Thermal decomposition of double selenates of lanthanides (III), yttrium (III) and ammonium

International Nuclear Information System (INIS)

Crespi, M.S.

1989-01-01

Double selenates of lanthanides, yttrium and ammonium were prepared by treating mixtures of simple selenates with equimolar amounts and then dried in a vacuum desiccator containing anhydrous calcium chloride, protected from light. The compounds were studied using the conventional analytical methods such as infrared absorption spectra, X-ray diffraction, differential thermal analysis (DTA), and thermogravimetry (TG). (author)

The intensity of tyrosine nitration is associated with selenite and selenate toxicity in Brassica juncea L.

Science.gov (United States)

Molnár, Árpád; Feigl, Gábor; Trifán, Vanda; Ördög, Attila; Szőllősi, Réka; Erdei, László; Kolbert, Zsuzsanna

2018-01-01

Selenium phytotoxicity involves processes like reactive nitrogen species overproduction and nitrosative protein modifications. This study evaluates the toxicity of two selenium forms (selenite and selenate at 0µM, 20µM, 50µM and 100µM concentrations) and its correlation with protein tyrosine nitration in the organs of hydroponically grown Indian mustard (Brassica juncea L.). Selenate treatment resulted in large selenium accumulation in both Brassica organs, while selenite showed slight root-to-shoot translocation resulting in a much lower selenium accumulation in the shoot. Shoot and root growth inhibition and cell viability loss revealed that Brassica tolerates selenate better than selenite. Results also show that relative high amounts of selenium are able to accumulate in Brassica leaves without obvious visible symptoms such as chlorosis or necrosis. The more severe phytotoxicity of selenite was accompanied by more intense protein tyrosine nitration as well as alterations in nitration pattern suggesting a correlation between the degree of Se forms-induced toxicities and nitroproteome size, composition in Brassica organs. These results imply the possibility of considering protein tyrosine nitration as novel biomarker of selenium phytotoxicity, which could help the evaluation of asymptomatic selenium stress of plants. Copyright © 2017 Elsevier Inc. All rights reserved.

Uptake and Distribution of Added Selenite and Selenate by Barley and Red Clover as Influenced by Sulphur

DEFF Research Database (Denmark)

Nielsen, Gunnar Gissel

1973-01-01

The uptake of added Se from selenite and selenate by barley and red clover was investigated in a pot experiment. Much more of selenate than of selenite was taken up but the Se concentrations in the plants declined more with time when selenate was the source. Increasing sulphate addition to the soil...

Growth of Cu(In,Al)(Se,S)2 thin films by selenization and sulfurization for a wide bandgap absorber

International Nuclear Information System (INIS)

Fujiwara, C.; Kawasaki, Y.; Sato, T.; Sugiyama, M.; Chichibu, S.F.

2010-01-01

Full text : Chalcopyrite structure Cu(In 1 .xAlx)(S y Se 1 -y) 2 (CIASS) alloys are attracting attention as promising candidates for the light-absorbing medium of high conversion efficiency, low cost, and lightweight solar cells. In addition, according to the wide variation in the bandgap energy (1.0-3.5eV), multiple-junction or tandem solar cells able to be fabricated using CIASS films of different compositions, x and y. In fact, several research groups have recently fabricated Cu(In,Al)Se 2 -based solar cells, and a high μ of 16.9 percent has been demonstrated. The sulfurization following selenization of Cu(In,Ga)Se2 (CIGS) films is believed to be promising for bandgap engineering of absorber material. Furthermore, it has been reported that the controlled incorporation of sulfur into CIGS films reduces the carrier recombination in the space charge region due to the deep trap states. Therefore, the sulfurization following selenization is expected to be used as a method of growth of CIASS films. However, sulfurization condition following selenization for obtaining CIASS films has not been clarified. The crystal growth of CIASS must be studied for solar cell applications. In this study, the advantages of using sulfurization for the growth of CIASS will be presented. Cu-In-Al precursors were selenized using diethylselenide (DESe) at 515-570 degrees Celsium for 60- 90 min under atmospheric pressure. The flow rates of DESe and N 2 carrier gases were 35 imol/min and 2 L/min, respectively. The films were then sulfurized at 550 degrees Celsium using S vapor. These films were characterized by SEM, EDX, XRD, and PL measurements. Using the selenization and sulfurization technique, polycrystalline Cu(In,Al)Se 2 , CuIn(Se,S) 2 , CuInS 2 films with thickness of approximately 2.0 im were formed without additional annealing. The films adhered well to the Mo/SLG substrate, which was confirmed by the peeling test. Phase separations, i.e. distinct peaks corresponding to CuInSe 2

Selen og vitamin E til svin

DEFF Research Database (Denmark)

Nielsen, H. E.; Danielsen, V.; Nielsen, Gunnar Gissel

1975-01-01

, kan der let opstå selenmangel. Vitamin E kan i nogen grad erstatte selen, men kun indenfor visse grænser. De senere års erfaringer har tydeligt vist, at der ofte opstår selenmangel, selvom der findes rigeligt E-vitamin i foderet. Resultaterne fra dette forsøg tyder på, at en nedsættelse af...

Dehydration-driven evolution of topological complexity in ethylamonium uranyl selenates

Energy Technology Data Exchange (ETDEWEB)

Gurzhiy, Vladislav V., E-mail: vladgeo17@mail.ru [Department of Crystallography, St. Petersburg State University, University Emb. 7/9, 199034 St. Petersburg (Russian Federation); Krivovichev, Sergey V. [Department of Crystallography, St. Petersburg State University, University Emb. 7/9, 199034 St. Petersburg (Russian Federation); Tananaev, Ivan G. [Far Eastern Federal University, Suhanova st. 8, 690950 Vladivostok (Russian Federation)

2017-03-15

Single crystals of four novel uranyl selenate and selenite-selenate oxysalts with protonated ethylamine molecules, (C{sub 2}H{sub 8}N){sub 2}[(UO{sub 2})(SeO{sub 4}){sub 2}(H{sub 2}O)](H{sub 2}O) (I), (C{sub 2}H{sub 8}N){sub 3}[(UO{sub 2})(SeO{sub 4}){sub 2}(HSeO{sub 4})] (II), (C{sub 2}H{sub 8}N)[(UO{sub 2})(SeO{sub 4})(HSeO{sub 3})] (III), and (C{sub 2}H{sub 8}N)(H{sub 3}O)[(UO{sub 2})(SeO{sub 4}){sub 2}(H{sub 2}O)] (IV) have been prepared by isothermal evaporation from aqueous solutions. Uranyl-containing 1D and 2D units have been investigated using topological approach and information-based complexity measurements that demonstrate the evolution of structural units and the increase of topological complexity with the decrease of H{sub 2}O content. - Graphical abstract: Single crystals of four novel uranyl selenate and selenite-selenate oxysalts with protonated ethylamine molecules have been prepared by isothermal evaporation from aqueous solutions. Structural analysis and information-based topological complexity calculations points to the possible sequence of crystalline phases formation, showing both topological and structural branches of evolution. - Highlights: • Single crystals of four novel uranyl oxysalts were prepared by evaporation method. • The graph theory was used for investigation of topologies of structural units. • Dehydration processes drives the evolution of topological complexity of 1D and 2D structural units.

Modeling selenate adsorption behavior on oxides, clay minerals, and soils using the triple layer model

Science.gov (United States)

Selenate adsorption behavior was investigated on amorphous aluminum oxide, amorphous iron oxide, goethite, clay minerals: kaolinites, montmorillonites, illite, and 18 soil samples from Hawaii, and the Southwestern and the Midwestern regions of the US as a function of solution pH. Selenate adsorpti...

The chemical consequences of thermal neutron capture in alkali selenates

International Nuclear Information System (INIS)

Duplatre, G.; Vargas, J.I.

1977-01-01

The initial retention of the SeO 4 2- ion after thermal neutron capture has been studied in various matrices by chemical analysis. A comparison between the thermal behaviour of the chemically analyzed Sesup(IV) and the disappearance of the E.P.R. species SeO 3 - and SeO 4 3- showed that the retention fraction would include all species with oxidation state higher or equal to VI. The retentions observed in the different matrices show the existence of four families with respective retentions of: 2.6%[K 2 SeO 4 diluted in (NH 4 ) 2 SO 4 ], 9.2% [anhydrous and hydrated Li and Ca selenates; K 2 SeO 4 diluted in NaIO 3 ; Se + implanted in K 2 SeO 4 ; Triglycine selenate], 21.5% [K 2 SeO 4 diluted in KNO 3 , K 2 SO 4 , Na 2 WO 4 and Na 2 WO 4 .2H 2 O] and 32.0% [Na,K and Cs selenates]. Whereas chemical considerations may be invoked for the (NH 4 ) 2 SO 4 matrix, a mechanical model is proposed for the three other groups. (author)

A novel selenization technique for fabrication of superconducting FeSex thin film

International Nuclear Information System (INIS)

Chai Qinglin; Tu Hailing; Hua Zhiqiang; Wang Lei; Qu Fei

2011-01-01

A novel selenization technique was applied to prepare superconducting FeSe x films with pre-set FeS films. The combination of reactive sputtering deposition with elemental diffusion technique would extend to prepare films of other iron-based superconductors. The results of transport measurement got close or greater than that of previous reports. T c,onset and T c,0 got to 10.2 K and 4 K respectively. We believe that increase of the content of Fe 7 Se 8 could not only reduce T c but also slow down the decline of resistivity. A combinative method with reactive sputtering deposition and selenization technique was applied to prepare superconducting FeSe x films on LaAlO 3 substrates successfully. The influence of selenizing temperature on film components was studied. FeSe 0.96 and FeSe films had similar and good performances in transport measurement but little difference in magnetic property. The critical onset temperature got to 11.2 K and T c,0 got to 4 K approximately. X-ray diffraction, energy dispersive spectroscopy and scanning electron microscopy were used to analyze the ratio of constituents and morphology of several selenized films. FeSe x film had a porous structure on surface and no well preferred orientation, which were confirmed to have little influence on superconducting properties.

SELENE - Self-Forming Extensible Lunar EVA Network, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — The overall objective of this research effort (Phase I and Phase II) by Scientific Systems Company, Inc. and BBN Technologies is to develop the SELENE network --...

Selenate as a novel ligand for keplerate chemistry. New {W72Mo60} keplerates with selenates inside the cavity.

Science.gov (United States)

Korenev, Vladimir S; Abramov, Pavel A; Vicent, Cristian; Zhdanov, Artem A; Tsygankova, Alphiya R; Sokolov, Maxim N; Fedin, Vladimir P

2015-05-21

The synthesis and characterization of three novel keplerate-type compounds containing the {W72Mo60} mixed-metal core are reported. Complexes (NH4)72[{W6O21(H2O)6}12{Mo2O4(SeO4)}30]·150H2O·6(NH4)2SeO4 (1a) and (NH4)25(NH2Me2)47[{W6O21(H2O)6}12{Mo2O4(SeO4)}30]·130H2O·3(NH4)2SeO4 (1b) were prepared by ligand substitution from the acetate anionic complex [{W6O21(H2O)5(CH3COO)0.5}12{Mo2O4(CH3COO)}30](48-) and selenate. The selenate anions in keplerate ions [{W6O21(H2O)6}12{Mo2O4(SeO4)}30](72-) are very labile and easily aquate with the formation of [{W6O21(H2O)6}12{Mo2O4}30(SeO4)20(H2O)20](52-), which was isolated as (NH4)20(NH2Me2)32[{W6O21(H2O)6}12{Mo2O4}30(SeO4)20(H2O)20]·150H2O (2) and structurally characterized. In the crystal structure of 2 selenate has several coordination modes, preferentially bonding to the {Mo2O4}(2+) units, and, additionally, to the {(W)W5} pentagonal blocks. The compounds have been characterized by elemental analysis, Raman, IR and (77)Se NMR spectroscopy, and by ESI mass spectrometry. Capillary electrophoresis was used for characterization of keplerates in solution for the first time.

Preliminary observations on the effects of selenate on the development of the embryonic skate, Raja eglanteria

Science.gov (United States)

Conrad, G. W.; Luer, C. A.; Paulsen, A. Q.; Funderburgh, J. L.; Spooner, B. S. (Principal Investigator)

1993-01-01

Morphogenesis of the clearnose skate, Raja eglanteria, was not significantly inhibited as a result of 7 days of exposure to 1-2 mM selenate in the sea water during Days 59-69 of embryonic development (hatching would normally have occurred at 82 +/- 4 days of incubation). Although corneal transparency appeared normal in the eye, preliminary measurements of the thickness of Bowman's layer of the cornea suggested that it was significantly thinner in the corneas of embryos exposed to 1-2 mM selenate. Selenate is an ion reported to inhibit sulfation of glycosaminoglycans in connective tissue.

Potentiometric titration of selenic and telluric acids with titanium(III) chloride in nonaqueous solvents

International Nuclear Information System (INIS)

Yoshimura, Chozo; Miyamoto, Kiyoshige

1985-01-01

Selenic and Telluric acids were titrated potentiometrically with titanium(III) chloride solution by using Pt-Cu · Hg bimetallic electrodes in nonaqueous solvents such as N, N-dimethyl-formamide (DMF), dimethyl sulfoxide (DMSO), isopropyl alcohol (IPA) and the mixtures of these solvents. It was found that selenic and telluric acids were titrated directly at room temperature in DMF solution without hydrochloric acid. The molar ratios of selenic and telluric acids to titanium(III) chloride was 1 : 6. However, the corresponding reactions to SeO 4 2- → SeO 3 2- or TeO 4 2- → TeO 3 2- were not confirmed in the titration curve in DMF. In the titration of selenic acid in mixed solvents of DMF and IPA in 1 : 1 or 1 : 2 ratio, two steps were observed. The first and the second steps were appeared on the titration curve at molar ratios of 1 : 2 and 1 : 6, respectively. It was interpreted that the first step corresponded to the intermediate reaction of SeO 4 2- → SeO 3 2- . Mixed solution of selenic and telluric acids were determined by the proposed method. Three steps were observed on the titration curve. It was interpreted that the first, second and third steps corresponded to the reaction of SeO 4 2- → SeO 3 2- , SeO 3 2- → Se(0), and TeO 4 2- → Te(0), respectively. Less than 5 % of water gave no influence on the titration. (author)

The influence of temperature on selenate adsorption by goethite

Energy Technology Data Exchange (ETDEWEB)

Kersten, M.; Vlasova, N. [Mainz Univ. (Germany). Geosciences Inst.

2013-08-01

Acid-base batch titration data up to 75 C were used to constrain a temperature-dependent 1-pK basic Stern model of the surface protonation reactions of goethite. Experimental data for the temperature dependence of pH{sub PZC} (as determined using the two-term Van't Hoff extrapolation) yielded a negative value of -44.9 kJ/mol for the surface protonation enthalpy, and therefore a shift of the zero point of charge towards lower pH values with increasing temperature. Batch titrations at selenate concentrations of between 10 and 100 {mu}M showed an increased degree of adsorption in the acidic pH range, which appeared to be sensitive to the ionic strength of the solution. The selenate adsorption edges shifted towards more acidic pH values with increasing temperature. A 1-pK charge distribution multi-site surface complexation (CD-MUSIC) model was applied, assuming the formation of an outer-spheric surface complex together with an inner-spheric one, in agreement with published spectroscopic information. The temperature behaviour of the intrinsic equilibrium constants were well represented by a linear Van't Hoff log K vs. 1/T plot, from which negative enthalpy values could be derived for both adsorption reactions. The adsorption of the selenate was therefore exothermic and became weaker with increasing temperature. The bidentate inner-spheric complex was more sensitive to rises in temperature (-70 kJ/mol), compared to the outer-spheric complex (-36 kJ/mol). The latter ultimately became the dominating adsorption process at the highest temperature studied. (orig.)

The influence of temperature on selenate adsorption by goethite

International Nuclear Information System (INIS)

Kersten, M.; Vlasova, N.

2013-01-01

Acid-base batch titration data up to 75 C were used to constrain a temperature-dependent 1-pK basic Stern model of the surface protonation reactions of goethite. Experimental data for the temperature dependence of pH PZC (as determined using the two-term Van't Hoff extrapolation) yielded a negative value of -44.9 kJ/mol for the surface protonation enthalpy, and therefore a shift of the zero point of charge towards lower pH values with increasing temperature. Batch titrations at selenate concentrations of between 10 and 100 μM showed an increased degree of adsorption in the acidic pH range, which appeared to be sensitive to the ionic strength of the solution. The selenate adsorption edges shifted towards more acidic pH values with increasing temperature. A 1-pK charge distribution multi-site surface complexation (CD-MUSIC) model was applied, assuming the formation of an outer-spheric surface complex together with an inner-spheric one, in agreement with published spectroscopic information. The temperature behaviour of the intrinsic equilibrium constants were well represented by a linear Van't Hoff log K vs. 1/T plot, from which negative enthalpy values could be derived for both adsorption reactions. The adsorption of the selenate was therefore exothermic and became weaker with increasing temperature. The bidentate inner-spheric complex was more sensitive to rises in temperature (-70 kJ/mol), compared to the outer-spheric complex (-36 kJ/mol). The latter ultimately became the dominating adsorption process at the highest temperature studied. (orig.)

Global Lunar Gravity Field Determination Using Historical and Recent Tracking Data in Preparation for SELENE

Science.gov (United States)

Goossens, S.; Matsumoto, K.; Namiki, N.; Hanada, H.; Iwata, T.; Tsuruta, S.; Kawano, N.; Sasaki, S.

2006-12-01

In the near future, a number of satellite missions are planned to be launched to the Moon. These missions include initiatives by China, India, the USA, as well as the Japanese SELENE mission. These missions will gather a wealth of lunar data which will improve the knowledge of the Moon. One of the main topics to be addressed will be the lunar gravity field. Especially SELENE will contribute to improving the knowledge of the gravity field, by applying 4-way Doppler tracking between the main satellite and a relay satellite, and by applying a separate differential VLBI experiment. These will improve the determination of the global gravity field, especially over the far side and at the lower degrees (mostly for degrees lower than 30), as is shown by extensive simulations of the SELENE mission. This work focuses on the determination of the global lunar gravity field from all available tracking data to this date. In preparation for the SELENE mission, analysis using Lunar Prospector tracking data, as well as Clementine data and historical data from the Apollo and Lunar Orbiter projects is being conducted at NAOJ. Some SMART-1 tracking data are also included. The goal is to combine the good-quality data from the existing lunar missions up to this date with the tracking data from SELENE in order to derive a new lunar gravity field model. The focus therefore currently lies on processing the available data and extracting lunar gravity field information from them. It is shown that the historical tracking data contribute especially to the lower degrees of the global lunar gravity field model. Due to the large gap in tracking data coverage over the far side for the historical data, the higher degrees are almost fully determined by the a priori information in the form of a Kaula rule. The combination with SELENE data is thus expected to improve the estimate for the lower degrees even further, including coverage of the far side. Since historical tracking data are from orbits with

Optimum Exploration for the Self-Ordering of Anodic Porous Alumina Formed via Selenic Acid Anodizing

OpenAIRE

Akiya, Shunta; Kikuchi, Tatsuya; Natsui, Shungo; Suzuki, Ryosuke O.

2015-01-01

Improvements of the regularity of the arrangement of anodic porous alumina formed by selenic acid anodizing were investigated under various operating conditions. The oxide burning voltage increased with the stirring rate of the selenic acid solution, and the high applied voltage without oxide burning was achieved by vigorously stirring the solution. The regularity of the porous alumina was improved as the anodizing time and surface flatness increased. Conversely, the purity of the 99.5–99.999...

Variation in electrical properties of gamma irradiated cadmium selenate nanowires

Science.gov (United States)

Chauhan, R. P.; Rana, Pallavi; Narula, Chetna; Panchal, Suresh; Choudhary, Ritika

2016-07-01

Preparation of low-dimensional materials attracts more and more interest in the last few years, mainly due to the wide field of potential commercial applications ranging from life sciences, medicine and biotechnology to communication and electronics. One-dimensional systems are the smallest dimension structures that can be used for efficient transport of electrons and thus expected to be critical to the function and integration of nanoscale devices. Nanowires with well controlled morphology and extremely high aspect ratio can be obtained by replicating a nanoporous polymer ion-track membrane with cylindrical pores of controlled dimensions. With this technique, materials can be deposited within the pores of the membrane by electrochemical reduction of the desired ion. In the present study, cadmium selenate nanowires were synthesized potentiostatically via template method. These synthesized nanowires were then exposed to gamma rays by using a 60Co source at the Inter University Accelerator Centre, New Delhi, India. Structural, morphological, electrical and elemental characterizations were made in order to analyze the effect of gamma irradiation on the synthesized nanowires. I-V measurements of cadmium selenate nanowires, before and after irradiation were made with the help of Keithley 2400 source meter and Ecopia probe station. A significant change in the electrical conductivity of cadmium selenate nanowires was found after gamma irradiation. The crystallography of the synthesized nanowires was also studied using a Rigaku X-ray diffractrometer equipped with Cu-Kα radiation. XRD patterns of irradiated samples showed no variation in the peak positions or phase change.

Variation in electrical properties of gamma irradiated cadmium selenate nanowires

Energy Technology Data Exchange (ETDEWEB)

Chauhan, R.P., E-mail: chauhanrpc@gmail.com; Rana, Pallavi, E-mail: prana.phy@gmail.com; Narula, Chetna; Panchal, Suresh; Choudhary, Ritika

2016-07-15

Preparation of low-dimensional materials attracts more and more interest in the last few years, mainly due to the wide field of potential commercial applications ranging from life sciences, medicine and biotechnology to communication and electronics. One-dimensional systems are the smallest dimension structures that can be used for efficient transport of electrons and thus expected to be critical to the function and integration of nanoscale devices. Nanowires with well controlled morphology and extremely high aspect ratio can be obtained by replicating a nanoporous polymer ion-track membrane with cylindrical pores of controlled dimensions. With this technique, materials can be deposited within the pores of the membrane by electrochemical reduction of the desired ion. In the present study, cadmium selenate nanowires were synthesized potentiostatically via template method. These synthesized nanowires were then exposed to gamma rays by using a {sup 60}Co source at the Inter University Accelerator Centre, New Delhi, India. Structural, morphological, electrical and elemental characterizations were made in order to analyze the effect of gamma irradiation on the synthesized nanowires. I–V measurements of cadmium selenate nanowires, before and after irradiation were made with the help of Keithley 2400 source meter and Ecopia probe station. A significant change in the electrical conductivity of cadmium selenate nanowires was found after gamma irradiation. The crystallography of the synthesized nanowires was also studied using a Rigaku X-ray diffractrometer equipped with Cu-Kα radiation. XRD patterns of irradiated samples showed no variation in the peak positions or phase change.

Background electrolytes and pH effects on selenate adsorption using iron-impregnated granular activated carbon and surface binding mechanisms.

Science.gov (United States)

Zhang, Ning; Gang, Daniel Dianchen; McDonald, Louis; Lin, Lian-Shin

2018-03-01

Iron-impregnated granular activated carbon (Fe-GAC) has been shown effective for selenite adsorptive removal from aqueous solutions, but similar effectiveness was not observed with selenate. This study examined the effects of background electrolytes and pH on selenate adsorption on to Fe-GAC, and surface bindings to elucidate the selenate adsorption mechanisms. The decrease magnitude of selenate adsorption capacity under three background electrolytes followed the order: LiCl > NaCl > KCl, as ionic strength increased from 0.01 to 0.1 M. Larger adsorption capacity differences among the three electrolytes were observed under the higher ionic strengths (0.05 and 0.1 M) than those under 0.01 M. Multiplet peak fittings of high resolution X-ray photoelectron spectra for O1s and Fe2p 3/2 indicated the presence of iron (III) on adsorbent surface. pH variations during the adsorbent preparation within 3-8 in NaCl solutions did not cause appreciable changes in the iron redox state and composition. Raman spectra showed the formation of both monodentate and bidentate inner sphere complexes under pHs adsorption under alkaline conditions. Mechanisms for monodentate and bidentate formations and a stable six-member ring structure were proposed. Two strategies were recommended for modifying Fe-GAC preparation procedure to enhance the selenate adsorption: (1) mixed-metal oxide coatings to increase the point of zero charge (pH zpc ); and (2) ferrous iron coating to initially reduce selenate followed by selenite adsorption. Copyright © 2017 Elsevier Ltd. All rights reserved.

Uptake and speciation of selenium in garlic cultivated in soil amended with symbiotic fungi (mycorrhiza) and selenate

DEFF Research Database (Denmark)

Larsen, Erik Huusfeldt; Lobinski, R.; Burger-Meyer, K.

2006-01-01

The scope of the work was to investigate the influence of selenate fertilisation and the addition of symbiotic fungi (mycorrhiza) to soil on selenium and selenium species concentrations in garlic. The selenium species were extracted from garlic cultivated in experimental plots by proteolytic...... in garlic. The selenium content in garlic, which was analysed by ICP-MS, showed that addition of mycorrhiza to the natural soil increased the selenium uptake by garlic tenfold to 15 mu g g(-1) (dry mass). Fertilisation with selenate and addition of mycorrhiza strongly increased the selenium content...... of soil by mycorrhiza and/or by selenate increased the content of selenium but not the distribution of detected selenium species in garlic. Finally, the use of two-dimensional HPLC (size exclusion followed by reversed-phase) allowed the structural characterisation of gamma...

Investigation into the dehydration of selenate doped Na2M(SO4)2·2H2O (M = Mn, Fe, Co and Ni): Stabilisation of the high Na content alluaudite phases Na3M1.5(SO4)3-1.5x(SeO4)1.5x (M = Mn, Co and Ni) through selenate incorporation

Science.gov (United States)

Driscoll, L. L.; Kendrick, E.; Knight, K. S.; Wright, A. J.; Slater, P. R.

2018-02-01

In this paper we report an investigation into the phases formed on dehydration of Na2M(SO4)2-x(SeO4)x·2H2O (0 ≤ x ≤ 1; M = Mn, Fe, Co and Ni). For the Fe series, all attempts to dehydrate the samples doped with selenate resulted in amorphous products, and it is suspected that a side redox reaction involving the Fe and selenate may be occurring leading to phase decomposition and hence the lack of a crystalline product on dehydration. For M = Mn, Co, Ni, the structure observed was shown to depend upon the transition metal cation and level of selenate doping. An alluaudite phase, Na3M1.5(SO4)3-1.5x(SeO4)1.5x, was observed for the selenate doped compositions, with this phase forming as a single phase for x ≥ 0.5 M = Co, and x = 1.0 M = Ni. For M = Mn, the alluaudite structure is obtained across the series, albeit with small impurities for lower selenate content samples. Although the alluaudite-type phases Na2+2y(Mn/Co)2-y(SO4)3 have recently been reported [1,2], doping with selenate appears to increase the maximum sodium content within the structure. Moreover, the selenate doped Ni based samples reported here are the first examples of a Ni sulfate/selenate containing system exhibiting the alluaudite structure.

Subsurface structures in the northern Mare Imbrium measured by Chang'E-3 and SELENE

Science.gov (United States)

Kumamoto, A.; Ishiyama, K.; Feng, J.

2016-12-01

Subsurface structures in the northern Mare Imbrium measured by Chang'E-3 and SELENE have been compared. In Chang'E-3 mission, subsurface radar sounding at (19.51W, 44.12N) was performed by Lunar Penetrating Radar (LPR) onboard the Yutu rover. The LPR was pulse radar operated at two frequencies: 60 MHz and 500 MHz. During its operation period from December 2013 to January 2014, the LPR observed subsurface echoes along the rover's track with total distance of 114 m. From the observation in 60 MHz, the subsurface echoes from buried regolith layers at depths of 35, 50, 140, 240, and 360 m were reported (Xiao et al., 2015). In SELENE mission, global subsurface radar sounding of the moon was performed by Lunar Radar Sounder (LRS) onboard the SELENE (Kaguya) spacecraft from the polar orbit with an altitude of 100 km. The LRS was chirp radar operated in a frequency range from 4-6 MHz. So the range resolution of LRS was 75 m in vacuum. During operation period from December 2007 to September 2008, subsurface echoes from all areas of the Moon was observed with a lateral resolution of 76 m. From the global observation, the subsurface echoes from the buried regolith layers in the neraside maria including Mare Imbrium at depths of several hundred meters were reported (Ono et al., 2009).In the present study, we focus on SELENE/LRS data obtained at (19.50W, 44.12N) which is the nearest to the Chang'E-3 landing site. While clear and large-scale subsurface reflectors, as found in Ono et al. (2009), are not found in it, we can identify some echo components from the depths of 140 ( 2000 ns), 240 ( 4000 ns), and 360 m ( 6000 ns). Further analyses utilizing high-resolution data from Chang'E-3/LPR and large-scale data from SELENE/LRS, we will be able to determine the thickness and large-scale structures of the buried regolith layers found by the both radars, and discuss their formation processes in volcanic history of Mare Imbrium.

Determination of selenite and selenate in human urine by ion chromatography and inductively coupled plasma mass spectrometry

DEFF Research Database (Denmark)

Gammelgaard, Bente; Jons, O.

2000-01-01

The selenium species selenite, selenate and selenomethionine were separated in aqueous solution by ion chromatography. The separation was performed on an IonPac AG11 in series with an AS11 anion exchange column by elution with 25 mM sodium hydroxide in 2% methanol. The Se-78 and Se-82 isotopes were...... monitored in the inductively coupled plasma mass spectrometry (ICP-MS) detector. When the chromatographic system was applied to analysis of urine samples diluted 1 + 1, the selenomethionine signal appeared in the front together with other unresolved selenium species, while the selenite and selenate signals...... and selenate, respectively, corresponding to absolute amounts of 8 and 16 pg, respectively. Calculations were based on peak height measurements of the Se-82 isotope. In 23 analysed urine samples, the concentration of selenite was in the range selenium...

Novel in situ resistance measurement for the investigation of CIGS growth in a selenization process

International Nuclear Information System (INIS)

Liu Wei; He Qing; Li Fengyan; Li Changjian; Sun Yun; Tian Jianguo; Li Zubin

2009-01-01

During the selenization process of CIGS thin films, the relation between the element loss rate and the precursor depositions are analyzed. The growth of the CIGS thin films during the selenization process is investigated by the novel in situ resistance measurement, by which the formation of compound semiconductors can be observed directly and simultaneously. Their structures, phase evolutions and element losses are analyzed by XRD and XRF. Based on the experimental results, it can be concluded that the phase transforms have nothing to do with the deposition sequences of precursors, while the element loss rates are related to the deposition sequences in this process. In addition, element loss mechanisms of CIGS thin films prepared by the selenization process are analyzed by the phase evolutions and chemical combined path in the In, Ga–Se reaction processes. Moreover it is verified that the element losses are depressed by increasing the ramping-up rate finally. The results provide effective methods to fabricate high-quality CIGS thin films with low element losses

Novel in situ resistance measurement for the investigation of CIGS growth in a selenization process

Science.gov (United States)

Liu, Wei; Tian, Jian-Guo; Li, Zu-Bin; He, Qing; Li, Feng-Yan; Li, Chang-Jian; Sun, Yun

2009-03-01

During the selenization process of CIGS thin films, the relation between the element loss rate and the precursor depositions are analyzed. The growth of the CIGS thin films during the selenization process is investigated by the novel in situ resistance measurement, by which the formation of compound semiconductors can be observed directly and simultaneously. Their structures, phase evolutions and element losses are analyzed by XRD and XRF. Based on the experimental results, it can be concluded that the phase transforms have nothing to do with the deposition sequences of precursors, while the element loss rates are related to the deposition sequences in this process. In addition, element loss mechanisms of CIGS thin films prepared by the selenization process are analyzed by the phase evolutions and chemical combined path in the In, Ga-Se reaction processes. Moreover it is verified that the element losses are depressed by increasing the ramping-up rate finally. The results provide effective methods to fabricate high-quality CIGS thin films with low element losses.

Selenate reduction to elemental selenium by anaerobic bacteria in sediments and culture: biogeochemical significance of a novel, sulfate-independent respiration

Science.gov (United States)

Oremland, Ronald S.; Hollibaugh, James T.; Maest, Ann S.; Presser, Theresa S.; Miller, Laurence G.; Culbertson, Charles W.

1989-01-01

Interstitial water profiles of SeO42−, SeO32−, SO42−, and Cl− in anoxic sediments indicated removal of the seleno-oxyanions by a near-surface process unrelated to sulfate reduction. In sediment slurry experiments, a complete reductive removal of SeO42− occurred under anaerobic conditions, was more rapid with H2 or acetate, and was inhibited by O2, NO3−, MnO2, or autoclaving but not by SO42− or FeOOH. Oxidation of acetate in sediments could be coupled to selenate but not to molybdate. Reduction of selenate to elemental selenium was determined to be the mechanism for loss from solution. Selenate reduction was inhibited by tungstate and chromate but not by molybdate. A small quantity of the elemental selenium precipitated into sediments from solution could be resolublized by oxidation with either nitrate or FeOOH, but not with MnO2. A bacterium isolated from estuarine sediments demonstrated selenate-dependent growth on acetate, forming elemental selenium and carbon dioxide as respiratory end products. These results indicate that dissimilatory selenate reduction to elemental selenium is the major sink for selenium oxyanions in anoxic sediments. In addition, they suggest application as a treatment process for removing selenium oxyanions from wastewaters and also offer an explanation for the presence of selenite in oxic waters.

Changes in SeMSC, glucosinolates and sulforaphane levels, and in proteome profile in broccoli (Brassica oleracea var. Italica) fertilized with sodium selenate.

Science.gov (United States)

Sepúlveda, Ignacio; Barrientos, Herna; Mahn, Andrea; Moenne, Alejandra

2013-05-07

The aim of this work was to analyze the effect of sodium selenate fortification on the content of selenomethyl selenocysteine (SeMSC), total glucosinolates and sulforaphane, as well as the changes in protein profile of the inflorescences of broccoli (Brassica oleracea var. Italica). Two experimental groups were considered: plants treated with 100 μmol/L sodium selenate (final concentration in the pot) and control plants treated with water. Fortification began 2 weeks after transplantation and was repeated once a week during 10 weeks. Broccoli florets were harvested when they reached appropriate size. SeMSC content in broccoli florets increased significantly with sodium selenate fortification; but total glucosinolates and sulforaphane content as well as myrosinase activity were not affected. The protein profile of broccoli florets changed due to fortification with sodium selenate. Some proteins involved in general stress-responses were up-regulated, whereas down-regulated proteins were identified as proteins involved in protection against pathogens. This is the first attempt to evaluate the physiological effect of fortification with sodium selenate on broccoli at protein level. The results of this work will contribute to better understanding the metabolic processes related with selenium uptake and accumulation in broccoli.

Changes in SeMSC, Glucosinolates and Sulforaphane Levels, and in Proteome Profile in Broccoli (Brassica oleracea var. Italica Fertilized with Sodium Selenate

Directory of Open Access Journals (Sweden)

Alejandra Moenne

2013-05-01

Full Text Available The aim of this work was to analyze the effect of sodium selenate fortification on the content of selenomethyl selenocysteine (SeMSC, total glucosinolates and sulforaphane, as well as the changes in protein profile of the inflorescences of broccoli (Brassica oleracea var. Italica. Two experimental groups were considered: plants treated with 100 mmol/L sodium selenate (final concentration in the pot and control plants treated with water. Fortification began 2 weeks after transplantation and was repeated once a week during 10 weeks. Broccoli florets were harvested when they reached appropriate size. SeMSC content in broccoli florets increased significantly with sodium selenate fortification; but total glucosinolates and sulforaphane content as well as myrosinase activity were not affected. The protein profile of broccoli florets changed due to fortification with sodium selenate. Some proteins involved in general stress-responses were up-regulated, whereas down-regulated proteins were identified as proteins involved in protection against pathogens. This is the first attempt to evaluate the physiological effect of fortification with sodium selenate on broccoli at protein level. The results of this work will contribute to better understanding the metabolic processes related with selenium uptake and accumulation in broccoli.

Study of the Cupriavidus metallidurans CH34 resistance of selenite and selenate oxy-anions: accumulation, localisation and transformation of selenium

International Nuclear Information System (INIS)

Avoscan, L.

2007-06-01

Selenium is an essential trace element for the living organisms but it is very toxic at high concentration. Selenite and selenate oxides, soluble forms, highly toxic and bio-assimilable, are the most prevalent forms in the environment. Some soil micro-organisms play a dominant role and contribute to the natural cycle of selenium. Our study model, Cupriavidus (formerly Ralstonia) metallidurans CH34, a telluric bacterium characteristic of metal-contaminated biotopes, is known to resist selenite by reducing it into elemental selenium, an insoluble and less toxic form of selenium. In order to better understand the mechanisms of selenium reduction in the bacteria, three methods of speciation were combined (XAS (XANES and EXAFS), HPLC-ICP-MS and SDS-PAGEPIXE). They were completed by the direct quantification of selenium accumulated in the bacteria. Speciation analyses highlighted the existence of two mechanisms of reduction of selenium oxides in C. metallidurans CH34. Assimilation transforms selenite and selenate into organic selenium, identified as seleno-methionine and leads to its non-specific incorporation into bacterial proteins (presence of selenious proteins). Detoxication precipitates selenite in nano-particles of elemental selenium. This way of detoxication is not set up after an exposure to selenate although it is nevertheless possible to detect elemental selenium but in very small amount compared to the exposure of selenite. Seleno-diglutathion is detected in bacteria stressed by an exposure to selenate in medium limited in sulphate. Bacteria exposed to selenite accumulate 25 times more selenium than when they are exposed to selenate. The study of mutants resistant to selenite, which do not express the membrane protein DedA, showed that the accumulation of selenium after exposure to selenite is decreased compared with the wild strain meaning probable link between the transport of selenite and the DedA protein. Finally, selenate would use the sulphate permease

Contribution of SELENE-2 geodetic measurements to constrain the lunar internal structure

Science.gov (United States)

Matsumoto, K.; Kikuchi, F.; Yamada, R.; Iwata, T.; Kono, Y.; Tsuruta, S.; Hanada, H.; Goossens, S. J.; Ishihara, Y.; Kamata, S.; Sasaki, S.

2012-12-01

Internal structure and composition of the Moon provide important clue and constraints on theories for how the Moon formed and evolved. The Apollo seismic network has contributed to the internal structure modeling. Efforts have been made to detect the lunar core from the noisy Apollo data (e.g., [1], [2]), but there is scant information about the structure below the deepest moonquakes at about 1000 km depth. On the other hand, there have been geodetic studies to infer the deep structure of the Moon. For example, LLR (Lunar Laser Ranging) data analyses detected a displacement of the lunar pole of rotation, indicating that dissipation is acting on the rotation arising from a fluid core [3]. Bayesian inversion using geodetic data (such as mass, moments of inertia, tidal Love numbers k2 and h2, and quality factor Q) also suggests a fluid core and partial melt in the lower mantle region [4]. Further improvements in determining the second-degree gravity coefficients (which will lead to better estimates of moments of inertia) and the Love number k2 will help us to better constrain the lunar internal structure. Differential VLBI (Very Long Baseline Interferometry) technique, which was used in the Japanese lunar exploration mission SELENE (Sept. 2007 - June 2009), is expected to contribute to better determining the second-degree potential Love number k2 and low-degree gravity coefficients. SELENE will be followed by the future lunar mission SELENE-2 which will carry both a lander and an orbiter. We propose to put the SELENE-type radio sources on these spacecraft in order to accurately estimate k2 and the low-degree gravity coefficients. By using the same-beam VLBI tracking technique, these parameters will be retrieved through precision orbit determination of the orbiter with respect to the lander which serves as a reference. The VLBI mission with the radio sources is currently one of the mission candidates for SELENE-2. We have conducted a preliminary simulation study on the

Separation of selenium compounds by CE-ICP-MS in dynamically coated capillaries applied to selenized yeast samples

DEFF Research Database (Denmark)

Bendahl, Lars; Gammelgaard, Bente

2004-01-01

The selenium species in nutritional supplement tablets, based on selenized yeast, were separated by capillary zone electrophoresis using capillaries coated dynamically with poly(vinyl sulfonate) and detected by ICP-MS. Sample pre-treatment consisted of cold-water extraction by sonication and subs......The selenium species in nutritional supplement tablets, based on selenized yeast, were separated by capillary zone electrophoresis using capillaries coated dynamically with poly(vinyl sulfonate) and detected by ICP-MS. Sample pre-treatment consisted of cold-water extraction by sonication...

Detection of over 100 selenium metabolites in selenized yeast by liquid chromatography electrospray time-of-flight mass spectrometry.

Science.gov (United States)

Gilbert-López, Bienvenida; Dernovics, Mihaly; Moreno-González, David; Molina-Díaz, Antonio; García-Reyes, Juan F

2017-08-15

The characterization of the selenometabolome of Selenized(Se)-yeast, that is the fraction of water soluble low-molecular weight Se-metabolites produced in Se-yeast is of paramount interest to expand the knowledge on the composition of this food supplement. In this work, we have applied liquid chromatography electrospray time-of-flight mass spectrometry (LC-TOFMS) to search for Se-species from the low molecular weight range fraction of the selenized yeast used for food supplements. Prior to LC-TOFMS, sample treatment consisted of ultrasound assisted water extraction followed by size exclusion fractionation assisted with off-line inductively coupled plasma mass spectrometry detection of isotope 82 Se. The fraction corresponding to low-molecular weight species was subjected to LC-TOFMS using electrospray ionization in the positive ion mode. The detection of the suspected selenized species has been based on the information obtained from accurate mass measurements of both the protonated molecules and fragments from in-source CID fragmentation; along with the characteristic isotope pattern exhibited by the presence of Se. The approach enables the detection of 103 selenized species, most of them not previously reported, in the range from ca. 300-650Da. Besides the detection of selenium species, related sulphur derivate metabolites were detected based on the accurate mass shift due to the substitution of sulphur and selenium. Copyright © 2017. Published by Elsevier B.V.

Deposition of CuIn(Se,S)2 thin films by sulfurization of selenized Cu/In alloys

International Nuclear Information System (INIS)

Sheppard, C.J.; Alberts, V.; Bekker, W.J.

2004-01-01

The relatively small band gap values (close to 1eV) of CuInSe 2 thin films limits the conversion efficiencies of completed CuInSe 2 /CdS/ZnO solar cell devices. In the case of traditional two-stage growth techniques, limited success has been achieved to increase the band gap by substituting indium with gallium. In this study, sputtered copper-indium alloys were exposed to a H 2 Se/Ar atmosphere under defined conditions in order to produce partially reacted CuInSe 2 structures. These films were subsequently exposed to a H 2 S/Ar atmosphere to produce monophasic CuIn(Se, S) 2 quaternary alloys. The homogeneous incorporation of S into CuInSe 2 led to a systematic shift in the lattice parameters and band gap of the ab- sorber films. From these studies optimum selenization/sulfurization conditions were determined for the deposition of homogeneous CuIn(Se,S) 2 thin films with an optimum band gap values between 1.15 and 1.2 eV. (copyright 2004 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Synthesis, characterization and thermal decomposition of tetramethylammonium rare earth double selenates

Science.gov (United States)

Divekar, Sandesh K.; Achary, S. Nagabhusan; Ajgaonkar, Vishnu R.

2018-06-01

A series of double selenates, as (CH3)4NLn(SeO4)2rad 4H2O (Ln = Rare earth ion like La, Pr, Nd, Sm, Gd, Tb, Dy) was crystallized from mixed solution and characterized in detail for their structure, vibrational and optical properties as well as thermal stabilities. The crystal structure of the praseodymium compound was obtained by single crystal X-ray diffraction (XRD) and revealed a monoclinic (C2/c) lattice with chains formed by PrO8 and SeO4 units. The chains with compositions [Pr(SeO4)4(H2O)4]- are stacked in three dimensions and the (CH3)4N+ ions located in between them provide charge neutrality to the structure. The characterization of other compounds were carried out from powder XRD data and revealed that they all are isostructural to Pr-compound. All the functional groups were identified by Raman and IR spectroscopic studies. Solid state 77Se NMR revealed noticeable changes in selenium environment in these compounds. The optical absorption studies on the compounds show strong band edge absorptions in UV region. Thermal stabilities of the compounds, as investigated by simultaneous TG-DTA techniques indicate their sequential decompositions due to loss of H2O, (CH3)4N+ group, SeO2 and finally leaving their corresponding rare earth oxides.

Effect of Sodium Selenate on Hippocampal Proteome of 3×Tg-AD Mice-Exploring the Antioxidant Dogma of Selenium against Alzheimer's Disease.

Science.gov (United States)

Iqbal, Javed; Zhang, Kaoyuan; Jin, Na; Zhao, Yuxi; Liu, Qiong; Ni, Jiazuan; Shen, Liming

2018-04-19

Selenium (Se), an antioxidant trace element, is an important nutrient for maintaining brain functions and is reported to be involved in Alzheimer's disease (AD) pathologies. The present study has been designed to elucidate the protein changes in hippocampus of 3×Tg-AD mice after supplementing sodium selenate as an inorganic source of selenium. By using iTRAQ proteomics technology, 113 differentially expressed proteins (DEPs) are found in AD/WT mice with 37 upregulated and 76 downregulated proteins. Similarly, in selenate-treated 3×Tg-AD (ADSe/AD) mice, 115 DEPs are found with 98 upregulated and 17 downregulated proteins. The third group of mice (ADSe/WT) showed 75 DEPs with 46 upregulated and 29 downregulated proteins. Among these results, 42 proteins (40 downregulated and 2 upregulated) in the diseased group showed reverse expression when treated with selenate. These DEPs are analyzed with different bioinformatics tools and are found associated with various AD pathologies and pathways. Based on their functions, selenate-reversed proteins are classified as structural proteins, metabolic proteins, calcium regulating proteins, synaptic proteins, signaling proteins, stress related proteins, and transport proteins. Six altered AD associated proteins are successfully validated by Western blot analysis. This study shows that sodium selenate has a profound effect on the hippocampus of the triple transgenic AD mice. This might be established as an effective therapeutic agent after further investigation.

Rapid fabrication of self-ordered porous alumina with 10-/sub-10-nm-scale nanostructures by selenic acid anodizing

Science.gov (United States)

Nishinaga, Osamu; Kikuchi, Tatsuya; Natsui, Shungo; Suzuki, Ryosuke O.

2013-01-01

Anodic porous alumina has been widely investigated and used as a nanostructure template in various nanoapplications. The porous structure consists of numerous hexagonal cells perpendicular to the aluminum substrate and each cell has several tens or hundreds of nanoscale pores at its center. Because the nanomorphology of anodic porous alumina is limited by the electrolyte during anodizing, the discovery of additional electrolytes would expand the applicability of porous alumina. In this study, we report a new self-ordered nanoporous alumina formed by selenic acid (H2SeO4) anodizing. By optimizing the anodizing conditions, anodic alumina possessing 10-nm-scale pores was rapidly assembled (within 1 h) during selenic acid anodizing without any special electrochemical equipment. Novel sub-10-nm-scale spacing can also be achieved by selenic acid anodizing and metal sputter deposition. Our new nanoporous alumina can be used as a nanotemplate for various nanostructures in 10-/sub-10-nm-scale manufacturing. PMID:24067318

Selen og vitamin E til søer og pattegrise

DEFF Research Database (Denmark)

Nielsen, H. E.; Danielsen, V.; Simesen, M. G.

1977-01-01

Formålet med dette forsøg var at undersøge virkningen af foderets selen- og vitamin E indhold på søernes frugtbarhed og pattegrisenes levedygtighed og vækst. Endvidere at undersøge koncentrationen af selen (Se) og vitamin E i råmælk, somælk og blod i relation til foderet. Der forekom enkelte...... dødsfald blandt grisene, som kunne sættes i forbindelse med enten lavt Se-indhold eller lavt vitamin E indhold i foderet. Der blev desuden konstateret flere brunst- og drægtighedsproblemer hos søer, derfik foder med det lave indhold af vitamin E end hos søer i de andre grupper. En forøgelse af Se......-indholdet fra 30 til 60 µg pr. kg foder gav en fordobling af indholdet i råmælk og i somælk. En forøgelse af vitamin E indholdet i foderet fra ca. 20 mg til ca. 45 mg pr. kg foder gav 4 gange forøgelse i råmælk og somælk. Der blev konstateret tilsvarende virkninger af Se og vitamin E i foderet på indholdet i...

Combination cancer treatment through photothermally controlled release of selenous acid from gold nanocages.

Science.gov (United States)

Cheng, Haoyan; Huo, Da; Zhu, Chunlei; Shen, Song; Wang, Wenxia; Li, Haoxuan; Zhu, Zhihong; Xia, Younan

2018-04-03

Selenite, one of the inorganic forms of selenium, is emerging as an attractive chemotherapeutic agent owing to its selectivity in eradicating cancer cells. Here we demonstrate a new formulation of nanomedicine based on selenous acid, which is mixed with lauric acid (a phase-change material with a melting point around 43 °C) and then loaded into the cavities of Au nanocages. The Au nanocages can serve as a carrier during cell endocytosis and then as a photothermal agent to melt the lauric acid upon the irradiation with a near-infrared laser, triggering the swift release of selenous acid. The photothermal and chemo therapies can also work synergistically, leading to enhanced destruction of cancer cells relative to normal cells. Our systematic study suggests that the impaired mitochondrial function arising from the ROS generated through combination treatment is responsible for the cell death. This study offers an appealing candidate that holds great promise for synergistic cancer treatment. Published by Elsevier Ltd.

Effect of selenization conditions on the growth and properties of Cu2ZnSn(S,Se)4 thin films

OpenAIRE

Ranjbar, Samaneh; Rajesh Menon, M.R.; Fernandes, P.A.; da Cunha, A.F.

2015-01-01

The opto-electronic properties of copper zinc tin sulfide can be tuned to achieve better cell efficiencies by controlled incorporation of selenium. In this paper we report the growth of Cu2ZnSn(S,Se)4 (CZTSSe) using a hybrid process involving the sequential evaporation of Zn and sputtering of the sulfide precursors of Cu and Sn, followed by a selenization step. Two approaches for selenization were followed, one using a tubular furnace and the other using a rapid thermal processor. The effects...

Preparation of SnSe thin films by encapsulated selenization

International Nuclear Information System (INIS)

Sabar D. Hutagalung; Samsudi Sakrani; Yussof Wahab

1994-01-01

Tin selenide thin films were prepared by encapsulated selenization. A stacked layer of evaporated Sn and Se films were annealed in a carbon block at temperatures 100 - 500 degree Celsius for 3 hours. X-ray analysis and SEM (Scanning electron) micrograph results showed that SnSe was initially formed at 150 degree Celsius with crystal size 30.0 nm and reached optimum formation at 200 daximum of 57.4 % yield of 5-decene. Other factors such as reaction temperatures, types of solvent and wt% of rhenium loadings influence the activity of the catalytic system

Sneaking of the Solar Wind Ions Into the Lunar Anti-subsolar Region Revealed by SELENE (Kaguya)

Science.gov (United States)

Nishino, M. N.; Fujimoto, M.; Saito, Y.; Shoichiro, Y.; Asamura, K.; Tanaka, T.; Tsunakawa, H.; Shibuya, H.; Matsushima, M.; Shimizu, H.; Takahashi, F.; Maezawa, K.; Terasawa, T.

2008-12-01

The moon spends more than 80 percent of its life staying in the solar wind (SW), where a quasi-vacuum region called the lunar wake is formed on the night side. The SW electrons with higher energy can come to the lunar night-side surface, while it has been thought that the SW ions are unlikely to approach the low altitude region on the night side because their thermal speed is much lower than the SW bulk speed. Here we show detection of SW ions sneaking into the anti-subsolar region at ~100 km altitude, using recent comprehensive measurement by a Japanese lunar orbiter SELENE (Kaguya). The sneaking of SW ions into the deepest lunar wake was accompanied by an enhancement of counter-streaming electrons along the SW magnetic field. A part of the ions detected in the anti-subsolar region came from the lunar surface, which means that the ions of solar wind origin reflected at the night-side surface. One possibility is that electron- rich wake environment strengthened the bipolar electric field at the wake boundary to let solar-wind ions approach the lunar night side, and the other scenario is that enhancement of ions in the wake let ambient electrons to come in. The sneaking mechanism of the solar wind ions in terms of plasma and electromagnetic environment around/inside the lunar wake will be discussed.

Sorption mechanisms of selenium species (selenite and selenate) on copper-based minerals

International Nuclear Information System (INIS)

Devoy, J.

2001-09-01

The sorption of radionuclides on the surface of minerals represents a process capable to delay the migration of the elements from a spent fuel deep repository towards the biosphere. In the framework of a deep underground repository, an engineered clay barrier has a high trapping capacity for cationic radio-elements, in particular because of the negative charge of clay surfaces. However, anionic radioelements like selenium species, would be only weakly retained by chemical processes. In order to optimize the trapping capacity of a clay barrier with respect to anionic species, prospective studies are carried out in order to find and evaluate some minerals with specific chemical trapping functions. Among radionuclides, the case of selenium has to be considered because its isotope 79 Se is present in radioactive wastes and has a half life time of 6.5 10 4 years. It is also judicious to find a mineral capable of trapping simultaneously several anionic radio-elements. Copper oxides and sulfides (Cu 2 O, CuO, Cu 2 S, CuS, CuFeS 2 and Cu 5 FeS 4 ) are good adsorbents with respect to selenium species (selenite and selenate). These minerals, with their selenium retention properties, could be used also for the decontamination of soils and waters or to process industrial effluents. The sorption mechanisms have been studied in details for copper oxides (Cu 2 O and CuO) with respect to selenite and selenate. Chalcomenite precipitates in acid pH conditions when selenite is added to a Cu 2 O and CuO suspension. Selenate, in contact with cuprite (Cu 2 O) leads also to a selenium-based precipitate in acid pH environment. For higher pH values, selenite and selenate are adsorbed on copper oxides (Cu 2 O and CuO) and lead to internal and external sphere complexes, respectively. In the case of a selenite/cuprite mixture in basic pH environment and at the equilibrium, a chemical reaction occurs between the oxidation product of cuprite, Cu(OH) 2 and HSeO 3 . A preliminary study of

How the Starting Precursor Influences the Properties of Polycrystalline CuInGaSe2 Thin Films Prepared by Sputtering and Selenization

Directory of Open Access Journals (Sweden)

Greta Rosa

2016-05-01

Full Text Available Cu(In,GaSe2 (CIGS/CdS thin-film solar cells have reached, at laboratory scale, an efficiency higher than 22.3%, which is one of the highest efficiencies ever obtained for thin-film solar cells. The research focus has now shifted onto fabrication processes, which have to be easily scalable at an industrial level. For this reason, a process is highlighted here which uses only the sputtering technique for both the absorber preparation and the deposition of all the other materials that make up the cell. Particular emphasis is placed on the comparison between different precursors obtained with either In2Se3 and Ga2Se3 or InSe and GaSe as starting materials. In both cases, the precursor does not require any heat treatment, and it is immediately ready to be selenized. The selenization is performed in a pure-selenium atmosphere and only lasts a few minutes at a temperature of about 803 K. Energy conversion efficiencies in the range of 15%–16% are reproducibly obtained on soda-lime glass (SLG substrates. Similar results are achieved if commercial ceramic tiles are used as a substrate instead of glass. This result is especially useful for the so-called building integrated photovoltaic. Cu(In,GaSe2-based solar cells grown directly on ceramic tiles are ideal for the fabrication of ventilated façades in low impact buildings.

Preparation, solubility, infrared spectra and radiolysis of tetramethylammonium hydrogenselenate monohydrate and lithium tetramethylammonium selenate tetrahydrate

Czech Academy of Sciences Publication Activity Database

Havlíček, D.; Turek, L.; Plocek, Jiří; Mička, Z.

2006-01-01

Roč. 71, č. 3 (2006), s. 411-422 ISSN 0010-0765 Institutional research plan: CEZ:AV0Z40320502 Keywords : tetramethylammonium salts * hydrogenselenates * selenates Subject RIV: CA - Inorganic Chemistry Impact factor: 0.881, year: 2006

Uptake and speciation of selenium in garlic cultivated in soil amended with symbiotic fungi (mycorrhiza) and selenate

Energy Technology Data Exchange (ETDEWEB)

Larsen, Erik H.; Hansen, Marianne; Rasmussen, Peter Have; Sloth, Jens J. [Danish Institute for Food and Veterinary Research, Department of Food Chemistry, Soeborg (Denmark); Lobinski, Ryszard; Ruzik, Rafal; Mazurowska, Lena [CNRS UMR 5034, Pau (France); Warsaw University of Technology, Department of Analytical Chemistry, Warsaw (Poland); Burger-Meyer, Karin; Scholten, Olga [Wageningen University and Research Centre, Plant Research International (PRI), P.O. Box 16, Wageningen (Netherlands); Kik, Chris [Wageningen University and Research Centre, Plant Research International (PRI), P.O. Box 16, Wageningen (Netherlands); Wageningen University and Research Centre, Centre for Genetic Resources, The Netherlands (CGN), P.O. Box 16, Wageningen (Netherlands)

2006-07-15

The scope of the work was to investigate the influence of selenate fertilisation and the addition of symbiotic fungi (mycorrhiza) to soil on selenium and selenium species concentrations in garlic. The selenium species were extracted from garlic cultivated in experimental plots by proteolytic enzymes, which ensured liberation of selenium species contained in peptides or proteins. Separate extractions using an aqueous solution of enzyme-deactivating hydroxylamine hydrochloride counteracted the possible degradation of labile selenium species by enzymes (such as alliinase) that occur naturally in garlic. The selenium content in garlic, which was analysed by ICP-MS, showed that addition of mycorrhiza to the natural soil increased the selenium uptake by garlic tenfold to 15 {mu}g g{sup -1} (dry mass). Fertilisation with selenate and addition of mycorrhiza strongly increased the selenium content in garlic to around one part per thousand. The parallel analysis of the sample extracts by cation exchange and reversed-phase HPLC with ICP-MS detection showed that {gamma}-glutamyl-Se-methyl-selenocysteine amounted to 2/3, whereas methylselenocysteine, selenomethionine and selenate each amounted to a few percent of the total chromatographed selenium in all garlic samples. Se-allyl-selenocysteine and Se-propyl-selenocysteine, which are selenium analogues of biologically active sulfur-containing amino acids known to occur in garlic, were searched for but not detected in any of the extracts. The amendment of soil by mycorrhiza and/or by selenate increased the content of selenium but not the distribution of detected selenium species in garlic. Finally, the use of two-dimensional HPLC (size exclusion followed by reversed-phase) allowed the structural characterisation of {gamma}-glutamyl-Se-methyl-selenocysteine and {gamma}-glutamyl-Se-methyl-selenomethionine in isolated chromatographic fractions by quadrupole time-of-flight mass spectrometry. (orig.)

Effect of selenization time on the structural and morphological properties of Cu(In,Ga)Se2 thin films absorber layers using two step growth process

Science.gov (United States)

Korir, Peter C.; Dejene, Francis B.

2018-04-01

In this work two step growth process was used to prepare Cu(In, Ga)Se2 thin film for solar cell applications. The first step involves deposition of Cu-In-Ga precursor films followed by the selenization process under vacuum using elemental selenium vapor to form Cu(In,Ga)Se2 film. The growth process was done at a fixed temperature of 515 °C for 45, 60 and 90 min to control film thickness and gallium incorporation into the absorber layer film. The X-ray diffraction (XRD) pattern confirms single-phase Cu(In,Ga)Se2 film for all the three samples and no secondary phases were observed. A shift in the diffraction peaks to higher 2θ (2 theta) values is observed for the thin films compared to that of pure CuInSe2. The surface morphology of the resulting film grown for 60 min was characterized by the presence of uniform large grain size particles, which are typical for device quality material. Photoluminescence spectra show the shifting of emission peaks to higher energies for longer duration of selenization attributed to the incorporation of more gallium into the CuInSe2 crystal structure. Electron probe microanalysis (EPMA) revealed a uniform distribution of the elements through the surface of the film. The elemental ratio of Cu/(In + Ga) and Se/Cu + In + Ga strongly depends on the selenization time. The Cu/In + Ga ratio for the 60 min film is 0.88 which is in the range of the values (0.75-0.98) for best solar cell device performances.

Controlled formation of MoSe{sub 2} by MoN{sub x} thin film as a diffusion barrier against Se during selenization annealing for CIGS solar cell

Energy Technology Data Exchange (ETDEWEB)

Jeon, Chan-Wook [School of Chemical Engineering, Yeungnam University, Gyeongsangbuk-do 712-749 (Korea, Republic of); Cheon, Taehoon [School of Materials Science and Engineering, Yeungnam University, Gyeongsangbuk-do 712-749 (Korea, Republic of); Center for Core Research Facilities, DaeguGyeongbuk Institute of Science & Technology, Daegu (Korea, Republic of); Kim, Hangil [School of Materials Science and Engineering, Yeungnam University, Gyeongsangbuk-do 712-749 (Korea, Republic of); Kwon, Min-Su [School of Chemical Engineering, Yeungnam University, Gyeongsangbuk-do 712-749 (Korea, Republic of); Kim, Soo-Hyun [School of Materials Science and Engineering, Yeungnam University, Gyeongsangbuk-do 712-749 (Korea, Republic of)

2015-09-25

Highlights: • Mo/MoN{sub x}/Mo multilayer was investigated as a back contact for CIGS solar cell. • The MoN{sub x} protected the underlying Mo layer during high temperature selenization. • The formation of MoSe{sub 2} layer was precisely controlled. • The diffusion barrier performance of MoN{sub x} against Se was evaluated using TEM analysis. - Abstract: This study investigated the interfacial reactions and electrical properties of a Mo single layer and Mo/MoN{sub x}/Mo multilayer during high temperature selenization annealing. The Mo single layer was converted easily to MoSe{sub 2}, which was 7 times thicker than the Mo layer consumed ∼900 nm, by selenization at 460 °C for 10 min and the sheet resistance increased 8 fold compared to that of the as-deposited Mo film. On the other hand, in the Mo/MoN{sub x}/Mo structure, transmission electron microscopy (TEM) showed that the MoSe{sub 2} transformation was localized only in the top Mo layer and the bottom Mo layer was completely unaffected, even after selenization at 560 °C. The sheet resistance of the multilayer was relatively unchanged by selenization. This suggests that the MoN{sub x} layer performed well as a diffusion barrier against Se and the thickness of MoSe{sub 2} can be controlled precisely by adjusting the top Mo layer thickness. Furthermore, TEM and energy dispersive spectroscopy analysis showed that the selenized multilayer consisted of MoSe{sub 2}/Mo/MoN{sub x}/Mo, in which the top Mo layer of 60 nm was not fully converted to MoSe{sub 2} and 20 nm was left unreacted. The residual Mo interlayer located at the interface of MoSe{sub 2} and MoN{sub x} is believed to be beneficial for the ohmic contact of the selenized multilayer.

Formation of CuInSe{sub 2} films from metal sulfide and selenide precursor nanocrystals by gas-phase selenization, an in-situ XRD study

Energy Technology Data Exchange (ETDEWEB)

Capon, B., E-mail: boris.capon@ugent.be [Department of Solid State Sciences, Ghent University, Krijgslaan 281-S1, B-9000 Ghent (Belgium); Dierick, R. [Physics and Chemistry of Nanostructures, Ghent University, Krijgslaan 281-S3, B-9000 Ghent (Belgium); Hens, Z. [Physics and Chemistry of Nanostructures, Ghent University, Krijgslaan 281-S3, B-9000 Ghent (Belgium); Center for Nano and Biophotonics, Ghent University, Ghent (Belgium); Detavernier, C. [Department of Solid State Sciences, Ghent University, Krijgslaan 281-S1, B-9000 Ghent (Belgium)

2016-08-01

In this work phase pure CuInSe{sub 2} thin flms were obtained by selenization of ternary CuInSe{sub 2} and CuInS{sub 2} nanocrystals and mixtures of binary nanocrystals such as CuS, In{sub 2}S{sub 3}, Cu{sub 2}Se and In{sub 2}Se{sub 3}. The temperature of the selenium source was kept at 400 °C during selenization. Monitoring the process using in-situ x-ray diffraction, the effect of selenization on the phase formation and grain growth in the precursor film was investigated. Whereas CuInSe{sub 2} and CuInS{sub 2} nanocrystals exhibit little grain growth, we found that mixtures of binary nanocrystals can show significant sintering depending on the reaction conditions. For the mixture of CuS and In{sub 2}S{sub 3} nanocrystals, the crystallinity and the morphology of the obtained fims strongly depends on the Cu/In ratio, with a Cu excess strongly promoting grain growth. With mixtures of Cu{sub 2}Se and In{sub 2}Se{sub 3} nanocrystals the selenium partial pressure plays a crucial role. Selenium evaporation from the mixed compounds results in CuInSe{sub 2} films composed of relatively small crystallites. Higher selenium partial pressures however resulted in improved sintering. Incomplete propagation of the selenization reaction through the layer was observed though, only leading to a well sintered CuInSe{sub 2} top layer above a fine grained bottom layer. - Highlights: • Different types of colloidal nanocrystals were used as precursors to obtain CuInSe{sub 2} films by gas-phase selenization. • In-situ XRD was used to study the effect of selenization on the phase formation and grain growth in the precursor films. • For a mixture of binary metal sulfides the crystallinity and the morphology strongly depend on the Cu/In ratio. • Higher selenium partial pressures result in improved sintering for a mixture of binary metal selenides.

Bioavailability of selenium from fish, yeast and selenate: A comparative study in humans using stable isotopes

NARCIS (Netherlands)

Fox, T.E.; Heuvel, E.G.H.M. van den; Atherton, C.A.; Dainty, J.R.; Lewis, D.J.; Langford, N.J.; Crews, H.M.; Luten, J.B.; Lorentzen, M.; Sieling, F.W.; Aken-Schneyder, P. van; Hoek, M.; Kotterman, M.J.J.; Dael, P. van; Firweather-Tail, S.J.

2004-01-01

Objective: To measure the bioavailability of selenium from cooked and raw fish in humans by estimating and comparing apparent absorption and retention of selenium in biosynthetically labelled fish with labelled selenate and biosynthetically labelled selenium in brewers yeast. Design: The

Bioavailibility of selenium from fish, yeast and selenate: a comparative study in humans using stable isotopes

NARCIS (Netherlands)

Fox, T.E.; Heuvel, van den E.G.H.M.; Atherton, C.A.; Luten, J.B.; Hoek-van Nieuwenhuizen, van M.; Kotterman, M.J.J.

2004-01-01

Objective: To measure the bioavailability of selenium from cooked and raw fish in humans by estimating and comparing apparent absorption and retention of selenium in biosynthetically labelled fish with labelled selenate and biosynthetically labelled selenium in brewers yeast. Design: The

The Effect of E-Selen Antioxidant on the Fatty Acids Content of the Homogenate of Unirradiated and Irradiated Pupae of Ceratitis Capitata

International Nuclear Information System (INIS)

Zaghloul, Y.S.; Abbassy, S.A.; Elakhdar, E.A.H.; Elakhdar, E.A.H.

2011-01-01

As antioxidant E-selen was added to the larval artificial diets of the Mediterranean fruit fly, Ceratitis capitata. The produced full grown pupae were exposed to gamma rays at dose rate of 90 Gy. The fatty acid contents of the normal and irradiated insects were analyzed to test to what extent, the uptake of the antioxidant will ameliorate the physiological damage induced to the medfly pupae, as a result of their exposure to irradiation. The results obtained by using Gas-liquid chromatography of fatty acid methyl esters, showed the palmitic and oleic acids to be the most predominant fatty acids in all pupal homogenates in both normal and irradiated pupae, either by the uptake of doses of the E-selen or without. The uptake of E-Selen with a dose of 0.3 mg led to a complete absence of the lauric and myristic acids in the homogenates of the unirradiated pupae of the medfly. This absence of lauric and myristic acids was accompanied by a decrease in the concentrations of the palmitic and linoleic acids reaching 25.17% and 32.98%, respectively as compared to pupae without the uptake of antioxidant. The concentrations of both the stearic and oleic acids showed an obvious increment reaching 199.22% and 58.94%, respectively, relative to those reared on the defined media and no added E.Selen. Exposure of the pupae to a dose of 90 Gy, resulted in an increment in the concentrations of the saturated lauric and myristic acid reaching 96.77% and 34.07%, respectively, relative to the untreated ones. While, at the same dose level, there were decrements in the concentrations of the palmitic, stearic, oleic and linoleic acids with percentages reaching 6.4, 9.22, 3.65 and 1.15%, respectively as compared to unirradiated controls. Irradiation of the pupae with sterilizing dose (90 Gy) after up taking the E-Selen in their larval diets, led to the increase of the concentrations of lauric, oleic and linoleic acids by ratios of 16.82, 8.84 and 29.26%, respectively as compared to their

Uptake of selenate on hydrated and degraded cement: batch and dynamic experiments

International Nuclear Information System (INIS)

Rojo, I.; Rovira, I.; Marti, V.; Pablo, J. de; Duro, L.; Gaona, X.; Colas, E.; Grive, M.

2009-01-01

The evaluation of selenate sorption and retardation in batch and dynamic experiments on hydrated and degraded cement has been studied. Desorption studies have also been carried in order to assess the reversibility of the sorption process. Sorption data onto degraded cement have been treated assuming the formation of surface complexes, whereas sorption kinetics has been fitted by using a pseudo-first order kinetic equation. Dynamic flow experiments have also been modelled. (authors)

Preparation of Cu{sub 2}ZnSnSe{sub 4} solar cells by low-temperature co-evaporation and following selenization

Energy Technology Data Exchange (ETDEWEB)

Gao, Chao, E-mail: chao.gao@kit.edu; Hetterich, Michael [Institute of Applied Physics, Karlsruhe Institute of Technology (KIT), 76131 Karlsruhe (Germany); Schnabel, Thomas; Abzieher, Tobias; Ahlswede, Erik [Zentrum für Sonnenenergie- und Wasserstoff-Forschung Baden-Württemberg (ZSW), 70565 Stuttgart (Germany); Powalla, Michael [Zentrum für Sonnenenergie- und Wasserstoff-Forschung Baden-Württemberg (ZSW), 70565 Stuttgart (Germany); Light Technology Institute (LTI), Karlsruhe Institute of Technology (KIT), 76131 Karlsruhe (Germany)

2016-01-04

Cu{sub 2}ZnSnSe{sub 4} (CZTSe) thin films are prepared by a two-step method which involves co-evaporation of Cu, Zn, Sn, and Se on molybdenum-coated soda-lime glass at low substrate temperature and a following selenization. Solar cells with efficiencies of up to 6.5% can be achieved. The influence of the selenium deposition rates during co-evaporation and the nitrogen pressure during selenization on the properties of the CZTSe films are investigated. It is found that these two parameters can significantly affect the morphology and crystallinity of the CZTSe films. The possible reasons for the experimental results are discussed.

Identifying the Impact of E-Selen on the Sterile Medfly Ceratitis capitata at the Genomic Level Using DNA Profile

International Nuclear Information System (INIS)

Zaghloul, Y.S.

2014-01-01

The antioxidant E-Selen is an exogenous antioxidant containing both selenium and vitamin E. It was added to the larval artificial diets of the Mediterranean fruit fly, Ceratitis capitata in various concentrations (0.1, 0.3, 0.5 and 1.5 mg) prior to irradiation in order to obtain fully competent males. The produced full grown pupae were exposed to gamma rays at a dose rate of 90 Gy. Biological assessment of two E-Selen concentrations 0.3 and 0.5 mg were found to ameliorate the fitness of the sterile insects as well as to increase significantly most of their amino acids content. The study of the PCR patterns of normal and irradiated C. capitata undertaken or not different doses of E-Selen prior to irradiation and contained in the larval diets induced some modifications to the DNA profiles. The appearance of some new bands and disappearance of others were frequently encountered during this investigation. The appearance of bands was attributed to a repair mechanism that occurs in the irradiated DNA. However, the similarity in the DNA patterns of the homogenate pupal of C. capitata was due to the irradiation-induced damage may be in genome regions other than the regions of study

Observation of Possible Lava Tube Skylights by SELENE cameras

Science.gov (United States)

Haruyama, Junichi; Hiesinger, Harald; van der Bogert, Carolyn

We have discovered three deep hole-structures on the Moon in the Terrain Camera and Multi-band Imager on the SELENE. These holes are large depth to diameter ratios: Marius Hills Hole (MHH) is 65 m in diameter and 88-90 m in depth, Mare Tranquillitatis Hole (MTH) is 120 x 110 m in diameter and 180 m in depth, and Mare Ingenii Hole (MIH) is 140 x 110 m in diameter and deeper than 90 m. No volcanic material from the holes nor dike-relating pit craters is seen around the holes. They are possible lava tube skylights. These holes and possibly connected tubes have a lot of scientific interests and high potentialities as lunar bases.

From zinc selenate to zinc selenide nano structures synthesized by reduction process

International Nuclear Information System (INIS)

Hutagalung, S.D.; Eng, S.T.; Ahmad, Z.A.; Ishak Mat; Yussof Wahab

2009-01-01

One-dimensional nano structure materials are very attractive because of their electronic and optical properties depending on their size. It is well known that properties of material can be tuned by reducing size to nano scale because at the small sizes, that they behave differently with its bulk materials and the band gap will control by the size. The tunability of the band gap makes nano structured materials useful for many applications. As one of the wide band gaps semiconductor compounds, zinc selenide (ZnSe) nano structures (nanoparticles, nano wires, nano rods) have received much attention for the application in optoelectronic devices, such as blue laser diode, light emitting diodes, solar cells and IR optical windows. In this study, ZnSe nano structures have been synthesized by reduction process of zinc selenate using hydrazine hydrate (N 2 H 4 .2H 2 O). The reductive agent of hydrazine hydrate was added to the starting materials of zinc selenate were heat treated at 500 degree Celsius for 1 hour under argon flow to form one-dimensional nano structures. The SEM and TEM images show the formation of nano composite-like structure, which some small nano bar and nano pellets stick to the rod. The x-ray diffraction and elemental composition analysis confirm the formation of mixture zinc oxide and zinc selenide phases. (author)

Uptake and specification of selenium in garlic cultivated in soil amended with symbiotic fungi (mycorrhiza) and selenate

NARCIS (Netherlands)

Larsen, E.H.; Lobinski, R.; Burger-Meijer, K.; Hansen, M.; Ruzik, R.; Mazurowska, L.; Rasmussen, P.H.; Sloth, J.J.; Scholten, O.E.; Kik, C.

