Reduction of RuVI≡N to RuIII-NH3 by Cysteine in Aqueous Solution.

Science.gov (United States)

Wang, Qian; Man, Wai-Lun; Lam, William W Y; Yiu, Shek-Man; Tse, Man-Kit; Lau, Tai-Chu

2018-05-21

The reduction of metal nitride to ammonia is a key step in biological and chemical nitrogen fixation. We report herein the facile reduction of a ruthenium(VI) nitrido complex [(L)Ru VI (N)(OH 2 )] + (1, L = N, N'-bis(salicylidene)- o-cyclohexyldiamine dianion) to [(L)Ru III (NH 3 )(OH 2 )] + by l-cysteine (Cys), an ubiquitous biological reductant, in aqueous solution. At pH 1.0-5.3, the reaction has the following stoichiometry: [(L)Ru VI (N)(OH 2 )] + + 3HSCH 2 CH(NH 3 )CO 2 → [(L)Ru III (NH 3 )(OH 2 )] + + 1.5(SCH 2 CH(NH 3 )CO 2 ) 2 . Kinetic studies show that at pH 1 the reaction consists of two phases, while at pH 5 there are three distinct phases. For all phases the rate law is rate = k 2 [1][Cys]. Studies on the effects of acidity indicate that both HSCH 2 CH(NH 3 + )CO 2 - and - SCH 2 CH(NH 3 + )CO 2 - are kinetically active species. At pH 1, the reaction is proposed to go through [(L)Ru IV (NHSCH 2 CHNH 3 CO 2 H)(OH 2 )] 2+ (2a), [(L)Ru III (NH 2 SCH 2 CHNH 3 CO 2 H)(OH 2 )] 2+ (3), and [(L)Ru IV (NH 2 )(OH 2 )] + (4) intermediates. On the other hand, at pH around 5, the proposed intermediates are [(L)Ru IV (NHSCH 2 CHNH 3 CO 2 )(OH 2 )] + (2b) and [(L)Ru IV (NH 2 )(OH 2 )] + (4). The intermediate ruthenium(IV) sulfilamido species, [(L)Ru IV (NHSCH 2 CHNH 3 CO 2 H)(OH 2 )] 2+ (2a) and the final ruthenium(III) ammine species, [(L)Ru III (NH 3 )(MeOH)] + (5) (where H 2 O was replaced by MeOH) have been isolated and characterized by various spectroscopic methods.

Stopped-Flow Spectrophotometric Study of the Kinetics and Mechanism of CO2 Uptake by cis-[Cr(C2O4(BaraNH2(OH22]+ Cation and the Acid-Catalyzed Decomposition of cis-[Cr(C2O4(BaraNH2OCO2]− Anion in Aqueous Solution

Directory of Open Access Journals (Sweden)

Lech Chmurzyński

2011-09-01

Full Text Available The kinetics of CO2 uptake by the cis-[Cr(C2O4(BaraNH2(OH22]+ complex cation and the acid hydrolysis of the cis-[Cr(C2O4(BaraNH2OCO2]− complex anion (where BaraNH2 denotes methyl 3-amino-2,3-dideoxy-b-D-arabino-hexopyranoside were studied using the stopped-flow technique. The reactions under study were investigated in aqueous solution in the 288–308 K temperature range. In the case of the reaction between CO2 and cis-[Cr(C2O4(BaraNH2(OH22]+ cation variable pH values (6.82–8.91 and the constant ionic strength of solution (H+, Na+, ClO4− = 1.0 were used. Carbon dioxide was generated by the reaction between sodium pyruvate and hydrogen peroxide. The acid hydrolysis of cis-[Cr(C2O4(BaraNH2OCO2]− was investigated for varying concentrations of H+ ions (0.01–2.7 M. The obtained results enabled the determination of the number of steps of the studied reactions. Based on the kinetic equations, rate constants were determined for each step. Finally, mechanisms for both reactions were proposed and discussed. Based on the obtained results it was concluded that the carboxylation (CO2 uptake reactions of cis-[Cr(C2O4(BaraNH2(OH22]+ and the decarboxylation (acid hydrolysis of the cis-[Cr(C2O4(BaraNH2OCO2]− are the opposite of each other.

Self-assembly of red-blood-cell-like (NH4)[Fe2(OH)(PO4)2]·2H2O architectures from 2D nanoplates by sonochemical method.

Science.gov (United States)

Wu, Kaipeng; Liu, Diwei; Tang, Yun

2018-01-01

Red-blood-cell-like (RBC-like) (NH 4 )[Fe 2 (OH)(PO 4 ) 2 ]·2H 2 O architectures assembled from 2D nanoplates are successfully synthesized via a facile sonochemical method. XRD measurement indicates that the as-prepared sample is well crystallized with a monoclinic structure. The morphology of the sample is characterized by SEM analysis, which shows that the (NH 4 )[Fe 2 (OH)(PO 4 ) 2 ]·2H 2 O particles exhibit a unique biconcave red blood cell morphology with an average diameter of 4um and thickness of 1.5um. The detailed time-dependent experiments are conducted to investigate the morphological evolution process. It reveals that the ultrasonic time is crucial to the morphology of the products, and the RBC-like (NH 4 )[Fe 2 (OH)(PO 4 ) 2 ]·2H 2 O proceeds in steps of crystallization, formation of thin plates, and the subsequent self-assembly. Compared to the available methods that are typically time-consuming and complicated, this smart sonochemical strategy proposed herein is efficient and simple. Moreover, these obtained special RBC-like architectures will be more fascinating for application in many areas. Copyright © 2017 Elsevier B.V. All rights reserved.

PCBs and OH-PCBs in polar bear mother-cub pairs: a comparative study based on plasma levels in 1998 and 2008.

Science.gov (United States)

Bytingsvik, Jenny; Lie, Elisabeth; Aars, Jon; Derocher, Andrew E; Wiig, Øystein; Jenssen, Bjørn M

2012-02-15

The aim of this study was to examine the plasma concentrations and prevalence of polychlorinated biphenyls (PCBs) and hydroxylated PCB-metabolites (OH-PCBs) in polar bear (Ursus maritimus) mothers (n=26) and their 4 months old cubs-of-the-year (n=38) from Svalbard to gain insight into the mother-cub transfer, biotransformation and to evaluate the health risk associated with the exposure to these contaminants. As samplings were performed in 1997/1998 and 2008, we further investigated the differences in levels and pattern of PCBs between the two sampling years. The plasma concentrations of Σ(21)PCBs (1997/1998: 5710 ± 3090 ng/g lipid weight [lw], 2008: 2560 ± 1500 ng/g lw) and Σ(6)OH-PCBs (1997/1998: 228 ± 60 ng/g wet weight [ww], 2008: 80 ± 38 ng/g ww) in mothers were significantly lower in 2008 compared to in 1997/1998. In cubs, the plasma concentrations of Σ(21)PCBs (1997/1998: 14680 ± 5350 ng/g lw, 2008: 6070 ± 2590 ng/g lw) and Σ(6)OH-PCBs (1997/1998: 98 ± 23 ng/g ww, 2008: 49 ± 21 ng/g ww) were also significantly lower in 2008 than in 1997/1998. Σ(21)PCBs in cubs was 2.7 ± 0.7 times higher than in their mothers. This is due to a significant maternal transfer of these contaminants. In contrast, Σ(6)OH-PCBs in cubs were approximately 0.53 ± 0.16 times the concentration in their mothers. This indicates a lower maternal transfer of OH-PCBs compared to PCBs. The majority of the metabolite/precursor-ratios were lower in cubs compared to mothers. This may indicate that cubs have a lower endogenous capacity to biotransform PCBs to OH-PCBs than polar bear mothers. Exposure to PCBs and OH-PCBs is a potential health risk for polar bears, and the levels of PCBs and OH-PCBs in cubs from 2008 were still above levels associated with health effects in humans and wildlife. Copyright © 2012 Elsevier B.V. All rights reserved.

Photodissociation Spectroscopy of Cold Protonated Synephrine: Surprising Differences between IR-UV Hole-Burning and IR Photodissociation Spectroscopy of the O-H and N-H Modes.

Science.gov (United States)

Nieuwjaer, N; Desfrançois, C; Lecomte, F; Manil, B; Soorkia, S; Broquier, M; Grégoire, G

2018-04-19

We report the UV and IR photofragmentation spectroscopies of protonated synephrine in a cryogenically cooled Paul trap. Single (UV or IR) and double (UV-UV and IR-UV) resonance spectroscopies have been performed and compared to quantum chemistry calculations, allowing the assignment of the lowest-energy conformer with two rotamers depending on the orientation of the phenol hydroxyl (OH) group. The IR-UV hole burning spectrum exhibits the four expected vibrational modes in the 3 μm region, i.e., the phenol OH, C β -OH, and two NH 2 + stretches. The striking difference is that, among these modes, only the free phenol OH mode is active through IRPD. The protonated amino group acts as a proton donor in the internal hydrogen bond and displays large frequency shifts upon isomerization expected during the multiphoton absorption process, leading to the so-called IRMPD transparency. More interestingly, while the C β -OH is a proton acceptor group with moderate frequency shift for the different conformations, this mode is still inactive through IRPD.

Synthesis of 15N-enriched urea (CO(15NH22 from 15NH3, CO, and S in a discontinuous process

Directory of Open Access Journals (Sweden)

C. R. Sant Ana Filho

2012-12-01

Full Text Available CO(15NH22 enriched with the stable isotope 15N was synthesized based on a reaction involving CO, 15NH3, and S in the presence of CH3OH. The method differs from the industrial method; a stainless steel reactor internally lined with polytetrafluoroethylene (PTFE was used in a discontinuous process under low pressure and temperature. The yield of the synthesis was evaluated as a function of the parameters: the amount of reagents, reaction time, addition of H2S, liquid solution and reaction temperature. The results showed that under optimum conditions (1.36, 4.01, and 4.48 g of 15NH3, CO, and S, respectively, 40 ml CH3OH, 40 mg H2S, 100 ºC and 120 min of reaction 1.82 g (yield 76.5% of the compound was obtained per batch. The synthesized CO(15NH22 contained 46.2% N, 0.55% biuret, melting point of 132.55 ºC and did not exhibit isotopic fractionation. The production cost of CO(15NH22 with 90.0 at. % 15N was US$ 238.60 per gram.

[Co(NH3)6]3[Cu4(OH)(CO3)8].2H2O--a new carbonato-copper(II) anion stabilized by extensive hydrogen bonding.

Science.gov (United States)

Abrahams, Brendan F; Haywood, Marissa G; Robson, Richard

2004-04-21

Addition of Co(NH3)6(3+) to aqueous solutions of Cu(II) in excess carbonate promotes the assembly of a new highly charged carbonato-copper(II) anion, [Cu4(OH)(CO3)8](9-), which contains an unusual mu4 hydroxo-bridged square Cu4 arrangement, stabilised in the crystal by no less than forty hydrogen bonds (< 3 Angstrom) to hexammine cations.

Controllable synthesis of (NH4)Fe2(PO4)2(OH)·2H2O using two-step route: Ultrasonic-intensified impinging stream pre-treatment followed by hydrothermal treatment.

Science.gov (United States)

Dong, Bin; Li, Guang; Yang, Xiaogang; Chen, Luming; Chen, George Z

2018-04-01

(NH 4 )Fe 2 (PO 4 ) 2 (OH)·2H 2 O samples with different morphology are successfully synthesized via two-step synthesis route - ultrasonic-intensified impinging stream pre-treatment followed by hydrothermal treatment (UIHT) method. The effects of the adoption of ultrasonic-intensified impinging stream pre-treatment, reagent concentration (C), pH value of solution and hydrothermal reaction time (T) on the physical and chemical properties of the synthesised (NH 4 )Fe 2 (PO 4 ) 2 (OH)·2H 2 O composites and FePO 4 particles were systematically investigated. Nano-seeds were firstly synthesized using the ultrasonic-intensified T-mixer and these nano-seeds were then transferred into a hydrothermal reactor, heated at 170 °C for 4 h. The obtained samples were characterized by utilising XRD, BET, TG-DTA, SEM, TEM, Mastersizer 3000 and FTIR, respectively. The experimental results have indicated that the particle size and morphology of the obtained samples are remarkably affected by the use of ultrasonic-intensified impinging stream pre-treatment, hydrothermal reaction time, reagent concentration, and pH value of solution. When such (NH 4 )Fe 2 (PO 4 ) 2 (OH)·2H 2 O precursor samples were transformed to FePO 4 products after sintering at 650 °C for 10 h, the SEM images have clearly shown that both the precursor and the final product still retain their monodispersed spherical microstructures with similar particle size of about 3 μm when the samples are synthesised at the optimised condition. Copyright © 2017 Elsevier B.V. All rights reserved.

NH4+-NH3 removal from simulated wastewater using UV-TiO2 photocatalysis: effect of co-pollutants and pH.

Science.gov (United States)

Vohra, M S; Selimuzzaman, S M; Al-Suwaiyan, M S

2010-05-01

The main objective of the present study was to investigate the efficiency of titanium dioxide (TiO2) assisted photocatalytic degradation (PCD) process for the removal of ammonium-ammonia (NH4(+)-NH3) from the aqueous phase and in the presence of co-pollutants thiosulfate (S2O3(2-)) and p-cresol (C6H4CH3OH) under varying mixed conditions. For the NH4(+)-NH3 only PCD experiments, results showed higher NH4 -NH3 removal at pH 12 compared to pH 7 and 10. For the binary NH4(+)-NH3/S2O3(2-) studies the respective results indicated a significant lowering in NH4(+)-NH3 PCD in the presence of S2O32- at pH 7/12 whereas at pH 10 a marked increase in NH4(+)-NH3 removal transpired. A similar trend was noted for the p-cresol/NH4(+)-NH3 binary system. Comparing findings from the binary (NH4(+)-NH3/S2O3(2-) and p-cresol/NH4(+)-NH3) and tertiary (NH4(+)-NH3/S2O3(2-)/p-cresol) systems, at pH 10, showed fastest NH4(+)-NH3 removal transpiring for the tertiary system as compared to the binary systems, whereas both the binary systems indicated comparable NH4(+)-NH3 removal trends. The respective details have been discussed.

Stereochemistry of substitution at trico-ordinate phosphorus

DEFF Research Database (Denmark)

Nielsen, John; Dahl, Otto

1984-01-01

A series of reactions of ring-substituted 1,3,2-dioxaphospholanes, 1,3,2-oxazaphospholanes, 1,2-oxaphospholes, and phosphetanes bearing the leaving groups Cl, OR, or NR2 on phosphorus, with the nucleophiles HCl, MeO-, MeOH, PhOH, Me2NH, Et2NH, and [CH 2]5NH have been studied. N.m.r. signals (1H...

Laboratory study on new particle formation from the reaction OH + SO2: influence of experimental conditions, H2O vapour, NH3 and the amine tert-butylamine on the overall process

Directory of Open Access Journals (Sweden)

J. Curtius

2010-08-01

Full Text Available Nucleation experiments starting from the reaction of OH radicals with SO2 have been performed in the IfT-LFT flow tube under atmospheric conditions at 293±0.5 K for a relative humidity of 13–61%. The presence of different additives (H2, CO, 1,3,5-trimethylbenzene for adjusting the OH radical concentration and resulting OH levels in the range (4–300 ×105 molecule cm−3 did not influence the nucleation process itself. The number of detected particles as well as the threshold H2SO4 concentration needed for nucleation was found to be strongly dependent on the counting efficiency of the used counting devices. High-sensitivity particle counters allowed the measurement of freshly nucleated particles with diameters down to about 1.5 nm. A parameterization of the experimental data was developed using power law equations for H2SO4 and H2O vapour. The exponent for H2SO4 from different measurement series was in the range of 1.7–2.1 being in good agreement with those arising from analysis of nucleation events in the atmosphere. For increasing relative humidity, an increase of the particle number was observed. The exponent for H2O vapour was found to be 3.1 representing an upper limit. Addition of 1.2×1011 molecule cm−3 or 1.2×1012 molecule cm−3 of NH3 (range of atmospheric NH3 peak concentrations revealed that NH3 has a measureable, promoting effect on the nucleation rate under these conditions. The promoting effect was found to be more pronounced for relatively dry conditions, i.e. a rise of the particle number by 1–2 orders of magnitude at RH = 13% and only by a factor of 2–5 at RH = 47% (NH3 addition: 1.2×1012 molecule cm−3. Using the amine tert-butylamine instead of NH3, the enhancing impact of the base for nucleation and particle growth appears to be stronger. Tert-butylamine addition of about 1010 molecule cm−3 at RH = 13% enhances particle formation by about two orders of magnitude, while for NH3 only a small or negligible

Characterisation of Ba(OH){sub 2}–Na{sub 2}SO{sub 4}–blast furnace slag cement-like composites for the immobilisation of sulfate bearing nuclear wastes

Energy Technology Data Exchange (ETDEWEB)

Mobasher, Neda; Bernal, Susan A.; Hussain, Oday H. [Immobilisation Science Laboratory, Department of Materials Science and Engineering, The University of Sheffield, Sheffield S1 3JD (United Kingdom); Apperley, David C. [Solid-State NMR Group, Department of Chemistry, Durham University, Durham DH1 3LE (United Kingdom); Kinoshita, Hajime [Immobilisation Science Laboratory, Department of Materials Science and Engineering, The University of Sheffield, Sheffield S1 3JD (United Kingdom); Provis, John L., E-mail: j.provis@sheffield.ac.uk [Immobilisation Science Laboratory, Department of Materials Science and Engineering, The University of Sheffield, Sheffield S1 3JD (United Kingdom)

2014-12-15

Soluble sulfate ions in nuclear waste can have detrimental effects on cementitious wasteforms and disposal facilities based on Portland cement. As an alternative, Ba(OH){sub 2}–Na{sub 2}SO{sub 4}–blast furnace slag composites are studied for immobilisation of sulfate-bearing nuclear wastes. Calcium aluminosilicate hydrate (C–A–S–H) with some barium substitution is the main binder phase, with barium also present in the low solubility salts BaSO{sub 4} and BaCO{sub 3}, along with Ba-substituted calcium sulfoaluminate hydrates, and a hydrotalcite-type layered double hydroxide. This reaction product assemblage indicates that Ba(OH){sub 2} and Na{sub 2}SO{sub 4} act as alkaline activators and control the reaction of the slag in addition to forming insoluble BaSO{sub 4}, and this restricts sulfate availability for further reaction as long as sufficient Ba(OH){sub 2} is added. An increased content of Ba(OH){sub 2} promotes a higher degree of reaction, and the formation of a highly cross-linked C–A–S–H gel. These Ba(OH){sub 2}–Na{sub 2}SO{sub 4}–blast furnace slag composite binders could be effective in the immobilisation of sulfate-bearing nuclear wastes.

EFFECT OF GRAIN SIZE AND ACTIVATION TIME OF ZEOLITE TO ADSORPTION AND DESORPTION OF NH4OH AND KCL AS MODEL OF FERTILIZER-ZEOLITE MIX

Directory of Open Access Journals (Sweden)

Muhammad Prasantio Bimantio

2017-10-01

Full Text Available Zeolites can be used as adsorbent, ion exchange, catalyst, or catalyst carrier. Application of fertilizer use in the zeolite also be one of the interesting topic. Zeolites in a mixture of fertilizer can use to control the release of nutrients. The purpose of this research is to study the effect of grain size and time of the activation of zeolite to adsorption and desorption of NH4OH and KCl as modeling of ZA and KCl fertilizer, to obtain the value of adsorption rate constant (ka and desorption rate constant (kd. This research procedure include: the process of adsorption by adding zeolite with various size and time of activation into a sealed beaker glass and let the adsorption process occurs for 24 hours. After 24 hours, the solution was filtered, the zeolite then put in 100 ml of aquadest into a sealed beaker glass and let the desorption process happened for another 24 hours. Three samples with the largest difference solution concentrations looked for the value of the ka and kd. Zeolite configuration with the largest ka is trialed with fertilizer and compared with the value of ka obtained from modeling. The result for NH4OH adsorbate, -50+60 mesh 2 hours configuration zeolite give the largest ka. For KCl adsorbate, -30+40 mesh 4 hours configuration zeolite give the largest ka. The value between modeling and trials with fertilizers are not much different.

Clean production of corn stover pulp using KOH+NH4OH solution and its kinetic during delignification

Directory of Open Access Journals (Sweden)

Sun Yong

2012-01-01

Full Text Available The self-made KOH together with NH4OH pulping of corn stover was investigated. The combined alkaline system could effectively remove lignin during pulping. There are three stages of lignin removal during delginification. Approximately 90% of lignin could be removed after temperature reached 150ºC for over 30 minutes. The p-hydroxyl phenol groups in lignin could be completely removed during the delignification reaction. The tendency of the increase of the crystalline degree of cellulose is observed with increase of reaction temperature. The kinetics of delignification is found to be the first order with respect to the remained lignin and the 0.4 order with respect to the remained hydroxide concentration. The activation energy of delignification is 23 kJ/mol. The solution obtained from precipitation of lignin is rich in nitrogen, phosphorous, potassium elements and organic matters. Various techniques including FT-IR, GPC, DSC, were applied to characterize the acid precipitated lignin. The result shows that the lignin with the polydispersity of 1.4 still maintains the p-coumaryl, coniferyl, and sinapyl units in its matrix.

Overtone spectroscopy of the hydroxyl stretch vibration in hydroxylamine (NH2OH)

International Nuclear Information System (INIS)

Scott, J.L.; Luckhaus, D.; Brown, S.S.; Crim, F.F.

1995-01-01

We present photoacoustic spectra of the second (3ν OH ), third (4ν OH ), and fourth (5ν OH ) overtone bands of the hydroxyl stretch vibration in hydroxylamine. Asymmetric rotor simulations of the rovibrational contours provide rotational constants and an estimate of the homogeneous linewidth. The fourth overtone band appears anomalously broad relative to the two lower bands, reflecting a sharp increase in the rate of intramolecular vibrational energy redistribution (IVR). By contrast, the calculated density of states increases smoothly with energy. The homogeneous linewidth of the fourth overtone transition is similar to that measured by Luo et al. [J. Chem. Phys. 93, 9194 (1990)] for the predissociative sixth overtone band, supporting the conclusion that the broadening arises from increased (ro)vibrational coupling at an energy between the third and fourth overtone states

The spatial distribution of C2, C3, and NH in comet 2P/Encke

International Nuclear Information System (INIS)

Dorman, Garrett; Pierce, Donna M.; Cochran, Anita L.

2013-01-01

We examine the spatial distribution of C 2 , C 3 , and NH radicals in the coma of comet Encke in order to understand their abundances and distributions in the coma. The observations were obtained from 2003 October 22-24, using the 2.7 m telescope at McDonald Observatory. Building on our original study of CN and OH, we have used our modified version of the vectorial model, which treats the coma as one large cone, in order to reproduce Encke's highly aspherical and asymmetric coma. Our results suggest that NH can be explained by the photodissociation of NH 2 , assuming that NH 2 is produced rapidly from NH 3 in the innermost coma. Our modeling of C 2 and C 3 suggests a multi-generational photodissociation process may be required for their production. Using the results of our previous study, we also obtain abundance ratios with respect to OH and CN. Overall, we find that Encke exhibits typical carbon-chain abundances, and the results are consistent with other studies of comet Encke.

The Spatial Distribution of C2, C3, and NH in Comet 2P/Encke

Science.gov (United States)

Dorman, Garrett; Pierce, Donna M.; Cochran, Anita L.

2013-12-01

We examine the spatial distribution of C2, C3, and NH radicals in the coma of comet Encke in order to understand their abundances and distributions in the coma. The observations were obtained from 2003 October 22-24, using the 2.7 m telescope at McDonald Observatory. Building on our original study of CN and OH, we have used our modified version of the vectorial model, which treats the coma as one large cone, in order to reproduce Encke's highly aspherical and asymmetric coma. Our results suggest that NH can be explained by the photodissociation of NH2, assuming that NH2 is produced rapidly from NH3 in the innermost coma. Our modeling of C2 and C3 suggests a multi-generational photodissociation process may be required for their production. Using the results of our previous study, we also obtain abundance ratios with respect to OH and CN. Overall, we find that Encke exhibits typical carbon-chain abundances, and the results are consistent with other studies of comet Encke.

Dynamic investigation of the diffusion absorption refrigeration system NH3-H2O-H2

Directory of Open Access Journals (Sweden)

Mohamed Izzedine Serge Adjibade

2017-09-01

Full Text Available This paper reports on a numerical and experimental study of a diffusion absorption refrigerator. The performance of the system is examined by computer simulation using MATLAB software and Engineering Equations Solver. A dynamic model is developed for each component of the system and solved numerically in order to predict the transient state of the diffusion absorption refrigeration. The experiment set included 0.04 m3 commercial absorption diffusion refrigerator working with the ammonia-water-hydrogen (NH3-H2O-H2 solution. The transient numerical results were validated with the experimental data. The investigations are focused on the dynamic profile of the temperature of each component. The results obtained agree with the experiment; the relative error between numerical and experimental models doesn’t exceed 15% for all temperatures of each component. The increase of the average ambient temperature from 23.04 °C to 32.56 °C causes an increase of the condensation temperature from 29.46 °C to 37.51 °C, and the best evaporation temperature obtained was 3 °C, with an ambient temperature of 23.04 °C. The results show that a minimum starting temperature of 152 °C and 63.8 W electric power are required to initiate the decrease of evaporation temperature.

NH4(+) Resides Inside the Water 20-mer Cage As Opposed to H3O(+), Which Resides on the Surface: A First Principles Molecular Dynamics Simulation Study.

Science.gov (United States)

Willow, Soohaeng Yoo; Singh, N Jiten; Kim, Kwang S

2011-11-08

Experimental vibrational predissociation spectra of the magic NH4(+)(H2O)20 clusters are close to those of the magic H3O(+)(H2O)20 clusters. It has been assumed that the geometric features of NH4(+)(H2O)20 clusters might be close to those of H3O(+)(H2O)20 clusters, in which H3O(+) resides on the surface. Car-Parrinello molecular dynamics simulations in conjunction with density functional theory calculations are performed to generate the infrared spectra of the magic NH4(+)(H2O)20 clusters. In comparison with the experimental vibrational predissociation spectra of NH4(+)(H2O)20, we find that NH4(+) is inside the cage structure of NH4(+)(H2O)20 as opposed to on the surface structure. This shows a clear distinction between the structures of NH4(+)(H2O)20 and H3O(+)(H2O)20 as well as between the hydration phenomena of NH4(+) and H3O(+).

Immobilization of Mn and NH4 (+)-N from electrolytic manganese residue waste.

Science.gov (United States)

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

2016-06-01

The objective of this work was the immobilization of soluble manganese (Mn) and ammonium nitrogen (NH4 (+)-N) leached from electrolytic manganese residue (EMR). Immobilization of Mn was investigated via carbonation using carbon dioxide (CO2) and alkaline additives. NH4 (+)-N immobilization was evaluated via struvite precipitation using magnesium and phosphate sources. Results indicated that the immobilization efficiency of Mn using CO2 and quicklime (CaO) was higher than using CO2 and sodium hydroxide (NaOH). This higher efficiency was likely due to the slower release of OH(-) during CaO hydrolysis. The immobilization efficiency of Mn was >99.99 % at the CaO:EMR mass ratio of 0.05:1 for 20-min reaction time. The struvite precipitation of NH4 (+)-N was conducted in the carbonated EMR slurry and the immobilization efficiency was 89 % using MgCl2 · 6H2O + Na3PO4 · 12H2O at the Mg:P:N molar ratio of 1.5:1.5:1 for 90-min reaction time. A leaching test showed that the concentrations of Mn and NH4 (+)-N in the filtrate of the treated EMR were 0.2 and 9 mg/L, respectively. The combined immobilization of Mn and NH4 (+)-N was an effective pretreatment method in the harmless treatment of the EMR.

Synthesis of NH4-Substituted Muscovite at 6.3 GPa and 1000°C: Implications for Nitrogen Transport to the Earth's Mantle

Science.gov (United States)

Sokol, A. G.; Sokol, E. V.; Kupriyanov, I. N.; Sobolev, N. V.

2018-03-01

The synthesis of NH4-bearing muscovite at P = 6.3 GPa and T = 1000°C in equilibrium with NH3-H2O fluid is performed. It is determined that the newly formed muscovite is enriched in celadonite minal and contains 370 ppm of NH4. The obtained data make it possible to conclude that ammonium-bearing micas have sufficient thermal stability and can transport crustal nitrogen to the mantle in the presence of a reduced water-ammonia fluid at fO2 less than the values of IW + 2 log units even in the regime of "hot" subduction. The key parameter that determines the efficiency of this mechanism for the deep nitrogen cycle is redox stability of NH4-bearing muscovite at the mantle PT-parameters.

Sonolytic Oxidation of Tc(IVO2nH2O Nanoparticles to Tc(VIIO4 in Aqueous Solution

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M. Zakir

2010-04-01

Full Text Available Sonolysis of a hydrosol of TcO2nH2O was investigated in the Ar- or He- atmosphere. Colloidal TcO2nH2O nanoparticles were irradiated with a 200 kHz and 1.25 W/cm2 ultrasound. It was found that the TcO2nH2O colloids dispersed in an aqueous solution (under Ar or He atmosphere was completely dissolved by ultrasonic irradiation (200 kHz, 200 W. The original brownish black color of the suspension slowly disappeared leaving behind a colorless solution. This change suggests that oxidation of Tc(IV to Tc(VII takes place. The oxidation was almost complete during 30 minutes sonication time under argon atmosphere for initial concentration of 6.0E-5 M. Addition of t-butyl alcohol, an effective radical scavenger which readily reacts with OH radicals, supressed the dissolution of TcO2nH2O colloids. This reaction indicates that TcO2nH2O molecules are oxidized by OH radicals produced in cavitation bubbles.

Theoretical study on the mechanism of CH3NH2 and O3 ...

Indian Academy of Sciences (India)

CH3NH + OH + O2 adducts with one transition state is the most favoured path. Keywords. Ozone; calculation; reaction mechanism; potential energy profile; transition state. 1. Introduction ..... University of. Applied Science, Bielefeld, Germany.

Thermal decomposition of ammonium perchlorate in the presence of Al(OH){sub 3}·Cr(OH){sub 3} nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Zhang, WenJing [Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190 (China); National Engineering Laboratory for Hydrometallurgical Cleaner Production Technology, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Li, Ping, E-mail: lipinggnipil@home.ipe.ac.cn [Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190 (China); National Engineering Laboratory for Hydrometallurgical Cleaner Production Technology, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190 (China); Xu, HongBin; Sun, Randi; Qing, Penghui; Zhang, Yi [Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190 (China); National Engineering Laboratory for Hydrometallurgical Cleaner Production Technology, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190 (China)

2014-03-01

Highlights: • The amorphous Al(OH){sub 3}·Cr(OH){sub 3} nanoparticles containing surface hydroxyls were prepared by a hydrolytic co-precipitation method. • The Al(OH){sub 3}·Cr(OH){sub 3} nanoparticles show excellent catalytic ability for AP decomposition. • The surface hydroxyls and amorphous form of Al(OH){sub 3}·Cr(OH){sub 3} nanoparticles promote ammonia oxidation of AP. - Abstract: An Al(OH){sub 3}·Cr(OH){sub 3} nanoparticle preparation procedure and its catalytic effect and mechanism on thermal decomposition of ammonium perchlorate (AP) were investigated using transmission electron microscopy (TEM), X-ray diffraction (XRD), thermogravimetric analysis and differential scanning calorimetry (TG-DSC), X-ray photoelectron spectroscopy (XPS), and thermogravimetric analysis and mass spectroscopy (TG-MS). In the preparation procedure, TEM, SAED, and FT-IR showed that the Al(OH){sub 3}·Cr(OH){sub 3} particles were amorphous particles with dimensions in the nanometer size regime containing a large amount of surface hydroxyl under the controllable preparation conditions. When the Al(OH){sub 3}·Cr(OH){sub 3} nanoparticles were used as additives for the thermal decomposition of AP, the TG-DSC results showed that the addition of Al(OH){sub 3}·Cr(OH){sub 3} nanoparticles to AP remarkably decreased the onset temperature of AP decomposition from approximately 450 °C to 245 °C. The FT-IR, RS and XPS results confirmed that the surface hydroxyl content of the Al(OH){sub 3}·Cr(OH){sub 3} nanoparticles decreased from 67.94% to 63.65%, and Al(OH){sub 3}·Cr(OH){sub 3} nanoparticles were limitedly transformed from amorphous to crystalline after used as additives for the thermal decomposition of AP. Such behavior of Al(OH){sub 3}·Cr(OH){sub 3} nanoparticles promoted the oxidation of NH{sub 3} of AP to decompose to N{sub 2}O first, as indicated by the TG-MS results, accelerating the AP thermal decomposition.

Hydroxylated polychlorinated biphenyls decrease circulating steroids in female polar bears (Ursus maritimus).

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Gustavson, Lisa; Ciesielski, Tomasz M; Bytingsvik, Jenny; Styrishave, Bjarne; Hansen, Martin; Lie, Elisabeth; Aars, Jon; Jenssen, Bjørn M

2015-04-01

As a top predator in the Arctic food chain, polar bears (Ursus maritimus) are exposed to high levels of persistent organic pollutants (POPs). Because several of these compounds have been reported to alter endocrine pathways, such as the steroidogenesis, potential disruption of the sex steroid synthesis by POPs may cause implications for reproduction by interfering with ovulation, implantation and fertility. Blood samples were collected from 15 female polar bears in Svalbard (Norway) in April 2008. The concentrations of nine circulating steroid hormones; dehydroepiandrosterone (DHEA), androstenedione (AN), testosterone (TS), dihydrotestosterone (DHT), estrone (E1), 17α-estradiol (αE2), 17β-estradiol (βE2), pregnenolone (PRE) and progesterone (PRO) were determined. The aim of the study was to investigate associations among circulating levels of specific POP compounds and POP-metabolites (hydroxylated PCBs [OH-PCBs] and hydroxylated PBDEs [OH-PBDEs]), steroid hormones, biological and capture variables in female polar bears. Inverse correlations were found between circulating levels of PRE and AN, and circulating levels of OH-PCBs. There were no significant relationships between the steroid concentrations and other analyzed POPs or the variables capture date and capture location (latitude and longitude), lipid content, condition and body mass. Although statistical associations do not necessarily represent direct cause-effect relationships, the present study indicate that OH-PCBs may affect the circulating levels of AN and PRE in female polar bears and that OH-PCBs thus may interfere with the steroid homeostasis. Increase in PRO and a decrease in AN concentrations suggest that the enzyme CYP17 may be a potential target for OH-PCBs. In combination with natural stressors, ongoing climate change and contaminant exposure, it is possible that OH-PCBs may disturb the reproductive potential of polar bears. Copyright © 2015 Elsevier Inc. All rights reserved.

Air-stable hydrogen generation materials and enhanced hydrolysis performance of MgH2-LiNH2 composites

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Ma, Miaolian; Ouyang, Liuzhang; Liu, Jiangwen; Wang, Hui; Shao, Huaiyu; Zhu, Min

2017-08-01

Hydrolysis of materials in water can be a promising solution of onsite hydrogen generation for realization of hydrogen economy. In this work, it was the first time that the MgH2-LiNH2 composites were explored as air-stable hydrolysis system for hydrogen generation. The MgH2-LiNH2 composites with different composition ratios were synthesized by ball milling with various durations and the hydrogen generation performances of the composite samples were investigated and compared. X-ray diffraction, X-ray photoelectron spectroscopy and scanning electron microscopy techniques were adopted to elucidate the performance improvement mechanisms. The hydrolysis properties of MgH2 were found to be significantly enhanced by the introduction of LiNH2. The 4MgH2-LiNH2 composite ball milled for 5 h can generate 887.2 mL g-1 hydrogen in 1 min and 1016 mL g-1 in 50 min, one of the best results so far for Mg based hydrolysis materials. The LiOH·H2O and NH4OH phases of hydrolysis products from LiNH2 may prevent formation of Mg(OH)2 passivation layer on the surface and supply enough channels for hydrolysis of MgH2. The MgH2-LiNH2 composites appeared to be very stable in air and no obvious negative effect on kinetics and hydrogen generation yield was observed. These good performances demonstrate that the studied MgH2-LiNH2 composites can be a promising and practicable hydrogen generation system.

Increase in Ice Nucleation Efficiency of Feldspars, Kaolinite and Mica in Dilute NH3 and NH4+-containing Solutions

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Kumar, A.; Marcolli, C.; Luo, B.; Krieger, U. K.; Peter, T.

2017-12-01

Semivolatile species present in the atmosphere are prone to adhere to mineral dust particle surfaces during long range transport, and could potentially change the particle surface properties and its ice nucleation (IN) efficiency. Immersion freezing experiments were performed with microcline (K-feldspar), known to be highly IN active, suspended in aqueous solutions of ammonia, (NH4)2SO4, NH4HSO4, NH4NO3, NH4Cl, Na2SO4, H2SO4, K2SO4 and KCl to investigate the effect of solutes on the IN efficiency. Freezing of emulsified droplets investigated with a differential scanning calorimeter (DSC) showed that the heterogeneous ice nucleation temperatures deviate from the water activity-based IN theory, describing heterogeneous ice nucleation temperatures as a function of solution water activity by a constant offset with respect to the ice melting point curve (Zobrist et al. 2008). IN temperatures enhanced up to 4.5 K were observed for very dilute NH3 and NH4+-containing solutions while a decrease was observed as the concentration was further increased. For all solutes with cations other than NH4+, the IN efficiency decreased. An increase of the IN efficiency in very dilute NH3 and NH4+-containing solutions followed by a decrease with increasing concentration was also observed for sanidine (K-feldspar) and andesine (Na/Ca-feldspar). This is an important indication towards specific chemical interactions between solutes and the feldspar surface which is not captured by the water activity-based IN theory. A similar trend is present but less pronounced in case of kaolinite and mica, while quartz is barely affected. We hypothesize that the hydrogen bonding of NH3 molecules with surface -OH groups could be the reason for the enhanced freezing temperatures in dilute ammonia and ammonium containing solutions as they could form an ice-like overlayer providing hydrogen bonding groups for ice to nucleate on top of it. This implies to possibilities of enhanced IN efficiency, especially

Reflectance spectroscopy (0.35-8 μm) of ammonium-bearing minerals and qualitative comparison to Ceres-like asteroids

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Berg, Breanne L.; Cloutis, Edward A.; Beck, Pierre; Vernazza, Pierre; Bishop, Janice L.; Takir, Driss; Reddy, Vishnu; Applin, Daniel; Mann, Paul

2016-02-01

Ammonium-bearing minerals have been suggested to be present on Mars, Ceres, and various asteroids and comets. We undertook a systematic study of the spectral reflectance properties of ammonium-bearing minerals and compounds that have possible planetary relevance (i.e., ammonium carbonates, chlorides, nitrates, oxalates, phosphates, silicates, and sulfates). Various synthetic and natural NH4+-bearing minerals were analyzed using reflectance spectroscopy in the long-wave ultraviolet, visible, near-infrared, and mid-infrared regions (0.35-8 μm) in order to identify spectral features characteristic of the NH4+ molecule, and to evaluate if and how these features vary among different species. Mineral phases were confirmed through structural and compositional analyses using X-ray diffraction, X-ray fluorescence, and elemental combustion analysis. Characteristic absorption features associated with NH4 can be seen in the reflectance spectra at wavelengths as short as ∼1 μm. In the near-infrared region, the most prominent absorption bands are located near 1.6, 2.0, and 2.2 μm. Absorption features characteristic of NH4+ occurred at slightly longer wavelengths in the mineral-bound NH4+ spectra than for free NH4+ for most of the samples. Differences in wavelength position are attributable to various factors, including differences in the type and polarizability of the anion(s) attached to the NH4+, degree and type of hydrogen bonding, molecule symmetry, and cation substitutions. Multiple absorption features, usually three absorption bands, in the mid-infrared region between ∼2.8 and 3.8 μm were seen in all but the most NH4-poor sample spectra, and are attributed to fundamentals, combinations, and overtones of stretching and bending vibrations of the NH4+ molecule. These features appear even in reflectance spectra of water-rich samples which exhibit a strong 3 μm region water absorption feature. While many of the samples examined in this study have NH4 absorption bands

Reflectance spectroscopy (0.35–8 μm) of ammonium-bearing minerals and qualitative comparison to Ceres-like asteroids

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Berg, Breanne L.; Cloutis, Edward A.; Beck, P.; Vernazza, P.; Bishop, Janice L; Takir, Driss; Reddy, V.; Applin, D.; Mann, Paul

2016-01-01

Ammonium-bearing minerals have been suggested to be present on Mars, Ceres, and various asteroids and comets. We undertook a systematic study of the spectral reflectance properties of ammonium-bearing minerals and compounds that have possible planetary relevance (i.e., ammonium carbonates, chlorides, nitrates, oxalates, phosphates, silicates, and sulfates). Various synthetic and natural NH4+-bearing minerals were analyzed using reflectance spectroscopy in the long-wave ultraviolet, visible, near-infrared, and mid-infrared regions (0.35–8 μm) in order to identify spectral features characteristic of the NH4+ molecule, and to evaluate if and how these features vary among different species. Mineral phases were confirmed through structural and compositional analyses using X-ray diffraction, X-ray fluorescence, and elemental combustion analysis. Characteristic absorption features associated with NH4 can be seen in the reflectance spectra at wavelengths as short as ∼1 μm. In the near-infrared region, the most prominent absorption bands are located near 1.6, 2.0, and 2.2 μm. Absorption features characteristic of NH4+ occurred at slightly longer wavelengths in the mineral-bound NH4+ spectra than for free NH4+ for most of the samples. Differences in wavelength position are attributable to various factors, including differences in the type and polarizability of the anion(s) attached to the NH4+, degree and type of hydrogen bonding, molecule symmetry, and cation substitutions. Multiple absorption features, usually three absorption bands, in the mid-infrared region between ∼2.8 and 3.8 μm were seen in all but the most NH4-poor sample spectra, and are attributed to fundamentals, combinations, and overtones of stretching and bending vibrations of the NH4+ molecule. These features appear even in reflectance spectra of water-rich samples which exhibit a strong 3 μm region water absorption feature. While many of the samples examined in this study have NH4 absorption

Laboratory procedure for sizing and electroless nickel plating assembled steel bearings

International Nuclear Information System (INIS)

Wright, R.R.; Petit, G.S.

1976-01-01

The bearing is placed in a holder and degreased in methyl chloroform. The entire bearing is etched in hydrochloric acid and sized in an ammonium bifluoride-hydrogen peroxide solution (NH 4 F.HF--H 2 O 2 ). The bearing is removed from the holder, activated in hydrochloric acid and plated with 0.001 in. of nickel in a plating tumbler immersed in a heated electroless nickel plating bath. The bearing is water-rinsed and air-dried

A multi-level quantum mechanics and molecular mechanics study of SN2 reaction at nitrogen: NH2Cl + OH(-) in aqueous solution.

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Lv, Jing; Zhang, Jingxue; Wang, Dunyou

2016-02-17

We employed a multi-level quantum mechanics and molecular mechanics approach to study the reaction NH2Cl + OH(-) in aqueous solution. The multi-level quantum method (including the DFT method with both the B3LYP and M06-2X exchange-correlation functionals and the CCSD(T) method, and both methods with the aug-cc-pVDZ basis set) was used to treat the quantum reaction region in different stages of the calculation in order to obtain an accurate potential of mean force. The obtained free energy activation barriers at the DFT/MM level of theory yielded a big difference of 21.8 kcal mol(-1) with the B3LYP functional and 27.4 kcal mol(-1) with the M06-2X functional respectively. Nonetheless, the barrier heights become very close when shifted from DFT to CCSD(T): 22.4 kcal mol(-1) and 22.9 kcal mol(-1) at CCSD(T)(B3LYP)/MM and CCSD(T)(M06-2X)/MM levels of theory, respectively. The free reaction energy obtained using CCSD(T)(M06-2X)/MM shows an excellent agreement with the one calculated using the available gas-phase data. Aqueous solution plays a significant role in shaping the reaction profile. In total, the water solution contributes 13.3 kcal mol(-1) and 14.6 kcal mol(-1) to the free energy barrier heights at CCSD(T)(B3LYP)/MM and CCSD(T)(M06-2X)/MM respectively. The title reaction at nitrogen is a faster reaction than the corresponding reaction at carbon, CH3Cl + OH(-).

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

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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.

Bioaccumulation and biotransformation of brominated and chlorinated contaminants and their metabolites in ringed seals (Pusa hispida) and polar bears (Ursus maritimus) from East Greenland.

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Letcher, Robert J; Gebbink, Wouter A; Sonne, Christian; Born, Erik W; McKinney, Melissa A; Dietz, Rune

2009-11-01

We report on the comparative bioaccumulation, biotransformation and/or biomagnification from East Greenland ringed seal (Pusa hispida) blubber to polar bear (Ursus maritimus) tissues (adipose, liver and brain) of various classes and congeners of persistent chlorinated and brominated contaminants and metabolic by-products: polychlorinated biphenyls (PCBs), chlordanes (CHLs), hydroxyl (OH-) and methylsulfonyl (MeSO(2)-) PCBs, polybrominated biphenyls (PBBs), OH-PBBs, polybrominated diphenyl ether (PBDE) and hexabromocyclododecane (HBCD) flame retardants and OH- and methoxyl (MeO-) PBDEs, 2,2-dichloro-bis(4-chlorophenyl)ethene (p,p'-DDE), 3-MeSO(2)-p,p'-DDE, pentachlorophenol (PCP) and 4-OH-heptachlorostyrene (4-OH-HpCS). We detected all of the investigated contaminants in ringed seal blubber with high frequency, the main diet of East Greenland bears, with the exception of OH-PCBs and 4-OH-HpCS, which indicated that these phenolic contaminants were likely of metabolic origin and formed in the bears from accumulated PCBs and octachlorostyrene (OCS), respectively, rather than being bioaccumulated from a seal blubber diet. For all of the detectable sum of classes or individual organohalogens, in general, the ringed seal to polar bear mean BMFs for SigmaPCBs, p,p'-DDE, SigmaCHLs, SigmaMeSO(2)-PCBs, 3-MeSO(2)-p,p'-DDE, PCP, SigmaPBDEs, total-(alpha)-HBCD, SigmaOH-PBDEs, SigmaMeO-PBDEs and SigmaOH-PBBs indicated that these organohalogens bioaccumulate, and in some cases there was tissue-specific biomagnification, e.g., BMFs for bear adipose and liver ranged from 2 to 570. The blood-brain barrier appeared to be effective in minimizing brain accumulation as BMFs were bear tissues appeared to be mainly accumulated from the seal blubber rather than being metabolic formed from PBDEs in the bears. In vitro PBDE depletion assays using polar bear hepatic microsomes, wherein the rate of oxidative metabolism of PBDE congeners was very slow, supported the probability that accumulation

Tissue-specific congener composition of organohalogen and metabolite contaminants in East Greenland polar bears (Ursus maritimus)

International Nuclear Information System (INIS)

Gebbink, Wouter A.; Sonne, Christian; Dietz, Rune; Kirkegaard, Maja; Riget, Frank F.; Born, Erik W.; Muir, Derek C.G.; Letcher, Robert J.

2008-01-01

Congener patterns of the major organohalogen contaminant classes of PCBs, PBDEs and their metabolites and/or by-products (OH-PCBs, MeSO 2 -PCBs, OH-PBDEs and MeO-PBDEs) were examined in adipose tissue, liver, brain and blood of East Greenland polar bears (Ursus maritimus). PCB, OH-PCB, MeSO 2 -PCB and PBDE congener patterns showed significant differences (p ≤ 0.05) mainly in the liver and the brain relative to the adipose tissue and the blood. OH-PBDEs and MeO-PBDEs were not detected in the brain and liver, but had different patterns in blood versus the adipose tissue. Novel OH-polybrominated biphenyls (OH-PBBs), one tri- and two tetra-brominated OH-PBBs were detected in all tissues and blood. Congener pattern differences among tissues and blood are likely due to a combination of factors, e.g., biotransformation and retention in the liver, retention in the blood and blood-brain barrier transport. Our findings suggest that different congener pattern exposures to these classes of contaminants should be considered with respect to potential target tissue-specific effects in East Greenland polar bears. - Tissues-specific (adipose tissue, liver, brain and blood) differences exist for the congener patterns of PCBs, PBDEs and their metabolites/degradation products in East Greenland polar bears

A conformation-selective IR-UV study of the dipeptides Ac-Phe-Ser-NH2 and Ac-Phe-Cys-NH2: probing the SH···O and OH···O hydrogen bond interactions.

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Yan, Bin; Jaeqx, Sander; van der Zande, Wim J; Rijs, Anouk M

2014-06-14

The conformational preferences of peptides are mainly controlled by the stabilizing effect of intramolecular interactions. In peptides with polar side chains, not only the backbone but also the side chain interactions determine the resulting conformations. In this paper, the conformational preferences of the capped dipeptides Ac-Phe-Ser-NH2 (FS) and Ac-Phe-Cys-NH2 (FC) are resolved under laser-desorbed jet cooling conditions using IR-UV ion dip spectroscopy and density functional theory (DFT) quantum chemistry calculations. As serine (Ser) and cysteine (Cys) only differ in an OH (Ser) or SH (Cys) moiety; this subtle alteration allows us to study the effect of the difference in hydrogen bonding for an OH and SH group in detail, and its effect on the secondary structure. IR absorption spectra are recorded in the NH stretching region (3200-3600 cm(-1)). In combination with quantum chemical calculations the spectra provide a direct view of intramolecular interactions. Here, we show that both FS as FC share a singly γ-folded backbone conformation as the most stable conformer. The hydrogen bond strength of OH···O (FS) is stronger than that of SH···O (FC), resulting in a more compact gamma turn structure. A second conformer is found for FC, showing a β turn interaction.

Replacement of Oxygen by Sulfur in Small Organic Molecules. 3. Theoretical Studies on the Tautomeric Equilibria of the 2OH and 4OH-Substituted Oxazole and Thiazole and the 3OH and 4OH-Substituted Isoxazole and Isothiazole in the Isolated State and in Solution

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Peter I. Nagy

2016-07-01

Full Text Available This follow-up paper completes the author’s investigations to explore the in-solution structural preferences and relative free energies of all OH-substituted oxazole, thiazole, isoxazole, and isothiazole systems. The polarizable continuum dielectric solvent method calculations in the integral-equation formalism (IEF-PCM were performed at the DFT/B97D/aug-cc-pv(q+(dz level for the stable neutral tautomers with geometries optimized in dichloromethane and aqueous solution. With the exception of the predictions for the predominant tautomers of the 3OH isoxazole and isothiazole, the results of the IEF-PCM calculations for identifying the most stable tautomer of the given species in the two selected solvents agreed with those from experimental investigations. The calculations predict that the hydroxy proton, with the exception for the 4OH isoxazole and 4OH isothiazole, moves preferentially to the ring nitrogen or to a ring carbon atom in parallel with the development of a C=O group. The remaining, low-fraction OH tautomers will not be observable in the equilibrium compositions. Relative solvation free energies obtained by the free energy perturbation method implemented in Monte Carlo simulations are in moderate accord with the IEF-PCM results, but consideration of the ΔGsolv/MC values in calculating ΔGstot maintains the tautomeric preferences. It was revealed from the Monte Carlo solution structure analyses that the S atom is not a hydrogen-bond acceptor in any OH-substituted thiazole or isothiazole, and the OH-substituted isoxazole and oxazole ring oxygens may act as a weak hydrogen-bond acceptor at most. The molecules form 1.0−3.4 solute−water hydrogen bonds in generally unexplored numbers at some specific solute sites. Nonetheless, hydrogen-bond formation is favorable with the NH, C=O and OH groups.

Theoretical study on the gas adsorption capacity and selectivity of CPM-200-In/Mg and CPM-200-In/Mg-X (-X = -NH2, -OH, -N, -F).

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Liu, Xiao-le; Chen, Guang-Hui; Wang, Xiu-Jun; Li, Peng; Song, Yi-Bing; Li, Rui-Yan

2017-11-15

The adsorption capacities of a heterometallic metal-organic framework (CPM-200-In/Mg) to VOCs (HCHO, C 2 H 4 , CH 4 , C 2 H 2 , C 3 H 8 , C 2 H 6 , C 2 H 3 Cl, C 2 H 2 Cl 2 , CH 2 Cl 2 and CHCl 3 ) and some inorganic gas molecules (HCN, SO 2 , NO, CO 2 , CO, H 2 S and NH 3 ), as well as its selectivity in ternary mixture systems of natural gas and post-combustion flue gas are theoretically explored at the grand canonical Monte Carlo (GCMC) and density functional theory (DFT) levels. It is shown that CPM-200-In/Mg is suitable for the adsorption of VOCs, particularly for HCHO (up to 0.39 g g -1 at 298 K and 1 bar), and the adsorption capacities of some inorganic gas molecules such as SO 2 , H 2 S and CO 2 match well with the sequence of their polarizability (SO 2 > H 2 S > CO 2 ). The large adsorption capacities of HCN and HCHO in the framework result from the strong interaction between adsorbates and metal centers, based on analyzing the radial distribution functions (RDF). Comparing C 2 H 4 and CH 4 molecules interacting with CPM-200-In/Mg by VDW interaction, we speculate that the high adsorption capacities of their chlorine derivatives in the framework could be due to the existence of halogen bonding or strong electrostatic and VDW interactions. It is found that the basic groups, including -NH 2 , -N and -OH, can effectively improve both the adsorption capacities and selectivity of CPM-200-In/Mg for harmful gases. Note that the adsorption capacity of CPM-200-In/Mg-NH 2 (site 2) (245 cm 3 g -1 ) for CO 2 exceeded that of MOF-74-Mg (228 cm 3 g -1 ) at 273 K and 1 bar and that for HCHO can reach 0.41 g g -1 , which is almost twice that of 438-MOF and nearly 45 times of that in active carbon. Moreover, for natural gas mixtures, the decarburization and desulfurization abilities of CPM-200-In/Mg-NH 2 (site 2) have exceeded those of the MOF-74 series, while for post-combustion flue gas mixtures, the desulfurization ability of CPM-200-In/Mg-NH 2 (site 2) is still

Investigating the mechanism for maintaining eucalcemia despite immobility and anuria in the hibernating American black bear (Ursus americanus).

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Seger, Rita L; Cross, Randal A; Rosen, Clifford J; Causey, Robert C; Gundberg, Caren M; Carpenter, Thomas O; Chen, Tai C; Halteman, William A; Holick, Michael F; Jakubas, Walter J; Keisler, Duane H; Seger, Richard M; Servello, Frederick A

2011-12-01

Ursine hibernation uniquely combines prolonged skeletal unloading, anuria, pregnancy, lactation, protein recycling, and lipolysis. This study presents a radiographic and biochemical picture of bone metabolism in free-ranging, female American black bears (Ursus americanus) that were active (spring bears and autumn bears) or hibernating (hibernating bears). Hibernating bears included lactating and non-lactating individuals. We measured serum calcium, albumin, inorganic phosphate, creatinine, bone specific alkaline phosphatase (BSALP), CTX, parathyroid hormone, insulin-like growth factor-I (IGF-l), leptin, 25-hydroxyvitamin D [25(OH)D], 1,25-dihydroxyvitamin D [1,25(OH)(2)D] and sclerostin from 35 to 50 tranquilized hibernating bears and 14 to 35 tranquilized spring bears. We compared metacarpal cortical indices (MCI), measured by digital X-ray radiogrammetry, from 60 hunter-killed autumn bears and 79 tranquilized, hibernating bears. MCI was greater in autumn than winter in younger bears, but showed no seasonal difference in older bears. During hibernation eucalcemia was maintained, BSALP was suppressed, and CTX was in the range expected for anuria. During hibernation 1,25(OH)(2)D was produced despite anuria. 1,25(OH)(2)D and IGF-I were less in hibernating than spring bears. In a quarter of hibernating bears, sclerostin was elevated. Leptin was greater in hibernating than spring bears. In hibernating bears, leptin correlated positively with BSALP in non-lactating bears and with CTX in lactating bears. Taken together the biochemical and radiographic findings indicate that during hibernation, bone turnover was persistent, balanced, and suppressed; bone resorption was lower than expected for an unloaded skeleton; and there was no unloading-induced bone loss. The skeleton appears to perceive that it was loaded when it was actually unloaded during hibernation. However, at the level of sclerostin, the skeleton recognized that it was unloaded. During hibernation leptin

Comparison of high-titer lactic acid fermentation from NaOH- and NH3-H2O2-pretreated corncob by Bacillus coagulans using simultaneous saccharification and fermentation

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Zhang, Zhenting; Xie, Yuejiao; He, Xiaolan; Li, Xinli; Hu, Jinlong; Ruan, Zhiyong; Zhao, Shumiao; Peng, Nan; Liang, Yunxiang

2016-01-01

Lignocellulose is one of the most abundant renewable feedstocks that has attracted considerable attention as a substrate for biofuel and biochemical production. One such biochemical product, lactic acid, is an important fermentation product because of its great potential for the production of biodegradable and biocompatible polylactic acid. High-titer lactic acid production from lignocellulosic materials has been achieved recently; however, it requires biodetoxification or results in large amounts of waste washing water. In this study, we employed two alkaline pretreatment methods and compared their effects on lactic acid fermentation of pretreated corncob by Bacillus coagulans LA204 using fed-batch simultaneous saccharification and fermentation under non-sterile conditions. The lactic acid titer, yield, and productivity from 16% (w/w) NaOH-pretreated and washed corncob were 122.99 g/L, 0.77 g/g corncob, and 1.37 g/L/h, respectively, and from 16% NH3-H2O2-pretreated and washed corncob were 118.60 g/L, 0.74 g/g corncob, and 1.32 g/L/h, respectively. Importantly, the lactic acid titer, yield, and productivity from 18.4% NH3-H2O2-pretreated and unwashed corncob by using fed-batch simultaneous saccharification and fermentation reached 79.47 g/L, 0.43 g/g corncob, and 1.10 g/L/h, respectively, demonstrating that this method is possible for industrial applications and saves washing water. PMID:27853308

Comparison of high-titer lactic acid fermentation from NaOH- and NH3-H2O2-pretreated corncob by Bacillus coagulans using simultaneous saccharification and fermentation.

Science.gov (United States)

Zhang, Zhenting; Xie, Yuejiao; He, Xiaolan; Li, Xinli; Hu, Jinlong; Ruan, Zhiyong; Zhao, Shumiao; Peng, Nan; Liang, Yunxiang

2016-11-17

Lignocellulose is one of the most abundant renewable feedstocks that has attracted considerable attention as a substrate for biofuel and biochemical production. One such biochemical product, lactic acid, is an important fermentation product because of its great potential for the production of biodegradable and biocompatible polylactic acid. High-titer lactic acid production from lignocellulosic materials has been achieved recently; however, it requires biodetoxification or results in large amounts of waste washing water. In this study, we employed two alkaline pretreatment methods and compared their effects on lactic acid fermentation of pretreated corncob by Bacillus coagulans LA204 using fed-batch simultaneous saccharification and fermentation under non-sterile conditions. The lactic acid titer, yield, and productivity from 16% (w/w) NaOH-pretreated and washed corncob were 122.99 g/L, 0.77 g/g corncob, and 1.37 g/L/h, respectively, and from 16% NH 3 -H 2 O 2 -pretreated and washed corncob were 118.60 g/L, 0.74 g/g corncob, and 1.32 g/L/h, respectively. Importantly, the lactic acid titer, yield, and productivity from 18.4% NH 3 -H 2 O 2 -pretreated and unwashed corncob by using fed-batch simultaneous saccharification and fermentation reached 79.47 g/L, 0.43 g/g corncob, and 1.10 g/L/h, respectively, demonstrating that this method is possible for industrial applications and saves washing water.

Compatibility of hydrogarnet, Ca3Al2(SiO4)x(OH)4(3−x), with sulfate and carbonate-bearing cement phases: 5–85 °C

International Nuclear Information System (INIS)

Okoronkwo, Monday Uchenna; Glasser, Fredrik Paul

2016-01-01

The stable existence of hydrogarnet in Portland cement compositions cured at temperatures below 55 °C has long been predicted from application of equilibrium thermodynamics. However hydrogarnet is not often reported in hydrated commercial Portland cements. The substitutions (SO 4 –CO 3 –OH) in AFm have previously been shown to stabilise AFm to higher temperatures and raise the temperature at which AFm converts to Si-free hydrogarnet, C 3 AH 6 . But unanswered question remains about the compatibility of AFm and AFm solid solutions with Si-substituted hydrogarnet, Ca 3 Al 2 (SiO 4 ) x (OH) 4(3 − x) . Phase relations of C 3 AH 6 and Ca 3 Al 2 (SiO 4 ) x (OH) 4(3 − x) at sulfate and carbonate activities conditioned respectively by (gypsum and SO 4 -AFt) and (calcite and CO 3 -AFt) have been determined experimentally in the range 5–85 °C. The results confirm the instability of Si-free hydrogarnet with carbonate and sulfate-bearing cement phases, but do indicate that a range of silica-substituted hydrogarnet solid solutions are stable under conditions likely to be encountered in blended cement systems.

Kinetics of struvite to newberyite transformation in the precipitation system MgCl2-NH4H2PO4NaOH-H2O.

Science.gov (United States)

Babić-Ivancić, Vesna; Kontrec, Jasminka; Brecević, Ljerka; Kralj, Damir

2006-10-01

The influence of the initial reactant concentrations on the composition of the solid phases formed in the precipitation system MgCl(2)-NH(4)H(2)PO(4)-NaOH-H(2)O was investigated. The precipitation diagram constructed shows the approximate concentration regions within which struvite, newberyite, and their mixtures exist at 25 degrees C and an aging time of 60 min. It was found that immediately after mixing the reactant solutions, struvite (MgNH(4)PO(4).6H(2)O) precipitated in nearly the whole concentration area, while newberyite (MgHPO(4).3H(2)O) appeared mostly within the region of the excess of magnesium concentration. It was also found that after aging time of 60 min the precipitation domain of struvite alone is much broader than that of newberyite or the domain of their coexistence, and shows that struvite is more abundant in the systems in which the initial concentration of ammonium phosphate is higher than that of magnesium. The kinetics of struvite to newberyite transformation (conversion) was systematically studied under the conditions of different initial reactant concentrations and different initial pH in the systems in which a mixture of both phases precipitated spontaneously. The struvite to newberyite conversion period was found to be strongly related to the ratio of initial supersaturations, S(N)/S(S), rather than to the any particular physical quantity that can describe and predict the behavior of the precipitation system. Experimental data suggest a solution-mediated process as a most possible transformation mechanism. Along with a continuous monitoring of the changes in the liquid phase, the content of struvite in the solid phase was estimated by means of a Fourier transform infrared (FT-IR) method, developed for this particular precipitation system.

Cooperativity of hydrogen-bonded networks in 7-azaindole(CH3OH)n (n=2,3) clusters evidenced by IR-UV ion-dip spectroscopy and natural bond orbital analysis.

