Determination and modeling for the solubility of Na_2WO_4·2H_2O and Na_2MoO_4·2H_2O in the (Na"+ + MoO_4"2"− + WO_4"2"− + SO_4"2"− + H_2O) system

International Nuclear Information System (INIS)

Ning, Pengge; Xu, Weifeng; Cao, Hongbin; Xu, Hongbin

2016-01-01

Highlights: • The solubility of Na_2MoO_4·2H_2O and Na_2WO_4·2H_2O in Na_2MoO_4–Na_2WO_4–Na_2SO_4–H_2O were performed. • The solubility of sodium tungstate dihydrate in Na_2WO_4–Na_2SO_4–H_2O was determined. • The new model was established via regressing the published and the determined data. • The Pitzer parameter and the solubility product constant of the salt in solution were calculated. • The model was used to estimate the solubility of the sodium molybdate and sodium tungstate. - Abstract: The solubility of sodium tungstate dihydrate and sodium molybdate dihydrate in the (Na_2MoO_4 + Na_2WO_4 + Na_2SO_4 + H_2O) system was studied using experimental and calculated methods. The osmotic coefficient of sodium tungstate was fitted to calculate the thermodynamics parameters of (Na_2WO_4 + H_2O) system. The solubility of sodium tungstate dihydrate was determined using the dynamic method in Na_2WO_4–Na_2SO_4–H_2O to establish the new model which can provide an estimate the solubility of sodium tungstate dihydrate in various conditions, combined with the data published, the solubility of sodium tungstate dihydrate and the sodium molybdate dihydrate in quaternary system of (Na_2MoO_4 + Na_2WO_4 + Na_2SO_4 + H_2O) was estimated using the parameters of the two ternary systems of (Na_2WO_4 + Na_2SO_4 + H_2O) and (Na_2MoO_4 + Na_2SO_4 + H_2O). The results show that the AARD is always small and the calculated value is basically consistent with the experimental values for the system studied.

Systems Li2B4O7 (Na2B4O7, K2B4O7)-N2H3H4OH-H2O at 25 deg C

International Nuclear Information System (INIS)

Skvortsov, V.G.; Sadetdinov, Sh.V.; Akimov, V.M.; Mitrasov, Yu.N.; Petrova, O.V.; Klopov, Yu.N.

1994-01-01

Phase equilibriums in the Li 2 B 4 O 7 (Na 2 B 4 O 7 , K 2 B 4 O 7 )-N 2 H 3 H 4 OH-H 2 O systems were investigated by methods of isothermal solubility, refractometry and PH-metry at 25 deg C for the first time. Lithium and sodium tetraborates was established to form phases of changed composition mM 2 B 4 O 7 ·nN 2 H 3 C 2 H 4 OH·XH 2 O, where M=Li, Na with hydrazine ethanol. K 2 B 4 O 7 ·4H 2 O precipitates in solid phase in the case of potassium salt. Formation of isomorphous mixtures was supported by X-ray diffraction and IR spectroscopy methods

A model for radiolysis of water and aqueous solutions of H2, H2O2 and O2

International Nuclear Information System (INIS)

Ershov, B.G.; Gordeev, A.V.

2008-01-01

Kinetic model for the radiolysis of pure water describing the formation of H 2 , H 2 O 2 and O 2 and the radiation chemical transformations of aqueous solutions containing these compounds over a broad range of concentrations, pH, absorbed doses and dose rates is proposed and substantiated. The model includes a set of chemical reactions with optimized rate constants and the radiation chemical yields of radiolysis products. The model applicability to the description of the whole set of data on the radiation chemical transformations of water and aqueous solutions of H 2 , H 2 O 2 and O 2 is demonstrated

Study of ZrO2-H2SO4-(NH4)2SO4(NH4Cl)-H2O systems

International Nuclear Information System (INIS)

Motov, D.L.; Sozinova, Yu.P.; Rys'kina, M.P.

1988-01-01

Regions of formation, composition and solubility of ammonium sulfatozirconates (ASZ) in ZrO 2 -H 2 SO 4 -(NH 4 ) 2 SO 4 (NH 4 Cl)-H 2 O systems at 25 and 75 deg C are studied by the isothermal method. Five ASZ: (NH 4 ) 2 Zr(OH) 2 (SO 4 ) 2 , NH 4 ZrOH(SO 4 ) 2 xH 2 O, NH 4 ZrO 0.5 (OH) 2 SO 4 x1.5H 2 O, (NH 4 ) 2 Zr(SO 4 ) 3 x2H 2 O, (NH 4 ) 4 Zr(SO 4 ) 4 x4H 2 O are detected, their properties are investigated. Main sulfates are new compounds never described ealier

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...

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.

Hydrothermal synthesis and structural characterization of an organic–inorganic hybrid sandwich-type tungstoantimonate [Cu(en)2(H2O)]4[Cu(en)2(H2O)2][Cu2Na4(α-SbW9O33)2]·6H2O

International Nuclear Information System (INIS)

Liu, Yingjie; Cao, Jing; Wang, Yujie; Li, Yanzhou; Zhao, Junwei; Chen, Lijuan; Ma, Pengtao; Niu, Jingyang

2014-01-01

An organic–inorganic hybrid sandwich-type tungstoantimonate [Cu(en) 2 (H 2 O)] 4 [Cu(en) 2 (H 2 O) 2 ][Cu 2 Na 4 (α-SbW 9 O 33 ) 2 ]·6H 2 O (1) has been synthesized by reaction of Sb 2 O 3 , Na 2 WO 4 ·2H 2 O, CuCl 2 ·2H 2 O with en (en=ethanediamine) under hydrothermal conditions and structurally characterized by elemental analysis, inductively coupled plasma atomic emission spectrometry, IR spectrum and single-crystal X-ray diffraction. 1 displays a centric dimeric structure formed by two equivalent trivacant Keggin [α-SbW 9 O 33 ] 9− subunits sandwiching a hexagonal (Cu 2 Na 4 ) cluster. Moreover, those related hexagonal hexa-metal cluster sandwiched tungstoantimonates have been also summarized and compared. The variable-temperature magnetic measurements of 1 exhibit the weak ferromagnetic exchange interactions within the hexagonal (Cu 2 Na 4 ) cluster mediated by the oxygen bridges. - Graphical abstract: An organic–inorganic hybrid (Cu 2 Na 4 ) sandwiched tungstoantimonate [Cu(en) 2 (H 2 O)] 4 [Cu (en) 2 (H 2 O) 2 ][Cu 2 Na 4 (α-SbW 9 O 33 ) 2 ]·6H 2 O was synthesized and magnetic properties was investigated. Display Omitted - Highlights: • Organic–inorganic hybrid sandwich-type tungstoantimonate. • (Cu 2 Na 4 sandwiched) tungstoantimonate [Cu 2 Na 4 (α-SbW 9 O 33 ) 2 ] 10− . • Ferromagnetic tungstoantimonate

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

Kinetic removal of haloacetonitrile precursors by photo-based advanced oxidation processes (UV/H2O2, UV/O3, and UV/H2O2/O3).

Science.gov (United States)

Srithep, Sirinthip; Phattarapattamawong, Songkeart

2017-06-01

The objective of the study is to evaluate the performance of conventional treatment process (i.e., coagulation, flocculation, sedimentation and sand filtration) on the removals of haloacetonitrile (HAN) precursors. In addition, the removals of HAN precursors by photo-based advanced oxidation processes (Photo-AOPs) (i.e., UV/H 2 O 2 , UV/O 3 , and UV/H 2 O 2 /O 3 ) are investigated. The conventional treatment process was ineffective to remove HAN precursors. Among Photo-AOPs, the UV/H 2 O 2 /O 3 was the most effective process for removing HAN precursors, followed by UV/H 2 O 2 , and UV/O 3 , respectively. For 20min contact time, the UV/H 2 O 2 /O 3 , UV/H 2 O 2 , and UV/O 3 suppressed the HAN formations by 54, 42, and 27% reduction. Increasing ozone doses from 1 to 5 mgL -1 in UV/O 3 systems slightly improved the removals of HAN precursors. Changes in pH (6-8) were unaffected most of processes (i.e., UV, UV/H 2 O 2 , and UV/H 2 O 2 /O 3 ), except for the UV/O 3 system that its efficiency was low in the weak acid condition. The pseudo first-order kinetic constant for removals of dichloroacetonitrile precursors (k' DCANFP ) by the UV/H 2 O 2 /O 3 , UV/H 2 O 2 and standalone UV systems were 1.4-2.8 orders magnitude higher than the UV/O 3 process. The kinetic degradation of dissolved organic nitrogen (DON) tended to be higher than the k' DCANFP value. This study firstly differentiates the kinetic degradation between DON and HAN precursors. Copyright © 2017 Elsevier Ltd. All rights reserved.

Redetermination of Ce[B5O8(OH(H2O]NO3·2H2O

Directory of Open Access Journals (Sweden)

Ya-Xi Huang

2012-05-01

Full Text Available The crystal structure of Ce[B5O8(OH(H2O]NO3·2H2O, cerium(III aquahydroxidooctaoxidopentaborate nitrate dihydrate, has been redetermined from single-crystal X-ray diffraction data. In contrast to the previous determination [Li et al. (2003. Chem. Mater. 15, 2253–2260], the present study reveals the location of all H atoms, slightly different fundamental building blocks (FBBs of the polyborate anions, more reasonable displacement ellipsoids for all non-H atoms, as well as a model without disorder of the nitrate anion. The crystal structure is built from corrugated polyborate layers parallel to (010. These layers, consisting of [B5O8(OH(H2O]2− anions as FBBs, stack along [010] and are linked by Ce3+ ions, which exhibit a distorted CeO10 coordination sphere. The layers are additionally stabilized via O—H...O hydrogen bonds between water molecules and nitrate anions, located at the interlayer space. The [BO3(H2O]-group shows a [3 + 1] coordination and is considerably distorted from a tetrahedral configuration. Bond-valence-sum calculation shows that the valence sum of boron is only 2.63 valence units (v.u. when the contribution of the water molecule (0.49 v.u. is neglected.

Investigation of the Na2(H2PO2)2 - Ba(H2PO2)2 - H2O Water-Salt Ternary System at Room Temperature

OpenAIRE

Erge, Hasan; Turan, Hakan; Kul, Ali Riza

2016-01-01

Objective: In this study, the solubility, density, conductivity and phase equilibria of the Na2(H2PO2)2-Ba(H2PO2)2-H2O ternary system located in the structure of the Na+, Ba2+, (H2PO2)-//H2O quaternary reciprocal water-salt system were investigated using physicochemical analysis methods. Material and Methods: Riedel-de Haen and Merck salts were used to investigate the solubility and phase equilibria of the Na2(H2PO2)2 -Ba(H2PO2)2-H2O ternary water–salt system at room temperature Res...

H{sub 2} dissociation on γ-Al{sub 2}O{sub 3} supported Cu/Pd atoms: A DFT investigation

Energy Technology Data Exchange (ETDEWEB)

Wang, Hongtao [College of Environmental Science and Engineering, Taiyuan University of Technology, Taiyuan 030024, Shanxi (China); Key Laboratory of Coal Science and Technology of Shanxi Province and Ministry of Education, Taiyuan University of Technology, Taiyuan 030024, Shanxi (China); Chen, Lijuan [Key Laboratory of Coal Science and Technology of Shanxi Province and Ministry of Education, Taiyuan University of Technology, Taiyuan 030024, Shanxi (China); Lv, Yongkang, E-mail: lykang@tyut.edu.cn [Key Laboratory of Coal Science and Technology of Shanxi Province and Ministry of Education, Taiyuan University of Technology, Taiyuan 030024, Shanxi (China); Ren, Ruipeng, E-mail: s2003wht@126.com [Key Laboratory of Coal Science and Technology of Shanxi Province and Ministry of Education, Taiyuan University of Technology, Taiyuan 030024, Shanxi (China)

2014-01-30

The density functional theory (DFT) was applied to investigate the promotion effects of single Cu and Pd atoms deposition on γ-Al{sub 2}O{sub 3} surface for the adsorption and dissociation of H{sub 2} molecule, which is of importance for many catalysis reactions. Due to its strong Lewis acidity, the tri-coordinated surface Al site was identified to be the most preferable site for both Cu and Pd location. The inner surface electrons rearrangement from O to Al of alumina was found to be a key factor to stabilize the Cu/Pd adsorption configurations, rather than the total electrons transfer between Cu/Pd and the surface. It was found that the supported Cu and Pd atoms are more active for H{sub 2} dissociation than the clean γ-Al{sub 2}O{sub 3} surface. The supported Pd is more active than Cu for H{sub 2} dissociation. In addition, the metal–support interaction of the γ-Al{sub 2}O{sub 3} supported Cu/Pd atoms are more favored than the metal–metal interaction of the metal clusters for the H{sub 2} dissociated adsorption.

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....

An open-framework three-dimensional indium oxalate: [In(OH)(C2O4)(H2O)]3.H2O

International Nuclear Information System (INIS)

Yang Sihai; Li Guobao; Tian Shujian; Liao Fuhui; Lin Jianhua

2005-01-01

By hydrothermal reaction of In 2 O 3 with H 2 C 2 O 4 .2H 2 O in the presence of H 3 BO 3 at 155 deg. C, an open-framework three-dimensional indium oxalate of formula [In(OH)(C 2 O 4 )(H 2 O)] 3 .H 2 O (1) has been obtained. The compound crystallizes in the trigonal system, space group R3c with a=18.668(3)A, c=7.953(2)A, V=2400.3(7)A 3 , Z=6, R 1 =0.0352 at 298K. The small pores in 1 are filled with water molecules. It loses its filled water at about 180 deg. C without the change of structure, then the bounded water at 260 deg. C, and completely decompounds at 324 deg. C. The residue is confirmed to be In 2 O 3

Computational Elucidation of a Role That Brønsted Acidification of the Lewis Acid-Bound Water Might Play in the Hydrogenation of Carbonyl Compounds with H2 in Lewis Basic Solvents.

Science.gov (United States)

Heshmat, Mojgan; Privalov, Timofei

2017-08-25

Brønsted acidification of water by Lewis acid (LA) complexation is one of the fundamental principles in chemistry. Using transition-state calculations (TS), herein we investigate the role that Brønsted acidification of the LA-bound water might play in the mechanism of the hydrogenation of carbonyl compounds in Lewis basic solvents under non-anhydrous conditions. The potential energy scans and TS calculations were carried out with a series of eight borane LAs as well as the commonly known strong LA AlCl 3 in 1,4-dioxane or THF as Lewis basic solvents. Our molecular model consists of the dative LA-water adduct with hydrogen bonds to acetone and a solvent molecule plus one additional solvent molecule that participates is the TS structure describing the cleavage of H 2 at acetone's carbonyl carbon atom. In all the molecular models applied here, acetone (O=CMe 2 ) is the archetypical carbonyl substrate. We demonstrate that Brønsted acidification of the LA-bound water can indeed lower the barrier height of the solvent-involving H 2 -cleavage at the acetone's carbonyl carbon atom. This is significant because at present it is believed that the mechanism of the herein considered reaction is described by the same mechanism regardless of whether the reaction conditions are strictly anhydrous or non-anhydrous. Our results offer an alternative to this belief that warrants consideration and further study. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Using H2O2 as oxidant in leaching of uranium ores. The new research on the reaction of H2O2 with Fe2+

International Nuclear Information System (INIS)

Gao Xizhen

1997-05-01

The new research on the reaction of H 2 O 2 with Fe 2+ has been studied. Through determining the electric potential, pH and O 2 release during the mutual titration between H 2 O 2 solution and FeSO 4 solution, deduced the chemical equations of H 2 O 2 (without free hydroxyl) oxidizing FeSO 4 and Fe 2 (SO 4 ) 3 oxidizing H 2 O 2 . The research results show that acid is a catalytic agent for decomposing H 2 O 2 to be O 2 and H 2 O besides iron ions. The maximum oxidizing potential is up to about 640 mV. While using H 2 O 2 as an oxidant in uranium heap leaching and in-situ leaching, controlling electric potential can be regarded as a method for adjusting the feeding speed of H 2 O 2 to keep the electric potential below 500 mV, thus the H 2 O 2 decomposition can be reduced. (13 refs., 3 tabs., 1 fig.)

DOE/NASA Lewis large-wind-turbine program

Energy Technology Data Exchange (ETDEWEB)

Thomas, R.L.

1982-01-01

There are several ongoing large wind system development project; ots directed toward meeting the technology requirements for utility applications. First generation tehcnology machines (Mod-0A and Mod-1) and second generation machines (Mod-2) are in opoeration at selected utility sites. Third generation technology machines (Mod-5) are in the design phase and are scheduled for initial operation in 1984 if project funding is continued. An overview of the large wind turbine activities managed by NASA Lewis is provided. These activities include results from the first and second generation field machines (Mod-0A, 01, and -2), the status of the Department of Interior WTS-4 machine for which NASA is responsible for technical management, and the design phase of the third generation wind turbines (Mod-5).

Vibrational spectra of Cs2Cu(SO4)2·6H2O and Cs2Cu(SeO4)2·nH2O (n = 4, 6) with a crystal structure determination of the Tutton salt Cs2Cu(SeO4)2·6H2O

Science.gov (United States)

Wildner, M.; Marinova, D.; Stoilova, D.

2016-02-01

The solubility in the three-component systems Cs2SO4-CuSO4-H2O and Cs2SeO4-CuSeO4-H2O have been studied at 25 °C. The experimental results show that double salts, Cs2Cu(SO4)2·6H2O and Cs2Cu(SeO4)2·4H2O, crystallize from the ternary solutions within large concentration ranges. Crystals of Cs2Cu(SeO4)2·6H2O were synthesized at somewhat lower temperatures (7-8 °C). The thermal dehydration of the title compounds was studied by TG, DTA and DSC methods and the respective dehydration schemes are proposed. The calculated enthalpies of dehydration (ΔHdeh) have values of: 434.2 kJ mol-1 (Cs2Cu(SeO4)2·6H2O), 280.9 kJ mol-1 (Cs2Cu(SeO4)2·4H2O), and 420.2 kJ mol-1 (the phase transition of Cs2Cu(SO4)2·6H2O into Cs2Cu(SO4)2·H2O). The crystal structure of Cs2Cu(SeO4)2ṡ6H2O was determined from single crystal X-ray diffraction data. It belongs to the group of Tutton salts, crystallizing isotypic to the respective sulfate in a monoclinic structure which is characterized by isolated Cu(H2O)6 octahedra and SeO4 tetrahedra, interlinked by hydrogen bonds and [9]-coordinated Cs+ cations. Infrared spectra of the cesium copper compounds are presented and discussed with respect to both the normal modes of the tetrahedral ions and the water molecules. The analysis of the infrared spectra of the double compounds reveals that the distortion of the selenate tetrahedra in Cs2Cu(SeO4)2·4H2O is stronger than those in Cs2Cu(SeO4)2·6H2O in agreement with the structural data. Matrix-infrared spectroscopy was applied to confirm this claim - Δν3 for SO4 2 - ions matrix-isolated in Cs2Cu(SeO4)2·6H2O has a value of 35 cm-1 and that of the same ions included in Cs2Cu(SeO4)2·4H2O - 84 cm-1. This spectroscopic finding is due to the formation of strong covalent bands Cu-OSO3 on one hand, and on the other to the stronger deformation of the host SeO4 2 - tetrahedra in Cs2Cu(SeO4)2·4H2O as compared to those in Cs2Cu(SeO4)2·6H2O. The strength of the hydrogen bonds as deduced from the

Hydrogen constituents of the mesosphere inferred from positive ions - H2O, CH4, H2CO, H2O2, and HCN

Science.gov (United States)

Kopp, E.

1990-01-01

The concentrations in the mesosphere of H2O, CH4, H2CO, H2O2, and HCN were inferred from data on positive ion compositions, obtained from one mid-latitude and four high-latitude rocket flights. The inferred concentrations were found to agree only partially with the ground-based microwave measurements and/or model prediction by Garcia and Solomon (1985). The CH4 concentration was found to vary between 70 and 4 ppb in daytime and 900 and 100 ppbv at night, respectively. Unexpectedly high H2CO concentrations were obtained, with H2CO/H2O ratios between 0.0006 and 0.1, and a mean HCN volume mixing ratio of 6 x 10 to the -10th was inferred.

Distance Learning With NASA Lewis Research Center's Learning Technologies Project

Science.gov (United States)

Petersen, Ruth

1998-01-01

The NASA Lewis Research Center's Learning Technologies Project (LTP) has responded to requests from local school district technology coordinators to provide content for videoconferencing workshops. Over the past year we have offered three teacher professional development workshops that showcase NASA Lewis-developed educational products and NASA educational Internet sites. In order to determine the direction of our involvement with distance learning, the LTP staff conducted a survey of 500 U.S. schools. We received responses from 72 schools that either currently use distance learning or will be using distance learning in 98-99 school year. The results of the survey are summarized in the article. In addition, the article provides information on distance learners, distance learning technologies, and the NASA Lewis LTP videoconferencing workshops. The LTP staff will continue to offer teacher development workshops through videoconferencing during the 98-99 school year. We hope to add workshops on new educational products as they are developed at NASA Lewis.

VUV photoionization cross sections of HO2, H2O2, and H2CO.

Science.gov (United States)

Dodson, Leah G; Shen, Linhan; Savee, John D; Eddingsaas, Nathan C; Welz, Oliver; Taatjes, Craig A; Osborn, David L; Sander, Stanley P; Okumura, Mitchio

2015-02-26

The absolute vacuum ultraviolet (VUV) photoionization spectra of the hydroperoxyl radical (HO2), hydrogen peroxide (H2O2), and formaldehyde (H2CO) have been measured from their first ionization thresholds to 12.008 eV. HO2, H2O2, and H2CO were generated from the oxidation of methanol initiated by pulsed-laser-photolysis of Cl2 in a low-pressure slow flow reactor. Reactants, intermediates, and products were detected by time-resolved multiplexed synchrotron photoionization mass spectrometry. Absolute concentrations were obtained from the time-dependent photoion signals by modeling the kinetics of the methanol oxidation chemistry. Photoionization cross sections were determined at several photon energies relative to the cross section of methanol, which was in turn determined relative to that of propene. These measurements were used to place relative photoionization spectra of HO2, H2O2, and H2CO on an absolute scale, resulting in absolute photoionization spectra.

