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1

Controlling barium sulfate  

Microsoft Academic Search

Even though for several years success has been realized in controlling barium sulfate scale deposition in relatively shallow, low pressure oil wells--by squeezing an organic phosphonate scale inhibitor into the producing zone--barium sulfate scale depositon in deep, high pressure\\/high temperature wells usually meant an expensive workover operation. A case history of a deep (16,000 ft) well in St. Mary Parish,

Greenley

2009-01-01

2

Effect of flow structure at the onset of instability on barium sulfate precipitation in Taylor-Couette crystallizers  

NASA Astrophysics Data System (ADS)

The effect of the vortex flow by primary instability on the precipitation of barium sulfate crystals was examined in Taylor-Couette crystallizers. Experiments involving precipitation of barium sulfate under laminar flow (before the onset of instability) and vortex flow (after the onset of primary instability) at three different axial flow rates revealed that the vortex motion plays a critical role in fine-tuning crystal properties such as internal crystal structure, particle microstructure and morphology. While no clear trends in crystalline size were observed for laminar flow, all flowrates at the onset of instability resulted in smaller crystalline sizes that ranged between 40 nm and 50 nm. A decrease in the unit cell dimensions of the orthorhombic lattice structure was also observed after the onset of instability. For both laminar and vortex flow, shortening the residence time by increasing axial flow rate led to a substantial decrease in crystal size. It is also observed that the crystal size distribution (CSD) became much narrower after the emergence of vortices. Under vortex flow, an increase in axial flow resulted in even narrower crystal size distributions. Finally, the observed phenomena of smaller crystal size and narrow crystal size distribution under vortex flow are qualitatively explained by the analysis of particle trajetory.

Aljishi, Mohammad Fuad; Ruo, An-Cheng; Park, Jay Hoon; Nasser, Bader; Kim, Woo-Sik; Joo, Yong Lak

2013-06-01

3

Effects of nitrate and water on the oxygen isotopic analysis of barium sulfate precipitated from solution  

USGS Publications Warehouse

BaSO4 precipitated from mixed salt solutions by common techniques for SO isotopic analysis may contain quantities of H2O and NOthat introduce errors in O isotope measurements. Experiments with synthetic solutions indicate that ?18O values of CO produced by decomposition of precipitated BaSO4 in a carbon reactor may be either too low or too high, depending on the relative concentrations of SO and NO and the ?18O values of the H2O, NO, and SO. Typical ?18O errors are of the order of 0.5 to 1‰ in many sample types, and can be larger in samples containing atmospheric NO, which can cause similar errors in ?17O and ?17O. These errors can be reduced by (1) ion chromatographic separation of SO from NO, (2) increasing the salinity of the solutions before precipitating BaSO4 to minimize incorporation of H2O, (3) heating BaSO4 under vacuum to remove H2O, (4) preparing isotopic reference materials as aqueous samples to mimic the conditions of the samples, and (5) adjusting measured ?18O values based on amounts and isotopic compositions of coexisting H2O and NO. These procedures are demonstrated for SO isotopic reference materials, synthetic solutions with isotopically known reagents, atmospheric deposition from Shenandoah National Park, Virginia, USA, and sulfate salt deposits from the Atacama Desert, Chile, and Mojave Desert, California, USA. These results have implications for the calibration and use of O isotope data in studies of SOsources and reaction mechanisms.

Janet E Hannon;Johnkarl F Bohlke;Stanley J Mroczkowski

2008-01-01

4

Effects of nitrate and water on the oxygen isotopic analysis of barium sulfate precipitated from water samples  

USGS Publications Warehouse

BaSO4 precipitated from mixed salt solutions by common techniques for SO42- isotopic analysis may contain quantities of H2O and NO3- that introduce errors in O isotope measurements. Experiments with synthetic solutions indicate that ??18O values of CO produced by decomposition of precipitated BaSO4 in a carbon reactor may be either too low or too high, depending on the relative concentrations of SO42- and NO3- and the ??18O values of the H2O, NO3-, and SO42-. Typical ??18O errors are of the order of 0.5 to 1??? in many sample types, and can be larger in samples containing atmospheric NO 3-, which can cause similar errors in ?? 17O and ??17O. These errors can be reduced by (1) ion chromatographic separation of SO42- from NO 3-, (2) increasing the salinity of the solutions before precipitating BaSO4 to minimize incorporation of H2O, (3) heating BaSO4 under vacuum to remove H2O, (4) preparing isotopic reference materials as aqueous samples to mimic the conditions of the samples, and (5) adjusting measured ??18O values based on amounts and isotopic compositions of coexisting H2O and NO 3-. These procedures are demonstrated for SO 42- isotopic reference materials, synthetic solutions with isotopically known reagents, atmospheric deposition from Shenandoah National Park, Virginia, USA, and sulfate salt deposits from the Atacama Desert, Chile, and Mojave Desert, California, USA. These results have implications for the calibration and use of O isotope data in studies of SO42- sources and reaction mechanisms.

Hannon, J. E.; Bohlke, J. K.; Mroczkowski, S. J.

2008-01-01

5

Synthesis and surface properties of submicron barium sulfate particles  

NASA Astrophysics Data System (ADS)

Barium sulfate particles were synthesized in the presence of EDTA at room temperature. X-ray diffractometry (XRD), Fourier transform infrared resonance (FTIR) and scanning electron microscopy (SEM) were used to characterize the structure and morphology of BaSO 4 particles. The effect of the preparation parameters on the particle size distribution and morphology was investigated. The conditional formation constants of Ba-EDTA at different pH values were calculated. The results show that the size and morphology of BaSO 4 particles can be effectively controlled by adding EDTA in the precipitation process. Among all the operation conditions, the pH value has significant effect on the particle size. The obtained barium sulfate particles are spherical and well dispersed at pH = 9-10. Zeta potentials of BaSO 4 were measured at different pH. The isoelectric point (IEP) of barium sulfate colloid appears at pH 6.92. The model of the solid-solution interface at a particle of BaSO 4 was presented. The FTIR result indicates that the surface of the prepared BaSO 4 absorbs the functional groups of EDTA, which lower the IEP of the barium sulfate particles.

Zhang, Ming; Zhang, Bao; Li, Xinhai; Yin, Zhoulan; Guo, Xueyi

2011-10-01

6

Co-precipitation of Radium with Barium and Strontium Sulfate and Its Impact on the Fate of Radium during Treatment of Produced Water from Unconventional Gas Extraction.  

PubMed

Radium occurs in flowback and produced waters from hydraulic fracturing for unconventional gas extraction along with high concentrations of barium and strontium and elevated salinity. Radium is often removed from this wastewater by co-precipitation with barium or other alkaline earth metals. The distribution equation for Ra in the precipitate is derived from the equilibrium of the lattice replacement reaction (inclusion) between the Ra(2+) ion and the carrier ions (e.g., Ba(2+) and Sr(2+)) in aqueous and solid phases and is often applied to describe the fate of radium in these systems. Although the theoretical distribution coefficient for Ra-SrSO4 (Kd = 237) is much larger than that for Ra-BaSO4 (Kd = 1.54), previous studies have focused on Ra-BaSO4 equilibrium. This study evaluates the equilibria and kinetics of co-precipitation reactions in Ra-Ba-SO4 and Ra-Sr-SO4 binary systems and the Ra-Ba-Sr-SO4 ternary system under varying ionic strength (IS) conditions that are representative of brines generated during unconventional gas extraction. Results show that radium removal generally follows the theoretical distribution law in binary systems and is enhanced in the Ra-Ba-SO4 system and restrained in the Ra-Sr-SO4 system by high IS. However, the experimental distribution coefficient (Kd') varies widely and cannot be accurately described by the distribution equation, which depends on IS, kinetics of carrier precipitation and does not account for radium removal by adsorption. Radium removal in the ternary system is controlled by the co-precipitation of Ra-Ba-SO4, which is attributed to the rapid BaSO4 nucleation rate and closer ionic radii of Ra(2+) with Ba(2+) than with Sr(2+). Carrier (i.e., barite) recycling during water treatment was shown to be effective in enhancing radium removal even after co-precipitation was completed. Calculations based on experimental results show that Ra levels in the precipitate generated in centralized waste treatment facilities far exceed regulatory limits for disposal in municipal sanitary landfills and require careful monitoring of allowed source term loading (ASTL) for technically enhanced naturally occurring materials (TENORM) in these landfills. Several alternatives for sustainable management of TENORM are discussed. PMID:24670034

Zhang, Tieyuan; Gregory, Kelvin; Hammack, Richard W; Vidic, Radisav D

2014-04-15

7

Radiation dose in mass screening for gastric cancer with high-concentration barium sulfate compared with moderate-concentration barium sulfate.  

PubMed

Recently, high-concentration barium sulfate has been developed and is used in many medical facilities. This study compared radiation dose using high-concentration and moderate-concentration barium sulfate. The dose was evaluated with an experimental method using a gastric phantom and with a clinical examination. In the former, the dose and X-ray tube load were measured on the phantom with two concentrations of barium sulfate. In the latter, the fluoroscopic dose-area product (DAP), the radiographic DAP and their sum, the total DAP, were investigated in 150 subjects (112 males, 38 females) treated with both concentrations of barium sulfate. The effective dose was calculated by the software of PCXMC in every case. The results of the experimental evaluation indicated that the effective dose and X-ray tube load were greater with high-concentration barium sulfate than with moderate-concentration barium sulfate (p < 0.05). The results of the clinical evaluation indicated that the fluoroscopic DAP was greater with moderate-concentration barium sulfate than with high-concentration barium sulfate (p < 0.05), but the radiographic DAP was quite the reverse, so the total DAP and effective dose were almost same with both concentrations of barium sulfate. We conclude that high-concentration barium sulfate does not increase radiation dose in mass screening for gastric cancer. PMID:19623859

Yamamoto, K; Azuma, M; Kuroda, C; Kubo, T; Yabunaka, K; Yamazaki, H; Katsuda, T; Takeda, Y

2009-06-01

8

Precipitation of Calcium, Magnesium, Strontium and Barium in Tissues of Four Acacia Species (Leguminosae: Mimosoideae)  

PubMed Central

Precipitation of calcium in plants is common. There are abundant studies on the uptake and content of magnesium, strontium and barium, which have similar chemical properties to calcium, in comparison with those of calcium in plants, but studies on co-precipitation of these elements with calcium in plants are rare. In this study, we compared morphologies, distributional patterns, and elemental compositions of crystals in tissues of four Acacia species grown in the field as well as in the glasshouse. A comparison was also made of field-grown plants and glasshouse-grown plants, and of phyllodes of different ages for each species. Crystals of various morphologies and distributional patterns were observed in the four Acacia species studied. Magnesium, strontium and barium were precipitated together with calcium, mainly in phyllodes of the four Acacia species, and sometimes in branchlets and primary roots. These elements were most likely precipitated in forms of oxalate and sulfate in various tissues, including epidermis, mesophyll, parenchyma, sclerenchyma (fibre cells), pith, pith ray and cortex. In most cases, precipitation of calcium, magnesium, strontium and barium was biologically induced, and elements precipitated differed between soil types, plant species, and tissues within an individual plant; the precipitation was also related to tissue age. Formation of crystals containing these elements might play a role in regulating and detoxifying these elements in plants, and protecting the plants against herbivory.

He, Honghua; Bleby, Timothy M.; Veneklaas, Erik J.; Lambers, Hans; Kuo, John

2012-01-01

9

Role of Polyelectrolytes in Barium Sulphate Precipitation.  

National Technical Information Service (NTIS)

In the last decades, the use of additives in precipitation processes to improve process efficiency as well as product performance became more and more common practice. Additives alter the surface properties of the crystals which leads to changes in nuclea...

M. C. van der Leeden

1991-01-01

10

Comparison of the reflectance characteristics of polytetrafluoroethylene and barium sulfate paints  

NASA Astrophysics Data System (ADS)

Preliminary results are presented of the directional reflectance measurements taken on two tetrafluorethylene (TFE) paints formulated with silicone binders. Both paints are found to be more Lambertian than barium sulfate paint and pressed powder, although the pigment to binder ratios for barium sulfate and TFE paints are about 133 and 3.3 to 1, respectively. The TFE paints exhibit total visible reflectances above 90 percent and offer surfaces that are not significantly affected by water.

Butner, C. L.; Schutt, J. B.; Shai, M. C.

1984-04-01

11

Nanofunctionalized zirconia and barium sulfate particles as bone cement additives  

PubMed Central

Zirconia (ZrO2) and barium sulfate (BaSO4) particles were introduced into a methyl methacrylate monomer (MMA) solution with polymethyl methacrylate (PMMA) beads during polymerization to develop the following novel bone cements: bone cements with unfunctionalized ZrO2 micron particles, bone cements with unfunctionalized ZrO2 nanoparticles, bone cements with ZrO2 nanoparticles functionalized with 3-(trimethoxysilyl)propyl methacrylate (TMS), bone cements with unfunctionalized BaSO4 micron particles, bone cements with unfunctionalized BaSO4 nanoparticles, and bone cements with BaSO4 nanoparticles functionalized with TMS. Results demonstrated that in vitro osteoblast (bone-forming cell) densities were greater on bone cements containing BaSO4 ceramic particles after four hours compared to control unmodified bone cements. Osteoblast densities were also greater on bone cements containing all of the ceramic particles after 24 hours compared to unmodified bone cements, particularly those bone cements containing nanofunctionalized ceramic particles. Bone cements containing ceramic particles demonstrated significantly altered mechanical properties; specifically, under tensile loading, plain bone cements and bone cements containing unfunctionalized ceramic particles exhibited brittle failure modes whereas bone cements containing nanofunctionalized ceramic particles exhibited plastic failure modes. Finally, all bone cements containing ceramic particles possessed greater radio-opacity than unmodified bone cements. In summary, the results of this study demonstrated a positive impact on the properties of traditional bone cements for orthopedic applications with the addition of unfunctionalized and TMS functionalized ceramic nanoparticles.

Gillani, Riaz; Ercan, Batur; Qiao, Alex; Webster, Thomas J

2010-01-01

12

Nanofunctionalized zirconia and barium sulfate particles as bone cement additives.  

PubMed

Zirconia (ZrO(2)) and barium sulfate (BaSO(4)) particles were introduced into a methyl methacrylate monomer (MMA) solution with polymethyl methacrylate (PMMA) beads during polymerization to develop the following novel bone cements: bone cements with unfunctionalized ZrO(2) micron particles, bone cements with unfunctionalized ZrO(2) nanoparticles, bone cements with ZrO(2) nanoparticles functionalized with 3-(trimethoxysilyl)propyl methacrylate (TMS), bone cements with unfunctionalized BaSO(4) micron particles, bone cements with unfunctionalized BaSO(4) nanoparticles, and bone cements with BaSO(4) nanoparticles functionalized with TMS. Results demonstrated that in vitro osteoblast (bone-forming cell) densities were greater on bone cements containing BaSO(4) ceramic particles after four hours compared to control unmodified bone cements. Osteoblast densities were also greater on bone cements containing all of the ceramic particles after 24 hours compared to unmodified bone cements, particularly those bone cements containing nanofunctionalized ceramic particles. Bone cements containing ceramic particles demonstrated significantly altered mechanical properties; specifically, under tensile loading, plain bone cements and bone cements containing unfunctionalized ceramic particles exhibited brittle failure modes whereas bone cements containing nanofunctionalized ceramic particles exhibited plastic failure modes. Finally, all bone cements containing ceramic particles possessed greater radio-opacity than unmodified bone cements. In summary, the results of this study demonstrated a positive impact on the properties of traditional bone cements for orthopedic applications with the addition of unfunctionalized and TMS functionalized ceramic nanoparticles. PMID:20161983

Gillani, Riaz; Ercan, Batur; Qiao, Alex; Webster, Thomas J

2010-01-01

13

Development and Demonstration of a Sulfate Precipitation Process for Hanford Waste Tank 241-AN-107  

SciTech Connect

A series of precipitation experiments were conducted on Hanford waste tank 241-AN-107 samples in an effort to remove sulfate from the matrix. Calcium nitrate was added directly to AN-107 sub-samples to yield several combinations of Ca:CO{sub 3} mole ratios spanning a range of 0:1 to 3:1 to remove carbonate as insoluble CaCO{sub 3}. Similarly barium nitrate was added directly to the AN-107 aliquots, or to the calcium pretreated AN-107 aliquots, giving of Ba:SO{sub 4} mole ratios spanning a range of 1:1 to 5:1 to precipitate sulfate as BaSO{sub 4}. Initial bulk carbonate removal was required for successful follow-on barium sulfate precipitation. A {ge} 1:1 mole ratio of Ca:CO{sub 3} was found to lower the carbonate concentration such that Ba would react preferentially with the sulfate. A follow-on 1:1 mole ratio of Ba:SO{sub 4} resulted in 70% sulfate removal. The experiment was scaled up with a 735-mL aliquot of AN-107 for more complete testing. Calcium carbonate and barium sulfate settling rates were determined and fates of selected cations, anions, and radionuclides were followed through the various process steps. Seventy percent of the sulfate was removed in the scale-up test while recovering 63% of the filtrate volume. Surprisingly, during the scale-up test a sub-sample of the CaCO{sub 3}/241-AN-107 slurry was found to lose fluidity upon standing for {le} 2 days. Metathesis with BaCO{sub 3} at ambient temperature was also evaluated using batch contacts at various BaCO{sub 3}:SO{sub 4} mole ratios with no measurable success.

SK Fiskum; DE Kurath; BM Rapko

2000-08-16

14

Understanding barite and gypsum precipitation in upland acid-sulfate soils: An example from a Lufkin Series toposequence, south-central Texas, USA  

NASA Astrophysics Data System (ADS)

Although low-temperature barite precipitation has been previously documented in soils and paleosols, pedogenic barite precipitation remains poorly understood. This study characterizes the micromorphology, elemental trends, and stable isotope geochemistry of sulfates in a barite-bearing soil (Lufkin Series) toposequence using optical microscopy, XRD, ICP-MS, and stable S and O isotope data. Synthesized data indicate that fluctuating redox processes and microbial activity resulting from epiaquatic and evaporative conditions lead to the precipitation of sulfates in the Lufkin soils. Stable sulfur and oxygen isotopes indicate that the primary source of sulfur is the partial dissolution of jarosite during microbial sulfate reduction. Barium-rich parent material provides adequate barium for barite precipitation. Barium is mobilized and concentrated in Btg horizons ~ 100-160 cm below the surface. The presence of humic acids in profiles lower on the landscape prevents barite precipitation and drives the precipitation of gypsum between saturated, anoxic conditions (November to May) and drier, more oxic conditions (May to November). Barite precipitation is a slow, punctuated process. Micromorphological data reveal that barite precipitates first along evacuated macropores and then in the adjacent matrix. In general, optimal conditions for pedogenic barite precipitation in upland wetland acid-sulfate soils are: 1) warm soil temperature that supports active sulfur-reducing and sulfur oxidizing microbes; 2) distinct wet/dry seasons that allow alternating redox conditions; 3) low-gradient landscape; 4) parent material that contains barium- and sulfur-rich constituents; and 5) a long-lived, stable landscape.

Jennings, Debra S.; Driese, Steven G.

2014-01-01

15

Barium sulphate precipitation in a pipe — an experimental study and CFD modelling  

Microsoft Academic Search

Precipitation of barium sulphate in an unpremixed feed two-dimensional tubular precipitator is studied experimentally and interpreted theoretically using a closure procedure proposed previously by the authors. The closure employs the presumed beta PDF of the inert type composition variables formed with the local values of Ba2+ and SO42? concentrations and the turbulent mixer model. The flow field is computed using

Jerzy Ba?dyga; Wojciech Orciuch

2001-01-01

16

Oilfield scales: controls on precipitation and crystal morphology of barite (barium sulphate)  

Microsoft Academic Search

The precipitation and subsequent build up of barite (barium sulphate) inside extraction tubing presents a costly problem for off shore oil wells which use seawater to mobilize oil during hydrocarbon recovery. Mixing of reservoir formation water containing Ba2+ ions and seawater containing SO_42- ions results in barite precipitation within the reservoir well-bore region and piping. Great effort has been expended

A. I. R. Stark; R. A. Wogelius; D. J. Vaughan

2003-01-01

17

Micro-Computed Tomography of Fatigue Microdamage in Cortical Bone Using a Barium Sulfate Contrast Agent  

PubMed Central

Accumulation of microdamage during fatigue can lead to increased fracture susceptibility in bone. Current techniques for imaging microdamage in bone are inherently destructive and two-dimensional. Therefore, the objective of this study was to image the accumulation of fatigue microdamage in cortical bone using micro-computed tomography (micro-CT) with a barium sulfate (BaSO4) contrast agent. Two symmetric notches were machined on the tensile surface of bovine cortical bone beams in order to generate damage ahead of the stress concentrations during four-point bending fatigue. Specimens were loaded to a specified number of cycles or until one notch fractured, such that the other notch exhibited the accumulation of microdamage prior to fracture. Microdamage ahead of the notch was stained in vitro by precipitation of BaSO4 and imaged using micro-CT. Reconstructed images showed a distinct region of bright voxels around the notch tip or along propagating cracks due to the presence of BaSO4, which was verified by backscattered electron imaging and energy dispersive spectroscopy. The shape of the stained region ahead of the notch tip was consistent with principal strain contours calculated by finite element analysis. The relative volume of the stained region was correlated with the number of loading cycles by non-linear regression using a power-law. This study demonstrates new methods for the non-destructive and three-dimensional detection of fatigue microdamage accumulation in cortical bone in vitro, which may be useful to gain further understanding into the role of microdamage in bone fragility.

Leng, Huijie; Wang, Xiang; Ross, Ryan D.; Niebur, Glen L.; Roeder, Ryan K.

2008-01-01

18

Precipitation of Barite by Myxococcus xanthus: Possible Implications for the Biogeochemical Cycle of Barium  

PubMed Central

Bacterial precipitation of barite (BaSO4) under laboratory conditions is reported for the first time. The bacterium Myxococcus xanthus was cultivated in a solid medium with a diluted solution of barium chloride. Crystallization occurred as a result of the presence of live bacteria and the bacterial metabolic activity. A phosphorous-rich amorphous phase preceded the more crystalline barite formation. These experiments may indicate the involvement of bacteria in the barium biogeochemical cycle, which is closely related to the carbon cycle.

Gonzalez-Munoz, Maria Teresa; Fernandez-Luque, Belen; Martinez-Ruiz, Francisca; Ben Chekroun, Kaoutar; Arias, Jose Maria; Rodriguez-Gallego, Manuel; Martinez-Canamero, Magdalena; de Linares, Concepcion; Paytan, Adina

2003-01-01

19

The effect of calcium ions on the precipitation of barium sulphate 1: calcium ions in the absence of organic additives  

Microsoft Academic Search

The effect of calcium cations on the precipitation of barium sulphate is comprehensively studied using several techniques for the first time. The dominant mechanism at <0.00025M calcium ions is an ionic strength effect. Above this concentration, tests conducted at the same ionic strength show that differences in the behaviour of barium sulphate precipitation occur depending on the cation present (sodium

F. Jones; A Oliviera; G. M Parkinson; A. L Rohl; T Upson

2004-01-01

20

Precipitation of iron, silica, and sulfate on bacterial cell surfaces  

Microsoft Academic Search

The present study documents the precipitation of Fe(III), silica, and sulfate in the presence of 3 different bacteria (Bacillus subtilus, Bacillus licheniformis, and Pseudomonas aeruginosa), under different total Fe(III) concentrations (10 M, 10 M, 10 M) at constant pH (4.0). Morphology and chemical composition of the precipitates were compared with those formed in abiotic control systems, while chemical composition and

D. Fortin; F. G. Ferris

1998-01-01

21

Reactions of calcium orthosilicate and barium zirconate with oxides and sulfates of various elements  

NASA Technical Reports Server (NTRS)

Calcium orthosilicate and barium zirconate were evaluated as the insulation layer of thermal barrier coatings for air cooled gas turbine components. Their reactions with various oxides and sulfates were studied at 1100 C and 1300 C for times ranging up to 400 and 200 hours, respectively. These oxides and sulfates represent potential impurities or additives in gas turbine fuels and in turbine combustion air, as well as elements of potential bond coat alloys. The phase compositions of the reaction products were determined by X-ray diffraction analysis. BaZrO3 and 2CaO-SiO2 both reacted with P2O5, V2O5, Cr2O3, Al2O3, and SiO2. In addition, 2CaO-SiO2 reacted with Na2O, BaO, MgO, and CoO and BaZrO3 reacted with Fe2O3.

Zaplatynsky, I.

1979-01-01

22

Precipitation of Barite by Myxococcus xanthus: Possible Implications for the Biogeochemical Cycle of Barium  

Microsoft Academic Search

Bacterial precipitation of barite (BaSO4) under laboratory conditions is reported for the first time. The bacterium Myxococcus xanthus was cultivated in a solid medium with a diluted solution of barium chloride. Crystallization occurred as a result of the presence of live bacteria and the bacterial metabolic activity. A phosphorous-rich amorphous phase preceded the more crystalline barite formation. These experiments may

Maria Teresa Gonzalez-Munoz; Belen Fernandez-Luque; F. Martinez-Ruiz; Kaoutar Ben Chekroun; JoseMaría Arias; M. Rodriguez-Gallego; M. Martinez-Canamero; Concepcion de Linares; Adina Paytan

2003-01-01

23

Quantitative Analysis of Sulfate in Water by Indirect EDTA Titration  

ERIC Educational Resources Information Center

The determination of sulfate concentration in water by indirect EDTA titration is an instructive experiment that is easily implemented in an analytical chemistry laboratory course. A water sample is treated with excess barium chloride to precipitate sulfate ions as BaSO[subscript 4](s). The unprecipitated barium ions are then titrated with EDTA.…

Belle-Oudry, Deirdre

2008-01-01

24

59 FR- Barium Sulfate; Toxic Chemical Release Reporting; Community Right-To-Know  

Federal Register 2010, 2011, 2012, 2013

...members of the section 313 metal compound categories...toxicity, neurotoxicity, gene mutations, or chronic toxicity...barium is not a heavy metal (page 32626, column...barium is not a heavy metal, and it is not...

1994-06-28

25

Effect of Interfacial Structure on Crystallization Behavior of Polypropylene\\/Polyolefin Elastomer\\/Barium Sulfate Ternary Composites  

Microsoft Academic Search

In this paper, interfacial structure induced development of crystallization behavior of polypropylene (PP)\\/polyolefin elastomer (POE)\\/barium sulfate (BaSO4) ternary composites was studied by DSC. Two kinds of PP (copolymer and homopolymer) were used. The compatibility between PP and POE had a distinct influence on nucleation and crystal growth of PP in PP\\/POE binary composites. The crystallization rate of PP homopolymer increased

Hong Wu; Xiaolan Sun; Zhen Li; Shaoyun Guo

2007-01-01

26

Sulfate-reducing bacteria release barium and radium from naturally occurring radioactive material in oil-field barite  

USGS Publications Warehouse

Scale and sludge deposits formed during oil production can contain elevated levels of Ra, often coprecipitated with barium sulfate (barite). The potential for sulfate-reducing bacteria to release 226 Ra and Ba (a Ra analog) from oil-field barite was evaluated. The concentration of dissolved Ba increased when samples containing pipe scale, tank sludge, or oil-field brine pond sediment were incubated with sulfate-reducing bacteria Desulfovibrio sp., Str LZKI, isolated from an oil-field brine pond. However, Ba release was not stoichiometric with sulfide production in oil-field samples, and <0.1% of the Ba was released. Potential for the release of 226Ra was demonstrated, and the 226 Ra release associated with sulfate-reducing activity was predictable from the amount of Ba released. As with Ba, only a fraction of the 226Ra expected from the amount of sulfide produced was released, and most of the Ra remained associated with the solid material.

Phillips, E. J. P.; Landa, E. R.; Kraemer, T.; Zielinski, R.

2001-01-01

27

Comparison of Gastrografin to barium sulfate as a gastrointestinal contrast agent in red-eared slider turtles (Trachemys scripta elegans).  

PubMed

Red-eared slider turtles (Trachemys scripta elegans) commonly develop intestinal obstruction. The gastrointestinal transit time in turtles tends to be longer than in other animals, making a rapid diagnosis of obstruction difficult. Fifteen red-eared sliders were given either Gastrografin or 30% w/v barium sulfate orally to compare ease of administration, transit time, and image quality. Each contrast medium was easy to administer but barium sulfate had to be administered more slowly (mean = 40s) than Gastrografin (mean = 20s) to prevent regurgitation. The mean transit and emptying time of Gastrografin was at least 9 h faster than barium sulfate at all time points except gastric transit. Both contrast media had a smooth, uniform appearance that outlined the mucosa with well-defined margins within the stomach and proximal small intestine. Dilution of Gastrografin occurred as it progressed through the intestines, resulting in decreased opacity in the distal small intestine and colon. Pre-administration packed cell volume and total serum protein levels of four turtles receiving Gastrografin were compared with levels at 24-, 96-, and 168-hours postadministration as well as to four control turtles not receiving contrast medium. Packed cell volume and total serum protein levels did not significantly differ among the Gastrografin and control group. From a clinical perspective, administration of Gastrografin allows for quicker results with only minor hematologic changes in red-eared sliders, but visualization of this contrast medium in the lower gastrointestinal tract may be insufficient for an accurate diagnosis. PMID:20166392

Long, Charles Tyler; Page, Richard B; Howard, Antwain M; McKeon, Gabriel P; Felt, Stephen A

2010-01-01

28

Precipitation of barium flouride microcrystals from electrolytic solutions: The influence of the composition of the precipitating solutions  

NASA Astrophysics Data System (ADS)

The composition, shape and size of the particles obtained by precipitation in aqueous solutions of various barium salts (chloride, nitrate and acetate) with various fluorides (ammonium, sodium and hydrogen) have been studied by X-ray powder diffraction analysis and scanning electron microscopy. From Ba(NO 3) 2 in combination with NH 4F or NaF and from Ba(C 2H 3O 2) 2 in combination with NH 4F, NaF or HF, precipitates of pure cubic-BaF 2 (?-BaF 2) are obtained. The shape and size of ?-BaF 2 particles depend on the combination of the compounds used for the precipitation and their concentrations. It appears that only when (equal volumes of) solutions of Ba(NO 3) 2 (0.125 mol dm -3) or Ba(C 2H 3O 2) 2 (0.125 and 0.150 mol dm -3) and NH 4F (0.250 or 0.300 mol dm -3) are mixed particles are formed as more or less regular cubes with smooth faces. These crystals are suitable to be used in studies of the transport of ions from crystals to the solution and vice versa with the aid of radioactive tracers ("heterogeneous isotopic exchange" studies).

Kolar, Z.; Binsma, J. J. M.; Suboti?, B.

1984-02-01

29

Low temperature catalytic conversion of methane to methanol by barium sulfate nanotubes supporting sulfates: Pt(SO4)2, HgSO4, Ce(SO4)2 and Pb(SO4)2.  

PubMed

Barium sulfate nanotubes perform excellently in supporting sulfates (Pt(SO4)2, HgSO4, Ce(SO4)2 and Pb(SO4)2) for low temperature catalytic conversion of methane to methanol under strongly acidic conditions in a conventional gas-phase reactor. PMID:15856108

Li, Fengbo; Yuan, Guoqing

2005-05-01

30

The nucleation kinetics of barium sulfate in NaCl solutions up to 6 m and 90 C  

SciTech Connect

The formation of barite crystals is both desirable for quantitative analysis of barium or sulfate concentrations and undesirable as scale deposits in wells and associated facilities during geothermal drilling, gas and oil production, and brine disposal. Induction periods for the nucleation of barium sulfate were experimentally determined as a function of supersaturation in NaCl solutions from 0 to 6 m at 25 C and in 1.0 m NaCl solutions at temperatures from 25 to 90 C. Employing the classical nucleation theory, the interfacial tension between barite and supersaturated solutions with NaCl was estimated to be about 93 mJ/m{sup 2} (less than 0.003 m NaCl) and 79 mJ/m{sup 2} (1 m NaCl) at 25 C. It decreases slightly with increasing temperature (to 71 mJ/m{sup 2} in 1 m NaCl solutions at 90 C). It was observed that the induction period decreases with increasing NaCl concentrations to 3 mm and then starts to increase slightly at a given temperature and saturation index. The electrolyte effect on nucleation was proportional to the enhanced solubility of barium sulfate in NaCl solutions. This phenomenon may result from decreased crystal-solution interfacial tensions caused by increased barite solubility in electrolyte solutions. The increase in induction period at high NaCl concentrations may be due to the substitution of Na{sup +} ions into the lattice of BaSO{sub 4}.

He, S.; Oddo, J.E.; Tomson, M.B. [Rice Univ., Houston, TX (United States). Dept. of Environmental Science and Engineering] [Rice Univ., Houston, TX (United States). Dept. of Environmental Science and Engineering

1995-09-15

31

BARIUM BIOAVAILABILITY AS THE CHLORIDE, SULFATE, OR CARBONATE SALT IN THE RAT  

EPA Science Inventory

This study was conducted to determine how the bioavailability of a low concentration of barium (Ba) in drinking water is affected by anion speciation. Male Sprague Dawley rats weighing 250-300 grams were maintained on a diet of less than 1 mg Ba/kg of food for at least 1 month pr...

32

Barium borosilicate glass a potential matrix for immobilization of sulfate bearing high-level radioactive liquid waste  

NASA Astrophysics Data System (ADS)

Borosilicate glass formulations adopted worldwide for immobilization of high-level radioactive liquid waste (HLW) is not suitable for sulphate bearing HLW, because of its low solubility in such glass. A suitable glass matrix based on barium borosilicate has been developed for immobilization of sulphate bearing HLW. Various compositions based on different glass formulations were made to examine compatibility with waste oxide with around 10 wt% sulfate content. The vitrified waste product obtained from barium borosilicate glass matrix was extensively evaluated for its characteristic properties like homogeneity, chemical durability, glass transition temperature, thermal conductivity, impact strength, etc. using appropriate techniques. Process parameters like melt viscosity and pour temperature were also determined. It is found that SB-44 glass composition (SiO 2: 30.5 wt%, B 2O 3: 20.0 wt%, Na 2O: 9.5 wt% and BaO: 19.0 wt%) can be safely loaded with 21 wt% waste oxide without any phase separation. The other product qualities of SB-44 waste glass are also found to be on a par with internationally adopted waste glass matrices. This formulation has been successfully implemented in plant scale.

Kaushik, C. P.; Mishra, R. K.; Sengupta, P.; Kumar, Amar; Das, D.; Kale, G. B.; Raj, Kanwar

2006-11-01

33

Study of the Dissolution of the Barium Sulfate (001) Surface with Hydrochloric Acid by Atomic Force Microscopy.  

PubMed

Noncontact atomic force microscopy (NC-AFM) has been used to investigate the morphological changes of a freshly cleaved (001) surface of barium sulfate (barite) etched with an aqueous solution of 0.1 M HCl at room temperature. Shallow triangular etch pits with a height of 3.6 Å were developed in atomically flat (001) terraces. The etching of the surface was found to proceed in a layer-by-layer dissolution process. Because the crystal structure of barite exhibits a two-fold screw axis parallel to the c axis, "alternating" etch pits were formed, with any two consecutive etch pits pointing opposite to each other. These etch pits became deeper and more elongated along the b axis with time. Copyright 1999 Academic Press. PMID:10527591

Wang; Resch; Koel; Shuler; Tang; Chen; Yen

1999-11-01

34

Co-precipitation of yttrium and barium fluorides from aqueous solutions  

SciTech Connect

Highlights: ? BaF{sub 2}–YF{sub 3} system has been studied under the non-equilibrium ambient conditions. ? Ba{sub 1?x}Y{sub x}F{sub 2+x} (x = 0.35–0.75) solid solution phase has cubic fluorite-type structure. ? Ba{sub 1?x}Y{sub x}F{sub 2+x} cubic crystal lattice parameter a{sub 0} does not change monotonously. ? Different types of lattice defects determine a dependency from sample composition. ? (H{sub 3}O{sup +})Y{sub 3}F{sub 10}{sup ?}·nH{sub 2}O phase precipitates from HF aqueous solutions instead of YF{sub 3}·nH{sub 2}O. -- Abstract: Co-precipitation of barium and yttrium fluorides from aqueous solutions at room temperature produced non-equilibrium Ba{sub 1?x}Y{sub x}F{sub 2+x} nanofluoride phase with face-centered cubic crystal lattice of fluorite-type with the composition interval of the homogeneity for x = 0.35–0.75. Lattice parameter a of this solid solution nanophase varied as a function of the sample chemical composition in a complex manner with two areas of linear dependency, from x = 0.35 to 0.45 and from x = 0.50 to 0.75. A plausible explanation of this phenomenon included a change of the type of crystal lattice defects and the manner of their population with the corresponding ions. An increase of the relative amount of yttrium in the HF reaction system led to the formation of hydroxonium salt of decafluorotriyttrium acid, (H{sub 3}O{sup +})Y{sub 3}F{sub 10}{sup ?}·nH{sub 2}O, instead of expected YF{sub 3} hydrate. No formation of oxyfluoride phases under acidic conditions has been observed.

Fedorov, Pavel P., E-mail: ppfedorov@yandex.ru [A. M. Prokhorov General Physics Institute, Russian Academy of Sciences, 38 Vavilov Street, Moscow 119991 (Russian Federation); Mayakova, Maria N.; Kuznetsov, Sergey V.; Voronov, Valery V.; Ermakov, Roman P.; Samarina, Kseniya S.; Popov, Arthur I.; Osiko, Vyacheslav V. [A. M. Prokhorov General Physics Institute, Russian Academy of Sciences, 38 Vavilov Street, Moscow 119991 (Russian Federation)] [A. M. Prokhorov General Physics Institute, Russian Academy of Sciences, 38 Vavilov Street, Moscow 119991 (Russian Federation)

2012-07-15

35

Alumina Extraction by Autoclave Precipitation of Basic Sodium Aluminum Sulfate.  

National Technical Information Service (NTIS)

An investigation was conducted on the conditions affecting the precipitation of aluminum by autoclaving synthetic solutions containing Na2SO4, Al2(SO3)3, H2SO4, and H2O. Virtually all of the alumina could be precipitated as natroalunite (NaAl3(SO4)2(OH)6)...

H. G. Iverson H. Leitch

1968-01-01

36

Selective Precipitation and Purification of Monovalent Proteins Using Oligovalent Ligands and Ammonium Sulfate  

PubMed Central

This paper describes a method for the selective precipitation and purification of a monovalent protein (carbonic anhydrase is used as a demonstration) from cellular lysate using ammonium sulfate and oligovalent ligands. The oligovalent ligands induce the formation of protein-ligand aggregates, and at an appropriate concentration of dissolved ammonium sulfate, these complexes precipitate. The purification involves three steps: i) the removal of high-molecular weight impurities through the addition of ammonium sulfate to the crude cell lysate; ii) the introduction of an oligovalent ligand and the selective precipitation of the target protein-ligand aggregates from solution; and iii) the removal of the oligovalent ligand from the precipitate by dialysis to release the target protein. The increase of mass and volume of the proteins upon aggregate formation reduces their solubility, and results in the selective precipitation of these aggregates. We recovered human carbonic anhydrase, from crude cellular lysate, in 82% yield and 95% purity with a trivalent benzene sulfonamide ligand. This method provides a chromatography-free strategy of purifying monovalent proteins—for which appropriate oligovalent ligands can be synthesized—and combines the selectivity of affinity-based purification with the convenience of salt-induced precipitation.

Mirica, Katherine A.; Lockett, Matthew R.; Snyder, Phillip W.; Shapiro, Nathan D.; Mack, Eric T.; Nam, Sarah; Whitesides, George M.

2012-01-01

37

Sourcing Marine Sulfate: Isotope evidence for secondary sulfide precipitation in the Marsyandi River, Nepal, Himalaya  

NASA Astrophysics Data System (ADS)

The weathering of sulfur bearing minerals forms the largest source of sulfate to the ocean. The nature of the minerals being weathered, either sulfate minerals (e.g. gypsum), or sulfide minerals (e.g. oxidative weathering of pyrite) impacts the flux of sulfate to the ocean, the isotope composition of this flux, and is one of the long-term controls on atmospheric oxygen. Sulfur and oxygen isotopes in riverine sulfate are a powerful tool for tracing the sulfur minerals being weathered. This is because evaporite minerals are typically more enriched in the heavy sulfur and oxygen isotopes, while pyrite is much more enriched in the light sulfur isotope and has a range of oxygen isotopes depending on the oxidative pathway. We measured the sulfur and oxygen isotopes in sulfate in the Marsyandi River (Nepal), a Himalayan tributary to the Ganges River. Sulfur and oxygen isotopes in sulfate are isotopically light in the headwaters (-20 to -25% ?34S and -10 to -13% ?18O)), suggesting that oxidative weathering of pyrite through iron reduction is the dominant source of sulfate to the Marsyandi. However, progressing downstream the sulfur and oxygen isotope composition in sulfate both increase, reaching +11 to +15% for ?34S and +8 to +10% for ?18O), although the dominant lithology in the catchment does not change. This increase could be due to weathering of evaporites from further away or isotopic enrichment due to microbially mediated sulfate reduction. The lack of coeval changes in the calcium and chlorine concentration rule out evaporite weathering, and we conclude that the isotope shift downstream is indicative of sulfate reduction and secondary sulfide precipitation. These results have implications for the isotope composition of riverine sulfate as well as our understanding of the functioning of the deep terrestrial biosphere.

Turchyn, A. V.; Tipper, E.; Galy, A.; Bickle, M. J.; Lo, J.

2011-12-01

38

PRIMARY SULFATE EMISSION FACTORS FOR THE NAPAP (NATIONAL ACID PRECIPITATION ASSESSMENT PROGRAM) EMISSIONS INVENTORY  

EPA Science Inventory

The report gives results of an estimation of primary sulfate emission factors for use in the 1980 and 1985 National Acid Precipitation Assessment Program (NAPAP) emissions inventories. The estimates were developed from an assessment of existing measurements data for source catego...

39

Influence of storm characteristics on sulfate in precipitation  

SciTech Connect

The effects of storm dynamics on precipitation chemistry were examined using an atmospheric budget for SO/sub 4//sup =/. One hundred storms occurring between 1975 and 1978 at Hubbard Brook Experimental Forest in New Hampshire were used as test data. Concentrations of major ions were usually greater in convective storms than in continuouus or layer storms. For example the geometric mean concentrations of SO/sub 4//sup =/ in convective and continous storms were 4.1 and 1.1 mg L/sup -1/, respectively. Higher SO/sub 4//sup =/ concentrations also occurred when surface wind direction were south or southwest. The summer maximum in convective activity along with the seasonal dependence of surface wind directions and the seasonal atmospheric chemistry cycle can account for the summer maximum in SO/sub 4//sup =/ concentrations observed in the northeastern United States. 22 references, 5 figures, 4 tables.

Bloxam, R.M.; Hornbeck, J.W.; Martin, C.W.

1984-01-01

40

Metabolic Engineering of an Aerobic Sulfate Reduction Pathway and Its Application to Precipitation of Cadmium on the Cell Surface  

PubMed Central

The conversion of sulfate to an excess of free sulfide requires stringent reductive conditions. Dissimilatory sulfate reduction is used in nature by sulfate-reducing bacteria for respiration and results in the conversion of sulfate to sulfide. However, this dissimilatory sulfate reduction pathway is inhibited by oxygen and is thus limited to anaerobic environments. As an alternative, we have metabolically engineered a novel aerobic sulfate reduction pathway for the secretion of sulfides. The assimilatory sulfate reduction pathway was redirected to overproduce cysteine, and excess cysteine was converted to sulfide by cysteine desulfhydrase. As a potential application for this pathway, a bacterium was engineered with this pathway and was used to aerobically precipitate cadmium as cadmium sulfide, which was deposited on the cell surface. To maximize sulfide production and cadmium precipitation, the production of cysteine desulfhydrase was modulated to achieve an optimal balance between the production and degradation of cysteine.

Wang, Clifford L.; Maratukulam, Priya D.; Lum, Amy M.; Clark, Douglas S.; Keasling, J. D.

2000-01-01

41

Spectral investigations of Cu2+ doped beta-barium borate nanopowder by the co-precipitation method  

NASA Astrophysics Data System (ADS)

A Cu2+ doped beta-barium borate nanopowder has been synthesized using the co-precipitation method. The average crystallite size of the present system is evaluated at 68 nm and the lattice cell parameters are calculated from x-ray diffraction data. Optical absorption spectral data reveal that the Cu2+ ions are in a tetragonally distorted octahedral site in the host lattice. Direct, indirect and Urbach energies are calculated with the absorption edge technique. Electron paramagnetic resonance results confirm that the Cu2+ ions enter a tetragonally elongated octahedral site at room temperature. The crystal field and spin-Hamiltonian parameters are also evaluated. Fourier transform infrared spectroscopy confirms the vibrational bands of Ba-O and B-O in the system.

Venkata Reddy, Ch; Rama Krishna, Ch; Udayachandran Thampy, U. S.; Reddy, Y. P.; Rao, P. S.; Ravikumar, R. V. S. S. N.

2011-08-01

42

COMPARISON OF WET CHEMICAL AND INSTRUMENTAL METHODS FOR MEASURING AIRBORNE SULFATE  

EPA Science Inventory

Four techniques for determination of water soluble sulfate in atmospheric samples were compared including the barium sulfate turbidimetric method, the Brosset (barium-Thorin) method, the automated barium-methylthymol blue procedure and a microchemical (barium-dinitro-sulfanazo II...

43

Automatic Determination of Sulfates by an Improved Nephelometric Method. Application to the Determination of SO2 in the Ambient Air and of Sulfates in Rainwater (Dosage Automatique des Sulfates par un Methode Nephelometrique Amelioree. Application au Dosage du SO2 dans l'Air Ambiant et des Sulfates dans les Eaux de Pluie).  

National Technical Information Service (NTIS)

An automatic nephelometric method for the determination of low concentrations of sulfate is described. It permits the determination of concentrations as low as 0.1 micro gram/cu cm. The sulfate ions are precipitated by means of barium perchlorate. Fifty s...

G. Verduyn A. Derouane

1974-01-01

44

Nonspecific Precipitation of Serum Proteins by Sodium Lauryl Sulfate in Agar Diffusion and Immunoelectrophoresis  

PubMed Central

The anionic detergent sodium lauryl sulfate (SLS), in a final concentration of 0.1% and greater, reacted with whole serum in agar diffusion and immunoelectrophoresis to form artifactual precipitin lines. These lines occurred when either Ionagar or agarose was used as the supporting gel and were not affected by the presence of urea and 2-mercaptoethanol. Analytic chemical tests confirmed that the precipitating agent is SLS, and staining techniques showed that the detergent precipitates both protein and lipoprotein components of whole serum. Multiple artifactual precipitin lines occurred with a wide variety of animal sera, and a single line formed with human 7S immunoglobulin. Hence, in agar diffusion studies in which SLS is present in the test system, these artifactual lines may be easily misinterpreted as true antigen-antibody precipitin reactions. Images

Palmer, E. L.; Martin, M. L.; Hierholzer, J. C.; Ziegler, D. W.

1971-01-01

45

Synthesis of Nanometric-Sized Barium Titanate Powders Using Acetylacetone as the Chelating Agent in a Sol-Precipitation Process  

NASA Astrophysics Data System (ADS)

Nanometric-sized barium titanate powders were prepared by using titanium isopropoxid as the raw material and acetylacetone as a chelating agent, in a strong alkaline solution (pH > 13) through the sol-precipitation method. The preparatory variables affect the extent of cross-linking in the structure, change the mode of condensation of the gels, and even control the particle size of the powder. The reaction rate of forming powder, at a higher temperature such as 100°C and more water content (the molar ratio of water to titanium isopropoxide is 25) or fewer acetylacetone (the molar ratio of acetylacetone to titanium isopropoxide is 1), is rapid and the particle size formed is finer at 60 80 nm. On the contrary, that of forming powder, at lower temperature (40°C) and less water content (molar ratio of water/titanium isopropoxide = 5) or higher acetylacetone (acetylacetone/titanium isopropoxide = 7), is slow and the particle size of the powder is larger. The optimal preparatory conditions were obtained by using the experimental statistical method; as a result, nanometric-sized BaTiO3 powder with an average particle size of about 50 nm was prepared.

Hung, Kun Ming; Hsieh, Ching Shieh; Yang, Wein Duo; Tsai, Hui Ju

2007-03-01

46

Short-Range Dissolution-Precipitation Crystallization of Hydrothermal Barium Titanate  

SciTech Connect

A modified autoclave was used to investigate the crystallization mechanism of BaTiO3 during the hydrothermal reaction of Ba(OH)2 and TiO2 anatase. An uneven distribution of the crystallized BaTiO3 particles was observed: more than 99 wt% of total BaTiO3 articles remained where the precursor TiO2 was put; less than 1 wt% was collected from the areas away from the TiO2. According to the experimental observations in this work and proofs reported in the literature, we propose that the crystallization mechanism is dissolution-precipitation in nature, but the soluble Ti4+ species can only redisperse in a short distance away from TiO2 particles before precipitation. In another words, the nucleation of hydrothermal BaTiO3 starts at a low concentration of Ti4+. The mechanism of the Ba(OH)2-Ti(OH)4 reaction is a fast dehydration process.

Qi, Lai; Lee, Burtrand I.; Badheka, Prerak; Yoon, Dang-Hyok; Samuels, William D.; Exarhos, Gregory J.

2004-07-01

47

Influence of semi-batch operation on the precipitation of natrojarosite particles from sulfate solutions  

NASA Astrophysics Data System (ADS)

The precipitation of natrojarosite from iron sodium sulfate solutions has been investigated at temperatures close to the atmospheric boiling point, in batch and semi-batch conditions. Semi-batch conditions make it possible to maintain a weaker iron concentration in the stirred reactor, leading to lower supersaturations, closer to those in continuous and possibly seeded MSMPRs or tanks—in series units. In these reactors, primary and secondary nucleations are few, allowing the growth of pure mono-crystalline particles of controlled size and size dispersion. Both modi operandi lead to agglomerates made of crystals of cubic habit. The surface of cauliflower-like particles from the batch modus operandi displays overlaying crystals, of size between 100 and 400 nm. The particles from the semi-batch mode, with moderate iron addition, are rougher and show bigger intergrown constitutive crystals of size up to a few microns, which denotes lesser secondary nucleation and more growth. A model is developed to characterize iron(III) and sulfate speciation with non-ideal behavior in the mother solution. It is used to compare the variations of supersaturation in the reactor between the batch and the semi-batch conditions. During the first 500 min, the supersaturation resulting from a moderate addition of iron is 10,000-10 times lower than during batch kinetics, which agrees with the reduction of secondary nucleation suggested by scanning electron micrographs. The semi-batch technique, which can be combined with the addition of support particles, is worth further work, aiming to reduce secondary nucleation and to determine the crystallite growth rate expression of natrojarosite as a function of supersaturation, using the model of solution developed in this work.

Sandré, Anne-Laure; Gaunand, Alain

2012-03-01

48

In situ metal precipitation in a zinc-contaminated, aerobic sandy aquifer by means of biological sulfate reduction.  

PubMed

The applicability of in situ metal precipitation (ISMP) based on bacterial sulfate reduction (BSR) with molasses as carbon source was tested for the immobilization of a zinc plume in an aquifer with highly unsuitable initial conditions (high Eh, low pH, low organic matter content, and low sulfate concentrations), using deep wells for substrate injection. Batch experiments revealed an optimal molasses concentration range of 1-5 g/L and demonstrated the necessity of adding a specific growth medium to the groundwater. Without this growth medium, even sulfate, nitrogen, phosphorus, and potassium addition combined with pH optimization could not trigger biological sulfate reduction. In column experiments, precipitation of ZnS(s) was induced biologically as well as chemically (by adding Na2S). In both systems, zinc concentrations dropped from about 30 mg/L to below 0.02 mg/L. After termination of substrate addition the biological system showed continuation of BSR for at least 2 months, suggesting the insensitivity of the sulfate reducing system for short stagnations of nutrient supply, whereas in the chemical system an immediate increase of Zn concentrations was observed. A pilot experiment conducted in situ at the zinc-contaminated site showed a reduction of zinc concentrations from around 40 mg/L to below 0.01 mg/L. Termination of substrate supply did not result in an immediate stagnation of the BSR process, but continuation of BSR was observed for at least 5 weeks. PMID:15298212

Janssen, G M C M; Temminghoff, E J M

2004-07-15

49

Tantalum oxide and barium sulfate as radiopacifiers in injectable calcium phosphate-poly(lactic-co-glycolic acid) cements for monitoring in vivo degradation.  

