the literature. The spectra of N 2 -O 2 mixtures are pretty complex, but by referring to known spectra of the pure systems N 2 or O 2 we were able to assign and interpret broad (∼100 cm - 1 ) phonon side bands to fundamentals and an electronic transition (O 2 ), depending on actual temperature and concentration. Narrow features in the spectra ( -1 ) were attributed to the vibron DOS of N 2 or O 2 , whose bandwidth, band shape, and intensity are different and characteristic for each phase. Differences between pure and mixed systems are pointed out. The matrix isolation technique (2 ppm of CO) was used to probe our mixture
Nanosecond pulsed discharges in N2 and N2/H2O mixtures

NARCIS (Netherlands)

Joosten, R.M.; Verreycken, T.; Veldhuizen, van E.M.; Bruggeman, P.J.

2011-01-01

Nanosecond pulsed discharges in N2 and N2/H2O at atmospheric pressure between two pin-shaped electrodes are studied. The evolution of the discharge is investigated with time-resolved imaging and optical emission spectroscopy. The discharge consists of three phases, the ignition (mainly molecular
Validation of a station-prototype designed to integrate temporally soil N2O fluxes: IPNOA Station prototype.

Science.gov (United States)

Laville, Patricia; Volpi, Iride; Bosco, Simona; Virgili, Giorgio; Neri, Simone; Continanza, Davide; Bonari, Enrico

2016-04-01

Nitrous oxide (N2O) flux measurements from agricultural soil surface still accounts for the scientific community as major challenge. The evaluations of integrated soil N2O fluxes are difficult because these emissions are lower than for the other greenhouse gases sources (CO2, CH4). They are also sporadic, because highly dependent on few environmental conditions acting as limiting factors. Within a LIFE project (IPNOA: LIFE11 ENV/IT/00032) a station prototype was developed to integrate annually N2O and CO2 emissions using automatically chamber technique. Main challenge was to develop a device enough durable to be able of measuring in continuous way CO2 and N2O fluxes with sufficient sensitivity to allow make reliable assessments of soil GHG measurements with minimal technical field interventions. The IPNOA station prototype was developed by West System SRL and was set up during 2 years (2014 -2015) in an experimental maize field in Tuscan. The prototype involved six automatic chambers; the complete measurement cycle was of 2 hours. Each chamber was closing during 20 min and biogas accumulations were monitoring in line with IR spectrometers. Auxiliary's measurements including soil temperatures and water contents as weather data were also monitoring. All data were managed remotely with the same acquisition software installed in the prototype control unit. The operation of the prototype during the two cropping years allowed testing its major features: its ability to evaluate the temporal variation of N2O soil fluxes during a long period with weather conditions and agricultural managements and to prove the interest to have continuous measurements of fluxes. The temporal distribution of N2O fluxes indicated that emissions can be very large and discontinuous over short periods less ten days and that during about 70% of the time N2O fluxes were around detection limit of the instrumentation, evaluated to 2 ng N ha-1 day-1. N2O emission factor assessments were 1.9% in 2014
μ-Oxalato-κ4O1,O2:O1′,O2′-bis[aqua(2,2′-bipyridine-κN(nitrato-κ2O,O′lead(II

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Gang-Hong Pan

2012-10-01

Full Text Available The title compound, [Pb2(C2O4(NO32(C10H8N22(H2O2], was synthesized hydrothermally. The binuclear complex molecule is centrosymmetric, the inversion centre being located at the mid-point of the oxalate C—C bond. The PbII ion is heptacoordinated by the O atom of one water molecule, two oxalate O atoms, two nitrate O atoms and two 2,2′-bipyridine N atoms, forming an irregular coordination environemnt. Intermolecular O—H...O hydrogen bonds between water molecules and oxalate and nitrate ions result in the formation of layers parallel to (010. π–π interactions between pyridine rings in adjacent layers, with centroid–centroid distances of 3.584 (2 Å, stabilize the structural set-up.
Thermal stability of polyoxometalate compound of Keggin K8[2-SiW11O39]∙nH2O supported with SiO2

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Yunita Sari M A

2017-06-01

Full Text Available Synthesis through sol-gel method and characterization of polyoxometalate compound of K8[b2-SiW11O39]∙nH2O supported with SiO2 have been done. The functional groups of polyoxometalate compound was characterized by FT-IR spectrophotometer for the fungtional groups and the degree’s of crystalinity using XRD. The acidity of K8[b2-SiW11O39]∙nH2O/SiO2 was determined qualitative analysis using ammonia and pyridine adsorption and the quantitative analysis using potentiometric titration method. The results of FT-IR spectrum of K8[b2-SiW11O39]∙nH2O appeared at wavenumber 987.55 cm-1 (W=O, 864.11 cm-1 (W-Oe-W, 756.1 cm-1 (W-Oc-W, 3425.58 cm-1 (O-H, respectively and spectrum of K8[b2-SiW11O39]SiO2 appeared at wavenumber 956.69 cm-1 (W=O, 864.11 cm-1 (W-Oe-W, 3448.72 cm-1 (O-H, respectively. The diffraction of XRD pattern of K8[b2-SiW11O39]∙nH2O and K8[b2-SiW11O39]∙nH2O/SiO2 compounds show high crystalinity. The acidic properties showed K8[b2-SiW11O39]∙nH2O/SiO2 more acidic compared to K8[b2-The SiW11O39]∙nH2O. The qualitative analysis showed pyridine compound adsorbed more of polyoxometalate compound of K8[b2-SiW11O39]∙nH2O/SiO2. Analysis of stability showed that the K8[b2-SiW11O39]∙nH2O/SiO2 at temperature 500°C has structural changes compare to 200-400oC which was indicated from vibration at wavenumber 800-1000 cm-1. Keywords : K8[b2-SiW11O39]∙nH2O, polyoxometalate, SiO2.

Total scattering cross-sections for the systems nH2 + nH2, pH2 + pH2, nD2 + nD2, oD2 + oD2 and HD + HD for relative energies below ten milli-electron volts

International Nuclear Information System (INIS)

Johnson, D.L.

1979-01-01

Relative total scattering cross sections for nH 2 + nH 2 , pH 2 + pH 2 , nD 2 + nD 2 , oD 2 + oD 2 , and HD + HD were measured with inclined nozzle beams derived from nozzle sources and intersecting at 21 0 . Both nozzles could be varied in temperature from 4.2K to 300K to provide the velocity range for the cross sections. The use of a parahydrogen converter allowed the measurement of the pH 2 + pH 2 and oD 2 + oD 2 cross sections. Cross sections for the H 2 + H 2 were measured over a relative velocity range of 200 m/s to 1450 m/s. The nH 2 + nH 2 results show an undulation in the velocity range between 350 m/s and 400 m/s that corresponds to a l = 3 orbiting resonance. Analysis of the pH 2 + pH 2 cross section indicates a l = 4 orbiting resonance near 586 m/s. This resonance has a peak energy of 1.79 meV and a measured energy width of 1.05 meV, both which agree well with theoretical predictions. The D 2 + D 2 cross sections have been measured in the velocity range between 190 m/s and 1000 m/s. No orbiting resonances have been observed, but in the oD 2 + oD 2 cross section a deep minimum between the l = 4 and the l = 5 resonances at low velocities is clearly suggested. Initial measurements of the HD + HD cross section suggests the presence of the l = 4 orbiting resonance near a relative velocity of 300 m/s. The experimental results for each system were normalized to the total cross sections, which were convoluted to account for experimental velocity and angular dispersions. Three different potentials were considered, but a chi-square fit of the data indicates that the Schaefer and Meyer potential, which has been theoretically obtained from first principles, provides the best overall description of the hydrogen systems in the low collisional energy range
Mechanosynthesis and mechanical activation processes to the preparation of the Sr2[Srn-1TinO3n+1] Ruddlesden-Popper family

International Nuclear Information System (INIS)

Hungria, Teresa; Hungria, A.-B.; Castro, Alicia

2004-01-01

A novel mechanochemical activation route has been applied in order to obtain the n=1-4 and ∞ members of the Sr 2 [Sr n-1 Ti n O 3n+1 ] Ruddlesden-Popper series. The evolution of the (n+1)SrO:nTiO 2 powder mixtures during mechanical treatment was followed by X-ray powder diffraction in all cases. Except for the 2SrO:TiO 2 composition, SrTiO 3 was always mechanosynthesized. High-energy milling of 2SrO:TiO 2 sample resulted in the formation of nanosized Sr 2 TiO 4 , which is the only K 2 NiF 4 -type oxide prepared by mechanical treatment until now. The mechanical treatment was followed by annealing at different temperatures to establish the optimized protocol for synthesis of each member of the series. SrTiO 3 , Sr 2 TiO 4 and Sr 3 Ti 2 O 7 were obtained with very important decreases in the formation temperatures and reaction times as compared with the traditional ceramic method. Final and milled products were studied by X-ray powder diffraction at room and increasing temperatures, and by thermal analysis and scanning and high resolution transmission electron microscopy
Carbonyl(N-nitroso-N-oxido-1-naphtylamine-κ2O,O′(triphenylphosphine-κPrhodium(I acetone solvate

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T. J. Muller

2009-12-01

Full Text Available The title compound, [Rh(C10H7N2O2(C18H15P(CO]·(CH32CO, is the second structural report of a metal complex formed with the O,O′-C10H7N2O2 (neocupferrate ligand. In the crystal structure, the metal centre is surrounded by one carbonyl ligand, one triphenylphosphine ligand and the bidentate neocupferrate ligand, forming a distorted square-planar RhCO2P coordination set which is best illustrated by the small O—Rh—O bite angle of 77.74 (10°. There are no classical hydrogen-bond interactions observed for this complex.
Optimization of α-Fe{sub 2}O{sub 3}@Fe{sub 3}O{sub 4} incorporated N-TiO{sub 2} as super effective photocatalysts under visible light irradiation

Energy Technology Data Exchange (ETDEWEB)

Mohamed, Mohamed Mokhtar, E-mail: mohmok2000@yahoo.com [Benha University, Faculty of Science, Chemistry Department, Benha (Egypt); Bayoumy, W.A. [Benha University, Faculty of Science, Chemistry Department, Benha (Egypt); Goher, M.E. [National Institute of Oceanography & Fisheries, Environmental Chemistry, Cairo (Egypt); Abdo, M.H., E-mail: mh_omr@yahoo.com [National Institute of Oceanography & Fisheries, Environmental Chemistry, Cairo (Egypt); Mansour El-Ashkar, T.Y. [National Institute of Oceanography & Fisheries, Environmental Chemistry, Cairo (Egypt)

2017-08-01

Highlights: • The α-Fe{sub 2}O{sub 3}/Fe{sub 3}O{sub 4} doped n-TiO{sub 2} was synthesized via deposition-self assembly technique. • The photocatalyst 1%α-Fe{sub 2}O{sub 3}/Fe{sub 3}O{sub 4}/n-TiO{sub 2} show a remarkable performance while MB degradation. • The strong interaction between α-Fe{sub 2}O{sub 3}/Fe{sub 3}O{sub 4} and n-TiO{sub 2} plays an important role. • It exhibits a unique textural, optical and charge transfer properties. - Abstract: Well dispersed α-Fe{sub 2}O{sub 3}@Fe{sub 3}O{sub 4} nanoparticles (7 nm) supported on mesoporous nitrogen doped titanium dioxide (N-TiO{sub 2}) are synthesized by deposition self-assembly route and their performances as photocatalysts toward methylene blue (MB) degradation are evaluated. The results illustrate that the spherical yolk-shell structure of α-Fe{sub 2}O{sub 3}@Fe{sub 3}O{sub 4}@N-TiO{sub 2} at the loading of 1%; of excellent S{sub BET} (187 m{sup 2} g{sup −1}) and pore volume (0.50 cm{sup 3} g{sup −1}), achieved high photocatalytic performance for the MB degradation (20 ppm, λ > 420 nm, lamp power = 160 W) under visible light illumination (k = 0.059 min{sup −1}). The influence of the interface formation between α-Fe{sub 2}O{sub 3}@Fe{sub 3}O{sub 4} and n-TiO{sub 2} affects severely the charges separation efficiency and enhances the electron transfer to keep on the existence of Fe{sup 3+}/Fe{sup 2+} moieties; those take significant role in the reaction mechanism. The existence of the latter junction is affirmed via XRD, TEM-SAED, Raman and FTIR techniques whereas, the photogenerated charges, their separation together with their transport and recombination rates are depicted via photoluminescence, electrical conductivity, incident photon to current efficiency (IPCE), cyclic voltammetry (CV) and impedance (EIS) measurements. The catalyst loading, zero point charge, pH variation, total organic carbon (TOC%) and the effect of lamps power are thoroughly investigated. The 1%α-Fe{sub 2}O{sub 3
N loss to drain flow and N2O emissions from a corn-soybean rotation with winter rye.

Science.gov (United States)

Gillette, K; Malone, R W; Kaspar, T C; Ma, L; Parkin, T B; Jaynes, D B; Fang, Q X; Hatfield, J L; Feyereisen, G W; Kersebaum, K C

2018-03-15

Anthropogenic perturbation of the global nitrogen cycle and its effects on the environment such as hypoxia in coastal regions and increased N 2 O emissions is of increasing, multi-disciplinary, worldwide concern, and agricultural production is a major contributor. Only limited studies, however, have simultaneously investigated NO 3 - losses to subsurface drain flow and N 2 O emissions under corn-soybean production. We used the Root Zone Water Quality Model (RZWQM) to evaluate NO 3 - losses to drain flow and N 2 O emissions in a corn-soybean system with a winter rye cover crop (CC) in central Iowa over a nine year period. The observed and simulated average drain flow N concentration reductions from CC were 60% and 54% compared to the no cover crop system (NCC). Average annual April through October cumulative observed and simulated N 2 O emissions (2004-2010) were 6.7 and 6.0kgN 2 O-Nha -1 yr -1 for NCC, and 6.2 and 7.2kgNha -1 for CC. In contrast to previous research, monthly N 2 O emissions were generally greatest when N loss to leaching were greatest, mostly because relatively high rainfall occurred during the months fertilizer was applied. N 2 O emission factors of 0.032 and 0.041 were estimated for NCC and CC using the tested model, which are similar to field results in the region. A local sensitivity analysis suggests that lower soil field capacity affects RZWQM simulations, which includes increased drain flow nitrate concentrations, increased N mineralization, and reduced soil water content. The results suggest that 1) RZWQM is a promising tool to estimate N 2 O emissions from subsurface drained corn-soybean rotations and to estimate the relative effects of a winter rye cover crop over a nine year period on nitrate loss to drain flow and 2) soil field capacity is an important parameter to model N mineralization and N loss to drain flow. Published by Elsevier B.V.
Nitrification and N2O production processes in soil incubations after ammonium fertilizer application at high concentrations

Science.gov (United States)

Deppe, Marianna; Well, Reinhard; Giesemann, Anette; Flessa, Heinz

2016-04-01

High concentrations of ammonium as they occur, e.g., after point-injection of ammonium fertilizer solution according to the CULTAN fertilization technique may retard nitrification. Potential advantages in comparison to conventional fertilization include a higher N efficiency of crops, reduced nitrate leaching, and lower N2O and N2 emissions. Dynamics of nitrification due to plant uptake and dilution processes, leading to decreasing ammonium concentrations in fertilizer depots, has only poorly been studied before. Furthermore, there is little information about the relative contribution of different N2O production processes under these conditions. To elucidate the process dynamics a laboratory incubation study was conducted. After fertilization with ammonium sulfate at 5 levels (from 0 to 5000 mg NH4+-N kg-1; 20mg NO3--N kg-1 each), sandy loam soil was incubated in dynamic soil microcosms for 21 days. N2O, CH4 and CO2 fluxes as well as isotope signatures of N2O and, at three dates, NO3- and NH4+ were measured. To identify N2O production processes, acetylene inhibition (0.01 vol.%), 15N tracer approaches, and isotopomer data (15N site preference and δ18O) were used. N2O emissions were highest at 450mg NH4+-N kg-1 and declined with further increasing concentrations. At 5000 mg NH4+-N kg-1 nitrification was completely inhibited. However, approximately 90% of N2O production was inhibited by acetylene application, and there was no change in the relative contribution of nitrification and denitrification to N2O production with N level. Applying the non-equilibrium technique to our 15N tracer data revealed heterogeneous distribution of denitrification in soil, with at least two distinct NO3- pools, and spatial separation of NO3- formation and consumption. In comparison with the acetylene inhibition and 15N tracer approaches the results of the isotopomer approach were reasonable and indicated substantial contribution of nitrifier-denitrification (10-40%) to total N2O
(3-Benzoyl-1,7,7-trimethylbicyclo[2.2.1]heptan-2-olato-κ2O,Obis[2-(2-pyridylphenyl-κ2C1,N]iridium(III

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Kaijun Luo

2011-11-01

Full Text Available The title compound, [Ir(C11H8N2(C17H19O2], has an octahedral coordination geometry around the IrIII atom, retaining the cis-C,C,trans–N,N chelate disposition of the two 2-phenylpyridine ligands. The chelate rings are nearly mutually perpendicular [the interplanar angles range from 85.48 (17 to 89.17 (19°]. The two 2-(2-pyridylphenyl ligands are approximately planar, with the plane of the phenyl ring being inclined to that of the pyridine ring by 2.3 (3 and 5.1 (3° in the two ligands. The interplanar angle between the phenyl ring in 3-benzoyl-camphor and the IrO2C3 chelate ring is 35.5 (2°.
Heterojunction p-Cu2O/n-Ga2O3 diode with high breakdown voltage

Science.gov (United States)

Watahiki, Tatsuro; Yuda, Yohei; Furukawa, Akihiko; Yamamuka, Mikio; Takiguchi, Yuki; Miyajima, Shinsuke

2017-11-01

Heterojunction p-Cu2O/n-β-Ga2O3 diodes were fabricated on an epitaxially grown β-Ga2O3(001) layer. The reverse breakdown voltage of these p-n diodes reached 1.49 kV with a specific on-resistance of 8.2 mΩ cm2. The leakage current of the p-n diodes was lower than that of the Schottky barrier diode due to the higher barrier height against the electron. The ideality factor of the p-n diode was 1.31. It indicated that some portion of the recombination current at the interface contributed to the forward current, but the diffusion current was the dominant. The forward current more than 100 A/cm2 indicated the lower conduction band offset at the hetero-interface between Cu2O and Ga2O3 layers than that predicted from the bulk properties, resulting in such a high forward current without limitation. These results open the possibility of advanced device structures for wide bandgap Ga2O3 to achieve higher breakdown voltage and lower on-resistance.
Hexa-μ-acetato-1:2κ4O,O′;1:2κ2O:O;2:3κ4O,O′;2:3κ2O:O-bis(4,4′-dimethyl-2,2′-bipyridine-1κ2N,N′;3κ2N,N′-2-calcium-1,3-dizinc

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Md. Alamgir Hossain

2013-12-01

Full Text Available In the centrosymmetric trinuclear ZnII...CaII...ZnII title complex, [CaZn2(CH3COO6(C12H12N22], the CaII ion lies on an inversion centre and is octahedrally coordinated by six acetate O atoms. The ZnII ion is coordinated by two N atoms from a bidentate dimethylbipyridine ligand and three O atoms from acetate ligands bridging to the CaII ion, leading to a distorted square-pyramidal coordination sphere. The Zn...Ca distance is 3.4668 (5 Å.
Elucidating source processes of N2O fluxes following grassland-to-field-conversion using isotopologue signatures of soil-emitted N2O

Science.gov (United States)

Roth, G.; Giesemann, A.; Well, R.; Flessa, H.

2012-04-01

Conversion of grassland to arable land often causes enhanced nitrous oxide (N2O) emissions to the atmosphere. This is due to the tillage of the sward and subsequent decomposition of organic matter. Prediction of such effects is uncertain so far because emissions may differ depending on site and soil conditions. The processes of N2O turnover (nitrification, production by bacterial or fungal denitrifiers, bacterial reduction to N2) are difficult to identify, however. Isotopologue signatures of N2O such as δ18O, average δ15N (δ15Nbulk) and 15N site preference (SP = difference in δ15N between the central and peripheral N positions of the asymmetric N2O molecule) can be used to characterize N2O turnover processes using the known ranges of isotope effects of the various N2O pathways. We aim to evaluate the impact of grassland-to-field-conversion on N2O fluxes and the governing processes using isotopic signatures of emitted N2O. At two sites, in Kleve (North Rhine-Westphalia, Germany, conventional farming) and Trenthorst (Schleswig-Holstein, Germany, organic farming), a four times replicated plot experiment with (i) mechanical conversion (ploughing, maize), (ii) chemical conversion (broadband herbicide, maize per direct seed) and (iii) continuous grassland as reference was started in April 2010. In Trenthorst we additionally established a (iv) field with continuous maize cultivation as further reference. Over a period of two years, mineral nitrogen (Nmin) content was measured weekly on soil samples taken from 0-10 cm and 10-30 cm depth. Soil water content and N2O emissions were measured weekly as well. Gas samples were collected using a closed chamber system. Isotope ratio mass spectrometry was carried out on gas samples from selected high flux events to determine δ18O, δ15Nbulk and SP of N2O. δ18O and SP of N2O exhibited a relatively large range (32 to 72 ‰ and 6 to 34 ‰, respectively) indicating highly variable process dynamics. The data-set is grouped
Constraining a complex biogeochemical model for CO2 and N2O emission simulations from various land uses by model-data fusion

Science.gov (United States)

Houska, Tobias; Kraus, David; Kiese, Ralf; Breuer, Lutz

2017-07-01

This study presents the results of a combined measurement and modelling strategy to analyse N2O and CO2 emissions from adjacent arable land, forest and grassland sites in Hesse, Germany. The measured emissions reveal seasonal patterns and management effects, including fertilizer application, tillage, harvest and grazing. The measured annual N2O fluxes are 4.5, 0.4 and 0.1 kg N ha-1 a-1, and the CO2 fluxes are 20.0, 12.2 and 3.0 t C ha-1 a-1 for the arable land, grassland and forest sites, respectively. An innovative model-data fusion concept based on a multicriteria evaluation (soil moisture at different depths, yield, CO2 and N2O emissions) is used to rigorously test the LandscapeDNDC biogeochemical model. The model is run in a Latin-hypercube-based uncertainty analysis framework to constrain model parameter uncertainty and derive behavioural model runs. The results indicate that the model is generally capable of predicting trace gas emissions, as evaluated with RMSE as the objective function. The model shows a reasonable performance in simulating the ecosystem C and N balances. The model-data fusion concept helps to detect remaining model errors, such as missing (e.g. freeze-thaw cycling) or incomplete model processes (e.g. respiration rates after harvest). This concept further elucidates the identification of missing model input sources (e.g. the uptake of N through shallow groundwater on grassland during the vegetation period) and uncertainty in the measured validation data (e.g. forest N2O emissions in winter months). Guidance is provided to improve the model structure and field measurements to further advance landscape-scale model predictions.
Ammonia-evaporation-induced construction of three-dimensional NiO/g-C3N4 composite with enhanced adsorption and visible light-driven photocatalytic performance

Science.gov (United States)

Tzvetkov, George; Tsvetkov, Martin; Spassov, Tony

2018-07-01

Novel visible light-driven heterostructured NiO/g-C3N4 photocatalyst has been designed and successfully prepared via ammonia-evaporation-induced method. The synthetic strategy consists of grafting the surface of g-C3N4 with Ni(NH3)62+ complex followed by its hydrolysis at lower pH to form nano-wrinkled thin film of α-Ni(OH)2. The final NiO/g-C3N4 hybrid was obtained after calcination of the Ni(OH)2/g-C3N4 precursor at 350 °C. Scanning electron microscopy, transmission electron microscopy, X-ray diffraction, FTIR, N2 adsorption/desorption, UV-vis diffuse reflectance and photoluminescence spectroscopy were used to characterize the resulting material. Our results revealed the formation of meso-/macroporous three-dimensional hierarchical honeycomb-like structure with high BET surface area (141 m2 g-1). The photocatalytic performance of the composite under visible light (λ > 400 nm) irradiation was evaluated through degradation of Malachite Green (MG) from aqueous medium at room temperature (25 °C). For the sake of comparison, the physico-chemical and photocatalytic properties of the pristine g-C3N4 and nanostructured NiO were also examined. Results indicated that NiO/g-C3N4 is much more active than pristine g-C3N4 and NiO in the photodegradation of MG. The enhanced photocatalytic performance of the composite was mainly attributed to the combination of high adsorption capacity which facilitates the direct redox reactions of dye and the efficient inhibition of photo-generated electron-hole pair recombination. Superoxide radicals (•O2-) and photo-generated holes (h+) were found to be the main active species in the process.
p-Cu2O-shell/n-TiO2-nanowire-core heterostucture photodiodes

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Hsueh Ting-Jen

2011-01-01

Full Text Available Abstract This study reports the deposition of cuprous oxide [Cu2O] onto titanium dioxide [TiO2] nanowires [NWs] prepared on TiO2/glass templates. The average length and average diameter of these thermally oxidized and evaporated TiO2 NWs are 0.1 to 0.4 μm and 30 to 100 nm, respectively. The deposited Cu2O fills gaps between the TiO2 NWs with good step coverage to form nanoshells surrounding the TiO2 cores. The p-Cu2O/n-TiO2 NW heterostructure exhibits a rectifying behavior with a sharp turn-on at approximately 0.9 V. Furthermore, the fabricated p-Cu2O-shell/n-TiO2-nanowire-core photodiodes exhibit reasonably large photocurrent-to-dark-current contrast ratios and fast responses.
Photocatalytic Removal of Phenol under Natural Sunlight over N-TiO2-SiO2 Catalyst: The Effect of Nitrogen Composition in TiO2-SiO2

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Viet-Cuong Nguyen

2009-01-01

Full Text Available In this present work, high specific surface area and strong visible light absorption nitrogen doped TiO2-SiO2 photocatalyst was synthesized by using sol-gel coupled with hydrothermal treatment method. Nitrogen was found to improve the specific surface area while it also distorted the crystal phase of the resulting N-TiO2-SiO2 catalyst. As the N/ (TiO2-SiO2 molar ratio was more than 10%, the derived catalyst presented the superior specific surface area up to 260 m2/g. Nevertheless, its photoactivity towards phenol removal was observed to significantly decrease, which could results from the too low crystallinity. The nitrogen content in N-TiO2-SiO2 catalyst was therefore necessary to be optimized in terms of phenol removal efficiency and found at ca. 5%. Under UVA light and natural sunlight irradiation of 80 min, N(5%-TiO2-SiO2 catalyst presented the phenol decomposition efficiencies of 68 and 100%, respectively. It was also interestingly found in this study that the reaction rate was successfully expressed using a Langmuir-Hinshelwood (L-H model, indicating the L-H nature of photocatalytic phenol decomposition reaction on the N-TiO2-SiO2 catalyst.
Statistical modeling of the reactions Fe(+) + N2O → FeO(+) + N2 and FeO(+) + CO → Fe(+) + CO2.

Science.gov (United States)

Ushakov, Vladimir G; Troe, Jürgen; Johnson, Ryan S; Guo, Hua; Ard, Shaun G; Melko, Joshua J; Shuman, Nicholas S; Viggiano, Albert A

2015-08-14

The rates of the reactions Fe(+) + N2O → FeO(+) + N2 and FeO(+) + CO → Fe(+) + CO2 are modeled by statistical rate theory accounting for energy- and angular momentum-specific rate constants for formation of the primary and secondary cationic adducts and their backward and forward reactions. The reactions are both suggested to proceed on sextet and quartet potential energy surfaces with efficient, but probably not complete, equilibration by spin-inversion of the populations of the sextet and quartet adducts. The influence of spin-inversion on the overall reaction rate is investigated. The differences of the two reaction rates mostly are due to different numbers of entrance states (atom + linear rotor or linear rotor + linear rotor, respectively). The reaction Fe(+) + N2O was studied either with (6)Fe(+) or with (4)Fe(+) reactants. Differences in the rate constants of (6)Fe(+) and (4)Fe(+) reacting with N2O are attributed to different contributions from electronically excited potential energy surfaces, such as they originate from the open-electronic shell reactants.
(4-Chloroacetanilido-κ2N,Obis[2-(pyridin-2-ylphenyl-κ2C1,N]iridium(III

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Lijun Sun

2013-02-01

Full Text Available In the neutral mononuclear iridium(III title compound, [Ir(C8H7ClNO(C11H8N2], the IrIII atom adopts an octahedral geometry, and is coordinated by two 2-phenylpyridyl ligands and one anionic 4-chloroacetanilide ligand. The 2-phenylpyridyl ligands are arranged in a cis-C,C′ and cis-N,N′ fashion. Each 2-phenylpyridyl ligand forms a five-membered ring with the IrIII atom. The 2-phenylpyridyl planes are perpendicular to each other [dihedral angle = 89.9 (1°]. The Ir—C and Ir—N bond lengths are comparable to those reported for related iridium(III 2-phenylpyridyl complexes. The remaining two coordination sites are occupied by the amidate N and O atoms, which form a four-membered ring with the iridium atom (Ir—N—C—O. The amidate plane is nearly perpendicular to both 2-phenylpyridyl ligands [dihedral angles = 87.8 (2 and 88.3 (2°].
Cocrystals of 6-propyl-2-thiouracil: N-H···O versus N-H···S hydrogen bonds.

Science.gov (United States)

Tutughamiarso, Maya; Egert, Ernst

2011-11-01

In order to investigate the relative stability of N-H···O and N-H···S hydrogen bonds, we cocrystallized the antithyroid drug 6-propyl-2-thiouracil with two complementary heterocycles. In the cocrystal pyrimidin-2-amine-6-propyl-2-thiouracil (1/2), C(4)H(5)N(3)·2C(7)H(10)N(2)OS, (I), the `base pair' is connected by one N-H···S and one N-H···N hydrogen bond. Homodimers of 6-propyl-2-thiouracil linked by two N-H···S hydrogen bonds are observed in the cocrystal N-(6-acetamidopyridin-2-yl)acetamide-6-propyl-2-thiouracil (1/2), C(9)H(11)N(3)O(2)·2C(7)H(10)N(2)OS, (II). The crystal structure of 6-propyl-2-thiouracil itself, C(7)H(10)N(2)OS, (III), is stabilized by pairwise N-H···O and N-H···S hydrogen bonds. In all three structures, N-H···S hydrogen bonds occur only within R(2)(2)(8) patterns, whereas N-H···O hydrogen bonds tend to connect the homo- and heterodimers into extended networks. In agreement with related structures, the hydrogen-bonding capability of C=O and C=S groups seems to be comparable.
Structures and Spectroscopic Properties of F-(H2O) n with n = 1-10 Clusters from a Global Search Based On Density Functional Theory.

Science.gov (United States)

Shi, Ruili; Wang, Pengju; Tang, Lingli; Huang, Xiaoming; Chen, Yonggang; Su, Yan; Zhao, Jijun

2018-04-05

Using a genetic algorithm incorporated in density functional theory, we explore the ground state structures of fluoride anion-water clusters F - (H 2 O) n with n = 1-10. The F - (H 2 O) n clusters prefer structures in which the F - anion remains at the surface of the structure and coordinates with four water molecules, as the F - (H 2 O) n clusters have strong F - -H 2 O interactions as well as strong hydrogen bonds between H 2 O molecules. The strong interaction between the F - anion and adjacent H 2 O molecule leads to a longer O-H distance in the adjacent molecule than in an individual water molecule. The simulated infrared (IR) spectra of the F - (H 2 O) 1-5 clusters obtained via second-order vibrational perturbation theory (VPT2) and including anharmonic effects reproduce the experimental results quite well. The strong interaction between the F - anion and water molecules results in a large redshift (600-2300 cm -1 ) of the adjacent O-H stretching mode. Natural bond orbital (NBO) analysis of the lowest-energy structures of the F - (H 2 O) 1-10 clusters illustrates that charge transfer from the lone pair electron orbital of F - to the antibonding orbital of the adjacent O-H is mainly responsible for the strong interaction between the F - anion and water molecules, which leads to distinctly different geometric and vibrational properties compared with neutral water clusters.
[Pr2(pdc3(Hpdc(H2O4]n·n(H3hp·8n(H2O, a One-Dimensional Coordination Polymer Containing PrO6N3 Tri-Capped Trigonal Prisms and PrO8N Mono-Capped Square Anti-Prisms (H2pdc = Pyridine 2,6-Dicarboxylic Acid, C7H5NO4; 3hp = 3-Hydroxy Pyridine, C5H5NO

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Shahzad Sharif

2012-08-01

Full Text Available The synthesis, structure and some properties of the one-dimensional coordination polymer, [Pr2(pdc3(Hpdc]n·n(H3hp·8n(H2O, (H2pdc = pyridine 2,6-dicarboxylic acid, C7H5NO4; 3hp = 3-hydroxypyridine, C5H5NO are described. One of the Pr3+ ions is coordinated by two O,N,O-tridentate pdc2− ligands and one tridentate Hpdc− anion to generate a fairly regular PrO6N3 tri-capped trigonal prism, with the N atoms acting as the caps. The second Pr3+ ion is coordinated by one tridentate pdc2− dianion, four water molecules and two monodentate bridging pdc2− ligands to result in a PrO8N coordination polyhedron that approximates to a mono-capped square-anti-prism. The ligands bridge the metal-atom nodes into a chain, which extends in the [100] direction. The H3hp+ cation and uncoordinated water molecules occupy the inter-chain regions and an N–HLO and numerous O–HLO hydrogen bonds consolidate the structure. The H3hp+ species appears to intercalate between pendant pdc rings to consolidate the polymeric structure. Crystal data: 1 (C33H43N5O29Pr2, Mr = 1255.54, triclinic, (No. 2, Z = 2, a = 13.2567(1 Å, b = 13.6304(2 Å, c = 13.6409(2 Å, α = 89.695(1°, β = 63.049(1°, γ = 86.105(1°, V = 2191.16(5 Å3, R(F = 0.033, wR(F2 = 0.084.
Origin of visible-light sensitivity in N-doped TiO2 films

International Nuclear Information System (INIS)

Nakano, Yoshitaka; Morikawa, Takeshi; Ohwaki, Takeshi; Taga, Yasunori

2007-01-01

We report on visible-light sensitivity in N-doped TiO 2 (TiO 2 :N) films that were deposited on n + -GaN/Al 2 O 3 substrates by reactive magnetron sputtering and subsequently crystallized by annealing at 550 deg. C in flowing N 2 gas. The N-doping concentration was ∼8.8%, as determined by X-ray photoelectron spectroscopy measurements. From transmission electron microscopic observations and optical absorption measurements, yellow-colored TiO 2 :N samples showed an enhanced granular structure and strong absorption in the visible-light region. Photoelectron spectroscopy in air measurements showed a noticeable decrease in ionization energy of TiO 2 by the N doping. Deep-level optical spectroscopy measurements revealed two characteristic deep levels located at ∼1.18 and ∼2.48 eV below the conduction band. The 1.18 eV level is probably attributable to the O vacancy state and can be active as an efficient generation-recombination center. The pronounced 2.48 eV band is newly introduced by the N doping and contributes to band-gap narrowing of TiO 2 by mixing with the O 2p valence band. Therefore, this localized intraband is probably one origin of visible-light sensitivity in TiO 2 :N

Nitrous Oxide (N2O production in axenic Chlorella vulgaris microalgae cultures: evidence, putative pathways, and potential environmental impacts

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B. Guieysse

2013-10-01

Full Text Available Using antibiotic assays and genomic analysis, this study demonstrates nitrous oxide (N2O is generated from axenic Chlorella vulgaris cultures. In batch assays, this production is magnified under conditions favouring intracellular nitrite accumulation, but repressed when nitrate reductase (NR activity is inhibited. These observations suggest N2O formation in C. vulgaris might proceed via NR-mediated nitrite reduction into nitric oxide (NO acting as N2O precursor via a pathway similar to N2O formation in bacterial denitrifiers, although NO reduction to N2O under oxia remains unproven in plant cells. Alternatively, NR may reduce nitrite to nitroxyl (HNO, the latter being known to dimerize to N2O under oxia. Regardless of the precursor considered, an NR-mediated nitrite reduction pathway provides a unifying explanation for correlations reported between N2O emissions from algae-based ecosystems and NR activity, nitrate concentration, nitrite concentration, and photosynthesis repression. Moreover, these results indicate microalgae-mediated N2O formation might significantly contribute to N2O emissions in algae-based ecosystems (e.g. 1.38–10.1 kg N2O-N ha−1 yr−1 in a 0.25 m deep raceway pond operated under Mediterranean climatic conditions. These findings have profound implications for the life cycle analysis of algae biotechnologies and our understanding of the global biogeochemical nitrogen cycle.
Crystal structure and optical property of complex perovskite oxynitrides ALi0.2Nb0.8O2.8N0.2, ANa0.2Nb0.8O2.8N0.2, and AMg0.2Nb0.8O2.6N0.4 (A = Sr, Ba)

Science.gov (United States)

Moon, Keon Ho; Avdeev, Maxim; Kim, Young-Il

2017-10-01

Oxynitride type complex perovskites AM0.2Nb0.8O3-xNx (A = Sr, Ba; M = Li, Na, Mg) were newly synthesized by the solid state diffusion of Li+, Na+, or Mg2+ into the layered oxide, A5Nb4O15, with concurrent O/N substitution. Neutron and synchrotron X-ray Rietveld refinement showed that SrLi0.2Nb0.8O2.8N0.2, SrNa0.2Nb0.8O2.8N0.2, and SrMg0.2Nb0.8O2.6N0.4 had body-centered tetragonal symmetry (I4/mcm), while those with A = Ba had simple cubic symmetry (Pm 3 ̅ m). In the tetragonal Sr-compounds, the nitrogen atoms were localized on the c-axial 4a site. However, the octahedral cations, M/Nb (M = Li, Na, Mg) were distributed randomly in all six compounds. The lattice volume of AM0.2Nb0.8O3-xNx was dependent on various factors including the type of A and the electronegativity of M. Compared to the simple perovskites, ANbO2N (A = Sr, Ba), AM0.2Nb0.8O3-xNx had wider band gaps (1.76-2.15 eV for A = Sr and 1.65-2.10 eV for A = Ba), but significantly lower sub-gap absorption.
Chlorine activation by N2O5: simultaneous, in situ detection of ClNO2 and N2O5 by chemical ionization mass spectrometry

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J. A. Thornton

2009-05-01

Full Text Available We report a new method for the simultaneous in situ detection of nitryl chloride (ClNO2 and dinitrogen pentoxide (N2O5 using chemical ionization mass spectrometry (CIMS. The technique relies on the formation and detection of iodide ion-molecule clusters, I(ClNO2− and I(N2O5−. The novel N2O5 detection scheme is direct. It does not suffer from high and variable chemical interferences, which are associated with the typical method of nitrate anion detection. We address the role of water vapor, CDC electric field strength, and instrument zero determinations, which influence the overall sensitivity and detection limit of this method. For both species, the method demonstrates high sensitivity (>1 Hz/pptv, precision (~10% for 100 pptv in 1 s, and accuracy (~20%, the latter ultimately determined by the nitrogen dioxide (NO2 cylinder calibration standard and characterization of inlet effects. For the typically low background signals (S/N ratios of 2 for 1 pptv in 60 s averages, but uncertainty associated with the instrumental zero currently leads to an ultimate detection limit of ~5 pptv for both species. We validate our approach for the simultaneous in situ measurement of ClNO2 and N2O5 while on board the R/V Knorr as part of the ICEALOT 2008 Field Campaign.
Quantification of nitrous oxide (N2O) emissions and soluble microbial product (SMP) production by a modified AOB-NOB-N2O-SMP model.