Hydrothermal synthesis and crystal structures of new uranyl oxalate hydroxides: α- and β-[(UO2)2(C2O4)(OH)2(H2O)2] and [(UO2)2(C2O4)(OH)2(H2O)2].H2O

International Nuclear Information System (INIS)

Duvieubourg, Laurence; Nowogrocki, Guy; Abraham, Francis; Grandjean, Stephane

2005-01-01

Two modifications of the new uranyl oxalate hydroxide dihydrate [UO 2 ) 2 (C 2 O 4 )(OH) 2 (H 2 O) 2 ] (1 and 2) and one form of the new uranyl oxalate hydroxide trihydrate [(UO 2 ) 2 (C 2 O 4 )(OH) 2 (H 2 O) 2 ].H 2 O (3) were synthesized by hydrothermal methods and their structures determined from single-crystal X-ray diffraction data. The crystal structures were refined by full-matrix least-squares methods to agreement indices R(wR)=0.0372(0.0842) and 0.0267(0.0671) calculated for 1096 and 1167 unique observed reflections (I>2σ(I)), for α (1) and β (2) forms, respectively and to R(wR)=0.0301(0.0737) calculated for 2471 unique observed reflections (I>2σ(I)), for 3. The α-form of the dihydrate is triclinic, space group P1-bar , Z=1, a=6.097(2), b=5.548(2), c=7.806(3)A, α=89.353(5), β=94.387(5), γ=97.646(5) o , V=260.88(15)A 3 , β-form is monoclinic, space group C2/c, Z=4, a=12.180(3), b=8.223(2), c=10.777(3)A, β=95.817(4), V=1073.8(5)A 3 . The trihydrate is monoclinic, space group P2 1 /c, Z=4, a=5.5095(12), b=15.195(3), c=13.398(3)A, β=93.927(3), V=1119.0(4)A 3 . In the three structures, the coordination of uranium atom is a pentagonal bipyramid composed of dioxo UO 2 2+ cation perpendicular to five equatorial oxygen atoms belonging to one bidentate oxalate ion, one water molecule and two hydroxyl ions in trans configuration in 2 and in cis configuration in 1 and 3. The UO 7 polyhedra are linked through hydroxyl oxygen atoms to form different structural building units, dimers [U 2 O 10 ] obtained by edge-sharing in 1, chains [UO 6 ] ∼ and tetramers [U 4 O 26 ] built by corner-sharing in 2 and 3, respectively. These units are further connected by oxalate entities that act as bis-bidentate to form one-dimensional chains in 1 and bi-dimensional network in 2 and 3. These chains or layers are connected in frameworks by hydrogen-bond arrays

Synthesis of "trans"-4,5-Bis-dibenzylaminocyclopent-2-Enone from Furfural Catalyzed by ErCl[subscript 3]·6H[subscript 2]O

Science.gov (United States)

Estevão, Mónica S.; Martins, Ricardo J. V.; Alfonso, Carlos A. M.

2017-01-01

An experiment exploring the chemistry of the carbonyl group for the one-step synthesis of "trans"-4,5- dibenzylaminocyclopent-2-enone is described. The reaction of furfural and dibenzylamine in the environmentally friendly solvent ethanol and catalyzed by the Lewis acid ErCl[subscript 3]·6H[subscript 2]O afforded the product in high…

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.

Does residual H2O2 result in inhibitory effect on enhanced anaerobic digestion of sludge pretreated by microwave-H2O2 pretreatment process?

Science.gov (United States)

Liu, Jibao; Jia, Ruilai; Wang, Yawei; Wei, Yuansong; Zhang, Junya; Wang, Rui; Cai, Xing

2017-04-01

This study investigated the effects of residual H 2 O 2 on hydrolysis-acidification and methanogenesis stages of anaerobic digestion after microwave-H 2 O 2 (MW-H 2 O 2 ) pretreatment of waste activated sludge (WAS). Results showed that high sludge solubilization at 35-45 % was achieved after pretreatment, while large amounts of residual H 2 O 2 remained and refractory compounds were thus generated with high dosage of H 2 O 2 (0.6 g H 2 O 2 /g total solids (TS), 1.0 g H 2 O 2 /g TS) pretreatment. The residual H 2 O 2 not only inhibited hydrolysis-acidification stage mildly, such as hydrolase activity, but also had acute toxic effect on methanogens, resulting in long lag phase, low methane yield rate, and no increase of cumulative methane production during the 30-day BMP tests. When the low dosage of H 2 O 2 at 0.2 g H 2 O 2 /g TS was used in MW-H 2 O 2 pretreatment, sludge anaerobic digestion was significantly enhanced. The cumulative methane production increased by 29.02 %, but still with a lag phase of 1.0 day. With removing the residual H 2 O 2 by catalase, the initial lag phase of hydrolysis-acidification stage decreased from 1.0 to 0.5 day.

Complexing in (NH4)2SeO4-UO2SeO4 H2O system

International Nuclear Information System (INIS)

Serezhkina, L.B.

1994-01-01

Isotherm of solubility in the (NH 4 ) 2 SeO 4 -UO 2 SeO 4 -H 2 O system has been constructed at 25 deg C. (NH 4 ) 2 (UO 2 ) 2 (SeO 4 ) 3 x6H 2 O formation is established for the first time and certain its physicochemical properties are determined. Regularities of complexing in the R 2 Se) 4 -UO 2 SeO 4 -H 2 O systems, where R-univalent cation are under discussion. 6 refs.; 3 tabs

A cluster DFT study of NH{sub 3} and NO adsorption on the (MoO{sub 2}){sup 2+}/HZSM-5 surface: Lewis versus Brønsted acid sites

Energy Technology Data Exchange (ETDEWEB)

Yan, Zhifeng [College of Chemistry and Chemical Engineering, Taiyuan University of Technology, Taiyuan 030024, Shanxi (China); College of Material Science and Engineering, Taiyuan University of Technology, Taiyuan 030024, Shanxi (China); Zuo, Zhijun [Key Laboratory of Coal Science and Technology of Ministry of Education and Shanxi Province, Taiyuan University of Technology, Taiyuan 030024, Shanxi (China); Li, Zhe, E-mail: lizhe@tyut.edu.cn [College of Chemistry and Chemical Engineering, Taiyuan University of Technology, Taiyuan 030024, Shanxi (China); Zhang, Jinshan [College of Material Science and Engineering, Taiyuan University of Technology, Taiyuan 030024, Shanxi (China)

2014-12-01

Graphical abstract: - Highlights: • NH{sub 3} adsorption is found to be more favorable energetically than NO adsorption on both Lewis and Brønsted acid sites. • Lewis and Brønsted acid sites are competitive energetically for NH{sub 3} adsorption. • Reduced-state Mo{sup 5+} is suggested to play a key role in adsorption and activation of NO{sub x} together with the adsorbed NH{sub 4}{sup +}. - Abstract: A systematic DFT study was carried out to investigate NH{sub 3} and NO adsorption on both Lewis and Brønsted acid sites of (MoO{sub 2}){sup 2+}/HZSM-5 catalyst by using cluster models. The adsorption energy results indicate that NH{sub 3} could strongly adsorb on both Lewis and Brønsted acid sites in the form of coordinated NH{sub 3} and NH{sub 4}{sup +}, respectively, whereas NO represents poorer adsorption ability. It is also found that Lewis and Brønsted acid sites are competitive energetically for NH{sub 3} adsorption. According to the difference in the proposed mechanisms for NH{sub 3} adsorption on different acid sites, particular attention has been focused on the first dissociation of coordinated NH{sub 3} for Lewis acid site and the effect of Mo site on the introduction of NO for Brønsted acid site. For the coordinated NH{sub 3} on Lewis acid site, the more electron donation from NH{sub 3} is, the greater its adsorption stability is and the higher active its H atoms are. In addition, DOS results show that stability of the H atoms is enhanced by interacting with framework oxygen and especially the H atoms chemical-bonded with framework oxygen. For the NH{sub 4}{sup +} on Brønsted acid site, reduced-state Mo{sup 5+} holds stronger reducibility and oxidizability than terminal oxygen, which is suggested to play a key role in adsorption and activation of NO{sub x} together with the adsorbed NH{sub 4}{sup +}.

Application of H2O2 and H2O2/Fe0 in removal of Acid Red 18 dye from aqueous solutions

Directory of Open Access Journals (Sweden)

Nazari Shahram

2013-08-01

Full Text Available Background & Aims of the Study: Organic dyes with a complex structure are often toxic, carcinogenic, mutagenic, non-biodegradation and stable in the environment and if released to the environment without treatment can endanger the environment and human health. The aim of this study was to evaluate the performance of H2O2 and H2O2/Fe0 Iron in removal of dye Acid Red 18 from aqueous solutions. Materials & Methods: This study was conducted at the laboratory scale. In this study, the removal efficiency of Acid Red 18 from a synthetic solution by H2O2 and H2O2/Fe0 was investigated. As well as Effect of solution pH, dye concentration, Concentration of Nanoscale Zero-Valent Iron, H2O2 and contact time in decolorization efficiency was investigated. Results: Results show that in pH=3, Contact time of 80 minutes, dye concentration of 50 mg/l and Concentration of Nanoscale Zero-Valent Iron of 2 g/l and H2O2 concentration equal to 200 mmol/l, the removal efficiency was about 98%. Conclusions: According to the results of experiments, H2O2/Fe0 has high efficiency in removal of Acid Red 18 from aqueous solution.

Competition between weak OH···π and CH··O hydrogen bonds: THz spectroscopy of the C2H2—H2O and C2H4—H2O complexes

DEFF Research Database (Denmark)

Andersen, Jonas; Heimdal, Jimmy; Nelander, B.

2017-01-01

an intermolecular CH⋯O hydrogen-bonded configuration of C2v symmetry with the H2O subunit acting as the hydrogen bond acceptor. The observation and assignment of two large-amplitude donor OH librational modes of the C2H4—H2O complex at 255.0 and 187.5 cm−1, respectively, confirms an intermolecular OH⋯π hydrogen...

Structure of LaH(PO3H)2.3H2O

International Nuclear Information System (INIS)

Loukili, M.; Durand, J.; Larbot, A.; Cot, L.; Rafiq, M.

1991-01-01

Lanthanum hydrogen bis(hydrogenphosphite) trihydrate, LaH(Po 3 H) 2 .3H 2 O, M r =353.8, monoclinic, P2 1 /c, a=9.687 (3), b=7.138 (2), c=13.518 A, β=104.48 (3) deg, V=905.0 (5) A 3 , Z=4, D m =2.56 (2), D x =2.598 Mg m -3 , λ(MoKα)=0.71073 A, μ(MoKα)=5.103 mm -1 , F(000)=672, T=300 K, R=0.032 for 1018 independent observed reflections. The structure contains two phosphite anions connected by a hydrogen bond. The La 3+ cation is eight coordinated by seven O atoms from phosphite anions and one O atom of a water molecule. (orig.)

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.

Combined use of O3/H2O2 and O3/Mn2+ in flotation of dairy wastewater

Directory of Open Access Journals (Sweden)

Marta Cristina Silva Carvalho

2018-05-01

Full Text Available This work investigated the degradation of organic matter present in synthetic dairy wastewater by the combination of ozonation (ozone (O3/hydrogen peroxide (H2O2 and catalytic ozonation (ozone (O3/manganese (Mn2+ associated with dispersed air flotation process. The effect of independent factors such as O3 concentration, pH and H2O2 and Mn2+ concentration was evaluated. For the flotation/O3/H2O2 treatment, the significant variables (p ≤ 0.05 were: O3 concentration (linear and quadratic effect, H2O2 concentration linear and quadratic effect, pH values (linear and quadratic effect and interaction O3 concentration versus pH. For catalytic ozonation, it was observed that the significant variable was the linear effect of O3 concentration. According to the desirability function, it was concluded that the optimal condition for the treatment of flotation/O3/H2O2 can be obtained in acidic solution using O3 concentrations greater than 42.9 mg L-1 combined with higher concentrations of H2O2 to 1071.5 mg L-1. On other hand, at pH values higher than 9.0, the addition of O3 may be neglected when using higher concentrations than 1071.5 mg L-1 of H2O2. For flotation/ozonation catalyzed by Mn2+, it was observed that metal addition did not affect treatment, resulting in an optimum condition: 53.8 mg L-1 of O3 and pH 3.6.

A Cadmium Anionic 1-D Coordination Polymer {[Cd(H2O6][Cd2(atr2(μ2-btc2(H2O4] 2H2O}n within a 3-D Supramolecular Charge-Assisted Hydrogen-Bonded and π-Stacking Network

Directory of Open Access Journals (Sweden)

Anas Tahli

2016-03-01

Full Text Available The hydrothermal reaction of 4,4′-bis(1,2,4-triazol-4-yl (btr and benzene-1,3,5-tricarboxylic acid (H3btc with Cd(OAc2·2H2O at 125 °C in situ forms 4-amino-1,2,4-triazole (atr from btr, which crystallizes to a mixed-ligand, poly-anionic chain of [Cd2(atr2(µ2-btc2(H2O4]2–. Together with a hexaaquacadmium(II cation and water molecules the anionic coordination-polymeric forms a 3-D supramolecular network of hexaaquacadmium(II-catena-[bis(4-amino-1,2,4-triazoletetraaquabis(benzene-1,3,5-tricarboxylatodicadmate(II] dihydrate, 1-D-{[Cd(H2O6][Cd2(atr2(µ2-btc2(H2O4] 2H2O}n which is based on hydrogen bonds (in part charge-assisted and π–π interactions.

Experimental Microkinetic Approach of De-NO x by NH 3 on V 2 O 5 /WO 3 /TiO 2 Catalysts. 4. Individual Heats of Adsorption of Adsorbed H 2 O Species on Sulfate-Free and Sulfated TiO 2 Supports

KAUST Repository

Giraud, Franç ois; Couble, Julien; Geantet, Christophe; Guilhaume, Nolven; Puzenat, Eric; Gros, Sé bastien; Porcheron, Lynda; Kanniche, Mohamed; Bianchi, Daniel

2015-01-01

© 2015 American Chemical Society. The present study is a part of an experimental microkinetic approach of the removal of NOx from coal-fired power plants by reduction with NH3 on V2O5/WO3/TiO2 catalysts (NH3-selective catalytic reduction, NH3-SCR). It is dedicated to the characterization of the heats of adsorption of molecularly adsorbed H2Oads species formed on sulfate-free and sulfated TiO2 supports. Water, which is always present during the NH3-SCR, may be in competition and/or react (formation of NH4⁺) with the adsorbed NH3 species controlling the coverage of the adsorbed intermediate species of the reaction. Mainly, an original experimental procedure named adsorption equilibrium infrared spectroscopy (AEIR) previously used for the adsorption of NH3 species on the same solids is adapted for the adsorption of H2O. At Ta = 300 K and for PH2 O ≤ 1 kPa, three main H2Oads species are formed (associated with a minor amount of dissociated H2O species) on the two TiO2 solids. The species are identified by the positions of their IR bands in the 3750-3000 cm^-1 range. Considering the decreasing order of stability, they are (a) coordinated to strong (L2) and weak (L1) Lewis sites and denoted H2O ads-L2 and H2Oads-L1, respectively, and (b) hydrogen bonded to the H2Oads-L species and on O^2-/OH sites of the solids (denoted H2Owads). The three species have a common well-defined δH2O IR band at a position in the range 1640-1610 cm^-1 according to the total coverage of the surface. According to the AEIR method, the evolution of the intensity of this IR band during the increase in the adsorption temperature Ta in isobaric condition provides the evolution of the average coverage of the three species and then to their individual heats of adsorption as a function of their coverage. It is shown that there are no significant differences on the two TiO2 solids. In particular, the heat of adsorption of the H2Oads-L2 species varies from �

Experimental Microkinetic Approach of De-NO x by NH 3 on V 2 O 5 /WO 3 /TiO 2 Catalysts. 4. Individual Heats of Adsorption of Adsorbed H 2 O Species on Sulfate-Free and Sulfated TiO 2 Supports

KAUST Repository

Giraud, François

2015-07-16

© 2015 American Chemical Society. The present study is a part of an experimental microkinetic approach of the removal of NOx from coal-fired power plants by reduction with NH3 on V2O5/WO3/TiO2 catalysts (NH3-selective catalytic reduction, NH3-SCR). It is dedicated to the characterization of the heats of adsorption of molecularly adsorbed H2Oads species formed on sulfate-free and sulfated TiO2 supports. Water, which is always present during the NH3-SCR, may be in competition and/or react (formation of NH4⁺) with the adsorbed NH3 species controlling the coverage of the adsorbed intermediate species of the reaction. Mainly, an original experimental procedure named adsorption equilibrium infrared spectroscopy (AEIR) previously used for the adsorption of NH3 species on the same solids is adapted for the adsorption of H2O. At Ta = 300 K and for PH2 O ≤ 1 kPa, three main H2Oads species are formed (associated with a minor amount of dissociated H2O species) on the two TiO2 solids. The species are identified by the positions of their IR bands in the 3750-3000 cm^-1 range. Considering the decreasing order of stability, they are (a) coordinated to strong (L2) and weak (L1) Lewis sites and denoted H2O ads-L2 and H2Oads-L1, respectively, and (b) hydrogen bonded to the H2Oads-L species and on O^2-/OH sites of the solids (denoted H2Owads). The three species have a common well-defined δH2O IR band at a position in the range 1640-1610 cm^-1 according to the total coverage of the surface. According to the AEIR method, the evolution of the intensity of this IR band during the increase in the adsorption temperature Ta in isobaric condition provides the evolution of the average coverage of the three species and then to their individual heats of adsorption as a function of their coverage. It is shown that there are no significant differences on the two TiO2 solids. In particular, the heat of adsorption of the H2Oads-L2 species varies from �

Synthesis, crystal structure and magnetic properties of [Cu(mal(abpt(H2O].3/2H2O and [Cu2(sq(abpt 2].2H2O (mal = malonate, sq = squarate, abpt = 4-amino-3,5-di-2-pyridyl-4H-1,2,4 triazole

Directory of Open Access Journals (Sweden)

Eno A. Ededet

2011-04-01

Full Text Available Two new mixed-ligand complexes of formula [Cu(mal(abpt(H2O].3/2H2O (1 and [Cu2(sq(abpt2].2H2O (2 [mal = malonate, abpt = 4-amino-3,5-di-2-pyridyl-4H-1,2,4 triazole and sq = squarate], have been prepared and characterized by X-ray crystal structure determination and magnetic studies. Complex 1 crystallizes in the monoclinic system, space group C2/c, with a = 14.0086(2 Å, b = 10.0980(2 Å, c = 25.630(4 Å; β = 97.5900(10 o, and Z = 8. Complex 2 crystallizes in the triclinic system, space group P-1 with a = 7.5696(15 Å, b = 8.4697(17 Å, c = 11.049(2 Å; β = 93.00(3o, α = 96.98(3, γ = 90.111(3 and Z = 1. Complex 1 consist of a neutral mononuclear [Cu(mal(abpt(H2O] unit and water molecule of crystallization in a distorted square pyramidal coordination sphere, while complex 2 is viewed as being made up of [Cu(sq(abpt2] units with the squarato ligand bridging the two copper(II cations. Variable temperature magnetic behaviour of the complexes reveals the existence of weak antiferromagnetic interaction for complex 1 and weak ferromagnetic intrachain interaction for complex 2.

Observations of interstellar H2O emission at 183 Gigahertz

International Nuclear Information System (INIS)

Waters, J.W.; Gustincic, J.J.; Kakar, R.K.; Kuiper, T.B.H.; Roscoe, H.K.; Swanson, P.N.; Rodriguez Kuiper, E.N.; Kerr, A.R.; Thaddeus, P.

1980-01-01

Line emission at 183 GHz by the 3 13 --2 20 rotational transition of water vapor has been detected from the Orion Nebula with the NASA Kuiper Airborne Observatory 91 cm telescope. The peak antenna temperature of the line is 15 K, its LSR velocity is 8 km s -1 , and its width is 15 km s -1 . The velocity profile has characteristics similar to those for CO:a narrow (approx.4 km s -1 ) ''spike'' centered at 9.5 km s -1 and a broad ''plateau'' with flaring wings centered at approx.8 km s -1 . Our 7'.5 antenna beam did not resolve the source. The 183 GHz H 2 O plateau emission appears enhanced above that expected for thermal excitation if it originates from the no greater than 1' region characteristic of plateau emission from all other observed molecules. The spike emission is consistent with an optically thick source of the approximated size of the well-known molecular ridge in Orion having the H 2 O in thermal equilibrium at Tapprox. =50 K. If this is the case, then the H 2 O column density giving rise to the spike is N/sub H/2/sub O/> or =3 x 10 17 cm -2 . An excitation calculation implies N/sub H/2/sub O/approx. =10 18 cm -2 for a source the size of the molecular ridge. These results imply that H 2 O is one of the more abundant species in the Orion Molecualr Cloud.H 2 O emission at 183 GHz was not detected in Sgr A, Sgr B2, W3, W43, W49, W51, DR 21, NGC 1333, NGC 7027, GL 2591, or the rho Oph cloud; it may have been detected in M17

Monte Carlo analysis of Pu-H2O and UO2-PuO2-H2O critical assemblies with ENDF/B-IV data

International Nuclear Information System (INIS)

Hardy, J. Jr.; Ullo, J.J.

1981-04-01

A set of critical experiments, comprising thirteen homogeneous Pu-H 2 O assemblies and twelve UO 2 -PuO 2 lattices, was analyzed with ENDF/B-IV data and the RCPO1 Monte Carlo program, which modeled the experiments explicitly. Some major data sensitivities were also evaluated. For the Pu-H 2 O assemblies, calculated K/sub eff/ averaged 1.011. The large (2.7%) scatter of K/sub eff/ values for these assemblies was attributed mostly to uncertainties in physical specifications since no clear trends of K/sub eff/ were evident and data sensitivities were insignificant. The UO 2 -PuO 2 lattices showed just one trend of K/sub eff/, which indicated an overprediction of U238 capture consistent with that observed for uranium-H 2 O experiments. There was however a approx. 1% discrepancy in calculated K/sub eff/ between the two sets of UO 2 -PuO 2 lattices studied

[Mechanism and performance of styrene oxidation by O3/H2O2].

Science.gov (United States)

He, Jue-Cong; Huang, Qian-Ru; Ye, Qi-Hong; Luo, Yu-Wei; Zhang, Zai-Li; Fan, Qing-Juan; Wei, Zai-Shan

2013-10-01

It can produce a large number of free radicals in O3/H2O2, system, ozone and free radical coupling oxidation can improve the styrene removal efficiency. Styrene oxidation by O3/H2O2 was investigated. Ozone dosage, residence time, H2o2 volume fraction, spray density and molar ratio of O3/C8H8 on styrene removal were evaluated. The experimental results showed that styrene removal efficiency achieved 85.7%. The optimal residence time, H2O2, volume fraction, spray density and O3/C8H8 molar ratio were 20. 6 s, 10% , 1.72 m3.(m2.h)-1 and 0.46, respectively. The gas-phase degradation intermediate products were benzaldehyde(C6H5CHO) and benzoic acid (C6H5 COOH) , which were identified by means of gas chromatography-mass spectrometry(GC-MS). The degradation mechanism of styrene is presented.