2006-01-01

The scope of the work was to investigate the influence of selenate fertilisation and the addition of symbiotic fungi (mycorrhiza) to soil on selenium and selenium species concentrations in garlic. The selenium species were extracted from garlic cultivated in experimental plots by proteolytic

Synthesis and crystal structure of a new neodymium(III) selenate-selenite: Nd2(SeO4)(SeO3)2(H2O)2

International Nuclear Information System (INIS)

Feng Meiling; Mao Jianggao

2005-01-01

The title new neodymium(III) selenate-selenite was obtained by hydrothermal reactions of neodymium(III) oxide, H 2 SeO 4 and 1,10-phenanthroline at 140 o C. Its structure was established by single-crystal X-ray diffraction. The title compound crystallizes in the monoclinic space group C2/c with cell parameters of a = 12.258(2) A, b 7.1024(15) A, c = 13.391(3) A, β = 104.250(2) o . The structure of Nd 2 (SeO 4 )(SeO 3 ) 2 (H 2 O) 2 is isomorphous with that of Er 2 (SeO 4 )(SeO 3 ) 2 (H 2 O) 2 , which was refined in the monoclinic space group C2 with the disordered selenate group. It features an ordered 3D network with channels along b-axis. The selenate or selenite groups alone can form a 2D layer with the Nd(III) ions. IR spectrum, TGA and luminescent studies have also been performed

Determination of Proteinaceous Selenocysteine in Selenized Yeast

Directory of Open Access Journals (Sweden)

Katarzyna Bierla

2018-02-01

Full Text Available A method for the quantitation of proteinaceous selenocysteine (SeCys in Se-rich yeast was developed. The method is based on the reduction of the Se-Se and S-Se bridges with dithiotretiol, derivatization with iodoacetamide (carbamidomethylation, followed by HPLC-ICP MS. The chromatographic conditions were optimized for the total recovery of the proteinaceous selenocysteine, the minimum number of peaks in the chromatogram (reduction of derivatization products of other Se-species present and the baseline separation. A typical chromatogram of a proteolytic digest of selenized yeast protein consisted of up to five peaks (including SeMet, carbamidomethylated (CAM-SeCys, and Se(CAM2 identified by retention time matching with available standards and electrospray MS. Inorganic selenium non-specifically attached to proteins and selenomethionine could be quantified (in the form of Se(CAM2 along with SeCys. Selenocysteine, selenomethionine, inorganic selenium, and the water soluble-metabolite fraction accounted for the totality of selenium species in Se-rich yeast.

Optical and structural properties of FeSe2 thin films obtained by selenization of sprayed amorphous iron oxide films

International Nuclear Information System (INIS)

Ouertani, B.; Ouerfelli, J.; Saadoun, M.; Zribi, M.; Rabha, M.Ben; Bessais, B.; Ezzaouia, H.

2006-01-01

We report in this work the optical and structural properties of iron diselenide films (FeSe 2 ) obtained by selenization under vacuum of amorphous iron oxide films predeposited by spray pyrolysis. The structure of the FeSe 2 films was investigated by scanning electron microscopy (SEM), microprobe analyses, atomic force microscopy (AFM) and X-ray diffraction (XRD). XRD and micro-probe analyses showed that FeSe 2 as well as FeSe 2-x phases begin to appear at a selenization temperature of 500 deg. C. As the selenization temperature rises, the iron diselenide films become more stoichiometric with a dominance of the FeSe 2 phase. At 550 deg. C, a single FeSe 2 phase having good crystallinity was obtained. At 600 deg. C, two phases were detected: the major one corresponds to Fe 3 O 4 , and the minor one to FeSe 2 . SEM surface views show that FeSe 2 films have granular structure with small spherical crystallites. However, layered and clustered FeSe 2 films were found, respectively, at 550 deg. C and 600 deg. C. Absorption measurements show that iron diselenide films have a direct and an indirect gaps of about 1.03 eV and 0.3 eV, which were suggested to be due to the stoichiometric FeSe 2 phase and to a Fe-rich non-stoichiometric phase, respectively

Preparation of CIGS thin films by HiPIMS or DC sputtering and various selenization processes

Czech Academy of Sciences Publication Activity Database

Olejníček, Jiří; Hubička, Zdeněk; Kšírová, Petra; Kment, Štěpán; Brunclíková, Michaela; Kohout, Michal; Čada, Martin; Darveau, S.A.; Exstrom, C.L.

2013-01-01

Roč. 16, č. 2 (2013), s. 314-319 ISSN 1203-8407 R&D Projects: GA MŠk LH12045 Institutional support: RVO:68378271 Keywords : CIGS * HIPIMS * selenization * nanocrystals * solar energy * sputtering * thin films Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 1.106, year: 2013 http://www.ingentaconnect.com/content/stn/jaots/2013/00000016/00000002/art00015

Studies on structural, optical, and photoelectric properties of CdS{sub 1-x}Se{sub x} films fabricated by selenization of chemical bath deposited CdS films

Energy Technology Data Exchange (ETDEWEB)

Lu, Tianyu; Gu, Han; Ge, Zhenhua; Zhang, Lei; Wang, Zhicheng; Fang, Yong; Han, Zhida; Qian, Bin; Jiang, Xuefan [Department of Physics, Changshu Institute of Technology, Changshu (China); Wu, Wangping [School of Mechanical Engineering, Changzhou University, Changzhou (China)

2017-02-15

In this paper, high-photosensitive CdS{sub 1-x}Se{sub x} films are synthesized by a two-step technique, which includes the chemical bath deposition of CdS films and a following selenization process. The structural, optical, and photoelectric properties of the CdS{sub 1-x}Se{sub x} films were investigated. With the substitution of selenium for sulfur atoms, grain sizes of the as-prepared CdS{sub 1-x}Se{sub x} films are effectively enlarged and reach the scales of the films thickness when the selenization temperature exceeds 450 C. With increasing the selenization temperature from 350 to 550 C, the band gaps of CdS{sub 1-x}Se{sub x} films gradually decrease from 2.37 to 1.82 eV. Under the co-action of the grain-size enlargement and band-gap decrease, the CdS{sub 1-x}Se{sub x} films fabricated at 450 C show very pronounced photosensitivity. Noteworthy, the ratio of photo to dark conductivity of the CdS{sub 1-x}Se{sub x} film selenized at 450 C reaches 1.1 x 10{sup 5}, suggesting a promising application potential in the photoelectric devices. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Synthesis and crystal structure of hydrogen selenates K(HSeO4)(H2SeO4) and Cs(HSeO4)(H2SeO4)

International Nuclear Information System (INIS)

Troyanov, S.I.; Morozov, I.V.; Zakharov, M.A.; Kemnitz, E.

1999-01-01

Hydrogen selenates of the compositions K(HSeO 4 )(H 2 SeO 4 ) and Cs(HSeO 4 )(H 2 SeO 4 ) are synthesized by the reaction of alkali metal carbonates with an excess of the concentrated selenic acid. The X-ray diffraction study showed that both compounds are isostructural to the corresponding hydrogen sulfates. The difference in the systems of hydrogen bonding are caused by various combinations of the acceptor functions of the oxygen atoms in the HSeO 4 and H 2 SeO 4 groups

Infrared absorption spectra of selenate compounds of indium (3)

International Nuclear Information System (INIS)

Kharitonov, Yu.Ya.; Kadoshnikova, N.V.; Tananaev, I.V.

1979-01-01

Obtained and discussed are infrared absorption spectra (400-4000 cm -1 ) of the following indium selenates: In 2 (SeO 4 ) 3 x5H 2 O, In 2 (SeO 4 ) 3 x9H 2 O, NaIn(SeO 4 ) 2 x6H 2 O, NaIn(SeO 4 ) 2 xH 2 O, MIn(SeO 4 ) 2 x4H 2 O (M=NH 4 , K, Rb), CsIn(SeO 4 ) 2 x2H 2 O, Na 3 In(SeO 4 ) 3 x7H 2 O, MIn(SeO 4 ) 2 (M=NH 4 , Na, K, Rb, Cs), M 2 InOH(SeO 4 ) 2 xyH 2 O (M=NH 4 , Na, K, Rb) and K 2 InOD(SeO 4 ) 2 xyD 2 O

Investigation of stacked elemental layers for Cu(In,Ga)Se{sub 2} thin film preparation by rapid thermal selenization

Energy Technology Data Exchange (ETDEWEB)

Stroth, Christiane; Ohland, Joerg; Mikolajczak, Ulf; Madena, Thomas; Keller, Jan; Parisi, Juergen; Hammer, Maria; Riedel, Ingo [Energy and Semiconductor Research Laboratory, Department of Physics, University of Oldenburg, 26111 Oldenburg (Germany)

2013-07-01

Rapid thermal selenization of pure metallic (Cu-In-Ga) or selenium-containing (Cu-In-Ga-Se) precursors is a favorable method to fabricate Cu(In,Ga)Se{sub 2} absorber films for application in thin film solar cells. Because of its upscaling potential and the short process time it is a promising approach for the fabrication of CIGSe photovoltaic modules on industrial scale. As a preliminary work for prospective plasma-enhanced selenization of stacked elemental layers (SEL) the elements copper, indium and gallium were sequentially deposited on molybdenum coated soda-lime glass by thermal evaporation. The stacking order was varied and the precursors were annealed with different heating rates. Morphology, elemental depth distribution and phases of the layers were investigated before and after annealing using scanning electron microscopy, energy-dispersive X-ray spectroscopy and X-ray diffraction. Furthermore the influence of different heating rates on phase transitions during annealing was studied by in-situ X-ray diffraction.

The study of complex equilibria of uranium(VI) with selenate

International Nuclear Information System (INIS)

Lubal, P.; Havel, J.

1997-01-01

Uranyl (M)-selenate (L) complex equilibria in solution were investigated by spectrophotometry in visible range and potentiometry by means of uranyl ion selective electrode. The formation ML and ML 2 species was proved and the corresponding stability constants calculated were: log β 1 = 1.57 6 ± 0.01 6 , log β 2 = 2.42 3 ± 0.01 3 (I 3.0 mol 1 -1 Na(ClO 4 , SeO 4 ) (spectrophotometry) at 298.2 K. Using potentiometry the values for infinite dilution (I → 0 mol 1 -1 ) were: log β 1 = 2.64 ± 0.01, log β 2 ≤ 3.4 at 298.2 K. Absorption spectra of the complexes were calculated and analysed by deconvolution technique. Derivative spectrophotometry for the chemical model determination has also been successfully applied. (author)

The simulation of lunar gravity field recovery from D-VLBI of Chang’E-1 and SELENE lunar orbiters

Science.gov (United States)

Yan, Jianguo; Ping, Jingsong; Matsumoto, K.; Li, Fei

2008-07-01

The lunar gravity field is a foundation to study the lunar interior structure, and to recover the evolution history of the Moon. It is still an open and key topic for lunar science. For above mentioned reasons, it becomes one of the important scientific objectives of recent lunar missions, such as KAGUYA (SELENE) the Japanese lunar mission and Chang’E-1, the Chinese lunar mission. The Chang’E-1 and the SELENE were successfully launched in 2007. It is estimated that these two missions can fly around the Moon longer than 6 months simultaneously. In these two missions, the Chinese new VLBI (Very Long Baseline Interferometry) network will be applied for precise orbit determination (POD) by using a differential VLBI (D-VLBI) method during the mission period. The same-beam D-VLBI technique will contribute to recover the lunar gravity field together with other conventional observables, i.e. R&RR (Range and Range Rate) and multi-way Doppler. Taking VLBI tracking conditions into consideration and using the GEODYNII/SOVLE software of GSFC/NASA/USA [Rowlands, D.D., Marshall, J.A., Mccarthy, J., et al. GEODYN II System Description, vols. 1 5. Contractor Report, Hughes STX Corp. Greenbelt, MD, 1997; Ullman, R.E. SOLVE program: mathematical formulation and guide to user input, Hughes/STX Contractor Report, Contract NAS5-31760. NASA Goddard Space Flight Center, Greenbelt, Maryland, 1994], we simulated the lunar gravity field recovering ability with and without D-VLBI between the Chang’E-1 and SELENE main satellite. The cases of overlapped flying and tracking period of 30 days, 60 days and 90 days have been analyzed, respectively. The results show that D-VLBI tracking between two lunar satellites can improve the gravity field recovery remarkably. The results and methods introduced in this paper will benefit the actual missions.

Gamma-radiation and isotopic effect on the critical behavior in triglycine selenate crystals

Science.gov (United States)

Kassem, M. E.; Hamed, A. E.; Abulnasr, L.; Abboudy, S.

1994-11-01

Isotopic effects in pure and γ-irradiated triglycine selenate crystals were investigated using the specific heat ( Cp) technique. The obtained results showed an interesting dependence of the critical behavior of Cp on the deuterium content. With increasing content of deuterium, the character of the phase transition changed from a second order (γ-type) to a first order transition. After γ-irradiation, the behavior of Cp around the phase transition region was essentially affected. The transition temperature, Tc, decreased and Δ Cp depressed, and the transition became broad. It was noted that the effect of γ-irradiation is opposite to the isotopic effect.

Community ecology of the metazoan parasites of Atlantic Moonfish, Selene setapinnis (Osteichthyes: Carangidae from the coastal zone of the state of Rio de Janeiro, Brazil

Directory of Open Access Journals (Sweden)

A. S. Cordeiro

Full Text Available Eighty-nine specimens of Selene setapinnis (Mitchill, 1815 collected from the coastal zone of the State of Rio de Janeiro (21-23ºS, 41-45ºW and 23º05'S, 44º30'W, Brazil, from August 2001 to May 2002, were necropsied to study their metazoan parasites. Eighty-one (91% specimens of S. setapinnis were parasitized by one or more metazoan species. Twenty-one species of parasites were collected: 8 digeneans, 3 monogeneans, 2 cestodes, 5 nematodes, and 3 copepods. The endoparasites (digeneans, cestodes, and nematodes were 74.1% of total number of parasite specimens collected. The monogenean Pseudomazocraes selene (Hargis, 1957 was the most dominant species with the highest prevalence in the parasite community of S. setapinnis. The metazoan parasites of this host species showed the typical aggregated pattern of distribution. Only one parasite species (Acanthocolpoides pauloi Travassos, Freitas & Buhrnheim, 1955 showed positive correlation between the host total length and parasite abundance in S. setapinnis. Caligus robustus Bassett-Smith, 1898, P. selene, and Terranova sp. demonstrated positive correlation between the host total length and prevalence. Larvae of Terranova sp. showed influence of the host sex on its prevalence. A pair of ectoparasite species, P. selene-C. robustus, exhibited positive covariation between their abundances. Two pairs of endoparasite species, L. microstomum-P. merus and A. pauloi-P. merus showed significant covariation among their abundances; and the pair Terranova sp.-Raphidascaris sp. had positive co-ocorrence and covariation in the infracommunities of S. setapinnis. Like the parasite communities of the other carangid fishes from Rio de Janeiro, the parasite community of S. setapinnis is apparently only a slightly ordered species complex, characterized by dominance of endoparasite species.

Rover exploration on the lunar surface; a science proposal for SELENE-B mission

Science.gov (United States)

Sasaki, S.; Kubota, T.; Akiyama, H.; Hirata, N.; Kunii, Y.; Matsumoto, K.; Okada, T.; Otake, M.; Saiki, K.; Sugihara, T.

LUNARSURFACE:ASCIENCES. Sasaki (1), T. Kubota (2) , H. Akiyama (1) , N. Hirata (3), Y. Kunii (4), K. Matsumoto (5), T. Okada (2), M. Otake (3), K. Saiki (6), T. Sugihara (3) (1) Department of Earth and Planetary Science, Univ. Tokyo, (2) Institute of Space and Astronautical Sciences, (3) National Space Development Agency of Japan, (4) Department of Electrical and Electronic Engineering, Chuo Univ., (5) National Aerospace Laboratory of Japan, (6) Research Institute of Materials and Resources, Akita Univ. sho@eps.s.u -tokyo.ac.jp/Fax:+81-3-5841-4569 A new lunar landing mission (SELENE-B) is now in consideration in Japan. Scientific investigation plans using a rover are proposed. To clarify the origin and evolution of the moon, the early crustal formation and later mare volcanic processes are still unveiled. We proposed two geological investigation plans: exploration of a crater central peak to discover subsurface materials and exploration of dome-cone structures on young mare region. We propose multi-band macro/micro camera using AOTF, X-ray spectrometer/diffractometer and gamma ray spectrometer. Since observation of rock fragments in brecciaed rocks is necessary, the rover should have cutting or scraping mechanism of rocks. In our current scenario, landing should be performed about 500m from the main target (foot of a crater central peak or a cone/dome). After the spectral survey by multi-band camera on the lander, the rover should be deployed for geological investigation. The rover should make a short (a few tens meter) round trip at first, then it should perform traverse observation toward the main target. Some technological investigations on SELENE-B project will be also presented.

Gamma-radiation and isotopic effect on the critical behavior in triglycine selenate crystals

International Nuclear Information System (INIS)

Kassem, M.E.; Hamed, A.E.; Abulnasr, L.; Abboudy, S.

1994-01-01

Isotopic effects in pure and γ-irradiated triglycine selenate crystals were investigated using the specific heat (C p ) technique. The obtained results showed an interesting dependence of the critical behavior of C p on the deuterium content. With increasing content of deuterium, the character of the phase transition changed from a second order (λ-type) to a first order transition. After γ-irradiation, the behavior of C p around the phase transition region was essentially affected. The transition temperature, T c , decreased and ΔC p depressed, and the transition became broad. It was noted that the effect of γ-irradiation is opposite to the isotopic effect. (author)

An optional focusing SELENE extension to conventional neutron guides: A case study for the ESS instrument BIFROST

Energy Technology Data Exchange (ETDEWEB)

Hansen, U.B., E-mail: uhansen@nbi.ku.dk [Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen (Denmark); Bertelsen, M. [Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen (Denmark); Stahn, J. [Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland); Lefmann, K. [Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen (Denmark)

2017-04-21

The high brilliance at the European Spallation Source (ESS) will allow for performing experiments with much smaller samples than at present neutron facilities and in much more complex sample environments. However the higher flux also results in higher background from unwanted neutrons not originating from scattering of the sample. We here present a new design idea for beam delivery, where a 165 m ballistic guide system with good transport properties is followed by a 4–8 m SELENE guide system similar to Montel optics used for X-ray optics. We have investigated the system by detailed Monte-Carlo simulations using McStas. We show that under certain conditions, this set-up works surprisingly well, with a brilliance transfer of 20–60% for neutrons of wavelength 4 Å and above. We demonstrate that the guide system is able to focus the beam almost perfectly onto samples sizes in the range of 0.1–2 mm. We furthermore show that our SELENE system is insensitive to gravity and to realistic values of guide waviness. We argue that this guide system can be useful as an optional guide insert when small samples are used in the vicinity of bulky sample environment, e.g. for high-field or high-pressure experiments.

Selenium deficiency occurs in some patients with moderate-to-severe cirrhosis and can be corrected by administration of selenate but not selenomethionine: a randomized controlled trial123

Science.gov (United States)

Burk, Raymond F; Hill, Kristina E; Motley, Amy K; Byrne, Daniel W; Norsworthy, Brooke K

2015-01-01

Background: Selenomethionine, which is the principal dietary form of selenium, is metabolized by the liver to selenide, which is the form of the element required for the synthesis of selenoproteins. The liver synthesizes selenium-rich selenoprotein P (SEPP1) and secretes it into the plasma to supply extrahepatic tissues with selenium. Objectives: We conducted a randomized controlled trial to determine whether cirrhosis is associated with functional selenium deficiency (the lack of selenium for the process of selenoprotein synthesis even though selenium intake is not limited) and, if it is, whether the deficiency is associated with impairment of selenomethionine metabolism. Design: Patients with Child-Pugh (C-P) classes A, B, and C (mild, moderate, and severe, respectively) cirrhosis were supplemented with a placebo or supranutritional amounts of selenium as selenate (200 or 400 μg/d) or as selenomethionine (200 μg/d) for 4 wk. Plasma SEPP1 concentration and glutathione peroxidase (GPX) activity, the latter due largely to the selenoprotein GPX3 secreted by the kidneys, were measured before and after supplementation. Results: GPX activity was increased more by both doses of selenate than by the placebo in C-P class B patients. The activity was not increased more by selenomethionine supplementation than by the placebo in C-P class B patients. Plasma selenium was increased more by 400 μg Se as selenate than by the placebo in C-P class C patients. Within the groups who responded to selenate, there was a considerable variation in responses. Conclusion: These results indicate that severe cirrhosis causes mild functional selenium deficiency in some patients that is associated with impaired metabolism of selenomethionine. This trial was registered at clinicaltrials.gov as NCT00271245. PMID:26468123

Preparation and Characterization of Cu(In,GaSe2 Thin Films by Selenization of Cu0.8Ga0.2 and In2Se3 Precursor Films

Directory of Open Access Journals (Sweden)

Jiang Liu

2012-01-01

Full Text Available Se-containing precursor films with two different compositions were prepared by magnetron sputtering from and targets, and then were selenized using Se vapor. The effects of precursor composition and selenization temperature on the film properties were investigated. The results show that Se phase plays a critical role in film growth and electrical properties of CIGS films. The Cu-rich films exhibit different surface morphology and better crystallinity, as compared to the Cu-poor films. All the CIGS films exhibit p-type conductivity. The resistivity of the Cu-rich films is about three orders of magnitude lower than that of the Cu-poor films, which is attributed to the presence of p-type highly conductive Se phase.

Gamma-radiation and isotopic effect on the critical behavior in triglycine selenate crystals

Energy Technology Data Exchange (ETDEWEB)

Kassem, M.E.; Hamed, A.E.; Abulnasr, L.; Abboudy, S. [Alexandria Univ. (Egypt). Dept. of Physics

1994-11-01

Isotopic effects in pure and {gamma}-irradiated triglycine selenate crystals were investigated using the specific heat (C{sub p}) technique. The obtained results showed an interesting dependence of the critical behavior of C{sub p} on the deuterium content. With increasing content of deuterium, the character of the phase transition changed from a second order ({lambda}-type) to a first order transition. After {gamma}-irradiation, the behavior of C{sub p} around the phase transition region was essentially affected. The transition temperature, T{sub c}, decreased and {Delta}C{sub p} depressed, and the transition became broad. It was noted that the effect of {gamma}-irradiation is opposite to the isotopic effect. (author).

Study of the Cupriavidus metallidurans CH34 resistance of selenite and selenate oxy-anions: accumulation, localisation and transformation of selenium; Etude de la resistance de Cupriavidus metallidurans CH34 aux oxyanions selenite et seleniate: accumulation, localisation et transformation du selenium

Energy Technology Data Exchange (ETDEWEB)

Avoscan, L

2007-06-15

Selenium is an essential trace element for the living organisms but it is very toxic at high concentration. Selenite and selenate oxides, soluble forms, highly toxic and bio-assimilable, are the most prevalent forms in the environment. Some soil micro-organisms play a dominant role and contribute to the natural cycle of selenium. Our study model, Cupriavidus (formerly Ralstonia) metallidurans CH34, a telluric bacterium characteristic of metal-contaminated biotopes, is known to resist selenite by reducing it into elemental selenium, an insoluble and less toxic form of selenium. In order to better understand the mechanisms of selenium reduction in the bacteria, three methods of speciation were combined (XAS (XANES and EXAFS), HPLC-ICP-MS and SDS-PAGEPIXE). They were completed by the direct quantification of selenium accumulated in the bacteria. Speciation analyses highlighted the existence of two mechanisms of reduction of selenium oxides in C. metallidurans CH34. Assimilation transforms selenite and selenate into organic selenium, identified as seleno-methionine and leads to its non-specific incorporation into bacterial proteins (presence of selenious proteins). Detoxication precipitates selenite in nano-particles of elemental selenium. This way of detoxication is not set up after an exposure to selenate although it is nevertheless possible to detect elemental selenium but in very small amount compared to the exposure of selenite. Seleno-diglutathion is detected in bacteria stressed by an exposure to selenate in medium limited in sulphate. Bacteria exposed to selenite accumulate 25 times more selenium than when they are exposed to selenate. The study of mutants resistant to selenite, which do not express the membrane protein DedA, showed that the accumulation of selenium after exposure to selenite is decreased compared with the wild strain meaning probable link between the transport of selenite and the DedA protein. Finally, selenate would use the sulphate permease

THE EFFECTS OF SODIUM SELENITE AND SELENIZED YEAST SUPPLEMENTATION INTO DIET FOR LAYING HENS ON SELECTED QUALITATIVE PARAMETERS OF TABLE EGGS

Directory of Open Access Journals (Sweden)

HENRIETA ARPÁŠOVÁ

2009-10-01

Full Text Available In this experiment the effects of supplementation of the diet for laying hens with sodium selenite (SS or selenized yeast (SY on whole egg and egg shell quality of layers were studied. The chickens of Shaver Starcross 288 strain were randomly divided at the day of hatching into 4 groups (n=12; in each. The birds were fed from Day 1 of life to 9 months of age with diets differing in amounts and/or forms of selenium. Control group received basal diet (BD containing selenium naturally occurring in feeds (0.1 mg Se/kg of dry matter (DM. First and second experimental group of chickens were fed with a same BD enriched with equivalent dose of Se 0.4 mg/kg DM in form of sodium selenite or selenized yeast, respectively. The feed for third experimental group of birds consisted of BD supplemented with selenized yeast to the final amount of selenium 1.0 mg/kg DM. The egg weight was significantly higher in the groups with SY supplementation only. On the contrary the egg shell ratio was significantly lower in the groups with SY supplementation in both amounts. The width of egg was significantly increased in the groups with selenium supplementation in both forms. The value of egg shell strength was significantly decreased in group with SY in the highest amount 0.9 mg/kg DM The average egg shell thickness was the highest in the experimental group with Se-yeast in amount 0.9 mg/kg DM, however different was not significant compared with control group. The results showed that the most of selected parameters of egg quality appeared to be significantly influenced by selenium supplementation into laying hen’s basal diet.

Selenized milk casein in the diet of BALB/c nude mice reduces growth of intramammary MCF-7 tumors

International Nuclear Information System (INIS)

Warrington, Jenny M; Kim, Julie JM; Stahel, Priska; Cieslar, Scott RL; Moorehead, Roger A; Coomber, Brenda L; Corredig, Milena; Cant, John P

2013-01-01

Dietary selenium has the potential to reduce growth of mammary tumors. Increasing the Se content of cows’ milk proteins is a potentially effective means to increase Se intake in humans. We investigate the effects of selenized milk protein on human mammary tumor progression in immunodeficient BALB/c nude mice. Four isonitrogenous diets with selenium levels of 0.16, 0.51, 0.85 and 1.15 ppm were formulated by mixing low- and high-selenium milk casein isolates with a rodent premix. MCF-7 cells were inoculated into the mammary fat pad of female BALB/c nude mice implanted with slow-release 17 β-estradiol pellets. Mice with palpable tumors were randomly assigned to one of the four diets for 10 weeks, during which time weekly tumor caliper measurements were conducted. Individual growth curves were fit with the Gompertz equation. Apoptotic cells and Bcl-2, Bax, and Cyclin D1 protein levels in tumors were determined. There was a linear decrease in mean tumor volume at 70 days with increasing Se intake (P < 0.05), where final tumor volume decreased 35% between 0.16 and 1.15 ppm Se. There was a linear decrease in mean predicted tumor volume at 56, 63 and 70 days, and the number of tumors with a final volume above 500 mm 3 , with increasing Se intake (P < 0.05). This tumor volume effect was associated with a decrease in the proportion of tumors with a maximum growth rate above 0.03 day -1 . The predicted maximum volume of tumors (V max ) and the number of tumors with a large V max , were not affected by Se-casein. Final tumor mass, Bcl-2, Bax, and Cyclin D1 protein levels in tumors were not significantly affected by Se-casein. There was a significantly higher number of apoptotic cells in high-Se tumors as compared to low-Se tumors. Taken together, these results suggest that turnover of cells in the tumor, but not its nutrient supply, were affected by dairy Se. We have shown that 1.1 ppm dietary Se from selenized casein can effectively reduce tumor progression in an MCF-7

Influence of selenite and selenate supplementation on the chromium uptake and translocation in Allium cepa

International Nuclear Information System (INIS)

Karuna Shanker; Setia, Seema; Srivastava, Shalini; Dass, Sahab; Srivastava, Rohit; Satya Prakash; Srivastava, M.M.

1997-01-01

Pot experiments were conducted on onion plant to study the effects of selenite and selenate treatments (0.5-6.0) μg ml -1 on the uptake and translocation of root absorbed chromium irrigated with 2 and 5 μg ml -1 of chromium in sand and soil. Both the form of selenium (SeO 3 2- , and SeO 4 2- ) were found equally effective in reducing the chromium burden of the plant. No significant difference (p>0.05) in dry matter yields among various selenium treatments exist suggesting no salt injury occurred in the plants under prevailing conditions. (author). 10 refs., 1 tab

Cation–Anion Interactions within the Nucleic Acid Ion Atmosphere Revealed by Ion Counting

Science.gov (United States)

Gebala, Magdalena; Giambasu, George M.; Lipfert, Jan; Bisaria, Namita; Bonilla, Steve; Li, Guangchao; York, Darrin M.; Herschlag, Daniel

2016-01-01

The ion atmosphere is a critical structural, dynamic, and energetic component of nucleic acids that profoundly affects their interactions with proteins and ligands. Experimental methods that “count” the number of ions thermodynamically associated with the ion atmosphere allow dissection of energetic properties of the ion atmosphere, and thus provide direct comparison to theoretical results. Previous experiments have focused primarily on the cations that are attracted to nucleic acid polyanions, but have also showed that anions are excluded from the ion atmosphere. Herein, we have systematically explored the properties of anion exclusion, testing the zeroth-order model that anions of different identity are equally excluded due to electrostatic repulsion. Using a series of monovalent salts, we find, surprisingly, that the extent of anion exclusion and cation inclusion significantly depends on salt identity. The differences are prominent at higher concentrations and mirror trends in mean activity coefficients of the electrolyte solutions. Salts with lower activity coefficients exhibit greater accumulation of both cations and anions within the ion atmosphere, strongly suggesting that cation–anion correlation effects are present in the ion atmosphere and need to be accounted for to understand electrostatic interactions of nucleic acids. To test whether the effects of cation–anion correlations extend to nucleic acid kinetics and thermodynamics, we followed the folding of P4–P6, a domain of the Tetrahymena group I ribozyme, via single-molecule fluorescence resonance energy transfer in solutions with different salts. Solutions of identical concentration but lower activity gave slower and less favorable folding. Our results reveal hitherto unknown properties of the ion atmosphere and suggest possible roles of oriented ion pairs or anion-bridged cations in the ion atmosphere for electrolyte solutions of salts with reduced activity. Consideration of these new

Selenization of mixed metal oxides for dense and ZnSe-free Cu{sub 2}ZnSnSe{sub 4} absorber films

Energy Technology Data Exchange (ETDEWEB)

Deng, Yitao; Chen, Guilin; Pan, Bin; Li, JianMin; Jiang, Guoshun; Liu, Weifeng, E-mail: liuwf@ustc.edu.cn; Zhu, Changfei, E-mail: cfzhu@ustc.edu.cn

2014-04-05

Highlights: • ZnSe-free CZTSe films with large grains was prepared from mixed oxides nanopraticles. • Appearance of Zn{sub 2}SnO{sub 4} in mixed oxides precursors leads to the absence of ZnSe secondary phrase. • To obtain pure CZTSe phase, different treating temperature was used. -- Abstract: Cu{sub 2}ZnSnSe{sub 4} (CZTSe) films were prepared by direct selenization of Cu{sub 2}O, SnO{sub 2} and Zn{sub 2}SnO{sub 4} precursors. Oxides precursors were prepared by baking hydroxides precipitation. In order to obtain ZnSe-free CZTSe films, Zn{sub 2}SnO{sub 4} was used to replace separated ZnO and SnO{sub 2} as one of the precursors. Through X-ray diffraction (XRD), scanning electron microscopy (SEM), it was found that CZTSe films, with micron-sized dense grains, were obtained in our work. From Raman spectra, it was also found that the ZnSe secondary phase was absent after the selenization. An energy bandgap about 0.86 eV was obtained in our work, which confirmed the Stannite-CZTSe structure.

Broadband and polarization reflectors in the lookdown, Selene vomer.

Science.gov (United States)

Zhao, Shulei; Brady, Parrish Clawson; Gao, Meng; Etheredge, Robert Ian; Kattawar, George W; Cummings, Molly E

2015-03-06

Predator evasion in the open ocean is difficult because there are no objects to hide behind. The silvery surface of fish plays an important role in open water camouflage. Various models have been proposed to account for the broadband reflectance by the fish skin that involve one-dimensional variations in the arrangement of guanine crystal reflectors, yet the three-dimensional organization of these guanine platelets have not been well characterized. Here, we report the three-dimensional organization and the optical properties of integumentary guanine platelets in a silvery marine fish, the lookdown (Selene vomer). Our structural analysis and computational modelling show that stacks of guanine platelets with random yaw angles in the fish skin produce broadband reflectance via colour mixing. Optical axes of the guanine platelets and the collagen layer are aligned closely and provide bulk birefringence properties that influence the polarization reflectance by the skin. These data demonstrate how the lookdown preserves or alters polarization states at different incident polarization angles. These optical properties resulted from the organization of these guanine platelets and the collagen layer may have implications for open ocean camouflage in varying light fields. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

Abiotic pyrite reactivity versus nitrate, selenate and selenite using chemical and electrochemical methods

International Nuclear Information System (INIS)

Ignatiadis, I.; Betelu, S.; Gaucher, E.; Tournassat, C.; Chainet, F.

2010-01-01

Document available in extended abstract form only. This work is part of ReCosy European project (www.recosy.eu), whose main objectives are the sound understanding of redox phenomena controlling the long-term release/retention of radionuclides in nuclear waste disposal and providing tools to apply the results to performance assessment/safety case. Redox is one of the main factor affecting speciation and mobility of redox-sensitive radionuclides. Thus, it is of a great importance to investigate the redox reactivity of the host radioactive waste formations, particularly when exposed to redox perturbations. Callovo-Oxfordian formation (COx), a clay rock known as an anoxic and reducing system, was selected in France as the most suitable location to store nuclear waste. Iron (II) sulfide, mostly constituted of pyrite (FeS 2 ), iron (II) carbonate, iron(II) bearing clays and organic matter are considered to account almost entirely for the total reducing capacity of the rock. We report here the redox reactivity of pyrite upon exposure to nitrate (N(V)), selenate (Se(VI)) and selenite (Se(IV)) that possibly occur in the nuclear storage. Both, chemical and electrochemical kinetic approaches were simultaneously conducted such as to (i) determine the kinetics parameters of the reactions and (ii) understand the kinetic mechanisms. In order to reach similar conditions that are encountered in the storage system, all experiments were realised in NaCl 0.1 M, near neutral pH solutions, and an abiotic glove box (O 2 less than 10 -8 M). Chemical approach has consisted to set in contact pyrite in grains with solutions containing respectively nitrate, selenate and selenite. Reactants and products chemical analyses, conducted at different contact times, allowed us to assess the kinetics of oxidant reduction. Electrochemical approach has consisted in the continuous or semi-continuous analysis of large surface pyrite electrodes immersed in solutions with or without oxidant (nitrate

EXAFS and FTIR studies of selenite and selenate sorption by alkoxide-free sol–gel generated Mg–Al–CO 3 layered double hydroxide with very labile interlayer anions

KAUST Repository

Chubar, Natalia

2014-01-01

© the Partner Organisations 2014. Current research on Layered Double Hydroxides (LDHs, also known as hydrotalcites, HTs) is predominantly focused on their intercalations, but the industrial application of LDHs for anion exchange adsorption has not yet been achieved. It was recently recognized that, to develop LDH applications, these materials should be produced using methods other than direct co-precipitation. Mg-Al-CO3LDH produced using an alkoxide-free sol-gel synthesis showed exceptional removal properties for aqueous selenium species. Se K-edge EXAFS/XANES and FTIR studies (supporting the data by XRD patterns) were performed to explain the unusual adsorptive performance of Mg-Al LDH by revealing the molecular-level mechanism of HSeO3 -, SeO4 2-and {HSeO3 -+ SeO4 2-} uptake at pH 5, 7 and 8.5. The role of inner-sphere complexation (exhibited by inorganic adsorbents with good performance) in adsorption of both selenium aqueous species was not confirmed. However, Mg-Al LDH fully met the other expectations regarding the involvement of the interlayer anions. The interlayer carbonate (due to its favorable speciation and generous HT hydration) gave a "second breath" to selenite sorption and was the only mechanism that controlled the removal of Se(vi). Because inner sphere complexation was the leading mechanism for selenite removal, ion exchange via surface OH-and interlayer CO3 2-species was the only mechanism for selenate removal; both of these species were easily bound to Mg-Al LDH (on its surface and gently parked into the interlayer forming a multilayer without violation of the structure of Mg-Al-CO3LDH). This work provides the first theoretical explanation of why it is more difficult to sorb selenate than selenite and which material should be used for this purpose. This journal is

EXAFS and FTIR studies of selenite and selenate sorption by alkoxide-free sol–gel generated Mg–Al–CO 3 layered double hydroxide with very labile interlayer anions

KAUST Repository

Chubar, Natalia

2014-08-08

© the Partner Organisations 2014. Current research on Layered Double Hydroxides (LDHs, also known as hydrotalcites, HTs) is predominantly focused on their intercalations, but the industrial application of LDHs for anion exchange adsorption has not yet been achieved. It was recently recognized that, to develop LDH applications, these materials should be produced using methods other than direct co-precipitation. Mg-Al-CO3LDH produced using an alkoxide-free sol-gel synthesis showed exceptional removal properties for aqueous selenium species. Se K-edge EXAFS/XANES and FTIR studies (supporting the data by XRD patterns) were performed to explain the unusual adsorptive performance of Mg-Al LDH by revealing the molecular-level mechanism of HSeO3 -, SeO4 2-and {HSeO3 -+ SeO4 2-} uptake at pH 5, 7 and 8.5. The role of inner-sphere complexation (exhibited by inorganic adsorbents with good performance) in adsorption of both selenium aqueous species was not confirmed. However, Mg-Al LDH fully met the other expectations regarding the involvement of the interlayer anions. The interlayer carbonate (due to its favorable speciation and generous HT hydration) gave a "second breath" to selenite sorption and was the only mechanism that controlled the removal of Se(vi). Because inner sphere complexation was the leading mechanism for selenite removal, ion exchange via surface OH-and interlayer CO3 2-species was the only mechanism for selenate removal; both of these species were easily bound to Mg-Al LDH (on its surface and gently parked into the interlayer forming a multilayer without violation of the structure of Mg-Al-CO3LDH). This work provides the first theoretical explanation of why it is more difficult to sorb selenate than selenite and which material should be used for this purpose. This journal is

Preparation of SnSe thin films by encapsulated selenization; Saput tipis SnSe disediakan dengan kaedah penselenidan tertudung-tebat

Energy Technology Data Exchange (ETDEWEB)

Sabar, D Hutagalung [Universitas Sumatera Utara, Medan (Indonesia). Dept. of Physics; Sakrani, Samsudi; Wahab, Yussof [Universiti Teknologi Malaysia, Skudai, Johor Bahru (Malaysia). Dept. of Physics

1994-12-31

Tin selenide thin films were prepared by encapsulated selenization. A stacked layer of evaporated Sn and Se films were annealed in a carbon block at temperatures 100 - 500 degree Celsius for 3 hours. X-ray analysis and SEM (Scanning electron) micrograph results showed that SnSe was initially formed at 150 degree Celsius with crystal size 30.0 nm and reached optimum formation at 200 daximum of 57.4 % yield of 5-decene. Other factors such as reaction temperatures, types of solvent and wt% of rhenium loadings influence the activity of the catalytic system.

Studies of rubidium selenate with secondary phase of RbOH under humidified reducing atmosphere

DEFF Research Database (Denmark)

Beyribey, Berceste; Hallinder, Jonathan; Poulsen, Finn Willy

2012-01-01

The high temperature properties of Rb2SeO4 have been studied by calorimetry, impedance spectroscopy and X-ray powder diffraction. As synthesized, Rb2SeO4 includes a second phase of Rb2SeO3, which can be eliminated upon heating the compound. As expected, no conductivity is observed in dry (pH2O ....001 bar) air. By changing to humidified (pH2O = 0.1 bar) air at 176 deg. C, the conductivity increases sharply from 8.6·10-8 to 1.7·10-6 S cm-1. Under humidified (pH2O = 0.1 bar) reducing atmosphere (9%H2 in N2), the conductivity increases to 2.0·10-4 S cm-1 at 317 C. Degradation of Rb2SeO3 and Rb2SeO4...

Initial investigations of microscale cellular convection in an equatorial marine atmospheric boundary layer revealed by lidar

Science.gov (United States)

Cooper, D. I.; Eichinger, W. E.; Ecke, R. E.; Kao, J. C. Y.; Reisner, J. M.; Tellier, L. L.

During the Combined Sensor Program (CSP) in March of 1996, the Los Alamos National Laboratory (LANL) fielded an advanced scanning Raman lidar. The lidar was part of a larger suite of micrometeorological sensors to quantify processes associated with the ocean-atmosphere interface, including intermittency and coherent atmospheric features in the “warm pool” of the Tropical Western Pacific (TWP) near Manus Island (2° S. lat, 147° E. long). Initial inspection of the data has revealed excellent information on the microscale vertical and horizontal spatial and temporal structure of the equatorial Marine Atmospheric Boundary Layer (MABL). The data from this experiment have added to the increasing body of measurements on surface layer convection and intermittency including, for the first time, the observation of microscale cellular convective structures such as hexagonal patterns associated with Rayleigh-Bénard cells.

[Pb2F2](SeO4): a heavier analogue of grandreefite, the first layered fluoride selenate

Science.gov (United States)

Charkin, Dmitri O.; Plokhikh, Igor V.; Zadoya, Anastasiya I.; Kazakov, Sergey M.; Zaloga, Alexander N.; Kozin, Michael S.; Depmeier, Wulf; Siidra, Oleg I.

2018-01-01

Co-precipitation of PbF2 and PbSeO4 in weakly acidic media results in the formation of [Pb2F2](SeO4), the selenate analogue of the naturally occurring mineral grandreefite, [Pb2F2](SO4). The new compound is monoclinic, C2/ c, a = 14.0784(2) Å, b = 4.6267(1) Å, c = 8.8628(1) Å, β = 108.98(1)°, V = 545.93(1) Å3. Its structure has been refined from powder data to R B = 1.55%. From thermal studies, it is established that the compound is stable in air up to about 300 °C, after which it gradually converts into a single phase with composition [Pb2O](SeO4), space group C2/ m, and lattice parameters a = 14.0332(1) Å, b = 5.7532(1) Å, c = 7.2113(1) Å, β = 115.07(1)°, V = 527.37(1) Å3. It is the selenate analogue of lanarkite, [Pb2O](SO4), and phoenicochroite, [Pb2O](CrO4), and its crystal structure was refined to R B = 1.21%. The formation of a single decomposition product upon heating in air suggests that this happens by a thermal hydrolysis mechanism, i.e., Pb2F2SeO4 + H2O (vapor) → Pb2OSeO4 + 2HF↑. This relatively low-temperature process involves complete rearrangement of the crystal structure—from a 2D architecture featuring slabs [Pb2F2]2+ formed by fluorine-centered tetrahedra into a structure characterized by 1D motifs based on [OPb2]2+ chains of oxocentered tetrahedra. The comparative crystal chemistry of the obtained anion-centered structural architectures is discussed.

Fabrication of selenization-free superstrate-type CuInS{sub 2} solar cells based on all-spin-coated layers

Energy Technology Data Exchange (ETDEWEB)

Cheshme khavar, Amir Hossein [Department of Chemistry, Tarbiat Modares University, P.O. Box. 14155-4383, Gisha Bridge, Tehran (Iran, Islamic Republic of); Mahjoub, Alireza, E-mail: mahjouba@modares.ac.ir [Department of Chemistry, Tarbiat Modares University, P.O. Box. 14155-4383, Gisha Bridge, Tehran (Iran, Islamic Republic of); Samghabadi, Farnaz Safi [Physics Department, Sharif University of Technology, Tehran, 14588 (Iran, Islamic Republic of); Taghavinia, Nima, E-mail: taghavinia@sharif.edu [Physics Department, Sharif University of Technology, Tehran, 14588 (Iran, Islamic Republic of); Institute for Nanoscience and Nanotechnology, Sharif University of Technology, Tehran, 14588 (Iran, Islamic Republic of)

2017-01-15

Today manufacturing of high efficiency chalcogenide thin film solar cells is based on high cost vacuum-based deposition processes at high temperature (>500 °C) and in chalcogen -containing atmosphere. In this paper, we introduce a simple vacuum-free and selenization-free, solution processing for fabricating a superstrate-type CuInS{sub 2} (CIS) solar cell. The absorber, buffer and blocking layers were all deposited by spin coating of molecular precursor inks. We demonstrate the deposition of In{sub 2}S{sub 3} buffer layer by sol-gel spin casting for the first time. The rapid sintering process of CIS layer was carried out at 250 °C that is considered a very low temperature in CIGS thin-film technologies. A novel molecular-ink route to deposit In{sub 2}S{sub 3} type buffer layer is presented. For the back contact we employed carbon, deposited by simple knife coating method. Different parameters including type of buffer, thickness of absorber layer, CIS and In{sub 2}S{sub 3} annealing temperature and morphology were optimized. Our air stable simple device structure consisting of showed promising power conversion efficiency (PCE) of 2.67%. - Highlights: • This work is an effort on the fabrication of all spin-coated CIS solar cells. • A novel molecular-ink route to deposit In{sub 2}S{sub 3} type buffer layer is presented. • The best devices showed power conversion efficiency (PCE) of 2.67%.

Syntheses, structures, and IR spectroscopic characterization of new uranyl sulfate/selenate 1D-chain, 2D-sheet and 3D-framework

Energy Technology Data Exchange (ETDEWEB)

Ling Jie; Sigmon, Ginger E.; Ward, Matthew; Roback, Nancy; Burns, Peter C. [Dept. of Civil Engineering and Geological Science, Univ. of Notre Dame, IN (United States)

2010-07-01

Three uranyl sulfates, (C{sub 6}H{sub 20}N{sub 4})[(UO{sub 2}){sub 2} . (SO{sub 4}){sub 4}(H{sub 2}O){sub 2}](H{sub 2}O){sub 6} (TETAUS), (C{sub 15}H{sub 14}N{sub 3})[(UO{sub 2}) . (SO{sub 4}){sub 2}](NO{sub 3})(H{sub 2}O){sub 2} (TPUS), and K{sub 2}[(UO{sub 2})(SO{sub 4}){sub 2}(H{sub 2}O)] . H{sub 2}O (KUS), and two uranyl selenates, K(H{sub 3}O)[(UO{sub 2}){sub 2} . (SeO{sub 4}){sub 3}(H{sub 2}O)](H{sub 2}O){sub 6} (KUSe) and (H{sub 3}O){sub 2}[(UO{sub 2}){sub 2}(SeO{sub 4}){sub 3} . (H{sub 2}O)] (USe), were synthesized by slow evaporation of aqueous solutions at room temperature. TETAUS crystallizes in space group P anti 1, a = 6.7186(5) A, b = 9.2625(7) A, c = 13.1078(9) A, {alpha} = 72.337(2) , {beta} = 89.198(2) , {gamma} = 70.037(1) , V = 726.89(9) A{sup 3}, Z = 1. TPUS is triclinic, P anti 1, a = 6.9732(7) A, b = 13.569(1) A, c = 13.641(1) A, {alpha} = 111.809(2) , {beta} = 102.386(2) , {gamma} = 93.833(2) , V = 1150.0(2) A{sup 3}, Z = 2. KUS is orthorhombic, Cmca, a = 12.171(2) A, b = 16.689(3) A, c = 10.997(2) A, V = 2233.8(6) A{sup 3}, Z = 8. These uranyl sulfates are built from infinite one-dimensional uranyl sulfate chains with different topologies. KUSe is monoclinic, P2{sub 1}/n, a = 14.715(1) A, b = 10.1557(7) A, c = 15.833(1) A, {beta} = 114.415(1) , V = 2154.5(3) A{sup 3}, Z = 4. Its structure is based on a two-dimensional uranyl selenate sheet. USe crystallizes in space group P2{sub 1}/c, a = 10.6124(2) A, b = 14.7717(3) A, c = 13.7139(3) A, {beta} = 96.989(1) , V = 2133.86(8) A{sup 3}, Z = 4, with a complex three-dimensional uranyl selenate framework containing channels extending in three directions. (orig.)

Microstructure of atmospheric particles revealed by TXM and a new mode of influenza virus transmission

Energy Technology Data Exchange (ETDEWEB)

Bao, L.M., E-mail: baoliangman@sinap.ac.cn [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); Zhang, G.L., E-mail: zhangguilin@sinap.ac.cn [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); Lei, Q.T.; Li, Y.; Li, X.L. [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); Hwu, Y.K. [Institute of Physics, Academia Sinica, Taipei 11529, Taiwan (China); Yi, J.M. [Advanced Photon Source, Argonne National Laboratory, Argonne 60439 (United States)

2015-09-15

For control of influenza, firstly it is important to find the real virus transmission media. Atmospheric aerosol particles are presumably one of the media. In this study, three typical atmospheric inhaled particles in Shanghai were studied by the synchrotron based transmission X-ray microscopes (TXM). Three dimensional microstructure of the particles reveals that there are many pores contained in, particularly the coal combustion fly particles which may be possible virus carrier. The particles can transport over long distance and cause long-range infections due to its light weight. We suggest a mode which is droplet combining with aerosol mode. By this mode the transmission of global and pandemic influenzas and infection between inland avian far from population and poultry or human living in cities along coast may be explained.

Study of Pitch Attitude Estimation Using a High-Definition TV (HDTV) Camera on the Japanese Lunar Explorer SELENE (KAGUYA)

Science.gov (United States)

Sobue, Shinichi; Yamazaki, Junichi; Matsumoto, Shuichi; Konishi, Hisahiro; Maejima, Hironori; Sasaki, Susumu; Kato, Manabu; Mitsuhashi, Seiji; Tachino, Junichi

The lunar explorer SELENE (also called KAGUYA) carried thirteen scientific mission instruments to reveal the origin and evolution of Moon and to investigate the possible future utilization of Moon. In addition to the scientific instruments, a high-definition TV (HDTV) camera provided by the Japan Broadcasting Corporation (NHK) was carried on KAGUYA to promote public outreach. We usually use housekeeping telemetry data to derive the satellite attitude along with orbital determination and propagated information. However, it takes time to derive this information, since orbital determination and propagation calculation require the use of the orbital model. When a malfunction of the KAGUYA reaction wheel occurred, we could not have correct attitude information. This means that we don’t have a correct orbital determination in timely fashion. However, when we checked HDTV movies, we found that horizon information on the lunar surface derived from HDTV moving images as a horizon sensor was very useful for the detection of the attitude of KAGUYA. We then compared this information with the attitude information derived from orbital telemetry to validate the accuracy of the HDTV derived estimation. As a result of this comparison, there are good pitch attitude estimation using HDTV derived estimation and we could estimate the pitch angle change during the KAGUYA mission operation simplify and quickly. In this study, we show the usefulness of this HDTV camera as a horizon sensor.

Chiral speciation and determination of selenomethionine enantiomers in selenized yeast by ligand-exchange micellar electrokinetic capillary chromatography after solid phase extraction.

Science.gov (United States)

Duan, Jiankun; He, Man; Hu, Bin

2012-12-14

A new phenylalanine derivative (L-N-(2-hydroxy-propyl)-phenylalanine, L-HP-Phe) was synthesized and its chelate with Cu(II) (Cu(II)-(L-HP-Phe)(2)) was used as the chiral selector for the ligand-exchange (LE) chiral separation of D,L-selenomethionine (SeMet) in selenized yeast samples by micelle electrokinetic capillary chromatography (MEKC). In order to improve the sensitivity of MEKC-UV, two-step preconcentration strategy was employed, off-line solid phase extraction (SPE) and on-line large volume sample stacking (LVSS). D,L-SeMet was first retained on the Cu(II) loaded mesoporous TiO(2), then eluted by 0.1 mL of 5 mol L(-1) ammonia, and finally introduced for MEKC-UV analysis by LVSS injection after evaporation of NH(3). With the enrichment factors of 1400 and 1378, the LODs of 0.44 and 0.60 ng mL(-1) for L-SeMet and D-SeMet was obtained, respectively. The developed method was applied to the analysis of D,L-SeMet in a certified reference material of SELM-1 and a commercial nutrition yeast, and the results showed that most of SeMet in the SELM-1 selenized yeast was l isomer and the recovery for L and D isomers in the spiked commercial nutrition yeast was 96.3% and 103%, respectively. This method is featured with low running cost, high sensitivity and selectivity, and exhibits application potential in chiral analysis of seleno amino acids in real world samples. Copyright © 2012 Elsevier B.V. All rights reserved.

Sorption mechanisms of selenium species (selenite and selenate) on copper-based minerals; Mecanismes de sorption des especes du selenium (selenite et seleniate) sur des mineraux a base de cuivre

Energy Technology Data Exchange (ETDEWEB)

Devoy, J

2001-09-01

The sorption of radionuclides on the surface of minerals represents a process capable to delay the migration of the elements from a spent fuel deep repository towards the biosphere. In the framework of a deep underground repository, an engineered clay barrier has a high trapping capacity for cationic radio-elements, in particular because of the negative charge of clay surfaces. However, anionic radioelements like selenium species, would be only weakly retained by chemical processes. In order to optimize the trapping capacity of a clay barrier with respect to anionic species, prospective studies are carried out in order to find and evaluate some minerals with specific chemical trapping functions. Among radionuclides, the case of selenium has to be considered because its isotope {sup 79}Se is present in radioactive wastes and has a half life time of 6.5 10{sup 4} years. It is also judicious to find a mineral capable of trapping simultaneously several anionic radio-elements. Copper oxides and sulfides (Cu{sub 2}O, CuO, Cu{sub 2}S, CuS, CuFeS{sub 2} and Cu{sub 5}FeS{sub 4}) are good adsorbents with respect to selenium species (selenite and selenate). These minerals, with their selenium retention properties, could be used also for the decontamination of soils and waters or to process industrial effluents. The sorption mechanisms have been studied in details for copper oxides (Cu{sub 2}O and CuO) with respect to selenite and selenate. Chalcomenite precipitates in acid pH conditions when selenite is added to a Cu{sub 2}O and CuO suspension. Selenate, in contact with cuprite (Cu{sub 2}O) leads also to a selenium-based precipitate in acid pH environment. For higher pH values, selenite and selenate are adsorbed on copper oxides (Cu{sub 2}O and CuO) and lead to internal and external sphere complexes, respectively. In the case of a selenite/cuprite mixture in basic pH environment and at the equilibrium, a chemical reaction occurs between the oxidation product of cuprite, Cu

Behaviour of selenate in soils: experimental approach and modeling of hysteresis of sorption/desorption

International Nuclear Information System (INIS)

Loffredo, N.

2010-01-01

In the context of future storage of nuclear material in deep geological layers, the transfer of selenium-79 from groundwater to biosphere through irrigation is one of the scenarios considered by the ANDRA (National Agency for Radioactive Waste Management). So, the soil would act as an interface between the geosphere and biosphere. Actually the model adopted to evaluate the element mobility in soil is based on a simple representation of its distribution between the quantity adsorbed on the soil and the amount remaining in the solution (KD model). Such distribution is considered as instantaneous, reversible and linear with the concentration of contamination. This model has some inadequacies with respect to selenium because this latter can be present in different redox states that control its mobility and whose transformation kinetics among states are poorly known (Se(-II), Se(0), Se(IV) and Se(VI)). In order to improve predictions on the mobility of selenium in soil, selenate (Se(VI)) - which is the most mobile form - has been used to study its interactions with respect to two different soils (soil B and soil R). A kinetic model, alternative to the K d model, has been developed to describe the evolution of stocks of Se(VI) in solution. This model considers that a fraction of selenium is associated with soil in a reversibly way (potentially mobile) and a portion of it is stabilized in soil (pseudo-irreversibly fixed). This model integrates on one hand, in the soil, kinetics of biotic and abiotic stabilization and on the other hand, in solution, a reduction kinetic. With the goal of acquiring the parameters of the models, various experiments using dialysis bags have been effectuated, both in batch and with open-flow reactors. The parameter acquisition has allowed kinetic and K d models to be compared in different realistic scenarios of contamination (chronic or sequential) of a surface soil with 79 Se(VI). In addition, the sorption mechanisms of Se(VI) have been

Syntheses, characterizations and crystal structures of three new organically templated or organically bonded zinc selenates

International Nuclear Information System (INIS)

Feng Meiling; Mao Jianggao; Song Junling

2004-01-01

Three new organically templated or organically bonded zinc selenates, namely, {H 2 bipy}Zn(SeO 4 ) 2 (H 2 O) 2 1 (bipy=4,4'-bipyridine), {H 2 pip}{Zn(SeO 4 ) 2 (H 2 O) 4 }·2H 2 O 2 (pip=piprazine), and Zn(SeO 4 )(phen)(H 2 O) 2 3 (phen=1,10-phenanthroline) have been synthesized by hydrothermal reactions. The structure of compound 1 features a 1D chain composed of [Zn(SeO 4 ) 2 (H 2 O) 2 ] 2- anions. Compound 2 has a 2D layer structure built from {Zn(SeO 4 ) 2 (H 2 O) 4 } 2- anions that are cross-linked by doubly protonated piperazine cations via N-H···O hydrogen bonds. The structure of compound 3 contains a 1D chain of Zn(SeO 4 )(phen)(H 2 O) 2 , such chains are further interlinked by hydrogen bonds and π···π interactions to form a layer. The different roles the templates played have also been discussed

Pluto's atmosphere

International Nuclear Information System (INIS)

Elliot, J.L.; Dunham, E.W.; Bosh, A.S.; Slivan, S.M.; Young, L.A.

1989-01-01

Airborne CCD photometer observations of Pluto's June 9, 1988 stellar occultation have yielded an occultation lightcurve, probing two regions on the sunrise limb 2000 km apart, which reveals an upper atmosphere overlying an extinction layer with an abrupt upper boundary. The extinction layer may surround the entire planet. Attention is given to a model atmosphere whose occultation lightcurve closely duplicates observations; fits of the model to the immersion and emersion lightcurves exhibit no significant derived atmosphere-structure differences. Assuming a pure methane atmosphere, surface pressures of the order of 3 microbars are consistent with the occultation data. 43 references

Regional Atmospheric CO2 Inversion Reveals Seasonal and Geographic Differences in Amazon Net Biome Exchange

Science.gov (United States)

Alden, Caroline B.; Miller, John B.; Gatti, Luciana V.; Gloor, Manuel M.; Guan, Kaiyu; Michalak, Anna M.; van der Laan-Luijkx, Ingrid; Touma, Danielle; Andrews, Arlyn; Basso, Luana G.;

Upper atmospheric gravity wave details revealed in nightglow satellite imagery

Science.gov (United States)

Miller, Steven D.; Straka, William C.; Yue, Jia; Smith, Steven M.; Alexander, M. Joan; Hoffmann, Lars; Setvák, Martin; Partain, Philip T.

2015-01-01

Gravity waves (disturbances to the density structure of the atmosphere whose restoring forces are gravity and buoyancy) comprise the principal form of energy exchange between the lower and upper atmosphere. Wave breaking drives the mean upper atmospheric circulation, determining boundary conditions to stratospheric processes, which in turn influence tropospheric weather and climate patterns on various spatial and temporal scales. Despite their recognized importance, very little is known about upper-level gravity wave characteristics. The knowledge gap is mainly due to lack of global, high-resolution observations from currently available satellite observing systems. Consequently, representations of wave-related processes in global models are crude, highly parameterized, and poorly constrained, limiting the description of various processes influenced by them. Here we highlight, through a series of examples, the unanticipated ability of the Day/Night Band (DNB) on the NOAA/NASA Suomi National Polar-orbiting Partnership environmental satellite to resolve gravity structures near the mesopause via nightglow emissions at unprecedented subkilometric detail. On moonless nights, the Day/Night Band observations provide all-weather viewing of waves as they modulate the nightglow layer located near the mesopause (∼90 km above mean sea level). These waves are launched by a variety of physical mechanisms, ranging from orography to convection, intensifying fronts, and even seismic and volcanic events. Cross-referencing the Day/Night Band imagery with conventional thermal infrared imagery also available helps to discern nightglow structures and in some cases to attribute their sources. The capability stands to advance our basic understanding of a critical yet poorly constrained driver of the atmospheric circulation. PMID:26630004

Ocean to continent transfer of atmospheric Se as revealed by epiphytic lichens

International Nuclear Information System (INIS)

Wen Hanjie; Carignan, Jean

2009-01-01

There is still a long-term debate concerning the relative contributions of naturally emitted and anthropogenic Se at the regional and local scales. Here, Se and heavy metal concentrations are reported for epiphytic lichens collected in coastal and inland areas from the USA, Canada and France for assessing atmospheric Se source. Correlations found between Se and Cl in lichens confirmed the major marine biogenic source for atmospheric Se. Continental samples do not show systematic relationships between Se and other metal (Pb, Cu, In ...) contents, even for lichens collected in the vicinity of smelters or close to urban areas. Our results suggest that, although anthropogenic Se may be present, the marine biogenic Se source is a major contributor to atmospheric Se for our sampling locations. The contribution of naturally emitted atmospheric Se may be significant in urban and industrial areas and should be taken into account for further studies. - Although anthropogenic Se may be present, the contribution of naturally emitted atmospheric Se may be significant in urban and industrial areas and should be taken into account for further studies.

Local Lunar Gravity Field Analysis over the South Pole-aitken Basin from SELENE Farside Tracking Data

Science.gov (United States)

Goossens, Sander Johannes; Ishihara, Yoshiaki; Matsumoto, Koji; Sasaki, Sho

2012-01-01

We present a method with which we determined the local lunar gravity field model over the South Pole-Aitken (SPA) basin on the farside of the Moon by estimating adjustments to a global lunar gravity field model using SELENE tracking data. Our adjustments are expressed in localized functions concentrated over the SPA region in a spherical cap with a radius of 45deg centered at (191.1 deg E, 53.2 deg S), and the resolution is equivalent to a 150th degree and order spherical harmonics expansion. The new solution over SPA was used in several applications of geophysical analysis. It shows an increased correlation with high-resolution lunar topography in the frequency band l = 40-70, and admittance values are slightly different and more leveled when compared to other, global gravity field models using the same data. The adjustments expressed in free-air anomalies and differences in Bouguer anomalies between the local solution and the a priori global solution correlate with topographic surface features. The Moho structure beneath the SPA basin is slightly modified in our solution, most notably at the southern rim of the Apollo basin and around the Zeeman crater

Microgravimetric Studies of Selenium Electrodeposition Onto Different Substrates

Directory of Open Access Journals (Sweden)

Kowalik R.

2014-10-01

Full Text Available The mechanism of selenium electrodeposition from sulfuric acid solution on different substrates was studied with the electrochemical techniques. The cyclic voltammetry was combined with the quartz crystal microbalance technique to analyze selenium deposition process. The electrochemical reduction of selenous acid on gold, silver and copper electrodes was investigated. It was found that reduction of selenous acid is a very complex process and it strongly depends from the applied substrate. The voltammetric measurements indicate the range of potentials in which the process of reduction of selenous acids on the applied substrate is possible. Additionally, the microgravimetric data confirm the deposition of selenium and they reveal the mechanism of the deposition process.

Texture control and growth mechanism of WSe{sub 2} film prepared by rapid selenization of W film

Energy Technology Data Exchange (ETDEWEB)

Li, Hongchao [State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083 (China); Chongyi Zhangyuan Tungsten Industry Corporation Limited, Ganzhou 341300 (China); Gao, Di; Li, Kun; Pang, Mengde; Xie, Senlin [State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083 (China); Liu, Rutie, E-mail: llrrtt@csu.edu.cn [State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083 (China); Zou, Jianpeng [State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083 (China)

2017-02-01

Highlights: • We present a highly efficient method for preparing WSe{sub 2} film by rapid selenization. • The W film phase composition has little effect on WSe{sub 2} film orientation. • W film density is a critical factor that influences the WSe{sub 2} orientation. • A growth model was proposed for two kinds of WSe{sub 2} film textures. - Abstract: The tungsten diselenide (WSe{sub 2}) films with different orientation present unique properties suitable for specific applications, such as WSe{sub 2} with a C-axis⊥substrate for optoelectronics and WSe{sub 2} with a C-axis // substrate for electrocatalysts. Orientation control of WSe{sub 2} is essential for realizing the practical applications. In this letter, a WSe{sub 2} film has been prepared via rapid selenization of a magnetron-sputtered tungsten (W) film. The influence of the magnetron-sputtered W film on WSe{sub 2} film growth was studied systematically. Scanning electron microscopy, X-ray diffractometry and high-resolution transmission electron microscopy were used to evaluate the morphology, microstructure and phase composition of the W and WSe{sub 2} films. The substrate temperature has a significant effect on the W film phase composition, but little effect on the WSe{sub 2} film orientation. The WSe{sub 2} orientation can be controlled by changing the W film microstructure. A dense W film that is deposited at low pressure is conducive to the formation of WSe{sub 2} with a C-axis⊥substrate, whereas a porous W film deposited at high pressure favors the formation of WSe{sub 2} with a C-axis // substrate. A growth model for the WSe{sub 2} film with different texture has been proposed based on the experimental results. The direction of selenium (Se) vapor diffusion differs at the top and side surfaces. This is a key factor for the preparation of anisotropic WSe{sub 2} films. Highly oriented WSe{sub 2} films with a C-axis⊥substrate grow from the dense W film deposited at low pressure because Se vapor

Strength, stiffness, and microstructure of Cu(In,Ga)Se2 thin films deposited via sputtering and co-evaporation

International Nuclear Information System (INIS)

Luo, Shi; Jang, Dongchan; Greer, Julia R.; Lee, Jiun-Haw; Liu, Chee-Wee; Shieh, Jia-Min; Shen, Chang-Hong; Wu, Tsung-Ta

2014-01-01

This work examines Cu(In,Ga)Se 2 thin films fabricated by (1) selenization of pre-sputtered Cu-In-Ga and (2) co-evaporation of each constituent. The efficiency disparity between films deposited via these two methods is linked to differences in morphology and microstructure. Atomic force microscopy and scanning electron microscopy show that selenized films have rougher surfaces and poor adhesion to molybdenum back contact. Transmission electron microscopy and electron energy loss spectroscopy revealed multiple voids near the Mo layer in selenized films and a depletion of Na and Se around the voids. Residual stresses in co-evaporated films were found to be ∼1.23 GPa using wafer curvature measurements. Uniaxial compression experiments on 500 nm-diameter nanopillars carved out from co-evaporated films revealed the elastic modulus of 70.4 ± 6.5 GPa. Hertzian contact model applied to nanoindentation data on selenized films revealed the indentation modulus of 68.9 ± 12.4 GPa, which is in agreement with previous reports. This equivalence of the elastic moduli suggests that microstructural differences manifest themselves after the yield point. Typical plastic behavior with two distinct failure modes is observed in the extracted stress-strain results, with the yield strength of 640.9 ± 13.7 MPa for pillars that failed by shearing and 1100.8 ± 77.8 MPa for pillars that failed by shattering.

Strength, stiffness, and microstructure of Cu(In,Ga)Se{sub 2} thin films deposited via sputtering and co-evaporation

Energy Technology Data Exchange (ETDEWEB)

Luo, Shi; Jang, Dongchan; Greer, Julia R., E-mail: jrgreer@caltech.edu [Division of Applied Science and Engineering, California Institute of Technology, 1200 E California Blvd., Pasadena, California 91125 (United States); Lee, Jiun-Haw [Graduate Institute of Photonics and Optoelectronics and Department of Electrical Engineering, National Taiwan University, No. 1, Sec 4 Roosevelt, Taipei 10617, Taiwan (China); Liu, Chee-Wee [Department of Electrical Engineering, National Taiwan University, No 1, Sec 4 Roosevelt, Taipei 10617, Taiwan (China); Shieh, Jia-Min; Shen, Chang-Hong; Wu, Tsung-Ta [National Nano Device Laboratories, Hsinchu Science Park, No. 26, Prosperity Road I, Hsinchu 30078, Taiwan (China)

2014-07-07

This work examines Cu(In,Ga)Se{sub 2} thin films fabricated by (1) selenization of pre-sputtered Cu-In-Ga and (2) co-evaporation of each constituent. The efficiency disparity between films deposited via these two methods is linked to differences in morphology and microstructure. Atomic force microscopy and scanning electron microscopy show that selenized films have rougher surfaces and poor adhesion to molybdenum back contact. Transmission electron microscopy and electron energy loss spectroscopy revealed multiple voids near the Mo layer in selenized films and a depletion of Na and Se around the voids. Residual stresses in co-evaporated films were found to be ∼1.23 GPa using wafer curvature measurements. Uniaxial compression experiments on 500 nm-diameter nanopillars carved out from co-evaporated films revealed the elastic modulus of 70.4 ± 6.5 GPa. Hertzian contact model applied to nanoindentation data on selenized films revealed the indentation modulus of 68.9 ± 12.4 GPa, which is in agreement with previous reports. This equivalence of the elastic moduli suggests that microstructural differences manifest themselves after the yield point. Typical plastic behavior with two distinct failure modes is observed in the extracted stress-strain results, with the yield strength of 640.9 ± 13.7 MPa for pillars that failed by shearing and 1100.8 ± 77.8 MPa for pillars that failed by shattering.

Deletion of thioredoxin reductase and effects of selenite and selenate toxicity in Caenorhabditis elegans.

Directory of Open Access Journals (Sweden)

Christopher J Boehler

Full Text Available Thioredoxin reductase-1 (TRXR-1 is the sole selenoprotein in C. elegans, and selenite is a substrate for thioredoxin reductase, so TRXR-1 may play a role in metabolism of selenium (Se to toxic forms. To study the role of TRXR in Se toxicity, we cultured C. elegans with deletions of trxr-1, trxr-2, and both in axenic media with increasing concentrations of inorganic Se. Wild-type C. elegans cultured for 12 days in Se-deficient axenic media grow and reproduce equivalent to Se-supplemented media. Supplementation with 0-2 mM Se as selenite results in inverse, sigmoidal response curves with an LC50 of 0.20 mM Se, due to impaired growth rather than reproduction. Deletion of trxr-1, trxr-2 or both does not modulate growth or Se toxicity in C. elegans grown axenically, and (75Se labeling showed that TRXR-1 arises from the trxr-1 gene and not from bacterial genes. Se response curves for selenide (LC50 0.23 mM Se were identical to selenite, but selenate was 1/4(th as toxic (LC50 0.95 mM Se as selenite and not modulated by TRXR deletion. These nutritional and genetic studies in axenic media show that Se and TRXR are not essential for C. elegans, and that TRXR alone is not essential for metabolism of inorganic Se to toxic species.

Hazard assessment of inorganics to three endangered fish in the Green River, Utah

Science.gov (United States)

Hamilton, S.J.

1995-01-01

Acute toxicity tests were conducted with three life stages of Colorado squawfish (Ptychocheilus lucius), razorback sucker (Xyrauchen texanus), and bonytail (Gila elegans) in a reconstituted water quality simulating the middle part of the Green River of Utah. Tests were conducted with boron, lithium, selenate, selenite, uranium, vanadium, and zinc. The overall rank order of toxicity to all species and life stages combined from most to least toxic was vanadium = zinc > selenite > lithium = uranium > selenate > boron. There was no difference between the three species in their sensitivity to the seven inorganics based on a rank-order evaluation at the species level. Colorado squawfish were 2-5 times more sensitive to selenate and selenite at the swimup life stage than older stages, whereas razorback suckers displayed equal sensitivity among life stages. Bonytail exhibited equal sensitivity to selenite, but were five times more sensitive to selenate at the swimup life stage than the older stages. Comparison of 96-hr LC50 values with a limited number of environmental water concentrations in Ashley Creek, Utah, which receives irrigation drainwater, revealed moderate hazard ratios for boron, selenate, selenite, and zinc, low hazard ratios for uranium and vanadium, but unknown ratios for lithium. These inorganic contaminants in drainwaters may adversely affect endangered fish in the Green River.

Drought sensitivity of Amazonian carbon balance revealed by atmospheric measurements

Science.gov (United States)

Gatti, L. V.; Gloor, M.; Miller, J. B.; Doughty, C. E.; Malhi, Y.; Domingues, L. G.; Basso, L. S.; Martinewski, A.; Correia, C. S. C.; Borges, V. F.; Freitas, S.; Braz, R.; Anderson, L. O.; Rocha, H.; Grace, J.; Phillips, O. L.; Lloyd, J.

2014-02-01

Feedbacks between land carbon pools and climate provide one of the largest sources of uncertainty in our predictions of global climate. Estimates of the sensitivity of the terrestrial carbon budget to climate anomalies in the tropics and the identification of the mechanisms responsible for feedback effects remain uncertain. The Amazon basin stores a vast amount of carbon, and has experienced increasingly higher temperatures and more frequent floods and droughts over the past two decades. Here we report seasonal and annual carbon balances across the Amazon basin, based on carbon dioxide and carbon monoxide measurements for the anomalously dry and wet years 2010 and 2011, respectively. We find that the Amazon basin lost 0.48+/-0.18 petagrams of carbon per year (PgCyr-1) during the dry year but was carbon neutral (0.06+/-0.1PgCyr-1) during the wet year. Taking into account carbon losses from fire by using carbon monoxide measurements, we derived the basin net biome exchange (that is, the carbon flux between the non-burned forest and the atmosphere) revealing that during the dry year, vegetation was carbon neutral. During the wet year, vegetation was a net carbon sink of 0.25+/-0.14PgCyr-1, which is roughly consistent with the mean long-term intact-forest biomass sink of 0.39+/-0.10PgCyr-1 previously estimated from forest censuses. Observations from Amazonian forest plots suggest the suppression of photosynthesis during drought as the primary cause for the 2010 sink neutralization. Overall, our results suggest that moisture has an important role in determining the Amazonian carbon balance. If the recent trend of increasing precipitation extremes persists, the Amazon may become an increasing carbon source as a result of both emissions from fires and the suppression of net biome exchange by drought.

Comparing the influence of selenite (Se4+) and selenate (Se6+) on the inhibition of the mercury (Hg) phytotoxicity to pak choi.