Science.gov (United States)

Kim, MinJeong; Wu, Guangxue; Yoo, ChangKyoo

2017-03-01

A modified AOB-NOB-N 2 O-SMP model able to quantify nitrous oxide (N 2 O) emissions and soluble microbial product (SMP) production during wastewater treatment is proposed. The modified AOB-NOB-N 2 O-SMP model takes into account: (1) two-step nitrification by ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB), (2) N 2 O production by AOB denitrification under oxygen-limited conditions and (3) SMP production by microbial growth and endogenous respiration. Validity of the modified model is demonstrated by comparing the simulation results with experimental data from lab-scale sequencing batch reactors (SBRs). To reliably implement the modified model, a model calibration that adjusts model parameters to fit the model outputs to the experimental data is conducted. The results of this study showed that the modeling accuracy of the modified AOB-NOB-N 2 O-SMP model increases by 19.7% (NH 4 ), 51.0% (NO 2 ), 57.8% (N 2 O) and 16.7% (SMP) compared to the conventional model which does not consider the two-step nitrification and SMP production by microbial endogenous respiration. Copyright © 2016 Elsevier Ltd. All rights reserved.
Microbial CH4 and N2O consumption in acidic wetlands

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Steffen eKolb

2012-03-01

Full Text Available Acidic wetlands are global sources of the atmospheric greenhouse gases methane (CH4, and nitrous oxide (N2O. Consumption of both atmospheric gases has been observed in various acidic wetlands, but information on the microbial mechanisms underlying these phenomena is scarce. A substantial amount of CH4 is consumed in sub soil by aerobic methanotrophs at anoxic–oxic interfaces (e.g., tissues of Sphagnum mosses, rhizosphere of vascular plant roots. Methylocystis-related species are likely candidates that are involved in the consumption of atmospheric CH4 in acidic wetlands. Oxygen availability regulates the activity of methanotrophs of acidic wetlands. Other parameters impacting on the methanotroph-mediated CH4 consumption have not been systematically evaluated. N2O is produced and consumed by microbial denitrification, thus rendering acidic wetlands as temporary sources or sinks for N2O. Denitrifier communities in such ecosystems are diverse, and largely uncultured and/or new, and environmental factors that control their consumption activity are unresolved. Analyses of the composition of N2O reductase genes in acidic wetlands suggest that acid-tolerant Proteobacteria have the potential to mediate N2O consumption in such soils. Thus, the fragmented current state of knowledge raises open questions concerning methanotrophs and dentrifiers that consume atmospheric CH4 and N2O in acidic wetlands.
Relationship between interlayer hydration and photocatalytic water splitting of A'1-xNaxCa2Ta3O10.nH2O (A'=K and Li)

International Nuclear Information System (INIS)

Mitsuyama, Tomohiro; Tsutsumi, Akiko; Sato, Sakiko; Ikeue, Keita; Machida, Masato

2008-01-01

Partial replacement of alkaline metals in anhydrous KCa 2 Ta 3 O 10 and LiCa 2 Ta 3 O 10 was studied to control interlayer hydration and photocatalytic activity for water splitting under UV irradiation. A' 1-x Na x Ca 2 Ta 3 O 10 .nH 2 O (A'=K and Li) samples were synthesized by ion exchange of CsCa 2 Ta 3 O 10 in mixed molten nitrates at 400 deg. C. In K 1-x Na x Ca 2 Ta 3 O 10 .nH 2 O, two phases with the orthorhombic (C222) and tetragonal (I4/mmm) structures were formed at x≤0.7 and x≥0.5, respectively. Upon replacement by Na + having a larger enthalpy of hydration (ΔH h 0 ), the interlayer hydration occurred at x≥0.3 and the hydration number (n) was increased monotonically with an increase of x. Li 1-x Na x Ca 2 Ta 3 O 10 .nH 2 O showed a similar hydration behavior, but the phase was changed from I4/mmm (x 1-x Na x Ca 2 Ta 3 O 10 .nH 2 O exhibited the activity increasing in consistent with n, whereas Li 1-x Na x Ca 2 Ta 3 O 10 .nH 2 O exhibited the activity maximum at x=0.77, where the rates of H 2 /O 2 evolution were nearly doubled compared with those for end-member compositions (x=0 and 1). - Graphical abstract: The partial substitution of Na in the interlayer of anhydrous-layered perovskite has been found as useful structural modification toward highly active hydrated photocatalysts
Crystal structure of triaqua(1,10-phenanthroline-κ2N,N′(2,4,5-trifluoro-3-methoxybenzoato-κO1cobalt(II 2,4,5-trifluoro-3-methoxybenzoate

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Junshan Sun

2014-11-01

Full Text Available The title salt, [Co(C8H4F3O3(C12H8N2(H2O3](C8H4F3O3, was obtained under solvothermal conditions by the reaction of 2,4,5-trifluoro-3-methoxybenzoic acid with CoCl2 in the presence of 1,10-phenanthroline (phen. The CoII ion is octahedrally coordinated by two N atoms [Co—N = 2.165 (2 and 2.129 (2 Å] from the phen ligand, by one carboxylate O atom [Co—O = 2.107 (1 Å] and by three O atoms from water molecules [Co—O = 2.093 (1, 2.102 (1 and 2.114 (1 Å]. The equatorial positions of the slightly distorted octahedron are occupied by the N atoms, the carboxylate O and one water O atom. An intra- and intermolecular O—H...O hydrogen-bonding network between the water-containing complex cation and the organic anion leads to the formation of ribbons parallel to [010].
Bis(1,10-phenanthroline-κ2N,N′(sulfato-κ2O,O′cobalt(II propane-1,3-diol solvate

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Kai-Long Zhong

2010-03-01

Full Text Available The title compound, [Co(SO4(C12H8N22]·C3H8O2, was obtained unexpectedly as a by-product during an attempt to synthesize a mixed-ligand complex of CoII with 1,10-phenanthroline (phen and melamine via a solvothermal reaction. The CoII metal ions are in a distorted octahedral coordination environment formed by four N atoms from two chelating phen ligands and two O atoms from a bidentate sulfate ligand. The two chelating N2C2 groups are almost perpendicular to each other [dihedral angle = 80.06 (8°]. A twofold rotation axis passes through the Co and S atoms, and also through the central C atom of the propane-1,3-diol solvent molecule. Intermolecular O—H...O hydrogen bonds help to stabilize the structure.
Broadband sensitized white light emission of g-C{sub 3}N{sub 4}/Y{sub 2}MoO{sub 6}:Eu{sup 3+} composite phosphor under near ultraviolet excitation

Energy Technology Data Exchange (ETDEWEB)

Han, Bing, E-mail: hanbing@zzuli.edu.cn [School of Material and Chemical Engineering, Zhengzhou University of Light Industry, Zhengzhou 450002 (China); Xue, Yongfei; Li, Pengju [School of Material and Chemical Engineering, Zhengzhou University of Light Industry, Zhengzhou 450002 (China); Zhang, Jingtao [School of Food and Bioengineering, Zhengzhou University of Light Industry, Zhengzhou 450002 (China); Zhang, Jie [School of Material and Chemical Engineering, Zhengzhou University of Light Industry, Zhengzhou 450002 (China); Shi, Hengzhen, E-mail: shihz@zzuli.edu.cn [School of Material and Chemical Engineering, Zhengzhou University of Light Industry, Zhengzhou 450002 (China)

2015-12-15

The g-C{sub 3}N{sub 4}/Y{sub 2}MoO{sub 6}:Eu{sup 3+} composite phosphors were synthesized and characterized by X-ray diffraction, Fourier transform-infrared spectroscopy, ultraviolet visible diffuse reflection spectra, photoluminescence spectra and luminescence decay curves. Under the excitation of 360 nm near ultraviolet light, these composite phosphors show tunable emission from blue to red region, in which white light emission can be obtained in term of appropriate quality proportion of Y{sub 2}MoO{sub 6}:Eu{sup 3+} relative to g-C{sub 3}N{sub 4}/Y{sub 2}MoO{sub 6}:Eu{sup 3+}. In addition, the emission color can be also dependent on the excitation wavelength in g-C{sub 3}N{sub 4}/Y{sub 2}MoO{sub 6}:Eu{sup 3+} composite phosphor. - Graphical abstract: Under the excitation of 360 nm near ultraviolet light, the g-C{sub 3}N{sub 4}/Y{sub 2}MoO{sub 6}:Eu{sup 3+} composite phosphors show tunable emission from blue to red region, in which white light emission can be obtained. - Highlights: • The g-C3N4/Y2MoO6:Eu{sup 3+} composite phosphors were synthesized and characterized. • White light emission was realized in the g-C3N4/Y2MoO6:Eu{sup 3+} composites under UV excitation. • A novel idea to realize the broadband sensitized white light emission in phosphors was provided.
An experimental technique for the direct measurement of N2O5 reactivity on ambient particles

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T. H. Bertram

2009-06-01

Full Text Available An experimental approach for the direct measurement of trace gas reactivity on ambient aerosol particles has been developed. The method utilizes a newly designed entrained aerosol flow reactor coupled to a custom-built chemical ionization mass spectrometer. The experimental method is described via application to the measurement of the N2O5 reaction probability, γ (N2O5. Laboratory investigations on well characterized aerosol particles show that measurements of γ (N2O5 observed with this technique are in agreement with previous observations, using conventional flow tube methods, to within ±20% at atmospherically relevant particle surface area concentrations (0–1000 μm2 cm−3. Uncertainty in the measured γ (N2O5 is discussed in the context of fluctuations in potential ambient biases (e.g., temperature, relative humidity and trace gas loadings. Under ambient operating conditions we estimate a single-point uncertainty in γ (N2O5 that ranges between ± (1.3×10-2 + 0.2×γ (N2O5, and ± (1.3×10-3 + 0.2×γ (N2O5 for particle surface area concentrations of 100 to 1000 μm2 cm−3, respectively. Examples from both laboratory investigations and field observations are included alongside discussion of future applications for the reactivity measurement and optimal deployment locations and conditions.
Vertical segregation among pathways mediating nitrogen loss (N2 and N2O production) across the oxygen gradient in a coastal upwelling ecosystem

Science.gov (United States)

Galán, Alexander; Thamdrup, Bo; Saldías, Gonzalo S.; Farías, Laura

2017-10-01

The upwelling system off central Chile (36.5° S) is seasonally subjected to oxygen (O2)-deficient waters, with a strong vertical gradient in O2 (from oxic to anoxic conditions) that spans a few metres (30-50 m interval) over the shelf. This condition inhibits and/or stimulates processes involved in nitrogen (N) removal (e.g. anammox, denitrification, and nitrification). During austral spring (September 2013) and summer (January 2014), the main pathways involved in N loss and its speciation, in the form of N2 and/or N2O, were studied using 15N-tracer incubations, inhibitor assays, and the natural abundance of nitrate isotopes along with hydrographic information. Incubations were developed using water retrieved from the oxycline (25 m depth) and bottom waters (85 m depth) over the continental shelf off Concepción, Chile. Results of 15N-labelled incubations revealed higher N removal activity during the austral summer, with denitrification as the dominant N2-producing pathway, which occurred together with anammox at all times. Interestingly, in both spring and summer maximum potential N removal rates were observed in the oxycline, where a greater availability of oxygen was observed (maximum O2 fluctuation between 270 and 40 µmol L-1) relative to the hypoxic bottom waters ( multiple N-cycling processes are modulating the isotopic nitrate composition over the shelf off central Chile during spring and summer. N removal processes in this coastal system appear to be related to the availability and distribution of oxygen and particles, which are a source of organic matter and the fuel for the production of other electron donors (i.e. ammonium) and acceptors (i.e. nitrate and nitrite) after its remineralization. These results highlight the links between several pathways involved in N loss. They also establish that different mechanisms supported by alternative N substrates are responsible for substantial accumulation of N2O, which are frequently observed as hotspots in the
(Acetato-κO(aqua-κO(2-{bis[(3,5-dimethyl-1H-pyrazol-1-yl-κN2methyl]amino-κN}ethanol-κOnickel(II perchlorate monohydrate

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Jia Zhou

2012-04-01

Full Text Available In the structure of the title complex, [Ni(CH3CO2(C14H23N5O(H2O]ClO4·H2O, the NiII centre has a distorted octahedral environment defined by one O and three N atoms derived from the tetradentate ligand, and two O atoms, one from a water molecule and the other from an acetate anion. The molecules are connected into a three-dimensional architecture by O—H...O hydrogen bonds. The perchlorate anion is disordered over two positions; the major component has a site-occupancy factor of 0.525 (19.
Bis(2,2'-bipyridyl-κN,N')(carbonato-κO,O')cobalt(III) bromide trihydrate.

Science.gov (United States)

Ma, Peng-Tao; Wang, Yu-Xia; Zhang, Guo-Qian; Li, Ming-Xue

2007-12-06

The title complex, [Co(CO(3))(C(10)H(8)N(2))(2)]Br·3H(2)O, is isostructural with the chloride analogue. The six-coordinated octahedral [Co(2,2'-bipy)(2)CO(3)](+) cation (2,2'-bipy is 2,2'-bipyrid-yl), bromide ion and water mol-ecules are linked together via O-H⋯Br and O-H⋯O hydrogen bonds, generating a one-dimensional chain.
Highly luminescent S,N co-doped carbon quantum dots-sensitized chemiluminescence on luminol-H2 O2 system for the determination of ranitidine.

Science.gov (United States)

Chen, Jianqiu; Shu, Juan; Chen, Jiao; Cao, Zhiran; Xiao, An; Yan, Zhengyu

2017-05-01

S,N co-doped carbon quantum dots (N,S-CQDs) with super high quantum yield (79%) were prepared by the hydrothermal method and characterized by transmission electron microscopy, photoluminescence, UV-Vis spectroscopy and Fourier transformed infrared spectroscopy. N,S-CQDs can enhance the chemiluminescence intensity of a luminol-H 2 O 2 system. The possible mechanism of the luminol-H 2 O 2 -(N,S-CQDs) was illustrated by using chemiluminescence, photoluminescence and ultraviolet analysis. Ranitidine can quench the chemiluminescence intensity of a luminol-H 2 O 2 -N,S-CQDs system. So, a novel flow-injection chemiluminescence method was designed to determine ranitidine within a linear range of 0.5-50 μg ml -1 and a detection limit of 0.12 μg ml -1 . The method shows promising application prospects. Copyright © 2016 John Wiley & Sons, Ltd.
Hydrazinium lanthanide oxalates: synthesis, structure and thermal reactivity of N_2H_5[Ln_2(C_2O_4)_4(N_2H_5)].4H_2O, Ln = Ce, Nd

International Nuclear Information System (INIS)

De Almeida, Lucie; Grandjean, Stephane; Abraham, Francis; Rivenet, Murielle; Patisson, Fabrice

2014-01-01

New hydrazinium lanthanide oxalates N_2H_5[Ln_2(C_2O_4)_4(N_2H_5)].4H_2O, Ln = Ce (Ce-H_yO_x) and Nd (Nd- H_yO_x), were synthesized by hydrothermal reaction at 150 C between lanthanide nitrate, oxalic acid and hydrazine solutions. The structure of the Nd compound was determined from single-crystal X-ray diffraction data, space group P2_1/c with a = 16.315(4), b = 12.127(3), c = 11.430(2) Angstroms, β = 116.638(4) degrees, V = 2021.4(7) Angstroems"3, Z = 4, and R1 = 0.0313 for 4231 independent reflections. Two distinct neodymium polyhedra are formed, NdO_9 and NdO_8N, an oxygen of one monodentate oxalate in the former being replaced by a nitrogen atom of a coordinated hydrazinium ion in the latter. The infrared absorption band at 1005 cm"-"1 confirms the coordination of N_2H_5"+ to the metal. These polyhedra are connected through μ"2 and μ"3 oxalate ions to form an anionic three-dimensional neodymium-oxalate arrangement. A non-coordinated charge-compensating hydrazinium ion occupies, with water molecules, the resulting tunnels. The N-N stretching frequencies of the infrared spectra demonstrate the existence of the two types of hydrazine ions. Thermal reactivity of these hydrazinium oxalates and of the mixed isotypic Ce/Nd (CeNd-H_yO_x) oxalate were studied by using thermogravimetric and differential thermal analyses coupled with gas analyzers, and high temperature X-ray diffraction. Under air, fine particles of CeO_2 and Ce_0_._5Nd_0_._5O_1_._7_5 are formed at low temperature from Ce-H_yO_x and CeNd-H_yO_x, respectively, thanks to a decomposition/oxidation process. Under argon flow, dioxy-mono-cyanamides Ln_2O_2CN_2 are formed. (authors)
(Pyridine-2-aldoximato-κ2N,N′bis[2-(pyridin-2-ylphenyl-κ2C1,N]iridium(III

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Bimal Chandra Singh

2013-03-01

Full Text Available In the title complex, [Ir(C11H8N2(C6H5N2O], the octahedrally coordinated IrIII atom is bonded to two 2-(pyridin-2-ylphenyl ligands, through two phenyl C and two pydidine N atoms, and to one pyridine-2-aldoxime ligand through a pyridine N and an oxime N atom. The oxime O atom of the aldoxime unit forms intermolecular C—H...O hydrogen bonds, which result in a two-dimensional hydrogen-bonded polymeric network parallel to (100. C—H...π interactions are also observed.
Band-gap narrowing of TiO2 films induced by N-doping

International Nuclear Information System (INIS)

Nakano, Y.; Morikawa, T.; Ohwaki, T.; Taga, Y.

2006-01-01

N-doped TiO 2 films were deposited on n + -GaN/Al 2 O 3 substrates by reactive magnetron sputtering and subsequently crystallized by annealing at 550 o C in flowing N 2 gas. The N-doping concentration was ∼8.8%, as determined from X-ray photoelectron spectroscopy measurements. Deep-level optical spectroscopy measurements revealed two characteristic deep levels located at 1.18 and 2.48 eV below the conduction band. The 1.18 eV level is probably attributable to the O vacancy state and can be active as an efficient generation-recombination center. Additionally, the 2.48 eV band is newly introduced by the N-doping and contributes to band-gap narrowing by mixing with the O 2p valence band
Mitigation of nitrous oxide (N2 O) emission from swine wastewater treatment in an aerobic bioreactor packed with carbon fibers.

Science.gov (United States)

Yamashita, Takahiro; Yamamoto-Ikemoto, Ryoko; Yokoyama, Hiroshi; Kawahara, Hirofumi; Ogino, Akifumi; Osada, Takashi

2015-03-01

Mitigation of nitrous oxide (N2 O) emission from swine wastewater treatment was demonstrated in an aerobic bioreactor packed with carbon fibers (CF reactor). The CF reactor had a demonstrated advantage in mitigating N2 O emission and avoiding NOx (NO3 + NO2 ) accumulation. The N2 O emission factor was 0.0003 g N2 O-N/gTN-load in the CF bioreactor compared to 0.03 gN2 O-N/gTN-load in an activated sludge reactor (AS reactor). N2 O and CH4 emissions from the CF reactor were 42 g-CO2 eq/m(3) /day, while those from the AS reactor were 725 g-CO2 eq/m(3) /day. The dissolved inorganic nitrogen (DIN) in the CF reactor removed an average of 156 mg/L of the NH4 -N, and accumulated an average of 14 mg/L of the NO3 -N. In contrast, the DIN in the AS reactor removed an average 144 mg/L of the NH4 -N and accumulated an average 183 mg/L of the NO3 -N. NO2 -N was almost undetectable in both reactors. © 2014 Japanese Society of Animal Science.
Enhanced visible-light photocatalytic decomposition of 2,4-dichlorophenoxyacetic acid over ZnIn_2S_4/g-C_3N_4 photocatalyst

International Nuclear Information System (INIS)

Qiu, Pengxiang; Yao, Jinhua; Chen, Huan; Jiang, Fang; Xie, Xianchuan

2016-01-01

Highlights: • A novel flower-on-sheet ZnIn_2S_4/g-C_3N_4 nanocomposite was synthesized. • ZnIn_2S_4/g-C_3N_4 showed high visible light catalytic activity for 2,4-D degradation. • The photocatalytic degradation pathway of 2,4-D was investigated. - Abstract: ZnIn_2S_4/g-C_3N_4 heterojunction photocatalyst was successfully synthesized via a simple hydrothermal method and applied to visible-light photocatalytic decomposition of 2,4-dichlorophenoxyacetic acid (2,4-D) from aqueous phase. The flower-like ZnIn_2S_4 particles were dispersed on the surface of g-C_3N_4 nanosheets in the ZnIn_2S_4/g-C_3N_4 composite. The composite showed higher separation rate of electron-hole pairs as compared to ZnIn_2S_4 and g-C_3N_4. Consequently, the ZnIn_2S_4/g-C_3N_4 composite exhibited enhanced visible light photocatalytic decomposition efficiency of 2,4-D, within 20% ZnIn_2S_4/g-C_3N_4 composite owning the highest photocatalytic efficiency and initial rate. The initial rates of 2,4-D degradation on g-C_3N_4, ZnIn_2S_4, and 20% ZnIn_2S_4/g-C_3N_4 were 1.23, 0.57 and 3.69 mmol/(g_c_a_t h), respectively. The h"+ and O_2"·"− were found to be the dominant active species for 2,4-D decomposition. The photocatalytic degradation pathways of 2,4-D by ZnIn_2S_4/g-C_3N_4 under visible light irradiation were explored. The ZnIn_2S_4/g-C_3N_4 composite displayed high photostability in recycling tests, reflecting its promising potential as an effective visible light photocatalyst for 2,4-D treatment.
HIDROGENACIÓN DE CROTONALDEHÍDO SOBRE CATALIZADORES Ir/TiO2-SiO2

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HUGO ROJAS

2009-01-01

Full Text Available Se estudió la hidrogenación de crotonaldehído en fase líquida, sobre catalizadores Ir/TiO2-SiO2; este aldehído es altamente contaminante y proviene de fuentes tan diversas como humo de tabaco, gases de escape de motores de gasolina o diesel y humo de combustión de madera [1]. El objetivo principal de esta investigación fue la obtención del alcohol insaturado (crotil alcohol. A partir de los estudios realizados logró demostrarse que un aumento en el contenido de TiO2, lo mismo que la reducción de los catalizadores a altas temperaturas favorece parámetros como selectividad hacia el producto de interés, actividad catalítica y en general se logró mejorar de manera notable los niveles de conversión. El comportamiento observado se atribuyó principalmente a la fuerte influencia del efecto SMSI (Strong Metal Support Interaction, presente a altas temperaturas en óxidos parcialmente reducibles.

Bis(1,10-phenanthroline-κ2N,N′(sulfato-κ2O,O′cobalt(II butane-2,3-diol monosolvate

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Shi-Juan Wang

2011-04-01

Full Text Available In the title compound, [Co(SO4(C12H8N22]·C4H10O2, the Co2+ ion has a distorted octahedral coordination environment composed of four N atoms from two chelating 1,10-phenanthroline ligands and two O atoms from an O,O′-bidentate sulfate anion. The dihedral angle between the two chelating N2C2 groups is 83.48 (1°. The Co2+ ion, the S atom and the mid-point of the central C—C bond of the butane-2,3-diol solvent molecule are situated on twofold rotation axes. The molecules of the complex and the solvent molecules are held together by pairs of symmetry-related O—H...O hydrogen bonds with the uncoordinated O atoms of the sulfate ions as acceptors. The solvent molecule is disordered over two sets of sites with site occupancies of 0.40 and 0.60.
Measuring CO ₂ and N ₂ O Mass Transfer into GAP-1 CO ₂ –Capture Solvents at Varied Water Loadings

Energy Technology Data Exchange (ETDEWEB)

Whyatt, Greg A.; Zwoster, Andy; Zheng, Feng; Perry, Robert J.; Wood, Benjamin R.; Spiry, Irina; Freeman, Charles J.; Heldebrant, David J.

2017-04-12

This paper investigates the CO₂ and N₂ O absorption behavior in the water-lean gamma amino propyl (GAP)-1/TEG solvent system using a wetted-wall contactor. Testing was performed on a blend of GAP-1 aminosilicone in triethylene glycol at varied water loadings in the solvent. Measurements were made with CO₂ and N₂ O at representative lean (0.04 mol CO₂/mol alkalinity), middle (0.13 mol CO₂ /mol alkalinity) and rich (0.46 mol CO₂ /mol alkalinity) solvent loadings at 0, 5, 10 and 15 wt% water loadings at 40, 60 and 80C° and N₂ O at (0.08-0.09 mol CO₂ /mol alkalinity) at 5 wt% water at 40, 60 and 80C°. CO₂ flux was found to be non-linear with respect to log mean pressure driving force (LMPD). Liquid-film mass transfer coefficients (k'g) were calculated by subtracting the gas film resistance (determined from a correlation from literature) from the overall mass transfer measurement. The resulting k'g values for CO₂ and N₂ O in GAP-1/TEG mixtures were found to be higher than that of 5M aqueous monoethanolamine under comparable driving force albeit at higher solvent viscosities. The k'g values for CO₂ were also found to decrease with increasing solvent water content and increase with a decrease in temperature. These observations indicate that mass transfer of CO₂ in GAP-1/TEG is linked to the physical solubility of CO₂ , which is higher in organic solvents compared to water. This paper expands on the understanding of the unique mass transfer behavior and kinetics of CO₂ capture in water-lean solvents.
Iodide, azide, and cyanide complexes of (N,C), (N,N), and (N,O) metallacycles of tetra- and pentavalent uranium

International Nuclear Information System (INIS)

Benaud, Olivier; Berthet, Jean-Claude; Thuery, Pierre; Ephritikhine, Michel

2011-01-01

In contrast to the neutral macrocycle [UN* 2 (N,C)] (1) [N* = N(SiMe 3 ) 3 ; N,C = CH 2 SiMe 2 N-(SiMe 3 )] which was quite inert toward I 2 , the anionic bismetallacycle [NaUN*(N,C) 2 ] (2) was readily transformed into the enlarged monometallacycle [UN*(N,N)I] (4) [N,N = (Me 3 Si)NSiMe 2 CH 2 CH 2 SiMe 2 N(SiMe 3 )] resulting from C-C coupling of the two CH 2 groups, and [NaUN*(N,O) 2 ] (3) [N,O = OC(=CH 2 )SiMe 2 N(SiMe 3 )], which is devoid of any U-C bond, was oxidized into the UV bismetallacycle [Na{UN*(N,O) 2 }2(μ-I)] (5). Sodium amalgam reduction of 4 gave the U(III) compound [UN*(N,N)] (6). Addition of MN 3 or MCN to the (N,C), (N,N), and (N,O) metallacycles 1, 4, and 5 led to the formation of the anionic azide or cyanide derivatives M[UN* 2 (N,C)(N 3 )] [M = Na, 7a or Na(15-crown-5), 7b], M[UN* 2 (N,C)(CN)] [M = NEt 4 , 8a or Na(15-crown-5), 8b or K(18-crown-6), 8c], M[UN*(N,N)(N 3 ) 2 ] [M = Na, 9a or Na(THF)4, 9b], [NEt 4 ][UN*(N,N)(CN) 2 ] (10), M[UN*(N,O) 2 (N 3 )] [M = Na, 11a or Na(15-crown-5), 11b], M[UN*(N,O) 2 (CN)] [M = NEt 4 , 12a or Na(15-crown-5), 12b]. In the presence of excess iodine in THF, the cyanide 12a was converted back into the iodide 5, while the azide 11a was transformed into the neutral UV complex [U(N{SiMe 3 }-SiMe 2 C{CHI}O) 2 I(THF)] (13). The X-ray crystal structures of 4, 7b, 8a-c, 9b, 10, 12b, and 13 were determined. (authors)
Upland Trees Contribute to Exchange of Nitrous Oxide (N2O) in Forest Ecosystems

Science.gov (United States)

Tian, H.; Thompson, R.; Canadell, J.; Winiwarter, W.; Machacova, K.; Maier, M.; Halmeenmäki, E.; Svobodova, K.; Lang, F.; Pihlatie, M.; Urban, O.

2017-12-01

The increase in atmospheric nitrous oxide (N2O) concentration contributes to the acceleration of the greenhouse effect. However, the role of trees in the N2O exchange of forest ecosystems is still an open question. While the soils of temperate and boreal forests were shown to be a natural source of N2O, trees have been so far overlooked in the forest N2O inventories. We determined N2O fluxes in common tree species of boreal and temperate forests: Scots pine (Pinus sylvestris), Norway spruce (Picea abies), downy and silver birch (Betula pubescens, B. pendula), and European beech (Fagus sylvatica). We investigated (1) whether these tree species exchange N2O with the atmosphere under natural field conditions, (2) how the tree N2O fluxes contribute to the forest N2O balance, and (3) whether these fluxes show seasonal dynamics. The studies were performed in a boreal forest (SMEAR II station, Finland; June 2014 - May 2015) and two temperate mountain forests (White Carpathians, Czech Republic; Black Forest, Germany; June and July 2015). Fluxes of N2O in mature tree stems and forest floor were measured using static chamber systems followed by chromatographic and photo-acoustic analyses of N2O concentration changes. Pine, spruce and birch trees were identified as net annual N2O sources. Spruce was found the strongest emitter (0.27 mg ha-1 h-1) amounting thus up to 2.5% of forest floor N2O emissions. All tree species showed a substantial seasonality in stem N2O flux that was related to their physiological activity and climatic variables. In contrast, stems of beech trees growing at soils consuming N2O may act as a substantial sink of N2O from the atmosphere. Consistent N2O consumption by tree stems ranging between -12.1 and -35.2 mg ha-1 h-1 and contributing by up to 3.4% to the forest floor N2O uptake is a novel finding in contrast to current studies presenting trees as N2O emitters. To understand these fluxes, N2O exchange of photoautotrophic organisms associated with
Fluxes of CH4 and N2O in aspen stands grown under ambient and twice-ambient CO2

DEFF Research Database (Denmark)

Ambus, P.; Robertson, G.P.

1999-01-01

Elevated atmospheric CO2 has the potential to change below-ground nutrient cycling and thereby alter the soil-atmosphere exchange of biogenic trace gases. We measured fluxes of CH4 and N2O in trembling aspen (Populus tremuloides Michx.) stands grown in open-top chambers under ambient and twice......-ambient CO2 concentrations crossed with `high' and low soil-N conditions. Flux measurements with small static chambers indicated net CH4 oxidation in the open-top chambers. Across dates, CH4 oxidation activity was significantly (P CO2 (8.7 mu g CH4-C m(-2) h(-1)) than...... with elevated CO2 (6.5 mu g CH4-C m(-2) h(-1)) in the low N soil. Likewise, across dates and soil N treatments CH4 was oxidized more rapidly (P CO2 (9.5 mu g CH4-C m(-2) h(-1)) than in chambers with elevated CO2 (8.8 mu g CH4-C m(-2) h(-1)). Methane oxidation in soils incubated...
Frozen cropland soil in northeast China as source of N2O and CO2 emissions.

Science.gov (United States)

Miao, Shujie; Qiao, Yunfa; Han, Xiaozeng; Brancher Franco, Roberta; Burger, Martin

2014-01-01

Agricultural soils are important sources of atmospheric N2O and CO2. However, in boreal agro-ecosystems the contribution of the winter season to annual emissions of these gases has rarely been determined. In this study, soil N2O and CO2 fluxes were measured for 6 years in a corn-soybean-wheat rotation in northeast China to quantify the contribution of wintertime N2O and CO2 fluxes to annual emissions. The treatments were chemical fertilizer (NPK), chemical fertilizer plus composted pig manure (NPKOM), and control (Cont.). Mean soil N2O fluxes among all three treatments in the winter (November-March), when soil temperatures are below -7°C for extended periods, were 0.89-3.01 µg N m(-2) h(-1), and in between the growing season and winter (October and April), when freeze-thaw events occur, 1.73-5.48 µg N m(-2) h(-1). The cumulative N2O emissions were on average 0.27-1.39, 0.03-0.08 and 0.03-0.11 kg N2O_N ha(-1) during the growing season, October and April, and winter, respectively. The average contributions of winter N2O efflux to annual emissions were 6.3-12.1%. In all three seasons, the highest N2O emissions occurred in NPKOM, while NPK and Cont. emissions were similar. Cumulative CO2 emissions were 2.73-4.94, 0.13-0.20 and 0.07-0.11 Mg CO2-C ha(-1) during growing season, October and April, and winter, respectively. The contribution of winter CO2 to total annual emissions was 2.0-2.4%. Our results indicate that in boreal agricultural systems in northeast China, CO2 and N2O emissions continue throughout the winter.
Binary Oxide p-n Heterojunction Piezoelectric Nanogenerators with an Electrochemically Deposited High p-Type Cu2O Layer.

Science.gov (United States)

Baek, Seung Ki; Kwak, Sung Soo; Kim, Joo Sung; Kim, Sang Woo; Cho, Hyung Koun

2016-08-31

The high performance of ZnO-based piezoelectric nanogenerators (NGs) has been limited due to the potential screening from intrinsic electron carriers in ZnO. We have demonstrated a novel approach to greatly improve piezoelectric power generation by electrodepositing a high-quality p-type Cu2O layer between the piezoelectric semiconducting film and the metal electrode. The p-n heterojunction using only oxides suppresses the screening effect by forming an intrinsic depletion region, and thus sufficiently enhances the piezoelectric potential, compared to the pristine ZnO piezoelectric NG. Interestingly, a Sb-doped Cu2O layer has high mobility and low surface trap states. Thus, this doped layer is an attractive p-type material to significantly improve piezoelectric performance. Our results revealed that p-n junction NGs consisting of Au/ZnO/Cu2O/indium tin oxide with a Cu2O:Sb (cuprous oxide with a small amount of antimony) layer of sufficient thickness (3 μm) exhibit an extraordinarily high piezoelectric potential of 0.9 V and a maximum output current density of 3.1 μA/cm(2).
Effects of Dăoyĭn Qìgōng in postpolio syndrome patients with cold intolerance

Directory of Open Access Journals (Sweden)

Paulo Eduardo Ramos

2012-09-01

Full Text Available Postpolio syndrome (PPS is characterized by progressive muscle weakness due to former infection with poliomyelitis and can be associated with other symptoms such as cold intolerance (CI. Dăoyĭn Qìgōng (DQ is a technique in Traditional Chinese Medicine that impacts the circulation of energy and blood. OBJECTIVE: It was to verify the effects of DQ in PPS patients complaining of cold intolerance. METHODS: Ten PPS patients were assessed using the visual analogue scale (VAS adapted for CI before and after intervention with DQ; patients practiced it in a sitting position for 40 minutes, 3 times per week over 3 consecutive months. Patients were reassessed three months after ceasing DQ. RESULTS: There was a statistically significant difference in local and systemic VAS-Cold both at the end of DQ training and three months past the end of this. CONCLUSION: The DQ technique ameliorated CI complaints in patients with PPS.
N2O production, a widespread trait in fungi

Science.gov (United States)

Maeda, Koki; Spor, Aymé; Edel-Hermann, Véronique; Heraud, Cécile; Breuil, Marie-Christine; Bizouard, Florian; Toyoda, Sakae; Yoshida, Naohiro; Steinberg, Christian; Philippot, Laurent

2015-04-01

N2O is a powerful greenhouse gas contributing both to global warming and ozone depletion. While fungi have been identified as a putative source of N2O, little is known about their production of this greenhouse gas. Here we investigated the N2O-producing ability of a collection of 207 fungal isolates. Seventy strains producing N2O in pure culture were identified. They were mostly species from the order Hypocreales order--particularly Fusarium oxysporum and Trichoderma spp.--and to a lesser extent species from the orders Eurotiales, Sordariales, and Chaetosphaeriales. The N2O 15N site preference (SP) values of the fungal strains ranged from 15.8‰ to 36.7‰, and we observed a significant taxa effect, with Penicillium strains displaying lower SP values than the other fungal genera. Inoculation of 15 N2O-producing strains into pre-sterilized arable, forest and grassland soils confirmed the ability of the strains to produce N2O in soil with a significant strain-by-soil effect. The copper-containing nitrite reductase gene (nirK) was amplified from 45 N2O-producing strains, and its genetic variability showed a strong congruence with the ITS phylogeny, indicating vertical inheritance of this trait. Taken together, this comprehensive set of findings should enhance our knowledge of fungi as a source of N2O in the environment.
Effect of sulfation on the surface activity of CaO for N{sub 2}O decomposition

Energy Technology Data Exchange (ETDEWEB)

Wu, Lingnan, E-mail: wulingnan@126.com [School of Energy, Power and Mechanical Engineering, North China Electric Power University, 102206 Beijing (China); National Engineering Laboratory for Biomass Power Generation Equipment, North China Electric Power University, 102206 Beijing (China); Hu, Xiaoying, E-mail: huxy@ncepu.edu.cn [National Engineering Laboratory for Biomass Power Generation Equipment, North China Electric Power University, 102206 Beijing (China); Qin, Wu, E-mail: qinwugx@126.com [National Engineering Laboratory for Biomass Power Generation Equipment, North China Electric Power University, 102206 Beijing (China); Dong, Changqing, E-mail: cqdong1@163.com [National Engineering Laboratory for Biomass Power Generation Equipment, North China Electric Power University, 102206 Beijing (China); Yang, Yongping, E-mail: yypncepu@163.com [School of Energy, Power and Mechanical Engineering, North China Electric Power University, 102206 Beijing (China)

2015-12-01

Graphical abstract: - Highlights: • Sulfation of CaO (1 0 0) surface greatly deactivates its surface activity for N{sub 2}O decomposition. • An increase of sulfation degree leads to a decrease of CaO surface activity for N{sub 2}O decomposition. • Sulfation from CaSO{sub 3} into CaSO{sub 4} is the crucial step for deactivating the surface activity for N{sub 2}O decomposition. • The electronic interaction CaO (1 0 0)/CaSO{sub 4} (0 0 1) interface is limited to the bottom layer of CaSO{sub 4} (0 0 1) and the top layer of CaO (1 0 0). • CaSO{sub 4} (0 0 1) and (0 1 0) surfaces show negligible catalytic ability for N{sub 2}O decomposition. - Abstract: Limestone addition to circulating fluidized bed boilers for sulfur removal affects nitrous oxide (N{sub 2}O) emission at the same time, but mechanism of how sulfation process influences the surface activity of CaO for N{sub 2}O decomposition remains unclear. In this paper, we investigated the effect of sulfation on the surface properties and catalytic activity of CaO for N{sub 2}O decomposition using density functional theory calculations. Sulfation of CaO (1 0 0) surface by the adsorption of a single gaseous SO{sub 2} or SO{sub 3} molecule forms stable local CaSO{sub 3} or CaSO{sub 4} on the CaO (1 0 0) surface with strong hybridization between the S atom of SO{sub x} and the surface O anion. The formed local CaSO{sub 3} increases the barrier energy of N{sub 2}O decomposition from 0.989 eV (on the CaO (1 0 0) surface) to 1.340 eV, and further sulfation into local CaSO{sub 4} remarkably increases the barrier energy to 2.967 eV. Sulfation from CaSO{sub 3} into CaSO{sub 4} is therefore the crucial step for deactivating the surface activity for N{sub 2}O decomposition. Completely sulfated CaSO{sub 4} (0 0 1) and (0 1 0) surfaces further validate the negligible catalytic ability of CaSO{sub 4} for N{sub 2}O decomposition.
Effects of cover crops incorporation and nitrogen fertilization on N2O and CO2 emissions

Science.gov (United States)

Kandel, T. P.; Gowda, P. H.; Northup, B. K.; DuPont, J.; Somenahally, A. C.; Rocateli, A.