LiOH - H2O2 - H2O trinary system study for the selection of optimal conditions of lithium peroxide synthesis

International Nuclear Information System (INIS)

Nefedov, R A; Ferapontov, Yu A; Kozlova, N P

2016-01-01

Using solubility method the decay kinetics of peroxide products contained in liquid phase of LiOH - H 2 O 2 - H 2 O trinary system with 2 to 6% by wt hydrogen peroxide content in liquid phase in 21 to 33 °C temperature range has been studied. Conducted studies have allowed to determine temperature and concentration limits of solid phase existence of Li 2 O 2 ·H 2 O content, distinctness of which has been confirmed using chemical and qualitative X- ray phase analysis. Stabilizing effect of solid phase of Li 2 O 2 ·H 2 O content on hydrogen peroxide decay contained in liquid phase of LiOH - H 2 O 2 - H 2 O trinary system under conditions of experiments conducted has been shown. (paper)

LiOH - H2O2 - H2O trinary system study for the selection of optimal conditions of lithium peroxide synthesis

Science.gov (United States)

Nefedov, R. A.; Ferapontov, Yu A.; Kozlova, N. P.

2016-01-01

Using solubility method the decay kinetics of peroxide products contained in liquid phase of LiOH - H2O2 - H2O trinary system with 2 to 6% by wt hydrogen peroxide content in liquid phase in 21 to 33 °C temperature range has been studied. Conducted studies have allowed to determine temperature and concentration limits of solid phase existence of Li2O2·H2O content, distinctness of which has been confirmed using chemical and qualitative X- ray phase analysis. Stabilizing effect of solid phase of Li2O2·H2O content on hydrogen peroxide decay contained in liquid phase of LiOH - H2O2 - H2O trinary system under conditions of experiments conducted has been shown.

Improved radiosensitive microcapsules using H2O2

International Nuclear Information System (INIS)

Harada, Satoshi; Ehara, Shigeru; Ishii, Keizo

2010-01-01

The radiation-induced releasing of the liquid-core of the microcapsules was improved using H 2 O 2 , which produced O 2 generation of H 2 O 2 after irradiation. Further, we tested whether these microcapsules enhanced the antitumor effects and decreased the adverse effects in vivo in C3He/J mice. The capsules were produced by spraying a mixture of 3.0% hyaluronic acid, 2.0% alginate, 3.0% H 2 O 2 , and 0.3 mmol of carboplatin on a mixture of 0.3 mol FeCl 2 and 0.15 mol CaCl 2 . The microcapsules were subcutaneously injected into MM46 tumors that had been inoculated in the left hind legs of C3He/J mice. The radiotherapy comprised tumor irradiation with 10 Gy or 20 Gy 60 Co. The antitumor effect of the microcapsules was tested by measuring tumor size and monitoring tumor growth. Three types of adverse effects were considered: fuzzy hair, loss of body weight, and death. The size of the capsule size was 23±2.4 μmφ and that of the liquid core, 20.2±2.2 μmφ. The injected microcapsules localized drugs around the tumor. The production of O 2 by radiation increased the release of carboplatin from the microcapsules. The antitumor effects of radiation, carboplatin, and released oxygen were synergistic. Localization of the carboplatin decreased its adverse effects. However, the H 2 O 2 caused ulceration of the skin in the treated area. The use of our microcapsules enhanced the antitumor effects and decreased the adverse effects of carboplatin. However, the skin-ulceration caused by H 2 O 2 must be considered before these microcapsules can be used clinically. (author)

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...

Study of UO{sub 2}F{sub 2} - H{sub 2}O - HF compounds; Etude des composes UO{sub 2}F{sub 2} - H{sub 2}O - HF

Energy Technology Data Exchange (ETDEWEB)

Neveu, G [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1961-07-01

We study various compounds resulting from the interaction of UO{sub 2}F{sub 2} with H{sub 2}O and HF (gas), and various triple compounds UO{sub 2}F{sub 2} - H{sub 2}O - HF; the conditions of decomposition and the thermodynamic limits of stability are specified. (author) [French] Nous etudions divers composes formes par reaction de UO{sub 2}F{sub 2} avec H{sub 2}O et HF (gaz) et divers composes triples UO{sub 2}F{sub 2} - H{sub 2}O - HF, en essayant de preciser les decompositions et domaines d'exisfence thermodynamiques de ces corps. (auteur)

IR and Raman spectra of LaH(SeO3)2 and FeH(SeO3)2

International Nuclear Information System (INIS)

Ratheesh, R.; Suresh, G.; Nayar, V.U.; Morris, R.E.

1995-01-01

The infrared and Raman spectra of LaH(SeO 3 ) 2 and FeH(SeO 3 ) 2 crystals are recorded and analysed. Bands confirm the coexistence of HSeO 3 - and SeO 3 2- ions in both LaH(SeO 3 ) 2 and FeH(SeO 3 ) 2 crystals. The Se-OH stretching vibrations are observed to be at lower wavenumbers in LaH(SeO 3 ) 2 than that in the iron compound in agreement with the short O-O distance in the former. Observed bands indicate that the SeO 3 2- ions are more angularly distorted in FeH(SeO 3 ) 2 crystal. ABC bands, characteristic of strong hydrogen bonded systems are observed in the infrared spectra of both the crystals. (author). 15 refs., 2 figs., 1 tab

Application of UV/TiO2/H2O2 Advanced Oxidation to Remove Naphthalene from Water

Directory of Open Access Journals (Sweden)

Behroz Karimi

2016-11-01

Full Text Available Naphthalene is released into the environment by burning such organic materials as fossil fuels and wood and in industrial and vehicle exhaust emissions. Naphthalene is used in the manufacture of plastics, resins, fuels, and dyes. The aim of this study was to evaluate the performance of UV/TiO2/H2O2 process to decompose naphthalene in aqueous solutions. For this purpose, the photocatalytic degradation of naphthalene was investigated under UV light irradiation in the presence of TiO2 and H2O2 under a variety of conditions. Photodegradation efficiencies of H2O2/UV, TiO2/UV, and H2O2/TiO2/UV processes were compared in a batch reactor using the low pressure mercury lamp irradiation. The effects of operating parameters such as reaction time (min; solution pH; and initial naphthalene, TiO2, and H2O2 concentrations on photodegradation were examined. In the UV/TiO2/H2O2 system with a naphthalene concentration of 15 mg/L, naphthalene removal efficiencies of 63, 75, 80, 88, 92, 95, 96.5, and 98% were achieved, respectively, for reaction times of 5, 10, 20, 30, 40, 50, 60, 100 and 120 min. This is while removal efficienciesof 50, 59.5, 69, 80, 85, 88, 91, and 95% were obtained in the UV/TiO2 system under the same conditions. For initial pH values of 3, 4, 5, 6, 7,9, 10, and 12, naphthalene removal efficiencies of approximately 96.8, 85.5, 86, 75.5, 68.8, 57.8, and 52.5% were acheived, respectively, with the UV/TiO2/H2O2 system. Thus, it may be claiomed that, compared to either H2O2/UV or TiO2/UV process, the H2O2/TiO2/UV process yielded a far more efficient photodegradation.

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.

Magnetism of CuCl{sub 2}·2D{sub 2}O and CuCl{sub 2}·2H{sub 2}O, and of CuBr{sub 2}·6H{sub 2}O

Energy Technology Data Exchange (ETDEWEB)

DeFotis, G.C., E-mail: gxdefo@wm.edu [Department of Chemistry, College of William and Mary, Williamsburg, VA 23187 (United States); Hampton, A.S.; Van Dongen, M.J.; Komatsu, C.H.; Benday, N.S.; Davis, C.M. [Department of Chemistry, College of William and Mary, Williamsburg, VA 23187 (United States); Hays, K.; Wagner, M.J. [Department of Chemistry, George Washington University, Washington, D.C. 20052 (United States)

2017-07-15

Highlights: • CuCl{sub 2}·2D{sub 2}O is examined magnetically and compared with CuCl{sub 2}·2H{sub 2}O. • Slightly lower magnetic characteristic temperatures occur for deuterated dihydrate. • The new compound CuBr{sub 2}·6H{sub 2}O is examined magnetically. • Unexpected relationships appears between magnetic behaviors of CuBr{sub 2}·6H{sub 2}O and CuBr{sub 2}. • Two alternative monoclinic unit cells can account for diffraction data on CuBr{sub 2}·6H{sub 2}O. - Abstract: The magnetic properties of little examined CuCl{sub 2}·2D{sub 2}O are studied and compared with those of CuCl{sub 2}·2H{sub 2}O. New CuBr{sub 2}·6H{sub 2}O is also examined. Susceptibility maxima appear for chlorides at 5.35 and 5.50 K, in the above order, with estimated antiferromagnetic ordering at 4.15 and 4.25 K. Curie-Weiss fits yield g of 2.210 and 2.205, and Weiss θ of −6.0 and −4.7 K, respectively, in χ{sub M} = C/(T − θ). One-dimensional Heisenberg model fits to susceptibilities, including interchain exchange in a mean-field approximation, are performed. Interchain exchange is significant but much weaker than intrachain. The bromide hexahydrate strongly differs magnetically from any chloride hydrate, but exhibits notable similarities and differences compared to previously studied CuBr{sub 2}. A broad susceptibility maximum occurs near 218 K, only 4% lower than for CuBr{sub 2}, but with almost twice the magnitude. Powder X-ray diffraction data for CuBr{sub 2}·6H{sub 2}O may be best accounted for by a monoclinic unit cell that is metrically orthorhombic. The volume per formula unit is consistent with trends in metal ionic radii. However, an alternative monoclinic cell with 5% smaller volume more readily rationalizes the magnetism.

Vibrational and thermodynamic properties of Ar, N2, O2, H2 and CO adsorbed and condensed into (H,Na)-Y zeolite cages as studied by variable temperature IR spectroscopy.

Science.gov (United States)

Gribov, Evgueni N; Cocina, Donato; Spoto, Giuseppe; Bordiga, Silvia; Ricchiardi, Gabriele; Zecchina, Adriano

2006-03-14

The adsorption of Ar, H2, O2, N2 and CO on (H,Na)-Y zeolite (Si/Al = 2.9, H+/Na+ approximately 5) has been studied at variable-temperature (90-20 K) and sub-atmospheric pressure (0-40 mbar) by FTIR spectroscopy. Unprecedented filling conditions of the zeolite cavities were attained, which allowed the investigation of very weakly adsorbed species and of condensed, liquid-like or solid-like, phases. Two pressure regimes were singled out, characterized by: (i) specific interaction at low pressure of the probe molecules (P) with the internal Brønsted and Lewis sites, and (ii) multilayer adsorption at higher pressure. In the case of CO the perturbation of the protonic sites located inside the sodalite cages was also observed. As the molecule is too large to penetrate the sodalite cage, the perturbation is thought to involve a proton jump tunneling mechanism. The adsorption energy for the (HF)OH...P (P = Ar, H2, O2, N2 and CO) specific interaction involving the high frequency Brønsted acid sites exposed in the supercages was derived following the VTIR (variable temperature infrared spectroscopy) method described by E. Garrone and C. Otero Areán (Chem. Soc. Rev., 2005, 34, 846).

Synthesis, structural characterization, and dehydration analysis of uranyl zinc mellitate, (UO{sub 2})Zn(H{sub 2}O){sub 4}(H{sub 2}mel).2H{sub 2}O

Energy Technology Data Exchange (ETDEWEB)

Olchowka, Jakub; Volkringer, Christophe; Henry, Natacha; Loiseau, Thierry [Unite de Catalyse et Chimie du Solide (UCCS) - UMR CNRS 8181, Universite de Lille Nord de France, USTL-ENSCL, Villeneuve d' Ascq (France)

2013-04-15

A new heterometallic uranyl zinc carboxylate, (UO{sub 2})Zn(H{sub 2}O){sub 4}(H{sub 2}mel).2H{sub 2}O, has been hydrothermally prepared (150 C, 24 h) by using 1,2,3,4,5,6-benzenehexacarboxylic acid (mellitic acid) as organic linker in order to form a three-dimensional network. Four of the six carboxylate groups of the mellitate ligand interact with mononuclear uranyl or zinc cations, which are eightfold (hexagonal bipyramid, UO{sub 8}) or sixfold [octahedron, ZnO{sub 2}(H{sub 2}O){sub 4}] coordinated, respectively. The remaining free carboxylate arms of the mellitate species preferentially interact through hydrogen bonds with water molecules trapped within the framework. Thermogravimetric and X-ray thermodiffraction (up to 800 C) analyses and in situ infrared spectroscopy (up to 210 C) indicated that both free and bound water species are evacuated from the structure in one step between 80 and 170 C, followed by its transformation into an unknown, anhydrous, poorly crystalline phase [UO{sub 2}Zn(mel)] up to 320 C. After the formation of an amorphous phase, the re-crystallization of oxides α-ZnU{sub 3}O{sub 10} and ZnO was observed from 460 C. The fluorescence spectrum of the as-synthesized uranyl zinc mellitate shows the six bands that are typical for vibronic couplings of the [O=U=O]{sup 2+} moiety. (Copyright copyright 2013 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Complexation in the system K2SeO4-UO2SeO4-H2O

International Nuclear Information System (INIS)

Serezhkina, L.B.; Kuchumova, N.V.; Serezhkin, V.N.

1994-01-01

Complexation in the system K 2 SeO 4 -UO 2 SeO 4 -H 2 O at 25 degrees C is studied by isothermal solubility. Congruently soluble K 2 UO 2 (SeO 4 ) 2 ·4H 2 O (I) and incongruently soluble K 2 (UO 2 ) 2 (SeO 4 ) 3 ·6H 2 O (II) are observed. The unit-cell constants of I and II are determined from an X-ray diffraction investigation. For I, a = 12,969, b = 11.588, c = 8.533 angstrom, Z = 4, space group Pmmb. For II, a = 23.36, b = 6.784, c = 13.699 angstrom, β = 104.42 degrees, Z = 4, space group P2/m, P2, or Pm. Complexes I and II are representatives of the crystal-chemical groups AB 2 2 M 1 and A 2 T 3 3 M 1 , respectively, of uranyl complexes

Profiling of cytosolic and mitochondrial H2O2 production using the H2O2-sensitive protein HyPer in LPS-induced microglia cells.

Science.gov (United States)

Park, Junghyung; Lee, Seunghoon; Lee, Hyun-Shik; Lee, Sang-Rae; Lee, Dong-Seok

2017-07-27

Dysregulation of the production of pro-inflammatory mediators in microglia exacerbates the pathologic process of neurodegenerative disease. ROS actively affect microglia activation by regulating transcription factors that control the expression of pro-inflammatory genes. However, accurate information regarding the function of ROS in different subcellular organelles has not yet been established. Here, we analyzed the pattern of cytosolic and mitochondrial H 2 O 2 formation in LPS-activated BV-2 microglia using the H 2 O 2- sensitive protein HyPer targeted to specific subcellular compartments. Our results show that from an early time, cytosolic H 2 O 2 started increasing constantly, whereas mitochondrial H 2 O 2 rapidly increased later. In addition, we found that MAPK affected cytosolic H 2 O 2 , but not mitochondrial H 2 O 2 . Consequently, our study provides the basic information about subcellular H 2 O 2 generation in activated microglia, and a useful tool for investigating molecular targets that can modulate neuroinflammatory responses. Copyright © 2017 Elsevier B.V. All rights reserved.

Syntheses, crystal structures, and properties of the isotypic pair [Cr(H{sub 2}O){sub 6}]{sub 2}[B{sub 12}H{sub 12}]{sub 3}.15H{sub 2}O and [In(H{sub 2}O){sub 6}]{sub 2}[B{sub 12}H{sub 12}]{sub 3}.15H{sub 2}O

Energy Technology Data Exchange (ETDEWEB)

Van, Nguyen-Duc; Kleeberg, Fabian M.; Schleid, Thomas [Institut fuer Anorganische Chemie, Universitaet Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart (Germany)

2015-11-15

Single crystals of [Cr(H{sub 2}O){sub 6}]{sub 2}[B{sub 12}H{sub 12}]{sub 3}.15H{sub 2}O and [In(H{sub 2}O){sub 6}]{sub 2}[B{sub 12}H{sub 12}]{sub 3}.15H{sub 2}O were obtained by reactions of aqueous solutions of the acid (H{sub 3}O){sub 2}[B{sub 12}H{sub 12}] with chromium(III) hydroxide and indium metal shot, respectively. The title compounds crystallize isotypically in the trigonal system with space group R anti 3c (a = 1157.62(3), c = 6730.48(9) pm for the chromium, a = 1171.71(3), c = 6740.04(9) pm for the indium compound, Z = 6). The arrangement of the quasi-icosahedral [B{sub 12}H{sub 12}]{sup 2-} dianions can be considered as stacking of two times nine layers with the sequence..ABCCABBCA.. and the metal trications arrange in a cubic closest packed..abc.. stacking sequence. The metal trications are octahedrally coordinated by six water molecules of hydration, while another fifteen H{sub 2}O molecules fill up the structures as zeolitic crystal water or second-sphere hydrating species. Between these free and the metal-bonded water molecules, bridging hydrogen bonds are found. Furthermore, there is also evidence of hydrogen bonding between the anionic [B{sub 12}H{sub 12}]{sup 2-} clusters and the free zeolitic water molecules according to B-H{sup δ-}..{sup δ+}H-O interactions. Vibrational spectroscopy studies prove the presence of these hydrogen bonds and also show slight distortions of the dodecahydro-closo-dodecaborate anions from their ideal icosahedral symmetry (I{sub h}). Thermal decomposition studies for the example of [Cr(H{sub 2}O){sub 6}]{sub 2}[B{sub 12}H{sub 12}]{sub 3}.15H{sub 2}O gave no hints for just a simple multi-stepwise dehydration process. (Copyright copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Decolorization and Mineralization of Reactive Dyes, by the H2O2/UV Process With Electrochemically Produced H2O2

NARCIS (Netherlands)

Jeric, T.; Bisselink, R.J.M.; Tongeren, W. van; Marechal. A.M. Le

2013-01-01

Decolorization of Reactive Red 238, Reactive Orange 16, Reactive Black 5 and Reactive Blue 4 was studied in the UV/H2O2 process with H2O2 being produced electrochemically. The experimental results show that decolorization increased considerably when switching on the electrochemical production of

I + (H2O)2 → HI + (H2O)OH Forward and Reverse Reactions. CCSD(T) Studies Including Spin-Orbit Coupling.

Science.gov (United States)

Wang, Hui; Li, Guoliang; Li, Qian-Shu; Xie, Yaoming; Schaefer, Henry F

2016-03-03

The potential energy profile for the atomic iodine plus water dimer reaction I + (H2O)2 → HI + (H2O)OH has been explored using the "Gold Standard" CCSD(T) method with quadruple-ζ correlation-consistent basis sets. The corresponding information for the reverse reaction HI + (H2O)OH → I + (H2O)2 is also derived. Both zero-point vibrational energies (ZPVEs) and spin-orbit (SO) coupling are considered, and these notably alter the classical energetics. On the basis of the CCSD(T)/cc-pVQZ-PP results, including ZPVE and SO coupling, the forward reaction is found to be endothermic by 47.4 kcal/mol, implying a significant exothermicity for the reverse reaction. The entrance complex I···(H2O)2 is bound by 1.8 kcal/mol, and this dissociation energy is significantly affected by SO coupling. The reaction barrier lies 45.1 kcal/mol higher than the reactants. The exit complex HI···(H2O)OH is bound by 3.0 kcal/mol relative to the asymptotic limit. At every level of theory, the reverse reaction HI + (H2O)OH → I + (H2O)2 proceeds without a barrier. Compared with the analogous water monomer reaction I + H2O → HI + OH, the additional water molecule reduces the relative energies of the entrance stationary point, transition state, and exit complex by 3-5 kcal/mol. The I + (H2O)2 reaction is related to the valence isoelectronic bromine and chlorine reactions but is distinctly different from the F + (H2O)2 system.

Ground and excited states of the [Fe(H2O)6]2+ and [Fe(H2O)6]3+ clusters: Insight into the electronic structure of the [Fe(H2O)6]2+ – [Fe(H2O)6]3+ complex

Energy Technology Data Exchange (ETDEWEB)

Miliordos, Evangelos; Xantheas, Sotiris S.

2015-04-14

We report the ground and low lying electronically excited states of the [Fe(H2O)6]2+ and [Fe(H2O)6]3+ clusters using multi-configuration electronic structure theory. In particular, we have constructed the Potential Energy Curves (PECs) with respect to the iron-oxygen distance when removing all water ligands at the same time from the cluster minima and established their correlation to the long range dissociation channels. Due to the fact that both the second and third ionization potentials of iron are larger than the one for water, the ground state products asymptotically correlate with dissociation channels that are repulsive in nature at large separations as they contain at least one H2O+ fragment and a positive metal center. The most stable equilibrium structures emanate – via intersections and/or avoided crossings – from the channels consisting of the lowest electronic states of Fe2+(5D; 3d6) or Fe3+(6S; 3d5) and six neutral water molecules. Upon hydration, the ground state of Fe2+(H2O)6 is a triply (5Tg) degenerate one with the doubly (5Eg) degenerate state lying slightly higher in energy. Similarly, Fe3+(H2O)6 has a ground state of 6Ag symmetry under Th symmetry. We furthermore examine a multitude of electronically excited states of many possible spin multiplicities, and report the optimized geometries for several selected states. The PECs for those cases are characterized by a high density of states. Focusing on the ground and the first few excited states of the [Fe(H2O)6]2+ and [Fe(H2O)6]3+ clusters, we studied their mutual interaction in the gas phase. We obtained the optimal geometries of the Fe2+(H2O)6 – Fe3+(H2O)6 gas phase complex for different Fe–Fe distances. For distances shorter than 6.0 Å, the water molecules in the respective first solvation shells located between the two metal centers were found to interact via weak hydrogen bonds. We examined a total of ten electronic states for this complex, including those corresponding to the

SIMULTANEOUS OBSERVATIONS OF SiO AND H{sub 2}O MASERS TOWARD KNOWN STELLAR H{sub 2}O MASER SOURCES

Energy Technology Data Exchange (ETDEWEB)

Kim, Jaeheon [Yonsei University Observatory, Seongsan-ro 262, Seodaemun, Seoul 120-749 (Korea, Republic of); Cho, Se-Hyung [Korean VLBI Network Yonsei Radio Astronomy Observatory, Yonsei University, Seongsan-ro 262, Seodaemun, Seoul 120-749 (Korea, Republic of); Kim, Sang Joon, E-mail: jhkim@kasi.re.kr, E-mail: cho@kasi.re.kr, E-mail: sjkim1@khu.ac.kr [Department of Astronomy and Space Science, Kyung Hee University, Seocheon-Dong, Giheung-Gu, Yongin, Gyeonggi-Do 446-701 (Korea, Republic of)

2013-01-01

We present the results of simultaneous observations of SiO v = 1, 2, {sup 29}SiO v = 0, J = 1-0, and H{sub 2}O 6{sub 16}-5{sub 23} maser lines toward 152 known stellar H{sub 2}O maser sources using the Yonsei 21 m radio telescope of the Korean VLBI Network from 2009 June to 2011 January. Both SiO and H{sub 2}O masers were detected from 62 sources with a detection rate of 40.8%. The SiO-only maser emission without H{sub 2}O maser detection was detected from 27 sources, while the H{sub 2}O-only maser without SiO maser detection was detected from 22 sources. Therefore, the overall SiO maser emission was detected from 89 sources, resulting in a detection rate of 58.6%. We have identified 70 new detections of the SiO maser emission. For both H{sub 2}O and SiO maser detected sources, the peak and integrated antenna temperatures of SiO masers are stronger than those of H{sub 2}O masers in both Mira variables and OH/IR stars and the relative intensity ratios of H{sub 2}O to SiO masers in OH/IR stars are larger than those in Mira variables. In addition, distributions of 152 observed sources were investigated in the IRAS two-color diagram.