Science.gov (United States)

Sakota, Kenji; Kageura, Yutaka; Sekiya, Hiroshi

2008-08-07

IR-UV ion-dip spectra of the 7-azaindole (7AI)(CH(3)OH)(n) (n=1-3) clusters have been measured in the hydrogen-bonded NH and OH stretching regions to investigate the stable structures of 7AI(CH(3)OH)(n) (n=1-3) in the S(0) state and the cooperativity of the H-bonding interactions in the H-bonded networks. The comparison of the IR-UV ion-dip spectra with IR spectra obtained by quantum chemistry calculations shows that 7AI(CH(3)OH)(n) (n=1-3) have cyclic H-bonded structures, where the NH group and the heteroaromatic N atom of 7AI act as the proton donor and proton acceptor, respectively. The H-bonded OH stretch fundamental of 7AI(CH(3)OH)(2) is remarkably redshifted from the corresponding fundamental of (CH(3)OH)(2) by 286 cm(-1), which is an experimental manifestation of the cooperativity in H-bonding interaction. Similarly, two localized OH fundamentals of 7AI(CH(3)OH)(3) also exhibit large redshifts. The cooperativity of 7AI(CH(3)OH)(n) (n=2,3) is successfully explained by the donor-acceptor electron delocalization interactions between the lone-pair orbital in the proton acceptor and the antibonding orbital in the proton donor in natural bond orbital (NBO) analyses.

A new crystal modification of diammonium hydrogen phosphate, (NH42(HPO4

Directory of Open Access Journals (Sweden)

Bernhard Spingler

2010-04-01

Full Text Available The addition of hexafluoridophosphate salts (ammonium, silver, thallium or potassium is usually used to precipitate complex cations from aqueous solutions. It has long been known that PF6− is sensitive towards hydrolysis under acidic conditions [Gebala & Jones (1969. J. Inorg. Nucl. Chem. 31, 771–776; Plakhotnyk et al. (2005. J. Fluorine Chem. 126, 27–31]. During the course of our investigation into coinage metal complexes of diphosphine ligands, we used ammonium hexafluoridophosphate in order to crystallize [Ag(diphosphine2]PF6 complexes. From these solutions we always obtained needle-like crystals which turned out to be the title compound, 2NH4+·HPO42−. It was received as the hydrolysis product of NH4PF6. The crystals are a new modification of diammonium hydrogen phosphate. In contrast to the previously published polymorph [Khan et al. (1972. Acta Cryst. B28, 2065–2069], Z′ of the title compound is 2. In the new modification of the title compound, there are eight molecules of (NH42(HPO4 in the unit cell. The structure consists of PO3OH and NH4 tetrahedra, held together by O—H...O and N—H...O hydrogen bonds.

Evaluation of Low-Noise, Improved-Bearing-Contact Spiral Bevel Gears

National Research Council Canada - National Science Library

Lewicki, Davide

2003-01-01

.... Experimental tests were performed on the OH-58D helicopter main-rotor transmission in the NASA Glenn 500-hp Helicopter Transmission Test Stand Low-noise, improved-bearing- contact spiral-bevel gears...

Depletion of the heaviest stable N isotope is associated with NH4+/NH3 toxicity in NH4+-fed plants.

Science.gov (United States)

Ariz, Idoia; Cruz, Cristina; Moran, Jose F; González-Moro, María B; García-Olaverri, Carmen; González-Murua, Carmen; Martins-Loução, Maria A; Aparicio-Tejo, Pedro M

2011-05-16

In plants, nitrate (NO3-) nutrition gives rise to a natural N isotopic signature (δ15N), which correlates with the δ15N of the N source. However, little is known about the relationship between the δ15N of the N source and the 14N/15N fractionation in plants under ammonium (NH4+) nutrition. When NH4+ is the major N source, the two forms, NH4+ and NH3, are present in the nutrient solution. There is a 1.025 thermodynamic isotope effect between NH3 (g) and NH4+ (aq) which drives to a different δ15N. Nine plant species with different NH4+-sensitivities were cultured hydroponically with NO3- or NH4+ as the sole N sources, and plant growth and δ15N were determined. Short-term NH4+/NH3 uptake experiments at pH 6.0 and 9.0 (which favours NH3 form) were carried out in order to support and substantiate our hypothesis. N source fractionation throughout the whole plant was interpreted on the basis of the relative transport of NH4+ and NH3. Several NO3--fed plants were consistently enriched in 15N, whereas plants under NH4+ nutrition were depleted of 15N. It was shown that more sensitive plants to NH4+ toxicity were the most depleted in 15N. In parallel, N-deficient pea and spinach plants fed with 15NH4+ showed an increased level of NH3 uptake at alkaline pH that was related to the 15N depletion of the plant. Tolerant to NH4+ pea plants or sensitive spinach plants showed similar trend on 15N depletion while slight differences in the time kinetics were observed during the initial stages. The use of RbNO3 as control discarded that the differences observed arise from pH detrimental effects. This article proposes that the negative values of δ15N in NH4+-fed plants are originated from NH3 uptake by plants. Moreover, this depletion of the heavier N isotope is proportional to the NH4+/NH3 toxicity in plants species. Therefore, we hypothesise that the low affinity transport system for NH4+ may have two components: one that transports N in the molecular form and is associated with

Depletion of the heaviest stable N isotope is associated with NH4+/NH3 toxicity in NH4+-fed plants

Science.gov (United States)

2011-01-01

Background In plants, nitrate (NO3-) nutrition gives rise to a natural N isotopic signature (δ15N), which correlates with the δ15N of the N source. However, little is known about the relationship between the δ15N of the N source and the 14N/15N fractionation in plants under ammonium (NH4+) nutrition. When NH4+ is the major N source, the two forms, NH4+ and NH3, are present in the nutrient solution. There is a 1.025 thermodynamic isotope effect between NH3 (g) and NH4+ (aq) which drives to a different δ15N. Nine plant species with different NH4+-sensitivities were cultured hydroponically with NO3- or NH4+ as the sole N sources, and plant growth and δ15N were determined. Short-term NH4+/NH3 uptake experiments at pH 6.0 and 9.0 (which favours NH3 form) were carried out in order to support and substantiate our hypothesis. N source fractionation throughout the whole plant was interpreted on the basis of the relative transport of NH4+ and NH3. Results Several NO3--fed plants were consistently enriched in 15N, whereas plants under NH4+ nutrition were depleted of 15N. It was shown that more sensitive plants to NH4+ toxicity were the most depleted in 15N. In parallel, N-deficient pea and spinach plants fed with 15NH4+ showed an increased level of NH3 uptake at alkaline pH that was related to the 15N depletion of the plant. Tolerant to NH4+ pea plants or sensitive spinach plants showed similar trend on 15N depletion while slight differences in the time kinetics were observed during the initial stages. The use of RbNO3 as control discarded that the differences observed arise from pH detrimental effects. Conclusions This article proposes that the negative values of δ15N in NH4+-fed plants are originated from NH3 uptake by plants. Moreover, this depletion of the heavier N isotope is proportional to the NH4+/NH3 toxicity in plants species. Therefore, we hypothesise that the low affinity transport system for NH4+ may have two components: one that transports N in the

Depletion of the heaviest stable N isotope is associated with NH4+/NH3 toxicity in NH4+-fed plants

Directory of Open Access Journals (Sweden)

Martins-Loução Maria A

2011-05-01

Full Text Available Abstract Background In plants, nitrate (NO3- nutrition gives rise to a natural N isotopic signature (δ15N, which correlates with the δ15N of the N source. However, little is known about the relationship between the δ15N of the N source and the 14N/15N fractionation in plants under ammonium (NH4+ nutrition. When NH4+ is the major N source, the two forms, NH4+ and NH3, are present in the nutrient solution. There is a 1.025 thermodynamic isotope effect between NH3 (g and NH4+ (aq which drives to a different δ15N. Nine plant species with different NH4+-sensitivities were cultured hydroponically with NO3- or NH4+ as the sole N sources, and plant growth and δ15N were determined. Short-term NH4+/NH3 uptake experiments at pH 6.0 and 9.0 (which favours NH3 form were carried out in order to support and substantiate our hypothesis. N source fractionation throughout the whole plant was interpreted on the basis of the relative transport of NH4+ and NH3. Results Several NO3--fed plants were consistently enriched in 15N, whereas plants under NH4+ nutrition were depleted of 15N. It was shown that more sensitive plants to NH4+ toxicity were the most depleted in 15N. In parallel, N-deficient pea and spinach plants fed with 15NH4+ showed an increased level of NH3 uptake at alkaline pH that was related to the 15N depletion of the plant. Tolerant to NH4+ pea plants or sensitive spinach plants showed similar trend on 15N depletion while slight differences in the time kinetics were observed during the initial stages. The use of RbNO3 as control discarded that the differences observed arise from pH detrimental effects. Conclusions This article proposes that the negative values of δ15N in NH4+-fed plants are originated from NH3 uptake by plants. Moreover, this depletion of the heavier N isotope is proportional to the NH4+/NH3 toxicity in plants species. Therefore, we hypothesise that the low affinity transport system for NH4+ may have two components: one that

Self-Assembled Hollow Spheres of β-Ni(OH) 2 and Their Derived Nanomaterials

KAUST Repository

Zhang, Shengmao

2009-03-10

This paper describes a novel solution-based chemical process to architect hollow spheres of β-Ni(OH) 2 with controllable sizes in submicrometer and micrometer regimes. In the synthesis, starting nickel salt (nitrate) is first converted to 6-coordinated nickel ion complex [Ni(EDA) 3] 2+ (bidentate ligand EDA = C 2H 4(NH 2) 2) to avoid rapid solid formation. Hollow and core - shell β-Ni(OH) 2 spheres can be obtained with this template-free approach under one-pot conditions. The β-Ni(OH) 2 spheres are constructed from petal-like nanobuilding units which in turn are formed from even smaller nanocrystallites. The obtained porous β-Ni(OH) 2 spheres have a large specific surface area and show a unimodal pore-size distribution. Several preparative parameters have been examined and optimized. In particular, the concentration of divalent nickel in the starting solutions plays an important role in controlling thickness of the petal-like β-Ni(OH) 2 flakes and diameter of spheres. The β-Ni(OH) 2 flakes self-assemble into final spherical products through a donut-like structural intermediate. Furthermore, the β-Ni(OH) 2 hollow spheres can be used as solid precursors to synthesize other nanostructured derivatives. In this work, phase pure inorganic nanostructures, carbon nanotube (CNT) - inorganic nanocomposites, and inorganic - inorganic nanocom-posites (e.g., NiO, Ni, NiO/Ni, Ni/β-Ni(OH) 2, CNTs/NiO, CNTs/Ni, Ni@CNTs, Fe(OH) 3/β-Ni(OH) 2, Co(OH) 2/β-Ni(OH) 2, and Mg(OH) 2/β-Ni(OH) 2) have been prepared via solid-state thermal decomposition, gas-phase reduction, solution-based reduction, surface oxidation, chemical vapor deposition, and liquid-phase deposition. A greater picture for general synthesis of Ni-containing nanomaterials is thus obtained. © 2009 American Chemical Society.

Porous Ni3(NO3)2(OH)4 nano-sheets for supercapacitors: Facile synthesis and excellent rate performance at high mass loadings

Science.gov (United States)

Shi, Mingjie; Cui, Mangwei; Kang, Litao; Li, Taotao; Yun, Shan; Du, Jing; Xu, Shoudong; Liu, Ying

2018-01-01

For supercapacitors, pores in electrode materials can accelerate chemical reaction kinetics by shortening ion diffusion distances and by enlarging electrolyte/electrode interfaces. This article describes a simple one-step route for the preparation of pure-phase porous Ni3(NO3)2(OH)4 nano-sheets by directly heating a mild Ni(NO3)2 and urea solution. During heating, urea decomposed into NH3·H2O, which provided a suitable alkaline environment for the formation of Ni3(NO3)2(OH)4 nano-sheets. Meanwhile, the side product, NH4NO3, created numerous pores as a pore-forming agent. After NH4NO3 removal, the specific surface areas and pore volumes of products were boosted by ∼180-times (from 0.61 to 113.12 m2/g) and ∼90-times (from 3.40 × 10-3 to 3.17 × 10-1 m2/g), respectively. As a cathode material of supercapacitor, the porous Ni3(NO3)2(OH)4 nano-sheets exhibited a high specific capacitance of 1094 F/g at an ultrahigh mass loading of 17.55 mg/cm2, leading to an impressive areal capacitance of 19.2 F/cm2. Furthermore, a Ni3(NO3)2(OH)4 nano-sheet//commercial active carbon asymmetric supercapacitor was constructed and delivered an energy density of 33.2 Wh/Kg at a power density of 190.5 W/Kg, based on the mass of active materials on both electrodes.

Synthesis and structure determination of new open-framework chromium carboxylate MIL-105 or CrIII(OH).{O2C-C6(CH3)4-CO2}.nH2O

International Nuclear Information System (INIS)

Serre, Christian; Millange, Franck; Devic, Thomas; Audebrand, Nathalie; Van Beek, Wouter

2006-01-01

Two new three-dimensional chromium(III) dicarboxylate, MIL-105 or Cr III (OH).{O 2 C-C 6 (CH 3 ) 4 -CO 2 }.nH 2 O, have been obtained under hydrothermal conditions, and their structures solved using X-ray powder diffraction data. Both solids are structural analogs of the known Cr benzenedicarboxylate compound (MIL-53). Both contain trans corner-sharing CrO 4 (OH) 2 octahedral chains connected by tetramethylterephthalate di-anions. Each chain is linked by the ligands to four other chains to form a three-dimensional framework with an array of 1D pores channels. The pores of the high temperature form of the solid, MIL-105ht, are empty. However, MIL-105ht re-hydrates at room temperature to finally give MIL-105lt with pores channels filled with free water molecules (lt: low temperature form; ht: high temperature form). The thermal behaviour of the two solids has been investigated using TGA. Crystal data for MIL-105ht: monoclinic space group C2/c with a = 19.653(1) A, b = 9.984(1) A, c = 6.970(1) A, β = 110.67(1) o and Z = 4. Crystal data for MIL-105lt: orthorhombic space group Pnam with a = 17.892(1) A, b = 11.165(1) A, c = 6.916(1) A and Z = 4

New insights into Cu/SSZ-13 SCR catalyst acidity. Part I: Nature of acidic sites probed by NH 3 titration

Energy Technology Data Exchange (ETDEWEB)

Luo, Jinyong; Gao, Feng; Kamasamudram, Krishna; Currier, Neal; Peden, Charles H. F.; Yezerets, Aleksey

2017-04-01

In this work we investigated an unusual acidity feature of a Cu/SSZ-13 catalyst used in selective catalytic reduction of NOx with NH3 (NH3-SCR). In particular, this catalyst showed two distinct NH3 desorption peaks in NH3-TPD measurements, in contrast to single, unresolved desorption peaks observed for other Cu-exchanged zeolites conventionally used in the SCR studies, including its isostructural but chemically different analogue Cu/SAPO-34. We further observed that the intensities of the two TPD peaks, which represented the amount of stored NH3, changed in opposite directions in response to progressive mild hydrothermal aging, while the total storage capacity was preserved. We proposed an explanation for this remarkable behavior, by using model reference samples and additional characterization techniques. At least three NH3 storage sites were identified: two distinct populations of Cu sites responsible for low-temperature NH3 storage, and Brønsted acid sites responsible for high-temperature NH3 storage. Contrary to the commonly accepted mechanism that Brønsted acid site loss during hydrothermal aging is driven by dealumination, we concluded that the decline in the number of Brønsted acid sites upon mild hydrothermal aging for Cu/SSZ-13 was not due to dealumination, but rather transformation of Cu sites, i.e., gradual conversion of ZCuOH (Cu2+ singly coordinated with Zeolite) to Z2Cu (Cu2+ doubly coordinated with Zeolite). This transformation was responsible for the increased low-temperature desorption peak in NH3-TPD since each ZCuOH adsorbed ~1 NH3 molecule while each Z2Cu adsorbed ~2 NH3 molecules under the conditions used here. These findings were used in Part II of this series of studies to develop a method for quantifying hydrothermal ageing of industrial Cu/SSZ-13 SCR catalysts. Authors would like to thank Randall Jines for his help with collecting the reactor data, Nancy W. Washton for measuring the NMR data and Tamas Varga for in-situ XRD measurements

Formation of simple nitrogen hydrides NH and NH2 at cryogenic temperatures through N + NH3→ NH + NH2 reaction: dark cloud chemistry of nitrogen.

Science.gov (United States)

Nourry, Sendres; Krim, Lahouari

2016-07-21

Although NH3 molecules interacting with ground state nitrogen atoms N((4)S) seem not to be a very reactive system without providing additional energy to initiate the chemical process, we show through this study that, in the solid phase, at very low temperature, NH3 + N((4)S) reaction leads to the formation of the amidogen radical NH2. Such a dissociation reaction previously thought to occur exclusively through UV photon or energetic particle irradiation is in this work readily occurring just by stimulating the mobility of N((4)S)-atoms in the 3-10 K temperature range in the solid sample. The N((4)S)-N((4)S) recombination may be the source of metastable molecular nitrogen N2(A), a reactive species which might trigger the NH3 dissociation or react with ground state nitrogen atoms N((4)S) to form excited nitrogen atoms N((4)P/(2)D) through energy transfer processes. Based on our obtained results, it is possible to propose reaction pathways to explain the NH2 radical formation which is the first step in the activation of stable species such as NH3, a chemical induction process that, in addition to playing an important role in the origin of molecular complexity in interstellar space, is known to require external energy supplies to occur in the gas phase.

Synthesis and properties of ternary (K, NH4, H3O)-jarosites precipitated from Acidithiobacillus ferrooxidans cultures in simulated bioleaching solutions

International Nuclear Information System (INIS)

Sandy Jones, F.; Bigham, Jerry M.; Gramp, Jonathan P.; Tuovinen, Olli H.

2014-01-01

The purpose of this study was to synthesize a series of solid solution jarosites by biological oxidation of ferrous iron at pH 2.2–4.4 and ambient temperature in media containing mixtures of K + (0, 1, 4, 6, 12, 31 mM) and NH 4 + (6.1, 80, 160, 320 mM). The starting material was a liquid medium for Acidithiobacillus ferrooxidans comprised of 120 mM FeSO 4 solution and mineral salts at pH 2.2. Following inoculation with A. ferrooxidans, the cultures were incubated in shake flasks at 22 °C. As bacteria oxidized ferrous iron, ferric iron hydrolyzed and precipitated as jarosite-group minerals (AFe 3 (SO 4 ) 2 (OH) 6 ) and/or schwertmannite (idealized formula Fe 8 O 8 (OH) 6 (SO 4 )·nH 2 O). The precipitates were characterized by X-ray diffraction (XRD), elemental analysis, and Munsell color. Schwertmannite was the dominant mineral product at low combinations of K + (≤ 4 mM) and NH 4 + (≤ 80 mM) in the media. At higher single or combined concentrations, yellowish jarosite phases were produced, and Munsell hue provided a sensitive means of detecting minor schwertmannite in the oxidation products. Although the hydrated ionic radii of K + and NH 4 + are similar, K + greatly facilitated the formation of a jarosite phase compared to NH 4 + . Unit cell and cell volume calculations from refinements of the powder XRD patterns indicated that the jarosite phases produced were mostly ternary (K, NH 4 , H 3 O)-solid solutions that were also deficient in structural Fe, especially at low NH 4 contents. Thus, ferric iron precipitation from the simulated bioleaching systems yielded solid solutions of jarosite with chemical compositions that were dependent on the relative concentrations of K + and NH 4 + in the synthesis media. No phase separations involving discrete, end-member K-jarosite or NH 4 -jarosite were detected in the un-aged precipitates. - Highlights: • Fe(III) precipitates formed in A. ferrooxidans culture solutions were characterized. • The monovalent cation

NH3 (10-00) in the pre-stellar core L1544

DEFF Research Database (Denmark)

Caselli, P.; Bizzocchi, L.; Keto, E.

2017-01-01

GHz and study the abundance profile of ammonia across the pre-stellar core L1544 to test current theories of its physical and chemical structure. Recently calculated collisional coefficients have been included in our non-LTE radiative transfer code to reproduce Herschel observations. A gas......Pre-stellar cores represent the initial conditions in the process of star and planet formation, therefore it is important to study their physical and chemical structure. Because of their volatility, nitrogen-bearing molecules are key to study the dense and cold gas present in pre-stellar cores....... The NH3 rotational transition detected with Herschel-HIFI provides a unique combination of sensitivity and spectral resolution to further investigate physical and chemical processes in pre-stellar cores. Here we present the velocity-resolved Herschel-HIFI observations of the ortho-NH3(10-00) line at 572...

Different transport behaviors of NH4 (+) and NH3 in transmembrane cyclic peptide nanotubes.

Science.gov (United States)

Zhang, Mingming; Fan, Jianfen; Xu, Jian; Weng, Peipei; Lin, Huifang

2016-10-01

Two water-filled transmembrane cyclic peptide nanotubes (CPNTs) of 8×cyclo-(WL)n=4,5/POPE were chosen to investigate the dependences of the transport properties of the positive NH4 (+) and neutral NH3 on the channel radius. Molecular dynamic simulations revealed that molecular charge, size, ability to form H-bonds and channel radius all significantly influence the behaviors of NH4 (+) and NH3 in a CPNT. Higher electrostatic interactions, more H-bonds, and water-bridges were found in the NH4 (+) system, resulting in NH4 (+) meeting higher energy barriers, while NH3 can enter, exit and permeate the channels effortlessly. This work sheds a first light on the differences between the mechanisms of NH4 (+) and NH3 moving in a CPNT at an atomic level. Graphical Abstract Snapshot of the simulation system of NH4 (+)_octa-CPNT with an NH4 (+) initially positioned at one mouth of the tube, PMF profiles for single NH4 (+) ion and NH3 molecule moving through water-filled transmembrane CPNTs of 8×cyclo-(WL)n=4,5/POPE and sketch graphs of the possible H-bond forms of NH3 and NH4 (+) with the neighboring water.

Morphology Controlled Synthesis of α-GaO(OH Nanoparticles: Thermal Conversion to Ga2O3 and Photocatalytic Properties

Directory of Open Access Journals (Sweden)

Ayse Dulda

2016-01-01

Full Text Available Morphology controlled α-GaO(OH particles have been synthesized via precipitation method which allows the tuning of relative growth rates of crystal facets. The effects of alkali addition rate and the type of alkali on the growth rates of the crystal facets during hydrolysis were also investigated. XRD and TG analysis confirmed that there was a phase transition from GaO(OH to Ga2O3 when precursor sample was calcined to 750°C. The single phase α-Ga2O3 was obtained after thermal treatment of NaOH precipitated precursor, while β-Ga2O3 was formed when the urea or NH4OH precipitated precursor was calcinated. Furthermore, the thermal, spectral, and photocatalytic properties connected to the crystal structure and morphology were discussed.

Mineralogical and chemical assessment of concrete damaged by the oxidation of sulfide-bearing aggregates: Importance of thaumasite formation on reaction mechanisms

International Nuclear Information System (INIS)

Rodrigues, A.; Duchesne, J.; Fournier, B.; Durand, B.; Rivard, P.; Shehata, M.

2012-01-01

Damages in concrete containing sulfide-bearing aggregates were recently observed in the Trois-Rivières area (Quebec, Canada), characterized by rapid deterioration within 3 to 5 years after construction. A petrographic examination of concrete core samples was carried out using a combination of tools including: stereomicroscopic evaluation, polarized light microscopy, scanning electron microscopy, X-ray diffraction and electron microprobe analysis. The aggregate used to produce concrete was an intrusive igneous rock with different metamorphism degrees and various proportions of sulfide minerals. In the rock, sulfide minerals were often surrounded by a thin layer of carbonate minerals (siderite). Secondary reaction products observed in the damaged concrete include “rust” mineral forms (e.g. ferric oxyhydroxides such as goethite, limonite (FeO (OH) nH 2 O) and ferrihydrite), gypsum, ettringite and thaumasite. In the presence of water and oxygen, pyrrhotite oxidizes to form iron oxyhydroxides and sulphuric acid. The acid then reacts with the phases of the cement paste/aggregate and provokes the formation of sulfate minerals. Understanding both mechanisms, oxidation and internal sulfate attack, is important to be able to duplicate the damaging reaction in laboratory conditions, thus allowing the development of a performance test for evaluating the potential for deleterious expansion in concrete associated with sulfide-bearing aggregates.

DFT study on the attacking mechanisms of H and OH radicals to G-C and A-T base pairs in water

Energy Technology Data Exchange (ETDEWEB)

Okutsu, N.; Shimamura, K.; Shimizu, E.; Kurita, N., E-mail: kurita@cs.tut.ac.jp [Department of Computer Science and Engineering, Toyohashi University of Technology, Toyohashi, Aichi, 441-8580 (Japan); Shulga, S. [Institute for Food Biotechnology and Genomics, National Academy of Sciences of Ukraine, Kyiv (Ukraine); Danilov, V. I. [Institute of Molecular Biology and Genetics, National Academy of Sciences of Ukraine, Kyiv (Ukraine)

2016-02-01

To elucidate the effect of radicals on DNA base pairs, we investigated the attacking mechanism of OH and H radicals to the G-C and A-T base pairs, using the density functional theory (DFT) calculations in water approximated by the continuum solvation model. The DFT calculations revealed that the OH radical abstracts the hydrogen atom of a NH{sub 2} group of G or A base and induces a tautomeric reaction for an A-T base pair more significantly than for a G-C base pair. On the other hand, the H radical prefers to bind to the Cytosine NH{sub 2} group of G-C base pair and induce a tautomeric reaction from G-C to G*-C*, whose activation free energy is considerably small (−0.1 kcal/mol) in comparison with that (42.9 kcal/mol) for the reaction of an A-T base pair. Accordingly, our DFT calculations elucidated that OH and H radicals have a significant effect on A-T and G-C base pairs, respectively. This finding will be useful for predicting the effect of radiation on the genetic information recorded in the base sequences of DNA duplexes.

DFT study on the attacking mechanisms of H and OH radicals to G-C and A-T base pairs in water

International Nuclear Information System (INIS)

Okutsu, N.; Shimamura, K.; Shimizu, E.; Kurita, N.; Shulga, S.; Danilov, V. I.

2016-01-01

To elucidate the effect of radicals on DNA base pairs, we investigated the attacking mechanism of OH and H radicals to the G-C and A-T base pairs, using the density functional theory (DFT) calculations in water approximated by the continuum solvation model. The DFT calculations revealed that the OH radical abstracts the hydrogen atom of a NH 2 group of G or A base and induces a tautomeric reaction for an A-T base pair more significantly than for a G-C base pair. On the other hand, the H radical prefers to bind to the Cytosine NH 2 group of G-C base pair and induce a tautomeric reaction from G-C to G*-C*, whose activation free energy is considerably small (−0.1 kcal/mol) in comparison with that (42.9 kcal/mol) for the reaction of an A-T base pair. Accordingly, our DFT calculations elucidated that OH and H radicals have a significant effect on A-T and G-C base pairs, respectively. This finding will be useful for predicting the effect of radiation on the genetic information recorded in the base sequences of DNA duplexes

Biodistribution and tumor uptake of C60(OH)x in mice

International Nuclear Information System (INIS)

Ji Zhiqiang; Sun Hongfang; Wang Haifang; Xie Qunying; Liu Yuangfang; Wang Zheng

2006-01-01

Radiolabeling of fullerol, 125 I-C 60 (OH) x , was performed by the traditional chloramine-T method. The C-I covalent bond in I-C 60 (OH) x was characterized by X-ray photoelectron spectroscopy (XPS) that was sufficiently stable for in vivo study. Laser light scattering spectroscopy clearly showed that C 60 (OH) x aggregated to large nanoparticle clumps with a wide range of distribution. The clumps formed were also visualized by transmission electron microscope (TEM). We examined the biodistribution and tumor uptake of C 60 (OH) x in five mouse bearing tumor models, including mouse H22 hepatocarcinoma, human lung giantcellcarcinoma PD, human colon cancer HCT-8, human gastric cancer MGC803, and human OS732 osteosarcoma. The accumulation ratios of 125 I-C 60 (OH) x in mouse H22 hepatocarcinoma to that in normal muscle tissue (T/N) and blood (T/B) at 1, 6, 24 and 72 h, reveal that 125 I-C 60 (OH) x gradually accumulates in H22 tumor, and retains for a quite long period (e.g., T/N 3.41, T/B 3.94 at 24 h). For the other four tumor models, the T/N ratio at 24 h ranges within 1.21-6.26, while the T/B ratio ranges between 1.23 and 4.73. The accumulation of C 60 (OH) x in tumor is mostly due to the enhanced permeability and retention effect (EPR) and the phagocytosis of mononuclear phagocytes. Hence, C 60 (OH) x might serve as a photosensitizer in the photodynamic therapy of some kinds of tumor

Kinetics and branching ratios of the reactions NH2+NO2->N2O+H2O and NH2+NO2->H2NO+NO studied by pulse radiolysis combined with time-resolved infrared diode laser spectroscopy

DEFF Research Database (Denmark)

Meunier, H.; Pagsberg, Palle Bjørn; Sillesen, A.

1996-01-01

studied by monitoring the decay of NH2 and the simultaneous formation of N2O and NO by time-resolved infrared diode laser spectroscopy. The decay rate of NH2 was studied as a function of NO2 concentration to obtain an overall rate constant k(NH2 + NO2) = (1.35 +/- 0.15) X 10(-11) molecule(-1) cm(3) s(-1...

Exploring the crystallization landscape of cadmium bis(N-hydroxyethyl, N-isopropyldithiocarbamate), Cd[S2CN(iPr)CH2CH2OH]2

International Nuclear Information System (INIS)

Tan, Yee Seng; Halim, Siti Nadiah Abdul; Tiekink, Edward R.T.; Sunway Univ., Bandar Sunway

2016-01-01

Crystallization of Cd[S 2 CN(iPr)CH 2 CH 2 OH] 2 from ethanol yields the coordination polymer [{Cd[S 2 CN(iPr)CH 2 CH 2 OH] 2 }.EtOH] ∞ (1) within 3 h. When the solution is allowed to stand for another hour, the needles begin to dissolve and prisms emerge of the supramolecular isomer (SI), binuclear {Cd[S 2 CN(iPr)CH 2 CH 2 OH] 2 } 2 .2EtOH (2). These have been fully characterized spectroscopically and by X-ray crystallography. Polymeric 1 has 2-fold symmetry and features dithiocarbamate ligands coordinating two octahedral Cd atoms in a μ 2 κ 2 -tridentate mode. Binuclear 2 is centrosymmetric with two ligands being μ 2 κ 2 -tridentate as for 1 but the other two being κ 2 -chelating leading to square pyramidal geometries. The conversion of the kinetic crystallization product, 1, to thermodynamic 2 is irreversible but transformations mediated by recrystallization (ethanol and acetonitrile) to related literature SI species, namely coordination polymer [{Cd[S 2 CN(iPr)CH 2 CH 2 OH] 2 } 3 .MeCN] ∞ and binuclear {Cd[S 2 CN(iPr)CH 2 CH 2 OH] 2 } 2 .2H 2 O.2MeCN, are demonstrated, some of which are reversible. Three other crystallization outcomes are described whereby crystal structures were obtained for the 1:2 co-crystal {Cd[S 2 CN(iPr)CH 2 CH 2 OH] 2 } 2 :2[3-(propan-2-yl)-1,3-oxazolidine-2-thione] (3), the salt co-crystal [iPrNH 2 (CH 2 CH 2 OH)] 4 [SO 4 ] 2 {Cd[S 2 CN(iPr)CH 2 CH 2 OH] 2 } 2 (4) and the salt [iPrNH 2 (CH 2 CH 2 OH)]{Cd[S 2 CN(iPr)CH 2 CH 2 OH] 3 } (5). These arise as a result of decomposition/oxidation of the dithiocarbamate ligands. In each of 3 and 4 the binuclear {Cd[S 2 CN(iPr)CH 2 CH 2 OH] 2 } 2 SI, as in 2, is observed strongly suggesting a thermodynamic preference for this form.

The O-H Bond Dissociation Energies of Substituted Phenols and Proton Affinities of Substituted Phenoxide Ions: A DFT Study

Directory of Open Access Journals (Sweden)

Tadafumi Uchimaru

2002-04-01

Full Text Available Abstract: The accurate O-H bond dissociation enthalpies for a series of meta and para substituted phenols (X-C6H4-OH, X=H, F, Cl, CH3, OCH3, OH, NH2, CF3, CN, and NO2 have been calculated by using the (ROB3LYP procedure with 6-311G(d,p and 6-311++G(2df,2p basis sets. The proton affinities of the corresponding phenoxide ions (XC6H4-O- have also been computed at the same level of theory. The effect of change of substituent position on the energetics of substituted phenols has been analyzed. The correlations of Hammett’s substituent constants with the bond dissociation enthalpies of the O-H bonds of phenols and proton affinities of phenoxide ions have been explored.

NH3 and NH4+ permeability in aquaporin-expressing Xenopus oocytes

DEFF Research Database (Denmark)

Holm, Lars M.; Jahn, Thomas Paul; Møller, Anders Laurell Blom

2005-01-01

We have shown recently, in a yeast expression system, that some aquaporins are permeable to ammonia. In the present study, we expressed the mammalian aquaporins AQP8, AQQP9, AQP3, AQP1 and a plant aquaporin TIP2;1 in Xenopus oocytes to study the transport of ammonia (NH3) and ammonium (NH4+) under...... inwards currents carried by NH4+. This conductivity increased as a sigmoid function of external [NH3]: for AQP8 at a bath pH (pH(e)) of 6.5, the conductance was abolished, at pH(e) 7.4 it was half maximal and at pH(e) 7.8 it saturated. NY4+ influx was associated with oocyte swelling. In comparison, native...... oocytes as well as AQP1 and tip2;1-expressing oocytes showed small currents that were associated with small and even negative volume changes. We conclude that AQP8, AQP9, AQP3, and TIP2;1, apart from being water channels, also support significant fluxes of NH3. These aquaporins could support NH4...

Effects of the addition of H2O and NH4OH in the optical and structural properties of the thin films of Y2O3 deposited by pyrolytic spray

International Nuclear Information System (INIS)

Alarcon F, G.; Carvajal V, R.; Aguilar F, M.; Falcony, C.

2005-01-01

In this work we studied the optical and structural properties of yttrium oxide thin films deposited by spray pyrolysis. Yttrium acetylacetonate was used as raw material and N, N-DMF was used as solvent. The films were deposited on Si (100) and Si (111) substrates at temperatures of 400, 450, 500 and 550 C. The optical and structural characteristics of the films were dramatically improved when a mist of H 2 O and/or NH 4 0H was simultaneously added during deposition of the films. A refraction index up to 1.88, and deposition rates lower than 10 A/sec were obtained in the films. Infrared spectroscopy measurements indicate that the films resulted free from -OH bonds. X-ray diffraction patterns reveal that the films were polycrystalline. In addition, the relative chemical composition of the films was determined by Energy Dispersive Spectroscopy and the surface morphology was analyzed in the Atomic Force Microscope. (Author)

Proton location in (CH3)3N-H+-(CH3OH)n: A theoretical and infrared spectroscopic study

International Nuclear Information System (INIS)

Bing, Dan; Hamashima, Toru; Tsai, Chen-Wei; Fujii, Asuka; Kuo, Jer-Lai

2013-01-01

Highlights: • Preferential location of the excess proton in the trimethylamine-methanol clusters. • Collaboration between DFT calculations and IR spectroscopy. • The excess proton prefers the protonation to the trimethylamine moiety. - Abstract: The dependence of the preferential protonated site in (CH 3 ) 3 N-H + -(CH 3 OH) n on the cluster size was investigated using theoretical calculations and infrared spectroscopy measurements. While simple estimation from the magnitude of proton affinity suggested that the excess proton prefers the methanol site in n ⩾ 4, density functional theory calculations of the stabilization energy indicated the clear preference as protonation of the trimethylamine site, even for n = 9. Infrared spectra of the clusters were observed for n = 3–7. Spectral simulations were also performed using the quantum harmonic superposition approximation. The observed (CH 3 ) 3 N-H + -(CH 3 OH) n spectra were well interpreted by simulations of the isomers with the protonated trimethylamine ion core. It was shown that both the proton affinity and the mutual solvation energy govern the preferential location of the excess proton in binary component clusters

Infrared observations of circumstellar ammonia in OH/IR supergiants

International Nuclear Information System (INIS)

McLaren, R.A.; Betz, A.L.

1980-01-01

Ammonia has been detected in the circumstellar envelopes of VY Canis Majoris, VX Sagittarii, and IRC+10420 by means of several absorption lines in the ν 2 vibration-rotation band near 950 cm -1 . The line profiles are well resolved (0.2 km s -1 resolution) and show the gas being accelerated to terminal expansion velocities near 30 km s -1 . The observations reveal a method for determining the position of the central star on VLBI maps of OH maser emission to an accuracy of approx.0''.2. A firm lower limit of 2 x 10 15 cm -2 is obtained for the NH 3 column density in VY Canis Majoris

Identification of 4-hydroxyheptachlorostyrene in polar bear plasma and its binding affinity to transhyretin: a metabolite of octachlorostyrene

NARCIS (Netherlands)

Sandau, C.D.; Meerts, I.A.T.M.; Letcher, R.J.; McAlee, A.J.; Chittim, B.; Brouwer, A.; Norstrom, R.J.

2000-01-01

A new compound, 4-hydroxyheptachlorostyrene (4-OH-HpCS), was identified as a major component in the chlorinated phenolic compound fraction of polar bear plasma. The structure was hypothesized to be 4-OH-HpCS based on mass spectral interpretation, the assumption that it was a metabolite of

Identification of 4-hydroxyheptachlorostyrene in polar bear plasma and its binding affinity to transthyretin : a metabolite of octachlorostyrene?

NARCIS (Netherlands)

Standau, C.D.; Meerts, I.A.T.M.; Letcher, R.J.; McAlees, A.J.; Chittim, B.; Brouwer, A.; Norstrom, R.J.

2000-01-01

A new compound, 4-hydroxyheptachlorostyrene (4-OH-HpCS), was identified as a major component in the chlorinated phenolic compound fraction of polar bear plasma. The structure was hypothesized to be 4-OH-HpCS based on mass spectral interpretation, the assumption that it was a metabolite of

Effects of the addition of H{sub 2}O and NH{sub 4}OH in the optical and structural properties of the thin films of Y{sub 2}O{sub 3} deposited by pyrolytic spray; Efectos de la adicion de H{sub 2}O y NH{sub 4}OH en las propiedades opticas y estructurales de las peliculas delgadas de Y{sub 2}O{sub 3} depositadas por rocio pirolitico

Energy Technology Data Exchange (ETDEWEB)

Alarcon F, G.; Carvajal V, R.; Aguilar F, M. [CICATA-IPN, Legaria 694, Col. Irrigacion, 11500 Mexico D.F. (Mexico); Falcony, C. [CINVESTAV, A.P. 14-740, 07000 Mexico D.F. (Mexico)] [and others

2005-07-01

In this work we studied the optical and structural properties of yttrium oxide thin films deposited by spray pyrolysis. Yttrium acetylacetonate was used as raw material and N, N-DMF was used as solvent. The films were deposited on Si (100) and Si (111) substrates at temperatures of 400, 450, 500 and 550 C. The optical and structural characteristics of the films were dramatically improved when a mist of H{sub 2}O and/or NH{sub 4}0H was simultaneously added during deposition of the films. A refraction index up to 1.88, and deposition rates lower than 10 A/sec were obtained in the films. Infrared spectroscopy measurements indicate that the films resulted free from -OH bonds. X-ray diffraction patterns reveal that the films were polycrystalline. In addition, the relative chemical composition of the films was determined by Energy Dispersive Spectroscopy and the surface morphology was analyzed in the Atomic Force Microscope. (Author)

Polymeric cobalt(ii) thiolato complexes - syntheses, structures and properties of [Co(SMes)2] and [Co(SPh)2NH3].

Science.gov (United States)

Eichhöfer, Andreas; Buth, Gernot

2016-11-01

Reactions of [Co(N(SiMe 3 ) 2 ) 2 thf] with 2.1 equiv. of MesSH (Mes = C 6 H 2 -2,4,6-(CH 3 ) 3 ) yield dark brown crystals of the one dimensional chain compound [Co(SMes) 2 ]. In contrast reactions of [Co(N(SiMe 3 ) 2 ) 2 thf] with 2.1 equiv. of PhSH result in the formation of a dark brown almost X-ray amorphous powder of 'Co(SPh) 2 '. Addition of aliquots of CH 3 OH to the latter reaction resulted in the almost quantitative formation of crystalline ammonia thiolato complexes either [Co(SPh) 2 (NH 3 ) 2 ] or [Co(SPh) 2 NH 3 ]. Single crystal XRD reveals that [Co(SPh) 2 NH 3 ] forms one-dimensional chains in the crystal via μ 2 -SPh bridges whereas [Co(SPh) 2 (NH 3 ) 2 ] consists at a first glance of isolated distorted tetrahedral units. Magnetic measurements suggest strong antiferromagnetic coupling for the two chain compounds [Co(SMes) 2 ] (J = -38.6 cm -1 ) and [Co(SPh) 2 NH 3 ] (J = -27.1 cm -1 ). Interestingly, also the temperature dependence of the susceptibility of tetrahedral [Co(SPh) 2 (NH 3 ) 2 ] shows an antiferromagnetic transition at around 6 K. UV-Vis-NIR spectra display d-d bands in the NIR region between 500 and 2250 nm. Thermal gravimetric analysis of [Co(SPh) 2 (NH 3 ) 2 ] and [Co(SPh) 2 NH 3 ] reveals two well separated cleavage processes for NH 3 and SPh 2 upon heating accompanied by the stepwise formation of 'Co(SPh) 2 ' and cobalt sulfide.

44Sc-DOTA-BN[2-14]NH2 in comparison to 68Ga-DOTA-BN[2-14]NH2 in pre-clinical investigation. Is 44Sc a potential radionuclide for PET?

Science.gov (United States)

Koumarianou, E; Loktionova, N S; Fellner, M; Roesch, F; Thews, O; Pawlak, D; Archimandritis, S C; Mikolajczak, R

2012-12-01

In the present study we demonstrate the in vitro and in vivo comparison of the (44)Sc and (68)Ga labeled DOTA-BN[2-14]NH(2). (44)Sc is a positron emitter with a half life of 3.92 h. Hence it could be used for PET imaging with ligands requiring longer observation time than in the case of (68)Ga. The binding affinity of (nat)Sc-DOTA-BN[2-14]NH(2) and (nat)Ga-DOTA-BN[2-14]NH(2) to GRP receptors was studied in competition to [(125)I-Tyr(4)]-Bombesin in the human prostate cancer cell line PC-3. A preliminary biodistribution in normal rats was performed, while first microPET images were assessed in male Copenhagen rats bearing the androgen-independent Dunning R-3327-AT-1 prostate cancer tumor. The affinity to GRP receptors in the PC-3 cell line was higher for (nat)Ga-DOTA-BN[2-14]NH(2) (IC(50)(nM)=0.85 ± 0.06) than that of (nat)Sc-DOTA-BN[2-14]NH(2) (IC(50) (nM)=6.49 ± 0.13). The internalization rate of (68)Ga labeled DOTA-BN[2-14]NH(2) was slower than that of (44)Sc, but their final internalization percents were comparable. (68)Ga-DOTA-BN[2-14]NH(2) was externalized faster than (44)Sc-DOTA-BN[2-14]NH(2). The biodistribution of (44)Sc-DOTA-BN[2-14]NH(2) and (68)Ga-DOTA-BN[2-14]NH(2) in normal rats revealed a higher uptake in target organs and tissues of the first one while both excreted mainly through urinary tract. In microPET images both tracers were accumulated in the tumor with similar uptake patterns. Despite the differences in the receptor affinity both the (68)Ga- and the (44)Sc-labeled DOTA-BN[2-14]NH(2) tracers showed comparable distribution and similar time constants of uptake and elimination. Moreover no differences in tumor accumulation (neither in the overall uptake nor in the dynamics) were observed from the microPet imaging. From that perspective the use of either (44)Sc or (68)Ga for detecting tumors with GRP receptors is equivalent. Copyright © 2012 Elsevier Ltd. All rights reserved.

Synthesis and properties of ternary (K, NH{sub 4}, H{sub 3}O)-jarosites precipitated from Acidithiobacillus ferrooxidans cultures in simulated bioleaching solutions

Energy Technology Data Exchange (ETDEWEB)

Sandy Jones, F.; Bigham, Jerry M. [School of Environment and Natural Resources, Ohio State University, 2021 Coffey Road, Columbus, OH 43210 (United States); Gramp, Jonathan P. [Department of Microbiology, Ohio State University, 484 West 12th Avenue, Columbus, OH 43210 (United States); Tuovinen, Olli H., E-mail: tuovinen.1@osu.edu [Department of Microbiology, Ohio State University, 484 West 12th Avenue, Columbus, OH 43210 (United States)

2014-11-01

The purpose of this study was to synthesize a series of solid solution jarosites by biological oxidation of ferrous iron at pH 2.2–4.4 and ambient temperature in media containing mixtures of K{sup +} (0, 1, 4, 6, 12, 31 mM) and NH{sub 4}{sup +} (6.1, 80, 160, 320 mM). The starting material was a liquid medium for Acidithiobacillus ferrooxidans comprised of 120 mM FeSO{sub 4} solution and mineral salts at pH 2.2. Following inoculation with A. ferrooxidans, the cultures were incubated in shake flasks at 22 °C. As bacteria oxidized ferrous iron, ferric iron hydrolyzed and precipitated as jarosite-group minerals (AFe{sub 3}(SO{sub 4}){sub 2}(OH){sub 6}) and/or schwertmannite (idealized formula Fe{sub 8}O{sub 8}(OH){sub 6}(SO{sub 4})·nH{sub 2}O). The precipitates were characterized by X-ray diffraction (XRD), elemental analysis, and Munsell color. Schwertmannite was the dominant mineral product at low combinations of K{sup +} (≤ 4 mM) and NH{sub 4}{sup +} (≤ 80 mM) in the media. At higher single or combined concentrations, yellowish jarosite phases were produced, and Munsell hue provided a sensitive means of detecting minor schwertmannite in the oxidation products. Although the hydrated ionic radii of K{sup +} and NH{sub 4}{sup +} are similar, K{sup +} greatly facilitated the formation of a jarosite phase compared to NH{sub 4}{sup +}. Unit cell and cell volume calculations from refinements of the powder XRD patterns indicated that the jarosite phases produced were mostly ternary (K, NH{sub 4}, H{sub 3}O)-solid solutions that were also deficient in structural Fe, especially at low NH{sub 4} contents. Thus, ferric iron precipitation from the simulated bioleaching systems yielded solid solutions of jarosite with chemical compositions that were dependent on the relative concentrations of K{sup +} and NH{sub 4}{sup +} in the synthesis media. No phase separations involving discrete, end-member K-jarosite or NH{sub 4}-jarosite were detected in the un-aged precipitates

Role of NH3 and NH4+ transporters in renal acid-base transport.

Science.gov (United States)

Weiner, I David; Verlander, Jill W

2011-01-01

Renal ammonia excretion is the predominant component of renal net acid excretion. The majority of ammonia excretion is produced in the kidney and then undergoes regulated transport in a number of renal epithelial segments. Recent findings have substantially altered our understanding of renal ammonia transport. In particular, the classic model of passive, diffusive NH3 movement coupled with NH4+ "trapping" is being replaced by a model in which specific proteins mediate regulated transport of NH3 and NH4+ across plasma membranes. In the proximal tubule, the apical Na+/H+ exchanger, NHE-3, is a major mechanism of preferential NH4+ secretion. In the thick ascending limb of Henle's loop, the apical Na+-K+-2Cl- cotransporter, NKCC2, is a major contributor to ammonia reabsorption and the basolateral Na+/H+ exchanger, NHE-4, appears to be important for basolateral NH4+ exit. The collecting duct is a major site for renal ammonia secretion, involving parallel H+ secretion and NH3 secretion. The Rhesus glycoproteins, Rh B Glycoprotein (Rhbg) and Rh C Glycoprotein (Rhcg), are recently recognized ammonia transporters in the distal tubule and collecting duct. Rhcg is present in both the apical and basolateral plasma membrane, is expressed in parallel with renal ammonia excretion, and mediates a critical role in renal ammonia excretion and collecting duct ammonia transport. Rhbg is expressed specifically in the basolateral plasma membrane, and its role in renal acid-base homeostasis is controversial. In the inner medullary collecting duct (IMCD), basolateral Na+-K+-ATPase enables active basolateral NH4+ uptake. In addition to these proteins, several other proteins also contribute to renal NH3/NH4+ transport. The role and mechanisms of these proteins are discussed in depth in this review.

MERLIN observations of the OH/IR stars OH 53.6-0.2, OH 138.0+7.2 and OH 141.7+3.5

International Nuclear Information System (INIS)

Chapman, J.; Cohen, R.J.; Norris, R.P.; Diamond, P.J.; Booth, R.S.

1984-01-01

OH maser emission from the three OH/IR stars OH 53.6-0.2, OH 138.0+7.2 and OH 141.7+3.5 has been mapped with an angular resolution of 0.28 arcsec and a velocity resolution of 0.7 km s -1 using the Jodrell Bank MERLIN array. Maps are presented of the 1612-MHz OH emission over individual velocity ranges. The maps are consistent with a uniform expanding shell model, and by fitting such models to the data the angular diameters of the shells have been estimated to an accuracy of approx. 25 per cent. (author)

Infrared observations of circumstellar ammonia in OH/IR supergiants

Science.gov (United States)

Mclaren, R. A.; Betz, A. L.

1980-01-01

Ammonia has been detected in the circumstellar envelopes of VY Canis Majoris, VX Sagittarii, and IRC +10420 by means of several absorption lines in the nu-2 vibration-rotation band near 950 kaysers. The line profiles are well resolved (0.2 km/sec resolution) and show the gas being accelerated to terminal expansion velocities near 30 km/sec. The observations reveal a method for determining the position of the central star on VLBI maps of OH maser emission to an accuracy of approximately 0.2 arcsec. A firm lower limit of 2 x 10 to the 15th/sq cm is obtained for the NH3 column density in VY Canis Majoris.

Estabilidade da sílica biogênica extraída de capim Jaraguá (Hyparrhenia rufa em solução de NaOH Stability of biogenic silica extract of Jaraguá grass (Hyparrhenia rufa in NaOH solution

Directory of Open Access Journals (Sweden)

Liovando M. Costa

2010-01-01

Full Text Available Biogenic silica is used to describe compounds of hydrated silica (SiO2.nH2O, with specific shapes and sizes, deposited in plants. The chemical composition of biogenic silica and its stability in Jaraguá grass was studied in increasing concentration of NaOH. The analytical results demonstrated high concentration of Si, Al, Fe, Mg, P and low of Cu, Cd and Zn in the phytoliths composition. The silica bodies stability in NaOH solution with increasing concentration was different among the shapes and sizes. Silicified stomata and silicified plant tissues were dissolved along with the dumbbells because they are the less stable forms of biogenic silica.

In vivo evaluation of the 3-carboranyl thymidine analogue (3-CTA), N5-2OH, for neutron capture therapy

International Nuclear Information System (INIS)

Barth, Rolf F.; Yang, Weilian; Wu, Gong; Byun, Youngjoo; Tjarks, Werner; Eriksson, Staffan; Binns, Peter J.; Riley, Kent J.

2006-01-01

The purpose of the present study was to evaluate a 3 CTA, designated N5-2OH, as a boron delivery agent for NCT. Target validation was established using the thymidine kinase 1 (+) wild type L929 cell line and its TK1(-) counterpart, which were implanted subcutaneously into NIH nu/nu mice. 10 B-enriched N5-2OH, solubilized in DMSO (50μg 10 B in 15μl), was administered by 2 intratumoral (i.t.) injections at 2 h intervals. Two hours later the animals were irradiated at the MITR-II Research Reactor, following which tumor volumes were determined over a period of 30 days. Mice bearing TK1(+) wild type tumors, which had received N5-2OH, had a 15 fold inhibition in tumor growth compared to TK1(-) controls (247 versus 3,603 mm 3 ). Based on these data, biodistribution and therapy studies were initiated in F98 glioma bearing rats. Animals received 500μg of N5-2OH, administered intracerebrally (i.c.) by convection enhanced delivery (CED) using ALZET pumps (8μl/h for 24 h). The tumor boron concentration was 17.3μg/g compared to undetectable amounts in normal brain and blood. BNCT was carried out 14 d following i.c. implantation of 10 3 F98 glioma cells and 24 h following CED of N5-2OH (500μg/200μl). The mean survival time (MST) of these animals was 38 d compared to 31 d and 25 d, respectively, for irradiated and untreated controls. Studies are planned to optimize the delivery and formulation of N5-2OH and additional therapy studies will be carried out using N5-2OH in combination with BPA and BSH. (author)

Room temperature atomic layer deposited Al2O3 on CH3NH3PbI3 characterized by synchrotron-based X-ray photoelectron spectroscopy

Science.gov (United States)

Kot, Małgorzata; Das, Chittaranjan; Henkel, Karsten; Wojciechowski, Konrad; Snaith, Henry J.; Schmeisser, Dieter

2017-11-01

An ultrathin Al2O3 film deposited on methylammonium lead triiodide (CH3NH3PbI3) perovskite has the capability to suppress the carrier recombination process and improve the perovskite solar cells efficiency and stability. However, annealing at temperatures higher than 85 °C degrades the CH3NH3PbI3 perovskite film. The X-ray photoelectron spectroscopy study performed in this work indicates that it is possible to grow Al2O3 by atomic layer deposition on the perovskite at room temperature, however, besides pure Al2O3 some OH groups are found and the creation of lead and iodine oxides at the Al2O3/CH3NH3PbI3 interface takes place.

The influence of Uranium-Thorium ratio and heating time during gelation using as a CCl4(NH3) on the Gel quality

International Nuclear Information System (INIS)

Indra-Suryawan; Sukarsono, R; Setyo-Sulardi

1996-01-01

Gel has been prepared from a uranium-thorium sol using CCI 4 (NH 3 ) as a gelling medium. The uranium-thorium ratio and the heating time during gelation have been chosen as variables. The sol was prepared by mixing Th(NO 3 ) 4 and UO 2 (NO 3 ) 2 solutions, heating the solution at 95 o C and adding NH 4 OH solution drop by drop until colloidal particles were formed. Sol was then fed into a gelation column containing CCI 4 (NH 3 ), where the sol was transformed into gel. A good gel has properties such as sphere in shape and elastic which it will not crack when it is dropped from 2 metres height. The experimental work resulted a good gel when the percentage of uranium was about 15 - 25 % at heating time of 40 - 50 minutes

Rapid ammonia gas transport accounts for futile transmembrane cycling under NH3/NH4+ toxicity in plant roots.

Science.gov (United States)

Coskun, Devrim; Britto, Dev T; Li, Mingyuan; Becker, Alexander; Kronzucker, Herbert J

2013-12-01

Futile transmembrane NH3/NH4(+) cycling in plant root cells, characterized by extremely rapid fluxes and high efflux to influx ratios, has been successfully linked to NH3/NH4(+) toxicity. Surprisingly, the fundamental question of which species of the conjugate pair (NH3 or NH4(+)) participates in such fluxes is unresolved. Using flux analyses with the short-lived radioisotope (13)N and electrophysiological, respiratory, and histochemical measurements, we show that futile cycling in roots of barley (Hordeum vulgare) seedlings is predominately of the gaseous NH3 species, rather than the NH4(+) ion. Influx of (13)NH3/(13)NH4(+), which exceeded 200 µmol g(-1) h(-1), was not commensurate with membrane depolarization or increases in root respiration, suggesting electroneutral NH3 transport. Influx followed Michaelis-Menten kinetics for NH3 (but not NH4(+)), as a function of external concentration (Km = 152 µm, Vmax = 205 µmol g(-1) h(-1)). Efflux of (13)NH3/(13)NH4(+) responded with a nearly identical Km. Pharmacological characterization of influx and efflux suggests mediation by aquaporins. Our study fundamentally revises the futile-cycling model by demonstrating that NH3 is the major permeating species across both plasmalemma and tonoplast of root cells under toxicity conditions.

Evidence of amino acid precursors: C-N bond coupling in simulated interstellar CO2/NH3 ices

Science.gov (United States)

Esmaili, Sasan

2015-08-01

Low energy secondary electrons are abundantly produced in astrophysical or planetary ices by the numerous ionizing radiation fields typically encountered in space environments and may thus play a role in the radiation processing of such ices [1]. One approach to determine their chemical effect is to irradiate nanometer thick molecular solids of simple molecular constituents, with energy selected electron beams and to monitor changes in film chemistry with the surface analytical techniques [2].Of particular interest is the formation of HCN, which is a signature of dense gases in interstellar clouds, and is ubiquitous in the ISM. Moreover, the chemistry of HCN radiolysis products such as CN- may be essential to understand of the formation of amino acids [3] and purine DNA bases. Here we present new results on the irradiation of multilayer films of CO2 and NH3 with 70 eV electrons, leading to CN bond formations. The electron stimulated desorption (ESD) yields of cations and anions are recorded as a function of electron fluence. The prompt desorption of cationic reaction/scattering products [4], is observed at low fluence (~4x1013 electrons/cm2). Detected ions include C2+, C2O2+, C2O+, CO3+, C2O3+ or CO4+ from pure CO2, and N+, NH+, NH2+, NH3+, NH4+, N2+, N2H+ from pure NH3, and NO+, NOH+ from CO2/NH3 mixtures. Most saliently, increasing signals of negative ion products desorbing during prolonged irradiation of CO2/NH3 films included C2-, C2H-, C2H2-, as well as CN-, HCN- and H2CN-. The identification of particular product ions was accomplished by using 13CO2 and 15NH3 isotopes. The chemistry induced by electrons in pure films of CO2 and NH3 and mixtures with composition ratios (3:1), (1:1), and (1:3), was also studied by X-ray photoelectron spectroscopy (XPS). Irradiation of CO2/NH3 mixed films at 22 K produces species containing the following bonds/functional groups identified by XPS: C=O, O-H, C-C, C-O, C=N and N=O. (This work has been funded by NSERC).

Densities and apparent molar volumes of atmospherically important electrolyte solutions. 1. The solutes H2SO4, HNO3, HCl, Na2SO4, NaNO3, NaCl, (NH4)2SO4, NH4NO3, and NH4Cl from 0 to 50 °C, including extrapolations to very low temperature and to the pure liquid state, and NaHSO4, NaOH, and NH3 at 25 °C.

Science.gov (United States)

Clegg, S L; Wexler, A S

2011-04-21

Calculations of the size and density of atmospheric aerosols are complicated by the fact that they can exist at concentrations highly supersaturated with respect to dissolved salts and supercooled with respect to ice. Densities and apparent molar volumes of solutes in aqueous solutions containing the solutes H(2)SO(4), HNO(3), HCl, Na(2)SO(4), NaNO(3), NaCl, (NH(4))(2)SO(4), NH(4)NO(3), and NH(4)Cl have been critically evaluated and represented using fitted equations from 0 to 50 °C or greater and from infinite dilution to concentrations saturated or supersaturated with respect to the dissolved salts. Using extrapolated densities of high-temperature solutions and melts, the relationship between density and concentration is extended to the hypothetical pure liquid solutes. Above a given reference concentration of a few mol kg(-1), it is observed that density increases almost linearly with decreasing temperature, and comparisons with available data below 0 °C suggest that the fitted equations for density can be extrapolated to very low temperatures. As concentration is decreased below the reference concentration, the variation of density with temperature tends to that of water (which decreases as temperature is reduced below 3.98 °C). In this region below the reference concentration, and below 0 °C, densities are calculated using extrapolated apparent molar volumes which are constrained to agree at the reference concentrations with an equation for the directly fitted density. Calculated volume properties agree well with available data at low temperatures, for both concentrated and dilute solutions. Comparisons are made with literature data for temperatures of maximum density. Apparent molar volumes at infinite dilution are consistent, on a single ion basis, to better than ±0.1 cm(3) mol(-1) from 0 to 50 °C. Volume properties of aqueous NaHSO(4), NaOH, and NH(3) have also been evaluated, at 25 °C only. In part 2 of this work (ref 1 ) an ion interaction (Pitzer

Imaging a multidimensional multichannel potential energy surface: Photodetachment of H(-)(NH3) and NH4 (.).

Science.gov (United States)

Hu, Qichi; Song, Hongwei; Johnson, Christopher J; Li, Jun; Guo, Hua; Continetti, Robert E

2016-06-28

Probes of the Born-Oppenheimer potential energy surfaces governing polyatomic molecules often rely on spectroscopy for the bound regions or collision experiments in the continuum. A combined spectroscopic and half-collision approach to image nuclear dynamics in a multidimensional and multichannel system is reported here. The Rydberg radical NH4 and the double Rydberg anion NH4 (-) represent a polyatomic system for benchmarking electronic structure and nine-dimensional quantum dynamics calculations. Photodetachment of the H(-)(NH3) ion-dipole complex and the NH4 (-) DRA probes different regions on the neutral NH4 PES. Photoelectron energy and angular distributions at photon energies of 1.17, 1.60, and 2.33 eV compare well with quantum dynamics. Photoelectron-photofragment coincidence experiments indicate dissociation of the nascent NH4 Rydberg radical occurs to H + NH3 with a peak kinetic energy of 0.13 eV, showing the ground state of NH4 to be unstable, decaying by tunneling-induced dissociation on a time scale beyond the present scope of multidimensional quantum dynamics.

Purine biosynthesis in L1210 leukemia cells is inhibited by 7-hydroxymethotrexate (7-OH-MTX) polyglutamates (PGS)

International Nuclear Information System (INIS)

Seither, R.L.; Matherly, L.H.; Goldman, I.D.

1986-01-01

The biochemical basis for 7-OH-MTX cytotoxicity was examined in L1210 tumor cells. Cells were exposed to 100 μM 7-OH-MTX (approx. 50% growth inhibition) or 10 μM methotrexate (MTX) (approx. 95% growth inhibition) for 6 hrs to allow high levels of PGS to accumulate. Dihydrofolate reductase (DHFR) activity was assessed by dihydrofolate (FH 2 ) pools labeled with 5-formyl-[ 3 H]-tetrahydrofolate (5μM) or 3 H-folic acid (1 μM). FH 2 was not elevated above control levels in 7-OH-MTX treated cells, in contrast to MTX treated cells in which FH 2 increased 4- to 7-fold. 3 H-Deoxyuridine incorporation into DNA was not inhibited in cells containing high levels (11.5 nmol/g dry wt.) of 7-OH-MTX tetraglutamate (7-OH-4-NH 2 -10-CH 3 -PteGlu 4 ), well in excess of the DHFR-binding capacity (7.3 +/- 0.9 nmol/g), indicating a normal rate of thymidylate synthesis. Although small amounts of 7-OH-MTX and its PGS were bound to DHFR in L1210 cells, as assessed by gel filtration, there was evidence for the preferential binding of 7-OH-MTX tetraglutamate. In all cases this was well below the DHFR binding capacity, consistent with normal rates of deoxyuridine metabolism and FH 2 levels in the cell. Incorporation of 14 C-formate (60 min) into thymidylate and amino acids was unaffected by 7-OH-MTX, yet incorporation into purines was inhibited over 50%, supporting a block(s) in de novo purine biosynthesis

Keggin type polyoxometalate H4[αSiW12O40].nH2O as intercalant for hydrotalcite

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Neza Rahayu Palapa

2017-06-01

Full Text Available The synthesis of hydrotalcite and polyoxometalate H4[αSiW12O40].nH2O with the ratio (2:1, (1:1, (1:2 and (1:3 has been done. The product of intercalation was characterized using FT-IR spectrophotometer, XRD, and TG-DTA. Polyoxometalate H4[αSiW12O40].nH2O intercalated layered double hydroxide was optimised to use as adsorbent Congo red dye. Characterization using FT-IR was not showing the optimal insertion process. The result using XRD characterization was showed successful of polyoxometalate H4[αSiW12O40].nH2O inserted layered double hydroxide with a ratio (1:1 which the basal spacing was expanded from 7,8 Ȧ to 9,81 Ȧ. Furthermore, the thermal analysis was performed using TG-DTA. The result show that the decomposition of polyoxometalate H4[αSiW12O40].nH2O intercalated  hydrotalcite with ratio (1:1 was occured at 80oC to 400oC with a loss of OH in the layer at 150oC to 220oC, and then the decomposition of the compound polyoxometalate H4[αSiW12O40].nH2O at 350oC to 420oC. Keywords: Hydrotalcite, Layered Double Hydroxide, Polyoxometalate, Intercalation

LPG and NH3 Sensing Properties of SnO2 Thick Film Resistors Prepared by Screen Printing Technique

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A. S. GARDE

2010-11-01

Full Text Available The gas sensing behavior of SnO2 thick film resistors deposited on alumina substrates has been investigated for LPG and NH3 gas. The standard screen printing technology was used to prepare the thick films. The films were fired at optimized temperature of 780 0C for 30 minutes. The material characterization was performed by XRD, SEM, FTIR, UV and EDAX for elemental analysis. IR spectroscopy analysis at 2949.26 cm-1 showed the peak assigned to the –Sn-H vibration due to the effect of hybridization i.e. sp3 and the sharp peak at 3734.31 cm-1 assigned to –Sn-OH stretching vibration due to hydrogen bonding. The variation of D.C electrical resistance of SnO2 film samples was measured in air as well as in LPG and NH3 gas atmosphere as a function of temperature. The SnO2 film samples show negative temperature coefficient of résistance. The SnO2 film samples showed the highest sensitivity to 600 ppm of LPG at 230 0C and NH3 at 370 0C. The effect of microstructure on sensitivity, response time and recovery time of the sensor in the presence of LPG and NH3 gases were studied and discussed.