2017-12-01

In this study, we measured N2O and CO2 fluxes from plots planted to hairy vetch (winter cover crop) and broadleaf vetch (spring cover crop) as N sources for the following crabgrass (summer forage crop) in El Reno, Oklahoma, USA. Comparisons also included 0 and 60 kg ha-1 mineral N fertilizer supplied as dry urea. No significant N2O fluxes were observed during rapid growing periods of cover crops (March-April, 2017), however, large fluxes were observed after hairy vetch incorporation. Immediately after the hairy vetch biomass incorporation, large rainfall events were recorded. The fluxes subsided gradually with drying soil condition but were enhanced after every consecutive rainfall events. A rainfall induced flux measuring up to 8.2 kg N2O ha-1 day-1 was observed after 26 days of biomass incorporation. In total, 29 kg N2O ha-1 (18 kg N ha-1) was emitted within a month after biomass incorporation from hairy vetch plots. Growth of broadleaf vetch was poor and N2O fluxes were also lower. Similarly, plots fertilized with 60 kg N ha-1 had significant fluxes of N2O but the magnitude was much lower than the hairy vetch plots. Dynamics of N2O and CO fluxes correlated strongly. The results thus indicated that although cover crops may provide many environmental/agronomic benefits such as N fixation, soil carbon built-up, weed suppression and erosion control, high N2O emissions may dwarf these benefits.
Impact of raw pig slurry and pig farming practices on physicochemical parameters and on atmospheric N2O and CH 4 emissions of tropical soils, Uvéa Island (South Pacific).

Science.gov (United States)

Roth, E; Gunkel-Grillon, P; Joly, L; Thomas, X; Decarpenterie, T; Mappe-Fogaing, I; Laporte-Magoni, C; Dumelié, N; Durry, G

2014-09-01

Emissions of CH4 and N2O related to private pig farming under a tropical climate in Uvéa Island were studied in this paper. Physicochemical soil parameters such as nitrate, nitrite, ammonium, Kjeldahl nitrogen, total organic carbon, pH and moisture were measured. Gaseous soil emissions as well as physicochemical parameters were compared in two private pig farming strategies encountered on this island on two different soils (calcareous and ferralitic) in order to determine the best pig farming management: in small concrete pens or in large land pens. Ammonium levels were higher in control areas while nitrate and nitrite levels were higher in soils with pig slurry inputs, indicating that nitrification was the predominant process related to N2O emissions. Nitrate contents in soils near concrete pens were important (≥ 55 μg N/g) and can thus be a threat for the groundwater. For both pig farming strategies, N2O and CH4 fluxes can reach high levels up to 1 mg N/m(2)/h and 1 mg C/m(2)/h, respectively. CH4 emissions near concrete pens were very high (≥ 10.4 mg C/m(2)/h). Former land pens converted into agricultural land recover low N2O emission rates (≤ 0.03 mg N/m(2)/h), and methane uptake dominates. N2O emissions were related to nitrate content whereas CH4 emissions were found to be moisture dependent. As a result relating to the physicochemical parameters as well as to the gaseous emissions, we demonstrate that pig farming in large land pens is the best strategy for sustainable family pig breeding in Uvéa Islands and therefore in similar small tropical islands.
N2O production pathways in the subtropical acid forest soils in China

International Nuclear Information System (INIS)

Zhang Jinbo; Cai Zucong; Zhu Tongbin

2011-01-01

To date, N 2 O production pathways are poorly understood in the humid subtropical and tropical forest soils. A 15 N-tracing experiment was carried out under controlled laboratory conditions to investigate the processes responsible for N 2 O production in four subtropical acid forest soils (pH 2 O emission in the subtropical acid forest soils, being responsible for 56.1%, 53.5%, 54.4%, and 55.2% of N 2 O production, in the GC, GS, GB, and TC soils, respectively, under aerobic conditions (40%-52%WFPS). The heterotrophic nitrification (recalcitrant organic N oxidation) accounted for 27.3%-41.8% of N 2 O production, while the contribution of autotrophic nitrification was little in the studied subtropical acid forest soils. The ratios of N 2 O-N emission from total nitrification (heterotrophic+autotrophic nitrification) were higher than those in most previous references. The soil with the lowest pH and highest organic-C content (GB) had the highest ratio (1.63%), suggesting that soil pH-organic matter interactions may exist and affect N 2 O product ratios from nitrification. The ratio of N 2 O-N emission from heterotrophic nitrification varied from 0.02% to 25.4% due to soil pH and organic matter. Results are valuable in the accurate modeling of N2O production in the subtropical acid forest soils and global budget. - Highlights: → We studied N 2 O production pathways in subtropical acid forest soil under aerobic conditions. → Denitrification was the main source of N 2 O production in subtropical acid forest soils. → Heterotrophic nitrification accounted for 27.3%-41.8% of N 2 O production. → While, contribution of autotrophic nitrification to N 2 O production was little. → Ratios of N 2 O-N emission from nitrification were higher than those in most previous references.
Effects of flooding-induced N2O production, consumption and emission dynamics on the annual N2O emission budget in wetland soil

DEFF Research Database (Denmark)

Jørgensen, Christian Juncher; Elberling, Bo

2012-01-01

during mid-summer when the WL was at its seasonally lowest counterbalancing ~6.4% of the total annual net N2O emission budget. Main surface emission periods of N2O were observed when the water level and associated peaks in subsurface N2O concentrations were gradually decreasing to soil depths down to 40...... production and consumption capacities where >500 nmol N2O cm-3 were sequentially produced and consumed in less than 24 hrs. It is concluded that a higher future frequency of flooding induced N2O emissions will have a very limited effect on the net annual N2O emission budget as long as NO3- availability...
Market Analysis DeN2O. Market potential for reduction of N2O emissions at nitric acid facilities

International Nuclear Information System (INIS)

Smit, A.W.; Gent, M.M.C.; Van den Brink, R.W.

2001-05-01

ECN has developed a technique for the removal of nitrous oxide (N2O) from the tail gases of a nitric acid plant. The aim of this project was to make an assessment of the market opportunities of this technique. To this end a study was made of the relevant international regulations and agreements on the field of climate policy. The formulation of an international greenhouse gas policy and concomitant flexible mechanisms is a prerequisite for the market introduction of any N2O abatement technique. The available techniques and techniques in development for N2O abatement in the nitric acid industry are described and the strengths and weaknesses are given. Furthermore, the costs per ton CO2 equivalents removed are estimated. Direct decomposition of N2O (either in the NH3 combustion reactor or downstream the absorber) are the most cost efficient techniques. Finally, the number and sizes of nitric acid plants in Europe and the developments in the fertiliser market are described. The current difficult fertiliser market makes the nitric acid producers reluctant to invest in N2O abatement technologies
Structure and high photocatalytic activity of (N, Ta)-doped TiO{sub 2} nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Le, N. T. H.; Lam, V. D.; Manh, D. H.; Hong, L. V. [Institute of Materials Science, Vietnam Academy of Science and Technology, 18-Hoang Quoc Viet, Hanoi (Viet Nam); Thanh, T. D., E-mail: thanhxraylab@yahoo.com, E-mail: scyu@cbnu.ac.kr [Institute of Materials Science, Vietnam Academy of Science and Technology, 18-Hoang Quoc Viet, Hanoi (Viet Nam); Department of Physics, Chungbuk National University, Cheongju 28644 (Korea, Republic of); Pham, V.-T. [Center for Quantum Electronics, Institute of Physics, Vietnam Academy of Science and Technology, Hanoi (Viet Nam); Synchrotron SOLEIL, L' Orme des Merisiers, Boîte Postale, 48, 91192 Gif-sur-Yvette Cedex (France); Phan, T. L.; Yu, S. C., E-mail: thanhxraylab@yahoo.com, E-mail: scyu@cbnu.ac.kr [Department of Physics, Chungbuk National University, Cheongju 28644 (Korea, Republic of); Anh, T. X. [Center for Quantum Electronics, Institute of Physics, Vietnam Academy of Science and Technology, Hanoi (Viet Nam); Le, T. K. C. [Institut des Sciences Moleculaires d' Orsay, CNRS, Univ Paris-Sud, 91405 Orsay Cedex (France); Thammajak, N. [Synchrotron Light Research Institute, 111 University Avenue, Muang, Nakhon Ratchasima 30000 (Thailand)

2016-10-14

A hydrothermal method was used to prepare three nano-crystalline samples of TiO{sub 2} (S1), N-doped TiO{sub 2} (S2), and (N, Ta)-codoped TiO{sub 2} (S3) with average crystallite sizes (D) of 13–25 nm. X-ray diffraction studies confirmed a single phase of the samples with a tetragonal/anatase structure. A slight increase in the lattice parameters was observed when N and/or Ta dopants were doped into the TiO{sub 2} host lattice. Detailed analyses of extended X-ray absorption spectra indicated that N- and/or Ta-doping into TiO{sub 2} nanoparticles influenced the co-ordination number and radial distance (R) of Ti ions in the anatase structure. Concerning their absorption spectra, (N, Ta)-doping narrowed the band gap (E{sub g}) of TiO{sub 2} from 3.03 eV for S1 through 2.94 eV for S2 to 2.85 eV for S3. Such results revealed the applicability of these nanoparticles in the photocatalytic field working in the ultraviolet (UV)-visible region. Among these, photocatalytic activity of S3 was the strongest. By using S3 as a catalyst powder, the degradation efficiency of methylene blue solution was about 99% and 93% after irradiation of UV-visible light for 75 min and visible-light for 180 min, respectively.
High Resolution Measurements of Nitrous Oxide (N2O in the Elbe Estuary

Directory of Open Access Journals (Sweden)

Lisa Brase

2017-05-01

Full Text Available Nitrous oxide (N2O is one of the most important greenhouse gases and a major sink for stratospheric ozone. Estuaries are sites of intense biological production and N2O emissions. We aimed to identify hot spots of N2O production and potential pathways contributing to N2O concentrations in the surface water of the tidal Elbe estuary. During two research cruises in April and June 2015, surface water N2O concentrations were measured along the salinity gradient of the Elbe estuary by using a laser-based on-line analyzer coupled to an equilibrator. Based on these high-resolution N2O profiles, N2O saturations, and fluxes across the surface water/atmosphere interface were calculated. Additional measurements of DIN concentrations, oxygen concentration, and salinity were performed. Highest N2O concentrations were determined in the Hamburg port region reaching maximum values of 32.3 nM in April 2015 and 52.2 nM in June 2015. These results identify the Hamburg port region as a significant hot spot of N2O production, where linear correlations of AOU-N2Oxs indicate nitrification as an important contributor to N2O production in the freshwater part. However, in the region with lowest oxygen saturation, sediment denitrification obviously affected water column N2O saturation. The average N2O saturation over the entire estuary was 201% (SD: ±94%, with an average estuarine N2O flux density of 48 μmol m−2 d−1 and an overall emission of 0.18 Gg N2O y−1. In comparison to previous studies, our data indicate that N2O production pathways over the whole estuarine freshwater part have changed from predominant denitrification in the 1980s toward significant production from nitrification in the present estuary. Despite a significant reduction in N2O saturation compared to the 1980s, N2O concentrations nowadays remain on a high level, comparable to the mid-90s, although a steady decrease of DIN inputs occurred over the last decades. Hence, the Elbe estuary still
Effects of carbon sources and COD/N ratio on N2O emissions in subsurface flow constructed wetlands.

Science.gov (United States)

Lyu, Wanlin; Huang, Lei; Xiao, Guangquan; Chen, Yucheng

2017-12-01

A set of constructed wetlands under two different carbon sources, namely, glucose (CW) and sodium acetate (YW), was established at a laboratory scale with influent COD/N ratios of 20:1, 10:1, 7:1, 4:1, and 0 to analyze the influence of carbon supply on nitrous oxide emissions. Results showed that the glucose systems generated higher N 2 O emissions than those of the sodium acetate systems. The higher amount of N 2 O-releasing fluxes in the CWs than in the YWs was consistent with the higher NO 2 - -N accumulation in the former than in the latter. Moreover, electron competition was tighter in the CWs and contributed to the incomplete denitrification with poor N 2 O production performance. Illumina MiSeq sequencing demonstrated that some denitrifying bacteria, such as Denitratisoma, Bacillus, and Zoogloea, were higher in the YWs than in the CWs. This result indicated that the carbon source is important in controlling N 2 O emissions in microbial communities. Copyright © 2017. Published by Elsevier Ltd.
Photocatalytic Decomposition of N2O on Ag-TiO2

Czech Academy of Sciences Publication Activity Database

Kočí, K.; Krejčíková, Simona; Šolcová, Olga; Obalová, L.

2012-01-01

Roč. 191, č. 1 (2012), s. 134-137 ISSN 0920-5861. [International Symposium on Nitrogen Oxides Emission Abatement. Zakopane, 04.09.2011-07.09.2011] R&D Projects: GA ČR GA104/09/0694 Institutional support: RVO:67985858 Keywords : photocatalytic decomposition * N2O * Ag doping * TiO2 Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.980, year: 2012
(Carbonato-κO,O')bis-(di-2-pyridyl-amine-κN,N')cobalt(III) bromide.

Science.gov (United States)

Czapik, Agnieszka; Papadopoulos, Christos; Lalia-Kantouri, Maria; Gdaniec, Maria

2011-04-01

In the title compound, [Co(CO(3))(C(10)H(9)N(3))(2)]Br, a distorted octa-hedral coordination of the Co(III) atom is completed by four N atoms of the two chelating di-2-pyridyl-amine ligands and two O atoms of the chelating carbonate anion. The di-2-pyridyl-amine ligands are nonplanar and the dihedral angles between the 2-pyridyl groups are 29.11 (9) and 37.15 (12)°. The coordination cation, which has approximate C(2) symmetry, is connected to the bromide ion via an N-H⋯Br(-) hydrogen bond. The ionic pair thus formed is further assembled into a dimer via N-H⋯O inter-actions about an inversion centre. A set of weaker C-H⋯O and C-H⋯Br(-) inter-actions connect the dimers into a three-dimensional network.

Chemical stabilization and high pressure synthesis of Ba-free Hg-based superconductors, (Hg,M)Sr{sub 2}Ca{sub n-1}Cu{sub n}O{sub y}(N=1{approximately}3)

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Kishio, K. [Univ. of Tokyo (Japan)]|[Kyoto Univ. (Japan); Shimoyama, J.; Hahakura, S. [Univ. of Tokyo (Japan)] [and others

1994-12-31

A homologous series of new Hg-based HTSC compounds, (Hg,M)Sr{sub 2}Ca{sub n-1}Cu{sub n}O{sub y} with n=1 to 3, have been synthesized. The stabilization of the pure phases have been accomplished by chemical doping of third elements such as M=Cr, Mo and Re. While the Hg1201(n=1) phase was readily obtained in this way, it was necessary to simultaneously dope Y into the Ca site to stabilize the Hg1212(n=2) phase. On the other hand, single-phase Y-free Hg1212(n=2) and Hg1223(n=3) samples were synthesized only under a high pressure of 6 GPa. In sharp contrast to the Ba-containing compounds, all the samples prepared in the present study have been quite stable during the synthesis and no deterioration in air has been observed after the preparation.
{6,6′-Dimethoxy-2,2′-[ethane-1,2-diylbis(nitrilomethylidyne]diphenolato-1κ4O1,O1′,O6,O6′:2κ4O1,N,N′,O1′}(ethanol-1κO-μ-nitrato-1:2κ2O:O′-dinitrato-1κ4O,O′-samarium(IIIzinc(II

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Qiang Huang

2009-10-01

Full Text Available In the title heteronuclear ZnII–SmIII complex, [SmZn(C18H18N2O4(NO33(CH3CH2OH], with the hexadentate Schiff base compartmental ligand N,N′-bis(3-methoxysalicylideneethylenediamine (H2L, the SmIII and ZnII ions are triply bridged by two phenolate O atoms from the Schiff base ligand and one nitrate anion. The five-coordinate ZnII ion is in a square-pyramidal geometry formed by the donor centers of two imine N atoms, two phenolate O atoms and one of the bridging nitrate O atoms. The SmIII center is in a ten-fold coordination of O atoms, involving the phenolate O atoms, two methoxy O atoms, one ethanol O atom, and two O atoms from two nitrate anions and one from the bridging nitrate anion. In the crystal, intermolecular O—H...O and C—H...O interactions generate a layer structure extending parallel to (101.
Investigation of the N2O emission strength in the U. S. Corn Belt

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Fu, Congsheng; Lee, Xuhui; Griffis, Timothy J.; Dlugokencky, Edward J.; Andrews, Arlyn E.

2017-09-01

Nitrous oxide (N2O) has a high global warming potential and depletes stratospheric ozone. The U. S. Corn Belt plays an important role in the global anthropogenic N2O budget. To date, studies on local surface N2O emissions and the atmospheric N2O budget have commonly used Lagrangian models. In the present study, we used an Eulerian model - Weather Research and Forecasting Chemistry (WRF-Chem) model to investigate the relationships between N2O emissions in the Corn Belt and observed atmospheric N2O mixing ratios. We derived a simple equation to relate the emission strengths to atmospheric N2O mixing ratios, and used the derived equation and hourly atmospheric N2O measurements at the KCMP tall tower in Minnesota to constrain agricultural N2O emissions. The modeled spatial patterns of atmospheric N2O were evaluated against discrete observations at multiple tall towers in the NOAA flask network. After optimization of the surface flux, the model reproduced reasonably well the hourly N2O mixing ratios monitored at the KCMP tower. Agricultural N2O emissions in the EDGAR42 database needed to be scaled up by 19.0 to 28.1 fold to represent the true emissions in the Corn Belt for June 1-20, 2010 - a peak emission period. Optimized mean N2O emissions were 3.00-4.38, 1.52-2.08, 0.61-0.81 and 0.56-0.75 nmol m- 2 s- 1 for June 1-20, August 1-20, October 1-20 and December 1-20, 2010, respectively. The simulated spatial patterns of atmospheric N2O mixing ratios after optimization were in good agreement with the NOAA discrete observations during the strong emission peak in June. Such spatial patterns suggest that the underestimate of emissions using IPCC (Inter-governmental Panel on Climate Change) inventory methodology is not dependent on tower measurement location.
Butane-1,4-diammonium bis(pyridine-2,6-dicarboxylato-κ3O2,N,O6cadmate(II dihydrate

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Najmeh Firoozi

2008-10-01

Full Text Available In the title compound, (C4H14N2[Cd(C7H3NO42]·2H2O, the CdII ion is coordinated by four O atoms [Cd—O = 2.2399 (17–2.2493 (17 Å] and two N atoms [Cd—N = 2.3113 (15 and 2.3917 (15 Å] from two tridentate pyridine-2,6-dicarboxylato ligands in a distorted octahedral geometry. The uncoordinated water molecules are involved in O—H...O and N—H...O hydrogen bonds, which contribute to the formation of a three-dimensional supramolecular structure, along with π–π stacking interactions [centroid–centroid distances of 3.5313 (13 and 3.6028 (11 Å between the pyridine rings of neighbouring dianions].
Propane-1,2-diammonium bis(pyridine-2,6-dicarboxylato-κ3O,N,O′nickelate(II tetrahydrate

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Mohammad Ghadermazi

2008-07-01

Full Text Available The reaction of nickel(II nitrate hexahydrate, propane-1,2-diamine and pyridine-2,6-dicarboxylic acid in a 1:2:2 molar ratio in aqueous solution resulted in the formation of the title compound, (C3H12N2[Ni(C7H3NO42]·4H2O or (p-1,2-daH2[Ni(pydc2]·4H2O (where p-1,2-da is propane-1,2-diamine and pydcH2 is pyridine-2,6-dicarboxylic acid. The geometry of the resulting NiN2O4 coordination can be described as distorted octahedral. Considerable C=O...π stacking interactions are observed between the carboxylate C=O groups and the pyridine rings of the (pydc2− fragments, with O...π distances of 3.1563 (12 and 3.2523 (12 Å and C=O...π angles of 95.14 (8 and 94.64 (8°. In the crystal structure, a wide range of non-covalent interactions, consisting of hydrogen bonding [O—H...O, N—H...O and C—H...O, with D...A distances ranging from 2.712 (2 to 3.484 (2 Å], ion pairing, π–π [centroid-to-centroid distance = 3.4825 (8 Å] and C=O...π stacking, connect the various components to form a supramolecular structure.
Computational study on the half-metallicity in transition metal—oxide-incorporated 2D g-C3N4 nanosheets

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Gao, Qian; Wang, Hui-Li; Zhang, Li-Fu; Hu, Shuang-Lin; Hu, Zhen-Peng

2018-06-01

In this study, based on the first-principles calculations, we systematically investigated the electronic and magnetic properties of the transition metal-oxide-incorporated 2D g-C3N4 nanosheet (labeled C3N4-TM-O, TM = Sc-Mn). The results suggest that the TM-O binds to g-C3N4 nanosheets strongly for all systems. We found that the 2D C3N4-TM-O framework is ferromagnetic for TM = Sc, Ti, V, Cr, while it is antiferromagnetic for TM = Mn. All the ferromagnetic systems exhibit the half-metallic property. Furthermore, Monte Carlo simulations based on the Heisenberg model suggest that the Curie temperatures ( T c ) of the C3N4-TM-O (TM = Sc, Ti, V, Cr) framework are 169 K, 68 K, 203 K, and 190 K, respectively. Based on Bader charge analysis, we found that the origin of the half-metallicity at Fermi energy can be partially attributed to the transfer of electrons from TM atoms to the g-C3N4 nanosheet. In addition, we found that not only electrons but also holes can induce half-metallicity for 2D g-C3N4 nanosheets, which may help to understand the origin of half-metallicity for graphitic carbon nitride.
Isotopologue fractionation during N(2)O production by fungal denitrification.

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Sutka, Robin L; Adams, Gerard C; Ostrom, Nathaniel E; Ostrom, Peggy H

2008-12-01

Identifying the importance of fungi to nitrous oxide (N2O) production requires a non-intrusive method for differentiating between fungal and bacterial N2O production such as natural abundance stable isotopes. We compare the isotopologue composition of N2O produced during nitrite reduction by the fungal denitrifiers Fusarium oxysporum and Cylindrocarpon tonkinense with published data for N2O production during bacterial nitrification and denitrification. The fractionation factors for bulk nitrogen isotope values for fungal denitrification were in the range -74.7 to -6.6 per thousand. There was an inverse relationship between the absolute value of the fractionation factors and the reaction rate constant. We interpret this in terms of variation in the relative importance of the rate constants for diffusion and enzymatic reduction in controlling the net isotope effect for N2O production during fungal denitrification. Over the course of nitrite reduction, the delta(18)O values for N2O remained constant and did not exhibit a relationship with the concentration characteristic of an isotope effect. This probably reflects isotopic exchange with water. Similar to the delta(18)O data, the site preference (SP; the difference in delta(15)N between the central and outer N atoms in N2O) was unrelated to concentration during nitrite reduction and, therefore, has the potential to act as a conservative tracer of production from fungal denitrification. The SP values of N2O produced by F. oxysporum and C. tonkinense were 37.1 +/- 2.5 per thousand and 36.9 +/- 2.8 per thousand, respectively. These SP values are similar to those obtained in pure culture studies of bacterial nitrification but quite distinct from SP values for bacterial denitrification. The large magnitude of the bulk nitrogen isotope fractionation and the delta(18)O values associated with fungal denitrification are distinct from bacterial production pathways; thus multiple isotopologue data holds much promise for
Integral Representation of the Pictorial Proof of Sum of [superscript n][subscript k=1]k[superscript 2] = 1/6n(n+1)(2n+1)

Science.gov (United States)

Kobayashi, Yukio

2011-01-01

The pictorial proof of the sum of [superscript n][subscript k=1] k[superscript 2] = 1/6n(n+1)(2n+1) is represented in the form of an integral. The integral representations are also applicable to the sum of [superscript n][subscript k-1] k[superscript m] (m greater than or equal to 3). These representations reveal that the sum of [superscript…
Enhanced photocatalytic ozonation of organics by g-C3N4 under visible light irradiation

International Nuclear Information System (INIS)

Liao, Gaozu; Zhu, Dongyun; Li, Laisheng; Lan, Bingyan

2014-01-01

Highlights: • g-C 3 N 4 is employed as active catalyst in the photocatalytic ozonation system. • The more negative conduction band of g-C 3 N 4 benefits the transfer of electrons. • The synergistic effect between photocatalysis and ozonation is promoted by g-C 3 N 4 . • Enhanced degradation of oxalic acid and biphenol A is achieved via g-C 3 N 4 /Vis/O 3 . - Abstract: Graphitic carbon nitride (g-C 3 N 4 ) was employed as the active photocatalyst in the photocatalytic ozonation coupling system in the present study. g-C 3 N 4 was prepared by directly heating thiourea in air at 550 °C. XRD, FT-IR, UV–vis was used to characterize the structure and optical property. Oxalic acid and bisphenol A were selected as model substances for photocatalytic ozonation reactions to evaluate the catalytic ability of g-C 3 N 4 (g-C 3 N 4 /Vis/O 3 ). The results showed that the degradation ratio of oxalic acid with g-C 3 N 4 /Vis/O 3 was 65.2% higher than the sum of ratio when it was individually decomposed by g-C 3 N 4 /Vis and O 3 . The TOC removal of biphenol A with g-C 3 N 4 /Vis/O 3 was 2.17 times as great as the sum of the ratio when using g-C 3 N 4 /Vis and O 3 . This improvement was attributed to the enhanced synergistic effect between photocatalysis and ozonation by g-C 3 N 4 . Under visible light irradiation, the photo-generated electrons produced on g-C 3 N 4 facilitated the electrons transfer owing to the more negative conduction band potential (−1.3 V versus NHE). It meant that the photo-generated electrons could be trapped by ozone and reaction with it more easily. Subsequently, the yield of hydroxyl radicals was improved so as to enhance the organics degradation efficiency. This work indicated that metal-free g-C 3 N 4 could be an excellent catalyst for mineralization of organic compounds in waste control
A limit for large R-charge correlators in N = 2 theories

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Bourget, Antoine; Rodriguez-Gomez, Diego; Russo, Jorge G.

2018-05-01

Using supersymmetric localization, we study the sector of chiral primary operators (Tr ϕ 2) n with large R-charge 4 n in N = 2 four-dimensional superconformal theories in the weak coupling regime g → 0, where λ ≡ g 2 n is kept fixed as n → ∞, g representing the gauge theory coupling(s). In this limit, correlation functions G 2 n of these operators behave in a simple way, with an asymptotic behavior of the form {G}_{2n}≈ {F}_{∞}(λ){(λ/2π e)}^{2n} n α , modulo O(1 /n) corrections, with α =1/2 \\dim (g) for a gauge algebra g and a universal function F ∞(λ). As a by-product we find several new formulas both for the partition function as well as for perturbative correlators in N=2 su(N) gauge theory with 2 N fundamental hypermultiplets.
Poly[[aqua(μ2-4,4′-bipyridine-κ2N:N′[μ3-3-bromo-2-(carboxylatomethylbenzoato-κ3O1:O1′:O2]cadmium] monohydrate

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Yangmei Liu

2012-08-01

Full Text Available In the title compound, {[Cd(C9H5BrO4(C10H8N2(H2O]·H2O}n, the CdII atom has a distorted octahedral coordination geometry. Two N atoms from two 4,4′-bipyridine (bipy ligands occupy the axial positions, while the equatorial positions are furnished by three carboxylate O atoms from three 3-bromo-2-(carboxylatomethylbenzoate (bcb ligands and one O atom from a water molecule. The bipy and bcb ligands link the CdII atoms into a three-dimensional network. O—H...O hydrogen bonds and π–π interactions between the pyridine and benzene rings [centroid–centroid distance = 3.736 (4 Å] are present in the crystal.
Diet effects on urine composition of cattle and N2O emissions.

Science.gov (United States)

Dijkstra, J; Oenema, O; van Groenigen, J W; Spek, J W; van Vuuren, A M; Bannink, A

2013-06-01

Ruminant production contributes to emissions of nitrogen (N) to the environment, principally ammonia (NH3), nitrous oxide (N2O) and di-nitrogen (N2) to air, nitrate (NO3 -) to groundwater and particulate N to surface waters. Variation in dietary N intake will particularly affect excretion of urinary N, which is much more vulnerable to losses than is faecal N. Our objective is to review dietary effects on the level and form of N excreted in cattle urine, as well as its consequences for emissions of N2O. The quantity of N excreted in urine varies widely. Urinary N excretion, in particular that of urea N, is decreased upon reduction of dietary N intake or an increase in the supply of energy to the rumen microorganisms and to the host animal itself. Most of the N in urine (from 50% to well over 90%) is present in the form of urea. Other nitrogenous components include purine derivatives (PD), hippuric acid, creatine and creatinine. Excretion of PD is related to rumen microbial protein synthesis, and that of hippuric acid to dietary concentration of degradable phenolic acids. The N concentration of cattle urine ranges from 3 to 20 g/l. High-dietary mineral levels increase urine volume and lead to reduced urinary N concentration as well as reduced urea concentration in plasma and milk. In lactating dairy cattle, variation in urine volume affects the relationship between milk urea and urinary N excretion, which hampers the use of milk urea as an accurate indicator of urinary N excretion. Following its deposition in pastures or in animal houses, ubiquitous microorganisms in soil and waters transform urinary N components into ammonium (NH4 +), and thereafter into NO3 - and ultimately in N2 accompanied with the release of N2O. Urinary hippuric acid, creatine and creatinine decompose more slowly than urea. Hippuric acid may act as a natural inhibitor of N2O emissions, but inhibition conditions have not been defined properly yet. Environmental and soil conditions at the site of
Soil invertebrate fauna affect N2 O emissions from soil.

Science.gov (United States)

Kuiper, Imke; de Deyn, Gerlinde B; Thakur, Madhav P; van Groenigen, Jan Willem

2013-09-01

Nitrous oxide (N2 O) emissions from soils contribute significantly to global warming. Mitigation of N2 O emissions is severely hampered by a lack of understanding of its main controls. Fluxes can only partly be predicted from soil abiotic factors and microbial analyses - a possible role for soil fauna has until now largely been overlooked. We studied the effect of six groups of soil invertebrate fauna and tested the hypothesis that all of them increase N2 O emissions, although to different extents. We conducted three microcosm experiments with sandy soil and hay residue. Faunal groups included in our experiments were as follows: fungal-feeding nematodes, mites, springtails, potworms, earthworms and isopods. In experiment I, involving all six faunal groups, N2 O emissions declined with earthworms and potworms from 78.4 (control) to 37.0 (earthworms) or 53.5 (potworms) mg N2 O-N m(-2) . In experiment II, with a higher soil-to-hay ratio and mites, springtails and potworms as faunal treatments, N2 O emissions increased with potworms from 51.9 (control) to 123.5 mg N2 O-N m(-2) . Experiment III studied the effect of potworm density; we found that higher densities of potworms accelerated the peak of the N2 O emissions by 5 days (P soil aeration by the soil fauna reduced N2 O emissions in experiment I, whereas in experiment II N2 O emissions were driven by increased nitrogen and carbon availability. In experiment III, higher densities of potworms accelerated nitrogen and carbon availability and N2 O emissions, but did not increase them. Overall, our data show that soil fauna can suppress, increase, delay or accelerate N2 O emissions from soil and should therefore be an integral part of future N2 O studies. © 2013 John Wiley & Sons Ltd.
Binding water to a PEG-linked flexible bichromophore: IR spectra of diphenoxyethane-(H{sub 2}O){sub n} clusters, n = 2-4

Energy Technology Data Exchange (ETDEWEB)

Walsh, Patrick S.; Buchanan, Evan G.; Gord, Joseph R.; Zwier, Timothy S., E-mail: zwier@purdue.edu [Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907-2084 (United States)

2015-04-21

The single-conformation infrared (IR) and ultraviolet (UV) spectroscopies of neutral 1,2-diphenoxyethane-(H{sub 2}O){sub n} clusters with n = 2-4 (labeled henceforth as 1:n) have been studied in a molecular beam using a combination of resonant two-photon ionization, IR-UV holeburning, and resonant ion-dip infrared (RIDIR) spectroscopies. Ground state RIDIR spectra in the OH and CH stretch regions were used to provide firm assignments for the structures of the clusters by comparing the experimental spectra with the predictions of calculations carried out at the density functional M05-2X/6-31+G(d) level of theory. At all sizes in this range, the water molecules form water clusters in which all water molecules engage in a single H-bonded network. Selective binding to the tgt monomer conformer of 1,2-diphenoxyethane (C{sub 6}H{sub 5}-O-CH{sub 2}-CH{sub 2}-O-C{sub 6}H{sub 5}, DPOE) occurs, since this conformer provides a binding pocket in which the two ether oxygens and two phenyl ring π clouds can be involved in stabilizing the water cluster. The 1:2 cluster incorporates a water dimer “chain” bound to DPOE much as it is in the 1:1 complex [E. G. Buchanan et al., J. Phys. Chem. Lett. 4, 1644 (2013)], with primary attachment via a double-donor water that bridges the ether oxygen of one phenoxy group and the π cloud of the other. Two conformers of the 1:3 cluster are observed and characterized, one that extends the water chain to a third molecule (1:3 chain) and the other incorporating a water trimer cycle (1:3 cycle). A cyclic water structure is also observed for the 1:4 cluster. These structural characterizations provide a necessary foundation for studies of the perturbations imposed on the two close-lying S{sub 1}/S{sub 2} excited states of DPOE considered in the adjoining paper [P. S. Walsh et al., J. Chem. Phys. 142, 154304 (2015)].
In vitro characterization of gE negative bovine herpesvirus types 1.1 (BHV-1.1 and 1.2a (BHV-1.2a Caracterização in vitro de herpes vírus bovino tipos 1.1 (BHV-1.1 e 1.2a (BHV-1.2a gE negativos

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Fernando R. Spilki

2004-09-01

Full Text Available This study aimed the in vitro growth characterization of a previously constructed Brazilian bovine herpesvirus 1.2a with a deletion in the glycoprotein E gene (BHV-1.2a gE-. The plaque sizes, penetration and growth kinetics of the Brazilian BHV-1.2a gE- were studied and compared with the parental virus, as well as with a BHV-1.1 gE- recombinant derived from an European BHV-1.1 strain. No statistical differences were observed between the gE- recombinants and the respective parental viruses penetration assays were performed. When single step growth curves were studied, no statistical differences were observed between gE- and parental viruses. However, it was observed that both gE- viruses were excreted from cells in significantly higher titres at 11 hours post infection in comparison with parental viruses. No statistical differences were observed when plaque sizes of parental viruses or gE- viruses we analyzed separately in each cell type. However, both gE- recombinants displayed a significantly reduced plaque areas on three different cell cultures, in comparison with parental viruses, indicating that the lack of gE had the same effect on both BHV-1 subtypes, manifested by a restricted cell-to-cell spread in infected cells.O presente estudo teve como objetivo a caracterização das propriedades de crescimento in vitro de uma amostra brasileira de herpesvírus bovino tipo 1.2a que apresenta uma deleção no gene que codifica a glicoproteína E (BHV-1.2a gE-. Os tamanhos de placa, cinética de penetração e cinética de multiplicação do vírus BHV-1.2a gE- foram estudados e comparados com o vírus parental, bem como com um vírus BHV-1.1 gE- recombinante, o qual é derivado de uma amostra européia de BHV-1.1. Em termos de cinética de penetração, não foram observadas diferenças significativas quando comparados os vírus gE- com os parentais. A determinação da cinética de multiplicação não demonstrou diferenças significativas entre os
(Acetonitrile{2-[bis(pyridin-2-ylmethyl-κ2Namino-κN]-N-(2,6-dimethylphenylacetamide-κO}(perchlorato-κOzinc (acetonitrile{2-[bis(pyridin-2-ylmethyl-κ2Namino-κN]-N-(2,6-dimethylphenylacetamide-κO}zinc tris(perchlorate

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Ove Alexander Høgmoen Åstrand

2013-02-01

Full Text Available In the title salt, [Zn(C22H24N4O(CH3CN][Zn(ClO4(C22H24N4O(CH3CN](ClO43, two differently coordinated zinc cations occur. In the first complex, the metal ion is coordinated by the N,N′,N′′,O-tetradentate acetamide ligand and an acetonitrile N atom, generating an approximate trigonal–bipyramidal coordination geometry, with the O atom in an equatorial site and the acetonitrile N atom in an axial site. In the second complex ion, a perchlorate ion is also bonded to the zinc ion, generating a distorted trans-ZnO2N4 octahedron. Of the uncoordinating perchlorate ions, one lies on a crystallographic twofold axis and one lies close to a twofold axis and has a site occupancy of 0.5. N—H...O and N—H...(O,O hydrogen bonds are observed in the crystal. Disordered solvent molecules occupy about 11% of the unit-cell volume; their contribution to the scattering was removed with the SQUEEZE routine of the PLATON program [Spek (2009. Acta Cryst. D65, 148–155.].
Visible Light Photoelectrochemical Properties of N-Doped TiO2 Nanorod Arrays from TiN

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Zheng Xie

2013-01-01

Full Text Available N-doped TiO2 nanorod arrays (NRAs were prepared by annealing the TiN nanorod arrays (NRAs which were deposited by using oblique angle deposition (OAD technique. The TiN NRAs were annealed at 330°C for different times (5, 15, 30, 60, and 120 min. The band gaps of annealed TiN NRAs (i.e., N-doped TiO2 NRAs show a significant variance with annealing time, and can be controlled readily by varying annealing time. All of the N-doped TiO2 NRAs exhibit an enhancement in photocurrent intensity in visible light compared with that of pure TiO2 and TiN, and the one annealed for 15 min shows the maximum photocurrent intensity owning to the optimal N dopant concentration. The results show that the N-doped TiO2 NRAs, of which the band gap can be tuned easily, are a very promising material for application in photocatalysis.
Constraints on global oceanic emissions of N2O from observations and models

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Buitenhuis, Erik T.; Suntharalingam, Parvadha; Le Quéré, Corinne

2018-04-01

We estimate the global ocean N2O flux to the atmosphere and its confidence interval using a statistical method based on model perturbation simulations and their fit to a database of ΔpN2O (n = 6136). We evaluate two submodels of N2O production. The first submodel splits N2O production into oxic and hypoxic pathways following previous publications. The second submodel explicitly represents the redox transformations of N that lead to N2O production (nitrification and hypoxic denitrification) and N2O consumption (suboxic denitrification), and is presented here for the first time. We perturb both submodels by modifying the key parameters of the N2O cycling pathways (nitrification rates; NH4+ uptake; N2O yields under oxic, hypoxic and suboxic conditions) and determine a set of optimal model parameters by minimisation of a cost function against four databases of N cycle observations. Our estimate of the global oceanic N2O flux resulting from this cost function minimisation derived from observed and model ΔpN2O concentrations is 2.4 ± 0.8 and 2.5 ± 0.8 Tg N yr-1 for the two N2O submodels. These estimates suggest that the currently available observational data of surface ΔpN2O constrain the global N2O flux to a narrower range relative to the large range of results presented in the latest IPCC report.
Isotope signatures of N2O emitted from vegetable soil: Ammonia oxidation drives N2O production in NH4(+)-fertilized soil of North China.