Science.gov (United States)

Tran, Thi Anh Thu; Dinh, Quang Toan; Cui, Zeiwei; Huang, Jie; Wang, Dan; Wei, Tianjiao; Liang, Dongli; Sun, Xin; Ning, Ping

2018-01-01

Selenite (Se (IV)) and selenate (Se (IV)) have recently been demonstrated to be equally effective in inhibiting mercury (Hg) phytotoxicity to plants. This assertion is still unclear. In this study, we aimed to explore the potential effects of Se species (Se 4+ and Se 6+ ) on the inhibition of the mercury (Hg) bioavailability to pak choi in dry land. Pot experiments with exposure to different dosages of mercuric chloride (HgCl 2 ) and selenite (Na 2 SeO 3 ) or selenate (Na 2 SeO 4 ) were treated. To compare the influence of Se (IV) and Se (VI) on the bioaccumulation and bioavailability of Hg, the levels of total Hg in different pak choi (Brassica chinensis L.) tissues (roots and shoots) and the distribution changes of Hg fractions in soil before planting and after harvest were determined as well as the Hg I R values in soils (relative binding intensity) were analyzed. Results showed that application Se (IV) reduced the concentrations of Hg in pak choi roots more than Se (VI). Hg concentrations were also decreased in pak choi shoots in Se (IV) treatments, while which notably increased in Se (VI) treatments. Thus, Se (IV) plays a more important role than Se (VI) in limiting the absorption and bioaccumulation of Hg in pak choi. Moreover, this inhibition may only significantly occur when Se (IV) is at an appropriate level (2.5mg/kg). In addition, the good correlations between the proportions of mobile Hg fractions (soluble and exchangeable fractions), I R values with the Hg concentrations in plants were observed. This affirmed the importance of the Hg fractions transformation and the I R indicator of Hg in the assessment of their bioavailability. Our findings regarding the importance of Se (IV) influence in reducing Hg bioaccumulation not only provided the correct appraisal about the effect of Se species on the inhibition of the Hg phytotoxicity to pak choi in dry land, but also be a good reference for selecting Se fertilizer forms (Se 4+ or Se 6+ ). Copyright © 2017

Highly efficient CuIn{sub 1-x}Ga{sub x}Se{sub 2-y}S{sub y}/CdS thin-film solar cells by using diethylselenide as selenium precursor

Energy Technology Data Exchange (ETDEWEB)

Kadam, Ankur A.; Dhere, Neelkanth G. [Florida Solar Energy Center, University of Central Florida, Cocoa, FL 32922-5703 (United States)

2010-05-15

Conventional furnace selenization process was optimized to achieve effective selenization using diethylselenide (C{sub 2}H{sub 5}){sub 2}Se (DESe). An optimized quantity of Na was added to improve V{sub oc}, FF and morphology. Sputter-deposited CuGa and In metallic precursors were homogenized in an inert atmosphere prior to the introduction of DESe followed by rapidly heating to the maximum process temperature to avoid formation of detrimental binary phases. Selenization was carried out in the temperature range 475-515 C followed by sulfurization in dilute H{sub 2}S. Solar cells were completed by depositing CdS heterojunction partner layer, i:ZnO/ZnO:Al window-bilayer and metallic contact fingers. PV conversion efficiency of 13.7% with a V{sub oc} of 540 mV, J{sub sc} of 38.3 mA/cm{sup 2} and FF of 66.3% were obtained on 0.442 cm{sup 2} cell areas. The process can be easily scaled-up for economic large-scale manufacture. (author)

Puerto Rico Revealed Preference Survey Data 2004

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Revealed preference models provide insights into recreational angler behavior and the economic value of recreational fishing trips. Revealed preference data is...

Establishing atmospheric neutrino oscillations with Super-Kamiokande

International Nuclear Information System (INIS)

Kajita, T.; Kearns, E.; Shiozawa, M.

2016-01-01

In this article we review the discovery of atmospheric neutrino oscillation by the Super-Kamiokande experiment. This review outlines the sequence of observations and their associated publications that solved the atmospheric neutrino anomaly and established the existence of neutrino oscillations with nearly maximal mixing of muon neutrinos and tau neutrinos. We also discuss subsequent and ongoing studies that use atmospheric neutrinos to continue to reveal the nature of the neutrino.

Coupled Effect of Ferrous Ion and Oxygen on the Electron Selectivity of Zerovalent Iron for Selenate Sequestration.

Science.gov (United States)

Qin, Hejie; Li, Jinxiang; Yang, Hongyi; Pan, Bingcai; Zhang, Weiming; Guan, Xiaohong

2017-05-02

Although the electron selectivity (ES) of zerovalent iron (ZVI) for target contaminant and its utilization ratio (UR) decide the removal capacity of ZVI, little effort has been made to improve them. Taking selenate [Se(VI)] as a target contaminant, this study investigated the coupled influence of aeration gas and Fe(II) on the ES and UR of ZVI. Oxygen was necessary for effective removal of Se(VI) by ZVI without Fe(II) addition. Due to the application of 1.0 mM Fe(II), the ES of ZVI was increased from 3.2-3.6% to 6.2-6.8% and the UR of ZVI was improved by 5.0-19.4% under aerobic conditions, which resulted in a 100-180% increase in the Se(VI) removal capacity by ZVI. Se(VI) reduction by Fe 0 was a heterogeneous redox reaction, and the enrichment of Se(VI) on ZVI surface was the first step of electron transfer from Fe 0 core to Se(VI). Oxygen promoted the generation of iron (hydr)oxides, which facilitated the enrichment of Se(VI) on the ZVI particle surface. Therefore, the high oxygen fraction (25-50%) in the purging gas resulted in only a slight decrease in the ES of ZVI. Fe(II) addition resulted in a pH drop and promoted the generation of lepidocrocite and magnetite, which benefited Se(VI) adsorption and the following electron transfer from underlying Fe 0 to surface-located Se(VI).

Cu2ZnSnSe4 Thin Film Solar Cell with Depth Gradient Composition Prepared by Selenization of Sputtered Novel Precursors.

Science.gov (United States)

Lai, Fang-I; Yang, Jui-Fu; Chen, Wei-Chun; Kuo, Shou-Yi

2017-11-22

In this study, we proposed a new method for the synthesis of the target material used in a two stage process for preparation of a high quality CZTSe thin film. The target material consisting of a mixture of Cu x Se and Zn x Sn 1-x alloy was synthesized, providing a quality CZTSe precursor layer for highly efficient CZTSe thin film solar cells. The CZTSe thin film can be obtained by annealing the precursor layers through a 30 min selenization process under a selenium atmosphere at 550 °C. The CZTSe thin films prepared by using the new precursor thin film were investigated and characterized using X-ray diffraction, Raman scattering, and photoluminescence spectroscopy. It was found that diffusion of Sn occurred and formed the CTSe phase and Cu x Se phase in the resultant CZTSe thin film. By selective area electron diffraction transmission electron microscopy images, the crystallinity of the CZTSe thin film was verified to be single crystal. By secondary ion mass spectroscopy measurements, it was confirmed that a double-gradient band gap profile across the CZTSe absorber layer was successfully achieved. The CZTSe solar cell with the CZTSe absorber layer consisting of the precursor stack exhibited a high efficiency of 5.46%, high short circuit current (J SC ) of 37.47 mA/cm 2 , open circuit voltage (V OC ) of 0.31 V, and fill factor (F.F.) of 47%, at a device area of 0.28 cm 2 . No crossover of the light and dark current-voltage (I-V) curves of the CZTSe solar cell was observed, and also, no red kink was observed under red light illumination, indicating a low defect concentration in the CZTSe absorber layer. Shunt leakage current with a characteristic metal/CZTSe/metal leakage current model was observed by temperature-dependent I-V curves, which led to the discovery of metal incursion through the CdS buffer layer on the CZTSe absorber layer. This leakage current, also known as space charge-limited current, grew larger as the measurement temperature increased and

大气水汽同位素组成的短期变异特征%Short-term variations of vapor isotope ratios reveal the influence of atmospheric processes

Institute of Scientific and Technical Information of China (English)

张世春; 孙晓敏; 王建林; 于贵瑞; 温学发

2011-01-01

Stable isotopes of atmospheric water vapor reveal rich information on water movement and phase changes in the atmosphere. Here we presented two nearly continuous time-series of δD and δ18O of atmospheric water vapor (δv) measured at hourly intervals in surface air in Beijing and above a winter wheat canopy in Shijiazhuang using in-situ measurement technique. During the precipitation events, the δv values in both Beijing and Shijiazhuang were in the state of equilibrium with precipitation water, revealing the influence of precipitation processes. However, the δv departures from the equilibrium state were positively correlated with local relative humidity. Note that the δv tended to enrich in Beijing, but deplete in Shijiazhuang during the precipitation events, which mainly resulted from the influence of transpiration processes that enriched the δv in Shijiazhuang. On seasonal time-scale, the δvvalues were log-linear functions of water vapor mixing ratios in both Beijing and Shijiazhuang. The water vapor mixing ratio was an excellent predictor of the δv by the Rayleigh distillation mechanisms, indicating that air mass advection could also play an important role in determining the δv. On a diurnal time-scale, the δv reached the minimum in the early afternoon hours in Beijing which was closely related to the atmospheric processes of boundary layer entrainment. During the peak of growing season of winter wheat, however, the δv reached the minimum in the early morning, and increased gradually through the daytime, and reached the maximum in the late afternoon, which was responsible by the interaction between boundary layer entrainment and the local atmospheric processes, such as transpiration and dew formation. This study has the implications for the important role of vegetation in determining the surface δv and highlights the need to conduct δv measurement on short-term (e.g. diurnal) time scales.

Preparation of CulnSe2 thin films by paste coating

Institute of Scientific and Technical Information of China (English)

无

2008-01-01

Precursor pastes were obtained by milling Cu-In alloys and Se powders.CuInSe2 thin films were successfully prepared by precursor layers,which were coated using these pastes,and were annealed in a H2 atmosphere.The pastes were tested by laser particle diameter analyzer,simultaneous thermogravimetric and differential thermal analysis instruments (TG-DTA),and X-ray diffractometry (XRD).Selenized films were characterized by XRD,scanning electron microscopy (SEM),and energy dispersive spectroscopy (EDS).The results indicate that chalcopyrite CuInSe2 is formed at 180℃ and the crystallinity of this phase is improved as the temperature rises.All the CuInSe2 thin films,which were annealed at various temperatures,exhibit the preferred orientation along the (112) plane.The compression of precursor layers before selenization step is one oftbe most essential factors for the preparation of perfect CulnSe2 thin films.

Photochemistry of Planetary Atmospheres

Science.gov (United States)

Yung, Y. L.

2005-12-01

The Space Age started half a century ago. Today, with the completion of a fairly detailed study of the planets of the Solar System, we have begun studying exoplanets (or extrasolar planets). The overriding question in is to ask whether an exoplanet is habitable and harbors life, and if so, what the biosignatures ought to be. This forces us to confront the fundamental question of what controls the composition of an atmosphere. The composition of a planetary atmosphere reflects a balance between thermodynamic equilibrium chemistry (as in the interior of giant planets) and photochemistry (as in the atmosphere of Mars). The terrestrial atmosphere has additional influence from life (biochemistry). The bulk of photochemistry in planetary atmospheres is driven by UV radiation. Photosynthesis may be considered an extension of photochemistry by inventing a molecule (chlorophyll) that can harvest visible light. Perhaps the most remarkable feature of photochemistry is catalytic chemistry, the ability of trace amounts of gases to profoundly affect the composition of the atmosphere. Notable examples include HOx (H, OH and HO2) chemistry on Mars and chlorine chemistry on Earth and Venus. Another remarkable feature of photochemistry is organic synthesis in the outer solar system. The best example is the atmosphere of Titan. Photolysis of methane results in the synthesis of more complex hydrocarbons. The hydrocarbon chemistry inevitably leads to the formation of high molecular weight products, giving rise to aerosols when the ambient atmosphere is cool enough for them to condense. These results are supported by the findings of the recent Cassini mission. Lastly, photochemistry leaves a distinctive isotopic signature that can be used to trace back the evolutionary history of the atmosphere. Examples include nitrogen isotopes on Mars and sulfur isotopes on Earth. Returning to the question of biosignatures on an exoplanet, our Solar System experience tells us to look for speciation

Illusion and reality in the atmospheres of exoplanets

Science.gov (United States)

Deming, L. Drake; Seager, Sara

2017-01-01

The atmospheres of exoplanets reveal all their properties beyond mass, radius, and orbit. Based on bulk densities, we know that exoplanets larger than 1.5 Earth radii must have gaseous envelopes and, hence, atmospheres. We discuss contemporary techniques for characterization of exoplanetary atmospheres. The measurements are difficult, because—even in current favorable cases—the signals can be as small as 0.001% of the host star's flux. Consequently, some early results have been illusory and not confirmed by subsequent investigations. Prominent illusions to date include polarized scattered light, temperature inversions, and the existence of carbon planets. The field moves from the first tentative and often incorrect conclusions, converging to the reality of exoplanetary atmospheres. That reality is revealed using transits for close-in exoplanets and direct imaging for young or massive exoplanets in distant orbits. Several atomic and molecular constituents have now been robustly detected in exoplanets as small as Neptune. In our current observations, the effects of clouds and haze appear ubiquitous. Topics at the current frontier include the measurement of heavy element abundances in giant planets, detection of carbon-based molecules, measurement of atmospheric temperature profiles, definition of heat circulation efficiencies for tidally locked planets, and the push to detect and characterize the atmospheres of super-Earths. Future observatories for this quest include the James Webb Space Telescope and the new generation of extremely large telescopes on the ground. On a more distant horizon, NASA's study concepts for the Habitable Exoplanet Imaging Mission (HabEx) and the Large UV/Optical/Infrared Surveyor (LUVOIR) missions could extend the study of exoplanetary atmospheres to true twins of Earth.

Assessment of the anticancer compounds Se-methylselenocysteine and glucosinolates in Se-biofortified broccoli (Brassica oleracea L. var. italica) sprouts and florets.

Science.gov (United States)

Ávila, Fabricio William; Faquin, Valdemar; Yang, Yong; Ramos, Silvio Junio; Guilherme, Luiz Roberto G; Thannhauser, Theodore W; Li, Li

2013-07-03

Broccoli (Brassica oleracea L. var. italica) is a rich source of chemopreventive compounds. Here, we evaluated and compared the effect of selenium (Se) treatment on the accumulation of anticancer compounds Se-methylselenocysteine (SeMSCys) and glucosinolates in broccoli sprouts and florets. Total Se and SeMSCys content in sprouts increased concomitantly with increasing Se doses. Selenate was superior to selenite in inducing total Se accumulation, but selenite is equally effective as selenate in promoting SeMSCys synthesis in sprouts. Increasing sulfur doses reduced total Se and SeMSCys content in sprouts treated with selenate, but not in those with selenite. Examination of five broccoli cultivars reveals that sprouts generally have better fractional ability than florets to convert inorganic Se into SeMSCys. Distinctive glucosinolate profiles between sprouts and florets were observed, and sprouts contained approximately 6-fold more glucoraphanin than florets. In contrast to florets, glucosinolate content was not affected by Se treatment in sprouts. Thus, Se-enriched broccoli sprouts are excellent for simultaneous accumulation of chemopreventive compounds SeMSCys and glucoraphanin.

Some aspects of composition of the lower Martian atmosphere: input for MIRA

Science.gov (United States)

Moroz, V.; Korablev, O.; Krasnopolsky, V.; Rorin, A.

Recent spacecraft missions and high-resolution spectroscopic observations from the Earth-based, airborne and spaceborne observatories have justified the chemical contents of the Martian atmosphere at a new level of confidence. Both the lower and middle atmosphere of Mars reveal very limited chemical activity, while the variations of the abundance of minor constituents may be attributed to phase transitions of volatiles. Water vapor, which mixing ratio is controlled by complex hydrological cycle in the lower atmosphere and at the surface of the planet, affects seasonally varying depletion of ozone. Measured ratio of D/H can be explained with general models of the early evolution of the planet, though this estimate in the bulk atmosphere may not be ultimately representative due to altitude dependant fractionation of water isotopes. CO, as a chemically passive nonvolatile component, reveals increase of mixing ratio in the vicinity of winter polar caps during active condensation of the bulk CO2 atmosphere. No reliable evidence o any organicf matter in the atmosphere of Mars has been obtained.

Selenium Accumulation Characteristics and Biofortification Potentiality in Turnip (Brassica rapa var. rapa Supplied with Selenite or Selenate

Directory of Open Access Journals (Sweden)

Xiong Li

2018-01-01

Full Text Available Selenium (Se is an essential trace element for humans. About 70% of the regions in China, including most of the Tibetan Plateau, are faced with Se deficiency problems. Turnip is mainly distributed around the Tibetan Plateau and is one of the few local crops. In the present study, we compared the absorption and translocation differences of Se (IV selenite and Se (VI selenate in turnip. The results showed that Se treatment, either by soil addition (0.2–2 mg Se kg−1 dry soil or by foliar spraying (50–200 mg L−1 Se, could significantly increase the Se concentrations in turnips, and 0.5 mg Se (IV or Se (VI kg−1 dry matter in soils could improve the biomasses of turnips. Moreover, turnip absorbed significantly more Se (VI than Se (IV at the same concentration and also transferred much more Se (VI from roots to leaves. Based on the Se concentrations, as well as the bioconcentration factors and translocation coefficients, we considered that turnip might be a potential Se indicator plant. Subsequently, we estimated the daily Se intake for adults based on the Se concentrations in turnip roots. The results indicated that Se (IV should be more suitable as an artificial Se fertilizer for turnips, although the levels found in most samples in this study could cause selenosis to humans. In addition, we also estimated the optimum and maximum Se concentrations for treating turnips based on the linear relations between Se concentrations in turnip roots and Se treatment concentrations. The results provided preliminary and useful information about Se biofortification in turnips.

Pluto's surface composition and atmosphere

Science.gov (United States)

Young, L. A.; Gladstone, R.; Summers, M. E.; Strobel, D. F.; Kammer, J.; Hinson, D. P.; Grundy, W. M.; Cruikshank, D. P.; Protopapa, S.; Schmitt, B.; Stern, A.; Weaver, H. A., Jr.; Olkin, C.; Ennico Smith, K.

2017-12-01

New Horizons studied Pluto's N2-dominated neutral atmosphere through radio (at 4.2 cm with the REX radio experiment), solar and stellar occultations and airglow (at 52-187 nm with the Alice ultraviolet spectrograph), and imaging (with the LORRI and MVIC visible-wavelength cameras). It studied the plasma environment and solar wind interaction with in situ instruments (PEPPSI and SWAP). Contemporaneous observations of Pluto's atmosphere from Earth included a ground-based stellar occultation and ALMA observations of gaseous CO and HCN. Joint analysis of these datasets reveal a variable boundary layer; a stable lower atmosphere; radiative heating and cooling; haze production and hydrocarbon chemistry; diffusive equilibrium; and slower-than-expected escape. New Horizons studied Pluto's surface composition with the LEISA near-infrared spectral imager from 1.25 to 2.5 micron. Additional compositional information at higher spatial resolution came from the MVIC 4-channel color imager, which included a channel centered at 0.89 micron specifically designed to detect solid CH4. These instruments allow mapping of the volatiles N2, CO, and CH4, the surface expression of the H2O bedrock, and the dark, reddish material presumed to be tholins. These observations reveal a large equatorial basin (informally named Sptunik Planitia), filled with N2 ice with minor amounts of CO and CH4, surrounded by hills of CH4 and H2O ice. Broadly speaking, composition outside of Sptunik Planitia follows latitudinal banding, with dark, mainly volatile free terrains near the equator, with N2, CO, and CH4 at mid-northern latitudes, and mainly CH4 at high northern latitudes. Deviations from these broad trends are seen, and point to complex surface-atmosphere interactions at diurnal, seasonal, perennial, and million-year timescales.

Exoplanetary Atmospheres-Chemistry, Formation Conditions, and Habitability.

Science.gov (United States)

Madhusudhan, Nikku; Agúndez, Marcelino; Moses, Julianne I; Hu, Yongyun

2016-12-01

Characterizing the atmospheres of extrasolar planets is the new frontier in exoplanetary science. The last two decades of exoplanet discoveries have revealed that exoplanets are very common and extremely diverse in their orbital and bulk properties. We now enter a new era as we begin to investigate the chemical diversity of exoplanets, their atmospheric and interior processes, and their formation conditions. Recent developments in the field have led to unprecedented advancements in our understanding of atmospheric chemistry of exoplanets and the implications for their formation conditions. We review these developments in the present work. We review in detail the theory of atmospheric chemistry in all classes of exoplanets discovered to date, from highly irradiated gas giants, ice giants, and super-Earths, to directly imaged giant planets at large orbital separations. We then review the observational detections of chemical species in exoplanetary atmospheres of these various types using different methods, including transit spectroscopy, Doppler spectroscopy, and direct imaging. In addition to chemical detections, we discuss the advances in determining chemical abundances in these atmospheres and how such abundances are being used to constrain exoplanetary formation conditions and migration mechanisms. Finally, we review recent theoretical work on the atmospheres of habitable exoplanets, followed by a discussion of future outlook of the field.

Atmospheric signals produced by cavity rebound

International Nuclear Information System (INIS)

Jones, E.M.; App, F.N.; Whitaker, R.W.

1993-01-01

An analysis of the atmospheric acoustic signals produced by a class of low-yield tests conducted just below the base of the alluvial cover in Yucca Flat of the Nevada Test Site (NTS), has revealed a clear manifestation of an elastic, cavity rebound signal. We use modeling as the basis for understanding the observed phenomena

SELENE

Indian Academy of Sciences (India)

Institute of Space and Astronautical Science, Japan Aerospace Exploration ... launch target is rescheduled for 2006 due to delay of completion of launch vehicle, H-IIA. ... Mapping of subsurface structure using active sounding, frequency 5MHz,.

Influence of Se concentrations and species in hydroponic cultures on Se uptake, translocation and assimilation in non-accumulator ryegrass.

Science.gov (United States)

Versini, Antoine; Di Tullo, Pamela; Aubry, Emmanuel; Bueno, Maïté; Thiry, Yves; Pannier, Florence; Castrec-Rouelle, Maryse

2016-11-01

The success of biofortification and phytoremediation practices, addressing Se deficiency and Se pollution issues, hinges crucially on the fate of selenium in the plant media in response to uptake, translocation and assimilation processes. We investigate the fate of selenium in root and shoot compartments after 3 and 6 weeks of experiment using a total of 128 plants grown in hydroponic solution supplied with 0.2, 2, 5, 20 and 100 mg L -1 of selenium in the form of selenite, selenate and a mixture of both species. Selenate-treated plants exhibited higher root-to-shoot Se translocation and total Se uptake than selenite-treated plants. Plants took advantage of the selenate mobility and presumably of the storage capacity of leaf vacuoles to circumvent selenium toxicity within the plant. Surprisingly, 28% of selenate was found in shoots of selenite-treated plants, questioning the ability of plants to oxidize selenite into selenate. Selenomethionine and methylated organo-selenium amounted to 30% and 8% respectively in shoots and 35% and 9% in roots of the identified Se, suggesting that selenium metabolization occurred concomitantly in root and shoot plant compartments and demonstrating that non-accumulator plants can synthesize notable quantities of precursor compound for volatilization. The present study demonstrated that non-accumulator plants can develop the same strategies as hyper-accumulator plants to limit selenium toxicity. When both selenate and selenite were supplied together, plants used selenate in a storage pathway and selenite in an assimilation pathway. Plants might thereby benefit from mixed supplies of selenite and selenate by saving enzymes and energy required for selenate reduction. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Oxidation Products of Biogenic Emissions Contribute to Nucleation of Atmospheric Particles

CERN Document Server

Riccobono, Francesco; Baltensperger, Urs; Worsnop, Douglas R; Curtius, Joachim; Carslaw, Kenneth S; Wimmer, Daniela; Wex, Heike; Weingartner, Ernest; Wagner, Paul E; Vrtala, Aron; Viisanen, Yrjö; Vaattovaara, Petri; Tsagkogeorgas, Georgios; Tomé, Antonio; Stratmann, Frank; Stozhkov, Yuri; Spracklen, Dominick V; Sipilä, Mikko; Praplan, Arnaud P; Petäjä, Tuukka; Onnela, Antti; Nieminen, Tuomo; Mathot, Serge; Makhmutov, Vladimir; Lehtipalo, Katrianne; Laaksonen, Ari; Kvashin, Alexander N.; Kürten, Andreas; Kupc, Agnieszka; Keskinen, Helmi; Kajos, Maija; Junninen, Heikki; Hansel, Armin; Franchin, Alessandro; Flagan, Richard C; Ehrhart, Sebastian; Duplissy, Jonathan; Dunne, Eimear M; Downard, Andrew; David, André; Breitenlechner, Martin; Bianchi, Federico; Amorim, Antonio; Almeida, João; Rondo, Linda; Ortega, Ismael K; Dommen, Josef; Scott, Catherine E; Vrtala, Aron; Santos, Filipe D; Schallhart, Simon; Seinfeld, John H; Sipila, Mikko; Donahue, Neil M; Kirkby, Jasper; Kulmala, Markku

2014-01-01

Atmospheric new-particle formation affects climate and is one of the least understood atmospheric aerosol processes. The complexity and variability of the atmosphere has hindered elucidation of the fundamental mechanism of new-particle formation from gaseous precursors. We show, in experiments performed with the CLOUD (Cosmics Leaving Outdoor Droplets) chamber at CERN, that sulfuric acid and oxidized organic vapors at atmospheric concentrations reproduce particle nucleation rates observed in the lower atmosphere. The experiments reveal a nucleation mechanism involving the formation of clusters containing sulfuric acid and oxidized organic molecules from the very first step. Inclusion of this mechanism in a global aerosol model yields a photochemically and biologically driven seasonal cycle of particle concentrations in the continental boundary layer, in good agreement with observations.

Characterising exoplanet atmospheres as part of the LRG-BEASTS survey

Science.gov (United States)

Kirk, James; Wheatley, Peter; LRG-BEASTS Collaboration

2018-01-01

I will present the latest results from the Low Resolution Ground-Based Exoplanet Atmosphere Survey using Transmission Spectroscopy (LRG-BEASTS, ‘large beasts’). This programme has demonstrated the capabilities of 4-metre class telescopes to produce transmission spectra with precision comparable to HST and 8- and 10-metre class telescopes. LRG-BEASTS has so far revealed a Rayleigh scattering haze in the atmosphere of HAT-P-18b, clouds in the atmosphere of WASP-52b, and ruled out a previously claimed detection of potassium in the atmosphere of WASP-80b. Studies of hot Jupiter atmospheres have revealed a startling diversity between systems, with many showing thick clouds and hazes which mask pressure-broadened absorption features. In the small sample of studied planets to date, no strong correlation has emerged between key planetary parameters and the presence, or absence, of clouds and hazes, although there has been a suggestion that temperature might play a role. In order to characterise this diversity and unravel the underlying physical processes, it is essential that we expand the current sample of studied planets. This is the focus of LRG-BEASTS and my dissertation. Clouds and hazes are not just prominent in giant planet atmospheres but also in the handful of smaller planets characterised in transmission. The knowledge and expertise we will gain from the study of giant planets with surveys such as LRG-BEASTS will inform our understanding of analogous processes in the exciting new generation of planets that will be discovered with TESS.

On the Atmospheric Correction of Antarctic Airborne Hyperspectral Data

Directory of Open Access Journals (Sweden)

Martin Black

2014-05-01

Full Text Available The first airborne hyperspectral campaign in the Antarctic Peninsula region was carried out by the British Antarctic Survey and partners in February 2011. This paper presents an insight into the applicability of currently available radiative transfer modelling and atmospheric correction techniques for processing airborne hyperspectral data in this unique coastal Antarctic environment. Results from the Atmospheric and Topographic Correction version 4 (ATCOR-4 package reveal absolute reflectance values somewhat in line with laboratory measured spectra, with Root Mean Square Error (RMSE values of 5% in the visible near infrared (0.4–1 µm and 8% in the shortwave infrared (1–2.5 µm. Residual noise remains present due to the absorption by atmospheric gases and aerosols, but certain parts of the spectrum match laboratory measured features very well. This study demonstrates that commercially available packages for carrying out atmospheric correction are capable of correcting airborne hyperspectral data in the challenging environment present in Antarctica. However, it is anticipated that future results from atmospheric correction could be improved by measuring in situ atmospheric data to generate atmospheric profiles and aerosol models, or with the use of multiple ground targets for calibration and validation.

Effects in atmospheric electricity daily variation controlled by solar wind

International Nuclear Information System (INIS)

Ptitsyna, N.G.; Tyasto, M.I.; Levitin, A.E.; Gromova, L.A.; Tuomi, T.; AN SSSR, Moscow

1995-01-01

An analysis of fair weather atmospheric electricity, one of the environmental factors which affects the biosphere, is conducted. A distinct difference in the diurnal variation of atmospheric electric field at Helsinki is found between disturbed and extremely quiet conditions in the magnetosphere in winter before midnight. The comparison with the numerical model of the ionospheric electric field based on the solar wind parameters reveals that the maximum contribution of the magnetospheric-ionospheric generator to atmospheric electric field is about 100-150 v/m which assumes values of about 30% of the surface field. 8 refs.; 2 figs

The First Atmospheric Characterization of a Habitable-Zone Exoplanet

Science.gov (United States)

Stevenson, Kevin; Bean, Jacob; Charbonneau, David; Desert, Jean-Michel; Fortney, Jonathan; Irwin, Jonathan; Kreidberg, Laura; Line, Michael; Montet, Ben; Morley, Caroline

2015-10-01

Exoplanet surveys have recently revealed nearby planets orbiting within stellar habitable zones. This highly-anticipated breakthrough brings us one step closer in our quest to identify cosmic biosignatures, the indicators of extrasolar life. To achieve our goal, we must first study the atmospheres of these temperate worlds to measure their compositions and determine the prevalence of obscuring clouds. Using observations from the K2 mission, Co-I Montet recently announced the discovery of a 2.2 Earth-radii planet within the habitable zone of its relatively bright, nearby M dwarf parent star, K2-18. This temperate world is currently the best habitable-zone target for atmospheric characterization. Congruent with currently planned HST observations, we propose a Spitzer program to measure the transmission spectrum of the first habitable-zone exoplanet. Both telescopes are essential to revealing K2-18b's chemical composition. In a cloud-free, hydrogen-dominated atmosphere, the precision achieved by these measurements will be sufficient to detect methane, ammonia, and water vapor, which are the dominant C, N, and O bearing species at these temperatures. In turn, elemental abundance constraints from a primordial atmosphere can tell us about the composition of a protoplanetary disk in which Earth-like planets could have formed. Conversely, if the atmosphere contains thick clouds then the multi-wavelength observations from K2, HST, and Spitzer will constrain the clouds' properties. Because temperature plays a key role in the formation of clouds, their detection within the atmosphere of this habitable-zone exoplanet would be an important signpost that serves as a guide to future investigations of smaller, rocky exoplanets. As K2 continues discovering more habitable-zone planets, it is imperative that we perform spectral reconnaissance with Spitzer to determine their physical characteristics and begin understanding the prevalence of potentially-obscuring clouds prior to the

Influence of tropical atmospheric variability on Weddell Sea deep water convection

Science.gov (United States)

Kleppin, H.

2016-02-01

Climate reconstructions from ice core records in Greenland and Antarctica have revealed a series of abrupt climate transitions, showing a distinct relationship between northern and southern hemisphere climate during the last glacial period. The recent ice core records from West Antarctica (WAIS) point towards an atmospheric teleconnection as a possible trigger for the interhemispheric climate variability (Markle et al., 2015). An unforced simulation of the Community Climate System Model, version 4 (CCSM4) reveals Greenland warming and cooling events, caused by stochastic atmospheric forcing, that resemble Dansgaard-Oeschger cycles in pattern and magnitude (Kleppin et al., 2015). Anti-phased temperature changes in the Southern Hemisphere are small in magnitude and have a spatially varying pattern. We argue that both north and south high latitude climate variability is triggered by changes in tropical atmospheric deep convection in the western tropical Pacific. The atmospheric wave guide provides a fast communication pathway connecting the deep tropics and the polar regions. In the Southern Hemisphere this is manifested as a distinct pressure pattern over West Antarctica. These altered atmospheric surface conditions over the convective region can lead to destabilization of the water column and thus to convective overturning in the Weddell Sea. However, opposed to what is seen in the Northern Hemisphere no centennial scale variability can establish, due to the absence of a strong feedback mechanism between ocean, atmosphere and sea ice. Kleppin, H., Jochum, M., Otto-Bliesner, B., Shields, C. A., & Yeager, S. (2015). Stochastic Atmospheric Forcing as a Cause of Greenland Climate Transitions. Journal of Climate, (2015). Markle, B. and Coauthors (2015, April). Atmospheric teleconnections between the tropics and high southern latitudes during millennial climate change. In EGU General Assembly Conference Abstracts (Vol. 17, p. 2569).

Oxidation products of biogenic emissions contribute to nucleation of atmospheric particles.

Science.gov (United States)

Riccobono, Francesco; Schobesberger, Siegfried; Scott, Catherine E; Dommen, Josef; Ortega, Ismael K; Rondo, Linda; Almeida, João; Amorim, Antonio; Bianchi, Federico; Breitenlechner, Martin; David, André; Downard, Andrew; Dunne, Eimear M; Duplissy, Jonathan; Ehrhart, Sebastian; Flagan, Richard C; Franchin, Alessandro; Hansel, Armin; Junninen, Heikki; Kajos, Maija; Keskinen, Helmi; Kupc, Agnieszka; Kürten, Andreas; Kvashin, Alexander N; Laaksonen, Ari; Lehtipalo, Katrianne; Makhmutov, Vladimir; Mathot, Serge; Nieminen, Tuomo; Onnela, Antti; Petäjä, Tuukka; Praplan, Arnaud P; Santos, Filipe D; Schallhart, Simon; Seinfeld, John H; Sipilä, Mikko; Spracklen, Dominick V; Stozhkov, Yuri; Stratmann, Frank; Tomé, Antonio; Tsagkogeorgas, Georgios; Vaattovaara, Petri; Viisanen, Yrjö; Vrtala, Aron; Wagner, Paul E; Weingartner, Ernest; Wex, Heike; Wimmer, Daniela; Carslaw, Kenneth S; Curtius, Joachim; Donahue, Neil M; Kirkby, Jasper; Kulmala, Markku; Worsnop, Douglas R; Baltensperger, Urs

2014-05-16

Atmospheric new-particle formation affects climate and is one of the least understood atmospheric aerosol processes. The complexity and variability of the atmosphere has hindered elucidation of the fundamental mechanism of new-particle formation from gaseous precursors. We show, in experiments performed with the CLOUD (Cosmics Leaving Outdoor Droplets) chamber at CERN, that sulfuric acid and oxidized organic vapors at atmospheric concentrations reproduce particle nucleation rates observed in the lower atmosphere. The experiments reveal a nucleation mechanism involving the formation of clusters containing sulfuric acid and oxidized organic molecules from the very first step. Inclusion of this mechanism in a global aerosol model yields a photochemically and biologically driven seasonal cycle of particle concentrations in the continental boundary layer, in good agreement with observations. Copyright © 2014, American Association for the Advancement of Science.

The atmospheric extinction of light

International Nuclear Information System (INIS)

Hughes, Stephen W; Powell, Sean; Carroll, Joshua; Cowley, Michael

2016-01-01

An experiment is described that enables students to understand the properties of atmospheric extinction due to Rayleigh scattering. The experiment requires the use of red, green and blue lasers attached to a travelling microscope or similar device. The laser beams are passed through an artificial atmosphere, made from milky water, at varying depths, before impinging on either a light meter or a photodiode integral to a Picotech Dr. DAQ ADC. A plot of measured spectral intensity verses depth reveals the contribution Rayleigh scattering has to the extinction coefficient. For the experiment with the light meter, the extinction coefficients for red, green and blue light in the milky sample of water were 0.27, 0.36 and 0.47 cm −1 respectively and 0.032, 0.037 and 0.092 cm −1 for the Picotech Dr. DAQ ADC. (paper)

HIGH-TEMPERATURE PHOTOCHEMISTRY IN THE ATMOSPHERE OF HD 189733b

International Nuclear Information System (INIS)

Line, M. R.; Yung, Y. L.; Liang, M. C.

2010-01-01

Recent infrared spectroscopy of hot exoplanets is beginning to reveal their atmospheric composition. Deep within the planetary atmosphere, the composition is controlled by thermochemical equilibrium. Photochemistry becomes important higher in the atmosphere, at levels above ∼1 bar. These two chemistries compete between ∼1 and 10 bars in hot-Jupiter-like atmospheres, depending on the strength of the eddy mixing and temperature. HD 189733b provides an excellent laboratory in which to study the consequences of chemistry of hot atmospheres. The recent spectra of HD 189733b contain signatures of CH 4 , CO 2 , CO, and H 2 O. Here we identify the primary chemical pathways that govern the abundances of CH 4 , CO 2 , CO, and H 2 O in the cases of thermochemical equilibrium chemistry, photochemistry, and their combination. Our results suggest that the disequilibrium mechanisms can significantly enhance the abundances of these species above their thermochemical equilibrium value, so some caution must be taken when assuming that an atmosphere is in strict thermochemical equilibrium.

Archives of Atmospheric Lead Pollution

Science.gov (United States)

Weiss, Dominik; Shotyk, William; Kempf, Oliver

Environmental archives such as peat bogs, sediments, corals, trees, polar ice, plant material from herbarium collections, and human tissue material have greatly helped to assess both ancient and recent atmospheric lead deposition and its sources on a regional and global scale. In Europe detectable atmospheric lead pollution began as early as 6000years ago due to enhanced soil dust and agricultural activities, as studies of peat bogs reveal. Increased lead emissions during ancient Greek and Roman times have been recorded and identified in many long-term archives such as lake sediments in Sweden, ice cores in Greenland, and peat bogs in Spain, Switzerland, the United Kingdom, and the Netherlands. For the period since the Industrial Revolution, other archives such as corals, trees, and herbarium collections provide similar chronologies of atmospheric lead pollution, with periods of enhanced lead deposition occurring at the turn of the century and since 1950. The main sources have been industry, including coal burning, ferrous and nonferrous smelting, and open waste incineration until c.1950 and leaded gasoline use since 1950. The greatest lead emissions to the atmosphere all over Europe occurred between 1950 and 1980 due to traffic exhaust. A marked drop in atmospheric lead fluxes found in most archives since the 1980s has been attributed to the phasing out of leaded gasoline. The isotope ratios of lead in the various archives show qualitatively similar temporal changes, for example, the immediate response to the introduction and phasing out of leaded gasoline. Isotope studies largely confirm source assessments based on lead emission inventories and allow the contributions of various anthropogenic sources to be calculated.

Atmospheric carbon reduction by urban trees

International Nuclear Information System (INIS)

Nowak, D.J.

1993-01-01

Trees, because they sequester atmospheric carbon through their growth process and conserve energy in urban areas, have been suggested as one means to combat increasing levels of atmospheric carbon. Analysis of the urban forest in Oakland, California (21% tree cover), reveals a tree carbon storage level of 11·0 metric tons/hectare. Trees in the area of the 1991 fire in Oakland stored approximately 14,500 metric tons of carbon, 10% of the total amount stored by Oakland's urban forest. National urban forest carbon storage in the United States (28% tree cover) is estimated at between 350 and 750 million metric tons. Establishment of 10 million urban trees annually over the next 10 years is estimated to sequester and offset the production of 363 million metric tons of carbon over the next 50 years-less than 1% of the estimated carbon emissions in the United States over the same time period. Advantages and limitations of managing urban trees to reduce atmospheric carbon are discussed. 36 refs., 2 figs., 3 tabs

Influence of atmospheric pressure on infrarenal abdominal aortic aneurysm rupture.

Science.gov (United States)

Robert, Nicolas; Frank, Michael; Avenin, Laure; Hemery, Francois; Becquemin, Jean Pierre

2014-04-01

Meteorologic conditions have a significant impact on the occurrence of cardiovascular events. Previous studies have shown that abdominal aortic aneurysm rupture (AAAR) may be associated with atmospheric pressure, with conflicting results. Therefore, we aimed to further investigate the nature of the correlation between atmospheric pressure variations and AAAR. Hospital admissions related to AAAR between 2005-2009 were assessed in 19 districts of metropolitan France and correlated with geographically and date-matched mean atmospheric pressures. In parallel and from 2005-2009, all fatal AAARs as reported by death certificates were assessed nationwide and correlated to local atmospheric pressures at the time of aortic rupture. Four hundred ninety-four hospital admissions related to AAAR and 6,358 deaths nationwide by AAAR were identified between 2005-2009. Both in-hospital ruptures and aneurysm-related mortality had seasonal variations, with peak/trough incidences in January and June, respectively. Atmospheric pressure peaks occurred during winter. Univariate analysis revealed a significant association (P atmospheric pressure values and AAAR. After multivariate analysis, mean maximum 1-month prerupture atmospheric pressure had a persistent correlation with both in-hospital relative risk (1.05 [95% confidence interval: 1.03-1.06]; P atmospheric pressure. Copyright © 2014 Elsevier Inc. All rights reserved.

Mobile Instruments Measure Atmospheric Pollutants

Science.gov (United States)

2009-01-01

As a part of NASA's active research of the Earth s atmosphere, which has included missions such as the Atmospheric Laboratory of Applications and Science (ATLAS, launched in 1992) and the Total Ozone Mapping Spectrometer (TOMS, launched on the Earth Probe satellite in 1996), the Agency also performs ground-based air pollution research. The ability to measure trace amounts of airborne pollutants precisely and quickly is important for determining natural patterns and human effects on global warming and air pollution, but until recent advances in field-grade spectroscopic instrumentation, this rapid, accurate data collection was limited and extremely difficult. In order to understand causes of climate change and airborne pollution, NASA has supported the development of compact, low power, rapid response instruments operating in the mid-infrared "molecular fingerprint" portion of the electromagnetic spectrum. These instruments, which measure atmospheric trace gases and airborne particles, can be deployed in mobile laboratories - customized ground vehicles, typically - to map distributions of pollutants in real time. The instruments must be rugged enough to operate rapidly and accurately, despite frequent jostling that can misalign, damage, or disconnect sensitive components. By measuring quickly while moving through an environment, a mobile laboratory can correlate data and geographic points, revealing patterns in the environment s pollutants. Rapid pollutant measurements also enable direct determination of pollutant sources and sinks (mechanisms that remove greenhouse gases and pollutants), providing information critical to understanding and managing atmospheric greenhouse gas and air pollutant concentrations.

Atmospheric processes on ice nanoparticles in molecular beams

Directory of Open Access Journals (Sweden)

Michal eFárník

2014-02-01

Full Text Available This review summarizes some recent experiments with ice nanoparticles (large water clusters in molecular beams and outlines their atmospheric relevance: (1 Investigation of mixed water–nitric acid particles by means of the electron ionization and sodium doping combined with photoionization revealed the prominent role of HNO3 molecule as the condensation nuclei. (2 The uptake of atmospheric molecules by water ice nanoparticles has been studied, and the pickup cross sections for some molecules exceed significantly the geometrical sizes of the ice nanoparticles. (3 Photodissociation of hydrogen halides on water ice particles has been shown to proceed via excitation of acidically dissociated ion pair and subsequent biradical generation and H3O dissociation. The photodissociation of CF2Cl2 molecule in clusters is also mentioned. Possible atmospheric consequences of all these results are briefly discussed.

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

International Nuclear Information System (INIS)

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

2006-01-01

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

Improving InSAR geodesy using Global Atmospheric Models

Science.gov (United States)

Jolivet, Romain; Agram, Piyush Shanker; Lin, Nina Y.; Simons, Mark; Doin, Marie-Pierre; Peltzer, Gilles; Li, Zhenghong

2014-03-01

Spatial and temporal variations of pressure, temperature, and water vapor content in the atmosphere introduce significant confounding delays in interferometric synthetic aperture radar (InSAR) observations of ground deformation and bias estimates of regional strain rates. Producing robust estimates of tropospheric delays remains one of the key challenges in increasing the accuracy of ground deformation measurements using InSAR. Recent studies revealed the efficiency of global atmospheric reanalysis to mitigate the impact of tropospheric delays, motivating further exploration of their potential. Here we explore the effectiveness of these models in several geographic and tectonic settings on both single interferograms and time series analysis products. Both hydrostatic and wet contributions to the phase delay are important to account for. We validate these path delay corrections by comparing with estimates of vertically integrated atmospheric water vapor content derived from the passive multispectral imager Medium-Resolution Imaging Spectrometer, onboard the Envisat satellite. Generally, the performance of the prediction depends on the vigor of atmospheric turbulence. We discuss (1) how separating atmospheric and orbital contributions allows one to better measure long-wavelength deformation and (2) how atmospheric delays affect measurements of surface deformation following earthquakes, and (3) how such a method allows us to reduce biases in multiyear strain rate estimates by reducing the influence of unevenly sampled seasonal oscillations of the tropospheric delay.

Comparison of Selenium Treatments of Crops in the Field

DEFF Research Database (Denmark)

Nielsen, Gunnar Gissel

1986-01-01

Field experiments with spring and winter barley and ryegrass were carried out to compare the effect of fertilizers enriched with selenate or selenite with foliar application on the selenium (Se) concentrations in the crops. Application of about 20 g Se/ha given as selenate or about 100 g as selen...... not occur. The choice of method thus depends on the farming practice in the individual cases....

Jovian atmospheres

International Nuclear Information System (INIS)

Allison, M.; Travis, L.D.

1986-10-01

A conference on the atmosphere of Jupiter produced papers in the areas of thermal and ortho-para hydrogen structure, clouds and chemistry, atmospheric structure, global dynamics, synoptic features and processes, atmospheric dynamics, and future spaceflight opportunities. A session on the atmospheres of Uranus and Neptune was included, and the atmosphere of Saturn was discussed in several papers

Identification and characterization of bacteria in a selenium-contaminated hypersaline evaporation pond.

Science.gov (United States)

de Souza, M P; Amini, A; Dojka, M A; Pickering, I J; Dawson, S C; Pace, N R; Terry , N

2001-09-01

Solar evaporation ponds are commonly used to reduce the volume of seleniferous agricultural drainage water in the San Joaquin Valley, Calif. These hypersaline ponds pose an environmental health hazard because they are heavily contaminated with selenium (Se), mainly in the form of selenate. Se in the ponds may be removed by microbial Se volatilization, a bioremediation process whereby toxic, bioavailable selenate is converted to relatively nontoxic dimethylselenide gas. In order to identify microbes that may be used for Se bioremediation, a 16S ribosomal DNA phylogenetic analysis of an aerobic hypersaline pond in the San Joaquin Valley showed that a previously unaffiliated group of uncultured bacteria (belonging to the order Cytophagales) was dominant, followed by a group of cultured gamma-Proteobacteria which was closely related to Halomonas species. Se K-edge X-ray absorption spectroscopy of selenate-treated bacterial isolates showed that they accumulated a mixture of predominantly selenate and a selenomethionine-like species, consistent with the idea that selenate was assimilated via the S assimilation pathway. One of these bacterial isolates (Halomonas-like strain MPD-51) was the best candidate for the bioremediation of hypersaline evaporation ponds contaminated with high Se concentrations because it tolerated 2 M selenate and 32.5% NaCl, grew rapidly in media containing selenate, and accumulated and volatilized Se at high rates (1.65 microg of Se g of protein(-1) x h(-1)), compared to other cultured bacterial isolates.

Band gap engineering of tandem structured CIGS compound absorption layer fabricated by sputtering and selenization

International Nuclear Information System (INIS)

Kang, San; Sharma, Rahul; Sim, Jae-Kwan; Lee, Cheul-Ro

2013-01-01

Highlights: ► Systematic band gap engineering to fabricate tandem Cu(In,Ga)Se 2 absorption layers. ► XRD shows prominent (1 1 2) reflection shift for attributed CIS, CIGS, and CGS phases. ► Optical transmittance and reflectance spectrum are improved towards infrared region. ► The Cu/In + Ga and Ga/In + Ga effect is matched with highest efficient solar cell. ► Tandem CIS/CIGS/CGS layer, the band gap is increased from 1.15 to 2.06 eV. -- Abstract: Band gap engineering was executed to fabricate a multi-junction stacked i.e. tandem Cu(In,Ga)Se 2 (CIGS) absorption layer. The CIGS absorption layers consist of multi-junction stacked CIS/CIGS/CGS thin films from bottom to top with increasing band gap. Tandem CIGS layers were fabricated by using three precursor of CuIn, In/CuGa/In, and CuGa onto the Mo coated soda-lime glass (SLG) by the sequential sputtering of CuIn, CuGa, and In targets. The CIG precursors were converted into CIGS absorption thin film by selenization process. From the X-ray diffraction (XRD) pattern of CIS/CIGS/CGS tandem layer, with the prominent peak shift for (1 1 2) reflections was attributed to the individual CIS, CIGS, and CGS phases at 26.76°, 27.15°, and 27.65° diffraction angles, respectively. The morphologies and atomic (at%) composition uniformity onto the surface and along the depth were extensively analyzed with field effect scanning electron microscope (FESEM) attached energy dispersive spectroscopy (EDS) and secondary ion mass spectroscopy (SIMS). The optical properties such as transmittance, reflectance and absorbance were found to improve in the infrared region for all the tandem CIGS layers. Near the fundamental absorption edge, the absorption coefficient was approached to 10 5 cm −1 for CIS/CIGS/CGS tandem layer. The straight-line behavior indicates that the films have a direct band gap. The band gap was found to increase from 1.15 to 1.74 eV with the Ga-grading along the depth of individual CIS, CIGS, and CGS thin films

Atmospheric bulk deposition of polycyclic aromatic hydrocarbons in Shanghai: Temporal and spatial variation, and global comparison

International Nuclear Information System (INIS)

Feng, Daolun; Liu, Ying; Gao, Yi; Zhou, Jinxing; Zheng, Lirong; Qiao, Gang; Ma, Liming; Lin, Zhifen; Grathwohl, Peter

2017-01-01

Atmospheric deposition leads to accumulation of atmospheric polycyclic aromatic hydrocarbons (PAHs) on urban surfaces and topsoils. To capture the inherent variability of atmospheric deposition of PAHs in Shanghai's urban agglomeration, 85 atmospheric bulk deposition samples and 7 surface soil samples were collected from seven sampling locations during 2012–2014. Total fluxes of 17 PAHs were 587-32,300 ng m −2 day −1 , with a geometric mean of 2600 ng m −2 day −1 . The deposition fluxes were categorized as moderate to high on a global scale. Phenanthrene, fluoranthene and pyrene were major contributors. The spatial distribution of deposition fluxes revealed the influence of urbanization/industrialization and the relevance of local emissions. Meteorological conditions and more heating demand in cold season lead to a significant increase of deposition rates. Atmospheric deposition is the principal pathway of PAHs input to topsoils and the annual deposition load in Shanghai amounts to ∼4.5 tons (0.7 kg km −2 ) with a range of 2.5–10 tons (0.4–1.6 kg km −2 ). - Highlights: • PAH deposition flux in Shanghai is categorized as moderate to high on global scale. • Their spatial distribution reveals the influence of urbanization/industrialization. • Atmospheric deposition is the principal pathway of PAHs input to local topsoils. • Other pathways have to be considered for PAH input in urban soil. - Atmospheric deposition of PAHs revealed the influence of urbanization and industrialization and the relevance of local emissions on Shanghai topsoils.

Staging atmospheres

DEFF Research Database (Denmark)

Bille, Mikkel; Bjerregaard, Peter; Sørensen, Tim Flohr

2015-01-01

The article introduces the special issue on staging atmospheres by surveying the philosophical, political and anthropological literature on atmosphere, and explores the relationship between atmosphere, material culture, subjectivity and affect. Atmosphere seems to occupy one of the classic...

Synthesis and crystal structure of Fe[(Te1.5Se0.5)O5]Cl, the first iron compound with selenate(IV) and tellurate(IV) groups

Science.gov (United States)

Akhrorov, Akhmad Yu; Kuznetsova, Elena S.; Aksenov, Sergey M.; Berdonosov, Peter S.; Kuznetsov, Alexey N.; Dolgikh, Valery A.

2017-12-01

During the search for selenium analogues of FeTe2O5Cl, the new iron (III) tellurate(IV) selenate(IV) chloride with the composition Fe[(Te1.5Se0.5)O5]Cl was synthesized by chemical vapor transport (CVT) reaction and characterized by TGA-, EDX-,SCXRD-analysis, as well as IR and Raman spectroscopy. It was found that Fe[(Te1.5Se0.5)O5]Cl crystallizes in the monoclinic space group P21/c with unitcell parameters a = 5.183(3) Å, b = 15.521(9) Å, c = 7.128(5) Å and β = 107.16(1)°. The crystal structure of Fe[(Te1.5Se0.5)O5]Cl represents a new structure type and contains electroneutral heteropolyhedral layers formed by dimers of the [FeO5Cl]8- octahedra, linked via common O-O edges, and mixed [Te3SeO10]4- tetramers. Adjacent layers are stacked along the b axis and linked by weak residual bonds. The new compound is stable up to 420 °C. DFT calculations predict Fe[(Te1.5Se0.5)O5]Cl to be a wide-gap semiconductor with the band gap of ca. 2.7 eV.

Migration history of air-breathing fishes reveals Neogene atmospheric circulation patterns

Science.gov (United States)

Böhme, M.

2004-05-01

The migration history of an air-breathing fish group (Channidae; snakehead fishes) is used for reconstructing Neogene Eurasian precipitation and atmospheric circulation patterns. The study shows that snakeheads are sensitive indicators of summer precipitation maxima in subtropical and temperate regions, and are present regularly if the wettest month exceeds 150 mm precipitation and 20 °C mean temperature. The analysis of 515 fossil freshwater fish deposits of the past 50 m.y. from Africa and Eurasia shows two continental-scale migration events from the snakeheads' center of origin in the south Himalayan region, events that can be related to changes in the Northern Hemisphere circulation pattern. The first migration, ca. 17.5 Ma, into western and central Eurasia may have been caused by a northward shift of the Intertropical Convergence Zone that brought western Eurasia under the influence of trade winds that produced a zonal and meridional precipitation gradient in Europe. During the second migration, between 8 and 4 Ma, into Africa and East Asia, snakeheads reached their present-day distribution. This migration could have been related to the intensification of the Asian monsoon that brought summer precipitation to their migratory pathways in East Africa Arabia and East Asia.

Atmospheric-pressure plasma activation and surface characterization on polyethylene membrane separator

Science.gov (United States)

Tseng, Yu-Chien; Li, Hsiao-Ling; Huang, Chun

2017-01-01

The surface hydrophilic activation of a polyethylene membrane separator was achieved using an atmospheric-pressure plasma jet. The surface of the atmospheric-pressure-plasma-treated membrane separator was found to be highly hydrophilic realized by adjusting the plasma power input. The variations in membrane separator chemical structure were confirmed by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. Chemical analysis showed newly formed carbonyl-containing groups and high surface concentrations of oxygen-containing species on the atmospheric-pressure-plasma-treated polymeric separator surface. It also showed that surface hydrophilicity primarily increased from the polar component after atmospheric-pressure plasma treatment. The surface and pore structures of the polyethylene membrane separator were examined by scanning electron microscopy, revealing a slight alteration in the pore structure. As a result of the incorporation of polar functionalities by atmospheric-pressure plasma activation, the electrolyte uptake and electrochemical impedance of the atmospheric-pressure-plasma-treated membrane separator improved. The investigational results show that the separator surface can be controlled by atmospheric-pressure plasma surface treatment to tailor the hydrophilicity and enhance the electrochemical performance of lithium ion batteries.

HIGH-RESOLUTION SATELLITE IMAGING OF THE 2004 TRANSIT OF VENUS AND ASYMMETRIES IN THE CYTHEREAN ATMOSPHERE

International Nuclear Information System (INIS)

Pasachoff, Jay M.; Schneider, Glenn; Widemann, Thomas

2011-01-01

This paper presents the only space-borne optical-imaging observations of the 2004 June 8 transit of Venus, the first such transit visible from Earth since AD 1882. The high-resolution, high-cadence satellite images we arranged from NASA's Transition Region and Coronal Explorer (TRACE) reveal the onset of visibility of Venus's atmosphere and give further information about the black-drop effect, whose causes we previously demonstrated from TRACE observations of a transit of Mercury. The atmosphere is gradually revealed before second contact and after third contact, resulting from the changing depth of atmospheric layers refracting the photospheric surface into the observer's direction. We use Venus Express observations to relate the atmospheric arcs seen during the transit to the atmospheric structure of Venus. Finally, we relate the transit images to current and future exoplanet observations, providing a sort of ground truth showing an analog in our solar system to effects observable only with light curves in other solar systems with the Kepler and CoRoT missions and ground-based exoplanet-transit observations.

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

Science.gov (United States)

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

2017-06-01

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

Atmospheric contamination

International Nuclear Information System (INIS)

Gruetter, Juerg

1997-01-01

It is about the levels of contamination in center America, the population's perception on the problem, effects of the atmospheric contamination, effects in the environment, causes of the atmospheric contamination, possibilities to reduce the atmospheric contamination and list of Roeco Swisscontac in atmospheric contamination

Glimpses of far away places: Intensive atmosphere characterization of extrasolar planets

Science.gov (United States)

Kreidberg, Laura

Exoplanet atmosphere characterization has the potential to reveal the origins, nature, and even habitability of distant worlds. This thesis represents a step towards realizing that potential for a diverse group of four extrasolar planets. Here, I present the results of intensive observational campaigns with the Hubble and Spitzer Space Telescopes to study the atmospheres of the super-Earth GJ 1214b and the hot Jupiters WASP-43b, WASP-12b, and WASP-103b. I measured an unprecedentedly precise near-infrared transmission spectrum for GJ 1214b that definitively reveals the presence of clouds in the planet's atmosphere. For WASP-43b and WASP-12b, I also measured very precise spectra that exhibit water features at high confidence (>7 sigma). The retrieved water abundance for WASP-43b extends the well-known Solar System trend of decreasing atmospheric metallicity with increasing planet mass. The detection of water for WASP-12b marks the first spectroscopic identification of a molecule in the planet's atmosphere and implies that it has solar composition, ruling out carbon-to-oxygen ratios greater than unity. For WASP-103b, I present preliminary results from the new technique of phase-resolved spectroscopy to determine the planet's temperature structure, dynamics, and energy budget. In addition to these observations, I also describe the BATMAN code, an open-source Python package for fast and flexible modeling of transit light curves. Taken together, these results provide a foundation for comparative planetology beyond the Solar System and the investigation of Earth-like, potentially habitable planets with future observing facilities.

Comparative enzymology of the adenosine triphosphate sulfurylases from leaf tissue of selenium-accumulator and non-accumulator plants

Energy Technology Data Exchange (ETDEWEB)

Shaw, W H; Anderson, J W

1974-01-01

ATP sulfurylases were partially purified (20-40-fold) from leaf tissue of Astragalus bisulcatus, Astragalus racemosus (selenium-accumulator species) and Astragalus hamosus and Astragalus sinicus (non-accumulator species). Activity was measured by sulfate-dependent PP/sub 1/-ATP exchange. The enzymes were separated from pyrophosphatase and adenosine triphosphatase activities. The properties of the Astragalus ATP sulfurylases were similar to the spinach enzyme. The ATP sulfurylases from both selenium-accumulator and non-accumulator species catalyzed selenate-dependent PP/sub 1/-ATP exchange; selenate competed with sulfate. The ratio of V(selenate)/V(sulfate) and K/sub m/ (selenate)/K/sub m/(sulfate) was approximately the same for the enzyme from each species. Sulfate-dependent PP/sub 1/-ATP exchange was inhibited by ADP, chlorate and nitrate. The kinetics of the inhibition for each enzyme were consistent with an ordered reaction mechanisms, in which ATP is the first substrate to react with the enzyme and PP/sub 1/ is the first product released. Synthesis of adenosine 5'-(/sup 35/S)sulfatophosphate from (/sup 35/S)sulfate was demonstrated by coupling the Astrgalus ATP sulfurylases with Mg/sup 2 +/-dependent pyrophosphatase; the reaction was inhibited by selenate. An analogous reaction using (/sup 75/Se)selenate as substrate could not be demonstrated.

Density imaging of volcanos with atmospheric muons

OpenAIRE

Fehr , F.

2011-01-01

collaboration : TOMUVOL; International audience; Their capability to penetrate large depths of material renders high-energy atmospheric muons a unique probe for geophysical explorations. Provided the topography of the target is known, the measurement of the attenuation of the muon flux permits the cartography of matter density distributions revealing spatial and possibly also temporal variations in extended geological structures. A Collaboration between volcanologists, astroparticle- and part...

Annealing in sulfur of CZTS nanoparticles deposited through doctor blading

DEFF Research Database (Denmark)

Engberg, Sara Lena Josefin; Crovetto, Andrea

of the main limitations for this approach, and (2) grain boundaries and defects are believed to be a site for recombination that limit the efficiency. Annealing in vacuum and/or nitrogen atmosphere facilitates grain growth and improves the electronic properties. Conventionally selenization shows the best...... results, however sulfurization has the advantage of being less toxic. In this work, nanocrystals of CZTS with a targeted Cu-poor/Zn-rich composition are synthesized through a hot-injection method with oleylamine as the solvent. The nanocrystal inks are deposited through doctor blading in octanethiol...

Latitudinal and seasonal variations of lower atmospheric inertial gravity wave energy revealed by US radiosonde data

Energy Technology Data Exchange (ETDEWEB)

Zhang, S.D.; Yi, F. [Wuhan Univ., Hubei (China). School of Electronic Information; Ministry of Education, Wuhan, Hubei (China). Key Lab. of Geospace Environment and Geodesy; State Observatory for Atmospheric Remote Sensing, Wuhan (China); Huang, C.M. [Wuhan Univ., Hubei (China). School of Electronic Information; Ministry of Education, Wuhan, Hubei (China). Key Lab. of Geospace Environment and Geodesy; State Observatory for Atmospheric Remote Sensing, Wuhan (China); Miami Univ., Oxford, OH (United States). Electrical and Computer Engineering Dept.; Zhou, Q. [Miami Univ., Oxford, OH (United States). Electrical and Computer Engineering Dept.

2010-07-01

The latitudinal and seasonal variations of gravity wave (GW) potential energy density (E{sub P}), kinetic energy density (E{sub K}), and total energy density (E{sub T}), i.e, the sum of potential and kinetic energy densities in the tropospheric (typically 2-10 km) and lower stratospheric (typically 18- 25 km) segments have been derived from 10 years (1998- 2007) of radiosonde observations over 92 United States stations in the Northern Hemisphere. The latitudinal variation of E{sub P} in the lower stratosphere is in good agreement with satellite observations. However, E{sub K} and E{sub T} in the lower stratosphere are different from satellite observations and the difference is believed to be linked with the latitudinal dependence of GW sources. Our analysis reveals that GW energy properties exhibit distinctive latitudinal and seasonal variations. The upward-propagating GW energy in the troposphere is larger than that in the lower stratosphere at low latitudes but the opposite holds true at high latitudes. The transition latitude, where the upward- propagating energies in the two altitude regions are the same, occurs at 35 N throughout the year. So striking differences between GW activity in the troposphere and lower stratosphere are not likely explained only by the background wind Doppler shifting due to strong tropospheric jets. Our analysis indicates that the region around tropopause, roughly from 10 km to 18 km, is an important source region, especially at latitudes below 35 N. Our studies strongly suggest that in order to fully understand the global GW activity in the lower atmosphere, the GW kinetic energy and its geographical and seasonal variations should be included, and more attention should be given to GWs in the troposphere and GW sources within the intermediate region, especially the upper troposphere. (orig.)

Latitudinal and seasonal variations of lower atmospheric inertial gravity wave energy revealed by US radiosonde data

Directory of Open Access Journals (Sweden)

S. D. Zhang

2010-05-01

Full Text Available The latitudinal and seasonal variations of gravity wave (GW potential energy density (EP, kinetic energy density (EK, and total energy density (ET, i.e, the sum of potential and kinetic energy densities in the tropospheric (typically 2–10 km and lower stratospheric (typically 18–25 km segments have been derived from 10 years (1998–2007 of radiosonde observations over 92 United States stations in the Northern Hemisphere. The latitudinal variation of EP in the lower stratosphere is in good agreement with satellite observations. However, EK and ET in the lower stratosphere are different from satellite observations and the difference is believed to be linked with the latitudinal dependence of GW sources. Our analysis reveals that GW energy properties exhibit distinctive latitudinal and seasonal variations. The upward-propagating GW energy in the troposphere is larger than that in the lower stratosphere at low latitudes but the opposite holds true at high latitudes. The transition latitude, where the upward- propagating energies in the two altitude regions are the same, occurs at 35° N throughout the year. So striking differences between GW activity in the troposphere and lower stratosphere are not likely explained only by the background wind Doppler shifting due to strong tropospheric jets. Our analysis indicates that the region around tropopause, roughly from 10 km to 18 km, is an important source region, especially at latitudes below 35° N. Our studies strongly suggest that in order to fully understand the global GW activity in the lower atmosphere, the GW kinetic energy and its geographical and seasonal variations should be included, and more attention should be given to GWs in the troposphere and GW sources within the intermediate region, especially the upper troposphere.

Surface cleaning of metal wire by atmospheric pressure plasma

International Nuclear Information System (INIS)

Nakamura, T.; Buttapeng, C.; Furuya, S.; Harada, N.

2009-01-01

In this study, the possible application of atmospheric pressure dielectric barrier discharge plasma for the annealing of metallic wire is examined and presented. The main purpose of the current study is to examine the surface cleaning effect for a cylindrical object by atmospheric pressure plasma. The experimental setup consists of a gas tank, plasma reactor, and power supply with control panel. The gas assists in the generation of plasma. Copper wire was used as an experimental cylindrical object. This copper wire was irradiated with the plasma, and the cleaning effect was confirmed. The result showed that it is possible to remove the tarnish which exists on the copper wire surface. The experiment reveals that atmospheric pressure plasma is usable for the surface cleaning of metal wire. However, it is necessary to examine the method for preventing oxidization of the copper wire.

Study of the high power laser-metal interactions in the gaseous atmospheres

Science.gov (United States)

Lugomer, Stjepan; Bitelli, G.; Stipancic, M.; Jovic, F.

1994-08-01

The tantalum and titanium plates were treated by pulsed, high power CO2 laser in the pressurized atmospheres of N2 and O2. Studies performed by the optical microscopy, microhardness measurements, and the auger electron spectroscopy revealed: (1) topographic modification of the surface caused by the temperature field; (2) metal hardening, caused by the laser shock; and (3) alloying/cladding, caused by the chemical reaction between the metal surface and the gaseous atmosphere.

Simultaneous detection of selenium by atomic fluorescence and sulfur by molecular emission by flow-injection hydride generation with on-line reduction for the determination of selenate, sulfate and sulfite

Energy Technology Data Exchange (ETDEWEB)

Tyson, J.F., E-mail: tyson@chem.umass.edu [Department of Chemistry, University of Massachusetts, 710 North Pleasant Street, Amherst, MA 01003 (United States); Palmer, C.D. [Lead Poisoning Trace Elements Laboratory, Wadsworth Center, New York State Department of Health, P.O. Box 509, Empire State Plaza, Albany, NY 12201-0509 (United States)

2009-10-12

An inductively coupled plasma atomic fluorescence spectrometry (ICP-AFS) instrument, was modified so that it was capable of monitoring transient chromatographic or flow-injection profiles and that sulfur molecular emission and selenium atomic fluorescence could be monitored simultaneously in an argon-hydrogen diffusion flame on a glass burner. The analytes were introduced as hydrogen selenide and hydrogen sulfide, generated on a flow-injection manifold. Selenate was reduced to hydride-forming selenite by microwave-assisted on-line reaction with hydrochloric acid, and sulfate, or sulfite, was reduced to hydride-forming sulfide by a mixture of hydriodic acid, acetic acid and sodium hypophosphite. The effects of the nature of reducing agent, flow rate, microwave power and coil length were studied. The limit of detection (3 s) for selenium was 10 {mu}g L{sup -1}, and for sulfide was 70 {mu}g L{sup -1} (200-{mu}L injection volume). The calibration was linear for selenium up to 2 mg L{sup -1} and to 10 mg L{sup -1} for sulfide. The throughput was 180 h{sup -1}. The three sulfur species could be differentiated on the basis of reactivity at various microwave powers.

Design and implementation of atmospheric multi-parameter sensor for UAVs

Science.gov (United States)

Yu, F.; Zhao, Y.; Chen, G.; Liu, Y.; Han, Y.

2017-12-01

With the rapid development of industry and the increase of cars in developing countries, air pollutants have caused a series of environmental issues such as haze and smog. However, air pollution is a process of surface-to-air mass exchange, and various kinds of atmospheric factors have close association with aerosol concentration, such as temperature, humidity, etc. Vertical distributions of aerosol in the region provide an important clue to reveal the exchange mechanism in the atmosphere between atmospheric boundary layer and troposphere. Among the various kinds of flying platforms, unmanned aerial vehicles (UAVs) shows more advantages in vertical measurement of aerosol owned to its flexibility and low cost. However, only few sensors could be mounted on the UAVs because of the limited size and power requirement. Here, a light-weight, low-power atmospheric multi-parameter sensor (AMPS) is proposed and could be mounted on several kinds of UAV platforms. The AMPS integrates multi-sensors, which are the laser aerosol particle sensor, the temperature probe, the humidity probe and the pressure probe, in order to simultaneously sample the vertical distribution characters of aerosol particle concentration, temperature, relative humidity and atmospheric pressure. The data from the sensors are synchronized by a proposed communication mechanism based on GPS. Several kinds of housing are designed to accommodate the different payload requirements of UAVs in size and weight. The experiments were carried out with AMPS mounted on three kinds of flying platforms. The results shows that the power consumption is less than 1.3 W, with relatively high accuracy in temperature (±0.1°C), relative humidity (±0.8%RH), PM2.5 (<20%) and PM10 (<20%). Vertical profiles of PM2.5 and PM10 concentrations were observed simultaneously by the AMPS three times every day in five days. The results revealed the significant correlation between the aerosol particle concentration and atmospheric

Atmospheric Precipitations, Hailstone and Rainwater, as a Novel Source of Streptomyces Producing Bioactive Natural Products

Science.gov (United States)

Sarmiento-Vizcaíno, Aida; Espadas, Julia; Martín, Jesús; Braña, Alfredo F.; Reyes, Fernando; García, Luis A.; Blanco, Gloria

2018-01-01

A cultivation-dependent approach revealed that highly diverse populations of Streptomyces were present in atmospheric precipitations from a hailstorm event sampled in February 2016 in the Cantabrian Sea coast, North of Spain. A total of 29 bioactive Streptomyces strains isolated from small samples of hailstone and rainwater, collected from this hailstorm event, were studied here. Taxonomic identification by 16S rRNA sequencing revealed more than 20 different Streptomyces species, with their closest homologs displaying mainly oceanic but also terrestrial origins. Backward trajectory analysis revealed that the air-mass sources of the hailstorm event, with North Western winds, were originated in the Arctic Ocean (West Greenland and North Iceland) and Canada (Labrador), depending on the altitude. After traveling across the North Atlantic Ocean during 4 days the air mass reached Europe and precipitated as hailstone and rain water at the sampling place in Spain. The finding of Streptomyces species able to survive and disperse through the atmosphere increases our knowledge of the biogeography of genus Streptomyces on Earth, and reinforces our previous dispersion model, suggesting a generalized feature for the genus which could have been essential in his evolution. This unique atmospheric-derived Streptomyces collection was screened for production of bioactive secondary metabolites. Analyses of isolates ethyl acetate extracts by LC-UV-MS and further database comparison revealed an extraordinary diversity of bioactive natural products. One hundred molecules were identified, mostly displaying contrasted antibiotic and antitumor/cytotoxic activities, but also antiparasitic, antiviral, anti-inflammatory, neuroprotector, and insecticide properties. More interestingly, 38 molecules not identified in natural products databases might represent new natural products. Our results revealed for the first time an extraordinary diversity of Streptomyces species in the atmosphere able to

Comparison of Selenium Toxicity in Sunflower and Maize Seedlings Grown in Hydroponic Cultures.

Science.gov (United States)

Garousi, Farzaneh; Veres, Szilvia; Kovács, Béla

2016-11-01

Several studies have demonstrated that selenium (Se) at low concentrations is beneficial, whereas high Se concentrations can induce toxicity. Controlling Se uptake, metabolism, translocation and accumulation in plants is important to decrease potential health risks and helping to select proper biofortification methods to improve the nutritional content of plant-based foods. The uptake and distribution of Se, changes in Se content, and effects of various concentrations of Se in two forms (sodium selenite and sodium selenate) on sunflower and maize plants were measured in nutrient solution experiments. Results revealed the Se content in shoots and roots of both sunflower and maize plants significantly increased as the Se level increased. In this study, the highest exposure concentrations (30 and 90 mg/L, respectively) caused toxicity in both sunflower and maize. While both Se forms damaged and inhibited plant growth, each behaved differently, as toxicity due to selenite was observed more than in the selenate treatments. Sunflower demonstrated a high Se accumulation capacity, with higher translocation of selenate from roots to shoots compared with selenite. Since in seleniferous soils, a high change in plants' capability exists to uptake Se from these soils and also most of the cultivated crop plants have a bit tolerance to high Se levels, distinction of plants with different Se tolerance is important. This study has tried to discuss about it.

Seductive Atmospheres: Using tools to effectuate spaces for Leadership Development

DEFF Research Database (Denmark)

Elmholdt, Kasper Trolle; Clausen, Rune Thorbjørn; Madsen, Mona T

2018-01-01

Hospital, this study investigates how a business game is used as a tool to effectuate episodic spaces for leadership development. The study reveals three tool affordances and discusses how they enable and constrain episodic spaces for development and further develops the notion of seductive atmospheres......This study applies an affordance lens to understand the use of management tools and how atmospheres for change and development are created and exploited. Drawing on an ethnographic case study of a consultant-facilitated change intervention among a group of research leaders at a Danish Public...... as an important mechanism. The article suggests that a broader understanding of the use of tools and the role of atmospheres is essential for understanding how episodic spaces for development come to work in relation to organizational change and development....

PIXE analysis of atmospheric aerosols in the city of Buenos Aires

International Nuclear Information System (INIS)

Ozafran, M.J.; Vazquez, M.E.; Burlon, A.

1999-01-01

Lead pollution present in atmospheric aerosols in the city Buenos Aires was measured in 1989, using Heavy Ion PIXE. Since then, environmental conditions have changed significantly. The usage of unleaded gasoline was introduced, and the utilisation of compressed natural gas as car fuel has increased. Recently, a new sampling campaign of atmospheric aerosols has started, partly in collaboration with the Greenpeace Foundation. The present studies reveal that lead pollution in Buenos Aires has significantly decreased since 1989. The concentrations of other elements are determined as well. (author)

Chemical and structural evolution in the Th-SeO3(2-)/SeO4(2-) system: from simple selenites to cluster-based selenate compounds.

Science.gov (United States)

Xiao, Bin; Langer, Eike; Dellen, Jakob; Schlenz, Hartmut; Bosbach, Dirk; Suleimanov, Evgeny V; Alekseev, Evgeny V

2015-03-16

While extensive success has been gained in the structural chemistry of the U-Se system, the synthesis and characterization of Th-based Se structures are widely unexplored. Here, four new Th-Se compounds, α-Th(SeO3)2, β-Th(SeO3)2, Th(Se2O5)2, and Th3O2(OH)2(SeO4)3, have been obtained from mild hydrothermal or low-temperature (180-220 °C) flux conditions and were subsequently structurally and spectroscopically characterized. The crystal structures of α-Th(SeO3)2 and β-Th(SeO3)2 are based on ThO8 and SeO3 polyhedra, respectively, featuring a three-dimensional (3D) network with selenite anions filling in the Th channels along the a axis. Th(Se2O5)2 is a 3D framework composed of isolated ThO8 polyhedra interconnected by [Se2O5](2-) dimers. Th3O2(OH)2(SeO4)3 is also a 3D framework constructed by octahedral hexathorium clusters [Th6(μ3-O)4(μ3-OH)4](12+), which are interlinked by selenate groups SeO4(2-). The positions of the vibrational modes associated with both Se(IV)O3(2-) and Se(VI)O4(2-) units, respectively, were determined for four compounds, and the Raman spectra of α- and β-Th(SeO3)2 are compared and discussed in detail.