A novel H2S/H2O2 fuel cell operating at the room temperature

Energy Technology Data Exchange (ETDEWEB)

Sanli, Ayse Elif [Gazi University (Turkey)], email: aecsanli@gmail.com; Aytac, Aylin [Department of Chemistry, Faculty of Science, Gazi University, Teknikokullar (Turkey)], email: aytaca@gazi.edu.tr

2011-07-01

This study concerns the oxidation mechanism of hydrogen sulfide and a fuel cell; acidic peroxide is used as the oxidant and basic hydrogen sulfide is the fuel. A solid state H2S/H2O2 stable fuel cell was produced at room temperature. A cell potential of 0.85 V was reached; this is quite remarkable in comparison to the H2S/O2 fuel cell potential of 0.85 V obtained at 850-1000 degree celsius. The hydrogen sulfide goes through an oxidation reaction in the alkaline fuel cell (H2S/H2O2 fuel cell) which opens up the possibility of using the cheaper nickel as a catalyst. As a result, the fuel cell becomes a potentially low cost technology. A further benefit from using H2S as the alkaline liquid H2S/H2O2 fuel cell, is that sulfide ions are oxidized at the anode, releasing electrons. Sulfur produced reacts with the other sulfide ions and forms disulfide and polysulfide ions in basic electrolytes (such as Black Sea water).

Synthesis and crystal structure of trans-[Ni(pyzdcH)M 2 (H 2 O) 2 ...

African Journals Online (AJOL)

The determined structure of the title compound C24H20Ni2N8O20 consists of the mononuclear trans-[Ni(pyzdc)2(H2O)2], (pyzdc = pyrazine-2,3- dicarboxylate). The Ni(II) atom is hexa-coordinated by two (pyzdcH)- groups and two water molecules. The coordinated water molecules are in trans-diaxial positions and the ...

Direct Synthesis of H2O2 over Ti-Containing Molecular Sieves Supported Gold Catalysts: A Comparative Study for In-situ-H2O2-ODS of Fuel

International Nuclear Information System (INIS)

Zhang, Han; Song, Haiyan; Chen, Chunxia; Han, Fuqin; Hu, Shaozheng; Liu, Guangliang; Chen, Ping; Zhao, Zhixi

2013-01-01

Direct synthesis of H 2 O 2 and in situ oxidative desulfurization of model fuel over Au/Ti-HMS and Au/TS-1 catalysts has been comparatively investigated in water or methanol. Maximum amount (82%) of active Au 0 species for H 2 O 2 synthesis was obtained. Au/Ti-HMS and Au/TS-1 exhibited the contrary performances in H 2 O 2 synthesis as CH 3 OH/H 2 O ratio of solvent changed. H 2 O 2 decomposition and hydrogenation in water was inhibited by the introduction of methanol. Effect of O 2 /H 2 ratio on H 2 O 2 concentration, H 2 conversion and H 2 O 2 selectivity revealed a relationship between H 2 O 2 generation and H2 consumption. The highest dibenzothiophene removal rate (83.2%) was obtained over Au/Ti-HMS in methanol at 1.5 of O 2 /H 2 ratio and 60 .deg. C. But removal of thiophene over Au/TS-1 should be performed in water without heating to obtain a high removal rate (61.3%). Meanwhile, H 2 conversion and oxidative desulfurization selectivity of H 2 were presented

Electrochemical, H2O2-Boosted Catalytic Oxidation System

Science.gov (United States)

Akse, James R.; Thompson, John O.; Schussel, Leonard J.

2004-01-01

An improved water-sterilizing aqueous-phase catalytic oxidation system (APCOS) is based partly on the electrochemical generation of hydrogen peroxide (H2O2). This H2O2-boosted system offers significant improvements over prior dissolved-oxygen water-sterilizing systems in the way in which it increases oxidation capabilities, supplies H2O2 when needed, reduces the total organic carbon (TOC) content of treated water to a low level, consumes less energy than prior systems do, reduces the risk of contamination, and costs less to operate. This system was developed as a variant of part of an improved waste-management subsystem of the life-support system of a spacecraft. Going beyond its original intended purpose, it offers the advantage of being able to produce H2O2 on demand for surface sterilization and/or decontamination: this is a major advantage inasmuch as the benign byproducts of this H2O2 system, unlike those of systems that utilize other chemical sterilants, place no additional burden of containment control on other spacecraft air- or water-reclamation systems.

Synthesis and characterization of polymer eight-coordinate (enH 2)[Y III(pdta)(H 2O)] 2·10H 2O as well as the interaction of [Y III(pdta)(H 2O)] 22- with BSA

Science.gov (United States)

Liu, Bin; Wang, Jun; Wang, Xin; Liu, Bing-Mi; He, Ling-Ling; Xu, Shu-Kun

2010-12-01

The eight-coordinate (enH 2)[Y III(pdta)(H 2O)] 2·10H 2O (en = ethylenediamine and H 4pdta = 1,3-propylenediamine- N, N, N', N'-tetraacetic acid) was synthesized, meanwhile its molecular and crystal structures were determined by single-crystal X-ray diffraction technology. The interaction between [Y III(pdta)(H 2O)] 22- and bovine serum albumin (BSA) was investigated by UV-vis and fluorescence spectra. The results indicate that [Y III(pdta)(H 2O)] 22- quenched effectively the intrinsic fluorescence of BSA via a static quenching process with the binding constant ( Ka) of the order of 10 4. Meanwhile, the binding and damaging sites to BSA molecules were also estimated by synchronous fluorescence. Results indicate that the hydrophobic environments around Trp and Tyr residues were all slightly changed. The thermodynamic parameters (Δ G = -25.20 kJ mol -1, Δ H = -26.57 kJ mol -1 and Δ S = -4.58 J mol -1 K -1) showed that the reaction was spontaneous and exothermic. What is more, both Δ H and Δ S were negative values indicated that hydrogen bond and Van der Waals forces were the predominant intermolecular forces between [Y III(pdta)(H 2O)] 22- and BSA.

Unfolding the Quantum Nature of Proton Bound Symmetric Dimers of (MeOH)2H+ and (Me2O)2H+: a Theoretical Study

Science.gov (United States)

Tan, Jake Acedera; Kuo, Jer-Lai

2014-06-01

A proton under a tug of war between two competing Lewis bases is a common motif in biological systems and proton transfer processes. Over the past decades, model compounds for such motifs can be prepared by delicate stoichiometric control of salt solutions. Unfortunately, condensed phase studies, which aims to identify the key vibrational signatures are complicated to analyze. As a result, gas-phase studies do provide promising insights on the behavior of the shared proton. This study attempts to understand the quantum nature of the shared proton under theoretical paradigms. Proton bound symmetric dimers of (MeOH)2H+ and (Me2O)2H+ are chosen as the model compounds. The simulation is performed using Density Functional Theory (DFT) at the B3LYP level with 6-311+G(d,p) as the basis set. It was found out that stretching mode of shared proton couples with several other normal modes and its corresponding oscillator strength do distribute to other normal modes. J.R. Roscioli, L.R. McCunn and M.A. Johnson. Science 2007, 316, 249 T.E. DeCoursey. Physiol. Rev., 2003, 83, 475 E.S. Stoyanov. Psys. Chem. Phys., 2000,2,1137

Structure of Chloro bis(1,10-phenanthroline)Cobalt(II) Complex, [Co(phen)2(Cl)(H2O)]Cl · 2H2O

International Nuclear Information System (INIS)

Zhao, Pu Su; Lu, Lu De; Jian, Fang Fang

2003-01-01

The crystal structure of [Co(phen) 2 (Cl)(H 2 O)] Cl · 2H 2 O(phen=1,10-phenanthroline) has been determined by X-ray crystallography. It crystallizes in the triclinic system, space group P 1 , with lattice parameters a=9.662(2), b=11.445(1), c=13.037(2)A, α=64.02(1), β=86.364(9), γ=78.58(2) .deg., and Z=2. The coordinated cations contain a six-coordinated cobalt atom chelated by two phen ligands and one chloride anion and one water ligand in cis arrangement. In addition to the chloride coordinated to the cobalt, there are one chloride ion and four water molecules which complete the crystal structure. In the solid state, the title compound forms three dimensional network structure through hydrogen bonds, within which exists the strongest hydrogen bond (O(3)-O(4)=2.33A). The intermolecular hydrogen bonds connect the [Co(phen) 2 (Cl)(H 2 O)] 1+ , H 2 O moieties and chloride ion

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)

A green chemoselective one-pot protocol for expeditious synthesis of symmetric pyranodipyrimidine derivatives using ZrOCl2.8H2O

Directory of Open Access Journals (Sweden)

Mehdi Rimaz

2016-09-01

Full Text Available A convenient, highly efficient and time economic method has been described for the chemo- and regioselective synthesis of 5-aryloyl-1,3,7,9-tetraalkyl-2,8-dithioxo-2,3,8,9-tetrahydro-1H-pyrano[2,3-d:6,5-dˊ]dipyrimidine-4,6(5H,7H-diones derivatives by one-pot two-component reaction of 1,3-diethyl-2-thiobarbituric acid or 1,3-dimethyl-2-thiobarbituric acid with substituted arylglyoxalmonohydrates using commercially available zirconium (IV oxydichloride octahydrate (ZrOCl2.8H2O as green Lewis acid catalyst. This method is associated with some attractive characteristics such as good selectivity, very short reaction time, high yield of products, cleaner reaction profile, no harmful by-product, cheap and environmental benign catalyst, simple experimental and work-up procedure. This procedure does not require solvent separation and purification steps such as column chromatography.

Stability of globular proteins in H2O and D2O

NARCIS (Netherlands)

Efimova, Y. M.; Haemers, S.; Wierczinski, B.; Norde, W.; van Well, A. A.

2007-01-01

In several experimental techniques D2O rather then H2O is often used as a solvent for proteins. Concerning the influence of the solvent on the stability of the proteins, contradicting results have been reported in literature. In this paper the influence of H2O-D2O solvent substitution on the

Application of H2O and UV/H2O2 processes for enhancing the biodegradability of reactive black 5 dye.

Science.gov (United States)

Kalpana, S Divya; Kalyanaraman, Chitra; Gandhi, N Nagendra

2011-07-01

Leather processing is a traditional activity in India during which many organic and inorganic chemicals are added while part of it is absorbed by the leather, the remaining chemicals are discharged along with the effluent. The effluent contains both easily biodegradable and not easily biodegradable synthetic organics like dyes, syntans. Easily biodegradable organics are removed in the existing biological treatment units whereas synthetic organics present in the wastewater are mostly adsorbed over the microbes. As the tannery effluent contains complex chemicals, it is difficult to ascertain the degradation of specific pollutants. To determine the increase in the biodegradability, one of the complex and synthetic organic chemical like dye used in the tanning operation was selected for Advanced Oxidation Process (AOPs) treatment for cleaving complex organics and its subsequent treatment in aerobic process. In the present study, Reactive Black 5 Dye used in the tanning operation was selected for Hydrogen Peroxide (H2O2) and UV/H2O2 pre-treatment for different operating conditions like pH, contact time and different volume of H2O2. A comparison was made between the untreated, Hydrogen Peroxide (H2O2) and UV/H2O2 treated effluent in order to ascertain the influence of AOP on the improvement of biodegradability of effluent. An increase in the BOD5/COD ratio from 0.21 to 0.435 was achieved in the UV/H2O2 pre-treatment process. This pre-treated effluent was further subjected to aerobic process. Biochemical Oxygen Demand (BOD5) and Chemical Oxygen Demand (COD) removal efficiency of the UV/H2O2 pre-treated dye solution in the aerobic process was found to be 86.39% and 77.82% when compared to 52.43% of BOD5 and 51.55% of COD removal efficiency without any pre-treatment. Hence from these results, to increase the biodegradability of Reactive Black 5 dye pre-treatment methods like H2O2 and UV/H2O2 can be used prior to biological treatment process.

Complexing in the system Rb2SeO4-UO2SeO4-H2O

International Nuclear Information System (INIS)

Kuchumova, N.V.; Shtokova, I.P.; Serezhkina, L.B.; Serezhkin, V.N.

1989-01-01

Method of isothermal solubility at 25 deg C is used to study interaction of rubidium and uranyl selenates in aqueous solution. Formation of congruently soluble Rb 2 UO 2 (SeO 4 ) 2 x2H 2 O and Rb 2 (UO 2 ) 2 x(SeO 4 ) 3 x6H 2 O is stated. For the last compound crystallographic characteristics (a=10.668; b=14.935(9); c=13.891(7) A; β=104.94(1); Z=4, sp.gr. P2 1 /c) are determined. Thermal decomposition of a compound results in formation of Rb 2 U 2 O 7

Neutron Spectra in H{sub 2}O, D{sub 2}O, BeO and CH{sub 2}; Spectres de Neutrons dans H{sub 2}O, D{sub 2}O, BeO et CH{sub 2}; Spektry nejtronov v H{sub 2}O, D{sub 2}O, BeO i CH{sub 2}; Espectros Neutronicos en H{sub 2}O, D{sub 2}O, BeO y CH{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Neill, J. M.; Young, J. C.; Trimble, G. D.; Beyster, J. R. [General Atomic Division of General Dynamics Corporation, John Jay Hopkins Laboratory for Pure and Applied Science, San Diego, CA (United States)

1965-08-15

Thermal neutron spectral measurements in moderators of interest to reactor technology are being made at General Atomic. The purpose of these measurements is to provide an integral check of the adequacy of proposed scattering models for these moderators. At present the scattering kernels are obtained by measuring the double differential scattering cross-sections directly, or by inferring them from a study of the vibrational and rotational motions of the molecules in a liquid or the lattice vibrational spectrum in a solid. The direct measurement has suffered from some experimental difficulties, such as obtaining the desired intensity and resolution and making the proper corrections for multiple scattering in the sample. From the standpoint of the application to reactor technology, the latter procedure for obtaining the scattering kernel has been more satisfactory in many instances. The integral measurements that have been made, coupled to comparative calculations of the neutron spectra, allow comment to be made on the status of the theoretical scattering models for H{sub 2}O, D{sub 2}O and BeO. In this paper, angular- and position-dependent spectra measured in H{sub 2}O and D{sub 2}O poisoned with boron or cadmium are presented and show improved agreement with the theoretical values. It appears that the Nelkin model for H{sub 2}O provides a reasonable first description for the scattering by that moderator. It also appears that the Honeck model for D{sub 2}O, an extension of the incoherent model for H{sub 2}O of Nelkin, is also an adequate description for some applications. This is surprising since deuterium, unlike hydrogen, is mostly a coherent scatterer; however it supports recent studies by Koppel which showed that the intramolecular and intermolecular interference scattering terms in D{sub 2}O tend to cancel. Measured angularly-dependent neutron spectra in BeO poisoned with borated stainless steel are also presented. In general the agreement of measurement with

Quasielastic neutron scattering and infra-red band contour study of H2O reorientations in [Ni(H2O)6] (ClO4)2

International Nuclear Information System (INIS)

Janik, J.A.; Janik, J.M.; Otnes, K.; Stanek, T.

1980-01-01

IR band contour measurements carried out for [Ni(H 2 O) 6 ] (ClO 4 ) 2 revealed an existence of fast H 2 O 180 deg flips around Ni-O axes at room temperatures. These flips were subjected to a more accurate study by the quasielastic neutron scattering method. Correlation times of the order of picosecond were obtained for room temperatures and the barrier to rotation of ca. 7 kcal/mole. The results are compared to those previously obtained for [Mg(H 2 O) 6 ] (ClO 4 ) 2 and also to those for [Ni(NH 3 ) 6 ] (ClO 4 ) 2 and [Mg(NH 3 ) 6 ] (ClO 4 ) 2 . (author)

Trapping {BW12}2 tungstoborate: synthesis and crystal structure of hybrid [{(H2BW12O42)2O}{Mo6O6S6(OH)4(H2O)2}]14- anion.

Science.gov (United States)

Korenev, V S; Abramov, P A; Vicent, C; Mainichev, D A; Floquet, S; Cadot, E; Sokolov, M N; Fedin, V P

2012-12-28

Reaction between monolacunary {BW(11)} tungstoborate and oxothiocationic building block, {Mo(2)O(2)S(2)}, results in the formation of a new polyoxothiometalate with a unique architecture in which two [H(2)BW(12)O(43)](9-) tungstoborate subunits are linked together with a hexamolybdate [Mo(V)(6)O(6)S(6)(OH)(4)(H(2)O)(2)](2+) bridge.

Cosmetic wastewater treatment by the ZVI/H2O2 process.

Science.gov (United States)

Bogacki, Jan; Marcinowski, Piotr; Zapałowska, Ewa; Maksymiec, Justyna; Naumczyk, Jeremi

2017-10-01

The ZVI/H 2 O 2 process was applied for cosmetic wastewater treatment. Two commercial zero-valent iron (ZVI) types with different granulations were chosen: Hepure Ferrox PRB and Hepure Ferrox Target. In addition, the pH and stirring method influence on ZVI/H 2 O 2 process efficiency was studied. During the ZVI and ZVI/H 2 O 2 processes, linear Fe ions concentration increase was observed. The addition of H 2 O 2 significantly accelerated the iron dissolution process. The highest COD removal was obtained using finer ZVI (Hepure Ferrox Target) for doses of reagents ZVI/H 2 O 2 1500/1600 mg/L, in a H 2 O 2 /COD weight ratio 2:1, at pH 3.0 with stirring on a magnetic stirrer. After 120 min of the process, 84.0% COD removal (from 796 to 127 mg/L) was achieved. It was found that the efficiency of the process depends, as in the case of the Fenton process, on the ratio of the reagents (ZVI/H 2 O 2 ) and their dose in relation to the COD (H 2 O 2 /COD) but does not depend on the dose of the iron itself. Statistical analysis confirms that COD removal efficiency depends primarily on H 2 O 2 /COD ratio and ZVI granulation, but ZVI dose influence is not statistically significant. The head space, solid-phase microextraction, gas chromatography, mass spectrometry results confirm high efficiency of the ZVI/H 2 O 2 process.

Catalase activity is stimulated by H2O2 in rich culture medium and is required for H2O2 resistance and adaptation in yeast ☆

OpenAIRE

Martins, Dorival; English, Ann M.

2014-01-01

Catalases are efficient scavengers of H2O2 and protect cells against H2O2 stress. Examination of the H2O2 stimulon in Saccharomyces cerevisiae revealed that the cytosolic catalase T (Ctt1) protein level increases 15-fold on H2O2 challenge in synthetic complete media although previous work revealed that deletion of the CCT1 or CTA1 genes (encoding peroxisomal/mitochondrial catalase A) does not increase the H2O2 sensitivity of yeast challenged in phosphate buffer (pH 7.4). This we attributed to...

Synthesis, structure, optical, photoluminescence and magnetic properties of K2[Co(C2O4)2(H2O)2]·4H2O

Science.gov (United States)

Narsimhulu, M.; Hussain, K. A.

2018-06-01

The synthesis, crystal structure, optical, photoluminescence and magnetic behaviour of potassium bis(oxalato)cobaltate(II)tertrahydrate{K2[Co(C2O4)2(H2O)2]·4H2O} are described. The compound was grown at room temperature from mixture of aqueous solutions by slow evaporation method. The X-ray crystallographic data showed that the compound belongs to the monoclinic crystal system with P21/n space group and Z = 4. The UV-visible diffuse absorbance spectra exhibited bands at 253, 285 and 541 nm in the visible and ultraviolet regions. The optical band gap of the compound was estimated as 3.4 eV. At room temperature, an intense photoluminescence was observed from this material around 392 nm when it excited at 254 nm. The variable temperature dc magnetic susceptibility measurements exposed paramagnetic behaviour at high temperatures and antiferromagnetic ordering at low temperatures.

Systems Li[sub 2]B[sub 4]O[sub 7] (Na[sub 2]B[sub 4]O[sub 7], K[sub 2]B[sub 4]O[sub 7])-N[sub 2]H[sub 3]H[sub 4]OH-H[sub 2]O at 25 deg C. Sistemy Li[sub 2]B[sub 4]O[sub 7] (Na[sub 2]B[sub 4]O[sub 7], K[sub 2]B[sub 4]O[sub 7])-N[sub 2]H[sub 3]H[sub 4]OH-H[sub 2]O pri 25 grad S

Energy Technology Data Exchange (ETDEWEB)

Skvortsov, V G; Sadetdinov, Sh V; Akimov, V M; Mitrasov, Yu N; Petrova, O V; Klopov, Yu N [Chuvashskij Gosudarstvennyj Pedagogicheskij Inst., Cheboksary (Russian Federation) Universitet Druzhby Narodov, Moscow (Russian Federation)

1994-02-01

Phase equilibriums in the Li[sub 2]B[sub 4]O[sub 7] (Na[sub 2]B[sub 4]O[sub 7], K[sub 2]B[sub 4]O[sub 7])-N[sub 2]H[sub 3]H[sub 4]OH-H[sub 2]O systems were investigated by methods of isothermal solubility, refractometry and PH-metry at 25 deg C for the first time. Lithium and sodium tetraborates was established to form phases of changed composition mM[sub 2]B[sub 4]O[sub 7][center dot]nN[sub 2]H[sub 3]C[sub 2]H[sub 4]OH[center dot]XH[sub 2]O, where M=Li, Na with hydrazine ethanol. K[sub 2]B[sub 4]O[sub 7][center dot]4H[sub 2]O precipitates in solid phase in the case of potassium salt. Formation of isomorphous mixtures was supported by X-ray diffraction and IR spectroscopy methods.

Characterization of a real time H2O2 monitor for use in studies on H2O2 production by antibodies and cells.