PubMed

Monitoring the degradation of calcium phosphate-based bone substitute materials in vivo by means of noninvasive techniques (e.g., radiography) is often a problem due to the chemical resemblance of those substitutes with the mineral phase of bone. In the view of that, the present study aimed at enhancing the radiopacity of calcium phosphate cement enriched with poly(lactic-co-glycolic acid) (CPC-PLGA) microspheres, by adding tantalum oxide (Ta2 O5 ) or the more traditional radiopacifier barium sulfate (BaSO4 ). The radiopacifying capacity of these radiopacifiers was first evaluated in vitro by microcomputed tomography (?CT). Thereafter, both radiopacifiers were tested in vivo using a distal femoral condyle model in rabbits, with subsequent ex vivo ?CT analysis in parallel with histomorphometry. Addition of either one of the radiopacifiers proved to enhance radiopacity of CPC-PLGA in vitro. The in vivo experiment showed that both radiopacifiers did not induce alterations in biological performance compared to plain CPC-PLGA, hence both radiopacifiers can be considered safe and biocompatible. The histomorphometrical assessment of cement degradation and bone formation showed similar values for the three experimental groups. Interestingly, ?CT analysis showed that monitoring cement degradation becomes feasible upon incorporation of either type of radiopacifier, albeit that BaSO4 showed more accuracy compared to Ta2 O5 . © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2013. PMID:23613219

Hoekstra, Jan Willem M; van den Beucken, Jeroen J J P; Leeuwenburgh, Sander C G; Bronkhorst, Ewald M; Meijer, Gert J; Jansen, John A

2013-04-24

50

Biodegradation of BTEX and Other Petroleum Hydrocarbons by Enhanced and Controlled Sulfate Reduction  

SciTech Connect

High concentrations of sulfide in the groundwater at a field site near South Lovedale, OK, were inhibiting sulfate reducing bacteria (SRB) that are known to degrade contaminants including benzene, toluene, ethylbenzene, and m+p-xylenes (BTEX). Microcosms were established in the laboratory using groundwater and sediment collected from the field site and amended with various nutrient, substrate, and inhibitor treatments. All microcosms were initially amended with FeCl{sub 2} to induce FeS precipitation and, thereby, reduce sulfide concentrations. Complete removal of BTEX was observed within 39 days in treatments with various combinations of nutrient and substrate amendments. Results indicate that elevated concentration of sulfide is a limiting factor to BTEX biodegradation at this site, and that treating the groundwater with FeCl{sub 2} is an effective remedy to facilitate and enhance BTEX degradation by the indigenous SRB population. On another site in Moore, OK, studies were conducted to investigate barium in the groundwater. BTEX biodegradation by SRB is suspected to mobilize barium from its precipitants in groundwater. Data from microcosms demonstrated instantaneous precipitation of barium when sulfate was added; however, barium was detected redissolving for a short period and precipitating eventually, when active sulfate reduction was occurring and BTEX was degraded through the process. SEM elemental spectra of the evolved show that sulfur was not present, which may exclude BaSO{sub 4} and BaS as a possible precipitates. The XRD analysis suggests that barium probably ended in BaS complexing with other amorphous species. Results from this study suggest that SRB may be able to use the sulfate from barite (BaSO{sub 4}) as an electron acceptor, resulting in the release of free barium ions (Ba{sup 2+}), and re-precipitate it in BaS, which exposes more toxicity to human and ecological health.

Song Jin

2007-07-01

51

Placement of Radium/Barium Sludges in Tailings Areas.  

National Technical Information Service (NTIS)

Currently radium is removed from uranium mining and milling effluents by the addition of barium chloride to precipitate the radium as radium/barium sulphate. The precipitate is allowed to settle in sedimentation basins prior to discharge of the effluent. ...

K. L. Murphy G. E. Multamaki

1980-01-01

52

Modeling investigation of controlling factors in the increasing ratio of nitrate to non-seasalt sulfate in precipitation over Japan  

NASA Astrophysics Data System (ADS)

Anthropogenic emissions in East Asia have been increasing during the three decades since 1980, as the population of East Asia has grown and the economies in East Asian countries have expanded. This has been particularly true in China, where NOx emissions have been rising continuously. However, because of fuel-gas desulfurization systems introduced as part of China's 11th Five-Year Plan (2006-2010), SO2 emissions in China reached a peak in 2005-2006 and have declined since then. These drastic changes in emission levels of acidifying species are likely to have caused substantial changes in the precipitation chemistry. The absolute concentration of compounds in precipitation is inherently linked to precipitation amount; therefore, we use the ratio of nitrate (NO) to non-seasalt sulfate (nss-SO2-) concentration in precipitation as an index for evaluating acidification, which we call Ratio. In this study, we analyzed the long-term behavior of Ratio in precipitation over the Japanese archipelago during 2000-2011 and estimated the factors responsible for changes in Ratio in precipitation by using a model simulation. This analysis showed that Ratio was relatively constant at 0.5-0.6 between 2000 and 2005, and subsequently increased to 0.6-0.7 between 2006 and 2011. These changes in Ratio corresponded remarkably well to the changes of NOx/SO2 emissions ratio in China; this correspondence suggests that anthropogenic emissions from China were responsible for most of the change in precipitation chemistry over Japan. Sensitivity analysis elucidated that the increase in NOx emissions and the decrease in SO2 emissions contributed equally to the increases in Ratio. Considering both emission changes in China enables to capture the observed increasing trend of Ratio in Japan.

Itahashi, Syuichi; Uno, Itsushi; Hayami, Hiroshi; Fujita, Shin-ichi

2014-08-01

53

Predictive simulation of nanoparticle precipitation based on the population balance equation  

Microsoft Academic Search

Nanoparticle precipitation is an interesting process to generate particles with tailored properties. In this study we investigate the impact of various process steps such as solid formation, mixing and agglomeration on the resulting particle size distribution (PSD) as representative property using barium sulfate as exemplary material. Besides the experimental investigation, process simulations were carried out by solving the full 1D

Hans-Christoph Schwarzer; Florian Schwertfirm; Michael Manhart; Hans-Joachim Schmid; Wolfgang Peukert

2006-01-01

54

ACID PRECIPITATION: EFFECTS OF SULFUR DIOXIDE AND SULFATE AEROSOL PARTICLES ON HUMAN HEALTH  

EPA Science Inventory

While human health impairment has been attributed to pollution by sulfur dioxide (SO2), data from inhalation studies in animals show that its oxidation products are more irritating. Population surveys in which suspended sulfate was a co-variant suggest that certain health paramet...

55

Acid Precipitation: Effects of Sulfur Dioxide and Sulfate Aerosol Particles on Human Health.  

National Technical Information Service (NTIS)

While human health impairment has been attributed to pollution by sulfur dioxide (SO2), data from inhalation studies in animals show that its oxidation products are more irritating. Population surveys in which suspended sulfate was a co-variant suggest th...

D. L. Coffin J. H. Knelson

1976-01-01

56

Cobalt and Nickel Removal from Zinc Sulfate Electrolyte by Solvent Extraction and Precipitation Techniques.  

National Technical Information Service (NTIS)

Sphalerite concentrates prepared during processing of Missouri lead ores contain small percentages of cobalt and nickel which adversely affect zinc electrolysis. The Federal Bureau of Mines has evaluated solvent extraction and precipitation techniques to ...

R. G. Sandberg T. L. Hebble

1978-01-01

57

Barium peritonitis in small animals.  

PubMed

Barium peritonitis is extremely rare, but is difficult to treat and may be life-threatening. Barium suspension leakage from the gastrointestinal tract into the abdominal cavity has a time-dependent and synergistically deleterious effect in patients who have generalized bacterial peritonitis. The severity of barium peritonitis is dependent on the quantity of barium in the abdominal cavity. Barium sulfate leakage results in hypovolemia and hypoproteinemia by worsening the exudation of extracellular fluid and albumin. Abdominal fluid analysis is a useful and efficient method to diagnose barium peritonitis. Serial radiographs may not be a reliable or timely diagnostic technique. Initial aggressive fluid resuscitation and empirical broad-spectrum antibiotic treatment should be instituted promptly, followed quickly by celiotomy. During exploratory surgical intervention, copious irrigation and direct wiping with gauze are employed to remove as much barium as possible. Omentectomy should be considered when needed to expedite barium removal. Despite aggressive medical and surgical treatments, postoperative prognosis is guarded to poor due to complications, such as acute vascular shock, sepsis, diffuse peritonitis, hypoproteninemia, electrolyte imbalance, cardiac arrest, small bowel obstruction related to progression of granulomas and adhesions in the abdominal cavity. Therefore, intensive postoperative monitoring and prompt intervention are necessary to maximize chances for a positive outcome. For those that do survive, small bowel obstruction is a potential consequence due to progression of abdominal adhesions. PMID:24430662

Ko, Jae Jin; Mann, F A Tony

2014-06-01

58

Barium Peritonitis in Small Animals  

PubMed Central

ABSTRACT Barium peritonitis is extremely rare, but is difficult to treat and may be life-threatening. Barium suspension leakage from the gastrointestinal tract into the abdominal cavity has a time-dependent and synergistically deleterious effect in patients who have generalized bacterial peritonitis. The severity of barium peritonitis is dependent on the quantity of barium in the abdominal cavity. Barium sulfate leakage results in hypovolemia and hypoproteinemia by worsening the exudation of extracellular fluid and albumin. Abdominal fluid analysis is a useful and efficient method to diagnose barium peritonitis. Serial radiographs may not be a reliable or timely diagnostic technique. Initial aggressive fluid resuscitation and empirical broad-spectrum antibiotic treatment should be instituted promptly, followed quickly by celiotomy. During exploratory surgical intervention, copious irrigation and direct wiping with gauze are employed to remove as much barium as possible. Omentectomy should be considered when needed to expedite barium removal. Despite aggressive medical and surgical treatments, postoperative prognosis is guarded to poor due to complications, such as acute vascular shock, sepsis, diffuse peritonitis, hypoproteninemia, electrolyte imbalance, cardiac arrest, small bowel obstruction related to progression of granulomas and adhesions in the abdominal cavity. Therefore, intensive postoperative monitoring and prompt intervention are necessary to maximize chances for a positive outcome. For those that do survive, small bowel obstruction is a potential consequence due to progression of abdominal adhesions.

KO, Jae Jin; MANN, F. A. (Tony)

2014-01-01

59

Depletion of highly abundant proteins in blood plasma by ammonium sulfate precipitation for 2D-PAGE analysis.  

PubMed

Ammonium sulfate precipitation (ASP) was explored as a method for depleting some highly abundant proteins from blood plasma, in order to reduce the dynamic range of protein concentration and to improve the detection of low abundance proteins by 2D-PAGE. 40% ammonium sulfate saturation was chosen since it allowed depleting 39% albumin and 82% ?-1-antitrypsin. ASP-depletion showed high reproducibility in 2D-PAGE analysis (4.2% variation in relative abundance of albumin), similar to that offered by commercial affinity-depletion columns. Besides, it allowed detecting 59 spots per gel, very close to the number of spots detected in immuno-affinity-depleted plasma. Thus, ASP at 40% saturation is a reliable depletion method that may help in proteomic analysis of blood plasma. Finally, ASP-depletion seems to be complementary to hydrophobic interaction chromatography (HIC)-depletion, and therefore an ASP-step followed by a HIC-step could probably deplete the most highly abundant plasma proteins, thus improving the detection of low abundance proteins by 2D-PAGE. PMID:21963274

Mahn, Andrea; Ismail, Maritza

2011-11-15

60

Relative role of decreasing precipitation sulfate and climate on recent lake recovery  

NASA Astrophysics Data System (ADS)

In the last 2 decades, acidic sulfur (S) depositions and SO4 concentration in surface water significantly decreased in many regions of the world, while at the same time temperatures have been increasing, particularly in the decade 1995-2005, which was one of the warmest ever recorded in the Northern Hemisphere. Understanding the potentially antagonistic or additive effects of decreasing S depositions and increasing temperatures on lake chemistry is essential to adequately evaluate the effectiveness of reduction programs for S emissions. By assessing the rate of change in climate variables, precipitation SO4 and lake chemistry for 47 temperate and boreal catchments, we found that changes in climate, particularly higher annual temperatures, were more often correlated to lake's pH and alkalinity than was the rate of decreasing S depositions between 1989 and 2005. It suggests that the recent improvement in the acid-base status of the studied lakes that cover a large area of northeastern North America as well as a large array of acid-base conditions cannot be attributed solely to a decrease in SO4 precipitation, but also to climatic variations. Not taking this information into account could lead to an overestimation of the benefit of lower SO4 deposition on aquatic ecosystems recovery.

Houle, Daniel; Couture, Suzanne; Gagnon, Christian

2010-12-01

61

Anthropogenic sulfate aerosol and the southward shift of tropical precipitation in the late 20th century  

NASA Astrophysics Data System (ADS)

In this paper, we demonstrate a global scale southward shift of the tropical rain belt during the latter half of the 20th century in observations and global climate models (GCMs). In rain gauge data, the southward shift maximizes in the 1980s and is associated with signals in Africa, Asia, and South America. A southward shift exists at a similar time in nearly all CMIP3 and CMIP5 historical simulations, and occurs on both land and ocean, although in most models the shifts are significantly less than in observations. Utilizing a theoretical framework based on atmospheric energetics, we perform an attribution of the zonal mean southward shift of precipitation across a large suite of CMIP3 and CMIP5 GCMs. Our results suggest that anthropogenic aerosol cooling of the Northern Hemisphere is the primary cause of the consistent southward shift across GCMs, although other processes affecting the atmospheric energy budget also contribute to the model-to-model spread.

Hwang, Yen-Ting; Frierson, Dargan M. W.; Kang, Sarah M.

2013-06-01

62

Barite fronts in continental margin sediments: a new look at barium remobilization in the zone of sulfate reduction and formation of heavy barites in diagenetic fronts  

Microsoft Academic Search

Micro-crystalline barites recovered by deep-sea drilling from Site 684 on the Peru margin and Site 799 in the Japan Sea are highly enriched in the heavy sulfur isotope relative to seawater (?34S up to + 84%). This isotopic composition is consistent with remobilization of biogenic barite triggered by sulfate reduction, and subsequent reprecipitation as a diagenetic barite front. The high

M. E. Torres; H. J. Brumsack; G. Bohrmann; K. C. Emeis

1996-01-01

63

Evaluation of feed COD\\/sulfate ratio as a control criterion for the biological hydrogen sulfide production and lead precipitation  

Microsoft Academic Search

The ability of sulfate-reducing bacteria to produce hydrogen sulfide and the high affinity of sulfide to react with divalent metallic cations represent an excellent option to remove heavy metals from wastewater. Different parameters have been proposed to control the hydrogen sulfide production by anaerobic bacteria, such as the organic and sulfate loading rates and the feed COD\\/SO42? ratio. This work

Antonio Velasco; Martha Ram ´ õrez; Tania Volke-Sep ´ ulveda; Armando Gonzalez-S; Sergio Revah

64

A partial equilibrium model to characterize the precipitation of ferric ion during the leaching of chalcopyrite with ferric sulfate  

SciTech Connect

A partial equilibrium model has been developed and used to characterize the conditions under which precipitation of ferric ion occurs during the dump leaching of chalcopyrite ores. The precipitates considered include amorphous Fe(OH)/sub 3/, ..cap alpha..-FeOOH (goethite), and Na/sup +/, K/sup +/, Ag/sup +/, Pb/sup 2 +/, and H/sub 3/O/sup +/ jarosites. The concentration product for Fe(OH)/sub 3/ (am) and ..cap alpha..-FeOOH was calculated for changing solution concentrations and compared with the solubility product constants to determine when precipitation would be expected thermodynamically. The K/sup +/, Na/sup +/, Ag/sup +/, and Pb/sup 2 +/ concentrations necessary to satisfy the solubility product constants were calculated for initial concentrations and varying amounts of O/sub 2/ consumption.

Liddell, K.C.; Bautista, R.G.

1983-03-01

65

Thermal decomposition of (BaTi) citrates into barium titanate  

Microsoft Academic Search

From aqueous solutions of barium and titanium citrates two different (BaTi) citrate salts can be precipitated, depending on the pH of the solution. The ratio of barium to titanium in the salts is either 1 : 1 or 2 : 1. The thermal decomposition of the salts was investigated by means of DTA, TGA, infrared spectroscopy, and X-ray diffraction. At

D. Hennings; W. Mayr

1978-01-01

66

Akaganéite (?-FeOOH) precipitation in inland acid sulfate soils of south-western New South Wales (NSW), Australia  

NASA Astrophysics Data System (ADS)

The prevalence of sulphidic sediments in inland wetlands has been only recently recognized in many parts of the world, including Australia. The exposure of sulphidic sediments in these wetlands due to natural and human induced drying events has resulted in the oxidation of iron sulfide minerals, the formation of secondary iron minerals characteristic of acid sulfate soils and the release of highly acidic solutions. The objective of this study was to determine the mineralogy and morphology of sediments collected from the oxidized surface horizon (0-5 cm) of an inland acid sulfate soil located in south-western New South Wales (NSW), Australia. Random powder X-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning transmission electron microscopy combined with energy dispersive X-ray spectroscopy (STEM-EDS) techniques were used to characterize the minerals present in these sediments. Akaganéite was identified as the major mineral phase in the sediments; K-jarosite was also determined in small amounts in some sediments. The XRD patterns of sequentially washed (E-pure® water-0.01 M HCl-0.01 M EDTA) sediment samples showed all akaganéite peaks; the Rietveld refinement of these patterns also revealed a predominance of akaganéite. The chemical analyses of the original and washed sediments using STEM-EDS clearly showed the presence of akaganéite as a pure mineral phase with an average Fe/Cl mole ratio of 6.7 and a structural formula of Fe 8O 8(OH) 6.8(Cl) 1.2. These findings show that the extreme saline-acidic solutions (pH ˜ 2, EC = 216 dS/m) at the Bottle Bend lagoon provide ideal conditions for the crystallization of this rarely forming mineral.

Bibi, Irshad; Singh, Balwant; Silvester, Ewen

2011-11-01

67

Emission spectrographic determination of barium in sea water using a cation exchange concentration procedure  

USGS Publications Warehouse

A concentration technique employing Dowex 50W cation exchange resin is described for the determination of barium in sea water. The separated barium is precipitated as fluoride together with calcium and strontium and measured by emission spectrographic analysis. The vertical distribution of barium in sea water has been measured in the Caribbean Sea and the Atlantic Ocean. The barium content varied between 7 and 23 ??g. per liter; in two profiles, the lowest concentrations were at a depth of about 1000 meters.

Szabo, B. J.; Joensuu, O.

1967-01-01

68

Barium enema (image)  

MedlinePLUS

A barium enema is performed to examine the walls of the colon. During the procedure, a well lubricated enema tube is inserted gently into the rectum. The barium, a radiopaque (shows up on X-ray) contrast ...

69

PMF analysis of impacts of SO 2 from Miyakejima and Asian Continent on precipitation sulfate in Japan  

NASA Astrophysics Data System (ADS)

PMF and back-trajectory analyses successfully evaluated contributions of sulfur dioxide to precipitation chemistry in Japan in terms of two major emission sources, Miyakejima and the Asian Continent. Precipitation chemistry datasets of Japanese Acid Deposition Survey (JADS) were subjected to PMF analysis to obtain the calculated concentration with contributions of five factors. The major sources were discussed for four selected JADS sites: Tanzawa, Tsukuba, Echizen and Goto. The first two are located close to Miyakejima, a volcano starting to erupt in 2000, while the others are located close to the Asian Continent on a national scale. PMF analysis of the observations suggested five factors, Factors 1-5, which corresponded to different acids and salts: Factor 1; H 2SO 4, Factor 2; HNO 3 and NH 4NO 3, Factor 3; (NH 4) 2SO 4 and NH 4NO 3, Factor 4; CaSO 4 and CaNO 3, and Factor 5; NaCl and MgCl 2. Concentration changes associated with the eruption of Miyakejima and the seasonal airflow were discussed in term of Factors 1-5. At Tanzawa and Tsukuba, the monthly mean concentration of Factor 1 remarkably changed after the onset of the eruption, although the concentrations of the other factors remained unchanged. This change suggested the volcanic SO 2 would be responsible for the Factor 1 concentration. No particular seasonality was confirmed for these sites. On the other hand, the volcanic impact did not appear to extend to Echizen and Goto because no apparent increases were detected in association with the eruption. However, remarkably seasonal changes were clearly detected for these sites, where winter concentration of SO 42- was two to four times larger than summer ones. This seasonal change was attributable to the northwesterly monsoon in winter which will transport SO 2 and SO 42- from the continental sources and the sea salt SO 42- from East China Sea and Sea of Japan, which was supported by back-trajectory analysis.

Kitayama, Kyo; Murao, Naoto; Hara, Hiroshi

2010-01-01

70

Sulfur-Tolerant NO x Storage Traps: An Infrared and Thermodynamic Study of the Reactions of Alkali and Alkaline-Earth Metal Sulfates  

Microsoft Academic Search

The sulfur tolerance of a barium-containing NOx storage\\/reduction trap was investigated using infrared analysis. It was confirmed that barium carbonate could be replaced by barium sulfate by reaction with low concentrations of sulfur dioxide (50 ppm) in the presence of large concentrations of carbon dioxide (10%) at temperatures up to 700 °C. These sulfates could at least be partially removed

J. P. Breen; M. Marella; C. Pistarino; J. R. H. Ross

2002-01-01

71

Microbial sulfate reduction within the Iheya North subseafloor hydrothermal system constrained by quadruple sulfur isotopes  

NASA Astrophysics Data System (ADS)

Subseafloor hydrothermal system may host active and abundant microbial community. Sulfate reduction may be one of the dominant microbial metabolisms among the subseafloor ecosystem. In order to demonstrate and quantify the potential sulfate reducing activity, we analyzed sulfur isotopes (32S/33S/34S/36S) of pore water sulfate extracted from core samples at the Iheya North hydrothermal system in the Okinawa drilled by CHIKYU, 2009 (IODP Leg 331). After drilling, core samples were divided into several sections. Then, pore water was extracted on board, and stored with cadmium chloride for fixing hydrogen sulfide. In our laboratory, the samples were first divided into sulfide precipitate and supernatant liquid by centrifugation. Then, dissolved sulfate was precipitated as BaSO4 by addition of barium chloride into the supernatant liquid. After weighing, the barium sulfate was converted into silver sulfide and subsequently sulfur hexafluoride, which was purified by GC and then introduced into mass spectrometer (MAT253) through newly developed microvolume inlet for precisely determining quadruple sulfur isotopic composition. Based on pore water chemistry and temperature profile, the subseafloor environment are divided into Unit-1, -2 and -3 with depth below surface. In Unit-1 (0-10 mbsf), fresh seawater is circulated, whereas in Unit-3 (>40 mbsf), hot hydrothermal fluid (>150 degrees Celsius) is stored below anhydrite cap. The Unit-2 is the mixing zone between the hydrothermal fluid and seawater. We found that the ?34S value of sulfate in the mixing zone was higher than those expected by simple mixing between seawater sulfate in Unit-1 (-20‰) and the hydrothermal component in Unit-3 (-16‰). The observed 34S-enrichment and decreased sulfate concentration suggest sulfate reduction took place in this hydrothermal system. Based on our model calculation assuming the mixing and reduction, apparent isotope effect for 33?, 34? and 36? are estimated to be -16.5‰, -32.2‰ and -62.5‰, respectively. These large fractionations together with slight D33S enrichment and D36S depletion all suggest that the sulfate reduction is microbial and not thermochemical process. Our numerical simulation also indicates that the sulfate is reduced before mixing with high temperature fluid, probably within the recharge zone of seawater. Based on these results, we will discuss microbial sulfur cycling in this subseafloor environment.

Aoyama, S.; Nishizawa, M.; Takai, K.; Ueno, Y.

2012-12-01

72

X?ray photoelectron and FTIR spectroscopic investigation of cement doped with barium nitrate  

Microsoft Academic Search

The chemical environment of barium in Portland cement which is doped with barium nitrate was investigated using x?ray photoelectron spectroscopy (XPS) and Fourier Transform Infrared spectroscopy (FTIR). The barium doped cement showed tremendous increases in carbonate content over the undoped cement. An XPS sulfate signal was observed in the cement doped with 20% w\\/w Ba(NO3)2 but not in the 0

H. G. McWhinney; M. W. Rowe; D. L. Cocke; J. D. Ortego

1990-01-01

73

Barium titanium glycolate: A new barium titanate powder precursor  

SciTech Connect

This paper describes the synthesis and structure of a barium titanium glycolate complex and the calcination into barium titanate preceramic powders that sinter into polycrystalline, tetragonal barium titanate having good dielectric properties.

Day, V.W.; Klemperer, W.G.; Payne, D.A. [Univ. of Nebraska, Lincoln, NE (United States)] [and others] [Univ. of Nebraska, Lincoln, NE (United States); and others

1996-02-01

74

Barium titanium glycolate: A new barium titanate powder precursor  

Microsoft Academic Search

This paper describes the synthesis and structure of a barium titanium glycolate complex and the calcination into barium titanate preceramic powders that sinter into polycrystalline, tetragonal barium titanate having good dielectric properties.

Victor W. Day; W. G. Klemperer; D. A. Payne; Shurong Liang

1996-01-01

75

Molecular Structure of Barium Chloride  

NSDL National Science Digital Library

Barium Chloride was the byproduct of the discovery of radium by Madame Curie. When refining radium, the final separation resulted in barium chloride and radium chloride. Electrophoresis of barium chloride produces small-scale amounts of barium atom. This can be used for obtaining barium for commercial uses. Applications of barium chloride include stimulating the heart and other muscles for medicinal purposes, and also for softening water. Other uses of barium chloride include the manufacturing of barium salts, as pesticide, pigments, boiler detergent, in purifying sugar, as mordant in dyeing and printing textiles, and in the manufacture of caustic soda, polymers, and stabilizers.

2002-08-15

76

Radioactive mineral spring precipitates, their analytical and statistical data and the uranium connection  

USGS Publications Warehouse

Major radioactive mineral springs are probably related to deep zones of active metamorphism in areas of orogenic tectonism. The most common precipitate is travertine, a chemically precipitated rock composed chiefly of calcium carbonate, but also containing other minerals. The mineral springs are surface manifestations of hydrothermal conduit systems which extend downward many kilometers to hot source rocks. Conduits are kept open by fluid pressure exerted by carbon dioxide-charged waters rising to the surface propelled by heat and gas (CO2 and steam) pressure. On reaching the surface, the dissolved carbon dioxide is released from solution, and calcium carbonate is precipitated. Springs also contain sulfur species (for example, H2S and HS-), and radon, helium and methane as entrained or dissolved gases. The HS- ion can react to form hydrogen sulfide gas, sulfate salts, and native sulfur. Chemical salts and native sulfur precipitate at the surface. The sulfur may partly oxidize to produce detectable sulfur dioxide gas. Radioactivity is due to the presence of radium-226, radon-222, radium-228, and radon-220, and other daughter products of uranium-238 and thorium-232. Uranium and thorium are not present in economically significant amounts in most radioactive spring precipitates. Most radium is coprecipitated at the surface with barite. Barite (barium sulfate) forms in the barium-containing spring water as a product of the oxidation of sulfur species to sulfate ions. The relatively insoluble barium sulfate precipitates and removes much of the radium from solution. Radium coprecipitates to a lesser extent with manganese-barium- and iron-oxy hydroxides. R-mode factor analysis of abundances of elements suggests that 65 percent of the variance of the different elements is affected by seven factors interpreted as follows: (1) Silica and silicate contamination and precipitation; (2) Carbonate travertine precipitation; (3) Radium coprecipitation; (4) Evaporite precipitation; (5) Hydrous limonite precipitation and coprecipitated elements including uranium; (6) Rare earth elements deposited with detrital contamination (?); (7) Metal carbonate adsorption and precipitation. Economically recoverable minerals occurring at some localities in spring precipitates are ores of iron, manganese, sulfur, tungsten and barium and ornamental travertine. Continental radioactive mineral springs occur in areas of crustal thickening caused by overthrusting of crustal plates, and intrusion and metamorphism. Sedimentary rocks on the lower plate are trapped between the plates and form a zone of metamorphism. Connate waters, carbonate rocks and organic-carbon-bearing rocks react to extreme pressure and temperature to produce carbon dioxide, and steam. Fractures are forced open by gas and fluid pressures. Deep-circulating meteoric waters then come in contact with the reactive products, and a hydrothermal cell forms. When hot mineral-charged waters reach the surface they form the familiar hot mineral springs. Hot springs also occur in relation to igneous intrusive action or volcanism both of which may be products of the crustal plate overthrusting. Uranium and thorium in the sedimentary rocks undergoing metamorphism are sometimes mobilized, but mobilization is generally restricted to an acid hydrothermal environment; much is redeposited in favorable environments in the metamorphosed sediments. Radium and radon, which are highly mobile in both acid and alkaline aqueous media move upward into the hydrothermal cell and to the surface.

Cadigan, R. A.; Felmlee, J. K.

1982-01-01

77

Barium toxicity and the role of the potassium inward rectifier current.  

PubMed

Abstract Introduction. Barium is a stable divalent earth metal and highly toxic upon acute and chronic exposure. Barium is present in many products and involved in a number of industrial processes. Barium targets the potassium inward rectifier channels (IRCs) of the KCNJx gene family. Extracellular barium enters and strongly binds the potassium selectivity filter region resulting in blockade of the potassium conducting pore. IRCs are involved in numerous physiological processes of the human body and the most barium sensitive IRCs are highly expressed in all muscle types. Objective. Our purpose was correlate to the clinical outcome of acute barium poisoning in man to current knowledge on IRC function. Methodology. The primary literature search was performed using Medline, Scopus and Google Scholar using search terms "barium AND poisoning"; "barium AND intoxication"; "barium AND case report" and retrieved publications from 1945 through 2012. Additional case reports were retrieved based on the reference lists of the primary hits. Duplicate publications, or publications presenting identical cases were omitted. A total of 39 case reports on acute barium poisoning containing 226 human subjects were identified for review. Results. BaCO3 was the most frequent source and food the most frequent mode of poisoning. Patients suffered from gastrointestinal (vomiting, diarrhea), cardiovascular (arrhythmias, hypertension), neuromuscular (abnormal reflexes, paralysis), respiratory (respiratory arrest/failure) and metabolic (hypokalemia) symptoms. Severe hypokalemia (< 2.5 mM) was observed from barium serum concentrations greater than or equal to 0.0025 mM. Review of the ECG outcomes demonstrated ventricular extrasystoles, ST changes and profound U-waves to be associated strongly with poisoning. Most common treatment modalities were gastric lavage, oral sulfates, potassium i.v. and cardiorespiratory support. 27 patients (12%) died from barium poisoning. Conclusions. Barium is a potent, non-specific inhibitor of the potassium IRC current and affects all types of muscle at micromolar concentrations. Gastrointestinal symptoms frequently occur early in the course of barium poisoning. Hypokalemia resulting from an intracellular shift of potassium and the direct effect of barium at the potassium channels explain the cardiac arrhythmias and muscle weakness which commonly occur in barium poisoning. Treatment of barium poisoning is mainly supportive. Orally administered sulfate salts to form insoluble barium sulfate in the intestinal tract and potassium supplementation have potential but unproven benefit. PMID:24905573

Bhoelan, B S; Stevering, C H; van der Boog, A T J; van der Heyden, M A G

2014-07-01

78

Effects of barium chlorine treatment of uranium ore on ²²²Rn emanation and ²²⁶Ra leachability from mill tailings  

Microsoft Academic Search

The purpose of this laboratory study was to investigate the effectiveness of barium chloride treatment of uranium ore on ²²²Rn emanation from mill tailings, ²²⁶Ra level in waste-water, and the leachability of radium from tailings. It has been shown that barium sulfate is an excellent carrier for radium and that barium sulfate crystals have high retention capacity for radon gas

S. A. Ibrahim; S. L. Church; F. W. Whicker

1985-01-01

79

[Determination of the sulfate ion content in antibiotic sulfate salts by a complexometric titration method].  

PubMed

A possibility of assaying antibiotic sulfates, such as gentamicin, kanamycin, monomycin, neomycin, ristomycin, streptomycin, florimycin and polymyxin M sulfates for sulfate ions by titration with barium chloride in the presence of chlorphosphonaso-III, a metal indicator immediately in the salt solutions or after elimination of the cation by means of ion exchange (sulfocation exchange resins in H+-form) was tested. The procedure was shown to be adequate to the classical weight method. PMID:7469396

Kartseva, V D; Lokshin, G B; Libinson, G S; Kruzhkova, N G

1980-12-01

80

Particulate barium fluxes and their relationships to biological productivity  

NASA Astrophysics Data System (ADS)

To understand better the processes that control the transport of particulate barium through the water column and its preservation in marine sediments, we measured particulate barium fluxes along an equatorial transect at 140°W using moored sediment traps. The fluxes of barium correlate strongly with the fluxes of organic carbon; however, this relationship is non-linear—higher carbon fluxes have proportionately less associated barium. As a result we observe spatial and temporal variations of roughly a factor of three in the barium-to-organic carbon ratio. Understanding this variability may help to define the processes that determine the geochemical behavior of Ba in the oceans. Several hypotheses that could influence the flux of Ba and its relationship to organic carbon flux have been proposed: barite formation in barium- and sulfate-enriched microenvironments formed during particle settling; lateral advection of carbon and barium from continental margins; the influence of seawater barium concentration; and Ba scavenging by aluminosilicates. Our study reveals temporal variability in the Ba/C org values that occurs over timescales of less than one month. Also, depth profiles of carbon and Ba fluxes show that the variability originates at depths less than 1200 m and is conveyed throughout the water column. Both the rapid changes and the upper water column origin of the signals point to upper-ocean biological processes as the predominant cause of the variability in the barium-to-organic carbon ratios. We also observe, however, a 25% increase in Ba flux below 1200 m. The deep sources of Ba could result from barite formation linked to continued organic carbon degradation or from lateral sources of particulate barium. Because the spatial and temporal changes in Ba/C org values correlated to changes in particulate opal and organic carbon fluxes, ocean ecology appears to have an important influence on barium fluxes. A better understanding of the processes that contribute to the particulate barium flux is needed before the accumulation of barium in marine sediments can be used as a quantitative proxy for ocean productivity.

Dymond, Jack; Collier, Robert

81

Beta barium borate (BBO)  

Microsoft Academic Search

The paper contains a review of crystallographic, optical and nonlinear optical properties of beta barium borate (ß-BaB2O4 or BBO) crystal and presents a description of its typical applications in nonlinear optics and quantum electronics.

D. N. Nikogosyan

1991-01-01

82

Radium and barium removal through blending hydraulic fracturing fluids with acid mine drainage.  

PubMed

Wastewaters generated during hydraulic fracturing of the Marcellus Shale typically contain high concentrations of salts, naturally occurring radioactive material (NORM), and metals, such as barium, that pose environmental and public health risks upon inadequate treatment and disposal. In addition, fresh water scarcity in dry regions or during periods of drought could limit shale gas development. This paper explores the possibility of using alternative water sources and their impact on NORM levels through blending acid mine drainage (AMD) effluent with recycled hydraulic fracturing flowback fluids (HFFFs). We conducted a series of laboratory experiments in which the chemistry and NORM of different mix proportions of AMD and HFFF were examined after reacting for 48 h. The experimental data combined with geochemical modeling and X-ray diffraction analysis suggest that several ions, including sulfate, iron, barium, strontium, and a large portion of radium (60-100%), precipitated into newly formed solids composed mainly of Sr barite within the first ? 10 h of mixing. The results imply that blending AMD and HFFF could be an effective management practice for both remediation of the high NORM in the Marcellus HFFF wastewater and beneficial utilization of AMD that is currently contaminating waterways in northeastern U.S.A. PMID:24367969

Kondash, Andrew J; Warner, Nathaniel R; Lahav, Ori; Vengosh, Avner

2014-01-21

83

Dissolution of Barium from Barite in Sewage Sludges and Cultures of Desulfovibrio desulfuricans  

PubMed Central

High concentrations of total barium, ranging from 0.42 to 1.58 mg(middot)g(sup-1) (dry weight) were found in sludges of two sewage treatment plants near Florence, Italy. Barium concentrations in the suspended matter decreased as redox potential values changed from negative to positive. An anoxic sewage sludge sample was aerated, and 30% of the total barium was removed in 24 h. To demonstrate that barium was solubilized from barite by sulfate-reducing bacteria, a strain of Desulfovibrio desulfuricans was used to study the solubilization of barium from barite under laboratory conditions. During cell growth with different concentrations of barite from 0.01 to 0.3 g(middot)liter(sup-1) (the latter is the MIC) as the only source of sulfates in the cultures, the D. desulfuricans strain accumulated barium up to 0.58 (mu)g(middot)mg(sup-1) (dry weight). Three times the quantity of barium was dissolved by bacteria than in the uninoculated medium (control). The unexpectedly low concentration of soluble barium (1.2 mg of Ba(middot)liter(sup-1)) with respect to the quantity expected (109 mg of Ba(middot)liter(sup-1)), calculated on the basis of the free H(inf2)S evolved from the dissimilatory reduction of sulfate from barite, was probably due to the formation of other barium compounds, such as witherite (BaCO(inf3)) and the transient species barium sulfide (BaS). The D. desulfuricans strain, growing on barite, formed visible aggregates. Confocal microscopy analysis showed that aggregates consisted of bacteria and barite. After 3 days of incubation, several autofluorescent crystals surrounded by a dissolution halo were observed. The crystals were identified as BaS by comparison with the commercial compound.

Baldi, F.; Pepi, M.; Burrini, D.; Kniewald, G.; Scali, D.; Lanciotti, E.

1996-01-01

84

Isotopic Zonation Within Sulfate Evaporite Mineral Crystals Reveal Quantitative Paleoenvironment Details  

NASA Astrophysics Data System (ADS)

Isotopic variations measured within a single crystal of hydrated magnesium sulfate are greater than 30 permil for delta 2-H, almost 10 permil for ?18O in water of hydration; and greater than 3 permil in sulfate oxygen. These results are interpreted to indicate the relative humidity of the system during evaporation (15 to 20 percent in this test case) and constrain the volume of water involved. The theoretical basis of this system is the isotopic fractionation between the species in solution and those precipitated as evaporite salts. Precipitation preferentially accumulates more of the heavy isotopes of sulfur and oxygen in mineral sulfate, relative to sulfate in solution. During the course of mineral growth this leads to successive depletion of the respective heavier isotopes in the residual brine reflected in a parallel trend in successive precipitates or even in successive zones within a single crystal. The change in isotopic composition at any one time during the process, relative to the initial value, can be described by an isotopic version of the Rayleigh Fractionation equation, depending only on the extent of the completion of the process and the relevant fractionation factor. Evaporation preferentially removes isotopically lighter hydrogen and oxygen leading to successive extents of enrichment in the respective heavier isotopes in the residual water. However, the relative effects on hydrogen and oxygen isotopes differs as function of relative humidity [1]. ALL OF THESE CHANGES ARE PRESERVED IN THE MINERAL ISOTOPE COMPOSITIONS. We precipitated barium sulfate from epsomite or gypsum samples, which was reduced at 1450°C in the presence of graphite and glassy carbon in a Finnigan TC/EA to produce CO for O isotopic analysis in a Finnigan 253 mass spectrometer, while a separate subsample was oxidized to SO2 in a Costech Elemental Analyzer. However, to make progress with this approach we needed to make a large number of measurements of hydration water and so we developed a new analytical method [2]. We use a modification of the standard TC/EA continuous-flow protocol to measure both hydrogen and oxygen of water of hydration from the same small sample. We have proved the concept of this new approach by analyzing zones within crystals and individual grains, growing epsomite (magnesium sulfate heptahydrate) in the laboratory and by analysis of natural gypsum evaporites. We are now exploring the effects of varying the controlling parameters. Eventual application to Martian sulfates will reveal amount of water involved in sulfate formation, its isotopic composition(s) and details of the paleo-atmospheric humidity. [1] Gat JR and Gonfiantini R, (Eds) (1981) IAEA Technical Report Series. [2] Rohrssen MK, Brunner B Mielke RE and Coleman M (2008) Analyt. Chem. (in press).

Coleman, M.; Rhorssen, M.; Mielke, R. E.

2008-12-01

85

New solutions to an old problem: calcium sulfate deposition in the Permian Basin  

Microsoft Academic Search

Scale deposits in producing oil wells and equipment are a serious problem in many areas of the country. There are 3 principal types of scale that are particularly troublesome--calcium carbonate, calcium sulfate, and barium sulfate. Calcium sulfate scale is predominant in many areas, particularly in the Permian basin of West Texas. Some operators in the West Texas area report growth

2009-01-01

86

Observed Barium Emission Rates  

NASA Technical Reports Server (NTRS)

The barium releases from the CRRES satellite have provided an opportunity for verifying theoretically calculated barium ion and neutral emission rates. Spectra of the five Caribbean releases in the summer of 1991 were taken with a spectrograph on board a U.S. Air Force jet aircraft. Because the line of sight release densities are not known, only relative rates could be obtained. The observed relative rates agree well with the theoretically calculated rates and, together with other observations, confirm the earlier detailed theoretical emission rates. The calculated emission rates can thus with good accuracy be used with photometric observations. It has been postulated that charge exchange between neutral barium and oxygen ions represents a significant source for ionization. If so. it should be associated with emissions at 4957.15 A and 5013.00 A, but these emissions were not detected.

Stenbaek-Nielsen, H. C.; Wescott, E. M.; Hallinan, T. J.

1993-01-01

87

Dissolution of Barium from Barite in Sewage Sludges and Cultures ofDesulfovibrio desulfuricans  

Microsoft Academic Search

to 0.3 g zliter 21 (the latter is the MIC) as the only source of sulfates in the cultures, theD. desulfuricansstrain accumulated barium up to 0.58 mg zmg 21 (dry weight). Three times the quantity of barium was dissolved by bacteriathanintheuninoculatedmedium(control).Theunexpectedlylowconcentrationofsolublebarium(1.2 mg of Ba zliter 21 ) with respect to the quantity expected (109 mg of Ba zliter 21 ),

FRANCO BALDI; MILVA PEPI; DANIELA BURRINI; GORAN KNIEWALD; DANIELA SCALI; ANDEUDES LANCIOTTI

1996-01-01

88

Superconductivity in barium fulleride  

NASA Astrophysics Data System (ADS)

The intercalation of fulleride with barium is reported. A pure body-centered cubic phase with a lattice constant of 11.171 A is realized near a stoichiometry of Ba6C60. This phase is also superconducting, suggesting that the mechanism of superconductivity is related to an intrinsic property of the C60 molecules, rather than the external coordination number.

Kortan, A. R.; Kopylov, N.; Glarum, S.; Gyorgy, E. M.; Ramirez, A. P.; Fleming, R. M.; Zhou, O.; Thiel, F. A.; Trevor, P. L.; Haddon, R. C.

1992-12-01

89

Semiconducting barium titanate  

Microsoft Academic Search

Barium titanate, which is well known as a basic ferroelectric material, is also of interest when doped because of the interaction between semiconductivity and ferroelectricity. The resistance of blocking layers at surfaces and grain-boundaries is governed mainly by the ferroelectric properties, so that a resistance jump of four decades is observed on heating above the Curie temperature. A survey of

W. Heywang

1971-01-01

90

Sulfate Aerosol Particulates  

NASA Astrophysics Data System (ADS)

The condensation of SO3 vapor to detrimental acid-mist occurs only after substantial flue gas cooling, usually downstream from electrostatic precipitators. This condensation is an equilibrium process depending on gas temperature and water vapor pressure. Smelter plume opacity is related to acidmist and other sulfate aerosol particulate concentration through Mie particulate scattering theory. It is possible to estimate the amounts of sulfate particulate emissions and plume opacity, particularly those resulting from anticipated changes in smelter operations and flue gas treatment. These estimates can be used to determine compliance with current or anticipated regulations on smelter particulate emissions or plume opacity.

Bartlett, Robert W.

1987-09-01

91

Comparing the relationship between precipitation and river geochemistry  

NASA Astrophysics Data System (ADS)

The geochemistry of precipitation affects the geochemistry of river water. Ideally, studies of river biogeochemistry should therefore include collection and analyses of dry and wet deposition. The Global Rivers Observatory has studied the Fraser River near Vancouver since the summer of 2009 at roughly bi-weekly resolution. The interpretation of this temporal record of river biogeochemistry, particularly the various sources of solutes, could be improved with a better understanding of atmospheric contributions. In this study precipitation and river water will be analysed from the Fraser River basin for nutrients as well as major and select trace ion concentrations. The nutrients analyzed will include ammonium (NH4), nitrate and nitrate (NO3-NO2), phosphate (PO4) and silicate (SiO4). Major ions include sodium (Na), potassium (K), calcium (Ca), magnesium (Mg), chloride (Cl), and sulfate (SO4). Trace elements may include molybdenum, strontium, barium, uranium, rubidium, manganese and iron. Samples will be collected using the bulk method which collects both wet and dry deposition . Correlating precipitation chemistry with data on wind direction may help elucidate sources of nutrients and major ions. For instance, westerly sources may transport pollution from the City of Vancouver and agricultural lands in the Fraser delta. Such pollutants may increase the acidity of precipitation and imprint the water chemistry with a unique chemical signature . The results of this study will be helpful in correcting Fraser River water data for contributions from atmospheric deposition.

Epp, A.; Luymes, R.; Bennett, M.; DaSilva, J.; Marsh, S. J.; Gillies, S. L.; Peucker-Ehrenbrink, B.; Voss, B.

2013-12-01

92

Rapid barium removal in the Delaware estuary  

SciTech Connect

Six profiles of dissolved barium covering the entire salinity range of the Delaware River and Bay estuary from March through September 1996 were collected and analyzed. The profiles are similar to one another in both shape and magnitude except for one attribute. A sudden ({le} 24 days), nearly complete (>90%) removal of dissolved Ba in midestuary occurs in mid-May followed by an 80% recovery in early June. This removal appears to be temporally and spatially coupled to the end of the spring bloom. Based on such episodic behavior, and on recent work with flocculation of diatom exudates, the authors conclude that the Ba depletion is caused by barite precipitation in the estuary during the late stages of the bloom. This would imply that lower estuary and inner coastal margin sediments associated with eutrophic estuaries receive a seasonal pulse of barite. The suddenness of this event also implies that sedimentary barite is strongly influenced by high productivity events. Comparison of the riverine Ba concentration with the effective riverine end member after desorptive barium release yields an estimated 30--40 nM Ba available from the suspended sediments as they enter the estuary. This estimate is supported by excess barium in unfiltered samples over filtered samples taken from the river and also by calculations done elsewhere.

Stecher, H.A. III [Univ. of Delaware, Lewes, DE (United States). College of Marine Studies] [Univ. of Delaware, Lewes, DE (United States). College of Marine Studies; [Univ. of Delaware, Newark, DE (United States). Dept. of Geology; Kogut, M.B. [Univ. of Washington, Seattle, WA (United States). School of Oceanography] [Univ. of Washington, Seattle, WA (United States). School of Oceanography

1999-04-01

93

75 FR 33824 - Barium Chloride From China  

Federal Register 2010, 2011, 2012, 2013

...No. 731-TA-149 (Third Review)] Barium Chloride From China Determination On the...revocation of the antidumping duty order on barium chloride from China would be likely to...Publication 4157 (June 2010), entitled Barium Chloride from China: Investigation...

2010-06-15

94

75 FR 19657 - Barium Chloride From China  

Federal Register 2010, 2011, 2012, 2013

...No. 731-TA-149 (Third Review)] Barium Chloride From China AGENCY: United States...concerning the antidumping duty order on barium chloride from China...revocation of the antidumping duty order on barium chloride from China would be likely...

2010-04-15

95

Properties of Semiconductive Barium Titanates  

Microsoft Academic Search

The resistivity of barium titanate which is usually of the order of 109˜1012 ohm-cm, may be remarkably reduced with suitable control in valency. The valency-controlled barium titanate, whose resistivity is of the order of 10˜104 ohm-cm at room temperature, shows anomalous positive character in the temperature dependency of the resistivity. For example, the resistivity of barium titanate containing 0.1 mol.

Osamu Saburi

1959-01-01

96

Optimized photorefractive barium titanate  

Microsoft Academic Search

The goal of this research program was to investigate new and modified crystal-growth techniques that would lead to high-optical-quality BaTiO3 with increased photorefractive speed and sensitivity. The research program consisted of four parts: (1) feed material purification; (2) crystal growth by the top-seeded-solution technique as well as by a barium borate flux technique; (3) new furnace design studies; and (4)

Cardinal Warde; Hans P. Jenssen

1992-01-01

97

Sources of sulfate supporting anaerobic metabolism in a contaminated aquifer  

USGS Publications Warehouse

Field and laboratory techniques were used to identify the biogeochemical factors affecting sulfate reduction in a shallow, unconsolidated alluvial aquifer contaminated with landfill leachate. Depth profiles of 35S-sulfate reduction rates in aquifer sediments were positively correlated with the concentration of dissolved sulfate. Manipulation of the sulfate concentration in samples revealed a Michaelis-Menten-like relationship with an apparent Km and Vmax of approximately 80 and 0.83 ??M SO4-2??day-1, respectively. The concentration of sulfate in the core of the leachate plume was well below 20 ??M and coincided with very low reduction rates. Thus, the concentration and availability of this anion could limit in situ sulfate-reducing activity. Three sulfate sources were identified, including iron sulfide oxidation, barite dissolution, and advective flux of sulfate. The relative importance of these sources varied with depth in the alluvium. The relatively high concentration of dissolved sulfate at the water table is attributed to the microbial oxidation of iron sulfides in response to fluctuations of the water table. At intermediate depths, barite dissolves in undersaturated pore water containing relatively high concentrations of dissolved barium (???100 ??M) and low concentrations of sulfate. Dissolution is consistent with the surface texture of detrital barite grains in contact with leachate. Laboratory incubations of unamended and barite-amended aquifer slurries supported the field observation of increasing concentrations of barium in solution when sulfate reached low levels. At a deeper highly permeable interval just above the confining bottom layer of the aquifer, sulfate reduction rates were markedly higher than rates at intermediate depths. Sulfate is supplied to this deeper zone by advection of uncontaminated groundwater beneath the landfill. The measured rates of sulfate reduction in the aquifer also correlated with the abundance of accumulated iron sulfide in this zone. This suggests that the current and past distributions of sulfate-reducing activity are similar and that the supply of sulfate has been sustained at these sites.

Ulrich, G. A.; Breit, G. N.; Cozzarelli, I. M.; Suflita, J. M.

2003-01-01

98

Synthesis, characterization and microwave absorption properties of titania-coated barium ferrite composites  

Microsoft Academic Search

Anatase titania-coated barium ferrite composites were prepared by a heterogeneous precipitation method in the presence of barium ferrite particles. The obtained samples were characterized by xi-pH, TEM, EDX and XRD. The complex permittivity and permeability were studied in the frequency range of 2 12 GHz. The structure and microwave response properties are investigated. The results show that the coverage of

X. Tang; B. Y. Zhao; Q. Tian; K. A. Hu

2006-01-01

99

Synthesis, characterization and microwave absorption properties of titania-coated barium ferrite composites  

Microsoft Academic Search

Anatase titania-coated barium ferrite composites were prepared by a heterogeneous precipitation method in the presence of barium ferrite particles. The obtained samples were characterized by ?-pH, TEM, EDX and XRD. The complex permittivity and permeability were studied in the frequency range of 2–12GHz. The structure and microwave response properties are investigated. The results show that the coverage of titania has

X. Tang; B. Y. Zhao; Q. Tian; K. A. Hu

2006-01-01

100

Synthesis, characterization and microwave absorption properties of titania-coated barium ferrite composites  

NASA Astrophysics Data System (ADS)

Anatase titania-coated barium ferrite composites were prepared by a heterogeneous precipitation method in the presence of barium ferrite particles. The obtained samples were characterized by ?-pH, TEM, EDX and XRD. The complex permittivity and permeability were studied in the frequency range of 2 12 GHz. The structure and microwave response properties are investigated. The results show that the coverage of titania has a great influence on microwave response of barium ferrite. The formation of an anatase titania nano-layer on the surface of a barium ferrite particle changes the character of the frequency dispersion of the complex permittivity. Comparing the anatase titania-coated barium ferrite composites with the uncoated barium ferrite, the complex permittivity of the anatase titania-coated barium ferrite composites is higher than that of uncoated barium ferrite. The complex permeability of composites was found to decrease with an increase in frequency as well as with the molar ratio of Ti:Ba. The enhancement of the complex permittivity may be due to dipolar polarization and interfacial polarization. The maximum reflection loss was obtained at the Ti:Ba ratio of 1:10, and the peak of the maximum reflection loss shifts to a lower frequency value with increasing titania fraction. By changing the thickness of titania coverage, the frequency dependence of the complex permittivity could be adjusted, which provides us an opportunity for the synthesis of tailored particles.