SeO2 adsorption on CaO surface: DFT study on the adsorption of a single SeO2 molecule

Science.gov (United States)

Fan, Yaming; Zhuo, Yuqun; Lou, Yu; Zhu, Zhenwu; Li, Liangliang

2017-08-01

Selenium is a hazardous element in coal. During coal combustion, most of the selenium will convert to SeO2 in the flue gas. Ca-based adsorbents, especially CaO, have been considered as a potential sorbent to adsorb SeO2 due to its low cost. In this paper, the adsorption mechanisms of single SeO2 on CaO surface were investigated by density functional theory (DFT) calculation. Both the physisorption and chemisorption structures were determined. It has been identified that the adsorption of SeO2 on CaO surface is primarily chemisorption, while physisorption takes effects at the initial stage of the process. Under O2 atmosphere, selenate is hard to form. Most of the adsorption products are selenite. Additionally, the electron density maps were obtained to reveal the surface active sites. The partial density of states (PDOS) was calculated for analyzing the electronic structural change of SeO2 and CaO surface during adsorption. The results provide fundamental information of the adsorption process, which could be meaningful for the development of new absorbents.

Characteristics in mineral compositions of lunar latest mare volcanism revealed from spectral data

Science.gov (United States)

Kato, S.; Morota, T.; Yamaguchi, Y.; Watanabe, S.; Otake, H.; Ohtake, M.; Nimura, T.

2016-12-01

Lunar mare basalts provide insights into the composition and thermal history of the lunar mantle. According to crater counting analysis with remote sensing data, the ages of mare basalts suggest a first peak of magma activity at 3.2-3.8 Ga and a second peak at 2 Ga. In order to understand the mechanism for causing the second peak and its magma source, we reassess the correlation between the titanium contents and the eruption ages of mare basalt units using the compositional and chronological data updated by SELENE (Kaguya). In the Procellarum KREEP Terrane, where the latest mare basalt units are concentrated, an increase in the mean titanium content is observed in the Eratosthenian Period, as reported by previous studies. We found that, however, a rapid increase in mean titanium content occurred near 2.3 Ga. This result suggests that the magma source of the mare basalts changed at this particular age. Moreover, the high-titanium basaltic eruptions are correlated with the second peak in mare volcanism at 2 Ga. The latest mare volcanism may have been induced by a super-hot plume originating from the core-mantle boundary. In this study, to reveal the difference between the volcanic activities before and after 2.3 Ga, we developed the method to estimate the mineral components and elemental compositions of lunar mare basalts by using the Kaguya Spectral Profiler data. We will introduce the detail of the method and discuss about the difference between the mineral compositions of mare basalts before and after 2.3 Ga based on our preliminary results.

Evidence for a link between atmospheric thermonuclear detonations and nitric acid.

Science.gov (United States)

Holdsworth, G

1986-12-11

Suitably located glacier cores, obtained from high-altitude, low-temperature sites, can reveal detailed information about atmospheric air chemistry at sub-annual resolution 1 . Such data may provide input to climate-change models, the study of acid precipitation patterns and many other phenomena. Here I present data from an ice core which show that during the era of intense atmospheric thermonuclear weapons testing (ATWT) a significant part of the nitrate content in the snow was modulated by the intensity of the nuclear detonations. The fixation of nitrogen by nuclear fireballs leads to NO x gases in the atmosphere 2 and ultimately to nitric acid in precipitation. At certain concentrations, these gases and the associated aerosols may perturb the climate 3,4 .

Band gap engineering of tandem structured CIGS compound absorption layer fabricated by sputtering and selenization

Energy Technology Data Exchange (ETDEWEB)

Kang, San; Sharma, Rahul; Sim, Jae-Kwan [Semiconductor Materials Processing Laboratory, School of Advanced Materials Engineering, College of Engineering, Research Center for Advanced Materials Development (RCAMD), Chonbuk National University, Deokjin-dong 664-14, Jeonju 561-756 (Korea, Republic of); Lee, Cheul-Ro, E-mail: crlee7@jbnu.ac.kr [Semiconductor Materials Processing Laboratory, School of Advanced Materials Engineering, College of Engineering, Research Center for Advanced Materials Development (RCAMD), Chonbuk National University, Deokjin-dong 664-14, Jeonju 561-756 (Korea, Republic of)

2013-06-25

Highlights: ► Systematic band gap engineering to fabricate tandem Cu(In,Ga)Se{sub 2} absorption layers. ► XRD shows prominent (1 1 2) reflection shift for attributed CIS, CIGS, and CGS phases. ► Optical transmittance and reflectance spectrum are improved towards infrared region. ► The Cu/In + Ga and Ga/In + Ga effect is matched with highest efficient solar cell. ► Tandem CIS/CIGS/CGS layer, the band gap is increased from 1.15 to 2.06 eV. -- Abstract: Band gap engineering was executed to fabricate a multi-junction stacked i.e. tandem Cu(In,Ga)Se{sub 2} (CIGS) absorption layer. The CIGS absorption layers consist of multi-junction stacked CIS/CIGS/CGS thin films from bottom to top with increasing band gap. Tandem CIGS layers were fabricated by using three precursor of CuIn, In/CuGa/In, and CuGa onto the Mo coated soda-lime glass (SLG) by the sequential sputtering of CuIn, CuGa, and In targets. The CIG precursors were converted into CIGS absorption thin film by selenization process. From the X-ray diffraction (XRD) pattern of CIS/CIGS/CGS tandem layer, with the prominent peak shift for (1 1 2) reflections was attributed to the individual CIS, CIGS, and CGS phases at 26.76°, 27.15°, and 27.65° diffraction angles, respectively. The morphologies and atomic (at%) composition uniformity onto the surface and along the depth were extensively analyzed with field effect scanning electron microscope (FESEM) attached energy dispersive spectroscopy (EDS) and secondary ion mass spectroscopy (SIMS). The optical properties such as transmittance, reflectance and absorbance were found to improve in the infrared region for all the tandem CIGS layers. Near the fundamental absorption edge, the absorption coefficient was approached to 10{sup 5} cm{sup −1} for CIS/CIGS/CGS tandem layer. The straight-line behavior indicates that the films have a direct band gap. The band gap was found to increase from 1.15 to 1.74 eV with the Ga-grading along the depth of individual CIS, CIGS

Liquid chromatography-dopant-assisted atmospheric pressure photoionization-mass spectrometry: Application to the analysis of aldehydes in atmospheric aerosol particles.

Science.gov (United States)

Ruiz-Jiménez, José; Hautala, Sanna; Parshintsev, Jevgeni; Laitinen, Totti; Hartonen, Kari; Petäjä, Tuukka; Kulmala, Markku; Riekkola, Marja-Liisa

2013-01-01

A complete methodology based on LC-anisole-toluene dopant-assisted atmospheric pressure photoionization-IT-MS was developed for the determination of aldehydes in atmospheric aerosol particles. For the derivatization, ultrasound was used to accelerate the reaction between the target analytes and 2,4-dinitrophenylhydrazine. The developed methodology was validated for three different samples, gas phase, ultrafine (Dp = 30 ± 4 nm; where Dp stands for particle diameter) and all-sized particles, collected on Teflon filters. The method quantitation limits ranged from 5 to 227 pg. The accuracy and the potential matrix effects were evaluated using standard addition methodology. Recoveries ranged between 91.7 and 109.9%, and the repeatability and the reproducibility of the method developed between 0.5 and 8.0% and between 2.9 and 11.1%, respectively. The results obtained by the developed methodology compared to those provided by the previously validated method revealed no statistical differences. The method developed was applied to the determination of aldehydes in 16 atmospheric aerosol samples (30 nm and all-sized samples) collected at the Station for Measuring Forest Ecosystem-Atmosphere Relations II during spring 2011. The mean concentrations of aldehydes, and oxidation products of terpenes were between 0.05 and 82.70 ng/m(3). © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

ALMA Long Baseline Observations of the Dynamical Atmospheres of AGB Stars

Science.gov (United States)

Vlemmings, Wouter

2018-04-01

I will present the current status of ALMA long baseline observations of W Hya, R Leo, R Dor and Mira. We have recently obtained band 4, 6 and 7 observations of the line and continuum emission tracing the temperature and dynamics in their extended atmosphere. Our preliminary analysis confirms our previous detection of a hotspot on W Hya, and reveals unexpected lines in most of the sources, as well as possible fast rotation in the atmopshere of one of the stars. The observations show the unique power of ALMA in observing the extended stellar atmospheres.

Unusual neurological syndrome induced by atmospheric pressure change.

Science.gov (United States)

Ptak, Judy A; Yazinski, Nancy A; Block, Clay A; Buckey, Jay C

2013-05-01

We describe a case of a 46-yr-old female who developed hypertension, tachycardia, dysarthria, and leg weakness provoked by pressure changes associated with flying. Typically during the landing phase of flight, she would feel dizzy and note that she had difficulty with speech and leg weakness. After the flight the leg weakness persisted for several days. The symptoms were mitigated when she took a combined alpha-beta blocker (labetalol) prior to the flight. To determine if these symptoms were related to atmospheric pressure change, she was referred for testing in a hyperbaric chamber. She was exposed to elevated atmospheric pressure (maximum 1.2 ATA) while her heart rate and blood pressure were monitored. Within 1 min she developed tachycardia and hypertension. She also quickly developed slurred speech, left arm and leg weakness, and sensory changes in her left leg. She was returned to sea level pressure and her symptoms gradually improved. A full neurological workup has revealed no explanation for these findings. She has no air collections, cysts, or other anatomic findings that could be sensitive to atmospheric pressure change. The pattern is most consistent with a vascular event stimulated by altitude exposure. This case suggests that atmospheric pressure change can produce neurological symptoms, although the mechanism is unknown.

Ionization Efficiency in the Dayside Martian Upper Atmosphere

Science.gov (United States)

Cui, J.; Wu, X.-S.; Xu, S.-S.; Wang, X.-D.; Wellbrock, A.; Nordheim, T. A.; Cao, Y.-T.; Wang, W.-R.; Sun, W.-Q.; Wu, S.-Q.; Wei, Y.

2018-04-01

Combining the Mars Atmosphere and Volatile Evolution measurements of neutral atmospheric density, solar EUV/X-ray flux, and differential photoelectron intensity made during 240 nominal orbits, we calculate the ionization efficiency, defined as the ratio of the secondary (photoelectron impact) ionization rate to the primary (photon impact) ionization rate, in the dayside Martian upper atmosphere under a range of solar illumination conditions. Both the CO2 and O ionization efficiencies tend to be constant from 160 km up to 250 km, with respective median values of 0.19 ± 0.03 and 0.27 ± 0.04. These values are useful for fast calculation of the ionization rate in the dayside Martian upper atmosphere, without the need to construct photoelectron transport models. No substantial diurnal and solar cycle variations can be identified, except for a marginal trend of reduced ionization efficiency approaching the terminator. These observations are favorably interpreted by a simple scenario with ionization efficiencies, as a first approximation, determined by a comparison between relevant cross sections. Our analysis further reveals a connection between regions with strong crustal magnetic fields and regions with high ionization efficiencies, which are likely indicative of more efficient vertical transport of photoelectrons near magnetic anomalies.

Atmospheric Seasonality as an Exoplanet Biosignature

Science.gov (United States)

Olson, Stephanie L.; Schwieterman, Edward W.; Reinhard, Christopher T.; Ridgwell, Andy; Kane, Stephen R.; Meadows, Victoria S.; Lyons, Timothy W.

2018-05-01

Current investigations of exoplanet biosignatures have focused on static evidence of life, such as the presence of biogenic gases like O2 or CH4. However, the expected diversity of terrestrial planet atmospheres and the likelihood of both “false positives” and “false negatives” for conventional biosignatures motivate exploration of additional life detection strategies, including time-varying signals. Seasonal variation in atmospheric composition is a biologically modulated phenomenon on Earth that may occur elsewhere because it arises naturally from the interplay between the biosphere and time-variable insolation. The search for seasonality as a biosignature would avoid many assumptions about specific metabolisms and provide an opportunity to directly quantify biological fluxes—allowing us to characterize, rather than simply recognize, biospheres on exoplanets. Despite this potential, there have been no comprehensive studies of seasonality as an exoplanet biosignature. Here, we provide a foundation for further studies by reviewing both biological and abiological controls on the magnitude and detectability of seasonality of atmospheric CO2, CH4, O2, and O3 on Earth. We also consider an example of an inhabited world for which atmospheric seasonality may be the most notable expression of its biosphere. We show that life on a low O2 planet like the weakly oxygenated mid-Proterozoic Earth could be fingerprinted by seasonal variation in O3 as revealed in its UV Hartley–Huggins bands. This example highlights the need for UV capabilities in future direct-imaging telescope missions (e.g., LUVOIR/HabEx) and illustrates the diagnostic importance of studying temporal biosignatures for exoplanet life detection/characterization.

Coherence degree of the fundamental Bessel-Gaussian beam in turbulent atmosphere

Science.gov (United States)

Lukin, Igor P.

2017-11-01

In this article the coherence of a fundamental Bessel-Gaussian optical beam in turbulent atmosphere is analyzed. The problem analysis is based on the solution of the equation for the transverse second-order mutual coherence function of a fundamental Bessel-Gaussian optical beam of optical radiation. The behavior of a coherence degree of a fundamental Bessel-Gaussian optical beam depending on parameters of an optical beam and characteristics of turbulent atmosphere is examined. It was revealed that at low levels of fluctuations in turbulent atmosphere the coherence degree of a fundamental Bessel-Gaussian optical beam has the characteristic oscillating appearance. At high levels of fluctuations in turbulent atmosphere the coherence degree of a fundamental Bessel-Gaussian optical beam is described by an one-scale decreasing curve which in process of increase of level of fluctuations on a line of formation of a laser beam becomes closer to the same characteristic of a spherical optical wave.

A comparative study of APLI and APCI in IMS at atmospheric pressure to reveal and explain peak broadening effects by the use of APLI.

Science.gov (United States)

Ihlenborg, Marvin; Raupers, Björn; Gunzer, Frank; Grotemeyer, Jürgen

2015-11-21

The details of the ionization mechanism in atmospheric pressure are still not completely known. In order to obtain further insight into the occurring processes in atmospheric pressure laser ionization (APLI) a comparative study of atmospheric pressure chemical ionization (APCI) and APLI is presented in this paper. This study is carried out using similar experimental condition at atmospheric pressure employing a commercial ion mobility spectrometer (IMS). Two different peak broadening mechanisms can then be assigned, one related to a range of different species generated and detected, and furthermore for the first time a power broadening effect on the signals can be identified.

Atomistic modeling of carbon Cottrell atmospheres in bcc iron

Science.gov (United States)

Veiga, R. G. A.; Perez, M.; Becquart, C. S.; Domain, C.

2013-01-01

Atomistic simulations with an EAM interatomic potential were used to evaluate carbon-dislocation binding energies in bcc iron. These binding energies were then used to calculate the occupation probability of interstitial sites in the vicinity of an edge and a screw dislocation. The saturation concentration due to carbon-carbon interactions was also estimated by atomistic simulations in the dislocation core and taken as an upper limit for carbon concentration in a Cottrell atmosphere. We obtained a maximum concentration of 10 ± 1 at.% C at T = 0 K within a radius of 1 nm from the dislocation lines. The spatial carbon distributions around the line defects revealed that the Cottrell atmosphere associated with an edge dislocation is denser than that around a screw dislocation, in contrast with the predictions of the classical model of Cochardt and colleagues. Moreover, the present Cottrell atmosphere model is in reasonable quantitative accord with the three-dimensional atom probe data available in the literature.

Thermal Band Atmospheric Correction Using Atmospheric Profiles Derived from Global Positioning System Radio Occultation and the Atmospheric Infrared Sounder

Science.gov (United States)

Pagnutti, Mary; Holekamp, Kara; Stewart, Randy; Vaughan, Ronald D.

2006-01-01

This Rapid Prototyping Capability study explores the potential to use atmospheric profiles derived from GPS (Global Positioning System) radio occultation measurements and by AIRS (Atmospheric Infrared Sounder) onboard the Aqua satellite to improve surface temperature retrieval from remotely sensed thermal imagery. This study demonstrates an example of a cross-cutting decision support technology whereby NASA data or models are shown to improve a wide number of observation systems or models. The ability to use one data source to improve others will be critical to the GEOSS (Global Earth Observation System of Systems) where a large number of potentially useful systems will require auxiliary datasets as input for decision support. Atmospheric correction of thermal imagery decouples TOA radiance and separates surface emission from atmospheric emission and absorption. Surface temperature can then be estimated from the surface emission with knowledge of its emissivity. Traditionally, radiosonde sounders or atmospheric models based on radiosonde sounders, such as the NOAA (National Oceanic & Atmospheric Administration) ARL (Air Resources Laboratory) READY (Real-time Environmental Application and Display sYstem), provide the atmospheric profiles required to perform atmospheric correction. Unfortunately, these types of data are too spatially sparse and too infrequently taken. The advent of high accuracy, global coverage, atmospheric data using GPS radio occultation and AIRS may provide a new avenue for filling data input gaps. In this study, AIRS and GPS radio occultation derived atmospheric profiles from the German Aerospace Center CHAMP (CHAllenging Minisatellite Payload), the Argentinean Commission on Space Activities SAC-C (Satellite de Aplicaciones Cientificas-C), and the pair of NASA GRACE (Gravity Recovery and Climate Experiment) satellites are used as input data in atmospheric radiative transport modeling based on the MODTRAN (MODerate resolution atmospheric

Urban atmospheres.

Science.gov (United States)

Gandy, Matthew

2017-07-01

What is an urban atmosphere? How can we differentiate an 'atmosphere' from other facets of urban consciousness and experience? This essay explores some of the wider cultural, political, and philosophical connotations of atmospheres as a focal point for critical reflections on space and subjectivity. The idea of an 'affective atmosphere' as a distinctive kind of mood or shared corporeal phenomenon is considered in relation to recent developments in phenomenology, extended conceptions of agency, and new understandings of materialism. The essay draws in particular on the changing characteristics of air and light to reflect on different forms of sensory experience and their wider cultural and political connotations. The argument highlights some of the tensions and anomalies that permeate contemporary understandings of urban atmospheres.

Atmospheric multidecadal variations in the North Atlantic realm: proxy data, observations, and atmospheric circulation model studies

Directory of Open Access Journals (Sweden)

K. Grosfeld

2007-01-01

Full Text Available We investigate the spatial and temporal characteristics of multidecadal climate variability in the North Atlantic realm, using observational data, proxy data and model results. The dominant pattern of multidecadal variability of SST depicts a monopolar structure in the North Atlantic during the instrumental period with cold (warm phases during 1900–1925 and 1970–1990 (1870–1890 and 1940–1960. Two atmospheric general circulation models of different complexity forced with global SST over the last century show SLP anomaly patterns from the warm and cold phases of the North Atlantic similar to the corresponding observed patterns. The analysis of a sediment core from Cariaco Basin, a coral record from the northern Red Sea, and a long-term sea level pressure (SLP reconstruction reveals that the multidecadal mode of the atmospheric circulation characterizes climate variability also in the pre-industrial era. The analyses of SLP reconstruction and proxy data depict a persistent atmospheric mode at least over the last 300 years, where SLP shows a dipolar structure in response to monopolar North Atlantic SST, in a similar way as the models' responses do. The combined analysis of observational and proxy data with model experiments provides an understanding of multidecadal climate modes during the late Holocene. The related patterns are useful for the interpretation of proxy data in the North Atlantic realm.

Atmospheric Pressure Plasma Treatment for Grey Cotton Knitted Fabric

Directory of Open Access Journals (Sweden)

Chi-wai Kan

2018-01-01

Full Text Available 100% grey cotton knitted fabric contains impurities and yellowness and needs to be prepared for processing to make it suitable for coloration and finishing. Therefore, conventionally 100% grey cotton knitted fabric undergoes a process of scouring and bleaching, which involves the use of large amounts of water and chemicals, in order to remove impurities and yellowness. Due to increased environmental awareness, pursuing a reduction of water and chemicals is a current trend in textile processing. In this study, we explore the possibility of using atmospheric pressure plasma as a dry process to treat 100% grey cotton knitted fabric (single jersey and interlock before processing. Experimental results reveal that atmospheric pressure plasma treatment can effectively remove impurities from 100% grey cotton knitted fabrics and significantly improve its water absorption property. On the other hand, if 100% grey cotton knitted fabrics are pretreated with plasma and then undergo a normal scouring process, the treatment time is reduced. In addition, the surface morphological and chemical changes in plasma-treated fabrics were studied and compared with the conventionally treated fabrics using scanning electron microscope (SEM, Fourier-transform infrared spectroscopy-attenuated total reflection (FTIR-ATR and X-ray photoelectron spectroscopy (XPS. The decrease in carbon content, as shown in XPS, reveal the removal of surface impurities. The oxygen-to-carbon (O/C ratios of the plasma treated knitted fabrics reveal enhanced hydrophilicity.

Atmospheric gravity waves in the Red Sea: a new hotspot

KAUST Repository

Magalhaes, J. M.

2011-02-03

The region of the Middle East around the Red Sea (between 32° E and 44° E longitude and 12° N and 28° N latitude) is a currently undocumented hotspot for atmospheric gravity waves (AGWs). Satellite imagery shows evidence that this region is prone to relatively high occurrence of AGWs compared to other areas in the world, and reveals the spatial characteristics of these waves. The favorable conditions for wave propagation in this region are illustrated with three typical cases of AGWs propagating in the lower troposphere over the sea. Using weakly nonlinear long wave theory and the observed characteristic wavelengths we obtain phase speeds which are consistent with those observed and typical for AGWs, with the Korteweg-de Vries theory performing slightly better than Benjamin-Davis-Acrivos-Ono theory as far as phase speeds are concerned. ERS-SAR and Envisat-ASAR satellite data analysis between 1993 and 2008 reveals signatures consistent with horizontally propagating large-scale internal waves. These signatures cover the entire Red Sea and are more frequently observed between April and September, although they also occur during the rest of the year. The region\\'s (seasonal) propagation conditions for AGWs, based upon average vertical atmospheric stratification profiles suggest that many of the signatures identified in the satellite images are atmospheric internal waves. © Author(s) 2011.

New inorganic (an)ion exchangers with a higher affinity for arsenate and a competitive removal capacity towards fluoride, bromate, bromide, selenate, selenite, arsenite and borate

KAUST Repository

Chubar, Natalia

2011-12-01

Highly selective materials and effective technologies are needed to meet the increasingly stronger drinking water standards for targeted ionic species. Inorganic ion exchangers based on individual and mixed-metal hydrous oxides (or mixed adsorbents that contain inorganic ion exchangers in their composition) are adsorptive materials that are capable of lowering the concentrations of anionic contaminants, such as H 2AsO 4 -, H 3AsO 3, F -, Br -, BrO 3 -, HSeO 4 -, HSeO 3 - and H 3BO 3, to 10 μg/L or less. To achieve a higher selectivity towards arsenate, a new ion exchanger based on Mg-Al hydrous oxides was developed by a novel, cost-effective and environmentally friendly synthesis method via a non-traditional (alkoxide-free) sol-gel approach. The exceptional adsorptive capacity of the Mg-Al hydrous oxides towards H 2AsO 4 - (up to 200 mg[As]/gdw) is due to the high affinity of this sorbent towards arsenate (steep equilibrium isotherms) and its fast adsorption kinetics. Because of the mesoporous (as determined by N 2 adsorption and SEM) and layered (as determined by XRD and FTIR) structure of the ion-exchange material as well as the abundance of anion exchange sites (as determined by XPS and potentiometric titration) on its surface the material demonstrated very competitive (or very high) removal capacity towards other targeted anions, including fluoride, bromide, bromate, selenate, selenite, and borate. © 2011 IWA Publishing.

Atmospheric electricity

CERN Document Server

Chalmers, J Alan

1957-01-01

Atmospheric Electricity brings together numerous studies on various aspects of atmospheric electricity. This book is composed of 13 chapters that cover the main problems in the field, including the maintenance of the negative charge on the earth and the origin of the charges in thunderstorms. After a brief overview of the historical developments of atmospheric electricity, this book goes on dealing with the general principles, results, methods, and the MKS system of the field. The succeeding chapters are devoted to some aspects of electricity in the atmosphere, such as the occurrence and d

Thomson scattering measurements in atmospheric plasma jets

International Nuclear Information System (INIS)

Gregori, G.; Schein, J.; Schwendinger, P.; Kortshagen, U.; Heberlein, J.; Pfender, E.

1999-01-01

Electron temperature and electron density in a dc plasma jet at atmospheric pressure have been obtained using Thomson laser scattering. Measurements performed at various scattering angles have revealed effects that are not accounted for by the standard scattering theory. Differences between the predicted and experimental results suggest that higher order corrections to the theory may be required, and that corrections to the form of the spectral density function may play an important role. copyright 1999 The American Physical Society

Growing Atmospheric Pollution and Its Relation with Occurrences of Natural Hazards in India

Science.gov (United States)

Singh, Ramesh

In the last three decades, multi satellite remote sensing data have revealed increasing atmospheric pollution. The satellite data have shown spatial distribution of fine and coarse atmospheric particles which impact human health, cloud albedo and atmospheric and meteorological parameters. The long range dusts coming over India travel through Arabian Sea and reach to the Bay of Bengal, such long range transport of dust influences atmospheric and ocean parameters, as a result strong coupling exists between land-ocean-atmosphere. Various kind of natural hazards, such as cyclone, algal bloom, cloud burst, excessive rainfall have been observed apart from the intense fog, haze and smog during winter and post monsoon seasons that have serious impacts on human health of people living in the Indo-Gangetic basin. The long range transport of dust and local anthropogenic emissions also reach to the Himalayan region affecting snow and glaciers of Himalaya and accelerating melting of snow and glaciers which is a threat of flooding of rivers originate from Himalayan region.

New insights into the atmospheric mercury cycling in central Antarctica and implications on a continental scale

Directory of Open Access Journals (Sweden)

H. Angot

2016-07-01

Full Text Available Under the framework of the GMOS project (Global Mercury Observation System atmospheric mercury monitoring has been implemented at Concordia Station on the high-altitude Antarctic plateau (75°06′ S, 123°20′ E, 3220 m above sea level. We report here the first year-round measurements of gaseous elemental mercury (Hg(0 in the atmosphere and in snowpack interstitial air on the East Antarctic ice sheet. This unique data set shows evidence of an intense oxidation of atmospheric Hg(0 in summer (24-hour daylight due to the high oxidative capacity of the Antarctic plateau atmosphere in this period of the year. Summertime Hg(0 concentrations exhibited a pronounced daily cycle in ambient air with maximal concentrations around midday. Photochemical reactions and chemical exchange at the air–snow interface were prominent, highlighting the role of the snowpack on the atmospheric mercury cycle. Our observations reveal a 20 to 30 % decrease of atmospheric Hg(0 concentrations from May to mid-August (winter, 24 h darkness. This phenomenon has not been reported elsewhere and possibly results from the dry deposition of Hg(0 onto the snowpack. We also reveal the occurrence of multi-day to weeklong atmospheric Hg(0 depletion events in summer, not associated with depletions of ozone, and likely due to a stagnation of air masses above the plateau triggering an accumulation of oxidants within the shallow boundary layer. Our observations suggest that the inland atmospheric reservoir is depleted in Hg(0 in summer. Due to katabatic winds flowing out from the Antarctic plateau down the steep vertical drops along the coast and according to observations at coastal Antarctic stations, the striking reactivity observed on the plateau most likely influences the cycle of atmospheric mercury on a continental scale.

Investigación de la biotransformación de Se en tejidos de Phaseolus vulgaris L. mediante espectroscopia de absorción de rayos X Investigación de la biotransformación de Se en tejidos de Phaseolus vulgaris L. mediante espectroscopia de absorción de rayos X

Directory of Open Access Journals (Sweden)

Jorge L. Gardea-Torresdey

2012-02-01

Full Text Available   In this investigation, selenate toxicity was evaluated in three varieties of Phaseoulus vulgaris L.: Negro, Peruano, and Flor de Mayo, where this last was identified as the most resistant to selenate. In the Flor de Mayo variety, Se in plant tissues was quantified and X-ray absorption spectroscopy (XAS analysis performed in order to determine the potential selenate biotransformation. Root and stem tissues accumulated up to 1 218 mg Se kg-1 and 101 mg Se kg-1, respectively. XAS results indicated that part of the selenate was biotransformed, as in plant tissues selenate as well as selanide forms were identified. According to these results, Flor de Mayo variety can be classified as a Se secondary accumulator. Also, selenate biotransformation was identified. To our knowledge, this is the first time selenate biotransformation using XAS in this plant species is reported.En este trabajo se evaluó la toxicidad del selenato en tres variedades de frijol (Phaseoulus vulgaris L.: Negro, Peruano y Flor de Mayo. La variedad Flor de Mayo se identificó como la más resistente por lo que en ella se cuantificó el selenio y se determinó la biotransformación del selenato mediante espectroscopia de absorción de rayos X (EAX. La raíz y tallo de esta variedad acumularon hasta 1 218 mg Se kg-1 y 101 mg Se kg-1, respectivamente. Los resultados de EAX indicaron que parte del selenato se biotransformó en los tejidos de la planta, en donde se identificaron las formas selenato y selenuro. De acuerdo a estos resultados, esta variedad de P. vulgaris puede ser clasificada como una acumuladora secundaria de selenio; por otro lado se comprobó la biotransformación del selenato usando EAX lo cual, hasta donde sabemos, no ha sido previamente reportada en la literatura.

Atmospheric Electricity

Science.gov (United States)

Aplin, Karen; Fischer, Georg

2018-02-01

Electricity occurs in atmospheres across the Solar System planets and beyond, spanning spectacular lightning displays in clouds of water or dust, to more subtle effects of charge and electric fields. On Earth, lightning is likely to have existed for a long time, based on evidence from fossilized lightning strikes in ancient rocks, but observations of planetary lightning are necessarily much more recent. The generation and observations of lightning and other atmospheric electrical processes, both from within-atmosphere measurements, and spacecraft remote sensing, can be readily studied using a comparative planetology approach, with Earth as a model. All atmospheres contain charged molecules, electrons, and/or molecular clusters created by ionization from cosmic rays and other processes, which may affect an atmosphere's energy balance both through aerosol and cloud formation, and direct absorption of radiation. Several planets are anticipated to host a "global electric circuit" by analogy with the circuit occurring on Earth, where thunderstorms drive current of ions or electrons through weakly conductive parts of the atmosphere. This current flow may further modulate an atmosphere's radiative properties through cloud and aerosol effects. Lightning could potentially have implications for life through its effects on atmospheric chemistry and particle transport. It has been observed on many of the Solar System planets (Earth, Jupiter, Saturn, Uranus, and Neptune) and it may also be present on Venus and Mars. On Earth, Jupiter, and Saturn, lightning is thought to be generated in deep water and ice clouds, but discharges can be generated in dust, as for terrestrial volcanic lightning, and on Mars. Other, less well-understood mechanisms causing discharges in non-water clouds also seem likely. The discovery of thousands of exoplanets has recently led to a range of further exotic possibilities for atmospheric electricity, though lightning detection beyond our Solar System

Achievement report for fiscal 1991 on Sunshine Program-entrusted research and development. Research and development of high-efficiency solar cells (Research on forbidden band width optimization); 1991 nendo kokoritsu taiyo denchi no kenkyu kaihatsu seika hokokusho. Kinsei taifuku no saitekika no kenkyu

Energy Technology Data Exchange (ETDEWEB)

NONE

1992-03-01

Research is conducted on film formation technologies etc. for the chalcopyritic compound semiconductors represented by CuInSe{sub 2} which is the most excellent of the materials for thin-film solar cells. As for the development of a encapsulated selenization method, research is conducted on an In formation method, temperature program for heat treatment, and Cu-In alloy film selenization, and then a CuInSe{sub 2} film less to suffer phase separation is obtained. In the development of a vaporized selenization method, the reactor tube and the temperature program are improved, and this results in a CuInSe{sub 2} film excellent in homogeneity. As for the evaluation of CuInSe{sub 2} film, photoluminescence is measured using a solid-phase selenized film, vapor-phase selenized film, and 3-source vapor-deposited film, and the result shows that photoluminescence-assisted CuInSe{sub 2} film evaluation is quite promising. In the development of ZnO film formation technologies, the MOCVD (metalorganic chemical vapor deposition) technology is almost complete, and film formation on a 10cm-square substrate is now practical. (NEDO)

Resistance, accumulation and transformation of selenium by the cyanobacterium Synechocystis sp. PCC 6803 after exposure to inorganic SeVI or SeIV

International Nuclear Information System (INIS)

Gouget, B.; Avoscan, L.; Collins, R.; Carriere, M.; Sarret, G.

2005-01-01

Our purpose was to investigate the ability of Synechocystis sp. PCC 6803, a photosynthetic prokaryote isolated from fresh water, to resist, incorporate and reduce the oxidized forms of selenium including selenite and selenate, the major selenium species present in aquatic systems. Selenium speciation and the chemical intermediates during selenium transformation were determined by X-ray absorption near edge structure (XANES) spectroscopy. The possible internalisation pathways involving selenium and the metabolic fate of selenate and selenite were examined. Selenate metabolism seemed to proceed via the sulfate reduction pathway resulting in the formation of the R-Se-H, R-Se-R and R-Se-Se-R species. The transformation of selenate to toxic amino acids may explain the high sensitivity of Synechocystis to selenate. Several mechanisms of selenium reduction seem to complete during selenite assimilation. A specific mechanism may transform internalised selenite into selenide and, subsequently induce the biosynthesis of selenoproteins. A non-specific mechanism may interfere with thiols, such as glutathione in the cell cytoplasm, or with proteins in the periplasm of the bacteria, notably thioredoxins. Several hypotheses concerning the complex transformation of selenium in Synechocystis could therefore be proposed. (orig.)

Atmospheric dayglow diagnostics involving the O2(b-X) Atmospheric band emission: Global Oxygen and Temperature (GOAT) mapping

Science.gov (United States)

Slanger, T. G.; Pejaković, D. A.; Kostko, O.; Matsiev, D.; Kalogerakis, K. S.

2017-03-01

The terrestrial dayglow displays prominent emission features from the 0-0 and 1-1 bands of the O2 Atmospheric band system in the 760-780 nm region. We present an analysis of observations in this wavelength region recorded by the Space Shuttle during the Arizona Airglow Experiment. A major conclusion is that the dominant product of O(1D) + O2 energy transfer is O2(b, v = 1), a result that corroborates our previous laboratory studies. Moreover, critical to the interpretation of dayglow is the possible interference by N2 and N2+ bands in the 760-780 nm region, where the single-most important component is the N2 1PG 3-1 band that overlaps with the O2(b-X) 0-0 band. When present, this background must be accounted for to reveal the O2(b-X) 0-0 and 1-1 bands for altitudes at which the O2 and N2/N2+ emissions coincide. Finally, we exploit the very different collisional behavior of the two lowest O2(b) vibrational levels to outline a remote sensing technique that provides information on Atmospheric composition and temperature from space-based observations of the 0-0 and 1-1 O2 atmospheric bands.

The role of ammonia in the chemistry of atmospheric aerosols

International Nuclear Information System (INIS)

Brosset, C.

1979-01-01

Data is presented on the concentrations of hydrogen and ammonium ions in aerosol samples taken under various meteorological conditions in different areas of Sweden, and implications for the atmospheric chemistry of aerosols are discussed. Particle compositions at coastal and inland stations were determined during situations when particle concentrations increased as much as a hundred times due to atmospheric transport from Europe or air movements from the east or west. Analysis of particle compositions during both types of particle episodes reveals variations in the H(+)/NH4(+) ratio which indicate that particles present over agricultural areas take up ammonia from the ground and release it over a forest district with acid lakes. The ratio is found to be dependent on the atmospheric partial pressure of ammonia at equilibrium, with the flow of ammonia to or from the ground and transport conditions also likely to influence the ratio

Atmospheric CO2 Observations Reveal Strong Correlation Between Regional Net Biospheric Carbon Uptake and Solar-Induced Chlorophyll Fluorescence

Science.gov (United States)

Shiga, Yoichi P.; Tadić, Jovan M.; Qiu, Xuemei; Yadav, Vineet; Andrews, Arlyn E.; Berry, Joseph A.; Michalak, Anna M.

2018-01-01

Recent studies have shown the promise of remotely sensed solar-induced chlorophyll fluorescence (SIF) in informing terrestrial carbon exchange, but analyses have been limited to either plot level ( 1 km2) or hemispheric/global ( 108 km2) scales due to the lack of a direct measure of carbon exchange at intermediate scales. Here we use a network of atmospheric CO2 observations over North America to explore the value of SIF for informing net ecosystem exchange (NEE) at regional scales. We find that SIF explains space-time NEE patterns at regional ( 100 km2) scales better than a variety of other vegetation and climate indicators. We further show that incorporating SIF into an atmospheric inversion leads to a spatial redistribution of NEE estimates over North America, with more uptake attributed to agricultural regions and less to needleleaf forests. Our results highlight the synergy of ground-based and spaceborne carbon cycle observations.

Oscillations of stellar extinction caused by disturbances in the Earth's atmosphere

International Nuclear Information System (INIS)

Clarke, D.

1980-01-01

Photometry of bright stars has revealed the possible presence of short period oscillations on the extinction by the Earth's atmosphere. From the colour dependence of the observed effects, it is suggested that the waves affect the aerosol contribution to the extinction more than the contribution by air molecules. The size of the effects presents a challenge to pursuing stellar photometry to accuracies of the order of 0.001 mag. The effects have parallels to the recently discovered brightness oscillations in the daytime sky which have been ascribed to buoyancy or gravity waves in the atmosphere. (author)

Atmospheric Habitable Zones in Y Dwarf Atmospheres

Energy Technology Data Exchange (ETDEWEB)

Yates, Jack S.; Palmer, Paul I. [School of GeoSciences, University of Edinburgh (United Kingdom); Biller, Beth; Cockell, Charles S., E-mail: j.s.yates@ed.ac.uk [Centre for Exoplanet Science, University of Edinburgh (United Kingdom)

2017-02-20

We use a simple organism lifecycle model to explore the viability of an atmospheric habitable zone (AHZ), with temperatures that could support Earth-centric life, which sits above an environment that does not support life. To illustrate our model, we use a cool Y dwarf atmosphere, such as WISE J085510.83–0714442.5, whose 4.5–5.2 μ m spectrum shows absorption features consistent with water vapor and clouds. We allow organisms to adapt to their atmospheric environment (described by temperature, convection, and gravity) by adopting different growth strategies that maximize their chance of survival and proliferation. We assume a constant upward vertical velocity through the AHZ. We found that the organism growth strategy is most sensitive to the magnitude of the atmospheric convection. Stronger convection supports the evolution of more massive organisms. For a purely radiative environment, we find that evolved organisms have a mass that is an order of magnitude smaller than terrestrial microbes, thereby defining a dynamical constraint on the dimensions of life that an AHZ can support. Based on a previously defined statistical approach, we infer that there are of the order of 10{sup 9} cool Y brown dwarfs in the Milky Way, and likely a few tens of these objects are within 10 pc from Earth. Our work also has implications for exploring life in the atmospheres of temperate gas giants. Consideration of the habitable volumes in planetary atmospheres significantly increases the volume of habitable space in the galaxy.

Observations of atmospheric ammonia from TANSO-FTS/GOSAT

Science.gov (United States)

Someya, Yu; Imasu, Ryoichi; Saitoh, Naoko; Shiomi, Kei

2017-04-01

Atmospheric ammonia has large impacts on the nitrogen cycles or atmospheric environment such as nucleation of PM2.5 particles. It is reported that ammonia in the atmosphere has been increasing rapidly with the growth of population globally and this trend must continue in the future. Satellite observation is an effective approach to get to know the global perspectives of the gas. Atmospheric ammonia is observable using the thermal infrared (TIR) spectra, and IASI, TES and CrIS had been revealed those distributions. GOSAT also has TIR band including the ammonia absorption bands. GOSAT has the shorter revisit cycle than that of the other hyper-spectral TIR sounders mentioned above, therefore, the shorter time-scale events can be represented. In addition to the importance of the impacts of ammonia itself, the concentration ratio between ammonia and the other trace gases such as CO which is one of the main targets of the GOSAT-2 project is useful as the indicator of their emission sources. In this study, we introduce an algorithm to retrieve the column amount of atmospheric ammonia based on non-linear optimal estimation (Rogers, 2000) from GOSAT spectra in the ammonia absorption band between 960 - 970 cm-1. Temperature and water vapor profiles are estimated in advance of the ammonia retrieval. The preliminary results showed significant high concentrations of ammonia in the Northern India and the Eastern China as pointed out in the previous researches. We will discuss the global distribution of ammonia in the presentation.

Volatility of 210Po in airborne dusts in an atmosphere of nitrogen

International Nuclear Information System (INIS)

Abe, Michiko; Abe, Siro; Ikeda, Nagao.

1976-01-01

Volatilization behavior of 210 Po contained in airborne dusts in the temperature range of 200 - 800 0 C was investigated in an atmosphere of nitrogen. It was revealed that the volatilization of 210 Po in airborne dusts in an atmosphere of nitrogen as a function of temperature can be expressed in a stairlike shape with two steps. This tendency is similar to the previous results obtained in air. The previous and present data may suggest that 210 Po in airborne dusts consists of two or more different kinds of chemical species. (auth.)

Observations of linear dependence between sulfate and nitrate in atmospheric particles

Science.gov (United States)

Kong, Lingdong; Yang, Yiwei; Zhang, Shuanqin; Zhao, Xi; Du, Huanhuan; Fu, Hongbo; Zhang, Shicheng; Cheng, Tiantao; Yang, Xin; Chen, Jianmin; Wu, Dui; Shen, Jiandong; Hong, Shengmao; Jiao, Li

2014-01-01

Hourly measurements of water-soluble inorganic ionic species in ambient atmospheric particles were conducted at Shanghai, Hangzhou, and Guangzhou sampling sites in China during the period of 2009-2011. The relation between sulfate and nitrate in particulate matter (PM10 and PM2.5) was examined based on these measurements. Results showed that the mass fraction of sulfate was strongly negatively correlated with that of nitrate in atmospheric particles on most of the sampling days, especially when sulfate and nitrate made up the vast majority of the total soluble anions and cations (Na+, K+, Ca2+, and Mg2+) made a small contribution to the total water-soluble ions, revealing that the formation mechanisms of sulfate and nitrate in the atmosphere are highly correlated, and there exists a significant negative correlation trend between sulfate and nitrate mass fractions in the atmospheric particles. We found that local meteorological conditions presented opposite influences on the mass fractions of sulfate and nitrate. Further analysis indicated that the two mass fractions were modulated by the neutralizing level of atmospheric aerosols, and the negative correlation could be found in acidic atmospheric particles. Strong negative correlation was usually observed on clear days, hazy days, foggy days, and respirable particulate air pollution days, whereas poor negative correlation was often observed during cloud, rain, snow, dust storm, and suspended dust events. The results can help to better understand the formation mechanisms of atmospheric sulfate and nitrate during air pollution episodes and to better explain field results of atmospheric chemistry concerning sulfate and nitrate.

Atmospheric chemistry and climate

OpenAIRE

Satheesh, SK

2012-01-01

Atmospheric chemistry is a branch of atmospheric science where major focus is the composition of the Earth's atmosphere. Knowledge of atmospheric composition is essential due to its interaction with (solar and terrestrial) radiation and interactions of atmospheric species (gaseous and particulate matter) with living organisms. Since atmospheric chemistry covers a vast range of topics, in this article the focus is on the chemistry of atmospheric aerosols with special emphasis on the Indian reg...

Determination of the Atmospheric Neutrino Fluxes from Atmospheric Neutrino Data

NARCIS (Netherlands)

Gonzalez-Garcia, M. C.; Maltoni, M.; Rojo, J.

2006-01-01

The precise knowledge of the atmospheric neutrino fluxes is a key ingredient in the interpretation of the results from any atmospheric neutrino experiment. In the standard atmospheric neutrino data analysis, these fluxes are theoretical inputs obtained from sophisticated numerical calculations based

Selenium biofortification in radish enhances nutritional quality via accumulation of methyl-selenocysteine and promotion of transcripts and metabolites related to glucosinolates, phenolics and amino acids

Directory of Open Access Journals (Sweden)

Michela Schiavon

2016-09-01

Full Text Available Two selenium (Se fertilization methods were tested for their effects on levels of anticarcinogenic selenocompounds in radish (Raphanus sativus, as well as other nutraceuticals. First, radish was grown on soil and foliar selenate applied 7d before harvest at 0, 5, 10 and 20 mg Se per plant. Selenium levels were up to 1,200 mg Se/kg DW in leaves and 120 mg Se/kg DW in roots. The thiols cysteine and glutathione were present at 2-3 fold higher levels in roots of Se treated plants, and total glucosinolate levels were 35% higher, due to increases in glucoraphanin. The only seleno-aminoacid detected in Se treated plants was Se-methyl-SeCys (100 mg/kg FW in leaves, 33 mg/kg FW in roots. The levels of phenolic aminoacids increased with selenate treatment, as did root total nitrogen and protein content, while the level of several polyphenols decreased. Second, radish was grown in hydroponics and supplied with 0, 5, 10, 20, or 40 microM selenate for one week. Selenate treatment led to a 20-30% increase in biomass. Selenium concentration was 242 mg Se/kg DW in leaves and 85 mg Se/kg DW in roots. Cysteine levels decreased with Se in leaves but increased in roots; glutatione levels decreased in both. Total glucosinolate levels in leaves decreased with Se treatment due to repression of genes involved in glucosinolates metabolism. Se-methyl-SeCys concentration ranged from 7-15 mg/kg FW. Aminoacid concentration increased with Se treatment in leaves but decreased in roots. Roots of Se treated plants contained elevated transcript levels of sulfate transporters (Sultr and ATP sulfurylase, a key enzyme of S/Se assimilation. No effects on polyphenols were observed. In conclusion, Se biofortification of radish roots may be achieved via foliar spray or hydroponic supply. One to ten radishes could fulfill the daily human requirement (70 microg after a single foliar spray of 5 mg selenate per plant or one week of 5-10 microM selenate supply in hydroponics. The radishes

Direct and indirect atmospheric deposition of PCBs to the Delaware River watershed.

Science.gov (United States)

Totten, Lisa A; Panangadan, Maya; Eisenreich, Steven J; Cavallo, Gregory J; Fikslin, Thomas J

2006-04-01

Atmospheric deposition can be an important source of PCBs to aquatic ecosystems. To develop the total maximum daily load (TMDL) for polychlorinated biphenyls (PCBs) for the tidal Delaware River (water-quality Zones 2-5), estimates of the loading of PCBs to the river from atmospheric deposition were generated from seven air-monitoring sites along the river. This paper presents the atmospheric PCB data from these sites, estimates direct atmospheric deposition fluxes, and assesses the importance of atmospheric deposition relative to other sources of PCBs to the river. Also, the relationship between indirect atmospheric deposition and PCB loads from minor tributaries to the Delaware River is discussed. Data from these sites revealed high atmospheric PCB concentrations in the Philadelphia/Camden urban area and lower regional background concentrations in the more remote areas. Wet, dry particle, and gaseous absorption deposition are estimated to contribute about 0.6, 1.8, and 6.5 kg year-(-1) sigmaPCBs to the River, respectively, exceeding the TMDL of 0.139 kg year(-1) by more than an order of magnitude. Penta-PCB watershed fluxes were obtained by dividing the tributary loads by the watershed area. The lowest of these watershed fluxes are less than approximately 1 ng m(-2) day(-1) for penta-PCB and probably indicates pristine watersheds in which PCB loads are dominated by atmospheric deposition. In these watersheds, the pass-through efficiency of PCBs is estimated to be on the order of 1%.

GCM simulations of cold dry Snowball Earth atmospheres

Science.gov (United States)

Voigt, A.; Held, I.; Marotzke, J.

2009-12-01

We use the full-physics atmospheric general circulation model ECHAM5 to investigate cold and virtually dry Snowball Earth atmospheres. These result from specifying sea ice as the surface boundary condition everywhere, corresponding to a frozen aquaplanet, while keeping total solar irradiance at its present-day value of 1365 Wm-2 and setting atmospheric carbon dioxide to 300 ppmv. Here, we present four simulations corresponding to the four possible combinations of enabled or disabled diurnal and seasonal cycles. The aim of this study is twofold. First, we focus on the zonal-mean circulation of Snowball Earth atmospheres, which, due to missing moisture, might constitute an ideal though yet unexplored testbed for theories of atmospheric dynamics. Second, we investigate tropical surface temperatures with an emphasis on the impact of the diurnal and seasonal cycles. This will indicate whether the presence of the diurnal or seasonal cycle would facilitate or anticipate the escape from Snowball Earth conditions when total solar irradiance or atmospheric CO2 levels were increased. The dynamics of the tropical circulation in Snowball Earth atmospheres differs substantially from that in the modern atmosphere. The analysis of the mean zonal momentum budget reveals that the mean flow meridional advection of absolute vorticity is primarily balanced by vertical diffusion of zonal momentum. The contribution of eddies is found to be even smaller than the contribution of mean flow vertical advection of zonal momentum, the latter being usually neglected in theories for the Hadley circulation, at least in its upper tropospheric branch. Suppressing vertical diffusion of horizontal momentum above 850 hPa leads to a stronger Hadley circulation. This behaviour cannot be understood from axisymmetric models of the atmosphere, nor idealized atmospheric general circulation models, which both predict a weakening of the Hadley circulation when the vertical viscosity is decreased globally. We

Direct Measure of Radiative and Dynamical Properties of an Exoplanet Atmosphere

Science.gov (United States)

de Wit, Julien; Lewis, Nikole K.; Langton, Jonathan; Laughlin, Gregory; Deming, Drake; Batygin, Konstantin; Fortney, Jonathan J.

2016-04-01

Two decades after the discovery of 51 Peg b, the formation processes and atmospheres of short-period gas giants remain poorly understood. Observations of eccentric systems provide key insights on those topics as they can illuminate how a planet’s atmosphere responds to changes in incident flux. We report here the analysis of multi-day multi-channel photometry of the eccentric (e∼ 0.93) hot Jupiter HD 80606 b obtained with the Spitzer Space Telescope. The planet’s extreme eccentricity combined with the long coverage and exquisite precision of new periastron-passage observations allow us to break the degeneracy between the radiative and dynamical timescales of HD 80606 b’s atmosphere and constrain its global thermal response. Our analysis reveals that the atmospheric layers probed heat rapidly (∼4 hr radiative timescale) from \\lt 500 to 1400 K as they absorb ∼ 20% of the incoming stellar flux during the periastron passage, while the planet’s rotation period is {93}-35+85 hr, which exceeds the predicted pseudo-synchronous period (40 hr).

Atmospheric stability and atmospheric circulation in Athens, Greece

International Nuclear Information System (INIS)

Synodinou, B.M.; Petrakis, M.; Kassomenos, P.; Lykoudis, S.

1996-01-01

In the evaluation and study of atmospheric pollution reference is always made to the stability criteria. These criteria, usually represented as functions of different meteorological data such as wind speed and direction, temperature, solar radiation, etc., play a very important role in the investigation of different parameters that affect the build up of pollution episodes mainly in urban areas. In this paper an attempt is made to evaluate the atmospheric stability criteria based on measurements obtained from two locations in and nearby Athens. The atmospheric stability is then examined along with the other meteorological parameters

Sampling of Atmospheric Precipitation and Deposits for Analysis of Atmospheric Pollution

OpenAIRE

Skarżyńska, K.; Polkowska, Ż; Namieśnik, J.

2006-01-01

This paper reviews techniques and equipment for collecting precipitation samples from the atmosphere (fog and cloud water) and from atmospheric deposits (dew, hoarfrost, and rime) that are suitable for the evaluation of atmospheric pollution. It discusses the storage and preparation of samples for analysis and also presents bibliographic information on the concentration ranges of inorganic and organic compounds in the precipitation and atmospheric deposit samples.

Surface modification of nanofibrillated cellulose films by atmospheric pressure dielectric barrier discharge

DEFF Research Database (Denmark)

Siró, Istvan; Kusano, Yukihiro; Norrman, Kion

2013-01-01

of atmospheric pressure plasma treatment, the water contact angle of NFC films increased and the values were comparable with those of PLA films. On the other hand, surface chemical characterization revealed inhomogeneity of the plasma treatment and limited improvement in adhesion between NFC and PLA films...

Atmosphere Impact Losses

Science.gov (United States)

Schlichting, Hilke E.; Mukhopadhyay, Sujoy

2018-02-01

Determining the origin of volatiles on terrestrial planets and quantifying atmospheric loss during planet formation is crucial for understanding the history and evolution of planetary atmospheres. Using geochemical observations of noble gases and major volatiles we determine what the present day inventory of volatiles tells us about the sources, the accretion process and the early differentiation of the Earth. We further quantify the key volatile loss mechanisms and the atmospheric loss history during Earth's formation. Volatiles were accreted throughout the Earth's formation, but Earth's early accretion history was volatile poor. Although nebular Ne and possible H in the deep mantle might be a fingerprint of this early accretion, most of the mantle does not remember this signature implying that volatile loss occurred during accretion. Present day geochemistry of volatiles shows no evidence of hydrodynamic escape as the isotopic compositions of most volatiles are chondritic. This suggests that atmospheric loss generated by impacts played a major role during Earth's formation. While many of the volatiles have chondritic isotopic ratios, their relative abundances are certainly not chondritic again suggesting volatile loss tied to impacts. Geochemical evidence of atmospheric loss comes from the {}3He/{}^{22}Ne, halogen ratios (e.g., F/Cl) and low H/N ratios. In addition, the geochemical ratios indicate that most of the water could have been delivered prior to the Moon forming impact and that the Moon forming impact did not drive off the ocean. Given the importance of impacts in determining the volatile budget of the Earth we examine the contributions to atmospheric loss from both small and large impacts. We find that atmospheric mass loss due to impacts can be characterized into three different regimes: 1) Giant Impacts, that create a strong shock transversing the whole planet and that can lead to atmospheric loss globally. 2) Large enough impactors (m_{cap} ≳ √{2

The signature of atmospheric tides in sub-daily variations of Earth rotation as unveiled by globally-gridded atmospheric angular momentum functions

Science.gov (United States)

Schindelegger, M.; Böhm, J.; Salstein, D. A.; Schuh, H.

2012-12-01

Thermally-driven atmospheric tides provide a small but distinct contribution to shortperiod variations of Earth rotation parameters (ERP). The effect of diurnal and semi-diurnal tides, commonly denoted as S1 and S2, respectively, is in the range of 2 - 10 uas for polar motion and 2 - 10 uas for changes in length-of-day (LOD). Even though ocean tides represent a much more dominant driving agent for ERP fluctuations at short time scales, high-frequency atmospheric effects are non-negligible, particularly given the prospective measurement accuracy of space geodetic techniques. However, previous studies, such as Brzezinski et al. (2002), de Viron et al. (2005) or Schindelegger et al. (2011), have been noticeably inconclusive on the exact amplitude and phase values of S1 and S2 atmospheric excitation signals. This study aims at shedding light on the origin of these uncertainties with respect to the axial component of Earth's rotation vector by investigating times series of atmospheric angular momentum (AAM) functions that are given on global grids and computed from three-hourly meteorological data of the European Centre for Medium-Range Weather Forecasts (ECMWF). The signature of diurnal and semi-diurnal atmospheric tides is clearly visible in the gridded axial AAM functions, revealing a distinct spatial and temporal phase difference between pressure and wind tidal constituents of about ± π. It is shown that due to this counterbalance and the explicit axisymmetric spatial structure of S1 and S2, the net effect in sub-diurnal AAM (which is calculated from the global sum of gridded AAM functions) is always a small quantity, particularly sensitive to minor differences between the analysis fields of numerical weather models.

Revealing skill of the MiKlip decadal prediction system by three-dimensional probabilistic evaluation

Directory of Open Access Journals (Sweden)

Sophie Stolzenberger

2016-12-01

Full Text Available Decadal climate predictions and their verification are part of ongoing research. This article studies different methods applied to decadal hindcasts of three-dimensional atmospheric variables to evaluate the MiKlip (Mittelfristige Klimaprognosen prediction system. Variables such as upper air temperature are tight to the core of the prediction system and hence help to reveal its power and deficiencies. The verification uses both, necessary and sufficient probabilistic measures. We analyze annual and multi-year averages of air temperature and geopotential height and the parametrized quantity net water flux at the ocean surface, the so-called freshwater flux, also known as E‑P (evaporation minus precipitation, as an important variable for atmosphere-ocean coupling. The model data stem from various versions of the MiKlip prediction system and constitute different sets of ensemble hindcasts covering 1979–2012. The results reveal that the freshwater flux is far more sensitive to model deficiencies than the basic dynamical variables and the predictability decays much earlier with prediction lead time. Initializing the atmospheric component is more important for the predictability than the difference in resolution between two model versions. The combined initialization of atmosphere and ocean has the effect of increasing the predictability in the inner tropics from 1 to 2 years compared to the ocean only initialization. For prediction year 7–10, the hindcasts are still closer to each other than to the uninitialized historical runs indicating that the prediction system is still influenced by the initial conditions. The skill for prediction year 7–10 is, however, only marginally larger than the skill of the uninitialized ensemble. The three-dimensional skill analysis reveals a clear indication of a mid-tropospheric temperature error developing in the tropical Pacific area.

The Voltammetric Analysis of Selenium Electrodeposition from H2SeO3 Solution on Gold Electrode

OpenAIRE

Kowalik R.

2015-01-01

The different voltammetry techniques were applied to understand the process of selenium deposition from sulfate solution on gold polycrystalline electrode. By applying the cycling voltammetry with different scan limits as well as the chronoamper-ometry combined with the cathodic and anodic linear stripping voltammetry, the different stages of the deposition of selenium were revealed. It was found that the process of reduction of selenous acid on gold surface exhibits a multistage character. T...

Selection of superior salt/boron tolerant Stanleya pinnata genotypes and quantification of their selenium phytoremediation abilities in drainage sediment.

Science.gov (United States)

The semi-metallic mineral Se, a naturally-occurring trace element, is primarily found as selenate originating from sedimentary and shale rock formations, e.g., in the western side of the San Joaquin Valley of central California (WSJV). Because selenate-Se is water soluble, bioavailable and biomagnif...

Correlative Cryo-Tem Cryo-Stxm and Cryo-Shxm Investigation of Selenium Bioreduction in a Contaminated Aquifer

Science.gov (United States)

Fakra, S.; Luef, B.; Tyliszczak, T.; Castelle, C. J.; Mullin, S. W.; Hug, L. A.; Williams, K. H.; Marcus, M.; Banfield, J. F.

2015-12-01

Accurate mapping of the composition and ultrastructure of minerals and cells is key to understanding biogeochemical process in contaminated environments. Here we developed two apparatus that allow correlation of cryogenic transmission electron microscopy (TEM), synchrotron hard X-ray microprobe (SHXM) and scanning transmission X-ray microscopy (STXM) datasets. These cryogenic methods enabled precise determination of the distribution, valence state and structure of selenium in intact biofilms sampled during a biostimulation experiment in a contaminated aquifer near Rifle, CO, USA. Results were replicated in the laboratory via anaerobic selenate-reducing enrichment cultures. 16S rRNA analyses of field-derived biofilm indicated the dominance of Betaproteobacteria from the Comamonadaceae family, and uncultivated members of the Simplicispira genus. The major product in field and culture-derived biofilms consists of ~25-300 nm red amorphous Se0 aggregates of colloidal nanoparticles. Correlative analyses of the cultures provided direct evidence for microbial dissimilatory reduction of Se(VI) to Se(IV) to Se0. X-ray diffraction and Se K-edge extended X-ray absorption fine structure spectroscopy revealed red amorphous Se0 with a first shell Se-Se interatomic distance of 2.339 ± 0.003 Å. STXM showed that these aggregates are strongly associated with a protein-rich biofilm matrix containing acidic polysaccharides. From Rifle groundwater, we isolated a strain that shares 98.9% 16S rRNA gene sequence identity with Dechloromonas aromatica RCB and grows anaerobically by oxidizing acetate and reducing selenate. We refer to this isolate as Dechloromonas selenatis strain RGW99. 3D cryo-electron tomography showed that Se0 particles do not form inside the cytoplasm but rather originate in the cell membrane. The end product of selenate reduction by D. selenatis is 240 ± 66 nm diameter red amorphous Se0 colloidal aggregates. This product was found to be stable for months. Overall

Global Hawk dropsonde observations of the Arctic atmosphere obtained during the Winter Storms and Pacific Atmospheric Rivers (WISPAR field campaign

Directory of Open Access Journals (Sweden)

J. M. Intrieri

2014-11-01

Full Text Available In February and March of 2011, the Global Hawk unmanned aircraft system (UAS was deployed over the Pacific Ocean and the Arctic during the Winter Storms and Pacific Atmospheric Rivers (WISPAR field campaign. The WISPAR science missions were designed to (1 mprove our understanding of Pacific weather systems and the polar atmosphere; (2 evaluate operational use of unmanned aircraft for investigating these atmospheric events; and (3 demonstrate operational and research applications of a UAS dropsonde system at high latitudes. Dropsondes deployed from the Global Hawk successfully obtained high-resolution profiles of temperature, pressure, humidity, and wind information between the stratosphere and surface. The 35 m wingspan Global Hawk, which can soar for ~ 31 h at altitudes up to ~ 20 km, was remotely operated from NASA's Dryden Flight Research Center at Edwards Air Force Base (AFB in California. During the 25 h polar flight on 9–10 March 2011, the Global Hawk released 35 sondes between the North Slope of Alaska and 85° N latitude, marking the first UAS Arctic dropsonde mission of its kind. The polar flight transected an unusually cold polar vortex, notable for an associated record-level Arctic ozone loss, and documented polar boundary layer variations over a sizable ocean–ice lead feature. Comparison of dropsonde observations with atmospheric reanalyses reveal that, for this day, large-scale structures such as the polar vortex and air masses are captured by the reanalyses, while smaller-scale features, including low-level jets and inversion depths, are mischaracterized. The successful Arctic dropsonde deployment demonstrates the capability of the Global Hawk to conduct operations in harsh, remote regions. The limited comparison with other measurements and reanalyses highlights the potential value of Arctic atmospheric dropsonde observations where routine in situ measurements are practically nonexistent.

Microstructural evolution of all-wet-processed CIGS films using Raman spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Choi, Hee Soo; Choi, Eunmi; Kim, Areum; Pyo, Sung Gyu [School of Integrative Engineering, Chung-Ang University, 221 Heukseok-Dong, Seoul, 156-756 (Korea, Republic of); Yoon, Sung Pil [Fuel Cell Research Center, Korea Institute of Science and Technology, Seoul, 136-791 (Korea, Republic of)

2014-08-15

We report a wet process deposition in order to identify a cost-effective processing scheme for CuIn{sub 1-x}Ga{sub x}Se{sub 2} (CIGS) layers on molybdenum/soda lime glass substrates from a Cu-In-Ga precursor solution. We employed a spin coater at various settings to evaluate the uniformity of the resulting CIGS solar cell layer. After the CIGS precursor film was deposited, we applied a selenization process. In the selenization process, we used a controlled temperature RTA system and compared it to a noncontrolled temperature system. We investigated the morphological properties for different selenization temperature treatments. We used Raman mapping to detect binary compounds and found the binary compound effect on the film. Raman mapping results show that the density of the binary compound in the CIGS layer increased with selenization temperature, and at 600 C, the density of the binary compounds was highest. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Decadal atmosphere-ocean variations in the Pacific

Science.gov (United States)

Trenberth, Kevin E.; Hurrell, James W.

1994-03-01

Considerable evidence has emerged of a substantial decade-long change in the north Pacific atmosphere and ocean lasting from about 1976 to 1988. Observed significant changes in the atmospheric circulation throughout the troposphere revealed a deeper and eastward shifted Aleutian low pressure system in the winter half year which advected warmer and moister air along the west coast of North America and into Alaska and colder air over the north Pacific. Consequently, there were increases in temperatures and sea surface temperatures (SSTs) along the west coast of North America and Alaska but decreases in SSTs over the central north Pacific, as well as changes in coastal rainfall and streamflow, and decreases in sea ice in the Bering Sea. Associated changes occurred in the surface wind stress, and, by inference, in the Sverdrup transport in the north Pacific Ocean. Changes in the monthly mean flow were accompanied by a southward shift in the storm tracks and associated synoptic eddy activity and in the surface ocean sensible and latent heat fluxes. In addition to the changes in the physical environment, the deeper Aleutian low increased the nutrient supply as seen through increases in total chlorophyll in the water column, phytoplankton and zooplankton. These changes, along with the altered ocean currents and temperatures, changed the migration patterns and increased the stock of many fish species. A north Pacific (NP) index is defined to measure the decadal variations, and the temporal variability of the index is explored on daily, annual, interannual and decadal time scales. The dominant atmosphere-ocean relation in the north Pacific is one where atmospheric changes lead SSTs by one to two months. However, strong ties are revealed with events in the tropical Pacific, with changes in tropical Pacific SSTs leading SSTs in the north Pacific by three months. Changes in the storm tracks in the north Pacific help to reinforce and maintain the anomalous circulation in the

Toward Quantitative Understanding of the Atmospheric Heating over the Tibetan Plateau (Invited)

Science.gov (United States)

Koike, T.; Tamura, T.; Rasmy, M.; Seto, R.

2010-12-01

There are different ideas on the atmospheric heating over the Tibetan Plateau. Yanai et al. (1992) and Yanai and Li (1994) concluded this sensible heat flux from the surface is the major source of heating on the plateau before the summer rain commences. On the other hand, Ueda et al. (2003) also showed the importance of condensation heating in the heat balance during the pre-onset-phase of the summer monsoon over the western part of the Tibetan Plateau. The first intensive in situ observation in early spring was implemented on the plateau in April 2004 under the framework of the Coordinated Enhanced Observing Period (CEOP) (Koike, 2004). Taniguchi and Koike (2007) revealed the importance of cumulus activity in atmospheric temperature increases in the upper troposphere even in April by in situ and satellite observations and numerical simulations. They concluded that sensible heat transfer by dry convection is insufficient to warm the upper layer over the plateau and that the development of cloud convection is indispensable for atmospheric heating in the upper troposphere over the plateau during early spring. Then, Taniguchi and Koike (2008) investigated the seasonal variation in the cloud activity over the eastern part of the Tibetan Plateau, and the vertical profile of the atmosphere and moist condition causing the cloud. They showed cumulus convections easily occur under the adiabatically neutral condition of the first phase of the active convections in April. During a resting phase before the second active phase, the atmosphere is conditionally unstable but an unsaturated condition restrains cloud activity, while during second phase, the atmosphere is inclined to be saturated and cloud activity begins again. From early May to mid June, there is a resting period of cumulus convective activity. However, the tropospheric temperature at 200 hPa increases rapidly from late April. Such rapid tropospheric warming without significant cumulus convective activity is

Abrupt rise in atmospheric CO2 at the onset of the Bølling/Allerød: in-situ ice core data versus true atmospheric signals

Directory of Open Access Journals (Sweden)

J. Chappellaz

2011-05-01

Full Text Available During the last glacial/interglacial transition the Earth's climate underwent abrupt changes around 14.6 kyr ago. Temperature proxies from ice cores revealed the onset of the Bølling/Allerød (B/A warm period in the north and the start of the Antarctic Cold Reversal in the south. Furthermore, the B/A was accompanied by a rapid sea level rise of about 20 m during meltwater pulse (MWP 1A, whose exact timing is a matter of current debate. In-situ measured CO2 in the EPICA Dome C (EDC ice core also revealed a remarkable jump of 10 ± 1 ppmv in 230 yr at the same time. Allowing for the modelled age distribution of CO2 in firn, we show that atmospheric CO2 could have jumped by 20–35 ppmv in less than 200 yr, which is a factor of 2–3.5 greater than the CO2 signal recorded in-situ in EDC. This rate of change in atmospheric CO2 corresponds to 29–50% of the anthropogenic signal during the last 50 yr and is connected with a radiative forcing of 0.59–0.75 W m−2. Using a model-based airborne fraction of 0.17 of atmospheric CO2, we infer that 125 Pg of carbon need to be released into the atmosphere to produce such a peak. If the abrupt rise in CO2 at the onset of the B/A is unique with respect to other Dansgaard/Oeschger (D/O events of the last 60 kyr (which seems plausible if not unequivocal based on current observations, then the mechanism responsible for it may also have been unique. Available δ13CO2 data are neutral, whether the source of the carbon is of marine or terrestrial origin. We therefore hypothesise that most of the carbon might have been activated as a consequence of continental shelf flooding during MWP-1A. This potential impact of rapid sea level rise on atmospheric CO2 might define the point of no return during the last deglaciation.

Articulating Atmospheres

DEFF Research Database (Denmark)

Kinch, Sofie

2011-01-01

This paper presents an architectural approach to designing computational interfaces by articulating the notion of atmosphere in the field of interaction design. It draws upon the concept of kinesthetic interaction and a philosophical notion on atmosphere emphasizing the importance of bodily...

Selenium Biofortification in Radish Enhances Nutritional Quality via Accumulation of Methyl-Selenocysteine and Promotion of Transcripts and Metabolites Related to Glucosinolates, Phenolics, and Amino Acids

Science.gov (United States)

Schiavon, Michela; Berto, Chiara; Malagoli, Mario; Trentin, Annarita; Sambo, Paolo; Dall'Acqua, Stefano; Pilon-Smits, Elizabeth A. H.

2016-01-01

Two selenium (Se) fertilization methods were tested for their effects on levels of anticarcinogenic selenocompounds in radish (Raphanus sativus), as well as other nutraceuticals. First, radish was grown on soil and foliar selenate applied 7 days before harvest at 0, 5, 10, and 20 mg Se per plant. Selenium levels were up to 1200 mg Se/kg DW in leaves and 120 mg Se/kg DW in roots. The thiols cysteine and glutathione were present at 2–3-fold higher levels in roots of Se treated plants, and total glucosinolate levels were 35% higher, due to increases in glucoraphanin. The only seleno-aminoacid detected in Se treated plants was Se-methyl-SeCys (100 mg/kg FW in leaves, 33 mg/kg FW in roots). The levels of phenolic aminoacids increased with selenate treatment, as did root total nitrogen and protein content, while the level of several polyphenols decreased. Second, radish was grown in hydroponics and supplied with 0, 5, 10, 20, or 40 μM selenate for 1 week. Selenate treatment led to a 20–30% increase in biomass. Selenium concentration was 242 mg Se/kg DW in leaves and 85 mg Se/kg DW in roots. Cysteine levels decreased with Se in leaves but increased in roots; glutatione levels decreased in both. Total glucosinolate levels in leaves decreased with Se treatment due to repression of genes involved in glucosinolates metabolism. Se-methyl-SeCys concentration ranged from 7–15 mg/kg FW. Aminoacid concentration increased with Se treatment in leaves but decreased in roots. Roots of Se treated plants contained elevated transcript levels of sulfate transporters (Sultr) and ATP sulfurylase, a key enzyme of S/Se assimilation. No effects on polyphenols were observed. In conclusion, Se biofortification of radish roots may be achieved via foliar spray or hydroponic supply. One to ten radishes could fulfill the daily human requirement (70 μg) after a single foliar spray of 5 mg selenate per plant or 1 week of 5–10 μM selenate supply in hydroponics. The radishes metabolized

Highly elevated atmospheric levels of volatile organic compounds in the Uintah Basin, Utah.

Science.gov (United States)

Helmig, D; Thompson, C R; Evans, J; Boylan, P; Hueber, J; Park, J-H

2014-05-06

Oil and natural gas production in the Western United States has grown rapidly in recent years, and with this industrial expansion, growing environmental concerns have arisen regarding impacts on water supplies and air quality. Recent studies have revealed highly enhanced atmospheric levels of volatile organic compounds (VOCs) from primary emissions in regions of heavy oil and gas development and associated rapid photochemical production of ozone during winter. Here, we present surface and vertical profile observations of VOC from the Uintah Basin Winter Ozone Studies conducted in January-February of 2012 and 2013. These measurements identify highly elevated levels of atmospheric alkane hydrocarbons with enhanced rates of C2-C5 nonmethane hydrocarbon (NMHC) mean mole fractions during temperature inversion events in 2013 at 200-300 times above the regional and seasonal background. Elevated atmospheric NMHC mole fractions coincided with build-up of ambient 1-h ozone to levels exceeding 150 ppbv (parts per billion by volume). The total annual mass flux of C2-C7 VOC was estimated at 194 ± 56 × 10(6) kg yr(-1), equivalent to the annual VOC emissions of a fleet of ∼100 million automobiles. Total annual fugitive emission of the aromatic compounds benzene and toluene, considered air toxics, were estimated at 1.6 ± 0.4 × 10(6) and 2.0 ± 0.5 × 10(6) kg yr(-1), respectively. These observations reveal a strong causal link between oil and gas emissions, accumulation of air toxics, and significant production of ozone in the atmospheric surface layer.

Microbial selenium sulfide reduction for selenium recovery from wastewater

NARCIS (Netherlands)

Hageman, S.P.W.; Weijden, van der R.D.; Stams, A.J.M.; Cappellen, van P.; Buisman, C.J.N.

2017-01-01

Microbial reduction of selenium sulfide (SeS2) is a key step in a new treatment process to recover selenium from selenate and selenite streams. In this process, selenate is first reduced to selenite, and subsequently selenite is reduced by sulfide and precipitates from the solution as SeS2. The

Spraying of Crops with Selenium

DEFF Research Database (Denmark)

Sima, Per; Nielsen, Gunnar Gissel

1985-01-01

A frame experiment was carried out in 1983 to test the effect of foliar application of selenate and selenite and the effect of simultaneous addition of a micronutrient solution on the Se concentration of barley and potatoes. In general, selenate was the more effective; however, both forms of Se p...

New Treatment Options for Osteosarcoma - Inactivation of Osteosarcoma Cells by Cold Atmospheric Plasma.

Science.gov (United States)

Gümbel, Denis; Gelbrich, Nadine; Weiss, Martin; Napp, Matthias; Daeschlein, Georg; Sckell, Axel; Ender, Stephan A; Kramer, Axel; Burchardt, Martin; Ekkernkamp, Axel; Stope, Matthias B

2016-11-01

Cold atmospheric plasma has been shown to inhibit tumor cell growth and induce tumor cell death. The aim of the study was to investigate the effects of cold atmospheric plasma treatment on proliferation of human osteosarcoma cells and to characterize the underlying cellular mechanisms. Human osteosarcoma cells (U2-OS and MNNG/HOS) were treated with cold atmospheric plasma and seeded in culture plates. Cell proliferation, p53 and phospho-p53 protein expression and nuclear morphology were assessed. The treated human osteosarcoma cell lines exhibited attenuated proliferation rates by up to 66%. The cells revealed an induction of p53, as well as phospho-p53 expression, by 2.3-fold and 4.5-fold, respectively, compared to controls. 4',6-diamidino-2-phenylindole staining demonstrated apoptotic nuclear condensation following cold atmospheric plasma treatment. Cold atmospheric plasma treatment significantly attenuated cell proliferation in a preclinical in vitro osteosarcoma model. The resulting increase in p53 expression and phospho-activation in combination with characteristic nuclear changes indicate this was through induction of apoptosis. Copyright© 2016 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.