44Sc-DOTA-BN[2-14]NH2 in comparison to 68Ga-DOTA-BN[2-14]NH2 in pre-clinical investigation. Is 44Sc a potential radionuclide for PET?

International Nuclear Information System (INIS)

Koumarianou, E.; Loktionova, N.S.; Fellner, M.; Roesch, F.; Thews, O.; Pawlak, D.; Archimandritis, S.C.; Mikolajczak, R.

2012-01-01

Aim: In the present study we demonstrate the in vitro and in vivo comparison of the 44 Sc and 68 Ga labeled DOTA-BN[2-14]NH 2 . 44 Sc is a positron emitter with a half life of 3.92 h. Hence it could be used for PET imaging with ligands requiring longer observation time than in the case of 68 Ga. Methods: The binding affinity of nat Sc-DOTA-BN[2-14]NH 2 and nat Ga-DOTA-BN[2-14]NH 2 to GRP receptors was studied in competition to [ 125 I-Tyr 4 ]-Bombesin in the human prostate cancer cell line PC-3. A preliminary biodistribution in normal rats was performed, while first microPET images were assessed in male Copenhagen rats bearing the androgen-independent Dunning R-3327-AT-1 prostate cancer tumor. Results: The affinity to GRP receptors in the PC-3 cell line was higher for nat Ga-DOTA-BN[2-14]NH 2 (IC 50 (nM)=0.85±0.06) than that of nat Sc-DOTA-BN[2-14]NH 2 (IC 50 (nM)=6.49±0.13). The internalization rate of 68 Ga labeled DOTA-BN[2-14]NH 2 was slower than that of 44 Sc, but their final internalization percents were comparable. 68 Ga-DOTA-BN[2-14]NH 2 was externalized faster than 44 Sc-DOTA-BN[2-14]NH 2 . The biodistribution of 44 Sc-DOTA-BN[2-14]NH 2 and 68 Ga-DOTA-BN[2-14]NH 2 in normal rats revealed a higher uptake in target organs and tissues of the first one while both excreted mainly through urinary tract. In microPET images both tracers were accumulated in the tumor with similar uptake patterns. Conclusions: Despite the differences in the receptor affinity both the 68 Ga- and the 44 Sc-labeled DOTA-BN[2-14]NH 2 tracers showed comparable distribution and similar time constants of uptake and elimination. Moreover no differences in tumor accumulation (neither in the overall uptake nor in the dynamics) were observed from the microPet imaging. From that perspective the use of either 44 Sc or 68 Ga for detecting tumors with GRP receptors is equivalent. - Highlights: ► In vitro and in vivo evaluation of 44 Sc- and 68 Ga-DOTA-BN[2-14]NH 2 in reference to published

Origin of the OH vibrational blue shift in the LiOH crystal.

Science.gov (United States)

Hermansson, Kersti; Gajewski, Grzegorz; Mitev, Pavlin D

2008-12-25

The O-H vibrational frequency in crystalline hydroxides is either upshifted or downshifted by its crystalline surroundings. In the LiOH crystal, the experimental gas-to-solid O-H frequency upshift ("blue shift") is approximately +115 cm(-1). Here plane-wave DFT calculations for the isotope-isolated LiOH crystal have been performed and we discuss the origin of the OH frequency upshift, and the nature of the OH group and the interlayer interactions. We find that (1) the vibrational frequency upshift originates from interactions within the LiOH layer; this OH upshift is slightly lessened by the interlayer interactions; (2) the interlayer O-H - - - H-O interaction is largely electrostatic in character (but there is no hydrogen bonding); (3) the gas-to-solid vibrational shift for OH in LiOH(s) and its subsystems qualitatively adheres to a parabola-like "frequency vs electric field strength" correlation curve, which has a maximum for a positive electric field, akin to the correlation curve earlier found in the literature for an isolated OH(-) ion in an electric field.

Managing OHS

DEFF Research Database (Denmark)

Hull Kristensen, Peer

2011-01-01

Contrary to a widely held view, rather than seeing the certification of Occupational Health and Safety (OHS) as a barrier to increasing employee participation, this article views new ways of structuring participation as a necessary step towards making improvements in OHS management systems....... The article first considers how work organization has changed and then in a similar way traces how bargaining has shifted from being distributive to become integrative to create a fundamental change in the negotiation regime. Finally, by analyzing an OHS-certified firm in greater depth, the article shows how...... solutions for improvements in OHS management and notable bottom-up formulations of OHS benchmarks may help us discover how the organizational form of firms with high-performance work organization can be developed through new participatory structures....

The loss of NH2O from the N-hydroxyacetamide radical cation CH3C(O)NHOH+

Science.gov (United States)

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

2006-08-01

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

Performance evaluation of poly-urethane foam packed-bed chemical scrubber for the oxidative absorption of NH3 and H2S gases.

Science.gov (United States)

Nisola, Grace M; Valdehuesa, Kris Niño G; Anonas, Alex V; Ramos, Kristine Rose M; Lee, Won-Keun; Chung, Wook-Jin

2018-01-02

The feasibility of open-pore polyurethane (PU) foam as packing material for wet chemical scrubber was tested for NH 3 and H 2 S removals. The foam is inexpensive, light-weight, highly porous (low pressure drop) and provides large surface area per unit volume, which are desirable properties for enhanced gas/liquid mass transfer. Conventional HCl/HOCl (for NH 3 ) and NaOH/NaOCl (for H 2 S) scrubbing solutions were used to absorb and oxidize the gases. Assessment of the wet chemical scrubbers reveals that pH and ORP levels are important to maintain the gas removal efficiencies >95%. A higher re-circulation rate of scrubbing solutions also proved to enhance the performance of the NH 3 and H 2 S columns. Accumulation of salts was confirmed by the gradual increase in total dissolved solids and conductivity values of scrubbing solutions. The critical elimination capacities at >95% gas removals were found to be 5.24 g NH 3 -N/m 3 -h and 17.2 g H 2 S-S/m 3 -h at an empty bed gas residence time of 23.6 s. Negligible pressure drops (scrubbers for NH 3 and H 2 S removals from high-volume dilute emissions.

Rydberb bonding in (NH4)2

International Nuclear Information System (INIS)

Boldyrev, A.I.; Simons, J.

1992-01-01

Chemical binding of two monovalent Rydberg species to form a singlet-state Rydberg dimer molecule is predicted to be possible Ab initio electronic structure methods that include electron correlation (at levels up through QCISD(T)/6-31++G** MP2(full)/6-31++G** + ZPE) are shown to be essential to achieving a proper description of such bonding. The (NH 4 ) molecule, selected as the prototype for this study, is shown to be bound with respect to its Rydberg-species fragments, 2NH 4 by 7.5-9.7 kcal/mol, depending on the level of treatment of electron correlation, and to be electronically stable (by ca.4 eV) with respect to (NH 4 ) 2 + at the neutral's equilibrium geometry. The (NH 4 ) 2 Rydberg dimer is thermodynamically unstable with respect to 2NH 3 + H 2 by 86-89 kcal/mol mol yet possesses all real vibrational frequencies; it is thus a metastable molecular held together by a weak Rydberg bond. The dissociation energy of the (NH 4 ) 2 + cation to form NH 4 + + NH 4 is found to be larger than that of the neutral (NH 4 ) 2 . 12 refs., 4 figs., 9 tabs

Exploring the crystallization landscape of cadmium bis(N-hydroxyethyl, N-isopropyldithiocarbamate), Cd[S{sub 2}CN(iPr)CH{sub 2}CH{sub 2}OH]{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Tan, Yee Seng; Halim, Siti Nadiah Abdul [Malaya Univ., Kuala Lumpur (Malaysia). Dept. of Chemistry; Tiekink, Edward R.T. [Malaya Univ., Kuala Lumpur (Malaysia). Dept. of Chemistry; Sunway Univ., Bandar Sunway (Malaysia). Centre for Chemical Crystallography

2016-04-01

Crystallization of Cd[S{sub 2}CN(iPr)CH{sub 2}CH{sub 2}OH]{sub 2} from ethanol yields the coordination polymer [{Cd[S_2CN(iPr)CH_2CH_2OH]_2}.EtOH]{sub ∞} (1) within 3 h. When the solution is allowed to stand for another hour, the needles begin to dissolve and prisms emerge of the supramolecular isomer (SI), binuclear {Cd[S_2CN(iPr)CH_2CH_2OH]_2}{sub 2}.2EtOH (2). These have been fully characterized spectroscopically and by X-ray crystallography. Polymeric 1 has 2-fold symmetry and features dithiocarbamate ligands coordinating two octahedral Cd atoms in a μ{sub 2}κ{sup 2}-tridentate mode. Binuclear 2 is centrosymmetric with two ligands being μ{sub 2}κ{sup 2}-tridentate as for 1 but the other two being κ{sup 2}-chelating leading to square pyramidal geometries. The conversion of the kinetic crystallization product, 1, to thermodynamic 2 is irreversible but transformations mediated by recrystallization (ethanol and acetonitrile) to related literature SI species, namely coordination polymer [{Cd[S_2CN(iPr)CH_2CH_2OH]_2}{sub 3}.MeCN]{sub ∞} and binuclear {Cd[S_2CN(iPr)CH_2CH_2OH]_2}{sub 2}.2H{sub 2}O.2MeCN, are demonstrated, some of which are reversible. Three other crystallization outcomes are described whereby crystal structures were obtained for the 1:2 co-crystal {Cd[S_2CN(iPr)CH_2CH_2OH]_2}{sub 2}:2[3-(propan-2-yl)-1,3-oxazolidine-2-thione] (3), the salt co-crystal [iPrNH{sub 2}(CH{sub 2}CH{sub 2}OH)]{sub 4}[SO{sub 4}]{sub 2}{Cd[S_2CN(iPr)CH_2CH_2OH]_2}{sub 2} (4) and the salt [iPrNH{sub 2}(CH{sub 2}CH{sub 2}OH)]{Cd[S_2CN(iPr)CH_2CH_2OH]_3} (5). These arise as a result of decomposition/oxidation of the dithiocarbamate ligands. In each of 3 and 4 the binuclear {Cd[S_2CN(iPr)CH_2CH_2OH]_2}{sub 2} SI, as in 2, is observed strongly suggesting a thermodynamic preference for this form.

Simultaneous stabilization/solidification of Mn2+ and NH4+-N from electrolytic manganese residue using MgO and different phosphate resource.

Science.gov (United States)

Shu, Jiancheng; Wu, Haiping; Liu, Renlong; Liu, Zuohua; Li, Bing; Chen, Mengjun; Tao, Changyuan

2018-02-01

This study examined simultaneous stabilization and solidification (S/S) of Mn 2+ and NH 4 + -N from electrolytic manganese residue (EMR) using MgO and different phosphate resource. The characteristics of EMR NH 4 + -N and Mn 2+ S/S behavior, S/S mechanisms, leaching test and economic analysis, were investigated. The results show that the S/S efficiency of Mn 2+ and NH 4 + -N could reach 91.58% and 99.98%, respectively, and the pH value is 8.75 when the molar ratio of Mg:P is 3:1 and the dose of PM (MgO and Na 3 PO 4 ·12H 2 O) is 8wt%. In this process, Mn 2+ could mainly be stabilized in the forms of Mn(H 2 PO 4 ) 2 ·2H 2 O, Mn 3 (PO 4 ) 2 ·3H 2 O, Mn(OH) 2 , and MnOOH, and NH 4 + -N in the form of NH 4 MgPO 4 ·6H 2 O. Economic evaluation indicates that using PM process has a lower cost than HPM and HOM process for the S/S of Mn 2+ and NH 4 + -N from EMR at the same stabilization agent dose. Leaching test values of all the measured metals are within the permitted level for the GB8978-1996 test suggested when the dose of PM, HPM and HOM is 8wt%. Copyright © 2017 Elsevier Inc. All rights reserved.

Biodistribution and tumor uptake of C{sub 60}(OH){sub x} in mice

Energy Technology Data Exchange (ETDEWEB)

Zhiqiang, Ji; Sun Hongfang, E-mail: shf@pku.edu.cn; Haifang, Wang; Qunying, Xie; Yuangfang, Liu [Peking University, Department of Chemical Biology, College of Chemistry and Molecular Engineering (China); Zheng, Wang [Chinese Academy of Medical Sciences, Cancer Institute (China)

2006-02-15

Radiolabeling of fullerol, {sup 125}I-C{sub 60}(OH){sub x}, was performed by the traditional chloramine-T method. The C-I covalent bond in I-C{sub 60}(OH){sub x} was characterized by X-ray photoelectron spectroscopy (XPS) that was sufficiently stable for in vivo study. Laser light scattering spectroscopy clearly showed that C{sub 60}(OH){sub x} aggregated to large nanoparticle clumps with a wide range of distribution. The clumps formed were also visualized by transmission electron microscope (TEM). We examined the biodistribution and tumor uptake of C{sub 60}(OH){sub x} in five mouse bearing tumor models, including mouse H22 hepatocarcinoma, human lung giantcellcarcinoma PD, human colon cancer HCT-8, human gastric cancer MGC803, and human OS732 osteosarcoma. The accumulation ratios of {sup 125}I-C{sub 60}(OH){sub x} in mouse H22 hepatocarcinoma to that in normal muscle tissue (T/N) and blood (T/B) at 1, 6, 24 and 72 h, reveal that {sup 125}I-C{sub 60}(OH){sub x} gradually accumulates in H22 tumor, and retains for a quite long period (e.g., T/N 3.41, T/B 3.94 at 24 h). For the other four tumor models, the T/N ratio at 24 h ranges within 1.21-6.26, while the T/B ratio ranges between 1.23 and 4.73. The accumulation of C{sub 60}(OH){sub x} in tumor is mostly due to the enhanced permeability and retention effect (EPR) and the phagocytosis of mononuclear phagocytes. Hence, C{sub 60}(OH){sub x} might serve as a photosensitizer in the photodynamic therapy of some kinds of tumor.

Synthesis and crystal structure of 4-fluorobenzylammonium dihydrogen phosphate, [FC6H4CH2NH3]H2PO4

Directory of Open Access Journals (Sweden)

Ali Rayes

2016-12-01

Full Text Available The asymmetric unit of the title salt, [p-FC6H4CH2NH3]+·H2PO4−, contains one 4-fluorobenzylammonium cation and one dihydrogen phosphate anion. In the crystal, the H2PO4− anions are linked by O—H...O hydrogen bonds to build corrugated layers extending parallel to the ab plane. The FC6H4CH2NH3+ cations lie between these anionic layers to maximize the electrostatic interactions and are linked to the H2PO4− anions through N—H...O hydrogen bonds, forming a three-dimensional supramolecular network. Two hydrogen atoms belonging to the dihydrogen phosphate anion are statistically occupied due to disorder along the OH...HO direction.

A proposed abiotic reaction scheme for hydroxylamine and monochloramine under chloramination relevant drinking water conditions.

Science.gov (United States)

Wahman, David G; Speitel, Gerald E; Machavaram, Madhav V

2014-09-01

Drinking water monochloramine (NH2Cl) use may promote ammonia-oxidizing bacteria (AOB). AOB use (i) ammonia monooxygenase for biological ammonia (NH3) oxidation to hydroxylamine (NH2OH) and (ii) hydroxylamine oxidoreductase for NH2OH oxidation to nitrite. NH2Cl and NH2OH may react, providing AOB potential benefits and detriments. The NH2Cl/NH2OH reaction would benefit AOB by removing the disinfectant (NH2Cl) and releasing their growth substrate (NH3), but the NH2Cl/NH2OH reaction would also provide a possible additional inactivation mechanism besides direct NH2Cl reaction with cells. Because biological NH2OH oxidation supplies the electrons required for biological NH3 oxidation, the NH2Cl/NH2OH reaction provides a direct mechanism for NH2Cl to inhibit NH3 oxidation, starving the cell of reductant by preventing biological NH2OH oxidation. To investigate possible NH2Cl/NH2OH reaction implications on AOB, an understanding of the underlying abiotic reaction is first required. The present study conducted a detailed literature review and proposed an abiotic NH2Cl/NH2OH reaction scheme (RS) for chloramination relevant drinking water conditions (μM concentrations, air saturation, and pH 7-9). Next, RS literature based kinetics and end-products were evaluated experimentally between pHs 7.7 and 8.3, representing (i) the pH range for future experiments with AOB and (ii) mid-range pHs typically found in chloraminated drinking water. In addition, a (15)N stable isotope experiment was conducted to verify nitrous oxide and nitrogen gas production and their nitrogen source. Finally, the RS was slightly refined using the experimental data and an AQUASIM implemented kinetic model. A chloraminated drinking water relevant RS is proposed and provides the abiotic reaction foundation for future AOB biotic experiments. Published by Elsevier Ltd.

Experimental Acidification Causes Soil Base-Cation Depletion at the Bear Brook Watershed in Maine

Science.gov (United States)

Ivan J. Fernandez; Lindsey E. Rustad; Stephen A. Norton; Jeffrey S. Kahl; Bernard J. Cosby

2003-01-01

There is concern that changes in atmospheric deposition, climate, or land use have altered the biogeochemistry of forests causing soil base-cation depletion, particularly Ca. The Bear Brook Watershed in Maine (BBWM) is a paired watershed experiment with one watershed subjected to elevated N and S deposition through bimonthly additions of (NH4)2SO4. Quantitative soil...

A new NH 3 orbital of the NH 3/Ni(110) surface observed by metastable quenching spectroscopy

Science.gov (United States)

Lee, Lihwa; Arias, Jose; Hanrahan, Ciaran; Martin, Richard M.; Metiu, Horia

1986-01-01

By using metastable quenching spectroscopy we have found a new NH 3 filled orbital (in the language of one electron theory) for NH 3/Ni(110), located at the Fermi level of the surface. The orbital is not observed when NH 3 is adsorbed on Ni(110), but it is detected for NH 3 adsorbed on polycrystalline Al.

Crystal structure of [UO2(NH35]NO3·NH3

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Patrick Woidy

2016-12-01

Full Text Available Pentaammine dioxide uranium(V nitrate ammonia (1/1, [UO2(NH35]NO3·NH3, was obtained in the form of yellow crystals from the reaction of caesium uranyl nitrate, Cs[UO2(NO33], and uranium tetrafluoride, UF4, in dry liquid ammonia. The [UO2]+ cation is coordinated by five ammine ligands. The resulting [UO2(NH35] coordination polyhedron is best described as a pentagonal bipyramid with the O atoms forming the apices. In the crystal, numerous N—H...N and N—H...O hydrogen bonds are present between the cation, anion and solvent molecules, leading to a three-dimensional network.

Structural determinants of NH3 and NH4+ transport by mouse Rhbg, a renal Rh glycoprotein.

Science.gov (United States)

Abdulnour-Nakhoul, Solange; Le, Trang; Rabon, Edd; Hamm, L Lee; Nakhoul, Nazih L

2016-12-01

Renal Rhbg is localized to the basolateral membrane of intercalated cells and is involved in NH 3 /NH 4 + transport. The structure of Rhbg is not yet resolved; however, a high-resolution crystal structure of AmtB, a bacterial homolog of Rh, has been determined. We aligned the sequence of Rhbg to that of AmtB and identified important sites of Rhbg that may affect transport. Our analysis positioned three conserved amino acids, histidine 183 (H183), histidine 342 (H342), and tryptophan 230 (W230), within the hydrophobic pore where they presumably serve to control NH 3 transport. A fourth residue, phenylalanine 128 (F128) was positioned at the upper vestibule, presumably contributing to recruitment of NH 4 + We generated three mutations each of H183, H342, W230, and F128 and expressed them in frog oocytes. Immunolabeling showed that W230 and F128 mutants were localized to the cell membrane, whereas H183 and H342 staining was diffuse and mostly intracellular. To determine function, we compared measurements of NH 3 /NH 4 + and methyl amine (MA)/methyl ammonium (MA + )-induced currents, intracellular pH, and surface pH (pHs) among oocytes expressing the mutants, Rhbg, or injected with H 2 O. In H183 and W230 mutants, NH 4 + -induced current and intracellular acidification were inhibited compared with that of Rhbg, and MA-induced intracellular alkalinization was completely absent. Expression of H183A or W230A mutants inhibited NH 3 /NH 4 + - and MA/MA + -induced decrease in pHs to the level observed in H 2 O-injected oocytes. Mutations of F128 did not significantly affect transport of NH 3 or NH 4 + These data demonstrated that mutating H183 or W230 caused loss of function but not F128. H183 and H342 may affect membrane expression of the transporter.

THEORETICAL STUDY OF THE REMOVAL OF THE TROPOSPHERIC FORMALDEHYDE BY REACTION WITH OH* AND NH3* RADICALS

OpenAIRE

Cjuno H., Jesús A.; Arroyo C., Juan; Cubas C., Roger

2014-01-01

In the context of atmospheric chemistry, two reactions radical-molecule of hydrogen abstraction have been studied. These are the OH' and NO3: radical (oxidizers agents in the troposphere) with formaldehyde in gas-phase. The calculations were carried out using the PM3 and . Ab initio methods of the UHF type. The results have allowed us to estimate the corresponding times of tropospheric permanency and the implications of these reactions in the removal of forrnaldehyde and similars from the low...

Crystal structure and characterization of the novel NH+⋯N hydrogen bonded polar crystal [NH2(CH2)4NH][BF4

International Nuclear Information System (INIS)

Wojtaś, M.; Gagor, A.; Czupiński, O.; Medycki, W.; Jakubas, R.

2012-01-01

Dielectric properties and phase transitions of the piperazinium tetrafluoroborate ([NH 2 (CH 2 ) 4 NH][BF 4 ], abbreviated as PFB) crystal are related to the one-dimensional arrangement of the cations linked by the bistable NH + ⋯N hydrogen bonds and molecular motions of the [BF 4 ] − units. The crystal structure of [NH 2 (CH 2 ) 4 NH][BF 4 ] is monoclinic at room temperature with the polar space group Pn. The polar/acentric properties of the room temperature phase IV have been confirmed by the piezoelectric and pyroelectric measurements. DSC measurements show that the compound undergoes three first-order structural phase transitions: at 421/411 K (heating/cooling), at 386/372 K and at 364/349 K. 1 H and 19 F NMR measurements indicate the reorientational motions of [BF 4 ] − anions and piperazinium(+) cations as well as the proton motion in the hydrogen-bonded chains of piperazine along the [001] direction. Over the phase I the isotropic reorientational motions or even self-diffusion of the cations and anions are expected. The conductivity measurements in the vicinity of the II–I PT indicate a superionic phase over the phase I. - Graphical abstract: It must be emphasized that the titled compound represents the first organic–inorganic simple salt containing the single-protonated piperazinium cation which was studied by means of the wide variety of experimental techniques. A survey of Cambridge Structural Database (CSD version 5.32 (November 2010) and updates (May 2011)) for structure containing the piperazinium cations yields 248 compounds with the doubly protonated piperazinium(2+) cations and only eight compounds with the singly protonated piperazinium(+) cations. Among these structures only one is the hybrid organic–inorganic material. This is piperazinium nitrate characterized structurally. The crystal packing of [NH 2 (CH 2 ) 4 NH][BF 4 ], phase IV. The dashed lines stand for the hydrogen bonds. The hydrogen bonds to BF4 groups are not included for

Crystal structure and characterization of the novel NH+⋯N hydrogen bonded polar crystal [NH2(CH2)4NH][BF4

Science.gov (United States)

Wojtaś, M.; Gaģor, A.; Czupiński, O.; Medycki, W.; Jakubas, R.

2012-03-01

Dielectric properties and phase transitions of the piperazinium tetrafluoroborate ([NH2(CH2)4NH][BF4], abbreviated as PFB) crystal are related to the one-dimensional arrangement of the cations linked by the bistable NH+⋯N hydrogen bonds and molecular motions of the [BF4]- units. The crystal structure of [NH2(CH2)4NH][BF4] is monoclinic at room temperature with the polar space group Pn. The polar/acentric properties of the room temperature phase IV have been confirmed by the piezoelectric and pyroelectric measurements. DSC measurements show that the compound undergoes three first-order structural phase transitions: at 421/411 K (heating/cooling), at 386/372 K and at 364/349 K. 1H and 19F NMR measurements indicate the reorientational motions of [BF4]- anions and piperazinium(+) cations as well as the proton motion in the hydrogen-bonded chains of piperazine along the [001] direction. Over the phase I the isotropic reorientational motions or even self-diffusion of the cations and anions are expected. The conductivity measurements in the vicinity of the II-I PT indicate a superionic phase over the phase I.

Communication: Equivalence between symmetric and antisymmetric stretching modes of NH3 in promoting H + NH3 → H2 + NH2 reaction

Science.gov (United States)

Song, Hongwei; Yang, Minghui; Guo, Hua

2016-10-01

Vibrational excitations of reactants sometimes promote reactions more effectively than the same amount of translational energy. Such mode specificity provides insights into the transition-state modulation of reactivity and might be used to control chemical reactions. We report here a state-of-the-art full-dimensional quantum dynamical study of the hydrogen abstraction reaction H + NH3 → H2 + NH2 on an accurate ab initio based global potential energy surface. This reaction serves as an ideal candidate to study the relative efficacies of symmetric and degenerate antisymmetric stretching modes. Strong mode specificity, particularly for the NH3 stretching modes, is demonstrated. It is further shown that nearly identical efficacies of the symmetric and antisymmetric stretching modes of NH3 in promoting the reaction can be understood in terms of local-mode stretching vibrations of the reactant molecule.

Aquaporin 4 as a NH3 Channel

DEFF Research Database (Denmark)

Assentoft, Mette; Kaptan, Shreyas; Schneider, Hans-Peter

2016-01-01

-brain-interface, participate in the exchange of ammonia, which is required to sustain the glutamate-glutamine cycle. Here we observe that AQP4-expressing Xenopus oocytes display a reflection coefficient NH4Cl at pH 8.0, at which pH an increased amount of the ammonia occurs in the form of NH3 Taken together with an NH4......Cl-mediated intracellular alkalization (or lesser acidification) of AQP4-expressing oocytes, these data suggest that NH3 is able to permeate the pore of AQP4. Exposure to NH4Cl increased the membrane currents to a similar extent in uninjected oocytes and in oocytes expressing AQP4, indicating...... that the ionic NH4 (+) did not permeate AQP4. Molecular dynamics simulations revealed partial pore permeation events of NH3 but not of NH4 (+) and a reduced energy barrier for NH3 permeation through AQP4 compared with that of a cholesterol-containing lipid bilayer, suggesting AQP4 as a favored transmembrane...

Extractability of plutonium-238 and curium-242 from a contaminated soil as a function of pH and certain soil components. CH3COOH-NH4OH system

International Nuclear Information System (INIS)

Nishita, H.

1978-01-01

Extractability of 238 Pu and 242 Cm from an artificially contaminated soil as a function of pH and certain soil components was examined with an equilibrium batch technique by the use of a CH 3 COOH--NH 4 OH extracting system. The influence of various soil components on 238 Pu and 242 Cm extractability was determined indirectly by selective removal of the components from the soil. The soil organic matter appeared to have a major influence on the extractability of these radionuclides. Though to a lesser extent, free iron oxides exerted an influence also. Before removal of soil organic matter, the extractability curves for these radionuclides were qualitatively similar in general form. The nature of this form is discussed. Within the contaminated, untreated soil, the 238 Pu and 242 Cm extractability ranged from 0.60 to 30.8% and 0.11 to 14.83% of dose, respectively, depending on the pH of the extracting solution. The liquid-to soild-phase ratio (K'/sub d/) values ranged from 3.5 x 10 -4 to 2.7 x 10 -2 for 238 Pu and 0.9 x 10 -4 to 1.4 x 10 -2 for 242 Cm. Very low extractability occurred in the pH range from approx. 8.6 to approx. 9.7 for 238 Pu and from 7.6 to approx. 9.7 for 242 Cm

Heterogeneous reactions between ions NH3+and NH+andhydrocarbons adsorbed on a tungsten surface.Formation of HCN+in NH+-surface hydrocarbon collisions

Czech Academy of Sciences Publication Activity Database

Harnisch, M.; Scheier, P.; Herman, Zdeněk

2015-01-01

Roč. 392, DEC 2015 (2015), s. 139-144 ISSN 1387-3806 Institutional support: RVO:61388955 Keywords : ion-surface collisions * NH3+ and NH+projectiles * surface hydrocarbons Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.183, year: 2015

Rapid Ammonia Gas Transport Accounts for Futile Transmembrane Cycling under NH3/NH4+ Toxicity in Plant Roots1[C][W

Science.gov (United States)

Coskun, Devrim; Britto, Dev T.; Li, Mingyuan; Becker, Alexander; Kronzucker, Herbert J.

2013-01-01

Futile transmembrane NH3/NH4+ cycling in plant root cells, characterized by extremely rapid fluxes and high efflux to influx ratios, has been successfully linked to NH3/NH4+ toxicity. Surprisingly, the fundamental question of which species of the conjugate pair (NH3 or NH4+) participates in such fluxes is unresolved. Using flux analyses with the short-lived radioisotope 13N and electrophysiological, respiratory, and histochemical measurements, we show that futile cycling in roots of barley (Hordeum vulgare) seedlings is predominately of the gaseous NH3 species, rather than the NH4+ ion. Influx of 13NH3/13NH4+, which exceeded 200 µmol g–1 h–1, was not commensurate with membrane depolarization or increases in root respiration, suggesting electroneutral NH3 transport. Influx followed Michaelis-Menten kinetics for NH3 (but not NH4+), as a function of external concentration (Km = 152 µm, Vmax = 205 µmol g–1 h–1). Efflux of 13NH3/13NH4+ responded with a nearly identical Km. Pharmacological characterization of influx and efflux suggests mediation by aquaporins. Our study fundamentally revises the futile-cycling model by demonstrating that NH3 is the major permeating species across both plasmalemma and tonoplast of root cells under toxicity conditions. PMID:24134887

Vibrational spectroscopic study of poldervaartite CaCa[SiO3(OH)(OH)

Science.gov (United States)

Frost, Ray L.; López, Andrés; Scholz, Ricardo; Lima, Rosa Malena Fernandes

2015-02-01

We have studied the mineral poldervaartite CaCa[SiO3(OH)(OH)] which forms a series with its manganese analogue olmiite CaMn[SiO3(OH)](OH) using a range of techniques including scanning electron microscopy, thermogravimetric analysis, Raman and infrared spectroscopy. Chemical analysis shows the mineral is reasonably pure and contains only calcium and manganese with low amounts of Al and F. Thermogravimetric analysis proves the mineral decomposes at 485 °C with a mass loss of 7.6% compared with the theoretical mass loss of 7.7%. A strong Raman band at 852 cm-1 is assigned to the SiO stretching vibration of the SiO3(OH) units. Two Raman bands at 914 and 953 cm-1 are attributed to the antisymmetric vibrations. Intense prominent peaks observed at 3487, 3502, 3509, 3521 and 3547 cm-1 are assigned to the OH stretching vibration of the SiO3(OH) units. The observation of multiple OH bands supports the concept of the non-equivalence of the OH units. Vibrational spectroscopy enables a detailed assessment of the molecular structure of poldervaartite.

Prospecting and exploration of rare earth bearing mineral resources in India: an overview

International Nuclear Information System (INIS)

Mohanty, R.

2014-01-01

Rare earth elements (REE) have a wide range of applications including nuclear and the REE bearing minerals occur in varied geological environments.The commercial rare earth bearing minerals are monazite ((Ce,La,Pr,Nd,Th,Y)PO 4 ), xenotime (YPO 4 ), bastnasite ((Ce,La,Y)CO 3 F) and pyrochlore ((Na,Ca) 2 Nb 2 O 6 (OH,F) which occur either as placer concentrations or in tracer quantities in rocks. While Monazite contains dominantly LREE, Xenotime and Bastnasite are richer in HREE. The exploration and evaluation of these two types of occurrences follow different methodologies

OH vibrational activation and decay dynamics of CH4-OH entrance channel complexes

International Nuclear Information System (INIS)

Wheeler, Martyn D.; Tsiouris, Maria; Lester, Marsha I.; Lendvay, Gyoergy

2000-01-01

Infrared spectroscopy has been utilized to examine the structure and vibrational decay dynamics of CH 4 -OH complexes that have been stabilized in the entrance channel to the CH 4 +OH hydrogen abstraction reaction. Rotationally resolved infrared spectra of the CH 4 -OH complexes have been obtained in the OH fundamental and overtone regions using an IR-UV (infrared-ultraviolet) double-resonance technique. Pure OH stretching bands have been identified at 3563.45(5) and 6961.98(4) cm-1 (origins), along with combination bands involving the simultaneous excitation of OH stretching and intermolecular bending motions. The infrared spectra exhibit extensive homogeneous broadening arising from the rapid decay of vibrationally activated CH 4 -OH complexes due to vibrational relaxation and/or reaction. Lifetimes of 38(5) and 25(3) ps for CH 4 -OH prepared with one and two quanta of OH excitation, respectively, have been extracted from the infrared spectra. The nascent distribution of the OH products from vibrational predissociation has been evaluated by ultraviolet probe laser-induced fluorescence measurements. The dominant inelastic decay channel involves the transfer of one quantum of OH stretch to the pentad of CH 4 vibrational states with energies near 3000 cm-1. The experimental findings are compared with full collision studies of vibrationally excited OH with CH 4 . In addition, ab initio electronic structure calculations have been carried out to elucidate the minimum energy configuration of the CH 4 -OH complex. The calculations predict a C 3v geometry with the hydrogen of OH pointing toward one of four equivalent faces of the CH 4 tetrahedron, consistent with the analysis of the experimental infrared spectra. (c) 2000 American Institute of Physics

Parallel Changes in Intracellular Water Volume and pH Induced by NH3/NH4+ Exposure in Single Neuroblastoma Cells

Directory of Open Access Journals (Sweden)

Víctor M. Blanco

2013-12-01

Full Text Available Background: Increased blood levels of ammonia (NH3 and ammonium (NH4+, i.e. hyperammonemia, leads to cellular brain edema in humans with acute liver failure. The pathophysiology of this edema is poorly understood. This is partly due to incomplete understanding of the osmotic effects of the pair NH3/NH4+ at the cellular and molecular levels. Cell exposure to solutions containing NH3/NH4+ elicits changes in intracellular pH (pHi, which can in turn affect cell water volume (CWV by activating transport mechanisms that produce net gain or loss of solutes and water. The occurrence of CWV changes caused by NH3/NH4+ has long been suspected, but the mechanisms, magnitude and kinetics of these changes remain unknown. Methods: Using fluorescence imaging microscopy we measured, in real time, parallel changes in pHi and CWV caused by brief exposure to NH3/NH4+ of single cells (N1E-115 neuroblastoma or NG-108 neuroblastoma X glioma loaded with the fluorescent indicator BCECF. Changes in CWV were measured by exciting BCECF at its intracellular isosbestic wavelength (∼438 nm, and pHi was measured ratiometrically. Results: Brief exposure to isosmotic solutions (i.e. having the same osmolality as that of control solutions containing NH4Cl (0.5- 30 mM resulted in a rapid, dose-dependent swelling, followed by isosmotic regulatory volume decrease (iRVD. NH4Cl solutions in which either extracellular [NH3] or [NH4+] was kept constant while the other was changed by varying the pH of the solution, demonstrated that [NH3]o rather than [NH4+]o is the main determinant of the NH4Cl-induced swelling. The iRVD response was sensitive to the anion channel blocker NPPB, and partly dependent on external Ca2+. Upon removal of NH4Cl, cells shrank and displayed isosmotic regulatory volume increase (iRVI. Regulatory volume responses could not be activated by comparable CWV changes produced by anisosmotic solutions, suggesting that membrane stretch or contraction by themselves are

Synthesis, Resistivity, and Thermal Properties of the Cubic Perovskite NH 2CH=NH 2SnI 3and Related Systems

Science.gov (United States)

Mitzi, D. B.; Liang, K.

1997-12-01

Combining concentrated hydriodic acid solutions of tin(II) iodide and formamidine acetate in an inert atmosphere results in the precipitation of a new conducting organic-inorganic compound, NH 2CH=NH 2SnI 3, which at room temperature adopts a cubic perovskite structure. The lattice constant for NH 2CH=NH 2SnI 3is found to be a=6.316(1) Å, which is approximately 1.2% larger than that for the isostructural compound CH 3NH 3SnI 3. The electrical resistivity of a pressed pellet of the new compound exhibits semimetallic temperature dependence from 10 to 300 K, with evidence of a structural transition at approximately 75 K. NH 2CH=NH 2SnI 3begins to slowly decompose in an inert atmosphere at temperatures as low as 200°C, with bulk decomposition/melting occurring above 300°C. The properties of the formamidinium-based perovskite are compared with those of the related cubic (at room temperature) perovskite CH 3NH 3SnI 3and the mixed-cation system (CH 3NH 3) 1- x(NH 2CH=NH 2) xSnI 3.

Optimization, biological evaluation and microPET imaging of copper-64-labeled bombesin agonists, [64Cu-NO2A-(X)-BBN(7-14)NH2], in a prostate tumor xenografted mouse model

International Nuclear Information System (INIS)

Lane, Stephanie R.; Nanda, Prasanta; Rold, Tammy L.; Sieckman, Gary L.; Figueroa, Said D.; Hoffman, Timothy J.; Jurisson, Silvia S.; Smith, Charles J.

2010-01-01

Gastrin-releasing peptide receptors (GRPr) are a member of the bombesin (BBN) receptor family. GRPr are expressed in high numbers on specific human cancers, including human prostate cancer. Therefore, copper-64 ( 64 Cu) radiolabeled BBN(7-14)NH 2 conjugates could have potential for diagnosis of human prostate cancer via positron-emission tomography (PET). The aim of this study was to produce [ 64 Cu-NO2A-(X)-BBN(7-14)NH 2 ] conjugates for prostate cancer imaging, where X=pharmacokinetic modifier (beta-alanine, 5-aminovaleric acid, 6-aminohexanoic acid, 8-aminooctanoic acid, 9-aminonanoic acid or para-aminobenzoic acid) and NO2A=1,4,7-triazacyclononane-1,4-diacetic acid [a derivative of NOTA (1,4,7-triazacyclononane-1,4,7-triacetic acid)]. Methods: [(X)-BBN(7-14)NH 2 ] Conjugates were synthesized by solid-phase peptide synthesis (SPPS), after which NOTA was added via manual conjugation. The new peptide conjugates were radiolabeled with 64 Cu radionuclide. The receptor-binding affinity was determined in human prostate PC-3 cells, and tumor-targeting efficacy was determined in PC-3 tumor-bearing severely combined immunodeficient (SCID) mice. Whole-body maximum intensity microPET/CT images of PC-3 tumor-bearing SCID mice were obtained 18 h postinjection (pi). Results: Competitive binding assays in PC-3 cells indicated high receptor-binding affinity for the [NO2A-(X)-BBN(7-14)NH 2 ] and [ nat Cu-NO2A-(X)-BBN(7-14)NH 2 ] conjugates. In vivo biodistribution studies of the [ 64 Cu-NO2A-(X)-BBN(7-14)NH 2 ] conjugates at 1, 4 and 24 h pi showed very high uptake of the tracer in GRPr-positive tissue with little accumulation and retention in nontarget tissues. High-quality, high-contrast microPET images were obtained, with xenografted tumors being clearly visible at 18 h pi. Conclusions: NO2A chelator sufficiently stabilizes copper(II) radiometal under in vivo conditions, producing conjugates with very high uptake and retention in targeted GRPr. Preclinical evaluation of these

Raman spectra from very concentrated aqueous NaOH and from wet and dry, solid, and anhydrous molten, LiOH, NaOH, and KOH.

Science.gov (United States)

Walrafen, George E; Douglas, Rudolph T W

2006-03-21

High-temperature, high-pressure Raman spectra were obtained from aqueous NaOH solutions up to 2NaOHH2O, with X(NaOH)=0.667 at 480 K. The spectra corresponding to the highest compositions, X(NaOH)> or =0.5, are dominated by H3O2-. An IR xi-function dispersion curve for aqueous NaOH, at 473 K and 1 kbar, calculated from the data of Franck and Charuel indicates that the OH- ion forms H3O2- by preferential H bonding with nonhydrogen-bonded OH groups. Raman spectra from wet to anhydrous, solid LiOH, NaOH, and KOH yield sharp, symmetric OH- stretching peaks at 3664, 3633, and 3596 cm(-1), respectively, plus water-related, i.e., H3O2-, peaks near LiOH, 3562 cm(-1), NaOH, 3596 cm(-1), and, KOH, 3500 cm(-1). Absence of H3O2- peaks from the solid assures that the corresponding melt is anhydrous. Raman spectra from the anhydrous melts yield OH- stretching peak frequencies: LiOH, 3614+/-4 cm(-1), 873 K; NaOH, 3610+/-2 cm(-1), 975 K; and, KOH, 3607+/-2 cm(-1), 773 K, but low-frequency asymmetry due to ion-pair interactions is present which is centered near 3550 cm(-1). The ion-pair-related asymmetry corresponds to the sole IR maximum near 3550 cm(-1) from anhydrous molten NaOH, at 623 K. Bose-Einstein correction of published low-frequency Raman data from molten LiOH revealed an acoustic phonon, near 205 cm(-1), related to restricted translation of OH- versus Li+, and an optical phonon, at 625 cm(-1) and tau approximately 0.05 ps, due to protonic precession and/or pendular motion. Strong H bonding between water and the O atom of OH- forms H3O2-, but the proton of OH- does not bond with H significantly. Large Raman bandwidths (aqueous solutions) are explained in terms of inhomogeneous broadening due to proton transfer in a double well. Vibrational assignments are presented for H3O2-.

A thermodynamic model for the solubility of NpO2(am) in the aqueous K+-HCO3--CO32--OH--H2O system

International Nuclear Information System (INIS)

Rai, D.; Hess, N.J.; Felmy, A.R.; Moore, D.A.; Yui, M.

1999-01-01

Solubility of NpO 2 (am) was determined in the aqueous K + -HCO 3 - -CO 3 2- -OH - -H 2 O system extending to high concentrations of carbonate, bicarbonate, and mixed carbonate-hydroxide. Several reducing agents (Fe powder, Na 2 S 2 O 4 , NH 2 . NH 2 , and NH 2 OH . HCl) were tested for their effectiveness to maintain neptunium in the tetravalent state. Of these reducing agents, Na 2 S 2 O 4 was found to be the most effective. Even in the presence of Na 2 S 2 O 4 , significant oxidation of Np(IV) to Np(V) occurred in samples containing relatively low concentrations of carbonate/bicarbonate, relatively high concentrations of hydroxide, and samples equilibrated for relatively long periods. X-ray absorption spectroscopy (XAS) and solvent extraction were used to identify aqueous species and oxidation states and to help select appropriate data sets for thermodynamic interpretations. The dominant aqueous species in CO 3 2- and relatively concentrated HCO 3 - solutions was found by XAS to be Np(CO 3 ) 5 6- . Solubility of NpO 2 (am) in carbonate and bicarbonate solutions increased dramatically with increasing molal concentrations (carbonate >0.1 moles per kg H 2 O (m) and bicarbonate >0.01 m), indicating that carbonate makes strong complexes with Np(IV). The dominant Np(IV)-carbonate species that reasonably described all of the experimental data were Np(CO 3 ) 5 6- in low to high concentrations of carbonate and hydroxide and in high concentrations of bicarbonate, and Np(OH) 2 (CO 3 ) 2 2- in low concentrations of bicarbonate. The logarithm of the thermodynamic equilibrium constants for the NpO 2 (am) dissolution reactions involving these species [(NpO 2 (am) + 5 CO 3 2- + 4 H + Np(CO 3 ) 3 6- + 2 H 2 O) and (NpO 2 (am) + 2 HCO 3 - Np(OH) 2 (CO 3 ) 2 2- )] were found to be 34.85 and -4.44, respectively. These values, when combined with the solubility product of NpO 2 (am) [log K Sp = -54.9 [1, and recent unpublished data from Rai et al.

Characteristics of N2O production and hydroxylamine variation in short-cut nitrification SBR process.

Science.gov (United States)

Hu, Bo; Ye, Junhong; Zhao, Jianqiang; Ding, Xiaoqian; Yang, Liwei; Tian, Xiaolei

2018-01-01

In order to study the characteristics of nitrous oxide (N 2 O) production and hydroxylamine (NH 2 OH) variation under oxic conditions, concentrations of NH 2 OH and N 2 O were simultaneously monitored in a short-cut nitrification sequencing batch reactor (SBR) operated with different influent ammonia concentrations. In the short-cut nitrification process, N 2 O production was increased with the increasing of ammonia concentration in influent. The maximum concentrations of dissolved N 2 O-N in the reactor were 0.11 mg/L and 0.52 mg/L when ammonia concentrations in the influent were 50 mg/L and 70 mg/L respectively. Under the low and medium ammonia load phases, the concentrations of NH 2 OH-N in the reactor were remained at a low level which fluctuated around 0.06 mg/L in a small range, and did not change with the variation of influent NH 4 + -N concentration. Based on the determination results, the half-saturation of NH 2 OH in the biochemical conversion process of NH 2 OH to NO 2 - -N was very small, and the value of 0.05 mg NH 2 OH-N/L proposed in the published literature was accurate. NH 2 OH is an important intermediate in the nitrification process, and the direct determination of NH 2 OH in the nitrification process was beneficial for revealing the kinetic process of NH 2 OH production and consumption as well as the effects of NH 2 OH on N 2 O production in the nitrification process.

NH4HCO3 gas-generating liposomal nanoparticle for photoacoustic imaging in breast cancer

Directory of Open Access Journals (Sweden)

Xia J

2017-03-01

Full Text Available Jizhu Xia, Gang Feng, Xiaorong Xia, Lan Hao, Zhigang Wang Chongqing Key Laboratory of Ultrasound Molecular Imaging, Department of Ultrasound, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, People’s Republic of China Abstract: In this study, we have developed a biodegradable nanomaterial for photoacoustic imaging (PAI. Its biodegradation products can be fully eliminated from a living organism. It is a gas-generating nanoparticle of liposome-encapsulating ammonium bicarbonate (NH4HCO3 solution, which is safe, effective, inexpensive, and free of side effects. When lasers irradiate these nanoparticles, NH4HCO3 decomposes to produce CO2, which can absorb much of the light energy under laser irradiation with a specific wavelength, and then expand under heat to generate a thermal acoustic wave. An acoustic detector can detect this wave and show it as a photoacoustic signal on a display screen. The intensity of the photoacoustic signal is enhanced corresponding to an increase in time, concentration, and temperature. During in vivo testing, nanoparticles were injected into tumor-bearing nude mice through the caudal vein, and photoacoustic signals were detected from the tumor, reaching a peak in 4 h, and then gradually disappearing. There was no damage to the skin or subcutaneous tissue from laser radiation. Our developed gas-generating nanomaterial, NH4HCO3 nanomaterial, is feasible, effective, safe, and inexpensive. Therefore, it is a promising material to be used in clinical PAI. Keywords: Photoacoustic tomography, CO2, NH4HCO3, contrast agent, cancer

Interaction between OHS regulation and OHS certification in Denmark

DEFF Research Database (Denmark)

Hendriksen, Kåre; Jørgensen, Kirsten; Jørgensen, Ulrik

2010-01-01

In 2001, the Danish Parliament approved a law on OHS certification that provided economic support to enterprises/organizations that were certified according to one of the two national OHS standards. These certified enterprises/organizations were also exempt from the initial inspection by the Danish...... Working Environment Authority, which they would otherwise be required to pay for. In practice, this meant that inspection of the certified enterprises was transferred to the certification bodies unless a work accident or work-caused ailment or the like was reported. In 2005, the law was revised so...... certification has existed as a form of substitute inspection for almost 10 years, no systematic evaluation of the effects of OHS certification on the OHS, and thereby the validity of the certificate, has been made. In several cases, however, certified enterprises/organizations have received injunctions...

Preparation of Mg(OH)_2 hybrid pigment by direct precipitation and graft onto cellulose fiber via surface-initiated atom transfer radical polymerization

International Nuclear Information System (INIS)

Wang, Xiao; Zhang, Yue; Lv, Lihua; Cui, Yongzhu; Wei, Chunyan; Pang, Guibing

2016-01-01

Graphical abstract: - Highlights: • Adsorbed anionic dye molecules are conducive to preferential growth of (0 0 1) plane of Mg(OH)_2 crystal for Mg(OH)_2 pigments. • Uniform coverage of nanosized Mg(OH)_2 pigments on fiber surface is achieved via surface-initiated ATRP. • About 4 wt% of Mg(OH)_2 pigment on fiber surface shortens nearly half of burning time of cellulose. - Abstract: Mg(OH)_2 flame retardant hybrid pigment is synthesized through simultaneous solution precipitation and adsorption of anionic dyes (C.I. Acid Red 6). The Mg(OH)_2 hybrid pigment bearing vinyl groups after surface silane modification is immobilized onto the surface of bromo end-functional cellulose fiber by atom transfer radical polymerization (ATRP). The morphology and structure of Mg(OH)_2 pigments and cellulose fibers grafted with modified pigments are characterized. The thermal properties, flammability and color fastness of cellulose fibers grafted with modified pigments are measured. The results reveal that anionic dye molecules are adsorbed onto Mg(OH)_2 crystals and affect the formation of lamella-like Mg(OH)_2 crystals. The cellulose fiber grafted with modified Mg(OH)_2 hybrid pigment absorbs about four times heat more than original cellulose fiber with about 4% immobilization ratio of pigment, which shortens nearly half of afterflame time and afterglow time.

Aluminum (III) and gallium (III) complexes with methyliminodiacetic acid: Crystal structures of Cat[M(Mida)2] (Cat+=Na, K, NH4; M3+=Al, Ga) and Me4N[Ga(Mida)2]·H2O

International Nuclear Information System (INIS)

Ilyukhin, A.B.; Petrosyants, S.P.; Milovanov, S.V.; Malyarik, M.A.

1997-01-01

The bis chelate complexes Cat[M(Mida) 2 ] and Me 4 N[Ga(Mida) 2 ]·H 2 O are synthesized from aqueous solutions M(NO 3 ) 3 -2H 2 Mida-CatOH (M 3+ =Al, Ga; Cat + =Na, K, NH 4 ) and Ga(OH) 3 -2H 2 Mida-Me 4 NOH. The crystal structures of the isostructural compounds Cat[M(Mida) 2 ] (Cat=Na, M=Al; Cat=K, M=Al; Cat=Na, M=Ga) and Me 4 N[Ga(Mida) 2 ]·H 2 O are determined by X-ray structure analysis. According to the X-ray powder diffraction analysis, all the six compounds Cat[M(Mida) 2 ] (Cat=Na, K, NH 4 ; M=Al, Ga) are isostructural. The octahedral anion in Cat[M(Mida) 2 ] and Me 4 N[Ga(Mida) 2 ]·H 2 O exhibits a trans(N)- fac configuration

OH+ IN DIFFUSE MOLECULAR CLOUDS

International Nuclear Information System (INIS)

Porras, A. J.; Federman, S. R.; Welty, D. E.; Ritchey, A. M.

2014-01-01

Near ultraviolet observations of OH + and OH in diffuse molecular clouds reveal a preference for different environments. The dominant absorption feature in OH + arises from a main component seen in CH + (that with the highest CH + /CH column density ratio), while OH follows CN absorption. This distinction provides new constraints on OH chemistry in these clouds. Since CH + detections favor low-density gas with small fractions of molecular hydrogen, this must be true for OH + as well, confirming OH + and H 2 O + observations with the Herschel Space Telescope. Our observed correspondence indicates that the cosmic ray ionization rate derived from these measurements pertains to mainly atomic gas. The association of OH absorption with gas rich in CN is attributed to the need for a high enough density and molecular fraction before detectable amounts are seen. Thus, while OH + leads to OH production, chemical arguments suggest that their abundances are controlled by different sets of conditions and that they coexist with different sets of observed species. Of particular note is that non-thermal chemistry appears to play a limited role in the synthesis of OH in diffuse molecular clouds

Low Temperature Catalyst for NH3 Removal

Science.gov (United States)

Monje, Oscar; Melendez, Orlando

2013-01-01

Air revitalization technologies maintain a safe atmosphere inside spacecraft by the removal of C02, ammonia (NH3), and trace contaminants. NH3 onboard the International Space Station (ISS) is produced by crew metabolism, payloads, or during an accidental release of thermal control refrigerant. Currently, the ISS relies on removing NH3 via humidity condensate and the crew wears hooded respirators during emergencies. A different approach to cabin NH3 removal is to use selective catalytic oxidation (SCO), which builds on thermal catalytic oxidation concepts that could be incorporated into the existing TCCS process equipment architecture on ISS. A low temperature platinum-based catalyst (LTP-Catalyst) developed at KSC was used for converting NH3 to H20 and N2 gas by SCO. The challenge of implementing SCO is to reduce formation of undesirable byproducts like NOx (N20 and NO). Gas mixture analysis was conducted using FTIR spectrometry in the Regenerable VOC Control System (RVCS) Testbed. The RVCS was modified by adding a 66 L semi-sealed chamber, and a custom NH3 generator. The effect of temperature on NH3 removal using the LTP-Catalyst was examined. A suitable temperature was found where NH3 removal did not produce toxic NO, (NO, N02) and N20 formation was reduced.

Two-center three-electron bonding in ClNH{sub 3} revealed via helium droplet infrared laser Stark spectroscopy: Entrance channel complex along the Cl + NH{sub 3} → ClNH{sub 2} + H reaction

Energy Technology Data Exchange (ETDEWEB)

Moradi, Christopher P.; Douberly, Gary E., E-mail: douberly@uga.edu [Department of Chemistry, University of Georgia, Athens, Georgia 30602-2556 (United States); Xie, Changjian; Guo, Hua [Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131 (United States); Kaufmann, Matin [Department of Physical Chemistry II, Ruhr-University Bochum, D-44801 Bochum (Germany)

2016-04-28

Pyrolytic dissociation of Cl{sub 2} is employed to dope helium droplets with single Cl atoms. Sequential addition of NH{sub 3} to Cl-doped droplets leads to the formation of a complex residing in the entry valley to the substitution reaction Cl + NH{sub 3} → ClNH{sub 2} + H. Infrared Stark spectroscopy in the NH stretching region reveals symmetric and antisymmetric vibrations of a C{sub 3v} symmetric top. Frequency shifts from NH{sub 3} and dipole moment measurements are consistent with a ClNH{sub 3} complex containing a relatively strong two-center three-electron (2c–3e) bond. The nature of the 2c–3e bonding in ClNH{sub 3} is explored computationally and found to be consistent with the complexation-induced blue shifts observed experimentally. Computations of interconversion pathways reveal nearly barrierless routes to the formation of this complex, consistent with the absence in experimental spectra of two other complexes, NH{sub 3}Cl and Cl–HNH{sub 2}, which are predicted in the entry valley to the hydrogen abstraction reaction Cl + NH{sub 3} → HCl + NH{sub 2}.

Improved GaSb surfaces using a (NH4)2S/(NH4)2S04 solution

International Nuclear Information System (INIS)

Murape, D.M.; Eassa, N.; Nyamhere, C.; Neethling, J.H.; Betz, R.; Coetsee, E.; Swart, H.C.; Botha, J.R.; Venter, A.

2012-01-01

Bulk (1 0 0) n-GaSb surfaces have been treated with a sulphur based solution ((NH 4 ) 2 S/(NH 4 ) 2 SO 4 ) to which sulphur has been added, not previously reported for the passivation of GaSb surfaces. Au/n-GaSb Schottky barrier diodes (SBDs) fabricated on the treated material show significant improvement compared to that of the similar SBDs on the as-received material as evidenced by the lower ideality factor (n), higher barrier height (φ b ) and lower contact resistance obtained. Additionally, the reverse leakage current, although not saturating, has been reduced by almost an order of magnitude at −0.2 V. The sample surfaces were studied by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The native oxide, Sb–O, present on the as-received material is effectively removed on treating with ([(NH 4 ) 2 S/(NH 4 ) 2 SO 4 ]+S) and (NH 4 ) 2 S. Analysis of the as-received surface by XPS, prior to and after argon sputtering, suggests that the native oxide layer is ≤8.5 nm.

Control of cavitation using dissolved carbon dioxide for damage-free megasonic cleaning of wafers

Science.gov (United States)

Kumari, Sangita

equilibria revealed that the loss of released CO2(aq) upon increase in pH can be compensated by moderate increase in added NH4HCO3. Using this method, simultaneous control of SL and solution pH was demonstrated in two systems, NH4HCO3/HCl and NH4OH/CO2, at two nominal pH values; 5.7 and 7.0. Damage studies were performed on wafer samples with line/space patterns donated by IMEC and FSI International bearing Si/metal/a-Si gate stacks of thickness ~36 nm and Si/Poly-Si gate stacks of thickness ~67 nm, respectively. A single wafer spin cleaning tool MegPieRTM was used for the generation of megasonic energy for inducing damage to the structures. It was demonstrated that CO2 dissolution in DI water suppresses damage to the gate stacks in a dose-dependent manner. Together, these studies establish a systematic and strong correlation between CO2(aq) concentration, SL suppression and damage suppression. Significant damage reduction (~50 % to ~90 %) was observed at [CO2(aq)] > ~300 ppm. It was also demonstrated that CO2(aq) suppresses damage under alkaline pH condition too. This demonstration was made possible by the successful design of two new cleaning systems NH4HCO3/NH4OH and CO2/NH 4OH that could generate CO2(aq) under alkaline conditions. Damage suppressing ability of the newly designed cleaning systems were compared to the standard cleaning system NH4OH at pH 8.2 and it was found that NH4HCO3/NH4OH and CO2/NH 4OH systems were 80 % more efficient in suppressing damage compared to the standard NH4OH cleaning system. Finally, megasonic cleaning studies were conducted in the same single wafer spin cleaning tool MegPieRTM, using SiO2 particles (size 185 nm) deposited on 200 mm oxide Si wafers, as the contaminant. It was found that the standard cleaning chemical, NH4OH, pH 8.2, was effective in achieving > 95 % particle removal for 2 min irradiation of megasonic energy at power densities > 0.7 W/cm2. Based on these results, a new system, NH4HCO3/NH4OH, was designed with an aim to

A possible answer to the mysterious non-detection of hydroxylamine in space: the thermal desorption mechanism

Science.gov (United States)

Jonusas, Mindaugas; Krim, Lahouari

2016-06-01

The presence of NH2OH, one of the main precursors in the formation of amino-acids, on dust grain mantles, may be the most obvious elucidation for the creation of large pre-biotic molecules in the interstellar medium. However, while many laboratory experimental studies, to simulate the icy grain chemistry in space, found that NH2OH molecules may be easily formed in solid phase with high abundances and then they should desorb, through a temperature-induced desorption into the gas phase, with the same high abundances; all the spatial observations conclude that NH2OH is not detected in gas phase within any of the explored astronomical sources. Such inconsistencies between laboratory experiment simulations and spatial observations lead our investigations towards this experimental study to see if there is any chemical transformation of NH2OH, occurring in the solid phase before the desorption processes of NH2OH from the mantle of interstellar icy grains. Our experimental results show that the heating of NH2OH-H2O ices lead to a decomposition of NH2OH into HNO, NH3 and O2, even before reaching its desorption temperature. We show through this work that the NH2OH non-detection from previous examined astronomical sources could mainly due to its high reactivity in solid phase on the icy interstellar grains.

Photodissociation thresholds of OH produced from CH sub 3 OH in solid neon and argon

CERN Document Server

Cheng, B M; Lo, W J; Lee, Y P

2001-01-01

Photodissociation thresholds of OH from CH sub 3 OH in solid Ne and Ar were determined via photolysis of CH sub 3 OH/Ne and CH sub 3 OH/Ar (1/200) samples in situ at 4 K. The samples were irradiated with VUV synchrotron radiation after dispersion by a Seya-Namioka monochromator. The OH photo-product was detected by means of laser-induced fluorescence technique. The increase of fluorescent intensity of OH was monitored and recorded after the matrix sample was irradiated at different wavelengths for 3-5 min. Photodissociation threshold energies of 7.13+-0.02 eV (174.0+-0.5 nm) and 7.08+-0.04 eV (175.0+-1.0 nm) were measured for OH production of CH sub 3 OH in solid Ne and Ar, respectively.

Synthesis of Al(OH3 Nanostructures from Al(OH3 Microagglomerates via Dissolution-Precipitation Route

Directory of Open Access Journals (Sweden)

Bo Yu

2013-01-01

Full Text Available A facile method was developed to synthesize Al(OH3 nanostructures from Al(OH3 microagglomerates by dissolution in 9.0 mol·L−1 NaOH at 115°C followed by dilution and aging of the solution at room temperature. The influence of Al(OH3 nanoseed and surfactants as sodium dodecyl sulfate (SDS, polyethylene glycol 6000 (PEG6000, and cetyltrimethylammonium bromide (CTAB on the formation of the Al(OH3 nano-structures was investigated. The experimental results indicated that the Al(OH3 microspheres composed of nanoparticles were prepared in the blank experiment, while dispersive Al(OH3 nano-particles with a diameter of 80–100 nm were produced in the presence of Al(OH3 nano-seed and CTAB.

Synthesis and biological evaluation of copper-64 radiolabeled [DUPA-6-Ahx-(NODAGA)-5-Ava-BBN(7-14)NH2], a novel bivalent targeting vector having affinity for two distinct biomarkers (GRPr/PSMA) of prostate cancer

International Nuclear Information System (INIS)

Bandari, Rajendra Prasad; Jiang, Zongrun; Reynolds, Tamila Stott; Bernskoetter, Nicole E.; Szczodroski, Ashley F.; Bassuner, Kurt J.; Kirkpatrick, Daniel L.; Rold, Tammy L.; Sieckman, Gary L.; Hoffman, Timothy J.; Connors, James P.; Smith, Charles J.