Tang, X.; Zhao, B. Y.; Tian, Q.; Hu, K. A.

2006-12-01

101

Barium uranyl diphosphonates  

NASA Astrophysics Data System (ADS)

Three Ba2+/UO22+ methylenediphosphonates have been prepared from mild hydrothermal treatment of uranium trioxide, methylendiphosphonic acid (C1P2) with barium hydroxide octahydrate, barium iodate monohydrate, and small aliquots of HF at 200 °C. These compounds, Ba[UO2[CH2(PO3)2]·1.4H2O (Ba-1), Ba3[(UO2)4(CH2(PO3)2)2F6]·6H2O (Ba-2), and Ba2[(UO2)2(CH2(PO3)2)F4]·5.75H2O (Ba-3) all adopt layered structures based upon linear uranyl groups and disphosphonate molecules. Ba-2 and Ba-3 are similar in that they both have UO5F2 pentagonal bipyramids that are bridged and chelated by the diphosphonate moiety into a two-dimensional zigzag anionic sheet (Ba-2) and a one-dimensional ribbon anionic chain (Ba-3). Ba-1, has a single crystallographically unique uranium metal center where the C1P2 ligand solely bridges to form [UO2[CH2(PO3)2]2- sheets. The interlayer space of the structures is occupied by Ba2+, which, along with the fluoride ion, mediates the structure formed and maintains overall charge balance.

Nelson, Anna-Gay D.; Alekseev, Evgeny V.; Ewing, Rodney C.; Albrecht-Schmitt, Thomas E.

2012-08-01

102

Discovery of the barium isotopes  

SciTech Connect

Thirty-eight barium isotopes have been observed so far and the discovery of these isotopes is discussed here. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.

Shore, A.; Fritsch, A.; Ginepro, J.Q.; Heim, M.; Schuh, A. [National Superconducting Cyclotron Laboratory and Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States); Thoennessen, M., E-mail: thoennessen@nscl.msu.ed [National Superconducting Cyclotron Laboratory and Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States)

2010-11-15

103

Barium swallow study in routine clinical practice: a prospective study in patients with chronic cough*,**  

PubMed Central

OBJECTIVE: To assess the routine use of barium swallow study in patients with chronic cough. METHODS: Between October of 2011 and March of 2012, 95 consecutive patients submitted to chest X-ray due to chronic cough (duration > 8 weeks) were included in the study. For study purposes, additional images were obtained immediately after the oral administration of 5 mL of a 5% barium sulfate suspension. Two radiologists systematically evaluated all of the images in order to identify any pathological changes. Fisher's exact test and the chi-square test for categorical data were used in the comparisons. RESULTS: The images taken immediately after barium swallow revealed significant pathological conditions that were potentially related to chronic cough in 12 (12.6%) of the 95 patients. These conditions, which included diaphragmatic hiatal hernia, esophageal neoplasm, achalasia, esophageal diverticulum, and abnormal esophageal dilatation, were not detected on the images taken without contrast. After appropriate treatment, the symptoms disappeared in 11 (91.6%) of the patients, whereas the treatment was ineffective in 1 (8.4%). We observed no complications related to barium swallow, such as contrast aspiration. CONCLUSIONS: Barium swallow improved the detection of significant radiographic findings related to chronic cough in 11.5% of patients. These initial findings suggest that the routine use of barium swallow can significantly increase the sensitivity of chest X-rays in the detection of chronic cough-related etiologies.

Nin, Carlos Shuler; Marchiori, Edson; Irion, Klaus Loureiro; Paludo, Artur de Oliveira; Alves, Giordano Rafael Tronco; Hochhegger, Daniela Reis; Hochhegger, Bruno

2013-01-01

104

Determination of barium in sulphide ores, concentrates and other geological samples by flame atomic-absorption spectrometry.  

PubMed

A rapid, precise and selective analytical method has been developed for estimation of barium in geological samples by flame atomic-absorption spectrometry. The method consists of precipitation of barium sulphate with ammonium sulphate, followed by dissolution of the sulphates in EDTA at pH 10. The barium in this solution is measured by AAS with a nitrous oxide-acetylene flame. Appreciable amounts of lead, calcium and strontium can be tolerated in the method, which has been applied for estimation of barium in sulphide ores and concentrates of lead, zinc and copper, and is feasible for estimation of barium from 20.0 ppm to the per cent level in such geological samples. PMID:18963404

Sharma, K D

1983-07-01

105

Analysis of Barium Clouds. Volume I.  

National Technical Information Service (NTIS)

Several aspects of the analysis of barium ion clouds are presented including ion cloud modeling, comparison of radar and optical data, and correlation of data with theory. A quantitative model has been developed from which various properties of barium ion...

B. Kivel L. F. Cianciolo L. M. Linson S. Powers

1972-01-01

106

Solid-state barium-vapor detector  

Microsoft Academic Search

The need for electrical switching devices for use in high-temperature radioactive environments in space nuclear power systems has led to the development of the cesium-barium tacitron. Effective evaluation of electrically insulating joints for the barium-cesium tacitron requires a method for the in situ detection of barium vapor which may leak through the joint. A solid-state barium-vapor detector has been developed

Jeffrey W. Fergus; S. Hui

1995-01-01

107

CT-Guided Percutaneous Transthoracic Localization of Pulmonary Nodules Prior to Video-Assisted Thoracoscopic Surgery Using Barium Suspension  

PubMed Central

Objective To describe our initial experience with CT-guided percutaneous barium marking for the localization of small pulmonary nodules prior to video-assisted thoracoscopic surgery (VATS). Materials and Methods From October 2010 to April 2011, 10 consecutive patients (4 men and 6 women; mean age, 60 years) underwent CT-guided percutaneous barium marking for the localization of 10 small pulmonary nodules (mean size, 7.6 mm; range, 3-14 mm): 6 pure ground-glass nodules, 3 part-solid nodules, and 1 solid nodule. A 140% barium sulfate suspension (mean amount, 0.2 mL; range, 0.15-0.25 mL) was injected around the nodules with a 21-gauge needle. The technical details, surgical findings and pathologic features associated with barium localizations were evaluated. Results All nodules were marked within 3 mm (mean distance, 1.1 mm; range, 0-3 mm) from the barium ball (mean diameter, 9.6 mm; range, 8-16 mm) formed by the injected barium suspension. Pneumothorax occurred in two cases, for which one needed aspiration. However, there were no other complications. All barium balls were palpable during VATS and visible on intraoperative fluoroscopy, and were completely resected. Both the whitish barium balls and target nodules were identifiable in the frozen specimens. Pathology revealed one invasive adenocarcinoma, five adenocarcinoma-in-situ, two atypical adenomatous hyperplasias, and two benign lesions. In all cases, there were acute inflammations around the barium balls which did not hamper the histological diagnosis of the nodules. Conclusion CT-guided percutaneous barium marking can be an effective, convenient and safe pre-operative localization procedure prior to VATS, enabling accurate resection and diagnosis of small or faint pulmonary nodules.

Lee, Nyoung Keun; Kang, Chang Hyun; Jeon, Yoon Kyung; Choo, Ji Yung; Lee, Hyun-Ju; Goo, Jin Mo

2012-01-01

108

Sources of sulfate supporting anaerobic metabolism in a contaminated aquifer.  

PubMed

Field and laboratory techniques were used to identify the biogeochemical factors affecting sulfate reduction in a shallow, unconsolidated alluvial aquifer contaminated with landfill leachate. Depth profiles of 35S-sulfate reduction rates in aquifer sediments were positively correlated with the concentration of dissolved sulfate. Manipulation of the sulfate concentration in samples revealed a Michaelis-Menten-like relationship with an apparent Km and Vmax of approximately 80 and 0.83 microM SO4(-2) x day(-1), respectively. The concentration of sulfate in the core of the leachate plume was well below 20 microM and coincided with very low reduction rates. Thus, the concentration and availability of this anion could limit in situ sulfate-reducing activity. Three sulfate sources were identified, including iron sulfide oxidation, barite dissolution, and advective flux of sulfate. The relative importance of these sources varied with depth in the alluvium. The relatively high concentration of dissolved sulfate at the water table is attributed to the microbial oxidation of iron sulfides in response to fluctuations of the water table. At intermediate depths, barite dissolves in undersaturated pore water containing relatively high concentrations of dissolved barium (approximately 100 microM) and low concentrations of sulfate. Dissolution is consistent with the surface texture of detrital barite grains in contact with leachate. Laboratory incubations of unamended and barite-amended aquifer slurries supported the field observation of increasing concentrations of barium in solution when sulfate reached low levels. At a deeper highly permeable interval just above the confining bottom layer of the aquifer, sulfate reduction rates were markedly higher than rates at intermediate depths. Sulfate is supplied to this deeper zone by advection of uncontaminated groundwater beneath the landfill. The measured rates of sulfate reduction in the aquifer also correlated with the abundance of accumulated iron sulfide in this zone. This suggests that the current and past distributions of sulfate-reducing activity are similar and that the supply of sulfate has been sustained at these sites. PMID:12680660

Ulrich, Glenn A; Breit, George N; Cozzarelli, Isabelle M; Suflita, Joseph M

2003-03-15

109

Computer modelling of barium titanate  

Microsoft Academic Search

Barium titanate is an important material for both scientific and industrial applications. Much of the interest centres around its ferroelectric properties, since it is structurally the most simple in this class. In addition rare-earth doped ceramics are found to exhibit a very steep positive temperature coefficient of resistance (PTCR) above the Curie point. The theory of this PTCR effect is

G. V. Lewis; C. R. A. Catlow

1983-01-01

110

Recent Developments in Barium Borate,  

National Technical Information Service (NTIS)

The nonlinear optical properties of Beta-BaB2O4(beta barium borate) are demonstrated in the generation of second through fifth harmonics of 1.06-micrometer neodymium laser radiation, and in optical parametric oscillation pumped by 532-nm radiation. Beta-B...

C. Chen Y. X. Fan R. C. Eckardt R. L. Byer

1986-01-01

111

Distribution and source of barium in ground water at Cattaraugus Indian Reservation, southwestern New York  

USGS Publications Warehouse

High concentrations of dissolved barium have been found in ground water from bedrock wells on the Seneca Nation of Indians Reservation on Cattaraugus Creek in southwestern New York. Concentrations in 1982 were as high as 23.0 milligrams per liter , the highest found reported from any natural ground-water system in the world. The highest concentrations are in a bedrock aquifer and in small lenses of saturated gravel between bedrock and the overlying till. The bedrock aquifer is partly confined by silt, clay, and till. The high barium concentrations are attributed to dissolution of the mineral barite (BaSO4), which is present in the bedrock and possibly in overlying silt, clay, or till. The dissolution of barite seems to be controlled by action of sulfate-reducing bacteria, which alter the BaSO4 equilibrium by removing sulfate ions and permitting additional barite to dissolve. Ground water from the surficial, unconsolidated deposits and surface water in streams contain little or no barium. Because barium is chemically similar to calcium, it probably could be removed by cation exchange or treatments similar to those used for water softening. (USGS)

Moore, R. B.; Staubitz, W. W.

1984-01-01

112

Barium uptake and adsorption in diatoms  

NASA Astrophysics Data System (ADS)

Using trace metal-defined culture conditions, we measured the cellular barium concentration in cultures of the diatom Thalassiosira weissflogii. In cultures with low Fe concentration, at a typical surface seawater Ba concentration of 35 to 40 nmol/L, the cellular Ba was 0.5 ?mol/mol P (˜0.04 ?g/g dw), much below all previously published values for phytoplankton. When the Fe concentration in the growth medium was increased, the measured "cellular" Ba increased proportionally to the particulate Fe. Under conditions of ferric hydroxide precipitation, similar particulate Ba concentrations were measured in the absence and the presence of cells for a given concentration of particulate Fe. Thus, the bulk of the particulate Ba in such experiments was not truly intracellular but adsorbed on precipitated Fe hydroxides associated with the cell surface. A similar mechanism likely explains the high cellular Ba concentrations reported by previous investigators who utilized relatively high ratios of Fe to EDTA concentrations in the growth medium, resulting in Fe precipitation. On the basis of our results, it seems highly unlikely that intracellular uptake by living phytoplankton explains the vertical flux of Ba in oceanic waters. But the adsorption of Ba on Fe hydroxides that is seen in laboratory experiments must also occur in the oceans and contribute to Ba transport in the upper part of the water column. To be significant, however, such a mechanism would require that the particles that transport Ba out of the surface have a markedly lower Ba/Fe ratio than is measured in the average suspended material.

Sternberg, Erika; Tang, Degui; Ho, Tung-Yuan; Jeandel, Catherine; Morel, François M. M.

2005-06-01

113

Centrifugal precipitation chromatography  

PubMed Central

Centrifugal precipitation chromatography separates analytes according their solubility in ammonium sulfate (AS) solution and other precipitants. The separation column is made from a pair of long spiral channels partitioned with a semipermeable membrane. In a typical separation, concentrated ammonium sulfate is eluted through one channel while water is eluted through the other channel in the opposite direction. The countercurrent process forms an exponential AS concentration gradient through the water channel. Consequently, protein samples injected into the water channel is subjected to a steadily increasing AS concentration and at the critical AS concentration they are precipitated and deposited in the channel bed by the centrifugal force. Then the chromatographic separation is started by gradually reducing the AS concentration in the AS channel which lowers the AS gradient concentration in the water channel. This results in dissolution of deposited proteins which are again precipitated at an advanced critical point as they move through the channel. Consequently, proteins repeat precipitation and dissolution through a long channel and finally eluted out from the column in the order of their solubility in the AS solution. The present method has been successfully applied to a number of analytes including human serum proteins, recombinant ketosteroid isomerase, carotenoid cleavage enzymes, plasmid DNA, polysaccharide, polymerized pigments, PEG-protein conjugates, etc. The method is capable to single out the target species of proteins by affinity ligand or immunoaffinity separation.

Ito, Yoichiro; Lin, Qi

2009-01-01

114

Oxidation of alkaline earth sulfides to sulfates: Thermodynamic aspects  

Microsoft Academic Search

The emf of the galvanic cell, Pt, Ni + NiO\\/(CaO) ZrO2JMS + MSO4, Ir, Pt, where M is calcium, strontium, or barium, has been measured in the temperature range 850 to 1100 K. From these measurements the Gibbs' energy changes for the oxidation of sulfides of alkaline earth metals to their respective sulfates have been calculated. The results are compared

K. T. Jacob; G. N. K. Iyengar

1991-01-01

115

Oxidation of alkaline earth sulfides to sulfates: Thermodynamic aspects  

Microsoft Academic Search

The emf of the galvanic cell, Pt, Ni + NiO\\/(CaO) ZrO2\\/MS + MSO4, Ir, Pt, where M is calcium, strontium, or barium, has been measured in the temperature range 850 to 1100 K. From these measurements the Gibbs' energy changes for the oxidation of sulfides of alkaline earth metals to their respective sulfates have been calculated. The results are compared

K. T. Jacob; G. N. K. Iyengar

1982-01-01

116

Oxidation of alkaline earth sulfides to sulfates: Thermodynamic aspects  

Microsoft Academic Search

The emf of the galvanic cell, Pt, Ni + NiO\\/(CaO) ZrO2\\/MS + MSO4, Ir, Pt, where M is calcium, strontium, or barium, has been measured in the temperature range 850 to 1100 K. From these measurements\\u000a the Gibbs’ energy changes for the oxidation of sulfides of alkaline earth metals to their respective sulfates have been calculated.\\u000a The results are compared

K. T. Jacob; G. N. K. Iyengar

1982-01-01

117

Preparation of carboxymethyl cellulose sulfates and its application as anticoagulant and wound dressing.  

PubMed

Tissue engineering is aiming to build an artificial environment or biological scaffold material that imitates the living environment of cells in the body. In this work, carboxymethyl cellulose sulfates were prepared by reacting carboxymethyl cellulose with N(SO3Na)3 which was synthesized by sodium bisulfite and sodium nitrite in aqueous solution. The reaction conditions affected the degree of substitution (DS) were measured by the barium sulfate nephelometry method. And the anticoagulant activity of carboxymethyl cellulose sulfates with different DS, concentration and molecular weights were investigated by the activated partial thromboplastin time (APTT), thrombin time (TT) and prothrombin time (PT). In addition, the effect of carboxymethyl cellulose sulfates on wound healing had been evaluated by the rate of wound healing and the histological examinations. The results indicated that the introduction of sulfate groups into the carboxymethyl cellulose sulfates improved its anticoagulant activity, and the wound dressings treated with carboxymethyl cellulose sulfates obviously promoted wound healing. PMID:24582936

Fan, Lihong; Zhou, Xiaoyu; Wu, Penghui; Xie, Weiguo; Zheng, Hua; Tan, Wang; Liu, Shuhua; Li, Qingyuan

2014-05-01

118

40 CFR 721.10011 - Barium calcium manganese strontium oxide.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 false Barium calcium manganese strontium oxide. 721.10011...Chemical Substances § 721.10011 Barium calcium manganese strontium oxide. (a...chemical substance identified as barium calcium manganese strontium oxide (PMN...

2013-07-01

119

40 CFR 721.10011 - Barium calcium manganese strontium oxide.  

Code of Federal Regulations, 2010 CFR

...2009-07-01 2009-07-01 false Barium calcium manganese strontium oxide. ...Chemical Substances § 721.10011 Barium calcium manganese strontium oxide. ...The chemical substance identified as barium calcium manganese strontium...

2009-07-01

120

75 FR 20625 - Barium Chloride From China  

Federal Register 2010, 2011, 2012, 2013

...INTERNATIONAL TRADE COMMISSION [Investigation No. 731-TA-149 (Third Review)] Barium Chloride From China AGENCY: United States International Trade Commission. ACTION: Revised schedule for the subject...

2010-04-20

121

Barium in planktonic foraminifera  

NASA Astrophysics Data System (ADS)

Reconstructions of Ba distributions in ancient oceanic surface waters could provide new insight into paleoceanographic change. Calcite shells of planktonic foraminifera potentially provide a means of reconstructing such paleo-Ba distributions if lattice-bound Ba can be determined on shells recovered from deep-sea cores. Planktonic foraminifera shells from a series of cores were purified of non-lattice-bound Ba associated with organic or sedimentary phases by a combination of physical agitation, oxidative-reductive steps, acid leaches, and a novel alkaline-DTPA step to dissolve barite. A sequential dissolution of a large sample of cleaned shells of the planktonic foraminifer Globigerinoides conglobatus indicates homogeneous distribution of Ba in the shell material. Comparison of shells from sediments, sediment traps, and plankton tows indicates no significant differences in the Ba content of the purified shells. Cleaned samples of the planktonic foraminifera Globigerinoides sacculifera, G. ruber, G. conglobatus, Orbulina spp., and Globoquadrina dutertrei from the equatorial Pacific, North Atlantic, and Mediterranean Sea have Ba/Ca ratios between 0.6 and 1.0 ?mol/mol (0.8 to 1.4 ppm). Variation in foraminiferal Ba contents between the three basins is consistent with the trend in surface seawater Ba. The calculated distribution coefficient for Ba incorporation in these five species based on these data is 0.19 ± 0.05. Several species of the non-spinose planktonic foraminifera Globorotalia have Ba/Ca ratios ranging from 2 to 13 ?mol/mol; these high Ba contents might be explained by differences in the way these foraminifera precipitate their shells. A temporal record of Ba/Ca in samples of Globigerinoides and Orbulina from a core in the northwest Atlantic suggests that the Ba concentration of surface waters at this site has not changed by more than 20% over the last 14 kyr.

Lea, David W.; Boyle, Edward A.

1991-11-01

122

The L equals 6.7 quiet time barium shaped charge injection experiment 'Chachalaca'  

NASA Technical Reports Server (NTRS)

Near dawn on October 9, 1972, UT, a barium plasma injection experiment was carried out from Poker Flat, Alaska, during quiet magnetic conditions (Kp equals 1+). The visible plasma flux tube produced was more diffuse than the flux tubes in previous experiments, but it could be tracked for 30 min out to an altitude of 2.5 earth radii. The flux tube remained integral for about 20 min, when a single striation separated from the main streak. Comparisons of the observed flux tube orientation with theoretical field models show no significant deviations ascribable to field-aligned currents. Cross-field drift rates of the foot of the flux tube indicate an E field of approximately 7 mV/m at 200-km altitude. Although an attempt was made via a jet aircraft flight, barium ions were not detected in the southern conjugate region. No energetic particle precipitation phenomena were observed which could be ascribed to the barium plasma injection.

Wescott, E. M.; Stenbaek-Nielsen, H. C.; Davis, T. N.; Rieger, E. P.; Peek, H. M.; Bottoms, P. J.

1975-01-01

123

Chinese hamster ovary cell mutants defective in heparan sulfate biosynthesis  

SciTech Connect

The authors have isolated Chinese hamster ovary cell mutants defective in proteoglycan synthesis by radiographic screening for cells unable to incorporate TVSO4 into acid-precipitable material. Some mutants did not incorporate TVSO4 into acid-precipitable material, whereas others incorporated about 3-fold less radioactivity. HPLC anion exchange chromatographic analysis of radiolabelled glycosaminoglycans isolated from these mutants revealed many are defective in heparan sulfate biosynthesis. Mutants 803 and 677 do not synthesize heparan sulfate, although they produce chondroitin sulfate: strain 803 makes chondroitin sulfate normally, whereas 677 overaccumulates chondroitin sulfate by a factor of three. These mutants fall into the same complementation group, suggesting that the mutations are allelic. A second group of heparan sulfate biosynthetic mutants, consisting of cell lines 625, 668 and 679, produce undersulfated heparan sulfate and normal chondroitin sulfate. Treatment of the chains with nitrous acid should determine the position of the sulfate groups along the chain. These mutants may define a complementation group that is defective in the enzymes which modify the heparan sulfate chain. To increase the authors repertoire of heparan sulfate mutants, they are presently developing an in situ enzyme assay to screen colonies replica plated on filter discs for sulfotransferase defects.

Bame, K.J.; Kiser, C.S.; Esko, J.D.

1987-05-01

124

Redox processes in highly yttrium-doped barium titanate  

SciTech Connect

The changes of microstructure occurring during oxidation of the reduced form of yttrium-doped barium titanate (Ba{sub 1-x}Y{sub x}{sup ?}Ti{sub 1-x}{sup 4+}Ti{sub x}{sup 3+}O{sub 3}) have been studied. Samples were sintered under reduction conditions at P{sub O{sub 2}}=10{sup -4}Pa and oxidized by annealing at high temperatures (1150 and 1350 deg. C) in air. Depending on yttrium concentration, the oxidation of the reduced form of the yttrium-doped BaTiO{sub 3} caused precipitation of the phase Ba{sub 6}Ti{sub 17}O{sub 40} or the phases Ba{sub 6}Ti{sub 17}O{sub 40} and Y{sub 2}Ti{sub 2}O{sub 7}. The precipitates had well-defined orientational relationships with the perovskite matrix. Oxidation of the reduced form of doped barium titanate results in formation of the phase Ba{sub 1-x}Y{sub x}{sup ?}Ti{sub 1-x/4}{sup 4+}(V{sub Ti}{sup -}bar ){sub x/4}O{sub 3} responsible for increase in the resistance of outer grain layers, which lie between grain boundaries and grain.

Belous, Anatolii [Department of Solid State Chemistry, V.I. Vernadskii Institute of General and Inorganic Chemistry, Ukrainian National Academy of Sciences, Institute of General and Inorganic Chemistry, 32/42, Palladin Ave, 03680 Kyiv 142 (Ukraine); V'yunov, Oleg [Department of Solid State Chemistry, V.I. Vernadskii Institute of General and Inorganic Chemistry, Ukrainian National Academy of Sciences, Institute of General and Inorganic Chemistry, 32/42, Palladin Ave, 03680 Kyiv 142 (Ukraine)]. E-mail: vyunov@ionc.kar.net; Kovalenko, Leonid [Department of Solid State Chemistry, V.I. Vernadskii Institute of General and Inorganic Chemistry, Ukrainian National Academy of Sciences, Institute of General and Inorganic Chemistry, 32/42, Palladin Ave, 03680 Kyiv 142 (Ukraine); Makovec, Darko [Jozef Stefan Institute, Ljubljana (Slovenia)

2005-05-15

125

Novel Thermally Stable Poly (vinyl chloride) Composites for Sulfate Removal  

EPA Science Inventory

BaCO3 dispersed PVC composites were prepared through a polymer re-precipitation method. The composites were tested for sulfate removal using rapid small scale column test (RSSCT) and found to significantly reduce sulfate concentration. The method was extended to synthe...

126

Calcite/barium fluoride ultraviolet polarizing prism  

NASA Astrophysics Data System (ADS)

A calcite/barium fluoride polarizing prism gives improved ultraviolet transmittance compared with a calcite/calcite ultraviolet polarizing prism. Beam spatial distortion is transmitted because of variations in absorption (and path length) in the calcite half of the calcite/barium fluoride prism.

Wu, Fuquan; Li, Guohua; Huang, Jiayin; Yu, Dehong

1995-07-01

127

Barium granuloma of the transverse colon.  

PubMed Central

A case of barium sulphate granuloma of the transverse colon following gunshot wounds to the abdomen has been described. Scanning electron microscopy with electron probe microanalysis was used to confirm the presence of barium sulphate and the absence of lead or other elements related to the gunshot wounds. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4

McKee, P. H.; Cameron, C. H.

1978-01-01

128

REMOVAL OF BARIUM AND RADIUM FROM GROUNDWATER  

EPA Science Inventory

A research project was undertaken to investigate processes for removing barium and radium from drinking water. Special emphasis was placed on ion exchange processes that can be used without adding large concentrations of sodium to the water. The wastes from radium and barium remo...

129

Simple oxalate precursor route for the preparation of barium–strontium titanate: Ba 1? x Sr x TiO 3 powders  

Microsoft Academic Search

A simple one-step cation-exchange reaction between the stoichiometric solutions of ammonium titanyl oxalate (ATO) and barium hydroxide+strontium nitrate at room temperature (RT) is investigated successfully for the quantitative precipitation of barium–strontium titanyl oxalate (BSTO): Ba1?xSrxTiO(C2O4)2·4H2O (x=0.25) precursor powders with nearly theoretical yield (?99%). The pyrolysis of BSTO at 730 °C\\/4 h in air produced barium–strontium titanate (Ba1?xSrxTiO3; BST) powders. The

Y. B. Khollam; S. B. Deshpande; H. S. Potdar; S. V. Bhoraskar; S. R. Sainkar; S. K. Date

2005-01-01

130

Silage supports sulfate reduction in the treatment of metals- and sulfate-containing waste waters.  

PubMed

Silage was used as source of carbon and electrons for enrichment of silage-degrading and sulfate reducing bacteria (SRB) from boreal, acidic, metals-containing peat-bog samples and to support their use in batch and semi-batch systems in treatment of synthetic waste water. Sulfidogenic silage utilization resulted in a rapid decrease in lactate concentrations; concentrations of acetate, butyrate and propionate increased concomitantly. Synthetic waste water consisting of Mn, Mg and Fe (II) ions inhibited sulfate reduction at concentrations of 6 g/l, 8 g/l and 1 g/l respectively. During treatment, Mn and Mg ions remained in solution while Fe ions partially precipitated. Up to 87 mg sulfate was reduced per gram of silage. Sulfate reduction rates of 34, 22 and 6 mg/l/day were obtained at temperatures of 30, 20 and 9 °C respectively. In semi-batch reactors operated at low pH, the iron precipitation capacity was controlled by sulfate reduction rates and by partial loss of hydrogen sulfide to the gas phase. Passive reactor systems should, therefore, be operated at neutral pH. Metals tolerant, silage-fermenting (predominantly species belonging to genus Clostridium) and sulfate reducing bacteria (including a species similar to the psychrotolerant Desulfovibrio arcticus) were obtained from the peat bog samples. This work demonstrates that silage supports sulfate reduction and can be used as a low cost carbon and electron source for SRB in treatment of metals-containing waste water. PMID:20708212

Wakeman, Kathryn D; Erving, Leena; Riekkola-Vanhanen, Marja L; Puhakka, Jaakko A

2010-09-01

131

Glucosamine and Chondroitin Sulfate  

MedlinePLUS

... therapies and dietary supplements such as glucosamine and chondroitin sulfate in their search for relief. Glucosamine is ... Over-the-counter supplements come from animal sources. Chondroitin sulfate is another natural substance found in the ...

132

New barium ferrite particles: Spherical shape  

NASA Astrophysics Data System (ADS)

Pure and ZnTi-doped spherical barium ferrite particles were prepared using two different methods: semicoprecipitation and ultrasonic spray pyrolysis. The ultrasonic spray pyrolysis method was more effective in controlling particle shape. Particle size was in between 0.27 and 0.3 ?m. Coercivity and saturation magnetization were in the range of 1000 to 5000 Oe and 49 to 53 emu/g, respectively. Crystallization of amorphous Ba-Fe-O spherical precursors occurs at a lower temperature than Ba-Fe-Zn-Ti-O precursors. ?M measurement shows that magnetic interaction in spherical barium ferrite tape is weaker than hexagonal platelet barium ferrite.

Hong, Y. K.; Jung, H. S.

1999-04-01

133

On the fate of sulfate during hydrothermal circulation at mid-ocean ridges  

NASA Astrophysics Data System (ADS)

Reliable sulfate data are reported for seafloor hydrothermal vents at the Galapagos Rift at 86°W and the East Pacific Rise at 21°N. Making use of sulfate- 3He systematics, a loss of sulfate comparable to the river input is estimated. It is argued that the dominant chemical mechanism is reduction by iron, a conclusion based on strontium systematics and indicators of the water/rock ratios. Controls on the fate of sulfate in laboratory experiments are examined. It is proposed that the Mg/Ca ratio exerts a significant influence on the rate of sulfate reduction. Mixing of the hydrothermal endmember with seawater is considered. With slow mixing, alkaline earth sulfates should precipitate. Such precipitation accounts for the greater sulfate/heat ratio in the Galapagos fluids which are diluted extensively subsurface. The particular sulfate mineral formed is not known because of questions concerning the control of alkalinity.

McDuff, Russell E.; Edmond, John M.

1982-01-01

134

SEPARATION FACTORS IN FRACTIONAL CRYSTALLISATION OF PRECIPITATION OF THE LANTHANONS  

Microsoft Academic Search

Previous work on systems of two isomorphous salts and water is shown to ; lead to the postulate from which the logarithmic separation law, log(a\\/(a -- x)! ; = lambda log(b\\/(b -- y)!, was derived for separation of radium and barium. For ; lanthanon separation the law was found to represent both fractional ; crystallization and fractional precipitation. The value

R. J. Callow

1962-01-01

135

Photorefractive and Photochromic Effects in Barium Titanate.  

National Technical Information Service (NTIS)

Nominally undoped p-type Barium titanate was grown that exhibits interesting intensity dependent photorefractive and photochromic properties. When its photochromism is activated the absorption increases at the activating wavelength and there is a concurre...

C. Warde H. P. Jenssen J. Y. Chang M. H. Garrett T. M. Pollak

1992-01-01

136

Barium Isotopes in Single Presolar Grains  

NASA Technical Reports Server (NTRS)

Barium isotopic compositions of single presolar grains were measured by laser ablation laser resonant ionization mass spectrometry and the implications of the data for stellar processes are discussed. Additional information is contained in the original extended abstract.

Pellin, M. J.; Davis, A. M.; Savina, M. R.; Kashiv, Y.; Clayton, R. N.; Lewis, R. S.; Amari, S.

2001-01-01

137

Geophysical disturbance environment during the NASA/MPE barium release at 5 earth radii on September 21, 1971.  

NASA Technical Reports Server (NTRS)

The geophysical disturbance environment was quiet during the NASA/MPE barium release at 5 earth radii on September 21, 1971. At the time of the release, the magnetosphere was in the late recovery phase of a principal magnetic storm, the provisional Dst value was -13 gammas, and the local horizontal disturbance at Great Whale River was near zero. Riometer and other observations indicated low-level widespread precipitation of high-energy electrons at Great Whale River before, during, and after the release. Cloudy sky at this station prevented optical observation of aurora. No magnetic or ionospheric effects attributable to the barium release were detected at Great Whale River.

Davis, T. N.; Stanley, G. M.; Boyd, J. S.

1973-01-01

138

Gas-Liquid Precipitation of Water Dissolved Heavy Metal Ions Using Hydrogen Sulfide Gas  

Microsoft Academic Search

Precipitation of solids promoted by gas-liquid reactions is applied in many industrial processes such as the production of ammonium phosphate, ammonium sulphate, barium carbonate, calcium carbonate, calcium fluoride, ypsum (calcium sulphate), goethite, sodium bicarbonate, strontium carbonate and terephthalic acid. In ddition gas-liquid precipitation can be applied in gas cleaning, heavy metal removal and in biotechnology. Despite the importance of this

Mousa Al-Tarazi

2004-01-01

139

Hydrometallurgical process for recovering iron sulfate and zinc sulfate from baghouse dust  

DOEpatents

A process for recovering zinc/rich and iron-rich fractions from the baghouse dust that is generated in various metallurgical operations, especially in steel-making and other iron-making plants, comprises the steps of leaching the dust by hot concentrated sulfuric acid so as to generate dissolved zinc sulfate and a precipitate of iron sulfate, separating the precipitate from the acid by filtration and washing with a volatile liquid, such as methanol or acetone, and collecting the filtered acid and the washings into a filtrate fraction. The volatile liquid may be recovered distillation, and the zinc may be removed from the filtrate by alternative methods, one of which involves addition of a sufficient amount of water to precipitate hydrated zinc sulfate at 10.degree. C., separation of the precipitate from sulfuric acid by filtration, and evaporation of water to regenerate concentrated sulfuric acid. The recovery of iron may also be effected in alternative ways, one of which involves roasting the ferric sulfate to yield ferric oxide and sulfur trioxide, which can be reconverted to concentrated sulfuric acid by hydration. The overall process should not generate any significant waste stream.

Zaromb, Solomon (95706 William Dr., Hinsdale, IL 60521); Lawson, Daniel B. (925 Putnam Dr., Lockport, IL 60441)

1994-01-01

140

Hydrometallurgical process for recovering iron sulfate and zinc sulfate from baghouse dust  

DOEpatents

A process for recovering zinc-rich and iron-rich fractions from the baghouse dust that is generated in various metallurgical operations, especially in steel-making and other iron-making plants, comprises the steps of leaching the dust by hot concentrated sulfuric acid so as to generate dissolved zinc sulfate and a precipitate of iron sulfate, separating the precipitate from the acid by filtration and washing with a volatile liquid, such as methanol or acetone, and collecting the filtered acid and the washings into a filtrate fraction. The volatile liquid may be recovered by distillation, and the zinc may be removed from the filtrate by alternative methods, one of which involves addition of a sufficient amount of water to precipitate hydrated zinc sulfate at 10 C, separation of the precipitate from sulfuric acid by filtration, and evaporation of water to regenerate concentrated sulfuric acid. The recovery of iron may also be effected in alternative ways, one of which involves roasting the ferric sulfate to yield ferric oxide and sulfur trioxide, which can be reconverted to concentrated sulfuric acid by hydration. The overall process should not generate any significant waste stream. 1 figure.

Zaromb, S.; Lawson, D.B.

1994-02-15

141

Effects of barium chlorine treatment of uranium ore on /sup 222/Rn emanation and /sup 226/Ra leachability from mill tailings  

SciTech Connect

The purpose of this laboratory study was to investigate the effectiveness of barium chloride treatment of uranium ore on /sup 222/Rn emanation from mill tailings, /sup 226/Ra level in waste-water, and the leachability of radium from tailings. It has been shown that barium sulfate is an excellent carrier for radium and that barium sulfate crystals have high retention capacity for radon gas produced by radium trapped within the lattice. Ground uranium ore from a mine in Wyoming was mixed with water to form a 1:1 ratio before barium and potassium chlorides were added at concentrations of 0, 10, 25, 50, and 100 mg per liter of slurry. The ore was then subjected to a simulated mill process using sulfuric acid leaching. The liquid representing tailings pond water was separated and analyzed for /sup 226/Ra and the solid fraction, representing mill tailings, was tested for radon emanation and the leachability of radium by deionized water. This study suggests that barium treatment of uranium ore prior to sulfuric acid leaching could be effective in reducing radon emanation from tailings and also in reducing the /sup 226/Ra concentration of waste-water. Leachability of radium from treated tailings was markedly reduced.

Ibrahim, S.A.; Church, S.L.; Whicker, F.W.

1985-01-01

142

Assessment of barium sulphate formation and inhibition at surfaces with synchrotron X-ray diffraction (SXRD)  

NASA Astrophysics Data System (ADS)

The precipitation of barium sulphate from aqueous supersaturated solutions is a well-known problem in the oil industry often referred to as 'scaling'. The formation and growth of barite on surfaces during the oil extraction process can result in malfunctions within the oil facilities and serious damage to the equipment. The formation of barium sulphate at surfaces remains an important topic of research with the focus being on understanding the mechanisms of formation and means of control. In situ synchrotron X-ray diffraction (SXRD) was used to investigate the formation of barium sulphate on a stainless steel surface. The effect of Poly-phosphinocarboxylic acid (PPCA) and Diethylenetriamine-penta-methylenephosphonic acid (DETPMP) which are two commercial inhibitors for barium sulphate was examined. The in situ SXRD measurements allowed the identification of the crystal faces of the deposited barite in the absence and presence of the two inhibitors. The preferential effect of the inhibitors on some crystal planes is reported and the practical significance discussed.

Mavredaki, Eleftheria; Neville, Anne; Sorbie, Ken

2011-02-01

143

Assessment of Barium Sulphate Formation and Inhibition at Surfaces with Synchrotron X-ray Diffraction (SXRD)  

SciTech Connect

The precipitation of barium sulphate from aqueous supersaturated solutions is a well-known problem in the oil industry often referred to as 'scaling'. The formation and growth of barite on surfaces during the oil extraction process can result in malfunctions within the oil facilities and serious damage to the equipment. The formation of barium sulphate at surfaces remains an important topic of research with the focus being on understanding the mechanisms of formation and means of control. In situ synchrotron X-ray diffraction (SXRD) was used to investigate the formation of barium sulphate on a stainless steel surface. The effect of Poly-phosphinocarboxylic acid (PPCA) and Diethylenetriamine-penta-methylenephosphonic acid (DETPMP) which are two commercial inhibitors for barium sulphate was examined. The in situ SXRD measurements allowed the identification of the crystal faces of the deposited barite in the absence and presence of the two inhibitors. The preferential effect of the inhibitors on some crystal planes is reported and the practical significance discussed.

E Mavredaki; A Neville; K Sorbie

2011-12-31

144

An ultrafine barium ferrite powder of high coercivity from water-in-oil microemulsion  

NASA Astrophysics Data System (ADS)

An ultrafine barium ferrite powder of high coercivity and high saturation magnetization has been successfully prepared from an inverse water-in-oil microemulsion consisting of cyclohexane, NP5/NP9, and an aqueous solution of mixed ferric nitrate and barium nitrate. An ammonium hydroxide solution was used as the precipitant to obtain the hydroxide precursor of particle size in the range of 10-30 nm from the microemulsion. The resulting precursor is characterized using techniques such as thermogravimetric analysis (TGA), differential thermal analysis (DTA) and a FT-IR analyzer. It was then calcined at various temperatures ranging from 600 to 950°C in order to develop the designed barium ferrite phase. Phase development in the precursor at each calcination temperature was monitored using X-ray diffractometer and a 57Fe-Mössbauer spectrometer analyzer. The particle size and size distribution of the calcined powders were determined using light scattering technique, scanning electron microscope and a transmission electron microscope. A high purity barium ferrite was obtained when the precursor was calcined at 950°C for 4 h. It exhibits an intrinsic coercivity ( iHc) of 5639 Oe and a saturation magnetization ( Ms) of 69.7 emu/g, when characterized using a vibrating sample magnetometer (VSM).

Liu, Xiangyuan; Wang, John; Gan, Leong-Ming; Ng, Sen-Choon; Ding, Jun

145

An ultrafine barium ferrite powder of high coercivity from water-in-oil microemulsion  

NASA Astrophysics Data System (ADS)

An ultrafine barium ferrite powder of high coercivity and high saturation magnetization has been successfully prepared from an inverse water-in-oil microemulsion consisting of cyclohexane, NP5/NP9, and an aqueous solution of mixed ferric nitrate and barium nitrate. An ammonium hydroxide solution was used as the precipitant to obtain the hydroxide precursor of particle size in the range of 10-30 nm from the microemulsion. The resulting precursor is characterized using techniques such as thermogravimetric analysis (TGA), differential thermal analysis (DTA) and a FT-IR analyzer. It was then calcined at various temperatures ranging from 600 to 950 degC in order to develop the designed barium ferrite phase. Phase development in the precursor at each calcination temperature was monitored using X-ray diffractometer and a 57Fe-Mössbauer spectrometer analyzer. The particle size and size distribution of the calcined powders were determined using light scattering technique, scanning electron microscope and a transmission electron microscope. A high purity barium ferrite was obtained when the precursor was calcined at 950 degC for 4 h. It exhibits an intrinsic coercivity (iHc) of 5639 Oe and a saturation magnetization (Ms) of 69.7 emu/g, when characterized using a vibrating sample magnetometer (VSM).

Liu, Xiangyuan; Wang, John; Gan, Leong-Ming; Ng, Sen-Choon; Ding, Jun

1998-05-01

146

A co-precipitation technique to prepare BaTa 2O 6  

Microsoft Academic Search

A mixture of ammonium oxalate and ammonium hydroxide was used to co-precipitate barium and tantalum ions as barium oxalate and tantalum hydroxide under basic conditions. On calcination at 750°C, this precursor yielded BaTa2O6 (BT) ceramics. This is much lower temperature as compared to that prepared by traditional solid-state method (1000°C) as reported for the formation of BaTa2O6. Transmission electron microscope

S. C. Navale; Violet Samuel; A. B. Gaikwad; V. Ravi

2007-01-01

147

Observe Precipitation  

NSDL National Science Digital Library

Water that falls from the sky is called precipitation. Precipitation such as rain or snow can affect daily life; however, it is also a vital step in the water cycle, returning water from the atmosphere back to Earth's surface. This video segment shows three different types of precipitation: rain, hail, and snow. The segment is fifty-nine seconds in length. A background essay and list of discussion questions are also provided.

148

Barium Cycling During the Paleocene-Eocene Thermal Maximum: Evidence From Ba/Ca in Foraminifera  

NASA Astrophysics Data System (ADS)

The Paleocene-Eocene thermal maximum (PETM) around 55 Ma reflects short-term, rapid climate change during a period of intense greenhouse climate. This interval is characterized by a negative carbon isotopic shift, interpreted as a release of methane from seafloor gas hydrate reservoirs. This perturbation of the carbon cycle is accompanied by significantly greater rates of euhedral barite accumulation in deep sea sediment commonly believed to be a reflection of elevated primary productivity in surface waters. An interpretation of higher productivity during the PETM, however, is contrary to microfossil assemblage data which indicates a decrease in primary productivity. It has also been suggested that the increase in barite accumulation during the PETM may have been the result of an increase in dissolved barium concentrations in the deep ocean coeval with methane release. This supposition has support from the fact that modern gas hydrate reservoirs are surrounded by pore waters with dissolved barium concentrations considerably higher than that of seawater. This investigation utilizes the barium content of foraminifera as a proxy to reconstruct changes in the barium concentration of the ocean. At 55 Ma, Ba/Ca decreases between 25 to 28% in the planktic foraminifer \\textit{Morozovella velascoensis}, indicating a decrease in the barium concentration of the surface ocean. These results bolster the theory that there was increased biogenic barite precipitation during the PETM. Changes in surface water temperature and pH may have altered species assemblages such that celestite (SrSO4) precipitating organisms enriched in barium as BaSO4 (possibly acantharia) were dominant, modifying the barite precipitation pathways, which affected water column barite cycling. Ba/Ca and Cd/Ca measurements on benthic foraminifera show a positive correlation with Mn/Ca, indicating contamination of manganese oxide coatings. This contamination is in part due to the greater surface to volume ratio of benthic foraminifera, which are smaller than planktic species. Additionally, smaller quantities of benthics were available for analysis, which limited the intensity of pre-treatment to remove these coatings. After correcting for this coating contamination, no significant change in benthic Ba/Ca could be discerned through this interval. Taken together, the planktic and benthic foraminiferal Ba/Ca data suggests that enhanced biogenic barite accumulation during the PETM was primarily due to increased export from the surface waters.

Hall, J. M.; Zachos, J. C.; Turekian, K. K.

2004-12-01

149

New barium paste mixture for helical (slip-ring) CT evaluation of the esophagus.  

PubMed

Successful opacification of the lumen of the esophagus with cancer or paraesophageal diseases has not yet been fully achieved. Therefore, we have recently adopted a new method for complete and continuous opacification of the whole thoracic esophagus using our newly developed oral contrast agent with a helical (slip-ring) CT scanner. The agent consists of 3.6 (wt/vol)% carboxy-methyl cellulose sodium paste containing 2 (wt/vol)% barium sulfate. The results indicate that almost complete and continuous opacification of esophageal lumen was achieved. Our new method of esophageal CT is easy to perform and was well tolerated by patients, being therefore ideal for routine examinations. PMID:8797911

Noda, Y; Ogawa, Y; Nishioka, A; Inomata, T; Yoshida, S; Toki, T; Ogoshi, S; Ma, J

1996-01-01

150

Methods for sulfate removal in liquid-phase catalytic hydrothermal gasification of biomass  

DOEpatents

Processing of wet biomass feedstock by liquid-phase catalytic hydrothermal gasification must address catalyst fouling and poisoning. One solution can involve heating the wet biomass with a heating unit to a pre-treatment temperature sufficient for organic constituents in the feedstock to decompose, for precipitates of inorganic wastes to form, for preheating the wet feedstock in preparation for subsequent removal of soluble sulfate contaminants, or combinations thereof. Processing further includes reacting the soluble sulfate contaminants with cations present in the feedstock material to yield a sulfate-containing precipitate and separating the inorganic precipitates and/or the sulfate-containing precipitates out of the wet feedstock. Having removed much of the inorganic wastes and the sulfate contaminants that can cause poisoning and fouling, the wet biomass feedstock can be exposed to the heterogenous catalyst for gasification.

Elliott, Douglas C; Oyler, James

2013-12-17

151

Cytotoxicity of synthetic barium hydroxyapatite.  

PubMed

Barium hydroxyapatite (Ba10(PO4)6(OH)2, Ba-HAp) was synthesized by a wet method using Ba(OH)2.8H2O and (NH4)2HPO4 as starting materials. The Ba-HAp obtained had a Ba/P atomic ratio of 1.76 and contained CO3 groups. The Ba-HAp was sintered at 1073 K for 12 hours. The sintered Ba-HAp had a three point bending strength of 29 MPa and Young's modulus of 27 GPa. Cytotoxicity of the sintered bodies and particles was tested using L-cells. The sintered Ba-HAp showed no cytotoxicity, and the cells were closely in contact with the surfaces of sintered Ba-HAp. Morphological observation of the cell around the Ba-HAp particles also showed no cytotoxicity. However, cell growth was inhibited by Ca adsorption on the Ba-HAp particles. These results suggested that the Ba-HAp had no cytotoxicity and can be applied as a bioactive X-ray opaque material. PMID:9138651

Kikuchi, M; Yamazaki, A; Akao, M; Aoki, H

1996-01-01

152

Heparan Sulfate Proteoglycans  

PubMed Central

Heparan sulfate proteoglycans are found at the cell surface and in the extracellular matrix, where they interact with a plethora of ligands. Over the last decade, new insights have emerged regarding the mechanism and biological significance of these interactions. Here, we discuss changing views on the specificity of protein–heparan sulfate binding and the activity of HSPGs as receptors and coreceptors. Although few in number, heparan sulfate proteoglycans have profound effects at the cellular, tissue, and organismal level.

Sarrazin, Stephane; Lamanna, William C.; Esko, Jeffrey D.

2011-01-01

153

Crystallization of sodium sulfate salts in limestone  

Microsoft Academic Search

Crystallization pressure of salt crystals growing in confined pores is found to be the main cause for damage to stone and\\u000a masonry. In this work, the crystallization of sodium sulfate salts in Cordova Cream and Indiana limestones is investigated\\u000a using differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). The DSC experiments indicate that sodium\\u000a heptahydrate always precipitates prior to

Rosa M. Espinosa Marzal; George W. Scherer

2008-01-01

154

Precipitation Protocols  

NSDL National Science Digital Library

The purpose of this activity is to determine the amount of moisture input to the local environment by measuring rain and snowfall and to measure the pH of precipitation. To do so students use a rain gauge and a snowboard to measure the daily amount of precipitation. Special pH measuring techniques for precipitation are used to determine the pH of rain and melted snow. Intended outcomes are that students will understand that precipitation is measured in depth and this depth is assumed to apply to a large area, that precipitation has a pH that can vary, and that snow is an input of water to the surface just like rain and each snowfall is equivalent to some amount of rainfall. Supporting background materials for both student and teacher are included.

The GLOBE Program, UCAR (University Corporation for Atmospheric Research)

2003-08-01

155

Research on Thermionic Converters Using Barium and Cesium Vapor.  

National Technical Information Service (NTIS)

Investigations of thermionic converter operations were conducted utilizing a dual vapor system of barium and cesium. Barium and cesium vapors were introduced into two differently designed converters. The first converter developed an internal short circuit...

J. D. Long

1967-01-01

156

Drinking Water Criteria Document for Barium (Final Draft), December 1987.  

National Technical Information Service (NTIS)

The Office of Drinking Water, Environmental Protection Agency has prepared a Drinking Water Criteria Document on barium. The Criteria Document is an extensive review of the following topics: Physical chemical properties of Barium; Toxicokinetics and human...

1987-01-01

157

Drinking Water Criteria Document for Barium (Final Draft).  

National Technical Information Service (NTIS)

The Office of Drinking Water (ODW), U.S. Environmental Protection Agency has prepared a Drinking Water Criteria Document on barium. This Criteria Document is an extensive review of the following topics: Physical and chemical properties of barium; Toxicoki...

1985-01-01

158

Preparation and Properties of Barium Titanate Nanopowder\\/Epoxy Composites  

Microsoft Academic Search

This article is focused on the preparation of barium titanate nanopowder\\/epoxy composites and studying the effect of barium titanate nanopowder on improving mechanical and thermal characteristics of the epoxy polymer. Composites are prepared by dispersing barium titanate nanopowder in epoxy resin and, subsequently, cross-linking by using diamino diphenyl methane (DDM) curing agents. Synthesis of barium titanate nanopowder\\/epoxy composites is carried

J. Chandradass; Dong-sik Bae

2008-01-01

159

Roles of heparan sulfate sulfation in dentinogenesis.  