Science.gov (United States)

Zhang, Wei; Li, Yuzhong; Xu, Chunying; Li, Qiaozhen; Lin, Wei

2016-07-08

Nitrous oxide (N2O) is a potent greenhouse gas. In North China, vegetable fields are amended with high levels of N fertilizer and irrigation water, which causes massive N2O flux. The aim of this study was to determine the contribution of microbial processes to N2O production and characterize isotopic signature effects on N2O source partitioning. We conducted a microcosm study that combined naturally abundant isotopologues and gas inhibitor techniques to analyze N2O flux and its isotopomer signatures [δ(15)N(bulk), δ(18)O, and SP (intramolecular (15)N site preference)] that emitted from vegetable soil after the addition of NH4(+) fertilizers. The results show that ammonia oxidation is the predominant process under high water content (70% water-filled pore space), and nitrifier denitrification contribution increases with increasing N content. δ(15)N(bulk) and δ(18)O of N2O may not provide information about microbial processes due to great shifts in precursor signatures and atom exchange, especially for soil treated with NH4(+) fertilizer. SP and associated two end-member mixing model are useful to distinguish N2O source and contribution. Further work is needed to explore isotopomer signature stability to improve N2O microbial process identification.
Formación en género en la universidad: ¿materia de asignaturas específicas o de educación transversal?

OpenAIRE

Asián-Chaves, Rosario; Cabeza Verdugo, Francisca; Rodríguez Sosa, Vicente

2015-01-01

En este artículo se debaten los diferentes resultados de recibir una formación mediante asignaturas específicas o de forma transversal. La persistencia de estereotipos de género y la división sexual del trabajo están relacionadas con la falta de concienciación social, debida, entre otros factores, a la falta de formación en cuestiones de género. Esta formación es necesaria para reflexionar y "construir" los mensajes sobre género para develar las premisas ideológicas y...

Tidal and spatial variability of nitrous oxide (N2O) in Sado estuary (Portugal)

Science.gov (United States)

Gonçalves, Célia; Brogueira, Maria José; Nogueira, Marta

2015-12-01

The estimate of the nitrous oxide (N2O) fluxes is fundamental to assess its impact on global warming. The tidal and spatial variability of N2O and the air-sea fluxes in the Sado estuary in July/August 2007 are examined. Measurements of N2O and other relevant environmental parameters (temperature, salinity, dissolved oxygen and dissolved inorganic nitrogen - nitrate plus nitrite and ammonium) were recorded during two diurnal tidal cycles performed in the Bay and Marateca region and along the estuary during ebb, at spring tide. N2O presented tidal and spatial variability and varied spatially from 5.0 nmol L-1 in Marateca region to 12.5 nmol L-1 in Sado river input. Although the Sado river may constitute a considerable N2O source to the estuary, the respective chemical signal discharge was rapidly lost in the main body of the estuary due to the low river flow during the sampling period. N2O varied with tide similarly between 5.2 nmol L-1 (Marateca) and 10.0 nmol L-1 (Sado Bay), with the maximum value reached two hours after flooding period. The influence of N2O enriched upwelled seawater (˜10.0 nmol L-1) was well visible in the estuary mouth and apparently represented an important contribution of N2O in the main body of Sado estuary. Despite the high water column oxygen saturation in most of Sado estuary, nitrification did not seem a relevant process for N2O production, probably as the concentration of the substrate, NH4+, was not adequate for this process to occur. Most of the estuary functioned as a N2O source, and only Marateca zone has acted as N2O sink. The N2O emission from Sado estuary was estimated to be 3.7 Mg N-N2O yr-1 (FC96) (4.4 Mg N-N2O yr-1, FRC01). These results have implications for future sampling and scaling strategies for estimating greenhouse gases (GHGs) fluxes in tidal ecosystems.
Diaquabis[N,N′-(ethane-1,2-diylbis(isonicotinamide-κN]bis(hydrogen phthalato-κOnickel(II hexahydrate

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Torél Beard

2016-07-01

Full Text Available In the title solvated coordination complex, [Ni(C8H5O42(C14H14N4O22(H2O2]·6H2O, the NiII cation is octahedrally coordinated by trans carboxylate O-atom donors from two crystallographically distinct monodentate hydrogen phthalate (Hpht− ligands, two trans aqua ligands, and trans pyridyl N-atom donors from two crystallographically distinct N,N′-(ethane-1,2-diylbis(isonicotinamide (ebin ligands. Extensive O—H...O and O—H...N hydrogen-bonding patterns involving the water molecules of crystallization anchor neighboring coordination complexes into a three-dimensional network.
Deep-level optical spectroscopy investigation of N-doped TiO2 films

International Nuclear Information System (INIS)

Nakano, Yoshitaka; Morikawa, Takeshi; Ohwaki, Takeshi; Taga, Yasunori

2005-01-01

N-doped TiO 2 films were deposited on n + -GaN/Al 2 O 3 substrates by reactive magnetron sputtering and subsequently crystallized by annealing at 550 deg. C in flowing N 2 gas. The N-doping concentration was ∼8.8%, as determined from x-ray photoelectron spectroscopy measurements. Deep-level optical spectroscopy measurements revealed two characteristic deep levels located at ∼1.18 and ∼2.48 eV below the conduction band. The 1.18 eV level is probably attributable to the O vacancy state and can be active as an efficient generation-recombination center. Additionally, the 2.48 eV band is newly introduced by the N doping and contributes to band-gap narrowing by mixing with the O 2p valence band
Crystal structures of the dioxane hemisolvates of N-(7-bromomethyl-1,8-naphthyridin-2-ylacetamide and bis[N-(7-dibromomethyl-1,8-naphthyridin-2-ylacetamide

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Robert Rosin

2017-10-01

Full Text Available The syntheses and crystal structures of N-(7-bromomethyl-1,8-naphthyridin-2-ylacetamide dioxane hemisolvate, C11H10BrN3O·0.5C4H8O2, (I, and bis[N-(7-dibromomethyl-1,8-naphthyridin-2-ylacetamide] dioxane hemisolvate, 2C11H9Br2N3O·0.5C4H8O2, (II, are described. The molecules adopt a conformation with the N—H hydrogen pointing towards the lone electron pair of the adjacent naphthyridine N atom. The crystals of (I are stabilized by a three-dimensional supramolecular network comprising N—H...N, C—H...N and C—H...O hydrogen bonds, as well as C—Br...π halogen bonds. The crystals of compound (II are stabilized by a three-dimensional supramolecular network comprising N—H...N, C—H...N and C—H...O hydrogen bonds, as well as C—H...π contacts and C—Br...π halogen bonds. The structure of the substituent attached in the 7-position of the naphthyridine skeleton has a fundamental influence on the pattern of intermolecular noncovalent bonding. While the Br atom of (I participates in weak C—Br...Oguest and C—Br...π contacts, the Br atoms of compound (II are involved in host–host interactions via C—Br...O=C, C—Br...N and C—Br...π bonding.
Enhanced visible light photocatalytic activity of g-C3N4 assisted by hydrogen peroxide

Science.gov (United States)

Chen, Quan-Liang; Liu, Yi-Ling; Tong, Li-Ge

2018-04-01

Water pollution has caused much attention nowadays. Photocatalysis as a kind of advanced oxidation technology has been widely studied in the field of environmental pollution control. As a stable non-metal photocatalyst, the photocatalytic activity of g-C3N4 assisted by H2O2 was investigated for the degradation of Rhodamine B (RhB) under visible light irradiation. The combination of g-C3N4 and H2O2 has much higher activity than that of pure g-C3N4 or H2O2. Neutral solution is preferred for the high phtotocatalytic activity of g-C3N4 with H2O2. The effect of the amount of catalyst, H2O2 concentration and RhB concentration was investigated. Photocatalytic mechanism study using radical scavenger showed free radicals {{{{O}}}2}- and · OH are the main active species. g-C3N4 assisted by H2O2 showed good photostability and repeatability after five cycles of degradation experiment.
Highly stable [mambf6-n(o/h2o)n(ligand)2(solvent)x]n metal organic frameworks

KAUST Repository

Eddaoudi, Mohamed; Adil, Karim; Belmabkhout, Youssef; Shekhah, Osama; Bhatt, Prashant M.; Cadiau, Amandine

2016-01-01

Provided herein are metal organic frameworks having high selectivity and stability in the present of gases and vapors including H2S, H2O, and CO2. Metal organic frameworks can comprise metal nodes and N-donor organic ligands. Further provided
Mixed Matrix Membranes for O2/N2 Separation: The Influence of Temperature

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Ana Fernández-Barquín

2016-05-01

Full Text Available In this work, mixed matrix membranes (MMMs composed of small-pore zeolites with various topologies (CHA (Si/Al = 5, LTA (Si/Al = 1 and 5, and Rho (Si/Al = 5 as dispersed phase, and the hugely permeable poly(1-trimethylsilyl-1-propyne (PTMSP as continuous phase, have been synthesized via solution casting, in order to obtain membranes that could be attractive for oxygen-enriched air production. The O2/N2 gas separation performance of the MMMs has been analyzed in terms of permeability, diffusivity, and solubility in the temperature range of 298–333 K. The higher the temperature of the oxygen-enriched stream, the lower the energy required for the combustion process. The effect of temperature on the gas permeability, diffusivity, and solubility of these MMMs is described in terms of the Arrhenius and Van’t Hoff relationships with acceptable accuracy. Moreover, the O2/N2 permselectivity of the MMMs increases with temperature, the O2/N2 selectivities being considerably higher than those of the pure PTMSP. In consequence, most of the MMMs prepared in this work exceeded the Robeson’s upper bound for the O2/N2 gas pair in the temperature range under study, with not much decrease in the O2 permeabilities, reaching O2/N2 selectivities of up to 8.43 and O2 permeabilities up to 4,800 Barrer at 333 K.
(Carbonato-κ(2)O,O')bis-(5,5'-dimethyl-2,2'-bipyridyl-κ(2)N,N')cobalt(III) bromide trihydrate.

Science.gov (United States)

Arun Kumar, Kannan; Meera, Parthsarathi; Amutha Selvi, Madhavan; Dayalan, Arunachalam

2012-04-01

In the title complex, [Co(CO(3))(C(12)H(12)N(2))(2)]Br·3H(2)O, the Co(III) cation has a distorted octa-hedral coordination environment. It is chelated by four N atoms of two different 5,5'-dimethyl-2,2'-bipyridyl (dmbpy) ligands in axial and equatorial positions, and by two O atoms of a carbonate anion completing the equatorial positions. Although the water mol-ecules are disordered and their H atoms were not located, there are typical O⋯O distances between 2.8 and 3.0 Å, indicating O-H⋯O hydrogen bonding. The crystal packing is consolidated by C-H⋯O and C-H⋯Br hydrogen bonds, as well as π-π stacking inter-actions between adjacent pyridine rings of the dmbpy ligands, with centroid-centroid distances of 3.694 (3) and 3.7053 (3) Å.
On Positive Solutions for the Rational Difference Equation Systems x n+1 = A/x n y n (2), and y n+1 = By n /x n-1 y n-1.

Science.gov (United States)

Ma, Hui-Li; Feng, Hui

2014-01-01

Our aim in this paper is to investigate the behavior of positive solutions for the following systems of rational difference equations: x n+1 = A/x n y n (2), and y n+1 = By n /x n-1 y n-1, n = 0,1,…, where x -1, x 0, y -1, and y 0 are positive real numbers and A and B are positive constants.
N-(5-Benzylsulfanyl-1,3,4-thiadiazol-2-yl-2-(piperidin-1-ylacetamide

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D. S. Ismailova

2014-03-01

Full Text Available The title compound, C16H20N4OS2, was synthesized by the reaction of 2-benzylsulfanyl-5-chloroacetamido-1,3,4-thiadiazole and piperidine in a 1:2 ratio. The planes of the acetamide and 1,3,4-thiadiazole units are twisted by 10.8 (4°. The thiadiazole S atom and the acetamide O atom are syn-oriented due to a hypervalent S...O interaction of 2.628 (4 Å. In the crystal, molecules form centrosymmetric dimers via N—H...N hydrogen bonds. These dimers are further connected by C—H...O interactions into (100 layers.
N2O emission under fluidized bed combustion condition

International Nuclear Information System (INIS)

Shen, B.X.; Yao, Q.; Mi, T.; Liu, D.C.; Feng, B.; Winter, Franz

2003-01-01

In this paper, many rules about N 2 O and NO x emission under fluidized bed combustion conditions were found by experiments. The research results indicate that CaO, CaSO 4 , Fe 2 O 3 and char have important influence on decomposition of N 2 O; co-combustion of coal and biomass are effective measures to low N 2 O and NO x emission
In situ growing Bi_2MoO_6 on g-C_3N_4 nanosheets with enhanced photocatalytic hydrogen evolution and disinfection of bacteria under visible light irradiation

International Nuclear Information System (INIS)

Li, Juan; Yin, Yunchao; Liu, Enzhou; Ma, Yongning; Wan, Jun; Fan, Jun; Hu, Xiaoyun

2017-01-01

Graphical abstract: TEM image and schematic diagram of photocatalytic mechanism of Bi_2MoO_6/g-C_3N_4 composite. - Highlights: • BM/CNNs heterojunctions were obtained by an in situ solvothermal method. • 2D CNNs are superior to CN as photocatalysts and supporting materials. • The photocatalytic hydrogen evolution of BM/CNNs has been first studied. • The photocatalytic disinfection of bacteria by BM/CNNs has been first studied. • The photocatalytic mechanism of BM/CNNs heterojunction was described. - Abstract: Bi_2MoO_6/g-C_3N_4 heterojunctions were fabricated by an in situ solvothermal method using g-C_3N_4 nanosheets. The photocatalytic activities of as-prepared samples were evaluated by hydrogen evolution from water splitting and disinfection of bacteria under visible light irradiation. The results indicate that exfoliating bulk g-C_3N_4 to g-C_3N_4 nanosheets greatly enlarges the specific surface area and shortens the diffusion distance for photogenerated charges, which could not only promote the photocatalytic performance but also benefit the sufficient interaction with Bi_2MoO_6. Furthermore, intimate contact of Bi_2MoO_6 (BM) and g-C_3N_4 nanosheets (CNNs) in the BM/CNNs composites facilitates the transfer and separation of photogenetrated electron-hole pairs. 20%-BM/CNNs heterojunction exhibits the optimal photocatalytic hydrogen evolution as well as photocatalytic disinfection of bacteria. Furthermore, h"+ was demonstrated as the dominant reactive species which could make the bacteria cells inactivated in the photocatalytic disinfection process. This study extends new chance of g-C_3N_4-based photocatalysts to the growing demand of clean new energy and drinking water.
Preparation and enhanced photocatalytic activity of carbon nitride/titania(001 vs 101 facets)/reduced graphene oxide (g-C3N4/TiO2/rGO) hybrids under visible light

Science.gov (United States)

Huang, Meina; Yu, Jianhua; Hu, Qun; Su, Wenli; Fan, Minguang; Li, Bin; Dong, Lihui

2016-12-01

Herein, a novel photocatalyst, anatase TiO2 nanoparticles with both exposed (101) and (001) facets synchronously incorporated with g-C3N4 and graphene, was successfully prepared via a simple one-step solvothermal route. The morphology and structure of as-prepared composites were confirmed by X-ray diffraction (XRD), transmission electron microscopy (TEM), N2 adsorption, Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS) and ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS). Efficiency of the prepared samples was investigated by monitoring the degradation of Methyl Orange (MO), Rhodamine B (RhB) and phenol under visible light irradiation. Improved photocatalytic activity in g-C3N4/TiO2/rGO is observed owing to higher specific surface area and enhanced visible light absorption capability. Most importantly, the in situ g-C3N4 and rGO doping might enhance the interaction among g-C3N4, TiO2 (001 vs 101) and rGO, which generates more synergistic heteroconjunctions in g-C3N4/TiO2/rGO facilitating a fast electron transfer at the interface among them. This synergistic approach could prove useful for the design and development of other visible light active photocatalysts with high chemical stability.
Gaseous Nitrogen Losses from Tropical Savanna Soils of Northern Australia: Dynamics, Controls and Magnitude of N2O, NO, and N2 emissions

Science.gov (United States)

Werner, C.; Hickler, T.; Hutley, L. B.; Butterbach-Bahl, K.

2014-12-01

Tropical savanna covers a large fraction of the global land area and thus may have a substantial effect on the global soil-atmosphere exchange of nitrogen. The pronounced seasonality of hygric conditions in this ecosystem affects strongly microbial process rates in the soil. As these microbial processes control the uptake, production, and release of nitrogen compounds, it is thought that this seasonality finally leads to strong temporal dynamics and varying magnitudes of gaseous losses to the atmosphere. However, given their areal extent and in contrast to other ecosystems, still few in-situ or laboratory studies exist that assess the soil-atmosphere exchange of nitrogen. We present laboratory incubation results from intact soil cores obtained from a natural savanna site in Northern Australia, where N2O, NO, and N2 emissions under controlled environmental conditions were investigated. Furthermore, in-situ measurements of high temporal resolution at this site recorded with automated static and dynamic chamber systems are discussed (N2O, NO). This data is then used to assess the performance of a process-based biogeochemical model (LandscapeDNDC), and the potential magnitude and dynamics of components of the site-scale nitrogen cycle where no measurements exist (biological nitrogen fixation and nitrate leaching). Our incubation results show that severe nutrient limitation of the soil only allows for very low N2O emissions (0.12 kg N ha-1 yr-1) and even a periodic N2O uptake. Annual NO emissions were estimated at 0.68 kg N ha-1 yr-1, while the release of inert nitrogen (N2) was estimated at 6.75 kg N ha-1 yr-1 (data excl. contribution by pulse emissions). We observed only minor N2O pulse emissions after watering the soil cores and initial rain events of the dry to wet season transition in-situ, but short-lived NO pulse emissions were substantial. Interestingly, some cores exhibited a very different N2O emission potential, indicating a substantial spatial variability of
Structure of N = 2 supergravity in N = 1 superfields

Energy Technology Data Exchange (ETDEWEB)

Awada, M.A.; Mokhtari, S. (Imperial Coll. of Science and Technology, London (UK). Blackett Lab.)

1985-01-01

A formulation of N = 2 supergravity in N = 1 superspace is presented. The authors solve up to all orders the N = 2 supergravity constraints in terms of unconstrained N = 1 superfields. The structure of the N = 2 action in N = 1 superspace is examined. The proposed action coincides in the quadratic limit of the spin (3/2,1) matter fields with the action given by previous workers.
Phase structure of the O(n) model on a random lattice for n > 2

DEFF Research Database (Denmark)

Durhuus, B.; Kristjansen, C.

1997-01-01

We show that coarse graining arguments invented for the analysis of multi-spin systems on a randomly triangulated surface apply also to the O(n) model on a random lattice. These arguments imply that if the model has a critical point with diverging string susceptibility, then either γ = +1....../2 or there exists a dual critical point with negative string susceptibility exponent, γ̃, related to γ by γ = γ̃/γ̃-1. Exploiting the exact solution of the O(n) model on a random lattice we show that both situations are realized for n > 2 and that the possible dual pairs of string susceptibility exponents are given...... by (γ̃, γ) = (-1/m, 1/m+1), m = 2, 3, . . . We also show that at the critical points with positive string susceptibility exponent the average number of loops on the surface diverges while the average length of a single loop stays finite....
Synthesis of [2-13C, 2-14C] 2-aminoethanol, [1-13C, 1-14C] 2-chloroethylamine, N,N'-bis([1-13C, 1-14C] 2-chloroethyl)-N-nitrosourea(BCNU) and N-([1-13C, 1-14C] 2-chloroethyl)-N-nitrosourea(CNU)

International Nuclear Information System (INIS)

Narayan, R.; Chang, C-j.

1982-01-01

[2- 13 C, 2- 14 C]2-Aminoethanol hydrochloride was prepared in good yield from Na*CN in a two step sequence by first converting the Na*CN to OHCH 2 *CN and then reducing the nitrile directly with a solution of borane-tetrahydrofuran complex. The reaction procedure was simple and the pure product could be obtained readily. Using this specifically labelled precursor, the synthesis of [1- 13 C, 1- 14 C]2-chloroethylamine hydrochloride, N-([1- 13 C, 1- 14 C]2-chloroethyl)-N-nitrosourea(CNU) and N,N'-bis([1- 13 C, 1- 14 C]2-chloroethyl)-N-nitrosourea(BCNU) in good yield without isotope scrambling was also reported. (author)
Ruddlesden-Popper compounds (SrO)(LaFeO3)n (n = 1 and 2) as p-type semiconductors for photocatalytic hydrogen production

International Nuclear Information System (INIS)

Chen, Hongmei; Sun, Xiaoqin; Xu, Xiaoxiang

2017-01-01

Graphical abstract: Two layered ferrites LaSrFeO 4 and La 2 SrFe 2 O 7 have been investigated which demonstrate interesting p-type semconductivity and efficient hydrogen production from water. Display Omitted -- Abstract: Here we report two Ruddlesden-Popper type ferrite perovskites (SrO)(LaFeO 3 ) n (n = 1 and 2) which demonstrate p-type semiconductivity. Their crystal structure, optical absorption and other physicochemical properties have been systematically explored. Our results show that both ferrites crystallize in tetragonal symmetry with structural lamination along c axis. Efficient photocatalytic hydrogen production has been achieved for both samples under full range and visible light illumination. Better performance is noticed for LaSrFeO 4 with apparent quantum efficiency approaches 0.31% and 0.19% under full range and visible light illumination, respectively. The p-type semiconductivity is verified by their cathodic photocurrent as well as negative Mott-Schottky slop during Photoelectrochemical measurement. The relative lower activity for La 2 SrFe 2 O 7 compared to LaSrFeO 4 is likely due to its higher defect concentration which facilitates charge recombination. Both compounds exhibit anisotropic phenomenon for charge migrations according to theoretical calculations. Their p-type semiconductivity, strong visible light absorption, chemical inertness and high abundance of constituent elements signify promising applications in the field of solar energy conversion and optoelectronics.
Synthesis and characterization of sodium vanadium oxide gels: the effects of water (n) and sodium (x) content on the electrochemistry of Na(x)V2O5·nH2O.

Science.gov (United States)

Lee, Chia-Ying; Marschilok, Amy C; Subramanian, Aditya; Takeuchi, Kenneth J; Takeuchi, Esther S

2011-10-28

Sodium vanadium oxide gels, Na(x)V(2)O(5)·nH(2)O, of varying sodium content (0.12 n > 0.01) and interlayer spacing were found to be inversely proportional to the sodium level (x), thus control of sodium (x) content provided a direct, chimie douce approach for control of hydration level (n) and interlayer spacing, without the need for high temperature treatment to affect dehydration. Notably, the use of high temperatures to modify hydration levels can result in crystallization and collapse of the interlayer structure, highlighting the distinct advantage of our novel chimie douce synthesis strategy. Subsequent to synthesis and characterization, results from an electrochemical study of a series of Na(x)V(2)O(5)·nH(2)O samples highlight the significant impact of interlayer water on delivered capacity of the layered materials. Specifically, the sodium vanadium oxide gels with higher sodium content and lower water content provided higher capacities in lithium based cells, where capacity delivered to 2.0 V under C/20 discharge ranged from 170 mAh/g for Na(0.12)V(2)O(5)·0.23H(2)O to 300 mAh/g for Na(0.32)V(2)O(5)·0.01H(2)O. The capacity differences were maintained as the cells were cycled. This journal is © the Owner Societies 2011
μ-Adipato-κ2O1:O4-bis{[2,6-bis(1H-benzimidazol-2-yl-κN3pyridine-κN](nitrato-κOlead(II}

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Lian-Qiang Wei

2010-01-01

Full Text Available The dinuclear title compound, [Pb2(C6H8O4(NO32(C19H13N52], lies with the mid-point of the butyl chain of the bridging adipate unit on a center of inversion. The PbII ion is covalently bonded to the nitrate anion and is bonded to a carboxylate group of the adipate unit by another covalent bond. The N-heterocycle functions in a chelating tridentate mode. The metal atom exists in a Ψ-octahedral coordination environment. When weaker Pb...O interactions are also considered, the geometry is a Ψ-tricapped trigonal prism in which the lone-pair electrons occupy one face of the trigonal prism. Adjacent molecules are linked into a layer structure by N—H...O hydrogen bonds.

Hydrazinium lanthanide oxalates: synthesis, structure and thermal reactivity of N2H5[Ln2(C2O4)4(N2H5)]·4H2O, Ln = Ce, Nd.

Science.gov (United States)

De Almeida, Lucie; Grandjean, Stéphane; Rivenet, Murielle; Patisson, Fabrice; Abraham, Francis

2014-03-28

New hydrazinium lanthanide oxalates N2H5[Ln2(C2O4)4(N2H5)]·4H2O, Ln = Ce (Ce-HyOx) and Nd (Nd-HyOx), were synthesized by hydrothermal reaction at 150 °C between lanthanide nitrate, oxalic acid and hydrazine solutions. The structure of the Nd compound was determined from single-crystal X-ray diffraction data, space group P2₁/c with a = 16.315(4), b = 12.127(3), c = 11.430(2) Å, β = 116.638(4)°, V = 2021.4(7) Å(3), Z = 4, and R1 = 0.0313 for 4231 independent reflections. Two distinct neodymium polyhedra are formed, NdO9 and NdO8N, an oxygen of one monodentate oxalate in the former being replaced by a nitrogen atom of a coordinated hydrazinium ion in the latter. The infrared absorption band at 1005 cm(-1) confirms the coordination of N2H5(+) to the metal. These polyhedra are connected through μ2 and μ3 oxalate ions to form an anionic three-dimensional neodymium-oxalate arrangement. A non-coordinated charge-compensating hydrazinium ion occupies, with water molecules, the resulting tunnels. The N-N stretching frequencies of the infrared spectra demonstrate the existence of the two types of hydrazine ions. Thermal reactivity of these hydrazinium oxalates and of the mixed isotypic Ce/Nd (CeNd-HyOx) oxalate were studied by using thermogravimetric and differential thermal analyses coupled with gas analyzers, and high temperature X-ray diffraction. Under air, fine particles of CeO2 and Ce(0.5)Nd(0.5)O(1.75) are formed at low temperature from Ce-HyOx and CeNd-HyOx, respectively, thanks to a decomposition/oxidation process. Under argon flow, dioxymonocyanamides Ln2O2CN2 are formed.
Comparative analysis of the effects of tantalum doping and annealing on atomic layer deposited (Ta{sub 2}O{sub 5}){sub x}(Al{sub 2}O{sub 3}){sub 1−x} as potential gate dielectrics for GaN/Al{sub x}Ga{sub 1−x}N/GaN high electron mobility transistors

Energy Technology Data Exchange (ETDEWEB)

Partida-Manzanera, T., E-mail: sgtparti@liv.ac.uk [Centre for Materials and Structures, School of Engineering, University of Liverpool, Liverpool, L69 3GH (United Kingdom); Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), Innovis, 2 Fusionopolis way, Singapore 138634 (Singapore); Roberts, J. W.; Sedghi, N.; Potter, R. J. [Centre for Materials and Structures, School of Engineering, University of Liverpool, Liverpool, L69 3GH (United Kingdom); Bhat, T. N.; Zhang, Z.; Tan, H. R.; Dolmanan, S. B.; Tripathy, S. [Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), Innovis, 2 Fusionopolis way, Singapore 138634 (Singapore)

2016-01-14

This paper describes a method to optimally combine wide band gap Al{sub 2}O{sub 3} with high dielectric constant (high-κ) Ta{sub 2}O{sub 5} for gate dielectric applications. (Ta{sub 2}O{sub 5}){sub x}(Al{sub 2}O{sub 3}){sub 1−x} thin films deposited by thermal atomic layer deposition (ALD) on GaN-capped Al{sub x}Ga{sub 1−x}N/GaN high electron mobility transistor (HEMT) structures have been studied as a function of the Ta{sub 2}O{sub 5} molar fraction. X-ray photoelectron spectroscopy shows that the bandgap of the oxide films linearly decreases from 6.5 eV for pure Al{sub 2}O{sub 3} to 4.6 eV for pure Ta{sub 2}O{sub 5}. The dielectric constant calculated from capacitance-voltage measurements also increases linearly from 7.8 for Al{sub 2}O{sub 3} up to 25.6 for Ta{sub 2}O{sub 5}. The effect of post-deposition annealing in N{sub 2} at 600 °C on the interfacial properties of undoped Al{sub 2}O{sub 3} and Ta-doped (Ta{sub 2}O{sub 5}){sub 0.12}(Al{sub 2}O{sub 3}){sub 0.88} films grown on GaN-HEMTs has been investigated. These conditions are analogous to the conditions used for source/drain contact formation in gate-first HEMT technology. A reduction of the Ga-O to Ga-N bond ratios at the oxide/HEMT interfaces is observed after annealing, which is attributed to a reduction of interstitial oxygen-related defects. As a result, the conduction band offsets (CBOs) of the Al{sub 2}O{sub 3}/GaN-HEMT and (Ta{sub 2}O{sub 5}){sub 0.16}(Al{sub 2}O{sub 3}){sub 0.84}/GaN-HEMT samples increased by ∼1.1 eV to 2.8 eV and 2.6 eV, respectively, which is advantageous for n-type HEMTs. The results demonstrate that ALD of Ta-doped Al{sub 2}O{sub 3} can be used to control the properties of the gate dielectric, allowing the κ-value to be increased, while still maintaining a sufficient CBO to the GaN-HEMT structure for low leakage currents.
Poly[μ2-benzene-1,3-dicarboxylato-κ2O:O′-μ2-1,3-di-4-pyridylpropane-κ2N:N′-zinc(II

Directory of Open Access Journals (Sweden)

En Tang

2008-02-01

Full Text Available The title compound, [Zn(C8H4O4(C13H14N2]n, was obtained by the hydrothermal reaction of Zn(OAc2·H2O with 1,3-di-4-pyridylpropane (bpp and isophthalic acid (H2ip. The ZnII ion is coordinated by two bpp and two ip ligands in a distorted tetrahedral environment. Each ligand coordinates in a bridging mode to connect ZnII ions into a three-dimensional diamondoid-type structure.
Constraints on global oceanic emissions of N2O from observations and models

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E. T. Buitenhuis

2018-04-01

Full Text Available We estimate the global ocean N2O flux to the atmosphere and its confidence interval using a statistical method based on model perturbation simulations and their fit to a database of ΔpN2O (n =  6136. We evaluate two submodels of N2O production. The first submodel splits N2O production into oxic and hypoxic pathways following previous publications. The second submodel explicitly represents the redox transformations of N that lead to N2O production (nitrification and hypoxic denitrification and N2O consumption (suboxic denitrification, and is presented here for the first time. We perturb both submodels by modifying the key parameters of the N2O cycling pathways (nitrification rates; NH4+ uptake; N2O yields under oxic, hypoxic and suboxic conditions and determine a set of optimal model parameters by minimisation of a cost function against four databases of N cycle observations. Our estimate of the global oceanic N2O flux resulting from this cost function minimisation derived from observed and model ΔpN2O concentrations is 2.4 ± 0.8 and 2.5 ± 0.8 Tg N yr−1 for the two N2O submodels. These estimates suggest that the currently available observational data of surface ΔpN2O constrain the global N2O flux to a narrower range relative to the large range of results presented in the latest IPCC report.
Bi∼3.785Cd∼3.575Cu∼1.5(PO4)3.5O5.5, a new arrangement of double (n=2) and triple (n=3) [M4Bi2n-2O2n]x+ polycationic ribbons in the bismuth-transition metal oxy-phosphate series

International Nuclear Information System (INIS)

Colmont, Marie; Huve, Marielle; Abraham, Francis; Mentre, Olivier

2004-01-01

This work is dedicated to investigation of new disordered bismuth-containing oxy-phosphates compounds with an original structure type. As previously observed in this series, they are formed of [M 4 Bi 2n-2 O 2n ] x+ polycationic ribbons of width n O(Bi,M) 4 tetrahedra, surrounded by PO 4 groups. In the new crystal structure type, double (=D), triple (=T) and tunnels (=t) alternate along a common axis obeying the TtDtTtDt/TTtTTt sequence in respect to a nomenclature previously described and recalled in this work. The existence this new polymorph has first been detected by electron diffraction in a multi-phased sample. Then, the crystal structure type, i.e., the TtDtTtDt/TTtTTt sequence, has been deduced from HREM images help to a contrast-interpreting code available for these series of polycations-formed compounds. The subsequent compounds formulation leads to a number of new materials that verify the general formula: [Bi 2 (Bi,M) 4 O 4 ] 2 [Bi 4 (Bi,M) 4 O 6 ] 6 (PO 4 ) 28 M x , with x= 2+ , Cd 2+ cations. Single crystals of the nominal [O6Bi 4.57 Cd 3.43 ] 4 +8.57 [O 6 Bi 4 Cd 4 ] 2 +8 [O 4 Bi 2 Cd 3.56 Cu 0.44 ] 2 +6 (PO 4 ) 28 Cu 10.86 have been prepared in a further stage and confirms the predicted crystal structure, Bi ∼3.785 Cd ∼3.575 Cu ∼1.5 (PO 4 ) 3.5 O 5.5 , a=11.506(8)A, b=5.416(4)A, c=53.94 (4)A, β=90.10(1) o , RF=0.0835, RwF=0.0993, SG=A2/m, Z=8. As already observed for other elements of this family such as Bi ∼1.2 M ∼1.2 O 1.5 (PO 4 ), Bi ∼6.2 Cu ∼6.2 O 8 (PO 4 ) 5 or Bi ∼3 Cd ∼3.72 M ∼1.28 O 5 (PO 4 ) 3 (M=Cu, Co, Zn), this compound shows an additional example of PO 4 disorder due to the presence of mixed Bi 3+ /M 2+ sites at the edges of ribbons. The origin and consequence of this so-called disorder mostly occurring on PO 4 configurations is intensively discussed and has been characterized by infrared spectroscopy and by neutron diffraction on similar compounds. It is noticeable that the great number of antagonist PO 4
Ammonium-induced calcium mobilization in 1321N1 astrocytoma cells

International Nuclear Information System (INIS)

Hillmann, Petra; Koese, Meryem; Soehl, Kristina; Mueller, Christa E.