Science.gov (United States)

Sharma, Harish A; Balcavage, Walter X; Waite, Lee R; Johnson, Mary T; Nindl, Gabi

2003-01-01

It was recently shown that antibodies catalyze a reaction between water and ultraviolet light (UV) creating singlet oxygen and ultimately H2O2. Although the in vivo relevance of these antibody reactions is unclear, it is interesting that among a wide variety of non-antibody proteins tested, the T cell receptor is the only protein with similar capabilities. In clinical settings UV is believed to exert therapeutic effects by eliminating inflammatory epidermal T cells and we hypothesized that UV-triggered H2O2 production is involved in this process. To test the hypothesis we developed tools to study production of H2O2 by T cell receptors with the long-term goal of understanding, and improving, UV phototherapy. Here, we report the development of an inexpensive, real time H2O2 monitoring system having broad applicability. The detector is a Clark oxygen electrode (Pt, Ag/AgCl) modified to detect UV-driven H2O2 production. Modifications include painting the electrode black to minimize UV effects on the Ag/AgCl electrode and the use of hydrophilic, large pore Gelnots electrode membranes. Electrode current was converted to voltage and then amplified and recorded using a digital multimeter coupled to a PC. A reaction vessel with a quartz window was developed to maintain constant temperature while permitting UV irradiation of the samples. The sensitivity and specificity of the system and its use in cell-free and cell-based assays will be presented. In a cellfree system, production of H2O2 by CD3 antibodies was confirmed using our real time H2O2 monitoring method. Additionally we report the finding that splenocytes and Jurkat T cells also produce H2O2 when exposed to UV light.

X-ray-induced dissociation of H.sub.2O and formation of an O.sub.2-H.sub.2 alloy at high pressure

Science.gov (United States)

Mao, Ho-kwang [Washington, DC; Mao, Wendy L [Washington, DC

2011-11-29

A novel molecular alloy of O.sub.2 and H.sub.2 and a method of producing such a molecular alloy are provided. When subjected to high pressure and extensive x-radiation, H.sub.2O molecules cleaved, forming O--O and H--H bonds. In the method of the present invention, the O and H framework in ice VII was converted into a molecular alloy of O.sub.2 and H.sub.2. X-ray diffraction, x-ray Raman scattering, and optical Raman spectroscopy demonstrate that this crystalline solid differs from previously known phases.

[Protective effect of taxifolin on H2O2-induced 
H9C2 cell pyroptosis].

Science.gov (United States)

Ye, Yanqiong; Wang, Xiaoli; Cai, Qian; Zhuang, Jian; Tan, Xiaohua; He, Wei; Zhao, Mingyi

2017-12-28

To explore the effect of taxifolin on H2O2-induced pyroptosis in H9C2 cells and the possible mechanisms.
 Methods: The H9C2 cells was divided into 3 groups: a control group, a hydrogen peroxide (H2O2)group and a taxifolin group. The morphology of H9C2 cells was observed by inverted phase contrast microscope. The mitochondrial membrane potential was measured by JC-1 staining and flow cytometry. The alteration of the level of reactive oxygen species (ROS) was detected by specific mitochondrial probe. The protein levels of cysteinyl aspartate specific proteinase-1 (caspase-1)was determined by Western blot. The mRNA levels of interleukin-18 (IL-18), interleukin-1a (IL-1a), interleukin-1b (IL-1b), absent in melanoma 2 (AIM2), apoptosis-associated apeck-like protein (ASC), nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3)and nucleotide-binding oligomerization domain-like receptor family caspase recruitment domain-containing protein 4 (NLRC4) were determined by reverse transcription-polymerase chain reaction (RT-PCR).
 Results: Compared with the control group, the morphology of H9C2 cells obviously changed in the H2O2-treated group, which was guadually improved in the presence of taxifolin. Compared with the control group, the mitochondrial membrane potential was markedly decreased in the H2O2-treated cells, accompanied by the increase ofROS (both PH2O2 group, the mitochondrial membrane potential changes in the taxifolin group was increased while the ROS was decreased, with significant difference (both PH2O2-treated group were significantly increased (all PH2O2-induced H9C2 cell pyroptosis through inhibition of AIM2, NLRP3 and NLRC4 in flammasome.

Removal of diethyl phthalate from water solution by adsorption, photo-oxidation, ozonation and advanced oxidation process (UV/H2O2, O3/H2O2 and O3/activated carbon)

International Nuclear Information System (INIS)

Medellin-Castillo, Nahum A.; Ocampo-Pérez, Raúl; Leyva-Ramos, Roberto; Sanchez-Polo, Manuel; Rivera-Utrilla, José; Méndez-Díaz, José D.

2013-01-01

The objective of this work was to compare the effectiveness of conventional technologies (adsorption on activated carbon, AC, and ozonation) and technologies based on advanced oxidation processes, AOPs, (UV/H 2 O 2 , O 3 /AC, O 3 /H 2 O 2 ) to remove phthalates from aqueous solution (ultrapure water, surface water and wastewater). Diethyl phthalate (DEP) was chosen as a model pollutant because of its high water solubility (1080 mg/L at 293 K) and toxicity. The activated carbons showed a high adsorption capacity to adsorb DEP in aqueous solution (up to 858 mg/g), besides the adsorption mechanism of DEP on activated carbon is governed by dispersive interactions between π electrons of its aromatic ring with π electrons of the carbon graphene planes. The photodegration process showed that the pH solution does not significantly affect the degradation kinetics of DEP and the first-order kinetic model satisfactorily fitted the experimental data. It was observed that the rate of decomposition of DEP with the O 3 /H 2 O 2 and O 3 /AC systems is faster than that with only O 3 . The technologies based on AOPs (UV/H 2 O 2 , O 3 /H 2 O 2 , O 3 /AC) significantly improve the degradation of DEP compared to conventional technologies (O 3 , UV). AC adsorption, UV/H 2 O 2 , O 3 /H 2 O 2 , and O 3 /AC showed a high yield to remove DEP; however, the disadvantage of AC adsorption is its much longer time to reach maximum removal. The best system to treat water (ultrapure and natural) polluted with DEP is the O 3 /AC one since it achieved the highest DEP degradation and TOC removal, as well as the lower water toxicity. -- Highlights: ► Activated carbons showed a high adsorption capacity (up to 858 mg/g) to remove DEP. ► The pH solution did not significantly affect the photodegradation kinetics of DEP. ► The O 3 /H 2 O 2 and O 3 /AC systems were more efficient than O 3 to degrade DEP. ► The generation of HO • from O 3 was enhanced by ACs, mainly by those of basic nature. ► O

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

Dissociative phototionization cross sections of H2, SO2 and H2O

International Nuclear Information System (INIS)

Chung, Y.

1989-01-01

The partial photoionization cross sections of H 2 , SO 2 , and H 2 O were calculated from the measured photoionization branching ratios and the known total photoionization cross sections. The branching ratios were measured with a time-of-flight mass spectrometer and synchrotron radiation. The branching ratios Of H 2 , SO 2 , and H 2 O were measured for 100 ∼ 410, 150 ∼ 380 and 120 ∼ 720 angstrom. The author also measured the photoionization yield Of SO 2 from 520 to 665 angstrom using a double ion chamber and a glow discharge light source. The principle of a time-of-flight mass spectrometer is explained. New calculations were made to see how the design of the mass spectrometer, applied voltage, and kinetic energy of the ions affect the overall performance of the mass spectrometer. Several useful techniques that we used at the synchrotron for wavelength calibration and higher order suppression are also discussed

Synthesis and X-ray Crystallography of [Mg(H2O)6][AnO2(C2H5COO)3]2 (An = U, Np, or Pu).

Science.gov (United States)

Serezhkin, Viktor N; Grigoriev, Mikhail S; Abdulmyanov, Aleksey R; Fedoseev, Aleksandr M; Savchenkov, Anton V; Serezhkina, Larisa B

2016-08-01

Synthesis and X-ray crystallography of single crystals of [Mg(H2O)6][AnO2(C2H5COO)3]2, where An = U (I), Np (II), or Pu (III), are reported. Compounds I-III are isostructural and crystallize in the trigonal crystal system. The structures of I-III are built of hydrated magnesium cations [Mg(H2O)6](2+) and mononuclear [AnO2(C2H5COO)3](-) complexes, which belong to the AB(01)3 crystallochemical group of uranyl complexes (A = AnO2(2+), B(01) = C2H5COO(-)). Peculiarities of intermolecular interactions in the structures of [Mg(H2O)6][UO2(L)3]2 complexes depending on the carboxylate ion L (acetate, propionate, or n-butyrate) are investigated using the method of molecular Voronoi-Dirichlet polyhedra. Actinide contraction in the series of U(VI)-Np(VI)-Pu(VI) in compounds I-III is reflected in a decrease in the mean An═O bond lengths and in the volume and sphericity degree of Voronoi-Dirichlet polyhedra of An atoms.

High-resolution photoelectron spectroscopy of TiO3H2-: Probing the TiO2- + H2O dissociative adduct

Science.gov (United States)

DeVine, Jessalyn A.; Abou Taka, Ali; Babin, Mark C.; Weichman, Marissa L.; Hratchian, Hrant P.; Neumark, Daniel M.

2018-06-01

Slow electron velocity-map imaging spectroscopy of cryogenically cooled TiO3H2- anions is used to probe the simplest titania/water reaction, TiO20/- + H2O. The resultant spectra show vibrationally resolved structure assigned to detachment from the cis-dihydroxide TiO(OH)2- geometry based on density functional theory calculations, demonstrating that for the reaction of the anionic TiO2- monomer with a single water molecule, the dissociative adduct (where the water is split) is energetically preferred over a molecularly adsorbed geometry. This work represents a significant improvement in resolution over previous measurements, yielding an electron affinity of 1.2529(4) eV as well as several vibrational frequencies for neutral TiO(OH)2. The energy resolution of the current results combined with photoelectron angular distributions reveals Herzberg-Teller coupling-induced transitions to Franck-Condon forbidden vibrational levels of the neutral ground state. A comparison to the previously measured spectrum of bare TiO2- indicates that reaction with water stabilizes neutral TiO2 more than the anion, providing insight into the fundamental chemical interactions between titania and water.

Physical limit of stability in supercooled D2O and D2O+H2O mixtures

Science.gov (United States)

Kiselev, S. B.; Ely, J. F.

2003-01-01

The fluctuation theory of homogeneous nucleation was applied for calculating the physical boundary of metastable states, the kinetic spinodal, in supercooled D2O and D2O+H2O mixtures. The kinetic spinodal in our approach is completely determined by the surface tension and equation of state of the supercooled liquid. We developed a crossover equation of state for supercooled D2O, which predicts a second critical point of low density water-high density water equilibrium, CP2, and represents all available experimental data in supercooled D2O within experimental accuracy. Using Turnbull's expression for the surface tension we calculated with the crossover equation of state for supercooled D2O the kinetic spinodal, TKS, which lies below the homogeneous nucleation temperature, TH. We show that CP2 always lies inside in the so-called "nonthermodynamic habitat" and physically does not exist. However, the concept of a second "virtual" critical point is physical and very useful. Using this concept we have extended this approach to supercooled D2O+H2O mixtures. As an example, we consider here an equimolar D2O+H2O mixture in normal and supercooled states at atmospheric pressure, P=0.1 MPa.

Crystal structure of RbCe(SeO4)2 · 5H2O

International Nuclear Information System (INIS)

Ovanesyan, S.M.; Iskhakova, L.D.; Trunov, V.K.

1987-01-01

RbTR(SeO 4 ) 2 x5H 2 O TR=La-Pr are synthesized. Crystal structure of RbCe(SeO 4 ) 2 x5H 2 O is studied. Monoclinic unit parameters are: a=7,200(2), b=8,723(1), c=19,258(6) A, Β=90,88(2), ρ (calc) =3,304 sp.gr. P2 1 /c. Within the structure the Ce nine vertex cages are united by Se(1)- and Se(2)-tetrahedrons in (Ce(SeO 4 ) 2 (H 2 O) 5 ) 2 ∞ n- layers. Some crystal structure regularities of the laminated MTR(EO 4 ) 2 xnH 2 O (M=NH 4 ,K,Rb,Cs; TR=La-Ln, E=S,Se) are considered

Ab initio and transition state theory study of the OH + HO2 → H2O + O2(3Σg−)/O2(1Δg) reactions: yield and role of O2(1Δg) in H2O2 decomposition and in combustion of H2

KAUST Repository

Monge Palacios, Manuel

2018-01-22

Reactions of hydroxyl (OH) and hydroperoxyl (HO2) are important for governing the reactivity of combustion systems. We performed post-CCSD(T) ab initio calculations at the W3X-L//CCSD = FC/cc-pVTZ level to explore the triplet ground-state and singlet excited-state potential energy surfaces of the OH + HO2 → H2O + O2(3Σg−)/O2(1Δg) reactions. Using microcanonical and multistructural canonical transition state theories, we calculated the rate constant for the triplet and singlet channels over the temperature range 200–2500 K, represented by k(T) = 3.08 × 1012T0.07 exp(1151/RT) + 8.00 × 1012T0.32 exp(−6896/RT) and k(T) = 2.14 × 106T1.65 exp(−2180/RT) in cm3 mol−1 s−1, respectively. The branching ratios show that the yield of singlet excited oxygen is small (<0.5% below 1000 K). To ascertain the importance of singlet oxygen channel, our new kinetic information was implemented into the kinetic model for hydrogen combustion recently updated by Konnov (Combust. Flame, 2015, 162, 3755–3772). The updated kinetic model was used to perform H2O2 thermal decomposition simulations for comparison against shock tube experiments performed by Hong et al. (Proc. Combust. Inst., 2013, 34, 565–571), and to estimate flame speeds and ignition delay times in H2 mixtures. The simulation predicted a larger amount of O2(1Δg) in H2O2 decomposition than that predicted by Konnov\\'s original model. These differences in the O2(1Δg) yield are due to the use of a higher ab initio level and a more sophisticated methodology to compute the rate constant than those used in previous studies, thereby predicting a significantly larger rate constant. No effect was observed on the rate of the H2O2 decomposition and on the flame speeds and ignition delay times of different H2–oxidizer mixtures. However, if the oxidizer is seeded with O3, small differences appear in the flame speed. Given that O2(1Δg) is much more reactive than O2(3Σg−), we do not preclude an effect of the

Advanced Low-Cost O2/H2 Engines for the SSTO Application

Science.gov (United States)

Goracke, B. David; Levack, Daniel J. H.; Nixon, Robert F.

1994-01-01

The recent NASA Access to Space study examined future Earth to orbit (ETO) transportation needs and fleets out to 2030. The baseline in the option 3 assessment was a single stage to orbit (SSTO) vehicle. A study was conducted to assess the use of new advanced low cost O2/H2 engines for this SSTO application. The study defined baseline configurations and ground rules and defined six engine cycles to explore engine performance. The cycles included an open cycle, and a series of closed cycles with varying abilities to extract energy from the propellants to power he turbomachinery. The cycles thus varied in the maximum chamber pressure they could reach and in their weights at any given chamber pressure. The weight of each cycle was calculated for two technology levels versus chamber pressure up to the power limit of the cycle. The performance in the SSTO mission was then modeled using the resulting engine weights and specific impulse performance using the Access to Space option 3 vehicle. The results showed that new O2/H2 engines are viable and competitive candidates for the SSTO application using chamber pressures of 4,000 psi.

ZrOCl2.8H2O as a green and efficient catalyst for the expeditious synthesis of substituted 3-arylpyrimido[4,5-c]pyridazines in water

Directory of Open Access Journals (Sweden)

Mehdi Rimaz

2015-09-01

Full Text Available A new and simple synthetic methodology for the preparation of 3-arylpyrimido[4,5-c]pyridazine-5,7(6H,8H-diones and 3-aryl-5-oxo-7-thioxo-7,8-dihydropyrimido[4,5-c]pyridazin-5(6H-ones by a one-pot three component reaction of barbituric acid or thiobarbituric acid with arylglyoxals in the presence of catalytic amount of ZrOCl2∙8H2O as green Lewis acid and hydrazine hydrate at ambient temperature in water was reported. All of these pyrimidopyridazines derivatives have one clustered water molecule in their molecular structure. The use of ZrOCl2∙8H2O catalyst is feasible because of its easy availability, convenient handling, high stability, simple recovery, reusability, good activity and eco-friendly.

UV and VUV photolysis vs. UV/H2O2 and VUV/H2O2, treatment for removal of clofibric acid from aqueous solution.

Science.gov (United States)

Li, Wenzhen; Lu, Shuguang; Qiu, Zhaofu; Lin, Kuangfei

2011-07-01

Clofibric acid (CA), a metabolite of lipid regulators, was investigated in ultra-pure water and sewage treatment plant (STP) effluent at 10 degrees C under UV, vacuum UV (VUV), UV/H2O2 and VUV/H2O2 processes. The influences of NO3-, HCO3- and humic acid (HA) on CA photolysis in all processes were examined. The results showed that all the experimental data well fitted the pseudo-first-order kinetic model, and the apparent rate constant (k(ap)) and half-life time (t(1/2)) were calculated accordingly. Direct photolysis of CA through UV irradiation was the main process, compared with the indirect oxidation of CA due to the slight generation of hydroxyl radicals dissociated from water molecules under UV irradiation below 200 nm monochromatic wavelength emission. In contrast, indirect oxidation was the main CA degradation mechanism in UV/H2O2 and VUV/H2O2, and VUV/H2O2 was the most effective process for CA degradation. The addition of 20 mg L(-1) HA could significantly inhibit CA degradation, whereas, except for UV irradiation, the inhibitive effects of NO3- and HCO3- (1.0 x 10(-3) and 0.1 mol L(-1), respectively) on CA degradation were observed in all processes, and their adverse effects were more significant in UV/H2O2 and VUV/H2O2 processes, particularly at the high NO3- and HCO3- concentrations. The degradation rate decreased 1.8-4.9-fold when these processes were applied to a real STP effluent owing to the presence of complex constituents. Of the four processes, VUV/H2O2 was the most effective, and the CA removal efficiency reached over 99% after 40 min in contrast to 80 min in both the UV/H2O2 and VUV processes and 240 min in the UV process.

Chlorogenic acid analogues from Gynura nepalensis protect H9c2 cardiomyoblasts against H2O2-induced apoptosis.

Science.gov (United States)

Yu, Bang-Wei; Li, Jin-Long; Guo, Bin-Bin; Fan, Hui-Min; Zhao, Wei-Min; Wang, He-Yao

2016-11-01

Chlorogenic acid has shown protective effect on cardiomyocytes against oxidative stress-induced damage. Herein, we evaluated nine caffeoylquinic acid analogues (1-9) isolated from the leaves of Gynura nepalensis for their protective effect against H 2 O 2 -induced H9c2 cardiomyoblast damage and explored the underlying mechanisms. H9c2 cardiomyoblasts were exposed to H 2 O 2 (0.3 mmol/L) for 3 h, and cell viability was detected with MTT assay. Hoechst 33342 staining was performed to evaluate cell apoptosis. MMPs (mitochondrial membrane potentials) were measured using a JC-1 assay kit, and ROS (reactive oxygen species) generation was measured using CM-H 2 DCFDA. The expression levels of relevant proteins were detected using Western blot analysis. Exposure to H 2 O 2 markedly decreased the viability of H9c2 cells and catalase activity, and increased LDH release and intracellular ROS production; accompanied by a loss of MMP and increased apoptotic rate. Among the 9 chlorogenic acid analogues as well as the positive control drug epigallocatechin gallate (EGCG) tested, compound 6 (3,5-dicaffeoylquinic acid ethyl ester) was the most effective in protecting H9c2 cells from H 2 O 2 -induced cell death. Pretreatment with compound 6 (1.56-100 μmol/L) dose-dependently alleviated all the H 2 O 2 -induced detrimental effects. Moreover, exposure to H 2 O 2 significantly increased the levels of Bax, p53, cleaved caspase-8, and cleaved caspase-9, and decreased the level of Bcl-2, resulting in cell apoptosis. Exposure to H 2 O 2 also significantly increased the phosphorylation of p38, JNK and ERK in the H9c2 cells. Pretreatment with compound 6 (12.5 and 25 μmol/L) dose-dependently inhibited the H 2 O 2 -induced increase in the level of cleaved caspase-9 but not of cleaved caspase-8. It also dose-dependently suppressed the H 2 O 2 -induced phosphorylation of JNK and ERK but not that of p38. Compound 6 isolated from the leaves of Gynura nepalensis potently protects H9c2

Multicomponent Biginelli's synthesis of 3,4-dihydropyrimidin-2(1H-ones promoted by SnCl2.2H2O

Directory of Open Access Journals (Sweden)

Russowsky Dennis

2004-01-01

Full Text Available The ability of SnCl2.2H2O as catalyst to promote the Biginelli three-component condensation reaction from a diversity of aromatic aldehydes, ethyl acetoacetate and urea or thiourea is described. The reaction was carried out in acetonitrile or ethanol as solvents in neutral media and represents an improvement of the classical Biginelli protocol and an advantage in comparison with FeCl3.6H2O, NiCl2.6H2O and CoCl2.6H2O which were used with HCl as co-catalyst. The synthesis of 3,4-dihydropyrimidinones was achieved in good to excelent yields.

Matrix Isolation Spectroscopy of H2O2, D2O, and HDO in Solid Parahydrogen

National Research Council Canada - National Science Library

Fajardo, Mario

2003-01-01

...) solids doped with H2O, D2O and HDO molecules. Analysis of the rovibrational spectra of the isolated H20, D2O and HDO monomers reveals their existence as very slightly hindered rotors, typically showing only 2 to 5...

Transcriptome analysis of H2O2-treated wheat seedlings reveals a H2O2-responsive fatty acid desaturase gene participating in powdery mildew resistance.

Directory of Open Access Journals (Sweden)

Aili Li

Full Text Available Hydrogen peroxide (H(2O(2 plays important roles in plant biotic and abiotic stress responses. However, the effect of H(2O(2 stress on the bread wheat transcriptome is still lacking. To investigate the cellular and metabolic responses triggered by H(2O(2, we performed an mRNA tag analysis of wheat seedlings under 10 mM H(2O(2 treatment for 6 hour in one powdery mildew (PM resistant (PmA and two susceptible (Cha and Han lines. In total, 6,156, 6,875 and 3,276 transcripts were found to be differentially expressed in PmA, Han and Cha respectively. Among them, 260 genes exhibited consistent expression patterns in all three wheat lines and may represent a subset of basal H(2O(2 responsive genes that were associated with cell defense, signal transduction, photosynthesis, carbohydrate metabolism, lipid metabolism, redox homeostasis, and transport. Among genes specific to PmA, 'transport' activity was significantly enriched in Gene Ontology analysis. MapMan classification showed that, while both up- and down- regulations were observed for auxin, abscisic acid, and brassinolides signaling genes, the jasmonic acid and ethylene signaling pathway genes were all up-regulated, suggesting H(2O(2-enhanced JA/Et functions in PmA. To further study whether any of these genes were involved in wheat PM response, 19 H(2O(2-responsive putative defense related genes were assayed in wheat seedlings infected with Blumeria graminis f. sp. tritici (Bgt. Eight of these genes were found to be co-regulated by H(2O(2 and Bgt, among which a fatty acid desaturase gene TaFAD was then confirmed by virus induced gene silencing (VIGS to be required for the PM resistance. Together, our data presents the first global picture of the wheat transcriptome under H(2O(2 stress and uncovers potential links between H(2O(2 and Bgt responses, hence providing important candidate genes for the PM resistance in wheat.