PubMed

Cell surface heparan sulfate (HS) is an essential regulator of cell signaling and development. HS traps signaling molecules, like Wnt in the glycosaminoglycan side chains of HS proteoglycans (HSPGs), and regulates their functions. Endosulfatases Sulf1 and Sulf2 are secreted at the cell surface to selectively remove 6-O-sulfate groups from HSPGs, thereby modifying the affinity of cell surface HSPGs for its ligands. This study provides molecular evidence for the functional roles of HSPG sulfation and desulfation in dentinogenesis. We show that odontogenic cells are highly sulfated on the cell surface and become desulfated during their differentiation to odontoblasts, which produce tooth dentin. Sulf1/Sulf2 double null mutant mice exhibit a thin dentin matrix and short roots combined with reduced expression of dentin sialophosphoprotein (Dspp) mRNA, encoding a dentin-specific extracellular matrix precursor protein, whereas single Sulf mutants do not show such defective phenotypes. In odontoblast cell lines, Dspp mRNA expression is potentiated by the activation of the Wnt canonical signaling pathway. In addition, pharmacological interference with HS sulfation promotes Dspp mRNA expression through activation of Wnt signaling. On the contrary, the silencing of Sulf suppresses the Wnt signaling pathway and subsequently Dspp mRNA expression. We also show that Wnt10a protein binds to cell surface HSPGs in odontoblasts, and interference with HS sulfation decreases the binding affinity of Wnt10a for HSPGs, which facilitates the binding of Wnt10a to its receptor and potentiates the Wnt signaling pathway, thereby up-regulating Dspp mRNA expression. These results demonstrate that Sulf-mediated desulfation of cellular HSPGs is an important modification that is critical for the activation of the Wnt signaling in odontoblasts and for production of the dentin matrix. PMID:22351753

Hayano, Satoru; Kurosaka, Hiroshi; Yanagita, Takeshi; Kalus, Ina; Milz, Fabian; Ishihara, Yoshihito; Islam, Md Nurul; Kawanabe, Noriaki; Saito, Masahiro; Kamioka, Hiroshi; Adachi, Taiji; Dierks, Thomas; Yamashiro, Takashi

2012-04-01

160

Roles of Heparan Sulfate Sulfation in Dentinogenesis*  

PubMed Central

Cell surface heparan sulfate (HS) is an essential regulator of cell signaling and development. HS traps signaling molecules, like Wnt in the glycosaminoglycan side chains of HS proteoglycans (HSPGs), and regulates their functions. Endosulfatases Sulf1 and Sulf2 are secreted at the cell surface to selectively remove 6-O-sulfate groups from HSPGs, thereby modifying the affinity of cell surface HSPGs for its ligands. This study provides molecular evidence for the functional roles of HSPG sulfation and desulfation in dentinogenesis. We show that odontogenic cells are highly sulfated on the cell surface and become desulfated during their differentiation to odontoblasts, which produce tooth dentin. Sulf1/Sulf2 double null mutant mice exhibit a thin dentin matrix and short roots combined with reduced expression of dentin sialophosphoprotein (Dspp) mRNA, encoding a dentin-specific extracellular matrix precursor protein, whereas single Sulf mutants do not show such defective phenotypes. In odontoblast cell lines, Dspp mRNA expression is potentiated by the activation of the Wnt canonical signaling pathway. In addition, pharmacological interference with HS sulfation promotes Dspp mRNA expression through activation of Wnt signaling. On the contrary, the silencing of Sulf suppresses the Wnt signaling pathway and subsequently Dspp mRNA expression. We also show that Wnt10a protein binds to cell surface HSPGs in odontoblasts, and interference with HS sulfation decreases the binding affinity of Wnt10a for HSPGs, which facilitates the binding of Wnt10a to its receptor and potentiates the Wnt signaling pathway, thereby up-regulating Dspp mRNA expression. These results demonstrate that Sulf-mediated desulfation of cellular HSPGs is an important modification that is critical for the activation of the Wnt signaling in odontoblasts and for production of the dentin matrix.

Hayano, Satoru; Kurosaka, Hiroshi; Yanagita, Takeshi; Kalus, Ina; Milz, Fabian; Ishihara, Yoshihito; Islam, Md. Nurul; Kawanabe, Noriaki; Saito, Masahiro; Kamioka, Hiroshi; Adachi, Taiji; Dierks, Thomas; Yamashiro, Takashi

2012-01-01

161

An assessment of the redistribution of Barium during diagenesis of Marcellus Shale  

NASA Astrophysics Data System (ADS)

Produced water from the hydrofracturing of Marcellus Shale have been reported to contain barium at concentrations >4000 ppm (Gregory et al, 2011). Understanding the reactions responsible for the leaching of Ba into produced water is important for improving the economic viability of gas extraction and to mitigate environmental concerns. Core samples of Marcellus Shale from New York and Pennsylvania were shown to contain Ba in the range of 400-2200 ?g/g. In some of these samples, barite (BaSO4) grains are shown to be partially replaced by pyrite (massive and framboidal varieties) suggesting that Ba is remobilized in the zone of sulfate reduction sometime after sedimentation. Sequential extraction experiments show Ba being released into buffered acetic acid (carbonate fraction), aqua regia (sulfide fraction), and hydrofluoric acid (silicate fraction) extractions despite ~50% of the barium remaining undissolved as barite. Laser ablation ICP-MS showed negligible concentrations of Ba in calcite veins and elevated concentrations in areas of the shale that are predominantly clay + organics. These results suggest that some of the Ba is associated with the clay fraction of the shale (e.g., sorbed to clay surfaces as a result of the anoxic dissolution of barite). These results may inform future strategies for mitigating the release of barium into produced water.

Renock, D.; Symcox, C.; Lanids, J. D.; Sharma, M.

2012-12-01

162

Synthesis of barium titanate nanopowder using polymeric precursor method  

Microsoft Academic Search

Barium titanate powder was prepared by a polymerized complex method based on the Pechini type reaction route, where barium and titanium ions were polymerized in mixed solution of citric acid, ethylene glycol, to form a transparent resin, which was used as a precursor. Barium titanate powder was formed by heat treating the polymeric precursor in air at 500–900°C. The thermal

V. Vinothini; Paramanand Singh; M. Balasubramanian

2006-01-01

163

Conditions of preparation of calcium and barium hexaboride powders  

Microsoft Academic Search

1.A study was made of the conditions of preparation of barium and calcium hexaborides by the boroncarbide and borothermic techniques and by the reaction of barium carbonate with boron in a vacuum.2.It was established that a barium hexaboride with a composition approaching theoretical can be obtained by the borothermic techniques at a temperature of 1600°C from a charge with a

T. I. Serebryakova; É. V. Marek

1969-01-01

164

Barium iodide single-crystal scintillator detectors  

SciTech Connect

We find that the high-Z crystal Barium Iodide is readily growable by the Bridgman growth technique and is less prone to crack compared to Lanthanum Halides. We have grown Barium Iodide crystals: undoped, doped with Ce{sup 3+}, and doped with Eu{sup 2+}. Radioluminescence spectra and time-resolved decay were measured. BaI{sub 2}(Eu) exhibits luminescence from both Eu{sup 2+} at 420 nm ({approx}450 ns decay), and a broad band at 550 nm ({approx}3 {micro}s decay) that we assign to a trapped exciton. The 550 nm luminescence decreases relative to the Eu{sup 2+} luminescence when the Barium Iodide is zone refined prior to crystal growth. We also describe the performance of BaI{sub 2}(Eu) crystals in experimental scintillator detectors.

Cherepy, N

2007-07-30

165

Improved spectrophotometric analysis of barium styphnate  

SciTech Connect

A spectrophotometric procedure to determine the purity of barium styphnate monohydrate based upon the absorbance of the styphnate ion at 326 and 413.3 nm has been developed. The purity is determined by comparing the absorbance of the styphnate ion in barium styphnate and in styphnic acid. Our investigation has shown that the molar absorptivity and lambda maxima of the styphnate ion are quite pH dependent; therefore, the pH is buffered to 6.8 to 7.0 with ammonium acetate. Under these conditions the molar absorptivity is 1.6 x 10/sup 4/ L/mol-cm. Analyses following the procedure in the Navy specification WS13444A using water were found to give low molar absorptivities (1.3 x 10/sup 4/ L/mol-cm) for the styphnic acid calibration resulting in erroneous values for barium styphnate purity.

Brown, N E; Blasi, J A

1983-01-01

166

Automotive sulfate emission data.  

PubMed Central

This paper discusses automotive sulfate emission results obtained by the Office of Mobile Source Air Pollution Control of EPA, General Motors, Ford, Chrysler, and Esso. This work has been directed towards obtaining sulfate emission factors for cars with and without catalyst. While the EPA and Chrysler investigations have found significant sulfate formation in noncatalyst cars, GM, Ford, and Esso have found only trace levels from noncatalyst cars. All of these investigators agree that much higher quantities of sulfate are emitted from catalyst cars. The work done to date shows pelleted catalysts to have much lower sulfate emissions over the low speed-EPA Federal Test Procedures than monolith catalysts. This is probably due to temporary storage of sulfates on the catalyst due to chemical interaction with the alumina pellets. The sulfate compounds are, to a large degree, emitted later under higher speed conditions which result in higher catalyst temperatures which decompose the alumina salt. Future work will be directed towards further elucidation of this storage mechanism as well as determining in detail how factors such as air injection rate and catalyst location affect sulfate emissions.

Somers, J H

1975-01-01

167

Mine water treatment with limestone for sulfate removal.  

PubMed

Limestone can be an option for sulfate sorption, particularly from neutral mine drainages because calcium ions on the solid surface can bind sulfate ions. This work investigated sulfate removal from mine waters through sorption on limestone. Continuous stirred-tank experiments reduced the sulfate concentration from 588.0mg/L to 87.0mg/L at a 210-min residence time. Batch equilibrium tests showed that sulfate loading on limestone can be described by the Langmuir isotherm, with a maximum loading of 23.7mg/g. Fixed-bed experiments were utilized to produce breakthrough curves at different bed depths. The Bed Depth Service Time (BDST) model was applied, and it indicated sulfate loadings of up to 20.0gSO(4)(2-)/L-bed as the flow rate increased from 1 to 10mL/min. Thomas, Yoon-Nelson and dose-response models, predicted a maximum particle loading of 19mg/g. Infrared spectrometry indicated the presence of sulfate ions on the limestone surface. Sulfate sorption on limestone seems to be an alternative to treating mine waters with sulfate concentrations below the 1200-2000mg/L range, where lime precipitation is not effective. In addition, this approach does not require alkaline pH values, as in the ettringite process. PMID:22541641

Silva, Adarlêne M; Lima, Rosa M F; Leão, Versiane A

2012-06-30

168

Precipitation Recycling  

NASA Technical Reports Server (NTRS)

The water cycle regulates and reflects natural variability in climate at the regional and global scales. Large-scale human activities that involve changes in land cover, such as tropical deforestation, are likely to modify climate through changes in the water cycle. In order to understand, and hopefully be able to predict, the extent of these potential global and regional changes, we need first to understand how the water cycle works. In the past, most of the research in hydrology focused on the land branch of the water cycle, with little attention given to the atmospheric branch. The study of precipitation recycling which is defined as the contribution of local evaporation to local precipitation, aims at understanding hydrologic processes in the atmospheric branch of the water cycle. Simply stated, any study on precipitation recycling is about how the atmospheric branch of the water cycle works, namely, what happens to water vapor molecules after they evaporate from the surface, and where will they precipitate?

Eltahir, Elfatih A. B.; Bras, Rafael L.

1996-01-01

169

Roles of Pt and BaO in the Sulfation of Pt/BaO/Al2O3 Lean NOx Trap Materials: Sulfur K-edge XANES and Pt Llll XAFS Studies  

SciTech Connect

The roles of barium oxide and platinum during the sulfation of Pt-BaO/Al2O3 lean NOx trap catalysts were investigated by S K edge XANES (X-ray absorption near-edge spectroscopy) and Pt LIII XAFS (X-ray absorption fine structure). All of the samples studied [Al2O3, BaO(x; x = 8 or 20 wt %)/Al2O3, Pt(2.5 wt %)/Al2O3, and Pt(2 wt %)-BaO(x; x = 8 or 20 wt %)/Al2O3] were pre-sulfated prior to the X-ray absorption measurements. It was found that barium oxide itself has the ability to directly form barium sulfate even in the absence of Pt and gas-phase oxygen. In the platinum-containing samples, the presence of Pt-O species plays an important role in the formation of sulfate species. For the case of the BaO(8)/Al2O3 sample, where the barium coverage is about 0.26 ML, both baria and alumina phases are available for sulfation. S XANES results show that barium sulfates are formed preferentially over aluminum sulfates. When oxygen is absent from the gas phase, the sulfation route that involves Pt-O is eliminated after the initially present Pt-O species are completely consumed. In this case, formation of sulfates is suppressed unless barium oxide is also present. Pt LIII XAFS results show that the first coordination sphere around the Pt atoms in the Pt particles is dependent upon the gas mixture used during the sulfation process. Sulfation under reducing environments (e.g., SO2/H2) leads to formation of Pt-S bonds, while oxidizing conditions (e.g., SO2/O2) continue to show the presence of Pt-O bonds. In addition, a reducing environment was found to cause Pt sintering in greater extent than an oxidizing one. This result explains why samples sulfated under reducing conditions had lower NOx uptakes than those sulfated under oxidizing conditions. Therefore, our results provide needed information for the development of optimum practical operation conditions (e.g., sulfation or desulfation) for lean NOx trap catalysts that minimize deactivation by sulfur.

Kim,D.; Kwak, J.; Szanyi, J.; Cho, S.; Peden, C.

2008-01-01

170

Synthesis of thin films of barium titanate and barium strontium titanate nanotubes on titanium substrates  

Microsoft Academic Search

In this study, well-ordered nanotubes of titania were fabricated by anodic oxidation of pure titanium foils in HF aqueous solution. Fe-SEM images indicate the average nanotubes diameter is ?100 nm with a thickness of about 200 nm. Nanotube arrays of barium titanate and barium strontium titanate were synthesized under hydrothermal condition at 200 °C taking above-oxidized titania nanotubes as templates.

Jianling Zhao; Xiaohui Wang; Renzheng Chen; Longtu Li

2005-01-01

171

Electric Tuning of Ferromagnetic Resonances in Hexagonal-Barium-Ferrite\\/Barium-Strontium-Titanate Heterostructures  

Microsoft Academic Search

This letter reports the first demonstration of a monolithic heterostructure with a large electric tuning of the ferromagnetic resonance (FMR) at millimeter-wave frequencies. The structure is composed of a barium-strontium-titanate (BST) film and two thin platinum electrodes, all grown on a barium ferrite slab with in-plane uniaxial anisotropy. The electric tuning of the FMR responses around 60 GHz was obtained

Young-Yeal Song; Jaydip Das; Pavol Krivosik; Hyung-Kee Seo; Mingzhong Wu

2010-01-01

172

Microstructure and magnetism in barium strontium titanate (BSTO)–barium hexaferrite (BaM) multilayers  

Microsoft Academic Search

High quality multilayers of barium ferrite (BaM) and barium strontium titanate (BSTO) were grown in optimized conditions on thermally oxidized Si(100) and Al2O3 substrates using magnetron sputtering. As-grown films were amorphous and different annealing procedures were explored to stabilize crystalline phases. BSTO and BaM phases were identified using X-ray diffraction and cross-sectional scanning electron micrographs showed sharp interfaces between BSTO

N. A. Frey; R. Heindl; S. Srinath; H. Srikanth; Nancy J Dudney

2005-01-01

173

Sputtered barium titanate and barium strontium titanate films for capacitor applications  

Microsoft Academic Search

Thin barium titanate and barium strontium titanate films are being developed as dielectric film for use in dc-dc converters. Thin BaTiO3 (BT) and (BaSr)TiO3 (BST) film capacitor devices were fabricated using RF magnetron sputtering techniques. The typical dielectric constant of these film capacitors was in the range of 300 to 690. These film capacitors had dissipation factors between 0.2% to

Bang-Hung Tsao; Susan Heidger; Joseph A. Weimer

2000-01-01

174

Low Temperature Thermal Expansion of Barium Ferrite.  

National Technical Information Service (NTIS)

The linear thermal expansion of polycrystalline barium ferrite, BaFe12O19, was measured from 76 to 293 K both parallel and perpendicular to the magnetization direction. An anisotropy of about 15-20% was observed. The results match well the available data ...

A. F. Clark W. M. Haynes V. A. Deason R. J. Trapani

1975-01-01

175

STABILIZED BARIUM TITANATE CERAMICS FOR CAPACITOR DIELECTRICS  

Microsoft Academic Search

The effects of additions of LaâOâ and LaâOâ--; 3TiOâ on the electronic properties of barium titanate were investigated. ; It was found that small additions of the components markedly increase the ; lifetime of the material subjected to d-c fields of 50 v per mil at 200 l ; C. (auth);

J. B. MacChesney; P. K. Gallagher; F. V. DiMarcello

1963-01-01

176

Beta-Barium Borate Optical Parametric Oscillator.  

National Technical Information Service (NTIS)

A Beta-Barium Borate Optical Parametric Oscillator (BBO OPO) has been constructed and shipped to the Army laboratory at White Sands. This OPO is a truly continuously tunable source with a very large spectral coverage. It is pumped at the third harmonic of...

C. L. Tang

1991-01-01

177

Incorporation of /sup 35/S-sulfate and /sup 3/H-glucosamine into heparan and chondroitin sulfates during the cell cycle of B16-F10 cells  

SciTech Connect

Changes in glycosaminoglycan composition occurring during the cell cycle were determined in B16-F10 cells sorted flow cytometrically with respect to DNA content. Incorporation of /sup 35/S-sulfate into heparan sulfate and chondroitin sulfate of unsorted and G1,S, and G2 +M sorted cells was determined following chondroitinase ABC or nitrous acid treatment; the incorporation into surface material was measured as the difference between the radioactivity of control and trypsin-treated cells. Incorporation of /sup 35/S-sulfate and /sup 3/H-glucosamine into cetyl pyridinium chloride (CPC)-precipitable material was characterized before and after chondroitinase or nitrous acid treatment by Sephadex G50 chromatography. Long-term (48 h) and short-term (1 h) labeling studies demonstrate that (a) the amount of total cellular chondroitin sulfate is greater than that of heparan sulfate, with larger amounts of unsulfated heparan than chondroitin being present; (b) the rate of turnover of heparan sulfate is greater than that of chondroitin sulfate; (c) greatest short-term incorporation of 3H-glucosamine into CPC-precipitable material occurs during S phase; and (d) the rate of turnover of both heparan sulfate and chondroitin sulfate is decreased in S phase relative to G1 and G2 + M.

Blair, O.C.; Sartorelli, A.C.

1984-05-01

178

Removal of sulfate from high-strength wastewater by crystallisation.  

PubMed

Sulfate causes considerable problems in anaerobic digesters, related to generation of sulfides, loss of electrons (and hence methane), and contamination of gas streams. Removal of sulfides is generally expensive, and still results in methane losses. In this paper, we evaluate the use of precipitation for low-cost sulfate removal, in highly contaminated streams (>1 gS L(-1)). The main precipitate assessed is calcium sulfate (gypsum), though the formation of complex precipitates such as jarosite and ettringite to remove residual sulfate is also evaluated. The four main concerns in contaminated wastewater are:- high solubility, caused by high ion activity and ion pairing; slow kinetics; inhibition of nucleation; and poisoning of crystals by impurities, rendering product unsuitable for reuse as seed. These concerns were addressed through batch experiments on a landfill wastewater with a similar composition to other sulfate rich industrial wastewaters (high levels of organic and inorganic contaminants). Crystallisation rates were rapid and comparable to what is observed by others for pure solutions (2-5 h). The kinetics of crystallisation showed a 2nd order dependence on supersaturation, which have implications for crystalliser design, as discussed in the paper. No spontaneous nucleation was observed (seed was required). Seed poisoning did not occur, and product crystals were as effective as pure seed. Solubility was increased by an order of magnitude compared to a pure solution (2.6x10(-3) M2 vs. 0.22x10(-3) M2). As evaluated using equilibrium modelling, this was caused equally by non-specific ion activity, and specific ion pairing. Jarosite and ettringite could not be formed at reasonable pH and temperature levels. Given the lack of complex precipitates, and relatively high solubility, gypsum crystallisation cannot practically be used to remove sulfate to very low levels, and gas-sulfide treatment will likely still be required. It can however, be used for low-cost bulk removal of sulfate. PMID:19059623

Tait, Stephan; Clarke, William P; Keller, Jurg; Batstone, Damien J

2009-02-01

179

Uranium Immobilization by Sulfate-reducing Biofilms  

SciTech Connect

Hexavalent uranium [U(VI)] was immobilized using biofilms of the sulfate-reducing bacterium (SRB) Desulfovibrio desulfuricans G20. The biofilms were grown in flat-plate continuous-flow reactors using lactate as the electron donor and sulfate as the electron acceptor. U(VI) was continuously fed into the reactor for 32 weeks at a concentration of 126 íM. During this time, the soluble U(VI) was removed (between 88 and 96% of feed) from solution and immobilized in the biofilms. The dynamics of U immobilization in the sulfate-reducing biofilms were quantified by estimating: (1) microbial activity in the SRB biofilm, defined as the hydrogen sulfide (H2S) production rate and estimated from the H2S concentration profiles measured using microelectrodes across the biofilms; (2) concentration of dissolved U in the solution; and (3) the mass of U precipitated in the biofilm. Results suggest that U was immobilized in the biofilms as a result of two processes: (1) enzymatically and (2) chemically, by reacting with microbially generated H2S. Visual inspection showed that the dissolved sulfide species reacted with U(VI) to produce a black precipitate. Synchrotron-based U L3-edge X-ray absorption near edge structure (XANES) spectroscopy analysis of U precipitated abiotically by sodium sulfide indicated that U(VI) had been reduced to U(IV). Selected-area electron diffraction pattern and crystallographic analysis of transmission electron microscope lattice-fringe images confirmed the structure of precipitated U as being that of uraninite.

Beyenal, Haluk; Sani, Rajesh K.; Peyton, Brent M.; Dohnalkova, Alice; Amonette, James E.; Lewandowski, Zbigniew

2004-04-01

180

Thermoresponsive hydrogels based on poly( N-isopropylacrylamide)\\/chondroitin sulfate  

Microsoft Academic Search

A fast, thermoresponsive hydrogel composed of poly(N-isopropylacrylamide) (PNIPAm) and chondroitin sulfate (ChS) was synthesized using precipitation polymerization. ChS was introduced to increase the water absorption of the PNIPAm hydrogel, and the precipitation polymerization method was used to induce a porous network morphology to enhance the thermal response of the hydrogel. PNIPAm\\/ChS hydrogels (15:7.5wt.%) underwent a very fast deswelling, within a

Justin M. Varghese; Yahya A. Ismail; Chang Kee Lee; Kwang Min Shin; Min Kyoon Shin; Sun I. Kim; Insuk So; Seon Jeong Kim

2008-01-01

181

Precipitation chemistry at Turrialba, Costa Rica  

SciTech Connect

Bulk precipitation samples were collected weekly at Turrialba, Costa Rica, from March 1979 through March 1981. The samples were analyzed for pH, conductivity, major cations and anions, nutrient N and P species and 12 trace metals. Precipitation was found to contain low levels of minerals, nutrients and acidity. During the spring period of low rainfall and increased agricultural activity, high levels of chemical constituents were observed. Low rainfall rates at this time resulted in relatively low depositions. The volume weighted pH over the 2 year period was 5.34 and ranged from 4.81 to 6.35. On the basis of equivalent ratios, excess sulfate was determined to be the principal acidic anion. Excess sulfate comprised 85% of the total sulfate and may result from long-range transport, biogenic emission, or sulfurous emission from nearby volcanic fumaroles. 27 references, 5 figures, 3 tables.

Hendry, C.D.; Berish, C.W.; Edgerton, E.S.

1984-11-01

182

Hydrazine Sulfate (PDQ)  

MedlinePLUS

... English | En español Search NCI Home Cancer Topics Clinical Trials Cancer Statistics Research & Funding News About NCI ... of Cancer Terms NCI Drug Dictionary Search for Clinical Trials NCI Publications Español Overview Hydrazine sulfate is ...

183

The removal of hydrogen sulfide from gas streams using an aqueous metal sulfate absorbent  

Microsoft Academic Search

The desulfurization of gas streams using aqueous iron(II)sulfate (Fe(II)SO4), zinc sulfate (ZnSO4) and copper sulfate (CuSO4) solutions as washing liquor is studied theoretically and experimentally. The desulfurization is accomplished by a precipitation reaction that occurs when sulfide ions and metal ions are brought into contact with each other. A thermodynamic study has been used to determine a theoretical operating window,

H. ter Maat; J. A. Hogendoorn; G. F. Versteeg

2005-01-01

184

Distinguishing solid bitumens formed by thermochemical sulfate reduction and thermal chemical alteration  

Microsoft Academic Search

Insoluble solid bitumens are organic residues that can form by the thermal chemical alteration (TCA) or thermochemical sulfate reduction (TSR) of migrated petroleum. TCA may actually encompass several low temperature processes, such as biodegradation and asphaltene precipitation, followed by thermal alteration. TSR is an abiotic redox reaction where petroleum is oxidized by sulfate. It is difficult to distinguish solid bitumens

Simon R. Kelemen; Clifford C. Walters; Peter J. Kwiatek; Mobae Afeworki; Michael Sansone; Howard Freund; Robert J. Pottorf; Hans G. Machel; Tongwei Zhang; Geoffrey S. Ellis; Yongchun Tang; Kenneth E. Peters

2008-01-01

185

Selective total encapsulation of the sulfate anion by neutral nano-jars.  

PubMed

Nano-sized toroidal copper(II)-hydroxide/pyrazolate assemblies, lined by H-bond donors on the inside and hydrophobic on the outside, selectively extract sulfate from mixtures with nitrate or perchlorate. Tetrabutylammonium "lids" seal the "nano-jars" and render the encapsulated sulfate anion completely buried and inaccessible, so that it is not precipitated by Ba(2+) ions. PMID:22669223

Fernando, Isurika R; Surmann, Stuart A; Urech, Alexander A; Poulsen, Alexander M; Mezei, Gellert

2012-07-11

186

Precipitation Matters  

ERIC Educational Resources Information Center

Although weather, including its role in the water cycle, is included in most elementary science programs, any further examination of raindrops and snowflakes is rare. Together rain and snow make up most of the precipitation that replenishes Earth's life-sustaining fresh water supply. When viewed individually, raindrops and snowflakes are quite…

McDuffie, Thomas

2007-01-01

187

Effect of antiscalants on precipitation of an RO concentrate: metals precipitated and particle characteristics for several water compositions.  

PubMed

Inland brackish water reverse osmosis (RO) is economically and technically limited by the large volume of salty waste (concentrate) produced. The use of a controlled precipitation step, followed by solid/liquid separation (filtration), has emerged as a promising side-stream treatment process to treat reverse osmosis concentrate and increase overall system recovery. The addition of antiscalants to the RO feed prevents precipitation within the membrane system but might have a deleterious effect on a concentrate treatment process that uses precipitation to remove problematic precipitates. The effects of antiscalant type and concentration on salt precipitation and precipitate particle morphology were evaluated for several water compositions. The primary precipitate for the synthetic brackish waters tested was calcium carbonate; the presence of magnesium, sulfate, minor ions, and antiscalant compounds affected the amount of calcium precipitated, as well as the phases of calcium carbonate formed during precipitation. Addition of antiscalant decreased calcium precipitation but increased incorporation of magnesium and sulfate into precipitating calcium carbonate. Antiscalants prevented the growth of nucleated precipitates, resulting in the formation of small (100-200 nm diameter) particles, as well as larger (6-10 microm) particles. Elemental analysis revealed changes in composition and calcium carbonate polymorph with antiscalant addition and antiscalant type. Results indicate that the presence of antiscalants does reduce the extent of calcium precipitation and can worsen subsequent filtration performance. PMID:20172582

Greenlee, Lauren F; Testa, Fabrice; Lawler, Desmond F; Freeman, Benny D; Moulin, Philippe

2010-04-01

188

Stoichiometry : PrecipYield (3 Variations)  

NSDL National Science Digital Library

In a laboratory experiment to determine accurately the amount of barium in solution, aqueous sulfuric acid was added to the solution to precipitate barium sulfate, which was then filtered and weighed. In this experiment it is MOST important that ...

189

Effects of Stratospheric Sulfate Geoengineering on Food Supply in China  

Microsoft Academic Search

Possible food supply change is one of the most important concerns in the discussion of stratospheric geoengineering. In regions with high population density, climate changes such as precipitation reduction spurred by stratospheric sulfate injection may cause drought, reduce crop yield, and affect the food supply for hundreds of millions of people. Therefore, as part of the research into the benefits

L. Xia; A. Robock

2010-01-01

190

Physico-chemical transformations of sulfated compounds during the leaching of highly sulfated cemented wastes  

SciTech Connect

Cementation of sulfated evaporator concentrates leads to highly sulfated low level wastes, (ca. 25% w/w sodium sulfate solution as mix water), which exhibit the presence of U-phase, a sodium-bearing calcium monosulfphoaluminate-like phase. During the leaching of simulated highly sulfated OPC/BFS cements, cured at room temperature and containing U-phase, sodium sulfate, and ettringite, physico-chemical transformations have been pointed out (transformation of U-phase into ettringite). Samples having the same chemical composition, but cured at high temperature (maximal temperature during curing: 120 C), do not contain ettringite initially, but secondary ettringite is formed during leaching. XRD spectra point out the existence of precipitation fronts (or of phase formation fronts) varying linearly versus the square root of time. The analysis of leaching solutions has provided complementary data used in a code, the aim of which is to assess cement degradation, based on coupling between transport by diffusion and chemical reactions (DIFFUZON code). The U-phase-ettringite transformation is confirmed.

Lovera, P.; Bescop, P. le; Adenot, F. [CEA Centre de`Etudes de Saclay, Gif/Yvette (France)] [CEA Centre de`Etudes de Saclay, Gif/Yvette (France); Li, G. [CEA Centre d`Etudes de Saclay, Gif/Yvette (France)] [CEA Centre d`Etudes de Saclay, Gif/Yvette (France); [Ecole Normale Superieure de Cachan (France). Lab. de Mecanique et de Technologie; Tanaka, Y. [Japan Nuclear Fuel Ltd., Tokyo (Japan)] [Japan Nuclear Fuel Ltd., Tokyo (Japan); Owaki, E. [Taisei Corp., Yokohama (Japan). Technology Research Center] [Taisei Corp., Yokohama (Japan). Technology Research Center

1997-10-01

191

Precipitation Matters  

NSDL National Science Digital Library

Although weather, including its role in the water cycle, is included in most elementary science programs, any further examination of raindrops and snowflakes is rare. Together rain and snow make up most of the precipitation that replenishes Earth's life-sustaining fresh water supply. When viewed individually, raindrops and snowflakes are quite varied either in size or shape and provide surprising hints about the atmospheric conditions in which they formed.

Mcduffie, Thomas

2007-07-01

192

Measuring Precipitation  

NSDL National Science Digital Library

Students will design, build and then test a rain gauge to measure precipitation. By sharing their results, they will recognize the need for standardization and precision in scientific tools. All background information, student worksheets and images/photographs/data are included in these downloadable sections: Teacherâs Guide, Student Capture Sheet and PowerPoint Presentation. This activity uses the 5E instructional model and is part of the Survivor Earth series of one-hour lessons.

193

Barium uptake and adsorption in diatoms  

Microsoft Academic Search

Using trace metal-defined culture conditions, we measured the cellular barium concentration in cultures of the diatom Thalassiosira weissflogii. In cultures with low Fe concentration, at a typical surface seawater Ba concentration of 35 to 40 nmol\\/L, the cellular Ba was 0.5 ?mol\\/mol P (?0.04 ?g\\/g dw), much below all previously published values for phytoplankton. When the Fe concentration in the

Erika Sternberg; Degui Tang; Tung-Yuan Ho; Catherine Jeandel; François M. M. Morel

2005-01-01

194

Leachability of barium-radium sulphate sludges  

Microsoft Academic Search

This paper presents results from the first phase of a research program designed to examine the leachability of radium-226 from barium-radium sulphate sludges. Batch leaching tests were performed. Results showed that liquid:solid contact time was relatively unimportant; radium in the sludge was stable in the presence of deionized water with a slight increase in the amount leached per gram of

P. M. Huck; B. Anderson

1982-01-01

195

Formation of barium-tantalum oxynitrides  

Microsoft Academic Search

Oxynitride powders suitable for sintering to form dielectric ABO3-type perovskites have been prepared by nitriding barium carbonate and tantalum oxide. Both heat treatment in air and reaction in flowing ammonia yield isostructural oxynitride phases, but the amount and electronic state of the oxynitrides depend on the nitriding gas conditions. A red-brown oxynitride of high nitrogen content is described as Ba2Ta2O3N2

A. Hellwig; A. Hendry

1994-01-01

196

Sulfate Transport and Release in Technogenic Soil Substrates: Experiments and Numerical Modeling  

NASA Astrophysics Data System (ADS)

In Berlin and many other cities technogenic soil substrates from World War II and building and construction debris in general play an important role for soil formation and solute transport in the vadose zone. The largest debris landfill in Berlin is the Teufelsberg. Sulfate release from the landfill poses threats for groundwater quality. The scope of this study is to determine the processes controlling sulfate release from soils containing rubble. Column leaching experiments were conducted to analyze sulfate mobilization from Teufelsberg topsoil material. Flow interruptions of one and seven days were introduced. Sulfate release was modeled using a geochemical simulation tool (HP1). The model considered water flux, solute transport and precipitation/dissolution with first order kinetics. Sulfate release increased after flow interruptions, although bromide breakthrough indicated physical equilibrium of transport processes. The model was applicable for qualitative description of our experimental results. The estimated equilibrium concentrations of sulfate were one to two orders of magnitude smaller than expected according to the equilibrium constant of gypsum. It is assumed that the mobilization of sulfate from calcite/gypsum co-precipitates determines the sulfate concentrations in the soil solution of the studied soils. If Sulfate release and transport from soils containing debris is modeled with literature values, sulfate concentrations will be overestimated by one to two orders of magnitude.

Schonsky, H.; Peters, A.; Lang, F.; Mekiffer, B.; Wessolek, G.

2012-04-01

197

Sulfate attack expansion mechanisms  

SciTech Connect

A specially constructed stress cell was used to measure the stress generated in thin-walled Portland cement mortar cylinders caused by external sulfate attack. The effects of sulfate concentration of the storage solution and C{sub 3}A content of the cement were studied. Changes in mineralogical composition and pore size distribution were investigated by X-ray diffraction and mercury intrusion porosimetry, respectively. Damage is due to the formation of ettringite in small pores (10–50 nm) which generates stresses up to 8 MPa exceeding the tensile strength of the binder matrix. Higher sulfate concentrations and C{sub 3}A contents result in higher stresses. The results can be understood in terms of the effect of crystal surface energy and size on supersaturation and crystal growth pressure.

Müllauer, Wolfram, E-mail: wolf_m@gmx.at; Beddoe, Robin E.; Heinz, Detlef

2013-10-15

198

The Use of Seaweed and Sugarcane Bagasse for the Biological Treatment of Metal-contaminated Waters Under Sulfate-reducing Conditions  

Microsoft Academic Search

When wetlands reach maximum treatment capacity to remove heavy metals, removal can still take place through precipitation as sulfide because of the biological reduction of sulfate. To achieve this goal, anaerobic conditions must be attained, a sulfate source must exist, and an adequate substrate for sulfate-reducing bacteria (SRB) is also required. In the present work, two ligneous-cellulosic materials, a brown

Márcia Monteiro Machado Gonçalves; Luiz Antonio Oliveira de Mello; Antonio Carlos Augusto da Costa

2008-01-01

199

Isolation of glycosaminoglycans (heparan sulfate) from glomerular basement membranes  

PubMed Central

Glycosaminoglycans were isolated from purified fractions of glomerular basement membranes and partially characterized by chemical analysis and cellulose acetate electrophoresis. Basement membranes were prepared by detergent treatment of rat glomeruli and subjected to digestion with papain and Pronase. Glycosaminoglycans were isolated from the digests by precipitation with cetyl pyridinium chloride and ethanol. Results of cellulose acetate electrophoresis of the isolated glycosaminoglycan fraction revealed the presence of one major and one minor spot. The major spot was identified as heparan sulfate because it comigrated with the heparan sulfate standard and was sensitive to heparinase and to nitrous acid oxidation but insensitive to chondroitinase ABC and to testicular or leech hyaluronidase. The minor spot was tentatively identified as hyaluronic acid based on its migratory behavior and sensitivity to leech and testicular hyaluronidase. The chemical composition of the isolated glycosaminoglycan was typical of that of heparan sulfate (high carbazole/orcinol ratio, high sulfate content, absence of galactosamine). The data support and confirm the cytochemical data obtained previously [Kanwar, Y. S. & Farquhar, M. G. (1979) Proc. Natl. Acad. Sci. USA 76, 1303-1307] demonstrating that heparan sulfate is the only sulfated glycosaminoglycan detectable in the glomerular basement membrane. The present results suggest that in addition to sulfated glycosaminoglycan some nonsulfated glycosaminoglycan (hyaluronic acid) may also be present in the glomerular basement membrane. Images

Kanwar, Yashpal S.; Farquhar, Marilyn Gist

1979-01-01

200

Hydrothermal crystallization of barium titanate: Mechanisms of nucleation and growth  

NASA Astrophysics Data System (ADS)

Barium titanate is synthesized under hydrothermal conditions by the reaction of a variety of titania precursors with aqueous solutions of Ba(OH)sb2 at 80sp°C. Particles processed at relatively low concentrations of Ba(OH)sb2 are micro-sized and highly aggregated, but increasing concentrations cause the particle size to decrease, resulting in nanometer-sized and fairly monodispersed particles. The change in particle size and morphology at various Ba(OH)sb2 concentrations is controlled by the dissolution of titania and precipitation of BaTiOsb3. In order to explain the origin of "raspberry-like" BaTiOsb3 particles and the generation of hierarchically ordered BaTiOsb3 aggregate comprised of primary, crystalline particles, which exhibit an unusually high degree of crystallographic alignment, the role of colloidal stability and therefore controlled aggregation of precipitated primary particles is taken into account. Formation of SrTiOsb3 on BaTiOsb3 particles reveal that two different morphologies for the growing SrTiOsb3 exists and that the form taken by SrTiOsb3 depends on the degree of supersaturation. In concentrated solutions, homogeneous nucleation and aggregation growth occur. In dilute solutions, heterogeneous nucleation and continuous growth of SrTiOsb3 promote epitaxial growth. BaTiOsb3 particles prepared by the alkoxide (Ti(OCsb3Hsb7)sb4) -hydroxide (Ba(OH)sb2) route under hydrothermal conditions show that secondary processed such as aggregation and recrystallization are important to control the particle size and morphology. Particle clustering, and rearrangement of nanometer-sized BaTiOsb3 particles, and particulate uniformity can then be explained in terms of solution reactions and colloidal behavior.

Chun, Chang-Min

201

Sulfate could mediate the therapeutic effect of glucosamine sulfate  

Microsoft Academic Search

Glucosamine sulfate is a controversial osteoarthritis remedy that is presumed to stimulate articular cartilage glycosaminoglycan synthesis by increasing glucosamine concentrations in the joint space. However, this is not plausible because even large oral doses of the product have no effect on serum glucosamine concentrations. We propose instead that sulfate could mediate the clinical benefit attributed to this treatment. Sulfate is

L. John Hoffer; Ludmila N. Kaplan; Mazen J. Hamadeh; Ariadna C. Grigoriu; Murray Baron

2001-01-01

202

Binding and Leakage of Barium in Alginate Microbeads  

PubMed Central

Microbeads of alginate cross-linked with Ca2+ and/or Ba2+ are popular matrices in cell-based therapy. The aim of this study was to quantify the binding of barium in alginate microbeads and its leakage under in vitro and accumulation under in vivo conditions. Low concentrations of barium (1 mM) in combination with calcium (50 mM) and high concentrations of barium (20 mM) in gelling solutions were used for preparation of microbeads made of high-G and high-M alginates. High-G microbeads accumulated barium from gelling solution and contained higher concentrations of divalent ions for both low- and high-Ba exposure compared to high-G microbeads exposed to calcium solely and to high-M microbeads for all gelling conditions. Although most of the unbound divalent ions were removed during the wash and culture steps, leakage of barium was still detected during storage. Barium accumulation in blood and femur bone of mice implanted with high-G beads was found to be dose-dependent. Estimated barium leakage relevant to transplantation to diabetic patients with islets in alginate microbeads showed that the leakage was 2.5 times lower than the tolerable intake value given by WHO for high-G microbeads made using low barium concentration. The similar estimate gave 1.5 times higher than is the tolerable intake value for the high-G microbeads made using high barium concentration. In order to reduce the risk of barium accumulation that may be of safety concern, the microbeads made of high-G alginate gelled with a combination of calcium and low concentration of barium ions is recommended for islet transplantation.

M?rch, Yrr A.; Qi, Meirigeng; Gundersen, Per Ole M.; Formo, Kjetil; Lacik, Igor; Skjak-Braek, Gudmund; Oberholzer, Jose; Strand, Berit L.

2013-01-01

203

Calcium sulfate fouling -- Precipitation or particulate: A proposed composite model  

SciTech Connect

Though it is of great importance, the majority of predictive models tend not to incorporate water chemistry in their formulations. The ionic diffusion model which was developed for CaCO{sub 3}, is based purely on crystallization, and is one of the few models that incorporates water chemistry. This model does not provide satisfactory predictions for CaSO{sub 4} fouling. In this article, a new model is proposed for CaSO{sub 4} fouling which takes into account the effect of both crystallization and particulate fouling and is capable of predicting the fouling resistance during the cleaning cycle as well as the fouling cycle. A removal term is incorporated into the model, as the occurrence of particulate fouling for CaSO{sub 4} tends to weaken its crystalline structure and makes it more prone than CaCO{sub 3} to removal. Properties of the electrolyte were evaluated using MINTEQA2 computer code, which is approved by the US Environmental Protection Agency. In this model, particulate fouling is estimated using the physical mechanism for particle transport and adherence, crystallization is estimated by ionic diffusion, and the removal term is approximated using hydrodynamics of flow and deposit properties. The inclusion of both crystallization and removal terms incorporates the effects of both water chemistry and hydrodynamics of the flow and provides a relationship which not only can predict fouling but also can predict dissolution, by change of water quality and/or stopping the operation, or removal by shear stress. The proposed model was assessed using published experimental data. The results indicate that this model provides good prediction. The experimental results, though limited in number, suggest that crystallization is not the main or only mechanism contributing to CaSO{sub 4} fouling. Particulate fouling seems to be a major contributor.

Sheikholeslami, R.

2000-06-01

204

Aluminum Sulfate 18 Hydrate  

ERIC Educational Resources Information Center

A chemical laboratory information profile (CLIP) of the chemical, aluminum sulfate 18 hydrate, is presented. The profile lists physical and harmful properties, exposure limits, reactivity risks, and symptoms of major exposure for the benefit of teachers and students using the chemical in the laboratory.

Young, Jay A.

2004-01-01

205

Experimental study of acid-sulfate alteration of basalt and implications for sulfate deposits on Mars  

NASA Astrophysics Data System (ADS)

Acid-sulfate alteration of basalt by SO2-bearing volcanic vapors has been proposed as one possible origin for sulfate-rich deposits on Mars. To better define mineralogical signatures of acid-sulfate alteration, laboratory experiments were performed to investigate alteration pathways and geochemical processes during reaction of basalt with sulfuric acid. Pyroclastic cinders composed of phenocrysts including plagioclase, olivine, and augite embedded in glass were reacted with sulfuric acid at 145 °C for up to 137 days at a range of fluid : rock ratios. During the experiments, the phenocrysts reacted rapidly to form secondary products, while the glass was unreactive. Major products included amorphous silica, anhydrite, and Fe-rich natroalunite, along with minor iron oxides/oxyhydroxides (probably hematite) and trace levels of other sulfates. At the lowest fluid : rock ratio, hexahydrite and an unidentified Fe-silicate phase also occurred as major products. Reaction-path models indicated that formation of the products required both slow dissolution of glass and kinetic inhibitions to precipitation of a number of minerals including phyllosilicates and other aluminosilicates as well as Al- and Fe-oxides/oxyhydroxides. Similar models performed for Martian basalt compositions predict that the initial stages of acid-sulfate alteration of pyroclastic deposits on Mars should result in formation of amorphous silica, anhydrite, Fe-bearing natroalunite, and kieserite, along with relict basaltic glass. In addition, analysis of the experimental products indicates that Fe-bearing natroalunite produces a Mössbauer spectrum closely resembling that of jarosite, suggesting that it should be considered an alternative to the component in sulfate-rich bedrocks at Meridiani Planum that has previously been identified as jarosite.

McCollom, Thomas M.; Robbins, Mark; Moskowitz, Bruce; Berquó, Thelma S.; Jöns, Niels; Hynek, Brian M.

2013-04-01

206

Structural features of sulfated chitosans  

Microsoft Academic Search

Chitosan sulfates prepared by different methods were analyzed by 13C NMR spectroscopy. It was shown that the sulfation conditions of chitosan essentially affect the position and degree of substitution with sulfate in derivatives of chitosan. Sulfated products obtained under homogeneous conditions are characterized by more heterogeneity and they have to be considered as copolymers of chitosan 6-O-monosulfate and 3,6-O-disulfate, whereas

A. Gamzazade; A. Sklyar; S. Nasibov; I. Sushkov; A. Shashkov; Yu. Knirel

1997-01-01

207

21 CFR 524.1484e - Neomycin sulfate and polymyxin B sulfate ophthalmic solution.  

Code of Federal Regulations, 2010 CFR

... false Neomycin sulfate and polymyxin B sulfate ophthalmic solution...1484e Neomycin sulfate and polymyxin B sulfate ophthalmic solution...base), and 10,000 Units of polymyxin B sulfate. (b) Sponsor....

2009-04-01

208

21 CFR 524.1484e - Neomycin sulfate and polymyxin B sulfate ophthalmic solution.  

Code of Federal Regulations, 2010 CFR

... false Neomycin sulfate and polymyxin B sulfate ophthalmic solution...1484e Neomycin sulfate and polymyxin B sulfate ophthalmic solution...base), and 10,000 Units of polymyxin B sulfate. (b) Sponsor....

2010-04-01

209

The first barium tin(II) bromide fluoride  

NASA Astrophysics Data System (ADS)

In an effort to prepare barium tin(II) bromide fluorides for the first time, possibly similar to the chloride fluorides obtained earlier in our laboratory, precipitation reactions were carried out by mixing aqueous solutions of SnF2 and of BaBr2.2H2O. In contrast with the chloride fluoride system, a single powdered phase was obtained throughout the SnF2 - BaBr2 system, with the yield being maximum at X ? 0.25, where X is the molar fraction of barium bromide in the reaction mixture. Phase identification with the JCPDS database failed to produce a match, confirming that a new phase had been produced. The exact chemical composition of the new compound has not been obtained yet. Based on the X value for the maximum yield, the Sn/Ba ratio is likely to be 3/1 or 2/1. The Mössbauer spectrum at ambient conditions shows that bonding to tin(II) is covalent, therefore with the tin lone pair being stereoactive. The Mössbauer parameters ( ? = 3.68 mm/s, ? = 0.99 mm/s) are similar to those of SnBrF and of Sn2BrF5, thereby showing that tin is bonded to both fluorine and bromine. The larger isomer shift and lower quadrupole splitting than in tin(II) fluorides show that the stereoactivity of the tin lone pair is lower than in the fluorides. The Mössbauer parameters fit well the linear correlation of the quadrupole splitting versus the isomer shift" that has been shown to be present in other series of tin(II) compounds. The linear decrease on this correlation shows that the contribution of non-spherical orbitals ( p and d) to the lone pair is a much larger contributor to the quadrupole splitting than lattice distortions. The structure is likely made of Ba2+ cations and tin(II) fluoride bromide polyatomic anions, with covalent bonding withinthe anions.

Dénès, Georges; Merazig, Hocine; Muntasar, Abdualhafeed; Porterfield, Robyn

2014-04-01

210

The first barium tin(II) bromide fluoride  

NASA Astrophysics Data System (ADS)

In an effort to prepare barium tin(II) bromide fluorides for the first time, possibly similar to the chloride fluorides obtained earlier in our laboratory, precipitation reactions were carried out by mixing aqueous solutions of SnF2 and of BaBr2.2H2O. In contrast with the chloride fluoride system, a single powdered phase was obtained throughout the SnF2 - BaBr2 system, with the yield being maximum at X ? 0.25, where X is the molar fraction of barium bromide in the reaction mixture. Phase identification with the JCPDS database failed to produce a match, confirming that a new phase had been produced. The exact chemical composition of the new compound has not been obtained yet. Based on the X value for the maximum yield, the Sn/Ba ratio is likely to be 3/1 or 2/1. The Mössbauer spectrum at ambient conditions shows that bonding to tin(II) is covalent, therefore with the tin lone pair being stereoactive. The Mössbauer parameters (? = 3.68 mm/s, ? = 0.99 mm/s) are similar to those of SnBrF and of Sn2BrF5, thereby showing that tin is bonded to both fluorine and bromine. The larger isomer shift and lower quadrupole splitting than in tin(II) fluorides show that the stereoactivity of the tin lone pair is lower than in the fluorides. The Mössbauer parameters fit well the linear correlation of the quadrupole splitting versus the isomer shift" that has been shown to be present in other series of tin(II) compounds. The linear decrease on this correlation shows that the contribution of non-spherical orbitals (p and d) to the lone pair is a much larger contributor to the quadrupole splitting than lattice distortions. The structure is likely made of Ba2+ cations and tin(II) fluoride bromide polyatomic anions, with covalent bonding withinthe anions.

Dénès, Georges; Merazig, Hocine; Muntasar, Abdualhafeed; Porterfield, Robyn

2014-03-01

211

Impact of glacial/interglacial changes in water column geochemistry on the diagenetic cycling of barium in Black Sea sediments  

NASA Astrophysics Data System (ADS)

Changes in depositional conditions and redox environment over time affect biogeochemical processes in the seabed and in this way control the variable and selective preservation, alteration and formation of various sediment constituents and attributes - including particulate organic matter, mineral assemblages and magnetic properties. As many of these solid-phase compounds are used as paleo-environmental tracers or stratigraphic tools an assessment of diagenetic influences on the sedimentary record is crucial for accurate environmental reconstructions. We present an integrated approach of pore-water and solid-phase geochemistry as well as transport reaction modeling for sediments of the Black Sea to assess the biogeochemical history of these deposits with particular emphasis on post-depositional redistribution of barium as a consequence of changes in water column geochemistry and redox (Henkel et al., 2012). High-resolution sedimentary records of major and minor elements (Al, Ba, Ca, Sr, Ti), total organic carbon (TOC), and profiles of pore-water constituents (SO42-, CH4, Ca2+, Ba2+, Mg2+, alkalinity) were obtained for two gravity cores (core 755, 501 m water depth and core 214, 1686 m water depth) from the northwestern Black Sea. The records were examined in order to gain insight into the cycling of Ba in anoxic marine sediments characterized by a shallow sulfate-methane transition (SMT) as well as the applicability of barite as a primary productivity proxy in such a setting. The Ba records are strongly overprinted by diagenetic barite (BaSO4) remobilization and precipitation; authigenic Ba enrichments were found at both sites at and slightly above the current SMT. Transport reaction modeling was applied to simulate the migration of the SMT during the changing geochemical conditions after the Holocene seawater intrusion into the Black Sea. Based on this, sediment intervals affected by diagenetic Ba redistribution were identified. Results reveal that the intense overprint of Ba and Baxs (Ba excess above detrital average) strongly limits its correlation to primary productivity. These findings have implications for other modern and ancient anoxic basins, such as sections covering the Oceanic Anoxic Events for which Ba is frequently used as a primary productivity indicator. Our study also demonstrates the limitations concerning the use of Baxs as a tracer for downward migrations of the SMT: due to high sedimentation rates at the investigated sites, diagenetic barite fronts are buried below the SMT within a relatively short period. Thus, "relict" barite fronts would only be preserved for a few thousands of years, if at all. References Henkel, S., Mogollón, J.M., Nöthen, K., Franke, C., Bogus, K., Robin, E., Bahr, A., Blumenberg, M., Pape, T., Seifert, R., März, C., de Lange, G.J., Kasten, S. (2012) Diagenetic barium cycling in Black Sea sediments - A case study for anoxic marine environments. Geochimica et Cosmochimica Acta, 88, 88-105.

Kasten, S.; Henkel, S.; Mogollón, J. M.; Nöthen, K.; Franke, C.; Bogus, K.; Robin, E.; Bahr, A.; Blumenberg, M.; Pape, T.; Seifert, R.; Marz, C.; De Lange, G. J.

2012-12-01

212

Minerals Yearbook, 1992: Sodium Sulfate.  

National Technical Information Service (NTIS)

Three companies produced natural sodium sulfate from a total of three plants in California, Texas, and Utah. The domestic natural sodium sulfate industry supplied about one-half of the total output of U.S. sodium sulfate. Because of the location of these ...

1993-01-01

213

BARIUM IN TEETH AS INDICATOR OF BODY BURDEN  

EPA Science Inventory

A study was conducted to determine the biological availability of naturally occurring barium in a municipal drinking water by the analysis of barium in deciduous teeth of children. The grade school children of two Illinois towns were chosen for the study. The towns were chosen ba...