2008-01-01

High blood levels of ammonium/ammonia (NH 4 + /NH 3 ) are associated with severe neurotoxicity as observed in hepatic encephalopathy (HE). Astrocytes are the main targets of ammonium toxicity, while neuronal cells are less vulnerable. In the present study, an astrocytoma cell line 1321N1 and a neuroblastoma glioma hybrid cell line NG108-15 were used as model systems for astrocytes and neuronal cells, respectively. Ammonium salts evoked a transient increase in intracellular calcium concentrations ([Ca 2+ ] i ) in astrocytoma (EC 50 = 6.38 mM), but not in NG108-15 cells. The ammonium-induced increase in [Ca 2+ ] i was due to an intracellular effect of NH 4 + /NH 3 and was independent of extracellular calcium. Acetate completely inhibited the ammonium effect. Ammonium potently reduced calcium signaling by G q protein-coupled receptors (H 1 and M3) expressed on the cells. Ammonium (5 mM) also significantly inhibited the proliferation of 1321N1 astrocytoma cells. While mRNA for the mammalian ammonium transporters RhBG and RhCG could not be detected in 1321N1 astrocytoma cells, both transporters were expressed in NG108-15 cells. RhBG and RhBC in brain may promote the excretion of NH 3 /NH 4 + from neuronal cells. Cellular uptake of NH 4 + /NH 3 was mainly by passive diffusion of NH 3 . Human 1321N1 astrocytoma cells appear to be an excellent, easily accessible human model for studying HE, which can substitute animal studies, while NG108-15 cells may be useful for investigating the role of the recently discovered Rhesus family type ammonium transporters in neuronal cells. Our findings may contribute to the understanding of pathologic ammonium effects in different brain cells, and to the treatment of hyperammonemia
Dissociative ionization of O2 and N2 by electron impact

International Nuclear Information System (INIS)

Deleanu, L.; Stockdale, J.A.

1975-05-01

A crossed molecular-pulsed electron beam apparatus used for the study of dissociative ionization of molecules by electron impact is described. The kinetic energy spectra of O + , N + and N ++ ions formed from dissociation of O 2 and N 2 by impact of threshold to 300 eV electrons measured by a time-of-flight method are presented. The ion energy spectra were obtained as a function of incident electron energy at a fixed electron beam-ion detector angle and at a fixed electron energy for electron beam-ion detector angles between 30 and 110 0 . Four main groups of O + ions were observed peaking at 0.8, 2.0, 3.0, and 5.0 eV kinetic energy. Angular distributions of all four of these groups are essentially isotropic. Four distinct groups of N + ions were observed in the N + kinetic energy spectra peaking at 1.9 eV, 2.2 to 2.5 eV, 3 to 4 eV and 6 to 7.6 eV. The angular distributions for N + ions of various kinetic energies were substantially isotropic. An attempt was made to measure the excitation function of N + from N 2 but the results were not very satisfactory. Nevertheless the excitation function data were analyzed by plotting the N + kinetic energy versus the value of the electron energy at which the abrupt changes in the slope of the excitation functions (''breaks'') occurred. The data on kinetic energy, angular distribution and excitation function of the ionic fragments were used in an attempt to identify the molecular ion states involved in the dissociation process. The kinetic energy spectra of N ++ /N 2 showed at least four major peaks and the total N ++ angular distributions was isotropic. (U.S.)
Spatial Variations in N2O Concentration and Isotopomer Composition off the Peru Coast

Science.gov (United States)

Bourbonnais, A.; Letscher, R. T.; Kock, A.; Bange, H. W.; Altabet, M. A.

2016-02-01

Nitrous oxide (N2O) is a potent greenhouse gas and stratospheric ozone depleting substance. The ocean is an important source of N2O to the atmosphere, accounting for up to about 30% of total emissions. However, the factors controlling N2O production and consumption in oceanic environments are still not understood nor constrained. N2O is a by-product of aerobic nitrification, and is formed by two different pathways: 1) the decomposition of hydroxylamine, an intermediate during ammonium oxidation to nitrite, or 2) the reduction of nitrite to N2O (nitrifier-denitrification). N2O is also an intermediate during denitrification under anoxic conditions. In this study, we measured N2O concentrations and isotopomer ratios, as well as O2, nutrient and biogenic N2 concentrations and the isotopic compositions of nitrate, nitrite and biogenic N2 at several coastal stations during two cruises off the Peru coast (6-14°S, 75-81°W) in December 2012 and January 2013. [N2O] varied from below equilibrium values in the OMZ to up to 238 nmol L-1 at 11 m depth at one of the shallowest stations. The isotopic composition of N2O (bulk δ15N: -5 to 30‰, δ18O: 41 to 95‰, and Site Preference: -3 to 65‰) also varied widely, with important differences between stations. Our results show a strong spatial heterogeneity in the mechanisms controlling N2O production and consumption in coastal upwelling regions, which should be taken into account in oceanic N2O models. We will discuss the contributions from different N2O production processes responsible for the observed extreme N2O accumulations.
The loss of NH2O from the N-hydroxyacetamide radical cation CH3C(O)NHOH+

Science.gov (United States)

Jobst, Karl J.; Burgers, Peter C.; Ruttink, Paul J. A.; Terlouw, Johan K.

2006-08-01

A previous study [Ch. Lifshitz, P.J.A. Ruttink, G. Schaftenaar, J.K. Terlouw, Rapid Commun. Mass Spectrom. 1 (1987) 61] shows that metastable N-hydroxyacetamide ions CH3C(O)NHOH+ (HA-1) do not dissociate into CH3CO+ + NHOH by direct bond cleavage but rather yield CH3CO+ + NH2OE The tandem mass spectrometry based experiments of the present study on the isotopologue CH3C(O)NDOD+ reveal that the majority of the metastable ions lose the NH2O radical as NHDO rather than ND2O. A mechanistic analysis using the CBS-QB3 model chemistry shows that the molecular ions HA-1 rearrange into hydrogen-bridged radical cations [OCC(H2)H...N(H)OH]+ whose acetyl cation component then catalyses the transformation NHOH --> NH2O prior to dissociation. The high barrier for the unassisted 1,2-H shift in the free radical, 43 kcal mol-1, is reduced to a mere 7 kcal mol-1 for the catalysed transformation which can be viewed as a quid-pro-quo reaction involving two proton transfers.
Highly stable [mambf6-n(o/h2o)n(ligand)2(solvent)x]n metal organic frameworks

KAUST Repository

Eddaoudi, Mohamed

2016-10-13

Provided herein are metal organic frameworks having high selectivity and stability in the present of gases and vapors including H2S, H2O, and CO2. Metal organic frameworks can comprise metal nodes and N-donor organic ligands. Further provided are methods of making metal organic frameworks.
Bis[μ-(E-N-(pyridin-3-ylmethylidenehydroxyamine]-κ2N1:N3;κ2N3:N1-bis{[(E-N-(pyridin-3-ylmethylidene-κNhydroxyamine]silver(I} dinitrate

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Shan Gao

2012-12-01

Full Text Available In the centrosymmetric dinuclear title AgI compound, [Ag2(C6H6N2O4](NO32, the aromatic amine-coordinated AgI atom is further bridged by two hydroxylamine molecules that use aromatic and oxime N atoms for bridging, and it exists in a distorted trigonal-planar geometry. In the crystal, the nitrate anions link to the dinuclear compound molecules via O—H...O hydrogen bonds, generating a chain running along the a-axis direction.
(Metformin-κ2N,N′(salicylato-κ2O,O′copper(II trihydrate

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Sandra Julieta Gutiérrez Ojeda

2018-02-01

Full Text Available The hydrous title complex [systematic name: (1,1-dimethylbiguanide-κ2N2,N4(2-oxidobenzoato-κ2O,O′copper(II trihydrate], [Cu(C7H4O3(C4H11N5]·3H2O, was synthesized electrolytically from an ethanolic solution of metformin hydrochloride, acetylsalicylic acid, Pepto-Bismol and a copper sacrificial anode. Diffraction data were collected at 0.56 Å resolution, allowing the accurate determination of H-atom positions in the neutral metformin ligand. Both imine groups in metformin have very similar N=C bond lengths, 1.2978 (17 and 1.3033 (17 Å, and the salicylate dianion behaves as a chelating ligand. The coordination sphere of the copper(II cation deviates marginally from a square-planar arrangement. In the crystal, short Cu...Cu separations of 3.5476 (3 Å are observed, along with classical hydrogen-bonding interactions.
catena-Poly[lead(II-[μ-2,4-diamino-6-(piperidin-1-ylpyrimidine N-oxide-κ2O:O]di-μ-iodido

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Maryam Ranjbar

2009-07-01

Full Text Available The N-oxide O atom of the minoxidil unit in the 1/1 adduct with lead(II iodide, [PbI2(C9H15N5O]n, bridges two PbII atoms, as do each of the I atoms. The bridging interactions give rise to a linear chain motif that propagates along the a axis of the orthorhombic unit cell. The coordination sphere around the six-coordinate PbII atom is a distorted ψ-monocapped octahedron in which the stereochemically active lone pair caps one of the faces defined by the O and I atoms forming the longer Pb—O or Pb—I bonds. The PbII atom lies on a mirror plane; the mirror plane is perpendicular to the pyrimidine ring and it bisects the piperidine ring. The aromatic ring is disordered about the mirror plane with respect to the 1-nitrogen and 5-carbon atoms.
Residual sleepiness after N2O sedation: a randomized control trial [ISRCTN88442975

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Lichtor J Lance

2004-05-01

Full Text Available Abstract Background Nitrous oxide (N2O provides sedation for procedures that result in constant low-intensity pain. How long do individuals remain sleepy after receiving N2O? We hypothesized that drug effects would be apparent for an hour or more. Methods This was a randomized, double blind controlled study. On three separate occasions, volunteers (N = 12 received 100% oxygen or 20% or 40% N2O for 30 min. Dependent measures included the multiple sleep latency test (MSLT, a Drug Effects/Liking questionnaire, visual analogue scales, and five psychomotor tests. Repeated measures analysis of variance was performed with drug and time as factors. Results During inhalation, drug effects were apparent based on the questionnaire, visual analogue scales, and psychomotor tests. Three hours after inhaling 100% oxygen or 20% N2O, subjects were sleepier than if they breathed 40% N2O. No other drug effects were apparent 1 hour after inhalation ceased. Patients did not demonstrate increased sleepiness after N2O inhalation. Conclusion We found no evidence for increased sleepiness greater than 1 hour after N2O inhalation. Our study suggests that long-term effects of N2O are not significant.
Bis(2,3,5,6-tetra-2-pyridylpyrazine-κ3N2,N1,N6iron(II bis(dicyanamidate 4.5-hydrate

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R. Cortés

2010-03-01

Full Text Available In the title compound, [Fe(C24H16N62][N(CN2]2·4.5H2O, the central iron(II ion is hexacoordinated by six N atoms of two tridentate 2,3,5,6-tetra-2-pyridylpyrazine (tppz ligands. Two dicyanamide anions [dca or N(CN2−] act as counter-ions, and 4.5 water molecules act as solvation agents. The structure contains isolated cationic iron(II–tppz complexes and the final neutrality is obtained with the two dicyanamide anions. One of the dicyanamide anions and a water molecule are disordered with an occupancy ratio of 0.614 (8:0.386 (8. O—H...O, O—H...N and C—H...O hydrogen bonds involving dca, water and tppz molecules are observed.
Comparing Cr, and N only doping with (Cr,N)-codoping for enhancing visible light reactivity of TiO2

International Nuclear Information System (INIS)

Li, Yuan; Wang, Wei; Qiu, Xiaofeng; Meyer, Harry M. III; Paranthaman, Mariappan Parans; Eres, Gyula; Zhang, Zhenyu; Gu, Baohua

2011-01-01

The photoreactivity of titania (TiO2) nanoclusters with varying levels of N or Cr-doping, or (Cr,N)-codoping, was systematically investigated using photodegradation of methyl orange in aqueous suspensions. The shifting of the TiO2 absorption edge into the visible spectral region that is primarily attributable to band gap narrowing was found to be a reliable metric for estimating the photoreactivity of the doped nanoclusters. Compared to the weak response with undoped and N-doped TiO2, Cr-doping and (Cr, N)-codoping were found to significantly enhance photodegradation of methyl orange under visible light. The initial reaction rates increase from about 0 to above 1.6 10-2 min-1 when the doping concentration of Cr in TiO2 increases from 0 to 5%. In stark contrast, under UV irradiation, doping is not only ineffective but detrimental to the photoreactivity, and all doping including N or Cr only and (Cr, N)-codoping were found to reduce photoreactivity.
Amplified spontaneous emission from ZnO in n-ZnO/ZnO nanodots-SiO(2) composite/p-AlGaN heterojunction light-emitting diodes.

Science.gov (United States)

Shih, Ying Tsang; Wu, Mong Kai; Li, Wei Chih; Kuan, Hon; Yang, Jer Ren; Shiojiri, Makoto; Chen, Miin Jang

2009-04-22

This study demonstrates amplified spontaneous emission (ASE) of the ultraviolet (UV) electroluminescence (EL) from ZnO at lambda~380 nm in the n-ZnO/ZnO nanodots-SiO(2) composite/p- Al(0.12)Ga(0.88)N heterojunction light-emitting diode. A SiO(2) layer embedded with ZnO nanodots was prepared on the p-type Al(0.12)Ga(0.88)N using spin-on coating of SiO(2) nanoparticles followed by atomic layer deposition (ALD) of ZnO. An n-type Al-doped ZnO layer was deposited upon the ZnO nanodots-SiO(2) composite layer also by the ALD technique. High-resolution transmission electron microscopy (HRTEM) reveals that the ZnO nanodots embedded in the SiO(2) matrix have diameters of 3-8 nm and the wurtzite crystal structure, which allows the transport of carriers through the thick ZnO nanodots-SiO(2) composite layer. The high quality of the n-ZnO layer was manifested by the well crystallized lattice image in the HRTEM picture and the low-threshold optically pumped stimulated emission. The low refractive index of the ZnO nanodots-SiO(2) composite layer results in the increase in the light extraction efficiency from n-ZnO and the internal optical feedback of UV EL into n-ZnO layer. Consequently, significant enhancement of the UV EL intensity and super-linear increase in the EL intensity, as well as the spectral narrowing, with injection current were observed owing to ASE in the n-ZnO layer.
Synthesis and distribution of tritiated N,N`-dibenzoyl-1,3-diaminopropan-2-ol

Energy Technology Data Exchange (ETDEWEB)

Lambert, D.M.; Gallez, Bernard [Universite Catholique de Louvain, Dept. des Sciences Pharmaceutiques, Bruxelles (Belgium)

1996-10-01

Tritiated N,N`-dibenzoyl-1,3-diaminopropan-2-ol, a compound mimicking a diacylglycerol moiety used as a lipid drug carrier was prepared from N,N`-dibenzoyl-1,3-diaminopropan-2-ol by isotopic exchange in the presence of rhodium chloride. Preliminary preparation of the deuterated analog was made in order to assess the position of the substitution. A biodistribution study was carried out in mice after intravenous administration. Five minutes after administration, the level found in the brain was about 9% of the injected dose per g organ. This value decreases to 1 % 3 hours after administration while at the same time radioactive levels measured in the urine increased. (author).
A barrier-free atomic radical-molecule reaction: N (2D) NO2 (2A1) mechanistic study

Science.gov (United States)

Zuo, Ming-Hui; Liu, Hui-Ling; Huang, Xu-Ri; Zhan, Jin-Hui; Sun, Chia-Chung

The reaction of N (2D) radical with NO2 molecule has been studied theoretically using density functional theory and ab initio quantum chemistry method. Singlet electronic state [N2O2] potential energy surfaces (PES) are calculated at the CCSD(T)/aug-cc-pVDZ//B3LYP/6-311+G(d) + ZPE and G3B3 levels of theory. All the involved transition states for generation of (2NO) and (O2 + N2) lie much lower than the reactants. Thus, the novel reaction N + NO2 can proceed effectively even at low temperatures and it is expected to play a role in both combustion and interstellar processes. On the basis of the analysis of the kinetics of all pathways through which the reactions proceed, we expect that the competitive power of reaction pathways may vary with experimental conditions for the title reaction.
(Acetylacetonato-κ2O,O′bis[5-methoxy-2-(naphth[1,2-d][1,3]oxazol-2-ylphenyl-κ2C1,N]iridium(III

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Yuan-Yuan Zhou

2011-10-01

Full Text Available In the title compound, [Ir(C18H12NO22(C5H7O2], the Ir atom is O,O′-chelated by the acetylacetonate group and C,N-chelated by the 2-arylnaphth[1,2-d]oxazole groups. The six-coordinate metal atom displays a distorted octahedral geometry. Intramolecular C—H...O hydrogen bonds occur. In the crystal, intermolecular C—H...O hydrogen bonds link the molecules into columns parallel to the b axis.

Growth of SnO2 Nanoflowers on N-doped Carbon Nanofibers as Anode for Li- and Na-ion Batteries

Science.gov (United States)

Liang, Jiaojiao; Yuan, Chaochun; Li, Huanhuan; Fan, Kai; Wei, Zengxi; Sun, Hanqi; Ma, Jianmin

2018-06-01

It is urgent to solve the problems of the dramatic volume expansion and pulverization of SnO2 anodes during cycling process in battery systems. To address this issue, we design a hybrid structure of N-doped carbon fibers@SnO2 nanoflowers (NC@SnO2) to overcome it in this work. The hybrid NC@SnO2 is synthesized through the hydrothermal growth of SnO2 nanoflowers on the surface of N-doped carbon fibers obtained by electrospinning. The NC is introduced not only to provide a support framework in guiding the growth of the SnO2 nanoflowers and prevent the flower-like structures from agglomeration, but also serve as a conductive network to accelerate electronic transmission along one-dimensional structure effectively. When the hybrid NC@SnO2 was served as anode, it exhibits a high discharge capacity of 750 mAh g-1 at 1 A g-1 after 100 cycles in Li-ion battery and 270 mAh g-1 at 100 mA g-1 for 100 cycles in Na-ion battery, respectively.[Figure not available: see fulltext.
Formation of hydroxyl radicals and kinetic study of 2-chlorophenol photocatalytic oxidation using C-doped TiO2, N-doped TiO2, and C,N Co-doped TiO2 under visible light.

Science.gov (United States)

Ananpattarachai, Jirapat; Seraphin, Supapan; Kajitvichyanukul, Puangrat

2016-02-01

This work reports on synthesis, characterization, adsorption ability, formation rate of hydroxyl radicals (OH(•)), photocatalytic oxidation kinetics, and mineralization ability of C-doped titanium dioxide (TiO2), N-doped TiO2, and C,N co-doped TiO2 prepared by the sol-gel method. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and UV-visible spectroscopy were used to analyze the titania. The rate of formation of OH(•) for each type of titania was determined, and the OH-index was calculated. The kinetics of as-synthesized TiO2 catalysts in photocatalytic oxidation of 2-chlorophenol (2-CP) under visible light irradiation were evaluated. Results revealed that nitrogen was incorporated into the lattice of titania with the structure of O-Ti-N linkages in N-doped TiO2 and C,N co-doped TiO2. Carbon was joined to the Ti-O-C bond in the C-doped TiO2 and C,N co-doped TiO2. The 2-CP adsorption ability of C,N co-doped TiO2 and C-doped TiO2 originated from a layer composed of a complex carbonaceous mixture at the surface of TiO2. C,N co-doped TiO2 had highest formation rate of OH(•) and photocatalytic activity due to a synergistic effect of carbon and nitrogen co-doping. The order of photocatalytic activity per unit surface area was the same as that of the formation rate of OH(•) unit surface area in the following order: C,N co-doped TiO2 > C-doped TiO2 > N-doped TiO2 > undoped TiO2.
Nitration of toluene with N[sub 2]O[sub 5

Energy Technology Data Exchange (ETDEWEB)

Furukawa, Kikuo.; Yoshizawa, Fujiroku.; Akutsu, Yoshiaki.; Arai, Mitsuru.; Tamura, Masamitsu. (The University of Tokyo, Tokyo (Japan). School of Engineering)

1999-06-30

In order to clarify the mechanism of aromatic nitration with N[sub 2]O[sub 5], the nitration of toluene with N[sub 2]O[sub 5] in CCl[sub 4] was carried out and was investigated the yields of the products and the isomer distributions. As a result, the reaction should be very rapid and should involve a typical electrophilic substitution. Moreover, in order to investigate the effect of the solvent, the nitration of toluene with N[sub 2]O[sub 5] powder without CCl[sub 4] was also carried out. The nitration of toluene with N[sub 2]O[sub 5]/N[sub 2]O[sub 4] was also carried out, and the dependence of the isomer distribution and the ratio of produced nitrotoluenes on the ratio of N[sub 2]O[sub 5] was showed. As a result, it is suggested that N[sub 2]O[sub 5] should be dissociated homolytically in CCl[sub 4] and that the aromatic nitration with N[sub 2]O[sub 5] in CCl[sub 4] should proceed with NO[sub 3] as the initial attacking species. The thermal decomposition of N[sub 2]O[sub 5] over 25 degree C should produce a large amount of N[sub 2]O[sub 4](2NO[sub 2]), and the attack of NO[sub 2] on the intermediate [Ar(H)(ONO[sub 2])] should form the intermediates [AR(H)(ONO[sub 2])(H)(NO[sub 2])] following the specific isomer distributions. (author)
Nitration of toluene with N{sub 2}O{sub 5}

Energy Technology Data Exchange (ETDEWEB)

Furukawa, Kikuo.; Yoshizawa, Fujiroku.; Akutsu, Yoshiaki.; Arai, Mitsuru.; Tamura, Masamitsu. [The University of Tokyo, Tokyo (Japan). School of Engineering

1999-06-30

In order to clarify the mechanism of aromatic nitration with N{sub 2}O{sub 5}, the nitration of toluene with N{sub 2}O{sub 5} in CCl{sub 4} was carried out and was investigated the yields of the products and the isomer distributions. As a result, the reaction should be very rapid and should involve a typical electrophilic substitution. Moreover, in order to investigate the effect of the solvent, the nitration of toluene with N{sub 2}O{sub 5} powder without CCl{sub 4} was also carried out. The nitration of toluene with N{sub 2}O{sub 5}/N{sub 2}O{sub 4} was also carried out, and the dependence of the isomer distribution and the ratio of produced nitrotoluenes on the ratio of N{sub 2}O{sub 5} was showed. As a result, it is suggested that N{sub 2}O{sub 5} should be dissociated homolytically in CCl{sub 4} and that the aromatic nitration with N{sub 2}O{sub 5} in CCl{sub 4} should proceed with NO{sub 3} as the initial attacking species. The thermal decomposition of N{sub 2}O{sub 5} over 25 degree C should produce a large amount of N{sub 2}O{sub 4}(2NO{sub 2}), and the attack of NO{sub 2} on the intermediate [Ar(H)(ONO{sub 2})] should form the intermediates [AR(H)(ONO{sub 2})(H)(NO{sub 2})] following the specific isomer distributions. (author)
Visible light water oxidation using a co-catalyst loaded anatase-structured Ti(1-(5x/4))Nb(x)O(2-y-δ)N(y) compound.

Science.gov (United States)

Breault, Tanya M; Brancho, James J; Guo, Ping; Bartlett, Bart M

2013-08-19

The photocatalytic activity of anatase-structured Ti(1-(5x/4))Nb(x)O(2-y-δ)N(y) (x = 0.25, y = 0.02; NbN-25) was examined for water oxidation under UV and visible light irradiation. The semiconductor was prepared by sol-gel processing followed by nitridation in flowing ammonia and exhibits an indirect optical gap of 2.2 eV. Ti(1-(5x/4))Nb(x)O(2-y-δ)N(y) was loaded with RuO2 by an impregnation technique, and optimized conditions reveal that 1 wt % RuO2 generates 16 μmol O2 from water with concomitant IO3(-) reduction after 3 h of illumination under simulated solar radiation at a flux of 600 mW/cm(2) illumination, which corresponds to 6-sun AM1.5G illumination (compared to no detectible O2 without the RuO2 cocatalyst). A series of cut-on filters shows that the catalyst-loaded semiconductor evolves O2 for λ ≤ 515 nm, and a gas-phase mass spectrometry isotope labeling experiment shows that irradiating an iodate solution in H2(18)O in the presence of 1 wt % RuO2 loaded on NbN-25 gives rise to catalytic water oxidation: both (36)O2 and (34)O2 are observed. It is unclear whether (16)O arises from IO3(-) or surface reconstruction on the photocatalyst, but ICP-AES analysis of the postirradiated solution shows no dissolved metal ions.
Canted ferrimagnetism and giant coercivity in the nonstoichiometric double perovskite L a2N i1.19O s0.81O6

Science.gov (United States)

Feng, Hai L.; Reehuis, Manfred; Adler, Peter; Hu, Zhiwei; Nicklas, Michael; Hoser, Andreas; Weng, Shih-Chang; Felser, Claudia; Jansen, Martin

2018-05-01

The nonstoichiometric double perovskite oxide L a2N i1.19O s0.81O6 was synthesized by solid-state reaction and its crystal and magnetic structures were investigated by powder x-ray and neutron diffraction. L a2N i1.19O s0.81O6 crystallizes in the monoclinic double perovskite structure (general formula A2B B'O6 ) with space group P 21/n , where the B site is fully occupied by Ni and the B ' site by 19% Ni and 81% Os atoms. Using x-ray absorption spectroscopy an O s4.5 + oxidation state was established, suggesting the presence of about 50% paramagnetic O s5 + (5 d3 , S =3 /2 ) and 50% nonmagnetic O s4 + (5 d4 , Jeff=0 ) ions at the B ' sites. Magnetization and neutron diffraction measurements on L a2N i1.19O s0.81O6 provide evidence for a ferrimagnetic transition at 125 K. The analysis of the neutron data suggests a canted ferrimagnetic spin structure with collinear N i2 + -spin chains extending along the c axis but a noncollinear spin alignment within the a b plane. The magnetization curve of L a2N i1.19O s0.81O6 features a hysteresis with a very high coercive field, HC=41 kOe , at T =5 K , which is explained in terms of large magnetocrystalline anisotropy due to the presence of Os ions together with atomic disorder. Our results are encouraging to search for rare-earth-free hard magnets in the class of double perovskite oxides.
Functionalization of Fe3O4/SiO2 with N-(2-Aminoethyl-3-aminopropyl for Sorption of [AuCl4]-

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Nuryono Nuryono

2016-08-01

Full Text Available Synthesis of Fe3O4/SiO2 modified with N-(2-aminoethyl-3-aminopropyl group (Fe3O4/SiO2/ED via coating method and its application for adsorption-desorption of anionic gold in aqueous solution have been conducted. The synthesized product was characterized with an X-ray diffractometer (XRD, a Fourier transform infrared (FT-IR spectrophotometer and a transmission electron microscopy (TEM. Adsorption of Au(III was conducted in a batch system and the variables included pH, contact time, and initial concentration were investigated. Results showed that magnetite/silica has been successfully functionalized with N-(2-aminoethyl-3-aminopropyl in a homogeneous system. Kinetics study showed that adsorption of Au(III followed the pseudo-second order model with rate constant of 0.710 g mmol L-1min-1. Furthermore, the experimental data fitted well with the Langmuir isotherm model with the maximum adsorption capacity for Au(III of 142.9 mg g-1 and the energy of 25.0 kJ mol-1. Gold loaded on the Fe3O4/SiO2/ED could be easily desorbed with 0.2 mol L-1 HCl containing 2 wt.% of thiourea with recovery of 99.8%. Fe3O4/SiO2/ED was reusable and stable in 5 cycles of adsorption-desorption with recovery more than 90%. Fe3O4/SiO2/ED showed high selectivity towards Au(III in the multimetal system Au(III/Cu(II/Cr(VI with the coefficient selectivity for αAu-Cu of 227.5and for αAu-Cr of 12.3.
Goldstone mode singularities in O(n models

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J. Kaupužs

2012-12-01

Full Text Available Monte Carlo (MC analysis of the Goldstone mode singularities for the transverse and the longitudinal correlation functions, behaving as G⊥ (k ≅ a k-λ⊥ and G|| (k ≅ b k-λ|| in the ordered phase at k → 0, is performed in the three-dimensional O(n models with n=2, 4, 10. Our aim is to test some challenging theoretical predictions, according to which the exponents λ⊥ and λ|| are non-trivial (3/2⊥||2/a2 (where M is a spontaneous magnetization is universal. The trivial standard-theoretical values are λ⊥=2 and λ||=1. Our earlier MC analysis gives λ⊥=1.955 ± 0.020 and λ|| about 0.9 for the O(4 model. A recent MC estimation of λ||, assuming corrections to scaling of the standard theory, yields λ|| = 0.69 ± 0.10 for the O(2 model. Currently, we have performed a similar MC estimation for the O(10 model, yielding λ⊥ = 1.9723(90. We have observed that the plot of the effective transverse exponent for the O(4 model is systematically shifted down with respect to the same plot for the O(10 model by Δ λ⊥ = 0.0121(52. It is consistent with the idea that 2-λ⊥ decreases for large n and tends to zero at n → ∞. We have also verified and confirmed the expected universality of b M2/a2 for the O(4 model, where simulations at two different temperatures (couplings have been performed.
Evaluation of cross-section data from threshold to 40-60 MeV for specific neutron reactions important for neutron dosimetry applications. Part 1: Evaluation of the excitation functions for the 27Al(n,α)24Na, 55Mn(n,2n)54Mn, 59Co(n,p)59Fe, 59Co(n,2n)58m+gCo and 90Zr(n,2n)89m+gZr reactions

International Nuclear Information System (INIS)

Zolotarev, K.I.

2009-04-01

Evaluations of cross sections and their associated covariance matrices have been carried out for five dosimetry reactions: - excitation functions were re-evaluated for the 27 Al(n,α) 24 Na, 55 Mn(n,2n) 54 Mn and 90 Zr(n,2n) 89m+g Zr reactions over the neutron energy range from threshold to 40 MeV; - excitation functions were re-evaluated for the 59 Co(n,p) 59 Fe and 59 Co(n,2n) 58m+g Co reactions over the neutron energy range from threshold to 60 MeV. Uncertainties in the cross sections for all of those reactions were also derived in the form of relative covariance matrices. Benchmark calculations performed for 235 U thermal fission and 252 Cf spontaneous fission neutron spectra show that the integral cross sections calculated from the newly evaluated excitation functions exhibit improved agreement with related experimental data when compared with the equivalent data from the IRDF-2002 library. (author)
Sterilization of E. coli bacterium in a flowing N2-O2 post-discharge reactor

International Nuclear Information System (INIS)

Villeger, S; Cousty, S; Ricard, A; Sixou, M

2003-01-01

Effective destruction of Escherichia coli (E. coli) bacteria has been obtained in a flowing N 2 -O 2 microwave post-discharge reactor. The sterilizing agents are the O atoms and the UV emissions of NOβ which are produced by N and O atoms recombination in the reactor. In the following plasma conditions: pressure 5 Torr, flow rate 1 L n min -1 , microwave power of 100 W in a quartz tube of 5 mm, an O atom density of 2.5x10 15 cm -3 is measured by NO titration in the post-discharge reactor with UV emission in a N 2 -(5%)O 2 gas mixture. Full destruction of 10 13 cfu ml -1 E. coli is observed after a treatment time of 25 min. (rapid communication)
(Carbonato-κO,O')bis-(1,10-phenan-throline-κN,N')cobalt(III) nitrate monohydrate.

Science.gov (United States)

Andaç, Omer; Yolcu, Zuhal; Büyükgüngör, Orhan

2009-12-12

The crystal structure of the title compound, [Co(CO(3))(C(12)H(8)N(2))(2)]NO(3)·H(2)O, consists of Co(III) complex cations, nitrate anions and uncoordinated water mol-ecules. The Co(III) cation is chelated by a carbonate anion and two phenanthroline ligands in a distorted octa-hedral coordination geometry. A three-dimensional supra-molecular structure is formed by O-H⋯O and C-H⋯O hydrogen bonding, C-H⋯π and aromatic π-π stacking [centroid-centroid distance = 3.995 (1)Å] inter-actions.
Third O2 addition reactions promote the low-temperature auto-ignition of n-alkanes

KAUST Repository

Wang, Zhandong

2016-01-20

Comprehensive low-temperature oxidation mechanisms are needed to accurately predict fuel auto-ignition properties. This paper studies the effects of a previously unconsidered third O2 addition reaction scheme on the simulated auto-ignition of n-alkanes. We demonstrate that this extended low-temperature oxidation scheme has a minor effect on the simulation of n-pentane ignition; however, its addition significantly improves the prediction of n-hexane auto-ignition under low-temperature rapid compression machine conditions. Additional simulations of n-hexane in a homogeneous charge compression ignition engine show that engine-operating parameters (e.g., intake temperature and combustion phasing) are significantly altered when the third O2 addition kinetic mechanism is considered. The advanced combustion phasing is initiated by the formation and destruction of additional radical chain-branching intermediates produced in the third O2 addition process, e.g. keto-dihydroperoxides and/or keto-hydroperoxy cyclic ethers. Our results indicate that third O2 addition reactions accelerate low-temperature radical chain branching at conditions of relevance to advance engine technologies, and therefore these chemical pathways should also be considered for n-alkanes with 6 or more carbon atoms. © 2015 The Combustion Institute.
Analysis of the coexisting pathways for NO and N2O formation in Chernozem using the (15)N-tracer SimKIM-Advanced model.

Science.gov (United States)

Stange, Claus Florian; Spott, Oliver; Russow, Rolf

2013-01-01

The nitrogen (N) cycle consists of a variety of microbial processes. These processes often occur simultaneously in soils, but respond differently to local environmental conditions due to process-specific biochemical restrictions (e.g. oxygen levels). Hence, soil nitrogen cycling (e.g. soil N gas production through nitrification and denitrification) is individually affected through these processes, resulting in the complex and highly dynamic behaviour of total soil N turnover. The development and application of methods that facilitate the quantification of individual contributions of coexisting processes is a fundamental prerequisite for (i) understanding the dynamics of soil N turnover and (ii) implementing these processes in ecosystem models. To explain the unexpected results of the triplet tracer experiment (TTE) of Russow et al. (Role of nitrite and nitric oxide in the processes of nitrification and denitrification in soil: results from (15)N tracer experiments. Soil Biol Biochem. 2009;41:785-795) the existing SimKIM model was extended to the SimKIM-Advanced model through the addition of three separate nitrite subpools associated with ammonia oxidation, oxidation of organic nitrogen (Norg), and denitrification, respectively. For the TTE, individual treatments with (15)N ammonium, (15)N nitrate, and (15)N nitrite were conducted under oxic, hypoxic, and anoxic conditions, respectively, to clarify the role of nitric oxide as a denitrification intermediate during N2O formation. Using a split nitrite pool, this analysis model explains the observed differences in the (15)N enrichments in nitric oxide (NO) and nitrous oxide (N2O) which occurred in dependence on different oxygen concentrations. The change from oxic over hypoxic to anoxic conditions only marginally increased the NO and N2O release rates (1.3-fold). The analysis using the model revealed that, under oxic and hypoxic conditions, Norg-based N2O production was the dominant pathway, contributing to 90 and 50�
The N2O activation by Rh5 clusters. A quantum chemistry study.

Science.gov (United States)

Olvera-Neria, Oscar; Avilés, Roberto; Francisco-Rodríguez, Héctor; Bertin, Virineya; García-Cruz, Raúl; González-Torres, Julio César; Poulain, Enrique

2015-04-01

Nitrous oxide (N2O) is a by-product of exhaust pipe gases treatment produced by motor vehicles. Therefore, the N2O reduction to N2 is necessary to meet the actual environmental legislation. The N2O adsorption and dissociation assisted by the square-based pyramidal Rh5 cluster was investigated using the density functional theory and the zero-order regular approximation (ZORA). The Rh5 sextet ground state is the most active in N2O dissociation, though the quartet and octet states are also active because they are degenerate. The Rh5 cluster spontaneously activates the N2─O cleavage, and the reaction is highly exothermic ca. -75 kcal mol(-1). The N2─O breaking is obtained for the geometrical arrangement that maximizes the overlap and electron transfers between the N2O and Rh5 frontier orbitals. The Rh5 high activity is due to the Rh 3d orbitals are located between the N2O HOMO and LUMO orbitals, which makes possible the interactions between them. In particular, the O 2p states strongly interact with Rh 3d orbitals, which finally weaken the N2─O bond. The electron transfer is from the Rh5 HOMO orbital to the N2O antibonding orbital.
Azobenzene Pd(II) complexes with N^N- and N^O-type ligands

Science.gov (United States)

Nikolaeva, M. V.; Puzyk, An. M.; Puzyk, M. V.