Removal of pharmaceutically active compounds from synthetic and real aqueous mixtures and simultaneous disinfection by supported TiO2/UV-A, H2O2/UV-A, and TiO2/H2O2/UV-A processes.

Science.gov (United States)

Bosio, Morgana; Satyro, Suéllen; Bassin, João Paulo; Saggioro, Enrico; Dezotti, Márcia

2018-05-01

Pharmaceutically active compounds are carried into aquatic bodies along with domestic sewage, industrial and agricultural wastewater discharges. Psychotropic drugs, which can be toxic to the biota, have been detected in natural waters in different parts of the world. Conventional water treatments, such as activated sludge, do not properly remove these recalcitrant substances, so the development of processes able to eliminate these compounds becomes very important. Advanced oxidation processes are considered clean technologies, capable of achieving high rates of organic compounds degradation, and can be an efficient alternative to conventional treatments. In this study, the degradation of alprazolam, clonazepam, diazepam, lorazepam, and carbamazepine was evaluated through TiO 2 /UV-A, H 2 O 2 /UV-A, and TiO 2 /H 2 O 2 /UV-A, using sunlight and artificial irradiation. While using TiO 2 in suspension, best results were found at [TiO 2 ] = 0.1 g L -1 . H 2 O 2 /UV-A displayed better results under acidic conditions, achieving from 60 to 80% of removal. When WWTP was used, degradation decreased around 50% for both processes, TiO 2 /UV-A and H 2 O 2 /UV-A, indicating a strong matrix effect. The combination of both processes was shown to be an adequate approach, since removal increased up to 90%. H 2 O 2 /UV-A was used for disinfecting the aqueous matrices, while mineralization was obtained by TiO 2 -photocatalysis.

Dexmedetomidine attenuates H2O2-induced cell death in human osteoblasts.

Science.gov (United States)

Yoon, Ji-Young; Park, Jeong-Hoon; Kim, Eun-Jung; Park, Bong-Soo; Yoon, Ji-Uk; Shin, Sang-Wook; Kim, Do-Wan

2016-12-01

Reactive oxygen species play critical roles in homeostasis and cell signaling. Dexmedetomidine, a specific agonist of the α 2 -adrenoceptor, has been commonly used for sedation, and it has been reported to have a protective effect against oxidative stress. In this study, we investigated whether dexmedetomidine has a protective effect against H 2 O 2 -induced oxidative stress and the mechanism of H 2 O 2 -induced cell death in normal human fetal osteoblast (hFOB) cells. Cells were divided into three groups: control group-cells were incubated in normoxia without dexmedetomidine, hydrogen peroxide (H 2 O 2 ) group-cells were exposed to H 2 O 2 (200 µM) for 2 h, and Dex/H 2 O 2 group-cells were pretreated with dexmedetomidine (5 µM) for 2 h then exposed to H 2 O 2 (200 µM) for 2 h. Cell viability and apoptosis were evaluated. Osteoblast maturation was determined by assaying bone nodular mineralization. Expression levels of bone-related proteins were determined by western blot. Cell viability was significantly decreased in the H 2 O 2 group compared with the control group, and this effect was improved by dexmedetomidine. The Hoechst 33342 and Annexin-V FITC/PI staining revealed that dexmedetomidine effectively decreased H 2 O 2 -induced hFOB cell apoptosis. Dexmedetomidine enhanced the mineralization of hFOB cells when compared to the H 2 O 2 group. In western blot analysis, bone-related protein was increased in the Dex/H 2 O 2 group. We demonstrated the potential therapeutic value of dexmedetomidine in H 2 O 2 -induced oxidative stress by inhibiting apoptosis and enhancing osteoblast activity. Additionally, the current investigation could be evidence to support the antioxidant potential of dexmedetomidine in vitro.

Stability of globular proteins in H2O and in D2O

NARCIS (Netherlands)

Efimova, Y.M.; Haemers, S.; Wierczinsky, B.; Norde, W.; Well, van A.A.

2007-01-01

In several experimental techniques D2O rather then H2O is often used as a solvent for proteins. Concerning the influence of the solvent on the stability of the proteins, contradicting results have been reported in literature. In this paper the influence of H2O-D2O solvent substitution on the

Borate mineral assemblages in the system Na2OCaOMgOB2O3H2O

Science.gov (United States)

Christ, C.L.; Truesdell, A.H.; Erd, Richard C.

1967-01-01

he significant known hydrated borate mineral assemblages (principally of the western United States) in the system Na2OCaOz.sbnd;MgOB2O3H2O are expressible in three ternary composition diagrams. Phase rule interpretation of the diagrams is consistent with observation, if the activity of H2O is generally considered to be determined by the geologic environment. The absence of conflicting tie-lines on a diagram indicates that the several mineral assemblages of the diagram were formed under relatively narrow ranges of temperature and pressure. The known structural as well as empirical formulas for the minerals are listed, and the more recent (since 1960) crystal structure findings are discussed briefly. Schematic Gibbs free energy-composition diagrams based on known solubility-temperature relations in the systems Na2B4O7-H2O and Na2B4O7-NaCl-H2O, are highly useful in the interpretation and prediction of the stability relations in these systems; in particular these diagrams indicate clearly that tincalconite, although geologically important, is everywhere a metastable phase. Crystal-chemical considerations indicate that the same thermodynamic and kinetic behavior observed in the Na2B4O7-H2O system will hold in the Ca2B6O11-H2O system. This conclusion is confirmed by the petrologic evidence. The chemical relations among the mineral assemblages of a ternary diagram are expressed by a schematic "activity-activity" diagram. These activity-activity diagrams permit the tracing-out of the paragenetic sequences as a function of changing cation and H2O activities. ?? 1967.

The H2O/D2O exchange across vesicular lipid bilayers

International Nuclear Information System (INIS)

Engelbert, H.P.; Lawaczek, R.

1985-01-01

A new method to measure the water (D 2 O/H 2 O) permeation across vesicular lipid bilayers is described. The method is based on the solvent isotope effect of the light scattering which is a consequence of the different indices of refraction of D 2 O and H 2 O. Unilamellar lipid vesicles in excess of H 2 O are rapidly mixed with D 2 O or vice versa. As result of the H 2 O/D 2 O exchange across the vesicular bilayer the light scattering signal has a time dependent, almost single exponential component allowing the deduction of the exchange relaxation rate and, at known size, of the permeability coefficient. The experimental results are in accord with calculations from the Mie theory of light scattering for coated spheres. The method is applicable for large vesicles where the permeation is the rate-limiting step. Size separations are performed by a flow dialysis through a sequence of pore-membrane-filters. For dimyristoyl-lecithin bilayers the water permeability-coefficient is 1.9 . 10 -5 cm/s in the crystalline phase and increases by a factor of 10-100 in the liquid-crystalline state. The temperature dependence of the permeation exhibits a sharp change at the phase transition. For binary mixtures of lecithins this sharp change follows the solidus curve of the non-ideal phase diagram determined by spectroscopic techniques. (orig.)

The first 3D malonate bridged copper [Cu(O2C–CH2–CO2H)2·2H2O]: Structure, properties and electronic structure

International Nuclear Information System (INIS)

Seguatni, A.; Fakhfakh, M.; Smiri, L.S.; Gressier, P.; Boucher, F.; Jouini, N.

2012-01-01

A new inorganic-organic compound [Cu(O 2 C–CH 2 –CO 2 H) 2 ·2H 2 O] ([Cumal]) was hydrothermally synthesized and characterized by IR spectroscopy, thermal analysis and single crystal X-ray diffraction. [Cumal] is the first three-dimensional compound existing in the system Cu(II)–malonic acid–H 2 O. Its framework is built up through carboxyl bridged copper where CuO 6 octahedra are elongated with an almost D 4h symmetry (4+2) due to the Jahn–Teller effect. The magnetic properties were studied by measuring its magnetic susceptibility in the temperature range of 2–300 K indicating the existence of weak ferromagnetic interactions. The electronic structure of [Cumal] was calculated within the density functional theory (DFT) framework. Structural features are well reproduced using DFT structural optimizations and the optical spectra, calculated within the dielectric formalism, explain very well the light blue colour of the compound. It is shown that a GGA+U approach with a U eff value of about 6 eV is necessary for a better correlation with the experiment. - Graphical abstract: [Cu(O 2 C–CH 2 –CO 2 H) 2 ·2H 2 O]: the first 3D hybrid organic–inorganic compound built up carboxyl groups. The network presents a diamond-like structure achieved via carboxyl. Highlights: ► A new organic–inorganic material with an unprecedented topology is synthesized. ► Crystallographic structure is determined using single crystal X-ray diffraction. ► Electronic structure is obtained from DFT, GGA+U calculation. ► Framework can be described as formed from CuC 4 tetrahedron sharing four corners. ► This structure can be classified as an extended diamond structure.

Synthetic, spectroscopic and structural studies on 4-aminobenzoate complexes of divalent alkaline earth metals: x-ray crystal structures of [[Mg(H2O)6] (4-aba)2].2H2O and [Ca(H2O)2(4-aba)2] (4-aba=4-aminobenzoate)

International Nuclear Information System (INIS)

Murugavel, Ramaswamy; Karambelkar, Vivek V.; Anantharaman, Ganapathi

2000-01-01

Reactions between MCl 2 .nH 2 O (M = Mg, Ca, Sr, and Ba) and 4-aminobenzoic acid (4-abaH) result in the formation of complexes [(Mg(H 2 O) 6 )(4-aba) 2 ) .2H 2 O (I), [Ca(4-aba) 2 (H2 O ) 2 ] (2), [Sr(4-aba) 2 (H2 O ) 2 ] (3), and [Ba(4-aba) 2 Cl] (4), respectively. The new compounds 1 and 2, as well as the previously reported 3 and 4 form an extended intra- and intermolecular hydrogen bonded network in the solid-state. The compounds have been characterized by elemental analysis, pH measurements, thermogravimetric studies, and IR, NMR, and UV-Vis spectroscopy. The solid state structures of the molecules 1 and 2 have been determined by single crystal x-ray diffraction studies. In the case of magnesium complex 1, the dipositively charged Mg cation is surrounded by six water molecules and the two 4-aminobenzoate ligands show no direct bonding to the metal ion. The calcium ion in 2 is octa-coordinated with direct coordination of the 4-aminobenzoate ligands to the metal ion. The Ca-Ca separation in the polymeric chain of 2 is 3.9047(5) A. (author)

Photodegradation of amoxicillin by catalyzed Fe3+/H2O2 process

Institute of Scientific and Technical Information of China (English)

Xiaoming Li; Tingting Shen; Dongbo Wang; Xiu Yue; Xian Liu; Qi Yang; Jianbin Cao; Wei Zheng; Guangming Zeng

2012-01-01

Three oxidation processes of UV-Fe3+(EDTA)/H2O2 (UV:ultraviolet light; EDTA:ethylenediaminetetraacetic acid),UV-Fe3+/H2O2 and Fe3+/H2O2 were simultaneously investigated for the degradation of amoxicillin at pH 7.0.The results indicated that,100% amoxicillin degradation and 81.9% chemical oxygen demand (CODcr) removal could be achieved in the UV-Fe3+ (EDTA)/H2O2 process.The treatment efficiency of amoxicillin and CODcr removal were found to decrease to 59.0% and 43.0% in the UV-Fe3+/H2O2 process;39.6% and 31.3% in the Fe3+/H2O2 process.Moreover,the results of biodegradability (biological oxygen demand (BOD5)/CODCr ratio) revealed that the UV-Fe3+ (EDTA)/H2O2 process was a promising strategy to degrade amoxicillin as the biodegradability of the effluent was improved to 0.45,compared with the cases of UV-Fe3+/H2O2 (0.25) and Fe3+/H2O2 (0.10) processes.Therefore,it could be deduced that EDTA and UV light performed synergetic catalytic effect on the Fe3+/H2O2 process,enhancing the treatment efficiency.The degradation mechanisms were also investigated via UV-Vis spectra,and high performance liquid chromatography-mass spectra.The degradation pathway of amoxicillin was further proposed.

Water Ice Radiolytic O2, H2, and H2O2 Yields for Any Projectile Species, Energy, or Temperature: A Model for Icy Astrophysical Bodies

Science.gov (United States)

Teolis, B. D.; Plainaki, C.; Cassidy, T. A.; Raut, U.

2017-10-01

O2, H2, and H2O2 radiolysis from water ice is pervasive on icy astrophysical bodies, but the lack of a self-consistent, quantitative model of the yields of these water products versus irradiation projectile species and energy has been an obstacle to estimating the radiolytic oxidant sources to the surfaces and exospheres of these objects. A major challenge is the wide variation of O2 radiolysis yields between laboratory experiments, ranging over 4 orders of magnitude from 5 × 10-7 to 5 × 10-3 molecules/eV for different particles and energies. We revisit decades of laboratory data to solve this long-standing puzzle, finding an inverse projectile range dependence in the O2 yields, due to preferential O2 formation from an 30 Å thick oxygenated surface layer. Highly penetrating projectile ions and electrons with ranges ≳30 Å are therefore less efficient at producing O2 than slow/heavy ions and low-energy electrons (≲ 400 eV) which deposit most energy near the surface. Unlike O2, the H2O2 yields from penetrating projectiles fall within a comparatively narrow range of (0.1-6) × 10-3 molecules/eV and do not depend on range, suggesting that H2O2 forms deep in the ice uniformly along the projectile track, e.g., by reactions of OH radicals. We develop an analytical model for O2, H2, and H2O2 yields from pure water ice for electrons and singly charged ions of any mass and energy and apply the model to estimate possible O2 source rates on several icy satellites. The yields are upper limits for icy bodies on which surface impurities may be present.

Human milk H2O2 content: does it benefit preterm infants?

Science.gov (United States)

Cieslak, Monika; Ferreira, Cristina H F; Shifrin, Yulia; Pan, Jingyi; Belik, Jaques

2018-03-01

BackgroundHuman milk has a high content of the antimicrobial compound hydrogen peroxide (H 2 O 2 ). As opposed to healthy full-term infants, preterm neonates are fed previously expressed and stored maternal milk. These practices may favor H 2 O 2 decomposition, thus limiting its potential benefit to preterm infants. The goal of this study was to evaluate the factors responsible for H 2 O 2 generation and degradation in breastmilk.MethodsHuman donors' and rats' milk, along with rat mammary tissue were evaluated. The role of oxytocin and xanthine oxidase on H 2 O 2 generation, its pH-dependent stability, as well as its degradation via lactoperoxidase and catalase was measured in milk.ResultsBreast tissue xanthine oxidase is responsible for the H 2 O 2 generation and its milk content is dependent on oxytocin stimulation. Stability of the human milk H 2 O 2 content is pH-dependent and greatest in the acidic range. Complete H 2 O 2 degradation occurs when human milk is maintained, longer than 10 min, at room temperature and this process is suppressed by lactoperoxidase and catalase inhibition.ConclusionFresh breastmilk H 2 O 2 content is labile and quickly degrades at room temperature. Further investigation on breastmilk handling techniques to preserve its H 2 O 2 content, when gavage-fed to preterm infants is warranted.

Highly Chemoselective Reduction of Amides (Primary, Secondary, Tertiary) to Alcohols using SmI2/Amine/H2O under Mild Conditions

Science.gov (United States)

2014-01-01

Highly chemoselective direct reduction of primary, secondary, and tertiary amides to alcohols using SmI2/amine/H2O is reported. The reaction proceeds with C–N bond cleavage in the carbinolamine intermediate, shows excellent functional group tolerance, and delivers the alcohol products in very high yields. The expected C–O cleavage products are not formed under the reaction conditions. The observed reactivity is opposite to the electrophilicity of polar carbonyl groups resulting from the nX → π*C=O (X = O, N) conjugation. Mechanistic studies suggest that coordination of Sm to the carbonyl and then to Lewis basic nitrogen in the tetrahedral intermediate facilitate electron transfer and control the selectivity of the C–N/C–O cleavage. Notably, the method provides direct access to acyl-type radicals from unactivated amides under mild electron transfer conditions. PMID:24460078

Photochemical degradation of diethyl phthalate with UV/H2O2

International Nuclear Information System (INIS)

Xu Bin; Gao Naiyun; Sun Xiaofeng; Xia Shengji; Rui Min; Simonnot, Marie-Odile; Causserand, Christel; Zhao Jianfu

2007-01-01

The decomposition of diethyl phthalate (DEP) in water using UV-H 2 O 2 process was investigated in this paper. DEP cannot be effectively removed by UV radiation and H 2 O 2 oxidation alone, while UV-H 2 O 2 combination process proved to be effective and could degrade this compound completely. With initial concentration about 1.0 mg/L, more than 98.6% of DEP can be removed at time of 60 min under intensity of UV radiation of 133.9 μW/cm 2 and H 2 O 2 dosage of 20 mg/L. The effects of applied H 2 O 2 dose, UV radiation intensity, water temperature and initial concentration of DEP on the degradation of DEP have been examined in this study. Degradation mechanisms of DEP with hydroxyl radicals oxidation also have been discussed. Removal rate of DEP was sensitive to the operational parameters. A simple kinetic model is proposed which confirms to pseudo-first order reaction. There is a linear relationship between rate constant k and UV intensity and H 2 O 2 concentration

Crystal structure of strontium aqua(ethylenediaminetetraacetato)cobaltate(II) tetrahydrate Sr[CoEdta(H2O)] · 4H2O

International Nuclear Information System (INIS)

Zasurskaya, L.A.; Polynova, T.N.; Polyakova, I.N.; Sergienko, V.S.; Poznyak, A.L.

2001-01-01

The complex Sr[Co II Edta] · 5H 2 O (I) (where Edta 4- is the ethylenediaminetetraacetate ion) has been synthesized. The crystal structure of this compound is determined by X-ray diffraction. Crystals are monoclinic, a = 7.906(2) A, b = 12.768(2) A, c = 18.254(3) A, β = 95.30(3) deg., V 1834.8 A 3 , space group P2 1 /n, Z = 4, and R = 0.036. The structure is built up of the binuclear complex fragments {Sr(H 2 O) 3 [CoEdta(H 2 O)]}, which consist of the anionic [CoEdta(H 2 O)] 2- and cationic [Sr(H 2 O) 3 ] 2+ units linked by the Sr-O bonds into a three-dimensional framework. The coordination polyhedra of the Co and Sr atoms are mono- and bicapped trigonal prisms. The coordination sphere of the Co atom (the coordination number is equal to 6 + 1) involves six donor atoms (2N and 4O) of the Edta 4- ligand and the O w atom of water molecule. One of the Co-O distances (2.718 A) is considerably longer than the other Co-O lig distances (2.092-2.190 A) and the Co-O w (1) distance (2.079 A). The Sr coordination polyhedron (the coordination number is eight) contains three water molecules, three carbonyl O atoms of the three different anionic complexes, and two O atoms of one acetate group of the fourth anionic complex. The Sr-O distances fall in the range 2.535-2.674 A. The structural formula of the compound is {Sr(H 2 O) 3 [CoEdta(H 2 O)]} 3∞ · H 2 O

The crystal structure of Cs{sub 2}S{sub 2}O{sub 3}.H{sub 2}O

Energy Technology Data Exchange (ETDEWEB)

Winkler, Verena; Schlosser, Marc; Pfitzner, Arno [Regensburg Univ. (Germany). Inst. fuer Anorganische Chemie

2016-08-01

A reinvestigation of the alkali metal thiosulfates has led to the new phase Cs{sub 2}S{sub 2}O{sub 3}.H{sub 2}O. At first cesium thiosulfate monohydrate was obtained as a byproduct of the synthesis of Cs{sub 4}In{sub 2}S{sub 5}. Further investigations were carried out using the traditional synthesis reported by J. Meyer and H. Eggeling. Cs{sub 2}S{sub 2}O{sub 3}.H{sub 2}O crystallizes in transparent, colorless needles. The crystal structure of the title compound was determined by single crystal X-ray diffraction at room temperature: space group C2/m (No. 12), unit cell dimensions: a = 11.229(4), b = 5.851(2), c = 11.260(5) Aa, β = 95.89(2) , with Z = 4 and a cell volume of V = 735.9(5) Aa{sup 3}. The positions of all atoms including the hydrogen atoms were located in the structure refinement. Cs{sub 2}S{sub 2}O{sub 3}.H{sub 2}O is isotypic with Rb{sub 2}S{sub 2}O{sub 3}.H{sub 2}O. Isolated tetrahedra [S{sub 2}O{sub 3}]{sup 2-} are coordinated by the alkali metal cations, and in addition they serve as acceptors for hydrogen bonding. For both Cs atoms the shortest distances are observed to oxygen atoms of the S{sub 2}O{sub 3}{sup 2-} anions whereas the terminating sulfur atom has its shortest contacts to the water hydrogen atoms. Thus, an extended hydrogen bonding network is formed. The title compound has also been characterized by IR spectroscopy. IR spectroscopy reveals the vibrational bands of the water molecules at 3385 cm{sup -1}. They show a red shift in the OH stretching and bending modes as compared to free water. This is due both to the S..H hydrogen bonding and to the coordination of H{sub 2}O molecules to the cesium atoms.

Synthesis and crystal structure of new uranyl selenite(IV)-selenate(VI) [C5H14N][(UO2)3(SeO4)4(HSeO3)(H2O)](H2SeO3)(HSeO4)

International Nuclear Information System (INIS)

Krivovichev, S.V.; Tananaev, I.G.; Myasoedov, B.F.; Kalenberg, V.