Tropospheric weather influenced by solar wind through atmospheric vertical coupling downward control

Science.gov (United States)

Prikryl, Paul; Bruntz, Robert; Tsukijihara, Takumi; Iwao, Koki; Muldrew, Donald B.; Rušin, Vojto; Rybanský, Milan; Turňa, Maroš; Šťastný, Pavel

2018-06-01

Occurrence of severe weather in the context of solar wind coupling to the magnetosphere-ionosphere-atmosphere (MIA) system is investigated. It is observed that significant snowfall, wind and heavy rain, particularly if caused by low pressure systems in winter, tend to follow arrivals of high-speed solar wind. Previously published statistical evidence that explosive extratropical cyclones in the northern hemisphere tend to occur within a few days after arrivals of high-speed solar wind streams from coronal holes (Prikryl et al., 2009, 2016) is corroborated for the southern hemisphere. Cases of severe weather events are examined in the context of the magnetosphere-ionosphere-atmosphere (MIA) coupling. Physical mechanism to explain these observations is proposed. The leading edge of high-speed solar wind streams is a locus of large-amplitude magneto-hydrodynamic waves that modulate Joule heating and/or Lorentz forcing of the high-latitude lower thermosphere generating medium-scale atmospheric gravity waves that propagate upward and downward through the atmosphere. Simulations of gravity wave propagation in a model atmosphere using the Transfer Function Model (Mayr et al., 1990) reveal that propagating waves originating in the lower thermosphere can excite a spectrum of gravity waves in the lower atmosphere. In spite of significantly reduced amplitudes but subject to amplification upon reflection in the upper troposphere, these gravity waves can provide a lift of unstable air to release instabilities in the troposphere and initiate convection to form cloud/precipitation bands. It is primarily the energy provided by release of latent heat that leads to intensification of storms. These results indicate that vertical coupling in the atmosphere exerts downward control from solar wind to the lower atmospheric levels influencing tropospheric weather development.

Atmospheric Photochemistry

Science.gov (United States)

Massey, Harrie; Potter, A. E.

1961-01-01

The upper atmosphere offers a vast photochemical laboratory free from solid surfaces, so all reactions take place in the gaseous phase. At 30 km altitude the pressure has fallen to about one-hundredth of that at ground level, and we shall, rather arbitrarily, regard the upper atmosphere as beginning at that height. By a little less than 100 km the pressure has fallen to 10(exp -3) mm Hg and is decreasing by a power of ten for every 15 km increase in altitude. Essentially we are concerned then with the photochemistry of a nitrogen-oxygen mixture under low-pressure conditions in which photo-ionization, as well as photodissociation, plays an important part. Account must also be taken of the presence of rare constituents, such as water vapour and its decomposition products, including particularly hydroxyl, oxides of carbon, methane and, strangely enough, sodium, lithium and calcium. Many curious and unfamiliar reactions occur in the upper atmosphere. Some of them are luminescent, causing the atmosphere to emit a dim light called the airglow. Others, between gaseous ions and neutral molecules, are almost a complete mystery at this time. Similar interesting phenomena must occur in other planetary atmospheres, and they might be predicted if sufficient chemical information were available.

Using barometric time series of the IMS infrasound network for a global analysis of thermally induced atmospheric tides

Science.gov (United States)

Hupe, Patrick; Ceranna, Lars; Pilger, Christoph

2018-04-01

The International Monitoring System (IMS) has been established to monitor compliance with the Comprehensive Nuclear-Test-Ban Treaty and comprises four technologies, one of which is infrasound. When fully established, the IMS infrasound network consists of 60 sites uniformly distributed around the globe. Besides its primary purpose of determining explosions in the atmosphere, the recorded data reveal information on other anthropogenic and natural infrasound sources. Furthermore, the almost continuous multi-year recordings of differential and absolute air pressure allow for analysing the atmospheric conditions. In this paper, spectral analysis tools are applied to derive atmospheric dynamics from barometric time series. Based on the solar atmospheric tides, a methodology for performing geographic and temporal variability analyses is presented, which is supposed to serve for upcoming studies related to atmospheric dynamics. The surplus value of using the IMS infrasound network data for such purposes is demonstrated by comparing the findings on the thermal tides with previous studies and the Modern-Era Retrospective analysis for Research and Applications Version 2 (MERRA-2), which represents the solar tides well in its surface pressure fields. Absolute air pressure recordings reveal geographical characteristics of atmospheric tides related to the solar day and even to the lunar day. We therefore claim the chosen methodology of using the IMS infrasound network to be applicable for global and temporal studies on specific atmospheric dynamics. Given the accuracy and high temporal resolution of the barometric data from the IMS infrasound network, interactions with gravity waves and planetary waves can be examined in future for refining the knowledge of atmospheric dynamics, e.g. the origin of tidal harmonics up to 9 cycles per day as found in the barometric data sets. Data assimilation in empirical models of solar tides would be a valuable application of the IMS infrasound

Crystal structure, vibrational spectra and DFT studies of hydrogen bonded 1,2,4-triazolium hydrogenselenate

Science.gov (United States)

Arjunan, V.; Thirunarayanan, S.; Marchewka, M. K.; Mohan, S.

2017-10-01

The new hydrogen bonded molecular complex 1,2,4-triazolium hydrogenselenate (THS) is prepared by the reaction of 1H-1,2,4-triazole and selenic acid. This complex is stabilised by N-H⋯O and C-H⋯O hydrogen bonding and electrostatic attractive forces between 1H and 1,2,4-triazolium cations and hydrogen selenate anions. The XRD studies revealed that intermolecular proton transfer occur from selenic acid to 1H-1,2,4-triazole molecule, results in the formation of 1,2,4-triazolium hydrogenselenate which contains 1,2,4-triazolium cations and hydrogenselenate anions. The molecular structure of THS crystal has also been optimised by using Density Functional Theory (DFT) using B3LYP/cc-pVTZ and B3LYP/6-311++G** methods in order to find the whole characteristics of the molecular complex. The theoretical structural parameters such as bond length, bond angle and dihedral angle determined by DFT methods are well agreed with the XRD parameters. The atomic charges and thermodynamic properties are also calculated and analysed. The energies of frontier molecular orbitals HOMO, LUMO, HOMO-1, LUMO+1 and LUMO-HUMO energy gap are calculated to understand the kinetic stability and chemical reactivity of the molecular complex. The natural bond orbital analysis (NBO) has been performed in order to study the intramolecular bonding interactions and delocalisation of electrons. These intra molecular charge transfer may induce biological activities such as antimicrobials, antiinflammatory, antifungal etc. The complete vibrational assignments of THS have been performed by using FT-IR and FT-Raman spectra.

Low oxygen and argon in the Neoproterozoic atmosphere at 815 Ma

Science.gov (United States)

Yeung, Laurence Y.

2017-12-01

The evolution of Earth's atmosphere on >106-yr timescales is tied to that of the deep Earth. Volcanic degassing, weathering, and burial of volatile elements regulates their abundance at the surface, setting a boundary condition for the biogeochemical cycles that modulate Earth's atmosphere and climate. The atmosphere expresses this interaction through its composition; however, direct measurements of the ancient atmosphere's composition more than a million years ago are notoriously difficult to obtain. Gases trapped in ancient minerals represent a potential archive of the ancient atmosphere, but their fidelity has not been thoroughly evaluated. Both trapping and preservation artifacts may be relevant. Here, I use a multi-element approach to reanalyze recently collected fluid-inclusion data from halites purportedly containing snapshots of the ancient atmosphere as old as 815 Ma. I argue that those samples were affected by the concomitant trapping of air dissolved in brines and contaminations associated with modern air. These artifacts lead to an apparent excess in O2 and Ar. The samples may also contain signals of mass-dependent fractionation and biogeochemical cycling within the fluid inclusions. After consideration of these artifacts, this new analysis suggests that the Tonian atmosphere was likely low in O2, containing ≤10% present atmospheric levels (PAL), not ∼50% PAL as the data would suggest at face value. Low concentrations of O2 are consistent with other geochemical constraints for this time period and further imply that the majority of Neoproterozoic atmospheric oxygenation occurred after 815 Ma. In addition, the analysis reveals a surprisingly low Tonian Ar inventory-≤60% PAL-which, if accurate, challenges our understanding of the solid Earth's degassing history. When placed in context with other empirical estimates of paleo-atmospheric Ar, the data imply a period of relatively slow atmospheric Ar accumulation in the Paleo- and Meso

Atmosphere physics and chemistry

International Nuclear Information System (INIS)

Delmas, R.; Megie, G.; Peuch, V.H.

2005-10-01

Since the 1970's, the awareness about the atmospheric pollution threat has led to a spectacular development of the researches on the complex interactions between the chemical composition of the atmosphere and the climate. This book makes a synthesis of the state-of-the-art in this very active domain of research. Content: introduction, atmosphere dynamics and transport, matter-radiation interaction and radiant transfer, physico-chemical processes, atmospheric aerosol and heterogenous chemistry, anthropic and natural emissions and deposition, stratospheric chemical system, tropospheric chemical system, polluted boundary layer, paleo-environments and ice archives, role of atmospheric chemistry in global changes, measurement principles and instruments, numerical modeling, experimental strategy, regulation and management of the atmospheric environment, index. (J.S.)

Atmospheric pollutants monitoring by analysis of epiphytic lichens

International Nuclear Information System (INIS)

Fuga, Alessandra; Saiki, Mitiko; Marcelli, Marcelo P.; Saldiva, Paulo H.N.

2008-01-01

The Canoparmelia texana epiphytic lichenized fungi was used to monitor atmospheric pollution in the Sao Paulo metropolitan region, SP, Brazil. The cluster analysis applied to the element concentration values confirmed the site groups of different levels of pollution due to industrial and vehicular emissions. In the distribution maps of element concentrations, higher concentrations of Ba and Mn were observed in the vicinity of industries and of a petrochemical complex. The highest concentration of Co found in lichens from the Sao Miguel Paulista site is due to the emissions from a metallurgical processing plant that produces this element. For Br and Zn, the highest concentrations could be associated both to vehicular and industrial emissions. Exploratory analyses revealed that the accumulation of toxic elements in C. texana may be of use in evaluating the human risk of cardiopulmonary mortality due to prolonged exposure to ambient levels of air pollution. - Canoparmelia texana lichenized fungi is a valuable biomonitor for atmospheric pollution

Nucleation in the atmosphere

International Nuclear Information System (INIS)

Hegg, D A; Baker, M B

2009-01-01

Small particles play major roles in modulating radiative and hydrological fluxes in the atmosphere and thus they impact both climate (IPCC 2007) and weather. Most atmospheric particles outside clouds are created in situ through nucleation from gas phase precursors and most ice particles within clouds are formed by nucleation, usually from the liquid. Thus, the nucleation process is of great significance in the Earth's atmosphere. The theoretical examination of nucleation in the atmosphere has been based mostly on classical nucleation theory. While diagnostically very useful, the prognostic skill demonstrated by this approach has been marginal. Microscopic approaches such as molecular dynamics and density functional theory have also proven useful in elucidating various aspects of the process but are not yet sufficiently refined to offer a significant prognostic advantage to the classical approach, due primarily to the heteromolecular nature of atmospheric nucleation. An important aspect of the nucleation process in the atmosphere is that the degree of metastability of the parent phase for the nucleation is modulated by a number of atmospheric processes such as condensation onto pre-existing particles, updraft velocities that are the main driving force for supersaturation of water (a major factor in all atmospheric nucleation), and photochemical production rates of nucleation precursors. Hence, atmospheric nucleation is both temporally and spatially inhomogeneous

Reassessing the atmospheric oxidation mechanism of toluene

Science.gov (United States)

Ji, Yuemeng; Zhao, Jun; Terazono, Hajime; Misawa, Kentaro; Levitt, Nicholas P.; Li, Yixin; Lin, Yun; Peng, Jianfei; Wang, Yuan; Duan, Lian; Pan, Bowen; Zhang, Fang; Feng, Xidan; An, Taicheng; Marrero-Ortiz, Wilmarie; Secrest, Jeremiah; Zhang, Annie L.; Shibuya, Kazuhiko; Molina, Mario J.; Zhang, Renyi

2017-08-01

Photochemical oxidation of aromatic hydrocarbons leads to tropospheric ozone and secondary organic aerosol (SOA) formation, with profound implications for air quality, human health, and climate. Toluene is the most abundant aromatic compound under urban environments, but its detailed chemical oxidation mechanism remains uncertain. From combined laboratory experiments and quantum chemical calculations, we show a toluene oxidation mechanism that is different from the one adopted in current atmospheric models. Our experimental work indicates a larger-than-expected branching ratio for cresols, but a negligible formation of ring-opening products (e.g., methylglyoxal). Quantum chemical calculations also demonstrate that cresols are much more stable than their corresponding peroxy radicals, and, for the most favorable OH (ortho) addition, the pathway of H extraction by O2 to form the cresol proceeds with a smaller barrier than O2 addition to form the peroxy radical. Our results reveal that phenolic (rather than peroxy radical) formation represents the dominant pathway for toluene oxidation, highlighting the necessity to reassess its role in ozone and SOA formation in the atmosphere.

Three-pattern decomposition of global atmospheric circulation: part II—dynamical equations of horizontal, meridional and zonal circulations

Science.gov (United States)

Hu, Shujuan; Cheng, Jianbo; Xu, Ming; Chou, Jifan

2018-04-01

The three-pattern decomposition of global atmospheric circulation (TPDGAC) partitions three-dimensional (3D) atmospheric circulation into horizontal, meridional and zonal components to study the 3D structures of global atmospheric circulation. This paper incorporates the three-pattern decomposition model (TPDM) into primitive equations of atmospheric dynamics and establishes a new set of dynamical equations of the horizontal, meridional and zonal circulations in which the operator properties are studied and energy conservation laws are preserved, as in the primitive equations. The physical significance of the newly established equations is demonstrated. Our findings reveal that the new equations are essentially the 3D vorticity equations of atmosphere and that the time evolution rules of the horizontal, meridional and zonal circulations can be described from the perspective of 3D vorticity evolution. The new set of dynamical equations includes decomposed expressions that can be used to explore the source terms of large-scale atmospheric circulation variations. A simplified model is presented to demonstrate the potential applications of the new equations for studying the dynamics of the Rossby, Hadley and Walker circulations. The model shows that the horizontal air temperature anomaly gradient (ATAG) induces changes in meridional and zonal circulations and promotes the baroclinic evolution of the horizontal circulation. The simplified model also indicates that the absolute vorticity of the horizontal circulation is not conserved, and its changes can be described by changes in the vertical vorticities of the meridional and zonal circulations. Moreover, the thermodynamic equation shows that the induced meridional and zonal circulations and advection transport by the horizontal circulation in turn cause a redistribution of the air temperature. The simplified model reveals the fundamental rules between the evolution of the air temperature and the horizontal, meridional

Atmospheric chemistry of peroxynitrates

International Nuclear Information System (INIS)

Hendry, D.G.; Kenley, R.A.

1979-01-01

The thermochemistry and kinetics of the various types of peroxy nitrates are discussed, and the influence of these compounds on smog formation is evaluated. The heats of formation and of two dissociation reactions for various peroxyalkyl nitrates are calculated and it is shown that dissociation into nitrogen dioxide is more favorable than into nitrogen trioxide for the peroxyalkyl and peroxyacetyl nitrates (PANs). The atmospheric lifetimes of peroxynitric acid, peroxyalkyl nitrates and peroxyacyl nitrates are estimated as a function of temperature and it is found that PANs can exhibit lifetimes greater than a day at low temperatures, resulting in significant concentrations. In the presence of NO, PANs are shown to be an important source of OH radicals in the early morning and at night. A computer simulation reveals the contribution of PANs to ozone formation by the oxidation of NO to NO2

Phase formation and reaction kinetics during the processing of the chalkopyrite-solar-cell-material Cu(In,Ga)(Se,S){sub 2}; Phasenbildung und Reaktionskinetik bei der Herstellung des Chalkopyrit-Solarzellenmaterials Cu(In,Ga)(Se,S){sub 2}

Energy Technology Data Exchange (ETDEWEB)

Purwins, Michael

2010-02-05

's lateral, uniform chemical composition and morphology. Based on variations of the composition of the deposited Cu-Ga-In-films a proposal of the phase relations in the region of the ternary Cu-Ga-In-system being relevant for the production of CIGSe-Absorbers was derived. This investigation revealed that the known phase separation of selenized Cu-Ga-In-precursors into a galliumfree and galliumrich chalkopyrite can be put down to the fact that Cu-In-Ga-Precursors with [Ga]/([Ga]+[In]) ratios between 0,16 and 0,31 are located in a ternary subsystem of the Cu-Ga-In-system. From thermal analysis experiments complemented by in- and ex-situ XRD phase analysis as well as TEM/EDX analysis thermodynamic consistent, kinetic reaction models were derived with the help of kinetic modelling techniques. The models obtained, give a detailed insight into the phase formation processes and associated kinetic mechanisms occurring during the selenization and sulfurization process of copper rich Cu/In-precursors conducted with a surplus of chalkogenes. It was found that the crystallization of CuInSe{sub 2} as well as that of CuInS{sub 2} can be described as one dimensional diffusion controlled nucleation and growth processes with activation energies of 208 and 250 kJ/mol, respectively. Furthermore it was found that CuInSe{sub 2} forms out of intermediate binary indium and copper selenides whereas CuInS{sub 2} crystallizes via the intermediate phases CuS and CuIn{sub 5}S{sub 8}. This is in contrast with the Cu-Ga-Se-system where the chalcopyrite CuGaSe{sub 2} forms directly out of the molten elements. This formation process can be described by a nucleation and growth process that needs a thermal activation of 107 kJ/mol. When the intermediate compound GaSe was involved in the formation process a slightly higher activation energy of 116 kJ/mol was determined. Based on kinetic parameters describing the selenization kinetics of copper rich Cu(In{sub 1-x}Ga{sub x})-alloys transformation

In Situ Measurement of Atmospheric Krypton and Xenon on Mars with Mars Science Laboratory

Science.gov (United States)

Conrad, P. G.; Malespin, C. A.; Franz, H. B.; Pepin, R. O.; Trainer, M. G.; Schwenzer, S. P.; Atreya, S. K.; Freissinet, C.; Jones, J. H.; Manning, H.;

Selenization of Cu2ZnSnS4 Enhanced the Performance of Dye-Sensitized Solar Cells: Improved Zinc-Site Catalytic Activity for I3.

Science.gov (United States)

Wang, Xiuwen; Xie, Ying; Bateer, Buhe; Pan, Kai; Jiao, Yanqing; Xiong, Ni; Wang, Song; Fu, Honggang

2017-11-01

Cu 2 ZnSnS 4 (CZTS) and Cu 2 ZnSn(S,Se) 4 (CZTSSe) as promising photovoltaic materials have drawn much attention because they are environmentally benign and earth-abundant elements. In this work, the monodispersed, low-cost Cu 2 ZnSnS 4 nanocrystals with small size have been controllably synthesized via a wet chemical routine. And CZTSSe could be easily prepared after selenization of CZTS. When they are employed as counter electrodes (CEs) for dye-sensitized solar cells (DSSCs), the power conversion efficiency (PCE) has been improved from 3.54% to 7.13% as CZTS is converted to CZTSSe, which is also compared to that of Pt (7.62%). The exact reason for the enhanced catalytic activity of I 3 - is discussed with the work function and density functional theory (DFT) when CZTSSe converted from CZTS. The results of a Kelvin probe suggest that the work function of CZTSSe (5.61 eV) is closer to that of Pt (5.65 eV) and higher than that of CZTS, which matched the redox shuttle potential better. According to the theory calculation, all the atomic and bond populations changed significantly when Se replaced partly the S on the CZTS system, especially in the Zn site. During the catalytic process as CEs, the adsorption energy obviously increased compared to those at other sites when I 3 - adsorbed on the Zn site in CZTSSe. So, Zn plays an important role for the reduction of I 3 - after CZTS is converted to CZTSSe. Based on above analysis, the reason for enhanced performance of DSSCs when CZTS converted to CZTSSe is mainly due to the enhancement of Zn-site activity. This work is beneficial for understanding the catalytic reaction mechanism of CZTS(Se) as CEs of DSSCs.

Selenium toxicity to honey bee (Apis mellifera L. pollinators: effects on behaviors and survival.

Directory of Open Access Journals (Sweden)

Kristen R Hladun

Full Text Available We know very little about how soil-borne pollutants such as selenium (Se can impact pollinators, even though Se has contaminated soils and plants in areas where insect pollination can be critical to the functioning of both agricultural and natural ecosystems. Se can be biotransferred throughout the food web, but few studies have examined its effects on the insects that feed on Se-accumulating plants, particularly pollinators. In laboratory bioassays, we used proboscis extension reflex (PER and taste perception to determine if the presence of Se affected the gustatory response of honey bee (Apis mellifera L., Hymenoptera: Apidae foragers. Antennae and proboscises were stimulated with both organic (selenomethionine and inorganic (selenate forms of Se that commonly occur in Se-accumulating plants. Methionine was also tested. Each compound was dissolved in 1 M sucrose at 5 concentrations, with sucrose alone as a control. Antennal stimulation with selenomethionine and methionine reduced PER at higher concentrations. Selenate did not reduce gustatory behaviors. Two hours after being fed the treatments, bees were tested for sucrose response threshold. Bees fed selenate responded less to sucrose stimulation. Mortality was higher in bees chronically dosed with selenate compared with a single dose. Selenomethionine did not increase mortality except at the highest concentration. Methionine did not significantly impact survival. Our study has shown that bees fed selenate were less responsive to sucrose, which may lead to a reduction in incoming floral resources needed to support coworkers and larvae in the field. If honey bees forage on nectar containing Se (particularly selenate, reductions in population numbers may occur due to direct toxicity. Given that honey bees are willing to consume food resources containing Se and may not avoid Se compounds in the plant tissues on which they are foraging, they may suffer similar adverse effects as seen in other

Advection of Potential Temperature in the Atmosphere of Irradiated Exoplanets: A Robust Mechanism to Explain Radius Inflation

Science.gov (United States)

Tremblin, P.; Chabrier, G.; Mayne, N. J.; Amundsen, D. S.; Baraffe, I.; Debras, F.; Drummond, B.; Manners, J.; Fromang, S.

2017-01-01

The anomalously large radii of strongly irradiated exoplanets have remained a major puzzle in astronomy. Based on a two-dimensional steady-state atmospheric circulation model, the validity of which is assessed by comparison to three-dimensional calculations, we reveal a new mechanism, namely the advection of the potential temperature due to mass and longitudinal momentum conservation, a process occurring in the Earth's atmosphere or oceans. In the deep atmosphere, the vanishing heating flux forces the atmospheric structure to converge to a hotter adiabat than the one obtained with 1D calculations, implying a larger radius for the planet. Not only do the calculations reproduce the observed radius of HD 209458b, but also reproduce the observed correlation between radius inflation and irradiation for transiting planets. Vertical advection of potential temperature induced by non-uniform atmospheric heating thus provides a robust mechanism to explain the inflated radii of irradiated hot Jupiters.

Advection of Potential Temperature in the Atmosphere of Irradiated Exoplanets: A Robust Mechanism to Explain Radius Inflation

International Nuclear Information System (INIS)

Tremblin, P.; Chabrier, G.; Mayne, N. J.; Baraffe, I.; Debras, F.; Drummond, B.; Manners, J.; Amundsen, D. S.; Fromang, S.

2017-01-01

The anomalously large radii of strongly irradiated exoplanets have remained a major puzzle in astronomy. Based on a two-dimensional steady-state atmospheric circulation model, the validity of which is assessed by comparison to three-dimensional calculations, we reveal a new mechanism, namely the advection of the potential temperature due to mass and longitudinal momentum conservation, a process occurring in the Earth’s atmosphere or oceans. In the deep atmosphere, the vanishing heating flux forces the atmospheric structure to converge to a hotter adiabat than the one obtained with 1D calculations, implying a larger radius for the planet. Not only do the calculations reproduce the observed radius of HD 209458b, but also reproduce the observed correlation between radius inflation and irradiation for transiting planets. Vertical advection of potential temperature induced by non-uniform atmospheric heating thus provides a robust mechanism to explain the inflated radii of irradiated hot Jupiters.

Advection of Potential Temperature in the Atmosphere of Irradiated Exoplanets: A Robust Mechanism to Explain Radius Inflation

Energy Technology Data Exchange (ETDEWEB)

Tremblin, P. [Maison de la Simulation, CEA-CNRS-INRIA-UPS-UVSQ, USR 3441, CEA Paris-Saclay, F-91191 Gif-Sur-Yvette (France); Chabrier, G.; Mayne, N. J.; Baraffe, I.; Debras, F.; Drummond, B.; Manners, J. [Astrophysics Group, University of Exeter, EX4 4QL Exeter (United Kingdom); Amundsen, D. S. [Department of Applied Physics and Applied Mathematics, Columbia University, New York, NY 10025 (United States); Fromang, S., E-mail: pascal.tremblin@cea.fr [Laboratoire AIM, CEA/DSM-CNRS-Université Paris 7, Irfu/Service d’Astrophysique, CEA Paris-Saclay, F-91191 Gif-sur-Yvette (France)

2017-05-20

The anomalously large radii of strongly irradiated exoplanets have remained a major puzzle in astronomy. Based on a two-dimensional steady-state atmospheric circulation model, the validity of which is assessed by comparison to three-dimensional calculations, we reveal a new mechanism, namely the advection of the potential temperature due to mass and longitudinal momentum conservation, a process occurring in the Earth’s atmosphere or oceans. In the deep atmosphere, the vanishing heating flux forces the atmospheric structure to converge to a hotter adiabat than the one obtained with 1D calculations, implying a larger radius for the planet. Not only do the calculations reproduce the observed radius of HD 209458b, but also reproduce the observed correlation between radius inflation and irradiation for transiting planets. Vertical advection of potential temperature induced by non-uniform atmospheric heating thus provides a robust mechanism to explain the inflated radii of irradiated hot Jupiters.

Titan Casts Revealing Shadow

Science.gov (United States)

2004-05-01

A rare celestial event was captured by NASA's Chandra X-ray Observatory as Titan -- Saturn's largest moon and the only moon in the Solar System with a thick atmosphere -- crossed in front of the X-ray bright Crab Nebula. The X-ray shadow cast by Titan allowed astronomers to make the first X-ray measurement of the extent of its atmosphere. On January 5, 2003, Titan transited the Crab Nebula, the remnant of a supernova explosion that was observed to occur in the year 1054. Although Saturn and Titan pass within a few degrees of the Crab Nebula every 30 years, they rarely pass directly in front of it. "This may have been the first transit of the Crab Nebula by Titan since the birth of the Crab Nebula," said Koji Mori of Pennsylvania State University in University Park, and lead author on an Astrophysical Journal paper describing these results. "The next similar conjunction will take place in the year 2267, so this was truly a once in a lifetime event." Animation of Titan's Shadow on Crab Nebula Animation of Titan's Shadow on Crab Nebula Chandra's observation revealed that the diameter of the X-ray shadow cast by Titan was larger than the diameter of its solid surface. The difference in diameters gives a measurement of about 550 miles (880 kilometers) for the height of the X-ray absorbing region of Titan's atmosphere. The extent of the upper atmosphere is consistent with, or slightly (10-15%) larger, than that implied by Voyager I observations made at radio, infrared, and ultraviolet wavelengths in 1980. "Saturn was about 5% closer to the Sun in 2003, so increased solar heating of Titan may account for some of this atmospheric expansion," said Hiroshi Tsunemi of Osaka University in Japan, one of the coauthors on the paper. The X-ray brightness and extent of the Crab Nebula made it possible to study the tiny X-ray shadow cast by Titan during its transit. By using Chandra to precisely track Titan's position, astronomers were able to measure a shadow one arcsecond in

Molecular understanding of sulphuric acid-amine particle nucleation in the atmosphere.

Science.gov (United States)

Almeida, João; Schobesberger, Siegfried; Kürten, Andreas; Ortega, Ismael K; Kupiainen-Määttä, Oona; Praplan, Arnaud P; Adamov, Alexey; Amorim, Antonio; Bianchi, Federico; Breitenlechner, Martin; David, André; Dommen, Josef; Donahue, Neil M; Downard, Andrew; Dunne, Eimear; Duplissy, Jonathan; Ehrhart, Sebastian; Flagan, Richard C; Franchin, Alessandro; Guida, Roberto; Hakala, Jani; Hansel, Armin; Heinritzi, Martin; Henschel, Henning; Jokinen, Tuija; Junninen, Heikki; Kajos, Maija; Kangasluoma, Juha; Keskinen, Helmi; Kupc, Agnieszka; Kurtén, Theo; Kvashin, Alexander N; Laaksonen, Ari; Lehtipalo, Katrianne; Leiminger, Markus; Leppä, Johannes; Loukonen, Ville; Makhmutov, Vladimir; Mathot, Serge; McGrath, Matthew J; Nieminen, Tuomo; Olenius, Tinja; Onnela, Antti; Petäjä, Tuukka; Riccobono, Francesco; Riipinen, Ilona; Rissanen, Matti; Rondo, Linda; Ruuskanen, Taina; Santos, Filipe D; Sarnela, Nina; Schallhart, Simon; Schnitzhofer, Ralf; Seinfeld, John H; Simon, Mario; Sipilä, Mikko; Stozhkov, Yuri; Stratmann, Frank; Tomé, Antonio; Tröstl, Jasmin; Tsagkogeorgas, Georgios; Vaattovaara, Petri; Viisanen, Yrjo; Virtanen, Annele; Vrtala, Aron; Wagner, Paul E; Weingartner, Ernest; Wex, Heike; Williamson, Christina; Wimmer, Daniela; Ye, Penglin; Yli-Juuti, Taina; Carslaw, Kenneth S; Kulmala, Markku; Curtius, Joachim; Baltensperger, Urs; Worsnop, Douglas R; Vehkamäki, Hanna; Kirkby, Jasper

2013-10-17

Nucleation of aerosol particles from trace atmospheric vapours is thought to provide up to half of global cloud condensation nuclei. Aerosols can cause a net cooling of climate by scattering sunlight and by leading to smaller but more numerous cloud droplets, which makes clouds brighter and extends their lifetimes. Atmospheric aerosols derived from human activities are thought to have compensated for a large fraction of the warming caused by greenhouse gases. However, despite its importance for climate, atmospheric nucleation is poorly understood. Recently, it has been shown that sulphuric acid and ammonia cannot explain particle formation rates observed in the lower atmosphere. It is thought that amines may enhance nucleation, but until now there has been no direct evidence for amine ternary nucleation under atmospheric conditions. Here we use the CLOUD (Cosmics Leaving OUtdoor Droplets) chamber at CERN and find that dimethylamine above three parts per trillion by volume can enhance particle formation rates more than 1,000-fold compared with ammonia, sufficient to account for the particle formation rates observed in the atmosphere. Molecular analysis of the clusters reveals that the faster nucleation is explained by a base-stabilization mechanism involving acid-amine pairs, which strongly decrease evaporation. The ion-induced contribution is generally small, reflecting the high stability of sulphuric acid-dimethylamine clusters and indicating that galactic cosmic rays exert only a small influence on their formation, except at low overall formation rates. Our experimental measurements are well reproduced by a dynamical model based on quantum chemical calculations of binding energies of molecular clusters, without any fitted parameters. These results show that, in regions of the atmosphere near amine sources, both amines and sulphur dioxide should be considered when assessing the impact of anthropogenic activities on particle formation.

Origin of atmosphere

Energy Technology Data Exchange (ETDEWEB)

Marx, Gy [Eotvos Lorand Tudomanyegyetem, Budapest (Hungary). Atomfizikai Tanszek

1975-01-01

The evolution of the atmosphere of the Earth is described. Starting from the hot Universe the main steps of the ''cooling-down'' process as the different states of the condensation of the matter are discussed. After this nuclear evolution the chemical evolution could start on the solid Earth's crust. In the reductive primordial atmosphere mainly due to ultraviolet rays the basic molecules for life as sugars and amino acids were formed. The photosynthesis of the plants has later produced the oxygen being present in the recent atmosphere. The question whether pollution could affect the auto-stabilization loop of the atmosphere is also discussed. Finally the possibility of life on the Mars is studied.

On the Impact of Wind Farms on a Convective Atmospheric Boundary Layer

Science.gov (United States)

Lu, Hao; Porté-Agel, Fernando

2015-10-01

With the rapid growth in the number of wind turbines installed worldwide, a demand exists for a clear understanding of how wind farms modify land-atmosphere exchanges. Here, we conduct three-dimensional large-eddy simulations to investigate the impact of wind farms on a convective atmospheric boundary layer. Surface temperature and heat flux are determined using a surface thermal energy balance approach, coupled with the solution of a three-dimensional heat equation in the soil. We study several cases of aligned and staggered wind farms with different streamwise and spanwise spacings. The farms consist of Siemens SWT-2.3-93 wind turbines. Results reveal that, in the presence of wind turbines, the stability of the atmospheric boundary layer is modified, the boundary-layer height is increased, and the magnitude of the surface heat flux is slightly reduced. Results also show an increase in land-surface temperature, a slight reduction in the vertically-integrated temperature, and a heterogeneous spatial distribution of the surface heat flux.

Bombs and Flares at the Surface and Lower Atmosphere of the Sun

Energy Technology Data Exchange (ETDEWEB)

Hansteen, V. H.; Pereira, T. M. D.; Carlsson, M.; Van der Voort, L. Rouppe [Institute of Theoretical Astrophysics, University of Oslo, Norway, PB 1029 Blindern, NO-0315 Oslo (Norway); Archontis, V. [School of Mathematics and Statistics, St. Andrews University, St. Andrews, KY169SS (United Kingdom); Leenaarts, J. [Institute for Solar Physics, Dept. of Astronomy, Stockholm University, Roslagstullbacken 21 SE-10691 Stockholm (Sweden)

2017-04-10

A spectacular manifestation of solar activity is the appearance of transient brightenings in the far wings of the H α line, known as Ellerman bombs (EBs). Recent observations obtained by the Interface Region Imaging Spectrograph have revealed another type of plasma “bombs” (UV bursts) with high temperatures of perhaps up to 8 × 10{sup 4} K within the cooler lower solar atmosphere. Realistic numerical modeling showing such events is needed to explain their nature. Here, we report on 3D radiative magnetohydrodynamic simulations of magnetic flux emergence in the solar atmosphere. We find that ubiquitous reconnection between emerging bipolar magnetic fields can trigger EBs in the photosphere, UV bursts in the mid/low chromosphere and small (nano-/micro-) flares (10{sup 6} K) in the upper chromosphere. These results provide new insights into the emergence and build up of the coronal magnetic field and the dynamics and heating of the solar surface and lower atmosphere.

Fair weather atmospheric electricity

International Nuclear Information System (INIS)

Harrison, R G

2011-01-01

Not long after Franklin's iconic studies, an atmospheric electric field was discovered in 'fair weather' regions, well away from thunderstorms. The origin of the fair weather field was sought by Lord Kelvin, through development of electrostatic instrumentation and early data logging techniques, but was ultimately explained through the global circuit model of C.T.R. Wilson. In Wilson's model, charge exchanged by disturbed weather electrifies the ionosphere, and returns via a small vertical current density in fair weather regions. New insights into the relevance of fair weather atmospheric electricity to terrestrial and planetary atmospheres are now emerging. For example, there is a possible role of the global circuit current density in atmospheric processes, such as cloud formation. Beyond natural atmospheric processes, a novel practical application is the use of early atmospheric electrostatic investigations to provide quantitative information on past urban air pollution.

Chernobyl source term, atmospheric dispersion, and dose estimation

International Nuclear Information System (INIS)

Gudiksen, P.H.; Harvey, T.F.; Lange, R.

1988-02-01

The Chernobyl source term available for long-range transport was estimated by integration of radiological measurements with atmospheric dispersion modeling, and by reactor core radionuclide inventory estimation in conjunction with WASH-1400 release fractions associated with specific chemical groups. These analyses indicated that essentially all of the noble gases, 80% of the radioiodines, 40% of the radiocesium, 10% of the tellurium, and about 1% or less of the more refractory elements were released. Atmospheric dispersion modeling of the radioactive cloud over the Northern Hemisphere revealed that the cloud became segmented during the first day, with the lower section heading toward Scandinavia and the uppper part heading in a southeasterly direction with subsequent transport across Asia to Japan, the North Pacific, and the west coast of North America. The inhalation doses due to direct cloud exposure were estimated to exceed 10 mGy near the Chernobyl area, to range between 0.1 and 0.001 mGy within most of Europe, and to be generally less than 0.00001 mGy within the US. The Chernobyl source term was several orders of magnitude greater than those associated with the Windscale and TMI reactor accidents, while the 137 Cs from the Chernobyl event is about 6% of that released by the US and USSR atmospheric nuclear weapon tests. 9 refs., 3 figs., 6 tabs

Annual atmospheric mercury species in downtown Toronto, Canada.

Science.gov (United States)

Song, Xinjie; Cheng, Irene; Lu, Julia

2009-03-01

Real-time concentrations of atmospheric gaseous elemental mercury (GEM), reactive gaseous mercury (RGM), and mercury associated with particles having sizes RGM were 4.5 +/- 3.1 ng m(-3) (99.2%), 21.5 +/- 16.4 pg m(-3) (0.5%) and 14.2 +/- 13.2 pg m(-3) (0.3%), respectively. The concentrations for all the measured Hg species were highly variable throughout the year and were lower in winter than in the other three seasons. The maximum concentrations of Hg species were observed in June and were a result of the high number of Hg spikes (using [GEM] >10 ng m(-3) as an indicator) that occurred in the month. Nighttime (between 9pm-6am) concentrations of Hg species were higher than those of daytime. The results revealed: (1) an urban area is a continuous source of Hg species that have the potential to pose impacts on local, regional and global scales; (2) local/regional anthropogenic sources contributed significantly to the levels and the distributions of the Hg species in the urban atmosphere. More studies are needed to identify and quantify the anthropogenic sources of Hg and the Hg species emitted from these sources; (3) surface emission and photochemical reactions (including the reactions involving ozone) did not have significant influence on the levels of Hg species and their distribution in the urban atmosphere.

Human and natural influences on the changing thermal structure of the atmosphere.

Science.gov (United States)

Santer, Benjamin D; Painter, Jeffrey F; Bonfils, Céline; Mears, Carl A; Solomon, Susan; Wigley, Tom M L; Gleckler, Peter J; Schmidt, Gavin A; Doutriaux, Charles; Gillett, Nathan P; Taylor, Karl E; Thorne, Peter W; Wentz, Frank J

2013-10-22

Since the late 1970s, satellite-based instruments have monitored global changes in atmospheric temperature. These measurements reveal multidecadal tropospheric warming and stratospheric cooling, punctuated by short-term volcanic signals of reverse sign. Similar long- and short-term temperature signals occur in model simulations driven by human-caused changes in atmospheric composition and natural variations in volcanic aerosols. Most previous comparisons of modeled and observed atmospheric temperature changes have used results from individual models and individual observational records. In contrast, we rely on a large multimodel archive and multiple observational datasets. We show that a human-caused latitude/altitude pattern of atmospheric temperature change can be identified with high statistical confidence in satellite data. Results are robust to current uncertainties in models and observations. Virtually all previous research in this area has attempted to discriminate an anthropogenic signal from internal variability. Here, we present evidence that a human-caused signal can also be identified relative to the larger "total" natural variability arising from sources internal to the climate system, solar irradiance changes, and volcanic forcing. Consistent signal identification occurs because both internal and total natural variability (as simulated by state-of-the-art models) cannot produce sustained global-scale tropospheric warming and stratospheric cooling. Our results provide clear evidence for a discernible human influence on the thermal structure of the atmosphere.

Anthropogenous modifications of the atmosphere. The atmospheric ozone threat

International Nuclear Information System (INIS)

Aimedieu, P.

1991-01-01

Ozone role and atmospheric chemistry are first reviewed: chemical reactions and vertical distribution of ozone in the atmosphere. The origins of chlorofluorocarbon air pollution and the role of the various types of CFC on ozone depletion, greenhouse effect, cancer, etc. are then discussed. The political and environmental discussions concerning these phenomena are also reviewed

Longwave atmospheric radiation as a possible indicator of the aviation impact

Energy Technology Data Exchange (ETDEWEB)

Zaitseva, N.A. [Central Aerological Observatory of the Russian Federal Service for Hydrometeorology and Environmental Monitoring, Moscow (Russian Federation)

1997-12-31

Aircraft emissions changing composition of the atmospheric air should be sensed by radiation parameters, such as downward (in first turn) and upward long-wave fluxes. It might be supposed that the accurate measurements of long-wave (LW) radiation fluxes in regions of crowded aircraft routes time outside these regions, could detect the influence. Main transformation of the long-wave radiation (LWR) proceeds in the troposphere which absorbs and irradiates the LWR. The only mass method of the LWR measurements in the free atmosphere became the radiometer probe. In the former USSR it was successfully developed in 1961, and since 1963 the special radiometer sounding network started to make regular observations over the USSR territory. Rather small spatial variations of the downward LWR flux was observed indicating rather high homogeneity of the atmosphere composition. Analysis of the seasonal variations of the downward LWR has revealed that over some stations it has the opposite course of changes from summer to winter and it is mainly observed at rather high levels. (R.P.) 10 refs.

Longwave atmospheric radiation as a possible indicator of the aviation impact

Energy Technology Data Exchange (ETDEWEB)

Zaitseva, N A [Central Aerological Observatory of the Russian Federal Service for Hydrometeorology and Environmental Monitoring, Moscow (Russian Federation)

1998-12-31

Aircraft emissions changing composition of the atmospheric air should be sensed by radiation parameters, such as downward (in first turn) and upward long-wave fluxes. It might be supposed that the accurate measurements of long-wave (LW) radiation fluxes in regions of crowded aircraft routes time outside these regions, could detect the influence. Main transformation of the long-wave radiation (LWR) proceeds in the troposphere which absorbs and irradiates the LWR. The only mass method of the LWR measurements in the free atmosphere became the radiometer probe. In the former USSR it was successfully developed in 1961, and since 1963 the special radiometer sounding network started to make regular observations over the USSR territory. Rather small spatial variations of the downward LWR flux was observed indicating rather high homogeneity of the atmosphere composition. Analysis of the seasonal variations of the downward LWR has revealed that over some stations it has the opposite course of changes from summer to winter and it is mainly observed at rather high levels. (R.P.) 10 refs.

Large wind ripples on Mars: A record of atmospheric evolution

Science.gov (United States)

Lapotre, M G; Ewing, R C; Lamb, M P; Fischer, W W; Grotzinger, J P; Rubin, D M; Lewis, K W; Ballard, M; Day, Mitch D.; Gupta, S.; Banham, S G; Bridges, N T; Des Marais, D J; Fraeman, A A; Grant, J A; Herkenhoff, Kenneth E.; Ming, D W; Mischna, M A; Rice, M S; Sumner, D A; Vasavada, A R; Yingst, R A

2016-01-01

Wind blowing over sand on Earth produces decimeter-wavelength ripples and hundred-meter– to kilometer-wavelength dunes: bedforms of two distinct size modes. Observations from the Mars Science Laboratory Curiosity rover and the Mars Reconnaissance Orbiter reveal that Mars hosts a third stable wind-driven bedform, with meter-scale wavelengths. These bedforms are spatially uniform in size and typically have asymmetric profiles with angle-of-repose lee slopes and sinuous crest lines, making them unlike terrestrial wind ripples. Rather, these structures resemble fluid-drag ripples, which on Earth include water-worked current ripples, but on Mars instead form by wind because of the higher kinematic viscosity of the low-density atmosphere. A reevaluation of the wind-deposited strata in the Burns formation (about 3.7 billion years old or younger) identifies potential wind-drag ripple stratification formed under a thin atmosphere.

Large wind ripples on Mars: A record of atmospheric evolution

Science.gov (United States)

Lapotre, M. G. A.; Ewing, R. C.; Lamb, M. P.; Fischer, W. W.; Grotzinger, J. P.; Rubin, D. M.; Lewis, K. W.; Ballard, M. J.; Day, M.; Gupta, S.; Banham, S. G.; Bridges, N. T.; Des Marais, D. J.; Fraeman, A. A.; Grant, J. A.; Herkenhoff, K. E.; Ming, D. W.; Mischna, M. A.; Rice, M. S.; Sumner, D. A.; Vasavada, A. R.; Yingst, R. A.

2016-07-01

Wind blowing over sand on Earth produces decimeter-wavelength ripples and hundred-meter- to kilometer-wavelength dunes: bedforms of two distinct size modes. Observations from the Mars Science Laboratory Curiosity rover and the Mars Reconnaissance Orbiter reveal that Mars hosts a third stable wind-driven bedform, with meter-scale wavelengths. These bedforms are spatially uniform in size and typically have asymmetric profiles with angle-of-repose lee slopes and sinuous crest lines, making them unlike terrestrial wind ripples. Rather, these structures resemble fluid-drag ripples, which on Earth include water-worked current ripples, but on Mars instead form by wind because of the higher kinematic viscosity of the low-density atmosphere. A reevaluation of the wind-deposited strata in the Burns formation (about 3.7 billion years old or younger) identifies potential wind-drag ripple stratification formed under a thin atmosphere.

Atmospheric electrodynamics

International Nuclear Information System (INIS)

Volland, H.

1984-01-01

The book Atmospheric Electrodynamics, by Hans Voland is reviewed. The book describes a wide variety of electrical phenomena occurring in the upper and lower atmosphere and develops the mathematical models which simulate these processes. The reviewer finds that the book is of interest to researchers with a background in electromagnetic theory but is of only limited use as a reference work

Atmospheric pollution

International Nuclear Information System (INIS)

Lambrozo, J.; Guillossou, G.

2008-01-01

The atmosphere is the reservoir of numerous pollutants (nitrogen oxides, sulfur oxides, carbon oxides, particulates, volatile organic compounds, polycyclic aromatic hydrocarbons) from natural origin or anthropogenic origin ( industry, transport, agriculture, district heating). With epidemiologic studies the atmospheric pollution is associated with an increase of respiratory and cardiovascular diseases. At the european level, the technological progress, the legislation have allowed a reduction of pollutant emissions, however these efforts have to be continued because the sanitary impact of atmospheric pollution must not be underestimated, even if the risks appear less important that these ones in relation with tobacco, inside pollution or others factors of cardiovascular risks. Indeed, on these last factors an individual action is possible for the exposure to air pollution people have no control. (N.C.)

Reference Atmosphere for Mercury

Science.gov (United States)

Killen, Rosemary M.

2002-01-01

We propose that Ar-40 measured in the lunar atmosphere and that in Mercury's atmosphere is due to current diffusion into connected pore space within the crust. Higher temperatures at Mercury, along with more rapid loss from the atmosphere will lead to a smaller column abundance of argon at Mercury than at the Moon, given the same crustal abundance of potassium. Because the noble gas abundance in the Hermean atmosphere represents current effusion, it is a direct measure of the crustal potassium abundance. Ar-40 in the atmospheres of the planets is a measure of potassium abundance in the interiors, since Ar-40 is a product of radiogenic decay of K-40 by electron capture with the subsequent emission of a 1.46 eV gamma-ray. Although the Ar-40 in the Earth's atmosphere is expected to have accumulated since the late bombardment, Ar-40 in the atmospheres of Mercury and the Moon is eroded quickly by photoionization and electron impact ionization. Thus, the argon content in the exospheres of the Moon and Mercury is representative of current effusion rather than accumulation over the lifetime of the planet.

Swell impact on wind stress and atmospheric mixing in a regional coupled atmosphere-wave model

DEFF Research Database (Denmark)

Wu, Lichuan; Rutgersson, Anna; Sahlée, Erik

2016-01-01

Over the ocean, the atmospheric turbulence can be significantly affected by swell waves. Change in the atmospheric turbulence affects the wind stress and atmospheric mixing over swell waves. In this study, the influence of swell on atmospheric mixing and wind stress is introduced into an atmosphere-wave-coupled...... regional climate model, separately and combined. The swell influence on atmospheric mixing is introduced into the atmospheric mixing length formula by adding a swell-induced contribution to the mixing. The swell influence on the wind stress under wind-following swell, moderate-range wind, and near......-neutral and unstable stratification conditions is introduced by changing the roughness length. Five year simulation results indicate that adding the swell influence on atmospheric mixing has limited influence, only slightly increasing the near-surface wind speed; in contrast, adding the swell influence on wind stress...

ABOUT THE POSSIBLE ROLE OF HYDROCARBON LAKES IN THE ORIGIN OF TITAN'S NOBLE GAS ATMOSPHERIC DEPLETION

International Nuclear Information System (INIS)

Cordier, D.; Mousis, O.; Lunine, J. I.; Lebonnois, S.; Lavvas, P.; Lobo, L. Q.; Ferreira, A. G. M.

2010-01-01

An unexpected feature of Titan's atmosphere is the strong depletion in primordial noble gases revealed by the Gas Chromatograph Mass Spectrometer aboard the Huygens probe during its descent on 2005 January 14. Although several plausible explanations have already been formulated, no definitive response to this issue has yet been found. Here, we investigate the possible sequestration of these noble gases in the liquid contained in lakes and wet terrains on Titan and the consequences for their atmospheric abundances. Considering the atmosphere and the liquid existing on the soil as a whole system, we compute the abundance of each noble gas relative to nitrogen. To do so, we make the assumption of thermodynamic equilibrium between the liquid and the atmosphere, the abundances of the different constituents being determined via regular solution theory. We find that xenon's atmospheric depletion can be explained by its dissolution at ambient temperature in the liquid presumably present on Titan's soil. In the cases of argon and krypton, we find that the fractions incorporated in the liquid are negligible, implying that an alternative mechanism must be invoked to explain their atmospheric depletion.

Interhemispheric gradient of atmospheric radiocarbon reveals natural variability of Southern Ocean winds

Science.gov (United States)

Rodgers, K. B.; Mikaloff-Fletcher, S. E.; Bianchi, D.; Beaulieu, C.; Galbraith, E. D.; Gnanadesikan, A.; Hogg, A. G.; Iudicone, D.; Lintner, B. R.; Naegler, T.; Reimer, P. J.; Sarmiento, J. L.; Slater, R. D.

2011-10-01

Tree ring Δ14C data (Reimer et al., 2004; McCormac et al., 2004) indicate that atmospheric Δ14C varied on multi-decadal to centennial timescales, in both hemispheres, over the period between AD 950 and 1830. The Northern and Southern Hemispheric Δ14C records display similar variability, but from the data alone is it not clear whether these variations are driven by the production of 14C in the stratosphere (Stuiver and Quay, 1980) or by perturbations to exchanges between carbon reservoirs (Siegenthaler et al., 1980). As the sea-air flux of 14CO2 has a clear maximum in the open ocean regions of the Southern Ocean, relatively modest perturbations to the winds over this region drive significant perturbations to the interhemispheric gradient. In this study, model simulations are used to show that Southern Ocean winds are likely a main driver of the observed variability in the interhemispheric gradient over AD 950-1830, and further, that this variability may be larger than the Southern Ocean wind trends that have been reported for recent decades (notably 1980-2004). This interpretation also implies that there may have been a significant weakening of the winds over the Southern Ocean within a few decades of AD 1375, associated with the transition between the Medieval Climate Anomaly and the Little Ice Age. The driving forces that could have produced such a shift in the winds at the Medieval Climate Anomaly to Little Ice Age transition remain unknown. Our process-focused suite of perturbation experiments with models raises the possibility that the current generation of coupled climate and earth system models may underestimate the natural background multi-decadal- to centennial-timescale variations in the winds over the Southern Ocean.

Interhemispheric gradient of atmospheric radiocarbon reveals natural variability of Southern Ocean winds

Directory of Open Access Journals (Sweden)

K. B. Rodgers

2011-10-01

Full Text Available Tree ring Δ¹⁴C data (Reimer et al., 2004; McCormac et al., 2004 indicate that atmospheric Δ¹⁴C varied on multi-decadal to centennial timescales, in both hemispheres, over the period between AD 950 and 1830. The Northern and Southern Hemispheric Δ¹⁴C records display similar variability, but from the data alone is it not clear whether these variations are driven by the production of ¹⁴C in the stratosphere (Stuiver and Quay, 1980 or by perturbations to exchanges between carbon reservoirs (Siegenthaler et al., 1980. As the sea-air flux of ¹⁴CO₂ has a clear maximum in the open ocean regions of the Southern Ocean, relatively modest perturbations to the winds over this region drive significant perturbations to the interhemispheric gradient. In this study, model simulations are used to show that Southern Ocean winds are likely a main driver of the observed variability in the interhemispheric gradient over AD 950–1830, and further, that this variability may be larger than the Southern Ocean wind trends that have been reported for recent decades (notably 1980–2004. This interpretation also implies that there may have been a significant weakening of the winds over the Southern Ocean within a few decades of AD 1375, associated with the transition between the Medieval Climate Anomaly and the Little Ice Age. The driving forces that could have produced such a shift in the winds at the Medieval Climate Anomaly to Little Ice Age transition remain unknown. Our process-focused suite of perturbation experiments with models raises the possibility that the current generation of coupled climate and earth system models may underestimate the natural background multi-decadal- to centennial-timescale variations in the winds over the Southern Ocean.

Atmospheric refraction : a history

NARCIS (Netherlands)

Lehn, WH; van der Werf, S

2005-01-01

We trace the history of atmospheric refraction from the ancient Greeks up to the time of Kepler. The concept that the atmosphere could refract light entered Western science in the second century B.C. Ptolemy, 300 years later, produced the first clearly defined atmospheric model, containing air of

Effect of Atmospheric Organics on Bioavailable Fe Lifetime in the Oceans

Science.gov (United States)

Meskhidze, Nicholas; Hurley, David; Royalty, Taylor Michael; Johnson, Matthew S.

2016-01-01

The deposition of atmospheric aerosols is an important supply pathway of soluble iron (sol-Fe) to the global oceans influencing marine ecosystem processes and climate. Previous studies have shown that natural and anthropogenic acidic trace gases, when mixed with mineral dust, can lead to production of sol-Fe, leading to considerable increase in dust-Fe solubility. Recent studies have further highlighted the importance of atmospheric organic compounds/ligands in the production of sol-Fe during atmospheric transport and transformation of mineral aerosols. However, the actual scope of this aerosol sol-Fe for stimulating the primary productivity in the oceans is determined by both: the total atmospheric fluxes of sol-Fe and the lifetime of sol-Fe after its deposition to the ocean. In this study several atmospheric organic ligands were investigated for their effect on the lifetime of sol-Fe after mixing with seawater. Organic ligands were selected based on their abundance in the marine boundary layer and rainwater and their ability to form bidentate complexes with Fe. The results reveal that the tested organics had minor influence on Fe(II) lifetime in seawater. However, results also show that some organic acid considerably extended the lifetime of colloidal and aqueous Fe(III). Using these results we simulate aerosol sol-Fe lifetime in the ocean for different mineral dust deposition events in the presence and the absence of atmospheric organic ligands. The calculations suggest that when a large dust plume is assumed to contain Fe(II) alone, less than 15% of aerosol sol-Fe gets complexed with marine organic ligands. However, this fraction increases to over 90% when atmospheric Fe is allowed to bond with atmospheric organic acids prior to deposition to the oceans. Calculations also show that for the conditions when seawater organic ligands get titrated by Fe released from dust aerosol particles, retention of sol-Fe in the ocean depends on surface ocean mixing, i

Potassium limits potential growth of bog vegetation under elevated atmospheric CO2 and N deposition

NARCIS (Netherlands)

Hoosbeek, M.R.; Breemen, van N.; Vasander, H.; Buttlers, A.; Berendse, F.

2002-01-01

The free air carbon dioxide enrichment (FACE) and N deposition experiments on four ombrotrophic bogs in Finland, Sweden, the Netherlands and Switzerland, revealed that after three years of treatment: (1) elevated atmospheric CO2 concentration had no significant effect on the biomass growth of

Mars: Atmosphere

Science.gov (United States)

Moroz, V.; Murdin, P.

2001-07-01

The atmosphere of MARS is much thinner than the terrestrial one. However, even the simplest visual telescopic observations show a set of atmospheric events such as seasonal exchange of material between polar caps, temporal appearance of clouds and changes of visibility of dark regions on the disk of the planet. In 1947 the prominent CO2 bands in the near-infrared part of the Martian spectrum were...

Fiscal 1998 New Sunshine Program achievement report. Development for practical application of photovoltaic system - Development of thin-film solar cell manufacturing technology (Development of low-cost large-area module manufacturing technology - Development of next-generation thin-film solar cell manufacturing technology - Development of CIS solar cell module manufacturing technology); 1998 nendo taiyoko hatsuden system jitsuyoka gijutsu kaihatsu seika hokokusho. Usumaku taiyo denchi no seizo gijutsu kaihatsu / tei cost daimenseki module seizo gijutsu kaihatsu / jisedai usumaku taiyo denchi no seizo gijutsu kaihatsu / CIS taiyo denchi module no seizo gijutsu kaihatsu

Energy Technology Data Exchange (ETDEWEB)

NONE

1999-03-01

This research aims to achieve a conversion efficiency of 13% and a manufacturing cost of 140 yen/Wp with a 30cm times 30cm Cu(InGa)Se{sub 2}-based thin-film solar cell submodule. Ga and sulfur are combined and a film fabrication technology was developed which would improve on Voc. Concerning Ga, a laminated precursor layer was fabricated and evaluated, which comprised a Cu-25wt%Ga alloy layer and a Ga source which was a Cu-48%Ga alloy layer. Concerning sulfur, the vapor phase selenization temperature and the selenization retention time in an H{sub 2}Se gas atmosphere was allowed to vary for a change in Cu(InGa)Se{sub 2} calcopyrite crystallinity for the study of relations between the amount of sulfur taken in and the solar cell characteristics, and the relations were assessed by EPMA (electron probe microanalyzer). Technologies were developed for the fabrication of high-resistivity buffer layers by solution growth, for the fabrication of window layers (transparent, conductive ZnO film) by sputtering, and for their patterning. Submodules of a ZnO/Zn(O,S,OH)x/Mo structure were fabricated, 10cm times 30cm and 30cm times 30cm in size. The former achieved 12.5% in conversion efficiency, and the latter 11.6%. (NEDO)

New Sunshine Project FY 1996 report on the results of development of photovoltaic power generation system commercialization technologies. Research on commercialization of the technologies for production of thin-film photovoltaic cells (Development of fabrication technologies of high-quality CuInSe{sub 2}-based thin-film solar cells); 1996 nendo taiyoko hatsuden system jitsuyoka gijutsu kaihatsu seika hokokusho. Usumaku taiyo denchi seizo gijutsu no jitsuyoka kenkyu (kohinshitsuka gijutsu (CuInSe{sub 2} taiyo denchi seizo no gijutsu kaihatsu))

Energy Technology Data Exchange (ETDEWEB)

NONE

1997-03-01

Described herein are the FY 1996 results of development of fabrication technologies for high-quality CuInSe{sub 2}-based photovoltaic cells. The Cu-Ga alloy/In-stacked precursor film is prepared for production of the high-quality thin-film absorber applicable to large-area module fabrication, and selenized by the vapor-phase selenization in a H{sub 2}Se gas atmosphere to produce the thin light-absorbing film in which In and Ga are present at graded concentrations. Increasing Ga alloy content in the CIGS-based thin-film photovoltaic cell fails to widen the forbidden band and improve V{sub oc}, and further optimization works are needed. The method is developed for production of thin-film buffer layer of sulfur-containing Zn compound which can give the cell characteristics equivalent to those of CdS generally used for CIS-based thin-film photovoltaic cell. It is clarified that the photovoltaic cell characteristics can be improved by use of a transparent electroconductive ZnO film of stacked structure, produced by a combination of RF sputtering and DC sputtering. For the patterning technologies necessary for forming series connection on a mini-module, the laser scribing method is applicable to the metal base-electrode, and the mechanical scribing method to the light absorber and window layer. (NEDO)

Modified Back Contact Interface of CZTSe Thin Film Solar Cells: Elimination of Double Layer Distribution in Absorber Layer.

Science.gov (United States)

Zhang, Zhaojing; Yao, Liyong; Zhang, Yi; Ao, Jianping; Bi, Jinlian; Gao, Shoushuai; Gao, Qing; Jeng, Ming-Jer; Sun, Guozhong; Zhou, Zhiqiang; He, Qing; Sun, Yun

2018-02-01

Double layer distribution exists in Cu 2 SnZnSe 4 (CZTSe) thin films prepared by selenizing the metallic precursors, which will degrade the back contact of Mo substrate to absorber layer and thus suppressing the performance of solar cell. In this work, the double-layer distribution of CZTSe film is eliminated entirely and the formation of MoSe 2 interfacial layer is inhibited successfully. CZTSe film is prepared by selenizing the precursor deposited by electrodeposition method under Se and SnSe x mixed atmosphere. It is found that the insufficient reaction between ZnSe and Cu-Sn-Se phases in the bottom of the film is the reason why the double layer distribution of CZTSe film is formed. By increasing Sn content in the metallic precursor, thus making up the loss of Sn because of the decomposition of CZTSe and facilitate the diffusion of liquid Cu 2 Se, the double layer distribution is eliminated entirely. The crystallization of the formed thin film is dense and the grains go through the entire film without voids. And there is no obvious MoSe 2 layer formed between CZTSe and Mo. As a consequence, the series resistance of the solar cell reduces significantly to 0.14 Ω cm 2 and a CZTSe solar cell with efficiency of 7.2% is fabricated.

The nitrogen cycle: Atmosphere interactions

Science.gov (United States)

Levine, J. S.

1984-01-01

Atmospheric interactions involving the nitrogen species are varied and complex. These interactions include photochemical reactions, initiated by the absorption of solar photons and chemical kinetic reactions, which involve both homogeneous (gas-to-gas reactions) and heterogeneous (gas-to-particle) reactions. Another important atmospheric interaction is the production of nitrogen oxides by atmospheric lightning. The nitrogen cycle strongly couples the biosphere and atmosphere. Many nitrogen species are produced by biogenic processes. Once in the atmosphere nitrogen oxides are photochemically and chemically transformed to nitrates, which are returned to the biosphere via precipitation, dry deposition and aerosols to close the biosphere-atmosphere nitrogen cycle. The sources, sinks and photochemistry/chemistry of the nitrogen species; atmospheric nitrogen species; souces and sinks of nitrous oxide; sources; sinks and photochemistry/chemistry of ammonia; seasonal variation of the vertical distribution of ammonia in the troposphere; surface and atmospheric sources of the nitrogen species, and seasonal variation of ground level ammonia are summarized.

Efficiency of fatty acid accumulation into breast muscles of chickens ...

African Journals Online (AJOL)

The purpose of the investigation was to determine the effect of the addition of 12 ppm lycopene (Lyc), 2% fish oil (FO) or 0.25 ppm Se as selenate (SeVI) or selenized yeast (SeY) to an isoenergetic and isonitrogenous basal diet containing sunflower oil (SO) as the source of energy on the concentrations of fatty acids (FA), ...

Sources of atmospheric methane from coastal marine wetlands

International Nuclear Information System (INIS)

Harriss, R.C.; Sebacher, D.I.; Bartlett, K.B.; Bartlett, D.S.

1982-01-01

Biological methanogenesis in wetlands is believed to be one of the major sources of global tropospheric methane. The present paper reports measurements of methane distribution in the soils, sediments, water and vegetation of coastal marine wetlands. Measurements, carried out in the salt marshes Bay Tree Creek in Virginia and Panacea in northwest Florida, reveal methane concentrations in soils and sediments to vary with depth below the surface and with soil temperature. The fluxes of methane from marsh soils to the atmosphere at the soil-air interface are estimated to range from -0.00067 g CH 4 /sq m per day (methane sink) to 0.024 g CH 4 /sq m per day, with an average value of 0.0066 g CH 4 /sq m per day. Data also demonstrate the important role of tidal waters percolating through marsh soils in removing methane from the soils and releasing it to the atmosphere. The information obtained, together with previous studies, provides a framework for the design of a program based on in situ and remote sensing measurements to study the global methane cycle

Our shared atmosphere

Science.gov (United States)

Our atmosphere is a precious and fascinating resource, providing air to breath, shielding us from harmful ultraviolet radiation (UV), and maintaining a comfortable climate. Since the industrial revolution, people have significantly altered the composition of the atmosphere throu...

Dynamics of Massive Atmospheres

Energy Technology Data Exchange (ETDEWEB)

Chemke, Rei; Kaspi, Yohai, E-mail: rei.chemke@weizmann.ac.il [Department of Earth and Planetary Sciences, Weizmann Institute of Science, 234 Herzl st., 76100, Rehovot (Israel)

2017-08-10

The many recently discovered terrestrial exoplanets are expected to hold a wide range of atmospheric masses. Here the dynamic-thermodynamic effects of atmospheric mass on atmospheric circulation are studied using an idealized global circulation model by systematically varying the atmospheric surface pressure. On an Earth analog planet, an increase in atmospheric mass weakens the Hadley circulation and decreases its latitudinal extent. These changes are found to be related to the reduction of the convective fluxes and net radiative cooling (due to the higher atmospheric heat capacity), which, respectively, cool the upper troposphere at mid-low latitudes and warm the troposphere at high latitudes. These together decrease the meridional temperature gradient, tropopause height and static stability. The reduction of these parameters, which play a key role in affecting the flow properties of the tropical circulation, weakens and contracts the Hadley circulation. The reduction of the meridional temperature gradient also decreases the extraction of mean potential energy to the eddy fields and the mean kinetic energy, which weakens the extratropical circulation. The decrease of the eddy kinetic energy decreases the Rhines wavelength, which is found to follow the meridional jet scale. The contraction of the jet scale in the extratropics results in multiple jets and meridional circulation cells as the atmospheric mass increases.

Generation and characterization of gasoline engine exhaust inhalation exposure atmospheres.

Science.gov (United States)

McDonald, Jacob D; Barr, Edward B; White, Richard K; Kracko, Dean; Chow, Judith C; Zielinska, Barbara; Grosjean, Eric

2008-10-01

Exposure atmospheres for a rodent inhalation toxicology study were generated from the exhaust of a 4.3-L gasoline engine coupled to a dynamometer and operated on an adapted California Unified Driving Cycle. Exposure levels were maintained at three different dilution rates. One chamber at the lowest dilution had particles removed by filtration. Each exposure atmosphere was characterized for particle mass, particle number, particle size distribution, and detailed chemical speciation. The majority of the mass in the exposure atmospheres was gaseous carbon monoxide, nitrogen oxides, and volatile organics, with small amounts of particle-bound carbon/ions and metals. The atmospheres varied according to the cycle, with the largest spikes in volatile organic and inorganic species shown during the "cold start" portion of the cycle. Ammonia present from the exhaust and rodents interacted with the gasoline exhaust to form secondary inorganic particles, and an increase in exhaust resulted in higher proportions of secondary inorganics as a portion of the total particle mass. Particle size had a median of 10-20 nm by number and approximately 150 nm by mass. Volatile organics matched the composition of the fuel, with large proportions of aliphatic and aromatic hydrocarbons coupled to low amounts of oxygenated organics. A new measurement technique revealed organics reacting with nitrogen oxides have likely resulted in measurement bias in previous studies of combustion emissions. Identified and measured particle organic species accounted for about 10% of total organic particle mass and were mostly aliphatic acids and polycyclic aromatic hydrocarbons.

FORMATION OF ORGANIC MOLECULES AND WATER IN WARM DISK ATMOSPHERES

International Nuclear Information System (INIS)

Najita, Joan R.; Ádámkovics, Máté; Glassgold, Alfred E.

2011-01-01

Observations from Spitzer and ground-based infrared spectroscopy reveal significant diversity in the molecular emission from the inner few AU of T Tauri disks. We explore theoretically the possible origin of this diversity by expanding on our earlier thermal-chemical model of disk atmospheres. We consider how variations in grain settling, X-ray irradiation, accretion-related mechanical heating, and the oxygen-to-carbon ratio can affect the thermal and chemical properties of the atmosphere at 0.25-40 AU. We find that these model parameters can account for many properties of the detected molecular emission. The column density of the warm (200-2000 K) molecular atmosphere is sensitive to grain settling and the efficiency of accretion-related heating, which may account, at least in part, for the large range in molecular emission fluxes that have been observed. The dependence of the atmospheric properties on the model parameters may also help to explain trends that have been reported in the literature between molecular emission strength and mid-infrared color, stellar accretion rate, and disk mass. We discuss whether some of the differences between our model results and the observations (e.g., for water) indicate a role for vertical transport and freezeout in the disk midplane. We also discuss how planetesimal formation in the outer disk (beyond the snowline) may imprint a chemical signature on the inner few AU of the disk and speculate on possible observational tracers of this process.

FORMATION OF ORGANIC MOLECULES AND WATER IN WARM DISK ATMOSPHERES

Energy Technology Data Exchange (ETDEWEB)

Najita, Joan R. [National Optical Astronomy Observatory, 950 N. Cherry Avenue, Tucson, AZ 85719 (United States); Adamkovics, Mate; Glassgold, Alfred E. [Astronomy Department, University of California, Berkeley, CA 94720 (United States)

2011-12-20

Observations from Spitzer and ground-based infrared spectroscopy reveal significant diversity in the molecular emission from the inner few AU of T Tauri disks. We explore theoretically the possible origin of this diversity by expanding on our earlier thermal-chemical model of disk atmospheres. We consider how variations in grain settling, X-ray irradiation, accretion-related mechanical heating, and the oxygen-to-carbon ratio can affect the thermal and chemical properties of the atmosphere at 0.25-40 AU. We find that these model parameters can account for many properties of the detected molecular emission. The column density of the warm (200-2000 K) molecular atmosphere is sensitive to grain settling and the efficiency of accretion-related heating, which may account, at least in part, for the large range in molecular emission fluxes that have been observed. The dependence of the atmospheric properties on the model parameters may also help to explain trends that have been reported in the literature between molecular emission strength and mid-infrared color, stellar accretion rate, and disk mass. We discuss whether some of the differences between our model results and the observations (e.g., for water) indicate a role for vertical transport and freezeout in the disk midplane. We also discuss how planetesimal formation in the outer disk (beyond the snowline) may imprint a chemical signature on the inner few AU of the disk and speculate on possible observational tracers of this process.

New atmospheric program

Science.gov (United States)

The National Science Foundation's Division of Atmospheric Sciences has established an Upper Atmospheric Facilities program within its Centers and Facilities section. The program will support the operation of and the scientific research that uses the longitudinal chain of incoherent scatter radars. The program also will ensure that the chain is maintained as a state-of-the-art research tool available to all interested and qualified scientists.For additional information, contact Richard A. Behnke, Division of Atmospheric Sciences, National Science Foundation, 1800 G Street, N.W., Washington, DC 20550 (telephone: 202-357-7390).

Global Dimming and Brightening Versus Atmospheric Column Transparency, Europe 1906-2007

Energy Technology Data Exchange (ETDEWEB)

Ohvril, H.; Teral, H.; Neiman, L.; Kannel, Martin; Uustare, M.; Tee, M.; Russak, V.; Okulov, O.; Joeveer, A.; Kallis, A.; Ohvril, Tiiu; Terez, E.; Terez, G.; Gushchin, G.; Abakumova, G. M.; Gorbarenko, Ekaterina V.; Tsvetkov, Anatoly V.; Laulainen, Nels S.

2009-05-09

Multiannual changes in atmospheric column transparency based on measurements of direct solar radiation allow us to assess various tendencies in climatic changes. Variability of the atmospheric integral (broadband) transparency coefficient, calculated according to the Bouguer-Lambert law and transformed to a solar elevation of 30°, is used for two Russian locations, Pavlovsk and Moscow, one Ukrainian location, Feodosiya, and three Estonian locations, Tartu, Tõravere, and Tiirikoja, covering together a 102-year period, 1906–2007. The comparison of time series revealed significant parallelism. Multiannual trends demonstrate decrease in transparency during the postwar period until 1983/1984. The trend ends with a steep decline of transparency after a series of four volcanic eruptions of Soufriere (1979), Saint Helens (1980), Alaid (1981), and El Chichón (1982). From 1984/1985 to 1990 the atmosphere remarkably restored its clarity, which almost reached again the level of the 1960s. Following the eruption of Mount Pinatubo (June 1991), there was the most significant reduction in column transparency of the postwar period. However, from the end of 1990s, the atmosphere in all considered locations is characterized with high values of transparency. The clearing of the atmosphere (from 1993) evidently indicates a decrease in the content of aerosol particles and, besides the decline of volcanic activity, may therefore be also traced to environmentally oriented changes in technology (pollution prevention), to general industrial and agricultural decline in the territory of the former USSR and Eastern Europe after deep political changes in 1991, and in part to migration of some industries out of Europe.

Global dimming and brightening versus atmospheric column transparency, Europe, 1906-2007

Science.gov (United States)

Ohvril, Hanno; Teral, Hilda; Neiman, Lennart; Kannel, Martin; Uustare, Marika; Tee, Mati; Russak, Viivi; Okulov, Oleg; Jõeveer, Anne; Kallis, Ain; Ohvril, Tiiu; Terez, Edward I.; Terez, Galina A.; Gushchin, Gennady K.; Abakumova, Galina M.; Gorbarenko, Ekaterina V.; Tsvetkov, Anatoly V.; Laulainen, Nels

2009-05-01

Multiannual changes in atmospheric column transparency based on measurements of direct solar radiation allow us to assess various tendencies in climatic changes. Variability of the atmospheric integral (broadband) transparency coefficient, calculated according to the Bouguer-Lambert law and transformed to a solar elevation of 30°, is used for two Russian locations, Pavlovsk and Moscow, one Ukrainian location, Feodosiya, and three Estonian locations, Tartu, Tõravere, and Tiirikoja, covering together a 102-year period, 1906-2007. The comparison of time series revealed significant parallelism. Multiannual trends demonstrate decrease in transparency during the postwar period until 1983/1984. The trend ends with a steep decline of transparency after a series of four volcanic eruptions of Soufriere (1979), Saint Helens (1980), Alaid (1981), and El Chichón (1982). From 1984/1985 to 1990 the atmosphere remarkably restored its clarity, which almost reached again the level of the 1960s. Following the eruption of Mount Pinatubo (June 1991), there was the most significant reduction in column transparency of the postwar period. However, from the end of 1990s, the atmosphere in all considered locations is characterized with high values of transparency. The clearing of the atmosphere (from 1993) evidently indicates a decrease in the content of aerosol particles and, besides the decline of volcanic activity, may therefore be also traced to environmentally oriented changes in technology (pollution prevention), to general industrial and agricultural decline in the territory of the former USSR and Eastern Europe after deep political changes in 1991, and in part to migration of some industries out of Europe.

Determination of the atmospheric neutrino fluxes from atmospheric neutrino data

International Nuclear Information System (INIS)

Gonzalez-Garcia, C.; Maltoni, M.; Rojo, J.