214

Toward a more environmentally benign synthesis of doped barium titanate  

Microsoft Academic Search

Barium titanate is one of the most thoroughly studied members of the perovskite family due to its prominent place in the electroceramic industry. To be used as a capacitor at room temperature, a high-dielectric constant is needed which is achieved through doping. The focus of this research was to develop a more environmentally benign alternative to the doping of barium

Anne Marteel-Parrish; Samantha DeCarlo; Danielle Harlan; Jonathan Martin; Heather Sheridan

2008-01-01

215

Large electrostrictive actuation of barium titanate single crystals  

Microsoft Academic Search

An experimental investigation of the electromechanical behavior of single crystals of the ferroelectric perovskite barium titanate is presented. An experimental setup has been designed to investigate large strain actuation in single crystal ferroelectrics subjected to combined electrical and mechanical loading. Experiments have been performed on initially single domain crystals of barium titanate with (100) and (001) orientation at compressive stresses

E. Burcsu; G. Ravichandran; K. Bhattacharya

2004-01-01

216

Composition and structure measurements in an ionospheric barium cloud  

NASA Astrophysics Data System (ADS)

A 48 kg barium payload was launched from Eglin Air Force Base, Florida on 12 December 1980 at 2311 GMT and detonated at 183.7 km. At 2342:50.25 GMT, a second rocket, instrumented with an ion mass spectrometer and pulsed plasma probes, was fired to traverse the barium cloud. Composition, ion density, and structure measurements were acquired up to 241.2 km in both the natural and disturbed ionosphere. The rocket penetrated the barium cloud between 147 and 184 km. In addition to the Ba+, Ba++ produced by H Lyman alpha ionization, and Ca+, an impurity in the barium were detected in the cloud. A peak barium ion concentration of about 6,000,000 ions cu cm was measured at 161 km where the ionospheric NO+ and O2+ ions were essentially eliminated by large recombination loss. The bottom side of the barium cloud had a relatively smooth structure while the top side showed significant density fluctuations. The first experimental evidence of a theoretically predicted E region 'image cloud' was found in the form of an enhanced NO+ layer just below the barium cloud. Unexplained wave-like density variations in O+, NO+, and O2(+) also were seen above the barium cloud to 195 km. A quantitative estimate of the outgassing water vapor concentrations near the payload's surface was made using the fast change transfer rate coefficient for O+ + H2O yields H2O+ + O that created the observed water vapor ions.

Narcisi, R.; Tracinski, E.; Federico, G.; Wlodyka, L.; Bench, P.

1981-12-01

217

Removal of barium and radium from groundwater. Environmental research brief  

Microsoft Academic Search

A research project was undertaken to investigate processes for removing barium and radium from drinking water. Special emphasis was placed on ion exchange processes that can be used without adding large concentrations of sodium to the water. The wastes from radium and barium removal processes were also characterized, and processes suitable for treatment of ion-exchange brines were evaluated. The report

V. L. Snoeyink; C. C. Chambers; C. K. Schmidt; R. F. Manner; A. G. Myers

1987-01-01

218

Barium strontium titanate powder obtained by polymeric precursor method  

Microsoft Academic Search

Pure barium strontium titanate powder, with Ba\\/Sr ratio of 80\\/20 was prepared by the polymeric precursor method (also called Pechini process). The powder was obtained after a calcination at 800 °C for 8 h and characterized by XRD, IR, BET and SEM. The requirements to avoid barium carbonate as a secondary phase are presented and discussed in detail.

A. Ries; A. Z. Simões; M. Cilense; M. A. Zaghete; J. A. Varela

2003-01-01

219

Barium strontium titanate powder obtained by polymeric precursor method  

SciTech Connect

Pure barium strontium titanate powder, with Ba/Sr ratio of 80/20 was prepared by the polymeric precursor method (also called Pechini process). The powder was obtained after a calcination at 800 deg. C for 8 h and characterized by XRD, IR, BET and SEM. The requirements to avoid barium carbonate as a secondary phase are presented and discussed in detail.

Ries, A.; Simoes, A.Z.; Cilense, M.; Zaghete, M.A.; Varela, J.A

2003-03-15

220

21 CFR 184.1307 - Ferric sulfate.  

Code of Federal Regulations, 2010 CFR

...Ferric sulfate. (a) Ferric sulfate (iron (III) sulfate, Fe2 (SO4 )3 ...substance that may be prepared by oxidizing iron (II) sulfate or by treating ferric oxide or ferric hydroxide with sulfuric acid. (b) The...

2009-04-01

221

21 CFR 184.1307 - Ferric sulfate.  

Code of Federal Regulations, 2013 CFR

...Ferric sulfate. (a) Ferric sulfate (iron (III) sulfate, Fe2 (SO4 )3 ...substance that may be prepared by oxidizing iron (II) sulfate or by treating ferric oxide or ferric hydroxide with sulfuric acid. (b) The...

2013-04-01

222

21 CFR 184.1307 - Ferric sulfate.  

Code of Federal Regulations, 2010 CFR

...Ferric sulfate. (a) Ferric sulfate (iron (III) sulfate, Fe2 (SO4 )3 ...substance that may be prepared by oxidizing iron (II) sulfate or by treating ferric oxide or ferric hydroxide with sulfuric acid. (b) The...

2010-01-01

223

Crystallization of calcium sulfate dihydrate and calcium sulfite hemihydrate from synthetic flue gas desulfurization solutions: Final report  

SciTech Connect

The precipitation of calcium sulfate dihydrate (CaSO/sub 4/.2H/sub 2/O) and calcium sulfite hemihydrate (CaSO/sub 3/.1/2H/sub 2/O) from high, up to 240,000 mg/L, total dissolved solids (TDS) solutions was studied at 50/sup 0/C. The solutions were selected to cover a range of solution compositions of magnesium, calcium, sodium, chloride, and sulfate. Precipitation rates along with crystal habit and size changes were measured to determine the effects of these dissolved species as compared to dilute solution conditions. Calcium sulfate dihydrate (gypsum) precipitation rate was accelerated in the high TDS solutions, especially those containing chloride ion. Alternatively, calcium sulfite hemihydrate precipitation rate was found to be faster in high sulfate ion containing solutions. Sodium ion appears to produce gypsum crystals more columnar in habit while solutions containing high amounts of calcium produced very lamellar gypsum crystals. Solutions containing magnesium produced acicular gypsum crystals. Calcium sulfite hemihydrate solids precipitated from solutions containing high sulfate concentrations were rod shaped and globular as compared to the lamellar calcium sulfite hemihydrate crystals precipitated from high chloride and dilute solution liquors. Calcium sulfate-calcium sulfite solid solutions were characterized using infrared spectroscopy. Ion scavenging of Na, Mg, and Cl by gypsum and calcium sulfite solids precipitated from these high TDS solutions was also investigated. 10 refs., 21 figs., 13 tabs.

Trofe, T.W.; Fishman, V.A.; Meserole, F.B.

1986-10-01

224

Current-voltage characteristics of barium polymethacrylate  

SciTech Connect

In this paper current-voltage characteristics of Barium Polymethacrylate (BaPMA) in the form of Al-BaPMA-Al structures are studied. The currents are measured in the voltage range 10 V-1 kV. At low voltages an ohmic relation is observed and at higher voltages the Poole-Frenkel mechanism is proposed. The mechanism of conduction has been explained on the basis of different current-voltage and current-temperature curves. The activation energy values calculated using Arrhenius relation fall in the range 0.25-2 eV, suggesting a sequence of trapping levels.

Chohan, M.H. (Lab. for Electrical Characterization of Polymers, Dept. of Electronics, Quaid-i-Azam Univ., Islamabad (PK)); Zulfiqar, M.; Sapra, Z.H.; Husain, R.; Zulfiqar, S. (Dept. of Chemistry, Quaid-i-Azam Univ., Islamabad (PK))

1992-06-30

225

Dielectric properties of barium titanate supramolecular nanocomposites  

NASA Astrophysics Data System (ADS)

Nanostructured dielectric composites can be obtained by dispersing high permittivity fillers, barium titanate (BTO) nanocubes, within a supramolecular framework. Thin films of BTO supramolecular nanocomposites exhibit a dielectric permittivity (?r) as high as 15 and a relatively low dielectric loss of ~0.1 at 1 kHz. These results demonstrate a new route to control the dispersion of high permittivity fillers toward high permittivity dielectric nanocomposites with low loss. Furthermore, the present study shows that the size distribution of nanofillers plays a key role in their spatial distribution and local ordering and alignment within supramolecular nanostructures.

Lee, Keun Hyung; Kao, Joseph; Parizi, Saman Salemizadeh; Caruntu, Gabriel; Xu, Ting

2014-03-01

226

Dielectric properties of barium titanate supramolecular nanocomposites.  

PubMed

Nanostructured dielectric composites can be obtained by dispersing high permittivity fillers, barium titanate (BTO) nanocubes, within a supramolecular framework. Thin films of BTO supramolecular nanocomposites exhibit a dielectric permittivity (?r) as high as 15 and a relatively low dielectric loss of ?0.1 at 1 kHz. These results demonstrate a new route to control the dispersion of high permittivity fillers toward high permittivity dielectric nanocomposites with low loss. Furthermore, the present study shows that the size distribution of nanofillers plays a key role in their spatial distribution and local ordering and alignment within supramolecular nanostructures. PMID:24584569

Lee, Keun Hyung; Kao, Joseph; Parizi, Saman Salemizadeh; Caruntu, Gabriel; Xu, Ting

2014-04-01

227

Scattering lengths of calcium and barium isotopes  

SciTech Connect

We have calculated the s-wave scattering length of all the even isotopes of calcium (Ca) and barium (Ba) in order to investigate the prospect of Bose-Einstein condensation (BEC). For Ca we have used an accurate molecular potential based on detailed spectroscopic data. Our calculations show that Ca does not provide other isotopes alternative to the recently Bose condensed {sup 40}Ca that suffers strong losses because of a very large scattering length. For Ba we show by using a model potential that the even isotopes cover a broad range of scattering lengths, opening the possibility of BEC for at least one of the isotopes.

Dammalapati, U.; Willmann, L.; Knoop, S. [Kernfysisch Versneller Instituut (KVI), University of Groningen, Zernikelaan 25, 9747 AA Groningen (Netherlands); LaserLaB Vrije Universiteit, De Boelelaan 1081, 1081 HV Amsterdam (Netherlands)

2011-11-15

228

Short-cavity squeezing in barium  

NASA Technical Reports Server (NTRS)

Broadband phase sensitive noise and squeezing were experimentally observed in a system of barium atoms interacting with a single mode of a short optical cavity. Squeezing of 13 +/- 3 percent was observed. A maximum possible squeezing of 45 +/- 8 percent could be inferred for out experimental conditions, after correction for measured loss factors. Noise reductions below the quantum limit were found over a range of detection frequencies 60-170 MHz and were best for high cavity transmission and large optical depths. The amount of squeezing observed is consistent with theoretical predictions from a full quantum statistical model of the system.

Hope, D. M.; Bachor, H-A.; Manson, P. J.; Mcclelland, D. E.

1992-01-01

229

Europium-doped barium bromide iodide  

SciTech Connect

Single crystals of Ba0.96Eu0.04BrI (barium europium bromide iodide) were grown by the Bridgman technique. The title compound adopts the ordered PbCl2 structure [Braekken (1932). Z. Kristallogr. 83, 222-282]. All atoms occupy the fourfold special positions (4c, site symmetry m) of the space group Pnma with a statistical distribution of Ba and Eu. They lie on the mirror planes, perpendicular to the b axis at y = +-0.25. Each cation is coordinated by nine anions in a tricapped trigonal prismatic arrangement.

Gundiah, Gautam; Hanrahan, Stephen M.; Hollander, Fredrick J.; Bourret-Courchesne, Edith D.

2009-10-21

230

Mineralogy and autoradiography of selected mineral-spring precipitates in the Western United States  

USGS Publications Warehouse

X-ray diffaction analysis of 236 precipitate or sediment samples from 97 mineral-spring sites in nine Western States showed the presence of 25 minerals, some precipitated and some detrital. Calcite and (or) aragonite are the most common of all the precipitated minerals. Gypsum and (or) anhydrite, as well as barite and native sulfur, are less common but are also believed to be precipitated minerals. Precipitated manganese and iron oxides, including romanechite, manganite, pyrolusite, goethite, and hematite, were found in some of the samples. Various salts of sodium, including halite and thenardite, were also identified. Dolomite and an unknown type of siliceous material are present in some of the samples and were possibly precipitated at the spring sites. Quartz, feldspar, and mica are present in many of the samples and are believed to be detrital contaminants. An autoradiographic and thin section study of 11 samples from nine of the most radioactive spring sites showed the radioactivity, which is due primarily to radium, to be directly associated with mineral phases containing barium, manganese, iron, and (or) calcium as major constituents. Furthermore, the radioactivity has an exclusive affinity for the manganese-bearing minerals, which in these samples contain a substantial amount of barium, even if calcite or iron oxides are present. Where calcite predominates and manganese- and barium-bearing minerals are absent, the radioactivity shows a close association with the iron oxides present, especially hematite, but also shows a moderate association with the calcite and (or) aragonite cementing phases. In other samples composed predominantly of calcite but lacking iron oxides, the radioactivity is preferentially associated with an early stage of calcite development and is considerably lower in the later cementing stages. The radioactivity observed in all these samples is believed to be caused by radium substituting for barium in mineral lattices, filling irregularities in other crystal structures, or adsorbing on the surfaces of precipitated molecules.

Bove, Dana; Felmlee, J. K.

1982-01-01

231

Relationship between microbial sulfate reduction rates and sulfur isotopic fractionation  

NASA Astrophysics Data System (ADS)

Sulfate reduction is one of the common processes to obtain energy for certain types of microorganisms.They use hydrogen gas or organic substrates as electron donor and sulfates as electron acceptor, and reduce sulfates to sulfides. Sulfate reducing microbes extend across domains Archea and Bacteria, and are believed to be one of the earliest forms of terrestrial life (Shen 2004). The origin of 34S-depleted (light) sulfide sulfur, especially ?34S < -30 ‰, around hydrothermal vents or beneath the sea-floor is speculated to be the products of sulfate reducers. But laboratory experiments using sulfate reducers fail to produce such light sulfur, and many models were proposed to explain the discrepancy. Canfield et al. (2006) proposed so-called "standard model" based on previous studies. The standard model explained the reason for the large fractionation by temperature dependence of sulfur isotopic fractionation factor and rate of sulfate reduction, which indicated the growth conditions of microbes. However, they failed to prove their model by their other experiments (Canfield et al., 2006). In this study, I performed laboratory culture experiment of sulfate reducing bacteria (SRB) to explain the 34S-depleted sulfide sulfur. [Experiments] To compare the result with Canfield et al. (2006), I used Desulfovibrio desulfuricans for my laboratory culture experiment. D. desulfuricans was inoculated into glass vials, which contain 40ml of liquid culture media slightly modified from DSMZ #63 medium.Excess amount of Fe (II) is added to the DSMZ#63 medium to precipitate sulfide as iron sulfide. The vials were incubated at 25°C, 30°C, and 37°C, respectively. 21 vials were used for one temperature and sulfide and sulfate was collected from each three glass vials at every 12 hours from 72 hours to 144 hours after start of incubation. The sulfide was precipitated as iron sulfide and the sulfate was precipitated as barite. Sulfur isotope compositions of sulfate and sulfide were measured by standard method using Delta Plus mass-spectrometer. [Results and Discussion] The fractionation between sulfide and sulfate ranged from 2.7 to 11.0. The fractionation values varied among the different incubation temperature and growth phase of D. desulfuricans. The maximum fractionation values of three incubation temperatures were 9.9, 11.0, and 9.7, for 25 °C, 30°C, and 37°C, respectively. These results were different from standard model and Canfield et al. (2006). I could not find the clear correlation between ?34S values and incubation temperatures in this experiment. The measured fractionation values during the incubation varied with incubation stage. The fractionation values clearly increased with incubation time at every temperature, and at 25°C ?34S value was 3.6 at the 72h and it increased to 7.9 at 144 hours. This indicated the difference of sulfate reduction rate due to the growth phase of SRB. In the early logarithmic growth phase, metabolic activity of SRB is high and sulfate reduction rate is fast. In contrast at the stationary phase, SRB stop growing and sulfate reduction rate get slower. My result suggested that the sulfur isotopic fractionation is controlled by growth phase of SRB and lighter sulfide would be produced by the stationary phase or half-dormant SRB in natural environment.

Matsu'Ura, F.

2009-12-01

232

Dissolution of sulfate scales  

SciTech Connect

This patent describes a composition for the removal of sulfate scale from surfaces. It comprises: an aqueous solution of about 0.1 to 1.0 molar concentration of an aminopolycarboxylic acid (APCA) containing 1 to 4 amino groups or a salt thereof, and about 0.1 to 1.0 molar concentration of a second component which is diethylenetriaminepenta (methylenephosphonic acid) (DTPMP) or a salt thereof, or aminotri (methylenephosphonic acid) (ATMP) or a salt thereof as an internal phase enveloped by a hydrocarbon membrane phase which is itself emulsified in an external aqueous phase, the hydrocarbon membrane phase continuing a complexing agent weaker for the cations of the sulfate scale than the APCA and DTPMP or ATMP, any complexing agent for the cations in the external aqueous phase being weaker than that in the hydrocarbon membrane phase.

Hen, J.

1991-11-26

233

Adeninium cytosinium sulfate  

PubMed Central

In the title compound, C5H6N5 +·C4H6N3O+·SO4 2?, the adeninium (AdH+) and cytosinium (CytH+) cations and sulfate dianion are involved in a three-dimensional hydrogen-bonding network with four different modes, viz. AdH+?AdH+, AdH+?CytH+, AdH+?SO4 2? and CytH+?SO4 2?. The adeninium cations form N—H?N dimers through the Hoogsteen faces, generating a characteristic R 2 2(10) motif. This AdH+?AdH+ hydrogen bond in combination with AdH+?CytH+ H-bonds leads to two-dimensional cationic ribbons parallel to the a axis. The sulfate anions inter­link the ribbons into a three-dimensional hydrogen-bonding network and thus reinforce the crystal structure.

Cherouana, Aouatef; Bousboua, Raja; Bendjeddou, Lamia; Dahaoui, Slimane; Lecomte, Claude

2009-01-01

234

Polymorphic change from vaterite to aragonite under influence of sulfate: The "morning star" habit  

NASA Astrophysics Data System (ADS)

The presence of sulfate in reverse osmosis drinking water concentrate and its effect on calcium carbonate precipitation was studied, notably the overall kinetics of CaCO3 formation and the types of polymorphs formed. CaCO3 formation slows down with increasing sulfate concentration and the preferential polymorph shifts from vaterite to aragonite with increasing sulfate concentration. With this polymorphic change, a new combined habit is observed where aragonite spikes grow on top of vaterite ("morning star" habit). The presence of a moderate magnesium concentration results in the shift of vaterite to aragonite at relatively low sulfate concentrations; where sulfate and magnesium appear to have an additive effect. Without magnesium, spikes on top of vaterite were also observed, but only at relatively high sulfate concentration. Without the presence of magnesium, single crystals of aragonite were not found.

Wagterveld, R. M.; Yu, M.; Miedema, H.; Witkamp, G. J.

2014-02-01

235

THE EFFECT OF RADIOACTIVITY ON THE SORPTIVE PROPERTIES OF BARIUM SULFATE  

Microsoft Academic Search

Studies of the effects of radioactivity on the adsorption of (CââH\\/; sub 11\\/OâNâS) Na, (Cââ HââNâS)Cl, and (CââH\\/; sub 35Nâ)Cl on BaSOâ (labeled with S³⁵) showed a much higher ; order of BaSOâ residue adsorption of methyl orange than any other dye ; indicator. However, the adsorption of methyl blue is somewhat higher than that ; of brilliant green. (R.V.J.);

V. I. Spitsyn; V. V. Gromov

1958-01-01

236

Barium in Deep-Sea Sediment: A Geochemical Proxy for Paleoproductivity  

Microsoft Academic Search

We used sediment traps to define the particulate fluxes of barium and organic carbon and investigate the use of barium as a proxy for ocean fertility. Strong correlations between Corg and Ba fluxes indicate a link between upper ocean biological processes and barium flux to the seafloor. The ratio of organic carbon to barium decreases systematically with water depth. Data

Jack Dymond; Erwin Suess; Mitch Lyle

1992-01-01

237

Effect of Barium on Growth and Macronutrient Nutrition in Tanzania Guineagrass Grown in Nutrient Solution  

Microsoft Academic Search

Barium has been identified as a toxic element to most plants, although for grasses the toxicity has not been determined. A greenhouse experiment was performed to evaluate the effect of barium on growth parameters, barium accumulation, and macronutrient concentration in Tanzania guineagrass (Panicum maximum Jacq.), cultivated in nutrient solution. Five barium rates and a control were set in a complete

Francisco Antonio Monteiro; Roberta Corrêa Nogueirol; Leônidas Carrijo Azevedo Melo; Adriana Guirado Artur; Fabiana da Rocha

2011-01-01

238

Microstructure and magnetism in barium strontium titanate (BSTO)-barium hexaferrite (BaM) multilayers  

SciTech Connect

High quality multilayers of barium ferrite (BaM) and barium strontium titanate (BSTO) were grown in optimized conditions on thermally oxidized Si(1 0 0) and Al{sub 2}O{sub 3} substrates using magnetron sputtering. As-grown films were amorphous and different annealing procedures were explored to stabilize crystalline phases. BSTO and BaM phases were identified using X-ray diffraction and cross-sectional scanning electron micrographs showed sharp interfaces between BSTO and BaM layers. Magnetic hysteresis loops obtained at various temperatures and field orientations showed a large coercivity ({approx}2500 Oe) consistent with the hard magnetic hexaferrite component. Hysteresis loops also revealed the distinct influence of magnetocrystalline and shape anisotropies at different temperature ranges.

Frey, N.A. [Materials Physics Laboratory, Physics Department, University of South Florida, 4202 East Fowler Avenue, Tampa, FL 33620 (United States); Heindl, R. [Materials Physics Laboratory, Physics Department, University of South Florida, 4202 East Fowler Avenue, Tampa, FL 33620 (United States); Srinath, S. [Materials Physics Laboratory, Physics Department, University of South Florida, 4202 East Fowler Avenue, Tampa, FL 33620 (United States); Srikanth, H. [Materials Physics Laboratory, Physics Department, University of South Florida, 4202 East Fowler Avenue, Tampa, FL 33620 (United States)]. E-mail: sharihar@cas.usf.edu; Dudney, N.J. [Solid State Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States)

2005-08-11

239

Proton conductivity of potassium doped barium zirconates  

SciTech Connect

Potassium doped barium zirconates have been synthesized by solid state reactions. It was found that the solubility limit of potassium on A-sites is between 5% and 10%. Introducing extra potassium leads to the formation of second phase or YSZ impurities. The water uptake of barium zirconates was increased even with 5% doping of potassium at the A-site. The sintering conditions and conductivity can be improved significantly by adding 1 wt% ZnO during material synthesis. The maximum solubility for yttrium at B-sites is around 15 at% after introducing 1 wt% zinc. The conductivity of Ba{sub 0.95}K{sub 0.05}Zr{sub 0.85}Y{sub 0.11}Zn{sub 0.04}O{sub 3-{delta}} at 600 deg. C is 2.2x10{sup -3} S/cm in wet 5% H{sub 2}. The activation energies for bulk and grain boundary are 0.29(2), 0.79(2) eV in wet 5% H{sub 2} and 0.31(1), 0.74(3) eV in dry 5% H{sub 2}. A power density of 7.7 mW/cm{sup 2} at 718 deg. C was observed when a 1 mm thick Ba{sub 0.95}K{sub 0.05}Zr{sub 0.85}Y{sub 0.11}Zn{sub 0.04}O{sub 3-{delta}} pellet was used as electrolyte and platinum electrodes. - Graphical abstract: Potassium doped barium zirconates have been synthesized by solid state reactions. It was found that the solubility limit of potassium on A-sites is between 5% and 10 %. The sintering conditions and conductivity can be improved significantly by adding 1 wt% ZnO during material synthesis. Five percent doping of potassium at A-site can double the total conductivity.

Xu Xiaoxiang [School of Chemistry, University of St. Andrews, Fife KY16 9ST (United Kingdom); Tao Shanwen, E-mail: s.tao@hw.ac.u [School of Chemistry, University of St. Andrews, Fife KY16 9ST (United Kingdom); Department of Chemistry, Heriot-Watt University, Edinburgh EH14 4AS (United Kingdom); Irvine, John T.S. [School of Chemistry, University of St. Andrews, Fife KY16 9ST (United Kingdom)

2010-01-15

240

Remediation of acid mine drainage with sulfate reducing bacteria  

SciTech Connect

Sulfate reducing bacteria have been shown to be effective at treating acid mine drainage through sulfide production and subsequent precipitation of metal sulfides. In this laboratory experiment for undergraduate environmental chemistry courses, students design and implement a set of bioreactors to remediate acid mine drainage and explain observed changes in dissolved metal concentrations and pH. Using synthetic acid mine drainage and combinations of inputs, students monitor their bioreactors for decreases in dissolved copper and iron concentrations.

Hauri, J.F.; Schaider, L.A. [Assumption College, Worcester, MA (USA)

2009-02-15

241

Determination of Cremophor® EL in plasma after sample preparation with solid phase extraction and plasma protein precipitation  

Microsoft Academic Search

The non-ionic emulsifier Cremophor® EL can be quantified using a special potentiometric titration technique with barium chloride activation and precipitation with sodium tetraphenylborate. The end point of the titration is indicated by an ionsensitive coated wire electrode which responds to an excess of tetraphenylborate ions. Sample preparation is necessary to quantify the excipient in plasma of patients receiving ciclosporin formulations

Th Meyer; J Böhler; A. W Frahm

2001-01-01

242

Magnetic properties of substituted barium ferrite powders  

SciTech Connect

Hexagonal barium ferrites were prepared using the citrate method. Cobalt and titanium were added in the amounts x from 0.2 to 1.1 ion/f.u. related to the formula BaCo{sub x}Ti{sub x}Fe{sub 12{minus}2x}O{sub 19}. The heat treatment has been applied in three steps of 550 C/5 hrs, 850 C/2 hrs and 1,100 C/2 hrs. The following magnetic properties have been achieved: H{sub c} {approximately} 80 kA/m, J{sub s} {approximately} 120 {times} 10{sup {minus}6} Tkg{sup {minus}1} m{sup 3}, and J{sub r} {approximately} 60 {times} 10{sup {minus}6} Tkg{sup {minus}1} m{sup 3} in the composition for which x is equal to 0.5 ion/f.u. The magnetic parameters have been measured by the vibration magnetometer.

Gruskova, A. [Slovak Univ. of Technology, Bratislava (Slovakia). Dept. of Electrotechnology] [Slovak Univ. of Technology, Bratislava (Slovakia). Dept. of Electrotechnology

1994-03-01

243

Barium hexaferrite ferrofluids - preparation and physical properties  

NASA Astrophysics Data System (ADS)

Barium hexaferrite BaFe 12-2 xTi xCo xO 19 ferrofluids have been prepared for the first time using oleic acid as surfactant and Isopar M ® as carrier liquid. The initial susceptibility versus temperature for zero-field cooling of the ferrofluid was obtained by a vibrating sample magnetometer. TEM pictures of the fluid show isolated particles and only small agglomerates and a mean particle diameter of approx. 8 nm. Numerical calculations of the magneto-viscous effect, based on the local-equilibrium magnetic state model, clearly show the benefit for Ba-ferrite ferrofluids resulting from the high uniaxial anisotropy compared to magnetite ferrofluids. Rheological measurements were performed with a rotational-type viscometer with magnetic field perpendicular to the hydrodynamic vortex axis.

Müller, R.; Hiergeist, R.; Steinmetz, H.; Ayoub, N.; Fujisaki, M.; Schüppel, W.

1999-07-01

244

Synthesis of barium fluoride nanoparticles from microemulsion  

NASA Astrophysics Data System (ADS)

The cetyltrimethylammonium bromide (CTAB)/2-octanol/water microemulsion system was used to synthesize barium fluoride nanoparticles. X-ray powder diffraction (XRD) analysis showed that the products were single phase. The results of scanning electron microscopy and calculations using the Scherrer equation from the line widths of the XRD have been used to estimate the average particle sizes of the powder products. The results showed that the nanoparticle size was affected by water content and surfactant (CTAB) concentration. As water content decreases from 14.2 to 9.47% (w/w), the particle size decreases from 75 to 40 nm. In addition, increasing the reaction times from 5 to 120 min increases the particle size from 75 to 150 nm, and increasing the amount of surfactant decreases the size of the particle. Luminescence spectra of the BaF2:Ce nanoparticles are also discussed.

Hua, Ruinian; Zang, Chunyu; Shao, Chen; Xie, Demin; Shi, Chunshan

2003-06-01

245

Oxidative dissolution of uraninite precipitated on Navajo sandstone  

Microsoft Academic Search

Column and batch experiments were conducted with sandstone and ground water samples to investigate oxidation of uraninite precipitated by microbially mediated reduction of U(VI), a contaminant in ground water beneath a uranium mill tailings site near Tuba City, AZ, USA. Uraninite precipitated together with mackinawite (FeS0.9) because Fe(III) from the sandstone and sulfate, another contaminant in the water were reduced

A Abdelouas; W Lutze; H. E Nuttall

1999-01-01

246

Sulfur Isotopes as Indicators of Bacterial Sulfate Reduction Processes Influencing Field Scale Uranium Bioremediation  

NASA Astrophysics Data System (ADS)

An in-situ acetate amendment at a DOE Uranium Mill Tailings Remedial Action (UMTRA) site near Rifle, CO demonstrated successful reduction of aqueous U(VI), to less soluble U(IV) through stimulated microbial activity. U(VI) reduction rates were highest during iron reduction and decreased with the onset of sulfate reduction. However, sustained U(IV) attenuation was observed following subsequent termination of the acetate amendment. These findings illustrate the importance of the transition between iron and sulfate reducing conditions in stimulating bioreduction of uranium. The sulfur isotope compositions of sulfate and sulfide were measured through this transition in order to explore the utility of these data in tracking the extent of microbial sulfate reduction and to assess the stability of sulfide precipitates. Samples for isotopic analyses and aqueous measurements of sulfate, ferrous iron, U(VI) and acetate were collected in one background well and three monitoring wells down-gradient of the acetate injection. Results show an increase of up to 7‰ in the ?34S of sulfate at the onset of sulfate reduction, followed by a return to background ?34S values of -8‰ following cessation of the acetate amendment. The ?34S values of sulfide increased from roughly -20‰ at the onset of sulfate reduction to a maximum of -0.8‰ during peak sulfate removal, followed by a gradual return to values of roughly -28‰ upon cessation of the acetate amendment. These data present a unique perspective on the processes governing the bioreduction experiment in that the sulfate isotopes are a function of both transport and mixing processes, whereas the sulfide isotopes represent biogenic sulfide that is rapidly removed from the aqueous phase. Thus a comparable enrichment in sulfate isotopic data noted in the closest and furthest wells from the injection gallery suggest bioreduction in both of these locations, while a larger increase in sulfide isotopic values in the closest well indicates greater rates of sulfate reduction closer to the injection gallery. In addition, a steady decline in ?34S of sulfide concurrent with increased sulfide concentrations following cessation of acetate amendment suggests that this increase is not a result of reoxidation of precipitated FeS species. FeS precipitates formed during the height of sulfate reduction therefore appear to be stable on a timeframe of months following acetate amendment and may support the stability and long-term sequestration of precipitated U(IV).

Druhan, J. L.; Conrad, M. E.; Williams, K. H.; N'guessan, L.; Long, P. E.; Hubbard, S. S.

2007-12-01

247

Developmental effects of barium exposure in a marine bivalve (Mytilus californianus)  

SciTech Connect

Produced water, an aqueous waste of variable composition associated with petroleum and natural gas extraction, is frequently discharged into the marine environment in significant quantities. Concern and controversy exist regarding potential adverse environmental effects related to such discharges. Previous reports indicated that barium (Ba) and/or strontium (Sr) were primarily responsible for the toxicity of a southern California produced water to developing marine embryos. To further investigate toxicity of Ba and Sr in seawater, mussel embryos (Mytilus californianus) were subjected to static exposures of barium acetate and strontium chloride from fertilization through veliger formation. Only Ba exhibited bioactivity at environmentally relevant levels. Adverse effects occurred between 200 and 900 {micro}g/L (ppb); higher concentrations were associated with decreased toxicity and apparent precipitation of Ba salts from seawater. Nominal Ba exposure concentrations between 100 and 900 {micro}g/L yielded measured concentrations of 100 to 550 {micro}g/L soluble Ba when analyzed by inductively coupled argon plasma emission spectroscopy. Adverse developmental effects included abnormal shell calcification and embryo morphology. Exposure of embryos to Ba in state-specific experiments revealed that developmental stages were differentially affected, though they exhibited similar abnormalities. Gastrulae were the most sensitive, while blastula and trochophore larvae were less so. Adverse effects in embryos exposed during the gastrula stage were not reversible despite washing and return to clean seawater. These findings are among the first to demonstrate that low concentrations of soluble Ba in seawater can be toxic and are of potential concern in the marine environment.

Spangenberg, J.V. [Univ. of California, Bodega Bay, CA (United States). Bodega Marine Lab.; Cherr, G.N. [Univ. of California, Bodega Bay, CA (United States). Bodega Marine Lab.]|[Univ. of California, Davis, CA (United States). Dept. of Environmental Toxicology

1996-10-01

248

Effects of light exposure on irradiated barium fluoride crystals.  

National Technical Information Service (NTIS)

Small barium fluoride crystals have been irradiated using cobalt-60 gamma rays under various illumination conditions to establish the effect of photo-bleaching of the radiation-induced color centers. This paper describes results of a few different experim...

C. R. Wuest G. J. Mauger

1993-01-01

249

Study of the photovoltaic effect in thin film barium titanate  

NASA Technical Reports Server (NTRS)

The feasibility of making non-volatile digital memory devices of barium titanate, BaTiO3, that are integrated onto a silicon substrate with the required ferroelectric film produced by processing, compatible with silicon technology was examined.

Grannemann, W. W.; Dharmadhikari, V. S.

1983-01-01

250

Barium and Radium in Water Treatment Plant Wastes.  

National Technical Information Service (NTIS)

Water treatment plants at nine locations (10 plants) in Illinois and Iowa were studied to determine the characteristics and disposal practices for the sludge, brine, and backwash water containing radium (Ra) and/or barium (Ba). The treatment processes in ...

A. G. Myers C. K. Jongeward S. K. Richter V. L. Snoeyink

1985-01-01

251

Calculated emission rates for barium releases in space  

NASA Technical Reports Server (NTRS)

The optical emissions from barium releases in space are caused by resonance and fluorescent scattering of sunlight. Emission rates for the dominant ion and neutral lines are calculated assuming the release to be optically thin and the barium to be in radiative equilibrium with the solar radiation. The solar spectrum has deep Fraunhofer absorption lines at the primary barium ion resonances. A velocity component toward or away from the sun will Doppler shift the emission lines relative to the absorption lines and the emission rates will increase many-fold over the rest value. The Doppler brightening is important in shaped charge or satellite releases where the barium is injected at high velocities. Emission rates as a function of velocity are calculated for the 4554, 4934, 5854, 6142 and 6497 A ion emission lines and the dominant neutral line at 5535 A. Results are presented for injection parallel to the ambient magnetic field, B, and for injection at an angle to B.

Stenbaek-Nielsen, H. C.

1989-01-01

252

Dielectrics of lead zirconate bonded with barium borate glass  

Microsoft Academic Search

Dielectric constant variation with temperature and frequency is reported for barium-borate glass-bonded lead zirconate. Lowering\\u000a of the relative permittivity of the ceramic is attributed to the presence of the glass.

K Singh; Aruna Indurkar

1988-01-01

253

Synthesis, photoluminescence and magnetic properties of barium vanadate nanoflowers  

SciTech Connect

Graphical abstract: The flower-shaped barium vanadate was obtained for the first time. The photoluminescence and magnetic properties of the barium vanadate nanoflowers were investigated at room temperature. Research highlights: {yields} In the paper, the flower-shaped barium vanadate were obtained for the first time. The CHM method used here is new and simple for preparation of barium vanadate. {yields} The photoluminescence and magnetic properties of the barium vanadate nanoflowers were investigated at room temperature. The strong bluish-green emission was observed. {yields} The ferromagnetic behavior of the barium vanadate nanoflowers was found with saturation magnetization of about 83.50 x 10{sup -3} emu/g, coercivity of 18.89 Oe and remnant magnetization of 4.63 x 10{sup -3} emu/g. {yields} The mechanisms of PL and magnetic property of barium vanadate nanoflowers have been discussed. -- Abstract: The flower-shaped barium vanadate has been obtained by the composite hydroxide mediated (CHM) method from V{sub 2}O{sub 5} and BaCl{sub 2} at 200 {sup o}C for 13 h. XRD and XPS spectrum of the as-synthesized sample indicate it is hexagonal Ba{sub 3}V{sub 2}O{sub 8} with small amount of Ba{sub 3}VO{sub 4.8} coexistence. Scan electron microscope and transmission electron microscope display that the flower-shaped crystals are composed of nanosheets with thickness of {approx}20 nm. The UV-visible spectrum shows that the barium vanadate sample has two optical gaps (3.85 eV and 3.12 eV). Photoluminescence spectrum of the barium vanadate flowers exhibits a visible light emission centered at 492 and 525 nm which might be attributed to VO{sub 4} tetrahedron with T{sub d} symmetry in Ba{sub 3}V{sub 2}O{sub 8}. The ferromagnetic behavior of the barium vanadate nanoflowers has been found with saturation magnetization of about 83.50 x 10{sup -3} emu/g, coercivity of 18.89 Oe and remnant magnetization of 4.63 x 10{sup -3} emu/g, which is mainly due to the presence of a non-orthovanadate phase with spin S = 1/2.

Xu, Jing [Department of Applied Physics, Chongqing University, 174 Shapingba Street, Chongqing 400044 (China) [Department of Applied Physics, Chongqing University, 174 Shapingba Street, Chongqing 400044 (China); Chongqing University of Science and Technology, Chongqing 401331 (China); Hu, Chenguo, E-mail: hucg@cqu.edu.cn [Department of Applied Physics, Chongqing University, 174 Shapingba Street, Chongqing 400044 (China)] [Department of Applied Physics, Chongqing University, 174 Shapingba Street, Chongqing 400044 (China); Xi, Yi [Department of Applied Physics, Chongqing University, 174 Shapingba Street, Chongqing 400044 (China)] [Department of Applied Physics, Chongqing University, 174 Shapingba Street, Chongqing 400044 (China); Peng, Chen [School of Physical Science and Technology, Southwest University, Chongqing 400715 (China)] [School of Physical Science and Technology, Southwest University, Chongqing 400715 (China); Wan, Buyong; He, Xiaoshan [Department of Applied Physics, Chongqing University, 174 Shapingba Street, Chongqing 400044 (China)] [Department of Applied Physics, Chongqing University, 174 Shapingba Street, Chongqing 400044 (China)

2011-06-15

254

Neutron source, neutron density and the origin of barium stars  

Microsoft Academic Search

The authors present new high resolution spectra of the MgH profiles in nine barium stars, and determine, by spectral synthesis techniques, the magnesium isotopic ratios in each star. When compared with recent AGB nucleosynthesis calculations, they can emphatically rule out the operation of the 22Ne(alpha, n)25Mg reaction as the neutron source responsible for the s-process enhancements observed in these barium

Robert A. Malaney; David L. Lambert

1988-01-01

255

White-dwarf kicks and implications for barium stars  

NASA Astrophysics Data System (ADS)

The formation mechanism of the barium stars is thought to be well understood. Barium-rich material, lost in a stellar wind from a thermally-pulsing asymptotic-giant branch star in a binary system, is accreted by its companion main-sequence star. Now, many millions of years later, the primary is an unseen white dwarf and the secondary has itself evolved into a giant which displays absorption lines of barium in its spectrum and is what we call a barium star. A similar wind-accretion mechanism is also thought to form the low-metallicity CH and carbon-enhanced metal-poor stars. Qualitatively the picture seems clear but quantitatively it is decidedly murky: several key outstanding problems remain which challenge our basic understanding of binary-star physics. Barium stars with orbital periods less than about 4000 days should - according to theory - be in circular orbits because of tidal dissipation, yet they are often observed to be eccentric. Only one barium-star period longer than 104 days has been published although such stars are predicted to exist in large numbers. In this paper we attempt to shed light on these problems. First, we consider the impact of kicking the white dwarf at its birth, a notion which is supported by independent evidence from studies of globular clusters. Second, we increase the amount of orbital angular momentum loss during wind mass transfer, which shrinks barium-star binaries to the required period range. We conclude with a discussion of possible physical mechanisms and implications of a kick, such as the break up of wide barium-star binaries and the limits imposed on our models by observations.

Izzard, R. G.; Dermine, T.; Church, R. P.

2010-11-01

256

The properties of barium titanate RF sputtered in argon  

Microsoft Academic Search

The structural, optical and dielectric properties of barium titanate thin films deposited on water-cooled substrates by RF sputtering in Ar (99.99%) were investigated. Optically thin and thick films for the visible spectral region were studied.From the investigations it is concluded that there are at least two crystalline phases in addition to amorphous barium titanate in the deposited coatings, and the

T Pencheva; M Nenkov

1997-01-01

257

'Skidding' of the CRRES G-9 barium release  

NASA Technical Reports Server (NTRS)

A simulation study and experimental data of the CRRES G-9 ionospheric barium release are presented. The simulation study is based on a 2D electrostatic code that incorporates time-dependent coupling to the background plasma. It is shown that the densest portion of the barium ion cloud 'skids' about 15 km within the first three seconds following the release, consistent with the optical data analyses.

Huba, J. D.; Mitchell, H. G.; Fedder, J. A.; Bernhardt, P. A.

1992-01-01

258

A statistical experiment design approach for arsenic removal by coagulation process using aluminum sulfate  

Microsoft Academic Search

Arsenic removal from drinking water by precipitation–coprecipitation method using aluminum sulfate was investigated. The Box–Behnken statistical experiment design (BBD) and response surface methodology (RSM) were used to investigate the effects of major operating variables. Initial arsenate concentration, pH, and aluminum sulfate dose were selected as independent variables in BBD while arsenate removal was considered as the response function. The predicted

Meltem Bilici Baskan; Aysegul Pala

2010-01-01

259

Natural or anthropogenic? On the origin of atmospheric sulfate deposition in the Andes of southeastern Ecuador  

NASA Astrophysics Data System (ADS)

Atmospheric sulfur deposition above certain limits can represent a threat to tropical forests, causing nutrient imbalances and mobilizing toxic elements that impact biodiversity and forest productivity. Atmospheric sources of sulfur deposited by precipitation have being roughly identified in only a few lowland tropical forests. Even scarcer are these type of studies in tropical mountain forests, many of them megadiversity hotspots and especially vulnerable to acidic deposition. Here, the topographic complexity and related streamflow condition the origin, type, and intensity of deposition. Furthermore, in regions with a variety of natural and anthropogenic sulfur sources, like active volcanoes and biomass-burning, no source-emission data has been used for determining the contribution of each of them to the deposition. The main goal of the current study is to evaluate sulfate (SO4-) deposition by rain and occult precipitation at two topographic locations in a tropical mountain forest of southern Ecuador, and to trace back the deposition to possible emission sources applying back trajectory modeling. To link upwind natural (volcanic) and anthropogenic (urban/industrial and biomass-burning) sulfur emissions and observed sulfate deposition, we employed state of the art inventory and satellite data, including volcanic passive degassing as well. We conclude that biomass-burning sources generally dominate sulfate deposition at the evaluated sites. Minor sulfate transport occurs during the shifting of the predominant winds to the north and west. Occult precipitation sulfate deposition and likely rain sulfate deposition are mainly linked to biomass-burning emissions from the Amazon lowlands. Volcanic and anthropogenic emissions from the north and west contribute to occult precipitation sulfate deposition at the mountain crest Cerro del Consuelo meteorological station and to rain-deposited sulfate at the upriver mountain-pass El Tiro meteorological station.

Makowski Giannoni, S.; Rollenbeck, R.; Trachte, K.; Bendix, J.

2014-05-01

260

Remediation of chromite ore processing residue using ferrous sulfate and calcium polysulfide  

Microsoft Academic Search

Batch tests were conducted to assess the potential use of ferrous sulfate and calcium polysulfide for the remediation of chromite\\u000a ore processing residue (COPR). The remediation process entails addition of ferrous sulfate or calcium polysulfide to chemically\\u000a reduce hexavalent chromium [Cr(VI)] to trivalent chromium [Cr(III)] in slurry form and pH adjustment to precipitate Cr(III)\\u000a as chromium hydroxide. The present study

Mahmoud Wazne; Deok Hyun Moon; Santhi Chandra Jagupilla; Sarath Chandra Jagupilla; Christos Christodoulatos; Dimitris Dermatas; Maria Chrysochoou

2007-01-01

261

21 CFR 524.1484e - Neomycin sulfate and polymyxin B sulfate ophthalmic solution.  

Code of Federal Regulations, 2013 CFR

...false Neomycin sulfate and polymyxin B sulfate ophthalmic solution. 524.1484e Section 524.1484e Food and Drugs ...1484e Neomycin sulfate and polymyxin B sulfate ophthalmic solution. (a) Specifications. Each milliliter of the...

2013-04-01

262

Minerals Yearbook, 1993: Sodium Sulfate.  

National Technical Information Service (NTIS)

U.S. sodium sulfate production increased 6% in 1993 to 651,000 tons according to preliminary statistics from the Bureau of the Census. Production of natural sodium sulfate from three domestic locations declined 5% to 327,000 tons, which was the lowest lev...

D. S. Kostick

1994-01-01

263

Integral membrane heparan sulfate proteoglycans  

Microsoft Academic Search

Heparan sulfate is a regulatory polysac- charide. It modulates specific growth factor-receptor in- teractions, accelerates the formation of specific proteinase- proteinase inhibitor complexes, and mediates interactions of the cell surface with several enzymes and structural proteins. It abounds on the surfaces of embryonic cells, respecting or outlining morphogenetic rather than histo- logical boundaries. This cell surface-associated heparan sulfate is implanted

GUIDO DAVID

1993-01-01

264

Determination of trace elements in triglycine sulfate solutions  

NASA Technical Reports Server (NTRS)

Ten elements were divided into 2 groups. The elements in the first group included iron, nickel, chromium, manganese, copper, and gold. The elements in the second group included zinc, cobalt, lead, cadmium, and gold. Five ppm of each element in each group was spiked in a 1 percent triglycine sulfate (TGS) solution. Glycine was removed with 1-naphthyl isocyanate in ether medium. The glycine derivative 1-naphthyl isocyanate glycine was removed by filtration, and the filtrates were analyzed for the different elements. Analysis of these elements was performed by using the 5100 Perkin-Elmer Atomic Absorption Spectrophotometer. The result of these experiments was the observation that there was a decrease in the concentration of chromium and gold, which was interpreted to be due to the chelation of these elements by the derivative 1-naphthyl isocyanate glycine. Further research is needed to determine the concentration of other elements in triglycine sulfate (TGS) solutions. These elements will include lithium, sodium, rubidium, magnesium, calcium, strontium, barium, aluminum, and silicon. These are the most likely elements to be found in the sulfuric acid used in manufacturing the TGS crystal. Moreover, we will extend our research to investigate the structural formula of the violet colored chelated compounds, which had been formed by interaction of the derivative 1-naphthyl isocyanate glycine with the different elements, such as gold, chromium.

Tadros, Shawky H.

1993-01-01

265

Polymerized complex route to barium titanate powders using barium-titanium mixed-metal citric acid complex  

Microsoft Academic Search

Barium titanate (BaTiOâ) powders were prepared by a polymerized complex method based on the Pechini-type reaction route, wherein a mixed solution of citric acid (CA), ethylene glycol (EG), and barium and titanium ions, with a molar ratio of CA:EG:Ba:Ti = 10:40:1:1, was polymerized to form a transparent resin, which was used as a precursor for BaTiOâ. Characterization of the initial

Momoko Arima; Masato Kakihana; Yoshiyuki Nakamura; Masatomo Yashima; Masahiro Yoshimura

1996-01-01

266

Sol-gel synthesis of ultrafine barium titanate using butyl titanate monomer and barium nitrate and its characterization  

Microsoft Academic Search

Barium titanate is a well-known ferroelectric material (Tc ? 120°C) dominating the dielectric ceramics field for the last five decades and is very widely used in multi-layer capacitors. It is usually prepared via the classical solid state reaction between barium carbonate and titanium dioxide around 1100–1300°C. On the other hand, chemical routes with new precursors are being developed to improve

P. D. Godbole; S. B. Deshpande; S. K. Date; Rashmi Nawathey; S. B. Ogale

1990-01-01

267

Preparation of crystalline beta barium borate thin films on Sr 2+-doped alpha barium borate substrates by liquid phase epitaxy  

Microsoft Academic Search

Thin films of beta barium borate have been prepared by liquid phase epitaxy on Sr2+-doped ?-BaB2O4 (?-BBO, the high temperature phase of barium borate) (001) and (110) substrates. The results of X-ray diffraction indicate that the films show highly (00l) preferred orientation on (001)-oriented substrates while the films grown on (110) substrates are textured with (140) orientation. The crystallinity of

Junfang Liu; Xiaoming He; Changtai Xia; Guoqing Zhou; Shengming Zhou; Jun Xu; W. Yao; Liejia Qian

2006-01-01

268

Barium recovery by crystallization in a fluidized-bed reactor: effects of pH, Ba/P molar ratio and seed.  

PubMed

The effects of process conditions, including upward velocity inside the column, the amount of added seed and seed size, the pH value of the precipitant or the phosphate stream and the Ba/P molar ratio in a fluidized-bed reactor (FBR) were studied with a view to producing BaHPO? crystals of significant size and maximize the removal of barium. XRD were used to identify the products that were collected from the FBR. Experimental results show that an upward velocity of 48 cmmin(-1) produced the largest BaHPO? crystals with a size of around 0.84-1.0mm. The addition of seed crystals has no effect on barium removal. The use of a seed of a size in the ranges unseeded<0.149-0.29 mm<0.149 mm<0.29-0.42 mm produced increasing amounts of increasingly large crystals. The largest BaHPO? crystals were obtained at pH 8.4-8.8 with a Ba/P molar ratio of 1.0. In the homogeneous and heterogeneous processes, around 98% of barium was removed at pH 8.4-8.6 and [Ba]/[P]=1.0. The XRD results show that a significant amount of barium phosphate (Ba?(PO?)?) was obtained at pH 11. The compounds BaHPO? and BaO were present at a pH of below 10. PMID:24462085

Su, Chia-Chi; Reano, Resmond L; Dalida, Maria Lourdes P; Lu, Ming-Chun

2014-06-01

269

Molecular Structure of Sulfate ion  

NSDL National Science Digital Library

Sulfate is a naturally occurring substance that is found in minerals and rocks, and in soil it is one of the most predominant anions. This substance results from the oxidation of elemental sulfur, sulfides, or organic sulfur. While sulfate is one of the least toxic anions, it is monitored under the Safe Drinking Water Act (SDWA). The anion is used in mining, pulping, metal and plating industries, water and sewage treatment, leather processing and in the manufacture of numerous chemicals, dyes, glass, soaps, textiles, fungicides, insecticides, astringents, and emetics. Various sulfate salts are used in foods, the estimated daily intake of sulfate from the consumption of food is approximately 453 milligrams (mg). Sulfate can have a cathartic effect on humans which results in the purgation of the alimentary canal, when 1000-2000 mg is ingested.

2002-09-11

270

SPATIAL AND TEMPORAL PATTERNS OF ACID PRECIPITATION AND THEIR INTERPRETATION  

EPA Science Inventory

Using data compiled from seven nationwide precipitation chemistry networks in the U.S. and Canada, the spatial distribution of hydrogen, sulfate, and nitrate ions in North America is discussed. Geographic patterns of concentration and deposition are characterized using isopleth m...

271

Process of precipitating zirconium or hafnium from spent pickling solutions  

Microsoft Academic Search

This patent describes a process for regenerating a spent, fluoride-containing pickle solution used in the pickling of zirconium or hafnium metal or their alloys. It comprises adding to the spent pickle solution a sufficient amount of sodium sulfate to precipitate sodium zirconium or hafnium fluoride.