2006-01-01

Crystals of new uranyl selenite(IV)-selenate(VI) [C 5 H 14 N][(UO 2 ) 3 (SeO 4 ) 4 (HSeO 3 )(H 2 O)](H 2 SeO 3 )(HSeO 4 ) are obtained by the method of evaporation from aqueous solutions. Compound has triclinic lattice, space group P1-bar, a=11.7068(9), b=14.8165(12), c=16.9766(15), α=73.899(6), β=76.221(7), γ=89.361(6) Deg, V=2743.0(4) A 3 , Z=2. Laminated complexes (UO 2 ) 3 (SeO 4 ) 4 (HSeO 3 )(H 2 O)] 3- are the basis of the structure. [HSe(VI)O 4 ] - , [H 2 Se(IV)O 3 ] complexes and protonated methylbutylamine cations are disposed between layers [ru

Inhibitory Effect of Dissolved Silica on the H2O2 Decomposition by Iron(III) and Manganese(IV) Oxides: Implications for H2O2-based In Situ Chemical Oxidation

Science.gov (United States)

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

2011-01-01

The decomposition of H2O2 on iron minerals can generate •OH, a strong oxidant that can transform a wide range of contaminants. This reaction is critical to In Situ Chemical Oxidation (ISCO) processes used for soil and groundwater remediation, as well as advanced oxidation processes employed in waste treatment systems. The presence of dissolved silica at concentrations comparable to those encountered in natural waters decreases the reactivity of iron minerals toward H2O2, because silica adsorbs onto the surface of iron minerals and alters catalytic sites. At circumneutral pH values, goethite, amorphous iron oxide, hematite, iron-coated sand and montmorillonite that were pre-equilibrated with 0.05 – 1.5 mM SiO2 were significantly less reactive toward H2O2 decomposition than their original counterparts, with the H2O2 loss rates inversely proportional to the SiO2 concentration. In the goethite/H2O2 system, the overall •OH yield, defined as the percentage of decomposed H2O2 producing •OH, was almost halved in the presence of 1.5 mM SiO2. Dissolved SiO2 also slows the H2O2 decomposition on manganese(IV) oxide. The presence of dissolved SiO2 results in greater persistence of H2O2 in groundwater, lower H2O2 utilization efficiency and should be considered in the design of H2O2-based treatment systems. PMID:22129132

Proton conducting system (ImH2)2SeO4·2H2O investigated with vibrational spectroscopy

Science.gov (United States)

Zięba, Sylwia; Mizera, Adam; Pogorzelec-Glaser, Katarzyna; Łapiński, Andrzej

2017-06-01

Imidazolium selenate dihydrate (ImH2)2SeO4·2H2O crystals have been investigated using Raman and IR spectroscopy. Experimental data were supported by the quantum-chemical calculations (DFT), Hirshfield surfaces and fingerprint plots analysis, and Bader theory calculations. The imidazolium selenate dihydrate crystal exhibits high proton conductivity of the order of 10- 1 S/m at T = 333 K. The spectra of this compound are dominated by bands related to the lattice modes, the internal vibrations of the protonated imidazole cation, selenate anion, water molecules, and hydrogen bonds network. For the imidazolium selenate dihydrate crystal, the formal classification of the fundamental modes has been carried out.

H2SO4-HNO3-H2O ternary system in the stratosphere

Science.gov (United States)

Kiang, C. S.; Hamill, P.

1974-01-01

Estimation of the equilibrium vapor pressure over the ternary system H2SO4-HNO3-H2O to study the possibility of stratospheric aerosol formation involving HNO3. It is shown that the vapor pressures for the ternary system H2SO4-HNO3-H2O with weight composition around 70-80% H2SO4, 10-20% HNO3, 10-20% H2O at -50 C are below the order of 10 to the minus 8th mm Hg. It is concluded that there exists more than sufficient nitric acid and water vapor in the stratosphere to participate in ternary system aerosol formation at -50 C. Therefore, HNO3 should be present in stratospheric aerosols, provided that H2SO4 is also present.

Nd(BrO3)3-Yb(BrO3)3-H2O and Nd2(SeO4)3-Yb2(SeO4)3-H2O systems at 25 deg C

International Nuclear Information System (INIS)

Serebrennikov, V.V.; Batyreva, V.A.; Tsybukova, T.N.

1981-01-01

Using the methods of isothermal solubility the Nd(BrO 3 ) 3 - Yb(BrO 3 ) 3 -H 2 O and Nd 2 (SeO 4 ) 3 -Yb 2 (SeO 4 ) 3 -H 2 O systems are studied at 25 deg C. The compositions of the solid phases are determined by the method of ''residues''. The formation of two series of solid solutions in both systems is established. Besides, there is a crystallization region of Nd 2 (SeO 4 ) 3 in the system of selenates. The solubility diagrams of the systems are presented [ru

Magnetic measurements and neutron diffraction study of the layered hybrid compounds Mn(C8H4O4)(H2O)2 and Mn2(OH)2(C8H4O4)

International Nuclear Information System (INIS)

Sibille, Romain; Mesbah, Adel; Mazet, Thomas; Malaman, Bernard; Capelli, Silvia; François, Michel

2012-01-01

Mn(C 8 H 4 O 4 )(H 2 O) 2 and Mn 2 (OH) 2 (C 8 H 4 O 4 ) layered organic–inorganic compounds based on manganese(II) and terephthalate molecules (C 8 H 4 O 4 2− ) have been studied by DC and AC magnetic measurements and powder neutron diffraction. The dihydrated compound behaves as a 3D antiferromagnet below 6.5 K. The temperature dependence of its χT product is typical of a 2D Heisenberg system and allows determining the in-plane exchange constant J≈−7.4 K through the carboxylate bridges. The magnetic structure confirms the in-plane nearest neighbor antiferromagnetic interactions and the 3D ordering. The hydroxide based compound also orders as a 3D antiferromagnet with a higher Néel temperature (38.5 K). Its magnetic structure is described from two antiferromagnetically coupled ferromagnetic sublattices, in relation with the two independent metallic sites. The isothermal magnetization data at 2 K are consistent with the antiferromagnetic ground-state of these compounds. However, in both cases, a slope change points to field-induced modification of the magnetic structure. - Graphical abstract: The macroscopic magnetic properties and magnetic structures of two metal-organic frameworks based on manganese (II) and terephthalate molecules are presented. Highlights: ► Magnetic study of Mn(C 8 H 4 O 4 )(H 2 O) 2 and Mn 2 (OH) 2 (C 8 H 4 O 4 ). ► Two compounds with common features (interlayer linker/distance, S=5/2 spin). ► Magnetic measurements quantitatively analyzed to deduce exchange constants. ► Magnetic structures determined from neutron powder diffraction experiments.

Atomic-Scale View on the H₂O Formation Reaction from H₂ on O-Rich RuO₂(110)

DEFF Research Database (Denmark)

Wei, Yinying; Martinez, Umberto; Lammich, Lutz

2014-01-01

The H2O formation reaction from H-2 on O-rich RuO2(110) was studied by temperature-programmed desorption and reaction (TPD/TPR) and scanning tunneling microscopy (STM) measurements and density functional theory (DFT) calculations. On the one hand, following H-2 adsorption at 270 K, our TPD/TPR me...

Production of 34S-labeled gypsum (Ca34SO4.2H2O Produção de gesso (Ca34SO4.2H2O, marcado com 34S

Directory of Open Access Journals (Sweden)

Alexssandra Luiza Rodrigues Molina Rossete

2006-08-01

Full Text Available Agricultural gypsum (CaSO4.2H2O stands out as an effective source of calcium and sulfur, and to control aluminum saturation in the soil. Labeled as 34S it can elucidate important aspects of the sulfur cycle. Ca34SO4.2H2O was obtained by chemical reaction between Ca(OH2 and H2(34SO4, performed under slow agitation. The acid was produced by ion exchange chromatography using the Dowex 50WX8 cation exchange resin and a Na2(34SO4 eluting solution. After precipitation, the precipitate was separated and dried in a ventilated oven at 60ºC. From 2.2 L H2SO4 0.2 mol L-1 and 33.6 g Ca(OH2, 73.7 ± 0.6 g Ca34SO4.2H2O were produced on average in the tests, representing a mean yield of 94.6 ± 0.8%, with 98% purity. The 34SO2 gas was obtained from Ca34SO4.2H2O in the presence of NaPO3 in a high vacuum line and was used for the isotopic determination of S in an ATLAS-MAT model CH-4 mass spectrometer.O gesso agrícola (CaSO4.2H2O destaca-se como fonte eficiente de cálcio e enxofre e na redução da saturação de alumínio no solo. O 34S como traçador isotópico pode elucidar aspectos importantes no ciclo do enxofre. Para tanto o Ca34SO4.2H2O foi obtido por reação química entre o Ca(OH2 e solução de H2(34SO4, realizada sob agitação lenta. O ácido foi produzido por cromatografia de troca iônica, utilizando resina catiônica Dowex 50WX8 e solução eluente de Na2(34SO4. Após a precipitação foi separado o precipitado e realizada a secagem em estufa ventilada à temperatura de 60ºC. Nos testes, a partir de 2,2 L de H2SO4 0,2 mol L-1 e 33,6 g de Ca(OH2, foram produzidos em média 73,7 ± 0,6 g de Ca34SO4.2H2O representando um rendimento médio de 94,6 ± 0,8%, com pureza de 98%. A partir do Ca34SO4.2H2O na presença de NaPO3, em linha de alto vácuo, obteve-se o gás 34SO2 utilizado para a determinação isotópica do S no espectrômetro de massas ATLAS-MAT modelo CH-4.

H2O2 INDUCES DELAYED HYPEREXCITABILITY IN NUCLEUS TRACTUS SOLITARII NEURONS

Science.gov (United States)

Ostrowski, Tim D.; Hasser, Eileen M.; Heesch, Cheryl M.; Kline, David D.

2014-01-01

Hydrogen peroxide (H2O2) is a stable reactive oxygen species and potent neuromodulator of cellular and synaptic activity. Centrally, endogenous H2O2 is elevated during bouts of hypoxia-reoxygenation, a variety of disease states, and aging. The nucleus tractus solitarii (nTS) is the central termination site of visceral afferents for homeostatic reflexes and contributes to reflex alterations during these conditions. We determined the extent to which H2O2 modulates synaptic and membrane properties in nTS neurons in rat brainstem slices. Stimulation of the tractus solitarii (which contains the sensory afferent fibers) evoked synaptic currents that were not altered by 10 – 500 μM H2O2. However, 500 μM H2O2 modulated several intrinsic membrane properties of nTS neurons, including a decrease in input resistance, hyperpolarization of resting membrane potential (RMP) and action potential (AP) threshold (THR), and an initial reduction in AP discharge to depolarizing current. H2O2 increased conductance of barium-sensitive potassium currents, and block of these currents ablated H2O2-induced changes in RMP, input resistance and AP discharge. Following washout of H2O2 AP discharge was enhanced due to depolarization of RMP and a partially maintained hyperpolarization of THR. Hyperexcitability persisted with repeated H2O2 exposure. H2O2 effects on RMP and THR were ablated by intracellular administration of the antioxidant catalase, which was immunohistochemically identified in neurons throughout the nTS. Thus, H2O2 initially reduces excitability of nTS neurons that is followed by sustained hyperexcitability, which may play a profound role in cardiorespiratory reflexes. PMID:24397952

Double molybdates in Li2MoO4 - Na2MoO4 - H2O system at 25 grad C

International Nuclear Information System (INIS)

Karov, Z.G.; Mirzoev, R.S.; Makitova, D.D.; Zhilova, S.B.; Podnek, A.G.; Urusova, R.Kh.

1989-01-01

Solubility in Li 2 MoO 4 - Na 2 MoO 4 - H 2 O system at 25 deg C is first stuied. Formation of two Li 2 MoO 4 · Na 2 MoO 4 · 4H 2 O and Li 2 MoO 4 · 3Na 2 MoO 4 · 12H 2 O compounds in a system is ascertained. Density, refractive index, viscosity, surface tension, electric conductivity and pH of saturated solutions are determined. Isothermes of mole volume, equivalent and reduced electric conductivity and seeming mole volume of salts sum in solutions are calculated. All these properties adequtely confirm the character of components interaction in a system determined by solubility method. Crystallhydrates of binary molybdates are separated, indentified and studied

Magnetocaloric effect in gadolinium-oxalate framework Gd2(C2O4)3(H2O)6⋅(0⋅6H2O)

International Nuclear Information System (INIS)

Sibille, Romain; Didelot, Emilie; Mazet, Thomas; Malaman, Bernard; François, Michel

2014-01-01

Magnetic refrigerants incorporating Gd 3+ ions and light organic ligands offer a good balance between isolation of the magnetic centers and their density. We synthesized the framework material Gd 2 (C 2 O 4 ) 3 (H 2 O) 6 ⋅0.6H 2 O by a hydrothermal route and characterized its structure. The honeycomb lattice of Gd 3+ ions interlinked by oxalate ligands in the (a,c) plane ensures their decoupling in terms of magnetic exchange interactions. This is corroborated by magnetic measurements indicating negligible interactions between the Gd 3+ ions in this material. The magnetocaloric effect was evaluated from isothermal magnetization measurements. The maximum entropy change −ΔS M max reaches 75.9 mJ cm −3 K −1 (around 2 K) for a moderate field change (2 T)

D/H fractionation in the H2-H2O system at supercritical water conditions: Compositional and hydrogen bonding effects

Science.gov (United States)

Foustoukos, Dionysis I.; Mysen, Bjorn O.

2012-06-01

A series of experiments has been conducted in the H2-D2-D2O-H2O-Ti-TiO2 system at temperatures ranging from 300 to 800 °C and pressures between ∼0.3 and 1.3 GPa in a hydrothermal diamond anvil cell, utilizing Raman spectroscopy as a quantitative tool to explore the relative distribution of hydrogen and deuterium isotopologues of the H2 and H2O in supercritical fluids. In detail, H2O-D2O solutions (1:1) were reacted with Ti metal (3-9 h) in the diamond cell, leading to formation of H2, D2, HD, and HDO species through Ti oxidation and H-D isotope exchange reactions. Experimental results obtained in situ and at ambient conditions on quenched samples indicate significant differences from the theoretical estimates of the equilibrium thermodynamic properties of the H-D exchange reactions. In fact, the estimated enthalpy for the H2(aq)-D2(aq) disproportionation reaction (ΔHrxn) is about -3.4 kcal/mol, which differs greatly from the +0.16 kcal/mol predicted for the exchange reaction in the gas phase by statistical mechanics models. The exothermic behavior of the exchange reaction implies enhanced stability of H2 and D2 relative to HD. Accordingly, the significant energy difference of the internal H2(aq)-D2(aq)-HD(aq) equilibrium translates to strong differences of the fractionation effects between the H2O-H2 and D2O-D2 isotope exchange relationships. The D/H fractionation factors between H2O-H2(aq) and D2O-D2(aq) differ by 365‰ in the 600-800 °C temperature range, and are indicative of the greater effect of D2O contribution to the δD isotopic composition of supercritical fluids. The negative ΔHrxn values for the H2(aq)-D2(aq)-HD(aq) equilibrium and the apparent decrease of the equilibrium constant with increasing temperature might be because of differences of the Henry’s law constant between the H- and D-bearing species dissolved in supercritical aqueous solutions. Such effects may be attributed to the stronger hydrogen bonding in the O-H⋯O relative to the

Transfer of π- from hydrogen to deuterium in H2O + D2O mixtures

International Nuclear Information System (INIS)

Stanislaus, S.; Measday, D.F.; Vetterli, D.; Weber, P.; Aniol, K.A.; Harston, M.R.; Armstrong, D.S.

1989-07-01

The transfer of stopping π - mesons from hydrogen to deuterium has been investigated in mixtures of H 2 O+D 2 O as a function of D 2 O concentration. The concentration dependence of the transfer probability is similar to that observed for the gas mixtures of H 2 and D 2 but slightly more transfer is found for H 2 O+D 2 O. (Author) 17 refs., 2 tabs., 4 figs

Effects of variation in background mixing ratios of N2, O2, and Ar on the measurement of δ18O-H2O and δ2H-H2O values by cavity ring-down spectroscopy

Science.gov (United States)

Johnson, Jennifer E.; Rella, Chris W.

2017-08-01

Cavity ring-down spectrometers have generally been designed to operate under conditions in which the background gas has a constant composition. However, there are a number of observational and experimental situations of interest in which the background gas has a variable composition. In this study, we examine the effect of background gas composition on a cavity ring-down spectrometer that measures δ18O-H2O and δ2H-H2O values based on the amplitude of water isotopologue absorption features around 7184 cm-1 (L2120-i, Picarro, Inc.). For background mixtures balanced with N2, the apparent δ18O values deviate from true values by -0.50 ± 0.001 ‰ O2 %-1 and -0.57 ± 0.001 ‰ Ar %-1, and apparent δ2H values deviate from true values by 0.26 ± 0.004 ‰ O2 %-1 and 0.42 ± 0.004 ‰ Ar %-1. The artifacts are the result of broadening, narrowing, and shifting of both the target absorption lines and strong neighboring lines. While the background-induced isotopic artifacts can largely be corrected with simple empirical or semi-mechanistic models, neither type of model is capable of completely correcting the isotopic artifacts to within the inherent instrument precision. The development of strategies for dynamically detecting and accommodating background variation in N2, O2, and/or Ar would facilitate the application of cavity ring-down spectrometers to a new class of observations and experiments.

Positronium formation and hydrated positron reactions in H2O, D2O, 1.74 M PPS/H2O and 1.74 M PPS/D2O solutions of Cl−, Br− and I−

DEFF Research Database (Denmark)

Mogensen, O. E.; Pedersen, Niels Jørgen

1986-01-01

Angular correlation of annihilation photons were measured for H2O, D2O, 1.74 M PPS/H2O and 1.74 M PPS/D2O solutions of Cl−, Br− and I−. The three components of the angular correlation spectra for D2O and H2O were nearly identical in shape. The positronium (Ps) yields for the H2O and D2O solutions...... before annihilation (lifetime 400 ps) was determined for the three halides in the four solvents. Simple kinetic equations (“trapping model”) with time dependent rate constant, solved analytically, could explain the [X−, e+] formation in H2O fairly well for concentrations below 0.03 M X−, if a diffusion...... controlled reaction with positron diffusion constant D = 5 × 10−5 cm2/s and reaction radius R = 1 nm were assumed. The three halides gave roughly identical [X−, e+] formation below 0.03 M X−. The difference between the four solutions could be explained partly only in terms of viscosity change for the model...

SYNTHESIS AND STRUCTURAL CHARACTERISTICS OF BIS(CITRATEGERMANATES(IV (Hbipy2[Ge(HCit2]•2H2O AND [CuCl(bipy2]2[Ge(HCit2]•8H2O

Directory of Open Access Journals (Sweden)

Inna Seifullina

2016-12-01

Full Text Available The crystalline compounds (Hbipy2[Ge(HCit2]·2H2O (1 and CuCl(bipy2]2[Ge(HCit2]·8H2O (2 (where H4Cit is citric acid, bipy is 2,2ʹ-bipyridine were obtained for the fi rst time and their structures were determined by the single-crystal X-ray diffraction method. Compounds were characterized by IR spectroscopy, thermogravimetric (TGA and elemental analyses. Both compounds are formed with complex bis(citrategermanate anion and protonated 2,2’-bipyridine or [Cu(bipy2Cl]+ as cations in compounds 1 and 2, respectively.

A neodymium(III)-ammonium complex involving oxalate and carbonate ligands: (NH4)2[Nd2(C2O4)3(CO3)(H2O)].H2O.

Science.gov (United States)

Trombe, Jean-Christian; Galy, Jean; Enjalbert, Renée

2002-10-01

The title compound, diammonium aqua-mu-carbonato-tri-mu-oxalato-dineodymium(III) hydrate, (NH(4))(2)[Nd(2)(CO(3))(C(2)O(4))(3)(H(2)O)].H(2)O, involving the two ligands oxalate and carbonate, has been prepared hydrothermally as single crystals. The Nd atoms form a tetranuclear unit across the inversion centre at (1/2, 1/2, 1/2). Starting from this tetranuclear unit, the oxalate ligands serve to develop a three-dimensional network. The carbonate group acts as a bis-chelating ligand to two Nd atoms, and is monodentate to a third Nd atom. The oxalate groups are all bis-chelating. The two independent Nd atoms are ninefold coordinated and the coordination polyhedron of these atoms is a distorted monocapped antiprism.

Synthesis and structure of heptaaqua(nitrilotris(methylenephosphonato))(dibarium)sodium monohydrate [Na(H{sub 2}O){sub 3}(μ{sup 6}-NH(CH{sub 2}PO{sub 3}){sub 3})(μ-H{sub 2}O){sub 3}Ba{sub 2}(H{sub 2}O)] · H{sub 2}O

Energy Technology Data Exchange (ETDEWEB)

Somov, N. V., E-mail: somov@phys.unn.ru [Lobachevsky State University of Nizhny Novgorod (Russian Federation); Chausov, F. F., E-mail: xps@ftiudm.ru [Russian Academy of Sciences, Physical–Technical Institute, Ural Branch (Russian Federation); Zakirova, R. M., E-mail: ftt@udsu.ru [Udmurt State University (Russian Federation)

2017-03-15

Crystals of the monohydrate form of heptaaqua(nitrilotris(methylenephosphonato))(dibarium) sodium [Na(H{sub 2}O{sub )3}(µ{sup 6}-NH(CH{sub 2}PO{sub 3}){sub 3})(µ-H{sub 2}O){sub 3}Ba{sub 2}(H{sub 2}O)] · H{sub 2}O are obtained; space group P2{sub 1}/c, Z = 4; a = 13.9117(10) Å, b = 11.54030(10) Å, and c = 24.1784(17) Å, ß = 148.785(18)°. The Na atom is coordinated octahedrally by one oxygen atom of a phosphonate group and five water molecules, including two bridging molecules. Ba atoms occupy two inequivalent crystallographic positions with coordination number eight and nine. The coordination spheres of both Ba atoms include two water molecules. Each ligand is bound to one Na atom and five Ba atoms forming three Ba–O–P–O and five Ba–O–P–C–N–C–P–O chelate cycles. In addition to the coordination bonds, molecules, including the solvate water molecule, are involved in hydrogen bonds in the crystal packing.

Experimental studies on cycling stable characteristics of inorganic phase change material CaCl2·6H2O-MgCl2·6H2O modified with SrCl2·6H2O and CMC

Science.gov (United States)

He, Meizhi; Yang, Luwei; Zhang, Zhentao

2018-01-01

By means of mass ratio method, binary eutectic hydrated salts inorganic phase change thermal energy storage system CaCl2·6H2O-20wt% MgCl2·6H2O was prepared, and through adding nucleating agent 1wt% SrCl2·6H2O and thickening agent 0.5wt% carboxy methyl cellulose (CMC), inoganic phase change material (PCM) modified was obtained. With recording cooling-melting curves simultaneously, this PCM was frozen and melted for 100 cycles under programmable temperature control. After per 10 cycles, the PCM was charaterized by differential scanning calorimeter (DSC), X-ray diffraction (XRD) and density meter, then analysing variation characteristics of phase change temperature, supercooling degree, superheat degree, latent heat, crystal structure and density with the increase of cycle index. The results showed that the average values of average phase change temperature for cooling and heating process were 25.70°C and 27.39°C respectively with small changes. The average values of average supercooling and superheat degree were 0.59°C and 0.49°C respectively, and the maximum value was 1.10°C. The average value and standard deviation of latent heat of fusion were 120.62 J/g and 1.90 J/g respectively. Non-molten white solid sediments resulted from phase separation were tachyhydrite (CaMg2Cl6·12H2O), which was characterized by XRD. Measuring density of the PCM after per 10 cycles, and the results suggested that the total mass of tachyhydrite was limited. In summary, such modified inoganic PCM CaCl2·6H2O-20wt% MgCl2·6H2O-1wt% SrCl2·6H2O-0.5wt% CMC could stay excellent circulation stability within 100 cycles, and providing reference value in practical use.

Low levels of iron enhance UV/H2O2 efficiency at neutral pH.