2017-05-01

Methods of synthesis of cyclometalated azobenzene palladium(II) complexes of [Pd(N^N)Azb]ClO4 and [Pd(N^O)Azb]ClO4 types (where Azb- is the deprotonated form of azobenzene; N^N is 2NH3, ethylenediamine, or 2,2'-bipyridine; and (N^O)- is the deprotonated form of amino acid (glycine, α-alanine, β-alanine, tyrosine, or tryptophan)) are developed. The electronic absorption and the electrochemical properties of these complexes are studied.
Aqua{2-(pyridin-2-yl-N-[(pyridin-2-ylmethylidene]ethanamine-κ3N,N′,N′′}(sulfato-κ2O,O′copper(II tetrahydrate

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Daniel Tinguiano

2013-01-01

Full Text Available The title complex, [Cu(SO4(C13H13N3(H2O]·4H2O, was obtained by mixing copper sulfate pentahydrate and 2-(pyridin-2-yl-N-(pyridin-2-ylmethylideneethanamine in ethanol under reflux conditions. The CuII ion shows a Jahn–Teller-distorted octahedral geometry, with equatorial positions occupied by three N atoms from the tridentate ligand (average Cu—N = 2.004 Å and one O atom from a bidentate sulfate anion [Cu—O = 1.963 (2 Å]. The axial positions are occupied by one O atom from a coordinating water molecule [Cu—O = 2.230 (3 Å] and one weakly bonded O atom [Cu—O = 2.750 (2 Å] from the bidentate sulfate ion. The complex molecules are connected through O—H...O hydrogen bonds between the coordinating water molecules and sulfate ions from neighboring complexes, forming a double chain parallel to the c axis. The chains are stabilized through additional hydrogen bonds by one of the non-coordinating water molecules bridging between neighboring strands of the double chains. The remaining three water molecules fill the interstitial space between the double chains and are involved in an intricate hydrogen-bonding network that consolidates the structure.
Potentials in N=2 supergravity

International Nuclear Information System (INIS)

Zinov'ev, Yu.M.

1985-01-01

The potentials and Yukava interactions, that arise while introducing a gauge interaction of vector and scalar multiplets in N=2 supergravity are presented, in this the gauge group may be either compact or noncompact. The scalar multiplets geometry corresponds to nonlinear σ, models of the form Sp(2,2n)/Sp(2)xSp(2n), SU(2,n)/SU(2)SU(n)xU(1) and O(4,n)/O(4)xO(n)
Bis(2,2′-bipyridyl-κ2N,N′(sulfato-κ2O,O′cobalt(II ethane-1,2-diol monosolvate

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Lin Chen

2011-01-01

Full Text Available The title compound, [Co(SO4(C10H8N22]·C2H6O2, has the Co2+ ion in a distorted octahedral CoN4O2 coordination geometry. A twofold rotation axis passes through the Co and S atoms, and through the mid-point of the C—C bond of the ethanediol molecule. In the crystal, the [CoSO4(C10H8N22] and C2H6O2 units are held together by a pair of O—H...O hydrogen bonds.
Nitration of benzene with N{sub 2}O{sub 5}

Energy Technology Data Exchange (ETDEWEB)

Furukawa, Kikuo; Yoshizawa, FUjiroku; Akutsu, Yoshiaki; Arai, Mitsuru; Tamura, Masamitsu [The University of Tokyo, Tokyo (Japan). School of Engineering

1999-08-31

In order to clarify the mechanism of aromatic nitration with N{sub 2}O{sub 5}, the nitrations of benzene and of nitrobenzene with N{sub 2}O{sub 5} were carried out and the yield of the products and the isomer distribution of dinitrobenzenes were investigated. As a result, the isomer distribution of the dinitrobenzenes in the nitration of benzene was quite different from that in the nitration of nitrobenzene. Moreover, the ratio of [dinitrobenzenes]/[nitrobenzene] increased with the reaction temperature. The nitration of benzene with N{sub 2}O{sub 5}/N{sub 2}O{sub 4} was also carried out and showed the dependence of the ratio of [dinitrobenzenes]/[nitrobenzene] on the ratio of N{sub 2}O{sub 4}. As a result, it is suggested that N{sub 2}O{sub 5} should be dissociated homolytically in CCl{sub 4}, that the aromatic nitration with N{sub 2}O{sub 5} over 25 degree C should produce a large amount of N{sub 2}O{sub 4}(2NO{sub 2}) and the attack of NO{sub 2} on the intermediate [Ar(H)(ONO{sub 2})] should form the intermediates [Ar(H)(ONO{sub 2})(H)(NO{sub 2})] following the production of a large amount of dinitrobenzenes. (author)
Infrared spectra and tunneling dynamics of the N2-D2O and OC-D2O complexes in the v2 bend region of D2O.

Science.gov (United States)

Zhu, Yu; Zheng, Rui; Li, Song; Yang, Yu; Duan, Chuanxi

2013-12-07

The rovibrational spectra of the N2-D2O and OC-D2O complexes in the v2 bend region of D2O have been measured in a supersonic slit jet expansion using a rapid-scan tunable diode laser spectrometer. Both a-type and b-type transitions were observed for these two complexes. All transitions are doubled, due to the heavy water tunneling within the complexes. Assuming the tunneling splittings are the same in K(a) = 0 and K(a) = 1, the band origins, all three rotational and several distortion constants of each tunneling state were determined for N2-D2O in the ground and excited vibrational states, and for OC-D2O in the excited vibrational state, respectively. The averaged band origin of OC-D2O is blueshifted by 2.241 cm(-1) from that of the v2 band of the D2O monomer, compared with 1.247 cm(-1) for N2-D2O. The tunneling splitting of N2-D2O in the ground state is 0.16359(28) cm(-1), which is about five times that of OC-D2O. The tunneling splittings decrease by about 26% for N2-D2O and 23% for OC-D2O, respectively, upon excitation of the D2O bending vibration, indicating an increase of the tunneling barrier in the excited vibrational state. The tunneling splittings are found to have a strong dependence on intramolecular vibrational excitation as well as a weak dependence on quantum number K(a).

Poly[(6-carboxypicolinato-κ3O2,N,O6(μ3-pyridine-2,6-dicarboxylato-κ5O2,N,O6:O2′:O6′dysprosium(III

Directory of Open Access Journals (Sweden)

Xu Li

2009-11-01

Full Text Available In the title complex, [Dy(C7H3NO4(C7H4NO4]n, one of the ligands is fully deprotonated while the second has lost only one H atom. Each DyIII ion is coordinated by six O atoms and two N atoms from two pyridine-2,6-dicarboxylate and two 6-carboxypicolinate ligands, displaying a bicapped trigonal-prismatic geometry. The average Dy—O bond distance is 2.40 Å, some 0.1Å longer than the corresponding Ho—O distance in the isotypic holmium complex. Adjacent DyIII ions are linked by the pyridine-2,6-dicarboxylate ligands, forming a layer in (100. These layers are further connected by π–π stacking interactions between neighboring pyridyl rings [centroid–centroid distance = 3.827 (3 Å] and C—H...O hydrogen-bonding interactions, assembling a three-dimensional supramolecular network. Within each layer, there are other π–π stacking interactions between neighboring pyridyl rings [centroid–centroid distance = 3.501 (2 Å] and O—H...O and C—H...O hydrogen-bonding interactions, which further stabilize the structure.
European-scale modelling of groundwater denitrification and associated N2O production

International Nuclear Information System (INIS)

Keuskamp, J.A.; Drecht, G. van; Bouwman, A.F.

2012-01-01

This paper presents a spatially explicit model for simulating the fate of nitrogen (N) in soil and groundwater and nitrous oxide (N 2 O) production in groundwater with a 1 km resolution at the European scale. The results show large heterogeneity of nitrate outflow from groundwater to surface water and production of N 2 O. This heterogeneity is the result of variability in agricultural and hydrological systems. Large parts of Europe have no groundwater aquifers and short travel times from soil to surface water. In these regions no groundwater denitrification and N 2 O production is expected. Predicted N leaching (16% of the N inputs) and N 2 O emissions (0.014% of N leaching) are much less than the IPCC default leaching rate and combined emission factor for groundwater and riparian zones, respectively. - Highlights: ► Groundwater denitrification and N 2 O production was modelled at the European scale. ► In large parts of Europe no groundwater denitrification is expected. ► N leaching and N 2 O emission in Europe are much less than the IPCC default values. - European groundwater denitrification is spatially variable, and associated nitrous oxide production is much less than based on the IPCC default estimate.
Comparative pathology of pigs infected with Korean H1N1, H1N2, or H3N2 swine influenza A viruses.

Science.gov (United States)

Lyoo, Kwang-Soo; Kim, Jeong-Ki; Jung, Kwonil; Kang, Bo-Kyu; Song, Daesub

2014-09-24

The predominant subtypes of swine influenza A virus (SIV) in Korea swine population are H1N1, H1N2, and H3N2. The viruses are genetically close to the classical U.S. H1N1 and triple-reassortant H1N2 and H3N2 viruses, respectively. Comparative pathogenesis caused by Korean H1N1, H1N2, and H3N2 SIV was evaluated in this study. The H3N2 infected pigs had severe scores of gross and histopathological lesions at post-inoculation days (PID) 2, and this then progressively decreased. Both the H1N1 and H1N2 infected pigs lacked gross lesions at PID 2, but they showed moderate to severe pneumonia on PID 4, 7 and 14. The pigs infected with H1N1 had significant scores of gross and histopathological lesions when compared with the other pigs infected with H1N2, H3N2, and mock at PID 14. Mean SIV antigen-positive scores were rarely detected for pigs infected with H1N2 and H3N2 from PID 7, whereas a significantly increased amount of viral antigens were found in the bronchioles and alveolar epithelium of the H1N1infected pigs at PID 14. We demonstrated that Korean SIV subtypes had different pulmonary pathologic patterns. The Korean H3N2 rapidly induced acute lung lesions such as broncho-interstitial pneumonia, while the Korean H1N1 showed longer course of infection as compared to other strains.
Emission of CO{sub 2} and N{sub 2}O from soil cultivated with common bean (Phaseolus vulgaris L.) fertilized with different N sources

Energy Technology Data Exchange (ETDEWEB)

Fernandez-Luqueno, F.; Reyes-Varela, V.; Martinez-Suarez, C.; Reynoso-Keller, R.E.; Mendez-Bautista, J.; Ruiz-Romero, E. [Laboratory of Soil Ecology, Department of Biotechnology and Bioengineering, Cinvestav, Mexico D.F, C.P. 07360 (Mexico); Lopez-Valdez, F. [Laboratory of Soil Ecology, Department of Biotechnology and Bioengineering, Cinvestav, Mexico D.F, C.P. 07360 (Mexico); CIBA, IPN, Tepetitla de Lardizabal, Tlaxcala C.P. 90700 (Mexico); Luna-Guido, M.L. [Laboratory of Soil Ecology, Department of Biotechnology and Bioengineering, Cinvestav, Mexico D.F, C.P. 07360 (Mexico); Dendooven, L., E-mail: dendoove@cinvestav.mx [Laboratory of Soil Ecology, Department of Biotechnology and Bioengineering, Cinvestav, Mexico D.F, C.P. 07360 (Mexico)

2009-07-01

Addition of different forms of nitrogen fertilizer to cultivated soil is known to affect carbon dioxide (CO{sub 2}) and nitrous oxide (N{sub 2}O) emissions. In this study, the effect of urea, wastewater sludge and vermicompost on emissions of CO{sub 2} and N{sub 2}O in soil cultivated with bean was investigated. Beans were cultivated in the greenhouse in three consecutive experiments, fertilized with or without wastewater sludge at two application rates (33 and 55 Mg fresh wastewater sludge ha{sup -1}, i.e. 48 and 80 kg N ha{sup -1} considering a N mineralization rate of 40%), vermicompost derived from the wastewater sludge (212 Mg ha{sup -1}, i.e. 80 kg N ha{sup -1}) or urea (170 kg ha{sup -1}, i.e. 80 kg N ha{sup -1}), while pH, electrolytic conductivity (EC), inorganic nitrogen and CO{sub 2} and N{sub 2}O emissions were monitored. Vermicompost added to soil increased EC at onset of the experiment, but thereafter values were similar to the other treatments. Most of the NO{sub 3}{sup -} was taken up by the plants, although some was leached from the upper to the lower soil layer. CO{sub 2} emission was 375 C kg ha{sup -1} y{sup -1} in the unamended soil, 340 kg C ha{sup -1} y{sup -1} in the urea-amended soil and 839 kg ha{sup -1} y{sup -1} in the vermicompost-amended soil. N{sub 2}O emission was 2.92 kg N ha{sup -1} y{sup -1} in soil amended with 55 Mg wastewater sludge ha{sup -1}, but only 0.03 kg N ha{sup -1} y{sup -1} in the unamended soil. The emission of CO{sub 2} was affected by the phenological stage of the plant while organic fertilizer increased the CO{sub 2} and N{sub 2}O emission, and the yield per plant. Environmental and economic implications must to be considered to decide how many, how often and what kind of organic fertilizer could be used to increase yields, while limiting soil deterioration and greenhouse gas emissions.
European-scale modelling of groundwater denitrification and associated N2O production

KAUST Repository

Keuskamp, J.A.

2012-06-01

This paper presents a spatially explicit model for simulating the fate of nitrogen (N) in soil and groundwater and nitrous oxide (N 2O) production in groundwater with a 1 km resolution at the European scale. The results show large heterogeneity of nitrate outflow from groundwater to surface water and production of N 2O. This heterogeneity is the result of variability in agricultural and hydrological systems. Large parts of Europe have no groundwater aquifers and short travel times from soil to surface water. In these regions no groundwater denitrification and N 2O production is expected. Predicted N leaching (16% of the N inputs) and N 2O emissions (0.014% of N leaching) are much less than the IPCC default leaching rate and combined emission factor for groundwater and riparian zones, respectively. © 2012 Elsevier Ltd. All rights reserved.
Detection mechanism and characteristics of ZnO-based N2O sensors operating with photons

Science.gov (United States)

Jeong, T. S.; Yu, J. H.; Mo, H. S.; Kim, T. S.; Youn, C. J.; Hong, K. J.

2013-11-01

N2O sensors made with ZnO-based ZnCdO films were grown on Pyrex substrates by using the RF co-sputtering method. The structure of the N2O sensor was electrode/sensor/glass/illuminant. The mechanism of the photo-assisted oxidation and reduction process on the surface of the N2O sensors was investigated using light from a UV lamp and violet light emitting diode (LED). For photon exposure wavelengths of 365 and 405 nm, the sensitivity of the ZnO-based ZnCdO sensors was measured. From these measurements, the values of the sensitivity of the sensors with x = 0, 0.01, and 0.05 were found to be S = 1.44, 1.39, and 1.33 under LED light with a wavelength of 405 nm, respectively. These sensitivities were compared to those of SnO2 and WO3 materials measured at operating temperatures of 300-600 °C. Also, under exposure with UV light, the response times were observed to be 130 to 270 sec. These response times were slightly slower than that for the traditional method of thermal heating. However, they indicate that the described photon exposure method for N2O detection can replace the conventional heating mode. Consequently, we demonstrated that portable N2O sensors for room-temperature operation could be fabricated without thermal heating.
Quantum Cascade Laser Measurements of Line Intensities, N2-, O2- and Ar- Collisional Broadening Coefficients of N2O in the 3 Band Near 4.5 m

KAUST Repository

Es-sebbar, Et-touhami; Deli, Meriem; Farooq, Aamir

2016-01-01

This study deals with precise measurements of absolute line intensities, N2-, O2- and Ar- collisional broadening coefficients of N2O in the P-branch of the ν3 vibrational band near 4.5 μm. Collisional broadening coefficients of N2O-air are derived from the N2- and O2- broadening contributions by considering an ideal atmospheric composition. Studies are performed at room temperature for 10 rotational transitions over 2190-2202 cm-1 spectral range using a distributed-feedback quantum cascade laser. To retrieve spectroscopic parameters for each individual transition, measured absorption line shape is simulated within Voigt and Galatry profiles. The obtained results compare well with previous experimental data available in the literature: the discrepancies being less than 4% for most of the probed transitions. The spectroscopic data reported here are very useful for the design of sensors used to monitor the abundance of N2O in earth's atmosphere. © The Author(s) 2016.
Quantum Cascade Laser Measurements of Line Intensities, N2-, O2- and Ar- Collisional Broadening Coefficients of N2O in the 3 Band Near 4.5 m

KAUST Repository

Es-sebbar, Et-touhami

2016-04-19

This study deals with precise measurements of absolute line intensities, N2-, O2- and Ar- collisional broadening coefficients of N2O in the P-branch of the ν3 vibrational band near 4.5 μm. Collisional broadening coefficients of N2O-air are derived from the N2- and O2- broadening contributions by considering an ideal atmospheric composition. Studies are performed at room temperature for 10 rotational transitions over 2190-2202 cm-1 spectral range using a distributed-feedback quantum cascade laser. To retrieve spectroscopic parameters for each individual transition, measured absorption line shape is simulated within Voigt and Galatry profiles. The obtained results compare well with previous experimental data available in the literature: the discrepancies being less than 4% for most of the probed transitions. The spectroscopic data reported here are very useful for the design of sensors used to monitor the abundance of N2O in earth\\'s atmosphere. © The Author(s) 2016.
Comparative pathology of pigs infected with Korean H1N1, H1N2, or H3N2 swine influenza A viruses

OpenAIRE

Lyoo, Kwang-Soo; Kim, Jeong-Ki; Jung, Kwonil; Kang, Bo-Kyu; Song, Daesub

2014-01-01

Background The predominant subtypes of swine influenza A virus (SIV) in Korea swine population are H1N1, H1N2, and H3N2. The viruses are genetically close to the classical U.S. H1N1 and triple-reassortant H1N2 and H3N2 viruses, respectively. Comparative pathogenesis caused by Korean H1N1, H1N2, and H3N2 SIV was evaluated in this study. Findings The H3N2 infected pigs had severe scores of gross and histopathological lesions at post-inoculation days (PID) 2, and this then progressively decrease...
Temperature dependent electrical characterisation of Pt/HfO{sub 2}/n-GaN metal-insulator-semiconductor (MIS) Schottky diodes

Energy Technology Data Exchange (ETDEWEB)

Shetty, Arjun, E-mail: arjun@ece.iisc.ernet.in; Vinoy, K. J. [Electrical Communication Engineering, Indian Institute of Science, Bangalore, India 560012 (India); Roul, Basanta; Mukundan, Shruti; Mohan, Lokesh; Chandan, Greeshma; Krupanidhi, S. B. [Materials Research Centre, Indian Institute of Science, Bangalore, India 560012 (India)

2015-09-15

This paper reports an improvement in Pt/n-GaN metal-semiconductor (MS) Schottky diode characteristics by the introduction of a layer of HfO{sub 2} (5 nm) between the metal and semiconductor interface. The resulting Pt/HfO{sub 2}/n-GaN metal-insulator-semiconductor (MIS) Schottky diode showed an increase in rectification ratio from 35.9 to 98.9(@ 2V), increase in barrier height (0.52 eV to 0.63eV) and a reduction in ideality factor (2.1 to 1.3) as compared to the MS Schottky. Epitaxial n-type GaN films of thickness 300nm were grown using plasma assisted molecular beam epitaxy (PAMBE). The crystalline and optical qualities of the films were confirmed using high resolution X-ray diffraction and photoluminescence measurements. Metal-semiconductor (Pt/n-GaN) and metal-insulator-semiconductor (Pt/HfO{sub 2}/n-GaN) Schottky diodes were fabricated. To gain further understanding of the Pt/HfO{sub 2}/GaN interface, I-V characterisation was carried out on the MIS Schottky diode over a temperature range of 150 K to 370 K. The barrier height was found to increase (0.3 eV to 0.79 eV) and the ideality factor decreased (3.6 to 1.2) with increase in temperature from 150 K to 370 K. This temperature dependence was attributed to the inhomogeneous nature of the contact and the explanation was validated by fitting the experimental data into a Gaussian distribution of barrier heights.
N 2 O Emissions and Inorganic N Release Following Incorporation ...

African Journals Online (AJOL)

West African Journal of Applied Ecology ... The results from the study demonstrated that whilst there is the potential for N2O emission to be controlled through varying ratios of residue:fertiliser input, the magnitude and direction of interactions between these N sources vary between different species as a result of their ...
Biologically fixed N2 as a source for N2O production in a grass–clover mixture, measured by 15N2 (erratum i vol. 74 p. 203)

DEFF Research Database (Denmark)

Carter, Mette Sustmann; Ambus, P.

2006-01-01

The contribution of biologically fixed dinitrogen (N-2) to the nitrous oxide (N2O) production in grasslands is unknown. To assess the contribution of recently fixed N-2 as a source of N2O and the transfer of fixed N from clover to companion grass, mixtures of white clover and perennial ryegrass...
N2O fluxes over a corn field from an open-path, laser-based eddy covariance system and static chambers

Science.gov (United States)

Tao, L.; Pan, D.; Gelfand, I.; Abraha, M.; Moyer, R.; Poe, A.; Sun, K.; Robertson, P.; Zondlo, M. A.

2015-12-01

Nitrous oxide (N2O) is important greenhouse and ozone-depleting gase. Although many efforts have been paid to N2O emissions, the spatial and temporal variability of N2O emissions still subject to large uncertainty. Application of the eddy covariance method for N2O emissions research would allow continuous ecosystem level flux measurements. The caveat, however, is need for high precision and high frequency measurements in field. In this study, an open-path, quantum cascade-laser-based eddy covariance N2O sensor has been deployed nearly continuously since May 2015 over a corn field at the W.K. Kellogg Biological Station site in SW Michigan. The field precision of the N2O sensor was assessed to be 0.1 ppbv at 10 Hz, and the total consumption was ~ 40 W, allowing the system to be powered solely by solar panels. The stability of the sensor under different temperature and humidity was tested within an environmental chamber. Spectroscopic experiments and cospectra analyses were carried out to study specific corrections associated with the sensor for eddy covariance techniques, including the line broadening effect due to water vapor and high frequency flux attenuation owning to sample path averaging. Ogive analyses indicated that the high-frequency N2O flux loss due to various damping effects was comparable to those of the CO2 flux. The detection limit of flux was estimated to be 0.3 ng N s-1 m-2 with a flux averaging interval of 30 minutes. The results from the EC system were also compared with ground measurements by standard static chambers (SC). Overall, more than 150 individual chamber measurements were taken within the footprint of the EC system. We found good correlation between the EC and SC methods given the spatiotemporal differences between the two techniques (R2 = 0.75). Both methods detected increased emissions during afternoon as compared to morning and night hours. Differences between EC and SC were also studied by investigating spatial variability with a
Minimizing N2O emissions and carbon footprint on a full-scale activated sludge sequencing batch reactor.

Science.gov (United States)

Rodriguez-Caballero, A; Aymerich, I; Marques, Ricardo; Poch, M; Pijuan, M

2015-03-15

A continuous, on-line quantification of the nitrous oxide (N2O) emissions from a full-scale sequencing batch reactor (SBR) placed in a municipal wastewater treatment plant (WWTP) was performed in this study. In general, N2O emissions from the biological wastewater treatment system were 97.1 ± 6.9 g N2O-N/Kg [Formula: see text] consumed or 6.8% of the influent [Formula: see text] load. In the WWTP of this study, N2O emissions accounted for over 60% of the total carbon footprint of the facility, on average. Different cycle configurations were implemented in the SBR aiming at reaching acceptable effluent values. Each cycle configuration consisted of sequences of aerated and non-aerated phases of different time length being controlled by the ammonium set-point fixed. Cycles with long aerated phases showed the largest N2O emissions, with the consequent increase in carbon footprint. Cycle configurations with intermittent aeration (aerated phases up to 20-30 min followed by short anoxic phases) were proven to effectively reduce N2O emissions, without compromising nitrification performance or increasing electricity consumption. This is the first study in which a successful operational strategy for N2O mitigation is identified at full-scale. Copyright © 2014 Elsevier Ltd. All rights reserved.
Bis(1,10-phenanthroline-κ2N,N′(sulfato-Ocopper(II ethane-1,2-diol monosolvate

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Kai-Long Zhong

2011-09-01

Full Text Available In the title compound, [Cu(SO4(C12H8N22]·C2H6O2, the CuII ion is five-coordinated in a distorted square-pyramidal manner by four N atoms from two chelating 1,10-phenanthroline (phen ligands and one O atom from a monodentate sulfate anion. The four N atoms comprise a square and the one O atom the apex of a square pyramid. The two chelating N2C2 groups are oriented at 71.1 (2°. In the crystal, the components are connected by intermolecular O—H...O hydrogen bonding. The presence of pseudosymmetry in the structure suggests the higher symmetry space group C2/c, but attempts to refine the structure in this space group resulted in an unsatisfactory model.
Solvent-Mediated Synthesis of M(II-Coordination Polymer Part 1: Crystal Structure of Poly(1,2-di(4-pyridylethylene-k2N,N'-bis(1,4-benzenediacetato-k4O,O′,O′′,O′′'zinc(II], C22H18ZnN2O4

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Stephen Adie Adalikwu

2017-08-01

Full Text Available An interaction of water-methanol solution of sodium1,4-benzenediacetate (bda and 4,4′-bipyridylethelene (bpee with aqueous solution of Zn(NO32·6H2O at room temperature yielded colourless crystals of 1 after three weeks in a sealed glass tube. The compound with composition C22H18ZnN2O4 crystallizes in monoclinic space group P21/c, with the following cell dimensions: a = 10.4566(2, b = 13.3085(2, c = 13.7189(2 Å, β = 101.491(1°. In the structure of 1, two Zn(II neighbours are connected by two bda ligands adopting chelating and bidentate-bridging coordination modes to form a dimeric unit (Zn2O8N4 with the Zn–Zn distance of 4.0432(6 Å. The carboxyl-bridged dimeric units are extended along the [001] direction by bpee co-ligands and further linked by bda ligand to form a three-dimensional network structure. The IR shows the characteristic bands of the carboxylates at 1611/1507 cm−1 and 1424/1373 cm−1, respectively, for asymmetric and symmetric stretching −CO2− vibrations. The separation ∆[νasym(CO2− − νsym(CO2−] values of 187 and 134 cm−1 are indicative of chelating and bidentate bridging coordination modes of the carboxylate to the metal centre.
Adiposidade corporal, mas não resistência insulínica, associa-se ao polimorfismo -675 4G/5G no gene PAI-1 em uma amostra de crianças mexicanas

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Ulises de la Cruz-Mosso

2013-10-01

Full Text Available OBJETIVO: Elaboramos este estudo para avaliar se o polimorfismo -675 4G/5G no gene inibidor 1 do ativador do plasminogênio se associa à obesidade e à resistência insulínica em crianças mexicanas. MÉTODOS: Foi realizado um estudo transversal em 174 crianças, 89 delas com peso normal e 85 obesas, variando sua idade de 6 a 13 anos. Todas as crianças eram do estado de Guerrero e foram recrutadas de três escolas primárias na cidade de Chilpancingo, México. Os níveis de insulina foram determinados por prova imunoenzimática. Foi usado o modelo de avaliação da homeostase para determinar resistência insulínica. O polimorfismo -675 4G/5G no gene PAI-1 foi analisado pelo método reação de polimerase em cadeia-polimorfismo no comprimento dos fragmentos de restrição. RESULTADOS: A prevalência de resistência insulínica no grupo obeso foi mais alta (49,41% do que no grupo com peso normal (16,85%. O polimorfismo 4G/5G do PAI-1 foi encontrado em equilíbrio de Hardy Weinberg. O genótipo 4G/5G contribuiu para um aumento significativo da relação cintura-quadril (β = 0,02, p = 0,006, da circunferência da cintura (β = 4,42, p = 0,009 e da espessura da prega subescapular (β = 1,79, p = 0,04, mas não se relacionou com a resistência insulínica. CONCLUSÃO: O genótipo -675 4G/5G do gene PAI-1 se associou a aumento da adiposidade corporal em crianças mexicanas.
Collisional Removal of OH (X (sup 2)Pi, nu=7) by O2, N2, CO2, and N2O

Science.gov (United States)

Knutsen, Karen; Dyer, Mark J.; Copeland, Richard A.

1996-01-01

Collisional removal rate constants for the OH (X 2PI, nu = 7) radical are measured for the colliders O2, CO2, and N2O, and an upper limit is established for N2. OH(nu = 4) molecules, generated in a microwave discharge flow cell by the reaction of hydrogen atoms with ozone, are excited to v = 7 by the output of a pulsed infrared laser via direct vibrational overtone excitation. The temporal evolution of the P = 7 population is probed as a function of the collider gas partial pressure by a time-delayed pulsed ultraviolet laser. Fluorescence from the B 21 + state is detected in the visible spectral region.
Tetraaquatetrakis{μ3-3,3′-[(E,E-ethane-1,2-diylbis(nitrilomethylidyne]benzene-1,2-diolato}octazinc(II N,N-dimethylformamide hexasolvate

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Lan-Sun Zheng

2009-12-01

Full Text Available The asymmetric unit of the title compound [Zn8(C16H12N2O44(H2O4]·6C3H7NO, consists of eight ZnII cations, four tetravalent anionic ligands, L4− (L4− = 3,3′-(1E,1′E-(ethane-1,2-diylbis(azan-1-yl-1-ylidenebis(methan-1-yl-1-ylidenedibenzene-1,2-bis(olate, four coordinated water molecules and six N,N-dimethylformamide solvate molecules. The coordination complex comprises an octanuclear ZnII unit with its ZnII centers coordinated in two discrete distorted square-pyramidal geometries. Four ZnII atoms each coordinate to two nitrogen atoms and two phenolate oxygen atoms from an individual L4− ligand and one coordinated water molecule. The other four ZnII atoms each bind to five phenolate oxygen atoms from three different L4− ligands. In the crystal structure, the ZnII complex unit, coordinated water molecules and dimethylformamide solvate molecules are linked via O—H...O and C—H...O hydrogen bonds. Molecules are connected by additional intermolecular O—H...O and C—H...O hydrogen bonds, forming an extensive three dimensional framework.
A New High-Resolution N2O Emission Inventory for China in 2008

Science.gov (United States)

Shang, Z.; Zhou, F.; Ciais, P.; Tao, S.; Piao, S.; Raymond, P. A.; He, C.; Li, B.; Wang, R.; Wang, X.; Peng, S.; Zeng, Z.; Chen, H.; Ying, N.; Hou, X.; Xu, P.

2014-12-01

The amount and geographic distribution of N2O emissions over China remain largely uncertain. Most of existing emission inventories use uniform emission factors (EFs) and the associated parameters and apply spatial proxies to downscale national or provincial data, resulting in the introduction of spatial bias. In this study, county-level and 0.1° × 0.1° gridded anthropogenic N2O emission inventories for China (PKU-N2O) in 2008 are developed based on high-resolution activity data and regional EFs and parameters. These new estimates are compared with estimates from EDGAR v4.2, GAINS-China, National Development and Reform Commission of China (NDRC), and with two sensitivity tests: one that uses high-resolution activity data but the default IPCC methodology (S1) and the other that uses regional EFs and parameters but starts from coarser-resolution activity data. The total N2O emissions are 2150 GgN2O/yr (interquartile range from 1174 to 2787 GgN2O/yr). Agriculture contributes 64% of the total, followed by energy (17%), indirect emissions (12%), wastes (5%), industry (2.8%), and wildfires (0.2%). Our national emission total is 17% greater than that of the EDGAR v4.2 global product sampled over China and is also greater than the GAINS-China, NDRC, and S1 estimates by 10%, 50%, and 17%, respectively. We also found that using uniform EFs and parameters or starting from national/provincial data causes systematic spatial biases compared to PKU-N2O. In addition, the considerable differences between the relative contributions of the six sectors across the six Agro-Climate Zones primarily reflect the different distributions of industrial activities and land use. Eastern China (8.7% area of China) is the largest contributor of N2O emissions and accounts for nearly 25% of the total. Spatial analysis also shows nonlinear relationships between N2O emission intensities and urbanization. Per-capita and per-GDP N2O emissions increase gradually with an increase in the urban

CO2 and N2O emissions from an Andisol in Chile under a no-till system using non-fixed closed chambers Emisiones de CO2 y N2O desde un Andisol de Chile bajo sistema de cero labranza usando cámaras cerradas no-fijas

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Cristina Muñoz

2011-06-01

realizado todavía en Chile. Este trabajo tiene como objetivo determinar los flujos de emisiones in situ de CO2 y N2O desde un suelo derivado de cenizas volcánicas bajo diferentes prácticas de manejo agronómico determinando su variación estacional. Las muestras gaseosas fueron obtenidas desde el espacio aéreo de cámaras cerradas no-fijas en una rotación anual de cultivos bajo sistema de cero labranza en un Andisol del Sur de Chile (36° S. Dos fuentes de N (NH4+ y NO3- y fertilización amoniacal más dos dosis de encalado (0.5 y 1 Mg ha-1 fueron considerados como tratamientos. Los flujos de CO2 y N2O fueron determinados periódicamente en un período de 1 año y variables de suelo tales como temperatura, contenido de agua, y N mineral fueron registrados. Los resultados muestran que los flujos de CO2 responden a patrones de estacionalidad. No fue evidenciado un efecto cuando fue considerada la práctica de manejo del cultivo, con un máximo de 53.2 ± 8.5 kg CO2-C ha-1 d-1 en la estación húmeda de otoño, y un mínimo de 9.7 ± 2.1 kg CO2-C ha-1 d-1 para verano, estación seca de otoño e invierno. El flujo de N2O fue altamente variable en el año y no muestra influencia de tratamientos o estacionalidad, con un promedio de 2.6 ± 0.6 g N2O-N ha-1 d-1. Variaciones de N mineral del suelo no están relacionadas a los flujos de GHG como una variable sola. Los resultados indican que un Andisol bajo sistema de cero labranza en el Sur de Chile tiene un bajo potencial de emisiones de N2O, y las mayores emisiones de CO2 son producidas principalmente en estaciones húmedas (otoño húmedo y/o primavera.
Effects of temperature on nitrous oxide (N2O) emission from intensive aquaculture system.

Science.gov (United States)

Paudel, Shukra Raj; Choi, Ohkyung; Khanal, Samir Kumar; Chandran, Kartik; Kim, Sungpyo; Lee, Jae Woo

2015-06-15

This study examines the effects of temperature on nitrous oxide (N2O) emissions in a bench-scale intensive aquaculture system rearing Koi fish. The water temperature varied from 15 to 24 °C at interval of 3 °C. Both volumetric and specific rate for nitrification and denitrification declined as the temperature decreased. The concentrations of ammonia and nitrite, however, were lower than the inhibitory level for Koi fish regardless of temperature. The effects of temperature on N2O emissions were significant, with the emission rate and emission factor increasing from 1.11 to 1.82 mg N2O-N/d and 0.49 to 0.94 mg N2O-N/kg fish as the temperature decreased from 24 to 15 °C. A global map of N2O emission from aquaculture was established by using the N2O emission factor depending on temperature. This study demonstrates that N2O emission from aquaculture is strongly dependent on regional water temperatures as well as on fish production. Copyright © 2015 Elsevier B.V. All rights reserved.
Comparison of N2O5 mixing ratios during NO3Comp 2007 in SAPHIR

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A. W. Rollins

2012-11-01

Full Text Available N2O5 detection in the atmosphere has been accomplished using techniques which have been developed during the last decade. Most techniques use a heated inlet to thermally decompose N2O5 to NO3, which can be detected by either cavity based absorption at 662 nm or by laser-induced fluorescence. In summer 2007, a large set of instruments, which were capable of measuring NO3 mixing ratios, were simultaneously deployed in the atmosphere simulation chamber SAPHIR in Jülich, Germany. Some of these instruments measured N2O5 mixing ratios either simultaneously or alternatively. Experiments focused on the investigation of potential interferences from, e.g., water vapour or aerosol and on the investigation of the oxidation of biogenic volatile organic compounds by NO3. The comparison of N2O5 mixing ratios shows an excellent agreement between measurements of instruments applying different techniques (3 cavity ring-down (CRDS instruments, 2 laser-induced fluorescence (LIF instruments. Datasets are highly correlated as indicated by the square of the linear correlation coefficients, R2, which values were larger than 0.96 for the entire datasets. N2O5 mixing ratios well agree within the combined accuracy of measurements. Slopes of the linear regression range between 0.87 and 1.26 and intercepts are negligible. The most critical aspect of N2O5 measurements by cavity ring-down instruments is the determination of the inlet and filter transmission efficiency. Measurements here show that the N2O5 inlet transmission efficiency can decrease in the presence of high aerosol loads, and that frequent filter/inlet changing is necessary to quantitatively sample N2O5 in some environments. The analysis of data also demonstrates that a general correction for degrading filter transmission is not applicable for all conditions encountered during this campaign. Besides the effect of a gradual degradation of the inlet transmission efficiency aerosol exposure, no other interference
Aquachlorido{6,6′-dimethoxy-2,2′-[ethane-1,2-diylbis(nitrilomethanylylidene]diphenolato-κ2O1,N,N′,O1′}cobalt(III dimethylformamide monosolvate

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Yun Wei

2012-04-01

Full Text Available In the title compound, [Co(C18H18N2O4Cl(H2O]·C3H7NO, the CoIII ion is six-coordinated by a tetradentate 6,6′-dimethoxy-2,2′-[ethane-1,2-diylbis(nitrilomethanylylidene]diphenolate ligand, with a chloride ion and an aqua ligand in the apical positions. The compound crystallized as a dimethylformamide (DMF monosolvate. In the crystal, complex molecules are linked via O—Hwater...O hydrogen bonds to form a dimer-like arrangement. These dimers are linked via a C—H...Cl interaction, and the DMF molecule is linked to the complex molecule by C—H...O interactions.
Hierarchical magnetic petal-like Fe3O4-ZnO@g-C3N4 for removal of sulfamethoxazole, suppression of photocorrosion, by-products identification and toxicity assessment.