C. L. Aguilar; R. G. Walker

1991-01-01

272

Process of precipitating zirconium or hafnium from spent pickling solutions  

SciTech Connect

This patent describes a process for regenerating a spent, fluoride-containing pickle solution used in the pickling of zirconium or hafnium metal or their alloys. It comprises adding to the spent pickle solution a sufficient amount of sodium sulfate to precipitate sodium zirconium or hafnium fluoride.

Aguilar, C.L.; Walker, R.G.

1991-12-31

273

Composition and solubility of ettringite precipitated from combusted oil shale.  

National Technical Information Service (NTIS)

Ettringite is a complex hydrated calcium aluminum sulfate hydroxide (Ca(sub 6)Al(sub 2)(SO(sub 4))(sub 3)(OH)(sub 12)(center dot)26H(sub 2)O) that precipitates in weathering spent oil shale environments. The application of an equilibrium solubility model ...

M. E. Essington

1989-01-01

274

Ion Exchange Studies for Removal of Sulfate from Hanford Tank Waste Envelope C (241-AN-107) Using SuperLig 655 Resin  

SciTech Connect

BNFL Inc. is evaluating various pretreatment technologies to mitigate the impacts of sulfate on the LAW vitrification system. One pretreatment technology for separating sulfate from LAW solutions involves the use of SuperLig{reg_sign} 655 (SL-655), a proprietary ion exchange material developed and supplied by IBC Advanced Technologies, Inc., American Fork, UT. This report describes testing of SL-655 with diluted ([Na] {approximately} 5 M) waste from Hanford Tank 241-AN-107 at Battelle, Pacific Northwest Division. Batch contact studies were conducted from 4 to 96 hours to determine the sulfate distribution coefficient and reaction kinetics. A small-scale ion exchange column test was conducted to evaluate sulfate removal, loading, breakthrough, and elution from the SL-655. In all of these tests, an archived 241-AN-107 tank waste sample (pretreated to remove Cs, Sr, and transuranics elements) was used. The experimental details and results are described in this report. Under the test conditions, SL-655 was found to have no significant ion exchange affinity for sulfate in this matrix. The batch contact study resulted in no measurable difference in the aqueous sulfate concentration following resin contact (K{sub d} {approximately} 0). The column test also demonstrated SL-655 had no practical affinity for sulfate in the tested matrix. Within experimental error, the sulfate concentration in the column effluent was equal to the concentration in the feed after passing 3 bed volumes of sample through the columns. Furthermore, some, if not all, of the decreased sulfate concentration in these first three column volumes of effluent can be ascribed to mixing and dilution of the 241-AN-107 feed with the interstitial liquid present in the column at the start of the loading cycle. Finally, ICP-AES measurements on the eluate solutions showed the presence of barium as soon as contact with the feed solution is completed. Barium is a metal not detected in the feed solution. Should the loss of barium be correlated with the resin's ability to selectively complex sulfate, then maintaining even the current limited resin characteristics for sulfate complexation over multiple cycles becomes questionable.

DE Kurath; JR Bontha; DL Blanchard; SK Fiskum; BM Rapko

2000-08-23

275

Sulfation of von Willebrand factor  

SciTech Connect

von Willebrand factor (vWF) is a multimeric adhesive glycoprotein essential for normal hemostasis. We have discovered that cultured human umbilical vein endothelial cells incorporate inorganic sulfate into vWF. Following immunoisolation and analysis by polyacrylamide or agarose gel electrophoresis, metabolically labeled vWF was found to have incorporated (35S)-sulfate into all secreted multimer species. The time course of incorporation shows that sulfation occurs late in the biosynthesis of vWF, near the point at which multimerization occurs. Quantitative analysis suggests the presence, on average, of one molecule of sulfate per mature vWF subunit. Virtually all the detectable sulfate is released from the mature vWF subunit by treatment with endoglycosidases that remove asparagine-linked carbohydrates. Sulfated carbohydrate was localized first to the N-terminal half of the mature subunit (amino acids 1 through 1,365) by partial proteolytic digestion with protease V8; and subsequently to a smaller fragment within this region (amino acids 273 through 511) by sequential digestions with protease V8 and trypsin. Thus, the carbohydrate at asparagine 384 and/or 468 appears to be the site of sulfate modification. Sodium chlorate, an inhibitor of adenosine triphosphate-sulfurylase, blocks sulfation of vWF without affecting either the ability of vWF to assemble into high molecular weight multimers or the ability of vWF multimers to enter Weible-Palade bodies. The stability of vWF multimers in the presence of an endothelial cell monolayer also was unaffected by the sulfation state. Additionally, we have found that the cleaved propeptide of vWF is sulfated on asparagine-linked carbohydrate.

Carew, J.A.; Browning, P.J.; Lynch, D.C. (Harvard Medical School, Boston, MA (USA))

1990-12-15

276

Change in ionization of barium in calcium and direct determination of barium in calcium by flame atomic absorption spectrometry using the Ba ion resonance line  

NASA Astrophysics Data System (ADS)

Partial pressures of barium at various concentrations of calcium are calculated, and degree of ionization of barium in the nitrous oxide-acetylene flame are determined experimentally and theoretically using the Saha equation. The ionization of barium (50 ?g ml -1 ) in the presence of 10000 ?g ml -1 of calcium was about one third of the theoretically expected value. Using the ion resonance line of barium permits the direct determination of barium down to 3 ppm in calcium matrices by atomic absorption spectrophotometry.

Takada, Takeo; Satho, Mamoru

277

Barium determination in gastric contents, blood and urine by inductively coupled plasma mass spectrometry in the case of oral barium chloride poisoning.  

PubMed

A serious case of barium intoxication from suicidal ingestion is reported. Oral barium chloride poisoning with hypokalemia, neuromuscular and cardiac toxicity, treated with intravenous potassium supplementation and hemodialysis, was confirmed by the determination of barium concentrations in gastric contents, blood, serum and urine using the inductively coupled plasma mass spectrometry method. Barium concentrations in the analyzed specimens were 20.45 µg/L in serum, 150 µg/L in blood, 10,500 µg/L in urine and 63,500 µg/L in gastric contents. Results were compared with barium levels obtained from a non-intoxicated person. PMID:24794066

Lukasik-G??bocka, Magdalena; Sommerfeld, Karina; Han?, Anetta; Grzegorowski, Adam; Bara?kiewicz, Danuta; Gaca, Micha?; Zieli?ska-Psuja, Barbara

2014-07-01

278

Mixture of sulfate and nitrate in coastal atmospheric aerosols: individual particle studies in Qingdao (36°04?N, 120°21?E), China  

Microsoft Academic Search

Atmospheric aerosol particles were collected at Qingdao (36°04?N, 120°21?E) in October 1996 in order to investigate the characteristics of aerosols in coastal areas of China. Morphologies and element compositions of individual particles were analyzed using a transmission electron microscope and an energy dispersive X-ray spectrometer. Particulate sulfate and nitrate were detected with nitron and barium chloride films pre-coated on the

Daizhou Zhang; Guang-Yu Shi; Yasunobu Iwasaka; Min Hu

2000-01-01

279

Electrooptic and piezoelectric measurements in photorefractive barium titanate and strontium barium niobate  

SciTech Connect

The authors measured the low-frequency (''unclamped'') electrooptic and piezoelectric coefficients in undoped BaTiO/sub 3/ and Sr/sub x/Ba/sub 1-x/Nb/sub 2/O/sub 6/ (chi - 0.61) crystals using interferometric techniques. The contribution of the piezoelectric effect to the Pockels measurement is discussed. For an applied ac electric field in the range 0.1-200 V/cm, the electrooptic and piezoelectric effects are linear in the magnitude of of the applied field and independent of its frequency in the range of 10 Hz-100 kHz. The unclamped electrooptic coefficients of poled BaTiO/sub 3/ single crystals are r/sub 13/ = 19.5 +- 1 pm/V and r/sub 33/ = 97 +- 7 pm/V, and for strontium barium niobate are r/sub 13/ = 47 +- 5 pm/V and r/sub 33/ = 235 +- 21 pm/V, all measured at a wavelength of 514.5 nm and at T = 23/sup 0/C. For the barium titanate samples the measured Pockels coefficient r/sub c/ identical to r/sub 33/ - (n/sub 1//n/sub 3/)/sup 3/r/sub 13/ = 79 +- 6 pm/V in good agreement with the value r/sub c/ = 76 +- 7 pm/V computed from the above values of r/sub 13/ and r/sub 33/, where n/sub 1/ and n/sub 3/ are the ordinary and extraordinary indexes of refraction, respectively. The measured piezoelectric coefficient is d/sub 23/ = +28.7 +- 2 pm/V for barium titanate, and is d/sub 23/ = +24.6 +- 2 pm/V for strontium barium niobate. They also measured the photoreflective coupling of two optical beams in the crystals, and they show that the dependence of the coupling strength on beam polarization is in fair agreement with the measured values of the Pockels coefficients.

Ducharme, S.; Feinberg, J.; Neurgaonkar, R.R.

1987-12-01

280

Preparation of highly dispersed YAG nano-sized powder by co-precipitation method  

Microsoft Academic Search

Yttrium aluminum garnet (YAG) nano-sized powder was synthesized using the co-precipitation method with ammonium hydrogen carbonate as precipitant, octyl polyoxyethylene sulfate sodium as surfactant and glycol as secondary surfactant. The phase evolution of the precursor during calcination at different temperatures was monitored. Results show that only a small amount of the intermediate phase was detected by calcining at 900 °C

Guogang Xu; Xudong Zhang; Wen He; Hong Liu; Hong Li; Robert I. Boughton

2006-01-01

281

Acid precipitation: its role in the alkalization of a lake in Michigan  

Microsoft Academic Search

The watershed of Weber Lake in northern lower Michigan has experienced a nearly 20-fold increase in proton loading from acid precipitation in the past 25 years. But, owing to alkalinity production by biologically mediated processes (nitrate uptake by plants and sulfate reduction by bacteria) and increased rates of carbonate weathering, acid precipitation has doubled the alkalinity, raised the equilibrium pH,

PETER KILHAM

1982-01-01

282

21 CFR 82.3 - Definitions.  

Code of Federal Regulations, 2013 CFR

...precipitated aluminum hydroxide. (h) The term blanc...co-precipitated aluminum hydroxide and barium sulfate. (j) The term mixed oxides means the sum of the quantities of aluminum, iron, calcium, and magnesium...aluminum trioxide, ferric oxide, calcium oxide,...

2013-04-01

283

Glycosaminoglycan sulfation in murine splenocytes  

SciTech Connect

The authors have studied the incorporation of /sup 35/sulfate into glycosaminoglycans (GAG) in splenocytes incubated in medium RPMI 1640 containing 3..mu..M sulfate. Addition of Concanavalin A (Con A) and phorbol 12-myristate 13-acetate (PMA) caused within 24 hr a 10- to 20-fold increase in incorporation into secreted GAG and a 2- to 4-fold increase in cell-retained GAG. PMA added alone caused only 2- to 4-fold increases in both fractions. Between 0 and 3 h however, PMA either alone or with Con A caused a substantial decrease in the incorporation of sulfate into the cellular GAG fraction, suggesting that an immediate effect of these agents is to cause the clearance of nascent GAG chains from the Golgi. The composition of newly sulfated lymphocyte GAG has been found to be approximately 75% chondroitin sulfate and 25% heparan sulfates in both secreted and non-secreted GAG irrespective of the presence of Con A and PMA. Amino column HPLC analysis of disaccharides released by chondroitinase ABC digestion indicates that both ..delta.. Di-4S and ..delta.. Di-6S are produced with the proportion of the latter increasing gradually from initially low levels such that at 24 h, equal proportions of the two are found. Possible mechanisms for this change in the position of sulfation will be discussed.

Rider, C.C.; Hart, G.W.

1986-05-01

284

Leachability of barium-radium sulphate sludges  

SciTech Connect

This paper presents results from the first phase of a research program designed to examine the leachability of radium-226 from barium-radium sulphate sludges. Batch leaching tests were performed. Results showed that liquid:solid contact time was relatively unimportant; radium in the sludge was stable in the presence of deionized water with a slight increase in the amount leached per gram of sludge occurring at higher liquid:solid ratios. Not unexpectedly, low and high values of leachant pH increased radium leaching. Both monovalent and divalent salt solutions also increased leaching; however, dissolved radium-226 activity levels in the leachate decreased as leachant molarity increased. For divalent salts this can be explained by the common ion effect; for monovalent salts it is opposite to results expected from solubility considerations. The interpretation of all results is complicated by the fact that in most tests, the amount of radium-226 present in the leachate was lower than the calculated contribution from the mother liquour present with the sludge. This apparent ability of the sludge to absorb radium from solution may be related to dissolution and reprecipitation of the sludge during the leaching tests.

Huck, P.M.; Anderson, B.

1982-01-01

285

Mononuclear barium diketonate polyamine adducts. Synthesis, structures, and use in MOCVD of barium titanate  

SciTech Connect

Mononuclear barium {beta}-diketonate Lewis base adducts have been synthesized by reaction of Ba(thd){sub 2} (thd = 2,2,6,6-tetramethyl-3,5-heptanedionate) with polyamines 1,1,4,7,7-pentamethyldiethylenetriamine (pmdt) and 1,1,4,7,10,10-hexamethyltriethylenetetramine (hmtt). The adducts [Ba(thd){sub 2}(pmdt)] (I) and [Ba(thd){sub 2}(hmtt)] (II) have been characterized by NMR spectroscopy, elemental analyses and single-crystal X-ray diffraction. Compound I crystallizes in the space group P2{sub 1}/c with a = 10.577(3) {angstrom}, b = 23.547(7) {angstrom}, c = 15.963(5) {angstrom}, {beta} = 105.21(2){degrees}, and Z = 4. Compound II crystallizes in the space group P2{sub 1}/c with a = 10.833(6) {angstrom}, b = 20.442(12) {angstrom}, c = 19.404(9) {angstrom}, {beta} = 104.35(4){degrees}, and Z = 4. The adducts are seven- and eight-coordinate, respectively, with all nitrogen atoms of the polyamine bound to a single barium center. Compound I has been used for thin-film growth of BaTiO{sub 3} which has revealed that, compared to Ba(thd){sub 2}(tetraglyme), the polyamine adduct allows a larger temperature window for effective vapor transport. 10 refs., 2 figs., 2 tabs.

Gardiner, R.A.; Gordon, D.C.; Stauf, G.T.; Vaartstra, B.A. [Advanced Technology Materials Inc., Danbury, CT (United States); Ostrander, R.L.; Rheingold, A.L. [Univ. of Delaware, Newark, DE (United States)

1994-11-01

286

21 CFR 201.304 - Tannic acid and barium enema preparations.  

Code of Federal Regulations, 2013 CFR

...widespread practice for tannic acid to be added to barium enemas...X-ray pictures. Tannic acid is capable of causing diminished...medical literature reports a number of deaths associated with the addition of tannic acid to barium enemas....

2013-04-01

287

Structural diversity of N-sulfated heparan sulfate domains: distinct modes of glucuronyl C5 epimerization, iduronic acid 2-O-sulfation, and glucosamine 6-O-sulfation.  

PubMed

The N-sulfated regions (NS domains) represent the modified sequences of heparan sulfate chains and mediate interactions of the polysaccharide with proteins. We have investigated the relationship between the type/extent of polymer modification and the length of NS domains in heparan sulfate species from human aorta, bovine kidney, and cultured NMuMG and MDCK cells. C5 epimerization of D-glucuronic acid to L-iduronic acid was found to be extensive and essentially similar in all heparan sulfate species studied, regardless of domain size, whereas the subsequent 2-O-sulfation of the formed iduronic acid residues varies appreciably. In aorta heparan sulfate, up to 90% of the formed iduronate residues were 2-O-sulfated, whereas in kidney heparan sulfate 2-O-sulfation occurred only in sulfation was consistently increased with increasing NS domain length, suggesting a correlation between 2-O-sulfation efficiency and length of the polymeric substrate during heparan sulfate biosynthesis. By contrast, 6-O-sulfation of glucosamine units did not correlate to domain size. 6-O-Sulfation exceeded 2-O-sulfation in NS domains from kidney heparan sulfate, but was very low in aorta heparan sulfate. Remarkably, total O-sulfation of NS domains, i.e., the sum of 2-O- and 6-O-sulfate groups, was highly similar in all heparan sulfate samples investigated. The results reveal marked tissue-specific variation in the sulfation patterns of NS domains and indicate previously unrecognized distinctions in the coordination of the three polymer modification reactions during heparan sulfate biosynthesis. PMID:10978168

Safaiyan, F; Lindahl, U; Salmivirta, M

2000-09-01

288

Creating unstable velocity-space distributions with barium injections  

SciTech Connect

Large Debye lengths relative to detector dimensions and the absence of confining walls makes space an attractive laboratory for studying fundamental theories of plasma instabilities. However, natural space plasmas are rarely found displaced from equilibrium enough to permit isolation and diagnosis of the controlling parameters and driving conditions. Furthermore, any plasma or field response to the departure from equilibrium can be masked by noise in the natural system. Active experiments provide a technique for addressing the chicken or egg dilemma. Early thermite barium releases were generally conducted at low altitudes from sounding rockets to trace electric fields passively or to study configuration-space instabilities. One can also study velocity-space instabilities with barium releases. Neutral barium vapor releases wherein a typical speed greatly exceeds the thermal speed can be used to produce barium ion velocity-space distributions that should be subject to a number of microinstabilities. We examine the ion velocity-space distributions resulting from barium injections from orbiting spacecraft and shaped-charges.

Pongratz, M.B.

1983-01-01

289

Acceleration of barium ions near 8000 km above an aurora  

NASA Technical Reports Server (NTRS)

A barium shaped charge, named Limerick, was released from a rocket launched from Poker Flat Research Range, Alaska, on March 30, 1982, at 1033 UT. The release took place in a small auroral breakup. The jet of ionized barium reached an altitude of 8100 km 14.5 min after release, indicating that there were no parallel electric fields below this altitude. At 8100 km the jet appeared to stop. Analysis shows that the barium at this altitude was effectively removed from the tip. It is concluded that the barium was actually accelerated upward, resulting in a large decrease in the line-of-sight density and hence the optical intensity. The parallel electric potential in the acceleration region must have been greater than 1 kV over an altitude interval of less than 200 km. The acceleration region, although presumably auroral in origin, did not seem to be related to individual auroral structures, but appeared to be a large-scale horizontal structure. The perpendicular electric field below, as deduced from the drift of the barium, was temporally and spatially very uniform and showed no variation related to individual auroral structures passing through.

Stenbaek-Nielsen, H. C.; Hallinan, T. J.; Wescott, E. M.; Foeppl, H.

1984-01-01

290

Phenotypic and Behavioral Defects Caused by Barium Exposure in Nematode Caenorhabditis elegans  

Microsoft Academic Search

To examine the possible phenotypic defects from barium exposure, a model organism, Caenorhabditis elegans, was chosen to analyze the multiple toxicities in barium-exposed animals. Endpoints of life span, body size, brood size,\\u000a generation time, head thrash, and body bend were selected for the assessment of barium toxicity. High concentrations (75 ?M\\u000a and 200 ?M) of barium exposure caused severe life-span defects. Body

D.-Y. Wang; Y. Wang

2008-01-01

291

Barium Aspiration in an Infant: A Case Report and Review of Management  

PubMed Central

We describe a case of bilateral inhalation of barium in an infant following a barium swallow for investigation of dusky spells associated with feeds. A bronchoscopy subsequently revealed the presence of a mid-tracheal tracheo-esophageal cleft. To date, little has been reported on barium aspiration in children and there is no consensus for management. We review the literature on barium aspiration, its consequences, and make recommendations for management.

Jackson, M.; Kapur, N.; Goyal, V.; Choo, K.; Sarikwal, A.; Masters, I. B.; Isles, Alan F.

2014-01-01

292

Minerals Yearbook, 1990: Sodium Sulfate.  

National Technical Information Service (NTIS)

Sodium sulfate is produced from natural sources or recovered as a byproduct from various manufacturing processes and has several important and useful applications in various consumer products. In a survey of the top 50 basic organic and inorganic chemical...

D. S. Kostick

1990-01-01

293

Minerals Yearbook, 1991: Sodium Sulfate.  

National Technical Information Service (NTIS)

U.S. natural and synthetic sodium sulfate production and consumption decreased 44% and 48%, respectively, from those of 1980 to 1991. The decreases were because of changes in the recovery operations of consuming industries mandated by environmental legisl...

D. S. Kostick

1992-01-01

294

Influnce of the solar radiation extinction by sulfate aerosol on climate  

NASA Astrophysics Data System (ADS)

Annual geographical distribution of sulfate aerosol concentrations after Langner and Rodhe (1991) were prescribed and found to be consistent with the observed sulfate aerosol concentrations in the atmosphere and in precipitation over polluted regions in Europe and North America. Radiative properties of sulfate were provided by Kiehl and Brie gleb (1993). Difference between net radiation at top with and without aerosol is radiative forcing by aerosol. Maximum negative radiative forcing by anthropogenic sulfate was located in Europe, East China, South East US and central Africa. Radiative forcing by natural sulfate predominantly located over oceans. Magnitude of radiative forcing by natural sulfate is much less than anthropogenic. Radiative forcing by anthropogenic is larger in Northern hemisphere than in Southern hemisphere Conversely, radiative forcing by natural sulfate is larger in Southern hemisphere than in Northern hemisphere. Vertical distribution on global bases indicates that sulfate is mainly between surface and 550 mb level. Our paper discuss the distribution of the global and hemispheric mean radiative forcing in comparison with distributions for many authors. Global mean radiative forcing anthropogenic and total aerosol is of greater values than those of Kiehl and Briegleb, smaller than Charlson et al and smaller than anthropogenic forcing of Taylor and Penner. Pattern of Global anthropogenic forcing between Northern hemisphere and Southern hemisphere is close to that obtained by Kiehl and Briegleb and less asymmetric than those by Charlson et al.

Mosalam Shaltout, M. A.; Ghoneim, M. M. S.; El Sayed, A. Y.

295

Bacterially Induced Dolomite Formation in the Presence of Sulfate Ions under Aerobic Conditions  

NASA Astrophysics Data System (ADS)

The origin of dolomite remains a long-standing enigma in sedimentary geology because, although thermodynamically favorable, precipitation of dolomite from modern seawater does not occur. Experiments conducted at elevated temperatures (200 oC) indicated that the presence of small concentrations of sulfate ions inhibits the transformation of calcite to dolomite [1]. Indeed, sulfate ions appeared to inhibit dolomite formation above 2 mM concentration (versus 28 mM in modern seawater). Recently, culture experiments have demonstrated that sulfate-reducing bacteria mediate the precipitation of dolomite at Earth surface conditions in the presence of sustained sulfate ion concentrations [2,3]. Additionally, in a number of modern hypersaline environments, dolomite forms from solutions with high sulfate ion concentrations (2 to 70 times seawater). These observations suggest that the experimentally observed sulfate-ion inhibition [1] may not apply to all ancient dolomite formation. Here, we report aerobic culture experiments conducted at low temperatures (25 and 35 oC) and variable sulfate ion concentrations (0, 0.5, 1 and 2 x seawater values) using moderately halophilic bacteria, Halomonas meridiana. After an incubation period of 15 days, experiments at 35 oC with variable sulfate ion concentrations (0, 0.5 x and seawater values) contained crystals of Ca-dolomite and stochiometric dolomite. The experiment at 35 oC with 2 x seawater sulfate ion concentration produced dolomite crystals after 20 days of incubation. In a parallel set of experiments at 25 oC, precipitation of dolomite was observed after 25 days of incubation in cultures with variable sulfate ion concentrations (0, 0.5 x and seawater values). In the culture with 2 x seawater sulfate ion concentration, dolomite crystals were observed after 30 days. Our study demonstrates that halophilic bacteria (or heterotrophic microorganisms), which do not require sulfate ions for metabolism, can mediate dolomite precipitation in the presence of sulfate ions. Apparently, microbial dolomite precipitation is not intrinsically linked to any particular group of organisms or specific metabolic processes or even specific environment. Furthermore, because heterotrophic microorganisms appear to be able to mediate microbial dolomite precipitation with or without sulfate ions in the media, our results indicate that the kinetic inhibition effect of sulfate ions can be overcome under specific sedimentary conditions. The present study adds a new insight to the dolomite problem, which could lead to a better clarification of the mechanism(s) involved in the massive dolomite formation observed in the geological record. References: [1] Baker, P.A., and Kastner, M., (1981), Science, 213, 214-216. [2] Vasconcelos, C., McKenzie, J.A., Bernasconi, S., Grujic, D. and Tien, A.J., (1995), Nature 377, 220-222.. [3] Warthmann R., van Lith Y., Vasconcelos C., McKenzie J.A. and Karpoff A.M., (2000), Geology 28, 1091-1094.

Sanchez-Roman, M.; McKenzie, J. A.; Vasconcelos, C.; Rivadeneyra, M.

2005-12-01

296

49 CFR 173.182 - Barium azide-50 percent or more water wet.  

Code of Federal Regulations, 2010 CFR

...2009-10-01 2009-10-01 false Barium azide-50 percent or more water wet. 173.182...Than Class 1 and Class 7 § 173.182 Barium azideâ50 percent or more water wet. Barium azideâ50 percent or more water wet, must be...

2009-10-01

297

49 CFR 173.182 - Barium azide-50 percent or more water wet.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false Barium azide-50 percent or more water wet. 173.182...Than Class 1 and Class 7 § 173.182 Barium azideâ50 percent or more water wet. Barium azideâ50 percent or more water wet, must be...

2010-10-01

298

Discrete barite particles and barium as tracers of paleoproductivity in South Atlantic sediments  

Microsoft Academic Search

Geochemical analyses as well as X ray diffraction measurements were carried out on five sediment cores from the eastern Angola Basin and the equatorial divergence of the South Atlantic. Barite concentrations were calculated from total barium concentrations by subtracting the estimated barium background supplied by ``nonbarite'' barium carriers. Barite concentrations assessed by this geochemical method show a good correspondence to

Franz Gingele; Andreas Dahmke

1994-01-01

299

The biological production of marine suspended barite and the barium cycle in the Western Mediterranean Sea  

Microsoft Academic Search

Suspended particulate barium was measured in the Western Mediterranean along 4 profiles sampled during the PHYCEMED 1 cruise in 1981. The non-terrigenous fraction of particulate barium (i.e. excess Ba; Baxs) can account for up to 96% of total barium. This fraction follows the barite settling and dissolution rate model we described earlier for the Atlantic Ocean, confirming barite as the

F. DEHAIRSI; C. E. Lambert; R. Chesselet; N. Risler

1987-01-01

300

Atomic force microscopy studies of twins in yttrium-doped barium titanate  

Microsoft Academic Search

Barium titanate is the main constituent of PTC materials and their electric properties are sensitive to microstructure and defects, in atomic scale, that are significantly affected by processing parameters. The microstructure of barium titanate doped with yttrium was investigated using topographic images obtained by AFM in contact mode. The AFM images of barium titanate doped with yttrium showed the effect

Simoni Maria Gheno; Haroldo Lhou Hasegawa; Pedro Iris Paulin Filho

2006-01-01

301

40 CFR 721.10010 - Barium manganese oxide (BaMnO3).  

Code of Federal Regulations, 2010 CFR

...2009-07-01 2009-07-01 false Barium manganese oxide (BaMnO3). 721.10010...Chemical Substances § 721.10010 Barium manganese oxide (BaMnO3 ). (a...The chemical substance identified as barium manganese oxide (BaMnO3 )...

2009-07-01

302

40 CFR 721.10010 - Barium manganese oxide (BaMnO3).  

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 false Barium manganese oxide (BaMnO3). 721.10010...Chemical Substances § 721.10010 Barium manganese oxide (BaMnO3). (a...The chemical substance identified as barium manganese oxide (BaMnO3 )...

2010-07-01

303

Fluid seepage along the San Clemente Fault scarp: basin-wide impact on barium cycling  

Microsoft Academic Search

Material fluxes associated with fluid expulsion at cold seeps and their contribution to oceanographic budgets have not been accurately constrained. Here we present evidence that the barium released at cold seeps along the San Clemente Fault zone may significantly impact the geochemical budget of barium within the basin. Barium fluxes at seep localities on the fault scarp, measured with benthic

Marta E. Torres; James McManus; Chih-An Huh

2002-01-01

304

The Use of Seaweed and Sugarcane Bagasse for the Biological Treatment of Metal-contaminated Waters Under Sulfate-reducing Conditions  

Microsoft Academic Search

When wetlands reach maximum treatment capacity to remove heavy metals, removal can still take place through precipitation\\u000a as sulfide because of the biological reduction of sulfate. To achieve this goal, anaerobic conditions must be attained, a\\u000a sulfate source must exist, and an adequate substrate for sulfate-reducing bacteria (SRB) is also required. In the present\\u000a work, two ligneous-cellulosic materials, a brown

Márcia Monteiro Machado Gonçalves; Luiz Antonio de Oliveira Mello; Antonio Carlos Augusto Costa

305

The Use of Seaweed and Sugarcane Bagasse for the Biological Treatment of Metal-contaminated Waters Under Sulfate-reducing Conditions  

Microsoft Academic Search

When wetlands reach maximum treatment capacity to remove heavy metals, removal can still take place through precipitation\\u000a as sulfide because of the biological reduction of sulfate. To achieve this goal, anaerobic conditions must be attained, a\\u000a sulfate source must exist, and an adequate substrate for sulfate-reducing bacteria (SRB) is also required. In the present\\u000a work, two ligneous-cellulosic materials, a brown

Márcia Monteiro Machado Gonçalves; Luiz Antonio de Oliveira Mello; Antonio Carlos Augusto da Costa

2008-01-01

306

The effect of acid rain and altitude on concentration, ? 34S, and ? 18O of sulfate in the water from Sudety Mountains, Poland  

Microsoft Academic Search

The analyses of sulfate content, ?34S and ?18O of dissolved sulfate, and ?18O of water were carried out in a 14 km2 crystalline massif located in the Sudety Mountains (SW Poland) to 1) assess the amount of the sulfate delivered to the surface and groundwater systems by modern atmospheric precipitation, 2) determine the effect of altitude on these parameters, and 3)

Anna Szynkiewicz; Magdalena Modelska; Mariusz Orion J?drysek; Maria Mastalerz

2008-01-01

307

Synthesis of nano-sized and highly sinterable Nd:YAG powders by the urea homogeneous precipitation method  

Microsoft Academic Search

Neodymium-doped yttrium aluminum garnet (Nd:YAG) nanopowders were synthesized via the urea homogeneous precipitation method. The morphology and sintering property controlling effects of ammonium sulfate and urea during the synthesis process were discussed. Spawn-like and fibrillar precipitates were obtained without and with sulfate ions, respectively. Dispersive Nd:YAG nanopowder with proper sintering property was obtained with 1273K calcination for 2h from the

Yaohui Lv; Wei Zhang; Hong Liu; Yuanhua Sang; Haiming Qin; Jie Tan; Liuniu Tong

308

Spectroscopy and dynamics of barium-doped helium nanodroplets  

NASA Astrophysics Data System (ADS)

Excitation spectra up to the ionization threshold are reported for barium atoms located on the surface of helium nanodroplets. For states with low principal quantum number, the resonances are substantially broadened and shifted towards higher energy with respect to the gas phase. This has been attributed to the repulsive interaction of the excited atom with the helium at the Franck-Condon region. In contrast, for states with high principal quantum number the resonances are narrower and shifted towards lower energies. Photoelectron and ZEKE spectroscopy reveal that the redshift results from a lowering of the ionization threshold due to polarization of the helium by the barium ionic core. As a result of the repulsive interaction with the helium, excited barium atoms desorb from the surface of the droplets. Only when excited to the 6s6p 1P1 state, which reveals an attractive interaction with the helium, the atoms remain attached to the droplets.

Loginov, Evgeniy; Drabbels, Marcel

2012-04-01

309

CLOUD AND CHEMICAL PATHWAY CHARACTERIZATION OF THE NONLINEAR RESPONSE OF SULFUR DEPOSITION AND SULFATE AIR CONCENTRATIONS TO CHANGES IN SO2 EMISSIONS IN THE RADM  

EPA Science Inventory

The aqueous-phase chemistry that occurs in both precipitating and nonprecipitating clouds provides a major mechanism for the conversion of S02 to sulfate in the troposphere. ccording to the Regional Acid Deposition Model (RADM), cloud production of sulfate dominates over gas-phas...

310

Steady-state interstitial water sulfate O-18/O-16 ratios as a function of salinity  

NASA Astrophysics Data System (ADS)

At ambient temperature and pH dissolved sulfate does not exchange isotopes with water to significant extent over millions of years. However, due to the formation of intermediate sulphur species during dissimilatory sulfate reduction, fast isotope exchange is observed under microbial mediation. The catalyzed oxygen isotope exchange between pore water sulfate and intracellular water upon sulfate reduction leads to the development of steady-state values for dissolve sulfate. At the same degrees of microbial conversion, sulfur isotope ratios may still proceed to increase due to continuous net sulfate reduction. Whereas the initial ratio of d34S-d18O variations in dissolved sulfate is controlled by metabolic rates (e.g., cellular sulfate reduction rates), the balance between sulfate reduction and sulphide oxidation, and the isotopic composition of cellular water, the steady state value is controlled only by oxygen isotope exchange with water. Although the exact relationship between measured steady-state values and equilibrium is still under debate, an ultimate control by both temperature and the oxygen isotope composition of water is expected. The latter is related to salinity and climate zone. In this study we show the results from interstitial waters obtained at different natural localities covering a wide range of salinity regimes and benthic metabolic rates. Sites include brackish coastal and euxinic systems in the Baltic Sea and the Black Sea, coastal sediments of the North Sea, and deep marine pore waters from the Mediterranean and the Pacific (ODP Legs 160, 161, 182, 201). Results are compared to previous findings by Fritz et al. (1989) on groundwaters and experimental studies by Mizutani & Rafter (1973). The field examples show that the pore waters reach steady-state values depending on the isotopic values of pore waters, and the rates can vary strongly with microbial activity in the specific setting. If conditions allow diagenetic barites to be formed in these environments at the diffusional sulfate-barium interface, these authigenic phases have the potential to serve as proxies for pore water salinity.

Wortmann, U. G.; Böttcher, M. E.; Blake, R. M.; Bernasconi, S. M.

2009-12-01

311

Compact pulse forming line using barium titanate ceramic material.  

PubMed

Ceramic material has very high relative permittivity, so compact pulse forming line can be made using these materials. Barium titanate (BaTiO(3)) has a relative permittivity of 1200 so it is used for making compact pulse forming line (PFL). Barium titanate also has piezoelectric effects so it cracks during high voltages discharges due to stresses developed in it. Barium titanate is mixed with rubber which absorbs the piezoelectric stresses when the PFL is charged and regain its original shape after the discharge. A composite mixture of barium titanate with the neoprene rubber is prepared. The relative permittivity of the composite mixture is measured to be 85. A coaxial pulse forming line of inner diameter 120 mm, outer diameter 240 mm, and length 350 mm is made and the composite mixture of barium titanate and neoprene rubber is filled between the inner and outer cylinders. The PFL is charged up to 120 kV and discharged into 5 ? load. The voltage pulse of 70 kV, 21 ns is measured across the load. The conventional PFL is made up of oil or plastics dielectrics with the relative permittivity of 2-10 [D. R. Linde, CRC Handbook of Chemistry and Physics, 90th ed. (CRC, 2009); Xia et al., Rev. Sci. Instrum. 79, 086113 (2008); Yang et al., Rev. Sci. Instrum. 81, 43303 (2010)], which increases the length of PFL. We have reported the compactness in length achieved due to increase in relative permittivity of composite mixture by adding barium titanate in neoprene rubber. PMID:22129008

Kumar Sharma, Surender; Deb, P; Shukla, R; Prabaharan, T; Shyam, A

2011-11-01

312

Compact pulse forming line using barium titanate ceramic material  

NASA Astrophysics Data System (ADS)

Ceramic material has very high relative permittivity, so compact pulse forming line can be made using these materials. Barium titanate (BaTiO3) has a relative permittivity of 1200 so it is used for making compact pulse forming line (PFL). Barium titanate also has piezoelectric effects so it cracks during high voltages discharges due to stresses developed in it. Barium titanate is mixed with rubber which absorbs the piezoelectric stresses when the PFL is charged and regain its original shape after the discharge. A composite mixture of barium titanate with the neoprene rubber is prepared. The relative permittivity of the composite mixture is measured to be 85. A coaxial pulse forming line of inner diameter 120 mm, outer diameter 240 mm, and length 350 mm is made and the composite mixture of barium titanate and neoprene rubber is filled between the inner and outer cylinders. The PFL is charged up to 120 kV and discharged into 5 ? load. The voltage pulse of 70 kV, 21 ns is measured across the load. The conventional PFL is made up of oil or plastics dielectrics with the relative permittivity of 2-10 [D. R. Linde, CRC Handbook of Chemistry and Physics, 90th ed. (CRC, 2009); Xia et al., Rev. Sci. Instrum. 79, 086113 (2008); Yang et al., Rev. Sci. Instrum. 81, 43303 (2010)], which increases the length of PFL. We have reported the compactness in length achieved due to increase in relative permittivity of composite mixture by adding barium titanate in neoprene rubber.

Kumar Sharma, Surender; Deb, P.; Shukla, R.; Prabaharan, T.; Shyam, A.

2011-11-01

313

Could binary mixture of Nd-Ni ions control the electrical behavior of strontium-barium M-type hexaferrite nanoparticles?  

SciTech Connect

Research highlights: {yields} Strontium-barium hexaferrites (Sr{sub 0.5}Ba{sub 0.5}Fe{sub 12}O{sub 19}) in single magnetoplumbite phase solid structure are synthesized by the co-precipitation method. {yields} Structural and electrical properties of Nd-Ni substituted ferrites are investigated. {yields} These ferrite materials possess high electrical resistivity (108 {Omega} cm) that is essential to curb the eddy current loss, which is pre-requisite for surface mount devices. -- Abstract: Cationic substitution in M-type hexaferrites is considered to be an important tool for modification of their electrical properties. This work is part of our comprehensive study on the synthesis and characterization of Nd-Ni doped strontium-barium hexaferrite nanomaterials of nominal composition Sr{sub 0.5}Ba{sub 0.5-x}Nd{sub x}Fe{sub 12-y}Ni{sub y}O{sub 19} (x = 0.00-0.10; y = 0.00-1.00). Doping with this binary mixture modulates the physical and electrical properties of strontium-barium hexaferrite nanoparticles. Structural and electrical properties of the co-precipitated ferrites are investigated using state-of-the-art techniques. The results of X-ray diffraction analysis reveal that the lattice parameters and cell volume are inversely related to the dopant content. Temperature dependent DC-electrical resistivity measurements infer that resistivity of strontium-barium hexaferrites decreases from 1.8 x 10{sup 10} to 2.0 x 10{sup 8} {Omega} cm whereas the drift mobility, dielectric constant and dielectric loss tangent are directly related to the Nd-Ni content. The results of the study demonstrate a relationship between the modulation of electrical properties of substituted ferrites and nature of cations and their lattice site occupancy.

Iqbal, Muhammad Javed, E-mail: mjiqauchem@yahoo.com [Surface and Solid State Chemistry Laboratory, Department of Chemistry, Quaid-i-Azam University, Islamabad 45320 (Pakistan); Farooq, Saima [Surface and Solid State Chemistry Laboratory, Department of Chemistry, Quaid-i-Azam University, Islamabad 45320 (Pakistan)] [Surface and Solid State Chemistry Laboratory, Department of Chemistry, Quaid-i-Azam University, Islamabad 45320 (Pakistan)

2011-05-15

314

In vitro and in vivo selectin-blocking activities of sulfated lipids and sulfated sialyl compounds  

Microsoft Academic Search

There is accumulating evidence that sulfated lipids, sulfated oligosaccharides and other sulfated compounds are reactive with selectins in a manner that interferes with selectin interactions with their natural ligands. In the report we describe the ability of sulfated lipids (sulfatides and gangliosides) and multimeric forms of sulfated sialic acid to block binding of P- and E-selectin-Ig to neutrophils. The in

Michael S. Mulligan; Roscoe L. Warner; John B. Lowe; Peter L. Smith; Yasuo Suzuki; Masayuki Miyasaka; Shinya Yamaguchi; Yasuhiro Ohta; Yoji Tsukada; Makoto Kiso; Akira Hasegawa; Peter A. Ward

1998-01-01

315

Ionization and expansion of barium clouds in the ionosphere  

NASA Technical Reports Server (NTRS)

A recently envelope 3D model is used here to study the motion of the barium clouds released in the ionosphere, including the ionization stage. The ionization and the expansion of the barium clouds and the interaction between the clouds and the background ions are investigated using three simulations: a cloud without a directional velocity, a cloud with an initial velocity of 5 km/s across the B field, and a cloud with initial velocity components of 2 km/s both along and across the B field.

Ma, T.-Z.; Schunk, R. W.

1993-01-01

316

Barium bismuth oxides with ?-, ?-, and ?-Bi 2 O 3 structures  

Microsoft Academic Search

Three new barium bismuth oxides have been synthesized containing 2.15–2.72 mol % BaO with the integer composition BaBi39O59.5, BaBi46O70, and BaBi40O61 and a monoclinic, cubic, and triclinic structure, respectively. These double oxides are, likely, derivatives of ?-, ?-, and\\u000a ?-Bi2O3 phases. The effects of the crucible material and surrounding atmosphere on the course of the synthesis of these new barium

L. A. Klinkova; V. I. Nikolaichik; N. V. Barkovskii; V. K. Fedotov

2007-01-01

317

Characterization of solid bitumens originating from thermal chemical alteration and thermochemical sulfate reduction  

Microsoft Academic Search

Solid bitumen can arise from several reservoir processes acting on migrated petroleum. Insoluble solid organic residues can form by oxidative processes associated with thermochemical sulfate reduction (TSR) as well as by thermal chemical alteration (TCA) of petroleum. TCA may follow non-thermal processes, such as biodegradation and asphaltene precipitation, that produce viscous fluids enriched in polar compounds that are then altered

Simon R. Kelemen; Clifford C. Walters; Peter J. Kwiatek; Howard Freund; Mobae Afeworki; Michael Sansone; William A. Lamberti; Robert J. Pottorf; Hans G. Machel; Kenneth E. Peters; Trudy Bolin

2010-01-01

318

Protamine precipitation of two reovirus particle types from polluted waters.  

PubMed

Two forms of virus particle are released from reovirus-infected cell cultures, infectious reovirus and potentially infectious reovirus (PIV). PIV particle forms have a complete outer coat and are not infectious until the outer coat is altered or removed. The PIV concentration in polluted waters, however, has not been determined. Protamine sulfate precipitation, using 0.25% fetal bovine serum and 0.005% protamine sulfate for the first precipitation of the sample and 0.0025% for the second, was employed to concentrate infectious reovirus and PIV from water and sewage. Infectious reovirus and PIV particles were concentrated over 500-fold from river water inoculated with virus, and virus recoveries of between 80 and 100% were achieved. Virus precipitates stored at -20 degrees C as a protamine-virus concentrate showed a 5% loss of PIV after 14 days. Virus preparations were assayed, before and after treatment, with 200 micrograms of chymotrypsin per ml, using a fluorescent-antibody procedure. Protamine sulfate precipitation and fluorescent-antibody detection are effective ways to recover and assay reoviruses present in raw sewage. PMID:7138002

Adams, D J; Ridinger, D N; Spendlove, R S; Barnett, B B

1982-09-01

319

Synthesis and Properties of Barium Titanate Nanocomposites.  

NASA Astrophysics Data System (ADS)

Electrical properties of BaTiO_3 /liquid composites were investigated. The main thesis objectives were as follows: (1) synthesis of high purity, nanometer-sized BaTiO_3; (2) characterization of the room temperature BaTiO _3 phase as a function of temperature; (3) to evaluate the possibilities of using BaTiO_3 in electrorheological (ER) fluids with both AC and DC fields; and (4) to determine the effects of AC and DC fields on agglomerate fibril formation by using optical microscopy. Powders produced by coprecipitation methods (TAM HPB) and hydrothermal techniques were evaluated in this research. Hydrothermal synthesis in the barium hydroxide octahydrate (BHO) and titanium isopropoxide (TI) system was extensively examined. It was determined that feedstock pH 12 was required for hydrothermal synthesis to ensure proper crystallinity of the resultant powder. The specific surface area increased linearly from 6.7m^2 /g to 14.3m^2/g with increased feedstock concentrations from 0.15M to 1.0M. This change in feedstock concentration also resulted in a drastic change in particle morphology. Particles produced at low feedstock concentrations were large, textured aggregates (5.0 ?m) produced from small crystallites (0.1 ?m). Particles produced at high feedstock concentrations (designated as BTH8) possessed a hexagonal platelet structure which grew slowly along < 111> and rapidly along < 211>. Particle size effects on the room temperature phase were successfully evaluated, as a function of temperature, with X-ray diffraction and dielectric measurements. It was found that the particle possessed the tetragonal phase at room temperature for 700A particles. The phase transition from cubic to tetragonal appeared at 120^ circC for this particle size. TAM HPB and BTH8 both showed an ER response (AC and DC fields) when suspended in silicone oil. The TAM HPB suspension showed a greater ER effect due to the larger particle size. All suspensions were frequency dependent with an optimal range of 20-100Hz. The viscosity of the BTH8 suspension dropped off rapidly above an applied field DC of 6.25kV/cm due to turbulent overturn.

Miller, David Vernon

320

Abundances of 12 metal-rich barium stars (Pereira+, 2011)  

NASA Astrophysics Data System (ADS)

The table contains equivalent width measurements for each individual line of the adopted line list, and the corresponding line parameters. The data analysed consist of FEROS@2.2m spectra of 12 barium stars. The resolution is of about R=45 000, which covers the range from 4500 to 9500Å, which include all the lines analysed. (3 data files).

Pereira, C. B.; Sales Silva, J. V.; Chavero, C.; Roig, F.; Jilinkski, E.

2011-07-01

321

HEALTH EFFECTS OF HUMAN EXPOSURE TO BARIUM IN DRINKING WATER  

EPA Science Inventory

The overall objective of this study was to examine by epidemiologic and supportive laboratory studies, the human health effects associated with ingestion of barium in drinking water exceeding the U.S. drinking water standard of 1.0 mg/l. The incidence of cardiovascular mortality ...

322

PROPOSED ORAL REFERENCE DOSE (RFD) FOR BARIUM AND COMPOUNDS  

EPA Science Inventory

The Integrated Risk Information System (IRIS) is a database of EPA's consensus opinion of the human health effects that may result from exposure to various substances found in the environment. A Toxicological Review and IRIS Summary were prepared for barium and compounds in 1998 ...

323

REMOVING BARIUM AND RADIUM THROUGH CALCIUM CATION EXCHANGE  

EPA Science Inventory

The removal of barium (Ba) and radium (Ra), which are found in many groundwater sources, was achieved in laboratory studies with an ion exchange process. In the studies, a strong acid resin in the calcium form effectively removed Ba(+2) and Ra (+2) to meet standards. The resin wa...

324

Removal of barium and radium from groundwater. Environmental research brief  

SciTech Connect

A research project was undertaken to investigate processes for removing barium and radium from drinking water. Special emphasis was placed on ion exchange processes that can be used without adding large concentrations of sodium to the water. The wastes from radium and barium removal processes were also characterized, and processes suitable for treatment of ion-exchange brines were evaluated. The report discusses two ion-exchange processes that can be used for barium and radium removal accompanied by either partial or no hardness removal. The calcium-form, strong-acid ion-exchange resin can be used for barium and radium removal without significant change in hardness or the concentration of other salts. This resin can be regenerated with CaC1/sub 2/ brine. The radium-selective complexer (RSC) will remove radium without altering hardness or other salt concentration. The capacity of this resin for waters with low total dissolved solids (TDS) (<1000 to 2000 mg/L TDS) is in excess of 30,000 pCi/dry g; however, if the TDS is increased to about 40,000 mg/L, the capacity drops to 200 to 300 pCi/dry g. Thus using this resin to remove radium from spent brine does not appear feasible.

Snoeyink, V.L.; Chambers, C.C.; Schmidt, C.K.; Manner, R.F.; Myers, A.G.

1987-02-01

325

Emission Fluctuations of Tungsten-Based Barium Dispenser Cathodes  

Microsoft Academic Search

Emission fluctuations in five different types of tungsten-based barium dispenser cathodes have been measured as functions of both frequency and current density. Two of the cathodes were of the L variety and the remainder of the ``impregnated'' variety. The L cathode spectra show that the emission fluctuations are caused by fluctuations in the number of adsorbed atoms on the tungsten

I. Brodie

1961-01-01

326

Effects of energetic ions on barium strontium titanate crystals  

Microsoft Academic Search

The effects of energetic ions on barium strontium titanate (BST) single crystals have been studied using low-energy He and high-energy Si ions. This investigation indicates that energetic ions significantly change the ferroelectric properties of BST single crystals. While He ion causes sharp increase in dielectric constant, Curie temperature (Tc) and spontaneous polarization (Ps), the Si ions cause slight change in

R. Varatharajan; P. Jayavel; J. Kumar; R. Jayavel; K. Asokan

2000-01-01

327

Measurement of carbon contamination in barium strontium titanate films  

Microsoft Academic Search

Ferroelectric films are being developed for use in DRAMs. The films are often manufactured using spin-on techniques making contamination with residual carbon inevitable. The concentration of carbon is rarely known and its effect not understood. This paper describes the analysis of barium strontium titanate (BST) films for carbon content using both Mass and Energy Dispersive Recoil Spectrometry (RS) with 77

Warren B. Stannard; Peter N. Johnston; James F. Scott; Ian F. Bubb; R. Walker; David D. Cohen; Nick Dytlewski; Jarrod W. Martin

1995-01-01

328

Barium strontium titanate powders prepared by spray pyrolysis  

Microsoft Academic Search

Ultasonic spray pyrolysis (SP) has been investigated for the production of the barium strontium titanate (BST) powders from the polymeric precursors. The processing parameters, such as flux of aerosol and temperature profile inside the furnace, were optimized to obtain single phase BST. The powders were characterized by the methods of X-ray diffraction analysis, SEM, EDS and TEM. The obtained powders

G. Brankovi?; Z. Brankovi?; M. S. Góes; C. O. Paiva-Santos; M. Cilense; J. A. Varela; E. Longo

2005-01-01

329

BARIUM AND RADIUM REMOVAL FROM GROUNDWATER BY ION EXCHANGE  

EPA Science Inventory

The primary objective of this study was to determine the applicability of weak acid exchange resin in the hydrogen form for removal of hardness, barium and radium from groundwater. Weak acid resin in the hydrogen form eliminates the addition of sodium to drinking water. The capac...

330

BARIUM AND RADIUM IN WATER TREATMENT PLANT WASTES  

EPA Science Inventory

Water treatment plants at nine locations (10 plants) in Illinois and Iowa were studied to determine the characteristics and disposal practices for the sludge, brine, and backwash water containing radium (Ra) and/or barium (Ba). The treatment processes in these ten plants include ...

331

Dynamics of a barium release in the magnetospheric tail  

NASA Technical Reports Server (NTRS)

The late time behavior of the May 13, 1985 magnetotail barium cloud is examined. The bulk dynamics of the cloud are studied based on triangulated data and data from Fabry-Perot Doppler velocity measurements. The changes in cloud morphology in relation to the in situ measurements made by the Ion Release Module satellite are discussed.

Mende, S. B.; Swenson, G. R.; Geller, S. P.; Doolittle, J. H.; Haerendel, G.