2014-01-01

Gastrin-releasing peptide receptors (GRPr) and prostate-specific membrane antigen (PSMA) are two identifying biomarkers expressed in very high numbers on prostate cancer cells and could serve as a useful tool for molecular targeting and diagnosis of disease via positron-emission tomography (PET). The aim of this study was to produce the multipurpose, bivalent [DUPA-6-Ahx-( 64 Cu-NODAGA)-5-Ava-BBN(7-14)NH 2 ] radioligand for prostate cancer imaging, where DUPA = (2-[3-(1,3-dicarboxypropyl)-ureido]pentanedioic acid), a small-molecule, PSMA-targeting probe, 6Ahx = 6-aminohexanoic acid, 5-Ava = 5-aminovaleric acid, NODAGA = [2-(4,7-biscarboxymethyl)-1,4,7-(triazonan-1-yl)pentanedioic acid] (a derivative of NOTA (1,4,7-triazacyclononane-1,4,7-triacetic acid)), and BBN(7-14)NH 2 = bombesin, a GRPr-specific peptide targeting probe. Methods: The PSMA/GRPr dual targeting ligand precursor [DUPA-6-Ahx-K-5-Ava-BBN(7-14)NH 2 ], was synthesized by solid-phase and manual peptide synthesis, after which NODAGA was added via manual conjugation to the ε-amine of lysine (K). The new bivalent GRPr/PSMA targeting vector was purified by reversed-phase high performance liquid chromatography (RP-HPLC), characterized by electrospray-ionization mass spectrometry (ESI-MS), and metallated with 64 CuCl 2 and nat CuCl 2 . The receptor binding affinity was evaluated in human, prostate, PC-3 (GRPr-positive) and LNCaP (PSMA-positive) cells and the tumor-targeting efficacy determined in severe combined immunodeficient (SCID) and athymic nude mice bearing PC-3 and LNCaP tumors. Whole-body maximum intensity microPET/CT images of PC-3/LNCaP tumor-bearing mice were obtained 18 h post-injection (p.i.). Results: Competitive binding assays in PC-3 and LNCaP cells indicated high receptor binding affinity for the [DUPA-6-Ahx-( nat Cu-NODAGA)-5-Ava-BBN(7-14)NH 2 ] conjugate. MicroPET scintigraphy in PC-3/LNCaP tumor-bearing mice indicated that xenografted tumors were visible at 18 h p.i. with collateral

Synthesis and biological evaluation of copper-64 radiolabeled [DUPA-6-Ahx-(NODAGA)-5-Ava-BBN(7-14)NH2], a novel bivalent targeting vector having affinity for two distinct biomarkers (GRPr/PSMA) of prostate cancer.

Science.gov (United States)

Bandari, Rajendra Prasad; Jiang, Zongrun; Reynolds, Tamila Stott; Bernskoetter, Nicole E; Szczodroski, Ashley F; Bassuner, Kurt J; Kirkpatrick, Daniel L; Rold, Tammy L; Sieckman, Gary L; Hoffman, Timothy J; Connors, James P; Smith, Charles J

2014-04-01

Gastrin-releasing peptide receptors (GRPr) and prostate-specific membrane antigen (PSMA) are two identifying biomarkers expressed in very high numbers on prostate cancer cells and could serve as a useful tool for molecular targeting and diagnosis of disease via positron-emission tomography (PET). The aim of this study was to produce the multipurpose, bivalent [DUPA-6-Ahx-((64)Cu-NODAGA)-5-Ava-BBN(7-14)NH2] radioligand for prostate cancer imaging, where DUPA = (2-[3-(1,3-dicarboxypropyl)-ureido]pentanedioic acid), a small-molecule, PSMA-targeting probe, 6Ahx = 6-aminohexanoic acid, 5-Ava = 5-aminovaleric acid, NODAGA = [2-(4,7-biscarboxymethyl)-1,4,7-(triazonan-1-yl)pentanedioic acid] (a derivative of NOTA (1,4,7-triazacyclononane-1,4,7-triacetic acid)), and BBN(7-14)NH2 = bombesin, a GRPr-specific peptide targeting probe. The PSMA/GRPr dual targeting ligand precursor [DUPA-6-Ahx-K-5-Ava-BBN(7-14)NH2], was synthesized by solid-phase and manual peptide synthesis, after which NODAGA was added via manual conjugation to the ε-amine of lysine (K). The new bivalent GRPr/PSMA targeting vector was purified by reversed-phase high performance liquid chromatography (RP-HPLC), characterized by electrospray-ionization mass spectrometry (ESI-MS), and metallated with (64)CuCl2 and (nat)CuCl2. The receptor binding affinity was evaluated in human, prostate, PC-3 (GRPr-positive) and LNCaP (PSMA-positive) cells and the tumor-targeting efficacy determined in severe combined immunodeficient (SCID) and athymic nude mice bearing PC-3 and LNCaP tumors. Whole-body maximum intensity microPET/CT images of PC-3/LNCaP tumor-bearing mice were obtained 18 h post-injection (p.i.). Competitive binding assays in PC-3 and LNCaP cells indicated high receptor binding affinity for the [DUPA-6-Ahx-((nat)Cu-NODAGA)-5-Ava-BBN(7-14)NH2] conjugate. MicroPET scintigraphy in PC-3/LNCaP tumor-bearing mice indicated that xenografted tumors were visible at 18h p.i. with collateral, background radiation also

Effective identification of (NH4)2CO3 and NH4HCO3 concentrations in NaHCO3 regeneration process from desulfurized waste.

Science.gov (United States)

Govindan, Muthuraman; Karunakaran, Kannan; Nallasamy, Palanisami; Moon, Il Shik

2015-01-01

This work describes the quantitative analysis of (NH4)2CO3 and NH4HCO3 using a simple solution phase titration method. Back titration results at various (NH4)2CO3-NH4HCO3 ratios demonstrated that 6:4 ratio caused a 3% error in their differentiation, but very high errors were found at other ratios. A similar trend was observed for the double indicator method, especially when strong acid HCl was used as a titrant, where still less errors (2.5%) at a middle ratio of (NH4)2CO3-NH4HCO3 was found. Remaining ratios with low (NH4)2CO3 (2:8, 4:6) show high +ve error (found concentration is less) and high (NH4)2CO3 (7:3, 8:2, and 9:1) show high -ve error (found concentration is higher) and vice versa for NH4HCO3. In replacement titration using Na2SO4, at both higher end ratios of (NH4)2CO3-NH4HCO3 (2:8 and 9:1), both -ve and +ve errors were minimized to 75% by partial equilibrium arrest between (NH4)2CO3 and NH2COONH4, instead of more than 100% observed in back titration and only double indicator methods. In the presence of (NH4)2SO4 both -ve and +ve error% are completely reduced to 3±1 at ratios 2:8, 4:6, and 6:4 of (NH4)2CO3-NH4HCO3, which demonstrates that the equilibrium transformation between NH2COONH4 and (NH4)2CO3 is completely controlled. The titration conducted at lower temperature (5 °C) in the presence of (NH4)2SO4 at higher ratios of (NH4)2CO3-NH4HCO3 (7:3, 8:2,and 9:1) shows complete minimization of both -ve and +ve errors to 2±1%, which explains the complete arresting of equilibrium transformation. Finally, the developed method shows 2±1% error in differentiation of CO3(2-) and HCO3(-) in the regeneration process of NaHCO3 from crude desulfurized sample. The developed method is more promising to differentiate CO3(2-) and HCO3(-) in industrial applications. Copyright © 2014 Elsevier B.V. All rights reserved.

Ternary Ni–Cu–OH and Ni–Co–OH electrodes for electrochemical energy storage

KAUST Repository

Alhebshi, Nuha; Alshareef, Husam N.

2015-01-01

In this project, Ni–Cu–OH and Ni–Co–OH ternary electrodes have been prepared. Different Ni:Cu and Ni:Co ratios were deposited by chemical bath deposition (CBD) at room temperature on carbon microfibers. Since Ni(OH)2 is notorious for poor cycling

Synthesis, characterization and flocculation activity of novel Fe(OH)3-polyacrylamide hybrid polymer

International Nuclear Information System (INIS)

Wang Huilong; Cui Jinyan; Jiang Wenfeng

2011-01-01

Highlights: → The preparation of a novel Fe(OH) 3 -PAM hybrid polymer flocculant is achieved via free radical solution polymerization. → Flocculation of kaolin suspensions using this novel Fe(OH) 3 -PAM hybrid polymer flocculant is revealed in this study. → The statistical model was first applied for calculating the thermodynamic parameters for the kaolin flocculating process. - Abstract: A novel Fe(OH) 3 -polyacrylamide inorganic-organic hybrid polymer (FHPAM) was synthesized via free radical solution polymerization initiated by a redox initiation system ((NH 4 ) 2 S 2 O 8 -NaHSO 3 ) in an aqueous medium. Reaction parameters influencing the intrinsic viscosity and the yield of the hybrid polymer, such as initiator concentration, monomer mass fraction, temperature and reaction time were investigated and optimized. The results show that the maximum intrinsic viscosity and up to 94% yields of the hybrid polymer can be achieved using initiator concentration of 0.3% with acrylamide monomer mass fraction of 20% under solution polymerization at 40 deg. C for 7 h. The physicochemical properties of this hybrid flocculant were characterized with TEM, FTIR spectra, TGA, and conductivity. It was found that a chemical bond exists between Fe(OH) 3 colloid and polyacrylamide chains in the FHPAM. The application of the hybrid polymer for the treatment of 2.5 g L -1 kaolin suspension indicates that it had an excellent flocculation capacity and its flocculation efficiency was much better than that of commercial available polyacrylamide (PAM) and polymeric ferric sulfate (PFS). The optimal conditions for the flocculation treatment of kaolin suspension were the FHPAM dosage of 40 mg L -1 at pH 7.0. The thermodynamic parameters for the flocculation process were calculated based on a statistical model. Interpretation of the results was given.

Increasing Hydrogen Density with the Cation-Anion Pair BH4−-NH4+ in Perovskite-Type NH4Ca(BH43

Directory of Open Access Journals (Sweden)

Pascal Schouwink

2015-08-01

Full Text Available A novel metal borohydride ammonia-borane complex Ca(BH42·NH3BH3 is characterized as the decomposition product of the recently reported perovskite-type metal borohydride NH4Ca(BH43, suggesting that ammonium-based metal borohydrides release hydrogen gas via ammonia-borane-complexes. For the first time the concept of proton-hydride interactions to promote hydrogen release is applied to a cation-anion pair in a complex metal hydride. NH4Ca(BH43 is prepared mechanochemically from Ca(BH42 and NH4Cl as well as NH4BH4 following two different protocols, where the synthesis procedures are modified in the latter to solvent-based ball-milling using diethyl ether to maximize the phase yield in chlorine-free samples. During decomposition of NH4Ca(BH43 pure H2 is released, prior to the decomposition of the complex to its constituents. As opposed to a previously reported adduct between Ca(BH42 and NH3BH3, the present complex is described as NH3BH3-stuffed α-Ca(BH42.

Treatment for GaSb surfaces using a sulphur blended (NH4)2S/(NH4)2SO4 solution

International Nuclear Information System (INIS)

Murape, D.M.; Eassa, N.; Neethling, J.H.; Betz, R.; Coetsee, E.; Swart, H.C.; Botha, J.R.; Venter, A.

2012-01-01

A sulphur based chemical, [(NH 4 ) 2 S/(NH 4 ) 2 SO 4 ] to which S has been added, not previously reported for the treatment of (1 0 0) n-GaSb surfaces, is introduced and benchmarked against the commonly used passivants Na 2 S·9H 2 O and (NH 4 ) 2 S. The surfaces of the treated material were studied by scanning electron microscopy (SEM), Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS). It has been found that the native oxides present on the GaSb surface are more effectively removed when treated with ([(NH 4 ) 2 S/(NH 4 ) 2 SO 4 ] + S) than with (NH 4 ) 2 S or Na 2 S·9H 2 O, as evidenced by the ratio of the O 506eV to Sb 457eV AES peaks. XPS results reveal that Sb 2 S 3 /Sb 2 S 5 “replaces” Sb 2 O 3 /Sb 2 O 5 , suggesting that sulphur atoms substitute oxygen atoms in Sb 2 O 3 /Sb 2 O 5 to form Sb-S. It seems sulphurization only partially removes Ga 2 O 3 . Treatment with ([(NH 4 ) 2 S/(NH 4 ) 2 SO 4 ] + S) also results in a noteworthy improvement in the current-voltage (I-V) characteristics of Au/n-GaSb Schottky contacts compared to those fabricated on as-received material.

Analysis of (NH4)2SO4/(NH4)H2PO4 mixtures by thermogravimetry and X-ray diffraction

International Nuclear Information System (INIS)

Perez, Jose; Perez, Eduardo; Vas, Beatriz del; Garcia, Luis; Serrano, Jose Luis

2006-01-01

(NH 4 ) 2 SO 4 and (NH 4 )H 2 PO 4 are the principal components in the powder material used in fire extinguishers. In this paper the mutual influence in their thermal decomposition is investigated by thermogravimetry. Two methods for the quantification of both salts in mixtures (NH 4 ) 2 SO 4 /(NH 4 )H 2 PO 4 are proposed. The first employs thermogravimetry and is based on the measurement of the mass fraction in the 500-550 deg. C interval, once (NH 4 ) 2 SO 4 has totally decomposed to yield gaseous products. The second uses some selected peaks in the X-ray diffractogram

Generation of nanopores during desorption of NH3 from Mg(NH3)6Cl2

DEFF Research Database (Denmark)

Hummelshøj, Jens Strabo; Sørensen, Rasmus Zink; Kostova, M.Y.

2006-01-01

It is shown that nanopores are formed during desorption of NH3 from Mg(NH3)6Cl2, which has been proposed as a hydrogen storage material. The system of nanopores facilitates the transport of desorbed ammonia away from the interior of large volumes of compacted storage material. DFT calculations sh...

A proposed abiotic reaction scheme for hydroxylamine and monochloramine under chloramination relevant drinking water conditions

Science.gov (United States)

Drinking water monochloramine (NH2Cl) use may promote ammonia–oxidizing bacteria (AOB) growth. For biological ammonia (NH3) oxidation, AOB use (i) ammonia monooxygenase for NH3 oxidation to hydroxylamine (NH2OH) and (ii) hydroxylamine oxidoreductase for NH2OH oxidation to nitrit...

Flotation of copper-bearing shale in solutions of inorganic salts and organic reagents

OpenAIRE

Ratajczak Tomasz

2017-01-01

Flotation data on copper-bearing shale in aqueous solutions of inorganic electrolytes (NaCl, Na2SO4, KPF6, NH4Cl) and organic reagents (ethylamine, propylamine) as frothers were presented and discussed. The relationships between shale flotation, surface tension of aqueous solution and foam height during bubbling with air in the flotation system were presented. It has been found that flotation of shale in the presence of inorganic salts the yield was directly proportional to the surface tensio...

The effect of hydroxylamine on the activity and aggregate structure of autotrophic nitrifying bioreactor cultures

DEFF Research Database (Denmark)

Harper, W.F.; Terada, Akihiko; Poly, F.

2009-01-01

Addition of hydroxylamine (NH2OH) to autotrophic biomass in nitrifying bioreactors affected the activity, physical structure, and microbial ecology of nitrifying aggregates. When NH2OH is added to nitrifying cultures in 6-h batch experiments, the initial NH3-N uptake rates were physiologically...... accelerated by a factor of 1.4-13. NH2OH addition caused a 20-40% decrease in the median aggregate size, broadened the shape of the aggregate size distribution by up to 230%, and caused some of the microcolonies to appear slightly more dispersed. Longer term NH2OH addition in fed batch bioreactors decreased...

Molecular beam epitaxy of GaN(0001) utilizing NH3 and/or NH+x ions: Growth kinetics and defect structure

International Nuclear Information System (INIS)

Lee, N.; Powell, R.C.; Kim, Y.; Greene, J.E.

1995-01-01

Gas-source molecular beam epitaxy (GS-MBE), utilizing Ga and NH 3 , and reactive-ion MBE (RIMBE), incorporating both thermal NH 3 and low-energy NH + x ions, were used to grow single crystal GaN(0001) layers on Al 2 O 3 (0001) at temperatures T s between 700 and 850 degree C with deposition rates of 0.2--0.5 μm h -1 . The RIMBE experiments were carried out with incident NH + x /Ga flux ratios J NH + x /J Ga =1.9--3.2 and NH + x acceleration energies E NH + x =45--90 eV. Plan-view and cross-sectional transmission electron microscopy analyses showed that the primary defects in the GS-MBE films were threading dislocations having either pure edge or mixed edge/screw characteristics with Burgers vectors bar b=1/3 left-angle 2 bar 1 bar 10 right-angle, basal-plane stacking faults with displacement vectors bar R=1/6 left-angle 02 bar 23 right-angle, and prismatic stacking faults with bar R=1/2 left-angle bar 1101 right-angle. In the case of RIMBE films, no stacking faults or residual ion-induced defects were observed with E NH + x =45 eV and T s ≥800 degree C. However, increasing E NH + x to ≥60 eV at T s =800 degree C gave rise to the formation of residual ion-induced point-defect clusters observable by transmission electron microscopy (TEM). Increasing T s to 850 degree C with E NH + x ≥60 eV resulted in the ion-induced defects aggregating to form interstitial basal and prismatic dislocation loops, whose number densities depended upon the ion flux, with Burgers vectors 1/2 left-angle 0001 right-angle and 1/3 left-angle 2 bar 1 bar 10 right-angle, respectively. (Abstract Truncated)

Imaging a multidimensional multichannel potential energy surface: Photodetachment of H{sup −}(NH{sub 3}) and NH{sub 4}{sup −}

Energy Technology Data Exchange (ETDEWEB)

Hu, Qichi; Johnson, Christopher J.; Continetti, Robert E., E-mail: hguo@umn.edu, E-mail: rcontinetti@ucsd.edu [Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093-0340 (United States); Song, Hongwei; Guo, Hua, E-mail: hguo@umn.edu, E-mail: rcontinetti@ucsd.edu [Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131 (United States); Li, Jun [School of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400044 (China)

2016-06-28

Probes of the Born-Oppenheimer potential energy surfaces governing polyatomic molecules often rely on spectroscopy for the bound regions or collision experiments in the continuum. A combined spectroscopic and half-collision approach to image nuclear dynamics in a multidimensional and multichannel system is reported here. The Rydberg radical NH{sub 4} and the double Rydberg anion NH{sub 4}{sup −} represent a polyatomic system for benchmarking electronic structure and nine-dimensional quantum dynamics calculations. Photodetachment of the H{sup −}(NH{sub 3}) ion-dipole complex and the NH{sub 4}{sup −} DRA probes different regions on the neutral NH{sub 4} PES. Photoelectron energy and angular distributions at photon energies of 1.17, 1.60, and 2.33 eV compare well with quantum dynamics. Photoelectron-photofragment coincidence experiments indicate dissociation of the nascent NH{sub 4} Rydberg radical occurs to H + NH{sub 3} with a peak kinetic energy of 0.13 eV, showing the ground state of NH{sub 4} to be unstable, decaying by tunneling-induced dissociation on a time scale beyond the present scope of multidimensional quantum dynamics.

Twenty-year inter-annual trends and seasonal variations in precipitation and stream water chemistry at the Bear Brook Watershed in Maine, USA.

Science.gov (United States)

Navrátil, Tomas; Norton, Stephen A; Fernandez, Ivan J; Nelson, Sarah J

2010-12-01

Mean annual concentration of SO4(-2) in wet-only deposition has decreased between 1988 and 2006 at the paired watershed study at Bear Brook Watershed in Maine, USA (BBWM) due to substantially decreased emissions of SO(2). Emissions of NO(x) have not changed substantially, but deposition has declined slightly at BBWM. Base cations, NH4+, and Cl(-) concentrations were largely unchanged, with small irregular changes of Bear Brook (EB), the reference stream, has been slowly responding to reduced but still elevated acid deposition. Calcium and Mg have declined fairly steadily and faster than SO4(-2), with consequent acidification (lower pH and higher inorganic Al). Eighteen years of experimental treatment with (NH(4))(2)SO(4) enhanced acidification of West Bear Brook's (WB) watershed. Despite the manipulation, NH4+ concentration remained below detection limits at WB, while leaching of NO3- increased. The seasonal pattern for NO3- concentrations in WB, however, remained similar to EB. Mean monthly concentrations of SO4(-2) have increased in WB since 1989, initially only during periods of high flow, but gradually also during base flow. Increases in mean monthly concentrations of Ca(2+), Mg(2+), and K(+) due to the manipulation occurred from 1989 until about 1995, during the depletion of base cations in shallow flow paths in WB. Progressive depletion of Ca and Mg at greater soil depth occurred, causing stream concentrations to decline to pre-manipulation values. Mean monthly Si concentrations did not change in EB or WB, suggesting that the manipulation had no effect on mineral weathering rates. DOC concentrations in both streams did not exhibit inter- or intra-annual trends.

R3 Cup Does Not Have a High Failure Rate in Conventional Bearings: A Minimum of 5-Year Follow-Up.

Science.gov (United States)

Teoh, Kar H; Whitham, Robert D J; Golding, David M; Wong, Jenny F; Lee, Paul Y F; Evans, Aled R

2018-02-01

The R3 cementless acetabular system was first marketed in Australia and Europe in 2007. Previous papers have shown high failure rates of the R3 cup with up to 24% with metal-on-metal bearing. There are currently no medium term clinical results on this cup. The aim of the study is to review our results of the R3 acetabular cup with conventional bearings with a minimum of 5-year follow-up. Patients who were implanted with the R3 acetabular cup were identified from our center's arthroplasty database. A total of 293 consecutive total hip arthroplasties were performed in 286 patients. The primary outcome was revision. The secondary outcomes were the Oxford Hip Scores (OHS) and radiographic evaluation. The mean age of the patients was 69.4 years. The mean preoperative OHS was 23 (range 10-34) and the mean OHS was 40 (range 33-48) at the final follow-up. Radiological evaluation showed an excellent ARA score in all patients at 5 years. None of the R3 cups showed osteolysis at the final follow-up. There were 3 revisions in our series, of which 2 R3 cups were revised. The risk of revision was 1.11% at 5 years. Our experience of using the R3 acetabular system with conventional bearings showed high survivorship and is consistent with the allocated Orthopaedic Data Evaluation Panel rating of 5A* as rated in 2015 in the United Kingdom. Copyright © 2017 Elsevier Inc. All rights reserved.

Facile synthesis of Co(OH)2/Al(OH)3 nanosheets with improved electrochemical properties for asymmetric supercapacitor

Science.gov (United States)

Zhao, Cuimei; Ren, Fang; Cao, Yang; Xue, Xiangxin; Duan, Xiaoyue; Wang, Hairui; Chang, Limin

2018-01-01

Sheet-like Co(OH)2/Al(OH)3 or Co(OH)2 nanomaterial has been synthesized on conducting carbon fiber paper (CFP) by a facile one-step electrochemical deposition. The binder-free Co(OH)2/Al(OH)3/CFP displays an improved electrical conductivity, electrochemical activity and material utilization than solitary Co(OH)2, therefore Co(OH)2/Al(OH)3 nanomaterial exhibits improved electrochemical properties (a maximum capacitance of 1006 Fg-1 at 2 Ag-1, with 77% retention even at a high current density of 32 Ag-1, and more than 87% of the capacitance retention after 10000 cycles at 32 Ag-1) in comparison to that of the Co(OH)2/CFP (709 Fg-1, 65%, 79%). In addition, an asymmetric supercapacitor (ASC) fabricated with Co(OH)2/Al(OH)3/CFP positive electrode and AC/CFP negative electrode demonstrates ultrahigh specific capacitance (75.8 Fg-1) and potential window (1.7 V). These encouraging results make these low-cost and eco-friendly materials promising for high-performance energy storage application.

Lamellar-crossing-structured Ni(OH){sub 2}/CNTs/Ni(OH){sub 2} nanocomposite for electrochemical supercapacitor materials

Energy Technology Data Exchange (ETDEWEB)

Wu, Qingnan [Department of Chemistry, State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, Shanghai 200092 (China); Wen, Ming, E-mail: m_wen@tongji.edu.cn [Department of Chemistry, State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, Shanghai 200092 (China); Shanghai Key Lab of Chemical Assessment and Sustainability, Tongji University, Shanghai 200092 (China); Chen, Shipei [Department of Chemistry, State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, Shanghai 200092 (China); Wu, Qingsheng [Department of Chemistry, State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, Shanghai 200092 (China); Shanghai Key Lab of Chemical Assessment and Sustainability, Tongji University, Shanghai 200092 (China)

2015-10-15

Ni(OH){sub 2}/CNTs/Ni(OH){sub 2} lamellar-crossing-nanostructure with a single lamellar spacing of ∼5 nm was effectively constructed through two-phase-interface reaction process followed by the CNTs crossed among the lamellar-nanostructured Ni(OH){sub 2}. The resultant nanocomposite can offer large active surface areas and short diffusion paths for electrons and ions, and is investigated as a potential pseudocapacitor electrode material for electrochemical energy storage applications. Electrochemical data demonstrate that the as-prepared nanocomposite exhibits a high specific capacitance of ∼1600 F g{sup −1} at the scan rate of 1 mV s{sup −1} in 6 M KOH solution at normal pressure and temperature, which is great higher than Ni(OH){sub 2} (∼1200 F g{sup −1}). Furthermore, Ni(OH){sub 2}/CNTs/Ni(OH){sub 2} nanocomposite shows a higher energy density (∼125 Wh kg{sup −1}, 2 A g{sup −1}) and has a slightly decrease of 5% in specific capacitance after 1000 continuous charge/discharge cycles. - Graphical abstract: As-constructed Ni(OH){sub 2}/CNTs/Ni(OH){sub 2} lamellar-crossing-nanostructure exhibits remarkable enhancement in electrochemical stability and high specific capacity of ∼1600 F g{sup −1} at a scan rate of 1 mV s{sup −1}, suggesting promising potential for supercapacitor applications. - Highlights: • New designed lamellar-crossing-structured Ni(OH){sub 2}/CNTs/Ni(OH){sub 2} nanocomposites have been firstly reported in this work. • Ni(OH){sub 2}/CNTs/Ni(OH){sub 2} lamellar-crossing-nanostructures show firm nanostructure and excellent electrochemical stability. • Ni(OH){sub 2}/CNTs/Ni(OH){sub 2} nanocomposites exhibit excellent specific capacitance. • Ni(OH){sub 2}/CNTs/Ni(OH){sub 2} nanocomposites have the potential application in electrochemical energy storage applications.

[Seasonal variation patterns of NH4(+) -N/NO3(-) -N ratio and delta 15 NH4(+) value in rainwater in Yangtze River Delta].

Science.gov (United States)

Xie, Ying-Xin; Zhang, Shu-Li; Zhao, Xu; Xiong, Zheng-Qin; Xing, Guang-Xi

2008-09-01

By using a customized manual rainwater sampler made of polyvinyl chloride plastic, the molar ratio of NH4(+) -N/NO3(-) -N and the natural 15N abundance of NH4(+) (delta 15 NH4(+) in rainwater was monitored all year round from June 2003 to July 2005 at three observation sites (Changshu, Nanjing, and Hangzhou) in the Yangtze River Delta. The results indicated that at the three sites, the NH4(+) -N/NO3(-) -N ratio and the delta 15 NH4(+) value in rainwater had the similar seasonal variation trend, being more obvious in Changshu (rural monitoring type) site than in Nanjing (urban monitoring type) and Hangzhou (urban-rural monitoring type) sites. The NH4(+) -N/NO3(-) -N ratio peaked from early June to early August, declined gradually afterwards, and reached the bottom in winter; while the delta 15 NH4(+) value was negative from late June to mid-August, turned positive from late August to mid or late November, became negative again when winter dominated from December to March, but turned positive again in next May and negative again in next July. These seasonal variation patterns of NH4(+) -N/NO3(-) -N ratio and delta 15 NH4(+) value were found in relation to the application of chemical nitrogen fertilizers during different crop growth periods, and also, the alternation of seasons and the NH3 volatilization from other NH3 emission sources (including excrements of human and animals, nitrogen- polluted water bodies, and organic nitrogen sources, etc.), which could be taken as an indicator of defining the sources and form composition of NH4(+) in atmospheric wet deposition and the intensity of various terrestrial NH3 emission sources.

Synthesis, characterization and flocculation activity of novel Fe(OH){sub 3}-polyacrylamide hybrid polymer

Energy Technology Data Exchange (ETDEWEB)

Wang Huilong; Cui Jinyan [Department of Chemistry, Dalian University of Technology, Dalian 116023 (China); Jiang Wenfeng, E-mail: dlutjiangwf@yahoo.com.cn [Department of Chemistry, Dalian University of Technology, Dalian 116023 (China)

2011-11-01

Highlights: {yields} The preparation of a novel Fe(OH){sub 3}-PAM hybrid polymer flocculant is achieved via free radical solution polymerization. {yields} Flocculation of kaolin suspensions using this novel Fe(OH){sub 3}-PAM hybrid polymer flocculant is revealed in this study. {yields} The statistical model was first applied for calculating the thermodynamic parameters for the kaolin flocculating process. - Abstract: A novel Fe(OH){sub 3}-polyacrylamide inorganic-organic hybrid polymer (FHPAM) was synthesized via free radical solution polymerization initiated by a redox initiation system ((NH{sub 4}){sub 2}S{sub 2}O{sub 8}-NaHSO{sub 3}) in an aqueous medium. Reaction parameters influencing the intrinsic viscosity and the yield of the hybrid polymer, such as initiator concentration, monomer mass fraction, temperature and reaction time were investigated and optimized. The results show that the maximum intrinsic viscosity and up to 94% yields of the hybrid polymer can be achieved using initiator concentration of 0.3% with acrylamide monomer mass fraction of 20% under solution polymerization at 40 deg. C for 7 h. The physicochemical properties of this hybrid flocculant were characterized with TEM, FTIR spectra, TGA, and conductivity. It was found that a chemical bond exists between Fe(OH){sub 3} colloid and polyacrylamide chains in the FHPAM. The application of the hybrid polymer for the treatment of 2.5 g L{sup -1} kaolin suspension indicates that it had an excellent flocculation capacity and its flocculation efficiency was much better than that of commercial available polyacrylamide (PAM) and polymeric ferric sulfate (PFS). The optimal conditions for the flocculation treatment of kaolin suspension were the FHPAM dosage of 40 mg L{sup -1} at pH 7.0. The thermodynamic parameters for the flocculation process were calculated based on a statistical model. Interpretation of the results was given.

N-hydroxylamine is not an intermediate in the conversion of L-arginine to an activator of soluble guanylate cyclase in neuroblastoma N1E-115 cells.

Science.gov (United States)

Pou, S; Pou, W S; Rosen, G M; el-Fakahany, E E

1991-01-01

This study evaluates the role of N-hydroxylamine (NH2OH) in activating soluble guanylate cyclase in the mouse neuroblastoma clone N1E-115. It has been proposed that NH2OH is a putative intermediate in the biochemical pathway for the generation of nitric oxide (NO)/endothelium-derived relaxing factor (EDRF) from L-arginine. NH2OH caused a time- and concentration-dependent increase in cyclic GMP formation in intact cells. This response was not dependent on Ca2+. In cytosol preparations the activation of guanylate cyclase by L-arginine was dose-dependent and required Ca2+ and NADPH. In contrast, NH2OH itself did not activate cytosolic guanylate cyclase but it inhibited the basal activity of this enzyme in a concentration-dependent manner. The formation of cyclic GMP in the cytosolic fractions in response to NH2OH required the addition of catalase and H2O2. On the other hand, catalase and/or H2O2 lead to a decrease in L-arginine-induced cyclic GMP formation. Furthermore, NH2OH inhibited L-arginine- and sodium nitroprusside-induced cyclic GMP formation in the cytosol. The inhibition of L-arginine-induced cyclic GMP formation in the cytosol by NH2OH was not reversed by the addition of superoxide dismutase. These data strongly suggest that NH2OH is not a putative intermediate in the metabolism of L-arginine to an activator of guanylate cyclase. PMID:1671745

Effect-directed analysis to explore the polar bear exposome: identification of thyroid hormone disrupting compounds in plasma.

Science.gov (United States)

Simon, Eszter; van Velzen, Martin; Brandsma, Sicco H; Lie, Elisabeth; Løken, Katharina; de Boer, Jacob; Bytingsvik, Jenny; Jenssen, Bjørn M; Aars, Jon; Hamers, Timo; Lamoree, Marja H

2013-08-06

Compounds with transthyretin (TTR)-binding potency in the blood plasma of polar bear cubs were identified with effect-directed analysis (EDA). This approach contributes to the understanding of the thyroid disrupting exposome of polar bears. The selection of these samples for in-depth EDA was based on the difference between the observed TTR-binding potency on the one hand and the calculated potency (based on known concentrations of TTR-binding compounds and their relative potencies) on the other. A library-based identification was applied to the liquid chromatography-time-of-flight-mass spectrometry (LC-ToF-MS) data by screening for matches between compound lists and the LC-ToF-MS data regarding accurate mass and isotope pattern. Then, isotope cluster analysis (ICA) was applied to the LC-ToF-MS data allowing specific screening for halogen isotope patterns. The presence of linear and branched nonylphenol (NP) was observed for the first time in polar bears. Furthermore, the presence of one di- and two monohydroxylated octachlorinated biphenyls (octaCBs) was revealed in the extracts. Linear and branched NP, 4'-OH-CB201 and 4,4'-OH-CB202 could be successfully confirmed with respect to their retention time in the analytical system. In addition, branched NP, mono- and dihydroxylated-octaCBs showed TTR-binding potencies and could explain another 32 ± 2% of the total measured activities in the extracts.

Ternary Ni–Cu–OH and Ni–Co–OH electrodes for electrochemical energy storage

KAUST Repository

Alhebshi, Nuha

2015-10-01

In this project, Ni–Cu–OH and Ni–Co–OH ternary electrodes have been prepared. Different Ni:Cu and Ni:Co ratios were deposited by chemical bath deposition (CBD) at room temperature on carbon microfibers. Since Ni(OH)2 is notorious for poor cycling stability, the goal of the work was to determine if doping with Cu or Co could improve Ni(OH)2 cycling stability performance and conductivity against reaction with electrolyte. It is observed that the electrodes with Ni:Cu and Ni:Co composition ratio of 100:10 result in the optimum capacitance and cycling stability in both Ni–Cu–OH and Ni–Co–OH electrodes. This improvement in cycling stability can be attributed to the higher redox reversibility as indicated by the smaller CV redox peak separation. In addition, it is found that decreasing Cu and Co ratios, with fixed CBD time, enhances nanoflakes formation, and hence increases electrode capacitance. For the optimum composition (Ni:Co = 100:10), composites of the ternary electrodes with graphene and carbon nanofibers were also tested, with resultant improvement in potential window, equivalent series resistance, areal capacitance and cycling stability.

EXOTIC METAL MOLECULES IN OXYGEN-RICH ENVELOPES: DETECTION OF AlOH (X1Σ+) IN VY CANIS MAJORIS

International Nuclear Information System (INIS)

Tenenbaum, E. D.; Ziurys, L. M.

2010-01-01

A new interstellar molecule, AlOH, has been detected toward the envelope of VY Canis Majoris (VY CMa), an oxygen-rich red supergiant. Three rotational transitions of AlOH were observed using the facilities of the Arizona Radio Observatory (ARO). The J = 9 → 8 and J = 7 → 6 lines at 1 mm were measured with the ARO Submillimeter Telescope, while the J = 5 → 4 transition at 2 mm was observed with the ARO 12 m antenna on Kitt Peak. The AlOH spectra exhibit quite narrow line widths of 16-23 km s -1 , as found for NaCl in this source, indicating that the emission arises from within the dust acceleration zone of the central circumstellar outflow. From a radiative transfer analysis, the abundance of AlOH relative to H 2 was found to be ∼1 x 10 -7 for a source size of 0.26'' or 22 R * . In contrast, AlCl was not detected with f ≤ 5 x 10 -8 . AlOH is likely formed just beyond the photosphere via thermodynamic equilibrium chemistry and then disappears due to dust condensation. The AlOH/AlO abundance ratio found in VY CMa is ∼17. Therefore, AlOH appears to be the dominant gas-phase molecular carrier of aluminum in this oxygen-rich shell. Local thermodynamic equilibrium calculations predict that the monohydroxides should be the major carriers of Al, Ca, and Mg in O-rich envelopes, as opposed to the oxides or halides. The apparent predominance of aluminum-bearing molecules in VY CMa may reflect proton addition processes in H-shell burning.

Trichinella nativa in a black bear from Plymouth, New Hampshire.

Science.gov (United States)

Hill, D E; Gamble, H R; Zarlenga, D S; Coss, C; Finnigan, J

2005-09-05

A suspected case of trichinellosis was identified in a single patient by the New Hampshire Public Health Laboratories in Concord, NH. The patient was thought to have become infected by consumption of muscle larvae (ML) in undercooked meat from a black bear killed in Plymouth, NH in October 2003 and stored frozen at -20 degrees C fro 4 months. In January 2004, a 600 g sample of the meat was thawed at 4 degrees C, digested in hydrochloric acid and pepsin, and larvae were collected by sedimentation. Intact, coiled, and motile ML were recovered (366 larvae per gram (l pg) of tissue), which were passed into mice and pigs. Multiplex PCR revealed a single 127 bp amplicon, indicative of Trichinella nativa. The Reproductive Capacity Index (RCI) for the T. nativa-Plymouth isolate in mice was 24.3. Worm burdens in the diaphragms of two 3-month-old pigs given 2,500 ML were 0.05 and 0.2l pg by 35 days post-inoculation, while 2.2 and 0.75 l pg were recovered from two 3-month-old pigs given 10,000 ML; no larvae were recovered from four 1-year-old pigs given 2,500 ML (n=2) or 10,000 ML (n=2). Viable larvae were also recovered from frozen black bear meat harvested at two additional locations, one in southern Ontario, Canada, and one in upstate New York, USA. Multiplex PCR using genomic DNA from these parasite samples demonstrated that both isolates were T. nativa. This is the first report of the freeze-resistant species, T. nativa, within the continental United States.

Facile Synthesis of Potassium Poly(heptazine imide) (PHIK)/Ti-Based Metal-Organic Framework (MIL-125-NH2) Composites for Photocatalytic Applications.

Science.gov (United States)

Rodríguez, Nicolás A; Savateev, Aleksandr; Grela, María A; Dontsova, Dariya

2017-07-12

Photocatalytically active composites comprising potassium poly(heptazine imide) (PHIK) and a Ti-based metal-organic framework (MOF, MIL-125-NH 2 ) are prepared in situ by simply dispersing both materials in water. The driving forces of composite formation are the electrostatic interactions between the solids and the diffusion of potassium ions from PHIK to MIL-125-NH 2 . This mechanism implies that other composites of poly(heptazine imide) salts and different MOFs bearing positive surface charge can potentially be obtained in a similar fashion. The suggested strategy thus opens a new avenue for the facile synthesis of such materials. The composites are shown to have a superior photocatalytic activity in Rhodamine B degradation under blue light irradiation. The reaction rate is doubled compared to that of pure MOF compound and is 7 times higher than the activity of the pristine PHIK. The results of the electron paramagnetic resonance (EPR) investigations and the analysis of the electronic structures of the solids suggest the electron transfer from MIL-125-NH 2 to PHIK in the composite. The possible pathways for the dye degradation and the rationalization of the increased activity of the composites are elaborated.

Ring opening of azetidine cycle: First examples of 1-azetidinepropanamine molecules as a template in hybrid organic-inorganic compounds

Science.gov (United States)

Gurzhiy, Vladislav V.; Tyumentseva, Olga S.; Britvin, Sergey N.; Krivovichev, Sergey V.; Tananaev, Ivan G.

2018-01-01

Three novel uranyl selenate and sulfate oxysalts templated by protonated azetidine molecules, [AzH]+, and its ring-opened counterpart 1-azetidinepropanamine, [AzH(CH2)3NH3]2+, have been prepared and studied by X-ray structural analysis. Conformations of azetidinium cations were analysed by means of infrared vibrational assignments supported by the DFT calculations. Crystallization of [AzH]2 [(UO2)2(SeO4)3(H2O)] (I) from highly acidic solutions suggests that low pH does not necessarily result in the opening of azetidine ring. [AzH(CH2)3NH3][(UO2)2(SeO4)3(H2O)](H2O) (II) and [AzH(CH2)3NH3](H5O2)[(UO2)2(SO4)3(HSO4)] (III) are the first structurally characterized crystalline compounds bearing isolated ring-opened azetidine moiety.

Ultrasonic irradiation-promoted one-pot synthesis of CH3NH3PbBr3 quantum dots without using flammable CH3NH2 precursor

Science.gov (United States)

Jiang, Han; Wang, Chunlei; Lv, Changgui; Xu, Shuhong; Zhu, Li; Zhang, Ruohu; Cui, Yiping

2017-02-01

At present, the CH3NH3PbBr3 quantum dots (QDs) reported in the literature usually contain two synthesis steps: the initial preparation of CH3NH3Br via the reaction of flammable CH3NH2 and HBr, together with the subsequent formation of CH3NH3PbBr3 QDs. To avoid the use of dangerous CH3NH2, this work develops a novel one-pot method for synthesizing CH3NH3PbBr3 QDs using safe and commercially available reactants (CH3NH3Cl, KBr and PbCl2). It is found that ultrasonic treatment plays a key role during the synthesis of CH3NH3PbBr3 QDs. Without ultrasonic irradiation, it is not possible to synthesize CH3NH3PbBr3 QDs under heating or vigorous stirring. Aliquots of samples taken at different ultrasonic irradiation time intervals show a time-dependent redshift in the emission wavelength. This suggests the formation of CH3NH3PbCl3 QDs first, followed by the formation of CH3NH3PbBr3 QDs through ultrasonically promoted halide exchange. Moreover, mixed CH3NH3PbCl x Br3-x QDs with a tunable emission wavelength can also be prepared through this one-pot method by controlling the ultrasonic irradiation time. In comparison to the previous two-step method, the current one-pot method is simpler, less time-consuming and does not use flammable CH3NH2. The as-prepared CH3NH3PbBr3 QDs show a comparable photoluminescence (PL) quantum yield (QY) to that of the literature. What is more, the ultrasonic time-controlled emission wavelength of CH3NH3PbCl x Br3-x QDs also provides an alternative way of tuning QD emission to the traditional way of controlling the halide ratios.

Layered Ni(OH)2-Co(OH)2 films prepared by electrodeposition as charge storage electrodes for hybrid supercapacitors.

Science.gov (United States)

Nguyen, Tuyen; Boudard, Michel; Carmezim, M João; Montemor, M Fátima

2017-01-04

Consecutive layers of Ni(OH) 2 and Co(OH) 2 were electrodeposited on stainless steel current collectors for preparing charge storage electrodes of high specific capacity with potential application in hybrid supercapacitors. Different electrodes were prepared consisting on films of Ni(OH) 2 , Co(OH) 2 , Ni 1/2 Co 1/2 (OH) 2 and layered films of Ni(OH) 2 on Co(OH) 2 and Co(OH) 2 on Ni(OH) 2 to highlight the advantages of the new architecture. The microscopy studies revealed the formation of nanosheets in the Co(OH) 2 films and of particles agglomerates in the Ni(OH) 2 films. Important morphological changes were observed in the double hydroxides films and layered films. Film growth by electrodeposition was governed by instantaneous nucleation mechanism. The new architecture composed of Ni(OH) 2 on Co(OH) 2 displayed a redox response characterized by the presence of two peaks in the cyclic voltammograms, arising from redox reactions of the metallic species present in the layered film. These electrodes revealed a specific capacity of 762 C g -1 at the specific current of 1 A g -1 . The hybrid cell using Ni(OH) 2 on Co(OH) 2 as positive electrode and carbon nanofoam paper as negative electrode display specific energies of 101.3 W h g -1 and 37.8 W h g -1 at specific powers of 0.2 W g -1 and 2.45 W g -1 , respectively.

13C, 18O, and D Fractionation Effects in the Reactions of CH3OH Isotopologues with Cl andOH Radicals

DEFF Research Database (Denmark)

Feilberg, Karen; Gruber-Stadler, Margaret; Johnson, Matthew Stanley

2008-01-01

A relative rate experiment is carried out for six isotopologues of methanol and their reactions with OH and Cl radicals. The reaction rates of CH2DOH, CHD2OH, CD3OH, 13CH3OH, and CH3 18OH with Cl and OH radicals are measured by long-path FTIR spectroscopy relative to CH3OH at 298 ( 2 K and 1013...... with measured high-resolution infrared spectra as references. The relative reaction rates defined as R ) klight/kheavy are determined to be: kOH + CH3OH/kOH + 13CH3OH ) 1.031 ( 0.020, kOH + CH3OH/kOH + CH3 18OH ) 1.017 ( 0.012, kOH + CH3OH/kOH + CH2DOH ) 1.119 ( 0.045, kOH + CH3OH/kOH + CHD2OH ) 1.326 ( 0...... reactions with CH3OH were further investigated using canonical variational transition state theory with small curvature tunneling and compared to experimental measurements as well as to those observed in CH4 and several other substituted methane species. Udgivelsesdato: 16 August 2008...

A liquid-based eutectic system: LiBH4·NH 3-nNH3BH3 with high dehydrogenation capacity at moderate temperature

KAUST Repository

Tan, Yingbin; Guo, Yanhui; Li, Shaofeng; Sun, Weiwei; Zhu, Yihan; Li, Qi; Yu, Xuebin

2011-01-01

A novel eutectic hydrogen storage system, LiBH4·NH 3-nNH3BH3, which exists in a liquid state at room temperature, was synthesized through a simple mixing of LiBH 4·NH3 and NH3BH3 (AB). In the temperature range of 90-110 °C, the eutectic system

The contribution of hydroxylamine content to spatial variability of N2O formation in soil of a Norway spruce forest

Science.gov (United States)

Liu, Shurong; Herbst, Michael; Bol, Roland; Gottselig, Nina; Pütz, Thomas; Weymann, Daniel; Wiekenkamp, Inge; Vereecken, Harry; Brüggemann, Nicolas

2016-04-01

Hydroxylamine (NH2OH), a reactive intermediate of several microbial nitrogen turnover processes, is a potential precursor of nitrous oxide (N2O) formation in the soil. However, the contribution of soil NH2OH to soil N2O emission rates in natural ecosystems is unclear. Here, we determined the spatial variability of NH2OH content and potential N2O emission rates of organic (Oh) and mineral (Ah) soil layers of a Norway spruce forest, using a recently developed analytical method for the determination of soil NH2OH content, combined with a geostatistical Kriging approach. Potential soil N2O emission rates were determined by laboratory incubations under oxic conditions, followed by gas chromatographic analysis and complemented by ancillary measurements of soil characteristics. Stepwise multiple regressions demonstrated that the potential N2O emission rates, NH2OH and nitrate (NO3-) content were spatially highly correlated, with hotspots for all three parameters observed in the headwater of a small creek flowing through the sampling area. In contrast, soil ammonium (NH4+) was only weakly correlated with potential N2O emission rates, and was excluded from the multiple regression models. While soil NH2OH content explained the potential soil N2O emission rates best for both layers, also NO3- and Mn content turned out to be significant parameters explaining N2O formation in both soil layers. The Kriging approach was improved markedly by the addition of the co-variable information of soil NH2OH and NO3- content. The results indicate that determination of soil NH2OH content could provide crucial information for the prediction of the spatial variability of soil N2O emissions.

Conditioning of dilute-acid pretreated corn stover hydrolysate liquors by treatment with lime or ammonium hydroxide to improve conversion of sugars to ethanol.

Science.gov (United States)

Jennings, Edward W; Schell, Daniel J

2011-01-01

Dilute-acid pretreatment of lignocellulosic biomass enhances the ability of enzymes to hydrolyze cellulose to glucose, but produces many toxic compounds that inhibit fermentation of sugars to ethanol. The objective of this study was to compare the effectiveness of treating hydrolysate liquor with Ca(OH)2 and NH4OH for improving ethanol yields. Corn stover was pretreated in a pilot-scale reactor and then the liquor fraction (hydrolysate) was extracted and treated with various amounts of Ca(OH)2 or NH4OH at several temperatures. Glucose and xylose in the treated liquor were fermented to ethanol using a glucose-xylose fermenting bacteria, Zymomonas mobilis 8b. Sugar losses up to 10% occurred during treatment with Ca(OH)2, but these losses were two to fourfold lower with NH4OH treatment. Ethanol yields for NH4OH-treated hydrolysate were 33% greater than those achieved in Ca(OH)2-treated hydrolysate and pH adjustment to either 6.0 or 8.5 with NH4OH prior to fermentation produced equivalent ethanol yields. Copyright © 2010 Elsevier Ltd. All rights reserved.

Ionization-induced solvent migration in acetanilide-methanol clusters inferred from isomer-selective infrared spectroscopy.

Science.gov (United States)

Weiler, Martin; Nakamura, Takashi; Sekiya, Hiroshi; Dopfer, Otto; Miyazaki, Mitsuhiko; Fujii, Masaaki

2012-12-07

We present the resonance-enhanced multiphoton ionization, infrared-ultraviolet hole burning (IR-UV HB), and IR dip spectra of the trans-acetanilide-methanol (AA-MeOH) cluster in the S(0), S(1), and cationic ground state (D(0)) in a supersonic jet. The IR-UV HB spectra demonstrate the co-existence of two isomers in S(0,1), in which MeOH binds either to the NH or the CO site of the peptide linkage in AA, denoted as AA(NH)-MeOH and AA(CO)-MeOH. When AA(CO)-MeOH is selectively ionized, its IR spectrum in D(0) is the same as that measured for AA(+) (NH)-MeOH. Thus, photoionization of AA(CO)-MeOH induces migration of MeOH from the CO to the NH site with 100% yield. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Analytic models of NH4+ uptake and regeneration experiments

International Nuclear Information System (INIS)

Laws, E.A.

1985-01-01

Differential equations describing the uptake and regeneration of NH 4 + in both laboratory and field experiments are shown to have analytic solutions which can easily be inverted to determine the rate constants of interest. The solutions are used to study the descriptive ability of two fundamentally different models of NH 4 + cycling, one in which NH 4 + regeneration is regarded as a process that transfers N from participate N to NH 4 + , the other in which regeneration is regarded as a process that introduced NH 4 + to the dissolved phase without removing N from the particulate phase. The former model was found to give a good description of experimental field data and reasonable parameter values in all cases studied. The latter model was much less successful in describing the data and in producing reasonable parameter values. It is concluded that transfer of nitrogen from particulate N to NH 4 + is a process which must be taken into account in analyzing NH 4 + uptake and regeneration experiments

Comparative genomic and physiological analysis of nutrient response to NH4+, NH4+:NO3- and NO3- in barley seedlings.

Science.gov (United States)

Lopes, Marta S; Araus, José L

2008-09-01

Long-term differences in photosynthesis, respiration and growth of plants receiving distinct nitrogen (N) sources imply that N metabolism generates signals that regulate metabolism and development. The molecular basis of these signals remains unclear. Here we studied the gene expression profiles of barley (Hordeum vulgare L. cv. Graphic) seedlings fertilized either with ammonium (NH4+), with ammonium and nitrate (NH4+:NO3-), or with nitrate (NO3-) only. Our transcriptome analysis after 48 h of growth in these N sources showed major changes in the expression of genes involved in N metabolism (nitrate reductase), signalling (protein kinases and protein phosphatases), photosynthesis (chlorophyll a/b-binding protein and a PsbQ domain), where increases in NO3- as compared with NH4+ were observed. Moreover, NH4+ assimilation induced genes participating in C and sugars metabolism (phosphoglycerate kinase, glucosyltranferase and galactokinase), respiration (cytochrome c oxidase), protein fate (heat shock proteins) and development (MTN3-like protein). These changes in gene expression could well explain the long-term growth depression observed in NH4+ plants. Even if a few genes participating in protein fate (proteases) and development (OsNAC5) were upregulated in NH4+ as compared with NH4+:NO3-, the general pattern of expression was quite similar between these two N sources. Taken together, these results indicated that other downstream mechanisms should be involved in the synergetic long-term response of NH4+:NO3-.

A liquid-based eutectic system: LiBH4·NH 3-nNH3BH3 with high dehydrogenation capacity at moderate temperature

KAUST Repository

Tan, Yingbin

2011-01-01

A novel eutectic hydrogen storage system, LiBH4·NH 3-nNH3BH3, which exists in a liquid state at room temperature, was synthesized through a simple mixing of LiBH 4·NH3 and NH3BH3 (AB). In the temperature range of 90-110 °C, the eutectic system showed significantly improved dehydrogenation properties compared to the neat AB and LiBH 4·NH3 alone. For example, in the case of the LiBH4·NH3/AB with a mole ratio of 1:3, over 8 wt.% hydrogen could be released at 90 °C within 4 h, while only 5 wt.% hydrogen released from the neat AB at the same conditions. Through a series of experiments it has been demonstrated that the hydrogen release of the new system is resulted from an interaction of AB and the NH3 group in the LiBH4·NH3, in which LiBH4 works as a carrier of ammonia and plays a crucial role in promoting the interaction between the NH3 group and AB. The enhanced dehydrogenation of LiBH 4·NH3/AB may result from the polar liquid state reaction environments and the initially promoted formation of the diammoniate of diborane, which will facilitate the B-H⋯H-N interaction between LiBH4·NH3 and AB. Kinetics analysis revealed that the rate-controlling steps of the dehydrogenation process are three-dimensional diffusion of hydrogen at temperatures ranging from 90 to 110 °C. This journal is © The Royal Society of Chemistry.

Biochar produced from oak sawdust by Lanthanum (La)-involved pyrolysis for adsorption of ammonium (NH4(+)), nitrate (NO3(-)), and phosphate (PO4(3-)).

Science.gov (United States)

Wang, Zhanghong; Guo, Haiyan; Shen, Fei; Yang, Gang; Zhang, Yanzong; Zeng, Yongmei; Wang, Lilin; Xiao, Hong; Deng, Shihuai

2015-01-01

A series of biochars were prepared by pyrolyzing oak sawdust with/without LaCl3 involvement at temperature of 300-600 °C, and approximate and ultimate analyses were carried out to check their basic characteristics. Meanwhile, the releases of readily soluble NH4(+), NO3(-) and PO4(3-) from biochars and the adsorption of NH4(+), NO3(-) and PO4(3-) by biochars were investigated. Results indicated that the involvement of LaCl3 in pyrolysis could advance the temperature of maximum mass loss by 10 °C compared with oak sawdust (CK), and potentially promoted biochar yield. Overall, the releases of readily soluble NH4(+), NO3(-) and PO4(3-) from biochars were negatively related to pyrolysis temperature, and the releases were greatly weakened by La-biochars. Additionally, the adsorption to NH4(+) can be promoted by the biochars produced at low temperature. On the contrary, the NO3(-) adsorption can be improved by increasing pyrolysis temperature. The highest PO4(3-) adsorption was achieved by the biochars produced at 500 °C. According to the results of adsorption isotherms, the maximum adsorption capacity of NH4(+), NO3(-) and PO4(3-) can be significantly promoted by 1.9, 11.2, and 4.5 folds using La-biochars. Based on the observations of FT-IR, SEM-EDS, and surface functional groups, the improvement of NH4(+) adsorption was potentially associated with the existing acidic function groups (phenolic-OH and carboxyl C=O). The increased basic functional groups on La-biochars were beneficial to improve NO3(-) and PO4(3-) adsorption. Besides, PO4(3-) adsorption was also potentially related to the formed La2O3. Copyright © 2014 Elsevier Ltd. All rights reserved.

Mixed adenine/guanine quartets with three trans-a2 Pt(II) (a=NH(3) or MeNH(2)) cross-links: linkage and rotational isomerism, base pairing, and loss of NH(3).

Science.gov (United States)

Albertí, Francisca M; Rodríguez-Santiago, Luis; Sodupe, Mariona; Mirats, Andrea; Kaitsiotou, Helena; Sanz Miguel, Pablo J; Lippert, Bernhard

2014-03-17

Of the numerous ways in which two adenine and two guanines (N9 positions blocked in each) can be cross-linked by three linear metal moieties such as trans-a2 Pt(II) (with a=NH3 or MeNH2 ) to produce open metalated purine quartets with exclusive metal coordination through N1 and N7 sites, one linkage isomer was studied in detail. The isomer trans,trans,trans-[{Pt(NH3 )2 (N7-9-EtA-N1)2 }{Pt(MeNH2 )2 (N7-9-MeGH)}2 ][(ClO4 )6 ]⋅3H2 O (1) (with 9-EtA=9-ethyladenine and 9-MeGH=9-methylguanine) was crystallized from water and found to adopt a flat Z-shape in the solid state as far as the trinuclear cation is concerned. In the presence of excess 9-MeGH, a meander-like construct, trans,trans,trans-[{Pt(NH3 )2 (N7-9-EtA-N1)2 }{Pt(MeNH2 )2 (N7-9-MeGH)2 }][(ClO4 )6 ]⋅[(9-MeGH)2 ]⋅7 H2 O (2) is formed, in which the two extra 9-MeGH nucleobases are hydrogen bonded to the two terminal platinated guanine ligands of 1. Compound 1, and likewise the analogous complex 1 a (with NH3 ligands only), undergo loss of an ammonia ligand and formation of NH4 (+) when dissolved in [D6 ]DMSO. From the analogy between the behavior of 1 and 1 a it is concluded that a NH3 ligand from the central Pt atom is lost. Addition of 1-methylcytosine (1-MeC) to such a DMSO solution reveals coordination of 1-MeC to the central Pt. In an analogous manner, 9-MeGH can coordinate to the central Pt in [D6 ]DMSO. It is proposed that the proton responsible for formation of NH4 (+) is from one of the exocyclic amino groups of the two adenine bases, and furthermore, that this process is accompanied by a conformational change of the cation from Z-form to U-form. DFT calculations confirm the proposed mechanism and shed light on possible pathways of this process. Calculations show that rotational isomerism is not kinetically hindered and that it would preferably occur previous to the displacement of NH3 by DMSO. This displacement is the most energetically costly step, but it is compensated by the proton

NMR Spectroscopic Characterization of Methylcobalt(III) Compounds with Classical Ligands. Crystal Structures of [Co(NH(3))(5)(CH(3))]S(2)O(6), trans-[Co(en)(2)(NH(3))(CH(3))]S(2)O(6) (en = 1,2-Ethanediamine), and [Co(NH(3))(6)]-mer,trans-[Co(NO(2))(3)(NH(

DEFF Research Database (Denmark)

Kofod, Pauli; Harris, Pernille; Larsen, Sine

1997-01-01

magnetic resonance spectroscopy and by absorption spectroscopy. Single-crystal X-ray structure determinations at 122.0(5) K were performed on [Co(NH(3))(5)(CH(3))]S(2)O(6) (1), trans-[Co(en)(2)(NH(3))(CH(3))]S(2)O(6) (2), and [Co(NH(3))(6)]-mer,trans-[Co(NO(2))(3)(NH(3))(2)(CH(3))](2)-trans-[Co(NO(2...

Lithium amide (LiNH2) under pressure.

Science.gov (United States)

Prasad, Dasari L V K; Ashcroft, N W; Hoffmann, Roald

2012-10-11

Static high pressure lithium amide (LiNH(2)) crystal structures are predicted using evolutionary structure search methodologies and intuitive approaches. In the process, we explore the relationship of the structure and properties of solid LiNH(2) to its molecular monomer and dimer, as well as its valence-isoelectronic crystalline phases of methane, water, and ammonia all under pressure. A NaNH(2) (Fddd) structure type is found to be competitive for the ground state of LiNH(2) above 6 GPa with the P = 1 atm I4[overline] phase. Three novel phases emerge at 11 (P4[overline]2(1)m), 13 (P4(2)/ncm), and 46 GPa (P2(1)2(1)2(1)), still containing molecular amide anions, which begin to form N-H···N hydrogen bonds. The P2(1)2(1)2(1) phase remains stable over a wide pressure range. This phase and another Pmc2(1) structure found at 280 GPa have infinite ···(H)N···H···N(H)···H polymeric zigzag chains comprising symmetric N···H···N hydrogen bonds with one NH bond kept out of the chain, an interesting general feature found in many of our high pressure (>280 GPa) LiNH(2) structures, with analogies in high pressure H(2)O-ices. All the predicted low enthalpy LiNH(2) phases are calculated to be enthalpically stable with respect to their elements but resist metallization with increasing pressure up to several TPa. The possibility of Li sublattice melting in the intermediate pressure range structures is raised.

Order-disorder phase transition in the peroxidovanadium complex NH4[VO(O2)2(NH3)].

Science.gov (United States)

Schwendt, Peter; Gyepes, Róbert; Chrappová, Jana; Němec, Ivan; Vaněk, Přemysl

2018-07-05

Complex NH 4 [VO(O 2 ) 2 (NH 3 )] (1) undergoes an order-disorder phase transition at T c ~258K. This transition is accompanied by change in the space group of the orthorhombic lattice and also by significant structural rearrangements of the constituent molecules, which are pertinent mostly to their NH 4 + ions and their ammonia ligands. The low-temperature solid state IR and Raman spectra of 1 were corroborated by solid-state computations that employed Gaussian functions as the basis set. Results of these computations yielded excellent agreement with experimental data. On the curves of temperature dependence of vibrational modes, the phase transition is expressed by an abrupt change of the slope above T c . Copyright © 2018 Elsevier B.V. All rights reserved.

Obesity hypoventilation syndrome (OHS)

Science.gov (United States)

... this page: //medlineplus.gov/ency/article/000085.htm Obesity hypoventilation syndrome (OHS) To use the sharing features on this page, please enable JavaScript. Obesity hypoventilation syndrome (OHS) is a condition in some ...

Formulation of an inhibitor radiopharmaceutical of prostatic antigen of {sup 177}Lu-Glu-Nh-CO-Nh-Lys membrane; Formulacion de un radiofarmaco inhibidor del antigeno prostatico de membrana {sup 177}Lu-Glu-NH-CO-NH-Lys

Energy Technology Data Exchange (ETDEWEB)

Ortega S, D.

2015-07-01

The prostate specific membrane antigen (PSMA) is a zinc metalloenzyme that is expressed on the cell membrane and highly expressed in prostate cancer. Recently, it has been demonstrated that the peptide sequence Glu-Nh-CO-Nh-Lys inhibit PSMA activity through an electrostatic interaction with the Zn. Several theragnostic radiopharmaceuticals with base in {sup 177}Lu have been developed for radiotherapy of specific molecular targets because gamma and beta emissions of the radionuclide (β = 0.498 MeV and γ= 0.133 MeV). However, there is currently no label a formulation for preparing a radiopharmaceutical of {sup 177}Lu-Glu-Nh-CO-Nh-Lys useful treatment of prostate cancer. The aim of this research was to optimize and document the process of production of the radiopharmaceutical {sup 177}Lu-Glu-Nh-CO-Nh-Lys for sanitary registration application before the Comision Federal para la Proteccion contra Riesgos Sanitarios (COFEPRIS). The optimization of the production process was assessed a factorial design of three variables with mixed levels (3 x 3 x 2) where the dependent variable is the radiochemical purity, the analytical method was validated by UV-Vis spectrophotometry. Next, process validation was carried out by labeling 3 lots of the optimized formulation of the radiopharmaceutical (5.55 GBq (2.16 μg) of {sup 177}LuCl{sub 3}, 90 mg peptide PSMA, 50 mg ascorbic acid and 150 μL of acetate buffer 1 M ph 5), long-term stability was performed by high resolution liquid chromatography) to determine its useful shelf life. 3 validation batches were prepared under protocols of Good Manufacturing Practice (GMP) in the Production Plant of Radiopharmaceuticals of the Instituto Nacional de Investigaciones Nucleares (ININ), meet specifications preset by obtaining a sterile and free development of bacterial endotoxin yields of labeled 100% and which retains its quality characteristics radiochemical purity greater than 90% for at least 15 days. (Author)

OH, HO2 and RO2 Radical and OH Reactivity Observations during the Summertime in Beijing: High In-Situ Ozone Production and Evidence of a Missing OH Source.