2006-06-01

The precise knowledge of the atmospheric neutrino fluxes is a key ingredient in the interpretation of the results from any atmospheric neutrino experiment. In the standard data analysis, these fluxes are theoretical inputs obtained from sophisticated numerical calculations based on the convolution of the primary cosmic ray spectrum with the expected yield of neutrinos per incident cosmic ray. In this work we present an alternative approach to the determination of the atmospheric neutrino fluxes based on the direct extraction from the experimental data on neutrino event rates. The extraction is achieved by means of a combination of artificial neural networks as interpolants and Monte Carlo methods for faithful error estimation. (author)

Determination of the atmospheric neutrino fluxes from atmospheric neutrino data

International Nuclear Information System (INIS)

Gonzalez-Garcia, Concepcion; Maltoni, Michele; Rojo, Joan

2006-01-01

The precise knowledge of the atmospheric neutrino fluxes is a key ingredient in the interpretation of the results from any atmospheric neutrino experiment. In the standard data analysis, these fluxes are theoretical inputs obtained from sophisticated numerical calculations based on the convolution of the primary cosmic ray spectrum with the expected yield of neutrinos per incident cosmic ray. In this work we present an alternative approach to the determination of the atmospheric neutrino fluxes based on the direct extraction from the experimental data on neutrino event rates. The extraction is achieved by means of a combination of artificial neural networks as interpolants and Monte Carlo methods for faithful error estimation

Variability of atmospheric carbonyl sulfide at a semi-arid urban site in western India.

Science.gov (United States)

Mallik, Chinmay; Chandra, Naveen; Venkataramani, S; Lal, Shyam

2016-05-01

Atmospheric carbonyl sulfide (COS) is a major precursor for sulfate aerosols that play a critical role in climate regulation. Recent studies have highlighted the importance of COS measurements as a reliable means to constrain biospheric carbon assimilation. In a scenario of limited availability of COS data around the globe, we present gas-chromatographic measurements of atmospheric COS mixing ratios over Ahmedabad, a semi-arid, urban region in western India. These measurements, being reported for the first time over an Indian site, enable us to understand the diurnal and seasonal variation in atmospheric COS with respect to its natural, anthropogenic and photochemical sources and sinks. The annual mean COS mixing ratio over Ahmedabad is found to be 0.83±0.43ppbv, which is substantially higher than free tropospheric values for the northern hemisphere. Inverse correlation of COS with soil and skin temperature, suggests that the dry soil of the semi-arid study region is a potential sink for atmospheric COS. Positive correlations of COS with NO2 and CO during post-monsoon and the COS/CO slope of 0.78pptv/ppbv reveals influence of diesel combustion and tire wear. The highest concentrations of COS are observed during pre-monsoon; COS/CO2 slope of 44.75pptv/ppmv combined with information from air mass back-trajectories reveal marshy wetlands spanning over 7500km(2) as an important source of COS in Ahmedabad. COS/CO2 slopes decrease drastically (8.28pptv/ppmv) during post-monsoon due to combined impact of biospheric uptake and anthropogenic emissions. Copyright © 2016 Elsevier B.V. All rights reserved.

Hazard evaluation of inorganics, singly and in mixtures, to Flannelmouth Sucker Catostomus latipinnis in the San Juan River, New Mexico

Science.gov (United States)

Hamilton, S.J.; Buhl, K.J.

1997-01-01

Larval flannelmouth sucker (Catostomus latipinnis) were exposed to arsenate, boron, copper, molybdenum, selenate, selenite, uranium, vanadium, and zinc singly, and to five mixtures of five to nine inorganics. The exposures were conducted in reconstituted water representative of the San Juan River near Shiprock, New Mexico. The mixtures simulated environmental ratios reported for sites along the San Juan River (San Juan River backwater, Fruitland marsh, Hogback East Drain, Mancos River, and McElmo Creek). The rank order of the individual inorganics, from most to least toxic, was: copper > zinc > vanadium > selenite > selenate > arsenate > uranium > boron > molybdenum. All five mixtures exhibited additive toxicity to flannelmouth sucker. In a limited number of tests, 44-day-old and 13-day-old larvae exhibited no difference in sensitivity to three mixtures. Copper was the major toxic component in four mixtures (San Juan backwater, Hogback East Drain, Mancos River, and McElmo Creek), whereas zinc was the major toxic component in the Fruitland marsh mixture, which did not contain copper. The Hogback East Drain was the most toxic mixture tested. Comparison of 96-h LC50values with reported environmental water concentrations from the San Juan River revealed low hazard ratios for arsenic, boron, molybdenum, selenate, selenite, uranium, and vanadium, moderate hazard ratios for zinc and the Fruitland marsh mixture, and high hazard ratios for copper at three sites and four environmental mixtures representing a San Juan backwater, Hogback East Drain, Mancos River, and McElmo Creek. The high hazard ratios suggest that inorganic contaminants could adversely affect larval flannelmouth sucker in the San Juan River at four sites receiving elevated inorganics.

Study of particle size and trace metal distribution in atmospheric aerosols of islamabad

International Nuclear Information System (INIS)

Shah, M.H.; Shaheen, N.

2009-01-01

Atmospheric aerosol samples were collected on glass fibre filters using high volume air samplers Half of each aerosol sample was solubilized in nitric acid/hydrochloric acid based wet digestion method and the concentration of trace metals was determined through flame atomic absorption spectrophotometer. Among the eight trace metals analyzed, mean concentration recorded for Zn (844 ng/m3), Fe (642 ng/m3) and Pb (253 ng/m3), was found to be higher than mean levels of Mn, Cr and Co. The size distribution of the collected particulate samples was carried out on mastersizer, which revealed PM/sub 100-10/ as the major fraction (55 %) followed by PM/sub 2.5-10/ (28 %). The correlation study evidenced a strong tendency of trace metals to be associated with fine particulate fractions. The atmospheric trace metal levels showed that the mean metal concentrations in the atmosphere of Islamabad are far higher than background and European urban sites mainly due to the anthropogenic emissions. (author)

Atmospheric correction of satellite data

Science.gov (United States)

Shmirko, Konstantin; Bobrikov, Alexey; Pavlov, Andrey

2015-11-01

Atmosphere responses for more than 90% of all radiation measured by satellite. Due to this, atmospheric correction plays an important role in separating water leaving radiance from the signal, evaluating concentration of various water pigments (chlorophyll-A, DOM, CDOM, etc). The elimination of atmospheric intrinsic radiance from remote sensing signal referred to as atmospheric correction.

Composition, Chemistry, and Climate of the Atmosphere. 2: Mean properties of the atmosphere

Science.gov (United States)

Singh, Hanwant B. (Editor); Salstein, David A.

1994-01-01

The atmosphere can be defined as the relatively thin gaseous envelope surrounding the entire planet Earth. It possesses a number of properties related to its physical state and chemical composition, and it undergoes a variety of internal processes and external interactions that can either maintain or alter these properties. Whereas descriptions of the atmosphere's chemical properties form much of the remaining chapters of this book, the present chapter will highlight the atmosphere's gases, and these define its temperature structure. In contrast, the larger-scale motions comprise the winds, the global organization of which is often referred to as the general circulation. The framework of the dynamical and thermodynamical laws, including the three principles of conversation of mass, momentum, and energy, are fundamental in describing both the internal processes of the atmosphere and its external interactions. The atmosphere is not a closed system, because it exchanges all three of these internally conservative quantities across the atmosphere's boundary below and receives input from regions outside it. Thus surface fluxes of moisture, momentum, and heat occur to and from the underlying ocean and land. The atmosphere exchanges very little mass and momentum with space, though it absorbs directly a portion of the solar radiational energy received from above.

Neutral molecular cluster formation of sulfuric acid–dimethylamine observed in real time under atmospheric conditions

CERN Document Server

Kürten, Andreas; Simon, Mario; Sipilä, Mikko; Sarnela, Nina; Junninen, Heikki; Adamov, Alexey; Almeida, João; Amorim, Antonio; Bianchi, Federico; Breitenlechner, Martin; Dommen, Josef; Donahue, Neil M; Duplissy, Jonathan; Ehrhart, Sebastian; Flagan, Richard C; Franchin, Alessandro; Hakala, Jani; Hansel, Armin; Heinritzi, Martin; Hutterli, Manuel; Kangasluoma, Juha; Kirkby, Jasper; Laaksonen, Ari; Lehtipalo, Katrianne; Leiminger, Markus; Makhmutov, Vladimir; Mathot, Serge; Onnela, Antti; Petäjä, Tuukka; Praplan, Arnaud P; Riccobono, Francesco; Rissanen, Matti P; Rondo, Linda; Schobesberger, Siegfried; Seinfeld, John H; Steiner, Gerhard; Tomé, António; Tröstl, Jasmin; Winkler, Paul M; Williamson, Christina; Wimmer, Daniela; Ye, Penglin; Baltensperger, Urs; Carslaw, Kenneth S; Kulmala, Markku; Worsnop, Douglas R; Curtius, Joachim

2014-01-01

For atmospheric sulfuric acid (SA) concentrations the presence of dimethylamine (DMA) at mixing ratios of several parts per trillion by volume can explain observed boundary layer new particle formation rates. However, the concentration and molecular composition of the neutral (uncharged) clusters have not been reported so far due to the lack of suitable instrumentation. Here we report on experiments from the Cosmics Leaving Outdoor Droplets chamber at the European Organization for Nuclear Research revealing the formation of neutral particles containing up to 14 SA and 16 DMA molecules, corresponding to a mobility diameter of about 2 nm, under atmospherically relevant conditions. These measurements bridge the gap between the molecular and particle perspectives of nucleation, revealing the fundamental processes involved in particle formation and growth. The neutral clusters are found to form at or close to the kinetic limit where particle formation is limited only by the collision rate of SA molecules. Even tho...

Impact of the Lower Atmosphere on the Ionosphere Response to a Geomagnetic Superstorm

Science.gov (United States)

Pedatella, N. M.

2016-12-01

Numerical simulations in the National Center for Atmospheric Research (NCAR) Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIE-GCM) are performed to elucidate the impacts of lower atmosphere forcing on the ionosphere response to a geomagnetic superstorm. In particular, how the ionosphere variability due to the October 2003 Halloween storm would be different if it occurred in January coincident with a major sudden stratosphere warming (SSW) event is investigated. The TIE-GCM simulations reveal that the E x B vertical drift velocity and total electron content (TEC) respond differently to the geomagnetic disturbance when the lower atmosphere forcing is representative of SSW conditions compared to climatological lower atmosphere forcing conditions. Notably, the storm time variations in the E x B vertical drift velocity differ when the effects of the SSW are considered, and this is in part due to effects of the SSW on the equatorial ionosphere being potentially misinterpreted as being of geomagnetic origin. Differences in the TEC response to the geomagnetic storm can be up to 100% ( 30 TECU) of the storm induced TEC change, and the temporal variability of the TEC during the storm recovery phase is considerably different if SSW effects are considered. The results demonstrate that even during periods of extreme geomagnetic forcing it is important to consider the effects of lower atmosphere forcing on the ionosphere variability.

Dispersion of effluents in the atmosphere; Dispersion des effluents dans l`atmosphere

Energy Technology Data Exchange (ETDEWEB)

NONE

1999-12-31

This conference day was organized by the `convection` section of the French association of thermal engineers with the support of the environment and energy mastery agency (ADEME). This book of proceedings contains 10 papers entitled: `physical modeling of atmospheric dispersion in wind tunnels. Some industrial examples`; `modeling of the noxious effects of a fire on the environment of an industrial site: importance of thermal engineering related hypotheses`; `atmospheric diffusion of a noxious cloud: fast evaluation method of safety areas around refrigerating installations that use ammonia`; `modeling of atmospheric flows in urban areas in order to study the dispersion of pollutants`; `use of a dispersion parameter to characterize the evolution of a diffusion process downstream of a linear source of passive contaminant placed inside a turbulent boundary layer`; `elements of reflexion around the development of an analytical methodology applied to the elaboration of measurement strategies of air quality in ambient and outdoor atmospheres around industrial sites`; `state-of-the-art about treatment techniques for VOC-rich gaseous effluents`; `characteristics of the time variation of the atmospheric pollution in the Paris region and visualization of its space distribution`; `mass-spectrometry for the measurement of atmospheric pollutants`; `volume variations in natural convection turbulence`. (J.S.)

Dispersion of effluents in the atmosphere; Dispersion des effluents dans l`atmosphere

Energy Technology Data Exchange (ETDEWEB)

NONE

1998-12-31

This conference day was organized by the `convection` section of the French association of thermal engineers with the support of the environment and energy mastery agency (ADEME). This book of proceedings contains 10 papers entitled: `physical modeling of atmospheric dispersion in wind tunnels. Some industrial examples`; `modeling of the noxious effects of a fire on the environment of an industrial site: importance of thermal engineering related hypotheses`; `atmospheric diffusion of a noxious cloud: fast evaluation method of safety areas around refrigerating installations that use ammonia`; `modeling of atmospheric flows in urban areas in order to study the dispersion of pollutants`; `use of a dispersion parameter to characterize the evolution of a diffusion process downstream of a linear source of passive contaminant placed inside a turbulent boundary layer`; `elements of reflexion around the development of an analytical methodology applied to the elaboration of measurement strategies of air quality in ambient and outdoor atmospheres around industrial sites`; `state-of-the-art about treatment techniques for VOC-rich gaseous effluents`; `characteristics of the time variation of the atmospheric pollution in the Paris region and visualization of its space distribution`; `mass-spectrometry for the measurement of atmospheric pollutants`; `volume variations in natural convection turbulence`. (J.S.)

Atmospheric sciences annual progress report, 1974

International Nuclear Information System (INIS)

Tucker, W.D.

1975-11-01

Activities in atmospheric sciences in the Department of Applied Science at Brookhaven National Laboratory carried out during 1974 are described. Included are contributions from the Meteorology, Atmospheric Diagnostics, Atmospheric Chemistry Research, and Atmospheric Instrumentation Groups. Programs in Meteorology reported on include diffusion from an off-shore source, plume dynamics studies, modeling of coastal effects on wind and temperature fields and pollutant distributions, effects of indoor shelter on inhalation of airborne radionuclides, chemical-dynamical interactions, techniques for determining acid-rain impact upon the ecology of the eastern U.S., and climatology. Work under Atmospheric Chemistry Research was concentrated on atmospheric aerosol studies, including formation by free radical and neutral association reactions, identification of reactive systems leading to aerosol formation, growth of sodium aerosols under atmospheric conditions and clustering reactions. Atmospheric Diagnostics presents work on field sampling and analytical technology for atmospheric pollutants, airborne sampling systems, atmospheric sulfate particulates methodology, and on a pyroturbidometric method for particulate sulfate discrimination and determination. Methodology for the use of sulfur hexafluoride in field tracer studies is discussed under Atmospheric Instrumentation. A list of publications is included

Verification of atmospheric diffusion models using data of long term atmospheric diffusion experiments

International Nuclear Information System (INIS)

Tamura, Junji; Kido, Hiroko; Hato, Shinji; Homma, Toshimitsu

2009-03-01

Straight-line or segmented plume models as atmospheric diffusion models are commonly used in probabilistic accident consequence assessment (PCA) codes due to cost and time savings. The PCA code, OSCAAR developed by Japan Atomic Energy Research Institute (Present; Japan Atomic Energy Agency) uses the variable puff trajectory model to calculate atmospheric transport and dispersion of released radionuclides. In order to investigate uncertainties involved with the structure of the atmospheric dispersion/deposition model in OSCAAR, we have introduced the more sophisticated computer codes that included regional meteorological models RAMS and atmospheric transport model HYPACT, which were developed by Colorado State University, and comparative analyses between OSCAAR and RAMS/HYPACT have been performed. In this study, model verification of OSCAAR and RAMS/HYPACT was conducted using data of long term atmospheric diffusion experiments, which were carried out in Tokai-mura, Ibaraki-ken. The predictions by models and the results of the atmospheric diffusion experiments indicated relatively good agreements. And it was shown that model performance of OSCAAR was the same degree as it of RAMS/HYPACT. (author)

Deciphering the Hot Giant Atmospheres Orbiting Nearby Extrasolar Systems with JWST

Science.gov (United States)

Afrin Badhan, Mahmuda; Batalha, Natasha; Deming, Drake; Domagal-Goldman, Shawn; HEBRARD, Eric; Kopparapu, Ravi Kumar; Irwin, Patrick Gerard Joseph

2016-10-01

Unique and exotic planets give us an opportunity to understand how planetary systems form and evolve over their lifetime, by placing our own planetary system in the context of the vastly different extrasolar systems that are being continually discovered by present space missions. With orbital separations that are less than one-tenth of the Mercury-Sun distance, these close-in planets provide us with valuable insights about the host stellar atmosphere and planetary atmospheres subjected to their enormous stellar insolation. Observed spectroscopic signatures reveal all spectrally active species in a planet, along with information about its thermal structure and dynamics, allowing us to characterize the planet's atmosphere. NASA's upcoming missions will give us the high-resolution spectra necessary to constrain the atmospheric properties with unprecedented accuracy. However, to interpret the observed signals from exoplanetary transit events with any certainty, we need reliable atmospheric retrieval tools that can model the expected observables adequately. In my work thus far, I have built a Markov Chain Monte Carlo (MCMC) convergence scheme, with an analytical radiative equilibrium formulation for the thermal structures, within the NEMESIS atmospheric modeling tool, to allow sufficient (and efficient) exploration of the parameter space. I also augmented the opacity tables to improve the speed and reliability of retrieval models. I then utilized this upgraded version to infer the pressure-temperature (P-T) structures and volume-mixing ratios (VMRs) of major gas species in hot Jupiter dayside atmospheres, from their emission spectra. I have employed a parameterized thermal structure to retrieve plausible P-T profiles, along with altitude-invariant VMRs. Here I show my retrieval results on published datasets of HD189733b, and compare them with both medium and high spectral resolution JWST/NIRSPEC simulations. In preparation for the upcoming JWST mission, my current work

Atmospheric Renewable Energy Research, Volume 3: Solar-Power Microgrids and Atmospheric Influences

Science.gov (United States)

2016-09-01

1.2 DOD Renewable Energy Applications 1 1.3 Atmospheric Renewable Energy Research Strategy 2 1.4 Microgrid Definitions 3 1.4.1 Mobile Microgrid 4...1.4.2 Hybrid Microgrid 4 1.4.3 Smart Microgrid 4 1.5 Long-Term Atmospheric Renewable Energy Research Vision 5 2. Atmospheric Dependencies 5 2.1...developed-for-Army “ smart ” mobile hybrid microgrid that will incorporate both traditional and renewable energy power resources. A significant

Study of a dual frequency atmospheric pressure corona plasma

International Nuclear Information System (INIS)

Kim, Dan Bee; Moon, S. Y.; Jung, H.; Gweon, B.; Choe, Wonho

2010-01-01

Radio frequency mixing of 2 and 13.56 MHz was investigated by performing experimental measurements on the atmospheric pressure corona plasma. As a result of the dual frequency, length, current density, and electron excitation temperature of the plasma were increased, while the gas temperature was maintained at roughly the same level when compared to the respective single frequency plasmas. Moreover, observation of time-resolved images revealed that the dual frequency plasma has a discharge mode of 2 MHz positive streamer, 2 MHz negative glow, and 13.56 MHz continuous glow.

GENERATION OF GROUND ATMOSPHERE α-, β- AND γ-FIELDS BY NATURAL ATMOSPHERIC RADIONUCLIDES

Directory of Open Access Journals (Sweden)

V.S. Yakovleva

2014-06-01

Full Text Available The results of numerical investigation of influence of atmospheric turbulence, wind speed and direction as well as radon and thoron flux density from the soil on characteristics of atmospheric α-, β- and γ-radiation fields, which created by atmospheric radon, thoron and their short-lived decay products, are represented and analyzed in the work. It was showed that variation of radon and thoron flux densities from the earth surface changes yields and flux densities of α-, β- and γ-radiation in the ground atmosphere proportionally but does not change a form of their vertical profile.

Genotoxic and antigenotoxic properties of selenium compounds in the in vitro micronucleus assay with human whole blood lymphocytes and tk6 lymphoblastoid cells

Directory of Open Access Journals (Sweden)

Eduard Cemeli

2006-01-01

Full Text Available Selenium is known to possess both genotoxic and antigenotoxic properties. In the present study, we have evaluated the genotoxicity and antigenotoxicity of three selenium compounds (sodium selenate, sodium selenite and selenous acid by measuring in vitro micronucleus induction. Assays were conducted in whole blood lymphocytes and in the TK6 lymphoblastoid cell line, with and without co-treatment with potassium dichromate, a known genotoxic compound. In general, the compounds were more active in TK6 cells than they were in blood lymphocytes. Only 1 μM selenous acid increased the frequency of binucleated cells containing micronuclei (BNMN in blood lymphocytes, while all three selenium compounds increased BNMN in TK6 cells. In addition, combinations of selenous acid and potassium dichromate resulted in lower frequencies of BNMN than potassium dichromate alone in blood lymphocytes, while combinations of sodium selenate and potassium dichromate produced lower frequencies of BNMN than potassium dichromate alone in TK6 cells. The concentrations of selenium compounds that were used, in combination with the medium components and the biological physiology of the whole blood lymphocytes and TK6 cells, could have affected the redox potential of the compounds, switching the chemicals from a pro-oxidant to antioxidant status and vice-versa. The lower activities of the compounds in blood lymphocytes may be due to the protective effects of blood components. The results indicate that the genotoxic and antigenotoxic properties of selenium compounds are highly dependent upon the conditions under which they are evaluated.

Uranium and selenium resistance in Cupriavidus metallidurans CH34

International Nuclear Information System (INIS)

Avoscan, L.; Untereiner, G.; Carriere, M.; Gouget, B.; Degrouard, J.

2007-01-01

Cupriavidus metallidurans CH34, a soil bacterium, is known to resist a variety of heavy metals and metalloids. Its capacity to resist, accumulate and transform selenium (Se as selenite or selenate) and uranium (U as uranyl-carbonate and uranyl-citrate) was investigated. C. metallidurans CH34 resists to high U concentrations (up to 10 mM) whatever its speciation. However, no major accumulation could be measured: U-carbonate and U-citrate are not bio-available for the bacteria. The anaerobic response of C. metallidurans CH34 to U will be looked for. C. metallidurans CH34 resists to high Se concentrations (up to 4 mM of selenite and 8 mM of selenate). Bacteria exposed to 2 mM of selenite accumulate 25 times more Se than when they are exposed to same concentration of selenate. Se resistance is characterized by the reduction of oxy-anions in the bacteria. Selenite is reduced to elemental Se by an intracellular process, but the metabolic fate of selenate is unknown. By combining three methods of speciation (X-ray absorption spectroscopy (XANES and EXAFS), HPLC-ICP-MS and SDS-PAGE coupled with particle induced X-ray emission (PIXE)), we both identified and specified the chemical intermediates formed by this bacterium upon exposure to these oxy-anions. Two mechanisms of reduction of Se oxides in C. metallidurans CH34 were highlighted. Assimilation transforms selenite and selenate into organic Se, identified as seleno-methionine and leads to its non-specific incorporation into bacterial proteins (presence of selenious proteins). Detoxication precipitates selenite in nano-particles of elemental Se. (authors)

Atmosphere-Ionosphere Electrodynamic Coupling

Science.gov (United States)

Sorokin, V. M.; Chmyrev, V. M.

Numerous phenomena that occur in the mesosphere, ionosphere, and the magnetosphere of the Earth are caused by the sources located in the lower atmosphere and on the ground. We describe the effects produced by lightning activity and by ground-based transmitters operated in high frequency (HF) and very low frequency (VLF) ranges. Among these phenomena are the ionosphere heating and the formation of plasma density inhomogeneities, the excitation of gamma ray bursts and atmospheric emissions in different spectral bands, the generation of ULF/ELF/VLF electromagnetic waves and plasma turbulence in the ionosphere, the stimulation of radiation belt electron precipitations and the acceleration of ions in the upper ionosphere. The most interesting results of experimental and theoretical studies of these phenomena are discussed below. The ionosphere is subject to the action of the conductive electric current flowing in the atmosphere-ionosphere circuit. We present a physical model of DC electric field and current formation in this circuit. The key element of this model is an external current, which is formed with the occurrence of convective upward transport of charged aerosols and their gravitational sedimentation in the atmosphere. An increase in the level of atmospheric radioactivity results in the appearance of additional ionization and change of electrical conductivity. Variation of conductivity and external current in the lower atmosphere leads to perturbation of the electric current flowing in the global atmosphere-ionosphere circuit and to the associated DC electric field perturbation both on the Earth's surface and in the ionosphere. Description of these processes and some results of the electric field and current calculations are presented below. The seismic-induced electric field perturbations produce noticeable effects in the ionosphere by generating the electromagnetic field and plasma disturbances. We describe the generation mechanisms of such experimentally

ATMOSPHERIC DYNAMICS OF TERRESTRIAL EXOPLANETS OVER A WIDE RANGE OF ORBITAL AND ATMOSPHERIC PARAMETERS

Energy Technology Data Exchange (ETDEWEB)

Kaspi, Yohai [Department of Earth and Planetary Sciences, Weizmann Institute of Science, 234 Herzl st., 76100, Rehovot (Israel); Showman, Adam P., E-mail: yohai.kaspi@weizmann.ac.il [Department of Planetary Sciences and Lunar and Planetary Laboratory, The University of Arizona, 1629 University Blvd., Tucson, AZ 85721 (United States)

2015-05-01

The recent discoveries of terrestrial exoplanets and super-Earths extending over a broad range of orbital and physical parameters suggest that these planets will span a wide range of climatic regimes. Characterization of the atmospheres of warm super-Earths has already begun and will be extended to smaller and more distant planets over the coming decade. The habitability of these worlds may be strongly affected by their three-dimensional atmospheric circulation regimes, since the global climate feedbacks that control the inner and outer edges of the habitable zone—including transitions to Snowball-like states and runaway-greenhouse feedbacks—depend on the equator-to-pole temperature differences, patterns of relative humidity, and other aspects of the dynamics. Here, using an idealized moist atmospheric general circulation model including a hydrological cycle, we study the dynamical principles governing the atmospheric dynamics on such planets. We show how the planetary rotation rate, stellar flux, atmospheric mass, surface gravity, optical thickness, and planetary radius affect the atmospheric circulation and temperature distribution on such planets. Our simulations demonstrate that equator-to-pole temperature differences, meridional heat transport rates, structure and strength of the winds, and the hydrological cycle vary strongly with these parameters, implying that the sensitivity of the planet to global climate feedbacks will depend significantly on the atmospheric circulation. We elucidate the possible climatic regimes and diagnose the mechanisms controlling the formation of atmospheric jet streams, Hadley and Ferrel cells, and latitudinal temperature differences. Finally, we discuss the implications for understanding how the atmospheric circulation influences the global climate.

ATMOSPHERIC DYNAMICS OF TERRESTRIAL EXOPLANETS OVER A WIDE RANGE OF ORBITAL AND ATMOSPHERIC PARAMETERS

International Nuclear Information System (INIS)

Kaspi, Yohai; Showman, Adam P.

2015-01-01

The recent discoveries of terrestrial exoplanets and super-Earths extending over a broad range of orbital and physical parameters suggest that these planets will span a wide range of climatic regimes. Characterization of the atmospheres of warm super-Earths has already begun and will be extended to smaller and more distant planets over the coming decade. The habitability of these worlds may be strongly affected by their three-dimensional atmospheric circulation regimes, since the global climate feedbacks that control the inner and outer edges of the habitable zone—including transitions to Snowball-like states and runaway-greenhouse feedbacks—depend on the equator-to-pole temperature differences, patterns of relative humidity, and other aspects of the dynamics. Here, using an idealized moist atmospheric general circulation model including a hydrological cycle, we study the dynamical principles governing the atmospheric dynamics on such planets. We show how the planetary rotation rate, stellar flux, atmospheric mass, surface gravity, optical thickness, and planetary radius affect the atmospheric circulation and temperature distribution on such planets. Our simulations demonstrate that equator-to-pole temperature differences, meridional heat transport rates, structure and strength of the winds, and the hydrological cycle vary strongly with these parameters, implying that the sensitivity of the planet to global climate feedbacks will depend significantly on the atmospheric circulation. We elucidate the possible climatic regimes and diagnose the mechanisms controlling the formation of atmospheric jet streams, Hadley and Ferrel cells, and latitudinal temperature differences. Finally, we discuss the implications for understanding how the atmospheric circulation influences the global climate

Study of atmospheric tritium transfers in lettuce: kinetic study, equilibrium and organic incorporation during a continuous atmospheric exposure

International Nuclear Information System (INIS)

Boyer, C.

2009-01-01

This thesis has explored the mechanisms of tritium 'absorption and incorporation in a human-consumed plant, lettuce (Lactuca sativa L.), due to atmospheric exposure. Foliar uptake appears to play a key role in absorption of tritium as tissue free water tritium. Whatever the development stage and the light conditions, the specific activity in tissue free water reaches that of water vapour in air in several hours. The specific activity ratio is then about 0, 4. The time to reach equilibrium in soil is over 24 hours in most cases: the specific activity ratio ranges then 0, 01 to 0, 26. Incorporation rate of tissue free water tritium as organically-bound tritium has been estimated to 0, 13 to 0, 16 % h-l in average over the growing period of the plant, but marked variations are observed during growth. In particular, a significant increase appeared at the exponential growth stage. Deposition and diffusion of tritium in soil lead to significant OBT activities in soil. Results globally indicate equilibrium between the different environmental compartments (air, soil, plant). However, some experiments have revealed high OBT concentrations regarding atmospheric level exposure and ask for a possible phenomenon of local tritium accumulation in OBT for particular conditions of exposure. (author) [fr

A high-resolution mass spectrometer to measure atmospheric ion composition

Directory of Open Access Journals (Sweden)

H. Junninen

2010-08-01

Full Text Available In this paper we present recent achievements on developing and testing a tool to detect the composition of ambient ions in the mass/charge range up to 2000 Th. The instrument is an Atmospheric Pressure Interface Time-of-Flight Mass Spectrometer (APi-TOF, Tofwerk AG. Its mass accuracy is better than 0.002%, and the mass resolving power is 3000 Th/Th. In the data analysis, a new efficient Matlab based set of programs (tofTools were developed, tested and used. The APi-TOF was tested both in laboratory conditions and applied to outdoor air sampling in Helsinki at the SMEAR III station. Transmission efficiency calibrations showed a throughput of 0.1–0.5% in the range 100–1300 Th for positive ions, and linearity over 3 orders of magnitude in concentration was determined. In the laboratory tests the APi-TOF detected sulphuric acid-ammonia clusters in high concentration from a nebulised sample illustrating the potential of the instrument in revealing the role of sulphuric acid clusters in atmospheric new particle formation. The APi-TOF features a high enough accuracy, resolution and sensitivity for the determination of the composition of atmospheric small ions although the total concentration of those ions is typically only 400–2000 cm⁻³. The atmospheric ions were identified based on their exact masses, utilizing Kendrick analysis and correlograms as well as narrowing down the potential candidates based on their proton affinities as well isotopic patterns. In Helsinki during day-time the main negative ambient small ions were inorganic acids and their clusters. The positive ions were more complex, the main compounds were (polyalkyl pyridines and – amines. The APi-TOF provides a near universal interface for atmospheric pressure sampling, and this key feature will be utilized in future laboratory and field studies.

Waterspout as a special type of atmospheric aerosol dusty plasma

Science.gov (United States)

Rantsev-Kartinov, Valentin A.

2004-11-01

An analysis of databases of photographic images of oceanic surface revealed the presence of oceanic skeletal structures (OSS) [1] Rantsev-Kartinov V.A., Preprint . The OSSs presumably differ from the formerly found skeletal structures (SS) (Phys. Lett. A 306 (2002) 175) only by the fact that OSS are filled in with the closely packed blocks of a smaller size, up to thin, tens of microns-sized capillaries. The SSs in the Earth atmosphere were suggested [1] to be produced during atmospheric electricity activity by the volcanic-born dust. The fall-out of such SSs on the oceanic surface is a material source of OSS. Here we suggest that an OSS block [1] in the form of vertically oriented floating cylinder may be a stimulator of waterspout (WS). The main body of WS may be interpreted as a special type of atmospheric aerosol dusty plasma, and WS column - as a long-lived filament, being formed in the process of electric breakdown between the cloud and oceanic surface. The charged water drops aerosol may behave similar to microdust and lift upward to the cloud by the electrostatic force. With such a capillary&;electrostatic model of WS, it appears possible to interpret many effects related to WS.

Nb-TiO{sub 2}/polymer hybrid solar cells with photovoltaic response under inert atmosphere conditions

Energy Technology Data Exchange (ETDEWEB)

Lira-Cantu, Monica; Khoda Siddiki, Mahbube; Munoz-Rojas, David; Amade, Roger [Centre d' Investigacio en Nanociencia i Nanotecnologia (CIN2, CSIC), Laboratory of Nanostructured Materials for Photovoltaic Energy, Campus UAB, Barcelona (Spain); Gonzalez-Pech, Natalia I. [Centre d' Investigacio en Nanociencia i Nanotecnologia (CIN2, CSIC), Laboratory of Nanostructured Materials for Photovoltaic Energy, Campus UAB, Barcelona (Spain); Instituto Tecnologico y de Estudios Superiores de Monterrey (ITESM), Ave. Eugenio Garza Sada, 64640 Monterrey, N.L. (Mexico)

2010-07-15

Hybrid Solar Cells (HSC) applying Nb-TiO{sub 2} in direct contact with a conducting organic polymer, MEH-PPV, show higher stability than the bare TiO{sub 2}-based HSC when analyzed under inert atmosphere conditions. IPCE analyses revealed that inert atmospheres affect directly the semiconductor oxide in the first stages of the analyses but photovoltaic performance stabilizes after several hours. A 20 wt% Nb-doped TiO{sub 2} presented the highest stability and photovoltaic properties. The behavior has been attributed to the solubility limit of Nb within the TiO{sub 2} beyond 20 wt% doping level where the co-existence of NbO{sub 2} is observed. The HSCs were analyzed under controlled N{sub 2} atmosphere and 1000 W/m{sup 2} (AM 1.5) irradiation. (author)

Selenium Sequestration in a Cationic Layered Rare Earth Hydroxide: A Combined Batch Experiments and EXAFS Investigation.

Science.gov (United States)

Zhu, Lin; Zhang, Linjuan; Li, Jie; Zhang, Duo; Chen, Lanhua; Sheng, Daopeng; Yang, Shitong; Xiao, Chengliang; Wang, Jianqiang; Chai, Zhifang; Albrecht-Schmitt, Thomas E; Wang, Shuao

2017-08-01

Selenium is of great concern owing to its acutely toxic characteristic at elevated dosage and the long-term radiotoxicity of 79 Se. The contents of selenium in industrial wastewater, agricultural runoff, and drinking water have to be constrained to a value of 50 μg/L as the maximum concentration limit. We reported here the selenium uptake using a structurally well-defined cationic layered rare earth hydroxide, Y 2 (OH) 5 Cl·1.5H 2 O. The sorption kinetics, isotherms, selectivity, and desorption of selenite and selenate on Y 2 (OH) 5 Cl·1.5H 2 O at pH 7 and 8.5 were systematically investigated using a batch method. The maximum sorption capacities of selenite and selenate are 207 and 124 mg/g, respectively, both representing the new records among those of inorganic sorbents. In the low concentration region, Y 2 (OH) 5 Cl·1.5H 2 O is able to almost completely remove selenium from aqueous solution even in the presence of competitive anions such as NO 3 - , Cl - , CO 3 2- , SO 4 2- , and HPO 4 2- . The resulting concentration of selenium is below 10 μg/L, well meeting the strictest criterion for the drinking water. The selenate on loaded samples could be desorbed by rinsing with concentrated noncomplexing NaCl solutions whereas complexing ligands have to be employed to elute selenite for the material regeneration. After desorption, Y 2 (OH) 5 Cl·1.5H 2 O could be reused to remove selenate and selenite. In addition, the sorption mechanism was unraveled by the combination of EDS, FT-IR, Raman, PXRD, and EXAFS techniques. Specifically, the selenate ions were exchanged with chloride ions in the interlayer space, forming outer-sphere complexes. In comparison, besides anion exchange mechanism, the selenite ions were directly bound to the Y 3+ center in the positively charged layer of [Y 2 (OH) 5 (H 2 O)] + through strong bidentate binuclear inner-sphere complexation, consistent with the observation of the higher uptake of selenite over selenate. The results presented in

ANALYTICAL MODELS OF EXOPLANETARY ATMOSPHERES. I. ATMOSPHERIC DYNAMICS VIA THE SHALLOW WATER SYSTEM

Energy Technology Data Exchange (ETDEWEB)

Heng, Kevin [Center for Space and Habitability, University of Bern, Sidlerstrasse 5, CH-3012 Bern (Switzerland); Workman, Jared, E-mail: kevin.heng@csh.unibe.ch, E-mail: jworkman@coloradomesa.edu [Colorado Mesa University, 1260 Kennedy Avenue, Grand Junction, CO 81501 (United States)

2014-08-01

Within the context of exoplanetary atmospheres, we present a comprehensive linear analysis of forced, damped, magnetized shallow water systems, exploring the effects of dimensionality, geometry (Cartesian, pseudo-spherical, and spherical), rotation, magnetic tension, and hydrodynamic and magnetic sources of friction. Across a broad range of conditions, we find that the key governing equation for atmospheres and quantum harmonic oscillators are identical, even when forcing (stellar irradiation), sources of friction (molecular viscosity, Rayleigh drag, and magnetic drag), and magnetic tension are included. The global atmospheric structure is largely controlled by a single key parameter that involves the Rossby and Prandtl numbers. This near-universality breaks down when either molecular viscosity or magnetic drag acts non-uniformly across latitude or a poloidal magnetic field is present, suggesting that these effects will introduce qualitative changes to the familiar chevron-shaped feature witnessed in simulations of atmospheric circulation. We also find that hydrodynamic and magnetic sources of friction have dissimilar phase signatures and affect the flow in fundamentally different ways, implying that using Rayleigh drag to mimic magnetic drag is inaccurate. We exhaustively lay down the theoretical formalism (dispersion relations, governing equations, and time-dependent wave solutions) for a broad suite of models. In all situations, we derive the steady state of an atmosphere, which is relevant to interpreting infrared phase and eclipse maps of exoplanetary atmospheres. We elucidate a pinching effect that confines the atmospheric structure to be near the equator. Our suite of analytical models may be used to develop decisively physical intuition and as a reference point for three-dimensional magnetohydrodynamic simulations of atmospheric circulation.

Hyperspectral material identification on radiance data using single-atmosphere or multiple-atmosphere modeling

Science.gov (United States)

Mariano, Adrian V.; Grossmann, John M.

2010-11-01

Reflectance-domain methods convert hyperspectral data from radiance to reflectance using an atmospheric compensation model. Material detection and identification are performed by comparing the compensated data to target reflectance spectra. We introduce two radiance-domain approaches, Single atmosphere Adaptive Cosine Estimator (SACE) and Multiple atmosphere ACE (MACE) in which the target reflectance spectra are instead converted into sensor-reaching radiance using physics-based models. For SACE, known illumination and atmospheric conditions are incorporated in a single atmospheric model. For MACE the conditions are unknown so the algorithm uses many atmospheric models to cover the range of environmental variability, and it approximates the result using a subspace model. This approach is sometimes called the invariant method, and requires the choice of a subspace dimension for the model. We compare these two radiance-domain approaches to a Reflectance-domain ACE (RACE) approach on a HYDICE image featuring concealed materials. All three algorithms use the ACE detector, and all three techniques are able to detect most of the hidden materials in the imagery. For MACE we observe a strong dependence on the choice of the material subspace dimension. Increasing this value can lead to a decline in performance.

Impact of annealing treatment before buffer layer deposition on Cu2ZnSn(S,Se)4 solar cells

International Nuclear Information System (INIS)

Hironiwa, Daisuke; Sakai, Noriyuki; Kato, Takuya; Sugimoto, Hiroki; Tang, Zeguo; Chantana, Jakapan; Minemoto, Takashi

2015-01-01

Cu 2 ZnSn(S,Se) 4 (CZTSSe) solar cells were fabricated with an annealing treatment before the deposition of buffer layers to improve their photovoltaic performance. The CZTSSe absorbers were produced by sulfurization and selenization of metallic precursors. The efficiency of the solar cells increased from 5.5% without the annealing treatment to 8.8% with the annealing treatment at a temperature of 200 °C before buffer layer fabrication. Photoluminescence (PL) measurements revealed that the density of defects in the CZTSSe absorber that acted as non-radiative recombination centers decreased with the annealing treatment. The PL peak intensity exhibited a linear relationship with the open circuit voltage and the fill factor. In addition, the carrier density and hole mobility of the CZTSSe absorbers, which were respectively investigated by capacitance-voltage and Hall effect measurements, increased with the annealing treatment, thus improving cell performance. - Highlights: • Cu 2 ZnSn(S,Se) 4 is fabricated by sulfurization and selenization. • The annealing treatment can effectively improve the cell performance. • The defect acting as recombination is decreased by annealing treatment. • Carrier density and hole mobility is increased by annealing treatment

ATMOSPHERIC RETRIEVAL FOR SUPER-EARTHS: UNIQUELY CONSTRAINING THE ATMOSPHERIC COMPOSITION WITH TRANSMISSION SPECTROSCOPY

International Nuclear Information System (INIS)

Benneke, Bjoern; Seager, Sara

2012-01-01

We present a retrieval method based on Bayesian analysis to infer the atmospheric compositions and surface or cloud-top pressures from transmission spectra of exoplanets with general compositions. In this study, we identify what can unambiguously be determined about the atmospheres of exoplanets from their transmission spectra by applying the retrieval method to synthetic observations of the super-Earth GJ 1214b. Our approach to inferring constraints on atmospheric parameters is to compute their joint and marginal posterior probability distributions using the Markov Chain Monte Carlo technique in a parallel tempering scheme. A new atmospheric parameterization is introduced that is applicable to general atmospheres in which the main constituent is not known a priori and clouds may be present. Our main finding is that a unique constraint of the mixing ratios of the absorbers and two spectrally inactive gases (such as N 2 and primordial H 2 + He) is possible if the observations are sufficient to quantify both (1) the broadband transit depths in at least one absorption feature for each absorber and (2) the slope and strength of the molecular Rayleigh scattering signature. A second finding is that the surface pressure or cloud-top pressure can be quantified if a surface or cloud deck is present at low optical depth. A third finding is that the mean molecular mass can be constrained by measuring either the Rayleigh scattering slope or the shapes of the absorption features, thus enabling one to distinguish between cloudy hydrogen-rich atmospheres and high mean molecular mass atmospheres. We conclude, however, that without the signature of molecular Rayleigh scattering—even with robustly detected infrared absorption features (>10σ)—there is no reliable way to tell from the transmission spectrum whether the absorber is a main constituent of the atmosphere or just a minor species with a mixing ratio of X abs < 0.1%. The retrieval method leads us to a conceptual picture

The origin of atmosphere

International Nuclear Information System (INIS)

Marx, Gy.

1975-01-01

The evolution of the atmosphere of the Earth is described. Starting from the hot Universe the main steps of the ''cooling-down'' process as the different states of the condensation of the matter are discussed. After this nuclear evolution the chemical evolution could start on the solid Earth's crust. In the reductive primordial atmosphere mainly due to ultraviolet rays the basic molecules for life as sugars and amino acids were formed. The photosynthesis of the plants has later produced the oxygen being present in the recent atmosphere. The question whether the pollution could affect the auto-stabilization loop of the atmosphere is also discussed. Finally the possibility of life on the Mars is studied. (Sz.Z.)

Atmospheric turbulence and diffusion research

International Nuclear Information System (INIS)

Hosker, R.P. Jr.

1993-01-01

The Atmospheric Turbulence and Diffusion Division (well known in the atmospheric dispersion community as the Atmospheric Turbulence and Diffusion Laboratory, ATDL) is one of several field facilities of NOAAs Air Resources Laboratory, headquartered in Silver Spring, Maryland. The laboratory conducts research on matters of atmospheric diffusion and turbulent exchange, concerning air quality. ATDD focuses attention on the physics of the lower atmosphere, with special emphasis on the processes contributing to atmospheric transport, dispersion, deposition, and air-surface exchange, and on the development of predictive capabilities using the results of this research. Research is directed toward issues of national and global importance related to the missions of DOE, to DOE's Oak Ridge Field Office, and to NOAA. The program is divided into four major projects: plume transport and diffusion in the planetary boundary layer, complex topography, canopy micrometeorology, and air-surface exchange

Atmospheric bulk deposition of polycyclic aromatic hydrocarbons in Shanghai: Temporal and spatial variation, and global comparison.

Science.gov (United States)

Feng, Daolun; Liu, Ying; Gao, Yi; Zhou, Jinxing; Zheng, Lirong; Qiao, Gang; Ma, Liming; Lin, Zhifen; Grathwohl, Peter

2017-11-01

Atmospheric deposition leads to accumulation of atmospheric polycyclic aromatic hydrocarbons (PAHs) on urban surfaces and topsoils. To capture the inherent variability of atmospheric deposition of PAHs in Shanghai's urban agglomeration, 85 atmospheric bulk deposition samples and 7 surface soil samples were collected from seven sampling locations during 2012-2014. Total fluxes of 17 PAHs were 587-32,300 ng m -2 day -1 , with a geometric mean of 2600 ng m -2 day -1 . The deposition fluxes were categorized as moderate to high on a global scale. Phenanthrene, fluoranthene and pyrene were major contributors. The spatial distribution of deposition fluxes revealed the influence of urbanization/industrialization and the relevance of local emissions. Meteorological conditions and more heating demand in cold season lead to a significant increase of deposition rates. Atmospheric deposition is the principal pathway of PAHs input to topsoils and the annual deposition load in Shanghai amounts to ∼4.5 tons (0.7 kg km -2 ) with a range of 2.5-10 tons (0.4-1.6 kg km -2 ). Copyright © 2017 Elsevier Ltd. All rights reserved.

A global perspective on atmospheric blocking using GPS radio occultation – one decade of observations

Directory of Open Access Journals (Sweden)

L. Brunner

2017-12-01

Full Text Available Atmospheric blocking represents a weather pattern where a stationary high-pressure system weakens or reverses the climatological westerly flow at mid-latitudes for up to several weeks. It is closely connected to strong anomalies in key atmospheric variables such as geopotential height, temperature, and humidity. Here we provide, for the first time, a comprehensive, global perspective on atmospheric blocking and related impacts by using an observation-based data set from Global Positioning System (GPS radio occultation (RO from 2006 to 2016. The main blocking regions in both hemispheres and seasonal variations are found to be represented well in RO data. The effect of blocking on vertically resolved temperature and humidity anomalies in the troposphere and lower stratosphere is investigated for blocking regions in the Northern and Southern hemispheres, respectively. We find a statistically significant correlation of blocking with positive temperature anomalies, exceeding 3 K in the troposphere, and a reversal above the tropopause with negative temperature anomalies below −3 K in the lower stratosphere. Specific humidity is positively correlated with temperature throughout the troposphere with larger anomalies revealed in the Southern Hemisphere. At the eastern and equatorward side of the investigated blocking regions, a band of tropospheric cold anomalies reveals advection of cold air by anticyclonic motion around blocking highs, which is less distinct in the Southern Hemisphere due to stronger zonal flow. We find GPS RO to be a promising new data set for blocking research that gives insight into the vertical atmospheric structure, especially in light of the expected increase in data coverage that future missions will provide.

Turbulent jet diffusion flame length evolution with cross flows in a sub-pressure atmosphere

International Nuclear Information System (INIS)

Wang, Qiang; Hu, Longhua; Zhang, Xiaozheng; Zhang, Xiaolei; Lu, Shouxiang; Ding, Hang

2015-01-01

Highlights: • Quantifying turbulent jet diffusion flame length with cross flows. • Unique data revealed for a sub-atmospheric pressure. • Non-dimensional global correlation proposed for flame trajectory-line length. - Abstract: This paper investigates the evolution characteristics of turbulent jet diffusion flame (flame trajectory-line length, flame height in vertical jet direction) with increasing cross flows in a sub-pressure (64 kPa) atmosphere. The combined effect of cross flow and a special sub-pressure atmosphere condition is revealed, where no data is available in the literatures. Experiments are carried out with a wind tunnel built specially in Lhasa city (altitude: 3650 m; pressure: 64 kPa) and in Hefei city (altitude: 50 m; pressure: 100 kPa), using nozzles with diameter of 3 mm, 4 mm and 5 mm and propane as fuel. It is found that, as cross flow air speed increases from zero, the flame trajectory-line length firstly decreases and then becomes almost stable (for relative small nozzle, 3 mm in this study) or increases (for relative large nozzle, 4 mm and 5 mm in this study) beyond a transitional critical cross flow air speed in normal pressure, however decreases monotonically until being blown-out in the sub-pressure atmosphere. The flame height in jet direction decreases monotonically with cross air flow speed and then reaches a steady value in both pressures. For the transitional state of flame trajectory-line length with increasing cross air flow speed, the corresponding critical cross flow air speed is found to be proportional to the fuel jet velocity, meanwhile independent of nozzle diameter. Correlation models are proposed for the flame height in jet direction and the flame trajectory-line length for both ambient pressures, which are shown to be in good agreement with the experimental results.

Atmospheric thermodynamics

CERN Document Server

Iribarne, J V

1973-01-01

The thermodynamics of the atmosphere is the subject of several chapters in most textbooks on dynamic meteorology, but there is no work in English to give the subject a specific and more extensive treatment. In writing the present textbook, we have tried to fill this rather remarkable gap in the literature related to atmospheric sciences. Our aim has been to provide students of meteorology with a book that can playa role similar to the textbooks on chemical thermodynamics for the chemists. This implies a previous knowledge of general thermodynamics, such as students acquire in general physics courses; therefore, although the basic principles are reviewed (in the first four chapters), they are only briefly discussed, and emphasis is laid on those topics that will be useful in later chapters, through their application to atmospheric problems. No attempt has been made to introduce the thermodynamics of irreversible processes; on the other hand, consideration of heterogeneous and open homogeneous systems permits a...

Controlled Atmosphere Stunning

NARCIS (Netherlands)

Lambooij, E.; Gerritzen, M.A.

2009-01-01

Controlled atmosphere (CAS) stunning includes several variations of gaseous mixtures given to induce an anaesthetic state before slaughter poultry. One method of multi phase CAS is to unload the birds out of the crate on a conveyor belt and subject the birds to an atmosphere of 30% O2, 40% CO2 and

On The Implications of Atmospheric Gravity Waves on Wind Power

OpenAIRE

Norris, Luke

2011-01-01

In view of the rapidly rising cost of fossil fuels and concerns over climate change, there can be little doubt that renewable energy is to play a large role in the future of our economic development. The impact of Atmospheric Gravity Waves (AGWs) on wind power is, at best, unclear. In this research, AGWs are successfully modelled both in theoretical and real world environments using the WindSim software package which has revealed a potential 7.4% drop in annual power output as a direct ...

Phytoremediation of Atmospheric Methane

Science.gov (United States)

2013-04-15

REPORT Phytoremediation of Atmospheric Methane 14. ABSTRACT 16. SECURITY CLASSIFICATION OF: We have transformed a plant, Arabidopsis thaliana, with the...298 (Rev 8/98) Prescribed by ANSI Std. Z39.18 - 31-Mar-2012 Phytoremediation of Atmospheric Methane Report Title ABSTRACT We have transformed a...DD882) Scientific Progress See attachment Technology Transfer 1    Final Report for DARPA project W911NF1010027  Phytoremediation  of Atmospheric

Planetary Surface-Atmosphere Interactions

Science.gov (United States)

Merrison, J. P.; Bak, E.; Finster, K.; Gunnlaugsson, H. P.; Holstein-Rathlou, C.; Knak Jensen, S.; Nørnberg, P.

2013-09-01

Planetary bodies having an accessible solid surface and significant atmosphere, such as Earth, Mars, Venus, Titan, share common phenomenology. Specifically wind induced transport of surface materials, subsequent erosion, the generation and transport of solid aerosols which leads both to chemical and electrostatic interaction with the atmosphere. How these processes affect the evolution of the atmosphere and surface will be discussed in the context of general planetology and the latest laboratory studies will be presented.

Mars - CO2 adsorption and capillary condensation on clays: Significance for volatile storage and atmospheric history

Science.gov (United States)

Fanale, F. P.; Cannon, W. A.

1979-01-01

Results on the adsorbate-adsorbent system CO2-nontronite are reported at 230, 196, and 158 deg K, covering the range of subsurface regolith temperature on Mars. A three-part regolith-atmosphere-cap model reveals that cold nontronite, and expanding clays in general, are far better but far more complex CO2 adsorbers than cold pulverized basalt. In addition, the layered terrain, and possibly the adjacent debris mantle, contains about 2% or more by mass of atmosphere-exchangeable CO2 and the total regolith inventory of available adsorbed CO2 is estimated to be 400 g/ sq cm.

Investigation of the influence of atmospheric stability and turbulence on land-atmosphere exchange

Science.gov (United States)

Osibanjo, O.; Holmes, H.

2015-12-01

Surface energy fluxes are exchanged between the surface of the earth and the atmosphere and impact weather, climate, and air quality. The radiation from the sun triggers the surface-atmosphere interaction during the day as heat is transmitted to the surface and the surface heats the air directly above generating wind (i.e., thermal turbulence) that transports heat, moisture, and momentum in the atmospheric boundary layer (ABL). This process is impacted by greenhouse gasses (i.e., water vapor, carbon dioxide and other trace gases) that absorb heat emitted by the earth's surface. The concentrations of atmospheric greenhouse gasses are increasing leading to changes in ABL dynamics as a result of the changing surface energy balance. The ABL processes are important to characterize because they are difficult to parameterize in global and regional scale atmospheric models. Empirical data can be collected using eddy covariance micrometeorological methods to measure turbulent fluxes (e.g., sensible heat, moisture, and CO2) and quantify the exchange between the surface and the atmosphere. The objective of this work is to calculate surface fluxes using observational data collected during one week in September 2014 from a monitoring site in Echo, Oregon. The site is located in the Columbia Basin with rolling terrain, irrigated farmland, and over 100 wind turbines. The 10m tower was placed in a small valley depression to isolate nighttime cold air pools. This work will present observations of momentum, sensible heat, moisture, and carbon dioxide fluxes from data collected at a sampling frequency of 10Hz at four heights. Atmospheric stability is determined using Monin-Obukov length and flux Richardson number, and the impact of stability on surface-atmosphere exchange is investigated. This work will provide a better understanding of surface fluxes and mixing, particularly during stable ABL periods, and the results can be used to compare with numerical models.

High resolution transmission spectroscopy as a diagnostic for Jovian exoplanet atmospheres: constraints from theoretical models

Energy Technology Data Exchange (ETDEWEB)

Kempton, Eliza M.-R. [Department of Physics, Grinnell College, Grinnell, IA 50112 (United States); Perna, Rosalba [Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY 11794 (United States); Heng, Kevin, E-mail: kemptone@grinnell.edu [University of Bern, Center for Space and Habitability, Sidlerstrasse 5, CH-3012 Bern (Switzerland)

2014-11-01

We present high resolution transmission spectra of giant planet atmospheres from a coupled three-dimensional (3D) atmospheric dynamics and transmission spectrum model that includes Doppler shifts which arise from winds and planetary motion. We model Jovian planets covering more than two orders of magnitude in incident flux, corresponding to planets with 0.9-55 day orbital periods around solar-type stars. The results of our 3D dynamical models reveal certain aspects of high resolution transmission spectra that are not present in simple one-dimensional (1D) models. We find that the hottest planets experience strong substellar to anti-stellar (SSAS) winds, resulting in transmission spectra with net blueshifts of up to 3 km s{sup –1}, whereas less irradiated planets show almost no net Doppler shifts. We find only minor differences between transmission spectra for atmospheres with temperature inversions and those without. Compared to 1D models, peak line strengths are significantly reduced for the hottest atmospheres owing to Doppler broadening from a combination of rotation (which is faster for close-in planets under the assumption of tidal locking) and atmospheric winds. Finally, high resolution transmission spectra may be useful in studying the atmospheres of exoplanets with optically thick clouds since line cores for very strong transitions should remain optically thick to very high altitude. High resolution transmission spectra are an excellent observational test for the validity of 3D atmospheric dynamics models, because they provide a direct probe of wind structures and heat circulation. Ground-based exoplanet spectroscopy is currently on the verge of being able to verify some of our modeling predictions, most notably the dependence of SSAS winds on insolation. We caution that interpretation of high resolution transmission spectra based on 1D atmospheric models may be inadequate, as 3D atmospheric motions can produce a noticeable effect on the absorption

Examining Model Atmospheric Particles Inside and Out

Science.gov (United States)

Wingen, L. M.; Zhao, Y.; Fairhurst, M. C.; Perraud, V. M.; Ezell, M. J.; Finlayson-Pitts, B. J.

2017-12-01

Atmospheric particles scatter incoming solar radiation and act as cloud condensation nuclei (CCN), thereby directly and indirectly affecting the earth's radiative balance and reducing visibility. These atmospheric particles may not be uniform in composition. Differences in the composition of a particle's outer surface from its core can arise during particle growth, (photo)chemical aging, and exchange of species with the gas phase. The nature of the surface on a molecular level is expected to impact growth mechanisms as well as their ability to act as CCN. Model laboratory particle systems are explored using direct analysis in real time-mass spectrometry (DART-MS), which is sensitive to surface composition, and contrasted with average composition measurements using high resolution, time-of-flight aerosol mass spectrometry (HR-ToF-AMS). Results include studies of the heterogeneous reactions of amines with solid dicarboxylic acid particles, which are shown to generate aminium dicarboxylate salts at the particle surface, leaving an unreacted core. Combination of both mass spectrometric techniques reveals a trend in reactivity of C3-C7 dicarboxylic acids with amines and allows calculation of the DART probe depth into the particles. The results of studies on additional model systems that are currently being explored will also be reported.

PROBING THE SOLAR ATMOSPHERE USING OSCILLATIONS OF INFRARED CO SPECTRAL LINES

International Nuclear Information System (INIS)

Penn, M. J.; Schad, T.; Cox, E.

2011-01-01

Oscillations were observed across the whole solar disk using the Doppler shift and line center intensity of spectral lines from the CO molecule near 4666 nm with the National Solar Observatory's McMath/Pierce solar telescope. Power, coherence, and phase spectra were examined, and diagnostic diagrams reveal power ridges at the solar global mode frequencies to show that these oscillations are solar p-modes. The phase was used to determine the height of formation of the CO lines by comparison with the IR continuum intensity phase shifts as measured in Kopp et al.; we find that the CO line formation height varies from 425 km μ > 0.5. The velocity power spectra show that while the sum of the background and p-mode power increases with height in the solar atmosphere as seen in previous work, the power in the p-modes only (background subtracted) decreases with height. The CO line center intensity weakens in regions of stronger magnetic fields, as does the p-mode oscillation power. Across most of the solar surface the phase shift is larger than the expected value of 90 0 for an adiabatic atmosphere. We fit the phase spectra at different disk positions with a simple atmospheric model to determine that the acoustic cutoff frequency is about 4.5 mHz with only small variations, but that the thermal relaxation frequency drops significantly from 2.7 to 0 mHz at these heights in the solar atmosphere.

Atmospheric effects on the photovoltaic performance of hybrid perovskite solar cells

KAUST Repository

Sheikh, Arif D.

2015-06-01

Organometal trihalide perovskite solar cells have recently attracted lots of attention in the photovoltaic community due to their escalating efficiency and solution processability. The most efficient organometallic mixed-halide sensitized solar cells often employ 2,2′7,7′-tetrakis-(N,N-di-p-methoxyphenyl-amine)-9,9′-spirobifluorene (spiro-MeOTAD) as the hole-transporting material. In this work, we investigated the effect of different atmospheric storage conditions, particularly vacuum, dry nitrogen, and dry air, on the photovoltaic performance of TiO2-CH3NH3PbI3-xClx-spiro-MeOTAD solar cells. We found that spin coating of spiro-MeOTAD in an oxygen atmosphere alone was not adequate to functionalize its hole-transport property completely, and our systematic experiments revealed that the device efficiency depends on the ambient atmospheric conditions during the drying process of spiro-MeOTAD. Complementary incident photon to current conversion efficiency (IPCE), light absorption and photoluminescence quenching measurements allowed us to attribute the atmosphere-dependent efficiency to the improved electronic characteristics of the solar cells. Furthermore, our Fourier transform infrared and electrical impedance measurements unambiguously detected modifications in the spiro-MeOTAD after the drying processes in different gas environments. Our findings demonstrate that proper oxidization and p-doping in functionalizing spiro-MeOTAD play a very critical role in determining device performance. These findings will facilitate the search for alternative hole-transporting materials in high-performance perovskite solar cells with long-term stability.

Structure of carbon monoxide time variations in the atmospheric thickness over Central Eurasia (Issyk Kul Monitoring Station)

Science.gov (United States)

Aref'ev, V. N.; Kashin, F. V.; Orozaliev, M. D.; Sizov, N. I.; Sinyakov, V. P.; Sorokina, L. I.

2013-03-01

The results of measurements of the CO content in the atmospheric thickness by the method of solar molecular-absorption spectroscopy are presented. Over 87 months of observations, the annual mean CO content decreased by ˜19% at a mean rate of changes equal to -(0.14 ± 0.02) atm cm per year. Maxima and minima of seasonal variations most often fall on February and September, respectively. The mean overall amplitude of changes in the CO content during the annual cycle is about 50% of the mean value. The Fourier analysis revealed variations in the CO composition with periods from 3 to 84 months. A simple statistical model satisfactorily describes time changes in the CO content in the atmospheric thickness. The results of measurements of the CO content in the atmospheric thickness are compared with the data of CO measurements in samples of surface air at stations of the Global Atmospheric Watch.

Dusk/dawn atmospheric asymmetries on tidally-locked satellites: O2 at Europa

Science.gov (United States)

Oza, Apurva V.; Johnson, Robert E.; Leblanc, François

2018-05-01

We use a simple analytic model to examine the effect of the atmospheric source properties on the spatial distribution of a volatile in a surface-bounded atmosphere on a satellite that is tidally-locked to its planet. Spatial asymmetries in the O2 exosphere of Europa observed using the Hubble Space Telescope appear to reveal on average a dusk enhancement in the near-surface ultraviolet auroral emissions. Since the hop distances in these ballistic atmospheres are small, we use a 1-D mass conservation equation to estimate the latitudinally-averaged column densities produced by suggested O2 sources. Although spatial asymmetries in the plasma flow and in the surface properties certainly affect the spatial distribution of the near-surface aurora, the dusk enhancements at Europa can be understood using a relatively simple thermally-dependent source. Such a source is consistent with the fact that radiolytically produced O2 permeates their porous regoliths and is not so sensitive to the local production rate from ice. The size of the shift towards dusk is determined by the ratio of the rotation rate and atmospheric loss rate. A thermally-dependent source emanating from a large reservoir of O2 permeating Europa's icy regolith is consistent with the suggestion that its subsurface ocean might be oxidized by subduction of such radiolytic products.

Atmospheric pollution. From processes to modelling

International Nuclear Information System (INIS)

Sportisse, B.

2008-01-01

Air quality, greenhouse effect, ozone hole, chemical or nuclear accidents.. All these phenomena are tightly linked to the chemical composition of atmosphere and to the atmospheric dispersion of pollutants. This book aims at supplying the main elements of understanding of 'atmospheric pollutions': stakes, physical processes involved, role of scientific expertise in decision making. Content: 1 - classifications and scales: chemical composition of the atmosphere, vertical structure, time scales (transport, residence); 2 - matter/light interaction: notions of radiative transfer, application to the Earth's atmosphere; 3 - some elements about the atmospheric boundary layer: notion of scales in meteorology, atmospheric boundary layer (ABL), thermal stratification and stability, description of ABL turbulence, elements of atmospheric dynamics, some elements about the urban climate; 4 - notions of atmospheric chemistry: characteristics, ozone stratospheric chemistry, ozone tropospheric chemistry, brief introduction to indoor air quality; 5 - aerosols, clouds and rains: aerosols and particulates, aerosols and clouds, acid rains and leaching; 6 - towards numerical simulation: equation of reactive dispersion, numerical methods for chemistry-transport models, numerical resolution of the general equation of aerosols dynamics (GDE), modern simulation chains, perspectives. (J.S.)

Atmospheres of Brown Dwarfs

Science.gov (United States)

Wang, Ruoyan; Seay, Christopher

2018-01-01

We construct a grid of brown dwarf model atmospheres spanning a wide range of atmospheric metallicity (0.3x ≤ met ≤ 100x), C/O ratios (0.25x ≤ C/O ≤ 2.5x), and cloud properties, encompassing atmospheres of effective temperatures 200 ≤ Teff ≤ 2400 K and gravities 2.5 ≤ log g ≤ 5.5. We produce the expected temperature-pressure profiles and emergent spectra from an atmosphere in radiative-convective equilibrium. We can then compare our predicted spectra to observations and retrieval results to aid in their predictions and influence future missions and telescopic observations. In our poster we briefly describe our modeling methodology and present our progress on model grid construction, spanning solar and subsolar C/O and metallicity.

Heat transfer in the atmosphere

NARCIS (Netherlands)

Oerlemans, J.

1982-01-01

The atmosphere is almost transparent to solar radiation and almost opaque to terrestrial radiation. This implies that in the mean the atmosphere cools while the earth's surface is heated. Convection in the lower atmosphere must therefore occur. The upward flux of energy associated with it

Siple Dome ice reveals two modes of millennial CO2 change during the last ice age

Science.gov (United States)

Ahn, Jinho; Brook, Edward J.

2014-01-01

Reconstruction of atmospheric CO2 during times of past abrupt climate change may help us better understand climate-carbon cycle feedbacks. Previous ice core studies reveal simultaneous increases in atmospheric CO2 and Antarctic temperature during times when Greenland and the northern hemisphere experienced very long, cold stadial conditions during the last ice age. Whether this relationship extends to all of the numerous stadial events in the Greenland ice core record has not been clear. Here we present a high-resolution record of atmospheric CO2 from the Siple Dome ice core, Antarctica for part of the last ice age. We find that CO2 does not significantly change during the short Greenlandic stadial events, implying that the climate system perturbation that produced the short stadials was not strong enough to substantially alter the carbon cycle. PMID:24781344

Understanding the formation and composition of hazes in planetary atmospheres that contain carbon monoxide

Science.gov (United States)

Hörst, S. M.; Yoon, Y. H.; Hicks, R. K.; Tolbert, M. A.

2012-09-01

Measurements from the Cassini Plasma Spectrometer (CAPS) have revealed the presence of molecules in Titan's ionosphere with masses in excess of hundreds of amu. Negative ions with mass/charge (m/z) up to 10,000 amu/q [1] and positive ions with m/z up to 400 amu/q [2] have been detected. CAPS has also observed O+ flowing into Titan's upper atmosphere [3], which appears to originate from Enceladus and is likely the source of oxygen bearing molecules in Titan's atmosphere [4]. The observed O+ is deposited in the region now known to contain large organic molecules. A recent Titan atmosphere simulation experiment has shown that incorporation of oxygen into Titan aerosol analogues results in the formation of all five nucleotide bases and the two smallest amino acids, glycine and alanine [5]. Similar chemical processes may have occurred in the atmosphere of the early Earth, or in the atmospheres of extrasolar planets; atmospheric aerosols may be an important source of the building blocks of life. Atmospheric aerosols play an important role in determining the radiation budget of an atmosphere and can also provide a wealth of organic material to the surface. The presence of atmospheric aerosols has been invoked to explain the relatively featureless spectrum of HD 189773b, including the lack of predicted atmospheric Na and K spectral lines [9]. The majority of the O+ precipitating into Titan's atmosphere forms CO (O(3P)+CH3 -> CO+H2+H) [4]. CO has also been detected in the atmospheres of a number of exoplanets including HD 189733b, HD 209458b, and WASP-12b [6-8]. It is therefore important to understand the role CO plays in the formation and composition of hazes in planetary atmospheres. Using a High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) (see e.g. [10]) we have obtained in situ composition measurements of aerosol particles (so-called "tholins") produced in N2/CH4/CO gas mixtures subjected to either FUV radiation (deuterium lamp, 115-400 nm) or a

Oscillations in stellar atmospheres

International Nuclear Information System (INIS)

Costa, A.; Ringuelet, A.E.; Fontenla, J.M.

1989-01-01

Atmospheric excitation and propagation of oscillations are analyzed for typical pulsating stars. The linear, plane-parallel approach for the pulsating atmosphere gives a local description of the phenomenon. From the local analysis of oscillations, the minimum frequencies are obtained for radially propagating waves. The comparison of the minimum frequencies obtained for a variety of stellar types is in good agreement with the observed periods of the oscillations. The role of the atmosphere in the globar stellar pulsations is thus emphasized. 7 refs

Future Atmospheric CO2 Concentration and Environmental Consequences for the Feed Market: a Consequential LCA

DEFF Research Database (Denmark)

Saxe, Henrik; Hamelin, Lorie; Hinrichsen, Torben

2014-01-01

that such altered chemical composition and crop yields would have for the production of pig feed. Results revealed, among others, that an extra European demand of pig feed under an atmospheric [CO2] of 550 μmole mole-1 would lead to ca. 6% less expansion of additional arable land worldwide, in comparison to feed...

Future atmospheric CO2 concentration and environmental consequences for the feed market: a consequential LCA

DEFF Research Database (Denmark)

Saxe, Henrik; Hamelin, Lorie; Hinrichsen, Torben

2014-01-01

that such altered chemical composition and crop yields would have for the production of pig feed. Results revealed, among others, that an extra European demand of pig feed under an atmospheric [CO2] of 550 μmole mole-1 would lead to ca. 6% less expansion of additional arable land worldwide, in comparison to feed...

Clouds and Hazes in Exoplanet Atmospheres

OpenAIRE

Marley, Mark S.; Ackerman, Andrew S.; Cuzzi, Jeffrey N.; Kitzmann, Daniel

2013-01-01

Clouds and hazes are commonplace in the atmospheres of solar system planets and are likely ubiquitous in the atmospheres of extrasolar planets as well. Clouds affect every aspect of a planetary atmosphere, from the transport of radiation, to atmospheric chemistry, to dynamics and they influence - if not control - aspects such as surface temperature and habitability. In this review we aim to provide an introduction to the role and properties of clouds in exoplanetary atmospheres. We consider t...

Evolution of Earth-like Extrasolar Planetary Atmospheres: Assessing the Atmospheres and Biospheres of Early Earth Analog Planets with a Coupled Atmosphere Biogeochemical Model.

Science.gov (United States)

Gebauer, S; Grenfell, J L; Stock, J W; Lehmann, R; Godolt, M; von Paris, P; Rauer, H

2017-01-01

Understanding the evolution of Earth and potentially habitable Earth-like worlds is essential to fathom our origin in the Universe. The search for Earth-like planets in the habitable zone and investigation of their atmospheres with climate and photochemical models is a central focus in exoplanetary science. Taking the evolution of Earth as a reference for Earth-like planets, a central scientific goal is to understand what the interactions were between atmosphere, geology, and biology on early Earth. The Great Oxidation Event in Earth's history was certainly caused by their interplay, but the origin and controlling processes of this occurrence are not well understood, the study of which will require interdisciplinary, coupled models. In this work, we present results from our newly developed Coupled Atmosphere Biogeochemistry model in which atmospheric O 2 concentrations are fixed to values inferred by geological evidence. Applying a unique tool (Pathway Analysis Program), ours is the first quantitative analysis of catalytic cycles that governed O 2 in early Earth's atmosphere near the Great Oxidation Event. Complicated oxidation pathways play a key role in destroying O 2 , whereas in the upper atmosphere, most O 2 is formed abiotically via CO 2 photolysis. The O 2 bistability found by Goldblatt et al. ( 2006 ) is not observed in our calculations likely due to our detailed CH 4 oxidation scheme. We calculate increased CH 4 with increasing O 2 during the Great Oxidation Event. For a given atmospheric surface flux, different atmospheric states are possible; however, the net primary productivity of the biosphere that produces O 2 is unique. Mixing, CH 4 fluxes, ocean solubility, and mantle/crust properties strongly affect net primary productivity and surface O 2 fluxes. Regarding exoplanets, different "states" of O 2 could exist for similar biomass output. Strong geological activity could lead to false negatives for life (since our analysis suggests that reducing gases

Urban atmospheric contamination

International Nuclear Information System (INIS)

Baldasano Jose, M.

1997-01-01

The problems of contamination are not only limited to this century, pale pathology evidences of the effects of the contamination of the air exist in interiors in the health of the old ones; the article mention the elements that configure the problem of the atmospheric contamination, atmospheric pollutants and emission sources, orography condition and effects induced by the urbanization process

Effects of selenium oxyanions on the white-rot fungus Phanerochaete chrysosporium

KAUST Repository

Espinosa-Ortiz, Erika J.

2014-10-24

The ability of Phanerochaete chrysosporium to reduce the oxidized forms of selenium, selenate and selenite, and their effects on the growth, substrate consumption rate, and pellet morphology of the fungus were assessed. The effect of different operational parameters (pH, glucose, and selenium concentration) on the response of P. chrysosporium to selenium oxyanions was explored as well. This fungal species showed a high sensitivity to selenium, particularly selenite, which inhibited the fungal growth and substrate consumption when supplied at 10 mg L−1 in the growth medium, whereas selenate did not have such a strong influence on the fungus. Biological removal of selenite was achieved under semi-acidic conditions (pH 4.5) with about 40 % removal efficiency, whereas less than 10 % selenium removal was achieved for incubations with selenate. P. chrysosporium was found to be a selenium-reducing organism, capable of synthesizing elemental selenium from selenite but not from selenate. Analysis with transmission electron microscopy, electron energy loss spectroscopy, and a 3D reconstruction showed that elemental selenium was produced intracellularly as nanoparticles in the range of 30–400 nm. Furthermore, selenite influenced the pellet morphology of P. chrysosporium by reducing the size of the fungal pellets and inducing their compaction and smoothness.

A glossary of atmospheric science

International Nuclear Information System (INIS)

1996-09-01

This book concentrates on the glossary of atmospheric science, which contains summary, for enactment and deliberation on choosing special glossary on atmospheric science in Korea, examiner for the glossary on atmospheric science, reference, explanatory notes and a lot of glossary on atmospheric science. It also has an appendix on commercial abbreviation, prefix, unit, wavelength and the number o vibrations of electromagnetic waves, ICAO classified catalogue on cloud, list of varietal cloud and list of local wind. It has explanation of the glossary in English, Korea, China and Japan.

Interaction of Titan's atmosphere with Saturn's magnetosphere

International Nuclear Information System (INIS)

Hartle, R.E.