1989-01-01

332

Optical, mechanical, and thermal properties of barium borate  

Microsoft Academic Search

We report measurements of all the material constants necessary to fully characterize barium borate as a nonlinear optical material. All data was taken on crystals supplied by Professor Chuangtien Chen, Fuzhou, People’s Republic of China. We have determined the crystal structure, the optical absorption, the refractive indices from the UV to the near IR, the thermo-optic coefficients, the nonlinear optical

D. Eimerl; L. Davis; S. Velsko; E. K. Graham; A. Zalkin

1987-01-01

333

Ultra-low temperature processing of barium tellurate dielectrics  

NASA Astrophysics Data System (ADS)

Ceramics, metals and polymers have unique electrical properties that are combined for electronic devices and systems. It necessitates lower processing temperatures for ceramics to be compatible with metal and polymer systems. In this thesis, the synthesis, crystal structure, and dielectric properties of barium tellurate are studied for temperatures between 500 and 900°C. Barium tellurate dielectric ceramics (BaTe4O9, BaTe 2O5, BaTe2O6, BaTeO3, BaTeO 4, and Ba2TeO5) are extensively investigated as new LTCC (Low-Temperature Cofired Ceramics) dielectric systems integrated with low resistivity metal electrodes such as silver and aluminum for microwave application. Studies on the phase formation and crystal structure through thermal analyses (Differential Scanning Calorimetry and Thermogravimetric Analysis, DSC-TGA) and X-ray diffraction phase analysis attest that barium tellurates are formed in the temperature range of 500 ˜ 900°C, through the sequential phase formations from Te-rich to Ba-rich phases. The oxygen coordination of the tellurium ion progresses from TeO4 to TeO6 via TeO 3+1 and TeO3 with increasing barium content as confirmed by structural analysis using infrared spectroscopy. High density barium tellurate ceramics are achieved at temperatures as low as 550°C, which provides the potential to be co-fired with low-melting aluminum metal electrodes in LTCC processing. Dielectric permittivity, loss, and temperature stability of barium tellurate dielectric ceramics were measured from 100 Hz to 13 GHz. Barium tellurate ceramics exhibit excellent microwave dielectric properties with intermediate dielectric permittivities and high quality factors (Q). The dielectric properties at microwave frequencies are epsilonr = 17.5, Qxf = 54700 GHz, TCf = -90 ppm/°C for BaTe4O9, epsilonr = 21, Qxf = 50300 GHz, TCf = -51 ppm/°C for BaTe2O6, epsilonr = 10, Qxf = 34000 GHz, TCf = -54 ppm/°C for BaTeO3, and epsilonr = 17, Qx f = 49600 GHz, TCf = -124 ppm/°C for Ba 2TeO5. Co-firing studies of barium tellurate ceramics with metal electrodes establish new LTCC systems for microwave devices. Chemical compatibility of barium tellurates with silver electrodes was achieved in the barium rich compositions. Ba2TeO5 was found to be covetable with silver electrodes at 850°C by adding CuO and B2O3 as fluxing agents. During the co-firing, a thin interfacial layer of AgTe is metastable according to the thermodynamic equilibrium between the Ba2TeO5-Ag/Ag 2O pseudo-binary system. A breakthrough LTCC technology with aluminum is based upon the ultra-low processing temperature and chemical compatibility of BaTe4O 9, which enables co-firing and fabrication of multilayer ceramic capacitors (MLCCs) with aluminum inner electrodes. The aluminum base metal electrode (BME) BaTe4O9 MLCCs provide good dielectric properties of epsilonr = 17.5, TCepsilon = 100 ppm/°C, and tan delta = 2.1 x 10-3 (Q ? 500) at 1 MHz, which are suitable for the class-1 MLCCs. Aluminum microstrip ring resonators on the BaTe4O9 substrates realized good electromagnetic performance of the new materials at microwave frequency exhibiting resonant frequency of 2.97 GHz and Q factor of 278.

Kwon, Do-Kyun

334

The biological reduction of selenate and sulfate in agricultural drainage water  

SciTech Connect

In many areas of the western US, subsurface drainage is produced when restrictive soils are irrigated and drained. The agricultural drainage water is saline and in many areas the concentration of selenium exceeds 100 {mu}g/L. Sulfate is present at concentrations ranging from 1,000 mg/L to 10,000 mg/L. Two upflow anaerobic sludge blanket reactors were constructed to evaluate the fate of selenate in a biological reactor treating a synthetic agricultural drainage water under sulfate-reducing conditions. Both lactate and molasses were evaluated as carbon sources for the microbiological process. Sulfate reducing conditions were established in both reactors with a 95+% reduction in sulfate from initial levels of 3,600 mg/L SO{sub 4}{sup {minus}2} Sulfate was reduced to sulfide via the dissimilatory sulfate reduction pathway. Selenate was reduced to elemental selenium through a sulfate-independent dissimilatory reduction pathway. The elemental selenium formed seleno-polysulfides in the sulfidic environment of the reactor. Conversion to seleno-polysulfides increased the solubility of the elemental selenium. The seleno-polysulfides were precipitated with iron salts. A residual total selenium level of about 20% of the initial 350 {mu}g/L Se remained in the effluent after precipitation of the seleno-polysulfides due to the presence of soluble organic selenium compounds. Denitrification of the influent nitrate at a concentration of 214 mg/L as NO{sub 3}{sup {minus}} was complete. A treatment scheme was proposed for the simultaneous removal of selenium, nitrate, and sulfate from agricultural drainage waters.

Owens, L.P.

1991-01-01

335

Localization and characterization of acharan sulfate in the body of the giant African snail Achatina fulica.  

PubMed

Acharan sulfate is a glycosaminoglycan (GAG), having the structure -->4)-2-acetamido-2-deoxy-alpha-D-glucopyranose(1-->4)-2-sulfo-alpha-L-idopyranosyluronic acid (1-->, isolated from the body of the giant African snail Achatina fulica. This GAG represents 3-5% of the dry weight of this snail's soft body tissues. Frozen sections and polyester wax sections of the snail's body were stained by Alcian blue-periodic acid-Schiff's reagent (PAS) to localize acharan sulfate. Alcian blue staining indicated that GAG was mainly secreted into the outer surface of the body from internal granules. A highly mucous material was collected and treated and the acharan sulfate was recovered by ethanol and cetyl pyridinium chloride precipitation. Crude acharan sulfate was purified by DEAE-Sephacel ion-exchange chromatography. Depolymerization of intact mucus and purified acharan sulfate fractions by heparin lyase II (heparitinase I) from Flavobacterium heparinum produced an unsaturated disaccharide as a major product, establishing the repeating unit of acharan sulfate. These results demonstrate that mucus in the granule and secreted to the outside of the body is composed entirely of acharan sulfate. PMID:11691628

Jeong, J; Toida, T; Muneta, Y; Kosiishi, I; Imanari, T; Linhardt, R J; Choi, H S; Wu, S J; Kim, Y S

2001-12-01

336

Aerobic sulfate reduction in microbial mats  

NASA Technical Reports Server (NTRS)

Measurements of bacterial sulfate reduction and dissolved oxygen (O2) in hypersaline bacterial mats from Baja California, Mexico, revealed that sulfate reduction occurred consistently within the well-oxygenated photosynthetic zone of the mats. This evidence that dissimilatory sulfate reduction can occur in the presence of O2 challenges the conventional view that sulfate reduction is a strictly anaerobic process. At constant temperature, the rates of sulfate reduction in oxygenated mats during daytime were similar to rates in anoxic mats at night: thus, during a 24-hour cycle, variations in light and O2 have little effect on rates of sulfate reduction in these mats.

Canfield, Donald E.; Des Marais, David J.

1991-01-01

337

Precipitate in Magnesium  

NASA Astrophysics Data System (ADS)

We performed molecular dynamics simulations and investigated interactions between a Mg17Al12 precipitate and a basal dislocation in magnesium. Modified embedded-atom method potentials for multiple-component systems were used in our simulations. The simulation results show that the basal dislocation is able to shear through the matrix and the precipitate/matrix interface, without creating a loop around the precipitate. The precipitate is only elastically deformed by the external shear strain. This interaction can be considered an extreme case of the Orowan mechanism when the strength of the precipitate/matrix interface is weak. Cross slip of the basal dislocation was observed when the precipitate size was 3.0 nm. The dislocation changed its slip plane to another basal plane via the prismatic and the pyramidal planes, creating jogs on these non-basal planes. The jogs had low mobility and debris was created when the jogs were dragged forward by the Shockley partial dislocations.

Liao, Min; Li, B.; Horstemeyer, M. F.

2014-07-01

338

In Situ Emission Microscopy of Scandium\\/Scandium-Oxide and Barium\\/Barium-Oxide Thin Films on Tungsten  

Microsoft Academic Search

The effect of a thin Sc\\/Sc-oxide base layer on Ba\\/Ba-oxide electron emission, surface diffusion, adsorption, and desorption on W is studied using photoelectron emission microscopy and thermionic emission microscopy. A barium-on-scandium structure enhances both photo- and thermionic electron emission.

Joel M. Vaughn; Keith D. Jamison; Martin E. Kordesch

2009-01-01

339

Precipitation Type Applet  

NSDL National Science Digital Library

This applet provides a simulation of the type of precipitation that results from adjusting the temperature (dry bulb and wet bulb) at different altitudes. An updraft in the cloud can be produced in order to see its influence on precipitation. The precipitation types that are simulated include snowflakes/ice crystals, supercooled droplets, raindrops, drizzle, sleet, snow grains, and freezing rain or drizzle on the ground.

Whittaker, Tom

340

Rock Star Precipitation  

NSDL National Science Digital Library

In this lesson, the student will play the role of a famous musician planning a world tour with performances in outdoor amphitheaters in Chile, Venezuela, Greenland, and Maine (USA). Based on Monthly Precipitation Data for 2006 from MyNASAData website, the student will evaluate changes in monthly precipitation levels, draw conclusions about how precipitation data will determine dates for a world tour and infer locations and months best for performing live outdoor concert.

341

Global Precipitation Measurement  

NASA Technical Reports Server (NTRS)

This chapter begins with a brief history and background of microwave precipitation sensors, with a discussion of the sensitivity of both passive and active instruments, to trace the evolution of satellite-based rainfall techniques from an era of inference to an era of physical measurement. Next, the highly successful Tropical Rainfall Measuring Mission will be described, followed by the goals and plans for the Global Precipitation Measurement (GPM) Mission and the status of precipitation retrieval algorithm development. The chapter concludes with a summary of the need for space-based precipitation measurement, current technological capabilities, near-term algorithm advancements and anticipated new sciences and societal benefits in the GPM era.

Hou, Arthur Y.; Skofronick-Jackson, Gail; Kummerow, Christian D.; Shepherd, James Marshall

2008-01-01

342

Mesoscale Banded Precipitation  

NSDL National Science Digital Library

Precipitation frequently falls and accumulates in discrete bands with accumulations that vary markedly over short distances. This module examines several mechanisms that result in mesoscale banded precipitation, focusing primarily on processes at work in midlatitude cyclones. The module starts with a review of the Norwegian and conveyor belt cyclone models. Then several banding processes are examined in detail, including deformation/frontogenesis, the Trowal (Trough of Warm Air Aloft), frontal merger, CSI/slantwise convection, and melting/evaporation-induced circulations. The module concludes with discussions of the representation of banded precipitation by NWP models and the detection of banded precipitation with satellite sensors.

Spangler, Tim

2005-06-24

343

Ceric-cerous sulfate dosimeter.  

National Technical Information Service (NTIS)

With a spectrophotometer at wavelength of 320 nm, the molar linear absorption coefficient determined for Ce(sup 4+) ions in acidic sulfate solution is 599.1 m(sup 2)/mol and its linearity is better than 0.5% in the absorption range from 0.1 to 1.6. The re...

Zhang Guiqing Chen Yundong Ye Hongsheng Lin Min

1994-01-01

344

Sulfated binary oxide solid superacids  

Microsoft Academic Search

Sulfated binary oxide solid superacids were prepared by the chemical method. The structural properties of the catalyst were examined by using BET, XRD, DTA and IR spectroscopy. Acidity properties of the catalysts were tested by Hammett indicator. Catalytic activity of the catalysts was researched by the reaction of glycerin with acetic acid in toluene. The optimum calcined temperature of the

Hua Yang; Rong Lu; Jingzhe Zhao; Xuwei Yang; Lianchun Shen; Zichen Wang

2003-01-01

345

Minerals Yearbook, 1989: Sodium Sulfate.  

National Technical Information Service (NTIS)

The U.S. sodium sulfate industry rebounded slightly in 1989 as demand increased in the detergent and pulp and paper sectors. After years of stagnant growth, domestic producers were encouraged at the positive trend but were aware the trend may be short liv...

D. S. Kostick

1989-01-01

346

Chiral Crystallization of Ethylenediamine Sulfate  

ERIC Educational Resources Information Center

The optimal conditions for the crystallization of achiral ethylenediamine sulfate into large chiral crystals that are ideal for polarimetry studies and observation using Polaroid sheets are presented. This experiment is an ideal undergraduate experiment, which clearly demonstrates the chiral crystallization of an achiral molecule.

Koby, Lawrence; Ningappa, Jyothi B.; Dakesssian, Maria; Cuccia, Louis A.

2005-01-01

347

Barium partitioning in coccoliths of Emiliania huxleyi  

NASA Astrophysics Data System (ADS)

The coccolithophore Emiliania huxleyi was grown in seawater under different Ba concentrations. The relationship of coccolith Ba/Ca ratio and seawater Ba/Ca ratio was found to be linear. The linear regression yields the apparent Ba exchange coefficient of 0.10. Our data support a recently proposed generic model (Langer G., Gussone N., Nehrke G., Riebesell U., Eisenhauer A., Kuhnert H., Rost B., Trimborn S., and Thoms S. (2006) Coccolith strontium to calcium ratios in Emiliania huxleyi: the dependence on seawater strontium and calcium concentrations. Limnol. Oceanogr.51, 310-320.) developed for explaining apparent exchange coefficients of metabolically inert divalent trace metals, such as Sr, in E. huxleyi. This model represents the first approach combining cell physiological processes and data from inorganic precipitation experiments, which quantitatively explains coccolith apparent Sr and Ba exchange coefficients.

Langer, Gerald; Nehrke, Gernot; Thoms, Silke; Stoll, Heather

2009-05-01

348

Sulfite-sulfide-sulfate-carbonate equilibria with applications to Mars  

NASA Astrophysics Data System (ADS)

Mars volcanic SO2 and H2S gas emissions are likely the dominant source of martian sulfate, and the source of sulfuric acid. Until this work, the FREZCHEM model lacked SO2 and H2S gases and associated sulfite and sulfide minerals. The specific objectives of this paper were to add these components and associated sulfite and sulfide minerals and phases into FREZCHEM, and to explore some possible roles of these chemistries on Mars. New solid phases added included the sulfites: Na2SO3·7H2O, K2SO3, (NH4)2SO3·H2O, MgSO3·6H2O, CaSO3·0.5H2O, and FeSO3·1.5H2O, and the sulfide: FeS2. The lowest eutectic of these minerals was K2SO3 (= 6.57 m) at 228 K. Because sulfurous acid is stronger than carbonic acid, this causes a much larger fraction of S(IV) to exist as sulfite (SO32-) at acidic to mildly alkaline pH, whereas almost none of the C is present as carbonate anion. Model calculations show that small quantities of SO2 in an early CO2-rich martian atmosphere suppressed formation of carbonates because SO2 is much more water soluble than CO2 and a stronger acid, which may be a major reason why sulfates are much more common than carbonates on Mars. Also, perhaps equally important are low temperatures that favor sulfite mineral precipitation, the oxidation of which leads to sulfate minerals. Another potentially important factor that favors sulfite/sulfide mineral formation is low pH values that cannot allow carbonate minerals, but can allow sulfide minerals such as pyrite (FeS2). The presence of pyrite, highly insoluble, would lead to sulfate minerals when oxygen becomes available in acidic environments. Major cations for both sulfites (or sulfates) and carbonates (Ca and Mg) can limit carbonates. Sulfite-sulfide volcanism on a cold, lower pH, Mars are the primary causes of high sulfate minerals (e.g., Ca and Mg sulfates), compared to volcanism on a warm, higher pH, Earth that led to more abundant carbonate minerals (e.g., Ca and Mg carbonates).

Marion, G. M.; Kargel, J. S.; Crowley, J. K.; Catling, D. C.

2013-07-01

349

21 CFR 522.2121 - Spectinomycin sulfate.  

Code of Federal Regulations, 2010 CFR

...522.2121 Spectinomycin sulfate. (a) Specifications . Each milliliter of solution contains spectinomycin sulfate tetrahydrate equivalent to 100 milligrams (mg) spectinomycin. (b) Sponsor . See No. 000009 in § 510.600(c) of this...

2010-04-01

350

Thermodynamic control of microbial sulfate reduction rates and consequences for the form and distribution of metal sulfide nanoparticles  

NASA Astrophysics Data System (ADS)

Sulfate reducing bacteria are widespread in natural environment. They derive energy for growth by reducing sulfate to sulfide. In the presence of metal ions, the sulfide byproduct precipitates as metal sulfide nanoparticles. Microorganisms can reduce sulfate through two metabolic pathways, i.e., an incomplete and a complete pathway. In the former case, microorganisms, such as Desulfovibrio sp., oxidize lactate, butyrate, ethanol, etc. to acetate, whereas in the latter, microorganisms, such as Desulfobacter sp., oxidize acetate to bicarbonate. It is important to study the kinetics of microbial sulfate reduction because microbial metabolic rates may influence the form, mobility, and reactivity of biogenic minerals. The rate of sulfate reduction is controlled not only by substrate concentrations in environments, but also by the thermodynamic driving force. The driving force is the difference between the energy available from environment and the energy conserved. The amount of energy conserved is about 80 kJ/mol lactate and 90 kJ/mol acetate for incomplete and complete pathway, respectively. Where the energy available from environments is much higher than the energy conserved, the driving force is large and sulfate reduction proceeds at high rate. The particle size of metal sulfide minerals precipitated under such conditions is extremely small. However, where the energy available is close to the energy conserved, the driving force is small and the rate of sulfate reduction is small. These conditions could favor nanoparticle transport because particle advection and dispersion may be strong enough to remove nanoparticles before large immobile aggregates can form.

Jin, Q.; Banfield, J.

2004-12-01

351

Benzene Oxidation Coupled to Sulfate Reduction  

Microsoft Academic Search

(14C)benzene tracer was included with the benzene added to benzene-adapted sediments, 92% of the added radioactivity was recovered as 14CO2. Molybdate, an inhibitor of sulfate reduction, inhibited benzene uptake and production of 14CO2from ( 14 C)benzene. Benzene metabolism stopped when the sediments became sulfate depleted,andbenzeneuptakeresumedwhensulfatewasaddedagain.Thestoichiometryofbenzeneuptakeand sulfate reduction was consistent with the hypothesis that sulfate was the principal electron acceptor for

DEREK R. LOVLEY; JOHN D. COATES; JOAN C. WOODWARD; ANDELIZABETH J. P. PHILLIPS

1995-01-01

352

Sulfate reduction and methanogenesis in marine sediments  

NASA Technical Reports Server (NTRS)

Methanogenesis and sulfate-reduction were followed in laboratory incubations of sediments taken from tropical seagrass beds. Methanogenesis and sulfate-reduction occurred simultaneously in sediments incubated under N2, thereby indicating that the two processes are not mutually exclusive. Sediments incubated under an atmosphere of H2 developed negative pressures due to the oxidation of H2 by sulfate-respiring bacteria. H2 also stimulated methanogenesis, but methanogenic bacteria could not compete for H2 with the sulfate-respiring bacteria.

Oremland, R. S.; Taylor, B. F.

1978-01-01

353

Volumetric determination of uranium using titanous sulfate as reductant before oxidimetric titration  

USGS Publications Warehouse

A new method for determining uranium in samples containing 0.05 percent or more U3O8, using titanous sulfate as reducing agent, is much shorter, faster, and has fewer interferences than conventional methods using reductor columns. The sample is dissolved with sulfuric, nitric, perchloric, and hydrofluoric acids. Elements that would otherwise form insoluble fluorides are kept in solution by complexing the fluoride ion with boric acid. A precipitation is made with cupferron to remove interfering elements. The solution is filtered to remove the precipitated cupferrates instead of extracting them with chloroform as is usually done. Filtration is preferred to extraction because any niobium that may be in solution forms an insoluble cupferrate that may be removed by filtering but is very difficult to extract with chloroform. Excess cupferron is destroyed by oxidizing with nitric and perchloric acids, and evaporating to dense fumes of sulfuric acid. The uranium is reduced to U(IV) by the addition of titanous sulfate, with cupric sulfate used as an indicator of the completeness of the reduction. Metallic copper is formed when all the uranium is reduced. The reduced copper is then reoxidized by the addition of mercuric perchlorate, an excess of ferric sulfate added, and the solution titrated immediately with standard ceric sulfate with ferroin as an indicator. Precision of the method compared favorable with methods in common use, both for uranium ores and for most types of uranium-rich materials.

Wahlberg, James S.; Skinner, Dwight L.; Rader, Lewis F.

1956-01-01

354

Dermatan sulfate in tunicate phylogeny: Order-specific sulfation pattern and the effect of [->4IdoA(2-Sulfate)?-1->3GalNAc(4-Sulfate)?-1->] motifs in dermatan sulfate on heparin cofactor II activity  

PubMed Central

Background Previously, we have reported the presence of highly sulfated dermatans in solitary ascidians from the orders Phlebobranchia (Phallusia nigra) and Stolidobranchia (Halocynthia pyriformis and Styela plicata). Despite the identical disaccharide backbone, consisting of [?4IdoA(2S)?-1?3GalNAc?-1?], those polymers differ in the position of sulfation on the N-Acetyl galactosamine, which can occur at carbon 4 or 6. We have shown that position rather than degree of sulfation is important for heparin cofactor II activity. As a consequence, 2,4- and 2,6-sulfated dermatans have high and low heparin cofactor II activities, respectively. In the present study we extended the disaccharide analysis of ascidian dermatan sulfates to additional species of the orders Stolidobranchia (Herdmania pallida, Halocynthia roretzi) and Phlebobranchia (Ciona intestinalis), aiming to investigate how sulfation evolved within Tunicata. In addition, we analysed how heparin cofactor II activity responds to dermatan sulfates containing different proportions of 2,6- or 2,4-disulfated units. Results Disaccharide analyses indicated a high content of disulfated disaccharide units in the dermatan sulfates from both orders. However, the degree of sulfation decreased from Stolidobranchia to Phlebobranchia. While 76% of the disaccharide units in dermatan sulfates from stolidobranch ascidians are disulfated, 53% of disulfated disaccharides are found in dermatan sulfates from phlebobranch ascidians. Besides this notable difference in the sulfation degree, dermatan sulfates from phlebobranch ascidians contain mainly 2,6-sulfated disaccharides whereas dermatan sulfate from the stolidobranch ascidians contain mostly 2,4-sulfated disaccharides, suggesting that the biosynthesis of dermatan sulfates might be differently regulated during tunicates evolution. Changes in the position of sulfation on N-acetylgalactosamine in the disaccharide [?4IdoA(2-Sulfate)?-1?3GalNAc?-1?] modulate heparin cofactor II activity of dermatan sulfate polymers. Thus, high and low heparin cofactor II stimulating activity is observed in 2,4-sulfated dermatan sulfates and 2,6-sulfated dermatan sulfates, respectively, confirming the clear correlation between the anticoagulant activities of dermatan sulfates and the presence of 2,4-sulfated units. Conclusions Our results indicate that in ascidian dermatan sulfates the position of sulfation on the GalNAc in the disaccharide [?4IdoA(2S)?-1?3GalNAc?-1?] is directly related to the taxon and that the 6-O sulfation is a novelty apparently restricted to the Phlebobranchia. We also show that the increased content of [?4IdoA(2S)?-1?3GalNAc(4S)?-1?] disaccharide units in dermatan sulfates from Stolidobranchia accounts for the increased heparin cofactor II stimulating activity.

2011-01-01

355

LASL bismuth sulfate thermochemical hydrogen cycle  

Microsoft Academic Search

The LASL bismuth sulfate cycle is one of a generic class of solid sulfate cycles in which a metal sulfate is substituted for sulfuric acid in a hybrid (partly electrochemical) cycle. This technique avoids the serious materials and heat penalty problems associated with the handling of concentrated acid solutions, and if the electrolyzer is operated at acid concentrations below 50%

K. E. Cox; W. M. Jones; C. L. Peterson

1980-01-01

356

21 CFR 556.300 - Gentamicin sulfate.  

Code of Federal Regulations, 2010 CFR

...2009-04-01 2009-04-01 false Gentamicin sulfate. 556.300 Section 556...of New Animal Drugs § 556.300 Gentamicin sulfate. (a) A tolerance of 0...established for negligible residues of gentamicin sulfate in the uncooked edible...

2009-04-01

357

21 CFR 556.300 - Gentamicin sulfate.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Gentamicin sulfate. 556.300 Section 556...of New Animal Drugs § 556.300 Gentamicin sulfate. (a) A tolerance of 0...established for negligible residues of gentamicin sulfate in the uncooked edible...

2010-04-01

358

Sulfate-reducing bacteria in anaerobic bioreactors  

Microsoft Academic Search

The treatment of industrial wastewaters containing high amounts of easily degradable organic compounds in anaerobic bioreactors is a well-established process. Similarly, wastewaters which in addition to organic compounds also contain sulfate can be treated in this way. For a long time, the occurrence of sulfate reduction was considered to be undesired. However, there are some recent developments in which sulfate

S. J. W. H. Oude Elferink

1998-01-01

359

Acid sulfate corrosion in PWR steam generators  

Microsoft Academic Search

This report summarizes the plant operating experience and the results of laboratory testing associated with the occurrence of corrosion produced in acid sulfate environments. Three forms of steam generator corrosion have been attributed to the presence of these environments: reduced sulfate species have produced stress corrosion cracking in several plants having sensitized tubing (primarily in once-through steam generators); acid sulfates

A. J. Baum; W. M. Connor; S. D. Piskor; W. J. Stenger

1991-01-01

360

21 CFR 184.1230 - Calcium sulfate.  

Code of Federal Regulations, 2010 CFR

...2009-04-01 2009-04-01 false Calcium sulfate. 184.1230 Section...Affirmed as GRAS § 184.1230 Calcium sulfate. (a) Calcium sulfate (CaSO4 , CAS Reg...23) of this chapter, 0.35 percent for processed...

2009-04-01

361

Efflorescence as a source of hydrated sulfate minerals in valley settings on Mars  

NASA Astrophysics Data System (ADS)

A distinctive sulfur cycle dominates many geological processes on Mars and hydrated sulfate minerals are found in numerous topographic settings with widespread occurrences on the Martian surface. However, many of the key processes controlling the hydrological transport of sulfur, including sulfur sources, climate and the depositional history that led to precipitation of these minerals, remain unclear. In this paper, we use a model for the formation of sulfate efflorescent salts (Mg-Ca-Na sulfates) in the Rio Puerco watershed of New Mexico, a terrestrial analog site from the semiarid Southwest U.S., to assess the origin and environmental conditions that may have controlled deposition of hydrated sulfates in Valles Marineris on Mars. Our terrestrial geochemical results (?S34 of -36.0 to +11.1‰) show that an ephemeral arid hydrological cycle that mobilizes sulfur present in the bedrock as sulfides, sulfate minerals, and dry/wet atmospheric deposition can lead to widespread surface accumulations of hydrated sulfate efflorescences. Repeating cycles of salt dissolution and reprecipitation appear to be major processes that migrate sulfate efflorescences to sites of surface deposition and ultimately increase the aqueous SO42- flux along the watershed (average 41,273 metric tons/yr). We suggest that similar shallow processes may explain the occurrence of hydrated sulfates detected on the scarps and valley floors of Valles Marineris on Mars. Our estimates of salt mass and distribution are in accord with studies that suggest a rather short-lived process of sulfate formation (minimum rough estimate ?100 to 1000 years) and restriction by prevailing arid conditions on Mars.

Szynkiewicz, Anna; Borrok, David M.; Vaniman, David T.

2014-05-01

362

Conversion of alkali metal sulfate to the carbonate  

DOEpatents

A process for converting potassium sulfate to potassium carbonate in which a mixture of potassium sulfate and calcium oxide are reacted at a temperature in the range of between about 700.degree. C. and about 800.degree. C. with a gaseous mixture having a minor amount of hydrogen and/or carbon monoxide in a diluent with the calcium oxide being present in an amount not greater than about 20 percent by weight of the potassium sulfate to produce an aqueous mixture of potassium sulfide, potassium bisulfide, potassium hydroxide and calcium sulfide and a gaseous mixture of steam and hydrogen sulfide. The potassium and calcium salts are quenched to produce an aqueous slurry of soluble potassium salts and insoluble calcium salts and a gaseous mixture of steam and hydrogen sulfide. The insoluble calcium salts are then separated from the aqueous solution of soluble potassium salts. The calcium salts are dried to produce calcium sulfide, calcium bisulfide and steam, and then, the calcium sulfide and calcium bisulfide are converted to the oxide and recycled. The soluble potassium salts are carbonated to produce potassium carbonate which is concentrated and the precipitated crystals separated. The sulfur-containing compounds are further treated.

Sheth, Atul C. (Woodridge, IL) [Woodridge, IL

1982-01-01

363

Life Model of Hollow Cathodes Using a Barium Calcium Aluminate Impregnated Tungsten Emitter  

NASA Technical Reports Server (NTRS)

Hollow cathodes with barium calcium aluminate impregnated tungsten emitters for thermionic emission are widely used in electric propulsion. These high current, low power cathodes are employed in ion thrusters, Hall thrusters, and on the International Space Station in plasma contactors. The requirements on hollow cathode life are growing more stringent with the increasing use of electric propulsion technology. The life limiting mechanism that determines the entitlement lifetime of a barium impregnated thermionic emission cathode is the evolution and transport of barium away from the emitter surface. A model is being developed to study the process of barium transport and loss from the emitter insert in hollow cathodes. The model accounts for the production of barium through analysis of the relevant impregnate chemistry. Transport of barium through the approximately static gas is also being treated. Finally, the effect of temperature gradients within the cathode are considered.

Kovaleski, S. D.; Burke, Tom (Technical Monitor)

2001-01-01

364

The crystal growth of barium flouride in aqueous solution  

NASA Astrophysics Data System (ADS)

The kinetics of growth of barium flouride seed crystals were investigated in aqueous solution at 25°C using a constant composition method, in which the supersaturation and ionic strength were maintained constant by the addition of titrants consisting of barium nitrate and potassium flouride solutions. The rates of reaction, studied over a range of supersaturation (? ? 0.4 to 1.0), were interpreted in terms of crystal growth models. A spiral growth mechanism best describes the data, and scanning electron microscopy indicates a three-dimensional growth. In the presence of inorganic additives such as phosphate, however, induction periods precede a morphological two-dimensional crystallization. Coulter Counter results show little crystal agglomeration.

Barone, J. P.; Svrjcek, D.; Nancollas, G. H.

1983-06-01

365

Study of the photovoltaic effect in thin film barium titanate  

NASA Technical Reports Server (NTRS)

Ferroelectric films of barium titanate were synthesized on silicon and quartz substrates, and the photoelectric effect in the structure consisting of metal deposited ferroelectric barium titanate film silicon was studied. A photovoltage with polarity that depends on the direction of the remanent polarization was observed. The deposition of BaTiO3 on silicon and fused quartz substrates was accomplished by an rf sputtering technique. A series of experiments to study the growth of ferroelectric BaTiO3 films on single crystal silicon and fused quartz substrates were conducted. The ferroelectric character in these films was found on the basis of evidence from the polarization electric field hysteresis loops, capacitance voltage and capacitance temperature techniques and from X-ray diffraction studies.

Grannemann, W. W.; Dharmadhikari, V. S.

1982-01-01

366

Nature of the semiconducting properties of ceramic barium titanate  

SciTech Connect

The compound BaTiO/sub 3/ is a dielectric but can be put into the semiconducting state by means of heat treatment in a reducing atmosphere or by doping with a small (0.1-0.5 mole %) amount of oxides of group-III or group-V elements (so-called donor dopants). The effect of dopants on the properties of barium titanate cannot be explained by means of quasi-chemical reactions. The chemical and crystal-chemical properties of dopant oxides and the phase relations in multicomponent BaTiO/sub 3/-dopant oxides systems make it possible correctly to estimate and predict the dependence of the properties of barium titantate on the dopant oxides.

Kvantov, M.A.; Kostikov, Yu.P.; Leikina, B.B.

1988-03-01

367

The Skylab barium plasma injection experiments. I - Convection observations  

NASA Technical Reports Server (NTRS)

Two barium-plasma injection experiments were carried out during magnetically active periods in conjunction with the Skylab 3 mission. The high-explosive shaped charges were launched near dawn on November 27 and December 4, 1973, UT. In both cases, the AE index was near 400 gammas, and extensive pulsating auroras covered the sky. The first experiment, Skylab Alpha, occurred in the waning phase of a 1000-gamma substorm, and the second, Skylab Beta, occurred in the expansive phase of an 800-gamma substorm. In both, the convection was generally magnetically eastward, with 100-km-level electric fields near 40 mV/m. However, in the Alpha experiment the observed orientation of the barium flux tube fit theoretical field lines having no parallel current, but the Beta flux-tube orientation indicated a substantial upward parallel sheet current.

Wescott, E. M.; Stenbaek-Nielsen, H. C.; Davis, T. N.; Peek, H. M.

1976-01-01

368

Observations and theory of the AMPTE magnetotail barium releases  

NASA Technical Reports Server (NTRS)

The barium releases in the magnetotail during the Active Magnetospheric Particle Tracer Explorers (AMPTE) operation were monitored by ground-based imagers and by instruments on the Ion Release Module. After each release, the data show the formation of a structured diamagnetic cavity. The cavity grows until the dynamic pressure of the expanding ions balances the magnetic pressure on its surface. The magnetic field inside the cavity is zero. The barium ions collect on the surface of the cavity, producing a shell. Plasma irregularities form along magnetic field lines draped over the surface of the cavity. The scale size of the irregularities is nearly equal to the thickness of the shell. The evolution and structuring of the diamagnetic cavity are modeled using magnetohydrodynamics theory.

Bernhardt, P. A.; Roussel-Dupre, R. A.; Pongratz, M. B.; Haerendel, G.; Valenzuela, A.

1987-01-01

369

21 CFR 524.154 - Bacitracin or bacitracin zinc-neomycin sulfate-polymyxin B sulfate ophthalmic ointment.  

Code of Federal Regulations, 2010 CFR

...bacitracin zinc-neomycin sulfate-polymyxin B sulfate ophthalmic ointment...bacitracin zinc-neomycin sulfate-polymyxin B sulfate ophthalmic ointment...neomycin, and 10,000 units of polymyxin B. (2) To 000061 and...

2009-04-01

370

21 CFR 524.154 - Bacitracin or bacitracin zinc-neomycin sulfate-polymyxin B sulfate ophthalmic ointment.  

Code of Federal Regulations, 2010 CFR

...bacitracin zinc-neomycin sulfate-polymyxin B sulfate ophthalmic ointment...bacitracin zinc-neomycin sulfate-polymyxin B sulfate ophthalmic ointment...neomycin, and 10,000 units of polymyxin B. (2) To 000061 and...

2010-04-01

371

Sulfate minerals and organic compounds on Mars  

NASA Astrophysics Data System (ADS)

Strong evidence for evaporitic sulfate minerals such as gypsum and jarosite has recently been found on Mars. Although organic molecules are often codeposited with terrestrial evaporitic minerals, there have been no systematic investigations of organic components in sulfate minerals. We report here the detection of organic material, including amino acids and their amine degradation products, in ancient terrestrial sulfate minerals. Amino acids and amines appear to be preserved for geologically long periods in sulfate mineral matrices. This suggests that sulfate minerals should be prime targets in the search for organic compounds, including those of biological origin, on Mars.

Aubrey, Andrew; Cleaves, H. James; Chalmers, John H.; Skelley, Alison M.; Mathies, Richard A.; Grunthaner, Frank J.; Ehrenfreund, Pascale; Bada, Jeffrey L.

2006-05-01

372

Preparation of barium\\/strontium titanate by solution route  

Microsoft Academic Search

As compared to the conventional solid-state route, solution routes have been reported to produce powders with better homogeneity and controlled morphology. A new solution-based method has been developed to produce fine powders of BaTiO3 and SrTiO3 of high reactivity. In this method an equimolar mixture of solutions of barium nitrate or strontium nitrate and titanium nitrate is heated with suitable

T. V. Vittal Rao; R. V. Kamat; V. N. Vaidya; D. D. Sood

1996-01-01

373

Glycothermal synthesis and characterization of tetragonal barium titanate  

Microsoft Academic Search

Tetragonal barium titanate (BaTiO3) particles were synthesized at temperature as low as 220°C through glycothermal reaction by using Ba(OH)2·8H2O and amorphous titanium hydrous gel as precursors and 1,4-butanediol and water as solvent. XRD, DSC and Raman data support that glycothermal processing method provides a simple low-temperature route for producing tetragonal BaTiO3 nanoparticles without alkaline mineralizers. It is also demonstrated that

Yong-Jin Jung; Dae-Young Lim; Jun-Seok Nho; Seung-Beom Cho; Richard E. Riman; Byeong Woo Lee

2005-01-01

374

Efficiency and mechanism of barium getters at low pressures  

Microsoft Academic Search

The gettering rates of barium getters for oxygen, nitrogen, hydrogen, carbon-monoxide, carbon-dioxide and water vapour are measured in the pressure range between 5 × 10-8 and 5 × 10-5 mm of mercury. Values for the decay in gettering rate during use of the getter are given. It is shown that the gettering effect at these low pressures is almost entirely

S. Wagener

1951-01-01

375

Radium and barium in the Amazon River system  

Microsoft Academic Search

Data for ²²⁶Ra and ²²⁸Ra in the Amazon River system show that the activity of each radium isotope is strongly correlated with barium concentrations. Two trends are apparent, one for rivers which drain shield areas and another for all other rivers. These data suggest that there has been extensive fractionation of U, Th, and Ba during weathering in the Amazon

Willard S. Moore; John M. Edmond

1984-01-01

376

Barium-strontium-titanate etching characteristics in chlorinated discharges  

Microsoft Academic Search

The etching characteristics of barium-strontium-titanate (BST) were investigated using a high-density plasma sustained by surface waves at 190 MHz in Ar\\/Cl2 gas mixtures. The etch rate was examined as a function of both the total gas pressure and the Cl2 fraction in Ar\\/Cl2 using a wafer temperature of 10 °C. The results were correlated to positive ion density and plasma

Luc Stafford; Joëlle Margot; Olivier Langlois; Mohamed Chaker

2003-01-01

377

Sol-Gel Derived Barium-Strontium Titanate Films  

Microsoft Academic Search

Sol-gel techniques for the preparation of barium-strontium titanate (BST) films are discussed. The evolution of film microstructure during heat treatment, and the dielectric properties of BST films prepared from alkoxide solutions and from alkoxide solutions modified by 2-ethylhexanoic acid were studied. It is shown that the extent of the modification of the precursors by 2-ethylhexanoic acid changes the precursor molecular

V. A. Vasiljev; K. A. Vorotilov; M. I. Yanovskaya; L. I. Solovjeva; A. S. Sigov

1998-01-01

378

Sol-gel preparation of barium strontium titanate thin films  

Microsoft Academic Search

Barium strontium titanate, ((BaxSr1-x)TiO 3), thin films of various compositions were prepared by a spin coating technique. Processing parameters were optimized to develop stable solutions which yielded crack-free films with relatively low crystallization temperatures. XRD and thermal analysis techniques were used to characterize the films and gels. The dielectric constant and dissipation factor of the films were measured as a

D. Tahan; A. Safari; L. C. Klein

1994-01-01

379

Nonlinear dielectric properties of barium strontium titanate ceramics  

Microsoft Academic Search

In barium strontium titanate (BaxSr1?xTiO3) ceramics, obvious tunabilities of both dielectric permittivity and loss tangent under external DC bias field were observed. The temperature and frequency dependences of nonlinear dielectric properties were studied. Polarizing process was carried out to evaluate the influence of domain reorientation on dielectric nonlinearity in the ferroelectric polycrystalline samples. The nonlinear variation of dielectric properties under

Xiaoyong Wei; Xi Yao

2003-01-01

380

Texture and Microstructural Development in Gelcast Barium Hexaferrite  

SciTech Connect

The development of texture in barium hexaferrite by templated grain growth was studied as a function of the Fe2O3/BaCO3 ratio, B2O3 additions in the starting materials, and sintering temperature. A magnetic field was used to orient the template particles during the gelcasting process. Excess BaCO3 resulted in abnormal grain growth and maximized texture, while B2O3 additions promoted coarsening, but no abnormal grain growth.

Hovis, David B. [Northwestern University, Evanston; Faber, Katherine T. [Northwestern University, Evanston; Kenik, Edward A [ORNL

2008-01-01

381

The positive temperature coefficient of resistivity in barium titanate  

Microsoft Academic Search

Positive temperature coefficient of resistivity (PTCR) materials have become very important components, and among these materials\\u000a barium titanate compounds make up the most important group. When properly processed these compounds show a high PTCR at the\\u000a Curie temperature (the transition temperature from the ferroelectric tetragonal phase to the paraelectric cube phase). In\\u000a the first half of this paper literature related

B. Huybrechts; K. Ishizaki; M. Takata

1995-01-01

382

Elastic and Piezoelectric Coefficients of Single-Crystal Barium Titanate  

Microsoft Academic Search

Mechanical resonance and antiresonance frequencies were measured on barium titanate single-crystal elements maintained under electric dc bias from -50°C to +150°C. A complete set of elastic, piezoelectric, and dielectric constants of the tetragonal modification at 25°C is obtained. The elastic compliances show substantial deviation from cubic symmetry. Measurements in the orthorhombic state show longitudinal compliance four times higher than in

Don Berlincourt; Hans Jaffe

1958-01-01

383

Barium–borate–flyash glasses: As radiation shielding materials  

Microsoft Academic Search

The attenuation coefficients of barium–borate–flyash glasses have been measured for ?-ray photon energies of 356, 662, 1173 and 1332keV using narrow beam transmission geometry. The photon beam was highly collimated and overall scatter acceptance angle was less than 3°. Our results have an uncertainty of less than 3%. These coefficients were then used to obtain the values of mean free

Sukhpal Singh; Ashok Kumar; Devinder Singh; Kulwant Singh Thind; Gurmel S. Mudahar

2008-01-01

384

Adequacy of preparation for barium enema among elderly outpatients.  

PubMed Central

OBJECTIVE: To determine whether outpatients 75 years of age or older have a higher rate of inadequate bowel preparation for barium enema and of complications associated with the preparation and the test than patients aged 55 to 74 years. DESIGN: Cross-sectional survey. SETTING: Radiology department in a teaching hospital. PATIENTS: Patients 55 years or older referred for a barium enema from March to August 1988. OUTCOME MEASURES: All films were reviewed independently by a study radiologist blind to the staff radiologist's report. Patients were interviewed by telephone within several days after the test to assess the occurrence of problems during the preparation or the test. MAIN RESULTS: Of the 213 patients assessed 72 were excluded: 43 refused to participate or could not be contacted, 16 had previously undergone colonic surgery, and 13 were excluded for other reasons. The remaining 141 patients were separated into three age groups: those 55 to 64 years (46 patients), those 65 to 74 (47) and those 75 or older (48). In 104 cases (74%) the bowel had been prepared adequately; there was no significant difference between the three groups with regard to the adequacy of preparation. The incidence of problems reported by the patients did not differ significantly between the groups. CONCLUSIONS: Outpatients aged 75 years or more are no more likely than those aged 55 to 74 to have problems with bowel preparation or the barium enema itself. Age should not be a criterion for exclusion from barium enema. To try to lower the rate of poor bowel preparation clinicians and radiologists should consider counselling patients more carefully about the importance of proper preparation. Also, the current method of preparation could be examined to determine whether simple changes would significantly improve colon cleanliness.

Grad, R M; Clarfield, A M; Rosenbloom, M; Perrone, M

1991-01-01

385

Pockels response in calcium barium niobate thin films  

NASA Astrophysics Data System (ADS)

The electro-optical response of calcium barium niobate ferroelectric thin films is characterized using a single beam setup in reflection geometry. Clear evidence of a Pockels response together with an r33 coefficient as high as 130 pm/V is found. This large value and the high Curie temperature of the material under study (>250 °C) can be considered as a promising feature for the fabrication of hybrid, integrated electro-optical modulators working at a high repetition rate.

Helsten, R.; Razzari, L.; Ferrera, M.; Ndione, P. F.; Gaidi, M.; Durand, C.; Chaker, M.; Morandotti, R.

2007-12-01

386

Isotopic Masses of Hydrogen, Chlorine, Barium, Cerium, and Neodymium  

Microsoft Academic Search

The 16-in. double-focusing mass spectrometer at the University of Minnesota has been employed to measure the atomic mass of H1 and the atomic masses and isotopic mass differences of chlorine, barium, cerium, and neodymium. Recent improvements in instrumentation have increased the precision of both narrow and wide doublet measurements. The doublet C11H22-C12H10 was used to relate the H1 mass directly

Jay L. Benson; Walter H. Johnson

1966-01-01

387

Reduction of Np(V) and precipitation of Np(IV) by an anaerobic microbial consortium.  

PubMed

A combination of experimental, analytical, and modeling investigations shows that an anaerobic, sulfate-reducing consortium reduced Np(V) to Np(IV), with subsequent precipitation of a Np(IV) solid. Precipitation of Np(IV) during growth on pyruvate occurred before sulfate reduction began. H2 stimulated precipitation of Np(IV) when added alone to growing cells, but it slowed precipitation when added along with pyruvate. Increasing concentrations of pyruvate also retarded precipitation. Accumulation of an intermediate pyruvate-fermentation product--probably succinate--played a key role in retarding Np(IV) precipitation by complexing the Np(IV). Hydrogen appears to have two roles in controlling Np precipitation: donating electrons for Np(V) reduction and modulating intermediate levels. That Np(V) is microbially reduced and subsequently precipitated under anaerobic conditions has likely beneficial implications for the containment of Np on lands contaminated by radionuclides, but complexation by fermentation intermediates can prevent immobilization by precipitation. PMID:12688585

Rittmann, Bruce E; Banaszak, James E; Reed, Donald T

2002-01-01

388

Comportement des materiaux cimentaires: Actions des sulfates et de la temperature  

NASA Astrophysics Data System (ADS)

The research work presented in this Ph.D. thesis is related to the nuclear waste underground repository concept. Concrete could be used in such a repository, and would be subjected to variations of temperature in presence of sulfate, a situation that could induce expansion of concrete. The research was lead in three parts: an experimental study of the possibility of an internal sulfate attack on mortars; an experimental study and modeling of the chemical equilibriums of the CaO-SiO2-Al2O 3-SO-H2O system; and a modeling of the mechanisms of internal and external sulfate attacks, and the effect of temperature. The results show that mortars can develop expansions after a steam-cure during hydration, but also when a long steam-cure is applied to one-year-old mortars, which is a new point. Ettringite precipitation can be considered as responsible for these expansions. The experimental study of the CaO-SiO2-Al2O 3-SO3-H2O system clarified the role of Calcium Silicate Hydrates (C-S-H) on chemical equilibriums of cementitious materials. Sulfate sorption on C-S-H has been studied in detail. The quantity of sulfate bound to the C-S-H mainly depends on the sulfate concentration in solution, on the Ca/Si ratio of the C-S-H and is not significantly influenced by temperature. Aluminium inclusion in the C-S-H seems to be a significant phenomenon. Temperature increases the calcium sulfoaluminate solubilities and thus increases sulfates concentration in solution. A modeling of the chemical system is proposed. Simulations of external sulfate attack (15 mmol/L of Na2SO 4) predict ettringite precipitation at 20 and 85°C. Simulation of internal sulfate attack was performed at a local scale (a hydrated cement grain). An initial inhomogeneity can lead, after a thermal curing at 85°C, to ettringite precipitation in zones originally free from ettringite. This new-formed ettringite could be the origin of the expansions.

Barbarulo, Remi

389

Modeling of Sulfate Double-salts in Nuclear Wastes  

SciTech Connect

Due to limited tank space at Hanford and Savannah River, the liquid nuclear wastes or supernatants have been concentrated in evaporators to remove excess water prior to the hot solutions being transferred to underground storage tanks. As the waste solutions cooled, the salts in the waste exceeded the associated solubility limits and precipitated in the form of saltcakes. The initial step in the remediation of these saltcakes is a rehydration process called saltcake dissolution. At Hanford, dissolution experiments have been conducted on small saltcake samples from five tanks. Modeling of these experimental results, using the Environmental Simulation Program (ESP), are being performed at the Diagnostic Instrumentation and Analysis Laboratory (DIAL) at Mississippi State University. The River Protection Project (RPP) at Hanford will use these experimental and theoretical results to determine the amount of water that will be needed for its dissolution and retrieval operations. A comprehensive effort by the RPP and the Tank Focus Area continues to validate and improve the ESP and its databases for this application. The initial effort focused on the sodium, fluoride, and phosphate system due to its role in the formation of pipeline plugs. In FY 1999, an evaluation of the ESP predictions for sodium fluoride, trisodium phosphate dodecahydrate, and natrophosphate clearly indicated that improvements to the Public database of the ESP were needed. One of the improvements identified was double salts. The inability of any equilibrium thermodynamic model to properly account for double salts in the system can result in errors in the predicted solid-liquid equilibria (SLE) of species in the system. The ESP code is evaluated by comparison with experimental data where possible. However, data does not cover the range of component concentrations and temperatures found in many tank wastes. Therefore, comparison of ESP with another code is desirable, and may illuminate problems with both. For this purpose, the SOLGASMIX code was used in conjunction with a small private database developed at ORNL. This code calculates thermodynamic equilibria through minimization of Gibbs Energy, and utilizes the Pitzer model for activity coefficients. The sodium nitrate-sulfate double salt and the sodium fluoride-sulfate double salt were selected for the FY 2000 validation study of ESP. Even though ESP does not include the sulfate-nitrate double salt, this study found that this omission does not appear to be a major consequence. In this case, the solubility predictions with and without the sulfate-nitrate double salt are comparable. In contrast, even though the sulfate-fluoride double salt is included within the ESP databank, comparison to previous experimental results indicates that ESP underestimates solubility. Thus, the prediction for the sulfate-fluoride system needs to be improved. A main consequence of the inability to accurately predict the SLE of double salts is its impact on the predicted ionic strength of the solution. The ionic strength has been observed to be an important factor in the formation of pipeline plugs. To improve the ESP prediction, solubility tests on the sulfate-fluoride system are underway at DIAL, and these experimental results will be incorporated into the Public database by OLI System, Inc. Preliminary ESP simulations also indicated difficulties with the SLE prediction for anhydrous sodium sulfate. The Public database for the ESP does not include fundamental parameters for this solid in mixed solutions below 32.4 C. The limitation, in the range of anhydrous sodium sulfate, leads to convergence problems in ESP and to inaccurate predictions of solubility near the invariant point when sodium sulfate decahydrate and other salts, such as sodium nitrate, were present. These difficulties were partially corrected through the use of an additional database. In conclusion, these results indicate the need for experimental data at temperatures above 25 C and in solutions containing both nitrate and hydroxide. Furthermore, the validation and do

Toghiani, B.

2000-10-30

390

Method for magnesium sulfate recovery  

DOEpatents

A method of obtaining magnesium sulfate substantially free from radioactive uranium from a slag containing the same and having a radioactivity level of at least about 7000 pCi/gm. The slag is ground to a particle size of about 200 microns or less. The ground slag is then contacted with a concentrated sulfuric acid under certain prescribed conditions to produce a liquid product and a solid product. The particulate solid product and a minor amount of the liquid is then treated to produce a solid residue consisting essentially of magnesium sulfate substantially free of uranium and having a residual radioactivity level of less than 1000 pCi/gm. In accordance with the preferred embodiment of the invention, a catalyst and an oxidizing agent are used during the initial acid treatment and a final solid residue has a radioactivity level of less than about 50 pCi/gm.

Gay, Richard L. (Canoga Park, CA); Grantham, LeRoy F. (Calabasas, CA)

1987-01-01

391

Method for magnesium sulfate recovery  

DOEpatents

A method is described for obtaining magnesium sulfate substantially free from radioactive uranium from a slag containing the same and having a radioactivity level of at least about 7,000 pCi/gm. The slag is ground to a particle size of about 200 microns or less. The ground slag is then contacted with a concentrated sulfuric acid under certain prescribed conditions to produce a liquid product and a solid product. The particulate solid product and a minor amount of the liquid is then treated to produce a solid residue consisting essentially of magnesium sulfate substantially free of uranium and having a residual radioactivity level of less than 1,000 pCi/gm. In accordance with the preferred embodiment of the invention, a catalyst and an oxidizing agent are used during the initial acid treatment and a final solid residue has a radioactivity level of less than about 50 pCi/gm.

Gay, R.L.; Grantham, L.F.