Science.gov (United States)

Whalley, L.; Ye, C.; Slater, E.; Woodward-Massey, R.; Lee, J. D.; Squires, F. A.; Hopkins, J. R.; Dunmore, R.; Shaw, M.; Hamilton, J.; Lewis, A. C.; Crilley, L.; Kramer, L. J.; Bloss, W.; Heard, D. E.

2017-12-01

Despite substantial reductions in primary emissions of pollutants in China over the past decade, concentrations of the secondary pollutant, ozone, still frequently exceed air quality threshold limits in urban areas during the summertime. We will present measurements of OH, HO2 and RO2 radicals and OH reactivity made in central Beijing at the Institute of Atmospheric Physics of the Chinese Academy of Sciences, close to the North 4th ring road in May and June 2017 which formed the summer phase of `An Integrated Study of AIR Pollution PROcesses'. Elevated levels of O3 (>100 ppbv) were regularly observed. NO concentrations were elevated during the morning but often decreased to below the instrument limit of detection during the afternoon hours when the ozone concentrations peaked. Biogenic emissions influenced the chemistry at the site, with several ppbv of isoprene measured during the afternoons. The OH measurements were made using the FAGE technique, equipped with an inlet pre injector (IPI) which provides an alternative method to determine the instrument background signal by injecting a scavenger to remove ambient OH and ensures an artefact-free OH measurement. Elevated levels of OH were observed, with a mean peak OH concentration of 1.2×107 molecule cm-3 at noon; but with OH concentrations reaching up to 2.5×107 molecule cm-3 on some days. Mean peak HO2 concentrations of 3×108 molecule cm-3 and total RO2 of 1.2×109 molecule cm-3 were recorded, with maximum concentrations of 1.0×109 molecule cm-3 and 4×109 molecule cm-3 observed for HO2 and RO2 respectively, suggesting significant in situ ozone production. A comparison of the artefact-free OH observations with steady state calculations, constrained to the total OH reactivity measurement and known OH precursors that were measured alongside OH, highlights a significant missing daytime OH source under low [NO], with the steady state OH concentrations approximately a factor of two lower than the OH concentrations

Bearing system

Science.gov (United States)

Kapich, Davorin D.

1987-01-01

A bearing system includes backup bearings for supporting a rotating shaft upon failure of primary bearings. In the preferred embodiment, the backup bearings are rolling element bearings having their rolling elements disposed out of contact with their associated respective inner races during normal functioning of the primary bearings. Displacement detection sensors are provided for detecting displacement of the shaft upon failure of the primary bearings. Upon detection of the failure of the primary bearings, the rolling elements and inner races of the backup bearings are brought into mutual contact by axial displacement of the shaft.

Reaction of atomic bromine with acetylene and loss rate of atmospheric acetylene due to reaction with OH, Cl, O, and Br

Science.gov (United States)

Payne, W. A.; Nava, D. F.; Brunning, J.; Stief, L. J.

1986-01-01

The first-order, diffusion, and bimolecular rate constants for the reaction Br + C2H2 yields C2H3Br are evaluated. The rate constants are measured at 210, 248, 298, and 393 K and at pressures between 15-100 torr Ar using flash photolysis combined with time-resolved detection of atomic bromine via Br resonance radiation. It is observed that the reaction is not affected by pressure or temperature and the bimolecular constant = (4.0 + or - 0.8) x 10 to the -15th cu cm/sec with an error of two standard deviations. The C2H2 + Br reaction rates are compared with reactions of C2H2 with Cl, OH, NH2, and H. The loss rates for atmospheric C2H2 for reactions with OH, Cl, O, and Br are calculated as a function of altitude.

NH2+ implantations induced superior hemocompatibility of carbon nanotubes.

Science.gov (United States)

Guo, Meixian; Li, Dejun; Zhao, Mengli; Zhang, Yiteng; Deng, Xiangyun; Geng, Dongsheng; Li, Ruying; Sun, Xueliang; Gu, Hanqing; Wan, Rongxin

2013-05-01

NH2+ implantation was performed on multiwalled carbon nanotubes (MWCNTs) prepared by chemical vapor deposition. The hemocompatibility of MWCNTs and NH2+-implanted MWCNTs was evaluated based on in vitro hemolysis, platelet adhesion, and kinetic-clotting tests. Compared with MWCNTs, NH2+-implanted MWCNTs displayed more perfect platelets and red blood cells in morphology, lower platelet adhesion rate, lower hemolytic rate, and longer kinetic blood-clotting time. NH2+-implanted MWCNTs with higher fluency of 1 × 1016 ions/cm2 led to the best thromboresistance, hence desired hemocompatibility. Fourier transfer infrared and X-ray photoelectron spectroscopy analyses showed that NH2+ implantation caused the cleavage of some pendants and the formation of some new N-containing functional groups. These results were responsible for the enhanced hemocompatibility of NH2+-implanted MWCNTs.

Exotic Metal Molecules in Oxygen-rich Envelopes: Detection of AlOH (X1Σ+) in VY Canis Majoris

Science.gov (United States)

Tenenbaum, E. D.; Ziurys, L. M.

2010-03-01

A new interstellar molecule, AlOH, has been detected toward the envelope of VY Canis Majoris (VY CMa), an oxygen-rich red supergiant. Three rotational transitions of AlOH were observed using the facilities of the Arizona Radio Observatory (ARO). The J = 9 → 8 and J = 7 → 6 lines at 1 mm were measured with the ARO Submillimeter Telescope, while the J = 5 → 4 transition at 2 mm was observed with the ARO 12 m antenna on Kitt Peak. The AlOH spectra exhibit quite narrow line widths of 16-23 km s-1, as found for NaCl in this source, indicating that the emission arises from within the dust acceleration zone of the central circumstellar outflow. From a radiative transfer analysis, the abundance of AlOH relative to H2 was found to be ~1 × 10-7 for a source size of 0.26'' or 22 R* . In contrast, AlCl was not detected with f VY CMa is ~17. Therefore, AlOH appears to be the dominant gas-phase molecular carrier of aluminum in this oxygen-rich shell. Local thermodynamic equilibrium calculations predict that the monohydroxides should be the major carriers of Al, Ca, and Mg in O-rich envelopes, as opposed to the oxides or halides. The apparent predominance of aluminum-bearing molecules in VY CMa may reflect proton addition processes in H-shell burning.

Crystal structure and characterization of the novel NH{sup +} Midline-Horizontal-Ellipsis N hydrogen bonded polar crystal [NH{sub 2}(CH{sub 2}){sub 4}NH][BF{sub 4}

Energy Technology Data Exchange (ETDEWEB)

Wojtas, M., E-mail: maciej.wojtas@chem.uni.wroc.pl [Faculty of Chemistry, University of Wroclaw, Joliot-Curie 14, 50-383 Wroclaw (Poland); Gagor, A. [W. Trzebiatowski Institute of Low Temperature and Structure Research, Polish Academy of Science, PO Box 1410, 50-950 Wroclaw (Poland); Czupinski, O. [Faculty of Chemistry, University of Wroclaw, Joliot-Curie 14, 50-383 Wroclaw (Poland); Medycki, W. [Institute of Molecular Physics, Polish Academy of Science, Smoluchowskiego 17, 60-179 Poznan (Poland); Jakubas, R. [Faculty of Chemistry, University of Wroclaw, Joliot-Curie 14, 50-383 Wroclaw (Poland)

2012-03-15

Dielectric properties and phase transitions of the piperazinium tetrafluoroborate ([NH{sub 2}(CH{sub 2}){sub 4}NH][BF{sub 4}], abbreviated as PFB) crystal are related to the one-dimensional arrangement of the cations linked by the bistable NH{sup +} Midline-Horizontal-Ellipsis N hydrogen bonds and molecular motions of the [BF{sub 4}]{sup -} units. The crystal structure of [NH{sub 2}(CH{sub 2}){sub 4}NH][BF{sub 4}] is monoclinic at room temperature with the polar space group Pn. The polar/acentric properties of the room temperature phase IV have been confirmed by the piezoelectric and pyroelectric measurements. DSC measurements show that the compound undergoes three first-order structural phase transitions: at 421/411 K (heating/cooling), at 386/372 K and at 364/349 K. {sup 1}H and {sup 19}F NMR measurements indicate the reorientational motions of [BF{sub 4}]{sup -} anions and piperazinium(+) cations as well as the proton motion in the hydrogen-bonded chains of piperazine along the [001] direction. Over the phase I the isotropic reorientational motions or even self-diffusion of the cations and anions are expected. The conductivity measurements in the vicinity of the II-I PT indicate a superionic phase over the phase I. - Graphical abstract: It must be emphasized that the titled compound represents the first organic-inorganic simple salt containing the single-protonated piperazinium cation which was studied by means of the wide variety of experimental techniques. A survey of Cambridge Structural Database (CSD version 5.32 (November 2010) and updates (May 2011)) for structure containing the piperazinium cations yields 248 compounds with the doubly protonated piperazinium(2+) cations and only eight compounds with the singly protonated piperazinium(+) cations. Among these structures only one is the hybrid organic-inorganic material. This is piperazinium nitrate characterized structurally. The crystal packing of [NH{sub 2}(CH{sub 2}){sub 4}NH][BF{sub 4}], phase IV. The

Nitric oxide is an obligate bacterial nitrification intermediate produced by hydroxylamine oxidoreductase.

Science.gov (United States)

Caranto, Jonathan D; Lancaster, Kyle M

2017-08-01

Ammonia (NH 3 )-oxidizing bacteria (AOB) emit substantial amounts of nitric oxide (NO) and nitrous oxide (N 2 O), both of which contribute to the harmful environmental side effects of large-scale agriculture. The currently accepted model for AOB metabolism involves NH 3 oxidation to nitrite (NO 2 - ) via a single obligate intermediate, hydroxylamine (NH 2 OH). Within this model, the multiheme enzyme hydroxylamine oxidoreductase (HAO) catalyzes the four-electron oxidation of NH 2 OH to NO 2 - We provide evidence that HAO oxidizes NH 2 OH by only three electrons to NO under both anaerobic and aerobic conditions. NO 2 - observed in HAO activity assays is a nonenzymatic product resulting from the oxidation of NO by O 2 under aerobic conditions. Our present study implies that aerobic NH 3 oxidation by AOB occurs via two obligate intermediates, NH 2 OH and NO, necessitating a mediator of the third enzymatic step.

Flotation of copper-bearing shale in solutions of inorganic salts and organic reagents

Directory of Open Access Journals (Sweden)

Ratajczak Tomasz

2017-01-01

Full Text Available Flotation data on copper-bearing shale in aqueous solutions of inorganic electrolytes (NaCl, Na2SO4, KPF6, NH4Cl and organic reagents (ethylamine, propylamine as frothers were presented and discussed. The relationships between shale flotation, surface tension of aqueous solution and foam height during bubbling with air in the flotation system were presented. It has been found that flotation of shale in the presence of inorganic salts the yield was directly proportional to the surface tension of the aqueous solution of salt and inversely proportional to the height of the foam. On the other hand, for organic reagents solutions (short chain amines, a reverse effect has been observed in relation to the inorganic compounds studied, that is the yield of copper-bearing shale flotation and the foam height were inversely proportional to the surface tension of the amine solution.

A roadmap for OH reactivity research

Science.gov (United States)

Williams, Jonathan; Brune, William

2015-04-01

A fundamental property of the atmosphere is the frequency of gas-phase reactions with the OH radical, the atmosphere's primary oxidizing agent. This reaction frequency is called the OH reactivity and is the inverse the lifetime of the OH radical itself, which varies from a few seconds in the clean upper troposphere to below 10 ms in forests and polluted city environments. Ever since the discovery of the OH radical's importance to tropospheric chemistry, the characterization of its overall loss rate (OH reactivity) has remained a key question. At first, this property was assessed by summing the reactivity contributions of individually measured compounds; however, as improving analytical technology revealed ever more reactive species in ambient air, it became clear that this approach could provide only a lower limit. Approximately 15 years ago, the direct measurement of total OH reactivity was conceived independently by two groups. The first publications demonstrated direct OH reactivity measurements in the laboratory (Calpini et al., 1999) based on LIDAR and in the ambient air (Kovacs and Brune, 2001) based on in situ laser induced fluorescence detection of OH.

Formulation of an inhibitor radiopharmaceutical of prostatic antigen of 177Lu-Glu-Nh-CO-Nh-Lys membrane

International Nuclear Information System (INIS)

Ortega S, D.

2015-01-01

The prostate specific membrane antigen (PSMA) is a zinc metalloenzyme that is expressed on the cell membrane and highly expressed in prostate cancer. Recently, it has been demonstrated that the peptide sequence Glu-Nh-CO-Nh-Lys inhibit PSMA activity through an electrostatic interaction with the Zn. Several theragnostic radiopharmaceuticals with base in 177 Lu have been developed for radiotherapy of specific molecular targets because gamma and beta emissions of the radionuclide (β = 0.498 MeV and γ= 0.133 MeV). However, there is currently no label a formulation for preparing a radiopharmaceutical of 177 Lu-Glu-Nh-CO-Nh-Lys useful treatment of prostate cancer. The aim of this research was to optimize and document the process of production of the radiopharmaceutical 177 Lu-Glu-Nh-CO-Nh-Lys for sanitary registration application before the Comision Federal para la Proteccion contra Riesgos Sanitarios (COFEPRIS). The optimization of the production process was assessed a factorial design of three variables with mixed levels (3 x 3 x 2) where the dependent variable is the radiochemical purity, the analytical method was validated by UV-Vis spectrophotometry. Next, process validation was carried out by labeling 3 lots of the optimized formulation of the radiopharmaceutical (5.55 GBq (2.16 μg) of 177 LuCl 3 , 90 mg peptide PSMA, 50 mg ascorbic acid and 150 μL of acetate buffer 1 M ph 5), long-term stability was performed by high resolution liquid chromatography) to determine its useful shelf life. 3 validation batches were prepared under protocols of Good Manufacturing Practice (GMP) in the Production Plant of Radiopharmaceuticals of the Instituto Nacional de Investigaciones Nucleares (ININ), meet specifications preset by obtaining a sterile and free development of bacterial endotoxin yields of labeled 100% and which retains its quality characteristics radiochemical purity greater than 90% for at least 15 days. (Author)

Oh No, Henrietta Got Out!

Science.gov (United States)

Lottero-Perdue, Pamela; Grabia, Kathryn; Sandifer, Cody

2017-01-01

In a kindergarten classroom, exclamations like "Oh no!" may be causes for concern. However, when the students in Mrs. Grabia's classroom shouted "Oh no!" and "Uh oh!" during an engineering-infused 5E lesson, it meant that a persistent little robot had pushed its way out of the fences they had created. It also meant…

极压润滑剂NH-EPL性能评价与现场应用%Performance Evaluation and Application of Extreme Pressure Lubricant NH-EPL

Institute of Scientific and Technical Information of China (English)

逯贵广

2017-01-01

Aiming at the problems of commonly drilling fluid lubricant,such as low pressure,poor anti-friction effect and temperature resistance, extreme pressure lubricant NH-EPL was prepared by introducing metal organic compound into alkanolamine ester. The properties of NH-EPL,such as lubrication,friction-reduction and wear-resistance effect,temperature resistance and salt tolerance,foam ability,fluorescence level and biological toxicity and so on,were studied and the effect of NH-EPL on the rheological property of drilling fluid was investigated. Furthermore,NH-EPL was applied in Xinjiang and Jiangsu area on site. The results showed that NH-EPL had excellent extreme pressure friction resistance and lubrication performance. At room temperature,the lubrication factor reduced 93.4%and the wear loss reduced 99.87%by 0.5%NH-EPL. The pressure capacity of NH-EPL was 320 kgf. NH-EPL had good resistance to temperature(160℃)and salt. The lubrication factor of 20% NaCl salt water slurry reduced 80.43% by NH-EPL. The foam ability of NH-EPL was poor and the foaming rate of base slurry containing 0.5% NH-EPL was only 1.0%. The fluorescence level of NH-EPL was one level. It had no biological toxicity which was in accordance with environmental guidelines. NH-EPL had little effect on the rheological property and filtration property of mud,and the compatibility between NH-EPL and other treatment agent was good. The field application effect of NH-EPL was remarkable in Xinjiang and Jiangsu area with drilling friction reduction rate up to 50%,which met the demand for drilling service of deep, highly-deviated and horizontal wells.%针对目前钻井液常用润滑剂承压能力低、减磨效果和抗温性能差等问题,通过在醇胺酯中引入金属有机化合物制得极压润滑剂NH-EPL.研究了NH-EPL的润滑性能、极压减磨性能、抗温耐盐性能、起泡性、荧光级别以及生物毒性等,考察了其对钻井液流变性的影响,并在新疆和江苏地区进行了现场应用.结果表明,NH

Rate-based modelling of combined SO2 removal and NH3 recycling integrated with an aqueous NH3-based CO2 capture process

International Nuclear Information System (INIS)

Li, Kangkang; Yu, Hai; Qi, Guojie; Feron, Paul; Tade, Moses; Yu, Jingwen; Wang, Shujuan

2015-01-01

Highlights: • A rigorous, rate-based model for an NH 3 –CO 2 –SO 2 –H 2 O system was developed. • Model predictions are in good agreement with pilot plant results. • >99.9% of SO 2 was captured and >99.9% of slipped ammonia was reused. • The process is highly adaptable to the variations of SO 2 /NH 3 level, temperatures. - Abstract: To reduce the costs of controlling emissions from coal-fired power stations, we propose an advanced and effective process of combined SO 2 removal and NH 3 recycling, which can be integrated with the aqueous NH 3 -based CO 2 capture process to simultaneously achieve SO 2 and CO 2 removal, NH 3 recycling and flue gas cooling in one process. A rigorous, rate-based model for an NH 3 –CO 2 –SO 2 –H 2 O system was developed and used to simulate the proposed process. The model was thermodynamically and kinetically validated by experimental results from the open literature and pilot-plant trials, respectively. Under typical flue gas conditions, the proposed process has SO 2 removal and NH 3 reuse efficiencies of >99.9%. The process is strongly adaptable to different scenarios such as high SO 2 levels in flue gas, high NH 3 levels from the CO 2 absorber and high flue gas temperatures, and has a low energy requirement. Because the process simplifies flue gas desulphurisation and resolves the problems of NH 3 loss and SO 2 removal, it could significantly reduce the cost of CO 2 and SO 2 capture by aqueous NH 3

Cation incorporation into zirconium oxide in LiOH, NaOH, and KOH solutions

International Nuclear Information System (INIS)

Jeong, Y.H.; Kim, K.H.; Baek, J.H.

1999-01-01

To investigate the cation incorporation into zirconium oxide, SIMS analysis was performed on the specimens prepared to have an equal oxide thickness in LiOH, NaOH, and KOH solutions. Even though they have an equal oxide thickness in LiOH, NaOH, and KOH solutions, the penetration depth of cation into the oxide decreased with an increase in the ionic radius of cation. The cation is considered to control the corrosion in alkali hydroxide solutions and its effect is dependent on the concentration of alkali and the oxide thickness. The slight enhancement of the corrosion rate at a low concentration is thought to be caused by cation incorporation into oxide, while the significant acceleration at a high concentration is due to the transformation of oxide microstructures that would be also induced by cation incorporation into oxide. (orig.)

Synthesis and preliminary biodistribution studies of [131I]SIB-PEG4-CHC in tumor-bearing mice

International Nuclear Information System (INIS)

Xiaobei Zheng; Jing Yang; Xiaojiang Duan; Tingting Niu; Wangsuo Wu; Jianjun Wang; Feng Dong

2011-01-01

This work reports the synthesis and preliminary biodistribution results of [ 131 I]SIB-PEG 4 -CHC in tumor-bearing mice. The tributylstannyl precursor ATE-PEG 4 -CHC was synthesized by conjugation of ATE to amino pegylated colchicine NH 2 -PEG 4 -CHC. [ 131 I]SIB-PEG 4 -CHC was radiosynthesized by electrophilic destannylation of the precursor with a yield of ∼44%. The radiochemical purity (RCP) appeared to be >95% by a Sep-Pak cartridge purification. [ 131 I]SIB-PEG 4 -CHC was lipophilic and was stable at room temperature. Biodistribution studies in tumor-bearing mice showed that [ 131 I]SIB-PEG 4 -CHC cleared from background rapidly, and didn't deiodinate in vivo. However, the poor tumor localization excluded it from further investigations as a tumor-targeted radiopharmaceuticals. (author)

Room temperature synthesis of Si-MCM-41 using polymeric version of ethyl silicate as a source of silica

International Nuclear Information System (INIS)

Gaydhankar, T.R.; Samuel, V.; Jha, R.K.; Kumar, R.; Joshi, P.N.

2007-01-01

Synthesis of mesoporous MCM-41 materials at room temperature using less expensive polymeric version of ethyl silicate (40 wt% SiO 2 ) as a source of silica was established. The influence of crucial synthesis parameters such as molar ratios of H 2 O/NH 4 OH, NH 4 OH/SiO 2 and CTMABr/SiO 2 in gel on the quality of the phase formed was investigated. Powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and low temperature N 2 adsorption-desorption isotherms have been employed to characterize the products. The magnitude of orderness, textural properties and thermal stability of the Si-MCM-41 samples prepared under identical judiciously pre-controlled synthesis conditions using ethyl silicate and conventional tetraethyl orthosilicate (TEOS) were assessed. Even though, ethyl silicate has proved to be suitable source for the preparation of MCM-41 at room temperature, there exists an optimum value of H 2 O/NH 4 OH for different NH 4 OH/SiO 2 molar ratios in the gel. Changes in the morphology were observed when NH 4 OH/SiO 2 , H 2 O/NH 4 OH molar ratios in the gels were changed

Removal of oil palm trunk lignin in ammonium hydroxide pretreatment

Science.gov (United States)

Az-Zahraa, Balqis; Zakaria, Sarani; Daud, Muhammad F. B.; Jaafar, Sharifah Nabihah Syed

2018-04-01

Alkaline pretreatment using ammonium hydroxide, NH4OH serves as one of a process to remove lignin from lignocellulosic biomass such as oil palm trunk fiber. In this study, the effect of NH4OH pretreatment on removal of oil palm trunk lignin was investigated. The oil palm trunk fiber was dissolved in NH4OH with different concentrations (6, 8 and 10 %), different duration (3, 5 and 7 h) and temperatures (60, 80 and 100 °C). The samples were analyzed by using UV-Vis to estimate the concentration of extracted lignin. The result indicates that the optimum conditions to gain maximum extracted lignin were 8% NH4OH, 100 °C and 5 h with concentration of 64 mgL-1 while the lowest was at 6% NH4OH, 100 °C and 5 h with concentration of 62.5 mgL-1.

Journal bearing

Science.gov (United States)

Menke, John R.; Boeker, Gilbert F.

1976-05-11

1. An improved journal bearing comprising in combination a non-rotatable cylindrical bearing member having a first bearing surface, a rotatable cylindrical bearing member having a confronting second bearing surface having a plurality of bearing elements, a source of lubricant adjacent said bearing elements for supplying lubricant thereto, each bearing element consisting of a pair of elongated relatively shallowly depressed surfaces lying in a cylindrical surface co-axial with the non-depressed surface and diverging from one another in the direction of rotation and obliquely arranged with respect to the axis of rotation of said rotatable member to cause a flow of lubricant longitudinally along said depressed surfaces from their distal ends toward their proximal ends as said bearing members are rotated relative to one another, each depressed surface subtending a radial angle of less than 360.degree., and means for rotating said rotatable bearing member to cause the lubricant to flow across and along said depressed surfaces, the flow of lubricant being impeded by the non-depressed portions of said second bearing surface to cause an increase in the lubricant pressure.

Camshaft bearing arrangement

Energy Technology Data Exchange (ETDEWEB)

Aoi, K.; Ozawa, T.

1986-06-10

A bearing arrangement is described for the camshaft of an internal combustion engine or the like which camshaft is formed along its length in axial order with a first bearing surface, a first cam lobe, a second bearing surface, a second cam lobe, a third bearing surface, a third cam lobe and a fourth bearing surface, the improvement comprising first bearing means extending around substantially the full circumference of the first bearing surface and journaling the first bearing surface, second bearing means extending around substantially less than the circumference of the second bearing surface and journaling the second bearing surface, third bearing means extending around substantially less than the circumference of the third bearing surface and journaling the third bearing surface, and fourth bearing means extending around substantially the full circumference of the fourth bearing surface and journaling the first bearing surface.

NH AND Mg INDEX TRENDS IN ELLIPTICAL GALAXIES

International Nuclear Information System (INIS)

Serven, Jedidiah; Worthey, Guy; Toloba, Elisa; Sanchez-Blazquez, Patricia

2011-01-01

We examine the spectrum in the vicinity of the NH3360 index of Davidge and Clark, which was defined to measure the NH absorption around 3360 A and shows almost no trend with velocity dispersion, unlike other N-sensitive indices, which show a strong trend. Computing the effect of individual elements on the integrated spectrum with synthetic stellar population integrated spectra, we find that, while being well correlated with nitrogen abundance, NH3360 is almost equally well anti-correlated with Mg abundance. This prompts the definition of two new indices, Mg3334, which is mostly sensitive to magnesium, and NH3375, which is mostly sensitive to nitrogen. Rather surprisingly, we find that the new NH3375 index shows a trend versus optical absorption feature indices that is as shallow as the NH3360 index. We hypothesize that the lack of a strong index trend in these near-UV indices is due to the presence of an old metal-poor component of the galactic population. Comparison of observed index trends and those predicted by models shows that a modest fraction of an old, metal-poor stellar population could easily account for the observed flat trend in these near-UV indices while still allowing substantial N abundance increase in the larger galaxies.

Eliminating amino acid interference during spectrophotometric NH4+ analysis

NARCIS (Netherlands)

Ros, G.H.; Leeuwen, van A.G.; Temminghoff, E.J.M.

2011-01-01

Amino acids can interfere with NH4+ in spectrophotometric NH4+ determination hampering accurate quantification of the fate of NH4+ and dissolved organic N in soils. Serious interference has been reported for soils rich in organic matter, and for soils that have been fumigated, oven-dried or

Kinetics of selected elementary reactions of NH(a{sup 1}{delta}) or ND(a{sup {delta}}), NH(X{sup 3}{sigma}{sup -}) or ND(X{sup 3}{sigma}{sup -}) and NH{sub 2}(X), NHD(X), NH{sub 2}(X) radicals; Untersuchung der Kinetik ausgewaehlter Elementarreaktionen von NH(a{sup 1}{delta})- bzw. ND(a{sup 1}{delta})-, NH(X{sup 3}{sigma}{sup -})- bzw. ND(X{sup 3}{sigma}{sup -})- und NH{sub 2}(X)-, NHD(X)-, ND{sub 2}(X)-Radikalen

Energy Technology Data Exchange (ETDEWEB)

Adam, L.

2002-02-01

The elementary reactions of the NH and ND radicals in the ground state and the first excited state with H({sup 2}S) atoms and with molecules containing hydrogen and fluorine element bonds were investigated in the gaseous phase at a pressure of p = 7-80 bar. The elementary reactions of the NH{sub 2}, NHD and ND{sub 2} radicals in the ground state with hydrogen halides in the gaseous phase were investigated as well. [German] Die Elementarreaktionen des NH- bzw. ND-Radikals im Elektronengrundzustand und im ersten elektronisch angeregten Zustand mit H({sup 2}S)-Atomen und mit Molekuelen, die Wasserstoff- und Fluor-Elementbindungen besitzen, wurden in der Gasphase bei einem Druck von p = 7 - 80 mbar untersucht. Weiterhin wurden die Elementarreaktionen der NH{sub 2}-, NHD- bzw. ND{sub 2}-Radikale im Elektronengrundzustand mit Halogenwasserstoffen in der Gasphase untersucht. (orig.)

Synthesis of quinoxaline derivatives via condensation of aryl-1,2-diamines with 1,2-diketones using (NH4)6 Mo7 O24 . 4 H2 O as an efficient, mild and reusable catalyst

International Nuclear Information System (INIS)

Hasaninejad, A.; Zare, A.; Mohammadizadeh, M. R.; Karami, Z.

2009-01-01

Ammonium heptamolybdate tetrahydrate [(NH 4 ) 6 Mo 7 O 24. 4H 2 O] efficiently catalyzes the condensation of aryl-1,2-diamines with l,2-diketones in EtOH/H 2 O as a green media at room temperature to afford quinoxaline derivatives as biologically interesting compounds. Ease of recycling of the catalyst is one of the most advantages of the proposed method

Photoionization of the OH radical

International Nuclear Information System (INIS)

Dehmer, P.M.

1985-01-01

The hydroxyl radical (OH) is one of the most thoroughly studied free radicals because of its importance in atmospheric chemistry, combustion processes, and the interstellar medium. Detailed experimental and theoretical studies have been performed on the ground electronic state (X 2 PI/sub i/) and on the four lowest bound excited electronic states (A 2 Σ + , B 2 Σ + , D 2 Σ - , and C 2 Σ + ). However, because it is difficult to distinguish the spectrum of OH from the spectra of the various radical precursors, the absorption spectrum in the wavelength region below 1200 A has not been well characterized. In the present work, the spectrum of OH has been determined in the wavelength region from 750 to 950 A using the technique of photoionization mass spectrometry. This technique allows complete separation of the spectrum of OH from that of the other components of the discharge and permits the unambiguous determination of the spectrum of OH

Acid mine water neutralisation with ammonium hydroxide and ...

African Journals Online (AJOL)

2013-05-30

May 30, 2013 ... Compare the behaviour of simulated and real acid mine ... intervals and assayed for pH and NH3 concentration. NH3 gas ... Process flow-diagram of integrated NH4OH/Ba(OH)2/lime process for acid mine water treatment.

On the volatility of nihonium (Nh, Z = 113)

Energy Technology Data Exchange (ETDEWEB)

Aksenov, Nikolay V.; Steinegger, Patrick; Abdullin, Farid Sh.; Albin, Yury V.; Chepigin, Viktor I.; Lebedev, Vyacheslav Ya.; Madumarov, Alexander Sh.; Malyshev, Oleg N.; Petrushkin, Oleg V.; Polyakov, Alexander N.; Popov, Yury A.; Sabel' nikov, Alexey V.; Sagaidak, Roman N.; Shirokovsky, Igor V.; Shumeiko, Maksim V.; Starodub, Gennadii Ya.; Tsyganov, Yury S.; Utyonkov, Vladimir K.; Voinov, Alexey A.; Vostokin, Grigory K.; Yeremin, Alexander V.; Dmitriev, Sergey N. [Flerov Laboratory of Nuclear Reactions, Joint Institute for Nuclear Research, Dubna (Russian Federation); Bozhikov, Gospodin A. [Flerov Laboratory of Nuclear Reactions, Joint Institute for Nuclear Research, Dubna (Russian Federation); Institute for Advanced Physical Studies, Sofia (Bulgaria); Eichler, Robert [Laboratory of Radiochemistry, Paul Scherrer Institute, Villigen PSI (Switzerland); Departement fuer Chemie und Biochemie, Universitaet Bern, Bern (Switzerland)

2017-07-15

Gas-phase chromatography studies of nihonium (Nh, Z = 113) were carried out at the one-atom-at-a-time level. For the production of nihonium, the heavy-ion-induced nuclear fusion reaction of {sup 48}Ca with {sup 243}Am was used. This leads to isotopes {sup 284,285}Nh, as the direct descendants of the α-decaying precursors {sup 288,289}Mc. Combining the Dubna Gas-Filled Recoil Separator with gas-phase chromatographic separation, the experiment was sensitive to elemental nihonium and its adsorption behavior on Teflon, theoretically predicted by modern relativistic density functional theory. The non-observation of any decays of Nh after the chemical separation indicates a larger than expected retention of elemental Nh on a Teflon surface. (orig.)

Formation of Hydroxylamine on Dust Grains via Ammonia Oxidation

Science.gov (United States)

He, Jiao; Vidali, Gianfranco; Lemaire, Jean-Louis; Garrod, Robin T.

2015-01-01

The quest to detect prebiotic molecules in space, notably amino acids, requires an understanding of the chemistry involving nitrogen atoms. Hydroxylamine (NH2OH) is considered a precursor to the amino acid glycine. Although not yet detected, NH2OH is considered a likely target of detection with ALMA. We report on an experimental investigation of the formation of hydroxylamine on an amorphous silicate surface via the oxidation of ammonia. The experimental data are then fed into a simulation of the formation of NH2OH in dense cloud conditions. On ices at 14 K and with a modest activation energy barrier, NH2OH is found to be formed with an abundance that never falls below a factor 10 with respect to NH3. Suggestions of conditions for future observations are provided.

[UO2(NH3)5]Br2·NH3: synthesis, crystal structure, and speciation in liquid ammonia solution by first-principles molecular dynamics simulations.

Science.gov (United States)

Woidy, Patrick; Bühl, Michael; Kraus, Florian

2015-04-28

Pentaammine dioxido uranium(VI) dibromide ammonia (1/1), [UO2(NH3)5]Br2·NH3, was synthesized in the form of yellow crystals by the reaction of uranyl bromide, UO2Br2, with dry liquid ammonia. The compound crystallizes orthorhombic in space group Cmcm and is isotypic to [UO2(NH3)5]Cl2·NH3 with a = 13.2499(2), b = 10.5536(1), c = 8.9126(1) Å, V = 1246.29(3) Å(3) and Z = 4 at 123 K. The UO2(2+) cation is coordinated by five ammine ligands and the coordination polyhedron can be best described as pentagonal bipyramid. Car-Parrinello molecular dynamics simulations are reported for [UO2(NH3)5](2+) in the gas phase and in liquid NH3 solution (using the BLYP density functional). According to free-energy simulations, solvation by ammonia has only a small effect on the uranyl-NH3 bond strength.

Determination of the hydrogen positions in the novel barium boroarsenate Ba[B{sub 2}As{sub 2}O{sub 8}(OH){sub 2}] by combined single crystal X-ray and powder neutron investigations

Energy Technology Data Exchange (ETDEWEB)

Lieb, Alexandra [School of Chemistry, University of Southampton (United Kingdom); Fakultaet fuer Verfahrens- und Systemtechnik, Lehrstuhl fuer Technische Chemie, Otto-von-Guericke-Universitaet, Magdeburg (Germany); Weller, Mark T. [School of Chemistry, University of Southampton (United Kingdom); Department of Chemistry, University of Bath (United Kingdom)

2017-11-17

The boroarsenate Ba[B{sub 2}As{sub 2}O{sub 8}(OH){sub 2}] was obtained by the reaction of NH{sub 4}H{sub 2}AsO{sub 4}, B(OH){sub 3} and BaBr{sub 2}.2H{sub 2}O in the melt. Ba[B{sub 2}As{sub 2}O{sub 8}(OH){sub 2}] was obtained as thin colorless needles, together with spherical crystals of BAsO{sub 4} as by-product, grown on a pellet of Ba[BAsO{sub 5}]. The products could be separated mechanically. For neutron scattering experiments a sample was prepared with {sup 11}B(OH){sub 3} as a starting material. The crystal structure of Ba[B{sub 2}As{sub 2}O{sub 8}(OH){sub 2}] was determined by single-crystal X-ray diffraction and exhibits a layer structure with an unprecedented layer topology. The exact positions of the hydrogen atoms were determined using combined single-crystal X-ray and powder neutron diffraction investigations. Ba[B{sub 2}As{sub 2}O{sub 8}(OH){sub 2}] was further characterized by IR spectroscopy and EDX analysis. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Green chemistry: highly selective biocatalytic hydrolysis of nitrile compounds

CSIR Research Space (South Africa)

Brady, D

2006-02-28

Full Text Available O N +O O OH O N N +O O OH O R O O O S OO NH2 O O O O 1 R = H 2 R = CH3 3 R = NH2 4 R = OH 5 R = CH2CH3 6 R = H 7 R = OH 8 9 10 R1 = CH3, R2 = H 11 R1 = OCH3, R2 = OCH3 12 13 14 15 16 17 R = Br 18 R = C(O)OCH2CH3 19 R... CN NH2 CN O O CN CN CN CN CN CN CN CN CN CN CN NC CN Cl CN N CN OH CN CN NC NC CN NH2 NH2 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 Slide 32 © CSIR 2006 www.csir.co.za Beta-amino compounds N...

The effect of different pH modifier on formation of CdS nanoparticles

International Nuclear Information System (INIS)

Ren Xiaoxiao; Zhao Gaoling; Li Hong; Wu Wei; Han Gaorong

2008-01-01

CdS nanoparticles were prepared by hydrothermal method. The effects of pH modifier on the properties of CdS particles were studied. NaOH and NH 4 OH were chosen as the pH modifier. The morphology and optical properties of CdS particles were characterized by transmitted electron microscope (TEM) and optical absorption spectra analysis, respectively. The particle size of the samples whose pH modifier is NaOH was smaller than that of the CdS samples with NH 4 OH at the same pH value. Optical absorption edge of CdS shifted to longer wavelength with increasing pH value. Optical absorption edge of the samples with NH 4 OH as pH modifier shifted to the longer wavelength more significantly than that of those samples with NaOH as pH modifier. When CdS particles were adsorbed to the TiO 2 electrodes, the photoelectrochemical property of CdS-sensitized TiO 2 electrode showed that the samples with NH 4 OH as pH modifier had higher photocurrent than those samples with NaOH

Global modelling of the total OH reactivity: investigations on the “missing” OH sink and its atmospheric implications

Directory of Open Access Journals (Sweden)

V. Ferracci

2018-05-01

Full Text Available The hydroxyl radical (OH plays a crucial role in the chemistry of the atmosphere as it initiates the removal of most trace gases. A number of field campaigns have observed the presence of a missing OH sink in a variety of regions across the planet. A comparison of direct measurements of the OH loss frequency, also known as total OH reactivity (kOH, with the sum of individual known OH sinks (obtained via the simultaneous detection of species such as volatile organic compounds and nitrogen oxides indicates that, in some cases, up to 80 % of kOH is unaccounted for. In this work, the UM-UKCA chemistry-climate model was used to investigate the wider implications of the missing reactivity on the oxidising capacity of the atmosphere. Simulations of the present-day atmosphere were performed and the model was evaluated against an array of field measurements to verify that the known OH sinks were reproduced well, with a resulting good agreement found for most species. Following this, an additional sink was introduced to simulate the missing OH reactivity as an emission of a hypothetical molecule, X, which undergoes rapid reaction with OH. The magnitude and spatial distribution of this sink were underpinned by observations of the missing reactivity. Model runs showed that the missing reactivity accounted for on average 6 % of the total OH loss flux at the surface and up to 50 % in regions where emissions of the additional sink were high. The lifetime of the hydroxyl radical was reduced by 3 % in the boundary layer, whilst tropospheric methane lifetime increased by 2 % when the additional OH sink was included. As no OH recycling was introduced following the initial oxidation of X, these results can be interpreted as an upper limit of the effects of the missing reactivity on the oxidising capacity of the troposphere. The UM-UKCA simulations also allowed us to establish the atmospheric implications of the newly characterised reactions of peroxy

AMT1;1 transgenic rice plants with enhanced NH4(+) permeability show superior growth and higher yield under optimal and suboptimal NH4(+) conditions.

Science.gov (United States)

Ranathunge, Kosala; El-Kereamy, Ashraf; Gidda, Satinder; Bi, Yong-Mei; Rothstein, Steven J

2014-03-01

The major source of nitrogen for rice (Oryza sativa L.) is ammonium (NH4(+)). The NH4(+) uptake of roots is mainly governed by membrane transporters, with OsAMT1;1 being a prominent member of the OsAMT1 gene family that is known to be involved in NH4(+) transport in rice plants. However, little is known about its involvement in NH4(+) uptake in rice roots and subsequent effects on NH4(+) assimilation. This study shows that OsAMT1;1 is a constitutively expressed, nitrogen-responsive gene, and its protein product is localized in the plasma membrane. Its expression level is under the control of circadian rhythm. Transgenic rice lines (L-2 and L-3) overexpressing the OsAMT1;1 gene had the same root structure as the wild type (WT). However, they had 2-fold greater NH4(+) permeability than the WT, whereas OsAMT1;1 gene expression was 20-fold higher than in the WT. Analogous to the expression, transgenic lines had a higher NH4(+) content in the shoots and roots than the WT. Direct NH4(+) fluxes in the xylem showed that the transgenic lines had significantly greater uptake rates than the WT. Higher NH4(+) contents also promoted higher expression levels of genes in the nitrogen assimilation pathway, resulting in greater nitrogen assimilates, chlorophyll, starch, sugars, and grain yield in transgenic lines than in the WT under suboptimal and optimal nitrogen conditions. OsAMT1;1 also enhanced overall plant growth, especially under suboptimal NH4(+) levels. These results suggest that OsAMT1;1 has the potential for improving nitrogen use efficiency, plant growth, and grain yield under both suboptimal and optimal nitrogen fertilizer conditions.

AMT1;1 transgenic rice plants with enhanced NH4 + permeability show superior growth and higher yield under optimal and suboptimal NH4 + conditions

Science.gov (United States)

Rothstein, Steven J.

2014-01-01

The major source of nitrogen for rice (Oryza sativa L.) is ammonium (NH4 +). The NH4 + uptake of roots is mainly governed by membrane transporters, with OsAMT1;1 being a prominent member of the OsAMT1 gene family that is known to be involved in NH4 + transport in rice plants. However, little is known about its involvement in NH4 + uptake in rice roots and subsequent effects on NH4 + assimilation. This study shows that OsAMT1;1 is a constitutively expressed, nitrogen-responsive gene, and its protein product is localized in the plasma membrane. Its expression level is under the control of circadian rhythm. Transgenic rice lines (L-2 and L-3) overexpressing the OsAMT1;1 gene had the same root structure as the wild type (WT). However, they had 2-fold greater NH4 + permeability than the WT, whereas OsAMT1;1 gene expression was 20-fold higher than in the WT. Analogous to the expression, transgenic lines had a higher NH4 + content in the shoots and roots than the WT. Direct NH4 + fluxes in the xylem showed that the transgenic lines had significantly greater uptake rates than the WT. Higher NH4 + contents also promoted higher expression levels of genes in the nitrogen assimilation pathway, resulting in greater nitrogen assimilates, chlorophyll, starch, sugars, and grain yield in transgenic lines than in the WT under suboptimal and optimal nitrogen conditions. OsAMT1;1 also enhanced overall plant growth, especially under suboptimal NH4 + levels. These results suggest that OsAMT1;1 has the potential for improving nitrogen use efficiency, plant growth, and grain yield under both suboptimal and optimal nitrogen fertilizer conditions. PMID:24420570

Synthesis, crystal structure refinement, and nonlinear-optical properties of CaB3O5(OH): Comparative crystal chemistry of calcium triborates

International Nuclear Information System (INIS)

Yamnova, N. A.; Aksenov, S. M.; Stefanovich, S. Yu.; Volkov, A. S.; Dimitrova, O. V.

2015-01-01

Calcium triborate CaB 3 O5(OH) obtained by hydrothermal synthesis in the Ca(OH) 2 –H 3 BO 3 –Na 2 CO 3 –KCl system is studied by single-crystal X-ray diffraction. The parameters of the orthorhombic unit cell are as follows: a = 13.490(1), b = 6.9576(3), and c = 4.3930(2) Å; V = 412.32(3) Å 3 and space group Pna2 1 . The structure is refined in the anisotropic approximation of the atomic displacement parameters to R = 4.28% using 972 vertical bar F vertical bar > 4σ(F). It is confirmed that the crystal structure of Ca triborate CaB 3 O 5 (OH) is identical to that described earlier. The hydrogen atom is localized. An SHG signal stronger than that of the quartz standard is registered. The phase transition of calcium triborate into calciborite is found on heating. The comparative crystal-chemical analysis of a series of borates with the general chemical formula 2CaO · 3B 2 O 3 · nH 2 O (n = 0–13) with the constant CaO: B 2 O 3 = 2: 3 ratio and variable content of water is performed

G331.512–0.103: An Interstellar Laboratory for Molecular Synthesis. I. The Ortho-to-para Ratios for CH3OH and CH3CN

Science.gov (United States)

Mendoza, Edgar; Bronfman, Leonardo; Duronea, Nicolas U.; Lépine, Jacques R. D.; Finger, Ricardo; Merello, Manuel; Hervías-Caimapo, Carlos; Gama, Diana R. G.; Reyes, Nicolas; Åke-Nyman, Lars

2018-02-01

Spectral line surveys reveal rich molecular reservoirs in G331.512–0.103, a compact radio source in the center of an energetic molecular outflow. In this first work, we analyze the physical conditions of the source by means of CH3OH and CH3CN. The observations were performed with the APEX Telescope. Six different system configurations were defined to cover most of the band within (292–356) GHz as a consequence, we detected a forest of lines toward the central core. A total of 70 lines of A/E–CH3OH and A/E–CH3CN were analyzed, including torsionally excited transitions of CH3OH ({ν }t=1). In a search for all the isotopologues, we identified transitions of 13CH3OH. The physical conditions were derived considering collisional and radiative processes. We found common temperatures for each A and E symmetry of CH3OH and CH3CN; the derived column densities indicate an A/E equilibrated ratio for both tracers. The results reveal that CH3CN and CH3OH trace a hot and cold component with {T}k∼ 141 K and {T}k∼ 74 K, respectively. In agreement with previous ALMA observations, the models show that the emission region is compact (≲ 5\\buildrel{\\prime\\prime}\\over{.} 5) with gas density n(H2) = (0.7–1)×107 cm‑3. The CH3OH/CH3CN abundance ratio and the evidences for prebiotic and complex organic molecules suggest a rich and active chemistry toward G331.512–0.103.

Evaluation of the phase composition of (NH4)2SO4 + (NH4)H2PO4 mixtures by X-ray diffractometry

International Nuclear Information System (INIS)

Ortiz, Angel L.; Cumbrera, Francisco L.; Perez, Jose; Vas, Beatriz del; Perez, Eduardo

2009-01-01

The phase composition of standard (NH 4 ) 2 SO 4 + (NH 4 )H 2 PO 4 mixtures was investigated by X-ray diffractometry (XRD) using the internal-standard, reference-intensity-ratio, and Rietveld methods. It was found that the Rietveld method yields the most accurate phase-composition measurements, with an average error of ∼2 wt.%. It was also found that the internal-standard method is only effective in determining the phase composition if the calibration curve for (NH 4 )H 2 PO 4 is used, giving an average error of ∼6.5 wt.%. On the contrary, the internal-standard method with the calibration curve of the (NH 4 ) 2 SO 4 phase and the reference-intensity-ratio method are not valid. The inappropriateness of these two methods was attributed to graininess in the (NH 4 ) 2 SO 4 phase, with the attendant deviation of its diffracted intensities from the theoretical values. Direct scanning electron microscopy observations of the morphology of the powder particles in the mixtures showed clear evidence of the large agglomerates formed because the individual powder particles are partially sintered together during milling, thus corroborating the graininess determined by the XRD analyses. Finally, the implications of the present study for the quantitative phase-composition analysis of (NH 4 ) 2 SO 4 + (NH 4 )H 2 PO 4 mixtures, which are of great technological importance for the fire prevention industry, are discussed.

Synthesis of Hydroxysodalite From Paper Sludge Ash Using NaOH-LiOH Mixtures

Directory of Open Access Journals (Sweden)

Takaaki Wajima

2017-06-01

Full Text Available Hydroxysodalite zeolite was synthesized at 90 oC from paper sludge ash, which is industrial wastes in paper manufacturing, using NaOH-LiOH mixed solution. Paper sludge ash was discharged from paper making plant as industrial wastes, and the amount is increasing annually. The new utilization of paper sludge ash is desired. Hydroxysodalite can be used to remove HCl gas at high temperature, and there are papers for hydroxysodalite synthesis from various ashes, for example, coal fly ash. In my previous study, hydroxysodalite can be synthesized from paper sludge ash. However, little information can be available on the synthesis of hydroxysodalite from paper sludge ash. Therefore, we attempted to examine the synthesis of hydroxysodalite from paper sludge ash using NaOH-LiOH mixtures. Hydroxysodalite [Na6Al6Si6O24‧8H2O] was obtained in the mixed solution with Li / (Li + Na ratios smaller than 0.25, while katoite [Ca3Al2(SiO4(OH8] was formed in the mixed solutions with the other molar ratios, due to the dissolution of gehlenite [Ca2Al2SiO7]. The observed concentrations of Si and Al in the solution during the reaction explain the synthesis of reaction products, which depends on alkali species.

Preparation of silver chloride nanoparticles by a mechanical treatment of the system NH4Cl−AgNO3−NH4NO3

Directory of Open Access Journals (Sweden)

Farit Urakaev

2014-08-01

Full Text Available Silver chloride nanoparticles dispersed within ammonium nitrate matrix have been prepared though displacement mechanochemical reaction NH4Cl + AgNO3 + z NH4NO3 = (z+1 NH4 NO3 + AgCl at various z coefficients z1 = 7.22 and z2 = 3.64. The intermediate compound of NH4Ag(NO32 were recorded after mechanochemical processing of studied system. By using simultaneous TG and DSC measurements possibilities to prepare silver chloride in its free form have been discussed by using thermal treatment.

Carbon dioxide sequestration using NaHSO4 and NaOH: A dissolution and carbonation optimisation study.

Science.gov (United States)

Sanna, Aimaro; Steel, Luc; Maroto-Valer, M Mercedes

2017-03-15

The use of NaHSO 4 to leach out Mg fromlizardite-rich serpentinite (in form of MgSO 4 ) and the carbonation of CO 2 (captured in form of Na 2 CO 3 using NaOH) to form MgCO 3 and Na 2 SO 4 was investigated. Unlike ammonium sulphate, sodium sulphate can be separated via precipitation during the recycling step avoiding energy intensive evaporation process required in NH 4 -based processes. To determine the effectiveness of the NaHSO 4 /NaOH process when applied to lizardite, the optimisation of the dissolution and carbonation steps were performed using a UK lizardite-rich serpentine. Temperature, solid/liquid ratio, particle size, concentration and molar ratio were evaluated. An optimal dissolution efficiency of 69.6% was achieved over 3 h at 100 °C using 1.4 M sodium bisulphate and 50 g/l serpentine with particle size 75-150 μm. An optimal carbonation efficiency of 95.4% was achieved over 30 min at 90 °C and 1:1 magnesium:sodium carbonate molar ratio using non-synthesised solution. The CO 2 sequestration capacity was 223.6 g carbon dioxide/kg serpentine (66.4% in terms of Mg bonded to hydromagnesite), which is comparable with those obtained using ammonium based processes. Therefore, lizardite-rich serpentinites represent a valuable resource for the NaHSO 4 /NaOH based pH swing mineralisation process. Copyright © 2016 Elsevier Ltd. All rights reserved.

Relativistic GW calculations on CH3NH3PbI3 and CH3NH3SnI3 perovskites for solar cell applications.

Science.gov (United States)

Umari, Paolo; Mosconi, Edoardo; De Angelis, Filippo

2014-03-26

Hybrid AMX3 perovskites (A = Cs, CH3NH3; M = Sn, Pb; X = halide) have revolutionized the scenario of emerging photovoltaic technologies, with very recent results demonstrating 15% efficient solar cells. The CH3NH3PbI3/MAPb(I(1-x)Cl(x))3 perovskites have dominated the field, while the similar CH3NH3SnI3 has not been exploited for photovoltaic applications. Replacement of Pb by Sn would facilitate the large uptake of perovskite-based photovoltaics. Despite the extremely fast progress, the materials electronic properties which are key to the photovoltaic performance are relatively little understood. Density Functional Theory electronic structure methods have so far delivered an unbalanced description of Pb- and Sn-based perovskites. Here we develop an effective GW method incorporating spin-orbit coupling which allows us to accurately model the electronic, optical and transport properties of CH3NH3SnI3 and CH3NH3PbI3, opening the way to new materials design. The different CH3NH3SnI3 and CH3NH3PbI3 electronic properties are discussed in light of their exploitation for solar cells, and found to be dominantly due to relativistic effects. These effects stabilize the CH3NH3PbI3 material towards oxidation, by inducing a deeper valence band edge. Relativistic effects, however, also increase the material band-gap compared to CH3NH3SnI3, due to the valence band energy downshift (~0.7 eV) being only partly compensated by the conduction band downshift (~0.2 eV).

Effect of mixing geopolymer and peat on bearing capacity in Ogan Komering Ilir (OKI) by California bearing ratio (CBR) test

Science.gov (United States)

Raharja, Danang S.; Hadiwardoyo, Sigit P.; Rahayu, Wiwik; Zain, Nasuhi

2017-06-01

Geopolymer is binder material that consists of solid material and the activator solution. Geopolymer material has successfully replaced cement in the manufacture of concrete with aluminosilicate bonding system. Geopolymer concrete has properties similar to cement concrete with high compressive strength, low shrinkage value, relatively low creep value, as well as acid-resistant. Based on these, the addition of polymers in peat soils is expected to improve the bearing capacity of peat soils. A study on the influence of geopolymer addition in peat soils was done by comparing before and after the peat soil was mixed with geopolymer using CBR (California Bearing Ratio) test in unsoaked and soaked conditions. 10% mixture content of the peat dry was used, weighted with a variety of curing time 4 hours, 5 days, and 10 days. There were two methods of mixing: first, peat was mixed with fly ash geopolymer activators and mixed solution (waterglass, NaOH, water), and second, peat was mixed with fly ash and mixed geopolymer (waterglass, NaOH, water, fly ash). Changes were observed in specific gravity, dry density, acidity (pH), and the microscopic structure with Scanning Electron Microscope (SEM). Curing time did not significantly affect the CBR value. It even shows a tendency to decline with longer curing time. The first type mixture obtained CBR value of: 5.4% for 4 hours curing, 4.6% for 5 days curing and 3.6% for 10 days curing. The second type mixture obtained CBR value of: 6.1% for 4 hours curing, 5.2% for 5 days curing and 5.2% for 10 days curing. Furthermore, the specific gravity value, dry density, pH near neutral and swelling percentage increased. From both variants, the second type mixture shows better results than the first type mixture. The results of SEM (Scanning Electron Microscopy) show the structure of the peat which became denser with the fly ash particles filling the peat microporous. Also, the reaction of fly ash with geopolymer is indicated by the solid

Ammonia oxidation at high pressure and intermediate temperatures

DEFF Research Database (Denmark)

Song, Yu; Hashemi, Hamid; Christensen, Jakob Munkholt

2016-01-01

Ammonia oxidation experiments were conducted at high pressure (30 bar and 100 bar) under oxidizing and stoichiometric conditions, respectively, and temperatures ranging from 450 to 925 K. The oxidation of ammonia was slow under stoichiometric conditions in the temperature range investigated. Under...... oxidizing conditions the onset temperature for reaction was 850–875 K at 30 bar, while at 100 bar it was about 800 K, with complete consumption of NH3 at 875 K. The products of reaction were N2 and N2O, while NO and NO2 concentrations were below the detection limit even under oxidizing conditions. The data...... was satisfactory. The main oxidation path for NH3 at high pressure under oxidizing conditions is NH3⟶+OH NH2⟶+HO2,NO2 H2NO⟶+O2 HNO⟶+O2 NO ⟶+NH2 N2. The modeling predictions are most sensitive to the reactions NH2 + NO = NNH + OH and NH2 + HO2 = H2NO + OH, which promote the ammonia consumption by forming OH...

Appendix S-NH-1 and S-NH-2 of the experiment operating specification for the semiscale MOD-2C small break LOCA without HPI experiment series

International Nuclear Information System (INIS)

Owca, W.A.

1985-10-01

This document is Appendix S-NH--1 and S-NH-2 of the Experiment Operating Specification (EOS) for the Small Break LOCA without high pressure injection (HPI) series. It contains detailed information on the S-NH-1 and S-NH-2 experiment operation and facility configuration necessary to meet the series objectives stated in the main EOS body. 14 refs., 17 figs

FORMATION OF HYDROXYLAMINE ON DUST GRAINS VIA AMMONIA OXIDATION

Energy Technology Data Exchange (ETDEWEB)

He, Jiao; Vidali, Gianfranco [Physics Department, Syracuse University, Syracuse, NY 13244 (United States); Lemaire, Jean-Louis [Paris Observatory, F-75014 Paris (France); Garrod, Robin T., E-mail: gvidali@syr.edu [Center for Radiophysics and Space Research, Cornell University, Ithaca, NY 14853 (United States)

2015-01-20

The quest to detect prebiotic molecules in space, notably amino acids, requires an understanding of the chemistry involving nitrogen atoms. Hydroxylamine (NH{sub 2}OH) is considered a precursor to the amino acid glycine. Although not yet detected, NH{sub 2}OH is considered a likely target of detection with ALMA. We report on an experimental investigation of the formation of hydroxylamine on an amorphous silicate surface via the oxidation of ammonia. The experimental data are then fed into a simulation of the formation of NH{sub 2}OH in dense cloud conditions. On ices at 14 K and with a modest activation energy barrier, NH{sub 2}OH is found to be formed with an abundance that never falls below a factor 10 with respect to NH{sub 3}. Suggestions of conditions for future observations are provided.

Review of ASME-NH Design Materials for Creep-Fatigue

International Nuclear Information System (INIS)

Koo, Gyeong Hoi; Kim, Jong Bum

2010-01-01

To review and recommend the candidate design materials for the Sodium-Cooled Fast Reactor, the material sensitivity evaluations by the comparison of design data between the ASME-NH materials were performed by using the SIE ASME-NH computer program implementing the material database of the ASME-NH. The design material data provided by the ASME-NH code are the elastic modulus and yield Strength, Time-Independent Allowable Stress Intensity value, time-dependent allowable stress intensity value, expected minimum stress-to rupture value, stress rupture Factors for weldment, isochronous stress-strain curves, and design fatigue curves. Among these, the data related with the creep-fatigue evaluation are investigated in this study

Variability of OH(3-1) and OH(6-2) emission altitude and volume emission rate from 2003 to 2011

Science.gov (United States)

Teiser, Georg; von Savigny, Christian

2017-08-01

In this study we report on variability in emission rate and centroid emission altitude of the OH(3-1) and OH(6-2) Meinel bands in the terrestrial nightglow based on spaceborne nightglow measurements with the SCIAMACHY (SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY) instrument on the Envisat satellite. The SCIAMACHY observations cover the time period from August 2002 to April 2012 and the nighttime observations used in this study are performed at 10:00 p.m. local solar time. Characterizing variability in OH emission altitude - particularly potential long-term variations - is important for an appropriate interpretation of ground-based OH rotational temperature measurements, because simultaneous observations of the vertical OH volume emission rate profile are usually not available for these measurements. OH emission altitude and vertically integrated emission rate time series with daily resolution for the OH(3-1) band and monthly resolution for the OH(6-2) band were analyzed using a standard multilinear regression approach allowing for seasonal variations, QBO-effects (Quasi-Biennial Oscillation), solar cycle (SC) variability and a linear long-term trend. The analysis focuses on low latitudes, where SCIAMACHY nighttime observations are available all year. The dominant sources of variability for both OH emission rate and altitude are the semi-annual and annual variations, with emission rate and altitude being highly anti-correlated. There is some evidence for a 11-year solar cycle signature in the vertically integrated emission rate and in the centroid emission altitude of both the OH(3-1) and OH(6-2) bands.

Grizzly bear

Science.gov (United States)

Schwartz, C.C.; Miller, S.D.; Haroldson, M.A.; Feldhamer, G.; Thompson, B.; Chapman, J.

2003-01-01

The grizzly bear inspires fear, awe, and respect in humans to a degree unmatched by any other North American wild mammal. Like other bear species, it can inflict serious injury and death on humans and sometimes does. Unlike the polar bear (Ursus maritimus) of the sparsely inhabited northern arctic, however, grizzly bears still live in areas visited by crowds of people, where presence of the grizzly remains physically real and emotionally dominant. A hike in the wilderness that includes grizzly bears is different from a stroll in a forest from which grizzly bears have been purged; nighttime conversations around the campfire and dreams in the tent reflect the presence of the great bear. Contributing to the aura of the grizzly bear is the mixture of myth and reality about its ferocity. unpredictable disposition, large size, strength, huge canines, long claws, keen senses, swiftness, and playfulness. They share characteristics with humans such as generalist life history strategies. extended periods of maternal care, and omnivorous diets. These factors capture the human imagination in ways distinct from other North American mammals. Precontact Native American legends reflected the same fascination with the grizzly bear as modern stories and legends (Rockwell 1991).

Hyperfine excitation of OH+ by H

Science.gov (United States)

Lique, François; Bulut, Niyazi; Roncero, Octavio

2016-10-01

The OH+ ions are widespread in the interstellar medium and play an important role in the interstellar chemistry as they act as precursors to the H2O molecule. Accurate determination of their abundance rely on their collisional rate coefficients with atomic hydrogen and electrons. In this paper, we derive OH+-H fine and hyperfine-resolved rate coefficients by extrapolating recent quantum wave packet calculations for the OH+ + H collisions, including inelastic and exchange processes. The extrapolation method used is based on the infinite order sudden approach. State-to-state rate coefficients between the first 22 fine levels and 43 hyperfine levels of OH+ were obtained for temperatures ranging from 10 to 1000 K. Fine structure-resolved rate coefficients present a strong propensity rule in favour of Δj = ΔN transitions. The Δj = ΔF propensity rule is observed for the hyperfine transitions. The new rate coefficients will help significantly in the interpretation of OH+ spectra from photon-dominated region (PDR), and enable the OH+ molecule to become a powerful astrophysical tool for studying the oxygen chemistry.

Synthesis of Formamide and Related Organic Species in the Interstellar Medium via Chemical Dynamics Simulations

Science.gov (United States)

Spezia, Riccardo; Jeanvoine, Yannick; Hase, William L.; Song, Kihyung; Largo, Antonio

2016-08-01

We show, by means of direct dynamics simulations, how it is possible to define possible reactants and mechanisms leading to the formation of formamide in the interstellar medium. In particular, different ion-molecule reactions in the gas phase were considered: NH3OH+, NH2OH{}2+, H2COH+, and NH4 + for the ions and NH2OH, H2CO, and NH3 for the partner neutrals. These calculations were combined with high level ab initio calculations to investigate possible further evolution of the products observed. In particular, for formamide, we propose that the NH2OH{}2+ + H2CO reaction can produce an isomer, NH2OCH{}2+, that, after dissociative recombination, can produce neutral formamide, which was observed in space. The direct dynamics do not pre-impose any reaction pathways and in other reactions, we did not observe the formation of formamide or any possible precursor. On the other hand, we obtained other interesting reactions, like the formation of NH2CH{}2+. Finally, some radiative association processes are proposed. All of the results obtained are discussed in light of the species observed in radioastronomy.

Experimental studies of the formation of cluster ions formed by corona discharge in an atmosphere containing SO₂, NH₃, and H₂O

DEFF Research Database (Denmark)

Hvelplund, Preben; Pedersen, Jens Olaf Pepke; Støchkel, Kristian

2013-01-01

Abstract We report on studies of ion-induced nucleation in a corona discharge taking place in an atmosphere containing SO2, NH3, and H2O at standard temperature and pressure. Positive ions such as H3O+(H2O)n, NH4+(H2O)n, and H+(H2SO4)(H2O)n and negative ions such as HSO5-(H2O)n, SO4-(H2O)n, HSO4-(H......5-, which has been observed in many studies, in our experiments is contaminated by O2-(HNO3)(H2O) ions, and this may also have been the case in other experiments. Finally an ion with m/z = 232 (where m is the cluster mass in amu and z is the charge state), capable of attaching H2O...