1985-01-01

The Voyager 1 measurements made during the Titan flyby reveal that Saturn's rotating magnetospheric plasma interacts directly with Titan's neutral atmosphere and ionosphere. This results from the lack of an intrinsic magnetic field at Titan. The interaction induces a magnetosphere which deflects the flowing plasma around Titan and forms a plasma wake downstream. Within the tail of the induced magnetosphere, ions of ionospheric origin flow away from Titan. Just outside Titan's magnetosphere, a substantial ion-exosphere forms from an extensive hydrogen-nitrogen exosphere. The exospheric ions are picked up and carried downstream into the wake by the plasma flowing around Titan. Mass loading produced by the addition of exospheric ions slows the wake plasma down considerably in the vicinity of the magnetopause. 36 references

Screening and identification of efficient strain in selenium oxyanions sorption in order to biological wastewater treatment

Directory of Open Access Journals (Sweden)

fatemeh yaghoobizadeh

2016-06-01

Full Text Available Introduction: Selenium is an element with antioxidant activities that plays roles in thyroid hormone homeostasis, immunity and also fertility. Nevertheless, selenium toxicity (selenosis causes problems for humans such as abnormalities of the nervous system, gastrointestinal problems and hair loss. Thus, this study was performed with the aim of bacterial biosorbent isolation in order to remove selenium contaminant from wastewater. Materials and methods: In this research, at first using modified Luria- Bertani agar (mLBA medium with certain concentration of sodium selenate salt, isolation of bacterial isolates was done from three collected wastewater and sludge samples from Khouzestan industrial factories. After determination of minimum inhibitory concentration (MIC and minimum bactericidal concentration (MBC, the sorption capacity and the percentage of metal removal efficiency (%RE were investigated by atomic absorption spectrophotometer using metabolically active and inactive samples belonging to an efficient isolate. Identification was performed by morphological, biochemical and molecular methods. Results: Among 73 attained bacterial isolates at the first stage, 8 selenate oxyanion resistant isolates were gathered. Among these, AMS1-S8 isolate with MIC= 600­mM and MBC= 1200­mM were selected for more studies. Attained results in sorption mechanism determination stage showed that the sorption capacity in metabolically active sample is more than the inactive samples. Based on the identification results, it is revealed that this isolate belongs to the Enterobacter genus. This isolate is deposited as accession JQ965667 in the GeneBank database. Discussion and conclusion: The results showed that active biomass of selected isolate, have most sorption capacity and %RE and among the other isolates, have high partial resistance against selenate. Therefore, it can be a relatively ideal option for the bioremediation of polluted environments.

Atmospheric Research 2014 Technical Highlights

Science.gov (United States)

Platnick, Steven

2015-01-01

Atmospheric research in the Earth Sciences Division (610) consists of research and technology development programs dedicated to advancing knowledge and understanding of the atmosphere and its interaction with the climate of Earth. The Division's goals are to improve understanding of the dynamics and physical properties of precipitation, clouds, and aerosols; atmospheric chemistry, including the role of natural and anthropogenic trace species on the ozone balance in the stratosphere and the troposphere; and radiative properties of Earth's atmosphere and the influence of solar variability on the Earth's climate. Major research activities are carried out in the Mesoscale Atmospheric Processes Laboratory, the Climate and Radiation Laboratory, the Atmospheric Chemistry and Dynamics Laboratory, and the Wallops Field Support Office. The overall scope of the research covers an end-to-end process, starting with the identification of scientific problems, leading to observation requirements for remote-sensing platforms, technology and retrieval algorithm development; followed by flight projects and satellite missions; and eventually, resulting in data processing, analyses of measurements, and dissemination from flight projects and missions. Instrument scientists conceive, design, develop, and implement ultraviolet, infrared, optical, radar, laser, and lidar technology to remotely sense the atmosphere. Members of the various Laboratories conduct field measurements for satellite sensor calibration and data validation, and carry out numerous modeling activities. These modeling activities include climate model simulations, modeling the chemistry and transport of trace species on regional-to-global scales, cloud resolving models, and developing the next-generation Earth system models. Satellite missions, field campaigns, peer-reviewed publications, and successful proposals are essential at every stage of the research process to meeting our goals and maintaining leadership of the

Sulfur dioxide in the Venus atmosphere: I. Vertical distribution and variability

Science.gov (United States)

Vandaele, A. C.; Korablev, O.; Belyaev, D.; Chamberlain, S.; Evdokimova, D.; Encrenaz, Th.; Esposito, L.; Jessup, K. L.; Lefèvre, F.; Limaye, S.; Mahieux, A.; Marcq, E.; Mills, F. P.; Montmessin, F.; Parkinson, C. D.; Robert, S.; Roman, T.; Sandor, B.; Stolzenbach, A.; Wilson, C.; Wilquet, V.

2017-10-01

Recent observations of sulfur containing species (SO2, SO, OCS, and H2SO4) in Venus' mesosphere have generated controversy and great interest in the scientific community. These observations revealed unexpected spatial patterns and spatial/temporal variability that have not been satisfactorily explained by models. Sulfur oxide chemistry on Venus is closely linked to the global-scale cloud and haze layers, which are composed primarily of concentrated sulfuric acid. Sulfur oxide observations provide therefore important insight into the on-going chemical evolution of Venus' atmosphere, atmospheric dynamics, and possible volcanism. This paper is the first of a series of two investigating the SO2 and SO variability in the Venus atmosphere. This first part of the study will focus on the vertical distribution of SO2, considering mostly observations performed by instruments and techniques providing accurate vertical information. This comprises instruments in space (SPICAV/SOIR suite on board Venus Express) and Earth-based instruments (JCMT). The most noticeable feature of the vertical profile of the SO2 abundance in the Venus atmosphere is the presence of an inversion layer located at about 70-75 km, with VMRs increasing above. The observations presented in this compilation indicate that at least one other significant sulfur reservoir (in addition to SO2 and SO) must be present throughout the 70-100 km altitude region to explain the inversion in the SO2 vertical profile. No photochemical model has an explanation for this behaviour. GCM modelling indicates that dynamics may play an important role in generating an inflection point at 75 km altitude but does not provide a definitive explanation of the source of the inflection at all local times or latitudes The current study has been carried out within the frame of the International Space Science Institute (ISSI) International Team entitled 'SO2 variability in the Venus atmosphere'.

Atmospheric Research 2012 Technical Highlights

Science.gov (United States)

Lau, William K -M.

2013-01-01

This annual report, as before, is intended for a broad audience. Our readers include colleagues within NASA, scientists outside the Agency, science graduate students, and members of the general public. Inside are descriptions of atmospheric research science highlights and summaries of our education and outreach accomplishments for calendar year 2012.The report covers research activities from the Mesoscale Atmospheric Processes Laboratory, the Climate and Radiation Laboratory, the Atmospheric Chemistry and Dynamics Laboratory, and the Wallops Field Support Office under the Office of Deputy Director for Atmospheres, Earth Sciences Division in the Sciences and Exploration Directorate of NASAs Goddard Space Flight Center. The overall mission of the office is advancing knowledge and understanding of the Earths atmosphere. Satellite missions, field campaigns, peer-reviewed publications, and successful proposals are essential to our continuing research.

Solar flares and radiocarbon abundance in the atmosphere of the Earth

International Nuclear Information System (INIS)

Metskhvarishvili, R.Ya.; Imedadze, T.Sh.; Tleugaliev, S.Kh.; Tsinamdzgvrishvili, T.Sh.; Tsereteli, S.L.

1978-01-01

The correlation between the radiocarbon ( 14 C) content in the atmosphere of the Earth and the solar activity is studied. Annual measurements of the 14 C content in the tree rings for the last 120 years have been made. Relations of the radiocarbon content in dendrochronologically dated tree rings and the Wolf numbers for the period from 1850 to 1940 are presented. The spectroscopic and Borg methods have been used to ascertain the periodicities in the radiocarbon series. It is shown that well-defined periods of approximately 11 and approximately 65 years are observed in the radiocarbon series. The former is associated with an 11-year and the latter with a secular cycle of the 14 C content in the earth atmosphere. To study the relation of the solar activity to the level of radiocarbon in the earth atmosphere a mutual correlation function was calculated for various values of the time lags of 14 C with respect to the processes on the Sun. It follows from the data obtained that a positive correlation takes place for time lags smaller than three years. The detected positive correlation has revealed that the effect of solar flares in the 11-year cycle is prevalent

CARBON NEUTRON STAR ATMOSPHERES

International Nuclear Information System (INIS)

Suleimanov, V. F.; Klochkov, D.; Werner, K.; Pavlov, G. G.

2014-01-01

The accuracy of measuring the basic parameters of neutron stars is limited in particular by uncertainties in the chemical composition of their atmospheres. For example, the atmospheres of thermally emitting neutron stars in supernova remnants might have exotic chemical compositions, and for one of them, the neutron star in Cas A, a pure carbon atmosphere has recently been suggested by Ho and Heinke. To test this composition for other similar sources, a publicly available detailed grid of the carbon model atmosphere spectra is needed. We have computed this grid using the standard local thermodynamic equilibrium approximation and assuming that the magnetic field does not exceed 10 8  G. The opacities and pressure ionization effects are calculated using the Opacity Project approach. We describe the properties of our models and investigate the impact of the adopted assumptions and approximations on the emergent spectra

Isotope ratios of H, C, and O in CO2 and H2O of the martian atmosphere.

Science.gov (United States)

Webster, Chris R; Mahaffy, Paul R; Flesch, Gregory J; Niles, Paul B; Jones, John H; Leshin, Laurie A; Atreya, Sushil K; Stern, Jennifer C; Christensen, Lance E; Owen, Tobias; Franz, Heather; Pepin, Robert O; Steele, Andrew; Achilles, Cherie; Agard, Christophe; Alves Verdasca, José Alexandre; Anderson, Robert; Anderson, Ryan; Archer, Doug; Armiens-Aparicio, Carlos; Arvidson, Ray; Atlaskin, Evgeny; Aubrey, Andrew; Baker, Burt; Baker, Michael; Balic-Zunic, Tonci; Baratoux, David; Baroukh, Julien; Barraclough, Bruce; Bean, Keri; Beegle, Luther; Behar, Alberto; Bell, James; Bender, Steve; Benna, Mehdi; Bentz, Jennifer; Berger, Gilles; Berger, Jeff; Berman, Daniel; Bish, David; Blake, David F; Blanco Avalos, Juan J; Blaney, Diana; Blank, Jen; Blau, Hannah; Bleacher, Lora; Boehm, Eckart; Botta, Oliver; Böttcher, Stephan; Boucher, Thomas; Bower, Hannah; Boyd, Nick; Boynton, Bill; Breves, Elly; Bridges, John; Bridges, Nathan; Brinckerhoff, William; Brinza, David; Bristow, Thomas; Brunet, Claude; Brunner, Anna; Brunner, Will; Buch, Arnaud; Bullock, Mark; Burmeister, Sönke; Cabane, Michel; Calef, Fred; Cameron, James; Campbell, John; Cantor, Bruce; Caplinger, Michael; Caride Rodríguez, Javier; Carmosino, Marco; Carrasco Blázquez, Isaías; Charpentier, Antoine; Chipera, Steve; Choi, David; Clark, Benton; Clegg, Sam; Cleghorn, Timothy; Cloutis, Ed; Cody, George; Coll, Patrice; Conrad, Pamela; Coscia, David; Cousin, Agnès; Cremers, David; Crisp, Joy; Cros, Alain; Cucinotta, Frank; d'Uston, Claude; Davis, Scott; Day, Mackenzie; de la Torre Juarez, Manuel; DeFlores, Lauren; DeLapp, Dorothea; DeMarines, Julia; DesMarais, David; Dietrich, William; Dingler, Robert; Donny, Christophe; Downs, Bob; Drake, Darrell; Dromart, Gilles; Dupont, Audrey; Duston, Brian; Dworkin, Jason; Dyar, M Darby; Edgar, Lauren; Edgett, Kenneth; Edwards, Christopher; Edwards, Laurence; Ehlmann, Bethany; Ehresmann, Bent; Eigenbrode, Jen; Elliott, Beverley; Elliott, Harvey; Ewing, Ryan; Fabre, Cécile; Fairén, Alberto; Farley, Ken; Farmer, Jack; Fassett, Caleb; Favot, Laurent; Fay, Donald; Fedosov, Fedor; Feldman, Jason; Feldman, Sabrina; Fisk, Marty; Fitzgibbon, Mike; Floyd, Melissa; Flückiger, Lorenzo; Forni, Olivier; Fraeman, Abby; Francis, Raymond; François, Pascaline; Freissinet, Caroline; French, Katherine Louise; Frydenvang, Jens; Gaboriaud, Alain; Gailhanou, Marc; Garvin, James; Gasnault, Olivier; Geffroy, Claude; Gellert, Ralf; Genzer, Maria; Glavin, Daniel; Godber, Austin; Goesmann, Fred; Goetz, Walter; Golovin, Dmitry; Gómez Gómez, Felipe; Gómez-Elvira, Javier; Gondet, Brigitte; Gordon, Suzanne; Gorevan, Stephen; Grant, John; Griffes, Jennifer; Grinspoon, David; Grotzinger, John; Guillemot, Philippe; Guo, Jingnan; Gupta, Sanjeev; Guzewich, Scott; Haberle, Robert; Halleaux, Douglas; Hallet, Bernard; Hamilton, Vicky; Hardgrove, Craig; Harker, David; Harpold, Daniel; Harri, Ari-Matti; Harshman, Karl; Hassler, Donald; Haukka, Harri; Hayes, Alex; Herkenhoff, Ken; Herrera, Paul; Hettrich, Sebastian; Heydari, Ezat; Hipkin, Victoria; Hoehler, Tori; Hollingsworth, Jeff; Hudgins, Judy; Huntress, Wesley; Hurowitz, Joel; Hviid, Stubbe; Iagnemma, Karl; Indyk, Steve; Israël, Guy; Jackson, Ryan; Jacob, Samantha; Jakosky, Bruce; Jensen, Elsa; Jensen, Jaqueline Kløvgaard; Johnson, Jeffrey; Johnson, Micah; Johnstone, Steve; Jones, Andrea; Joseph, Jonathan; Jun, Insoo; Kah, Linda; Kahanpää, Henrik; Kahre, Melinda; Karpushkina, Natalya; Kasprzak, Wayne; Kauhanen, Janne; Keely, Leslie; Kemppinen, Osku; Keymeulen, Didier; Kim, Myung-Hee; Kinch, Kjartan; King, Penny; Kirkland, Laurel; Kocurek, Gary; Koefoed, Asmus; Köhler, Jan; Kortmann, Onno; Kozyrev, Alexander; Krezoski, Jill; Krysak, Daniel; Kuzmin, Ruslan; Lacour, Jean Luc; Lafaille, Vivian; Langevin, Yves; Lanza, Nina; Lasue, Jeremie; Le Mouélic, Stéphane; Lee, Ella Mae; Lee, Qiu-Mei; Lees, David; Lefavor, Matthew; Lemmon, Mark; Lepinette Malvitte, Alain; Léveillé, Richard; Lewin-Carpintier, Éric; Lewis, Kevin; Li, Shuai; Lipkaman, Leslie; Little, Cynthia; Litvak, Maxim; Lorigny, Eric; Lugmair, Guenter; Lundberg, Angela; Lyness, Eric; Madsen, Morten; Maki, Justin; Malakhov, Alexey; Malespin, Charles; Malin, Michael; Mangold, Nicolas; Manhes, Gérard; Manning, Heidi; Marchand, Geneviève; Marín Jiménez, Mercedes; Martín García, César; Martin, Dave; Martin, Mildred; Martínez-Frías, Jesús; Martín-Soler, Javier; Martín-Torres, F Javier; Mauchien, Patrick; Maurice, Sylvestre; McAdam, Amy; McCartney, Elaina; McConnochie, Timothy; McCullough, Emily; McEwan, Ian; McKay, Christopher; McLennan, Scott; McNair, Sean; Melikechi, Noureddine; Meslin, Pierre-Yves; Meyer, Michael; Mezzacappa, Alissa; Miller, Hayden; Miller, Kristen; Milliken, Ralph; Ming, Douglas; Minitti, Michelle; Mischna, Michael; Mitrofanov, Igor; Moersch, Jeff; Mokrousov, Maxim; Molina Jurado, Antonio; Moores, John; Mora-Sotomayor, Luis; Morookian, John Michael; Morris, Richard; Morrison, Shaunna; Mueller-Mellin, Reinhold; Muller, Jan-Peter; Muñoz Caro, Guillermo; Nachon, Marion; Navarro López, Sara; Navarro-González, Rafael; Nealson, Kenneth; Nefian, Ara; Nelson, Tony; Newcombe, Megan; Newman, Claire; Newsom, Horton; Nikiforov, Sergey; Nixon, Brian; Noe Dobrea, Eldar; Nolan, Thomas; Oehler, Dorothy; Ollila, Ann; Olson, Timothy; de Pablo Hernández, Miguel Ángel; Paillet, Alexis; Pallier, Etienne; Palucis, Marisa; Parker, Timothy; Parot, Yann; Patel, Kiran; Paton, Mark; Paulsen, Gale; Pavlov, Alex; Pavri, Betina; Peinado-González, Verónica; Peret, Laurent; Perez, Rene; Perrett, Glynis; Peterson, Joe; Pilorget, Cedric; Pinet, Patrick; Pla-García, Jorge; Plante, Ianik; Poitrasson, Franck; Polkko, Jouni; Popa, Radu; Posiolova, Liliya; Posner, Arik; Pradler, Irina; Prats, Benito; Prokhorov, Vasily; Purdy, Sharon Wilson; Raaen, Eric; Radziemski, Leon; Rafkin, Scot; Ramos, Miguel; Rampe, Elizabeth; Raulin, François; Ravine, Michael; Reitz, Günther; Rennó, Nilton; Rice, Melissa; Richardson, Mark; Robert, François; Robertson, Kevin; Rodriguez Manfredi, José Antonio; Romeral-Planelló, Julio J; Rowland, Scott; Rubin, David; Saccoccio, Muriel; Salamon, Andrew; Sandoval, Jennifer; Sanin, Anton; Sans Fuentes, Sara Alejandra; Saper, Lee; Sarrazin, Philippe; Sautter, Violaine; Savijärvi, Hannu; Schieber, Juergen; Schmidt, Mariek; Schmidt, Walter; Scholes, Daniel; Schoppers, Marcel; Schröder, Susanne; Schwenzer, Susanne; Sebastian Martinez, Eduardo; Sengstacken, Aaron; Shterts, Ruslan; Siebach, Kirsten; Siili, Tero; Simmonds, Jeff; Sirven, Jean-Baptiste; Slavney, Susie; Sletten, Ronald; Smith, Michael; Sobrón Sánchez, Pablo; Spanovich, Nicole; Spray, John; Squyres, Steven; Stack, Katie; Stalport, Fabien; Stein, Thomas; Stewart, Noel; Stipp, Susan Louise Svane; Stoiber, Kevin; Stolper, Ed; Sucharski, Bob; Sullivan, Rob; Summons, Roger; Sumner, Dawn; Sun, Vivian; Supulver, Kimberley; Sutter, Brad; Szopa, Cyril; Tan, Florence; Tate, Christopher; Teinturier, Samuel; ten Kate, Inge; Thomas, Peter; Thompson, Lucy; Tokar, Robert; Toplis, Mike; Torres Redondo, Josefina; Trainer, Melissa; Treiman, Allan; Tretyakov, Vladislav; Urqui-O'Callaghan, Roser; Van Beek, Jason; Van Beek, Tessa; VanBommel, Scott; Vaniman, David; Varenikov, Alexey; Vasavada, Ashwin; Vasconcelos, Paulo; Vicenzi, Edward; Vostrukhin, Andrey; Voytek, Mary; Wadhwa, Meenakshi; Ward, Jennifer; Weigle, Eddie; Wellington, Danika; Westall, Frances; Wiens, Roger Craig; Wilhelm, Mary Beth; Williams, Amy; Williams, Joshua; Williams, Rebecca; Williams, Richard B; Wilson, Mike; Wimmer-Schweingruber, Robert; Wolff, Mike; Wong, Mike; Wray, James; Wu, Megan; Yana, Charles; Yen, Albert; Yingst, Aileen; Zeitlin, Cary; Zimdar, Robert; Zorzano Mier, María-Paz

2013-07-19

Stable isotope ratios of H, C, and O are powerful indicators of a wide variety of planetary geophysical processes, and for Mars they reveal the record of loss of its atmosphere and subsequent interactions with its surface such as carbonate formation. We report in situ measurements of the isotopic ratios of D/H and (18)O/(16)O in water and (13)C/(12)C, (18)O/(16)O, (17)O/(16)O, and (13)C(18)O/(12)C(16)O in carbon dioxide, made in the martian atmosphere at Gale Crater from the Curiosity rover using the Sample Analysis at Mars (SAM)'s tunable laser spectrometer (TLS). Comparison between our measurements in the modern atmosphere and those of martian meteorites such as ALH 84001 implies that the martian reservoirs of CO2 and H2O were largely established ~4 billion years ago, but that atmospheric loss or surface interaction may be still ongoing.

Synthesis of nanoparticles in an atmospheric pressure glow discharge

International Nuclear Information System (INIS)

Barankin, M.D.; Creyghton, Y.; Schmidt-Ott, A.

2006-01-01

Nanopowders are produced in a low temperature, non-equilibrium plasma jet (APPJ), which produces a glow discharge at atmospheric pressure, for the first time. Amorphous carbon and iron nanoparticles have been synthesized from Acetylene and Ferrocene/H 2 , respectively. High generation rates are achieved from the glow discharge at near-ambient temperature (40-80 deg. C), and rise with increasing plasma power and precursor concentration. Fairly narrow particle size distributions are measured with a differential mobility analyzer (DMA) and an aerosol electrometer (AEM), and are centered around 30-35 nm for carbon and 20-25 nm for iron. Particle characteristics analyzed by TEM and EDX reveal amorphous carbon and iron nanoparticles. The Fe particles are highly oxidized on exposure to air. Comparison of the mobility and micrograph diameters reveal that the particles are hardly agglomerated or unagglomerated. This is ascribed to the unipolar charge on particles in the plasma. The generated particle distributions are examined as a function of process parameters

Atmospheric science and power production

Energy Technology Data Exchange (ETDEWEB)

Randerson, D. (ed.)

1984-07-01

This is the third in a series of scientific publications sponsored by the US Atomic Energy Commission and the two later organizations, the US Energy Research and Development Adminstration, and the US Department of Energy. The first book, Meteorology and Atomic Energy, was published in 1955; the second, in 1968. The present volume is designed to update and to expand upon many of the important concepts presented previously. However, the present edition draws heavily on recent contributions made by atmospheric science to the analysis of air quality and on results originating from research conducted and completed in the 1970s. Special emphasis is placed on how atmospheric science can contribute to solving problems relating to the fate of combustion products released into the atmosphere. The framework of this book is built around the concept of air-quality modeling. Fundamentals are addressed first to equip the reader with basic background information and to focus on available meteorological instrumentation and to emphasize the importance of data management procedures. Atmospheric physics and field experiments are described in detail to provide an overview of atmospheric boundary layer processes, of how air flows around obstacles, and of the mechanism of plume rise. Atmospheric chemistry and removal processes are also detailed to provide fundamental knowledge on how gases and particulate matter can be transformed while in the atmosphere and how they can be removed from the atmosphere. The book closes with a review of how air-quality models are being applied to solve a wide variety of problems. Separate analytics have been prepared for each chapter.

Deuterium in atmospheric cycle

International Nuclear Information System (INIS)

Pontikis, M.C.

Interest of the study concerning the deuterium content variation (HDO) in the atmospheric water. Standards and measurement methods. Molecule HDO cycle in the atmospheric water. Application to the study of hail-generating cumulus-nimbus and of the mantle of snow [fr

Intercomparison of atmospheric water vapour measurements at a Canadian High Arctic site

Science.gov (United States)

Weaver, Dan; Strong, Kimberly; Schneider, Matthias; Rowe, Penny M.; Sioris, Chris; Walker, Kaley A.; Mariani, Zen; Uttal, Taneil; McElroy, C. Thomas; Vömel, Holger; Spassiani, Alessio; Drummond, James R.

2017-08-01

Water vapour is a critical component of the Earth system. Techniques to acquire and improve measurements of atmospheric water vapour and its isotopes are under active development. This work presents a detailed intercomparison of water vapour total column measurements taken between 2006 and 2014 at a Canadian High Arctic research site (Eureka, Nunavut). Instruments include radiosondes, sun photometers, a microwave radiometer, and emission and solar absorption Fourier transform infrared (FTIR) spectrometers. Close agreement is observed between all combination of datasets, with mean differences ≤ 1.0 kg m-2 and correlation coefficients ≥ 0.98. The one exception in the observed high correlation is the comparison between the microwave radiometer and a radiosonde product, which had a correlation coefficient of 0.92.A variety of biases affecting Eureka instruments are revealed and discussed. A subset of Eureka radiosonde measurements was processed by the Global Climate Observing System (GCOS) Reference Upper Air Network (GRUAN) for this study. Comparisons reveal a small dry bias in the standard radiosonde measurement water vapour total columns of approximately 4 %. A recently produced solar absorption FTIR spectrometer dataset resulting from the MUSICA (MUlti-platform remote Sensing of Isotopologues for investigating the Cycle of Atmospheric water) retrieval technique is shown to offer accurate measurements of water vapour total columns (e.g. average agreement within -5.2 % of GRUAN and -6.5 % of a co-located emission FTIR spectrometer). However, comparisons show a small wet bias of approximately 6 % at the high-latitude Eureka site. In addition, a new dataset derived from Atmospheric Emitted Radiance Interferometer (AERI) measurements is shown to provide accurate water vapour measurements (e.g. average agreement was within 4 % of GRUAN), which usefully enables measurements to be taken during day and night (especially valuable during polar night).

Chemistry and evolution of Titan's atmosphere

International Nuclear Information System (INIS)

Strobel, D.F.

1982-01-01

The chemistry and evolution of Titan's atmosphere is reviewed in the light of the scientific findings from the Voyager mission. It is argued that the present N 2 atmosphere may be Titan's initial atmosphere rather than photochemically derived from an original NH 3 atmosphere. The escape rate of hydrogen from Titan is controlled by photochemical production from hydrocarbons. CH 4 is irreversibly converted to less hydrogen rich hydrocarbons, which over geologic time accumulate on the surface to a layer thickness of approximately 0.5 km. Magnetospheric electrons interacting with Titan's exosphere may dissociate enough N 2 into hot, escaping N atoms to remove approximately 0.2 of Titan's present atmosphere over geologic time. The energy dissipation of magnetospheric electrons exceeds solar e.u.v. energy deposition in Titan's atmosphere by an order of magnitude and is the principal driver of nitrogen photochemistry. The environmental conditions in Titan's upper atmosphere are favorable to building up complex molecules, particularly in the north polar cap region. (author)

On the relationship between atmospheric circulation and the fluctuations in the sea ice extents of the Bering and Okhotsk Seas

Science.gov (United States)

Cavalieri, D. J.; Parkinson, C. L.

1987-01-01

The influence of the hemispheric atmospheric circulation on the sea ice covers of the Bering Sea and the Sea of Okhotsk is examined using data obtained with the Nimbus 5 electrically scanning microwave radiometer for the four winters of the 1973-1976 period. The 3-day averaged sea ice extent data were used to establish periods for which there is an out-of-phase relationship between fluctuations of the two ice covers. A comparison of the sea-level atmospheric pressure field with the seasonal, interannual, and short-term sea ice fluctuations reveal an association between changes in the phase and the amplitude of the long waves in the atmosphere and advance and retreat of Arctic ice covers.

Exploring the low friction of diamond-like carbon films in carbon dioxide atmosphere by experiments and first-principles calculations

Science.gov (United States)

Huo, Lei; Wang, Shunhua; Pu, Jibin; Sun, Junhui; Lu, Zhibin; Ju, Pengfei; Wang, Liping

2018-04-01

The friction behavior and the mechanism of DLC films in CO2 atmosphere are rarely explored, which is a significant obstacle for the potential practical application of DLC films in primarily CO2 environment. Here, the experiments and first-principles calculations are performed to simultaneously investigate this theme. We find that DLC films in CO2 atmosphere exhibit astoundingly low friction coefficient compared with in ambient air and vacuum atmospheres. The XPS and Raman spectrums demonstrate the possibly activation of CO2 molecule in the shearing interfaces, which may be critical for the low friction of DLC films in CO2 atmosphere. The calculated results reveal that the lactone groups can easily form during the horizontally chemisorption of CO2 molecule on the DLC surface, which is energetic and is a favorable process under the interfacial stress. Because of the presence of the lone-pairs of the lactone group, the lactone-terminated surfaces appear to be responsible for the low friction of DLC films in CO2 atmosphere. The studies may open up the possibility for DLC films usage in Mars applications.

Atmospheric tritium. Measurement and application

International Nuclear Information System (INIS)

Frejaville, Gerard

1967-02-01

The possible origins of atmospheric tritium are reviewed and discussed. A description is given of enrichment (electrolysis and thermal diffusion) and counting (gas counters and liquid scintillation counters) processes which can be used for determining atmospheric tritium concentrations. A series of examples illustrates the use of atmospheric tritium for resolving a certain number of hydrological and glaciological problems. (author) [fr

Coupled Regional Ocean-Atmosphere Modeling of the Mount Pinatubo Impact on the Red Sea

Science.gov (United States)

Stenchikov, G. L.; Osipov, S.

2017-12-01

The 1991 eruption of Mount Pinatubo had dramatic effects on the regional climate in the Middle East. Though acknowledged, these effects have not been thoroughly studied. To fill this gap and to advance understanding of the mechanisms that control variability in the Middle East's regional climate, we simulated the impact of the 1991 Pinatubo eruption using a regional coupled ocean-atmosphere modeling system set for the Middle East and North Africa (MENA) domain. We used the Coupled Ocean-Atmosphere-Wave-Sediment Transport (COAWST) framework, which couples the Weather Research and Forecasting Model (WRF) model with the Regional Oceanic Modeling System (ROMS). We modified the WRF model to account for the radiative effect of volcanic aerosols. Our coupled ocean-atmosphere simulations verified by available observations revealed strong perturbations in the energy balance of the Red Sea, which drove thermal and circulation responses. Our modeling approach allowed us to separate changes in the atmospheric circulation caused by the impact of the volcano from direct regional radiative cooling from volcanic aerosols. The atmospheric circulation effect was significantly stronger than the direct volcanic aerosols effect. We found that the Red Sea response to the Pinatubo eruption was stronger and qualitatively different from that of the global ocean system. Our results suggest that major volcanic eruptions significantly affect the climate in the Middle East and the Red Sea and should be carefully taken into account in assessments of long-term climate variability and warming trends in MENA and the Red Sea.

Exoplanet atmospheres physical processes

CERN Document Server

Seager, Sara

2010-01-01

Over the past twenty years, astronomers have identified hundreds of extrasolar planets--planets orbiting stars other than the sun. Recent research in this burgeoning field has made it possible to observe and measure the atmospheres of these exoplanets. This is the first textbook to describe the basic physical processes--including radiative transfer, molecular absorption, and chemical processes--common to all planetary atmospheres, as well as the transit, eclipse, and thermal phase variation observations that are unique to exoplanets. In each chapter, Sara Seager offers a conceptual introduction, examples that combine the relevant physics equations with real data, and exercises. Topics range from foundational knowledge, such as the origin of atmospheric composition and planetary spectra, to more advanced concepts, such as solutions to the radiative transfer equation, polarization, and molecular and condensate opacities. Since planets vary widely in their atmospheric properties, Seager emphasizes the major p...

Atmospheric evolution on inhabited and lifeless worlds

CERN Document Server

Catling, David C

2017-01-01

As the search for Earth-like exoplanets gathers pace, in order to understand them, we need comprehensive theories for how planetary atmospheres form and evolve. Written by two well-known planetary scientists, this text explains the physical and chemical principles of atmospheric evolution and planetary atmospheres, in the context of how atmospheric composition and climate determine a planet's habitability. The authors survey our current understanding of the atmospheric evolution and climate on Earth, on other rocky planets within our Solar System, and on planets far beyond. Incorporating a rigorous mathematical treatment, they cover the concepts and equations governing a range of topics, including atmospheric chemistry, thermodynamics, radiative transfer, and atmospheric dynamics, and provide an integrated view of planetary atmospheres and their evolution. This interdisciplinary text is an invaluable one-stop resource for graduate-level students and researchers working across the fields of atmospheric science...

Atmospheric radiocarbon as a Southern Ocean wind proxy over the last 1000 years

Science.gov (United States)

Rodgers, K. B.; Mikaloff Fletcher, S.; Galbraith, E.; Sarmiento, J. L.; Gnanadesikan, A.; Slater, R. D.; Naegler, T.

2009-04-01

Measurements of radiocarbon in tree rings over the last 1000 years indicate that there was a pre-industrial latitudinal gradient of atmospheric radiocarbon of 3.9-4.5 per mail and that this gradient had temporal variability of order 6 per mil. Here we test the idea that the mean gradient as well as variability in he gradient is dominated by the strength of the winds over the Southern Ocean. This is done using an ocean model and an atmospheric transport model. The ocean model is used to derive fluxes of 12CO2 and 14CO2 at the sea surface, and these fluxes are used as a lower boundary condition for the transport model. For the mean state, strong winds in the Southern Ocean drive significant upwelling of radiocarbon-depleted Circumpolar Deep Water (CDW), leading to a net flux of 14CO2 relative to 12CO2 into the ocean. This serves to maintain a hemispheric gradient in pre-anthropogenic atmospheric delta-c14. For perturbations, increased/decreased Southern Ocean winds drive increased/decreased uptake of 14CO2 relative to 12CO2, thus increasing/decreasing the hemispheric gradient in atmospheric delta-c14. The tree ring data is interpreted to reveal a decrease in the strength of the Southern Ocean winds at the transition between the Little Ice Age and the Medieval Warm Period.

Atmospheric Prebiotic Chemistry and Organic Hazes

Science.gov (United States)

Trainer, Melissa G.

2012-01-01

Earth's atmospheric composition at the time of the origin of life is not known, but it has often been suggested that chemical transformation of reactive species in the atmosphere was a significant source of pre biotic organic molecules. Experimental and theoretical studies over the past half century have shown that atmospheric synthesis can yield molecules such as amino acids and nucleobases, but these processes are very sensitive to gas composition and energy source. Abiotic synthesis of organic molecules is more productive in reduced atmospheres, yet the primitive Earth may not have been as reducing as earlier workers assumed, and recent research has reflected this shift in thinking. This work provides a survey of the range of chemical products that can be produced given a set of atmospheric conditions, with a particular focus on recent reports. Intertwined with the discussion of atmospheric synthesis is the consideration of an organic haze layer, which has been suggested as a possible ultraviolet shield on the anoxic early Earth. Since such a haze layer - if formed - would serve as a reservoir for organic molecules, the chemical composition of the aerosol should be closely examined. The results highlighted here show that a variety of products can be formed in mildly reducing or even neutral atmospheres, demonstrating that contributions of atmospheric synthesis to the organic inventory on early Earth should not be discounted. This review intends to bridge current knowledge of the range of possible atmospheric conditions in the prebiotic environment and pathways for synthesis under such conditions by examining the possible products of organic chemistry in the early atmosphere.

Atmospheric 14C variations derived from tree rings during the early Younger Dryas

Science.gov (United States)

Hua, Quan; Barbetti, Mike; Fink, David; Kaiser, Klaus Felix; Friedrich, Michael; Kromer, Bernd; Levchenko, Vladimir A.; Zoppi, Ugo; Smith, Andrew M.; Bertuch, Fiona

2009-12-01

Atmospheric radiocarbon variations over the Younger Dryas interval, from ˜13,000 to 11,600 cal yr BP, are of immense scientific interest because they reveal crucial information about the linkages between climate, ocean circulation and the carbon cycle. However, no direct and reliable atmospheric 14C records based on tree rings for the entire Younger Dryas have been available. In this paper, we present (1) high-precision 14C measurements on the extension of absolute tree-ring chronology from 12,400 to 12,560 cal yr BP and (2) high-precision, high-resolution atmospheric 14C record derived from a 617-yr-long tree-ring chronology of Huon pine from Tasmania, Australia, spanning the early Younger Dryas. The new tree-ring 14C records bridge the current gap in European tree-ring radiocarbon chronologies during the early Younger Dryas, linking the floating Lateglacial Pine record to the absolute tree-ring timescale. A continuous and reliable atmospheric 14C record for the past 14,000 cal yr BP including the Younger Dryas is now available. The new records indicate that the abrupt rise in atmospheric Δ 14C associated with the Younger Dryas onset occurs at ˜12,760 cal yr BP, ˜240 yrs later than that recorded in Cariaco varves, with a smaller magnitude of ˜40‰ followed by several centennial Δ 14C variations of 20-25‰. Comparing the tree-ring Δ 14C to marine-derived Δ 14C and modelled Δ 14C based on ice-core 10Be fluxes, we conclude that changes in ocean circulation were mainly responsible for the Younger Dryas onset, while a combination of changes in ocean circulation and 14C production rate were responsible for atmospheric Δ 14C variations for the remainder of the Younger Dryas.

Ar-37 in the Atmospheric and Sub-Soil Gases

International Nuclear Information System (INIS)

Purtschert, R.; Raghoo, L.S.

2015-01-01

On-site inspection of the radioactive noble gas isotope 37Ar is a definitive and unambiguous indicator of an underground nuclear explosion. 37Ar is produced underground by neutron activation of calcium by the reaction 40Ca(n,α)37Ar. In the atmosphere, 37Ar is produced by the spallation reaction 40Ar(n,4n)37Ar. Periodic measurements over the last six years on air collected in Bern revealed a background level in the order of 1-5 mBq/m 3 air in agreement with former findings and theoretical calculations. Those calculations also indicated that the intrusion of stratospheric air masses may lead to elevated tropospheric 37Ar concentrations up to 8-10 mBq/m 3 air. Selected samples taken up to now in the vicinity of nuclear power plants revealed no significant deviation from the natural background. In order to distinguish between natural and artificially elevated 37Ar the location-specific 37Ar activity range in soils, rocks and the atmosphere were identified. From CARIBIC flights, a passenger aircraft with a special air freight container filled with scientific equipment in the cargo compartment, tropospheric air samples were analyzed for 37Ar and 85Kr. The natural 37Ar production in soils and the rock basement underlying the alluvium is investigated by means of in situ measurements of different isotopes, theoretical calculations and irradiation experiments on selected rock samples. This will help resolve the temporal evolution and/or constancy of the natural 37Ar background and allow for an interpretation in terms of the identification of clandestine nuclear explosions. (author)

Huguangyan Maar Lake (SE China): A solid record of atmospheric mercury pollution history in a non-remote region

Science.gov (United States)

Zeng, Yan; Chen, Jingan; Yang, Yongqiong; Wang, Jianxu; Zhu, Zhengjie; Li, Jian

2017-10-01

Mercury is a highly toxic metal that can cause harm to environment and human health. As atmospheric deposition is the main source of total Hg input to aquatic system in remote and pristine regions, almost all the studies on atmospheric Hg pollution history concentrated in these areas, while the studies in non-remote areas are much limited, especially for the long history records. In this study, Huguangyan Maar Lake, an undisturbed lake system at low altitude in China, was selected to reconstruct the atmospheric mercury pollution history. Variation patterns of TOC, Hg and non-residual Sr in the sediment core indicated that, compared to the direct atmospheric Hg deposition, the effect of either Hg scavenging from water column by algae or the catchment inputs of previously deposited Hg on the Hg accumulation in the lake sediment was limited. The sediment Hg content in Huguangyan Lake was mainly controlled by the atmospheric Hg deposition, and thus accurately reflected the atmospheric Hg pollution history. The Hga (Hg content from atmospheric deposition) in Huguangyan Lake presented a comparable variation pattern to that in remote sites. It had the same variation trend as the global atmospheric Hg before 1950 CE, which could be attributed to the Industrial Revolution. After that, it was mainly controlled by Hg emissions from Asian countries. The variation of Hga also indicated that atmospheric Hg deposition accelerated significantly since 2000 CE. This study, along with other investigations in remote sites in China, showed that the sediment Hg in Huguangyan Lake responded to the atmospheric Hg pollution more sensitively than in the alpine regions. It should be noted that, the more intensive acceleration of Hg deposition in Huguangyan Lake may imply that the South of China suffered from much more serious atmospheric Hg pollution than previous studies revealed.

Atmospheric ionisation in Snowdonia

Energy Technology Data Exchange (ETDEWEB)

Aplin, K L [Department of Physics, University of Oxford, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH UK (United Kingdom); Williams, J H, E-mail: k.aplin1@physics.ox.ac.uk [Envirodata-Eyri, Bryn Goleu, Penmaen Park, Llanfairfechan, Gwynedd LL33 0RL (United Kingdom)

2011-06-23

Atmospheric ionisation from natural radioactivity and cosmic rays has been measured at several sites in Snowdonia from 2005-present. The motivation for this project was a combination of public engagement with science, and research into the effects of ionisation on climate. A four-component atmospheric radiometer instrument is co-located with the ionisation detectors and the data is remotely logged and displayed on the Web. Atmospheric ionisation from natural radioactivity varies with local geology, and the cosmic ray ionisation component is modulated by solar activity and altitude. Variations due to all these effects have been identified and are described.

Kajian Pustaka Mengenai Restaurant Atmosphere

Directory of Open Access Journals (Sweden)

Adeline Agoes

2015-05-01

Full Text Available Restaurant is one of the businesses that support tourism development. Restaurants nowadays don’t only provide food, but also the service and atmosphere to their customers. The purpose of this study is to discover theaspects defining restaurant atmosphere and the implications of restaurant atmosphere to other particular aspects related to restaurant business. This article is written based on a study conducted through a literature review. Through the examination, it is found that the atmosphere of a restaurant is one important aspect and can be considered as a competitive advantage as well as one of the determinants of customer satisfaction.

The impacts of the atmospheric annular mode on the AMOC and its feedback in an idealized experiment

Science.gov (United States)

Santis, Wlademir; Aimola, Luis; Campos, Edmo J. D.; Castellanos, Paola

2018-03-01

The interdecadal variability of the atmospheric and oceanic meridional overturning circulation is studied, using a coupled model with two narrow meridional barriers representing the land and a flat bottomed Aquaplanet. Empirical orthogonal function (EOF) analysis are used in the atmospheric and oceanic meridional overturning cells, revealing the atmospheric interdecadal variability is dominated by an annular mode, in both hemispheres, which introduces in the ocean a set of patterns of variability. The most energetic EOFs in the ocean are the barotropic responses from the annular mode. The interaction between the heat anomalies, due to the barotropic response, and the thermohaline circulation of each basin leads to a resonance mechanism that feeds back to the atmospheric forcing, modulating the annular mode spectrum. Besides the barotropic response, the annular mode introduces anomalies of salinity and temperature in the subtropical Atlantic that affects its upper buoyancy. These anomalies are incorporated within the ocean circulation and advected until the areas of deep sinking in the northern Atlantic, impacting on its overturning circulation as well.

Intensifying the Atmospheric

DEFF Research Database (Denmark)

Liebst, Lasse Suonperä

2012-01-01

The phenomenological concept of urban atmospheres is more often applied as an aesthetic description of the metropolitan space as such. This conceptualization is supported in this paper; however, I strive to give the concept a post-phenomenological axial turn. While phenomenology, due to its under...... sufficiently intense. All things considered, the paper should be read as a sociological contribution to theoretically reconstruct the concept of urban atmospheres in the light of spatial morphology....

Lack of tissue renewal in human adult Achilles tendon is revealed by nuclear bomb C

DEFF Research Database (Denmark)

Heinemeier, Katja Maria; Schjerling, Peter; Heinemeier, J.

2013-01-01

the 14C bomb-pulse method. This method takes advantage of the dramatic increase in atmospheric levels of 14C, produced by nuclear bomb tests in 1955-1963, which is reflected in all living organisms. Levels of 14C were measured in 28 forensic samples of Achilles tendon core and 4 skeletal muscle samples...... is revealed by nuclear bomb 14C....

The Vicious Cycle of Family Atmosphere, Interpersonal Self-concepts, and Paranoia in Schizophrenia-A Longitudinal Study.

Science.gov (United States)

Hesse, Klaus; Kriston, Levente; Mehl, Stephanie; Wittorf, Andreas; Wiedemann, Wolfgang; Wölwer, Wolfgang; Klingberg, Stefan

2015-11-01

Recent cognitive models of paranoid delusions highlight the role of self-concepts in the development and maintenance of paranoia. Evidence is growing that especially interpersonal self-concepts are relevant in the genesis of paranoia. In addition, negative interpersonal life-experiences are supposed to influence the course of paranoia. As dysfunctional family atmosphere corresponds with multiple distressing dyadic experiences, it could be a risk factor for the development and maintenance of paranoia. A total of 160 patients with a diagnosis of schizophrenia were assessed twice within 12 months. Standardized questionnaires and symptom rating scales were used to measure interpersonal self-concepts, perceived family atmosphere, and paranoia. Data were analyzed using longitudinal cross-lagged structural equation models. Perceived negative family atmosphere was associated with the development of more pronounced negative interpersonal self-concepts 12 months later. Moreover, paranoia was related to negative family atmosphere after 12 months as well. As tests revealed that reversed associations were not able to explain the data, we found evidence for a vicious cycle between paranoia, family atmosphere, and interpersonal self-concepts as suggested by theoretical/cognitive model of paranoid delusions. Results suggest that broader interventions for patients and their caretakers that aim at improving family atmosphere might also be able to improve negative self-concepts and paranoia. © The Author 2015. Published by Oxford University Press on behalf of the Maryland Psychiatric Research Center. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Atmospheric and aerosol chemistry

International Nuclear Information System (INIS)

McNeill, V. Faye; Ariya, Parisa A.; McGill Univ. Montreal, QC

2014-01-01

This series presents critical reviews of the present position and future trends in modern chemical research. Short and concise reports on chemistry, each written by the world renowned experts. Still valid and useful after 5 or 10 years. More information as well as the electronic version of the whole content available at: springerlink.com. Christian George, Barbara D'Anna, Hartmut Herrmann, Christian Weller, Veronica Vaida, D. J. Donaldson, Thorsten Bartels-Rausch, Markus Ammann Emerging Areas in Atmospheric Photochemistry. Lisa Whalley, Daniel Stone, Dwayne Heard New Insights into the Tropospheric Oxidation of Isoprene: Combining Field Measurements, Laboratory Studies, Chemical Modelling and Quantum Theory. Neil M. Donahue, Allen L. Robinson, Erica R. Trump, Ilona Riipinen, Jesse H. Kroll Volatility and Aging of Atmospheric Organic Aerosol. P. A. Ariya, G. Kos, R. Mortazavi, E. D. Hudson, V. Kanthasamy, N. Eltouny, J. Sun, C. Wilde Bio-Organic Materials in the Atmosphere and Snow: Measurement and Characterization V. Faye McNeill, Neha Sareen, Allison N. Schwier Surface-Active Organics in Atmospheric Aerosols.

Modeling the atmospheric chemistry of TICs

Science.gov (United States)

Henley, Michael V.; Burns, Douglas S.; Chynwat, Veeradej; Moore, William; Plitz, Angela; Rottmann, Shawn; Hearn, John

2009-05-01

An atmospheric chemistry model that describes the behavior and disposition of environmentally hazardous compounds discharged into the atmosphere was coupled with the transport and diffusion model, SCIPUFF. The atmospheric chemistry model was developed by reducing a detailed atmospheric chemistry mechanism to a simple empirical effective degradation rate term (keff) that is a function of important meteorological parameters such as solar flux, temperature, and cloud cover. Empirically derived keff functions that describe the degradation of target toxic industrial chemicals (TICs) were derived by statistically analyzing data generated from the detailed chemistry mechanism run over a wide range of (typical) atmospheric conditions. To assess and identify areas to improve the developed atmospheric chemistry model, sensitivity and uncertainty analyses were performed to (1) quantify the sensitivity of the model output (TIC concentrations) with respect to changes in the input parameters and (2) improve, where necessary, the quality of the input data based on sensitivity results. The model predictions were evaluated against experimental data. Chamber data were used to remove the complexities of dispersion in the atmosphere.

Recovering of images degraded by atmosphere

Science.gov (United States)

Lin, Guang; Feng, Huajun; Xu, Zhihai; Li, Qi; Chen, Yueting

2017-08-01

Remote sensing images are seriously degraded by multiple scattering and bad weather. Through the analysis of the radiative transfer procedure in atmosphere, an image atmospheric degradation model considering the influence of atmospheric absorption multiple scattering and non-uniform distribution is proposed in this paper. Based on the proposed model, a novel recovering method is presented to eliminate atmospheric degradation. Mean-shift image segmentation and block-wise deconvolution are used to reduce time cost, retaining a good result. The recovering results indicate that the proposed method can significantly remove atmospheric degradation and effectively improve contrast compared with other removal methods. The results also illustrate that our method is suitable for various degraded remote sensing, including images with large field of view (FOV), images taken in side-glance situations, image degraded by atmospheric non-uniform distribution and images with various forms of clouds.

ESA Atmospheric Toolbox

Science.gov (United States)

Niemeijer, Sander

2017-04-01

The ESA Atmospheric Toolbox (BEAT) is one of the ESA Sentinel Toolboxes. It consists of a set of software components to read, analyze, and visualize a wide range of atmospheric data products. In addition to the upcoming Sentinel-5P mission it supports a wide range of other atmospheric data products, including those of previous ESA missions, ESA Third Party missions, Copernicus Atmosphere Monitoring Service (CAMS), ground based data, etc. The toolbox consists of three main components that are called CODA, HARP and VISAN. CODA provides interfaces for direct reading of data from earth observation data files. These interfaces consist of command line applications, libraries, direct interfaces to scientific applications (IDL and MATLAB), and direct interfaces to programming languages (C, Fortran, Python, and Java). CODA provides a single interface to access data in a wide variety of data formats, including ASCII, binary, XML, netCDF, HDF4, HDF5, CDF, GRIB, RINEX, and SP3. HARP is a toolkit for reading, processing and inter-comparing satellite remote sensing data, model data, in-situ data, and ground based remote sensing data. The main goal of HARP is to assist in the inter-comparison of datasets. By appropriately chaining calls to HARP command line tools one can pre-process datasets such that two datasets that need to be compared end up having the same temporal/spatial grid, same data format/structure, and same physical unit. The toolkit comes with its own data format conventions, the HARP format, which is based on netcdf/HDF. Ingestion routines (based on CODA) allow conversion from a wide variety of atmospheric data products to this common format. In addition, the toolbox provides a wide range of operations to perform conversions on the data such as unit conversions, quantity conversions (e.g. number density to volume mixing ratios), regridding, vertical smoothing using averaging kernels, collocation of two datasets, etc. VISAN is a cross-platform visualization and

Atmospheric Research 2016 Technical Highlights

Science.gov (United States)

Platnick, Steven

2017-01-01

Atmospheric research in the Earth Sciences Division (610) consists of research and technology development programs dedicated to advancing knowledge and understanding of the atmosphere and its interaction with the climate of Earth. The Divisions goals are to improve understanding of the dynamics and physical properties of precipitation, clouds, and aerosols; atmospheric chemistry, including the role of natural and anthropogenic trace species on the ozone balance in the stratosphere and the troposphere; and radiative properties of Earth's atmosphere and the influence of solar variability on the Earth's climate. Major research activities are carried out in the Mesoscale Atmospheric Processes Laboratory, the Climate and Radiation Laboratory, the Atmospheric Chemistry and Dynamics Laboratory, and the Wallops Field Support Office. The overall scope of the research covers an end-to-end process, starting with the identification of scientific problems, leading to observation requirements for remote-sensing platforms, technology and retrieval algorithm development; followed by flight projects and satellite missions; and eventually, resulting in data processing, analyses of measurements, and dissemination from flight projects and missions. Instrument scientists conceive, design, develop, and implement ultraviolet, infrared, optical, radar, laser, and lidar technology to remotely sense the atmosphere. Members of the various laboratories conduct field measurements for satellite sensor calibration and data validation, and carry out numerous modeling activities. These modeling activities include climate model simulations, modeling the chemistry and transport of trace species on regional-to-global scales, cloud resolving models, and developing the next-generation Earth system models. Satellite missions, field campaigns, peer-reviewed publications, and successful proposals are essential at every stage of the research process to meeting our goals and maintaining leadership of the

Structure of caesium selenate

International Nuclear Information System (INIS)

Zuniga, F.J.; Breczewski, T.; Arnaiz, A.

1991-01-01

Cs 2 SeO 4 , M 4 =408.77, orthorhombic, Pnam, a=8.3777 (8), b=11.276 (2), c=6.434 (2) A, V=607.8 (2) A 3 , Z=4, D x =4.46 Mg m -3 , MoKα, λ=0.71069 A, μ=185.06 cm -1 , F(000)=704, T=293 K, R=0.048, 3348 observed reflections. Average values of the Se-O and Cs-O distances are 1.637 (4) and 3.387 (3) A, respectively [range 3.038 (5)-3.872 (6) A with 9 and 11 coordination of caesium by oxygen]. (orig.)

The annual averaged atmospheric dispersion factor and deposition factor according to methods of atmospheric stability classification

Energy Technology Data Exchange (ETDEWEB)

Jeong, Hae Sun; Jeong, Hyo Joon; Kim, Eun Han; Han, Moon Hee; Hwang, Won Tae [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2016-09-15

This study analyzes the differences in the annual averaged atmospheric dispersion factor and ground deposition factor produced using two classification methods of atmospheric stability, which are based on a vertical temperature difference and the standard deviation of horizontal wind direction fluctuation. Daedeok and Wolsong nuclear sites were chosen for an assessment, and the meteorological data at 10 m were applied to the evaluation of atmospheric stability. The XOQDOQ software program was used to calculate atmospheric dispersion factors and ground deposition factors. The calculated distances were chosen at 400 m, 800 m, 1,200 m, 1,600 m, 2,400 m, and 3,200 m away from the radioactive material release points. All of the atmospheric dispersion factors generated using the atmospheric stability based on the vertical temperature difference were shown to be higher than those from the standard deviation of horizontal wind direction fluctuation. On the other hand, the ground deposition factors were shown to be same regardless of the classification method, as they were based on the graph obtained from empirical data presented in the Nuclear Regulatory Commission's Regulatory Guide 1.111, which is unrelated to the atmospheric stability for the ground level release. These results are based on the meteorological data collected over the course of one year at the specified sites; however, the classification method of atmospheric stability using the vertical temperature difference is expected to be more conservative.

Atmospheric pollution in Lisbon urban atmosphere

Science.gov (United States)

Oliveira, C.

2009-04-01

Lisbon is the capital city of Portugal with about 565,000 residents in 2008 and a population density of 6,600 inhabitants per square kilometre. Like several other major metropolis, the town is surrounded by satellite cities, forming together a region known as "Lisbon Metropolitan Area" with about 3 million inhabitants, a quarter of the overall Portuguese population. Besides their local residents, it is estimated that more than one million citizens come into the Lisbon area every day from the outskirts, leading to elevated traffic densities and intense traffic jams, with important consequences on air pollution levels and obvious negative impacts on human health. Airborne particulate matter limit values are frequently exceeded, making urgent the existence of consistent programs to monitor and help taking measures to control them. Within the Portuguese project PAHLIS (Polycyclic Aromatic Hydrocarbons Contamination in Lisbon Urban Atmosphere) financed by the Portuguese Science Foundation ("Fundação para a Ciência e a Tecnologia"), an aerosol and vapour phase sampling program is being implemented in the city of Lisbon at two selected contrasting zones, namely a typically busy area with intense road traffic and frequent exceedences of the particulate matter standard for the maximum allowable concentration, and a residential quieter area, thus with a cleaner atmosphere characterised as an urban background site. An one month-long sampling campaign was performed during the summer of 2008, where particulate matter was collected in two fractions (coarse 2.5µmwork are expected to cover a lack of reliable information regarding sources of atmospheric pollutants in Portugal and present, for the first time, systematic data of PAHs levels in Lisbon. Acknowledgement: This work was performed under Project PAHLIS (PTDC/AMB/65699/2006) financed by "Fundação para a Ciência e a Tecnologia". C. Oliveira thanks Project PAHLIS his scholarship.

(Chemistry of the global atmosphere)

Energy Technology Data Exchange (ETDEWEB)

Marland, G.

1990-09-27

The traveler attended the conference The Chemistry of the Global Atmosphere,'' and presented a paper on the anthropogenic emission of carbon dioxide (CO{sub 2}) to the atmosphere. The conference included meetings of the International Global Atmospheric Chemistry (IGAC) programme, a core project of the International Geosphere/Biosphere Programme (IGBP) and the traveler participated in meetings on the IGAC project Development of Global Emissions Inventories'' and agreed to coordinate the working group on CO{sub 2}. Papers presented at the conference focused on the latest developments in analytical methods, modeling and understanding of atmospheric CO{sub 2}, CO, CH{sub 4}, N{sub 2}O, SO{sub 2}, NO{sub x}, NMHCs, CFCs, and aerosols.

Global atmospheric changes.

OpenAIRE

Piver, W T

1991-01-01

Increasing concentrations of CO2 and other greenhouse gases in the atmosphere can be directly related to global warming. In terms of human health, because a major cause of increasing atmospheric concentrations of CO2 is the increased combustion of fossil fuels, global warming also may result in increases in air pollutants, acid deposition, and exposure to ultraviolet (UV) radiation. To understand better the impacts of global warming phenomena on human health, this review emphasizes the proces...

Middle Atmosphere Program. Handbook for MAP. Volume 30: International School on Atmospheric Radar

Science.gov (United States)

Fukao, Shoichiro (Editor)

1989-01-01

Broad, tutorial coverage is given to the technical and scientific aspects of mesosphere stratosphere troposphere (MST) meteorological radar systems. Control issues, signal processing, atmospheric waves, the historical aspects of radar atmospheric dynamics, incoherent scatter radars, radar echoes, radar targets, and gravity waves are among the topics covered.

Atmospheres and surfaces of small bodies and dwarf planets in the Kuiper Belt

Directory of Open Access Journals (Sweden)

Schaller E.L.

2010-12-01

Full Text Available Kuiper Belt Objects (KBOs are icy relics orbiting the sun beyond Neptune left over from the planetary accretion disk. These bodies act as unique tracers of the chemical, thermal, and dynamical history of our solar system. Over 1000 Kuiper Belt Objects (KBOs and centaurs (objects with perihelia between the giant planets have been discovered over the past two decades. While the vast majority of these objects are small ( 6-meter telescopes, have allowed for the first detailed studies of their surfaces and atmospheres. Visible and near-infrared spectroscopy of KBOs and centaurs has revealed a great diversity of surface compositions. Only the largest and coldest objects are capable of retaining volatile ices and atmospheres. Knowledge of the dynamics, physical properties, and collisional history of objects in the Kuiper belt is important for understanding solar system formation and evolution.

Stochastic excitation of low frequency variability in the midlatitude atmosphere

International Nuclear Information System (INIS)

Ioannou, P.J.; Farrell, B.F.

1994-01-01

Spectral analysis of the transient geopotential variance of the midlatitude atmosphere reveals a sharp peak in the wavenumber-period spectra concentrated at large scales (zonal wave numbers m 10 days). This is surprising because conventional baroclinic instability calculations predict a broad maximum of the variance at synoptic scale (8 < m < 12) with associated period of a few days. In this work we review the method for calculating the maintained variance and associated fluxes and then discuss some results pertaining to the interpretation of the EOF's which arise from the stochastic dynamics of non-normal dynamical systems

RAYLEIGH SCATTERING IN THE ATMOSPHERE OF THE WARM EXO-NEPTUNE GJ 3470B

International Nuclear Information System (INIS)

Dragomir, Diana; Benneke, Björn; Pearson, Kyle A.; Crossfield, Ian J. M.; Barman, Travis; Eastman, Jason; Biddle, Lauren I.

2015-01-01

GJ 3470b is a warm Neptune-size planet transiting an M dwarf star. Like the handful of other small exoplanets for which transmission spectroscopy has been obtained, GJ 3470b exhibits a flat spectrum in the near- and mid-infrared. Recently, a tentative detection of Rayleigh scattering in its atmosphere has been reported. This signal manifests itself as an observed increase of the planetary radius as a function of decreasing wavelength in the visible. We set out to verify this detection and observed several transits of this planet with the LCOGT network and the Kuiper telescope in four different bands (Sloan g, Sloan i, Harris B, and Harris V). Our analysis reveals a strong Rayleigh scattering slope, thus confirming previous results. This makes GJ 3470b the smallest known exoplanet with a detection of Rayleigh scattering. We find that the most plausible scenario is a hydrogen/helium-dominated atmosphere covered by clouds which obscure absorption features in the infrared and hazes which give rise to scattering in the visible. Our results demonstrate the feasibility of exoplanet atmospheric characterization from the ground, even with meter-class telescopes

RAYLEIGH SCATTERING IN THE ATMOSPHERE OF THE WARM EXO-NEPTUNE GJ 3470B

Energy Technology Data Exchange (ETDEWEB)

Dragomir, Diana [Las Cumbres Observatory Global Telescope Network, 6740 Cortona Drive Suite 102, Goleta, CA 93117 (United States); Benneke, Björn [Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125 (United States); Pearson, Kyle A. [Department of Physics and Astronomy, Northern Arizona University, Flagstaff, AZ 86001 (United States); Crossfield, Ian J. M.; Barman, Travis [Department of Planetary Sciences, Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721 (United States); Eastman, Jason [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States); Biddle, Lauren I., E-mail: diana@oddjob.uchicago.edu [Gemini Observatory, Northern Operations Center, 670 N. Aohoku Place, Hilo, HI 96720 (United States)

2015-12-01

GJ 3470b is a warm Neptune-size planet transiting an M dwarf star. Like the handful of other small exoplanets for which transmission spectroscopy has been obtained, GJ 3470b exhibits a flat spectrum in the near- and mid-infrared. Recently, a tentative detection of Rayleigh scattering in its atmosphere has been reported. This signal manifests itself as an observed increase of the planetary radius as a function of decreasing wavelength in the visible. We set out to verify this detection and observed several transits of this planet with the LCOGT network and the Kuiper telescope in four different bands (Sloan g, Sloan i, Harris B, and Harris V). Our analysis reveals a strong Rayleigh scattering slope, thus confirming previous results. This makes GJ 3470b the smallest known exoplanet with a detection of Rayleigh scattering. We find that the most plausible scenario is a hydrogen/helium-dominated atmosphere covered by clouds which obscure absorption features in the infrared and hazes which give rise to scattering in the visible. Our results demonstrate the feasibility of exoplanet atmospheric characterization from the ground, even with meter-class telescopes.

Retrieval and analysis of atmospheric XCO2 using ground-based spectral observation.

Science.gov (United States)

Qin, Xiu-Chun; Lei, Li-Ping; Kawasaki, Masahiro; Masafumi, Ohashi; Takahiro, Kuroki; Zeng, Zhao-Cheng; Zhang, Bing

2014-07-01

Atmospheric CO2 column concentration (column-averaged dry air mole fractions of atmospheric carbon dioxide) data obtained by ground-based hyperspectral observation is an important source of data for the verification and improvement of the results of CO2 retrieval based on satellite hyperspectral observation. However, few studies have been conducted on atmospheric CO2 column concentration retrieval based on ground-based spectral hyperspectral observation in China. In the present study, we carried out the ground-based hyperspectral observation in Xilingol Grassland, Inner Mongolia of China by using an observation system which is consisted of an optical spectral analyzer, a sun tracker, and some other elements. The atmospheric CO2 column concentration was retrieved using the observed hyperspectral data. The effect of a wavelength shift of the observation spectra and the meteorological parameters on the retrieval precision of the atmospheric CO2 concentration was evaluated and analyzed. The results show that the mean value of atmospheric CO2 concentration was 390.9 microg x mL(-1) in the study area during the observing period from July to September. The shift of wavelength in the range between -0.012 and 0.042 nm will generally lead to 1 microg x mL(-1) deviation in the CO2 retrievals. This study also revealed that the spectral transmittance was sensitive to meteorological parameters in the wavelength range of 6 357-6 358, 6 360-6 361, and 6 363-6 364 cm(-1). By comparing the CO2 retrievals derived from the meteorological parameters observed in synchronous and non-synchronous time, respectively, with the spectral observation, it was showed that the concentration deviation caused by using the non-synchronously observed meteorological parameters is ranged from 0.11 to 4 microg x mL(-1). These results can be used as references for the further improvement of retrieving CO2 column concentration based on spectral observation.

Acoustic-gravity waves generated by atmospheric and near-surface sources

Science.gov (United States)

Kunitsyn, Viacheslav E.; Kholodov, Alexander S.; Krysanov, Boris Yu.; Andreeva, Elena S.; Nesterov, Ivan A.; Vorontsov, Artem M.

2013-04-01

. The ionospheric footprints of atmospheric disturbances are given. The effects of AGW evolution after launching the rockets are studied. One of the possible applications of RT imaging of wavelike disturbances is the study of AGW and TID as probable precursors of the earthquakes. The key difficulty here is to distinguish between the AGW and atmospheric and ionospheric disturbances of non-seismic nature (for example, those caused by the enhanced solar-geomagnetic activity), which can be done by analyzing spatial two-dimensional and three-dimensional structures revealed by tomographic methods. The examples of AGW RT imaging based on the real experimental satellite data measured in regions of the Europe, North America and Asia are demonstrated. The example of AGW and TID generation by the tsunami wave after the Tohoku earthquake is presented. Our results prove the capability of RT methods to detect wavelike disturbances in the ionosphere, which are caused by the near-surface sources, and to distinguish between these disturbances and the influence from the atmosphere and space. The work was supported by the Russian Foundation for Basic Research (grants 11-05-01157 and 13-05-01122 ).

Intercomparison of oceanic and atmospheric forced and coupled mesoscale simulations Part I: Surface fluxes

Directory of Open Access Journals (Sweden)

P. Josse

1999-04-01

Full Text Available A mesoscale non-hydrostatic atmospheric model has been coupled with a mesoscale oceanic model. The case study is a four-day simulation of a strong storm event observed during the SEMAPHORE experiment over a 500 × 500 km2 domain. This domain encompasses a thermohaline front associated with the Azores current. In order to analyze the effect of mesoscale coupling, three simulations are compared: the first one with the atmospheric model forced by realistic sea surface temperature analyses; the second one with the ocean model forced by atmospheric fields, derived from weather forecast re-analyses; the third one with the models being coupled. For these three simulations the surface fluxes were computed with the same bulk parametrization. All three simulations succeed well in representing the main oceanic or atmospheric features observed during the storm. Comparison of surface fields with in situ observations reveals that the winds of the fine mesh atmospheric model are more realistic than those of the weather forecast re-analyses. The low-level winds simulated with the atmospheric model in the forced and coupled simulations are appreciably stronger than the re-analyzed winds. They also generate stronger fluxes. The coupled simulation has the strongest surface heat fluxes: the difference in the net heat budget with the oceanic forced simulation reaches on average 50 Wm-2 over the simulation period. Sea surface-temperature cooling is too weak in both simulations, but is improved in the coupled run and matches better the cooling observed with drifters. The spatial distributions of sea surface-temperature cooling and surface fluxes are strongly inhomogeneous over the simulation domain. The amplitude of the flux variation is maximum in the coupled run. Moreover the weak correlation between the cooling and heat flux patterns indicates that the surface fluxes are not responsible for the whole cooling and suggests that the response of the ocean mixed layer

Intercomparison of oceanic and atmospheric forced and coupled mesoscale simulations Part I: Surface fluxes

Directory of Open Access Journals (Sweden)

H. Giordani

Full Text Available A mesoscale non-hydrostatic atmospheric model has been coupled with a mesoscale oceanic model. The case study is a four-day simulation of a strong storm event observed during the SEMAPHORE experiment over a 500 × 500 km2 domain. This domain encompasses a thermohaline front associated with the Azores current. In order to analyze the effect of mesoscale coupling, three simulations are compared: the first one with the atmospheric model forced by realistic sea surface temperature analyses; the second one with the ocean model forced by atmospheric fields, derived from weather forecast re-analyses; the third one with the models being coupled. For these three simulations the surface fluxes were computed with the same bulk parametrization. All three simulations succeed well in representing the main oceanic or atmospheric features observed during the storm. Comparison of surface fields with in situ observations reveals that the winds of the fine mesh atmospheric model are more realistic than those of the weather forecast re-analyses. The low-level winds simulated with the atmospheric model in the forced and coupled simulations are appreciably stronger than the re-analyzed winds. They also generate stronger fluxes. The coupled simulation has the strongest surface heat fluxes: the difference in the net heat budget with the oceanic forced simulation reaches on average 50 Wm-2 over the simulation period. Sea surface-temperature cooling is too weak in both simulations, but is improved in the coupled run and matches better the cooling observed with drifters. The spatial distributions of sea surface-temperature cooling and surface fluxes are strongly inhomogeneous over the simulation domain. The amplitude of the flux variation is maximum in the coupled run. Moreover the weak correlation between the cooling and heat flux patterns indicates that the surface fluxes are not responsible for the whole cooling and suggests that the response of the ocean mixed layer

Designing Affective Atmospheres on the Move

DEFF Research Database (Denmark)

Wind, Simon; Lanng, Ditte Bendix

travelling “unfolds affects as much as reasons” (Jensen, 2013, p.99). Practices, embodiment, technologies and materialities interconnect in non-quantifiable experiences of mobilities, which may fruitfully be unfolded by means of the concept of “atmosphere”. According to Böhme, atmosphere cannot be reduced...... to properties or qualities of neither human nor non-human bodies but they are “manifestations of the co-presence of subject and object” (Böhme, 1998, p.114). When travelling in and through spaces of mobilities in everyday life we are co-constituents in an on-flow of aesthetic atmospheres shaping emotional...... an analytical tool for capturing atmospheres as well as an interventionist tool for orchestrating atmospheres in everyday urban spaces of mobilities. References Anderson, B. (2009) ´Affective Atmospheres´, in: Emotion, Space and Society, pp. 77–81 Bissel, D. (2010) ´Passenger mobilities: affective atmospheres...

The OH-initiated oxidation of atmospheric peroxyacetic acid: Experimental and model studies

Science.gov (United States)

Wu, Huihui; Wang, Yin; Li, Huan; Huang, Liubin; Huang, Dao; Shen, Hengqing; Xing, Yanan; Chen, Zhongming

2017-09-01

Peroxyacetic acid (PAA, CH3C(O)OOH) plays an important role in atmospheric chemistry, serving as reactive oxidant and affecting radical recycling. However, previous studies revealed an obvious gap between modelled and observed concentrations of atmospheric PAA, which may be partly ascribed to the uncertainty in the kinetics and mechanism of OH-oxidation. In this study, we measured the rate constant of OH radical reaction with PAA (kPAA+OH) and investigated the products in order to develop a more robust atmospheric PAA chemistry. Using the relative rates technique and employing toluene and meta-xylene as reference compounds, the kPAA+OH was determined to be (9.4-11.9) × 10-12 cm3 molecule-1 s-1 at 298 K and 1 atm, which is about (2.5-3.2) times larger than that parameter used in Master Chemical Mechanism v3.3.1 (MCM v3.3.1) (3.70 × 10-12 cm3 molecule-1 s-1). Incorporation of a box model and MCM v3.3.1 with revised PAA chemistry represented a better simulation of atmospheric PAA observed during Wangdu Campaign 2014, a rural site in North China Plain. It is found that OH-oxidation is an important sink of atmospheric PAA in this rural area, accounting for ∼30% of the total loss. Moreover, the major terminal products of PAA-OH reaction were identified as formaldehyde (HCHO) and formic acid (HC(O)OH). The modelled results show that both primary and secondary chemistry play an important role in the large HCHO and HC(O)OH formation under experimental conditions. There should exist the channel of methyl H-abstraction for PAA-OH reaction, which may also provide routes to HCHO and HC(O)OH formation.

Erosion behavior of composite Al-Cr cathodes in cathodic arc plasmas in inert and reactive atmospheres

Energy Technology Data Exchange (ETDEWEB)

Franz, Robert, E-mail: robert.franz@unileoben.ac.at; Mendez Martin, Francisca; Hawranek, Gerhard [Montanuniversität Leoben, Franz-Josef-Strasse 18, 8700 Leoben (Austria); Polcik, Peter [Plansee Composite Materials GmbH, Siebenbürgerstrasse 23, 86983 Lechbruck am See (Germany)

2016-03-15

Al{sub x}Cr{sub 1−x} composite cathodes with Al contents of x = 0.75, 0.5, and 0.25 were exposed to cathodic arc plasmas in Ar, N{sub 2}, and O{sub 2} atmospheres and their erosion behavior was studied. Cross-sectional analysis of the elemental distribution of the near-surface zone in the cathodes by scanning electron microscopy revealed the formation of a modified layer for all cathodes and atmospheres. Due to intermixing of Al and Cr in the heat-affected zone, intermetallic Al-Cr phases formed as evidenced by x-ray diffraction analysis. Cathode poisoning effects in the reactive N{sub 2} and O{sub 2} atmospheres were nonuniform as a result of the applied magnetic field configuration. With the exception of oxide islands on Al-rich cathodes, reactive layers were absent in the circular erosion zone, while nitrides and oxides formed in the less eroded center region of the cathodes.

Overexpressing both ATP sulfurylase and selenocysteine methyltransferase enhances selenium phytoremediation traits in Indian mustard

International Nuclear Information System (INIS)

LeDuc, Danika L.; AbdelSamie, Manal; Montes-Bayon, Maria; Wu, Carol P.; Reisinger, Sarah J.; Terry, Norman

2006-01-01

A major goal of our selenium (Se) phytoremediation research is to use genetic engineering to develop fast-growing plants with an increased ability to tolerate, accumulate, and volatilize Se. To this end we incorporated a gene (encoding selenocysteine methyltransferase, SMT) from the Se hyperaccumulator, Astragalus bisulcatus, into Indian mustard (LeDuc, D.L., Tarun, A.S., Montes-Bayon, M., Meija, J., Malit, M.F., Wu, C.P., AbdelSamie, M., Chiang, C.-Y., Tagmount, A., deSouza, M., Neuhierl, B., Boeck, A., Caruso, J., Terry, N., 2004. Overexpression of selenocysteine methyltransferase in Arabidopsis and Indian mustard increases selenium tolerance and accumulation Plant Physiol. 135, 377-383.). The resulting transgenic plants successfully enhanced Se phytoremediation in that the plants tolerated and accumulated Se from selenite significantly better than wild type. However, the advantage conferred by the SMT enzyme was much less when Se was supplied as selenate. In order to enhance the phytoremediation of selenate, we developed double transgenic plants that overexpressed the gene encoding ATP sulfurylase (APS) in addition to SMT, i.e., APS x SMT. The results showed that there was a substantial improvement in Se accumulation from selenate (4 to 9 times increase) in transgenic plants overexpressing both APS and SMT. - Simultaneous overexpression of APS and SMT genes in Indian mustard greatly increases ability to accumulate selenate

Achievement report for fiscal 1992 on Sunshine Program-entrusted research and development. Research and development of high-efficiency solar cells (Research on forbidden band width optimization); 1992 nendo kokoritsu taiyo denchi no kenkyu kaihatsu seika hokokusho. Kinsei taifuku no saitekika no kenkyu

Energy Technology Data Exchange (ETDEWEB)

NONE

1993-03-01

Research is carried out on technologies concerning CuInSe{sub 2} thin-film solar cell manufacturing, thin film formation, thin film characterization, CdS, (CdZn)S formation, CuInSe{sub 2} single junction, analysis of the a-Si/CuInSe{sub 2} tandem solar cell operating theory, etc. In relation with the encapsulated selenization method for film formation for CuInSe{sub 2} thin-film solar cells, film constitution, film thickness, selenization temperature, etc., are studied for optimization. In relation with the vaporized selenization method, vaporized selenization is tested in a vacuum chamber aiming at improved homogeneity and reproducibility. In research on CdS and (CdZn)S which are window layer materials for CuInSe{sub 2} thin-film solar cells, CdS thin films are formed in a solution growth method using CdSO{sub 4} and (NH{sub 2}){sub 2}CS. In relation with the solution growth of the (CdZn)S crystal film, control of the Zn content in the film is now practicable. In the study of a-Si/CuInSe{sub 2} tandem solar cells, an analytical program is formulated, and calculation is made concerning the impacts of CuInSe{sub 2} forbidden band width and a-Si i-layer thickness. (NEDO)

Establishment of an atmospheric observatory for trace gases and atmospheric oxygen in Namibia

Science.gov (United States)

Morgan, E.; Lavrič, J.; Seely, M.; Heimann, M.