Science.gov (United States)

Mirzaei, Amir; Chen, Zhi; Haghighat, Fariborz; Yerushalmi, Laleh

2018-08-01

Herein, a petal-like photocatalyst, Fe 3 O 4 -ZnO@g-C 3 N 4 (FZG) with different g-C 3 N 4 to ZnO ratios was synthesized with hierarchical structure. The FZG1 photocatalyst, having the weight ratio of 1:1 for the initial urea and Fe 3 O 4 -ZnO (Fe-ZnO), presented the highest sulfamethoxazole (SMX) degradation rate of 0.0351 (min -1 ), which was 2.6 times higher than that of pristine ZnO. Besides the facile separation, the performance of photocatalyst was improved due to the function of iron oxide as an electron acceptor that reduced the electron/hole recombination rate. The coating of g-C 3 N 4 on the Fe-ZnO surface not only acted as a protective layer for ZnO against photocorrosion, but it also enhanced the photocatalytic activity of the catalyst for SMX degradation through the heterojunction mechanism. By using the FZG1 photocatalyst, 95% SMX removal was obtained after 90 min reaction, while 47% COD and 30% TOC removal were achieved after 60 min treatment under a low energy-consuming UV lamp (10 W). Moreover, a substantial reduction in the solution toxicity was shown after the treatment, as compared with the SMX solution before treatment. The LC-HR-MS/MS analysis results showed that the concentration of most detected by-products produced after 90 min reaction by FZG1 was considerably lower than those obtained using other synthesized photocatalysts. By performing radical scavenging experiments, OH ° radical was found to be the major reactive species. The FZG1 photocatalyst also displayed excellent reusability in five cycles and the leaching of zinc and iron ions was reduced by 54% and ∼100%, respectively, after coating Fe-ZnO with g-C 3 N 4 . Copyright © 2018 Elsevier Ltd. All rights reserved.
[KDy(Hptc3(H3ptc]n·2n(Hbipy·5n(H2O, a Layered Coordination Polymer Containing DyO6N3 Tri-Capped Trigonal Prisms (H3ptc = Pyridine 2,4,6-Tricarboxylic Acid, C8H5NO6; Bipy = 2,2'-Bipyridine, C10H8N2

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Shoaib Anwar

2012-08-01

Full Text Available The synthesis, structure and properties of the bimetallic layered coordination polymer, [KDy(C8H3NO63(C8H5NO6]n·2n(C10H9N2·5n(H2O = [KDy(Hptc3(H3ptc]n·2n(Hbipy·5n(H2O, are described. The Dy3+ ion is coordinated by three O,N,O-tridentate doubly-deprotonated pyridine tri-carboxylate (Hptc ligands to generate a fairly regular DyO6N3 tri-capped trigonal prism, with the N atoms acting as the caps. The potassium ion is coordinated by an O,N,O-tridentate H3ptc molecule as well as monodentate and bidentate Hptc ligands to result in an irregular KNO9 coordination geometry. The ligands bridge the metal-atom nodes into a bimetallic, layered, coordination polymer, which extends as corrugated layers in the (010 plane, with the mono-protonated bipyridine cations and water molecules occupying the inter-layer regions: Unlike related structures, there are no dysprosium–water bonds. Many O–HLO and N–HLO hydrogen bonds consolidate the structure. Characterization and bioactivity data are described. Crystal data: C52H42DyKN8O29, Mr = 1444.54, triclinic, (No. 2, Z = 2, a = 9.188(2 Å, b = 15.7332(17 Å, c = 19.1664(19 Å, α = 92.797(6°, β = 92.319(7°, γ = 91.273(9°, V = 2764.3(7 Å3, R(F = 0.029, wR(F2 = 0.084.
N,N-Diethylanilinium 2,4-dioxo-5-(2,4,6-trinitrophenyl-1,2,3,4-tetrahydropyrimidin-6-olate

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Manickam Buvaneswari

2011-12-01

Full Text Available In the crystal structure of the title molecular salt, C10H16N+·C10H4N5O9−, the components are linked through a N—H...O hydrogen bonds. R22(8 ring motifs are formed between inversion-related barbiturate residues. Two intramoleculer N—H...O hydrogen bonds are observed in the anion. The dihedral angle between 2,4,6-trinitrophenyl and barbiturate rings is 53.6 (2°. The N,N-diethylamine substituent is disordered and was modeled as two geometrically equivalent conformers with occupancies of 0.737 (2 and 0.273 (2.
Linkage between N2O emission and functional gene abundance in an intensively managed calcareous fluvo-aquic soil

Science.gov (United States)

Yang, Liuqing; Zhang, Xiaojun; Ju, Xiaotang

2017-02-01

The linkage between N2O emissions and the abundance of nitrifier and denitrifier genes is unclear in the intensively managed calcareous fluvo-aquic soils of the North China Plain. We investigated the abundance of bacterial amoA for nitrification and narG, nirS, nirK, and nosZ for denitrification by in situ soil sampling to determine how the abundance of these genes changes instantly during N fertilization events and is related to high N2O emission peaks. We also investigated how long-term incorporated straw and/or manure affect(s) the abundance of these genes based on a seven-year field experiment. The overall results demonstrate that the long-term application of urea-based fertilizer and/or manure significantly enhanced the number of bacterial amoA gene copies leading to high N2O emission peaks after N fertilizer applications. These peaks contributed greatly to the annual N2O emissions in the crop rotation. A significant correlation between annual N2O emissions and narG, nirS, and nirK gene numbers indicates that the abundance of these genes is related to N2O emission under conditions for denitrification, thus partly contributing to the annual N2O emissions. These findings will help to draw up appropriate measures for mitigation of N2O emissions in this ‘hotspot’ region.
N,N'-Diethyl-N,N'-diphenylpyridine-2,6-dicarboxamide

Czech Academy of Sciences Publication Activity Database

Klepetářová, Blanka; Makrlík, E.; Babain, V.A.; Kašička, Václav

2012-01-01

Roč. 68, č. 4 (2012), o1099-o1100 ISSN 1600-5368 Grant - others:GA ČZU(CZ) 42900/1312/3114 Institutional research plan: CEZ:AV0Z40550506 Keywords : N,N'-Diethyl-N,N'-diphenylpyridine-2,6-dicarboxamide * crystal structure * amide nitrogen Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 0.347, year: 2011
An automated setup to measure paleoatmospheric δ13C-CH4, δ15N-N2O and δ18O-N2O in one ice core sample

NARCIS (Netherlands)

Sperlich, P.; Buizert, C.; Jenk, T.M.; Sapart, C.J.; Prokopiou, M.; Röckmann, T.; Blunier, T.

2013-01-01

Air bubbles in ice core samples represent the only opportunity to study the isotopic variability of paleoatmospheric CH4 and N2O. The highest possible precision in isotope measurements is required to maximize the resolving power for CH4 and N2O sink and source reconstructions. We present a new setup
Phosphorus addition mitigates N2O and CH4 emissions in N-saturated subtropical forest, SW China

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L. Yu

2017-06-01

Full Text Available Chronically elevated nitrogen (N deposition has led to severe nutrient imbalance in forest soils. Particularly in tropical and subtropical forest ecosystems, increasing N loading has aggravated phosphorus (P limitation of biomass production, and has resulted in elevated emissions of nitrous oxide (N2O and reduced uptake of methane (CH4, both of which are important greenhouse gases. Yet, the interactions of N and P and their effects on greenhouse gas emissions remain elusive. Here, we report N2O and CH4 emissions together with soil N and P data for a period of 18 months following a single P addition (79 kg P ha−1, as NaH2PO4 powder to an N-saturated, Masson pine-dominated forest soil at TieShanPing (TSP, Chongqing, south-western (SW China. We observed a significant decline in both nitrate (NO3− concentrations in soil water (5 and 20 cm depths and in soil N2O emissions, following P application. We hypothesise that enhanced N uptake by plants in response to P addition, resulted in less available NO3− for denitrification. By contrast to most other forest ecosystems, TSP is a net source of CH4. P addition significantly decreased CH4 emissions and turned the soil from a net source into a net sink. Based on our observation and previous studies in South America and China, we believe that P addition relieves N inhibition of CH4 oxidation. Within the 1.5 years after P addition, no significant increase of forest growth was observed and P stimulation of forest N uptake by understorey vegetation remains to be confirmed. Our study indicates that P fertilisation of N-saturated, subtropical forest soils may mitigate N2O and CH4 emissions, in addition to alleviating nutrient imbalances and reducing losses of N through NO3− leaching.
C=C bond cleavage on neutral VO3(V2O5)n clusters.

Science.gov (United States)

Dong, Feng; Heinbuch, Scott; Xie, Yan; Bernstein, Elliot R; Rocca, Jorge J; Wang, Zhe-Chen; Ding, Xun-Lei; He, Sheng-Gui

2009-01-28

The reactions of neutral vanadium oxide clusters with alkenes (ethylene, propylene, 1-butene, and 1,3-butadiene) are investigated by experiments and density function theory (DFT) calculations. Single photon ionization through extreme ultraviolet radiation (EUV, 46.9 nm, 26.5 eV) is used to detect neutral cluster distributions and reaction products. In the experiments, we observe products (V(2)O(5))(n)VO(2)CH(2), (V(2)O(5))(n)VO(2)C(2)H(4), (V(2)O(5))(n)VO(2)C(3)H(4), and (V(2)O(5))(n)VO(2)C(3)H(6), for neural V(m)O(n) clusters in reactions with C(2)H(4), C(3)H(6), C(4)H(6), and C(4)H(8), respectively. The observation of these products indicates that the C=C bonds of alkenes can be broken on neutral oxygen rich vanadium oxide clusters with the general structure VO(3)(V(2)O(5))(n=0,1,2...). DFT calculations demonstrate that the reaction VO(3) + C(3)H(6) --> VO(2)C(2)H(4) + H(2)CO is thermodynamically favorable and overall barrierless at room temperature. They also provide a mechanistic explanation for the general reaction in which the C=C double bond of alkenes is broken on VO(3)(V(2)O(5))(n=0,1,2...) clusters. A catalytic cycle for alkene oxidation on vanadium oxide is suggested based on our experimental and theoretical investigations. The reactions of V(m)O(n) with C(6)H(6) and C(2)F(4) are also investigated by experiments. The products VO(2)(V(2)O(5))(n)C(6)H(4) are observed for dehydration reactions between V(m)O(n) clusters and C(6)H(6). No product is detected for V(m)O(n) clusters reacting with C(2)F(4). The mechanisms of the reactions between VO(3) and C(2)F(4)/C(6)H(6) are also investigated by calculations at the B3LYP/TZVP level.
Bis[1-methoxy-2,2,2-tris(pyrazol-1-yl-κN2ethane]nickel(II bis(trifluoromethanesulfonate dihydrate

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Ganna Lyubartseva

2013-10-01

Full Text Available In the title salt, [Ni(C12H14N6O2](CF3SO32·2H2O, the NiII cation is located on an inversion centre and is coordinated by six N atoms from two tridentate 1-methoxy-2,2,2-tris(pyrazol-1-ylethane ligands in a distorted octahedral geometry. The Ni—N distances range from 2.0594 (12 to 2.0664 (12 Å, intra-ligand N—Ni—N angles range from 84.59 (5 to 86.06 (5°, and adjacent inter-ligand N—Ni—N angles range between 93.94 (5 and 95.41 (5°. In the crystal, inversion-related pyrazole rings are π–π stacked, with an interplanar spacing of 3.4494 (18 Å, forming chains that propagate parallel to the a-axis direction. Intermolecular O—H...O hydrogen bonds are present between water molecules and trifluoromethanesulfonate anions.
Effect of atmosphere on the fabrication of Si2N2O matrix composites

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Wei Li

2018-03-01

Full Text Available Si2N2O matrix composites were fabricated by solid/gas reaction in air or N2 atmosphere. The effects of atmosphere on the phase and microstructure of the composites were investigated. The reaction mechanism of Si2N2O system was discussed by analysing the variation of the Gibbs free energy with temperature. The effect of N2 and air on sintering of Si2N2O matrix composites was discussed in relation to observed kinetics and thermodynamic calculations. The results showed that gradient structure of Si2N2O matrix composites were obtained in N2 atmosphere. While high N2 concentration was useful for the formation of the pure β-Si3N4 ceramics, low N2 concentration was proposed to form the pure Si2N2O ceramics. However, in the air atmosphere, structure of the Si3N4/SiO2 composites is homogeneous without the gradient structure appearing. Its composition is a little different as the O2 concentration changes.
Photooxidative desulfurization for diesel using Fe / N - TiO2 photocatalyst

Science.gov (United States)

Khan, Muhammad Saqib; Kait, Chong Fai; Mutalib, Mohd Ibrahim Abdul

2014-10-01

A series of N - TiO2 with different mol% N was synthesized via sol-gel method and characterized using thermal gravimetric analyzer and raman spectroscopy. 0.2 wt% Fe was incorporated onto the calcined (200°C) N - TiO2 followed by calcination at 200°C, 250°C and 300°C. Photooxidative desulfurization was conducted in the presence of 0.2wt% Fe / N - TiO2 with different mol% N with and without oxidant (H2O2). Oxidative desulfurization was only achieved when H2O2 was used while without H2O2 no major effect on the sulfur removal. 0.2Fe -30N - H2O2 photocatalysts showed best performance at all calcination temperatures as compared to other mol% N - H2O2 photocatalysts. 16.45% sulfur removal was achieved using photocatalysts calcined at 300 °C.
Estimating North American N2O emissions and the N fertilizer yield fraction using the Carbon Tracker-Lagrange regional inversion framework

Science.gov (United States)

Nevison, C. D.; Andrews, A. E.; Thoning, K. W.; Dlugokencky, E. J.; Sweeney, C.; Saikawa, E.; Miller, S. M.; Benmergui, J. S.; Fischer, M. L.

2017-12-01

North American nitrous oxide (N2O) emissions of 1.5 ± 0.2 Tg N/yr over 2008-2013 are estimated using the Carbon Tracker-Lagrange (CT-L) regional inversion framework. The estimated N2O emissions are largely consistent with the EDGAR global inventory and with the results of global atmospheric inversions, but offer more spatial and temporal detail and improved uncertainty quantification over North America. Emissions are strongest from the Midwestern corn/soybean belt, which accounts for about one fourth of the total North American N2O source. The emissions are maximum in spring/early summer, consistent with a nitrogen fertilizer-driven source, but also show a late winter spike suggestive of freeze-thaw effects. Interannual variability in emissions across the primary months of fertilizer application is positively correlated to mean soil moisture and precipitation. The inversion results, in combination with gridded N fertilizer datasets, are used to estimate the fraction of synthetic N fertilizer that is released as N2O. The estimated N2O flux from the Midwestern corn/soybean belt and the more northerly U.S./Canadian wheat belt corresponds to 3.6-4.5% and 1.4-3.5%, respectively, of total synthetic + organic N fertilizer applied to those regions. Consideration of additional N inputs from soybean N2 fixation reduces the N2O yield from the Midwestern corn/soybean belt to 2-2.6% of total N inputs. Figure 1. Posterior N2O flux integrated over the central Midwestern Corn/Soybean belt (38° to 43°N, 102° to 80°W, in grids where 5% or more of land area was planted in corn and/or soybean). Cases 1 (red) and 2 (blue) are defined based on different covariance matrix parameters, representing alternative scenarios of tighter prior/looser model-data mismatch and looser prior/tighter model-data mismatch. Both cases use a standard prior derived from a coarser resolution global inversion. Triangles show the approximate day when soil temperature climbs above 0°C and drops below 10�
ESTRUCTURA DE LA VEGETACIÓN DEL CANÓN DEL RÍO CHICAMOCHA, 500-1200 M; SANTANDERCOLOMBIA: UNA HERRAMIENTA PARA LA CONSERVACIÓN

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ALBESIANO SOFÍA

2006-12-01

Full Text Available En la vegetación de la cuenca media del cañón del río Chicamocha entre los 500y los 1170 m de altitud, en los municipios de Cepitá y Piedecuesta (Inspección dePolicía de Pescadero, en Santander-Colombia, el tipo fisionómico dominante es elmatorral, aunque se encuentran algunos tipos de vegetación boscosa cerca de loscursos de agua. La distribución en clases de frecuencia de los parámetros altura,cobertura y diámetro a la altura del pecho (DAP, muestra que la mayoría de losindividuos se agrupan en las clases inferiores. La mayor parte de los elementos delestrato herbáceo miden entre 60 cm y 1 m y los del estrato arbustivo entre 1,9 y2,1 m. La mayoría de los individuos del estrato arbustivo cubre entre 0,3 y 1,44m2. Son muy escasos los elementos con DAP superior a 8 cm. Las especies másimportantes en la vegetación regional según el Índice de Valor de Importancia (IVIson: Stenocereus griseus (79, Lippia origanoides (76 y Prosopis juliflora (75. Lariqueza florística del área está representada por 69 familias de plantas vasculares, con173 géneros y 220 especies. Las familias con mayor número de géneros y especiesson: Asteraceae (15 géneros/16 especies, Euphorbiaceae (9/16, Fabaceae (11/12,Poaceae (11/12 y Cactaceae (6/7. Entre el periodo de 1960-1990 se presentaroncambios en la cobertura vegetal debido principalmente al sobrepastoreo extensivoe incontrolado de ganado caprino y en menor proporción, a la extracción de leñay/o a la construcción de obras civiles como vías de comunicación y viviendas. ElÍndice de Deforestación durante los últimos 30 años en la cuenca media de la regiónsemiárida del cañón del río Chicamocha es del 7%.
Fabrication of Au_n_a_n_o_p_a_r_t_i_c_l_e@mSiO_2@Y_2O_3:Eu nanocomposites with enhanced fluorescence

International Nuclear Information System (INIS)

Li, Huiqin; Kang, Jianmiao; Yang, Jianhui; Wu, Biao

2016-01-01

Herein, Au_n_a_n_o_p_a_r_t_i_c_l_e@mSiO_2@Y_2O_3:Eu nanocomposites are synthesized through layer-by-layer assembly technology. Au_n_a_n_o_p_a_r_t_i_c_l_e@mSiO_2 core–shell nanospheres were prepared at first in the presence of CTAB in aqueous solution system by the modified one-pot method. A chemical precipitation method and a succeeding calcination process were adopted to the growth of Y_2O_3:Eu shells on the surfaces of Au_n_a_n_o_p_a_r_t_i_c_l_e@mSiO_2 core–shell nanospheres. The structure, morphology and composition of the nanocomposites were confirmed by XRD, TEM and UV–vis absorption spectrum. The prepared Au_n_a_n_o_p_a_r_t_i_c_l_e@mSiO_2@Y_2O_3:Eu nanocomposites have showed the emission intensity enhances to 6.23 times at 30 nm thickness of the silica spacer between the core of Au nanoparticle and the shell of Y_2O_3:Eu. According to the observations of fluorescent lifetime and the modeling of local electric field, the metal-enhanced and quenched fluorescence is closely related with the enhancement of excitation and radiative decay rate and the quenching by NRET comes as a result of competition between the distance-dependent mechanisms. This kind of multifunctional inorganic material will be widely used in electronics, biology and medical drug loading, etc. - Highlights: • Fabrication of Au_n_a_n_o_p_a_r_t_i_c_l_e@mSiO_2@Y_2O_3:Eu nanocomposites with core-spacer-shell structure. • The controllable fluorescence is achieved by adjusting the spacer thickness of silica. • The fluorescence enhancement is 6.23-fold at an optimal spacer thickness about 30 nm. • The metal-enhanced fluorescence mechanism is proposed.
Improved optical response and photocatalysis for N-doped titanium oxide (TiO2) films prepared by oxidation of TiN

International Nuclear Information System (INIS)

Wan, L.; Li, J.F.; Feng, J.Y.; Sun, W.; Mao, Z.Q.

2007-01-01

In order to improve the photocatalytic activity, N-doped titanium oxide (TiO 2 ) films were obtained by thermal oxidation of TiN films, which were prepared on Ti substrates by ion beam assisted deposition (IBAD). The dominating rutile TiO 2 phase was found in films after thermal oxidation. According to the results of X-ray photoelectron spectroscopy (XPS), the residual N atoms occupied O-atom sites in TiO 2 lattice to form Ti-O-N bonds. UV-vis spectra revealed the N-doped TiO 2 film had a red shift of absorption edge. The maximum red shift was assigned to the sample annealed at 750 deg. C, with an onset wavelength at 600 nm. The onset wavelength corresponded to the photon energy of 2.05 eV, which was nearly 1.0 eV below the band gap of pure rutile TiO 2 . The effect of nitrogen was responsible for the enhancement of photoactivity of N-doped TiO 2 films in the range of visible light
Aquabis(3,5-dimethyl-1H-pyrazole-κN(oxalato-κ2O,O′copper(II

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Andrii I. Buvailo

2008-01-01

Full Text Available In the title compound, [Cu(C2O4(C5H8N22(H2O], the CuII atom is coordinated in a slightly distorted square-pyramidal geometry by two N atoms belonging to the two 3,5-dimethyl-1H-pyrazole ligands, two O atoms of the oxalate anion providing an O,O′-chelating coordination mode, and an O atom of the water molecule occupying the apical position. The crystal packing shows a well defined layer structure. Intra-layer connections are realised through a system of hydrogen bonds while the nature of the inter-layer interactions is completely hydrophobic, including no hydrogen-bonding interactions.

Cultura democrática de género: discriminación, cuotas de género y simulación

OpenAIRE

Martín Rodríguez Peñaloza

2013-01-01

Es indudable que en los últimos años se ha dado, en general, un avance en la representación y/o participación de la mujer en las actividades políticas, esto se observa en la conformación por género en los diversos parlamentos en el mundo; sin embargo, su incorporación ha sido insuficiente para la tan pretendida igualdad y equidad de género; sigue predominando la reproducción de esquemas discriminatorios de participación típicamente masculinizados, lo que no contribuye a una distribución justa...
Potassium ions intercalated into g-C3N4-modified TiO2 nanobelts for the enhancement of photocatalytic hydrogen evolution activity under visible-light irradiation

Science.gov (United States)

Ma, Jian; Zhou, Wei; Tan, Xin; Yu, Tao

2018-05-01

Solar-to-chemical energy conversion is a challenging photochemical reaction for renewable energy storage. In recent decades, photocatalytic H2 evolution has been studied extensively. TiO2 is a well-established semiconductor in the field of photocatalytic H2 production; however, its low efficiency for solar energy utilization, and high photocarrier recombination rate, restrict its photocatalytic efficiency. Here, a series of K-intercalated g-C3N4-modified TiO2 nanobelts (TCN–Kx) with different dosages of K atoms were fabricated using a hydrothermal method followed by a calcination process. XRD, TEM and XPS tests indicate that a tight interfacial connection is formed between K–g-C3N4 and the TiO2 nanobelts. DFT calculations indicated that K dopants prefer to be at the interlayer sites of g-C3N4, suggesting increased charge transfer efficiency. The H2 production efficiency of the TCN–Kx composite materials from water splitting under visible-light irradiation was clearly improved. Steady fluorescence spectroscopy and photocurrent measurements confirmed that the improvement in photocatalytic H2 production activity was due to the superior charge separation and electron transfer efficiency of TCN–Kx composite materials.
UV-induced N2O emission from plants

DEFF Research Database (Denmark)

Bruhn, Dan; Albert, Kristian Rost; Mikkelsen, Teis Nørgaard

2014-01-01

investigate for the fi rst time N 2 O emission from terrestrial vegetation in response to natural solar ultra violet radiation. We conducted fi eld site measurements to investigate N 2 O atmosphere exchange from grass vegetation exposed to solar irradiance with and without UV-screening. Further laboratory...... magnitude as that to UV-B. Therefore, UV-A is more important than UV-B given the natural UV-spectrum at Earth's surface. Plants also emitted N 2 O in darkness, although at reduced rates. The emission rate is temperature dependent with a rather high activation energy indicative for an abiotic process...
BPS states in N = 2 supersymmetric G2 and F4 models

Science.gov (United States)

Ahl Laamara, R.; Mellal, O.; Saidi, E. H.

2017-07-01

In BPS quiver theory of N = 2 supersymmetric pure gauge models with gauge invariance G, primitive BPS quivers Q0G are of two types: Q0ADE and Q0BCFG. In this study, we first show that Q0ADE have outer-automorphism symmetries inherited from the outer-automorphisms of the Dynkin diagrams of ADE Lie algebras. Then, we extend the usual folding operation of Dynkin diagrams ADE → BCFG to obtain the two following things: (i) relate Q0BCFG quivers and their mutations to the Q0ADE ones and their mutations; and (ii) link the BPS chambers of the N = 2ADE theories with the corresponding BCFG ones. As an illustration of this construction, we derive the BPS and anti-BPS states of the strong chambers QstgG2 and QstgF4 of the 4d N = 2 pure G2 and F4 gauge models.
Efeitos da fertirrigação de N e K2O na absorção de macronutrientes pela gravioleira Effects of fertirrigation of N and K2O on absorption of macronutrients by soursop crop

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Roberto S. F. de H. Filho

2006-03-01

Full Text Available O objetivo deste trabalho foi avaliar o efeito de dosagens de N e K2O via água de irrigação na absorção de macronutrientes pela cultura da gravioleira. O experimento foi realizado no campo experimental da Embrapa Meio-Norte, situado no município de Teresina, PI (05º 05' S, 42º 48' W e 74,4 m de altitude. O delineamento experimental utilizado foi por blocos casualizados, com onze tratamentos e quatro repetições, com parcela útil composta de quatro plantas. Os tratamentos consistiram na aplicação de cinco dosagens de N (20, 120, 200, 280 e 380 kg ha-1 ano-1 combinadas com cinco dosagens de K2O (30, 180, 300, 420 e 570 kg ha-1 ano-1 de acordo com o modelo da matriz experimental Plan Plueba III, além de um tratamento com dosagem zero de ambos os nutrientes. Em nenhum dos tratamentos foi encontrado deficiência de N, K, Mg, S e P nas folhas da gravioleira. As dosagens de N, bem como as suas interações com as dosagens de K2O, não proporcionaram efeito significativo sobre os teores dos macronutrientes nas folhas da gravioleira. As dosagens de K2O influenciaram os teores dos macronutrientes Ca, K e Mg nas folhas da gravioleira.The objetive of this work was to evaluate the effect of doses of N and K2O through irrigation water on the absorption of macronutrients by soursop cultivation. The study was conducted at the experimental field of Embrapa - North, in Teresina, in the State of Piauí, Brazil (5º 05' S, 42º and 48' W. The experimental design was completely randomized blocks with eleven treatments and four repetitions. The treatments consisted in the application of five doses of N (20, 120, 200, 280 and 380 kg ha-1 year-1 combined with five doses of K2O (30, 180, 300, 420 and 570 kg ha-1 year-1 in agreement with the model of experimental matrix Plan Plueba III, besides a treatment with dose zero of both nutrients. No deficiency of N, K, Mg, S, and P in the soursop leaves was found in any treatment. The doses of N did not provide
Novel Cholinesterase Inhibitors Based on O-Aromatic N,N-Disubstituted Carbamates and Thiocarbamates

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Martin Krátký

2016-02-01

Full Text Available Based on the presence of carbamoyl moiety, twenty salicylanilide N,N-disubstituted (thiocarbamates were investigated using Ellman’s method for their ability to inhibit acetylcholinesterase (AChE and butyrylcholinesterase (BChE. O-Aromatic (thiocarbamates exhibited weak to moderate inhibition of both cholinesterases with IC50 values within the range of 1.60 to 311.0 µM. IC50 values for BChE were mostly lower than those obtained for AChE; four derivatives showed distinct selectivity for BChE. All of the (thiocarbamates produced a stronger inhibition of AChE than rivastigmine, and five of them inhibited BChE more effectively than both established drugs rivastigmine and galantamine. In general, 5-chloro-2-hydroxy-N-[4-(trifluoromethyl-phenyl]benzamide, 2-hydroxy-N-phenylbenzamide as well as N-methyl-N-phenyl carbamate derivatives led to the more potent inhibition. O-{4-Chloro-2-[(4-chlorophenylcarbamoyl]phenyl} dimethylcarbamothioate was identified as the most effective AChE inhibitor (IC50 = 38.98 µM, while 2-(phenylcarbamoylphenyl diphenylcarbamate produced the lowest IC50 value for BChE (1.60 µM. Results from molecular docking studies suggest that carbamate compounds, especially N,N-diphenyl substituted representatives with considerable portion of aromatic moieties may work as non-covalent inhibitors displaying many interactions at peripheral anionic sites of both enzymes. Mild cytotoxicity for HepG2 cells and consequent satisfactory calculated selectivity indexes qualify several derivatives for further optimization.
Ammonia oxidation pathways and nitrifier denitrification are significant sources of N2O and NO under low oxygen availability.

Science.gov (United States)

Zhu, Xia; Burger, Martin; Doane, Timothy A; Horwath, William R

2013-04-16

The continuous increase of nitrous oxide (N2O) abundance in the atmosphere is a global concern. Multiple pathways of N2O production occur in soil, but their significance and dependence on oxygen (O2) availability and nitrogen (N) fertilizer source are poorly understood. We examined N2O and nitric oxide (NO) production under 21%, 3%, 1%, 0.5%, and 0% (vol/vol) O2 concentrations following urea or ammonium sulfate [(NH4)2SO4] additions in loam, clay loam, and sandy loam soils that also contained ample nitrate. The contribution of the ammonia (NH3) oxidation pathways (nitrifier nitrification, nitrifier denitrification, and nitrification-coupled denitrification) and heterotrophic denitrification (HD) to N2O production was determined in 36-h incubations in microcosms by (15)N-(18)O isotope and NH3 oxidation inhibition (by 0.01% acetylene) methods. Nitrous oxide and NO production via NH3 oxidation pathways increased as O2 concentrations decreased from 21% to 0.5%. At low (0.5% and 3%) O2 concentrations, nitrifier denitrification contributed between 34% and 66%, and HD between 34% and 50% of total N2O production. Heterotrophic denitrification was responsible for all N2O production at 0% O2. Nitrifier denitrification was the main source of N2O production from ammonical fertilizer under low O2 concentrations with urea producing more N2O than (NH4)2SO4 additions. These findings challenge established thought attributing N2O emissions from soils with high water content to HD due to presumably low O2 availability. Our results imply that management practices that increase soil aeration, e.g., reducing compaction and enhancing soil structure, together with careful selection of fertilizer sources and/or nitrification inhibitors, could decrease N2O production in agricultural soils.
Crystal structures of N2,N3,N5,N6-tetrakis(pyridin-2-ylmethylpyrazine-2,3,5,6-tetracarboxamide and N2,N3,N5,N6-tetrakis(pyridin-4-ylmethylpyrazine-2,3,5,6-tetracarboxamide

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Dilovan S. Cati

2017-02-01

Full Text Available The title compounds, C32H28N10O4· unknown solvent, (I, and C32H28N10O4, (II, are pyrazine-2,3,5,6-tetracarboxamide derivatives. In (I, the substituents are (pyridin-2-ylmethylcarboxamide, while in (II, the substituents are (pyridin-4-ylmethylcarboxamide. Both compounds crystallize in the monoclinic space group P21/n, with Z′ = 1 for (I, and Z′ = 0.5 for (II. The whole molecule of (II is generated by inversion symmetry, the pyrazine ring being situated about a center of inversion. In (I, the four pyridine rings are inclined to the pyrazine ring by 83.9 (2, 82.16 (18, 82.73 (19 and 17.65 (19°. This last dihedral angle involves a pyridine ring that is linked to the adjacent carboxamide O atom by an intramolecular C—H...O hydrogen bond. In compound (II, the unique pyridine rings are inclined to the pyrazine ring by 33.3 (3 and 81.71 (10°. There are two symmetrical intramolecular C—H...O hydrogen bonds present in (II. In the crystal of (I, molecules are linked by N—H...O and N—H...N hydrogen bonds, forming layers parallel to (10-1. The layers are linked by C—H...O and C—H...N hydrogen bonds, forming a three-dimensional framework. In the crystal of (II, molecules are linked by N—H...N hydrogen bonds, forming chains propagating along the [010] direction. The chains are linked by a weaker N—H...N hydrogen bond, forming layers parallel to the (101 plane, which are in turn linked by C—H...O hydrogen bonds, forming a three-dimensional structure. In the crystal of compound (I, a region of disordered electron density was treated with the SQUEEZE routine in PLATON [Spek (2015. Acta Cryst. C71, 9–18]. Their contribution was not taken into account during refinement. In compound (II, one of the pyridine rings is positionally disordered, and the refined occupancy ratio for the disordered Car—Car—Npy atoms is 0.58 (3:0.42 (3.
[Effect of short-time drought process on denitrifying bacteria abundance and N2O emission in paddy soil].

Science.gov (United States)

Lu, Jing; Liu, Jin-Bo; Sheng, Rong; Liu, Yi; Chen, An-Lei; Wei, Wen-Xue

2014-10-01

In order to investigate the impact of drying process on greenhouse gas emissions and denitrifying microorganisms in paddy soil, wetting-drying process was simulated in laboratory conditions. N2O flux, redox potential (Eh) were monitored and narG- and nosZ-containing denitrifiers abundances were determined by real-time PCR. N2O emission was significantly increased only 4 h after drying process began, and it was more than 6 times of continuous flooding (CF) at 24 h. In addition, narG and nosZ gene abundances were increased rapidly with the drying process, and N2O emission flux was significantly correlated with narG gene abundance (P driving microorganisms which caused the N2O emission in the short-time drought process in paddy soil.
Bis(O-n-butyl dithiocarbonato-κ2 S,S′)bis(pyridine-κN)manganese(II)

Science.gov (United States)

Alam, Naveed; Ehsan, Muhammad Ali; Zeller, Matthias; Mazhar, Muhammad; Arifin, Zainudin

2011-01-01

The structure of the title manganese complex, [Mn(C5H9OS2)2(C5H5N)2] or [Mn(S2CO-n-Bu)2(C5H5N)2], consists of discrete monomeric entities with Mn2+ ions located on centres of inversion. The metal atom is coordinated by a six-coordinate trans-N2S4 donor set with the pyridyl N atoms located in the apical positions. The observed slight deviations from octahedral geometry are caused by the bite angle of the bidentate κ2-S2CO-n-Bu ligands [69.48 (1)°]. The O(CH2)3(CH3) chains of the O-n-butyl dithiocarbonate units are disordered over two sets of sites with an occupancy ratio of 0.589 (2):0.411 (2). PMID:22090847
1H-1H correlations across N-H···N hydrogen bonds in nucleic acids

International Nuclear Information System (INIS)

Majumdar, Ananya; Gosser, Yuying; Patel, Dinshaw J.

2001-01-01

In 2H J NN -COSY experiments, which correlate protons with donor/acceptor nitrogens across N d ···HN a bonds, the receptor nitrogen needs to be assigned in order to unambiguously identify the hydrogen bond. For many situations this is a non-trivial task which is further complicated by poor dispersion of (N a ,N d ) resonances. To address these problems, we present pulse sequences to obtain direct, internucleotide correlations between protons in uniformly 13 C/ 15 N labeled nucleic acids containing N d ···HN a hydrogen bonds. Specifically, the pulse sequence H2(N1N3)H3 correlates H2(A,ω 1 ):H3(U,ω 2 ) protons across Watson-Crick A-U and mismatched G·A base pairs, the sequences H5(N3N1)H1/H6(N3N1)H1 correlate H5(C,ω 1 )/H6(C,ω 1 ):H1(G,ω 2 ) protons across Watson-Crick G-C base pairs, and the H 2 (N2N7)H8 sequence correlates NH 2 (G,A,C;ω 1 ):H8(G,A;ω 2 ) protons across G·G, A·A, sheared G·A and other mismatch pairs. These 1 H- 1 H connectivities circumvent the need for independent assignment of the donor/acceptor nitrogen and related degeneracy issues associated with poorly dispersed nitrogen resonances. The methodology is demonstrated on uniformly 13 C/ 15 N labeled samples of (a) an RNA regulatory element involving the HIV-1 TAR RNA fragment, (b) a multi-stranded DNA architecture involving a G·(C-A) triad-containing G-quadruplex and (c) a peptide-RNA complex involving an evolved peptide bound to the HIV-1 Rev response element (RRE) RNA fragment
Effect of photocatalytic reduction of carbon dioxide by N-Zr co-doped nano TiO2.

Science.gov (United States)

Zhang, Ru; Wang, Li; Kang, Zhuo; Li, Qiang; Pan, Huixian

2017-11-01

Modified sol-gel method was adopted to prepare TiO 2 , Zr-TiO 2 and N/Zr-TiO 2 composite catalyst. The as-synthesized photocatalysts were characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, Brunner- Emmet- Teller measurement and UV-Vis diffuse reflectance spectroscopy. And the photocatalytic performance toward CO 2 reduction was evaluated under ultraviolet light. The catalyst particles were demonstrated in the nanometer level size. When N and Zr are co-doped, on the one hand, Ti 4+ can be replaced by Zr 4 +, which leads to lattice distortion and inhibits electron-hole recombination. On the other hand, N enters into TiO 2 lattice gap to form O-Ti-N bond structure, and partial Ti 4+ are reduced to Ti 3+ . Compared with pristine TiO 2 , the specific surface area and the band gap of N/Zr-TiO 2 were improved and reduced, respectively. The N and Zr synergistically contribute to the obviously strengthened absorption intensity in visible region, as well as significantly improved photocatalytic activity. In the gas phase reactor, when the calcination temperature was 550°C, 0.125N/0.25Zr-TiO 2 composite performed the highest photocatalytic activity UV irradiation for 8 h, and the corresponding CH 4 yield was 11.837 µmol/g, which was 87.8% higher than that of pristine TiO 2 . For the visible light, the CH 4 yield was 9.003 µmol/g after 8 h irradiation, which was 83.9% higher than that of pristine TiO 2 .
Oceanic nitrogen cycling and N2O flux perturbations in the Anthropocene

Science.gov (United States)

Landolfi, A.; Somes, C. J.; Koeve, W.; Zamora, L. M.; Oschlies, A.

2017-08-01

There is currently no consensus on how humans are affecting the marine nitrogen (N) cycle, which limits marine biological production and CO2 uptake. Anthropogenic changes in ocean warming, deoxygenation, and atmospheric N deposition can all individually affect the marine N cycle and the oceanic production of the greenhouse gas nitrous oxide (N2O). However, the combined effect of these perturbations on marine N cycling, ocean productivity, and marine N2O production is poorly understood. Here we use an Earth system model of intermediate complexity to investigate the combined effects of estimated 21st century CO2 atmospheric forcing and atmospheric N deposition. Our simulations suggest that anthropogenic perturbations cause only a small imbalance to the N cycle relative to preindustrial conditions (˜+5 Tg N y-1 in 2100). More N loss from water column denitrification in expanded oxygen minimum zones (OMZs) is counteracted by less benthic denitrification, due to the stratification-induced reduction in organic matter export. The larger atmospheric N load is offset by reduced N inputs by marine N2 fixation. Our model predicts a decline in oceanic N2O emissions by 2100. This is induced by the decrease in organic matter export and associated N2O production and by the anthropogenically driven changes in ocean circulation and atmospheric N2O concentrations. After comprehensively accounting for a series of complex physical-biogeochemical interactions, this study suggests that N flux imbalances are limited by biogeochemical feedbacks that help stabilize the marine N inventory against anthropogenic changes. These findings support the hypothesis that strong negative feedbacks regulate the marine N inventory on centennial time scales.
Identification of swine H1N2/pandemic H1N1 reassortant influenza virus in pigs, United States.