Topologically identical, but geometrically isomeric layers in hydrous α-, β-Rb[UO2(AsO3OH)(AsO2(OH)2)]·H2O and anhydrous Rb[UO2(AsO3OH)(AsO2(OH)2)

International Nuclear Information System (INIS)

Yu, Na; Klepov, Vladislav V.; Villa, Eric M.; Bosbach, Dirk; Suleimanov, Evgeny V.; Depmeier, Wulf; Albrecht-Schmitt, Thomas E.; Alekseev, Evgeny V.

2014-01-01

The hydrothermal reaction of uranyl nitrate with rubidium nitrate and arsenic (III) oxide results in the formation of polymorphic α- and β-Rb[UO 2 (AsO 3 OH)(AsO 2 (OH) 2 )]·H 2 O (α-, β-RbUAs) and the anhydrous phase Rb[UO 2 (AsO 3 OH)(AsO 2 (OH) 2 )] (RbUAs). These phases were structurally, chemically and spectroscopically characterized. The structures of all three compounds are based upon topologically identical, but geometrically isomeric layers. The layers are linked with each other by means of the Rb cations and hydrogen bonding. Dehydration experiments demonstrate that water deintercalation from hydrous α- and β-RbUAs yields anhydrous RbUAs via topotactic reactions. - Graphical abstract: Three different layer geometries observed in the structures of Rb[UO 2 (AsO 3 OH)(AsO 2 (OH) 2 )] and α- and β- Rb[UO 2 (AsO 3 OH)(AsO 2 (OH) 2 )]·H 2 O. Two different coordination environments of uranium polyhedra (types I and II) are shown schematically on the top of the figure. - Highlights: • Three new uranyl arsenates were synthesized from the hydrothermal reactions. • The phases consist of the topologically identical but geometrically different layers. • Topotactic transitions were observed in the processes of mono-hyrates dehydration

OH/IR stars in the Galaxy

International Nuclear Information System (INIS)

Baud, B.

1978-01-01

Radio astronomical observations leading to the discovery of 71 OH/IR sources are described in this thesis. These OH/IR sources are characterized by their double peaked OH emission profile at a wavelength of 18 cm and by their strong IR infrared emission. An analysis of the distribution and radial velocities of a number of previously known and new OH/IR sources was performed. The parameter ΔV (the velocity separation between two emission peaks of the 18 cm line profile) was found to be a good criterion for a population classification with respect to stellar age

Oral Conditioned Cues Can Enhance or Inhibit Ethanol (EtOH)-Seeking and EtOH-Relapse Drinking by Alcohol-Preferring (P) Rats.

Science.gov (United States)

Knight, Christopher P; Hauser, Sheketha R; Deehan, Gerald A; Toalston, Jamie E; McBride, William J; Rodd, Zachary A

2016-04-01

Conditioned cues can elicit drug-seeking in both humans and rodents. The majority of preclinical research has employed excitatory conditioned cues (stimuli present throughout the availability of a reinforcer), but oral consumption of alcohol is similar to a conditional stimuli (presence of stimuli is paired with the delivery of the reinforcer) approach. The current experiments attempted to determine the effects of conditional stimuli (both excitatory and inhibitory) on the expression of context-induced ethanol (EtOH)-seeking. Alcohol-preferring (P) rats self-administered EtOH and water in standard 2-lever operant chambers. A flavor was added to the EtOH solution (CS+) during the EtOH self-administration sessions. After 10 weeks, rats underwent extinction training (7 sessions), followed by a 2-week home cage period. Another flavor was present during extinction (CS-). Rats were exposed to a third flavor in a non-drug-paired environment (CS(0)). EtOH-seeking was assessed in the presence of no cue, CS+, CS-, or CS(0) in the dipper previously associated with EtOH self-administration (no EtOH available). Rats were maintained a week in their home cage before being returned to the operant chambers with access to EtOH (flavored with no cue, CS+, CS-, or CS(0)). The results indicated that the presence of the CS+ enhanced EtOH-seeking, while the presence of the CS- suppressed EtOH-seeking. Similarly, adding the CS- flavor to 15% EtOH reduced responding for EtOH while the CS+ enhanced responding for EtOH during relapse testing. Overall, the data indicate that conditional stimuli are effective at altering both EtOH-seeking behavior and EtOH-relapse drinking. Copyright © 2016 by the Research Society on Alcoholism.

Biopesticide activity of sugarcane associated rhizobacteria: Ochrobactrum intermedium strain NH-5 and Stenotrophomonas maltophilia strain NH-300 against red rot under field conditions

Directory of Open Access Journals (Sweden)

Muhammad Nadeem HASSAN

2014-09-01

Full Text Available Colletotrichum falcatum is the major fungal pathogen causing sugarcane red rot. Four antagonistic bacterial strains exhibiting biocontrol activity against this pathogen in greenhouse conditions were characterized for production of different antifungal metabolites and biocontrol determinants to elucidate the mechanism of action involved in their antagonistic activity. The strains were also evaluated under field conditions to assess their biocontrol potential. All the strains produced hydrogen cyanide (HCN, and volatile and diffusible antibiotics. In addition, the Ochrobactrum intermedium strain NH-5 produced siderophores and the broad spectrum antibiotic 2, 4-diacetylphloroglucinol (2,4-DAPG; Pseudomonas sp. NH-203 produced siderophores, and Pseudomonas sp. NH-276 produced protease. Two strains, Ochrobactrum intermedium NH-5 and Stenotrophomonas maltophilia NH-300, exhibited good biocontrol activity, suppressing red rot by 44–52% on two sugarcane varieties, SPF-234 and Co-1148, in field experiments. The strains gave consistent results in three consecutive years and showed potential to be used as biopesticides.

Thin-Film Transformation of NH4 PbI3 to CH3 NH3 PbI3 Perovskite: A Methylamine-Induced Conversion-Healing Process.

Science.gov (United States)

Zong, Yingxia; Zhou, Yuanyuan; Ju, Minggang; Garces, Hector F; Krause, Amanda R; Ji, Fuxiang; Cui, Guanglei; Zeng, Xiao Cheng; Padture, Nitin P; Pang, Shuping

2016-11-14

Methylamine-induced thin-film transformation at room-temperature is discovered, where a porous, rough, polycrystalline NH 4 PbI 3 non-perovskite thin film converts stepwise into a dense, ultrasmooth, textured CH 3 NH 3 PbI 3 perovskite thin film. Owing to the beneficial phase/structural development of the thin film, its photovoltaic properties undergo dramatic enhancement during this NH 4 PbI 3 -to-CH 3 NH 3 PbI 3 transformation process. The chemical origins of this transformation are studied at various length scales. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

The effect of different pH modifier on formation of CdS nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Xiaoxiao, Ren [State Key Laboratory of Silicon Materials, Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China); Zhao Gaoling [State Key Laboratory of Silicon Materials, Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China)], E-mail: glzhao@zju.edu.cn; Hong, Li; Wei, Wu; Gaorong, Han [State Key Laboratory of Silicon Materials, Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China)

2008-10-06

CdS nanoparticles were prepared by hydrothermal method. The effects of pH modifier on the properties of CdS particles were studied. NaOH and NH{sub 4}OH were chosen as the pH modifier. The morphology and optical properties of CdS particles were characterized by transmitted electron microscope (TEM) and optical absorption spectra analysis, respectively. The particle size of the samples whose pH modifier is NaOH was smaller than that of the CdS samples with NH{sub 4}OH at the same pH value. Optical absorption edge of CdS shifted to longer wavelength with increasing pH value. Optical absorption edge of the samples with NH{sub 4}OH as pH modifier shifted to the longer wavelength more significantly than that of those samples with NaOH as pH modifier. When CdS particles were adsorbed to the TiO{sub 2} electrodes, the photoelectrochemical property of CdS-sensitized TiO{sub 2} electrode showed that the samples with NH{sub 4}OH as pH modifier had higher photocurrent than those samples with NaOH.

?????????? ?????, ?????????? ??????????? ?? ?????????? ?????????? ????? ? ?????? ???????? ZnCl2 +NH4Cl

OpenAIRE

Kuntyi, Orest; Zozulya, Galyna

2010-01-01

Zinc cementation by magnesium from ZnCl2 + NH4Cl aqueous solutions has been investigated. The amount of magnesium has been established as 0.8?2.0 g per 1 g of conditioned zinc to obtain recovery degree ? 99 %. At low concentrations of Zn2+ ions (0.025?0.1 M ZnCl2) dispersed deposit is formed with nanoparticles of reduced metal; at high concentrations (0.25?0.5 M) coarse-crystalline and fern-shaped deposit is formed. ?????????? ?????????? ????? ??????? ? ?????? ???????? ZnCl2 + NH4Cl. ????????...

Conversion of CH/sub 3/OH into olefins over Al/sub 2/O/sub 3/Cr/sub 2/O/sub 3/ treated with CF/sub 3/Cl

Energy Technology Data Exchange (ETDEWEB)

Kurosaki, A; Okazaki, S

1983-05-01

Hydrocarbon production from methanol has become an important process for obtaining materials such as ethylene and propylene from coal, instead of petroleum. A mixed oxide of Al and Cr having an atomic ratio (Al/Cr) of around 9 showed catalytic activity for the conversion of CH/sub 3/OH into olefins and aromatic compounds after treatment with CF/sub 3/Cl at 450/sup 0/C. The mixed oxide treated with CF/sub 3/Cl adsorbed a considerable amount of NH/sub 3/ even at temperatures as high as 500/sup 0/C. Analyses of the compositions on the surface layer by using XPS showed that the F component was predominantly bound to Al, not to Cr. Strong acid sites related to the less crystallized AlF/sub 3/ seemed to be able to promote the conversion of CH/sub 3/OH.

Pharmacokinetics of 1,25(OH)(2)D(3) and 1alpha(OH)D(3) in normal and uraemic men

DEFF Research Database (Denmark)

Brandi, Lisbet; Egfjord, Martin; Olgaard, Klaus

2002-01-01

,25(OH)(2)D(3) (n=6) protocol. RESULTS: After oral administration of 1,25(OH)(2)D(3) the bioavailability of 1,25(OH)(2)D(3) was 70.6+/-5.8/72.2+/-4.8% in healthy volunteers/uraemic patients (n.s.). After i.v. administration the volume of distribution of 1,25(OH)(2)D(3) was similar, 0.49+/-0.14 vs 0...

First detection of cyanamide (NH2CN) towards solar-type protostars

Science.gov (United States)

Coutens, A.; Willis, E. R.; Garrod, R. T.; Müller, H. S. P.; Bourke, T. L.; Calcutt, H.; Drozdovskaya, M. N.; Jørgensen, J. K.; Ligterink, N. F. W.; Persson, M. V.; Stéphan, G.; van der Wiel, M. H. D.; van Dishoeck, E. F.; Wampfler, S. F.

2018-05-01

Searches for the prebiotically relevant cyanamide (NH2CN) towards solar-type protostars have not been reported in the literature. We present here the first detection of this species in the warm gas surrounding two solar-type protostars, using data from the Atacama Large Millimeter/Submillimeter Array Protostellar Interferometric Line Survey (PILS) of IRAS 16293-2422 B and observations from the IRAM Plateau de Bure Interferometer of NGC 1333 IRAS2A. We also detected the deuterated and 13C isotopologs of NH2CN towards IRAS 16293-2422 B. This is the first detection of NHDCN in the interstellar medium. Based on a local thermodynamic equilibrium analysis, we find that the deuteration of cyanamide ( 1.7%) is similar to that of formamide (NH2CHO), which may suggest that these two molecules share NH2 as a common precursor. The NH2CN/NH2CHO abundance ratio is about 0.2 for IRAS 16293-2422 B and 0.02 for IRAS2A, which is comparable to the range of values found for Sgr B2. We explored the possible formation of NH2CN on grains through the NH2 + CN reaction using the chemical model MAGICKAL. Grain-surface chemistry appears capable of reproducing the gas-phase abundance of NH2CN with the correct choice of physical parameters.

77 FR 70423 - Black Bear Hydro Partners, LLC and Black Bear Development Holdings, LLC and Black Bear SO, LLC...

Science.gov (United States)

2012-11-26

... Bear Hydro Partners, LLC and Black Bear Development Holdings, LLC and Black Bear SO, LLC; Notice of..., 2012, Black Bear Hydro Partners, LLC, sole licensee (transferor) and Black Bear Development Holdings, LLC and Black Bear SO, LLC (transferees) filed an application for the partial the transfer of licenses...

Analysis of Zr++++ dan ZrO++ cations through their Hydroxide precipitate with thermal differential analysis method

International Nuclear Information System (INIS)

Simbolon, Sahat; Ratmi-Herlani

1996-01-01

Hydroxide of zirconyl and zirconium, made by reacting zirconium and zirconyl solution with NH 4 OH 25 % solution, were analysed by thermal differential analysis (TDA). It was also done TDA method for hydroxide of zirconyl and zirconium, made by reacting zirconyl chloride and zirconium chloride solid with NH 4 OH 25 % solution directly. It was found that TDA of hydroxide precipitate made through solution had a clear TDA counter, meanwhile TDA thermogram of hydroxide precipitate made by direct adding NH 4 OH 25 % solution to zirconyl and zirconium hydroxide had no clear TDA thermogram. Precipitate Zr O(OH) 2 and Zr(OH) 4 found through solution could be differentiated each other based on their TDA thermograms

Herschel/HIFI deepens the circumstellar NH3 enigma

NARCIS (Netherlands)

Menten, K. M.; Wyrowski, F.; Alcolea, J.; De Beck, E.; Decin, L.; Marston, A. P.; Bujarrabal, V.; Cernicharo, J.; Dominik, C.; Justtanont, K.; de Koter, A.; Melnick, G.; Neufeld, D. A.; Olofsson, H.; Planesas, P.; Schmidt, M.; Schoier, F. L.; Szczerba, R.; Teyssier, D.; Waters, L. B. F. M.; Edwards, K.; Olberg, M.; Phillips, T. G.; Morris, P.; Salez, M.; Caux, E.

2010-01-01

Context. Circumstellar envelopes (CSEs) of a variety of evolved stars have been found to contain ammonia (NH3) in amounts that exceed predictions from conventional chemical models by many orders of magnitude. Aims. The observations reported here were performed in order to better constrain the NH3

Phylogeography of mitochondrial DNA variation in brown bears and polar bears.

Science.gov (United States)

Shields, G F; Adams, D; Garner, G; Labelle, M; Pietsch, J; Ramsay, M; Schwartz, C; Titus, K; Williamson, S

2000-05-01

We analyzed 286 nucleotides of the middle portion of the mitochondrial cytochrome b gene of 61 brown bears from three locations in Alaska and 55 polar bears from Arctic Canada and Arctic Siberia to test our earlier observations of paraphyly between polar bears and brown bears as well as to test the extreme uniqueness of mitochondrial DNA types of brown bears on Admiralty, Baranof, and Chichagof (ABC) islands of southeastern Alaska. We also investigated the phylogeography of brown bears of Alaska's Kenai Peninsula in relation to other Alaskan brown bears because the former are being threatened by increased human development. We predicted that: (1) mtDNA paraphyly between brown bears and polar bears would be upheld, (2) the mtDNA uniqueness of brown bears of the ABC islands would be upheld, and (3) brown bears of the Kenai Peninsula would belong to either clade II or clade III of brown bears of our earlier studies of mtDNA. All of our predictions were upheld through the analysis of these additional samples. Copyright 2000 Academic Press.

Phylogeography of mitochondrial DNA variation in brown bears and polar bears

Science.gov (United States)

Shields, Gerald F.; Adams, Deborah; Garner, Gerald W.; Labelle, Martine; Pietsch, Jacy; Ramsay, Malcolm; Schwartz, Charles; Titus, Kimberly; Williamson, Scott

2000-01-01

We analyzed 286 nucleotides of the middle portion of the mitochondrial cytochrome b gene of 61 brown bears from three locations in Alaska and 55 polar bears from Arctic Canada and Arctic Siberia to test our earlier observations of paraphyly between polar bears and brown bears as well as to test the extreme uniqueness of mitochondrial DNA types of brown bears on Admiralty, Baranof, and Chichagof (ABC) islands of southeastern Alaska. We also investigated the phylogeography of brown bears of Alaska's Kenai Peninsula in relation to other Alaskan brown bears because the former are being threatened by increased human development. We predicted that: (1) mtDNA paraphyly between brown bears and polar bears would be upheld, (2) the mtDNA uniqueness of brown bears of the ABC islands would be upheld, and (3) brown bears of the Kenai Peninsula would belong to either clade II or clade III of brown bears of our earlier studies of mtDNA. All of our predictions were upheld through the analysis of these additional samples.

Effects of atmospheric ammonia (NH3) on terrestrial vegetation: a review

International Nuclear Information System (INIS)

Krupa, S.V.

2003-01-01

A review of atmospheric ammonia (NH 3 ) and ammonium (NH 4 + ) deposition and their effects on plants. - At the global scale, among all N (nitrogen) species in the atmosphere and their deposition on to terrestrial vegetation and other receptors, NH 3 (ammonia) is considered to be the foremost. The major sources for atmospheric NH 3 are agricultural activities and animal feedlot operations, followed by biomass burning (including forest fires) and to a lesser extent fossil fuel combustion. Close to its sources, acute exposures to NH 3 can result in visible foliar injury on vegetation. NH 3 is deposited rapidly within the first 4-5 km from its source. However, NH 3 is also converted in the atmosphere to fine particle NH 4 + (ammonium) aerosols that are a regional scale problem. Much of our current knowledge of the effects of NH 3 on higher plants is predominantly derived from studies conducted in Europe. Adverse effects on vegetation occur when the rate of foliar uptake of NH 3 is greater than the rate and capacity for in vivo detoxification by the plants. Most to least sensitive plant species to NH 3 are native vegetation > forests > agricultural crops. There are also a number of studies on N deposition and lichens, mosses and green algae. Direct cause and effect relationships in most of those cases (exceptions being those locations very close to point sources) are confounded by other environmental factors, particularly changes in the ambient SO 2 (sulfur dioxide) concentrations. In addition to direct foliar injury, adverse effects of NH 3 on higher plants include alterations in: growth and productivity, tissue content of nutrients and toxic elements, drought and frost tolerance, responses to insect pests and disease causing microorganisms (pathogens), development of beneficial root symbiotic or mycorrhizal associations and inter species competition or biodiversity. In all these cases, the joint effects of NH 3 with other air pollutants such as all-pervasive O 3 or

Treatment for GaSb surfaces using a sulphur blended (NH{sub 4}){sub 2}S/(NH{sub 4}){sub 2}SO{sub 4} solution

Energy Technology Data Exchange (ETDEWEB)

Murape, D.M., E-mail: Davison.Murape@nmmu.ac.za [Department of Physics, Nelson Mandela Metropolitan University, PO Box 77000, Port Elizabeth, 6031 (South Africa); Eassa, N.; Neethling, J.H. [Department of Physics, Nelson Mandela Metropolitan University, PO Box 77000, Port Elizabeth, 6031 (South Africa); Betz, R. [Department of Chemistry, Nelson Mandela Metropolitan University, PO Box 77000, Port Elizabeth, 6031 (South Africa); Coetsee, E.; Swart, H.C. [Department of Physics, University of the Free State, PO Box 339, Bloemfontein, 9300 (South Africa); Botha, J.R.; Venter, A. [Department of Physics, Nelson Mandela Metropolitan University, PO Box 77000, Port Elizabeth, 6031 (South Africa)

2012-07-01

A sulphur based chemical, [(NH{sub 4}){sub 2}S/(NH{sub 4}){sub 2}SO{sub 4}] to which S has been added, not previously reported for the treatment of (1 0 0) n-GaSb surfaces, is introduced and benchmarked against the commonly used passivants Na{sub 2}S{center_dot}9H{sub 2}O and (NH{sub 4}){sub 2}S. The surfaces of the treated material were studied by scanning electron microscopy (SEM), Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS). It has been found that the native oxides present on the GaSb surface are more effectively removed when treated with ([(NH{sub 4}){sub 2}S/(NH{sub 4}){sub 2}SO{sub 4}] + S) than with (NH{sub 4}){sub 2}S or Na{sub 2}S{center_dot}9H{sub 2}O, as evidenced by the ratio of the O{sub 506eV} to Sb{sub 457eV} AES peaks. XPS results reveal that Sb{sub 2}S{sub 3}/Sb{sub 2}S{sub 5} 'replaces' Sb{sub 2}O{sub 3}/Sb{sub 2}O{sub 5}, suggesting that sulphur atoms substitute oxygen atoms in Sb{sub 2}O{sub 3}/Sb{sub 2}O{sub 5} to form Sb-S. It seems sulphurization only partially removes Ga{sub 2}O{sub 3}. Treatment with ([(NH{sub 4}){sub 2}S/(NH{sub 4}){sub 2}SO{sub 4}] + S) also results in a noteworthy improvement in the current-voltage (I-V) characteristics of Au/n-GaSb Schottky contacts compared to those fabricated on as-received material.

PlayDoh and Toothpicks and Gummy Bears... OH MY, They're Models!

Science.gov (United States)

Kolandaivelu, K. P.; Wilson, M. W.; Glesener, G. B.

2017-12-01

Simple, everyday items found around the house are often used in geoscience lab activities. Gummy bears and silly putty can model the bending and breaking behaviour of rocks; shaking buildings during an earthquake can be modeled with some Jello, toothpicks, and marshmallows; PlayDoh can be used to demonstrate layers of sedimentary rocks; and even plumbing pipes filled with pebbles and playground sand become miniature physical models of aquifers. When performed correctly, these activities can help students visualize geoscience phenomena or increase students' motivation to pay attention in class, but how do these activities help students develop ways to think like a scientist? "Developing and using models" is one of the important science and engineering practices recommended in the Next Generation Science Standards (NGSS). In this presentation, we will demonstrate a variety of common geoscience lab activities using simple, everyday household items in order to describe ways instructors can help their students develop model-based reasoning skills. Specific areas of interest will be on identifying positive and negative attributes of a model, ways to evaluate the reliability of a model, and how a model can be revised to improve its outcome. We will also outline other kinds of models that can be generated from these lab activities, such as mathematical, graphical, and verbal models. Our goal is to encourage educators to focus more time on helping students develop model-based reasoning skills, which can be used in almost all aspects of everyday life.

Bulk gold catalyzed oxidation reactions of amines and isocyanides and iron porphyrin catalyzed N-H and O-H bond insertion/cyclization reactions of diamines and aminoalcohols

Energy Technology Data Exchange (ETDEWEB)

Klobukowski, Erik [Iowa State Univ., Ames, IA (United States)

2011-01-01

conditions, it was found that the oxidative dehydrogenation of dibenzylamine to Nbenzylidenebenzylamine, with N-methylmorpholine N-oxide (NMMO), was nearly quantitative (96%) within 24 h. However, the reaction with oxygen was much slower, with only a 52% yield of imine product over the same time period. Moreover, the rate of reaction was found to be influenced by the nature of the amine N-oxide. For example, the use of the weakly basic pyridine N-oxide (PyNO) led to an imine yield of only 6% after 24 h. A comparison of amine N-oxide and O2 was also examined in the oxidation of PhCH{sub 2}OH to PhCHO catalyzed by bulk gold. In this reaction, a 52% yield of the aldehyde was achieved when NMMO was used, while only a 7% product yield was afforded when O{sub 2} was the oxidant after 48 h. The bulk gold-catalyzed oxidative dehydrogenation of cyclic amines generates amidines, which upon treatment with Aerosil and water were found to undergo hydrolysis to produce lactams. Moreover, 5-, 6-, and 7-membered lactams could be prepared through a one-pot reaction of cyclic amines by treatment with oxygen, water, bulk gold, and Aerosil. This method is much more atom economical than industrial processes, does not require corrosive acids, and does not generate undesired byproducts. Additionally, the gold and Aerosil catalysts can be readily separated from the reaction mixture. The second project involved studying iron(III) tetraphenylporphyrin chloride, Fe(TPP)Cl, as a homogeneous catalyst for the generation of carbenes from diazo reagents and their reaction with heteroatom compounds. Fe(TPP)Cl, efficiently catalyzed the insertion of carbenes derived from methyl 2-phenyldiazoacetates into O-H bonds of aliphatic and aromatic alcohols. Fe(TPP)Cl was also found to be an effective catalyst for tandem N-H and O-H insertion/cyclization reactions when 1,2-diamines and 1,2-alcoholamines were treated with diazo reagents. This approach provides a one-pot process for synthesizing piperazinones and

Improved GaSb surfaces using a (NH{sub 4}){sub 2}S/(NH{sub 4}){sub 2}S0{sub 4} solution

Energy Technology Data Exchange (ETDEWEB)

Murape, D.M., E-mail: Davison.Murape@live.nmmu.ac.za [Department of Physics, Nelson Mandela Metropolitan University, PO Box 77000, Port Elizabeth 6031 (South Africa); Eassa, N.; Nyamhere, C.; Neethling, J.H. [Department of Physics, Nelson Mandela Metropolitan University, PO Box 77000, Port Elizabeth 6031 (South Africa); Betz, R. [Department of Chemistry, Nelson Mandela Metropolitan University, PO Box 77000, Port Elizabeth 6031 (South Africa); Coetsee, E.; Swart, H.C. [Department of Physics, University of the Free State, PO Box 339, Bloemfontein 9300 (South Africa); Botha, J.R.; Venter, A. [Department of Physics, Nelson Mandela Metropolitan University, PO Box 77000, Port Elizabeth 6031 (South Africa)

2012-05-15

Bulk (1 0 0) n-GaSb surfaces have been treated with a sulphur based solution ((NH{sub 4}){sub 2}S/(NH{sub 4}){sub 2}SO{sub 4}) to which sulphur has been added, not previously reported for the passivation of GaSb surfaces. Au/n-GaSb Schottky barrier diodes (SBDs) fabricated on the treated material show significant improvement compared to that of the similar SBDs on the as-received material as evidenced by the lower ideality factor (n), higher barrier height ({phi}{sub b}) and lower contact resistance obtained. Additionally, the reverse leakage current, although not saturating, has been reduced by almost an order of magnitude at -0.2 V. The sample surfaces were studied by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The native oxide, Sb-O, present on the as-received material is effectively removed on treating with ([(NH{sub 4}){sub 2}S/(NH{sub 4}){sub 2}SO{sub 4}]+S) and (NH{sub 4}){sub 2}S. Analysis of the as-received surface by XPS, prior to and after argon sputtering, suggests that the native oxide layer is {<=}8.5 nm.

Introgressive hybridization: brown bears as vectors for polar bear alleles.

Science.gov (United States)

Hailer, Frank

2015-03-01

The dynamics and consequences of introgression can inform about numerous evolutionary processes. Biologists have therefore long been interested in hybridization. One challenge, however, lies in the identification of nonadmixed genotypes that can serve as a baseline for accurate quantification of admixture. In this issue of Molecular Ecology, Cahill et al. (2015) analyse a genomic data set of 28 polar bears, eight brown bears and one American black bear. Polar bear alleles are found to be introgressed into brown bears not only near a previously identified admixture zone on the Alaskan Admiralty, Baranof and Chichagof (ABC) Islands, but also far into the North American mainland. Elegantly contrasting admixture levels at autosomal and X chromosomal markers, Cahill and colleagues infer that male-biased dispersal has spread these introgressed alleles away from the Late Pleistocene contact zone. Compared to a previous study on the ABC Island population in which an Alaskan brown bear served as a putatively admixture-free reference, Cahill et al. (2015) utilize a newly sequenced Swedish brown bear as admixture baseline. This approach reveals that brown bears have been impacted by introgression from polar bears to a larger extent (up to 8.8% of their genome), than previously known, including the bear that had previously served as admixture baseline. No evidence for introgression of brown bear into polar bear is found, which the authors argue could be a consequence of selection. Besides adding new exciting pieces to the puzzle of polar/brown bear evolutionary history, the study by Cahill and colleagues highlights that wildlife genomics is moving from analysing single genomes towards a landscape genomics approach. © 2015 John Wiley & Sons Ltd.

Abundances and implications of volatile-bearing species from evolved gas analysis of the Rocknest aeolian deposit, Gale Crater, Mars

Science.gov (United States)

Archer, Paul Douglas; Franz, Heather B.; Sutter, Brad; Arevalo, Ricardo D.; Coll, Patrice; Eigenbrode, Jennifer L.; Glavin, Daniel P.; Jones, John J.; Leshin, Laurie A.; Mahaffy, Paul R.; McAdam, Amy C.; McKay, Christopher P.; Ming, Douglas W.; Morris, Richard V.; Navarro-González, Rafael; Niles, Paul B.; Pavlov, Alex; Squyres, Steven W.; Stern, Jennifer C.; Steele, Andrew; Wray, James J.

2014-01-01

The Sample Analysis at Mars (SAM) instrument on the Mars Science Laboratory (MSL) rover Curiosity detected evolved gases during thermal analysis of soil samples from the Rocknest aeolian deposit in Gale Crater. Major species detected (in order of decreasing molar abundance) were H2O, SO2, CO2, and O2, all at the µmol level, with HCl, H2S, NH3, NO, and HCN present at the tens to hundreds of nmol level. We compute weight % numbers for the major gases evolved by assuming a likely source and calculate abundances between 0.5 and 3 wt.%. The evolution of these gases implies the presence of both oxidized (perchlorates) and reduced (sulfides or H-bearing) species as well as minerals formed under alkaline (carbonates) and possibly acidic (sulfates) conditions. Possible source phases in the Rocknest material are hydrated amorphous material, minor clay minerals, and hydrated perchlorate salts (all potential H2O sources), carbonates (CO2), perchlorates (O2 and HCl), and potential N-bearing materials (e.g., Martian nitrates, terrestrial or Martian nitrogenated organics, ammonium salts) that evolve NH3, NO, and/or HCN. We conclude that Rocknest materials are a physical mixture in chemical disequilibrium, consistent with aeolian mixing, and that although weathering is not extensive, it may be ongoing even under current Martian surface conditions.

Dissociation of NH3 and NH2D by high power CO2 laser radiation

International Nuclear Information System (INIS)

Jacobs, R.R.

1976-08-01

Multiquantum dissociation of polyatomics using intense CO 2 lasers resulting in isotopic enrichment has been demonstrated for several molecules. In this presentation, the possibility of selective dissociation of NH 3 and NH 2 D by high power laser radiation at 10 μm will be considered. Relevant work performed at the Lawrence Livermore Laboratory and elsewhere will be summarized. In this review, attention will be given to four distinct mechanisms that can play varying degrees of importance in such investigations. Discussion will deal with the usefulness of two-resonant-frequency molecular excitation, the role of buffer gases, and the need to monitor the yields into the ground and excited electronic states of the dissociated fragments

OH megamasers: dense gas & the infrared radiation field

Science.gov (United States)

Huang, Yong; Zhang, JiangShui; Liu, Wei; Xu, Jie

2018-06-01

To investigate possible factors related to OH megamaser formation (OH MM, L_{H2O}>10L_{⊙}), we compiled a large HCN sample from all well-sampled HCN measurements so far in local galaxies and identified with the OH MM, OH kilomasers (L_{H2O}gas and the dense gas, respectively), we found that OH MM galaxies tend to have stronger HCN emission and no obvious difference on CO luminosity exists between OH MM and non-OH MM. This implies that OH MM formation should be related to the dense molecular gas, instead of the low-density molecular gas. It can be also supported by other facts: (1) OH MMs are confirmed to have higher mean molecular gas density and higher dense gas fraction (L_{HCN}/L_{CO}) than non-OH MMs. (2) After taking the distance effect into account, the apparent maser luminosity is still correlated with the HCN luminosity, while no significant correlation can be found at all between the maser luminosity and the CO luminosity. (3) The OH kMs tend to have lower values than those of OH MMs, including the dense gas luminosity and the dense gas fraction. (4) From analysis of known data of another dense gas tracer HCO^+, similar results can also be obtained. However, from our analysis, the infrared radiation field can not be ruled out for the OH MM trigger, which was proposed by previous works on one small sample (Darling in ApJ 669:L9, 2007). On the contrary, the infrared radiation field should play one more important role. The dense gas (good tracers of the star formation) and its surrounding dust are heated by the ultra-violet (UV) radiation generated by the star formation and the heating of the high-density gas raises the emission of the molecules. The infrared radiation field produced by the re-radiation of the heated dust in turn serves for the pumping of the OH MM.

The nature of OH/IR stars

International Nuclear Information System (INIS)

Herman, J.

1983-01-01

In this work masers in evolved stars are studied, in particular the emission from the OH radical. The time variability of the OH masers was measured over a period of five years with the Dwingeloo Radio Telescope. These single-dish observations proved that most of the underlying stars are very long period variables, apparently a kind of extension of the well-known long period Mira variables. The mean OH fluxes and epochs were obtained as well as a confirmation of the radiative coupling between the maser and the star (by comparison with infrared data provided by other observers), the degree of saturation, and, most important of all, a determination of the linear dimensions of the circumstellar shells. Multi-element interferometer observations were made in order to study the spatial structure of OH masers. By combining the phase lag measurements and the spatial extent distances to individual stars could be determined with a high, unprecedented accuracy. Infrared broad-band photometry was done in the wavelength region from 3 μm to 20 μm, where most of the energy of these objects is radiated. The space density and galactic distribution of OH/IR stars are discussed and compared with the appearance of OH masers in the solar neighbourhood. (Auth.)

Intercomparison of OH and OH reactivity measurements in a high isoprene and low NO environment during the Southern Oxidant and Aerosol Study (SOAS)

Science.gov (United States)

Sanchez, Dianne; Jeong, Daun; Seco, Roger; Wrangham, Ian; Park, Jeong-Hoo; Brune, William H.; Koss, Abigail; Gilman, Jessica; de Gouw, Joost; Misztal, Pawel; Goldstein, Allen; Baumann, Karsten; Wennberg, Paul O.; Keutsch, Frank N.; Guenther, Alex; Kim, Saewung

2018-02-01

We intercompare OH and OH reactivity datasets from two different techniques, chemical ionization mass spectrometry (CIMS) and laser-induced fluorescence (LIF) in a high isoprene and low NO environment in a southeastern US forest during the Southern Oxidant and Aerosol Study (SOAS). An LIF instrument measured OH and OH reactivity at the top of a tower, a CIMS instrument measured OH at the top of the tower, and a CIMS based comparative reactivity method (CRM-CIMS) instrument deployed at the base of the tower measured OH reactivity. Averaged diel variations of OH and OH reactivity from these datasets agree within analytical uncertainty and correlations of LIF versus CIMS for OH and OH reactivity have slopes of 0.65 and 0.97, respectively. However, there are systematic differences between the measurement datasets. The CRM-CIMS measurements of OH reactivity were ∼16% lower than those by the LIF technique in the late afternoon. We speculate that it is caused by losses in the sampling line down to the CRM-CIMS instrument. On the other hand, we could not come up with a reasonable explanation for the difference in the LIF and CIMS OH datasets for early morning and late afternoon when OH is below 1 × 106 molecules cm-3. Nonetheless, results of this intercomparison exercise strengthen previous publications from the field site on OH concentrations and atmospheric reactivity.

Heterolytic cleavage of ammonia N-H bond by bifunctional activation in silica-grafted single site Ta(V) imido amido surface complex. Importance of the outer sphere NH3 assistance

KAUST Repository

Gouré, Eric

2011-01-01

Ammonia N-H bond is cleaved at room temperature by the silica-supported tantalum imido amido complex [(≡SiO)2Ta(NH)(-NH2)], 2, if excess ammonia is present, but requires 150 °C to achieve the same reaction if only one equivalent NH3 is added to 2. MAS solid-state 15N NMR and in situ IR spectroscopic studies of the reaction of either 15N or 2H labeled ammonia with 2 show that initial coordination of the ammonia is followed by scrambling of either 15N or 2H among ammonia, amido and imido groups. Density functional theory (DFT) calculations with a cluster model [{(μ-O)[(H3SiO) 2SiO]2}Ta(NH)(-NH2)(NH3)], 2 q·NH3, show that the intramolecular H transfer from Ta-NH2 to TaNH is ruled out, but the H transfers from the coordinated ammonia to the amido and imido groups have accessible energy barriers. The energy barrier for the ammonia N-H activation by the Ta-amido group is energetically preferred relative to the Ta-imido group. The importance of excess NH3 for getting full isotope scrambling is rationalized by an outer sphere assistance of ammonia acting as proton transfer agent, which equalizes the energy barriers for H transfer from coordinated ammonia to the amido and imido groups. In contrast, additional coordinated ammonia does not favor significantly the H transfer. These results rationalize the experimental conditions used. © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2011.

Antidepressants differentially related to 1,25-(OH)₂ vitamin D₃ and 25-(OH) vitamin D₃ in late-life depression.

Science.gov (United States)

Oude Voshaar, R C; Derks, W J; Comijs, H C; Schoevers, R A; de Borst, M H; Marijnissen, R M

2014-04-15

A low plasma 25-OH vitamin D3 level is a universal risk factor for a wide range of diseases and has also been implicated in late-life depression. It is currently unknown whether the biologically active form of vitamin D, that is, 1,25-(OH)2 vitamin D3, is also decreased in late-life depression, or whether vitamin D levels correlate with specific depression characteristics. We determined plasma 25-OH vitamin D3, 1,25-(OH)2 vitamin D3 and parathormone levels in 355 depressed older persons and 124 non-depressed comparison subjects (age 60 years). Psychopathology was established with the Composite International Diagnostic Interview 2.1, together with potential confounders and depression characteristics (severity, symptom profile, age of onset, recurrence, chronicity and antidepressant drug use). Adjusted for confounders, depressed patients had significantly lower levels of 25-OH vitamin D33 (Cohen's d =0.28 (95% confidence interval: 0.07-0.49), P=0.033) as well as 1,25-(OH)2 vitamin D3 (Cohen's d =0.48 (95% confidence interval: 0.27-0.70), Pdepression characteristics tested, only the use of tricyclic antidepressants (TCAs) was significantly correlated with lower 1,25-(OH)2 vitamin D3 levels (Cohen's d =0.86 (95% confidence interval: 0.53-1.19), Pprecursor 25-OH vitamin D3. As vitamin D levels were significantly lower after adjustment for confounders, vitamin D might have an aetiological role in late-life depression. Differences between depressed and non-depressed subjects were largest for the biologically active form of vitamin D. The differential impact of TCAs on 25-OH vitamin D3 and 1,25-(OH)2 vitamin D3 levels suggests modulation of 1-α-hydroxylase and/or 24-hydroxylase, which may in turn have clinical implications for biological ageing mechanisms in late-life depression.

Electron pairing analysis of the Fischer-type chromium-carbene complexes (CO){sub 5}Cr=C(X)R (X=H, OH, OCH{sub 3}, NH{sub 2}, NHCH{sub 3} and R=H, CH{sub 3}, CH=CH{sub 2}, Ph, C-CH )

Energy Technology Data Exchange (ETDEWEB)

Poater, Jordi; Cases, Montserrat; Fradera, Xavier; Duran, Miquel; Sola, Miquel

2003-10-15

The electron-pair density distributions of a series of 25 Fischer carbene complexes of the type (CO){sub 5}Cr=C(X)R (X=H, OH, OCH{sub 3}, NH{sub 2}, NHCH{sub 3} and R=H, CH{sub 3}, CH=CH{sub 2}, Ph, C-CH) are analyzed using the Atoms in Molecules theory. Localization and delocalization indices are used to characterize the electron pairing taking place in the Cr=C---X moiety in these complexes. Electron delocalization between the Cr and C atoms and between the C atom and the X group are related to the {pi}-donor strength of the X group and the degree of back-donation between the chromium pentacarbonyl and the carbene fragments. The results obtained with the Atoms in Molecules theory complement those obtained in a previous study by means of energy and charge decomposition analyses. Electron delocalization between the Cr atom and the X group is consistent with the hypothesis of a weak 3-center 4-electron bonding interaction in the Cr=C-X group of atoms. Except for X=H, {delta}(Cr,X) increases with the decrease of the {pi}-donor character of the X group.

Hydrogen Bearing Material in the Lunar Exosphere

Science.gov (United States)

Hurley, D.; Benna, M.; Colaprete, A.; Retherford, K. D.; Cook, J. C.; Elphic, R. C.; Farrell, W. M.; Killen, R. M.; Sarantos, M.

2015-12-01

We report on observations of water and its daughters in the lunar exosphere. Data from LADEE NMS, LADEE UVS, and LRO LAMP indicating the presence of H, H2, OH, and H2O are presented in terms of their relationship to external drivers. These observations point to the roles of solar wind and micrometeoroids in the source and release of hydrogen-bearing atoms and molecules in the exosphere. In particular, the implantation of H via solar wind is found to be the largest contributor to H2 in the moon's exosphere. However, the spatial distribution is more consistent with a release mechanism centered on the morning hemisphere. Thus the data are consistent with H2 created through a 2-step process involving the implantation of solar wind and subsequent release by micrometeoroids. This accounts for >12% of the solar wind H budget, leaving day water cycle occurring on the Moon.

Fulltext PDF

Indian Academy of Sciences (India)

IAS Admin

of Creation: Camphor to Vitamin B. 12 . Page 603: Para 2, Line10, '33' should be read as '35'. ... OMe. H. 1. Li, NH3, ButOH, THF. 2. H+. 39. O. N. H. H. 1. NH2OH. 2. NaNO2, AcOH. O. O. O. N. H. H. O. N. MsO. COOMe. H. Polystyrene sulphonic acid. MeOH, 170°C, 2h. O. N. H. O. COOMe. H. 44. O. O. MeO. MeOH. 43. N.

The hydrogen bond between N-H or O-H and organic fluorine: favourable yes, competitive no.

Science.gov (United States)

Taylor, Robin

2017-06-01

A study was made of X-H...F-C interactions (X = N or O) in small-molecule crystal structures. It was primarily based on 6728 structures containing X-H and C-F and no atom heavier than chlorine. Of the 28 451 C-F moieties in these structures, 1051 interact with X-H groups. However, over three-quarters of these interactions are either the weaker components of bifurcated hydrogen bonds (so likely to be incidental contacts) or occur in structures where there is a clear insufficiency of good hydrogen-bond acceptors such as oxygen, nitrogen or halide. In structures where good acceptors are entirely absent, there is about a 2 in 3 chance that a given X-H group will donate to fluorine. Viable alternatives are X-H...π hydrogen bonds (especially to electron-rich aromatics) and dihydrogen bonds. The average H...F distances of X-H...F-C interactions are significantly shorter for CR 3 F (R = C or H) and Csp 2 -F acceptors than for CRF 3 . The X-H...F angle distribution is consistent with a weak energetic preference for linearity, but that of H...F-C suggests a flat energy profile in the range 100-180°. X-H...F-C interactions are more likely when the acceptor is Csp 2 -F or CR 3 F, and when the donor is C-NH 2 . They also occur significantly more often in structures containing tertiary alcohols or solvent molecules, or with Z' > 1, i.e. when there may be unusual packing problems. It is extremely rare to find X-H...F-C interactions in structures where there are several unused good acceptors. When it does happen, there is often a clear reason, e.g. awkwardly shaped molecules whose packing isolates a donor group from the good acceptors.

Experimental and theoretical understanding of the gas phase oxidation of atmospheric amides with OH radicals: kinetics, products, and mechanisms.

Science.gov (United States)

Borduas, Nadine; da Silva, Gabriel; Murphy, Jennifer G; Abbatt, Jonathan P D

2015-05-14

Atmospheric amides have primary and secondary sources and are present in ambient air at low pptv levels. To better assess the fate of amides in the atmosphere, the room temperature (298 ± 3 K) rate coefficients of five different amides with OH radicals were determined in a 1 m(3) smog chamber using online proton-transfer-reaction mass spectrometry (PTR-MS). Formamide, the simplest amide, has a rate coefficient of (4.44 ± 0.46) × 10(-12) cm(3) molec(-1) s(-1) against OH, translating to an atmospheric lifetime of ∼1 day. N-methylformamide, N-methylacetamide and propanamide, alkyl versions of formamide, have rate coefficients of (10.1 ± 0.6) × 10(-12), (5.42 ± 0.19) × 10(-12), and (1.78 ± 0.43) × 10(-12) cm(3) molec(-1) s(-1), respectively. Acetamide was also investigated, but due to its slow oxidation kinetics, we report a range of (0.4-1.1) × 10(-12) cm(3) molec(-1) s(-1) for its rate coefficient with OH radicals. Oxidation products were monitored and quantified and their time traces were fitted using a simple kinetic box model. To further probe the mechanism, ab initio calculations are used to identify the initial radical products of the amide reactions with OH. Our results indicate that N-H abstractions are negligible in all cases, in contrast to what is predicted by structure-activity relationships. Instead, the reactions proceed via C-H abstraction from alkyl groups and from formyl C(O)-H bonds when available. The latter process leads to radicals that can readily react with O2 to form isocyanates, explaining the detection of toxic compounds such as isocyanic acid (HNCO) and methyl isocyanate (CH3NCO). These contaminants of significant interest are primary oxidation products in the photochemical oxidation of formamide and N-methylformamide, respectively.

Effects of atmospheric ammonia (NH3) on terrestrial vegetation: a review.

Science.gov (United States)

Krupa, S V

2003-01-01

At the global scale, among all N (nitrogen) species in the atmosphere and their deposition on to terrestrial vegetation and other receptors, NH3 (ammonia) is considered to be the foremost. The major sources for atmospheric NH3 are agricultural activities and animal feedlot operations, followed by biomass burning (including forest fires) and to a lesser extent fossil fuel combustion. Close to its sources, acute exposures to NH3 can result in visible foliar injury on vegetation. NH3 is deposited rapidly within the first 4-5 km from its source. However, NH3 is also converted in the atmosphere to fine particle NH4+ (ammonium) aerosols that are a regional scale problem. Much of our current knowledge of the effects of NH3 on higher plants is predominantly derived from studies conducted in Europe. Adverse effects on vegetation occur when the rate of foliar uptake of NH3 is greater than the rate and capacity for in vivo detoxification by the plants. Most to least sensitive plant species to NH3 are native vegetation > forests > agricultural crops. There are also a number of studies on N deposition and lichens, mosses and green algae. Direct cause and effect relationships in most of those cases (exceptions being those locations very close to point sources) are confounded by other environmental factors, particularly changes in the ambient SO2 (sulfur dioxide) concentrations. In addition to direct foliar injury, adverse effects of NH3 on higher plants include alterations in: growth and productivity, tissue content of nutrients and toxic elements, drought and frost tolerance, responses to insect pests and disease causing microorganisms (pathogens), development of beneficial root symbiotic or mycorrhizal associations and inter species competition or biodiversity. In all these cases, the joint effects of NH3 with other air pollutants such as all-pervasive O3 or increasing CO2 concentrations are poorly understood. While NH3 uptake in higher plants occurs through the shoots, NH4

OH radiation from the interstellar cloud medium

Energy Technology Data Exchange (ETDEWEB)

Nguyen-Q-Rieu,; Winnberg, A [Max-Planck-Institut fuer Radioastronomie, Bonn (F.R. Germany); Guibert, J [Observatoire de Paris, Section de Meudon, 92 (France); Lepine, J R.D. [Universidade Mackenzie, Sao Paulo (Brazil). Centro de Radio-Astronomia et Astrofisica; Johansson, L E.B. [Rymdobservatoriet, Onsala (Sweden); Goss, W M [Commonwealth Scientific and Industrial Research Organization, Epping (Australia). Div. of Radiophysics

1976-02-01

We have detected OH in the direction of about 50% of the continuum sources investigated. The OH abundance is one order of magnitude less than usually found in dust clouds. Most of the OH features have HI counterparts. This suggests that the OH radiation arises from the HI interstellar cold clouds. Our observations allowed in some cases the determination of the excitation temperatures in all four lines. A pumping model involving far-infrared radiation and collisions with neutral and charged particles has been proposed. It explains the observed excitation temperatures.

A Low Temperature Infrared Study Of Deuterated NH4VO3

Science.gov (United States)

de Waal, D.; Heyns, A. M.

1989-12-01

The existence of (NH4)2V6016 as an intermediate in the thermal decomposition of NH4V03 to V205 has been confirmed by vibrational spectroscopy, resulting in the following reaction in an open systeml: NH4VO3 1 bar, air, 50-200°C/(1) (NH4)2v6o16 1 bar, air, ca.360°C/(2) V205 The kinetics of reaction (1) was studied by means of Raman spectroscopy, and structural information on NH4V03 and (N114)V60 16 was required to obtain an accurate description of the reaction mechanism2. Information on the site symmetry of an ammonium ion and hydrogen bonding in a crystal can be obtained by considering the infrared spectra of isotopically dilute NH3D+ ions in the lattice at liquid nitrogen temperatures3, especially as the position of hydrogen atoms in (NHO2V6016 could not be determined by X-ray methods.

Application procedures and analysis examples of the SIE ASME-NH program

International Nuclear Information System (INIS)

Kim, Seok Hoon; Koo, G. H.; Kim, J. B.

2010-12-01

In this report, the design rule of the ASME-NH Code was briefly summarized and the application procedures of SIE ASME-NH program were analysed, the analysis examples were described. The SIE ASME-NH program was developed according to the ASME Code Section III Subsection NH rules to perform the primary stress limits, the accumulated inelastic strain limits and the creep fatigue damage evaluations in the structural design of nuclear power plants operating with high temperatures over creep temperature at normal operating conditions. In the analysis examples, the benchmark problem for the high temperature reactor vessel which was discussed in the SIE ASME-NH user's seminar was described. Also, the preliminary structural analysis of an Advanced Burner Test Reactor internal structure was described. Considering the load combinations of the various cycle types submitted from significant operating conditions, the integrity of a reactor internal structure was reviewed according to the stress and strain limits of the ASME-NH rules and the analysis and evaluation results were summarized

CO2 Absorption and Magnesium Carbonate Precipitation in MgCl2–NH3–NH4Cl Solutions: Implications for Carbon Capture and Storage

Directory of Open Access Journals (Sweden)

Chen Zhu

2017-09-01

Full Text Available CO2 absorption and carbonate precipitation are the two core processes controlling the reaction rate and path of CO2 mineral sequestration. Whereas previous studies have focused on testing reactive crystallization and precipitation kinetics, much less attention has been paid to absorption, the key process determining the removal efficiency of CO2. In this study, adopting a novel wetted wall column reactor, we systematically explore the rates and mechanisms of carbon transformation from CO2 gas to carbonates in MgCl2–NH3–NH4Cl solutions. We find that reactive diffusion in liquid film of the wetted wall column is the rate-limiting step of CO2 absorption when proceeding chiefly through interactions between CO2(aq and NH3(aq. We further quantified the reaction kinetic constant of the CO2–NH3 reaction. Our results indicate that higher initial concentration of NH4Cl ( ≥ 2 mol · L − 1 leads to the precipitation of roguinite [ ( NH 4 2 Mg ( CO 3 2 · 4 H 2 O ], while nesquehonite appears to be the dominant Mg-carbonate without NH4Cl addition. We also noticed dypingite formation via phase transformation in hot water. This study provides new insight into the reaction kinetics of CO2 mineral carbonation that indicates the potential of this technique for future application to industrial-scale CO2 sequestration.

Methylene-bis[(aminomethyl)phosphinic acids]: synthesis, acid-base and coordination properties.

Science.gov (United States)

David, Tomáš; Procházková, Soňa; Havlíčková, Jana; Kotek, Jan; Kubíček, Vojtěch; Hermann, Petr; Lukeš, Ivan

2013-02-21

Three symmetrical methylene-bis[(aminomethyl)phosphinic acids] bearing different substituents on the central carbon atom, (NH(2)CH(2))PO(2)H-C(R(1))(R(2))-PO(2)H(CH(2)NH(2)) where R(1) = OH, R(2) = Me (H(2)L(1)), R(1) = OH, R(2) = Ph (H(2)L(2)) and R(1),R(2) = H (H(2)L(3)), were synthesized. Acid-base and complexing properties of the ligands were studied in solution as well as in the solid state. The ligands show unusually high basicity of the nitrogen atoms (log K(1) = 9.5-10, log K(2) = 8.5-9) if compared with simple (aminomethyl)phosphinic acids and, consequently, high stability constants of the complexes with studied divalent metal ions. The study showed the important role of the hydroxo group attached to the central carbon atom of the geminal bis(phosphinate) moiety. Deprotonation of the hydroxo group yields the alcoholate anion which tends to play the role of a bridging ligand and induces formation of polynuclear complexes. Solid-state structures of complexes [H(2)N=C(NH(2))(2)][Cu(2)(H(-1)L(2))(2)]CO(3)·10H(2)O and Li(2)[Co(4)(H(-1)L(1))(3)(OH)]·17.5H(2)O were determined by X-ray diffraction. The complexes show unexpected geometries forming dinuclear and cubane-like structures, respectively. The dinuclear copper(II) complex contains a bridging μ(2)-alcoholate group with the (-)O-P(=O)-CH(2)-NH(2) fragments of each ligand molecule chelated to the different central ion. In the cubane cobalt(II) complex, one μ(3)-hydroxide and three μ(3)-alcoholate anions are located in the cube vertices and both phosphinate groups of one ligand molecule are chelating the same cobalt(II) ion while each of its amino groups are bound to different neighbouring metal ions. All such three metal ions are bridged by the alcoholate group of a given ligand.

EcoBears

DEFF Research Database (Denmark)

Nielsen, Nick; Pedersen, Sandra Bleuenn; Sørensen, Jens Ager

2015-01-01

In this paper, we introduce the EcoBears concept that aims to augment household appliances with functional and aesthetic features to promote their "use'' and "longevity of use'' to prevent their disposal. The EcoBears also aim to support the communication of environmental issues in the home setting....... We present our initial design and implementation of the EcoBears that consist of two bear modules (a mother and her cub). We also present our preliminary concept validations and lessons learned to be considered for future directions....

THE KINETICS OF NH(4)+ AND NO3(-) UPTAKE BY DOUGLAS-FIR FROM SINGLE N-SOLUTIONS AND FROM SOLUTIONS CONTAINING BOTH NH(4)+ AND NO3(-)

NARCIS (Netherlands)

KAMMINGAVANWIJK, C; PRINS, HBA

The kinetics of NH4+ and NO3- uptake in young Douglas fir trees (Pseudotsuga menziesii [Mirb.] Franco) were studied in solutions, containing either one or both N species. Using solutions containing a single N species, the V(max) of NH4+ uptake was higher than that of NO3- uptake. The K(m) of NH4+

Topologically identical, but geometrically isomeric layers in hydrous α-, β-Rb[UO2(AsO3OH)(AsO2(OH)2)]·H2O and anhydrous Rb[UO2(AsO3OH)(AsO2(OH)2)

Science.gov (United States)

Yu, Na; Klepov, Vladislav V.; Villa, Eric M.; Bosbach, Dirk; Suleimanov, Evgeny V.; Depmeier, Wulf; Albrecht-Schmitt, Thomas E.; Alekseev, Evgeny V.

2014-07-01

The hydrothermal reaction of uranyl nitrate with rubidium nitrate and arsenic (III) oxide results in the formation of polymorphic α- and β-Rb[UO2(AsO3OH)(AsO2(OH)2)]·H2O (α-, β-RbUAs) and the anhydrous phase Rb[UO2(AsO3OH)(AsO2(OH)2)] (RbUAs). These phases were structurally, chemically and spectroscopically characterized. The structures of all three compounds are based upon topologically identical, but geometrically isomeric layers. The layers are linked with each other by means of the Rb cations and hydrogen bonding. Dehydration experiments demonstrate that water deintercalation from hydrous α- and β-RbUAs yields anhydrous RbUAs via topotactic reactions.

Atmospheric NH3 as plant nutrient: A case study with Brassica oleracea

International Nuclear Information System (INIS)

Castro, Ana; Stulen, Ineke; De Kok, Luit J.

2008-01-01

Nutrient-sufficient and nitrate- or sulfate-deprived plants of Brassica oleracea L. were exposed to 4 μl l -1 NH 3 (2.8 mg m -3 ), and effects on biomass production and allocation, N-compounds and root morphology investigated. Nitrate-deprived plants were able to transfer to atmospheric NH 3 as nitrogen source, but biomass allocation in favor of the root was not changed by exposure to NH 3 . NH 3 reduced the difference in total root length between nitrate-sufficient and nitrate-deprived plants, and increased the specific root length in the latter. The internal N status, therefore, might be involved in controlling root length in B. oleracea. Root surface area, volume and diameter were unaffected by both nitrate deprivation and NH 3 exposure. In sulfate-deprived plants an inhibitory effect of NH 3 on root morphological parameters was observed. These plants, therefore, might be more susceptible to atmospheric NH 3 than nitrate-deprived plants. The relevance of the present data under field conditions is discussed. - Atmospheric NH 3 can serve as sole N source for Brassica oleracea, but does not change root biomass allocation in nitrate-deprived plants

13N-NH3 PET in the diagnosis of astrocytomas: preliminary result

International Nuclear Information System (INIS)

Zhang Xiangsong; He Zuoxiang; Tang Anwu

2004-01-01

Objective: To evaluate the feasibility of diagnosing the astrocytoma with 13N-NH3 PET imaging. Methods 13N-NH3 and 18F-fluorodeoxyglucose (FDG) PET imaging were performed in seven cases of astrocytomas including 3 anteoperative astrocytomas, 2 recurrent astrocytomas, 2 brain injury or necrosis after the operation and radiotherapy. The radioactivity ratios of the tumor and normal white matter (T/WM) were calculated. Results: The tumor lesions in 3 anteoperative astrocytomas and 2 recurrent astrocytomas all uptake 13N-NH3. The average T/WM on 13N-NH3 images was 1.82±0.21, and T/WM on 13N-NH3 and 18F-FDG images were 1.98 and 0.97 for one case with grade 1 astrocytoma. 13N-NH3 and 18F-FDG PET imaging both showed decreased uptake in 2 brain injury or necrosis after the operation and radiotherapy of astrocytomas. Conclusions: 13N-NH3 was uptaken in astrocytomas. 13N-NH3 can be useful in the diagnosis of astrocytoma, and potentially improve diagnostic accuracy of astrocytoma, especially in low-grade astrocytoma. (authors)

13N-NH3 PET in the diagnosis of astrocytomas: preliminary result

International Nuclear Information System (INIS)

Zhang Xiangsong; He Zuoxiang; Tang Anwu

2004-01-01

Objective: To evaluate the feasibility of diagnosing the astrocytoma with 13N-NH3 PET imaging. Methods: 13N-NH3 and 18F-fluorodeoxyglucose (FDG) PET imaging were performed in seven cases of astrocytomas including 3 anteoperative astrocytomas, 2 recurrent astrocytomas, 2 brain injury or necrosis after the operation and radiotherapy. The radioactivity ratios of the tumor and normal white matter (T/WM) were calculated. Results: The tumor lesions in 3 anteoperative astrocytomas and 2 recurrent astrocytomas all uptake 13N-NH3 .The average T/WM on 13N-NH3 images was 1.82±0.21, and T/WM on 13N-NH3 and 18F-FDG images were 1.98 and 0.97 for one case with grade 1 astrocytoma. 13N-NH3 and 18F-FDG PET imaging both showed decreased uptake in 2 brain injury or necrosis after the operation and radiotherapy of astrocytomas. Conclusions: 13N-NH3 was uptaken in astrocytomas. 13N-NH3 can be useful in the diagnosis of astrocytoma, and potentially improve diagnostic accuracy of astrocytoma, especially in low-grade astrocytoma. (authors)

Stable isotopes to detect food-conditioned bears and to evaluate human-bear management

Science.gov (United States)

Hopkins, John B.; Koch, Paul L.; Schwartz, Charles C.; Ferguson, Jake M.; Greenleaf, Schuyler S.; Kalinowski, Steven T.

2012-01-01

We used genetic and stable isotope analysis of hair from free-ranging black bears (Ursus americanus) in Yosemite National Park, California, USA to: 1) identify bears that consume human food, 2) estimate the diets of these bears, and 3) evaluate the Yosemite human–bear management program. Specifically, we analyzed the isotopic composition of hair from bears known a priori to be food-conditioned or non-food-conditioned and used these data to predict whether bears with an unknown management status were food-conditioned (FC) or non-food-conditioned (NFC). We used a stable isotope mixing model to estimate the proportional contribution of natural foods (plants and animals) versus human food in the diets of FC bears. We then used results from both analyses to evaluate proactive (population-level) and reactive (individual-level) human–bear management, and discussed new metrics to evaluate the overall human–bear management program in Yosemite. Our results indicated that 19 out of 145 (13%) unknown bears sampled from 2005 to 2007 were food-conditioned. The proportion of human food in the diets of known FC bears likely declined from 2001–2003 to 2005–2007, suggesting proactive management was successful in reducing the amount of human food available to bears. In contrast, reactive management was not successful in changing the management status of known FC bears to NFC bears, or in reducing the contribution of human food to the diets of FC bears. Nine known FC bears were recaptured on 14 occasions from 2001 to 2007; all bears were classified as FC during subsequent recaptures, and human–bear management did not reduce the amount of human food in the diets of FC bears. Based on our results, we suggest Yosemite continue implementing proactive human–bear management, reevaluate reactive management, and consider removing problem bears (those involved in repeated bear incidents) from the population.

Enhancing anaerobic digestion of waste activated sludge by the combined use of NaOH and Mg(OH)2: Performance evaluation and mechanism study.

Science.gov (United States)

Huang, Cheng; Lai, Jia; Sun, Xiuyun; Li, Jiansheng; Shen, Jinyou; Han, Weiqing; Wang, Lianjun

2016-11-01

In this study, the combination treatment of NaOH and Mg(OH)2 was applied to anaerobic digestion of waste activated sludge (WAS) for simultaneously enhancement of volatile fatty acids (VFAs) production, nutrients removal and sludge dewaterability. The maximum VFAs production (461mg COD/g VSS) was obtained at the NaOH/Mg(OH)2 ratio of 75:25, which was much higher than that of the blank or sole NaOH. Moreover, nutrients removal and sludge dewaterability were improved by the combined using of NaOH and Mg(OH)2. Mechanism investigations revealed that the presence of Mg(OH)2 could maintain alkaline environment, which contributed to inhibit the activity of methanogens. Also, the bridging between Mg(2+) and extracellular polymeric substances (EPS) plays an important role in the solubilization and dewatering of sludge. High-throughput sequencing analysis demonstrated that the abundance of bacteria involved in sludge hydrolysis and VFAs accumulation was greatly enriched with the mixtures of NaOH and Mg(OH)2. Copyright © 2016 Elsevier Ltd. All rights reserved.

Photofragment imaging study of the CH2CCH2OH radical intermediate of the OH+allene reaction

International Nuclear Information System (INIS)

Raman, Arjun S.; Justine Bell, M.; Lau, K.-C.; Butler, Laurie J.