1987-08-25

392

Sulfates on Mars: Indicators of Aqueous Processes  

NASA Technical Reports Server (NTRS)

Recent analyses by MER instruments at Meridiani Planum and Gusev crater and the OMEGA instrument on Mars Express have provided detailed information about the presence of sulfates on Mars [1,2,3]. We are evaluating these recent data in an integrated multi-disciplinary study of visible-near-infrared, mid-IR and Mossbauer spectra of several sulfate minerals and sulfate-rich analog sites. Our analyses suggest that hydrated iron sulfates may account for features observed in Mossbauer and mid-IR spectra of Martian soils [4]. The sulfate minerals kieserite, gypsum and other hydrated sulfates have been identified in OMEGA spectra in the layered terrains in Valles Marineris and Terra Meridiani [2]. These recent discoveries emphasize the importance of studying sulfate minerals as tracers of aqueous processes. The sulfate-rich rock outcrops observed in Meridiani Planum may have formed in an acidic environment similar to acid rock drainage environments on Earth [5]. Because microorganisms typically are involved in the oxidation of sulfides to sulfates in terrestrial sites, sulfate-rich rock outcrops on Mars may be a good location to search for evidence of past life on that planet. Whether or not life evolved on Mars, following the trail of sulfate minerals will lead to a better understanding of aqueous processes and chemical weathering.

Bishop, Janice L.; Lane, Melissa D.; Dyar, M. Darby; Brown, Adrian J.

2006-01-01

393

Optical, mechanical, and thermal properties of barium borate  

SciTech Connect

We report measurements of all the material constants necessary to fully characterize barium borate as a nonlinear optical material. All data was taken on crystals supplied by Professor Chuangtien Chen, Fuzhou, People's Republic of China. We have determined the crystal structure, the optical absorption, the refractive indices from the UV to the near IR, the thermo-optic coefficients, the nonlinear optical or coefficients, the resistance to laser damage, the elastic constants, the thermal expansion, thermal conductivity and dielectric constants, and the fracture toughness. This data is used to evaluate barium borate for a variety of applications. We find that, in general, barium borate has a low acceptance angle, and that despite its higher optical nonlinearity, it is therefore not significantly more efficient than other commonly available materials, except in the UV below 250 nm. On the other hand, it has a high damage threshold, it is physically robust, it has good UV and IR transparency, and it has excellent average power capability. It permits deep UV generation, and has great potential for generating tunable visible and IR light as an optical parametric amplifier.

Eimerl, D.; Davis, L.; Velsko, S.; Graham, E.K.; Zalkin, A.

1987-09-01

394

Structure and multiferroic properties of barium hexaferrite ceramics  

NASA Astrophysics Data System (ADS)

Simultaneous occurrence of large ferroelectricity and strong ferromagnetism have been observed in barium hexaferrite ceramics. Barium hexaferrite (BaFe12O19) powders with hexagonal crystal structure were successfully synthesized in a polymer precursor method using barium acetate and ferric acetylacetonate as the precursors. The powders were pressed into pellets which were sintered into ceramics at 1200 °C and 1300 °C for 1 h. The structure and morphology of the ceramics were examined using X-ray diffraction and field emission scanning electron microscopy. Large spontaneous polarization was observed in the BaFe12O19 ceramics at room temperature, revealing a clear ferroelectric hysteresis loop. The maximum remanent polarization of the BaFe12O19 ceramic was estimated approximately 11.8 ?C cm-2. The FeO6 octahedron in its perovskite-like hexagonal unit cell and the shift of Fe3+ off the center of octahedron are suggested to be the origin of the polarization in BaFe12O19. The BaFe12O19 ceramics also showed strong ferromagnetism at room temperature.

Tan, Guolong; Chen, Xiuna

2013-02-01

395

Patch testing with neomycin sulfate.  

PubMed

The recommended patch test concentration of neomycin sulfate is 20% in petrolatum applied occluded for 48 h (2 days [D]). In the current study, the efficiency of such a test is compared to results with other techniques using lower allergen dose than obtained by approximately 20 microl of the 20% substance. Efficiency of petrolatum and demineralized water as vehicles are compared. 16 neomycin-sulfate positive subjects were retested with serial doses ranging from 0.4 to 0.0085 mg/cm2 neomycin sulfate in cellulose printed on polyester squares and applied by both tapes and plastic foils. Additionally, tests were performed with the 20% petrolatum substance in Finn Chambers. Tests containing the 20% substance in petrolatum and in water were applied directly with transparent foils. Readings ranged from 3 to 264 h (11D) following applications. Results show that foil applications of a polyester square dose, that is 7% of the dose obtained with the 20% substance, distinguished between perfusion of subjects who were visually positive and not with any test in the study. With the same test technique and visual assessments, 2 subjects were false-negative but developed doubtful test responses with the Finn Chambers. PMID:11016671

Bjarnason, B; Flosadóttir, E

2000-11-01

396

Changing Hafnium Speciation in Aqueous Sulfate Solutions: A High-Energy X-ray Scattering Study.  

PubMed

The relationship of solution speciation and the structures of corresponding precipitates is examined for an aqueous Hf(4+) sulfate series. High-energy X-ray scattering (HEXS) and Raman spectroscopy data are used to probe atomic correlations in solutions. Hf(4+) in acidic perchlorate solution shows no evidence of a mononuclear metal species but instead has a peak in the pair-distribution function (PDF), generated from the HEXS data, at 3.55 Å, indicating Hf(4+)-Hf(4+) solution correlations. The peak intensity is consistent with clusters that are, on average, larger than the tetramic unit [M4(OH)8(H2O)16](8+) usually attributed to Zr(4+) and Hf(4+) solution speciation under these conditions. Addition of sulfate results in a breakup of hydroxo-bridged oligomers into sulfate-capped dimers and, for higher concentrations, Hf-sulfate monomers. The bidentate coordination mode of sulfate dominates the dissolved precursors, although it is not found in the structure of the final crystallized product, which instead is comprised of bridging-bidentate sulfate ligation. Neither the PDF patterns nor the Raman spectra show any evidence of the larger oligomers, such as the octadecameric metal clusters, found in similar Zr(4+) solutions. The oligomeric units found in solution provide insights into possible assembly routes for crystallization. In addition to expanding our understanding of synthesis science this study also reveals differences in the aqueous chemistries between Hf and Zr, two elements with ostensibly very similar chemical behavior. PMID:24871556

Kalaji, Ali; Skanthakumar, S; Kanatzidis, Mercouri G; Mitchell, John F; Soderholm, L

2014-06-16

397

The rates of sea salt sulfatization in the atmosphere and surface snow of inland Antarctica  

NASA Astrophysics Data System (ADS)

Most of the aerosol particles present in the surface snow and ice of inland Antarctica come from primary sea salt (sodium chloride) and marine biological activity (methansulfonic and sulfuric acids). Melted water from surface snow, firn, and Holocene ice contains mainly sodium, chloride, and sulfate ions. Although it is well known that sea salt aerosols react rapidly with sulfuric acid, a process known as sulfatization, it is not known when this process takes place. In this research we undertake to measure the proportion of sea salt aerosols that undergo sulfatization in the atmosphere and surface snow, as opposed to deeper ice, in order to understand the suitability of sea salt aerosols as a proxy for past climates in deep ice cores. We directly measure the sulfatization rates in recently fallen snow (0-4 m in depth) collected at the Dome Fuji station, using X-ray dispersion spectroscopy to determine the constituent elements of soluble particles and computing the molar ratios of sodium chloride and sodium sulfate. We estimate that about 90% of the initial sea salt aerosols sulfatize as they are taken up by precipitation over Dome Fuji or in the snowpack within one year after being deposited on the ice sheet.

Iizuka, Yoshinori; Tsuchimoto, Akira; Hoshina, Yu; Sakurai, Toshimitsu; Hansson, Margareta; Karlin, TorbjöRn; Fujita, Koji; Nakazawa, Fumio; Motoyama, Hideaki; Fujita, Shuji

2012-02-01

398

Sulfated polysaccharides purified from two species of padina improve collagen and epidermis formation in the rat.  

PubMed

Sulfated polysaccharides have shown promising effects on wound healing processes along with many other biological activities. The sulfated polysaccharides extracted from two algae species habitats in Persian Gulf were studied in vivo for their effects on collagen formation and epidermal regeneration. The polysaccharides were purified from aqueous extracts of P. tetrastromatica and P. boergesenii using CaCl2 and ethanol precipitation. The sulfate content of each polysaccharide was determined. Two identical wounds (either burn or excision) were made on the back of 4 groups of male Wistar rats (10 rats per group) under anesthesia. The algal polysaccharide ointments (2%) were applied twice daily on one side and the other wound was treated with Eucerin (as control). The rats were sacrificed on day 7 or 14, and then the wound samples were examined for epidermal thickness by light microscope. Furthermore, hydroxyproline content (as a marker of collagen formation) was spectro-photometrically measured. The polysaccharides purified from P. boergesenii had higher sulfate content (32.6±1%) compared to P. tetrastromatica (19±1%). Both algal polysaccharides showed some improvements in collagen formation (hydroxyproline content) and epidermal thickness in both wound models compared to the vehicle. The sulfated polysaccharides purified from P. tetrastromatica and P. boergesenii seaweeds are able to induce collagen formation and epidermal regeneration in the two wound models. The superior healing properties of P. boergesenii polysaccharides might be correlated to its higher sulfate content. Both algal polysaccharides are good candidates for wound healing clinical trials. PMID:24551807

Kordjazi, Moazameh; Shabanpour, Bahareh; Zabihi, Ebrahim; Faramarzi, Mohammad Ali; Feizi, Farideh; Ahmadi Gavlighi, Hassan; Feghhi, Mohammad Amin; Hosseini, Seyed Abbas

2013-01-01

399

Coral barium incorporation: implications for proxy applications  

NASA Astrophysics Data System (ADS)

Coral Ba/Ca ratios have been proposed as proxies for various environmental variables including sediment loading, upwelling and groundwater input. Two assumptions that underpin the application of Ba/Ca ratios as an environmental proxy is 2) that corals take up Ba/Ca in concentrations proportional to seawater concentrations and 1) that the specified forcing mechanism influences seawater [Ba]. Here we present data from laboratory experiments that demonstrates corals reared in a range of seawater [Ba] linearly incorporate this signature in their skeletal Ba/Ca ratios. Observed coral Ba/Ca perturbations above baseline typically range from 5-15 ?mol/mol which is ~100-500% increase over baseline. Other factors known to influence coral Ba/Ca include the temperature dependence on the partition coefficient and mass fraction aragonite precipitated by the coral which may be linked to calcification rate. In our experiments, calcification rate increased with temperature, thus the observed coral partition coefficient is the net effect of temperature (Ba/Ca increase at lower temperature) and calcification rate (Ba/Ca increase at higher temperature). We observed that the partition coefficient for reared coral Ba/Ca increased 20% 27.7 to 22.5 C, much less than observed Ba/Ca perturbations. Thus we predict that seawater [Ba] drives coral Ba/Ca signals in many locations. We present a model framework to calculate the expected contribution from sediment input, upwelling and groundwater discharge that is needed to produce this signature in corals growing in receiving waters. Finally we apply this model to a coral record from the Yucatan Peninsula, Mexico, recording groundwater discharge to the coastal ocean.

Gonneea, M. E.; Cohen, A. L.; Charette, M. A.

2012-12-01

400

Rheology of Tetraphenylborate Precipitate Slurry.  

National Technical Information Service (NTIS)

The rheological properties of tetraphenylborate precipitate slurry were determined. This nonradioactive slurry simulates the radioactive tetraphenylborate precipitate generated at the Savannah River Plant by the In-Tank Precipitation Process. The data obt...

I. D. Goren H. D. Martin M. A. McLain

1985-01-01

401

Reduced sulfation of chondroitin sulfate but not heparan sulfate in kidneys of diabetic db/db mice.  

PubMed

Heparan sulfate proteoglycans are hypothesized to contribute to the filtration barrier in kidney glomeruli and the glycocalyx of endothelial cells. To investigate potential changes in proteoglycans in diabetic kidney, we isolated glycosaminoglycans from kidney cortex from healthy db/+ and diabetic db/db mice. Disaccharide analysis of chondroitin sulfate revealed a significant decrease in the 4-O-sulfated disaccharides (D0a4) from 65% to 40%, whereas 6-O-sulfated disaccharides (D0a6) were reduced from 11% to 6%, with a corresponding increase in unsulfated disaccharides. In contrast, no structural differences were observed in heparan sulfate. Furthermore, no difference was found in the molar amount of glycosaminoglycans, or in the ratio of hyaluronan/heparan sulfate/chondroitin sulfate. Immunohistochemical staining for the heparan sulfate proteoglycan perlecan was similar in both types of material but reduced staining of 4-O-sulfated chondroitin and dermatan was observed in kidney sections from diabetic mice. In support of this, using qRT-PCR, a 53.5% decrease in the expression level of Chst-11 (chondroitin 4-O sulfotransferase) was demonstrated in diabetic kidney. These results suggest that changes in the sulfation of chondroitin need to be addressed in future studies on proteoglycans and kidney function in diabetes. PMID:23757342

Reine, Trine M; Grøndahl, Frøy; Jenssen, Trond G; Hadler-Olsen, Elin; Prydz, Kristian; Kolset, Svein O

2013-08-01

402

Barium, Equatorial High Productivity, and the Northward Wandering of the Indian Continent  

NASA Astrophysics Data System (ADS)

High concentrations of biologically precipitated barite characterize the deep-sea sediments underlying the equatorial high-productivity belt of the Indian Ocean. By studying the barium distribution in five Deep Sea Drilling Project cores (213-217), drilled in the eastern Indian Ocean north of and below the present high-productivity zone, it is possible to determine the times when the different coring sites passed beneath the zone. From this information, net northward spreading rates of the Indian plate can be deduced. The results suggest that northward movement was very rapid during the early and middle Paleogene, slow during the mid-Cenozoic, and then rapid again from the Late Miocene onwards. The Late Miocene revitalization of active seafloor spreading south of the Indian continent coincides with the main phase of the Himalayan uplift. Supplemental tables are availablewith entire article on microfiche. Orderfrom American Geophysical Union, 2000Florida Avenue, N. W., Washington, D. C.,20009. Document P86-002; $2.00. Paymentmust accompany order.

Schmitz, Birger

1987-02-01

403

Crystallization behavior of a barium titanate tellurite glass doped with Eu3+ and Er3+  

NASA Astrophysics Data System (ADS)

The main objective of this work has been to investigate the crystallization behavior of the glass composition 70TeO2-15BaO-15TiO2 doped with Eu3+ and Er3+ in order to check the possibility of obtaining transparent glass-ceramics containing rare earth-doped BaTiO3 nanocrystals. Glass samples with the ternary composition 70TeO2-15BaO-15TiO2 were synthesized by the melt-quenching method and doped with 0.1% of Eu3+ and Er3+. Thermal properties were investigated by DTA and heat-treatments were applied between Tg and Tx to induce the controlled crystallization of these glasses. One-step and two-step heat treatments were tested and the final glass-ceramics characterized by X-ray diffraction and UV-Vis absorption. It has been shown that transparent glass-ceramics can be obtained after heat-treatment but barium titanate BaTiO3 is hardly precipitated without coprecipitation of another crystalline phase identified as an isostructure of lanthanum tellurate. In addition, the crystalline volume fraction is relatively small in these transparent samples. Finally, Gold doping has been shown to be very effective to promote a volume nucleation and preferential crystallization of BaTiO3 over the other crystalline phases.

Ferreira, Elivelton Alves; Cassanjes, Fábia Castro; Poirier, Gael

2013-04-01

404

Monohydrated Sulfates in Aurorae Chaos  

NASA Technical Reports Server (NTRS)

This image of sulfate-containing deposits in Aurorae Chaos was taken by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) at 0653 UTC (2:53 a.m. EDT) on June 10, 2007, near 7.5 degrees south latitude, 327.25 degrees east longitude. CRISM's image was taken in 544 colors covering 0.36-3.92 micrometers, and shows features as small as 40 meters (132 feet) across. The region covered is roughly 12 kilometers (7.5 miles) wide at its narrowest point.

Aurorae Chaos lies east of the Valles Marineris canyon system. Its western edge extends toward Capri and Eos Chasmata, while its eastern edge connects with Aureum Chaos. Some 750 kilometers (466 miles) wide, Aurorae Chaos is most likely the result of collapsed surface material that settled when subsurface ice or water was released.

The top panel in the montage above shows the location of the CRISM image on a mosaic taken by the Mars Odyssey spacecraft's Thermal Emission Imaging System (THEMIS). The CRISM data covers an area featuring several knobs of erosion-resistant material at one end of what appears to be a large teardrop shaped plateau. Similar plateaus occur throughout the interior of Valles Marineris, and they are formed of younger, typically layered rocks that post-date formation of the canyon system. Many of the deposits contain sulfate-rich layers, hinting at ancient saltwater.

The center left image, an infrared false color image, reveals a swath of light-colored material draped over the knobs. The center right image unveils the mineralogical composition of the area, with yellow representing monohydrated sulfates (sulfates with one water molecule incorporated into each molecule of the mineral).

The lower two images are renderings of data draped over topography with 5 times vertical exaggeration. These images provide a view of the topography and reveal how the monohydrated sulfate-containing deposits drape over the knobs and also an outcrop in lower-elevation parts of the plateau.

CRISM is one of six science instruments on NASA's Mars Reconnaissance Orbiter. Led by The Johns Hopkins University Applied Physics Laboratory, Laurel, Md., the CRISM team includes expertise from universities, government agencies and small businesses in the United States and abroad. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Mars Reconnaissance Orbiter and the Mars Science Laboratory for NASA's Science Mission Directorate, Washington. Lockheed Martin Space Systems, Denver, built the orbiter.

2008-01-01

405

Chemisorption And Precipitation Reactions  

EPA Science Inventory

The transport and bioavailability of chemical components within soils is, in part, controlled by partitioning between solids and solution. General terms used to describe these partitioning reactions include chemisorption and precipitation. Chemisorption is inclusive of the suit...

406

Precipitation Estimates for Hydroelectricity  

NASA Technical Reports Server (NTRS)

Hydroelectric plants require precise and timely estimates of rain, snow and other hydrometeors for operations. However, it is far from being a trivial task to measure and predict precipitation. This paper presents the linkages between precipitation science and hydroelectricity, and in doing so it provides insight into current research directions that are relevant for this renewable energy. Methods described include radars, disdrometers, satellites and numerical models. Two recent advances that have the potential of being highly beneficial for hydropower operations are featured: the Global Precipitation Measuring (GPM) mission, which represents an important leap forward in precipitation observations from space, and high performance computing (HPC) and grid technology, that allows building ensembles of numerical weather and climate models.

Tapiador, Francisco J.; Hou, Arthur Y.; de Castro, Manuel; Checa, Ramiro; Cuartero, Fernando; Barros, Ana P.

2011-01-01

407

Porphyria Precipitated by Fasting.  

National Technical Information Service (NTIS)

Acute intermittent porphyria is associated with an increase of the rate controlling enzyme of porphyrin biosynthesis, delta-aminolevulinic acid synthetase. Several chemotherapeutic agents may induce a marked increase of this synthetase and precipitate the...

K. B. Knudsen M. Sparberg F. Lecocq

1968-01-01

408

Global Precipitation Measurement Update.  

National Technical Information Service (NTIS)

Global Precipitation Measurement (GPM) is an international cooperative program whose objectives are to (a) increase understanding of rainfall processes, and (b) make frequent rainfall measurements on a global basis. The National Aeronautics and Space Admi...

G. M. Flaming

2005-01-01

409

Diel cycles in dissolved barium, lead, iron, vanadium, and nitrite in a stream draining a former zinc smelter site near Hegeler, Illinois  

USGS Publications Warehouse

Diel variations in the concentrations of a number of constituents have the potential to substantially affect the appropriate sampling regimen in acidic streams. Samples taken once during the course of the day cannot adequately reflect diel variations in water quality and may result in an inaccurate understanding of biogeochemical processes, ecological conditions, and of the threat posed by the water to human health and the associated wildlife. Surface water and groundwater affected by acid drainage were sampled every 60 to 90. min over a 48-hour period at a former zinc smelter known as the Hegeler Zinc Superfund Site, near Hegeler, Illinois. Diel variations related to water quality in the aquifer were not observed in groundwater. Diel variations were observed in the temperature, pH, and concentration of dissolved oxygen, nitrite, barium, iron, lead, vanadium, and possibly uranium in surface water. Temperature, dissolved oxygen, nitrite, barium, lead, and uranium generally attained maximum values during the afternoon and minimum values during the night. Iron, vanadium, and pH generally attained minimum values during the afternoon and maximum values during the night. Concentrations of dissolved oxygen were affected by the intensity of photosynthetic activity and respiration, which are dependent upon insolation. Nitrite, an intermediary in many nitrogen reactions, may have been formed by the oxidation of ammonium by dissolved oxygen and converted to other nitrogen species as part of the decomposition of organic matter. The timing of the pH cycles was distinctly different from the cycles found in Midwestern alkaline streams and likely was the result of the photoreduction of Fe3+ to Fe 2+ and variations in the intensity of precipitation of hydrous ferric oxide minerals. Diel cycles of iron and vanadium also were primarily the result of variations in the intensity of precipitation of hydrous ferric oxide minerals. The diel variation in the concentrations of lead, uranium, and barium may have been affected by competition with Fe+2 for sorption sites on hydrous ferric oxide minerals. ?? 2010.

Kay, R. T.; Groschen, G. E.; Cygan, G.; Dupre, David, H. , D. H.

2011-01-01

410

Precipitation and Dissolution Potentials  

Microsoft Academic Search

Precipitation and dissolution potentials for KCl, NaCl, BaCl2, and NH4Cl have been measured with a Lindemann electrometer both in air as well as in nitrogen. The values in the latter case are lower. The electrode on which precipitation and dissolution takes place is found to be negative. The available evidence shows that static potential is developed. In order to assess

R. P. Rastogi; R. D. Shukla

1970-01-01

411

Electron Precipitation Pulsations  

Microsoft Academic Search

When high-frequency wave turbulence is present, low-frequency micropulsations can strongly modulate the high-frequency wave amplitudes, leading to finite amplitude pulsations in the loss rate of energetic electrons from the magnetosphere (micropulsation amplitude is small). An extremely idealized model suggests that the precipitation modulation depends exponentially on the micropulsation amplitude, when the micropulsation period is less than the electron precipitation lifetime.

F. V. Coroniti; C. F. Kennel

1970-01-01

412

Effect of glutathione depletion on sulfate activation and sulfate ester formation in rats.  

PubMed

Sulfation of organic compounds requires activation of inorganic sulfate via formation of adenosine 3'-phosphate 5'-phosphosulfate (PAPS). Inorganic sulfate can be formed by sulfoxidation of cysteine, which can be derived from GSH. Thus, a decrease in hepatic GSH may impair formation of inorganic sulfate, the synthesis of PAPS, and the sulfation of chemicals. This hypothesis was tested by investigating the effect of GSH depletion on the levels of inorganic sulfate in serum and of PAPS in liver, and on the capacity to form the sulfate conjugate of harmol in rats. Phorone (2 mmol/kg, i.p.) decreased hepatic GSH (97%), serum inorganic sulfate (63%), and hepatic PAPS (48%). Diethyl maleate and vinylidene chloride (6 mmol/kg, each, i.p.) were less effective than phorone in decreasing GSH in liver and inorganic sulfate in serum, and they did not alter hepatic PAPS levels. Three hours after phorone treatment, the nadir of hepatic PAPS concentration, harmol was injected in order to assess sulfation in vivo. After administration of harmol (100 and 300 mumol/kg, i.v.), less harmol sulfate and more harmol glucuronide were found in the serum of phorone-treated rats as compared to control rats. At the higher dosage of harmol, phorone reduced the biliary excretion of harmol sulfate while increasing the biliary excretion of harmol glucuronide. These results indicate that severe GSH depletion decreases PAPS formation and sulfation of chemicals. However, an increase in glucuronidation may compensate for the impaired sulfation. PMID:3196355

Gregus, Z; White, C; Howell, S; Klaassen, C D

1988-11-15

413

Processes and fluxes during the initial stage of acid sulfate soil formation  

NASA Astrophysics Data System (ADS)

Acid sulfate soils occur over a wide range of climatic zones, mainly in coastal landscapes. In these soils, the release of sulfuric acid by the oxidation of pyrite generates a very acidic environment (e.g., DENT and PONS, 1995, PONS, 1973). Two major types of acid sulfate soils can be distinguished: In actual acid sulfate soils, the initially contained pyrite was at least partly oxidized. This resulted in a severe acidification of the soil. Potential acid sulfate soils are generally unoxidized and contain large amounts of pyrite. Upon oxidation, these soils will turn into actual acid sulfate soils. By excavation or lowering of the groundwater table, potential acid sulfate soils can be exposed to atmospheric oxygen. During oxidation the pH drops sharply to values below pH 4. This acidification promotes the release of various metals, e.g., alumina, iron and heavy metals. Additionally, large quantities of sulfate are released. In order to assess the effects of disturbances of potential acid sulfate soils, for example by excavations during construction works, several large scale column experiments were conducted with various types of potential acid sulfate soils from Northern Germany. In these experiments, the oxidation and initial profile development of pyritic fen peats and thionic fluvisols were studied over a period of 14 months. The study focused on leaching and the translocation of various metals in the soil profile. To study mobilization processes, element fluxes and the progress of acidification, soil water and leachate were analyzed for total element concentrations. Furthermore, several redox-sensitive parameters, e.g., Fe2+ and sulfide, were measured and changes to the initial solid phase composition were analyzed. Chemical equilibria calculations of the soil water were used to gain insights into precipitation processes of secondary products of pyrite oxidation and leaching products. The results of this study will support the assessment of risks deriving from acid sulfate soils. Furthermore, these experiments can serve as a model for the initial stage of naturally occurring acid sulfate soil formation. Thus, the results will provide a base for the interpretation of element distribution in the solid phase of natural acid sulfate soil profiles. References DENT, D. L. and PONS, L. J. (1995) A world perspective on acid sulphate soils. Geoderma 67, 263-276. PONS, L. J. (1973) Outline of genesis, characteristics, classification and improvement of acid sulphate soils. In Acid Sulphate Soils - Proceedings of the International Symposium on Acid Sulphate Soils - I Introductory Papers and Bibliography (ed. H. Dost). pp. 3-27

Gröger, J.; Hamer, K.; Schulz, H. D.

2009-04-01

414

A review of the health impacts of barium from natural and anthropogenic exposure.  

PubMed

There is an increasing public awareness of the relatively new and expanded industrial barium uses which are potential sources of human exposure (e.g., a shale gas development that causes an increased awareness of environmental exposures to barium). However, absorption of barium in exposed humans and a full spectrum of its health effects, especially among chronically exposed to moderate and low doses of barium populations, remain unclear. We suggest a systematic literature review (from 1875 to 2014) on environmental distribution of barium, its bioaccumulation, and potential and proven health impacts (in animal models and humans) to provide the information that can be used for optimization of future experimental and epidemiological studies and developing of mitigative and preventive strategies to minimize negative health effects in exposed populations. The potential health effects of barium exposure are largely based on animal studies, while epidemiological data for humans, specifically for chronic low-level exposures, are sparse. The reported health effects include cardiovascular and kidney diseases, metabolic, neurological, and mental disorders. Age, race, dietary patterns, behavioral risks (e.g., smoking), use of medications (those that interfere with absorbed barium in human organism), and specific physiological status (e.g., pregnancy) can modify barium effects on human health. Identifying, evaluating, and predicting the health effects of chronic low-level and moderate-level barium exposures in humans is challenging: Future research is needed to develop an understanding of barium bioaccumulation in order to mitigate its potential health impacts in various exposured populations. Further, while occupationally exposed at-risk populations exist, it is also important to identify potentially vulnerable subgroups among non-occupationally exposed populations (e.g., elderly, pregnant women, children) who are at higher risk of barium exposure from drinking water and food. PMID:24844320

Kravchenko, Julia; Darrah, Thomas H; Miller, Richard K; Lyerly, H Kim; Vengosh, Avner

2014-08-01

415

Inhibition of synthesis of heparan sulfate by selenate: Possible dependence on sulfation for chain polymerization  

SciTech Connect

Selenate, a sulfation inhibitor, blocks the synthesis of heparan sulfate and chondroitin sulfate by cultured endothelial cells. In contrast, selenate does not affect the production of hyaluronic acid, a nonsulfated glycosaminoglycan. No differences in molecular weight, ({sup 3}H)glucosamine/({sup 35}S)sulfuric acid ratios, or disaccharide composition were observed when the heparan sulfate synthesized by selenate-treated cells was compared with that of control cells. The absence of undersulfated chains in preparations from cultures exposed to selenate supports the concept that, in the intact cell, the polymerization of heparan sulfate might be dependent on the sulfation of the saccharide units added to the growing glycosaminoglycan chain.

Dietrich, C.P.; Nader, H.B. (Paulist School of Medicine, Sao Paulo (Brazil)); Buonassisi, V.; Colburn, P. (W. Alton Jones Cell Science Center, Lake Placid, NY (USA))

1988-01-01

416

Method for in-situ prevention of stable barium carbonate formation in high T[sub c] ceramic superconductor including the use of iodine or an iodine c  

SciTech Connect

This patent describes a method of making a pre-ceramic resinous material capable of being converted into a ceramic semiconductor material substantially free from stable barium carbonate and having the general composition RR[prime][sub 2]Cu[sub 3]O[sub 7[minus]x] where R is a rare earth metal, R[prime] is an alkaline earth metal, and x is from 0 to 0.5. It comprises: refluxing stoichiometric amounts of a first solution comprising a rare earth isopropoxide and an alkaline earth isopropoxide in isopropanol; adding to the first solution a stoichiometric amount of a second solution comprising copper ethylhexanoate in isopropanol; refluxing the first and second solutions to obtain a precipitate; hydrolyzing the precipitate in a quantity of a first solvent comprising water and isopropanol sufficient to substantially dissolve the precipitate into a precipitate solution; adding a third solution comprising an iodine compound in an alcohol to the precipitate solution to form a precursor solution having at least about 1 mole of iodine per mole of rare earth metal; concentrating the precursor solution by removing a sufficient amount of solvents to produce the pre-ceramic resinous material; and adding a second solvent comprising a nonpolar solvent to the pre-ceramic resinous material to obtain a desired viscosity.

Chen, K.C.; Mazdiyasni, K.S.

1992-10-06

417

Precipitation of mixtures of anionic and cationic surfactants; 3: Effect of added nonionic surfactant  

SciTech Connect

The precipitation of an anionic surfactant by a cationic surfactant in the presence of a nonionic surfactant is examined. The precipitation domains for sodium dodecyl sulfate/dodecyl-pyridinium chloride were measured over a wide range of surfactant concentrations as a function of nonylphenol polyethoxylate concentration. Increasing the nonylphenol polyethoxylate concentration decreases the tendency for precipitation to occur. A model for predicting precipitation domains in ternary surfactant mixtures has been developed and verified experimentally. The model allows the nonionic surfactant to affect the precipitation behavior only by lowering the critical micelle concentration of the mixture. Small deviations between theory and experiments along part of the anionic-rich micelle boundary result from adsorption of SDS on the precipitate which gives the microcrystals a negative charge and prevents their growth to a visible size.

Shiau, B.J.; Harwell, J.H.; Scamehorn, J.F. (Univ. of Oklahoma, Norman, OK (United States). Inst. for Applied Surfactant Research)

1994-10-15

418

Interactions between chloride and sulfate or silica removals from wastewater using an advanced lime-aluminum softening process: equilibrium modeling.  

PubMed

Interactions among chloride, sulfate, and silica removals from recycled industrial wastewater using an ultra-high lime with aluminum process (UHLA) were studied. An equilibrium model that is able to accurately predict the chemical behavior and interactions between chloride and sulfate or silica with UHLA at various initial conditions and chemical reagents was developed. X-ray diffraction (XRD) analysis was conducted to identify the precipitated solids formed in the UHLA process. Model predictions indicated that simultaneous removal of sulfate and chloride can be best described by the formation of a solid solution containing calcium chloroaluminate, calcium sulfoaluminate (ettringite), calcium monosulfate, tricalcium hydroxyaluminate, and tetracalcium hydroxyaluminate. However, simultaneous removal of silica and chloride can be best described by precipitation of calcium silicate and calcium aluminosilicate in addition to a solid solution containing calcium chloroaluminate, tricalcium hydroxyaluminate, and tetracalcium hydroxyaluminate. The XRD results indicated the presence of the same solids assumed by the equilibrium model. PMID:17571843

Abdel-Wahab, Ahmed; Batchelor, Bill

2007-05-01

419

The influence of cut off lows on sulfate burdens over the North Atlantic during April, 1987  

SciTech Connect

The authors have presented examples from a modeling study of the development of sulfur burdens over North America, the North Atlantic Ocean and Europe during April, 1987 using observation-derived meteorological data to represent the actual conditions for this period, focusing on the influence of cut-off lows on SO{sub 2} and sulfate column burdens over the North Atlantic Ocean. The analysis demonstrates that these systems can serve either as sources or sinks of sulfate, and that the major factor governing their resulting effect is the position during its formative stages relative to (a) sources of moisture, and (b) sulfur emissions, which regulates the availability of sulfur, cloud liquid water for sulfur oxidation, and the amount of precipitation for sulfate removal produced in the later stages of the life cycle.

Benkovitz, C.M.; Miller, M.A.; Schwartz, S.E.; Kwon, O.U.

2001-01-14

420

Cementation of ILW ion exchange resins: Impact of sulfate ions released by radiolysis on hydrated matrix  

NASA Astrophysics Data System (ADS)

Some of the ion exchange resins used during treatment of spent nuclear fuels are intermediate level radioactive wastes which may be damaged by radiolysis process, releasing sulfate ions directly into the cement-based encapsulating material. This work consists in an experimental study of the resulting sulfate attack on the properties of the hydrated matrix: dimensional stability, mineralogy and microstructure of the samples, as well as variations in the chemical composition of the curing solution, were studied during six months. Three sites of delayed ettringite formation were detected: into the cement matrix near the surface exposed to solution, localized in the interfacial transition zone between cement matrix and resins, or progressively replacing the portlandite that initially fulfilled the cracks of anionic resins. During the experiment period, the ettringite precipitation and the expansion detected were moderate, and did not lead to cracking. The material involved was considered as having a good resistance to sulfate attack.

Frizon, F.; Cau-dit-Coumes, C.

2006-12-01

421

Plasmatic dermatan sulfate and chondroitin sulfate determination in mucopolysaccharidoses.  

PubMed

The evaluation of plasmatic galactosaminoglycans, dermatan sulfate (DS) and chondroitin sulfate (CS) can be helpful in the early identification of MPS patients, also considering that primary storage of one type of GAG can lead to secondary accumulation of other lysosomal substrates. We explore the possibility to determine plasmatic DS and CS in numerous healthy pediatric (and sometimes adult) subjects depending on age and in patients affected by various forms of MPS. A highly sensitive HPLC separation and fluorescence detection was applied for plasma/serum DS and CS determination after a specific enzymatic treatment able to release their constituent disaccharides. DS and CS content decrease significantly with age in controls having high values in the first year (~8 ?g/mL). A highly significant decrease was observed for 1-5-year-old (?-33%) and 5-10-year-old (?-65%) healthy subgroups. No further decrease was determined showing a stabilization after 5 years of age. MPS I Scheie and Hurler patients showed rather similar DS and CS content significantly higher than controls matched for age. Similarly, MPS II, III and IV subjects all presented significantly higher plasmatic DS and CS content compared to healthy subjects matched for age. The same trend was determined for the only patient affected by MPS VI. Plasmatic DS and CS analyzed by the present procedure may be a useful diagnostic and screening marker for various forms of MPS. PMID:23872470

Volpi, Nicola; Maccari, Francesca; Galeotti, Fabio; Zampini, Lucia; Santoro, Lucia; Padella, Lucia; Galeazzi, Tiziana; Gabrielli, Orazio; Coppa, Giovanni V

2013-11-01

422

Low-frequency Electrical Response to Microbial Induced Sulfide Precipitation  

SciTech Connect

We investigated the sensitivity of low-frequency electrical measurements to microbeinduced metal sulfide precipitation. Three identical sand-packed monitoring columns were used; a geochemical column, an electrical column and a control column. In the first experiment, continuous upward flow of nutrients and metals in solution was established in each column. Cells of Desulfovibrio vulgaris (D. vulgaris) were injected into the center of the geochemical and electrical columns. Geochemical sampling and post-experiment destructive analysis showed that microbial induced sulfate reduction led to metal precipitation on bacteria cells, forming motile biominerals. Precipitation initially occurred in the injection zone, followed by chemotactic migration of D. vulgaris and ultimate accumulation around the nutrient source at the column base.

Ntarlagiannis, Dimitrios; Williams, Kenneth H.; Slater, Lee D.; Hubbard, Susan S.

2005-11-19

423

Tubular precipitation and redox gradients on a bubbling template  

PubMed Central

Tubular structures created by precipitation abound in nature, from chimneys at hydrothermal vents to soda straws in caves. Their formation is controlled by chemical gradients within which precipitation occurs, defining a surface that templates the growing structure. We report a self-organized periodic templating mechanism producing tubular structures electrochemically in iron-ammonium-sulfate solutions; iron oxides precipitate on the surface of bubbles that linger at the tube rim and then detach, leaving behind a ring of material. The acid–base and redox gradients spontaneously generated by diffusion of ammonia from the bubble into solution organize radial compositional layering within the tube wall, a mechanism studied on a larger scale by complex Liesegang patterns of iron oxides formed as ammonia diffuses through a gel containing FeSO4. When magnetite forms within the wall, a tube may grow curved in an external magnetic field. Connections with free-boundary problems in speleothem formation are emphasized.

Stone, David A.; Goldstein, Raymond E.

2004-01-01

424

Study of formation and inhibition of barium sulfate deposits in oil fields. Application to the Algerian field Tin Fouye Tabankort.  

National Technical Information Service (NTIS)

The aim of this work is the study of deposition-corrosion phenomena observed in water injection produced by incompatibility of formation water and injected water and research of an inhibitor adapted to specific conditions of the oil deposit of Tin Fouye T...

N. Messaoudene

1990-01-01

425

Long-term retention of /sup 133/Ba in the rat trachea following local administration as barium sulfate particles  

SciTech Connect

Long-term retention of /sup 133/Ba in the trachea from intratracheally administered BaSO/sub 4/ particles was determined by both serial sacrifice and external scanning methods up to 6 months after injection. The amount of /sup 133/Ba retained 1 week after injection in the caudal region of the trachea, where the tip of the cannula had been at injection, was 0.41% of the initial dose. Thereafter the /sup 133/Ba was cleared exponentially with a mean half-time of 88 days, as determined from the autopsy samples. The cranial region of the trachea, including the site of the tracheostomy, contained /sup 133/Ba at 10 times the level in the caudal region 1 week after injection and was cleared with a half-time of 66 days. These clearance rates were confirmed by repeated external scanning over the trachea. The 133Ba was drained to the lymph nodes not only in the thoracic cavity but also in the cervical region, suggesting the possibility of lymphatic drainage from the trachea to the cervical lymph nodes.

Takahashi, S.; Patrick, G.

1987-06-01

426

Endothelial Heparan Sulfate in Angiogenesis  

PubMed Central

Heparan sulfate (HS) is a linear polysaccharide composed of 50–200 glucosamine and uronic acid (glucuronic acid or iduronic acid) disaccharide repeats with epimerization and various sulfation modifications. HS is covalently attached to core proteins to form HS-proteoglycans. Most of the functions of HS-proteoglycans are mediated by their HS moieties. The biosynthesis of HS is initiated by chain polymerization and is followed by stepwise modification reactions, including sulfation and epimerization. These modifications generate ligand-binding sites that modulate cell functions and activities of proteinases and/or proteinase inhibitors. HS is abundantly expressed in developing and mature vasculature, and understanding its roles in vascular biology and related human diseases is an area of intense investigation. In this chapter, we summarize the significant recent advances in our understanding of the roles of HS in developmental and pathological angiogenesis with a major focus on studies using transgenic as well as gene knockout/knockdown models in mice and zebrafish. These studies have revealed that HS critically regulates angiogenesis by playing a proangiogenic role, and this regulatory function critically depends on HS fine structure. The latter is responsible for facilitating cell-surface binding of various proangiogenic growth factors that in turn mediate endothelial growth signaling. In cancer, mouse studies have revealed important roles for endothelial cell-surface HS as well as matrix-associated HS, wherein signaling by multiple growth factors as well as matrix storage of growth factors may be regulated by HS. We also discuss important mediators that may fine-tune such regulation, such as heparanase and sulfatases; and models wherein targeting HS (or core protein) biosynthesis may affect tumor growth and vascularization. Finally, the importance of targeting HS in other human diseases wherein angiogenesis may play pathophysiologic (or even therapeutic) roles is considered.

Fuster, Mark M.; Wang, Lianchun

2013-01-01

427

The action of caffeine on inward barium current through voltage-dependent calcium channels in single rabbit ear artery cells  

Microsoft Academic Search

The effect of caffeine on inward current carried by barium ions through voltage-dependent calcium channels has been investigated in single rabbit ear artery cells using whole-cell voltage-clamp techniques. Caffeine (1 –30 mM) caused a rapid and reversible concentration-dependent blockade of barium current and a related compound, 3-isobutyl-1-methylxanthine (IBMX), was a more potent inhibitor of barium current. Caffeine-induced inhibition of barium

A. D. Hughes; S. Hering; T. B. Bolton

1990-01-01

428

Sulfate reduction in freshwater wetland soils and the effects of sulfate and substrate loading  

SciTech Connect

Elevated sulfate and organic C loadings in freshwater wetlands could stimulate dissimilatory sulfate reduction that oxidizes organic C, produces hydrogen sulfide and alkalinity, and sequesters trace metals. The authors determined the extent of sulfate reduction in two freshwater wetland soils, that is black gum (Nyssa biflona) swamp soils and titi (Cliftonia monophylla) swamp soils, in northern Florida. They also investigated the potential of sulfate reduction in the wetland soils by adding sulfate, organic substrate, and lime. Sulfate reduction was found to be an active process in both swamp soils without any amendment, where the pore water pH was as low as 3.6 and sulfate concentration was as low as 5 mg L{sup {minus}1}. Without amendment, 11 to 14% of organic C was oxidized through sulfate reduction in the swamp soils. Sulfate loading, liming, and substrate addition significantly increased sulfate reduction in the black gum swamp soil, but none of those treatments increase sulfate reduction in the titi swamp soil. The limiting factor for sulfate reduction in the titi swamp soil were likely texture and soil aggregate related properties. The results suggested that wastewater loading may increase sulfate reduction in some freshwater wetlands such as the black swamps while it has no stimulating effect on other wetlands such as the titi swamps.

Feng, J.; Hsieh, Y.P. [Florida A and M Univ., Tallahassee, FL (United States)

1998-07-01

429

Mechanism of sulfate segregation during glass melting  

SciTech Connect

Sulfate retention in glass during the vitrification process can be as low as 1/3 of the solubility limit, or can exceed the solubility limit if suspended in the glass in the form of droplets. This study is focused on the mechanism of incorporating and segregating sodium sulfate during the melting of an alkali-alumino-borosilicate glass batch. Batches were ramp heated at 4°C/min to temperatures ranging from 600°C to 1050°C and fractured for examination. Observation of the melts showed that as the batch temperature increases and the primary oxo-anionic, predominantly nitrate melt decomposes, the sulfate residue accumulates inside gas bubbles and is transported in them to the melt surface, where it remains segregated. The degree of sulfate incorporation into the final glass depends on the relative rates of sulfate dissolution in the borosilicate melt and sulfate lifting inside bubbles.

Hrma, Pavel R.; Vienna, John D.; Ricklefs, Joel S.

2005-02-13

430

Irrigated precipitator for sampling soluble aerosols.  

PubMed

The design and performance of a simple parallel plate, irrigated, precipitator for use in the sampling of soluble aerosols is described. Unifrom surface coverage of 0.044 +/- 0.003 mL/cm2 by the gravity fed collection fluid is provided with a fiberglass mat (Gelman type A/E filter), while a surface washout of approximately 45% occurs in fluid residence time tf = V/q for a collector surface inclination of 40 degrees relative to horizontal. Efficiency tests using laboratory generated DOP aerosols and field tests of sulfate-bearing particles indicate good correlation with the Deutsch equation. Values of V/Q, proportional to the instrument sampling time, representing the ration of collection fluid volume to air flow rate for the present design compare favorably with other available instrumentation. PMID:696624

Forney, L J; Lee, S S; Szurgot, A M

1978-08-01

431

Development of a Fluorescence-Based in-situ Barium Sensor.  

National Technical Information Service (NTIS)

Biogeochemical characteristics render barium a useful tracer of riverine inputs on 10-100 kms spatial scales. Ultimately we seek to determine of barium in seawaters by an in-situ technique. An intermediate step toward achieving that goal is the developmen...

K. K. Falkner

1999-01-01

432

Synthesis and crystal structure of a barium complex with pyruvic acid isonicotinoyl hydrazone  

Microsoft Academic Search

A barium complex with pyruvic acid isonicotinoyl hydrazone (H2L) has been synthesized and its crystal structure was determined by X-ray diffraction analyses. There is one complex unit, Ba(HL)2(H2O), with eight lattice water molecules in the asymmetric unit. The nine-coordinated barium has a distorted, monocapped square antiprism configuration.

Kaibei Yu

1996-01-01

433

Electron microscopy of barium strontium titanate nanostructures in the aluminum oxide matrix  

NASA Astrophysics Data System (ADS)

Electron microscopy has revealed the mechanism of formation of barium strontium titanate nanostructures during crystallization in the bulk of pores of the aluminum matrix. The nanostructures have the form of nanotubes or nanocolumns 100-200 nm in diameter and a few microns long, which are formed by barium strontium titanate crystals 3-100 nm in size.

Zhigalina, O. M.; Vorotilov, K. A.; Kuskova, A. N.; Sigov, A. S.

2009-07-01

434

THE BARIUM FLUORIDEURANIUM TETRAFLUORIDE AND THE STRONTIUM FLUORIDE THORIUM TETRA-FLUORIDE SYSTEM  

Microsoft Academic Search

ined by x-ray diffraction and density- measurements. The tetrafluoride ; dissolves in difluoride to the extent of about 25 M%, the unit-cell constant ; decreasing in the former and increasing in the latter system. Barium and ; strontium fluorides dissolve in barium uranium hexafluoride and strontium thorium ; hexafluoride respectively to the extent of about 20 M % with the

R. W. M. DEye; I. F. Ferguson

1959-01-01

435

Obtaining Monocrystals of Solid Solutions of Barium and Strontium Titanates and Their Dielectric and Optical Properties.  

National Technical Information Service (NTIS)

In this paper monocrystals of solid solutions of barium and strontium titanates are described. The growing of the monocrystals was done in a platinum crucible from a solution of a mixture of barium and strontium titanates in potassium fluoride. The potass...

A. L. Khodakov M. L. Sholokhovich E. G. Fesenko O. P. Kramarov

1968-01-01

436

Investigations of Indium Tin Oxide—Barium Strontium Titanate–Indium Tin Oxide Heterostructure for Tunability  

Microsoft Academic Search

This letter reports for the first time the interesting behavior of the interface between indium tin oxide (ITO) as a high resistive electrode and barium strontium titanate tunable paraelectric thin film material. The interface is consisting of barium strontium titanate (BST) thin film dielectric material sandwiched between two ITO high resistive layers, all are integrated above glass substrate. When dc

Mahmoud Al Ahmad; Ludovic Salvagnac; Dominique Michau; Mario Maglione; Robert Plana

2008-01-01

437

The effect of barium on perceptions of taste intensity and palatability.  

PubMed

Barium may affect the perception of taste intensity and palatability. Such differences are important considerations in the selection of dysphagia assessment strategies and interpretation of results. Eighty healthy women grouped by age (younger, older) and genetic taste status (supertaster, nontaster) rated intensity and palatability for seven tastants prepared in deionized water with and without 40 % w/v barium: noncarbonated and carbonated water, diluted ethanol, and high concentrations of citric acid (sour), sodium chloride (salty), caffeine (bitter), and sucrose (sweet). Mixed-model analyses explored the effects of barium, taster status, and age on perceived taste intensity and acceptability of stimuli. Barium was associated with lower taste intensity ratings for sweet, salty, and bitter tastants, higher taste intensity in carbonated water, and lower palatability in water, sweet, sour, and carbonated water. Older subjects reported lower palatability (all barium samples, sour) and higher taste intensity scores (ethanol, sweet, sour) compared to younger subjects. Supertasters reported higher taste intensity (ethanol, sweet, sour, salty, bitter) and lower palatability (ethanol, salty, bitter) than nontasters. Refusal rates were highest for younger subjects and supertasters, and for barium (regardless of tastant), bitter, and ethanol. Barium suppressed the perceived intensity of some tastes and reduced palatability. These effects are more pronounced in older subjects and supertasters, but younger supertasters are least likely to tolerate trials of barium and strong tastant solutions. PMID:24037100

Dietsch, Angela M; Solomon, Nancy Pearl; Steele, Catriona M; Pelletier, Cathy A

2014-02-01

438

The effect of additives on the co-crystallisation of calcium with barium sulphate  

Microsoft Academic Search

A study has been carried out to ascertain the effect of divalent cations and scale inhibitors on the lattice parameters, crystal size and morphology of barium sulphate. The mineral barite can support up to 6% calcium substitution for barium ions in the crystal lattice. Grahmann (Neues Jahrb. Min. 1 (1920) 1). It is known that the presence of magnesium and

A. J. B. Hennessy; G. M. Graham

2002-01-01

439

Lack of effect of drinking water barium on cardiovascular risk factors  

SciTech Connect

Higher cardiovascular mortality has been associated in a single epidemiological study with higher levels of barium in drinking water. The purpose of this study was to determine whether drinking water barium at levels found in some U.S. communities-alters the known risk factors for cardiovascular disease. Eleven healthy men completed a 10-week dose-response protocol in which diet was controlled. Other aspects of the subjects' lifestyles known to affect cardiac risk factors were controlled, and the barium content (as barium chloride) of the drinking water was varied from 0, to 5 ppm, to 10 ppm. Multiple blood and urine samples, morning and evening blood pressure measurements, and 48-hr electrocardiographic monitoring were performed at each dose of barium. There were no changes in morning or evening systolic or diastolic blood pressures, plasma cholesterol or lipoprotein or apolipoprotein levels, serum potassium or glucose levels, or urine catecholamine levels. There were no arrythmias related to barium exposure detected on continuous electrocardiographic monitoring. A trend was seen toward increased total serum calcium levels with exposure to barium, which was of borderline statistical significance and of doubtful clinical significance. In summary, drinking water barium at levels of 5 and 10 ppm did not appear to affect any of the known modifiable cardiovascular risk factors.

Wones, R.G.; Stadler, B.L.; Frohman, L.A. (Univ. of Cincinnati College of Medicine, OH (USA))

1990-04-01

440

Study of Second Harmonic Generation Coefficients and Ultraviolet Absorption Edge of Barium Borate Crystal.  

National Technical Information Service (NTIS)

Barium borate (beta-BaB2O4) is a new type of non-linear optical crystal. In this paper the authors report one-electron energies and wave functions of barium borate by use of EHMO theory. Both the calculated values of SHG coefficient and ultraviolet absorp...

J. K. Zhu B. Zhang S. H. Liu

1985-01-01

441

Growth and characterization of a new non-linear optical barium strontium borate (BSB) single crystal  

Microsoft Academic Search

The growth of a new inorganic mixed borate of barium strontium borate (BSB) is reported by solution growth technique for the first time. The structure of the grown crystal has been identified by single crystal X-ray diffraction method. The exact percentage of barium and strontium present in the mixed borate crystal system is quantified by atomic absorption spectroscopic analysis. The

K. Prabha; T. Rajesh Kumar; Shi Feng Du; M. Vimalan; A. Dayalan; P. Sagayaraj

2010-01-01

442

Synthesis and properties of barium titanate solid solution thin films deposited on copper substrates  

Microsoft Academic Search

Barium titanate thin films were deposited via chemical solution deposition using a hybrid-chelate chemistry directly on copper foil substrates. A process was developed to crystallize and densify the ferroelectric films at 900°C by using a reductive atmosphere containing nitrogen, hydrogen, water vapor, and oxygen impurities such that film constituents were oxidized to form barium titanate and the foil substrate remained

Jon Fredrick Ihlefeld

2006-01-01

443

Photoemission study of the reactivity of barium towards SiO x thermal films  

Microsoft Academic Search

Barium was deposited at room temperature on a thermal silicon oxide layer and the interfacial reaction was monitored by synchrotron induced photoemission (both core level and valence band). The first step of the growth consists of an interfacial reaction which leads to the formation of an interfacial silicate layer. The next step consists in formation of barium oxide while metallic

T. Genevès; B. Domenichini; L. Imhoff; V. Potin; Z. Li; S. Bourgeois

2011-01-01

444