Science.gov (United States)

Ali, Ahmed; Khatri, Mahesh; Wang, Leyi; Saif, Yehia M; Lee, Chang-Won

2012-07-06

In October and November 2010, novel H1N2 reassortant influenza viruses were identified from pigs showing mild respiratory signs that included cough and depression. Sequence and phylogenetic analysis showed that the novel H1N2 reassortants possesses HA and NA genes derived from recent H1N2 swine isolates similar to those isolated from Midwest. Compared to the majority of reported reassortants, both viruses preserved human-like host restrictive and putative antigenic sites in their HA and NA genes. The four internal genes, PB2, PB1, PA, and NS were similar to the contemporary swine triple reassortant viruses' internal genes (TRIG). Interestingly, NP and M genes of the novel reassortants were derived from the 2009 pandemic H1N1. The NP and M proteins of the two isolates demonstrated one (E16G) and four (G34A, D53E, I109T, and V313I) amino acid changes in the M2 and NP proteins, respectively. Similar amino acid changes were also noticed upon incorporation of the 2009 pandemic H1N1 NP in other reassortant viruses reported in the U.S. Thus the role of those amino acids in relation to host adaptation need to be further investigated. The reassortments of pandemic H1N1 with swine influenza viruses and the potential of interspecies transmission of these reassortants from swine to other species including human indicate the importance of systematic surveillance of swine population to determine the origin, the prevalence of similar reassortants in the U.S. and their impact on both swine production and public health. Copyright © 2012 Elsevier B.V. All rights reserved.
Inhibition effect of zinc in wastewater on the N2O emission from coastal loam soils.

Science.gov (United States)

Huang, Yan; Ou, Danyun; Chen, Shunyang; Chen, Bin; Liu, Wenhua; Bai, Renao; Chen, Guangcheng

2017-03-15

The effects of zinc (Zn) on nitrous oxide (N 2 O) fluxes from coastal loam soil and the abundances of soil nitrifier and denitrifier were studied in a tidal microcosm receiving livestock wastewater with different Zn levels. Soil N 2 O emission significantly increased due to discharge of wastewater rich in ammonia (NH 4 + -N) while the continuous measurements of gas flux showed a durative reduction in N 2 O flux by high Zn input (40mgL -1 ) during the low tide period. Soil inorganic nitrogen concentrations increased at the end of the experiment and even more soil NH 4 + -N was measured in the high-Zn-level treatment, indicating an inhibition of ammonia oxidation by Zn input. Quantitative PCR of soil amoA, narG and nirK genes encoding ammonia monooxygenase, nitrate reductase and nitrite reductase, respectively, showed that the microbial abundances involved in these metabolisms were neither affected by wastewater discharge nor Zn contamination. Copyright © 2017 Elsevier Ltd. All rights reserved.
Bis[μ-2,5-bis(pyridin-2-yl-1,3,4-thiadiazole-κ4N2,N3:N4,N5]bis[(nitrato-κOsilver(I] tetrahydrate

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Abdelhakim Laachir

2013-06-01

Full Text Available The self-assembly of an angular 2,5-bis(pyridin-2-yl-1,3,4-thiadiazole ligand (L with silver nitrate (AgNO3 produced a new dinuclear silver(I coordination complex, [Ag2(C12H8N4S2(NO32]·4H2O, which crystallizes with two Ag atoms bridged by two L ligands. The Ag atom is surrounded by four N atoms of L and by one O from the nitrate anion defining a distorted square pyramid. The atoms comprising the dication are nearly coplanar, with an r.m.s. deviation of 0.1997 Å. Molecules are linked by C—H...O and O—H...O hydrogen bonds through nitrate anions and water molecules, forming a two-dimensional porous network. The overall structure involves stacking of Ag complex layers along the b axis. The cohesion in the three-dimensional architecture is ensured by O...Ag interactions.
Global behavior of the difference equation $x_{n+1}=\\frac{Ax_{n-1}} {B-Cx_{n}x_{n-2}}$

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R. Abo-Zeid

2013-11-01

Full Text Available The aim of this work is to investigate the global stability, periodic nature, oscillation and the boundedness of all admissible solutions of the difference equation $x_{n+1}=\\frac{Ax_{n-1}} {B-Cx_{n}x_{n-2}}$, n=0,1,2,... where A, B, C are positive real numbers.
Computation of the chiral condensate using N{sub f}=2 and N{sub f}=2+1+1 dynamical flavors of twisted mass fermions

Energy Technology Data Exchange (ETDEWEB)

Cichy, K. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Poznan Univ. (Poland). Faculty of Physics; Garcia-Ramos, E. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Humboldt-Universitaet, Berlin (Germany); Jansen, K. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Shindler, A. [Forschungszentrum Juelich (Germany). IAS; Forschungszentrum Juelich (Germany). IKP; Forschungszentrum Juelich (Germany). JCHP; Collaboration: European Twisted Mass Collaboration

2013-12-15

We apply the spectral projector method, recently introduced by Giusti and Luescher, to compute the chiral condensate using N{sub f}=2 and N{sub f}=2+1+1 dynamical flavors of maximally twisted mass fermions. We present our results for several quark masses at three different lattice spacings which allows us to perform the chiral and continuum extrapolations. In addition we report our analysis on the O(a) improvement of the chiral condensate for twisted mass fermions. We also study the effect of the dynamical strange and charm quarks by comparing our results for N{sub f}=2 and N{sub f}=2+1+1 dynamical flavors.
Bis(acetylacetonato-κ2O,O′(2-amino-1-methyl-1H-benzimidazole-κN3oxidovanadium(IV

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Zukhra Ch. Kadirova

2009-07-01

Full Text Available The title mixed-ligand oxidovanadium(IV compound, [VO(C5H7O22(C8H9N3], contains a VIV atom in a distorted octahedral coordination, which is typical for such complexes. The vanadyl group and the N-heterocyclic ligand are cis to each other. The coordination bond is located at the endocyclic N atom of the benzimidazole ligand. Intramolecular hydrogen bonds between the exo-NH2 group H atoms and acetylacetonate O atoms stabilize the crystal structure.
Synthesis and crystal structures of new complexes of Np(V) glycolate with 2,2'-bipyridine, [NpO2(C10H8N2)(OOC2H2OH)].1.5H2O and [NpO2(C10H8N2)(OOC2H2OH)].2.5H2O

International Nuclear Information System (INIS)

Charushnikova, I.A.; Krot, N.N.; Starikova, Z.A.

2009-01-01

Single crystals were prepared, and the structures of two complexes of Np(V) glycolate with 2,2'-bipyridine of the compositions [NpO 2 (C 10 H 8 N 2 )(OOC 2 H 2 OH)].1.5H 2 O (I) and [NpO 2 (C 10 H 8 N 2 )(OOC 2 H 2 OH)]2.5H 2 O (II) were studied. The structures of the compounds are based on neptunyl-glycolate chains in which the glycolate anion manifests its complexation ability in different manner. In structure I, the bidentate-bridging anion links the adjacent NpO 2 - cations through the oxygen atoms of the carboxylate group. The neptunyl-glycolate chains of I exhibits the mutual coordination of the NpO 2 - cations acting toward each other simultaneously as ligands and coordinating centers. In compound II, the glycolate anion is bidentately coordinated to one neptunium atom to form a planar five-membered metallocycle [NpOCCO]. The O atom external with respect to the metallocycle is in the coordination environment of the adjacent neptunyl. The nitrogen-containing molecular ligand Bipy is included into the coordination environment of Np. The coordination polyhedron of the Np atoms in both structures is a pentagonal bipyramid in which the average Np-N bond length is 2.666 Aa (I) and 2.596 Aa (II). (orig.)

Theoretical studies for the N2–N2O van der Waals complex: The potential energy surface, intermolecular vibrations, and rotational transition frequencies

International Nuclear Information System (INIS)

Zheng, Rui; Zheng, Limin; Yang, Minghui; Lu, Yunpeng

2015-01-01

Theoretical studies of the potential energy surface (PES) and bound states are performed for the N 2 –N 2 O van der Waals (vdW) complex. A four-dimensional intermolecular PES is constructed at the level of single and double excitation coupled-cluster method with a non-iterative perturbation treatment of triple excitations [CCSD(T)] with aug-cc-pVTZ basis set supplemented with bond functions. Two equivalent T-shaped global minima are located, in which the O atom of N 2 O monomer is near the N 2 monomer. The intermolecular fundamental vibrational states are assigned by inspecting the orientation of the nodal surface of the wavefunctions. The calculated frequency for intermolecular disrotation mode is 23.086 cm −1 , which is in good agreement with the available experimental data of 22.334 cm −1 . A negligible tunneling splitting with the value of 4.2 MHz is determined for the ground vibrational state and the tunneling splitting increases as the increment of the vibrational frequencies. Rotational levels and transition frequencies are calculated for both isotopomers 14 N 2 –N 2 O and 15 N 2 –N 2 O. The accuracy of the PES is validated by the good agreement between theoretical and experimental results for the transition frequencies and spectroscopic parameters
N2O-reducing activity of soil amended with organic and inorganic enrichments under flooded conditions

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Alicja Księżopolska

Full Text Available ABSTRACT Changes, apparent after investigation, in the physical and chemical properties in soil, as a result of organic and inorganic enrichments under flooded conditions, influence the growth of denitrifiers. The aim of this study was to determine the effect of the addition of manure (8 kg m−2 (M, clay (50 kg m−2 (CL and lime (1.12 kg m−2 (Ca on the N2O-reducing activity (N2O-RA of sandy loam soil (clay content - 24 % in 0-20 cm, during NO3 reduction under flooding. The soil samples were taken from field plots after 3 years of enrichment with grass cultivation. The enrichments had a distinct effect on the N2O-RA and N2O-released, due to the change in pH, the porosity, and the sorptive properties of the soil. The pH had the greatest impact on the N2O-RA of the soil and ranged from 4.9 to 7.6. For actual denitrification to N2O-realized (aD-N2O, the maximum N2O-releasing (mcN2O-releasing followed the order: 1.36 for the M-treatment, 6.39 for the M+CL+Ca-treatment, 7.79 for the c-soil and 8.69 N2O-N mg kg−1 for the M+CL-treatment. For actual denitrification (aD, the mcN2O-releasing was followed the order: 10.37 for the M-treatment, 10.49 for the control soil, 14.60 for the M+CL+Ca-treatment and 20.00 N2O-N mg kg−1 for the M+CL-treatment. The N2O-RA of the soil samples increased as pH increased. The average N2O/N2+N2O ratio and the N2O-RA of the soil samples increased in the following order: M+CL, control soil, M+CL+Ca, M-enrichments. The addition of enrichments did not pose a threat to the environment due to increased N2O emissions, but as regards conserving NO3− in the soil, the addition of clay distinctly increased the complete denitrification process.
Progress in the analysis and interpretation of N2O isotopes: Potential and future challenges

Science.gov (United States)

Mohn, Joachim; Tuzson, Béla; Zellweger, Christoph; Harris, Eliza; Ibraim, Erkan; Yu, Longfei; Emmenegger, Lukas

2017-04-01

In recent years, research on nitrous oxide (N2O) stable isotopes has significantly advanced, addressing an increasing number of research questions in biogeochemical and atmospheric sciences [1]. An important milestone was the development of quantum cascade laser based spectroscopic devices [2], which are inherently specific for structural isomers (15N14N16O vs. 14N15N16O) and capable to collect real-time data with high temporal resolution, complementary to the well-established isotope-ratio mass-spectrometry (IRMS) method. In combination with automated preconcentration, optical isotope ratio spectroscopy (OIRS) has been applied to disentangle source processes in suburban, rural and pristine environments [e.g. 3, 4]. Within the European Metrology Research Programme (EMRP) ENV52 project "Metrology for high-impact greenhouse gases (HIGHGAS)", the quality of N2O stable isotope analysis by OIRS, the comparability between laboratories, and the traceability to the international isotope ratio scales have been addressed. An inter-laboratory comparison between eleven IRMS and OIRS laboratories, organised within HIGHGAS, indicated limited comparability for 15N site preference, i.e. the difference between 15N abundance in central (N*NO) and end (*NNO) position [5]. In addition, the accuracy of the NH4NO3 decomposition reaction, which provides the link between 15N site preference and the international 15N/14N scale, was found to be limited by non-quantitative NH4NO3 decomposition in combination with substantially different isotope enrichment factors for both nitrogen atoms [6]. Results of the HIGHGAS project indicate that the following research tasks have to be completed to foster research on N2O isotopes: 1) develop improved techniques to link the 15N and 18O abundance and the 15N site preference in N2O to the international stable isotope ratio scales; 2) provide N2O reference materials, pure and diluted in an air matrix, to improve inter-laboratory compatibility. These tasks
The structure of N = 2 supergravity in N = 1 superfields

International Nuclear Information System (INIS)

Awada, M.A.; Mokhtari, S.

1985-01-01

A formulation of N = 2 supergravity in N = 1 superspace is presented. The authors solve up to all orders the N = 2 supergravity constraints in terms of unconstrained N = 1 superfields. The structure of the N = 2 action in N = 1 superspace is examined. The proposed action coincides in the quadratic limit of the spin (3/2,1) matter fields with the action given by previous workers. (author)
When the Sun's Away, N2O5 Comes Out to Play: An Updated Analysis of Ambient N2O5 Heterogeneous Chemistry

Science.gov (United States)

McDuffie, E. E.; Brown, S. S.

2017-12-01

The heterogeneous chemistry of N2O5 impacts the budget of tropospheric oxidants, which directly controls air quality at Earth's surface. The reaction between gas-phase N2O5 and aerosol particles occurs largely at night, and is therefore more important during the less-intensively-studied winter season. Though N2O5-aerosol interactions are vital for the accurate understanding and simulation of tropospheric chemistry and air quality, many uncertainties persist in our understanding of how various environmental factors influence the reaction rate and probability. Quantitative and accurate evaluation of these factors directly improves the predictive capabilities of atmospheric models, used to inform mitigation strategies for wintertime air pollution. In an update to last year's presentation, The Wintertime Fate of N2O5: Observations and Box Model Analysis for the 2015 WINTER Aircraft Campaign, this presentation will focus on recent field results regarding new information about N2O5 heterogeneous chemistry and future research directions.
Ab initio studies on the reaction of O2 with Ban (n=2,5) clusters

International Nuclear Information System (INIS)

Li, S.F.; Xue Xinlian; Chen, G.; Yuan, D.W.; Jia Yu; Gong, X.G.

2006-01-01

Ab initio theoretical calculations have been performed to study the reaction of O 2 with Ba n (n=2,5) clusters. Our results show that O 2 can easily chemisorb and dissociate on small Ba n clusters and there is no obvious energy barrier in the process of the dissociation. The local magnetic moment contributed by oxygen must vanish during the intermediate states before the O 2 dissociation. Correspondingly, local magnetic moment only decreases from 2μ B to about 1μ B if O 2 molecularly adsorbs onto Ba 5 cluster. The electronic structure analysis indicates that the charge transfer from Ba n cluster to O 2 as well as the orbital hybridization between the cluster and the oxygen molecule may play a key role in O 2 dissociation
Ethyl 4,6-O-benzylidene-2-deoxy-N-phthalimido-1-thio-β-d-glucopyranoside

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Göran Widmalm

2010-12-01

Full Text Available In the title compound, C23H23NO6S, the plane of the N-phthalimido group makes a dihedral angle of 67.4 (1° with the least square plane of the sugar ring defined by the C2, C3, C5 and O5 atoms using standard glucose nomenclature. The thioethyl group has the exo-anomeric conformation. In the crystal, intermolecular hydrogen bonds involving the hydroxy groups and the carbonyl O atoms of adjacent N-phthalimido groups form chains parallel to the b axis. The chains are further stabilized by C—H...π interactions.
Orman yangınları açısından riskli yılların güneş leke döngüsüne bağlı olarak önceden tahmin edilebilmesi

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Yüksek Lisans Uğur Baltacı

2017-11-01

Full Text Available Ülkemizde ve dünya genelinde, bazı yıllar daha çok sayıda ve büyük ölçekte orman yangınları görülmekte iken, bazı yıllarda orman yangını sayısı ve büyüklüğü azalmaktadır. Orman yangını istatistikleri yangın adedi ve yanan alan olarak zamana bağlı grafik haline dönüştürüldüğünde, minimum ve maksimum noktaları farklı sinüzoidal eğriler şeklinde periyodik bir dalgalanma görülmektedir. Bu durum, orman yangınlarının bir dış etkene bağlı olarak artıp azaldığını gösterebilir. Bu çalışmamızda; adet ve alan olarak orman yangınları ile Güneş Leke Döngüsü (Güneş Radyasyon Döngüsü karşılaştırılmış ve aralarında güçlü bir ilişkinin olduğu bulunmuştur. Çalışma sonucunda elde edilen bulgular, orman yangını açısından riski yüksek yılların tahmininde kullanılabilecektir. Orman yangınları ile mücadelede orta ve uzun vadeli programlar yapılırken bu tespitlerin göz önünde bulundurulmasının büyük önem arz ettiği düşünülmektedir. Özellikle bütçe planlamaları ve önceden alınacak tedbirler açısından bu öngörülerin dikkate alınması uygun olacaktır.
Effects of cattle slurry and nitrification inhibitor application on spatial soil O2 dynamics and N2O production pathways

DEFF Research Database (Denmark)

Quan, Nguyen Van; Wu, Di; Kong, Xianwang

2017-01-01

decomposition. Here, we applied O2 planar optode and N2O isotopomer techniques to investigate the linkage between soil O2 dynamics and N2O production pathways in soils treated with cattle slurry (treatment CS) and tested the effect of the nitrification inhibitor 3,4-dimethyl pyrazole phosphate, DMPP (treatment......Application of cattle slurry to grassland soil has environmental impacts such as ammonia volatilization and greenhouse gas emissions. The extent, however, depends on application method and soil conditions through their effects on infiltration and oxygen (O2) availability during subsequent...... CSD). Twodimensional planar optode images of soil O2 over time revealed that O2 depletion ultimately extended to 1.5 cm depth in CS, as opposed to 1.0 cm in CSD. The 15N site preference (SP) and d18O of emitted N2O varied between 11-25‰and 35e47‰, respectively, indicating a mixture of production...
catena-Poly[[bis[2-(2,3-dimethylanilinobenzoato-κO]cadmium(II]-di-μ-3-pyridylmethanol-κ2N:O;κ2O:N

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Tadeusz Lis

2008-03-01

Full Text Available In the crystal structure of the title compound, [Cd(C15H14NO22(C6H7NO2]n, the Cd atom displays a distorted octahedral geometry, including two pyridine N atoms and two hydroxyl O from four symmetry-related 3-pyridylmethanol (3-pyme ligands and two carboxylate O atoms from mefenamate [2-(2,3-dimethylanilinobenzoate] anions. The Cd atoms are connected via the bridging 3-pyme ligands into chains, that extend in the a-axis direction. The Cd atom is located on a center of inversion, whereas the 3-pyme ligands and the mefenamate anions occupy general positions.
[Effects of organic and inorganic fertilizers on emission and sources of N2O in vegetable soils.

Science.gov (United States)

Lin, Wei; Ding, Jun Jun; Li, Yu Zhong; Xu, Chun Ying; Li, Qiao Zhen; Zheng, Qian; Zhuang, Shan

2018-05-01

To clarify the microbial pathway of the N 2 O production and consumption under different fertilizers and provide theoretical basis for the reduction of N 2 O emission and rational management of fertilization in vegetable soils, we examined dynamics of N 2 O flux and isotope signatures under different fertilizer treatments in the vegetable soils of Beijing, by setting up four treatments (organic-acetylene, organic-nonacetylene, inorganic-acetylene, inorganic-nonacetylene) and using the stable isotope technique of natural N 2 O abundance. The results showed that the cumulative N 2 O emission from organic-acetylene group, organic-nonacetylene group, inorganic-acetylene group and inorganic-nonacetylene group was (374±37), (283±34), (458±36), (355±41) g·m -2 in cabbage growing season, respectively. N 2 O fluxes were significantly lower in treatments with organic fertilizer than those with inorganic fertilizer and significantly higher in acetylene group than nonacetylene group. The degree of N 2 O reduction were similar in both fertilizer treatments, and higher nitrification was found in inorganic fertilizer than organic fertilizer treatments. Acetylene only inhibited partial nitrification and partial N 2 O reduction at the peak of N 2 O emission. When the emission was reduced, N 2 O reduction could be completely suppressed. Therefore, the inorganic fertilizer might trigger nitrification and promote higher N 2 O emission. The high concentration of N 2 O could withstand that acetylene to inhibite N 2 O reduction. Hence, using organic fertilizers instead of some inorganic ones could effectively reduce N 2 O emission in vegetable soils of Beijing. The N 2 O concentration threshold should be considered when we identify N 2 O source by acetylene inhibition method.
Synthesis, structure, luminescent, and magnetic properties of carbonato-bridged Zn(II)2Ln(III)2 complexes [(μ4-CO3)2{Zn(II)L(n)Ln(III)(NO3)}2] (Ln(III) = Gd(III), Tb(III), Dy(III); L(1) = N,N'-bis(3-methoxy-2-oxybenzylidene)-1,3-propanediaminato, L(2) = N,N'-bis(3-ethoxy-2-oxybenzylidene)-1,3-propanediaminato).

Science.gov (United States)

Ehama, Kiyomi; Ohmichi, Yusuke; Sakamoto, Soichiro; Fujinami, Takeshi; Matsumoto, Naohide; Mochida, Naotaka; Ishida, Takayuki; Sunatsuki, Yukinari; Tsuchimoto, Masanobu; Re, Nazzareno

2013-11-04

Carbonato-bridged Zn(II)2Ln(III)2 complexes [(μ4-CO3)2{Zn(II)L(n)Ln(III)(NO3)}2]·solvent were synthesized through atmospheric CO2 fixation reaction of [Zn(II)L(n)(H2O)2]·xH2O, Ln(III)(NO3)3·6H2O, and triethylamine, where Ln(III) = Gd(III), Tb(III), Dy(III); L(1) = N,N'-bis(3-methoxy-2-oxybenzylidene)-1,3-propanediaminato, L(2) = N,N'-bis(3-ethoxy-2-oxybenzylidene)-1,3-propanediaminato. Each Zn(II)2Ln(III)2 structure possessing an inversion center can be described as two di-μ-phenoxo-bridged {Zn(II)L(n)Ln(III)(NO3)} binuclear units bridged by two carbonato CO3(2-) ions. The Zn(II) ion has square pyramidal coordination geometry with N2O2 donor atoms of L(n) and one oxygen atom of a bridging carbonato ion at the axial site. Ln(III) ion is coordinated by nine oxygen atoms consisting of four from the deprotonated Schiff-base L(n), two from a chelating nitrate, and three from two carbonate groups. The temperature-dependent magnetic susceptibilities in the range 1.9-300 K, field-dependent magnetization from 0 to 5 T at 1.9 K, and alternating current magnetic susceptibilities under the direct current bias fields of 0 and 1000 Oe were measured. The magnetic properties of the Zn(II)2Ln(III)2 complexes are analyzed on the basis of the dicarbonato-bridged binuclear Ln(III)-Ln(III) structure, as the Zn(II) ion with d(10) electronic configuration is diamagnetic. ZnGd1 (L(1)) and ZnGd2 (L(2)) show a ferromagnetic Gd(III)-Gd(III) interaction with J(Gd-Gd) = +0.042 and +0.028 cm(-1), respectively, on the basis of the Hamiltonian H = -2J(Gd-Gd)ŜGd1·ŜGd2. The magnetic data of the Zn(II)2Ln(III)2 complexes (Ln(III) = Tb(III), Dy(III)) were analyzed by a spin Hamiltonian including the crystal field effect on the Ln(III) ions and the Ln(III)-Ln(III) magnetic interaction. The Stark splitting of the ground state was so evaluated, and the energy pattern indicates a strong easy axis (Ising type) anisotropy. Luminescence spectra of Zn(II)2Tb(III)2 complexes were observed, while those
Facile synthesis of Z-scheme graphitic-C{sub 3}N{sub 4}/Bi{sub 2}MoO{sub 6} nanocomposite for enhanced visible photocatalytic properties

Energy Technology Data Exchange (ETDEWEB)

Lv, Jiali [College of Physics and Electronic Information, Huaibei Normal University, Huaibei 235000 (China); Dai, Kai, E-mail: daikai940@chnu.edu.cn [College of Physics and Electronic Information, Huaibei Normal University, Huaibei 235000 (China); Zhang, Jinfeng; Geng, Lei [College of Physics and Electronic Information, Huaibei Normal University, Huaibei 235000 (China); Liang, Changhao, E-mail: chliang@issp.ac.cn [College of Physics and Electronic Information, Huaibei Normal University, Huaibei 235000 (China); Key Laboratory of Materials Physics and Anhui Key Laboratory of Nanomaterials and Nanotechnology, Institute of Solid State Physics, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031 (China); Liu, Qiangchun; Zhu, Guangping; Chen, Chen [College of Physics and Electronic Information, Huaibei Normal University, Huaibei 235000 (China)

2015-12-15

Graphical abstract: - Highlights: • g-C{sub 3}N{sub 4}/Bi{sub 2}MoO{sub 6} nanocomposite photocatalyst was prepared. • g-C{sub 3}N{sub 4}/Bi{sub 2}MoO{sub 6} as a typical Z-scheme photocatalyst was proved. • g-C{sub 3}N{sub 4}/Bi{sub 2}MoO{sub 6} showed long reusable life with irradiation of LED light. - Abstract: The band engineering of visible-light-driven photocatalysts is a promising route for harnessing of effective solar energy to perform high chemical reactions and to treat environmental pollution. In this study, two narrow band gap semiconductor nanomaterials, graphitic carbon nitride (g-C{sub 3}N{sub 4}) and Bi{sub 2}MoO{sub 6}, were selected and coupled to form series of g-C{sub 3}N{sub 4}/Bi{sub 2}MoO{sub 6} photocatalysts. Their structure, light absorption wavelength range, charge transport properties and energy level were investigated. Through perfect manipulation of their composition, enhanced photocatalytic activity of the Z-scheme g-C{sub 3}N{sub 4}/Bi{sub 2}MoO{sub 6} photocatalysts with efficient reduction of recombination of photogenerated electrons and holes was achieved. The optimized Z-scheme g-C{sub 3}N{sub 4}/Bi{sub 2}MoO{sub 6} photocatalysts with 25 wt%g-C{sub 3}N{sub 4} showed apparent pseudo-first-order rate constant k{sub app} as high as 0.0688 min{sup −1}, which was 4.8 times and 8.2 times higher than that of g-C{sub 3}N{sub 4} and Bi{sub 2}MoO{sub 6} photocatalyst, respectively.
NO-oxygen scavenger or reaction intermediate in the decomposition of N2O?

Czech Academy of Sciences Publication Activity Database

Nováková, Jana; Sobalík, Zdeněk

2006-01-01

Roč. 111, 3-4 (2006), s. 195-202 ISSN 1011-372X R&D Projects: GA AV ČR 1ET400400413 Institutional research plan: CEZ:AV0Z40400503 Keywords : 15N2 18O and 15N2 18 O + 14N 16O decomposition * role of NOx intermediates * Fe-zeolites Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.772, year: 2006
Climate, duration, and N placement determine N2 O emissions in reduced tillage systems: a meta-analysis.

Science.gov (United States)

van Kessel, Chris; Venterea, Rodney; Six, Johan; Adviento-Borbe, Maria Arlene; Linquist, Bruce; van Groenigen, Kees Jan

2013-01-01

No-tillage and reduced tillage (NT/RT) management practices are being promoted in agroecosystems to reduce erosion, sequester additional soil C and reduce production costs. The impact of NT/RT on N2 O emissions, however, has been variable with both increases and decreases in emissions reported. Herein, we quantitatively synthesize studies on the short- and long-term impact of NT/RT on N2 O emissions in humid and dry climatic zones with emissions expressed on both an area- and crop yield-scaled basis. A meta-analysis was conducted on 239 direct comparisons between conventional tillage (CT) and NT/RT. In contrast to earlier studies, averaged across all comparisons, NT/RT did not alter N2 O emissions compared with CT. However, NT/RT significantly reduced N2 O emissions in experiments >10 years, especially in dry climates. No significant correlation was found between soil texture and the effect of NT/RT on N2 O emissions. When fertilizer-N was placed at ≥5 cm depth, NT/RT significantly reduced area-scaled N2 O emissions, in particular under humid climatic conditions. Compared to CT under dry climatic conditions, yield-scaled N2 O increased significantly (57%) when NT/RT was implemented <10 years, but decreased significantly (27%) after ≥10 years of NT/RT. There was a significant decrease in yield-scaled N2 O emissions in humid climates when fertilizer-N was placed at ≥5 cm depth. Therefore, in humid climates, deep placement of fertilizer-N is recommended when implementing NT/RT. In addition, NT/RT practices need to be sustained for a prolonged time, particularly in dry climates, to become an effective mitigation strategy for reducing N2 O emissions. © 2012 Blackwell Publishing Ltd.
Tris(2,2′-bipyridine-κ2 N,N′)cobalt(III) bis[bis(pyridine-2,6-dicarboxylato-κ3 O 2,N,O 6)cobaltate(III)] perchlorate dimethylformamide hemisolvate 1.3-hydrate

Science.gov (United States)

Golenya, Irina A.; Boyko, Alexander N.; Kotova, Natalia V.; Haukka, Matti; Iskenderov, Turganbay S.

2012-01-01

In the title compound, [Co(C10H8N2)3][Co(C7H3NO4)2]2(ClO4)·0.5C3H7NO·1.3H2O, the CoIII atom in the complex cation is pseudooctahedrally coordinated by six N atoms of three chelating bipyridine ligands. The CoIII atom in the complex anion is coordinated by two pyridine N atoms and four carboxylate O atoms of two doubly deprotonated pyridine-2,6-dicarboxylate ligands in a distorted octahedral geometry. One dimethylformamide solvent molecule and two water molecules are half-occupied and one water molecule is 0.3-occupied. O—H⋯O hydrogen bonds link the water molecules, the perchlorate anions and the complex anions. π–π interactions between the pyridine rings of the complex anions are also observed [centroid–centroid distance = 3.804 (3) Å]. PMID:23125573
AES, EELS and XPS characterization of Ti(C, N, O) films prepared by PLD using a Ti target in N2, CH4, O2 and CO as reactive gases

International Nuclear Information System (INIS)

Soto, G.

2004-01-01

Titanium-based films were grown on (1 0 0)-Si substrates by the pulsed laser deposition (PLD) method using a Ti target in reactive atmospheres. The films were grown in vacuum (Ti-film), O 2 (TiO x ), N 2 (TiN x ), CH 4 (TiC x ), CO (TiC x O y ), N 2 +CH 4 (TiC x N y ) and CO+N 2 (TiC x N y O z ). After depositions, every film is characterized in situ by Auger, electron-energy loss and X-ray photoelectron (XPS) spectroscopies. For the binary compounds the stoichiometry is regulated without difficulty by gas pressure during ablation. However, for ternary and quaternary compounds there is a tendency to produce chemically inhomogeneous films. For example, the ablation of Ti in a N 2 +CH 4 environment results in a TiNC:C composite. In this case, the overabundance of nitrogen influences the segregation of carbon. In the other hand, the O 2 +CH 4 mixture was ineffectively to produce TiC x O y films, yielding mostly TiO 2 with traces of embedded carbon. By using CO as reactive gas the TiC x O y films were completed. Also, a mixture of CO with N 2 was tested to produce quaternary TiC x N y O z compounds. Based on these results, it is recommended that better control on film stoichiometry and chemical homogeneity can be achieved by using reactive gases with predetermined C:N:O ratios
Betaine Phosphate (CH3)3N+CH2COO-.H3PO4 Modification Using D2O

International Nuclear Information System (INIS)

Saryati; Ridwan; Deswita; Sugiantoro, Sugik

2002-01-01

Betaine fosfate (CH 3 ) 3 N + CH 2 COO - .H 3 PO 4 modification by using D 2 O has been studied. This modification was carried out by slowly evaporation the saturated Betaine phosphat in the D 2 O solution in the dry box at 40 o C, until the dry crystal were formed. Based on the NMR data, can be concluded that the exchange process with D has been runed well and Betaine phosphate-D (CH 3 ) 3 N + CH 2 COO - .H 3 PO 4 has been resulted. From the X-ray diffraction pattern data can be concluded that there are a deference in the crystal structure between Betaine phosphate and Betaine phosphate modification result. From the Differential Scanning Colorimeter (DSC) diagram at the range temperature from 30 o C to 250 o C, can be shown that the Betaine phosphate-H has two endothermic transition phase, at 99 o C with a very little adsorbed calor and at 221.50 o C with -26.75 cal/g. Modified Betaine phosphate has also two endothermic transition phase, at 99.86 o C with -1.94 cal/g and at 171.01 o C with -3.48 cal/g. It can be conclosed that the D atom substitution on the H atoms in Betaine phosphate, to change the crystal and the endothermic fase temperature and energy
Facile one-pot construction of α-Fe{sub 2}O{sub 3}/g-C{sub 3}N{sub 4} heterojunction for arsenic removal by synchronous visible light catalysis oxidation and adsorption

Energy Technology Data Exchange (ETDEWEB)

Sun, Suwen; Ji, Chunnuan, E-mail: 1842355613@qq.com; Wu, Lingling; Chi, Shenghua; Qu, Rongjun; Li, Yan; Lu, Yangxiao; Sun, Changmei; Xue, Zhongxin

2017-06-15

α-Fe{sub 2}O{sub 3}/g-C{sub 3}N{sub 4} composites with heterojunction were prepared by facile one-pot synthesis using ferric chloride and dicyandiamide as precursors. The newly formed composites were applied to remove arsenic from aqueous solution for the first time through synchronous visible light catalysis oxidation and adsorption. α-Fe{sub 2}O{sub 3}/g-C{sub 3}N{sub 4} composites were characterized by wide-angle X-ray powder diffraction, transmission electron microscopy, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, UV–Vis diffuse reflectance spectroscopy, and BET surface analysis. Under visible light irradiation, As(III) was oxidized to As(V) efficiently on the surface of α-Fe{sub 2}O{sub 3}/g-C{sub 3}N{sub 4}. In addition, the oxidized arsenic could be adsorbed in situ, resulting in the effective arsenic removal. The enhancement of photocatalytic activity the composites was attributed to the construction of heterojunction between α-Fe{sub 2}O{sub 3} and g-C{sub 3}N{sub 4}. A possible oxidation mechanism of the as-composites for As(III) under visible light irradiation was also elucidated. - Highlights: • α-Fe{sub 2}O{sub 3}/g-C{sub 3}N{sub 4} composites with heterojunction was prepared by facile one-pot synthesis. • The photocatalytic activity of α-Fe{sub 2}O{sub 3}/g-C{sub 3}N{sub 4} composites under visible light irradiation for As(III) was evaluated. • Synchronous visible light catalysis oxidation and adsorption were achieved for the removal of arsenic. • The reasonable oxidation mechanism of the composites for As(III) under visible light irradiation was investigated.
Synthesis and Characterization of Ru(II) Tris(1,1O-phenanthroline)-Electron Acceptor Dyads Incorporating the 4-benzoyl-N-methylpyridinium Cation or N-Benzyl-N'-methyl-viologen. Improving the Dynamic Range, Sensitivity and Response Time of Sol-Gel Based Optical Oxygen Sensors

Science.gov (United States)

Leventis, Nicholas; Rawashdeh, Abdel-Monen M.; Elder, Ian A.; Yang, Jinhua; Dass, Amala; Sotiriou-Leventis, Chariklia

2004-01-01

The title compounds (1 and 2, above) were synthesized by Sonogashira coupling reactions of appropriate Ru(1I) complexes with the electron a cceptors. Characterization was conducted in solution and in frozen ma trices. Finally, the title compounds were evaluated as dopants of sol-gel materials. It was found that the intramolecular quenching efficie ncy of 4-benzoyl-Nmethylpyridinium cation in solution depends on the solvent: photoluminescence is quenched completely in CH,CN, but not i n methanol or ethanol. On the other hand, intramolecular emission que nching by 4-benzyl-N-methyl viologen is complete in all solvents. The difference between the two quenchers is traced electrochemically to t he solvation of the 4-benzoyl-Nmethylpyridiniums by alcohol. In froze n matrices or adsorbed on the surfaces of silica aerogel, both Ru(I1) complex/electron acceptor dyads of this study are photoluminescent, and the absence of quenching has been traced to the environmental rigi dity. When doped aerogels are cooled at 77 K, the emission intensity increases by approximately 4x, and the spectra shift to the blue, analogous to what is observed with Ru(I1) complexes in solutions undergoi ng fluid-to-rigid transition. However, in contrast to frozen solution s, the luminescent moieties in the bulk of aerogels kept at low tempe ratures are still accessible to gas-phase quenchers diffusing through the mesopores, leading to more sensitive platforms for sensors than o ther room-temperature configurations. Thus the photoluminescence of o ur Ru(I1) complex dyads adsorbed on aerogel is quenchable by O2 both at room temperature and at 77 K. Furthermore, it was also found that O 2 modulates the photoluminescence of aerogels doped with 4-benzoyl -N -methylpyridinium-based dyads over a wider dynamic range compared wi th aerogels doped with either our vislogen-based dyads or with Ru(I1) tris(1,lO-phenanthroline) itself.

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