2007-01-01

These velocity map imaging experiments characterize the photolytic generation of one of the two radical intermediates formed when OH reacts via an addition mechanism with allene. The CH 2 CCH 2 OH radical intermediate is generated photolytically from the photodissociation of 2-chloro-2-propen-1-ol at 193 nm. Detecting the Cl atoms using [2+1] resonance-enhanced multiphoton ionization evidences an isotropic angular distribution for the Cl+CH 2 CCH 2 OH photofragments, a spin-orbit branching ratio for Cl( 2 P 1/2 ):Cl( 2 P 3/2 ) of 0.28, and a bimodal recoil kinetic energy distribution. Conservation of momentum and energy allows us to determine from this data the internal energy distribution of the nascent CH 2 CCH 2 OH radical cofragment. To assess the possible subsequent decomposition pathways of this highly vibrationally excited radical intermediate, we include electronic structure calculations at the G3//B3LYP level of theory. They predict the isomerization and dissociation transition states en route from the initial CH 2 CCH 2 OH radical intermediate to the three most important product channels for the OH+allene reaction expected from this radical intermediate: formaldehyde+C 2 H 3 , H+acrolein, and ethene+CHO. We also calculate the intermediates and transition states en route from the other radical adduct, formed by addition of the OH to the center carbon of allene, to the ketene+CH 3 product channel. We compare our results to a previous theoretical study of the O+allyl reaction conducted at the CBS-QB3 level of theory, as the two reactions include several common intermediates

Photofragment imaging study of the CH2CCH2OH radical intermediate of the OH +allene reaction

Science.gov (United States)

Raman, Arjun S.; Justine Bell, M.; Lau, Kai-Chung; Butler, Laurie J.

2007-10-01

These velocity map imaging experiments characterize the photolytic generation of one of the two radical intermediates formed when OH reacts via an addition mechanism with allene. The CH2CCH2OH radical intermediate is generated photolytically from the photodissociation of 2-chloro-2-propen-1-ol at 193nm. Detecting the Cl atoms using [2+1] resonance-enhanced multiphoton ionization evidences an isotropic angular distribution for the Cl +CH2CCH2OH photofragments, a spin-orbit branching ratio for Cl(P1/22):Cl(P3/22) of 0.28, and a bimodal recoil kinetic energy distribution. Conservation of momentum and energy allows us to determine from this data the internal energy distribution of the nascent CH2CCH2OH radical cofragment. To assess the possible subsequent decomposition pathways of this highly vibrationally excited radical intermediate, we include electronic structure calculations at the G3//B3LYP level of theory. They predict the isomerization and dissociation transition states en route from the initial CH2CCH2OH radical intermediate to the three most important product channels for the OH +allene reaction expected from this radical intermediate: formaldehyde+C2H3, H +acrolein, and ethene+CHO. We also calculate the intermediates and transition states en route from the other radical adduct, formed by addition of the OH to the center carbon of allene, to the ketene+CH3 product channel. We compare our results to a previous theoretical study of the O +allyl reaction conducted at the CBS-QB3 level of theory, as the two reactions include several common intermediates.

State Space Formulation of Nonlinear Vibration Responses Collected from a Dynamic Rotor-Bearing System: An Extension of Bearing Diagnostics to Bearing Prognostics.

Science.gov (United States)

Tse, Peter W; Wang, Dong

2017-02-14

Bearings are widely used in various industries to support rotating shafts. Their failures accelerate failures of other adjacent components and may cause unexpected machine breakdowns. In recent years, nonlinear vibration responses collected from a dynamic rotor-bearing system have been widely analyzed for bearing diagnostics. Numerous methods have been proposed to identify different bearing faults. However, these methods are unable to predict the future health conditions of bearings. To extend bearing diagnostics to bearing prognostics, this paper reports the design of a state space formulation of nonlinear vibration responses collected from a dynamic rotor-bearing system in order to intelligently predict bearing remaining useful life (RUL). Firstly, analyses of nonlinear vibration responses were conducted to construct a bearing health indicator (BHI) so as to assess the current bearing health condition. Secondly, a state space model of the BHI was developed to mathematically track the health evolution of the BHI. Thirdly, unscented particle filtering was used to predict bearing RUL. Lastly, a new bearing acceleration life testing setup was designed to collect natural bearing degradation data, which were used to validate the effectiveness of the proposed bearing prognostic method. Results show that the prediction accuracy of the proposed bearing prognostic method is promising and the proposed bearing prognostic method is able to reflect future bearing health conditions.

State Space Formulation of Nonlinear Vibration Responses Collected from a Dynamic Rotor-Bearing System: An Extension of Bearing Diagnostics to Bearing Prognostics

Directory of Open Access Journals (Sweden)

Peter W. Tse

2017-02-01

Full Text Available Bearings are widely used in various industries to support rotating shafts. Their failures accelerate failures of other adjacent components and may cause unexpected machine breakdowns. In recent years, nonlinear vibration responses collected from a dynamic rotor-bearing system have been widely analyzed for bearing diagnostics. Numerous methods have been proposed to identify different bearing faults. However, these methods are unable to predict the future health conditions of bearings. To extend bearing diagnostics to bearing prognostics, this paper reports the design of a state space formulation of nonlinear vibration responses collected from a dynamic rotor-bearing system in order to intelligently predict bearing remaining useful life (RUL. Firstly, analyses of nonlinear vibration responses were conducted to construct a bearing health indicator (BHI so as to assess the current bearing health condition. Secondly, a state space model of the BHI was developed to mathematically track the health evolution of the BHI. Thirdly, unscented particle filtering was used to predict bearing RUL. Lastly, a new bearing acceleration life testing setup was designed to collect natural bearing degradation data, which were used to validate the effectiveness of the proposed bearing prognostic method. Results show that the prediction accuracy of the proposed bearing prognostic method is promising and the proposed bearing prognostic method is able to reflect future bearing health conditions.

Dehydriding reaction of Mg(NH2)2-LiH system under hydrogen pressure

International Nuclear Information System (INIS)

Aoki, M.; Noritake, T.; Kitahara, G.; Nakamori, Y.; Towata, S.; Orimo, S.

2007-01-01

The dehydriding and structural properties of the 3Mg(NH 2 ) 2 + 12LiH system under hydrogen pressure were investigated using the pressure-composition (p-c) isotherm measurement and X-ray diffraction (XRD) analysis. Two distinct regions, a plateau region and a sloping region, can be seen on the p-c isotherms and the amount of the desorbed hydrogen at 523 K was 4.9 mass%. The enthalpy of hydrogenation calculated using a van't Hoff plot was -46 kJ/mol H 2 . The dehydriding reaction was proposed for the 3Mg(NH 2 ) 2 + 12LiH system based on the obtained p-c isotherms and XRD profiles and chemical valences of Li, Mg, N, and H. In the plateau region on the p-c isotherm, Mg(NH 2 ) 2 , Li 4 Mg 3 (NH 2 ) 2 (NH) 4 (tetragonal), and LiH phases coexist and the molar ratio of the Li 4 Mg 3 (NH 2 ) 2 (NH) 4 phase increases (while those of Mg(NH 2 ) 2 and LiH phases decrease) with the amount of the desorbed hydrogen. On the other hand, the mixture of Li 4+x Mg 3 (NH 2 ) 2-x (NH) 4+x + (8-x)LiH (0 ≤ x ≤ 2) is formed and the lattice volume of the Li 4+x Mg 3 (NH 2 ) 2-x (NH) 4+x phase continuously increases with the amount of the desorbed hydrogen in the sloping region on the p-c isotherm

Process-based modelling of NH3 exchange with grazed grasslands

Science.gov (United States)

Móring, Andrea; Vieno, Massimo; Doherty, Ruth M.; Milford, Celia; Nemitz, Eiko; Twigg, Marsailidh M.; Horváth, László; Sutton, Mark A.

2017-09-01

In this study the GAG model, a process-based ammonia (NH3) emission model for urine patches, was extended and applied for the field scale. The new model (GAG_field) was tested over two modelling periods, for which micrometeorological NH3 flux data were available. Acknowledging uncertainties in the measurements, the model was able to simulate the main features of the observed fluxes. The temporal evolution of the simulated NH3 exchange flux was found to be dominated by NH3 emission from the urine patches, offset by simultaneous NH3 deposition to areas of the field not affected by urine. The simulations show how NH3 fluxes over a grazed field in a given day can be affected by urine patches deposited several days earlier, linked to the interaction of volatilization processes with soil pH dynamics. Sensitivity analysis showed that GAG_field was more sensitive to soil buffering capacity (β), field capacity (θfc) and permanent wilting point (θpwp) than the patch-scale model. The reason for these different sensitivities is dual. Firstly, the difference originates from the different scales. Secondly, the difference can be explained by the different initial soil pH and physical properties, which determine the maximum volume of urine that can be stored in the NH3 source layer. It was found that in the case of urine patches with a higher initial soil pH and higher initial soil water content, the sensitivity of NH3 exchange to β was stronger. Also, in the case of a higher initial soil water content, NH3 exchange was more sensitive to the changes in θfc and θpwp. The sensitivity analysis showed that the nitrogen content of urine (cN) is associated with high uncertainty in the simulated fluxes. However, model experiments based on cN values randomized from an estimated statistical distribution indicated that this uncertainty is considerably smaller in practice. Finally, GAG_field was tested with a constant soil pH of 7.5. The variation of NH3 fluxes simulated in this way

Methanol oxidation in a flow reactor: Implications for the branching ratio of the CH3OH+OH reaction

DEFF Research Database (Denmark)

Rasmussen, Christian Lund; Wassard, K.H.; Dam-Johansen, Kim

2008-01-01

The oxidation of methanol in a flow reactor has been studied experimentally under diluted, fuel-lean conditions at 650-1350 K, over a wide range of O-2 concentrations (1%-16%), and with and without the presence of nitric oxide. The reaction is initiated above 900 K, with the oxidation rate...... decreasing slightly with the increasing O-2 concentration. Addition of NO results in a mutually promoted oxidation of CH3OH and NO in the 750-1100 K range. The experimental results are interpreted in terms of a revised chemical kinetic model. Owing to the high sensitivity of the mutual sensitization of CH3OH...... and NO oxidation to the partitioning of CH3O and CH2OH, the CH3OH + OH branching fraction could be estimated as alpha = 0.10 +/- 0.05 at 990 K. Combined with low-temperature measurements, this value implies a branching fraction that is largely independent of temperature. It is in good agreement with recent...

Measurements of total OH reactivity during PROPHET-AMOS 2016

Science.gov (United States)

Rickly, P.; Sakowski, J.; Bottorff, B.; Lew, M.; Stevens, P. S.; Sklaveniti, S.; Locoge, N.; Dusanter, S.

2017-12-01

As one of the main oxidant in the atmosphere, the hydroxyl radical (OH) initiates the oxidation of volatile organic compounds that can lead to the formation of ozone and secondary organic aerosols. Understanding both the sources and sinks of OH is therefore important to address issues related to air quality and climate change. Measurements of total OH reactivity can provide an important test of our understanding of the OH radical budget. Recent measurements of total reactivity in many environments have been greater than calculated based on the measured concentration of VOCs, suggesting that important OH sinks in these environments are not well characterized. Measurements of total OH reactivity were performed in a forested environment during the PROPHET - AMOS field campaign (Program for Research on Oxidants: PHotochemisty, Emissions, and Transport - Atmospheric Measurements of Oxidants in Summer) using the Comparative Reactivity Method (CRM) and the Total OH Loss Rate Method (TOHLM). The site is characterized by large emissions of isoprene and monoterpenes and low anthropogenic influence. Measurements of total OH reactivity using these two techniques agree to within their respective uncertainties, giving confidence in the measured OH reactivity. In addition, measurements of trace gases (VOCs, NOx, O3) were used to perform a comprehensive apportionment of OH sinks. These measurements are used in a chemical model using the Master Chemical Mechanism to calculate the expected OH reactivity. The results will be compared to previous measurements of total OH reactivity at this site.

Comparison of Alignment Correction Angles Between Fixed-Bearing and Mobile-Bearing UKA.

Science.gov (United States)

Inoue, Atsuo; Arai, Yuji; Nakagawa, Shuji; Inoue, Hiroaki; Yamazoe, Shoichi; Kubo, Toshikazu

2016-01-01

Good outcomes have been reported with both fixed-bearing and mobile-bearing unicompartmental knee arthroplasty (UKA). However, overcorrected alignment could induce the progression of arthritis on the non-arthroplasty side. Changes of limb alignment after UKA with both types of bearings (fixed bearing: 24 knees, mobile bearing: 28 knees) were investigated. The mean difference between the preoperative standing femoral-tibial angle (FTA) and postoperative standing FTA was significantly larger in mobile bearing UKA group. In fixed-bearing UKA, there must be some laxity in MCL tension so that a 2-mm tension gauge can be inserted. In mobile-bearing UKA, appropriate MCL tension is needed to prevent bearing dislocation. This difference in MCL tension may have caused the difference in the correction angle between the groups. Copyright © 2016 Elsevier Inc. All rights reserved.

First principles study of NH3 molecular adsorption on LiH (100) surfaces

International Nuclear Information System (INIS)

Lu Xiaoxia; Chen Yuhong; Dong Xiao

2012-01-01

The adsorption of NH 3 on LiH (100) crystal surfaces was studied by first principles method. The preferred adsorption sites, adsorption energy, dissociation energy and electronic structure of the LiH (100)/NH 3 systems were calculated separately. It is found that chemical adsorption happened mainly when NH 3 molecules are on the LiH (100) crystal surfaces. When NH 3 is adsorbed on the Li top site, NH 2 is formed on the LiH (100) crystal surfaces after loss of H atom, the calculated adsorption energy, 0.511 eV, belongs to strong chemical adsorption, then the interaction is strongest. The interaction between NH 2 and the neighboring Li, H are ionic. The covalent bonds are formed between N and H atoms in NH 2 . One H 2 molecule is formed by another H atom in NH 3 and H atom from LiH (100) crystal sur- faces. The covalent bonds are formed between H and H atoms in H 2 . (authors)

Infrared spectra of the ammonium ion in ammonium metavanadate NH 4VO 3

Science.gov (United States)

de Waal, D.; Heyns, A. M.; Range, K.-J.; Eglmeier, C.

The ND stretching modes of isotopically dilute NH 3D + ions in NH 4VO 3 are in agreement with the predicted splitting into C s, C s and C1(2) components under C s site symmetry for the NH +4 ion. The three bands observed represent the three NH bonding distances in the crystal, and the position, shape and low temperature behaviour of each band confirms the existence of two types of hydrogen bonding in NH 4VO 3. The low temperature infrared modes of NH +4 and ND +4 in NH 4VO 3 and ND 4VO 3, respectively, can be assigned under space group Pbcm. Temperature dependence of these modes also reflects the presence of both normal and bifurcated hydrogen bonds in NH 4VO 3.

Investigation on thermal evaporated CH3NH3PbI3 thin films

Directory of Open Access Journals (Sweden)

Youzhen Li

2015-09-01

Full Text Available CH3NH3I, PbI2 and CH3NH3PbI3 films were fabricated by evaporation and characterized with X-ray Photoelectron Spectroscopy (XPS and X-ray diffraction (XRD. The XPS results indicate that the PbI2 and CH3NH3PbI3 films are more uniform and stable than the CH3NH3I film. The atomic ratio of the CH3NH3I, PbI2 and CH3NH3PbI3 films are C:N:I=1.00:1.01:0.70, Pb:I= 1.00:1.91 and C: N: Pb: I = 1.29:1.07:1.00:2.94, respectively. The atomic ratio of CH3NH3PbI3 is very close to that of the ideal perovskite. Small angle x-ray diffraction results demonstrate that the as evaporated CH3NH3PbI3 film is crystalline. The valence band maximum (VBM and work function (WF of the CH3NH3PbI3 film are about 0.85eV and 4.86eV, respectively.

SURVEY OBSERVATIONS OF A POSSIBLE GLYCINE PRECURSOR, METHANIMINE (CH{sub 2}NH)

Energy Technology Data Exchange (ETDEWEB)

Suzuki, Taiki; Ohishi, Masatoshi; Hirota, Tomoya; Saito, Masao [Department of Astronomy, the Graduate University for Advanced Studies (SOKENDAI), Osawa 2-21-1, Mitaka, Tokyo 181-8588 (Japan); Majumdar, Liton; Wakelam, Valentine, E-mail: taiki.suzuki@nao.ac.jp [Univ. Bordeaux, LAB, UMR 5804, F-33270, Floirac (France)

2016-07-01

We conducted survey observations of a glycine precursor, methanimine, or methylenimine (CH{sub 2}NH), with the Nobeyama Radio Observatory 45 m telescope and the Sub-Millimeter Radio telescope toward 12 high-mass and two low-mass star-forming regions in order to increase the number of known CH{sub 2}NH sources and to better understand the characteristics of CH{sub 2}NH sources. As a result of our survey, CH{sub 2}NH was detected in eight sources, including four new sources. The estimated fractional abundances were ∼10{sup −8} in Orion KL and G10.47+0.03, while they were ∼10{sup −9} toward the other sources. Our hydrogen recombination line and past studies suggest that CH{sub 2}NH-rich sources have less (this mean not so evolved) evolved H ii regions. The lower destruction rates from UV flux from the central star would contribute to the high CH{sub 2}NH abundances toward CH{sub 2}NH-rich sources. Our gas-grain chemical simulations suggest that CH{sub 2}NH is mostly formed in the gas phase by neutral–neutral reactions, rather than being the product of thermal evaporation from dust surfaces.

Urban NH3 levels and sources in six major Spanish cities.

Science.gov (United States)

Reche, Cristina; Viana, Mar; Karanasiou, Angeliki; Cusack, Michael; Alastuey, Andrés; Artiñano, Begoña; Revuelta, M Aranzazu; López-Mahía, Purificación; Blanco-Heras, Gustavo; Rodríguez, Sergio; Sánchez de la Campa, Ana M; Fernández-Camacho, Rocío; González-Castanedo, Yolanda; Mantilla, Enrique; Tang, Y Sim; Querol, Xavier

2015-01-01

A detailed spatial and temporal assessment of urban NH3 levels and potential emission sources was made with passive samplers in six major Spanish cities (Barcelona, Madrid, A Coruña, Huelva, Santa Cruz de Tenerife and Valencia). Measurements were conducted during two different periods (winter-autumn and spring-summer) in each city. Barcelona showed the clearest spatial pattern, with the highest concentrations in the old city centre, an area characterised by a high population density and a dense urban architecture. The variability in NH3 concentrations did not follow a common seasonal pattern across the different cities. The relationship of urban NH3 with SO2 and NOX allowed concluding on the causes responsible for the variations in NH3 levels between measurement periods observed in Barcelona, Huelva and Madrid. However, the factors governing the variations in A Coruña, Valencia and Santa Cruz de Tenerife are still not fully understood. This study identified a broad variability in NH3 concentrations at the city-scale, and it confirms that NH3 sources in Spanish urban environments are vehicular traffic, biological sources (e.g. garbage containers), wastewater treatment plants, solid waste treatment plants and industry. The importance of NH3 monitoring in urban environments relies on its role as a precursor of secondary inorganic species and therefore PMX. Further research should be addressed in order to establish criteria to develop and implement mitigation strategies for cities, and to include urban NH3 sources in the emission inventories. Copyright © 2014 Elsevier Ltd. All rights reserved.

Low energy electron attachment to cyanamide (NH{sub 2}CN)

Energy Technology Data Exchange (ETDEWEB)

Tanzer, Katrin; Denifl, Stephan, E-mail: Andrzej.Pelc@poczta.umcs.lublin.pl, E-mail: Stephan.Denifl@uibk.ac.at [Institut für Ionenphysik und Angewandte Physik, Leopold Franzens Universität Innsbruck, Technikerstr. 25, 6020 Innsbruck (Austria); Pelc, Andrzej, E-mail: Andrzej.Pelc@poczta.umcs.lublin.pl, E-mail: Stephan.Denifl@uibk.ac.at [Mass Spectrometry Department, Institute of Physics, Marie Curie-Sklodowska University, Pl. M. C.-Sklodowskiej 1, 20-031 Lublin (Poland); Huber, Stefan E. [Institut für Ionenphysik und Angewandte Physik, Leopold Franzens Universität Innsbruck, Technikerstr. 25, 6020 Innsbruck (Austria); Lehrstuhl für Theoretische Chemie, Technische Universität München, Lichtenbergstr. 4, 85747 Garching (Germany); Czupyt, Z. [Ion Microprobe Facility Micro-area Analysis Laboratory, Polish Geological Institute–National Research Institute, Rakowiecka 4, 00-975 Warszawa (Poland)

2015-01-21

Cyanamide (NH{sub 2}CN) is a molecule relevant for interstellar chemistry and the chemical evolution of life. In the present investigation, dissociative electron attachment to NH{sub 2}CN has been studied in a crossed electron–molecular beams experiment in the electron energy range from about 0 eV to 14 eV. The following anionic species were detected: NHCN{sup −}, NCN{sup −}, CN{sup −}, NH{sub 2}{sup −}, NH{sup −}, and CH{sub 2}{sup −}. The anion formation proceeds within two broad electron energy regions, one between about 0.5 and 4.5 eV and a second between 4.5 and 12 eV. A discussion of possible reaction channels for all measured negative ions is provided. The experimental results are compared with calculations of the thermochemical thresholds of the anions observed. For the dehydrogenated parent anion, we explain the deviation between the experimental appearance energy of the anion with the calculated corresponding reaction threshold by electron attachment to the isomeric form of NH{sub 2}CN—carbodiimide.

Brief Exposures to the Taste of Ethanol (EtOH) and Quinine Promote Subsequent Acceptance of EtOH in a Paradigm that Minimizes Postingestive Consequences.

Science.gov (United States)

Loney, Gregory C; Meyer, Paul J

2018-03-01

Aversion to the orosensory properties of concentrated ethanol (EtOH) solutions is often cited as a primary barrier to initiation of drinking and may contribute to abstention. These aversive properties include gustatory processes which encompass both bitter-like taste qualities and trigeminal-mediated irritation. Chronic intermittent EtOH access (CIA) results in substantial and persistent increases in EtOH consumption, but the degree to which this facilitation involves sensory responding to EtOH and other bitter stimuli is currently undetermined. Long-Evans rats were given brief-access licking tests designed to examine the immediate, taste-guided assessment of the palatability of EtOH and quinine solutions. Rats were assessed once in a naïve state and again following previous brief-access exposure, or following 4 weeks of CIA. The relationship between the sensitivity to the aversive orosensory properties of EtOH and quinine following EtOH access and the impact of antecedent quinine exposure on the acceptance of EtOH were determined in 2 parallel studies. Both brief access to EtOH and 4-week CIA resulted in substantial rightward shifts in the concentration-response function of brief-access EtOH licking, indicating that EtOH exposure increased acceptance of the taste of EtOH. The initial sensitivity to the aversive orosensory properties of EtOH and quinine was positively correlated in naïve rats, such that rats that were initially more accepting of quinine were also more accepting of EtOH. Rats that sampled quinine immediately prior to tasting EtOH exhibited successive positive contrast in that they were more accepting of highly concentrated EtOH, relative to a water-control group. Increased EtOH acceptance following exposure is, at least in part, facilitated by a decrease in its aversive sensory properties. Both long- and short-term access increase the palatability of the taste of EtOH in brief-access licking tests. Moreover, the sensitivity to the bitterness of

Mechanism of the self-condensation of GlcNH₂

DEFF Research Database (Denmark)

Jia, Lingyu; Liu, Xingchen; Qiao, Yan

2017-01-01

A combined experimental and computational study on the imidazolium ionic liquid-promoted conversion of d-Glucosamine (GlcNH2) to deoxyfructosazine (DOF) and fructosazine (FZ) was performed. The pathways for the formation of DOF and FZ via self-condensation of GlcNH2 were investigated by in situ13C...... NMR using site-selectively 13C-labeled GlcNH2. The structural characterization of the reactive species by ESI–MS spectrometry combined with NMR analysis of [13C-1]GlcNH2 indicates that the first carbon (C-1) of GlcNH2 maps onto the corresponding ring carbons of the intermediate, called...... dihydrofructosazine, indicates that both pathways are plausible and that the pathway to DOF is thermodynamically more favorable than that to FZ. The theoretical results are consistent with the experimental observations, and therefore, a detailed and reasonable reaction mechanism was proposed...

Infrared and Raman spectroscopic characterization of the silicate mineral olmiite CaMn2+[SiO3(OH)](OH) - implications for the molecular structure

Science.gov (United States)

Frost, Ray L.; Scholz, Ricardo; López, Andrés; Xi, Yunfei; Granja, Amanda; Žigovečki Gobac, Željka; Lima, Rosa Malena Fernandes

2013-12-01

We have studied the mineral olmiite CaMn[SiO3(OH)](OH) which forms a series with its calcium analogue poldervaartite CaCa[SiO3(OH)](OH) using a range of techniques including scanning electron microscopy, thermogravimetric analysis, Raman and infrared spectroscopy. Chemical analysis shows the mineral is pure and contains only calcium and manganese in the formula. Thermogravimetric analysis proves the mineral decomposes at 502 °C with a mass loss of 8.8% compared with the theoretical mass loss of 8.737%. A strong Raman band at 853 cm-1 is assigned to the SiO stretching vibration of the SiO3(OH) units. Two Raman bands at 914 and 953 cm-1 are attributed to the antisymmetric vibrations. Two intense Raman bands observed at 3511 and 3550 cm-1 are assigned to the OH stretching vibration of the SiO3(OH) units. The observation of multiple OH bands supports the concept of the non-equivalence of the OH units. Vibrational spectroscopy enables a detailed assessment of the molecular structure of olmiite.

Kinetics of abiotic nitrous oxide production via oxidation of hydroxylamine by particulate metals in seawater

Science.gov (United States)

Cavazos, A. R.; Taillefert, M.; Glass, J. B.

2016-12-01

The oceans are a significant of nitrous oxide (N2O) to the atmosphere. Current models of global oceanic N2­O flux focus on microbial N2O cycling and often ignore abiotic reactions, such as the thermodynamically favorable oxidation of the nitrification intermediate hydroxylamine (NH2OH) by Mn(IV) or Fe(III). At circumneutral pH, NH2OH oxidation is more thermodynamically favorable via Mn(IV) than Fe(III) reduction. We characterized the kinetics of NH2OH oxidation in synthetic ocean water at pH 5.1-8.8 using microsensor electrodes to measure real-time N2O production. N2O production rates and yield were greater when NH2OH was oxidized by Mn(IV) than Fe(III). Accordingly, the reduction of Mn(IV) was first order with respect to NH2OH whereas the reduction of Fe(III) was zero order with respect to NH2OH. Interestingly, the order of the reaction with respect to Mn(IV) appears to be negative whereas the reaction is second order with respect to Fe(III). The inverse order with respect to Mn(IV) may be due to the aggregation of particles in seawater, which decreases their surface area and changes their reactivity. Finally, the reaction is first order with respect to protons with Fe(III) as the oxidant but zero order with Mn(IV). The stronger effect of the pH on the reaction with Fe(III) as the oxidant compared to Mn(IV) reflects the stoichiometry of these two reactions, as each mole of N2O produced by Fe(III) reduction consumes eight protons while each mole of N2O produced with Mn(IV) as the oxidant requires only four protons. Our data show that abiotic NH2OH oxidation by Mn(IV) or Fe(III) particles may represent a significant source of N2O in seawater. These findings suggest that abiotic N2O production in marine waters may be significant in areas of the oceans where particulate metals originating from aerosols, dust, or rivers may react with NH2OH released from ammonia-oxidizing microorganisms.

Transcriptomic and physiological analysis of common duckweed Lemna minor responses to NH4(+) toxicity.

Science.gov (United States)

Wang, Wenguo; Li, Rui; Zhu, Qili; Tang, Xiaoyu; Zhao, Qi

2016-04-18

Plants can suffer ammonium (NH4 (+)) toxicity, particularly when NH4 (+) is supplied as the sole nitrogen source. However, our knowledge about the underlying mechanisms of NH4 (+) toxicity is still largely unknown. Lemna minor, a model duckweed species, can grow well in high NH4 (+) environment but to some extent can also suffer toxic effects. The transcriptomic and physiological analysis of L. minor responding to high NH4 (+) may provide us some interesting and useful information not only in toxic processes, but also in tolerance mechanisms. The L. minor cultured in the Hoagland solution were used as the control (NC), and in two NH4 (+) concentrations (NH4 (+) was the sole nitrogen source), 84 mg/L (A84) and 840 mg/L (A840) were used as stress treatments. The NH4 (+) toxicity could inhibit the growth of L. minor. Reactive oxygen species (ROS) and cell death were studied using stained fronds under toxic levels of NH4 (+). The malondialdehyde content and the activities of superoxide dismutase and peroxidase increased from NC to A840, rather than catalase and ascorbate peroxidase. A total of 6.62G nucleotides were generated from the three distinct libraries. A total of 14,207 differentially expressed genes (DEGs) among 70,728 unigenes were obtained. All the DEGs could be clustered into 7 profiles. Most DEGs were down-regulated under NH4 (+) toxicity. The genes required for lignin biosynthesis in phenylpropanoid biosynthesis pathway were up-regulated. ROS oxidative-related genes and programmed cell death (PCD)-related genes were also analyzed and indicated oxidative damage and PCD occurring under NH4 (+) toxicity. The first large transcriptome study in L. minor responses to NH4 (+) toxicity was reported in this work. NH4 (+) toxicity could induce ROS accumulation that causes oxidative damage and thus induce cell death in L. minor. The antioxidant enzyme system was activated under NH4 (+) toxicity for ROS scavenging. The phenylpropanoid pathway was stimulated under

OH Solar Radiometer

Data.gov (United States)

National Aeronautics and Space Administration — The abundance of the hydroxyl radical, OH, determines the lifetime of methane and its global warming potential. Despite the growing importance of methane and the...

DETOKSIFIKASI HIDROLISAT ASAM DARI UBI KAYU UNTUK PRODUKSI BIOETANOL

Directory of Open Access Journals (Sweden)

Yuana Susmiati

2016-11-01

Full Text Available The production of bioetanol by using acid hydrolisis method resulted the formation of compounds which can destructed the fermentation process, such as HMF or furfural, thus it needs detoxification process to erase or decrease it. Detoxification process is done by adding alkali in to hidrolisat before it is used as fermentation substrat. Alkali compound which is usually used are Ca(OH2 or NH4OH. This research is conducted to compare ethanol rendement resulted from the detoxification process, and also to decide the most optimal detoxification that can be done to produce the best etanol rendement. The study is done by using distinct treatmentof catalist, that are Ca(OH2 dan NH4OH as well as the stirring/mixing time, which are control, 15, 30 and 45 minutes during detoxification process. Based on the result of the study, it can be concluded that etanol rendement resulted from hydrolisat which is detoxificated by using catalyst NH4OH is higher than the one which use catalyst Ca(OH2. Acid hydrolisat detoxification method from cassava in order to produce an optimal bioetanol is by using catalist NH4OH with free stirring time(less than 15 minutes

A search for OH emission from symbiotic stars

International Nuclear Information System (INIS)

Norris, R.P.; Haynes, R.F.; Wright, A.E.

1984-01-01

A search was made for OH maser emission from a sample of 16 symbiotic stars. This sample was selected on the basis of infrared optical depth and variability, so that the stars within it have circumstellar shells similar to those seen in OH/IR and OH/Mira stars. There were no significant detections, except for one unassociated background source, and it is concluded that the presence of a hot binary companion inhibits any possible OH maser action

A review of bear farming and bear trade in Lao People's Democratic Republic

Directory of Open Access Journals (Sweden)

E. Livingstone

2018-01-01

Full Text Available This study reviews the bear farming industry in Lao PDR with the objective of documenting the current number of commercial bear facilities (i.e. captive bear facilities judged to be trading in bear bile and/or bears and bear parts and the number of bears contained within these facilities, noting changes since it was last examined between 2000 and 2012 by Livingstone and Shepherd (2014. We surveyed all known commercial bear facilities and searched for previously unrecorded facilities. We compared our records with Livingstone and Shepherd (2014 and corrected some duplicate records from their study. In 2017, we recorded seven commercial facilities; four dedicated bear farms, and three tiger farms that were reportedly also keeping bears. We found that between 2012 and 2017 the recorded number of dedicated bear farms reduced by two, and the recorded number of tiger farms also keeping bears increased by one. Within the same period, the total number of captive bears among all facilities in Lao PDR hardly changed (+one, but the number of bears within each facility did. The northern facilities, owned by ethnic Chinese, have expanded since 2012, and central and southern facilities have downsized or closed. While bear farming appears to be downsizing in Lao PDR overall, efforts to phase it out are undermined by the expansion of foreign owned facilities in the north, within Special and Specific Economic Zones that largely cater to a Chinese market, and where the Lao government's efforts to enforce laws and protect wildlife appear to be lacking. Closing the facilities in the north will require political will and decisive law enforcement. Keywords: Bear farms, Bear bile, Gall bladder, Urso-deoxycholic acid, Bear bile extraction facilities, Lao PDR, Ursus thibetanus

Herschel Observations of Extraordinary Sources: Analysi sof the HIFI 1.2 THz Wide Spectral Survey toward Orion KL II. Chemical Implications

Science.gov (United States)

Crockett, N. R.; Bergin, E. A.; Neill, J. L.; Favre, C.; Blake, G. A.; Herbst, E.; Anderson, D. E.; Hassel, G. E.

2015-06-01

We present chemical implications arising from spectral models fit to the Herschel/HIFI spectral survey toward the Orion Kleinmann-Low nebula (Orion KL). We focus our discussion on the eight complex organics detected within the HIFI survey utilizing a novel technique to identify those molecules emitting in the hottest gas. In particular, we find the complex nitrogen bearing species CH3CN, C2H3CN, C2H5CN, and NH2CHO systematically trace hotter gas than the oxygen bearing organics CH3OH, C2H5OH, CH3OCH3, and CH3OCHO, which do not contain nitrogen. If these complex species form predominantly on grain surfaces, this may indicate N-bearing organics are more difficult to remove from grain surfaces than O-bearing species. Another possibility is that hot (Tkin ∼ 300 K) gas phase chemistry naturally produces higher complex cyanide abundances while suppressing the formation of O-bearing complex organics. We compare our derived rotation temperatures and molecular abundances to chemical models, which include gas-phase and grain surface pathways. Abundances for a majority of the detected complex organics can be reproduced over timescales ≳105 years, with several species being underpredicted by less than 3σ. Derived rotation temperatures for most organics, furthermore, agree reasonably well with the predicted temperatures at peak abundance. We also find that sulfur bearing molecules that also contain oxygen (i.e., SO, SO2, and OCS) tend to probe the hottest gas toward Orion KL, indicating the formation pathways for these species are most efficient at high temperatures. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.

Formation of carbonato and hydroxo complexes in the reaction of platinum anticancer drugs with carbonate.

Science.gov (United States)

Di Pasqua, Anthony J; Centerwall, Corey R; Kerwood, Deborah J; Dabrowiak, James C

2009-02-02

The second-generation Pt(II) anticancer drug carboplatin is here shown to react with carbonate, which is present in blood, interstitial fluid, cytosol, and culture medium, to produce platinum-carbonato and -hydroxo complexes. Using [(1)H-(15)N] HSQC NMR and (15)N-labeled carboplatin, we observe that cis-[Pt(CBDCA-O)(OH)(NH(3))(2)](-), cis-[Pt(OH)(2)(NH(3))(2)], cis-[Pt(CO(3))(OH)(NH(3))(2)](-), and what may be cis-[Pt(CO(3))(NH(3))(2)] are produced when 1 is allowed to react in 23.8 mM carbonate buffer. When (15)N-labeled carboplatin is allowed to react in 0.5 M carbonate buffer, these platinum species, as well as other hydroxo and carbonato species, some of which may be dinuclear complexes, are produced. Furthermore, we show that the carbonato species cis-[Pt(CO(3))(OH)(NH(3))(2)](-) is also produced when cisplatin is allowed to react in carbonate buffer. The study outlines the conditions under which carboplatin and cisplatin form carbonato and aqua/hydroxo species in carbonate media.

Thermodynamic modeling of NH_3-CO_2-SO_2-K_2SO_4-H_2O system for combined CO_2 and SO_2 capture using aqueous NH_3

International Nuclear Information System (INIS)

Qi, Guojie; Wang, Shujuan

2017-01-01

Highlights: • A new application of aqueous NH_3 based combined CO_2 and SO_2 process was proposed. • A thermodynamic model simulated the heat of absorption and the K_2SO_4 precipitation. • The CO_2 content can be regenerated in a stripper with lower heat of desorption. • The SO_2 content can be removed by K_2SO_4 precipitation from the lean NH_3 solvent. - Abstract: A new application of aqueous NH_3 based post-combustion CO_2 and SO_2 combined capture process was proposed to simultaneously capture CO_2 and SO_2, and remove sulfite by solid (K_2SO_4) precipitation method. The thermodynamic model of the NH_3-CO_2-SO_2-K_2SO_4-H_2O system for the combined CO_2 and SO_2 capture process was developed and validated in this work to analyze the heat of CO_2 and SO_2 absorption in the NH_3-CO_2-SO_2-H_2O system, and the K_2SO_4 precipitation characteristics in the NH_3-CO_2-SO_2-K_2SO_4-H_2O system. The average heat of CO_2 absorption in the NH_3-CO_2-H_2O system at 40 °C is around −73 kJ/mol CO_2 in 2.5 wt% NH_3 with CO_2 loading between 0.2 and 0.5 C/N. The average heat of SO_2 absorption in the NH_3-SO_2-H_2O system at 40 °C is around −120 kJ/mol SO_2 in 2.5 wt% NH_3 with SO_2 loading between 0 and 0.5 S/N. The average heat of CO_2 absorption in the NH_3-CO_2-SO_2-H_2O system at 40 °C is 77, 68, and 58 kJ/mol CO_2 in 2.5 wt% NH_3 with CO_2 loading between 0.2 and 0.5 C/N, when SO_2 loading is 0, 0.1, 0.2 S/N, respectively. The solubility of K_2SO_4 increases with temperature, CO_2 and SO_2 loadings, but decreases with NH_3 concentration in the CO_2 and SO_2 loaded aqueous NH_3. The thermodynamic evaluation indicates that the combined CO_2 and SO_2 capture process could employ the typical absorption/regeneration process to simultaneously capture CO_2 and SO_2 in an absorber, thermally desorb CO_2 in a stripper, and feasibly remove sulfite (oxidized to sulfate) content by precipitating K_2SO_4 from the lean NH_3 solvent after the lean/rich heat exchanger.

Young planetary nebula with OH molecules - NGC 6302

International Nuclear Information System (INIS)

Payne, H.E.; Phillips, J.A.; Terzian, Y.

1988-01-01

The results of a sensitive survey of planetary nebulae in all four ground-state OH lines are reported. The results confirm that evolved planetary nebulas are not OH sources in general. However, one interesting object was not detected: an OH 1612 MHz maser in the young planetary nebula NGC 6302. This nebula may be in a brief evolutionary stage, similar to the young and compact planetary nebula Vy 2-2, where OH has already been detected. In addition, the results of further observations of NGC 6302 are reported, including VLA observations of the 1612 MHz line and continuum emission and detections of rotationally excited OH lines at 5-cm wavelength in absorption. 28 references

OH detection by Ford Motor Company

Science.gov (United States)

Wang, Charles C.

1986-12-01

Two different methods for detection of OH are presented: a low pressure flow cell system and a frequency modulation absorption measurement. Using conventional absorption spectroscopy, detection limits were quoted of 1,000,000 OH molecules per cu cm using a 30-minute averaging time on the ground, and a 3-hour averaging time in the air for present apparatus in use. With the addition of FM spectroscopy at 1 GHz, a double-beam machine should permit detectable absorption of and an OH limit of 100,000 per cu cm in a 30-minute averaging time. In the low pressure system on which experiments are ongoing nonexponential time behavior was observed after the decay had progressed to about 0.3 of its original level; this was attributed to ion emission in the photomultiplier. A flame source with OH present at high concentration levels was used as a calibration. It was estimated that within the sampling chamber, 400,000 OH could be measured. With a factor-of-2 loss at the sampling orifice, this means detectability of 5 to 8 x 100,000 cu cm at the present time. This could be reduced by a factor of 2 in one hour averaging time; improvements in laser bandwidth and energy should provide another factor of 2 in sensitivity.

Molecular phylogeny and SNP variation of polar bears (Ursus maritimus), brown bears (U. arctos), and black bears (U. americanus) derived from genome sequences.

Science.gov (United States)

Cronin, Matthew A; Rincon, Gonzalo; Meredith, Robert W; MacNeil, Michael D; Islas-Trejo, Alma; Cánovas, Angela; Medrano, Juan F

2014-01-01

We assessed the relationships of polar bears (Ursus maritimus), brown bears (U. arctos), and black bears (U. americanus) with high throughput genomic sequencing data with an average coverage of 25× for each species. A total of 1.4 billion 100-bp paired-end reads were assembled using the polar bear and annotated giant panda (Ailuropoda melanoleuca) genome sequences as references. We identified 13.8 million single nucleotide polymorphisms (SNP) in the 3 species aligned to the polar bear genome. These data indicate that polar bears and brown bears share more SNP with each other than either does with black bears. Concatenation and coalescence-based analysis of consensus sequences of approximately 1 million base pairs of ultraconserved elements in the nuclear genome resulted in a phylogeny with black bears as the sister group to brown and polar bears, and all brown bears are in a separate clade from polar bears. Genotypes for 162 SNP loci of 336 bears from Alaska and Montana showed that the species are genetically differentiated and there is geographic population structure of brown and black bears but not polar bears.

Metal-organic coordination architectures of tetrazole heterocycle ligands bearing acetate groups: Synthesis, characterization and magnetic properties

Science.gov (United States)

Hu, Bo-Wen; Zheng, Xiang-Yu; Ding, Cheng

2015-12-01

Two new coordination complexes with tetrazole heterocycle ligands bearing acetate groups, [Co(L)2]n (1) and [Co3(L)4(N3)2·2MeOH]n (2) (L=tetrazole-1-acetate) have been synthesized and structurally characterized. Single crystal structure analysis shows that the cobalt-complex 1 has the 3D 3,6-connected (42.6)2(44.62.88.10)-ant topology. By introducing azide in this system, complex 2 forms the 2D network containing the [Co3] units. And the magnetic properties of 1 and 2 have been studied.

Photostriction of CH3NH3PbBr3 Perovskite Crystals

KAUST Repository

Wei, Tzu-Chiao

2017-07-17

Organic-inorganic hybrid perovskite materials exhibit a variety of physical properties. Pronounced coupling between phonon, organic cations, and the inorganic framework suggest that these materials exhibit strong light-matter interactions. The photoinduced strain of CH3 NH3 PbBr3 is investigated using high-resolution and contactless in situ Raman spectroscopy. Under illumination, the material exhibits large blue shifts in its Raman spectra that indicate significant structural deformations (i.e., photostriction). From these shifts, the photostrictive coefficient of CH3 NH3 PbBr3 is calculated as 2.08 × 10-8 m2 W-1 at room temperature under visible light illumination. The significant photostriction of CH3 NH3 PbBr3 is attributed to a combination of the photovoltaic effect and translational symmetry loss of the molecular configuration via strong translation-rotation coupling. Unlike CH3 NH3 PbI3 , it is noted that the photostriction of CH3 NH3 PbBr3 is extremely stable, demonstrating no signs of optical decay for at least 30 d. These results suggest the potential of CH3 NH3 PbBr3 for applications in next-generation optical micro-electromechanical devices.

oh sport

Directory of Open Access Journals (Sweden)

Elena Grigoryeva

2017-03-01

Sports play a very important and diverse role in the present-day global culture. On the occasion of the 105th anniversary of Coubertin’s Ode we would like to wish sports to return to the main words of the Ode and to correspond with them: “Oh sport, you are the peace”.

Effects of atmospheric ammonia (NH{sub 3}) on terrestrial vegetation: a review

Energy Technology Data Exchange (ETDEWEB)

Krupa, S.V

2003-07-01

A review of atmospheric ammonia (NH{sub 3}) and ammonium (NH{sub 4}{sup +}) deposition and their effects on plants. - At the global scale, among all N (nitrogen) species in the atmosphere and their deposition on to terrestrial vegetation and other receptors, NH{sub 3} (ammonia) is considered to be the foremost. The major sources for atmospheric NH{sub 3} are agricultural activities and animal feedlot operations, followed by biomass burning (including forest fires) and to a lesser extent fossil fuel combustion. Close to its sources, acute exposures to NH{sub 3} can result in visible foliar injury on vegetation. NH{sub 3} is deposited rapidly within the first 4-5 km from its source. However, NH{sub 3} is also converted in the atmosphere to fine particle NH{sub 4}{sup +} (ammonium) aerosols that are a regional scale problem. Much of our current knowledge of the effects of NH{sub 3} on higher plants is predominantly derived from studies conducted in Europe. Adverse effects on vegetation occur when the rate of foliar uptake of NH{sub 3} is greater than the rate and capacity for in vivo detoxification by the plants. Most to least sensitive plant species to NH{sub 3} are native vegetation > forests > agricultural crops. There are also a number of studies on N deposition and lichens, mosses and green algae. Direct cause and effect relationships in most of those cases (exceptions being those locations very close to point sources) are confounded by other environmental factors, particularly changes in the ambient SO{sub 2} (sulfur dioxide) concentrations. In addition to direct foliar injury, adverse effects of NH{sub 3} on higher plants include alterations in: growth and productivity, tissue content of nutrients and toxic elements, drought and frost tolerance, responses to insect pests and disease causing microorganisms (pathogens), development of beneficial root symbiotic or mycorrhizal associations and inter species competition or biodiversity. In all these cases, the joint

OH outflows in star-forming regions

International Nuclear Information System (INIS)

Mirabel, I.F.; Ruiz, A.; Rodriguez, L.F.; Canto, J.; Universidad de Puer; Universidad de Puerto Rico, Rio Piedras; Universidad Nacional Autonoma de Mexico, Mexico City)

1987-01-01

The results from a survey for high-velocity OH in molecular outflows in star-forming regions are reported. High-velocity OH was detected in absorption in nine of these regions. When the telescope beam can resolve the outflows, they show similar anisotropic angular distribution as the redshifted and blueshifted CO. The OH transitions are markedly subthermal since for several sources it is found that the radiation that is being absorbed is a background continuum constituted by the cosmic component plus a small Galactic contribution. The absorbing OH appears to trace gas with higher velocities and lower densities than does the CO and, in some cases, provides information on the structure of the outflows at larger distances from the central source. At scales of 0.1 pc, the outflows are elongated in the direction of the steepest density gradient of the ambient cloud, suggesting that the large-scale collimation of the outflow is produced by the density structure of the ambient cloud. 29 references

Teddy Bear Stories

DEFF Research Database (Denmark)

van Leeuwen, Theo; Caldas-Coulthardt, Carmen

2014-01-01

This paper presents a semiotic analysis of a key cultural artefact, the teddy bear. After introducing the iconography of the teddy bear, it analyses different kinds of stories to show how teddy bears are endowed with meaning in everyday life: stories from children's books, reminiscenses by adults...... bears have traditionally centred on interpersonal relations within the nuclear family, but have recently been institutionalized and commercialized....

Optimization and kinetics decomposition of monazite using NaOH

International Nuclear Information System (INIS)

MV Purwani; Suyanti; Deddy Husnurrofiq

2015-01-01

Decomposition of monazite with NaOH has been done. Decomposition performed at high temperature on furnace. The parameters studied were the comparison NaOH / monazite, temperature and time decomposition. From the research decomposition for 100 grams of monazite with NaOH, it can be concluded that the greater the ratio of NaOH / monazite, the greater the conversion. In the temperature influences decomposition 400 - 700°C, the greater the reaction rate constant with increasing temperature greater decomposition. Comparison NaOH / monazite optimum was 1.5 and the optimum time of 3 hours. Relations ratio NaOH / monazite with conversion (x) following the polynomial equation y = 0.1579x 2 – 0.2855x + 0.8301 (y = conversion and x = ratio of NaOH/monazite). Decomposition reaction of monazite with NaOH was second orde reaction, the relationship between temperature (T) with a reaction rate constant (k), k = 6.106.e - 1006.8 /T or ln k = - 1006.8/T + 6.106, frequency factor A = 448.541, activation energy E = 8.371 kJ/mol. (author)

Towards validation of ammonia (NH3) measurements from the IASI satellite

Science.gov (United States)

Van Damme, M.; Clarisse, L.; Dammers, E.; Liu, X.; Nowak, J. B.; Clerbaux, C.; Flechard, C. R.; Galy-Lacaux, C.; Xu, W.; Neuman, J. A.; Tang, Y. S.; Sutton, M. A.; Erisman, J. W.; Coheur, P. F.

2015-03-01

Limited availability of ammonia (NH3) observations is currently a barrier for effective monitoring of the nitrogen cycle. It prevents a full understanding of the atmospheric processes in which this trace gas is involved and therefore impedes determining its related budgets. Since the end of 2007, the Infrared Atmospheric Sounding Interferometer (IASI) satellite has been observing NH3 from space at a high spatio-temporal resolution. This valuable data set, already used by models, still needs validation. We present here a first attempt to validate IASI-NH3 measurements using existing independent ground-based and airborne data sets. The yearly distributions reveal similar patterns between ground-based and space-borne observations and highlight the scarcity of local NH3 measurements as well as their spatial heterogeneity and lack of representativity. By comparison with monthly resolved data sets in Europe, China and Africa, we show that IASI-NH3 observations are in fair agreement, but they are characterized by a smaller variation in concentrations. The use of hourly and airborne data sets to compare with IASI individual observations allows investigations of the impact of averaging as well as the representativity of independent observations for the satellite footprint. The importance of considering the latter and the added value of densely located airborne measurements at various altitudes to validate IASI-NH3 columns are discussed. Perspectives and guidelines for future validation work on NH3 satellite observations are presented.

Reduction of Tc(VII) and Np(V) in solution by ferrous iron. A laboratory study of homogeneous and heterogeneous redox processes

International Nuclear Information System (INIS)

Cui, D.; Eriksen, T.E.

1996-03-01

The redox chemistry of Technetium and Neptunium in deep groundwater systems has been studied under well controlled conditions in laboratory experiments. The measured redox potentials in anoxic deep groundwater systems are consistent with redox reactions between Fe(II) in solution and hydrous Fe(III)-oxide phases. The fracture filling material and groundwater in transmissive fractures in bedrock constitute two different compartments in the groundwater system and experiments were therefore carried out in homogeneous Fe(II) containing solutions and in heterogeneous mixtures of solution with Fe(II) containing solid mineral phases. Reduction of the strongly sorbing neptunyl cation (NpO 2 + ) and the slightly sorbing pertechnetate anion (TcO 4 - ) by Fe(II) in solution was found to proceed very slowly, if at all, in reaction vessels with hydrophobic inner surfaces. However, in the heterogeneous systems we observed surface mediated reduction to the slightly soluble ( -8 mol*dm -3 ) tetravalent (hydr)oxides TcO 2 *nH 2 O (=Tc(OH) 4 ) and NpO 2 *nH 2 O (=Np(OH) 4 ) by Fe(II) sorbed on quartz,precipitated Fe(OH) 2 (s), Fe(II)CO 3 (s) and Fe(II) bearing minerals such as magnetite, hornblende and Fe(II)-chlorite. It is concluded that surface mediated redox-reactions will be the most effective pathway for the reduction of Tc(VII) and Np(V) in deep groundwater systems. On exposure of the surface-precipitated tetravalent (hydr)oxides to air saturated groundwater solutions the oxidative dissolution was found to be a very slow process and high concentration of hydrogen peroxide was required for oxidative dissolution. The slow rate of oxidative dissolution is most probably due to kinetic suppression of the reactions between dissolved oxygen and the precipitated (hydr)oxides. The kinetic suppression is caused by competing redox reactions at the surface of the Fe(II)-bearing minerals which consumes the dissolved oxygen. 30 refs, 22 figs

NH125 kills methicillin-resistant Staphylococcus aureus persisters by lipid bilayer disruption.

Science.gov (United States)

Kim, Wooseong; Fricke, Nico; Conery, Annie L; Fuchs, Beth Burgwyn; Rajamuthiah, Rajmohan; Jayamani, Elamparithi; Vlahovska, Petia M; Ausubel, Frederick M; Mylonakis, Eleftherios

2016-01-01

NH125, a known WalK inhibitor kills MRSA persisters. However, its precise mode of action is still unknown. The mode of action of NH125 was investigated by comparing its spectrum of antimicrobial activity and its effects on membrane permeability and giant unilamellar vesicles (GUVs) with walrycin B, a WalR inhibitor and benzyldimethylhexadecylammonium chloride (16-BAC), a cationic surfactant. NH125 killed persister cells of a variety of Staphylococcus aureus strains. Similar to 16-BAC, NH125 killed MRSA persisters by inducing rapid membrane permeabilization and caused the rupture of GUVs, whereas walrycin B did not kill MRSA persisters or induce membrane permeabilization and did not affect GUVs. NH125 kills MRSA persisters by interacting with and disrupting membranes in a detergent-like manner.

“Bear-ly” learning: Limits of abstraction in black bear cognition

Directory of Open Access Journals (Sweden)

Jennifer Vonk

2018-02-01

Full Text Available We presented two American black bears (Ursus americanus with a serial list learning memory task, and one of the bears with a matching-to-sample task. After extended training, both bears demonstrated some success with the memory task but failed to generalize the overarching rule of the task to novel stimuli. Matching to sample proved even more difficult for our bear to learn. We conclude that, despite previous success in training bears to respond to natural categories, quantity discriminations, and other related tasks, that bears may possess a cognitive limitation with regards to learning abstract rules. Future tests using different procedures are necessary to determine whether this is a limit of bears’ cognitive capacities, or a limitation of the current tasks as presented. Future tests should present a larger number of varying stimuli. Ideally, bears of various species should be tested on these tasks to demonstrate species as well as individual differences.

Empirical and mechanistic evaluation of NH4(+) release kinetic in calcareous soils.

Science.gov (United States)

Ranjbar, F; Jalali, M

2014-05-01

Release, fixation, and distribution of ammonium (NH4(+)) as a source of nitrogen can play an important role in soil fertility and plant nutrition. In this study, ten surface soils, after addition of 1,000 mg NH4(+) kg(-1,) were incubated for 1 week at the field capacity moisture and 25 ± 2 °C temperature, and then NH4(+) release kinetic was investigated by sequential extractions with 10 mM CaCl2. Furthermore, NH4(+) distribution among three fractions, including water-soluble, exchangeable, and non-exchangeable, was determined in all soil samples. NH4(+) release was initially rapid followed by a slower reaction, and this was described well with the Elovich equation as an empirical model. The cumulative NH4(+) concentration released in spiked soil samples had a positive significant correlation with sand content and negative ones with pH, exchangeable Ca(2+)m and K(+), cation exchange capacity (CEC), equivalent calcium carbonate (ECC), and clay content. The cation exchange model in the PHREEQC program was successful in mechanistic simulation of the release trend of native and added NH4(+) in all control and spiked soil samples. The results of fractionation experiments showed that the non-exchangeable fraction in control and spiked soil samples was greater than that in water-soluble and exchangeable fractions. Soil properties, such as pH, exchangeable Ca(2+) and K(+), CEC, ECC, and contents of sand and clay, had significant influences on the distribution of NH4(+) among three measured fractions. This study indicated that both native and recently fixed NH4(+), added to soil through the application of fertilizers, were readily available for plant roots during 1 week after exposure.

Coal demineralization with Ca(OH)2. Hydrothermal reaction between Ca(OH)2 and quartz; Ca(OH)2 wo mochiita sekitan no kagakuteki dakkai. Ca(OH)2 to sekitan no suinetsu hanno

Energy Technology Data Exchange (ETDEWEB)

Wang, J.; Tomita, A. [Tohoku University, Sendai (Japan). Institute for Chemical Reaction Science

1996-10-28

Coal demineralization mechanism and its optimum condition were studied by hydrothermal reaction between Ca(OH)2 and quartz as a coal demineralization model. In experiment, the mixture of powder quartz and Ca(OH)2 water slurry was subjected to reaction in an autoclave under spontaneous pressure at 175-340{degree}C. After dried in N2 gas atmosphere at 105{degree}C, the reaction product was analyzed by X-ray diffraction, thermo-balance and differential thermal analysis. In measurement of quartz conversion, the specimen was analyzed by X-ray diffraction after removal of bound water by heat treatment at 850{degree}C. The mixture of clean coal deashed by NaOH and a fixed amount of quartz was also used as specimen for experiment. As the experimental result, dicalcium silicate hydrate was mainly produced at 175{degree}C, and the product changed into xonotlite through tobermorite by longer treatment at higher temperature. For complete reaction of quartz, heat treatments for 7 and 5 hours at 300 and 400{degree}C were necessary, respectively. 2 refs., 2 figs., 2 tabs.

Constraints on the OH-to-H Abundance Ratio in Infrared-bright Galaxies Derived from the Strength of the OH 35 μm Absorption Feature

Science.gov (United States)

Stone, Myra; Veilleux, Sylvain; González-Alfonso, Eduardo; Spoon, Henrik; Sturm, Eckhard

2018-02-01

We analyze Spitzer/InfraRed Spectrograph (IRS) observations of the OH 35 μm feature in 15 nearby (z ≲ 0.06) (ultra-)luminous infrared galaxies (U/LIRGs). All objects exhibit OH 35 μm purely in absorption, as expected. The small optical depth of this transition makes the strength of this feature a good indicator of the true OH column density. The measured OH 35 μm equivalent widths imply an average OH column density and a 1-σ standard deviation to the mean of {N}{OH}=1.31+/- 0.22× {10}17 cm‑2. This number is then compared with the hydrogen column density for a typical optical depth at 35 μm of ∼0.5 and gas-to-dust ratio of 125 to derive an OH-to-H abundance ratio of {X}{OH}=1.01+/- 0.15× {10}-6. This abundance ratio is formally a lower limit. It is consistent with the values generally assumed in the literature. The OH 35 μm line profiles predicted from published radiative transfer models constrained by observations of OH 65, 79, 84, and 119 μm in 5 objects (Mrk 231, Mrk 273, IRAS F05189-2524, IRAS F08572+3915, and IRAS F20551-4250) are also found to be consistent with the IRS OH 35 μm spectra.

Vectorial Modeling Of NH In Comet 2P/Encke

Science.gov (United States)

Dorman, Garrett; Pierce, D.; Cochran, A.

2010-10-01

Encke is an ideal comet for studying the relationship of radicals to their photodissociative parent molecules due to its low dust content. On 2003 October 22 - 24, we used the the 2.7 m telescope at the McDonald Observatory of the University of Texas to obtain spectra of several cometary radical species. Using a version of the Vectorial Model that has been modified to simulate Encke's prominent sunward-facing fan, we examined the spacial distribution of NH in the coma. Potential photochemical parents of NH were studied in order to understand its production and spacial distribution in the coma. Derived production rates are compared to values in other comets to constrain the primary parent of NH in Encke.

Interactions between kaolinite Al−OH surface and sodium hexametaphosphate

Energy Technology Data Exchange (ETDEWEB)

Han, Yonghua, E-mail: hyh19891102@163.com [School of Chemical and Environmental Engineering, China University of Mining and Technology, Beijing 100083 (China); Liu, Wenli; Zhou, Jia [School of Chemical and Environmental Engineering, China University of Mining and Technology, Beijing 100083 (China); Chen, Jianhua [College of Resources and Metallurgy, Guangxi University, Nanning 530004 (China)

2016-11-30

Highlights: • Sodium hexametaphosphate (NaHMP) can adsorb on kaolinite Al−OH terminated (001) surface easily. • The oxygen atoms of hexametaphosphate form strong hydrogen bonds with the hydrogen atoms of kaolinite Al−OH surface. • The electrostatic force is the main interaction between NaHMP and Al−OH surface. • The linear hexaphosphate −[PO{sub 3}]{sub m}− chains adsorb stably than −[HPO{sub 3}]{sub m}− chains. - Abstract: To investigate the dispersion mechanism of sodium hexametaphosphate on kaolinite particles, we simulated the interaction between linear polyphosphate chains and kaolinite Al−OH terminated surface by molecular dynamics, as well as the interaction between the [HPO{sub 4}]{sup 2−} anion and kaolinite Al−OH surface by density functional theory (DFT). The calculated results demonstrate that hexametaphosphate can be adsorbed by the kaolinite Al−OH surface. The oxygen atoms of hexametaphosphate anions may receive many electrons from the Al−OH surface and form hydrogen bonds with the hydrogen atoms of surface hydroxyl groups. Moreover, electrostatic force dominates the interactions between hexametaphosphate anions and kaolinite Al−OH surface. Therefore, after the adsorption of hexametaphosphate on kaolinite Al−OH surface, the kaolinite particles carry more negative charge and the electrostatic repulsion between particles increases. In addition, the adsorption of −[PO{sub 3}]{sub m}− species on the Al−OH surface should be more stable than the adsorption of −[HPO{sub 3}]{sub m}− species.

NH4+ triggers the release of astrocytic lactate via mitochondrial pyruvate shunting

Science.gov (United States)

Lerchundi, Rodrigo; Fernández-Moncada, Ignacio; Contreras-Baeza, Yasna; Sotelo-Hitschfeld, Tamara; Mächler, Philipp; Wyss, Matthias T.; Stobart, Jillian; Baeza-Lehnert, Felipe; Alegría, Karin; Weber, Bruno; Barros, L. Felipe

2015-01-01

Neural activity is accompanied by a transient mismatch between local glucose and oxygen metabolism, a phenomenon of physiological and pathophysiological importance termed aerobic glycolysis. Previous studies have proposed glutamate and K+ as the neuronal signals that trigger aerobic glycolysis in astrocytes. Here we used a panel of genetically encoded FRET sensors in vitro and in vivo to investigate the participation of NH4+, a by-product of catabolism that is also released by active neurons. Astrocytes in mixed cortical cultures responded to physiological levels of NH4+ with an acute rise in cytosolic lactate followed by lactate release into the extracellular space, as detected by a lactate-sniffer. An acute increase in astrocytic lactate was also observed in acute hippocampal slices exposed to NH4+ and in the somatosensory cortex of anesthetized mice in response to i.v. NH4+. Unexpectedly, NH4+ had no effect on astrocytic glucose consumption. Parallel measurements showed simultaneous cytosolic pyruvate accumulation and NADH depletion, suggesting the involvement of mitochondria. An inhibitor-stop technique confirmed a strong inhibition of mitochondrial pyruvate uptake that can be explained by mitochondrial matrix acidification. These results show that physiological NH4+ diverts the flux of pyruvate from mitochondria to lactate production and release. Considering that NH4+ is produced stoichiometrically with glutamate during excitatory neurotransmission, we propose that NH4+ behaves as an intercellular signal and that pyruvate shunting contributes to aerobic lactate production by astrocytes. PMID:26286989

NH4(+) triggers the release of astrocytic lactate via mitochondrial pyruvate shunting.

Science.gov (United States)

Lerchundi, Rodrigo; Fernández-Moncada, Ignacio; Contreras-Baeza, Yasna; Sotelo-Hitschfeld, Tamara; Mächler, Philipp; Wyss, Matthias T; Stobart, Jillian; Baeza-Lehnert, Felipe; Alegría, Karin; Weber, Bruno; Barros, L Felipe

2015-09-01

Neural activity is accompanied by a transient mismatch between local glucose and oxygen metabolism, a phenomenon of physiological and pathophysiological importance termed aerobic glycolysis. Previous studies have proposed glutamate and K(+) as the neuronal signals that trigger aerobic glycolysis in astrocytes. Here we used a panel of genetically encoded FRET sensors in vitro and in vivo to investigate the participation of NH4(+), a by-product of catabolism that is also released by active neurons. Astrocytes in mixed cortical cultures responded to physiological levels of NH4(+) with an acute rise in cytosolic lactate followed by lactate release into the extracellular space, as detected by a lactate-sniffer. An acute increase in astrocytic lactate was also observed in acute hippocampal slices exposed to NH4(+) and in the somatosensory cortex of anesthetized mice in response to i.v. NH4(+). Unexpectedly, NH4(+) had no effect on astrocytic glucose consumption. Parallel measurements showed simultaneous cytosolic pyruvate accumulation and NADH depletion, suggesting the involvement of mitochondria. An inhibitor-stop technique confirmed a strong inhibition of mitochondrial pyruvate uptake that can be explained by mitochondrial matrix acidification. These results show that physiological NH4(+) diverts the flux of pyruvate from mitochondria to lactate production and release. Considering that NH4(+) is produced stoichiometrically with glutamate during excitatory neurotransmission, we propose that NH4(+) behaves as an intercellular signal and that pyruvate shunting contributes to aerobic lactate production by astrocytes.