Science.gov (United States)

Ulliman, Sydney L; McKay, Garrett; Rosario-Ortiz, Fernando L; Linden, Karl G

2018-03-01

While the presence of iron is generally not seen as favorable for UV-based treatment systems due to lamp fouling and decreased UV transmittance, we show that low levels of iron can lead to improvements in the abatement of chemicals in the UV-hydrogen peroxide advanced oxidation process. The oxidation potential of an iron-assisted UV/H 2 O 2 (UV 254  + H 2 O 2  + iron) process was evaluated at neutral pH using iron levels below USEPA secondary drinking water standards (UV/H 2 O 2 systems. The effects of iron species (Fe 2+ and Fe 3+ ), iron concentration (0-0.3 mg/L), H 2 O 2 concentration (0-10 mg/L) and background water matrix (low-carbon tap (LCT) and well water) on HO production and compound removal were examined. Iron-assisted UV/H 2 O 2 efficiency was most influenced by the target chemical and the water matrix. Added iron to UV/H 2 O 2 was shown to increase the steady-state HO concentration by approximately 25% in all well water scenarios. While CBZ removal was unchanged by iron addition, 0.3 mg/L iron improved NDMA removal rates in both LCT and well water matrices by 15.1% and 4.6% respectively. Furthermore, the combination of UV/Fe without H 2 O 2 was also shown to enhance NDMA removal when compared to UV photolysis alone indicating the presence of degradation pathways other than HO oxidation. Copyright © 2017 Elsevier Ltd. All rights reserved.

Three-dimensional WS2 nanosheet networks for H2O2 produced for cell signaling

Science.gov (United States)

Tang, Jing; Quan, Yingzhou; Zhang, Yueyu; Jiang, Min; Al-Enizi, Abdullah M.; Kong, Biao; An, Tiance; Wang, Wenshuo; Xia, Limin; Gong, Xingao; Zheng, Gengfeng

2016-03-01

Hydrogen peroxide (H2O2) is an important molecular messenger for cellular signal transduction. The capability of direct probing of H2O2 in complex biological systems can offer potential for elucidating its manifold roles in living systems. Here we report the fabrication of three-dimensional (3D) WS2 nanosheet networks with flower-like morphologies on a variety of conducting substrates. The semiconducting WS2 nanosheets with largely exposed edge sites on flexible carbon fibers enable abundant catalytically active sites, excellent charge transfer, and high permeability to chemicals and biomaterials. Thus, the 3D WS2-based nano-bio-interface exhibits a wide detection range, high sensitivity and rapid response time for H2O2, and is capable of visualizing endogenous H2O2 produced in living RAW 264.7 macrophage cells and neurons. First-principles calculations further demonstrate that the enhanced sensitivity of probing H2O2 is attributed to the efficient and spontaneous H2O2 adsorption on WS2 nanosheet edge sites. The combined features of 3D WS2 nanosheet networks suggest attractive new opportunities for exploring the physiological roles of reactive oxygen species like H2O2 in living systems.Hydrogen peroxide (H2O2) is an important molecular messenger for cellular signal transduction. The capability of direct probing of H2O2 in complex biological systems can offer potential for elucidating its manifold roles in living systems. Here we report the fabrication of three-dimensional (3D) WS2 nanosheet networks with flower-like morphologies on a variety of conducting substrates. The semiconducting WS2 nanosheets with largely exposed edge sites on flexible carbon fibers enable abundant catalytically active sites, excellent charge transfer, and high permeability to chemicals and biomaterials. Thus, the 3D WS2-based nano-bio-interface exhibits a wide detection range, high sensitivity and rapid response time for H2O2, and is capable of visualizing endogenous H2O2 produced in

Activity and Selectivity for O-2 Reduction to H2O2 on Transition Metal Surfaces

DEFF Research Database (Denmark)

Siahrostami, Samira; Verdaguer Casadevall, Arnau; Karamad, Mohammadreza

2013-01-01

Industrially viable electrochemical production of H2O2 requires active, selective and stable electrocatalyst materials to catalyse the oxygen reduction reaction to H2O2. On the basis of density functional theory calculations, we explain why single site catalysts such as Pd/Au show improved...

Crystal structure of strontium osmate (8) Sr[OsO5(H2O)]x3H2O

International Nuclear Information System (INIS)

Nevskij, N.N; Ivanov-Ehmin, B.N.; Nevskaya, N.A.; Belov, N.V.; AN SSSR, Moscow. Inst. Kristallografii)

1982-01-01

Crystal structure of the Sr[OsO 5 (H 2 O)]x3H 2 O complex is studied. Rhombic P-cell has the parameters: a=6.426(1), b=7.888(1), c=14.377(5) A, Vsub(c)=729 A 3 . The R-factor equals 0.034. The coordinates of the basis atoms and isotropic temperature corrections, as well as basic interatomic distances, are determined

Dehydration of MoO 3 · 2H 2O: A Neutron Thermodiffractometry Study

Science.gov (United States)

Boudjada, N.; Rodríguez-Carvajal, J.; Anne, M.; Figlarz, M.

1993-07-01

A neutron powder thermodiffractometric study of the dehydration reactions MoO 3 · 2H 2O → MoO 3 · H 2O → MoO 3 has been carried out in order to investigate the topotactic mechanism previously reported. The topotactic character of the reactions is confirmed and an approximate model for the crystal structure of MoO 3 · H 2O is proposed. Quantitative data about the relative amount of the existing phases, as a function of temperature, have been deduced from multiphase profile analysis. The anomalous behavior of the cell parameters of MoO 3 · H 2O, at about 100°C, indicates the existence of a new phase transition. The evolution of the crystallite size of MoO 3 has also been obtained from the broadening of Bragg reflections at high temperature. The preferred direction of growth is along [021].

Mesospheric H2O and H2O2 densities inferred from in situ positive ion composition measurement

Science.gov (United States)

Kopp, E.

1984-01-01

A model for production and loss of oxonium ions in the high-latitude D-region is developed, based on the observed excess of 34(+) which has been interpreted as H2O2(+). The loss mechanism suggested in the study is the attachment of N2 and/or CO2 in three-body reactions. Furthermore, mesospheric water vapor and H2O2 densities are inferred from measurements of four high-latitude ion compositions, based on the oxonium model. Mixing ratios of hydrogen peroxide of up to two orders of magnitude higher than previous values were obtained. A number of reactions, reaction constants, and a block diagram of the oxonium ion chemistry in the D-region are given.

[H3N(CH2)4NH3]2[Al4(C2O4)(H2PO4)2(PO4)4].4[H2O]: A new layered aluminum phosphate-oxalate

International Nuclear Information System (INIS)

Peng Li; Li Jiyang; Yu Jihong; Li Guanghua; Fang Qianrong; Xu Ruren

2005-01-01

A new layered inorganic-organic hybrid aluminum phosphate-oxalate [H 3 N(CH 2 ) 4 NH 3 ] 2 [Al 4 (C 2 O 4 )(H 2 PO 4 ) 2 (PO 4 ) 4 ].4[H 2 O](AlPO-CJ25) has been synthesized hydrothermally, by using 1,4-diaminobutane (DAB) as structure-directing agent. The structure has been solved by single-crystal X-ray diffraction analysis and further characterized by IR, 31 P MAS NMR, TG-DTA as well as compositional analyses. Crystal data: the triclinic space group P-1, a=8.0484(7) A, b=8.8608(8) A, c=13.2224(11) A, α=80.830(6) deg. , β=74.965(5) deg. , γ=78.782(6) deg. , Z=2, R 1[ I >2 σ ( I )] =0.0511 and wR 2(alldata) =0.1423. The alternation of AlO 4 tetrahedra and PO 4 tetrahedra gives rise to the four-membered corner-sharing chains, which are interconnected through AlO 6 octahedra to form the layered structure with 4,6-net sheet. Interestingly, oxalate ions are bis-bidentately bonded by participating in the coordination of AlO 6 , and bridging the adjacent AlO 6 octahedra. The layers are held with each other through strong H-bondings between the terminal oxygens. The organic ammonium cations and water molecules are located in the large cavities between the interlayer regions. -- Graphical abstract: The alternation of AlO 4 tetrahedra and PO 4 tetrahedra gives rise to the four-membered corner-sharing chains, which are interconnected through AlO 6 octahedra to form the layered structure with 4,6-net sheet. Oxalate ions are bis-bidentately boned by participating in the coordination of AlO 6 , and bridging the adjacent AlO 6 octahedra

Pd-catalytic in situ generation of H2O2 from H2 and O2 produced by water electrolysis for the efficient electro-fenton degradation of rhodamine B.

Science.gov (United States)

Yuan, Songhu; Fan, Ye; Zhang, Yucheng; Tong, Man; Liao, Peng

2011-10-01

A novel electro-Fenton process was developed for wastewater treatment using a modified divided electrolytic system in which H2O2 was generated in situ from electro-generated H2 and O2 in the presence of Pd/C catalyst. Appropriate pH conditions were obtained by the excessive H+ produced at the anode. The performance of the novel process was assessed by Rhodamine B (RhB) degradation in an aqueous solution. Experimental results showed that the accumulation of H2O2 occurred when the pH decreased and time elapsed. The maximum concentration of H2O2 reached 53.1 mg/L within 120 min at pH 2 and a current of 100 mA. Upon the formation of the Fenton reagent by the addition of Fe2+, RhB degraded completely within 30 min at pH 2 with a pseudo first order rate constant of 0.109 ± 0.009 min(-1). An insignificant decline in H2O2 generation and RhB degradation was found after six repetitions. RhB degradation was achieved by the chemisorption of H2O2 on the Pd/C surface, which subsequently decomposed into •OH upon catalysis by Pd0 and Fe2+. The catalytic decomposition of H2O2 to •OH by Fe2+ was more powerful than that by Pd0, which was responsible for the high efficiency of this novel electro-Fenton process.

Investigation of dehydration reaction of BaCl2.2H2O and SrCl2.6H2O by thermal analysis under pressure

International Nuclear Information System (INIS)

Homma, Tsuneyuki; Yamada, Tetsuo

1978-01-01

The dehydration reactions of BaCl 2 .2H 2 O and SrCl 2 .6H 2 O were investigated by the techniques of thermal analysis, i.e. thermogravimetry (TG and DTG) and differential thermal analysis (DTA) under pressures of 1, 4, 10 and 40 atm. For BaCl 2 .2H 2 O, the DTA curves showed two peaks at 1 atm and three or four peaks at pressures above 4 atm, and the TG curves showed two steps over the range of 1 -- 10 atm and 3 steps at 40 atm. For SrCl 2 .6H 2 O, the DTA curves showed five peaks at respective pressure, and the TG curves showed three steps at 1 atm and two steps at pressures above 4 atm. As a common effect of pressure to the dehydration of these two salts, DTG peaks and some of DTA peaks shifted to higher temperatures with a increase in pressure, but a few peaks remained unshifted on DTA curves in spite of increasing pressure. The peaks which corresponded to these unshifted peaks on DTA curves were not observed on DTG curves. The unshifted peaks on DTA curves were attributed to the endothermic reaction accompanied by the dissociation of coordination water. The DTA and TG curves suggested that both salts formed the intermediate state between anhydrous and monohydrate states. (auth.)

The Role of Peroxiredoxins in the Transduction of H2O2 Signals.

Science.gov (United States)

Rhee, Sue Goo; Woo, Hyun Ae; Kang, Dongmin

2018-03-01

Hydrogen peroxide (H 2 O 2 ) is produced on stimulation of many cell surface receptors and serves as an intracellular messenger in the regulation of diverse physiological events, mostly by oxidizing cysteine residues of effector proteins. Mammalian cells express multiple H 2 O 2 -eliminating enzymes, including catalase, glutathione peroxidase (GPx), and peroxiredoxin (Prx). A conserved cysteine in Prx family members is the site of oxidation by H 2 O 2 . Peroxiredoxins possess a high-affinity binding site for H 2 O 2 that is lacking in catalase and GPx and which renders the catalytic cysteine highly susceptible to oxidation, with a rate constant several orders of magnitude greater than that for oxidation of cysteine in most H 2 O 2 effector proteins. Moreover, Prxs are abundant and present in all subcellular compartments. The cysteines of most H 2 O 2 effectors are therefore at a competitive disadvantage for reaction with H 2 O 2 . Recent Advances: Here we review intracellular sources of H 2 O 2 as well as H 2 O 2 target proteins classified according to biochemical and cellular function. We then highlight two strategies implemented by cells to overcome the kinetic disadvantage of most target proteins with regard to H 2 O 2 -mediated oxidation: transient inactivation of local Prx molecules via phosphorylation, and indirect oxidation of target cysteines via oxidized Prx. Critical Issues and Future Directions: Recent studies suggest that only a small fraction of the total pools of Prxs and H 2 O 2 effector proteins localized in specific subcellular compartments participates in H 2 O 2 signaling. Development of sensitive tools to selectively detect phosphorylated Prxs and oxidized effector proteins is needed to provide further insight into H 2 O 2 signaling. Antioxid. Redox Signal. 28, 537-557.

H2O2 Synthesis Induced by Irradiation of H2O with Energetic H(+) and Ar(+) Ions at Various Temperatures

Science.gov (United States)

Baragiola, R. A.; Loeffler, M. J.; Raut, U.; Vidal, R. A.; Carlson, R. W.

2004-01-01

The detection of H2O2 on Jupiter's icy satellite Europa by the Galileo NIMS instrument presented a strong evidence for the importance of radiation effects on icy surfaces. A few experiments have investigated whether solar flux of protons incident on Europa ice could cause a significant if any H2O2 production. These published results differ as to whether H2O2 can be formed by ions impacting water at temperatures near 80 K, which are appropriate to Europa. This discrepancy may be a result of the use of different incident ion energies, different vacuum conditions, or different ways of processing the data. The latter possibility comes about from the difficulty of identifying the 3.5 m peroxide OH band on the long wavelength wing of the much stronger water 3.1 m band. The problem is aggravated by using straight line baselines to represent the water OH band with a curvature, in the region of the peroxide band, that increases with temperature. To overcome this problem, we use polynomial baselines that provide good fits to the water band and its derivative.

Photogeneration of H2O2 in SPEEK/PVA aqueous polymer solutions.

Science.gov (United States)

Little, Brian K; Lockhart, PaviElle; Slaten, B L; Mills, G

2013-05-23

Photolysis of air-saturated aqueous solutions containing sulphonated poly(ether etherketone) and poly(vinyl alcohol) results in the generation of hydrogen peroxide. Consumption of oxygen and H2O2 formation are initially concurrent processes with a quantum yield of peroxide generation of 0.02 in stirred or unstirred solutions within the range of 7 ≤ pH ≤ 9. The results are rationalized in terms of O2 reduction by photogenerated α-hydroxy radicals of the polymeric ketone in competition with radical-radical processes that consume the macromolecular reducing agents. Generation of H2O2 is controlled by the photochemical transformation that produces the polymer radicals, which is most efficient in neutral and slightly alkaline solutions. Quenching of the excited state of the polyketone by both H3O(+) and OH(-) affect the yields of the reducing macromolecular radicals and of H2O2. Deprotonation of the α-hydroxy polymeric radicals at pH > 9 accelerate their decay and contribute to suppressing the peroxide yields in basic solutions. Maxima in [H2O2] are observed when illuminations are performed with static systems, where O2 reduction is faster than diffusion of oxygen into the solutions. Under such conditions H2O2 can compete with O2 for the reducing radicals resulting in a consumption of the peroxide.

Direct Synthesis of H{sub 2}O{sub 2} over Ti-Containing Molecular Sieves Supported Gold Catalysts: A Comparative Study for In-situ-H{sub 2}O{sub 2}-ODS of Fuel

Energy Technology Data Exchange (ETDEWEB)

Zhang, Han; Song, Haiyan; Chen, Chunxia; Han, Fuqin; Hu, Shaozheng [Northeast Forestry Univ., Harbin (China); Liu, Guangliang [Univ. of Connecticut, Storrs (United States); Chen, Ping; Zhao, Zhixi [Xinjiang Normal Univ., Urumqi (China)

2013-10-15

Direct synthesis of H{sub 2}O{sub 2} and in situ oxidative desulfurization of model fuel over Au/Ti-HMS and Au/TS-1 catalysts has been comparatively investigated in water or methanol. Maximum amount (82%) of active Au{sup 0} species for H{sub 2}O{sub 2} synthesis was obtained. Au/Ti-HMS and Au/TS-1 exhibited the contrary performances in H{sub 2}O{sub 2} synthesis as CH{sub 3}OH/H{sub 2}O ratio of solvent changed. H{sub 2}O{sub 2} decomposition and hydrogenation in water was inhibited by the introduction of methanol. Effect of O{sub 2}/H{sub 2} ratio on H{sub 2}O{sub 2} concentration, H{sub 2} conversion and H{sub 2}O{sub 2} selectivity revealed a relationship between H{sub 2}O{sub 2} generation and H2 consumption. The highest dibenzothiophene removal rate (83.2%) was obtained over Au/Ti-HMS in methanol at 1.5 of O{sub 2}/H{sub 2} ratio and 60 .deg. C. But removal of thiophene over Au/TS-1 should be performed in water without heating to obtain a high removal rate (61.3%). Meanwhile, H{sub 2} conversion and oxidative desulfurization selectivity of H{sub 2} were presented.

Solar kerosene from H2O and CO2

Science.gov (United States)

Furler, P.; Marxer, D.; Scheffe, J.; Reinalda, D.; Geerlings, H.; Falter, C.; Batteiger, V.; Sizmann, A.; Steinfeld, A.

2017-06-01

The entire production chain for renewable kerosene obtained directly from sunlight, H2O, and CO2 is experimentally demonstrated. The key component of the production process is a high-temperature solar reactor containing a reticulated porous ceramic (RPC) structure made of ceria, which enables the splitting of H2O and CO2 via a 2-step thermochemical redox cycle. In the 1st reduction step, ceria is endo-thermally reduced using concentrated solar radiation as the energy source of process heat. In the 2nd oxidation step, nonstoichiometric ceria reacts with H2O and CO2 to form H2 and CO - syngas - which is finally converted into kerosene by the Fischer-Tropsch process. The RPC featured dual-scale porosity for enhanced heat and mass transfer: mm-size pores for volumetric radiation absorption during the reduction step and μm-size pores within its struts for fast kinetics during the oxidation step. We report on the engineering design of the solar reactor and the experimental demonstration of over 290 consecutive redox cycles for producing high-quality syngas suitable for the processing of liquid hydrocarbon fuels.

Structurally characterized 1,1,3,3-tetramethylguanidine solvated magnesium aryloxide complexes: [Mg(mu-OEt)(DBP)(H-TMG)]2, [Mg(mu-OBc)(DBP)(H-TMG)]2, [Mg(mu-TMBA)(DBP)(H-TMG)]2, [Mg(mu-DPP)(DBP)(H-TMG)]2, [Mg(BMP)2(H-TMG)2], [Mg(O-2,6-Ph2C6H3)2 (H-TMG)2].

Science.gov (United States)

Monegan, Jessie D; Bunge, Scott D

2009-04-06

The synthesis and structural characterization of several 1,1,3,3-tetramethylguanidine (H-TMG) solvated magnesium aryloxide complexes are reported. Bu(2)Mg was successfully reacted with H-TMG, HOC(6)H(3)(CMe(3))(2)-2,6 (H-DBP), and either ethanol, a carboxylic acid, or diphenyl phosphate in a 1:1 ratio to yield the corresponding [Mg(mu-L)(DBP)(H-TMG)](2) where L = OCH(2)CH(3) (OEt, 1), O(2)CC(CH(3))(3) (OBc, 2), O(2)C(C(6)H(2)-2,4,6-(CH(3))(3)) (TMBA, 3), or O(2)P(OC(6)H(5))(2) (DPP, 4). Bu(2)Mg was also reacted with two equivalents of H-TMG and HOC(6)H(3)(CMe(3))-2-(CH(3))-6 (BMP) or HO-2,6-Ph(2)C(6)H(3) to yield [Mg(BMP)(2)(H-TMG)(2)] (5) and [Mg(O-2,6-Ph(2)C(6)H(3))(2)(H-TMG)(2)] (6). Compounds 1-6 were characterized by single-crystal X-ray diffraction. Polymerization of l- and rac-lactide with 1 was found to generate polylactide (PLA). A discussion concerning the relevance of compounds 2 - 4 to the structure of Mg-activated phosphatase enzymes is also provided. The bulk powders for all complexes were found to be in agreement with the crystal structures based on elemental analyses, FT-IR spectroscopy, and (1)H, (13)C and (31)P NMR studies.

Polyaniline as a cathode for O/sub 2/ reduction - kinetics of the reaction with H/sub 2/O/sub 2/ and use of the polymer in a model H/sub 2/O/sub 2/ fuel cell

Energy Technology Data Exchange (ETDEWEB)

Doubova, L.; Mengoli, G.; Musiani, M.M.; Valcher, S.

1989-03-01

Oxygen reduction at a polyaniline cathode occurs in aqueous sulfuric acid through a chemical-electrochemical route which involves the intermediate oxidation of leucoemeraldine to emeraldine with the formation of H/sub 2/O/sub 2/. This paper specifically deals with the conversion of leucoemeraldine to emeraldine by H/sub 2/O/sub 2/ whose kinetics, apparently second order on the charge exchange, are similar to those found for the reaction with O/sub 2/, although they occur at lower rate. The catalytic four electron O/sub 2/ reduction mediated by the Fe(III)/Fe(II) couple which decomposes H/sub 2/O/sub 2/ is not fully achieved. However, polyaniline proved to be a reliable cathode for O/sub 2/, sustaining the working of a model H/sub 2//O/sub 2/ fuel cell.

Differentiating between apparent and actual rates of H2O2 metabolism by isolated rat muscle mitochondria to test a simple model of mitochondria as regulators of H2O2 concentration

Science.gov (United States)

Treberg, Jason R.; Munro, Daniel; Banh, Sheena; Zacharias, Pamela; Sotiri, Emianka

2015-01-01

Mitochondria are often regarded as a major source of reactive oxygen species (ROS) in animal cells, with H2O2 being the predominant ROS released from mitochondria; however, it has been recently demonstrated that energized brain mitochondria may act as stabilizers of H2O2 concentration (Starkov et al. [1]) based on the balance between production and the consumption of H2O2, the later of which is a function of [H2O2] and follows first order kinetics. Here we test the hypothesis that isolated skeletal muscle mitochondria, from the rat, are able to modulate [H2O2] based upon the interaction between the production of ROS, as superoxide/H2O2, and the H2O2 decomposition capacity. The compartmentalization of detection systems for H2O2 and the intramitochondrial metabolism of H2O2 leads to spacial separation between these two components of the assay system. This results in an underestimation of rates when relying solely on extramitochondrial H2O2 detection. We find that differentiating between these apparent rates found when using extramitochondrial H2O2 detection and the actual rates of metabolism is important to determining the rate constant for H2O2 consumption by mitochondria in kinetic experiments. Using the high rate of ROS production by mitochondria respiring on succinate, we demonstrate that net H2O2 metabolism by mitochondria can approach a stable steady-state of extramitochondrial [H2O2]. Importantly, the rate constant determined by extrapolation of kinetic experiments is similar to the rate constant determined as the [H2O2] approaches a steady state. PMID:26001520