2012-04-01

Continuous, high-precision measurements of greenhouse and other biogeochemically significant atmospheric gases help to establish a global baseline and create important data for the study of atmospheric transport, biogeochemical fluxes, and human emissions. Also, they can validate models and ground- and space-based remote sensing and complement airborne atmospheric measurements. There are currently few such facilities on the African continent. To reduce this gap in the global observational system, we are establishing an atmospheric observatory at Gobabeb, Namibia. Continuous measurements of the atmospheric O2/N2 ratio and biogeochemical trace gases (CO2, CH4, N2O, CO) will be accompanied by a regular flask sampling program. Our observatory also represents an opportunity to forge partnerships with local and global scientific organizations. The site is well located to study the natural and anthropogenic gas fluxes on the southern subtropical African continent, and the air-sea gas fluxes of the nearby Benguela Current system off the Namibian coast. This current system drives one of the four major eastern-boundary upwelling ecosystems, creating zones of intensive primary production that influence the budgets of atmospheric gases via air-sea exchange. Another feature of interest is the large biomass burning region in central and southern Africa. An analysis of HYSPLIT air mass back trajectories from Gobabeb indicate that the dominant origin of air at the site is from one of these two areas. On-site installation of the standalone measurement system, which is installed in a 20' container, is scheduled for the first half of 2012. We present here the detailed setup of the system and first performance data.

Seasonal trends in vegetation and atmospheric concentrations of PAHs and PBDEs near a sanitary landfill

Science.gov (United States)

St-Amand, Annick D.; Mayer, Paul M.; Blais, Jules M.

Spruce needle and atmospheric (gaseous and particulate-bound) concentrations were surveyed near a sanitary landfill from February 2004 to June 2005. The influence of several parameters such as temperature, relative humidity, wind speed and direction, as well as increased domestic heating during the winter was assessed. In general, polybrominated diphenyl ethers (PBDE) and polycyclic aromatic hydrocarbons (PAH) concentrations in spruce needles increased over time and decreased following snowmelt with a minimum coinciding with bud burst of deciduous trees. Atmospheric concentrations of PBDE and PAH, both particulate-bound and gaseous phase, were linked to daily weather events and thus showed more variability than those in spruce needles. Highest PAH concentrations were encountered during the winter, likely reflecting increased emission from heating homes. Pseudo Clausius-Clapeyron plots revealed higher PBDE gaseous concentrations with increasing temperature, but showed no correlation between PAH gaseous concentrations and temperature as this effect was obscured by seasonal emission patterns. Finally, air mass back trajectories and local wind directions revealed that particulate-bound PBDEs, along with both gaseous and particulate-bound PAHs were from local sources, whereas gaseous PBDEs were likely from distant sources.

Atmospheric turbidity parameters affecting the incident solar solar radiation for two different areas in (Eg))

International Nuclear Information System (INIS)

Tadros, M.T.Y.; Mosalam, M.A.; El-metwally, M.

1999-01-01

Atmospheric turbidity parameters such as Linke turbidity (L-0) and true Angstrom parameters (Bita o , Alpha 0 ) have been determined from the measurements of direct solar radiation for entire spectrum and for specified spectral bands during one year starting from june 1992 to may 1993. Comparison between the industrial area in Helwan (south Cairo) with that of the agricultural area in Mansoura, in (Eg), was done. Analysis of data revealed that the atmospheric turbidity parameters (L Beta) in Helwan is higher than that in Mansoura, except for hot wet months. The increase of L in Mansoura, in summer, is due to the increase of water vapor content. The wavelength exponent Alpha shows that the size the size of particles in Helwan is larger than that in Mansoura

Gravity Waves in the Atmosphere of Mars as seen by the Radio Science Experiment MaRS on Mars Express

Science.gov (United States)

Tellmann, S.; Paetzold, M.; Häusler, B.; Bird, M. K.; Tyler, G. L.; Hinson, D. P.

2016-12-01

Gravity waves are atmospheric waves whose restoring force is the buoyancy. They are known to play an essential role in the redistribution of energy, momentum and atmospheric constituents in all stably stratified planetary atmospheres. Possible excitation mechanisms comprise convection in an adjacent atmospheric layer, other atmospheric instabilities like wind shear instabilities, or air flow over orographic obstacles especially in combination with the strong winter jets on Mars. Gravity waves on Mars were observed in the lower atmosphere [1,2] but are also expected to play a major role in the cooling of the thermosphere [3] and the polar warming [4]. A fundamental understanding of the possible source mechanisms is required to reveal the influence of small scale gravity waves on the global atmospheric circulation. Radio occultation profiles from the MaRS experiment on Mars Express [5] with their exceptionally high vertical resolution can be used to study small-scale vertical gravity waves and their global distribution in the lower atmosphere from the planetary boundary layer up to 40 km altitude. Atmospheric instabilities, which are clearly identified in the data, are used to gain further insight into possible atmospheric processes contributing to the excitation of gravity waves. [1] Creasey, J. E., et al.,(2006), Geophys. Res. Lett., 33, L01803, doi:10.1029/2005GL024037. [2]Tellmann, S., et al.(2013), J. Geophys. Res. Planets, 118, 306-320, doi:10.1002/jgre.20058. [3]Medvedev, A. S., et al.(2015), J. Geophys. Res. Planets, 120, 913-927. doi:10.1002/2015JE004802.[4] Barnes, J. R. (1990), J. Geophys. Res., 95, B2, 1401-1421. [5] Pätzold, M., et al. (2016), Planet. Space Sci., 127, 44 - 90.

Proterozoic atmospheric oxygen

DEFF Research Database (Denmark)

Canfield, Donald Eugene

2014-01-01

This article is concerned with the evolution of atmospheric oxygen concentrations through the Proterozoic Eon. In particular, this article will seek to place the history of atmospheric oxygenation through the Proterozoic Eon in the context of the evolving physical environment including the history...... of continental growth and volcanic outgassing, as well as biogeochemical processing of elements within the oceans. The author will seek to explore constraints on the history of oxygenation and understand which processes have regulated oxygen through this eon....

A SEARCH FOR WATER IN THE ATMOSPHERE OF HAT-P-26b USING LDSS-3C

Energy Technology Data Exchange (ETDEWEB)

Stevenson, Kevin B.; Bean, Jacob L.; Seifahrt, Andreas; Gilbert, Gregory J. [Department of Astronomy and Astrophysics, University of Chicago, 5640 S Ellis Avenue, Chicago, IL 60637 (United States); Line, Michael R. [NASA Ames Research Center, Moffett Field, CA 94035 (United States); Désert, Jean-Michel [Anton Pannekoek Institute for Astronomy, University of Amsterdam, Amsterdam (Netherlands); Fortney, Jonathan J., E-mail: kbs@uchicago.edu [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States)

2016-02-01

The characterization of a physically diverse set of transiting exoplanets is an important and necessary step toward establishing the physical properties linked to the production of obscuring clouds or hazes. It is those planets with identifiable spectroscopic features that can most effectively enhance our understanding of atmospheric chemistry and metallicity. The newly commissioned LDSS-3C instrument on Magellan provides enhanced sensitivity and suppressed fringing in the red optical, thus advancing the search for the spectroscopic signature of water in exoplanetary atmospheres from the ground. Using data acquired by LDSS-3C and the Spitzer Space Telescope, we search for evidence of water vapor in the transmission spectrum of the Neptune-mass planet HAT-P-26b. Our measured spectrum is best explained by the presence of water vapor, a lack of potassium, and either a high-metallicity, cloud-free atmosphere or a solar-metallicity atmosphere with a cloud deck at ∼10 mbar. The emergence of multi-scale-height spectral features in our data suggests that future observations at higher precision could break this degeneracy and reveal the planet’s atmospheric chemical abundances. We also update HAT-P-26b’s transit ephemeris, t{sub 0} = 2455304.65218(25) BJD{sub TDB}, and orbital period, p = 4.2345023(7) days.

Evaluating the Contributions of Atmospheric Deposition of Carbon and Other Nutrients to Nitrification in Alpine Environments

Science.gov (United States)

Oldani, K. M.; Mladenov, N.; Williams, M. W.

2013-12-01

The Colorado Front Range of the Rocky Mountains contains undeveloped, barren soils, yet in this environment there is strong evidence for a microbial role in increased nitrogen (N) export. Barren soils in alpine environments are severely carbon-limited, which is the main energy source for microbial activity and sustenance of life. It has been shown that atmospheric deposition can contain high amounts of organic carbon (C). Atmospheric pollutants, dust events, and biological aerosols, such as bacteria, may be important contributors to the atmospheric organic C load. In this stage of the research we evaluated seasonal trends in the chemical composition and optical spectroscopic (fluorescence and UV-vis absorbance) signatures of snow, wet deposition, and dry deposition in an alpine environment at Niwot Ridge in the Rocky Mountains of Colorado to obtain a better understanding of the sources and chemical character of atmospheric deposition. Our results reveal a positive trend between dissolved organic carbon concentrations and calcium, nitrate and sulfate concentrations in wet and dry deposition, which may be derived from such sources as dust and urban air pollution. We also observed the presence of seasonally-variable fluorescent components that may be attributed to fluorescent pigments in bacteria. These results are relevant because atmospheric inputs of carbon and other nutrients may influence nitrification in barren, alpine soils and, ultimately, the export of nitrate to alpine watersheds.

The ward atmosphere important for the psychosocial work environment of nursing staff in psychiatric in-patient care.

Science.gov (United States)

Tuvesson, Hanna; Wann-Hansson, Christine; Eklund, Mona

2011-06-16

The nursing staff working in psychiatric care have a demanding work situation, which may be reflected in how they view their psychosocial work environment and the ward atmosphere. The aims of the present study were to investigate in what way different aspects of the ward atmosphere were related to the psychosocial work environment, as perceived by nursing staff working in psychiatric in-patient care, and possible differences between nurses and nurse assistants. 93 nursing staff working at 12 general psychiatric in-patient wards in Sweden completed two questionnaires, the Ward Atmosphere Scale and the QPSNordic 34+. Data analyses included descriptive statistics, the Mann-Whitney U-test, Spearman rank correlations and forward stepwise conditional logistic regression analyses. The data revealed that there were no differences between nurses and nurse assistants concerning perceptions of the psychosocial work environment and the ward atmosphere. The ward atmosphere subscales Personal Problem Orientation and Program Clarity were associated with a psychosocial work environment characterized by Empowering Leadership. Program Clarity was related to the staff's perceived Role Clarity, and Practical Orientation and Order and Organization were positively related to staff perceptions of the Organizational Climate. The results from the present study indicate that several ward atmosphere subscales were related to the nursing staff's perceptions of the psychosocial work environment in terms of Empowering Leadership, Role Clarity and Organizational Climate. Improvements in the ward atmosphere could be another way to accomplish improvements in the working conditions of the staff, and such improvements would affect nurses and nurse assistants in similar ways.

The ward atmosphere important for the psychosocial work environment of nursing staff in psychiatric in-patient care

Directory of Open Access Journals (Sweden)

Wann-Hansson Christine

2011-06-01

Full Text Available Abstract Background The nursing staff working in psychiatric care have a demanding work situation, which may be reflected in how they view their psychosocial work environment and the ward atmosphere. The aims of the present study were to investigate in what way different aspects of the ward atmosphere were related to the psychosocial work environment, as perceived by nursing staff working in psychiatric in-patient care, and possible differences between nurses and nurse assistants. Methods 93 nursing staff working at 12 general psychiatric in-patient wards in Sweden completed two questionnaires, the Ward Atmosphere Scale and the QPSNordic 34+. Data analyses included descriptive statistics, the Mann-Whitney U-test, Spearman rank correlations and forward stepwise conditional logistic regression analyses. Results The data revealed that there were no differences between nurses and nurse assistants concerning perceptions of the psychosocial work environment and the ward atmosphere. The ward atmosphere subscales Personal Problem Orientation and Program Clarity were associated with a psychosocial work environment characterized by Empowering Leadership. Program Clarity was related to the staff's perceived Role Clarity, and Practical Orientation and Order and Organization were positively related to staff perceptions of the Organizational Climate. Conclusions The results from the present study indicate that several ward atmosphere subscales were related to the nursing staff's perceptions of the psychosocial work environment in terms of Empowering Leadership, Role Clarity and Organizational Climate. Improvements in the ward atmosphere could be another way to accomplish improvements in the working conditions of the staff, and such improvements would affect nurses and nurse assistants in similar ways.

Magnetospheric structure and atmospheric Joule heating of habitable planets orbiting M-dwarf stars

Energy Technology Data Exchange (ETDEWEB)

Cohen, O.; Drake, J. J.; Garraffo, C.; Poppenhaeger, K. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Glocer, A. [NASA/GSFC, Code 673, Greenbelt, MD 20771 (United States); Bell, J. M. [Center for Planetary Atmospheres and Flight Sciences, National Institute of Aerospace, Hampton, VA 23666 (United States); Ridley, A. J.; Gombosi, T. I. [Center for Space Environment Modeling, University of Michigan, 2455 Hayward Street, Ann Arbor, MI 48109 (United States)

2014-07-20

We study the magnetospheric structure and the ionospheric Joule Heating of planets orbiting M-dwarf stars in the habitable zone using a set of magnetohydrodynamic models. The stellar wind solution is used to drive a model for the planetary magnetosphere, which is coupled with a model for the planetary ionosphere. Our simulations reveal that the space environment around close-in habitable planets is extreme, and the stellar wind plasma conditions change from sub- to super-Alfvénic along the planetary orbit. As a result, the magnetospheric structure changes dramatically with a bow shock forming in the super-Alfvénic sectors, while no bow shock forms in the sub-Alfvénic sectors. The planets reside most of the time in the sub-Alfvénic sectors with poor atmospheric protection. A significant amount of Joule Heating is provided at the top of the atmosphere as a result of the intense stellar wind. For the steady-state solution, the heating is about 0.1%-3% of the total incoming stellar irradiation, and it is enhanced by 50% for the time-dependent case. The significant Joule Heating obtained here should be considered in models for the atmospheres of habitable planets in terms of the thickness of the atmosphere, the top-side temperature and density, the boundary conditions for the atmospheric pressure, and particle radiation and transport. Here we assume constant ionospheric Pedersen conductance similar to that of the Earth. The conductance could be greater due to the intense EUV radiation leading to smaller heating rates. We plan to quantify the ionospheric conductance in future study.

The Upper Atmosphere; Threshold of Space.

Science.gov (United States)

Bird, John

This booklet contains illustrations of the upper atmosphere, describes some recent discoveries, and suggests future research questions. It contains many color photographs. Sections include: (1) "Where Does Space Begin?"; (2) "Importance of the Upper Atmosphere" (including neutral atmosphere, ionized regions, and balloon and investigations); (3)…

Calculation of atmospheric neutrino flux using the interaction model calibrated with atmospheric muon data

International Nuclear Information System (INIS)

Honda, M.; Kajita, T.; Kasahara, K.; Midorikawa, S.; Sanuki, T.

2007-01-01

Using the 'modified DPMJET-III' model explained in the previous paper [T. Sanuki et al., preceding Article, Phys. Rev. D 75, 043005 (2007).], we calculate the atmospheric neutrino flux. The calculation scheme is almost the same as HKKM04 [M. Honda, T. Kajita, K. Kasahara, and S. Midorikawa, Phys. Rev. D 70, 043008 (2004).], but the usage of the 'virtual detector' is improved to reduce the error due to it. Then we study the uncertainty of the calculated atmospheric neutrino flux summarizing the uncertainties of individual components of the simulation. The uncertainty of K-production in the interaction model is estimated using other interaction models: FLUKA'97 and FRITIOF 7.02, and modifying them so that they also reproduce the atmospheric muon flux data correctly. The uncertainties of the flux ratio and zenith angle dependence of the atmospheric neutrino flux are also studied

Hydrodynamic escape from planetary atmospheres

Science.gov (United States)

Tian, Feng

Hydrodynamic escape is an important process in the formation and evolution of planetary atmospheres. Due to the existence of a singularity point near the transonic point, it is difficult to find transonic steady state solutions by solving the time-independent hydrodynamic equations. In addition to that, most previous works assume that all energy driving the escape flow is deposited in one narrow layer. This assumption not only results in less accurate solutions to the hydrodynamic escape problem, but also makes it difficult to include other chemical and physical processes in the hydrodynamic escape models. In this work, a numerical model describing the transonic hydrodynamic escape from planetary atmospheres is developed. A robust solution technique is used to solve the time dependent hydrodynamic equations. The method has been validated in an isothermal atmosphere where an analytical solution is available. The hydrodynamic model is applied to 3 cases: hydrogen escape from small orbit extrasolar planets, hydrogen escape from a hydrogen rich early Earth's atmosphere, and nitrogen/methane escape from Pluto's atmosphere. Results of simulations on extrasolar planets are in good agreement with the observations of the transiting extrasolar planet HD209458b. Hydrodynamic escape of hydrogen from other hypothetical close-in extrasolar planets are simulated and the influence of hydrogen escape on the long-term evolution of these extrasolar planets are discussed. Simulations on early Earth suggest that hydrodynamic escape of hydrogen from a hydrogen rich early Earth's atmosphere is about two orders magnitude slower than the diffusion limited escape rate. A hydrogen rich early Earth's atmosphere could have been maintained by the balance between the hydrogen escape and the supply of hydrogen into the atmosphere by volcanic outgassing. Origin of life may have occurred in the organic soup ocean created by the efficient formation of prebiotic molecules in the hydrogen rich early

Atmospheric correction of APEX hyperspectral data

Directory of Open Access Journals (Sweden)

Sterckx Sindy

2016-03-01

Full Text Available Atmospheric correction plays a crucial role among the processing steps applied to remotely sensed hyperspectral data. Atmospheric correction comprises a group of procedures needed to remove atmospheric effects from observed spectra, i.e. the transformation from at-sensor radiances to at-surface radiances or reflectances. In this paper we present the different steps in the atmospheric correction process for APEX hyperspectral data as applied by the Central Data Processing Center (CDPC at the Flemish Institute for Technological Research (VITO, Mol, Belgium. The MODerate resolution atmospheric TRANsmission program (MODTRAN is used to determine the source of radiation and for applying the actual atmospheric correction. As part of the overall correction process, supporting algorithms are provided in order to derive MODTRAN configuration parameters and to account for specific effects, e.g. correction for adjacency effects, haze and shadow correction, and topographic BRDF correction. The methods and theory underlying these corrections and an example of an application are presented.

Composition of Estonian atmosphere

International Nuclear Information System (INIS)

Punning, J. M.; Karindi, A.

1996-01-01

Atmospheric study, particularly that of its chemical composition, has a long tradition in Estonia. Since middle of this century, in addition to meteorological observations, some chemical compounds in precipitations have been regularly measured in many meteorological stations. The main aim was to acquire information about the state and dynamics of the atmosphere. Therefore, main attention was paid to monitoring chemical compounds which have a direct impact on the human environment. As energy production developed intensively and SO 2 and NO x increased drastically in the atmosphere in acidic rock areas, like Scandinavia, the problem of acid rain became the most important environmental problem in Europe and North-America. As a consequence, monitoring the compounds of sulphur in precipitation was organized in Estonia. In the 1970 s, as related to large operating oil shale-based power plants, Estonia became a country , where emissions of sulphur compounds per capita were extremely high. In 1979, Estonia became a participant in the European Monitoring and Evaluation Programme - the network created to study transboundary air pollution. The aims of the precipitation chemistry study and the related problems of the formation and transformation of the atmospheric composition have varied over the years. But monitoring of pollutant (in particular, sulphur compound) loads has been a central issue. Over recent years, an attempt was made to estimate the spatial regularities of atmospheric impurities and their impact on the pH of mean monthly precipitations. Furthermore, calculations were provided to find out the origin of atmospheric impurities washed out in Estonia. Until the 1990 s, CO 2 , and some other greenhouse gas (GHG) emissions were not studied in Estonia. The first inventory of GHG for Estonia was provided in 1995 using the Intergovernmental Panel on Climate Change (IPCC) methodology

Non-toxic novel route synthesis and characterization of nanocrystalline ZnS{sub x}Se{sub 1−x} thin films with tunable band gap characteristics

Energy Technology Data Exchange (ETDEWEB)

Agawane, G.L., E-mail: agawaneganesh@gmail.com [Department of Materials Science and Engineering, Chonnam National University, Gwangju 500-757 (Korea, Republic of); Shin, Seung Wook [Department of Materials Science and Engineering, KAIST, Daejeon 305-701 (Korea, Republic of); Vanalakar, S.A. [Department of Materials Science and Engineering, Chonnam National University, Gwangju 500-757 (Korea, Republic of); Moholkar, A.V. [Electrochemical Mat. Lab., Department of Physics, Shivaji University, Kolhapur 416-004 (India); Gurav, K.V.; Suryawanshi, M.P. [Department of Materials Science and Engineering, Chonnam National University, Gwangju 500-757 (Korea, Republic of); Lee, Jeong Yong [Department of Materials Science and Engineering, KAIST, Daejeon 305-701 (Korea, Republic of); Yun, Jae Ho, E-mail: yunjh92@kier.re.kr [Photovoltaic Research Group, KIER, Jang-Dong, Yuseong-Gu, Daejeon 305-343 (Korea, Republic of); Kim, Jin Hyeok, E-mail: jinhyeok@chonnam.ac.kr [Department of Materials Science and Engineering, Chonnam National University, Gwangju 500-757 (Korea, Republic of)

2014-07-01

Highlights: • A simple, inexpensive, and non-toxic CBD route is used to deposit ZnS thin films. • The ZnS{sub x}Se{sub 1−x} thin films formation takes place via annealing of ZnS thin films in Se atmosphere. • S/(S + Se) ratio found to be temperature dependent and easy tuning of band gap has been done by Se atom deposition. - Abstract: An environmentally benign chemical bath deposition (CBD) route was employed to deposit zinc sulfide (ZnS) thin films. The CBD-ZnS thin films were further selenized in a furnace at various temperatures viz. 200, 300, 400, and 500 °C and the S/(S + Se) ratio was found to be dependent on the annealing temperature. The effects of S/(S + Se) ratio on the structural, compositional and optical properties of the ZnS{sub x}Se{sub 1−x} (ZnSSe) thin films were investigated. EDS analysis showed that the S/(S + Se) ratio decreased from 0.8 to 0.6 when the film annealing temperature increased from 200 to 500 °C. The field emission scanning electron microscopy and atomic force microscopy studies showed that all the films were uniform, pin hole free, smooth, and adhered well to the glass substrate. The X-ray diffraction study on the ZnSSe thin films showed the formation of the cubic phase, except for the unannealed ZnSSe thin film, which showed an amorphous phase. The X-ray photoelectron spectroscopy revealed Zn-S, Zn-Se, and insignificant Zn-OH bonds formation from the Zn 2p{sub 3/2}, S 2p, Se 3d{sub 5/2}, and O 1s atomic states, respectively. The ultraviolet–visible spectroscopy study showed ∼80% transmittance in the visible region for all the ZnSSe thin films having various absorption edges. The tuning of the band gap energy of the ZnSSe thin films was carried out by selenizing CBD-ZnS thin films, and as the S/(S + Se) ratio decreased from 0.8 to 0.6, the band gap energy decreased from 3.20 to 3.12 eV.

Microwave Atmospheric-Pressure Sensor

Science.gov (United States)

Flower, D. A.; Peckham, G. E.; Bradford, W. J.

1986-01-01

Report describes tests of microwave pressure sounder (MPS) for use in satellite measurements of atmospheric pressure. MPS is multifrequency radar operating between 25 and 80 GHz. Determines signal absorption over vertical path through atmosphere by measuring strength of echoes from ocean surface. MPS operates with cloud cover, and suitable for use on current meteorological satellites.

Revealing Invisible Water: Moisture Recycling as an Ecosystem Service.

Science.gov (United States)

Keys, Patrick W; Wang-Erlandsson, Lan; Gordon, Line J

2016-01-01

An ecosystem service is a benefit derived by humanity that can be traced back to an ecological process. Although ecosystem services related to surface water have been thoroughly described, the relationship between atmospheric water and ecosystem services has been mostly neglected, and perhaps misunderstood. Recent advances in land-atmosphere modeling have revealed the importance of terrestrial ecosystems for moisture recycling. In this paper, we analyze the extent to which vegetation sustains the supply of atmospheric moisture and precipitation for downwind beneficiaries, globally. We simulate land-surface evaporation with a global hydrology model and track changes to moisture recycling using an atmospheric moisture budget model, and we define vegetation-regulated moisture recycling as the difference in moisture recycling between current vegetation and a hypothetical desert world. Our results show that nearly a fifth of annual average precipitation falling on land is from vegetation-regulated moisture recycling, but the global variability is large, with many places receiving nearly half their precipitation from this ecosystem service. The largest potential impacts for changes to this ecosystem service are land-use changes across temperate regions in North America and Russia. Likewise, in semi-arid regions reliant on rainfed agricultural production, land-use change that even modestly reduces evaporation and subsequent precipitation, could significantly affect human well-being. We also present a regional case study in the Mato Grosso region of Brazil, where we identify the specific moisture recycling ecosystem services associated with the vegetation in Mato Grosso. We find that Mato Grosso vegetation regulates some internal precipitation, with a diffuse region of benefit downwind, primarily to the south and east, including the La Plata River basin and the megacities of Sao Paulo and Rio de Janeiro. We synthesize our global and regional results into a generalized

Atmospheric and aerosol chemistry

Energy Technology Data Exchange (ETDEWEB)

McNeill, V. Faye [Columbia Univ., New York, NY (United States). Dept. of Chemical Engineering; Ariya, Parisa A. (ed.) [McGill Univ. Montreal, QC (Canada). Dept. of Chemistry; McGill Univ. Montreal, QC (Canada). Dept. of Atmospheric and Oceanic Sciences

2014-09-01

This series presents critical reviews of the present position and future trends in modern chemical research. Short and concise reports on chemistry, each written by the world renowned experts. Still valid and useful after 5 or 10 years. More information as well as the electronic version of the whole content available at: springerlink.com. Christian George, Barbara D'Anna, Hartmut Herrmann, Christian Weller, Veronica Vaida, D. J. Donaldson, Thorsten Bartels-Rausch, Markus Ammann Emerging Areas in Atmospheric Photochemistry. Lisa Whalley, Daniel Stone, Dwayne Heard New Insights into the Tropospheric Oxidation of Isoprene: Combining Field Measurements, Laboratory Studies, Chemical Modelling and Quantum Theory. Neil M. Donahue, Allen L. Robinson, Erica R. Trump, Ilona Riipinen, Jesse H. Kroll Volatility and Aging of Atmospheric Organic Aerosol. P. A. Ariya, G. Kos, R. Mortazavi, E. D. Hudson, V. Kanthasamy, N. Eltouny, J. Sun, C. Wilde Bio-Organic Materials in the Atmosphere and Snow: Measurement and Characterization V. Faye McNeill, Neha Sareen, Allison N. Schwier Surface-Active Organics in Atmospheric Aerosols.

Astronomy and Atmospheric Optics

Science.gov (United States)

Cowley, Les; Gaina, Alex

2011-12-01

The authors discusse the insuccess of the observation of the Total Eclipse of the Moon from 10 december 2011 in Romania and relate them with meteoconditions. Only a very short part of the last penumbral phase was observed, while the inital part and the totality was not observed due to very dense clouds. The change in color and brightness during this phase was signaled. Meanwhile, there is an area of science where clouds are of great use and interest. This area is Atmospheric optics, while the science which study clouds is meteorology. Clouds in combination with Solar and Moon light could give rise to a variety of strange, rare and unobvious phenomena in the atmosphere (sky), sometimes confused with Unidentified Flying Objects (UFO). The importance of meteorology for astronomy and atmospheric optics is underlined and an invitation to astronomers to use unfavourable days for athmospheric observations was sent. The web address of the site by Les Cowley, designed for atmospheric optics phenomena is contained in the text of the entry.

Climate and atmospheric research

International Nuclear Information System (INIS)

Kramer, G.; Schumacher, R.

1992-01-01

This issue of the scientific journal of the Humboldt university is dedicated to results of research work carried out to the greatest extent at the meteorological institute in the last two years on the area of climate and atmospheric research. The traditional research areas of the institute are climatology and the dynamics of the atmosphere, in particular the atmospherical boundary layer. Considering the high probability of a global climatic fluctuation due to the anthropogenic change of composition of the atmosphere and other climate-relevant factors imminent in the next century, climatological research today is an important part of global and regional environmental research. From the necessity of determination and evaluation of the effect of climatic fluctuations on nature and society the contours of a new interdisciplinary research area are already visible now. This is suitable as hardly any other area to be the supporting idea of environmental research at universities. The contributions contained in the issue already consider, in addition to results on climate diagnosis, also results on aspects of climate effect research. (orig./KW) [de

Analysis of wave-like oscillations in parameters of sporadic E layer and neutral atmosphere

Science.gov (United States)

Mošna, Z.; Koucká Knížová, P.

2012-12-01

The present study mainly concerns the wave-like activity in the ionospheric sporadic E layer (Es) and in the lower lying stratosphere. The proposed analysis involves parameters describing the state of plasma in the sporadic E layer. Critical frequencies foEs and layer heights hEs were measured at the Pruhonice station (50°N, 14.5°E) during summer campaigns 2004, 2006 and 2008. Further, we use neutral atmosphere (temperature data at 10 hPa) data from the same time interval. The analysis concentrates on vertically propagating wave-like structures within distant atmospheric regions. By means of continuous wavelet transform (CWT) we have detected significant wave-like oscillation at periods covering tidal and planetary oscillation domains both in the Es layer parameters (some of them were reported earlier, for instance in works of Abdu et al., 2003; Pancheva and Mitchel, 2004; Pancheva et al., 2003; Šauli and Bourdillon, 2008) and in stratospheric temperature variations. Further analyses using cross wavelet transform (XWT) and wavelet coherence analysis (WTC) show that despite high wave-like activity in a wide period range, there are only limited coherent wave-like bursts present in both spectra. Such common coherent wave bursts occur on periods close to eigen-periods of the terrestrial atmosphere. We suppose that vertical coupling between atmospheric regions realized by vertically propagating planetary waves occurs predominantly on periods close to those of Rossby modes. Analysis of the phase shift between data from distant atmospheric regions reveals high variability and very likely supports the non-linear scenario of the vertical coupling provided by planetary waves.

Lord Kelvin's atmospheric electricity measurements

Science.gov (United States)

Aplin, Karen; Harrison, R. Giles; Trainer, Matthew; Hough, James

2013-04-01

Lord Kelvin (William Thomson), one of the greatest Victorian scientists, made a substantial but little-recognised contribution to geophysics through his work on atmospheric electricity. He developed sensitive instrumentation for measuring the atmospheric electric field, including invention of a portable electrometer, which made mobile measurements possible for the first time. Kelvin's measurements of the atmospheric electric field in 1859, made during development of the portable electrometer, can be used to deduce the substantial levels of particulate pollution blown over the Scottish island of Arran from the industrial mainland. Kelvin was also testing the electrometer during the largest solar flare ever recorded, the "Carrington event" in the late summer of 1859. Subsequently, Lord Kelvin also developed a water dropper sensor, and employed photographic techniques for "incessant recording" of the atmospheric electric field, which led to the long series of measurements recorded at UK observatories for the remainder of the 19th and much of the 20th century. These data sets have been valuable in both studies of historical pollution and cosmic ray effects on atmospheric processes.

Atmospheric ions and pollution

International Nuclear Information System (INIS)

Renoux, A.

1977-01-01

The various types of atmospheric ions are defined, the main sources of natural atmospheric radioactivity inducing the formation of radioactive ions in the air are then recalled. The basic equations governing the formation of these ions are indicated and the most current experimental methods used for detecting them are described (Zeleny tubes, Erikson tubes). The special properties of these ions are examined, they are particularly emphasized for the smaller ones. The existence of a discret spectrum of mobilities is shown and the presence of big negative radioactive ions is investigated. Indicative information are given on the granulometric distribution of the atmospheric radioactivity in the air, from small positive Ra A ion fixation on aerosols [fr

Experimental and Numerical Modelling of CO2 Atmospheric Dispersion in Hazardous Gas Emission Sites.

Science.gov (United States)

Gasparini, A.; sainz Gracia, A. S.; Grandia, F.; Bruno, J.

2015-12-01

Under stable atmospheric conditions and/or in presence of topographic depressions, CO2 concentrations can reach high values resulting in lethal effect to living organisms. The distribution of denser than air gases released from the underground is governed by gravity, turbulence and dispersion. Once emitted, the gas distribution is initially driven by buoyancy and a gas cloud accumulates on the ground (gravitational phase); with time the density gradient becomes less important due to dispersion or mixing and gas distribution is mainly governed by wind and atmospheric turbulence (passive dispersion phase). Natural analogues provide evidences of the impact of CO2 leakage. Dangerous CO2 concentration in atmosphere related to underground emission have been occasionally reported although the conditions favouring the persistence of such a concentration are barely studied.In this work, the dynamics of CO2 in the atmosphere after ground emission is assessed to quantify their potential risk. Two approaches have been followed: (1) direct measurement of air concentration in a natural emission site, where formation of a "CO2 lake" is common and (2) numerical atmospheric modelling. Two sites with different morphology were studied: (a) the Cañada Real site, a flat terrain in the Volcanic Field of Campo de Calatrava (Spain); (b) the Solforata di Pomezia site, a rough terrain in the Alban Hills Volcanic Region (Italy). The comparison between field data and model calculations reveal that numerical dispersion models are capable of predicting the formation of CO2 accumulation over the ground as a consequence of underground gas emission. Therefore, atmospheric modelling could be included as a valuable methodology in the risk assessment of leakage in natural degassing systems and in CCS projects. Conclusions from this work provide clues on whether leakage may be a real risk for humans and under which conditions this risk needs to be included in the risk assessment.

Ozone, Climate, and Global Atmospheric Change.

Science.gov (United States)

Levine, Joel S.

1992-01-01

Presents an overview of global atmospheric problems relating to ozone depletion and global warming. Provides background information on the composition of the earth's atmosphere and origin of atmospheric ozone. Describes causes, effects, and evidence of ozone depletion and the greenhouse effect. A vignette provides a summary of a 1991 assessment of…

First retrieval of hourly atmospheric radionuclides just after the Fukushima accident by analyzing filter-tapes of operational air pollution monitoring stations.

Science.gov (United States)

Tsuruta, Haruo; Oura, Yasuji; Ebihara, Mitsuru; Ohara, Toshimasa; Nakajima, Teruyuki

2014-10-22

No observed data have been found in the Fukushima Prefecture (FP) for the time-series of atmospheric radionuclides concentrations just after the Fukushima Daiichi Nuclear Power Plant (FD1NPP) accident. Accordingly, current estimates of internal radiation doses from inhalation, and atmospheric radionuclide concentrations by atmospheric transport models are highly uncertain. Here, we present a new method for retrieving the hourly atmospheric (137)Cs concentrations by measuring the radioactivity of suspended particulate matter (SPM) collected on filter tapes in SPM monitors which were operated even after the accident. This new dataset focused on the period of March 12-23, 2011 just after the accident, when massive radioactive materials were released from the FD1NPP to the atmosphere. Overall, 40 sites of the more than 400 sites in the air quality monitoring stations in eastern Japan were studied. For the first time, we show the spatio-temporal variation of atmospheric (137)Cs concentrations in the FP and the Tokyo Metropolitan Area (TMA) located more than 170 km southwest of the FD1NPP. The comprehensive dataset revealed how the polluted air masses were transported to the FP and TMA, and can be used to re-evaluate internal exposure, time-series radionuclides release rates, and atmospheric transport models.

First retrieval of hourly atmospheric radionuclides just after the Fukushima accident by analyzing filter-tapes of operational air pollution monitoring stations

Science.gov (United States)

Tsuruta, Haruo; Oura, Yasuji; Ebihara, Mitsuru; Ohara, Toshimasa; Nakajima, Teruyuki

2014-01-01

No observed data have been found in the Fukushima Prefecture (FP) for the time-series of atmospheric radionuclides concentrations just after the Fukushima Daiichi Nuclear Power Plant (FD1NPP) accident. Accordingly, current estimates of internal radiation doses from inhalation, and atmospheric radionuclide concentrations by atmospheric transport models are highly uncertain. Here, we present a new method for retrieving the hourly atmospheric 137Cs concentrations by measuring the radioactivity of suspended particulate matter (SPM) collected on filter tapes in SPM monitors which were operated even after the accident. This new dataset focused on the period of March 12–23, 2011 just after the accident, when massive radioactive materials were released from the FD1NPP to the atmosphere. Overall, 40 sites of the more than 400 sites in the air quality monitoring stations in eastern Japan were studied. For the first time, we show the spatio-temporal variation of atmospheric 137Cs concentrations in the FP and the Tokyo Metropolitan Area (TMA) located more than 170 km southwest of the FD1NPP. The comprehensive dataset revealed how the polluted air masses were transported to the FP and TMA, and can be used to re-evaluate internal exposure, time-series radionuclides release rates, and atmospheric transport models. PMID:25335435

Organic chemistry in the atmosphere. [laboratory modeling of Titan atmosphere

Science.gov (United States)

Sagan, C.

1974-01-01

The existence of an at least moderately complex organic chemistry on Titan is stipulated based on clear evidence of methane, and at least presumptive evidence of hydrogen in its atmosphere. The ratio of methane to hydrogen is the highest of any atmosphere in the solar system. Irradiation of hydrogen/methane mixtures produces aromatic and aliphatic hydrocarbons. A very reasonable hypothesis assumes that the red cloud cover of Titan is made of organic chemicals. Two-carbon hydrocarbons experimentally produced from irradiated mixtures of methane, ammonia, water, and hydrogen bear out the possible organic chemistry of the Titanian environment.

Stochastic background of atmospheric cascades

International Nuclear Information System (INIS)

Wilk, G.; Wlodarczyk, Z.

1993-01-01

Fluctuations in the atmospheric cascades developing during the propagation of very high energy cosmic rays through the atmosphere are investigated using stochastic branching model of pure birth process with immigration. In particular, we show that the multiplicity distributions of secondaries emerging from gamma families are much narrower than those resulting from hadronic families. We argue that the strong intermittent like behaviour found recently in atmospheric families results from the fluctuations in the cascades themselves and are insensitive to the details of elementary interactions

Assessment of Atmospheric Correction Methods for Sentinel-2 MSI Images Applied to Amazon Floodplain Lakes

Directory of Open Access Journals (Sweden)

Vitor Souza Martins

2017-03-01

Full Text Available Satellite data provide the only viable means for extensive monitoring of remote and large freshwater systems, such as the Amazon floodplain lakes. However, an accurate atmospheric correction is required to retrieve water constituents based on surface water reflectance ( R W . In this paper, we assessed three atmospheric correction methods (Second Simulation of a Satellite Signal in the Solar Spectrum (6SV, ACOLITE and Sen2Cor applied to an image acquired by the MultiSpectral Instrument (MSI on-board of the European Space Agency’s Sentinel-2A platform using concurrent in-situ measurements over four Amazon floodplain lakes in Brazil. In addition, we evaluated the correction of forest adjacency effects based on the linear spectral unmixing model, and performed a temporal evaluation of atmospheric constituents from Multi-Angle Implementation of Atmospheric Correction (MAIAC products. The validation of MAIAC aerosol optical depth (AOD indicated satisfactory retrievals over the Amazon region, with a correlation coefficient (R of ~0.7 and 0.85 for Terra and Aqua products, respectively. The seasonal distribution of the cloud cover and AOD revealed a contrast between the first and second half of the year in the study area. Furthermore, simulation of top-of-atmosphere (TOA reflectance showed a critical contribution of atmospheric effects (>50% to all spectral bands, especially the deep blue (92%–96% and blue (84%–92% bands. The atmospheric correction results of the visible bands illustrate the limitation of the methods over dark lakes ( R W < 1%, and better match of the R W shape compared with in-situ measurements over turbid lakes, although the accuracy varied depending on the spectral bands and methods. Particularly above 705 nm, R W was highly affected by Amazon forest adjacency, and the proposed adjacency effect correction minimized the spectral distortions in R W (RMSE < 0.006. Finally, an extensive validation of the methods is required for

Selenium Uptake and Volatilization by Marine Algae

Science.gov (United States)

Luxem, Katja E.; Vriens, Bas; Wagner, Bettina; Behra, Renata; Winkel, Lenny H. E.

2015-04-01

Selenium (Se) is an essential trace nutrient for humans. An estimated one half to one billion people worldwide suffer from Se deficiency, which is due to low concentrations and bioavailability of Se in soils where crops are grown. It has been hypothesized that more than half of the atmospheric Se deposition to soils is derived from the marine system, where microorganisms methylate and volatilize Se. Based on model results from the late 1980s, the atmospheric flux of these biogenic volatile Se compounds is around 9 Gt/year, with two thirds coming from the marine biosphere. Algae, fungi, and bacteria are known to methylate Se. Although algal Se uptake, metabolism, and methylation influence the speciation and bioavailability of Se in the oceans, these processes have not been quantified under environmentally relevant conditions and are likely to differ among organisms. Therefore, we are investigating the uptake and methylation of the two main inorganic Se species (selenate and selenite) by three globally relevant microalgae: Phaeocystis globosa, the coccolithophorid Emiliania huxleyi, and the diatom Thalassiosira oceanica. Selenium uptake and methylation were quantified in a batch experiment, where parallel gas-tight microcosms in a climate chamber were coupled to a gas-trapping system. For E. huxleyi, selenite uptake was strongly dependent on aqueous phosphate concentrations, which agrees with prior evidence that selenite uptake by phosphate transporters is a significant Se source for marine algae. Selenate uptake was much lower than selenite uptake. The most important volatile Se compounds produced were dimethyl selenide, dimethyl diselenide, and dimethyl selenyl sulfide. Production rates of volatile Se species were larger with increasing intracellular Se concentration and in the decline phase of the alga. Similar experiments are being carried out with P. globosa and T. oceanica. Our results indicate that marine algae are important for the global cycling of Se

The bibliometrics of atmospheric environment

Science.gov (United States)

Brimblecombe, Peter; Grossi, Carlota M.

Bibliometric analysis is an important tool in the management of a journal. SCOPUS output is used to assess the increase in the quantity of material in Atmospheric Environment and stylistic changes in the way authors choose words and punctuation in titles and assemble their reference lists. Citation analysis is used to consider the impact factor of the journal, but perhaps more importantly the way in which it reflects the importance authors give to papers published in Atmospheric Environment. The impact factor of Atmospheric Environment (2.549 for 2007) from the Journal Citation Reports suggests it performs well within the atmospheric sciences, but it conceals the long term value authors place on papers appearing in the journal. Reference lists show that a fifth come through citing papers more than a decade old.

Soil-vegetation-atmosphere transfer modeling

Energy Technology Data Exchange (ETDEWEB)

Ikonen, J P; Sucksdorff, Y [Finnish Environment Agency, Helsinki (Finland)

1997-12-31

In this study the soil/vegetation/atmosphere-model based on the formulation of Deardorff was refined to hour basis and applied to a field in Vihti. The effect of model parameters on model results (energy fluxes, temperatures) was also studied as well as the effect of atmospheric conditions. The estimation of atmospheric conditions on the soil-vegetation system as well as an estimation of the effect of vegetation parameters on the atmospheric climate was estimated. Areal surface fluxes, temperatures and moistures were also modelled for some river basins in southern Finland. Land-use and soil parameterisation was developed to include properties and yearly variation of all vegetation and soil types. One classification was selected to describe the hydrothermal properties of the soils. Evapotranspiration was verified against the water balance method

Soil-vegetation-atmosphere transfer modeling

Energy Technology Data Exchange (ETDEWEB)

Ikonen, J.P.; Sucksdorff, Y. [Finnish Environment Agency, Helsinki (Finland)

1996-12-31

In this study the soil/vegetation/atmosphere-model based on the formulation of Deardorff was refined to hour basis and applied to a field in Vihti. The effect of model parameters on model results (energy fluxes, temperatures) was also studied as well as the effect of atmospheric conditions. The estimation of atmospheric conditions on the soil-vegetation system as well as an estimation of the effect of vegetation parameters on the atmospheric climate was estimated. Areal surface fluxes, temperatures and moistures were also modelled for some river basins in southern Finland. Land-use and soil parameterisation was developed to include properties and yearly variation of all vegetation and soil types. One classification was selected to describe the hydrothermal properties of the soils. Evapotranspiration was verified against the water balance method

Application of PIXE analysis to atmospheric environmental studies

International Nuclear Information System (INIS)

Kasahara, Mikio

1997-01-01

Physical and chemical properties of the atmospheric aerosols is a fundamental to understand the behavior of aerosols in the atmosphere. The analysis of atmospheric aerosols is the most preferable fields of the PIXE. In this paper, the characteristics of atmospheric aerosols are reviewed at first, and the sampling method of atmospheric aerosols for the PIXE samples and the characterization of atmospheric aerosols using the PIXE analysis are discussed. (author)

A Synergistic Approach to Interpreting Planetary Atmospheres

Science.gov (United States)

Batalha, Natasha E.

We will soon have the technological capability to measure the atmospheric composition of temperate Earth-sized planets orbiting nearby stars. Interpreting these atmospheric signals poses a new challenge to planetary science. In contrast to jovian-like atmospheres, whose bulk compositions consist of hydrogen and helium, terrestrial planet atmospheres are likely comprised of high mean molecular weight secondary atmospheres, which have gone through a high degree of evolution. For example, present-day Mars has a frozen surface with a thin tenuous atmosphere, but 4 billion years ago it may have been warmed by a thick greenhouse atmosphere. Several processes contribute to a planet's atmospheric evolution: stellar evolution, geological processes, atmospheric escape, biology, etc. Each of these individual processes affects the planetary system as a whole and therefore they all must be considered in the modeling of terrestrial planets. In order to demonstrate the intricacies in modeling terrestrial planets, I use early Mars as a case study. I leverage a combination of one-dimensional climate, photochemical and energy balance models in order to create one self-consistent model that closely matches currently available climate data. One-dimensional models can address several processes: the influence of greenhouse gases on heating, the effect of the planet's geological processes (i.e. volcanoes and the carbonatesilicate cycle) on the atmosphere, the effect of rainfall on atmospheric composition and the stellar irradiance. After demonstrating the number of assumptions required to build a model, I look towards what exactly we can learn from remote observations of temperate Earths and Super Earths. However, unlike in-situ observations from our own solar system, remote sensing techniques need to be developed and understood in order to accurately characterize exo-atmospheres. I describe the models used to create synthetic transit transmission observations, which includes models of

Atmospheric Radiation Measurement Program Plan

International Nuclear Information System (INIS)

1990-02-01

In order to understand energy's role in anthropogenic global climate change, significant reliance is being placed on General Circulation Models (GCMs). A major goal of the Department is to foster the development of GCMs capable of predicting the timing and magnitude of greenhouse gas-induced global warming and the regional effects of such warming. DOE research has revealed that cloud radiative feedback is the single most important effect determining the magnitude of possible climate responses to human activity. However, cloud radiative forcing and feedbacks are not understood at the levels needed for reliable climate prediction. The Atmospheric Radiation Measurement (ARM) Program will contribute to the DOE goal by improving the treatment of cloud radiative forcing and feedbacks in GCMs. Two issues will be addressed: the radiation budget and its spectral dependence and the radiative and other properties of clouds. Understanding cloud properties and how to predict them is critical because cloud properties may very well change as climate changes. The experimental objective of the ARM Program is to characterize empirically the radiative processes in the Earth's atmosphere with improved resolution and accuracy. A key to this characterization is the effective treatment of cloud formation and cloud properties in GCMs. Through this characterization of radiative properties, it will be possible to understand both the forcing and feedback effects. GCM modelers will then be able to better identify the best approaches to improved parameterizations of radiative transfer effects. This is expected to greatly improve the accuracy of long-term, GCM predictions and the efficacy of those predictions at the important regional scale, as the research community and DOE attempt to understand the effects of greenhouse gas emissions on the Earth's climate. 153 refs., 24 figs., 6 tabs

Intercomparison of oceanic and atmospheric forced and coupled mesoscale simulations. Part I: Surface fluxes

Science.gov (United States)

Josse, P.; Caniaux, G.; Giordani, H.; Planton, S.

1999-04-01

A mesoscale non-hydrostatic atmospheric model has been coupled with a mesoscale oceanic model. The case study is a four-day simulation of a strong storm event observed during the SEMAPHORE experiment over a 500 × 500 km2 domain. This domain encompasses a thermohaline front associated with the Azores current. In order to analyze the effect of mesoscale coupling, three simulations are compared: the first one with the atmospheric model forced by realistic sea surface temperature analyses; the second one with the ocean model forced by atmospheric fields, derived from weather forecast re-analyses; the third one with the models being coupled. For these three simulations the surface fluxes were computed with the same bulk parametrization. All three simulations succeed well in representing the main oceanic or atmospheric features observed during the storm. Comparison of surface fields with in situ observations reveals that the winds of the fine mesh atmospheric model are more realistic than those of the weather forecast re-analyses. The low-level winds simulated with the atmospheric model in the forced and coupled simulations are appreciably stronger than the re-analyzed winds. They also generate stronger fluxes. The coupled simulation has the strongest surface heat fluxes: the difference in the net heat budget with the oceanic forced simulation reaches on average 50 Wm-2 over the simulation period. Sea surface-temperature cooling is too weak in both simulations, but is improved in the coupled run and matches better the cooling observed with drifters. The spatial distributions of sea surface-temperature cooling and surface fluxes are strongly inhomogeneous over the simulation domain. The amplitude of the flux variation is maximum in the coupled run. Moreover the weak correlation between the cooling and heat flux patterns indicates that the surface fluxes are not responsible for the whole cooling and suggests that the response of the ocean mixed layer to the atmosphere is

INERT Atmosphere confinement operability test procedure

International Nuclear Information System (INIS)

RISENMAY, H.R.

1999-01-01

This Operability Test Procedure (OTP) provides instructions for testing operability of the Inert Atmosphere Confinement (IAC). The Inert Atmosphere Confinement was designed and built for opening cans of metal items that might have hydrided surfaces. Unreviewed Safety Question (USQ) PFP-97-005 addresses the discovery of suspected plutonium hydride forming on plutonium metal currently stored in the Plutonium Finishing Plant vaults. Plutonium hydride reacts quickly with air, liberating energy. The Inert Atmosphere Confinement was designed to prevent this sudden liberation of energy by opening the material in an inert argon atmosphere instead of the normal glovebox atmosphere. The IAC is located in glovebox HC-21A, room 230B of the 234-5Z Building at the Plutonium Finishing Plant (PFP) in the 200-West Area of the Hanford Site

Archiving Derived Data with the PDS Atmospheres Node: The Educational Labeling System for Atmospheres (ELSA)

Science.gov (United States)

Neakrase, L. D. V.; Hornung, D.; Chanover, N.; Huber, L.; Beebe, R.; Johnson, J.; Sweebe, K.; Stevenson, Z.

2017-06-01

The PDS Atmospheres Node is developing an online tool, the Educational Labeling System for Atmospheres (ELSA), to aid in planning and creation of PDS4 bundles and associated labels for archiving derived data.

Atmospheres of the terrestrial planets

International Nuclear Information System (INIS)

Kivelson, M.G.; Schubert, G.

1986-01-01

Properties of the planets are identified - such as size, spin rate, and distance from the sun - that are important in understanding the characteristics of their atmospheres. Venus, earth and Mars have surface-temperature differences only partly explained by the decrease of solar radiation flux with distance from the sun. More significant effects arise from the variations in the degree to which the atmospheres act as absorbers of planetary thermal reradiation. Atmospheric circulation on a global scale also varies markedly among the three planets. 5 references

Global atmospheric changes.

Science.gov (United States)

Piver, W T

1991-12-01

Increasing concentrations of CO2 and other greenhouse gases in the atmosphere can be directly related to global warming. In terms of human health, because a major cause of increasing atmospheric concentrations of CO2 is the increased combustion of fossil fuels, global warming also may result in increases in air pollutants, acid deposition, and exposure to ultraviolet (UV) radiation. To understand better the impacts of global warming phenomena on human health, this review emphasizes the processes that are responsible for the greenhouse effect, air pollution, acid deposition, and increased exposure to UV radiation.

Atmosphere beyond Poetics

DEFF Research Database (Denmark)

Wieczorek, Izabela

2014-01-01

Defined by German philosopher Gernot Böhme as a ‘fundamental concept of a new aesthetics’ (Böhme 2003), the notion of atmosphere has been widely discussed across many disciplinary fields over the last few decades. It has taken a central stage also in architectural debate, leading to both conceptual......, the notion of atmosphere is presented as parallactic for designing experience in architectural fields, since it transgresses formal and material boundaries of bodies, opening a new gap that exposes the orthodox space-body-environment relationships to questions. It leads to the dissolution...

Marine atmospheric corrosion of carbon steels

Energy Technology Data Exchange (ETDEWEB)

Morcillo, M.; Alcantara, J.; Diaz, I.; Chico, B.; Simancas, J.; Fuente, D. de la

2015-07-01

Basic research on marine atmospheric corrosion of carbon steels is a relatively young scientific field and there continue to be great gaps in this area of knowledge. The presence of akaganeite in the corrosion products that form on steel when it is exposed to marine atmospheres leads to a notable increase in the corrosion rate. This work addresses the following issues: (a) environmental conditions necessary for akaganeite formation; (b) characterisation of akaganeite in the corrosion products formed; (c) corrosion mechanisms of carbon steel in marine atmospheres; (d) exfoliation of rust layers formed in highly aggressive marine atmospheres; (e) long-term corrosion rate prediction; and (f) behaviour of weathering steels. Field research has been carried out at Cabo Vilano wind farm (Camarinas, Galicia) in a wide range of atmospheric salinities and laboratory work involving the use of conventional atmospheric corrosion techniques and near-surface and bulk sensitive analytical techniques: scanning electron microscopy (SEM)/energy dispersive spectrometry (EDS), X-ray diffraction (XRD), Mossbauer spectroscopy and SEM/μRaman spectroscopy. (Author)

Do atmospheric aerosols form glasses?

Directory of Open Access Journals (Sweden)

D. A. Pedernera

2008-09-01

Full Text Available A new process is presented by which water soluble organics might influence ice nucleation, ice growth, chemical reactions and water uptake of aerosols in the upper troposphere: the formation of glassy aerosol particles. Glasses are disordered amorphous (non-crystalline solids that form when a liquid is cooled without crystallization until the viscosity increases exponentially and molecular diffusion practically ceases. The glass transition temperatures, T_g, homogeneous ice nucleation temperatures, T_hom, and ice melting temperatures, T_m, of various aqueous inorganic, organic and multi-component solutions are investigated with a differential scanning calorimeter. The investigated solutes are: various polyols, glucose, raffinose, levoglucosan, an aromatic compound, sulfuric acid, ammonium bisulfate and mixtures of dicarboxylic acids (M5, of dicarboxylic acids and ammonium sulfate (M5AS, of two polyols, of glucose and ammonium nitrate, and of raffinose and M5AS. The results indicate that aqueous solutions of the investigated inorganic solutes show T_g values that are too low to be of atmospheric importance. In contrast, aqueous organic and multi-component solutions readily form glasses at low but atmospherically relevant temperatures (≤230 K. To apply the laboratory data to the atmospheric situation, the measured phase transition temperatures were transformed from a concentration to a water activity scale by extrapolating water activities determined between 252 K and 313 K to lower temperatures. The obtained state diagrams reveal that the higher the molar mass of the aqueous organic or multi-component solutes, the higher T_g of their respective solutions at a given water activity. To a lesser extent, T_g also depends on the hydrophilicity of the organic solutes. Therefore, aerosol particles containing larger (≳150 g mol⁻¹ and

New frontiers of high-resolution spectroscopy: Probing the atmospheres of brown dwarfs and reflected light from exoplanets

Science.gov (United States)

Birkby, Jayne; Alonso, Roi; Brogi, Matteo; Charbonneau, David; Fortney, Jonathan; Hoyer, Sergio; Johnson, John Asher; de Kok, Remco; Lopez-Morales, Mercedes; Montet, Ben; Snellen, Ignas

2015-12-01

High-resolution spectroscopy (R>25,000) is a robust and powerful tool in the near-infrared characterization of exoplanet atmospheres. It has unambiguously revealed the presence of carbon monoxide and water in several hot Jupiters, measured the rotation rate of beta Pic b, and suggested the presence of fast day-to-night winds in one atmosphere. The method is applicable to transiting, non-transiting, and directly-imaged planets. It works by resolving broad molecular bands in the planetary spectrum into a dense, unique forest of individual lines and tracing them directly by their Doppler shift, while the star and tellurics remain essentially stationary. I will focus on two ongoing efforts to expand this technique. First, I will present new results on 51 Peg b revealing its infrared atmospheric compositional properties, then I will discuss an ongoing optical HARPS-N/TNG campaign (due mid October 2015) to obtain a detailed albedo spectrum of 51 Peg b at 387-691 nm in bins of 50nm. This spectrum would provide strong constraints on the previously claimed high albedo and potentially cloudy nature of this planet. Second, I will discuss preliminary results from Keck/NIRSPAO observations (due late September 2015) of LHS 6343 C, a 1000 K transiting brown dwarf with an M-dwarf host star. The high-resolution method converts this system into an eclipsing, double-lined spectroscopic binary, thus allowing dynamical mass and radius estimates of the components, free from astrophysical assumptions. Alongside probing the atmospheric composition of the brown dwarf, these data would provide the first model-independent study of the bulk properties of an old brown dwarf, with masses accurate to <5%, placing a crucial constraint on brown dwarf evolution models.

Atmospheric Chemistry Over Southern Africa

Science.gov (United States)

Gatebe, Charles K.; Levy, Robert C.; Thompson, Anne M.

2011-01-01

During the southern African dry season, regional haze from mixed industrial pollution, biomass burning aerosol and gases from domestic and grassland fires, and biogenic sources from plants and soils is worsened by a semi-permanent atmosphere gyre over the subcontinent. These factors were a driver of several major international field campaigns in the 1990s and early 2000s, and attracted many scientists to the region. Some researchers were interested in understanding fundamental processes governing chemistry of the atmosphere and interaction with climate change. Others found favorable conditions for evaluating satellite-derived measurements of atmospheric properties and a changing land surface. With that background in mind a workshop on atmospheric chemistry was held in South Africa. Sponsored by the International Commission for Atmospheric Chemistry and Global Pollution (ICACGP; http://www.icacgp.org/), the workshop received generous support from the South African power utility, Eskom, and the Climatology Research Group of the University of the Witwatersrand, Johannesburg, South Africa. The purpose of the workshop was to review some earlier findings as well as more recent findings on southern African climate vulnerability, chemical changes due to urbanization, land-use modification, and how these factors interact. Originally proposed by John Burrows, president of ICACGP, the workshop was the first ICACGP regional workshop to study the interaction of air pollution with global chemical and climate change. Organized locally by the University of the Witwatersrand, the workshop attracted more than 60 delegates from South Africa, Mozambique, Botswana, Zimbabwe, France, Germany, Canada, and the United States. More than 30 presentations were given, exploring both retrospective and prospective aspects of the science. In several talks, attention was focused on southern African chemistry, atmospheric pollution monitoring, and climate processes as they were studied in the field

Thermal Conductivity of the Multicomponent Neutral Atmosphere

Science.gov (United States)

Pavlov, A. V.

2017-12-01

Approximate expressions for the thermal conductivity coefficient of the multicomponent neutral atmosphere consisting of N2, O2, O, He, and H are analyzed and evaluated for the atmospheric conditions by comparing them with that given by the rigorous hydrodynamic theory. The new approximations of the thermal conductivity coefficients of simple gases N2, O2, O, He, and H are derived and used. It is proved that the modified Mason and Saxena approximation of the atmospheric thermal conductivity coefficient is more accurate in reproducing the atmospheric values of the rigorous hydrodynamic thermal conductivity coefficient in comparison with those that are generally accepted in atmospheric studies. This approximation of the thermal conductivity coefficient is recommended to use in calculations of the neutral temperature of the atmosphere.

Problems in global atmospheric chemistry

Science.gov (United States)

Crutzen, Paul J.

1993-02-01

The chemistry of the atmosphere is substantially influenced by a wide range of chemical processes which are primarily driven by the action of ultraviolet radiation of wavelengths shorter than 320 nm (UV-B) on ozone and water vapor. This leads to the formation of hydroxyl (OH) radicals which, despite very low tropospheric concentrations, remove most gases that are emitted into the atmosphere by natural and anthropogenic processes. Therefore, although only about 10% of all atmospheric ozone is located in the troposphere, through the formation of OH, it determines the oxidation efficiency of the atmosphere and is, therefore, of the utmost importance for maintaining its chemical composition. Due to a variety of human activities, especially through increasing emissions of CH4, CO, and NOx, the concentrations of tropospheric ozone and hydroxyl are expected to be increasing in polluted and decreasing in clean tropospheric environments. Altogether, this may be leading to an overall decrease in the oxidation efficiency of the atmosphere, contributing to a gradual buildup of several longlived trace gases that are primarily removed by reaction with OH. In the stratosphere, especially due to catalytic reactions of chlorine-containing gases of industrial origin, ozone is being depleted, most drastically noted during the early spring months over Antarctica. Because ozone is the only atmospheric constituent that can significantly absorb solar radiation in the wavelength region 240 - 320 nm, this loss of ozone enhances the penetration of biologically harmful UV-B radiation to the earth's surface with ensuing negative consequences for the biosphere. Several of the aforementioned chemically active trace gases with growing trends in the atmosphere are also efficient greenhouse gases. Together they can exert a warming effect on the earth's climate about equal to that of carbon dioxide.

Lidar mapping of atmospheric atomic mercury in the Wanshan area, China.

Science.gov (United States)

Lian, Ming; Shang, Lihai; Duan, Zheng; Li, Yiyun; Zhao, Guangyu; Zhu, Shiming; Qiu, Guangle; Meng, Bo; Sommar, Jonas; Feng, Xinbin; Svanberg, Sune

2018-05-08

A novel mobile laser radar system was used for mapping gaseous atomic mercury (Hg 0 ) atmospheric pollution in the Wanshan district, south of Tongren City, Guizhou Province, China. This area is heavily impacted by legacy mercury from now abandoned mining activities. Differential absorption lidar measurements were supplemented by localized point monitoring using a Lumex RA-915M Zeeman modulation mercury analyzer. Range-resolved concentration measurements in different directions were performed. Concentrations in the lower atmospheric layers often exceeded levels of 100 ng/m 3 for March conditions with temperature ranging from 5 °C to 20 °C. A flux measurement of Hg 0 over a vertical cross section of 0.12 km 2 resulted in about 29 g/h. Vertical lidar sounding at night revealed quickly falling Hg 0 concentrations with height. This is the first lidar mapping demonstration in a heavily mercury-polluted area in China, illustrating the lidar potential in complementing point monitors. Copyright © 2018 Elsevier Ltd. All rights reserved.

Polychlorinated biphenyls and polybrominated diphenyl ethers in the North American atmosphere

International Nuclear Information System (INIS)

Shen Li; Wania, Frank; Lei, Ying D.; Teixeira, Camilla; Muir, Derek C.G.; Xiao, Hang

2006-01-01

To assess the spatial concentration variability of polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) in the atmosphere on a large continental scale, their annually integrated air concentrations were determined in 2000/2001 using XAD-based passive air samplers (PAS). The network included 40 stations in Canada, the United States, Mexico, Belize and Costa Rica, and covered 72 degrees of latitude and longitude. Total concentrations of PCB and PBDE congeners ranged from below the detection limit to 130 ng PAS -1 and 24 ng PAS -1 , respectively. PCBs displayed a large variation between urban, rural and remote sites, whereas PBDEs did not follow such a pattern. Open burning of 'Penta'-containing waste may have contributed to the PBDEs detected in the air samples from rural and remote areas. Air from the Canadian Arctic had a relatively higher percentage of lighter PCB congeners than air sampled in the tropical region, which is interpreted as evidence for global fractionation. - A continental passive air sampling network reveals atmospheric distribution patterns of two classes of industrial chemicals

Clouds in the Martian Atmosphere

Science.gov (United States)

Määttänen, Anni; Montmessin, Franck

2018-01-01

Although resembling an extremely dry desert, planet Mars hosts clouds in its atmosphere. Every day somewhere on the planet a part of the tiny amount of water vapor held by the atmosphere can condense as ice crystals to form cirrus-type clouds. The existence of water ice clouds has been known for a long time, and they have been studied for decades, leading to the establishment of a well-known climatology and understanding of their formation and properties. Despite their thinness, they have a clear impact on the atmospheric temperatures, thus affecting the Martian climate. Another, more exotic type of clouds forms as well on Mars. The atmospheric temperatures can plunge to such frigid values that the major gaseous component of the atmosphere, CO2, condenses as ice crystals. These clouds form in the cold polar night where they also contribute to the formation of the CO2 ice polar cap, and also in the mesosphere at very high altitudes, near the edge of space, analogously to the noctilucent clouds on Earth. The mesospheric clouds are a fairly recent discovery and have put our understanding of the Martian atmosphere to a test. On Mars, cloud crystals form on ice nuclei, mostly provided by the omnipresent dust. Thus, the clouds link the three major climatic cycles: those of the two major volatiles, H2O and CO2; and that of dust, which is a major climatic agent itself.

A study of the middle atmospheric thermal structure over western India: Satellite data and comparisons with models

Science.gov (United States)

Sharma, Som; Kumar, Prashant; Vaishnav, Rajesh; Jethva, Chintan; Beig, G.

2017-12-01

Long term variations of the middle atmospheric thermal structure in the upper stratosphere and lower mesosphere (20-90 km) have been studied over Ahmedabad (23.1°N, 72.3°E, 55 m amsl), India using SABER (Sounding of the Atmosphere using Broadband Emission Radiometry) onboard TIMED (Thermosphere, Ionosphere, Mesosphere, Energetics and Dynamics) observations during year 2002 to year 2014. For the same period, three different atmospheric models show over-estimation of temperature (∼10 K) near the stratopause and in the upper mesosphere, and a signature of under-estimation is seen above mesopause when compared against SABER measured temperature profiles. Estimation of monthly temperature anomalies reveals a semiannual and ter-annual oscillation moving downward from the mesosphere to the stratosphere during January to December. Moreover, Lomb Scargle periodogram (LSP) and Wavelet transform techniques are employed to characterize the semi-annual, annual and quasi-biennial oscillations to diagnose the wave dynamics in the stratosphere-mesosphere system. Results suggested that semi-annual, annual and quasi-biennial oscillations are exist in stratosphere, whereas, semi-annual and annual oscillations are observed in mesosphere. In lower mesosphere, LSP analyses revealed conspicuous absence of annual oscillations in altitude range of ∼55-65 km, and semi-annual oscillations are not existing in 35-45 km. Four monthly oscillations are also reported in the altitude range of about 45-65 km. The temporal localization of oscillations using wavelet analysis shows strong annual oscillation during year 2004-2006 and 2009-2011.

Linking Atmospheric Pollution to Cryospheric Changes over the Third Pole

Science.gov (United States)

Kang, S.; Zhang, Q.; Ji, Z.; Li, Y.; Chen, J.; Zhang, G.; Li, C.; Cong, Z.; Chen, P.; Guo, J.; Huang, J.; Tripathee, L.; Rupakheti, D.; Li, X.; Zhang, Y.; Panday, A. K.; Rupakheti, M.

2016-12-01

Known as "the Third Pole" (TP), the Tibetan Plateau and surrounding mountains hold the largest aggregate of glaciers outside the pole regions. Recent monitoring and projection indicated an accelerated glacier decline and increasing glacier runoff. The long-range transport of South Asian atmospheric pollutants, including light absorbing impurities (LAIs) such as black carbon (BC) and mineral dust (MD), can absorb the solar radiation in the atmosphere and reduce albedo after being deposited onto the cryosphere, thereby promoting glacier and snow melt. A coordinated atmospheric pollution monitoring network has been launched covering the TP with emphasis on trans-Himalayan transects since 2013. TSP were collected for 24h at an interval of 3-6 days. BC/OC, polycyclic aromatic hydrocarbons (PAHs) and heavy metals were measured. Results reveal a consistent decrease in almost all analyzed parameters from south to north across the Himalayas. Geochemical signatures of carbonaceous aerosols indicate dominant sources of biomass burning and vehicle exhaust, in line with results of PAHs. Integrated analysis of satellite images and air mass trajectories suggest that the trans-boundary air pollution occurred episodically and concentrated in pre-monsoon seasons via upper air circulation, through-valley wind, and local convection. Simulation results showed that carbonaceous aerosols produced positive/negative shortwave radiative forcing in the atmosphere/ground surface. Aerosols increased surface air temperatures by 0.1-0.5° over the TP and decreased temperatures in South Asia during the monsoon season. Surface snow/ice samples were collected from benchmark glaciers to estimate the impacts of LAIs on glacier melt with model assistance. BC (37%) and MD (32%) contribute to the summer melting of Laohugou Glacier in the northern TP. MD (38%) contributed more glacier melt than BC (11%) on Zhadang Glacier in the southern TP. In the southeastern TP, BC and MD contribute to 30% of the

Atmospheric deposition of organochlorine contaminants to Galveston Bay, Texas

Science.gov (United States)

Park, June-Soo; Wade, Terry L.; Sweet, Stephen

Atmospheric monitoring of PCBs and chlorinated pesticides (e.g., HCHs, chlordanes, and DDTs) in Galveston Bay was conducted at Seabrook, Texas. Air and wet deposition samples were collected from 2 February 1995 and continued through 6 August 1996. Vapor total PCB ( tPCB) concentrations in air ranged from 0.21 to 4.78 ng m -3 with a dominance of tri-chlorinated PCBs. Dissolved tPCBs in rain ranged from 0.08 to 3.34 ng l -1, with tetra-chlorinated PCBs predominating. The predominant isomers found in air and rain were α- and γ-HCH, α- and γ-chlordanes, 4,4'-DDT, and dieldrin. The concentrations of PCBs and pesticides in the air and rain revealed no clear seasonal trend. Elevated levels of PCBs in the air occurred when temperatures were high and wind came from urban and industrialized areas (S, SW, NW, and W of the site). Concentrations of HCHs were elevated in April, May, and October, perhaps due to local and/or regional applications of γ-HCH (lindane). Other pesticides showed no notable temporal variation. When winds originated from the Gulf of Mexico (southeasterly), lower concentrations of organochlorines were detected in the air. The direct deposition rate (wet+dry) of PCBs to Galveston Bay (6.40 μg m -2 yr -1) was significantly higher than that of pesticides by a factor of 5-10. The net flux from gas exchange estimated for PCBs was from Galveston Bay water to the atmosphere (78 μg m -2 yr -1). Gas exchange of PCBs from bay water to the atmosphere was the dominant flux.

Evaluation of three atmospheric dispersion models using tracer release experiment data

International Nuclear Information System (INIS)

Daoo, V.J.; Oza, R.B.; Pandit, G.G.; Sadasivan, S.; Venkat Raj, V.

2004-01-01

Performance of three atmospheric dispersion models viz: (1) Gaussian Plume Model (GPM), (2) Equi-Distance PUFF Model (EDPUFFM) and (3) Particle Trajectory Model (PTM) is evaluated using field data collected from a tracer (SF 6 ) release experiment. The experiment was conducted within the campus of the Bhabha Atomic Research Centre (BARC), located at Trombay, Mumbai, India. The three models used are currently in operation at the BARC. The first one is a standard, well-documented empirical model while the other two models have been developed at the Bhabha Atomic Research Centre. The PTM is a numerical model while the EDPUFFM is a hybrid model combining both the numerical and analytical techniques. The procedure for evaluation is as per the recommendations of 1980 AMS (American Meteorological Society) workshop on atmospheric dispersion models performance evaluation. In addition, linear regression analysis has also been carried out. The regression analysis reveals that on an average, the EDPUFFM and the GPM predictions are higher by a factor of about 1.5 while the PTM predictions are lower by a factor of about 4. Comparison of various performance measures reveals that the performance of the EDPUFFM is marginally better than that of the GPM while the PTM performance is comparatively poor. The uncertainty factors obtained in this study, especially for higher concentration range ( > 100 ppt) are similar to those obtained in other validation study carried out elsewhere to validate the GPM predictions. However, for lower concentration range and for the conditions after the source is switched off, all the three models perform poorly in predicting the concentration. (author)

Uranus atmospheric dynamics and circulation

Science.gov (United States)

Allison, Michael; Beebe, Reta F.; Conrath, Barney J.; Hinson, David P.; Ingersoll, Andrew P.

1991-01-01

The observations, models, and theories relevant to the atmospheric dynamics and meteorology of Uranus are discussed. The available models for the large-scale heat transport and atmospheric dynamics as well as diagnostic interpretations of the Voyager data are reviewed. Some pertinent ideas and questions regarding the global circulation balance are considered, partly in comparison with other planetary atmospheres. The available data indicate atmospheric rotation at midlatitudes nearly 200 m/s faster than that of the planetary magnetic field. Analysis of the dynamical deformation of the shape and size of isobaric surfaces measured by the Voyager radio-occultation experiment suggests a subrotating equator at comparable altitudes. Infrared temperature retrievals above the cloud deck indicate a smaller equator-to-pole contrast than expected for purely radiative-convective equilibrium, but show local variations implying a latitudinally correlated decrease with altitude in the cloud-tracked wind.

Atmospheres in a Test Tube

Science.gov (United States)

Claudi, R.; Erculiani, M. S.; Giro, E.; D'Alessandro, M.; Galletta, G.

2013-09-01

The "Atmosphere in a Test Tube" project is a laboratory experiment that will be able to reproduce condition of extreme environments by means of a simulator. These conditions span from those existing inside some parts of the human body to combinations of temperatures, pressures, irradiation and atmospheric gases present on other planets. In this latter case the experiments to be performed will be useful as preliminary tests for both simulation of atmosphere of exoplanets and Solar System planets and Astrobiology experiments that should be performed by planetary landers or by instruments to be launched in the next years. In particular at INAF Astronomical Observatory of Padova Laboratory we are approaching the characterization of extrasolar planet atmospheres taking advantage by innovative laboratory experiments with a particular focus on low mass Neptunes and Super earths and low mass M dwarfs primaries.

Peranan Store Atmosphere Dalam Meningkatkan Keputusan Pembelian

Directory of Open Access Journals (Sweden)

Rennyta Yusiana

2017-04-01