GAS BEARING

Science.gov (United States)

Skarstrom, C.W.

1960-09-01

A gas lubricated bearing for a rotating shaft is described. The assembly comprises a stationary collar having an annular member resiliently supported thereon. The collar and annular member are provided with cooperating gas passages arranged for admission of pressurized gas which supports and lubricates a bearing block fixed to the rotatable shaft. The resilient means for the annular member support the latter against movement away from the bearing block when the assembly is in operation.

Limited overshooting of NH{sub 4}{sup +} ions in ammonium perchlorate; Ograniczene przeskoki jonow NH{sub 4}{sup +} w nadchloranie amonowym

Energy Technology Data Exchange (ETDEWEB)

Birczynski, A.; Lalowicz, Z.T. [Inst. of Nuclear Physics, Cracow (Poland); Ingman, L.P.; Punkkinen, M.; Ylinen, E.E. [Wihuri Physical Lab., Turku Univ., Turku (Finland)

1995-12-31

The interpretation of NMR spectra for polycrystalline sample of ammonium perchlorate in helium temperature assumes the tunneling of NH{sub 4}{sup +}. Such interpretation does not agree with experimental data. The hypothesis of additional motion (fast rotation around one of C3 axis) has been checked and discussed on the base of NMR spectra of NH{sub 4}ClO{sub 4} monocrystal for the temperature range 2.1-25 K. 9 refs, 1 fig.

Limited overshooting of NH{sub 4}{sup +} ions in ammonium perchlorate; Ograniczene przeskoki jonow NH{sub 4}{sup +} w nadchloranie amonowym

Energy Technology Data Exchange (ETDEWEB)

Birczynski, A; Lalowicz, Z T [Inst. of Nuclear Physics, Cracow (Poland); Ingman, L P; Punkkinen, M; Ylinen, E E [Wihuri Physical Lab., Turku Univ., Turku (Finland)

1996-12-31

The interpretation of NMR spectra for polycrystalline sample of ammonium perchlorate in helium temperature assumes the tunneling of NH{sub 4}{sup +}. Such interpretation does not agree with experimental data. The hypothesis of additional motion (fast rotation around one of C3 axis) has been checked and discussed on the base of NMR spectra of NH{sub 4}ClO{sub 4} monocrystal for the temperature range 2.1-25 K. 9 refs, 1 fig.

Crystal structure, equation of state, and elasticity of hydrous aluminosilicate phase, topaz-OH (Al2SiO4(OH)2) at high pressures

Science.gov (United States)

Mookherjee, Mainak; Tsuchiya, Jun; Hariharan, Anant

2016-02-01

We examined the equation of state and high-pressure elasticity of the hydrous aluminosilicate mineral topaz-OH (Al2SiO4(OH)2) using first principles simulation. Topaz-OH is a hydrous phase in the Al2O3-SiO2-H2O (ASH) ternary system, which is relevant for the mineral phase relations in the hydrated sedimentary layer of subducting slabs. Based on recent neutron diffraction experiments, it is known that the protons in the topaz-OH exhibit positional disorder with half occupancy over two distinct crystallographic sites. In order to adequately depict the proton environment in the topaz-OH, we examined five crystal structure models with distinct configuration for the protons in topaz-OH. Upon full geometry optimization we find two distinct space group, an orthorhombic Pbnm and a monoclinic P21/c for topaz-OH. The topaz-OH with the monoclinic P21/c space group has a lower energy compared to the orthorhombic Pbmn space group symmetry. The pressure-volume results for the monoclinic topaz-OH is well represented by a third order Birch-Murnaghan formulation, with V0mon = 348.63 (±0.04) Å3, K0mon = 164.7 (±0.04) GPa, and K0mon = 4.24 (±0.05). The pressure-volume results for the orthorhombic topaz-OH is well represented by a third order Birch-Murnaghan formulation, with V0orth = 352.47 (±0.04) Å3, K0orth = 166.4 (±0.06) GPa, and K0orth = 4.03 (±0.04). While the bulk moduli are very similar for both the monoclinic and orthorhombic topaz-OH, the shear elastic constants and the shear moduli are very sensitive to the position of the proton, orientation of the O-H dipole, and the space group symmetry. The S-wave anisotropy for the orthorhombic and monoclinic topaz-OH are also quite distinct. In the hydrated sedimentary layer of subducting slabs, transformation of a mineral assemblage consisting of coesite (SiO2) and diaspore (AlOOH) to topaz-OH (Al2SiO4(OH)2) is likely to be accompanied by an increase in density, compressional velocity, and shear wave velocity. However

Characteristics of infrared point sources associated with OH masers

International Nuclear Information System (INIS)

Mu Jimang; Esimbek, Jarken; Zhou Jianjun; Zhang Haijuan

2010-01-01

We collect 3249 OH maser sources from the literature published up to April 2007, and compile a new catalog of OH masers. We look for the exciting sources of these masers and their infrared properties from IRAS and MSX data, and make a statistical study. MSX sources associated with stellar 1612 MHz OH masers are located mainly above the blackbody line; this is caused by the dust absorption of stellar envelopes, especially in the MSX A band. The mid-IR sources associated with stellar OH masers are concentrated in a small region in an [A]-[D] vs. [A]-[E] diagram with a small fraction of contamination; this gives us a new criterion to search for new stellar OH masers and distinguish stellar masers from unknown types of OH masers. IR sources associated with 1612 MHz stellar OH masers show an expected result: the average flux of sources with F60 > F25 increases with increasing wavelength, while those with F60 F25.

Functional groups grafted nonwoven fabrics for blood filtration-The effects of functional groups and wettability on the adhesion of leukocyte and platelet

Energy Technology Data Exchange (ETDEWEB)

Yang Chao [State Key Lab of Metal Matrix Composites, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China); Cao Ye [Institute of Blood Transfusion, Chinese Academy of Medical Sciences and Peking Union Medical College, Chengdu 610081 (China); Sun Kang, E-mail: ksun@sjtu.edu.cn [State Key Lab of Metal Matrix Composites, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China); Liu Jiaxin; Wang Hong [Institute of Blood Transfusion, Chinese Academy of Medical Sciences and Peking Union Medical College, Chengdu 610081 (China)

2011-01-15

In this work, the effects of grafted functional groups and surface wettability on the adhesion of leukocyte and platelet were investigated by the method of blood filtration. The filter materials, poly(butylene terephthalate) nonwoven fabrics bearing different functional groups including hydroxyl (OH), carboxyl (COOH), sulfonic acid group (SO{sub 3}H) and zwitterionic sulfobetaine group ({sup +}N((CH{sub 3}){sub 2})(CH{sub 2}){sub 3}SO{sub 3}{sup Circled-Minus }) with controllable wettability were prepared by UV radiation grafting vinyl monomers with these functional groups. Our results emphasized that both surface functional groups and surface wettability had significant effects on the adhesion of leukocyte and platelet. In the case of filter materials with the same wettability, leukocytes adhering to filter materials decreased in the order: the surface bearing OH only > the surface bearing both OH and COOH > the surface bearing sulfobetaine group > the surface bearing SO{sub 3}H, while platelets adhering to filter materials decreased as the following order: the surface bearing SO{sub 3}H > the surface bearing both OH and COOH > the surface bearing OH only > the surface bearing sulfobetaine group. As the wettability of filter materials increased, both leukocyte and platelet adhesion to filter materials declined, except that leukocyte adhesion to the surface bearing OH only remained unchanged.

Effect of precipitating agent on the catalytic behaviour of precipitated iron catalysts

International Nuclear Information System (INIS)

Motjope, T.R.; Dlamini, H.T.; Pollak, H.; Coville, N.J.

1999-01-01

Iron precipitated catalysts have been prepared using different precipitating agents (NH 4 OH, K 2 CO 3 ) at different pH values. In situ Moessbauer (MES) study of the reduced catalyst prepared using NH 4 OH revealed the presence of superparamagnetic Fe 2+ , Fe 3+ and magnetically split α-Fe only, whereas the catalyst prepared with K 2 CO 3 also showed an extra magnetic sextuplet of Fe 3 O 4 . For both catalyst systems, in situ MES revealed that during Fischer-Tropsch synthesis α-Fe was converted into ε'-Fe 2,2 C and finally into χ-Fe 2,5 C when the synthesis time was increased. The rate of formation of hydrocarbons was observed to increase with the increase in the degree of carburisation with the NH 4 OH catalyst showing a higher rate of reaction. The K 2 CO 3 catalyst exhibited higher olefin selectivity than the NH 4 OH catalyst under similar pH conditions

Rotational spectrum of the NH3–He van der Waals complex

Directory of Open Access Journals (Sweden)

Surin L.

2017-01-01

Full Text Available The interaction between ammonia and helium has attracted considerable interest over many years, partly because of the observation of interstellar ammonia. The rate coefficients of NH3–He scattering are an important ingredient for numerical modeling of astrochemical environments. Another, though quite different application in which the NH3–He interaction can play an important role is the doping of helium clusters with NH3 molecules to perform high-resolution spectroscopy. Such experiments are directed on the detection of non-classical response of molecular rotation in helium clusters addressing fundamental questions related to the microscopic nature of superfluidity. High-resolution spectroscopy on the NH3–He complex is an important tool for increasing our understanding of intermolecular forces between NH3 and He.

Interaction of (NH4)2ZrF6 and (NH4)3ZrF7 with strontium and lead nitrates

International Nuclear Information System (INIS)

Krysenko, G.F.; Mel'nichenko, E.I.; Ehpov, D.G.; Polishchuk, S.A.

1991-01-01

Methods of chemical, X-ray phase, thermogravimetric analysis and IR spectroscopy were used to study reactions between ammonium fluorozirconates and strontium and lead nitrates. Formation of anhydrous hexa- and octafluorozirconates of strontium and lead in the form of MZrF 6 ·0.5NH 4 F and M 2 ZrF 8 ·0.5NH 4 F double salts, which decompose at 315-430 deg C to corresponding hexa- and octafluorozirconates, was established. Effect of hydrofluoric acid on composition of lead fluorozirconates was studied

C-H and C-C activation of n -butane with zirconium hydrides supported on SBA15 containing N-donor ligands: [(≡SiNH-)(≡SiX-)ZrH2], [(≡SiNH-)(≡SiX-)2ZrH], and[(≡SiN=)(≡SiX-)ZrH] (X = -NH-, -O-). A DFT study

KAUST Repository

Pasha, Farhan Ahmad; Bendjeriou-Sedjerari, Anissa; Huang, Kuo-Wei; Basset, Jean-Marie

2014-01-01

: [(≡SiNH-)(≡SiO-)ZrH2] (A), [(≡SiNH-)2ZrH2] (B), [(≡SiNH-)(≡SiO-) 2ZrH] (C), [(≡SiNH-)2(≡SiO-)ZrH] (D), [(≡SiN=)(≡Si-O-)ZrH] (E), and [(≡SiN=)(≡SiNH-)ZrH] (F). The roles of these hydrides have been investigated in C-H/C-C bond activation and cleavage

Crystal structure and charge density analysis of Li2NH by synchrotron X-ray diffraction

International Nuclear Information System (INIS)

Noritake, T.; Nozaki, H.; Aoki, M.; Towata, S.; Kitahara, G.; Nakamori, Y.; Orimo, S.

2005-01-01

Complex hydrides, such as lithium amide (LiNH 2 ) and lithium imide (Li 2 NH), have recently been noticed as one of the most promising materials for reversible hydrogen storage. In this paper, we reveal the bonding nature of hydrogen in Li 2 NH crystal by synchrotron powder X-ray diffraction measurement at room temperature. The crystal structure was refined by Rietveld method and the charge density distribution was analyzed by maximum entropy method (MEM). The Li 2 NH crystal is anti-fluorite type structure (space group Fm3-bar m) consisting of Li and NH. Hydrogen atom occupies randomly the 48h (Wyckoff notation) sites around N atom. The refined lattice constant is a=5.0742(2)A. The charge density distribution around NH anion in Li 2 NH is almost spherical. The number of electrons within the sphere around the Li and NH is estimated from the obtained charge density distribution. As the result, the ionic charge is expressed as [Li 0.99+ ] 2 [NH] 1.21- . Therefore, it is confirmed experimentally that Li 2 NH is ionically bonded

NO3-/NH4+ proportions affect cadmium bioaccumulation and tolerance of tomato.

Science.gov (United States)

Nogueirol, Roberta Corrêa; Monteiro, Francisco Antonio; de Souza Junior, João Cardoso; Azevedo, Ricardo Antunes

2018-05-01

With the growth of the world population, cadmium (Cd) concentration in the environment has increased considerably as a result of human activities such as foundry, battery disposal, mining, application of fertilizers containing toxic elements as impurities, and disposal of metal-containing waste. Higher plants uptake N as ammonium (NH 4 + ), nitrate (NO 3 - ), and many other water-soluble compounds such as urea and amino acids, and nourishing plants with N, providing part of it as NH 4 + , is an interesting alternative to the supply of this nutrient in the exclusive form of NO 3 - under Cd toxicity. The objective was to evaluate the influence of NO 3 - /NH 4 + proportions on the development and tolerance of tomato plants grown under the presence of Cd in the culture medium. The experiment was conducted in a completely randomized block design in a 3 × 3 factorial arrangement consisting of three Cd rates (0, 50, and 100 μmol L -1 ) and three NO 3 - /NH 4 + proportions (100/0, 70/30, and 50/50) in the nutrient solution. To this end, we quantified the responses of the antioxidant enzymatic system and productive and functional changes in Solanum lycopersicum var. esculentum (Calabash Rouge). Shoot biomass production decreased with the maximum Cd rate (100 μmol L -1 ) tested in the growth medium, whereas the NO 3 - /NH 4 + proportions and other Cd rates did not significantly influence this variable. The lowest SPAD values were observed at the 100/0 NO 3 - /NH 4 + proportion and in plants exposed to Cd. The largest accumulation of the metal occurred in the shoots at the NO 3 - /NH 4 + proportion of 70/30 and at 100 μmol L -1 Cd and in the roots at 100/0 NO 3 - /NH 4 + and with 50 and 100 μmol L -1 Cd. The concentration and accumulation of NO 3 - were highest at the NO 3 - /NH 4 + proportion of 100/0 in the shoots and at 50/50 NO 3 - /NH 4 + in the roots, whereas for NH 4 + , values were higher as the proportion of N supplied in the form of NH 4 + was

Molecular modelling of the decomposition of NH{sub 3} over CoO(100)

Energy Technology Data Exchange (ETDEWEB)

Shojaee, Kambiz; Haynes, Brian S.; Montoya, Alejandro, E-mail: alejandro.montoya@sydney.edu.au

2015-04-15

Spin-polarised density functional theory using the PBE + U approach are used to determine reaction pathways of successive NH{sub 3} dehydrogenation on the CoO(100) surface. NH{sub 3} dehydrogenation promotes noticeable displacements of the surface CoO sites, in particular due to the binding of NH{sub 2} and H species. Surface lattice O has low activity towards dehydrogenation, reflected in energy barriers that are in the range of 292 kJ mol{sup −1} to 328 kJ mol{sup −1}. There is a preference of surface NH{sub 3} dehydrogenation to N{sub 2} rather than towards NO, due to a high-energy penalty of surface O vacancy formation. The presence of CoO in cobalt oxide catalysts not only may decline the ammonia conversion but also alter the selectivity towards N{sub 2} rather than NO. - Highlights: • Minimum reactions pathways of ammonia decomposition were studied using density functional theory. • The bonding characteristics of NH{sub x} and H on the CoO(100) surface were analysed using Layer-projected density of states. • Dehydrogenations of NH{sub 3}, NH{sub 2} and NH are highly activated. • The presence of strongly bound lattice oxygen favours the ammonia decomposition towards N{sub 2}.

Studies on the ruthenium complexes. IX. Kinetic studies on the deaquation-anation reaction of aquapentaammineruthenium(III) complexes

Energy Technology Data Exchange (ETDEWEB)

Ohyoshi, A; Hiraki, S I; Odate, T; Kohata, S; Oda, J [Kumamoto Univ. (Japan). Faculty of Engineering

1975-01-01

The deaquation-anation reaction of (Ru(OH/sub 2/)(NH/sub 3/)/sub 5/)X/sub 3/-type complexes in the solid state, as shown by the (Ru(OH/sub 2/)(NH/sub 3/)/sub 5/)X/sub 3/(s)..-->..(RuX(NH/sub 3/)/sub 5/)X/sub 2/(s)+H/sub 2/O(g) equation, where X is Cl, Br, I, and NO/sub 3/ respectively, was kinetically studied by means of thermogravimetry (TG) along with differential thermal analysis (DTA). The activation energy and entropy in the reaction process (Esub(a) kcal/mol, ..delta..S c.u.) are, respectively, found by isothermal kinetic study to be (22.7, - 7.1) for the chloride, (23.4, - 5.2) for the bromide, (26.7, 5.8) for the iodide, and (19.3 - 15.9) for the nitrate. The reaction seems to proceed through the following two steps, except in the case of the iodide: (Ru(OH/sub 2/)(NH/sub 3/)/sub 5/)X/sub 3/..-->..(RuX(OH/sub 2/)(NH/sub 3/)/sub 5/)X/sub 2/..-->..(RuX(NH/sub 3/)/sub 5/)X/sub 2/+H/sub 2/O. The first step is regarded as the rate-determining one.

Chemical and electrical properties of (NH4)2S passivated GaSb surface

International Nuclear Information System (INIS)

Tao Dongyan; Cheng Yu; Liu Jingming; Su Jie; Liu Tong; Yang Fengyun; Wang Fenghua; Cao Kewei; Dong Zhiyuan; Zhao Youwen

2015-01-01

The surface chemical properties of gallium antimonide (GaSb) after ammonium sulfide ((NH 4 ) 2 S) solution passivation have been studied by X-ray photoelectron spectroscopy (XPS), time of flight secondary ion mass spectroscopy (TOF-SIMS) and I–V measurement. An advantage of neutral (NH 4 ) 2 S + S solution over pure (NH 4 ) 2 S solution and alkaline (NH 4 ) 2 S + S solution has been found in the ability to passivate the GaSb surface by contrast and comparison. It has been found that alkaline (NH 4 ) 2 S + S solution passivation effectively removes oxides of the GaSb surface and forms sulfide products to improve device performance. TOF-SIMS complementally demonstrates that pure (NH 4 ) 2 S passivation did form sulfide products, which are too soluble to really exist. The lowest roughness determined using a 3D optical profilometer and the highest improved SBD quality proved that neutral (NH 4 ) 2 S + S solution passivation worked much better in improving the surface properties of GaSb. (paper)

OH radio lines in comets - a review

International Nuclear Information System (INIS)

Gerard, E.

1987-01-01

A review of OH cometary radioastronomy from the excitation of the molecule to the detailed analysis of the line profile is presented. It is suggested that the inversion models of Despois et al. (1981) and Schleicher (1983) may be improved by taking the production rates from recent UV data (when the inversion modulus is small) once the radio vs UV discrepancies are better understood. OH radiation transfer through the coma is considered. The unresolved total integrated flux density of the OH coma can be determined by carefully mapping the OH coma using a point source calibrator. The SYMCOMET method for improving the SNR of existing profiles (in order to achieve early detections) has the advantage of suppressing the antisymmetric part of the baseline ripples or instrumental profiles. 24 references

Alkaloids from the hook-bearing branch of Uncaria rhynchophylla and their neuroprotective effects against glutamate-induced HT22 cell death

OpenAIRE

Qi, Wen; Yue, Si-Jia; Sun, Jia-Hong; Simpkins, James W.; Zhang, Lin; Yuan, Dan

2014-01-01

One new alkaloid, 4-geissoschizine N-oxide methyl ether (1), was isolated from the EtOH extract of the hook-bearing branch of Uncaria rhynchophylla, together with 10 known alkaloids, 3-epi-geissoschizine methyl ether (2) isolated from U. rhynchophylla for the first time, geissoschizine methyl ether (3), 4-hirsuteine N-oxide (4), hirsuteine (5), hirsutine (6), 3α-dihydro-cadambine (7), 3β-isodihydro-cadambine (8), cadambine (9), strictosamide (10), and akuammigine (11). The structures were elu...

Genomic evidence of geographically widespread effect of gene flow from polar bears into brown bears.

Science.gov (United States)

Cahill, James A; Stirling, Ian; Kistler, Logan; Salamzade, Rauf; Ersmark, Erik; Fulton, Tara L; Stiller, Mathias; Green, Richard E; Shapiro, Beth

2015-03-01

Polar bears are an arctic, marine adapted species that is closely related to brown bears. Genome analyses have shown that polar bears are distinct and genetically homogeneous in comparison to brown bears. However, these analyses have also revealed a remarkable episode of polar bear gene flow into the population of brown bears that colonized the Admiralty, Baranof and Chichagof islands (ABC islands) of Alaska. Here, we present an analysis of data from a large panel of polar bear and brown bear genomes that includes brown bears from the ABC islands, the Alaskan mainland and Europe. Our results provide clear evidence that gene flow between the two species had a geographically wide impact, with polar bear DNA found within the genomes of brown bears living both on the ABC islands and in the Alaskan mainland. Intriguingly, while brown bear genomes contain up to 8.8% polar bear ancestry, polar bear genomes appear to be devoid of brown bear ancestry, suggesting the presence of a barrier to gene flow in that direction. © 2014 The Authors. Molecular Ecology Published by John Wiley & Sons Ltd.

Crystal structure investigations on cation-substituted alums by X-ray and neutron diffraction

International Nuclear Information System (INIS)

Abdeen, A.M.

1980-04-01

The crystal structures of the three alums: NH 4 Al(SO 4 ) 2 .12H 2 O, (NH 3 CH 3 )Al(SO 4 ) 2 .12H 2 O and (NH 3 OH)Al(SO 4 ) 2 .12H 2 O have been determined from three-dimensional neutron diffraction data enhanced by X-ray diffraction when necessary. These compounds crystallize cubic in space group Pa3. The structures of the three alums exhibit partial occupancies of crystallographic sites for the NH 4 , (NH 3 CH 3 ) and (NH 3 OH) group atoms. This can be explained by a quantized rotation of the three groups around an axis perpendicular to the [111] direction. Some of the (SO 4 ) 2- groups in the NH 4 -alum are disordered with about 17% of the sulfate tetrahedra being in a reversed orientation around the sulfur atom. The disorder in (NH 3 CH 3 ) and (NH 3 OH)-alums is only 4,3% and 3.0% respectively. The atoms in the alum structures are held together by a system of hydrogen bonds between the water molecules and between the water molecules and the sulfate oxygen atoms. In these three structures there is a strong indication that shorter hydrogen bonds tend to be nearly linear. (orig.)

Synthesis and structure of [(NH2)2CSSC(NH2)2]2[OsBr6]Br2 . 3H2O

International Nuclear Information System (INIS)

Rudnitskaya, O. V.; Kultyshkina, E. K.; Stash, A. I.; Glukhova, A. A.; Venskovskii, N. U.

2008-01-01

The complex [(NH 2 ) 2 CSSC(NH 2 ) 2 ] 2 [OsBr 6 ]Br 2 . 3H 2 O is synthesized by the reaction of K 2 OsBr 6 with thiocarbamide in concentrated HBr and characterized using electronic absorption and IR absorption spectroscopy. Its crystal structure is determined by X-ray diffraction. The crystals are orthorhombic, a = 11.730(2) A, b = 14.052(3) A, c = 16.994(3) A, space group Cmcm, and Z = 4. The [OsBr 6 ] 2- anionic complex has an octahedral structure. The Os-Br distances fall in the range 2.483-2.490 A. The α,α'-dithiobisformamidinium cation is a product of the oxidation of thiocarbamide. The S-S and C-S distances are 2.016 and 1.784 A, respectively. The H 2 O molecules, Br - ions, and NH 2 groups of the cation are linked by hydrogen bonds.

Refinement of hydrogen positions in (NH4)2SeO4

International Nuclear Information System (INIS)

Loose, A.; Mel'nik, G.; Zink, N.; Wozniak, K.; Dominiak, P.; Smirnov, L.S.; Pawlukojc, A.; Shuvalov, L.A.

2005-01-01

The crystal structure of ammonium selenate has been studied by means of single crystal X-ray and neutron diffraction with the purpose of the refinement of hydrogen positions. The refined hydrogen positions obtained by single crystal neutron diffraction show that N-H bond lengths form a regular tetrahedron in an ammonium ion. The single crystal X-ray diffraction data show that N-H bond lengths are shorter than those obtained by neutron diffraction and are not equal between themselves. Thus, the comparison of the results of X-ray and neutron diffraction allows one to suggest that the shorter N-H bond lengths by X-ray diffraction reflect the distribution of the electron charge density of ammonium ions within the (NH 4 ) 2 SeO 4 crystal lattice

EFFECT OF CLEARANCE THE BALL BEARINGS ON INCORRECT WORK OF THREE-SUPORT BEARING SHAFT

Directory of Open Access Journals (Sweden)

Jarosław KACZOR

2014-06-01

Full Text Available Durability deep groove ball bearings depends on factors (called attributes design, technological and operational. Among the design features one of the most important is play in the bearings. Polish Norm shows five groups of looseness in the bearings, in which the play range from 0 to 105 microns. Manufacturers of rolling bearings they only play group, which has a bearing data, without giving the exact value of the slack. Aim of this study is to determine how it affects the play in the bearings to work three-bearing shafts, including elasticity and resilience three-bearing shafts.

Reaction OH + OH studied over the 298-834 K temperature and 1-100 bar pressure ranges.

Science.gov (United States)

Sangwan, Manuvesh; Chesnokov, Evgeni N; Krasnoperov, Lev N

2012-06-21

Self-reaction of hydroxyl radicals, OH + OH → H(2)O + O (1a) and OH + OH → H(2)O(2) (1b), was studied using pulsed laser photolysis coupled to transient UV-vis absorption spectroscopy over the 298-834 K temperature and 1-100 bar pressure ranges (bath gas He). A heatable high-pressure flow reactor was employed. Hydroxyl radicals were prepared using reaction of electronically excited oxygen atoms, O((1)D), produced in photolysis of N(2)O at 193 nm, with H(2)O. The temporal behavior of OH radicals was monitored via transient absorption of light from a dc discharge in H(2)O/Ar low-pressure resonance lamp at ca. 308 nm. The absolute intensity of the photolysis light was determined by accurate in situ actinometry based on the ozone formation in the presence of molecular oxygen. The results of this study combined with the literature data indicate that the rate constant of reaction 1a, associated with the pressure independent component, decreases with temperature within the temperature range 298-414 K and increases above 555 K. The pressure dependent rate constant for (1b) was parametrized using the Troe expression as k(1b,inf) = (2.4 ± 0.6) × 10(-11)(T/300)(-0.5) cm(3) molecule(-1) s(-1), k(1b,0) = [He] (9.0 ± 2.2) × 10(-31)(T/300)(-3.5±0.5) cm(3) molecule(-1) s(-1), F(c) = 0.37.

Metal–organic coordination architectures of tetrazole heterocycle ligands bearing acetate groups: Synthesis, characterization and magnetic properties

International Nuclear Information System (INIS)

Hu, Bo-Wen; Zheng, Xiang-Yu; Ding, Cheng

2015-01-01

Two new coordination complexes with tetrazole heterocycle ligands bearing acetate groups, [Co(L) 2 ] n (1) and [Co 3 (L) 4 (N 3 ) 2 ·2MeOH] n (2) (L=tetrazole-1-acetate) have been synthesized and structurally characterized. Single crystal structure analysis shows that the cobalt-complex 1 has the 3D 3,6-connected (4 2 .6) 2 (4 4 .6 2 .8 8 .10)-ant topology. By introducing azide in this system, complex 2 forms the 2D network containing the [Co 3 ] units. And the magnetic properties of 1 and 2 have been studied. - Graphical abstract: The synthesis, crystal structure, and magnetic properties of the new coordination complexes with tetrazole heterocycle ligands bearing acetate groups are reported. - Highlights: • Two novel Cobalt(II) complexes with tetrazole acetate ligands were synthesized. • The magnetic properties of two complexes were studied. • Azide as co-ligand resulted in different structures and magnetic properties. • The new coordination mode of tetrazole acetate ligand was obtained.

Ultraviolet Irradiation of Pyrimidine in Interstellar Ice Analogs: Formation and Photo-Stability of Nucleobases

Science.gov (United States)

Nuevo, Michel; Milam, Stefanie N.; Sandford, Scott A.; Elsila, Jamie E.; Dworkin, Jason P.

2010-01-01

Astrochemistry laboratory experiments recently showed that molecules of prebiotic interest can potentially form in space, as supported by the detection of amino acids in organic residues formed by the UV photolysis of ices simulating interstellar and cometary environments (H2O, CO, CO2, CH3OH, NH3, etc.). Although the presence of amino acids in the interstellar medium (ISM) is still under debate, experiments and the detection of amino acids in meteorites both support a scenario in which prebiotic molecules could be of extraterrestrial origin, before they are delivered to planets by comets, asteroids, and interplanetary dust particles. Nucleobases, the informational subunits of DNA and RNA, have also been detected in meteorites, although they have not yet been observed in the ISM. Thus, these molecules constitute another family of prebiotic compounds that can possibly form via abiotical processes in astrophysical environments. Nucleobases are nitrogen-bearing cyclic aromatic species with various functional groups attached, which are divided into two classes: pyrimidines (uracil, cytosine, and thymine) and purines (adenine and guanine). In this work, we study how UV irradiation affects pyrimidine mixed in interstellar ice analogs (H2O, NH3, CH3OH). In particular, we show that the UV irradiation of H2O:pyrimidine mixtures leads to the production of oxidized compounds including uracil, and show that both uracil and cytosine are formed upon irradiation of H2O:NH3:pyrimidine mixtures. We also study the photostability of pyrimidine and its photoproducts formed during these experiments.

Topologically identical, but geometrically isomeric layers in hydrous α-, β-Rb[UO{sub 2}(AsO{sub 3}OH)(AsO{sub 2}(OH){sub 2})]·H{sub 2}O and anhydrous Rb[UO{sub 2}(AsO{sub 3}OH)(AsO{sub 2}(OH){sub 2})

Energy Technology Data Exchange (ETDEWEB)

Yu, Na; Klepov, Vladislav V. [Forschungszentrum Jülich GmbH, Institute for Energy and Climate Research (IEK-6), 52428 Jülich (Germany); Villa, Eric M. [Department of Chemistry, Creighton University, 2500 California Plaza, Omaha NE 68178 (United States); Bosbach, Dirk [Forschungszentrum Jülich GmbH, Institute for Energy and Climate Research (IEK-6), 52428 Jülich (Germany); Suleimanov, Evgeny V. [Department of Chemistry, Lobachevsky State University of Nizhny Novgorod, 603950 Nizhny Novgorod (Russian Federation); Depmeier, Wulf [Institut für Geowissenschaften, Universität zu Kiel, 24118 Kiel (Germany); Albrecht-Schmitt, Thomas E., E-mail: albrecht-schmitt@chem.fsu.edu [Department of Chemistry and Biochemistry, Florida State University, 102 Varsity Way, Tallahassee, FL 32306-4390 (United States); Alekseev, Evgeny V., E-mail: e.alekseev@fz-juelich.de [Forschungszentrum Jülich GmbH, Institute for Energy and Climate Research (IEK-6), 52428 Jülich (Germany); Institut für Kristallographie, RWTH Aachen University, 52066 Aachen (Germany)

2014-07-01

The hydrothermal reaction of uranyl nitrate with rubidium nitrate and arsenic (III) oxide results in the formation of polymorphic α- and β-Rb[UO{sub 2}(AsO{sub 3}OH)(AsO{sub 2}(OH){sub 2})]·H{sub 2}O (α-, β-RbUAs) and the anhydrous phase Rb[UO{sub 2}(AsO{sub 3}OH)(AsO{sub 2}(OH){sub 2})] (RbUAs). These phases were structurally, chemically and spectroscopically characterized. The structures of all three compounds are based upon topologically identical, but geometrically isomeric layers. The layers are linked with each other by means of the Rb cations and hydrogen bonding. Dehydration experiments demonstrate that water deintercalation from hydrous α- and β-RbUAs yields anhydrous RbUAs via topotactic reactions. - Graphical abstract: Three different layer geometries observed in the structures of Rb[UO{sub 2}(AsO{sub 3}OH)(AsO{sub 2}(OH){sub 2})] and α- and β- Rb[UO{sub 2}(AsO{sub 3}OH)(AsO{sub 2}(OH){sub 2})]·H{sub 2}O. Two different coordination environments of uranium polyhedra (types I and II) are shown schematically on the top of the figure. - Highlights: • Three new uranyl arsenates were synthesized from the hydrothermal reactions. • The phases consist of the topologically identical but geometrically different layers. • Topotactic transitions were observed in the processes of mono-hyrates dehydration.

Geology and geomorphology of Bear Lake Valley and upper Bear River, Utah and Idaho

Science.gov (United States)

Reheis, M.C.; Laabs, B.J.C.; Kaufman, D.S.

2009-01-01

Bear Lake, on the Idaho-Utah border, lies in a fault-bounded valley through which the Bear River flows en route to the Great Salt Lake. Surficial deposits in the Bear Lake drainage basin provide a geologic context for interpretation of cores from Bear Lake deposits. In addition to groundwater discharge, Bear Lake received water and sediment from its own small drainage basin and sometimes from the Bear River and its glaciated headwaters. The lake basin interacts with the river in complex ways that are modulated by climatically induced lake-level changes, by the distribution of active Quaternary faults, and by the migration of the river across its fluvial fan north of the present lake. The upper Bear River flows northward for ???150 km from its headwaters in the northwestern Uinta Mountains, generally following the strike of regional Laramide and late Cenozoic structures. These structures likely also control the flow paths of groundwater that feeds Bear Lake, and groundwater-fed streams are the largest source of water when the lake is isolated from the Bear River. The present configuration of the Bear River with respect to Bear Lake Valley may not have been established until the late Pliocene. The absence of Uinta Range-derived quartzites in fluvial gravel on the crest of the Bear Lake Plateau east of Bear Lake suggests that the present headwaters were not part of the drainage basin in the late Tertiary. Newly mapped glacial deposits in the Bear River Range west of Bear Lake indicate several advances of valley glaciers that were probably coeval with glaciations in the Uinta Mountains. Much of the meltwater from these glaciers may have reached Bear Lake via groundwater pathways through infiltration in the karst terrain of the Bear River Range. At times during the Pleistocene, the Bear River flowed into Bear Lake and water level rose to the valley threshold at Nounan narrows. This threshold has been modified by aggradation, downcutting, and tectonics. Maximum lake

Kinetics of 15NH4+ assimilation in Zea mays

International Nuclear Information System (INIS)

Magalhaes, J.R.; Ju, G.C.; Rich, P.J.; Rhodes, D.

1990-01-01

Comparative studies of 15 NH 4 + assimilation were undertaken with a GDH1-null mutant of Zea mays and a related (but not strictly isogenic) GDH1-positive wild type from which this mutant was derived. The kinetics of 15 NH 4 + assimilation into free amino acids and total reduced nitrogen were monitored in both roots and shoots of 2-week-old seedlings supplied with 5 millimolar 99% ( 15 NH 4 ) 2 SO 4 via the aerated root medium in hydroponic culture over a 24-h period. The GDH1-null mutant, with a 10- to 15-fold lower total root GDH activity in comparison to the wild type, was found to exhibit a 40 to 50% lower rate of 15 NH 4 + assimilation into total reduced nitrogen. The lower rates of 15 NH 4 + assimilation in the mutant was associated with lower rates of labeling of several free amino acids (including glutamate, glutamine-amino N, aspartate, asparagine-amino N, and alanine) in both roots and shoots of the mutant in comparison to the wild type. Qualitatively, these labeling kinetics appear consistent with a reduced flux of 15 N via glutamate in the GDH1-null mutant. However, the responses of the two genotypes to the potent inhibitor of glutamine synthetase, methionine sulfoximine, and differences in morphology of the two genotypes (particularly a lower shoot:root ratio in the GDH1-null mutant) urge caution in concluding that GDH1 is solely responsible for these differences in ammonia assimilation rate

Fabrication and properties of highly luminescent materials from Tb(OH)3-SiO2 and Tb(OH)3-SiO2:Eu3+ nanotubes

International Nuclear Information System (INIS)

Tran Thu Huong; Tran Kim Anh; Le Quoc Minh

2009-01-01

Luminescent nanomaterials with one-dimensional (1D) structures have attracted much attention due to their unique properties and potential applications in nanophotonics and nanobiophotonics. In this paper, we report a synthesis of terbium - hydroxide - at - silica Tb(OH) 3 -SiO 2 and Tb(OH) 3 -SiO 2 :Eu 3+ nanotubes. Terbium - hydroxide tubes were synthesized by soft template method. The size of the tubes can be controlled precisely and have outer diameters ranging from 80 to 120 nm, wall thickness of about 30 nm, and lengths ranging from 300 to 800 nm. To fabricate core/shell materials, the seed growth method is used. FESEM, X-ray diffraction, Raman spectra of Tb(OH) 3 and Tb(OH) 3 -SiO 2 nanotubes were investigated. The photoluminescence (PL) spectrum of Tb(OH) 3 under 325 nm excitation consists of four main peaks at 488, 542, 582, and 618 nm. Furthermore, a preliminary suggestion for the mechanism of growth of the Tb(OH) 3 nanotubes using the soft - template synthesis technique has been proposed. The PL intensity from Tb(OH) 3 -SiO 2 or Tb(OH) 3 -SiO 2 :Eu 3+ nanotubes is much stronger than that of Tb(OH) 3 .

State Space Formulation of Nonlinear Vibration Responses Collected from a Dynamic Rotor-Bearing System: An Extension of Bearing Diagnostics to Bearing Prognostics

OpenAIRE

Peter W. Tse; Dong Wang

2017-01-01

Bearings are widely used in various industries to support rotating shafts. Their failures accelerate failures of other adjacent components and may cause unexpected machine breakdowns. In recent years, nonlinear vibration responses collected from a dynamic rotor-bearing system have been widely analyzed for bearing diagnostics. Numerous methods have been proposed to identify different bearing faults. However, these methods are unable to predict the future health conditions of bearings. To exten...

Evaluation of bearing configurations using the single bearing tester in liquid nitrogen

Science.gov (United States)

Jett, T.; Hall, P.; Thom, R.

1991-01-01

Various bearing configurations were tested using the Marshall Space Flight Center single bearing tester with LN2 as the cryogenic coolant. The baseline was one Rocketdyne phase one high pressure oxidizer turbopump (HPOTP) pump end 45-mm bore bearing. The bearing configurations that were tested included a Salox/M cage configuration, a silicon nitride ball configuration, an elongated cage configuration, and a Bray 601 grease configuration.

Quadrupole hyperfine structure and splitting of Δ-levels in the microwave spectra of KOH, RbOH and CsOH in the 100 GHz region

International Nuclear Information System (INIS)

Kuijpers, P.; Dymanus, A.; Toerring, T.

1977-01-01

Hyperfine structure of rotational transitions of KOH, RbOH and CsOH in various v 2 - and l-states has been carefully measured in the 100 GHz range. From the observed splittings and broadenings information about quadrupole coupling constant (eqQ) of the K nucleus in KOH and about the spacing (Esub(Δ) - Esub(Σ)) between Σ and Δ levels in the vibrational spectrum of KOH, RbOH and CsOH has been derived. The measured value of the eqQ of KOH is close to that of KF. The separation between Σ and Δ levels is found to be rather similar for the group of the alkali hydroxides increasing gradually when progressing from LiOH to CsOH. (orig.) [de

Improvement of journal bearing operation at heavy misalignment using bearing flexibility and compliant liners

DEFF Research Database (Denmark)

Thomsen, Kim; Klit, Peder

2012-01-01

A flexure journal bearing design is proposed that will improve operational behaviour of a journal bearing at pronounced misalignment. Using a thermoelastohydrodynamic model, it is shown that the proposed flexure journal bearing has vastly increased the hydrodynamic performance compared to the stiff...... bearing when misaligned. The hydrodynamic performance is evaluated on lubricant film thickness, pressure and temperature. Furthermore, the influence of a compliant bearing liner is investigated and it is found that it increases the hydrodynamic performance when applied to a stiff bearing, whereas...... the liner has practically no influence on the flexure journal bearing's performance....

Investigation of Mg(OH)2 nanoparticles as an antibacterial agent

International Nuclear Information System (INIS)

Dong Chunxu; Cairney, John; Sun Qunhui; Maddan, Orville Lee; He Gaohong; Deng Yulin

2010-01-01

Our experimental results of using Mg(OH) 2 nanoparticles as an antibacterial agent are reported in this study. The antibacterial behavior of Mg(OH) 2 nanoparticles in liquid culture and in paper sheets was investigated. The colony forming units (CFU) counting and the headspace gas chromatography (HS-GC) measurement were used to determine the cell viability. Results indicate that Mg(OH) 2 nanoparticles are effective antibacterial agent against Escherichia coli (E. coli) and Burkholderia phytofirmans, and the OH - and Mg 2+ ions in Mg(OH) 2 water suspension were found not to be the reason for killing the bacteria. Mg(OH) 2 nanoparticles could be added directly to wood pulp to make paper sheets, whose antibacterial efficiency increased with the increase of the nanoparticle amount. The possible mechanism of antibacterial effect of Mg(OH) 2 nanoparticles is discussed.

Direct observation of OH production from the ozonolysis of olefins

Science.gov (United States)

Donahue, Neil M.; Kroll, Jesse H.; Anderson, James G.; Demerjian, Kenneth L.

Ozone olefin reactions may be a significant source of OH in the urban atmosphere, but current evidence for OH production is indirect and contested. We report the first direct observation of OH radicals from the reaction of ozone with a series of olefins (ethene, isoprene, trans-2-butene and 2,3 dimethyl-2-butene) in 4-6 torr of nitrogen. Using LIF to directly observe the steady-state of OH produced by the initial ozone-olefin reaction and subsequently destroyed by the OH-olefin reaction, we are able to establish OH yields broadly consistent with indirect values. The identification of the OH is unequivocal, and there is no indication that it is produced by a secondary process. To support these observations, we present a complete ab-initio potential energy surface for the O3-ethene reaction, extending from the reactants to available products.

NH4SH and cloud cover in the atmospheres of the giant planets

Science.gov (United States)

Ibragimov, K. Iu.; Solodovnik, A. A.

1991-02-01

The probability of the formation of NH4SH and (NH4)2S is examined on the basis of the Le Chatelier principle. It is shown that it is very doubtful if NH4SH can be created in the atmospheres of the giant planets in quantities sufficient for cloud formation. Thus (NH4)2S is considered as a more likely candidate for cloud formation in the atmospheres of these planets, inasmuch as the conditions for its production there are more favorable.

Pressure induced polymorphism in ammonium azide (NH{sub 4}N{sub 3})

Energy Technology Data Exchange (ETDEWEB)

Medvedev, S.A., E-mail: s.medvedev@mpic.de [Max-Planck-Institute for Chemistry, Postfach 3060, D-55020 Mainz (Germany); Institute fuer Anorganische und Analytische Chemie, Johannes Gutenberg-Universitaet, D-55099 Mainz (Germany); Eremets, M.I. [Max-Planck-Institute for Chemistry, Postfach 3060, D-55020 Mainz (Germany); Evers, J.; Klapoetke, T.M. [Energetic Materials Research, Ludwig-Maximilian University Munich (LMU), Butenandtstrasse 5-13(D), D-81377 Munich (Germany); Palasyuk, T. [Max-Planck-Institute for Chemistry, Postfach 3060, D-55020 Mainz (Germany); Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw (Poland); Trojan, I.A. [Max-Planck-Institute for Chemistry, Postfach 3060, D-55020 Mainz (Germany)

2011-07-28

Graphical abstract: Polymorph phase transition is observed in NH{sub 4}N{sub 3} at {approx}3 GPa by pressure dependent Raman studies. The strength of hydrogen bond appears to be modified at the phase transition as illustrated by dependence of N-H stretching frequency on pressure shown on figure. Highlights: {yields} Ammonium azide (NH{sub 4}N{sub 3}) studied at high pressures by Raman spectroscopy. {yields} Phase transition is observed at pressure {approx}3 GPa. {yields} Strength of hydrogen bond appears to be modified at the phase transition. {yields} NH{sub 4}N{sub 3} remain in molecular form up to pressures above 50 GPa. - Abstract: Pressure-dependent Raman spectroscopy studies reveal polymorph phase transition in simple molecular ionic crystal NH{sub 4}N{sub 3} at pressure {approx}3 GPa unobserved by recent abinitio evolutionary structure searches. Hydrogen bonding is spectroscopically evident in both low- and high-pressure phases. The strength of hydrogen bond appears to be modified at the phase transition: in the low-pressure phase NH{sub 4}N{sub 3} behaves as system with very strong hydrogen bonding whereas changes of spectra with pressure in the high-pressure phase are indicative of weak or medium-strength hydrogen bonds. The high pressure phase is most likely thermodynamically stable at least up to pressure {approx}55 GPa contradicting the abinitio studies predicting transformation of NH{sub 4}N{sub 3} to nonmolecular hydronitrogen solid at 36 GPa.

Nuclear genomic sequences reveal that polar bears are an old and distinct bear lineage.

Science.gov (United States)

Hailer, Frank; Kutschera, Verena E; Hallström, Björn M; Klassert, Denise; Fain, Steven R; Leonard, Jennifer A; Arnason, Ulfur; Janke, Axel

2012-04-20

Recent studies have shown that the polar bear matriline (mitochondrial DNA) evolved from a brown bear lineage since the late Pleistocene, potentially indicating rapid speciation and adaption to arctic conditions. Here, we present a high-resolution data set from multiple independent loci across the nuclear genomes of a broad sample of polar, brown, and black bears. Bayesian coalescent analyses place polar bears outside the brown bear clade and date the divergence much earlier, in the middle Pleistocene, about 600 (338 to 934) thousand years ago. This provides more time for polar bear evolution and confirms previous suggestions that polar bears carry introgressed brown bear mitochondrial DNA due to past hybridization. Our results highlight that multilocus genomic analyses are crucial for an accurate understanding of evolutionary history.

Effects of optical diagnostic techniques on the accuracy of laminar flame speeds measured from Bunsen flames: OH* chemiluminescence, OH-PLIF and acetone/kerosene-PLIF

Science.gov (United States)

Wu, Yi; Modica, Vincent; Yu, Xilong; Li, Fei; Grisch, Frédéric

2018-01-01

The effects of optical diagnostic techniques on the accuracy of laminar flame speed measured from Bunsen flames were investigated. Laminar flame speed measurements were conducted for different fuel/air mixtures including CH4/air, acetone/air and kerosene (Jet A-1)/air in applying different optical diagnostic techniques, i.e. OH* chemiluminescence, OH-PLIF and acetone/kerosene-PLIF. It is found that the OH* chemiluminescence imaging technique cannot directly derive the location of the outer edge of the fresh gases and it is necessary to correct the position of the OH* peak to guarantee the accuracy of the measurements. OH-PLIF and acetone/kerosene-PLIF respectively are able to measure the disappearance of the fresh gas contour and the appearance of the reaction zone. It shows that the aromatic-PLIF technique gives similar laminar flame speed values when compared with those obtained from corrected OH* chemiluminescence images. However, discrepancies were observed between the OH-PLIF and the aromatic-PLIF techniques, in that OH-PLIF slightly underestimates laminar flame speeds by up to 5%. The difference between the flame contours obtained from different optical techniques are further analysed and illustrated with 1D flame structure simulation using detailed kinetic mechanisms.

Study of various NH4+/NO3- mixtures for enhancing growth of potatoes

Science.gov (United States)

Cao, W.; Tibbitts, T. W.

1993-01-01

Two experiments were conducted to determine the effects of various NH4(+)-N/NO3(-)-N percentages on growth and mineral concentrations in potato (Solanum tuberosum L.) plants using a non-recirculating nutrient film system in a controlled environment. The first experiment included six NH4(+)-N/NO3(-)-N percentages at 0/100, 20/80, 40/60, 60/40, 80/20, and 100/0 with the same total N concentration of 4 mM. The second experiment included six NH4(+)-N/NO3(-)-N percentages at 0/100, 4/96, 8/92, 12/88, 16/84, and 20/80 again with the same total N of 4 mM. In each experiment, plants were harvested 35 days after transplanting when tubers had been initiated and started to enlarge. Dry weights of shoots, tubers, and whole plant at the harvest were increased significantly with all mixed nitrogen treatments as compared with single NH4+ or NO3- form. The enhanced growth with mixed nitrogen was greatest at 8% to 20% NH4(+)-N. Also, the concentrations and accumulation of total N in the shoots and roots were greater with mixed nitrogen than with separate NH4+ or NO3- nutrition. With NH4+ present in the solutions, the concentrations of P and Cl in the shoots were increased compared to NO3- alone, whereas the tissue concentrations of Ca and Mg were decreased. It was concluded that nitrogen fertilization provided with combined NH4+ and NO3- forms, even at small proportions of NH4+, can enhance nitrogen uptake and productivity in potato plants.

NH4+ protects tomato plants against Pseudomonas syringae by activation of systemic acquired acclimation.

Science.gov (United States)

Fernández-Crespo, Emma; Scalschi, Loredana; Llorens, Eugenio; García-Agustín, Pilar; Camañes, Gemma

2015-11-01

NH4 (+) nutrition provokes mild toxicity by enhancing H2O2 accumulation, which acts as a signal activating systemic acquired acclimation (SAA). Until now, induced resistance mechanisms in response to an abiotic stimulus and related to SAA were only reported for exposure to a subsequent abiotic stress. Herein, the first evidence is provided that this acclimation to an abiotic stimulus induces resistance to later pathogen infection, since NH4 (+) nutrition (N-NH4 (+))-induced resistance (NH4 (+)-IR) against Pseudomonas syringae pv tomato DC3000 (Pst) in tomato plants was demonstrated. N-NH4 (+) plants displayed basal H2O2, abscisic acid (ABA), and putrescine (Put) accumulation. H2O2 accumulation acted as a signal to induce ABA-dependent signalling pathways required to prevent NH4 (+) toxicity. This acclimatory event provoked an increase in resistance against later pathogen infection. N-NH4 (+) plants displayed basal stomatal closure produced by H2O2 derived from enhanced CuAO and rboh1 activity that may reduce the entry of bacteria into the mesophyll, diminishing the disease symptoms as well as strongly inducing the oxidative burst upon Pst infection, favouring NH4 (+)-IR. Experiments with inhibitors of Put accumulation and the ABA-deficient mutant flacca demonstrated that Put and ABA downstream signalling pathways are required to complete NH4 (+)-IR. The metabolic profile revealed that infected N-NH4 (+) plants showed greater ferulic acid accumulation compared with control plants. Although classical salicylic acid (SA)-dependent responses against biotrophic pathogens were not found, the important role of Put in the resistance of tomato against Pst was demonstrated. Moreover, this work revealed the cross-talk between abiotic stress acclimation (NH4 (+) nutrition) and resistance to subsequent Pst infection. © The Author 2015. Published by Oxford University Press on behalf of the Society for Experimental Biology.

Natural Rosin-based Phosphate Diester Surfactant Assisted One-step Synthesis of 3D Flowerlikeβ-Ni(OH)2/γ-Ni(OH)2 Composite Nano-microspheres

Institute of Scientific and Technical Information of China (English)

BoShi Wu; Juan Li; ChunRui Han; Feng Xu

2018-01-01

Self-assembled uniform 3Dflowerlikeβ-Ni(OH)2/g-Ni(OH)2composite nano-microspheres with hollow interiors were successfully synthesized via a facile aqueous-ethanol mixed solvothermal method, using nickel sulfate as a precursor, urea as a precipitant, and dehydroabietic based phosphate diester sodium (DDPDS) as a surfactant. The prepared 3D flowerlikeβ-Ni(OH)2/g-Ni(OH)2composite nano-microspheres were tested as supercapacitors in a two-electrode cell with 6 mol/L KOH electrolyte. In addition, the influence of DDPDS concentration on the morphology and size of 3Dflowerlikeβ-Ni(OH)2/g-Ni(OH)2composite nano-microspheres was studied at 180℃. X-ray diffraction (XRD), scanning electron microscopy (SEM), BET(Brunauer, Emmett and Teller)techniques, and equity default swap (EDS) were used to characterize the structure, morphology, and size of the as-prepared samples. Moreover, a possible formation mechanism of the 3Dflowerlikeβ-Ni(OH)2/g-Ni(OH)2composite nano-microspheres was proposed based on the effects of DDPDS concentrationand reaction time. The surfactant micelles were used as soft templates to induce the self-assembly of nanosheets. The crystallinity of the 3D flowerlikeβ-Ni(OH)2/g-Ni(OH)2composite nano-microspheres improved with the increase of DDPDS concentration, and the morphology and size of synthetic nano-microspheres could be controlled.

Assessment of the Influence of Soil Characteristics and Hydrocarbon Fuel Cocontamination on the Solvent Extraction of Perfluoroalkyl and Polyfluoroalkyl Substances.

Science.gov (United States)

Mejia-Avendaño, Sandra; Munoz, Gabriel; Sauvé, Sébastien; Liu, Jinxia

2017-02-21

Sites impacted by the use of aqueous film-forming foams (AFFFs) present elevated concentrations of perfluoroalkyl and polyfluoroalkyl substances (PFAS). The characterization of the PFAS contamination at such sites may be greatly complicated by the presence of hydrocarbon cocontaminants and by the large variety of PFAS potentially present in AFFFs. In order to further a more comprehensive characterization of AFFF-contaminated soils, the solvent extraction of PFAS from soil was studied under different conditions. Specifically, the impact of soil properties (textural class, organic matter content) and the presence of hydrocarbon contamination (supplemented in the form of either diesel or crude oil) on PFAS recovery performance was evaluated for two extraction methods [methanol/sodium hydroxide (MeOH/NaOH) and methanol/ammonium hydroxide (MeOH/NH 4 OH)]. While both methods performed satisfactorily for perfluoroalkyl acids and fluorotelomer sulfonates, the extraction of newly identified surfactants with functionalities such as betaine and quaternary ammonium was improved with the MeOH/NaOH based method. The main factors that were found to influence the extraction efficiency were the soil properties; a high organic matter or clay content was observed to negatively affect the recovery of the newly identified compounds. While the MeOH/NaOH solvent yielded more efficient recovery rates overall, it also entailed the disadvantage of presenting higher detection limits and substantial matrix effects at the instrumental analysis stage, requiring matrix-matched calibration curves. The results discussed herein bear important implications for a more comprehensive and reliable environmental monitoring of PFAS components at AFFF-impacted sites.

Supramolecular Switches Based on the Guanine–Cytosine (GC) Watson–Crick Pair: Effect of Neutral and Ionic Substituents

NARCIS (Netherlands)

Guerra, C.F.; van der Wijst, T.; Bickelhaupt, F.M.

2006-01-01

We have theoretically analyzed Watson–Crick guanine–cytosine (GC) base pairs in which purine-C8 and/or pyrimidine-C6 positions carry a substituent X = NH−, NH2, NH3+ (N series), O−, OH, or OH2+ (O series), using the generalized gradient approximation (GGA) of density functional theory at the

Neutral and Ionized Hydrides in Star-forming Regions. Observations with Herschel/HIFI

DEFF Research Database (Denmark)

O. Benz, Arnold; Bruderer, Simon; F. van Dishoeck, Ewine

2013-01-01

of OH, CH, NH, SH and their ions OH+, CH+, NH+, SH+, H2O+, and H3O+ were observed in star-forming regions by the HIFI spectrometer onboard the Herschel Space Observatory. Molecular column densities are derived from observed ground-state lines, models, or rotational diagrams. We report here on two...

Acid mine water neutralisation with ammonium hydroxide and ...

African Journals Online (AJOL)

This study showed that NH4OH can be used for treatment of acid mine drainage rich in sulphates and NH4OH can be recycled in the process. Hydrated lime treatment resulted in removal of the remaining ammonia using a rotary evaporator. Keywords: acid mine water, ammonium hydroxide, barium hydroxide, sulphate ...

Heterogeneous processing of biomass burning aerosol proxies by OH radicals for a wide range of OH concentrations and detection of volatilization products

Science.gov (United States)

Slade, J. H.; Knopf, D. A.

2012-12-01

Biomass burning aerosol (BBA) constitutes the majority of primary organic aerosol found in the atmosphere, with emission rates comparable to fossil-fuel burning. BBA affects earth's radiative budget directly through absorption and scattering of radiation or indirectly by modifying cloud radiative properties, and impacts air quality. Quantifying BBA source strength and thus its effects on air quality, human health, and climate can be difficult since these organic particles can chemically transform during atmospheric transport, a process also termed aging, due to heterogeneous reactions with oxidants and radicals such as OH. In this work we investigate the reactive uptake of OH radicals by typical BBA compounds that also serve as molecular markers for source apportionment studies. Organic substrates of cellulose pyrolysis products such as levoglucosan (1,6-anhydro-β-glucopyranose, C6H10O5), resin acids such as abietic acid (1-phenanthrenecarboxylic acid, C20H30O2), and lignin decomposition products such as 5-nitroguaiacol (2-methoxy-5-nitrophenol, C7H7NO4) have been exposed to a wide range of OH concentrations (~107-1011 cm-3), in presence of O2 in a rotating wall flow reactor operated at 2-6 mbar coupled to a custom built chemical ionization mass spectrometer (CIMS). OH radicals were generated through H2 dissociation in an Evenson microwave resonant cavity operated at 2.45 GHz followed by reaction with O2 or NO2. In addition, potential volatilization of organic material due to heterogeneous oxidation by OH has been determined in-situ by monitoring the volatile organic compounds using a high resolution-proton transfer reaction-time of flight-mass spectrometer (HR-PTR-ToF-MS). The volatilization studies are conducted at 1 atm and OH is generated by O3 photolysis in the presence of H2O vapor and quantified using a photochemical box model as well as through reaction with a known concentration of isoprene (2-methyl-1,3-butadiene, C5H8). Reactive uptake validation

Vibration model of rolling element bearings in a rotor-bearing system for fault diagnosis

Science.gov (United States)

Cong, Feiyun; Chen, Jin; Dong, Guangming; Pecht, Michael

2013-04-01

Rolling element bearing faults are among the main causes of breakdown in rotating machines. In this paper, a rolling bearing fault model is proposed based on the dynamic load analysis of a rotor-bearing system. The rotor impact factor is taken into consideration in the rolling bearing fault signal model. The defect load on the surface of the bearing is divided into two parts, the alternate load and the determinate load. The vibration response of the proposed fault signal model is investigated and the fault signal calculating equation is derived through dynamic and kinematic analysis. Outer race and inner race fault simulations are realized in the paper. The simulation process includes consideration of several parameters, such as the gravity of the rotor-bearing system, the imbalance of the rotor, and the location of the defect on the surface. The simulation results show that different amplitude contributions of the alternate load and determinate load will cause different envelope spectrum expressions. The rotating frequency sidebands will occur in the envelope spectrum in addition to the fault characteristic frequency. This appearance of sidebands will increase the difficulty of fault recognition in intelligent fault diagnosis. The experiments given in the paper have successfully verified the proposed signal model simulation results. The test rig design of the rotor bearing system simulated several operating conditions: (1) rotor bearing only; (2) rotor bearing with loader added; (3) rotor bearing with loader and rotor disk; and (4) bearing fault simulation without rotor influence. The results of the experiments have verified that the proposed rolling bearing signal model is important to the rolling bearing fault diagnosis of rotor-bearing systems.

Polar bears at risk

Energy Technology Data Exchange (ETDEWEB)

Norris, S.; Rosentrater, L.; Eid, P.M. [WWF International Arctic Programme, Oslo (Norway)

2002-05-01

Polar bears, the world's largest terrestrial carnivore, spend much of their lives on the arctic sea ice. This is where they hunt and move between feeding, denning, and resting areas. The world population, estimated at 22,000 bears, is made up of 20 relatively distinct populations varying in size from a few hundred to a few thousand animals. About 60 per cent of all polar bears are found in Canada. In general, the status of this species is stable, although there are pronounced differences between populations. Reductions in the extent and thickness of sea ice has lead the IUCN Polar Bear Specialist Group to describe climate change as one of the major threats facing polar bears today. Though the long-term effects of climate change will vary in different areas of the Arctic, impacts on the condition and reproductive success of polar bears and their prey are likely to be negative. Longer ice-free periods resulting from earlier break-up of sea ice in the spring and later formation in the fall is already impacting polar bears in the southern portions of their range. In Canada's Hudson Bay, for example, bears hunt on the ice through the winter and into early summer, after which the ice melts completely, forcing bears ashore to fast on stored fat until freeze-up in the fall. The time bears have on the ice to hunt and build up their body condition is cut short when the ice melts early. Studies from Hudson Bay show that for every week earlier that ice break-up occurs, bears will come ashore 10 kg lighter and in poorer condition. It is likely that populations of polar bears dividing their time between land and sea will be severely reduced and local extinctions may occur as greenhouse gas emissions continue to rise and sea ice melts. Expected changes in regional weather patterns will also impact polar bears. Rain in the late winter can cause maternity dens to collapse before females and cubs have departed, thus exposing occupants to the elements and to predators. Such

Detection of OH radicals from IRAS sources

International Nuclear Information System (INIS)

Lewis, B.M.; Eder, J.; Terzian, Y.

1985-01-01

An efficient method for detecting new OH/infrared stars is to begin with IRAS source positions, selected for appropriate infrared colours, and using radio-line observations to confirm the OH properties. The authors demonstrate the validity of this approach here, using the Arecibo 305 m radio-telescope to confirm the 1,612 MHz line observations of sources in IRAS Circulars 8 and 9; the present observations identify 21 new OH/infrared stars. The new sources have weaker 1,612 MHz fluxes, bluer (60-25) μm colours and a smaller mean separation between the principal emission peaks than previous samples. (author)

Transient Vibration Prediction for Rotors on Ball Bearings Using Load-dependent Non-linear Bearing Stiffness

Science.gov (United States)

Fleming, David P.; Poplawski, J. V.

2002-01-01

Rolling-element bearing forces vary nonlinearly with bearing deflection. Thus an accurate rotordynamic transient analysis requires bearing forces to be determined at each step of the transient solution. Analyses have been carried out to show the effect of accurate bearing transient forces (accounting for non-linear speed and load dependent bearing stiffness) as compared to conventional use of average rolling-element bearing stiffness. Bearing forces were calculated by COBRA-AHS (Computer Optimized Ball and Roller Bearing Analysis - Advanced High Speed) and supplied to the rotordynamics code ARDS (Analysis of Rotor Dynamic Systems) for accurate simulation of rotor transient behavior. COBRA-AHS is a fast-running 5 degree-of-freedom computer code able to calculate high speed rolling-element bearing load-displacement data for radial and angular contact ball bearings and also for cylindrical and tapered roller beatings. Results show that use of nonlinear bearing characteristics is essential for accurate prediction of rotordynamic behavior.

Impact of Precipitants on the Structure and Properties of Fe-Co-Ce Composite Catalysts

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Yongli Zhang